CN101185571A - Magnetic resonance imaging apparatus - Google Patents

Abstract

A magnetic resonance imaging apparatus includes an acquisition unit which acquires first data in which a tissue of interest has higher signal intensity than a background and second data in which the tissue of interest has lower signal intensity than the background, with regard to images of the same region of the same subject, and a generation unit which generates, on the basis of the first data and the second data, third data in which the contrast of the tissue of interest to the background is higher than those in the first and second data.

Description

MR imaging apparatus

Technical field

The present invention relates to obtain being used for the MR imaging apparatus of the information of medical diagnosis according to the magnetic resonance signal that discharges from subject.

Background technology

MR angiography technology (MR angiography:MRA) is to be the nuclear magnetic resonance method of object with tremulous pulse and vein.In MRA, TOF (the time of fright) method of having used gtadient echo (gradient echo:GRE) method is arranged, used BB (black-blood) method of vessel delineation as high speed spin echo (the Fast spin echo:FSE) method of low signal.SWI (susceptibility-weighted imaging) method (with reference to No. 6501272 description of United States Patent (USP)) of application venous susceptibility effect (susceptibility effect) has been proposed recently.

The TOF method of non-radiography is the representation example of WB (white-blood) method.In the TOF of non-radiography method, utilize to flow into (in-flow) effect, therefore will be depicted as high signal near the inflow fast tremulous pulse of flow velocity partly of layer piece (slab).In the TOF of this non-radiography method, be difficult to depict the sinuous flow part, be difficult to depict the peripheral vessel that passes branch etc. in addition.That is, in the TOF of non-radiography method, the tremulous pulse main body is described.

In addition, under the situation of having made a video recording according to the sequential of T1W system having used normal magnetic contrast medium, owing to being high signal with vessel delineation, institute thinks the WB method.In addition, at this, blood vessel compared with background tissues to be become the MRA of high signal method and is called the WB method widely.

In the BB method, blood vessel is a low signal with respect to surrounding tissue.In the BB method, also depict slow blood flow, correctly depict blood vessel wall.In the BB method, can also depict the sinuous flow part that in the TOF method, is difficult to depict.In the sequential of BB method, utilized the FSE method at first, but because problem of Flame Image Process etc. and almost not popularizing.In the BB method, tremulous pulse and vein all are low signal, but by being provided with the echo time (TE) short, can strengthen tremulous pulse.In addition, using normal magnetic contrast medium according to T2 ^*Under the situation that the sequential of W system is made a video recording, owing to being low signal with vessel delineation, institute thinks the BB method.

In the BB method, surrounding tissue also becomes low signal, therefore is difficult to only extract out distinctively blood vessel.For example in the BB method, be difficult to get rid of the air that causes because of minima projection (minIP).In maximum projection (MIP) etc., also can extract out than the blood vessel that is easier to carry out in the WB method.

In above such existing MRA, WB method and BB method all have merits and demerits, suitably separate use accordingly with purposes.But, in WB method and BB method, all be difficult to clearly depict easily the various structures of blood vessel.

On the other hand, when collecting magnetic resonance signal, the method that makes spin dephasing (dephase), the method that makes spin complex phase (rephase) are arranged.Optionally use this 2 collection methods accordingly with purposes.In addition, according to the magnetic resonance signal of collecting by any means, can both obtain being used for the information of medical diagnosis.

In addition, known to implementing to divide other to handle according to the resulting information of the magnetic resonance signal of collecting by any means, obtain the technology of Useful Information.For example conduct is than T2 ^*Enhancing changes sharper camera method to susceptibility (magnetic susceptibility), proposed the absolute value images that reconstructs according to the magnetic resonance signal of collecting by complex phase is implemented phase place enhancement processing method (with reference to Magn Reson Med 52:612～618,2004).

But the information that obtains according to the magnetic resonance signal of collecting by dephasing or complex phase is limited, for example can't be depicted needed information such as blood vessel well.

According to such situation, require to obtain clearly to express easily the image that blood vessel etc. is paid close attention to the various structures of tissue.

On the other hand, wish to obtain the useful information that can't obtain according to the magnetic resonance signal of collecting separately respectively by dephasing or complex phase.

Summary of the invention

The MR imaging apparatus of first form of the present invention possesses: respectively at the image of the same area of same subject, obtain the unit of obtaining of the signal of the signal of paying close attention to tissue first data higher than background, above-mentioned concern tissue second data lower than background respectively; According to above-mentioned first data and above-mentioned second data, generate the generation unit of above-mentioned concern tissue three data all higher than above-mentioned first and second data with respect to the contrast of background.

The MR imaging apparatus of second form of the present invention possesses: respectively at the image of the same area of same subject, obtain the unit of obtaining of the signal of the signal of paying close attention to tissue first data higher than background, above-mentioned concern tissue second data lower than background respectively; Generate expression and distribute different colours and the generation unit of the 3rd data of synthetic image to the image shown in image shown in above-mentioned first data and above-mentioned second data respectively.

The MR imaging apparatus of the 3rd form of the present invention possesses: at the region-of-interest of subject, carry out the scanning element of carrying out first scanning of data collection, carrying out second scanning of data collection according to the pulse sequence different with above-mentioned first scanning of the signal that is used to obtain above-mentioned blood vessel second view data higher than background parts according to the pulse sequence of the signal that is used to obtain blood vessel first view data higher than background parts; According to above-mentioned first view data and above-mentioned second view data, generate the generation unit of above-mentioned blood vessel three view data all higher than above-mentioned first and second view data with respect to the contrast of background parts.

The MR imaging apparatus of the 4th form of the present invention possesses: at the region-of-interest of subject, carry out the scanning element of carrying out first scanning of data collection, carrying out second scanning of data collection according to the pulse sequence different with above-mentioned first scanning of the signal that is used to obtain above-mentioned blood vessel second view data lower than background parts according to the pulse sequence of the signal that is used to obtain blood vessel first view data lower than background parts; According to above-mentioned first view data and above-mentioned second view data, generate the generation unit of above-mentioned blood vessel three view data all higher than above-mentioned first and second view data with respect to the contrast of background parts.

The MR imaging apparatus of the 5th form of the present invention possesses: collect from the collector unit of the magnetic resonance signal of subject emission; According to the above-mentioned magnetic resonance signal of collecting, the reconfiguration unit of each dephasing image of reconstruct and complex phase image at least; According to the above-mentioned dephasing image that reconstructs and the both sides of above-mentioned complex phase image, the characteristic relevant with above-mentioned subject carried out the quantification unit of quantification.

Can understand other features and advantages of the present invention by the following description and embodiment.The present invention has more than and is limited to these explanations.

Description of drawings

Fig. 1 is the figure of summary structure of the MR imaging apparatus (MRI device) of expression one embodiment of the present of invention.

Fig. 2 is the flow chart that expression mixes the action step of the MRI device shown in Figure 1 under the situation of MRA.

Fig. 3 is an example of the pulse sequence under the situation of data collection of TOF method and FS-BB method is carried out in expression with 2 echoes figure.

Fig. 4 is the expression complex phase/vessel inner blood of dephasing GRE sequential and the signal intensity of the stationary figure with respect to the variation of TE.

Fig. 5 is the figure of the relation of expression blood vessel diameter, signal value S (WB), signal value S (BB).

The figure of Fig. 6 difference value Δ S that to be expression obtain according to signal value S (WB) shown in Figure 5 and signal value S (BB).

Fig. 7 is the figure of MIP image that represents to mix the MRA image of MRA MIP image and existing TOF method side by side.

Fig. 8 exists with ... layer piece position and figure that the object lesson of proportional zoom (scaling) value is set.

Fig. 9 is the flow chart of treatment step of master computer that expression is used for any one pixel is provided with Fig. 1 of proportional zoom value.

Figure 10 is the figure that expression mixes the relation of the CNR of MRA image and proportional zoom value α.

Figure 11 is the proportional zoom value α (k) that calculates of the master computer in the presentation graphs 1 and the figure of the relation of value k.

The figure of the treatment step when Figure 12 is the shooting of expression MRI device shown in Figure 1.

Figure 13 is the figure that the relation of the sampled point under the situation of complex phase TE and dephasing TE is collected on pointwise ground.

Figure 14 is the figure that the relation of the sampled point under 2 the situation of dephasing TE is collected in expression.

Figure 15 is the figure that the relation of the sampled point under 2 the situation of complex phase TE is collected in expression.

Figure 16 is the figure of an example of many echoes of expression GRE sequential.

Figure 17 is the figure of the relation of the sampled point in 4 methods of expression.

Figure 18 is the figure of notion of the computing of expression analytical parameters image.

Figure 19 is the figure of flow process of the computing of the analytical parameters image under the situation of the expression dephasing TE that collects 2 complex phase TE and at 1.

Figure 20 is illustrated in the suitable sampled point of the amplitude image picture that makes in the processing shown in Figure 19 and collects the figure of the relation of relevant sampled point with reality.

Figure 21 is the figure of flow process of the computing of the analytical parameters image under the situation of the expression dephasing TE that collects 1 complex phase TE and at 2.

Figure 22 is illustrated in the suitable sampled point of the amplitude image picture that makes in the processing shown in Figure 21 and collects the figure of the relation of relevant sampled point with reality.

Figure 23 is the figure of the asymmetric mask of expression.

Figure 24 is the figure of the mask of expression symmetric form.

Figure 25 is the figure of the colored synthetic object lesson of handling of expression.

Figure 26 is expression TR, the TE figure with respect to the example of the variation of k.

The specific embodiment

Below, embodiments of the invention are described with reference to the accompanying drawings.

Fig. 1 is the figure of summary structure of the MR imaging apparatus (MRI device) 100 of expression present embodiment.

This MRI device 100 possesses platform parts for sleeping in, magnetostatic field production part, leaning magnetic field production part, sends receiving-member and control calculating unit.The platform parts that crouch move the subject 200 of carrying.The magnetostatic field production part produces magnetostatic field.The leaning magnetic field production part produces the leaning magnetic field that is used for to the magnetostatic field additional location information.Send receiving-member high-frequency signal is sent reception.The control calculating unit is born all control of system and image reconstruction.In addition, as the element of these each parts, MRI device 100 possesses Magnet 1, magnetostatic field power supply 2, shim coil 3, shim coil power supply 4, top board 5, gradient magnetic field coil unit 6, leaning magnetic field power supply 7, RF coil unit 8, transmitter 9T, receptor 9R, clock generator (time schedule controller) 10, computing unit 11, memory element 12, display 13, loader 14, sound producer 15 and master computer 16.In addition, MRI device 100 is connected with the ecg measurement parts of the ECG signal of the dancing signal of the heart of measuring conduct expression subject 200.

The magnetostatic field production part comprises Magnet 1, magnetostatic field power supply 2, shim coil 3, shim coil power supply 4.As Magnet 1, for example can utilize superconducting magnet and normal electric conductance Magnet.Magnetostatic field power supply 2 is supplied with electric current to Magnet 1.In addition, under the situation of sampling superconducting magnet, can omit magnetostatic field power supply 2 as Magnet 1.In addition, the magnetostatic field production part produces magnetostatic field B in the space of subject 200 being sent into wherein cylindraceous (space is used in diagnosis) ₀This magnetostatic field B ₀Magnetic direction roughly with the diagnosis consistent with spatial direction of principal axis (Z-direction).Shim coil 3 is accepted the electric current supply from shim coil power supply 4 under the control of master computer 16, produce to be used to make magnetostatic field to revise magnetic field uniformly.

The top board 5 that platform parts for sleeping in will carry subject 200 is sent into diagnosis and is used the space, perhaps from diagnosing with taking out the space.

The leaning magnetic field production part comprises gradient magnetic field coil unit 6 and leaning magnetic field power supply 7.Gradient magnetic field coil unit 6 is configured in the inboard of Magnet 1.Gradient magnetic field coil unit 6 possesses 3 groups of coil 6x, 6y, the 6z that is used to produce orthogonal X-direction, Y direction and Z-direction leaning magnetic field separately.Leaning magnetic field power supply 7 is supplied with the pulse current that is used to produce leaning magnetic field to coil 6x, 6y, 6z respectively under the control of clock generator 10.The pulse current that the leaning magnetic field production part is supplied with to coil 6x, 6y, 6z from leaning magnetic field power supply 7 by control, and 3 (X-axis, Y-axis, Z axle) direction leaning magnetic fields separately as physical axis are synthesized, at random be provided with by orthogonal slice direction leaning magnetic field Gs, phase-encoding direction leaning magnetic field Ge, read axial each leaning magnetic field of logic that direction (frequency coding direction) leaning magnetic field Gr constitutes.Slice direction, phase-encoding direction and read each leaning magnetic field Gs, Ge, Gr and the magnetostatic field B of direction ₀Overlapping.Send receiving-member and comprise RF coil unit 8, transmitter 9T and receptor 9R.In diagnosis with in the space, RF coil unit 8 be configured in subject 200 near.Transmitter 9T is connected with RF coil unit 8 with receptor 9R.Transmitter 9T and receptor 9R move under the control of clock generator 10.Transmitter 9T supplies with the RF current impulse of the Larmor frequency that is used to produce nuclear magnetic resonance, NMR (NMR) to RF coil unit 8.Receptor 9R obtains the MR signals (radiofrequency signal) such as echo-signal that RF coil unit 8 receives, after it being implemented various signal processing such as preposition amplification, intermediate frequency conversion, phase detection, low frequency amplification or filtering, carry out the A/D conversion, generate numerical data (initial data).

The control calculating unit comprises clock generator 10, computing unit 11, memory element 12, display 13, loader 14, sound producer 15 and master computer 16.

Clock generator 10 possesses CPU and memorizer.Clock generator 10 will be stored in the memorizer from the pulse sequence information that master computer 16 sends.The CPU of clock generator 10 controls the action of leaning magnetic field power supply 7, transmitter 9T and receptor 9R according to the time sequence information that is stored in the memorizer.In case the initial data of the CPU input sink 9R of clock generator 10 output just is transferred to it computing unit 11.At this, time sequence information is meant according to a series of pulse sequence and makes leaning magnetic field power supply 7, transmitter 9T and receptor 9R move needed full detail, for example comprises with intensity, the application time of the pulse current that applies to coil 6x, 6y, 6z and applies relevant information such as timing.

Computing unit 11 is by the initial data of clock generator 10 inputs by receptor 9R output.Computing unit 11 is configured in the initial data of input in the k space (being also referred to as fourier space or frequency space) that is arranged in the internal storage.Computing unit 11 carries out the Fourier transforms of 2 dimensions or 3 dimensions, and the view data of the real space is reconstructed by being configured in data in this k space as object.In addition, computing unit 11 can also be carried out with synthetic processing, the Difference Calculation of image-related data and handle (also comprising weighted difference handles) as required.Should synthetic handle and comprise that processing, maximum projection (MIP) that the pixel value of each pixel is carried out addition are handled, minima projection (MinIP) is handled etc.In addition,, also can in fourier space, obtain on the basis of coupling of axle of a plurality of frames, the initial data of these a plurality of frames is synthesized, obtain the initial data of 1 frame as other examples of above-mentioned synthetic processing.In addition, addition process comprises simple addition process, summation averaging processing or weighted addition processing etc.

Memory element 12 storage reconstruct view data, implemented the view data of above-mentioned synthetic processing and difference processing.

Display 13 shows under the control of master computer 16 should be to the various images of user prompt.As display 13, can utilize display devices such as liquid crystal display.

Synchronization timing that loader 14 input operation persons wish selects the parameter information, the condition of scanning, pulse sequence of usefulness, synthesize with image and the relevant various information such as information of calculating of difference.Loader 14 sends to master computer 16 with the information of input.As loader 14, suitably possess input equipments such as selection equipment such as indicating equipments such as mouse, tracking ball, mode selector switch or keyboard.

Sound producer 15 has been when master computer 16 has had instruction, begins the information of holding one's breath and holding one's breath and finishing as sound generating.

Master computer 16 is controlled the action of each parts of MRI device 100 uniformly, makes to be implemented in the exercises that realized in the existing MRI device.As described later, master computer 16 also possesses the function that the proportional zoom coefficient is set when carrying out mixing MRA.

The ecg measurement parts comprise ECG pick off 17 and ECG unit 18.ECG pick off 17 is attached the body surface at subject 200, detects the ECG signal of subject 200 as the signal of telecommunication (hereinafter referred to as sensor signal).ECG unit 18 outputs to master computer 16 and clock generator 10 in that enforcement comprises on the basis of the various processing of digitized processing to sensor signal.As these ecg measurement parts, for example can use the vectorcardigram meter.When the heart with subject 200 synchronously scans time phase, in clock generator 10, use the sensor signal of these ecg measurement parts as required.

Embodiment 1

The action of the embodiment 1 of above-mentioned such MRI device 100 that constitutes then, is described.

In addition, the various shootings that MRI device 100 can carry out realizing in existing MRI device, but omit explanation to them.In addition, at this, the action under the situation that obtains mixing MRA is described.

Fig. 2 is the flow chart that expression obtains mixing the action step of the MRI device 100 under the situation of MRA.

In step Sa1, clock generator 10 control leaning magnetic field power supplys 7, transmitter 9T and receptor 9R collect the data separately in WB method and the BB method.Can under sequential separately, carry out the data collection of this WB method and the data collection of BB method, but, use many echo methods in a series of sequential, to carry out WB method and BB method both sides' data collection at this.Carry out this data collection at a plurality of sections in the layer piece that is set to camera watch region respectively.

As WB method and BB method, specifically adopting which method is arbitrarily.But, adopt the TOF method as the WB method in this hypothesis, adopt FS-BB (flow-sensitive BB) method as the BB method.In addition, FS-BB carries out data collection under the pulse sequence that the gtadient echo that comprises the pulse of dephasing leaning magnetic field (GRE) is.The pulse of dephasing leaning magnetic field produces and to be used to strengthen because of the tremulous pulse of region-of-interest and the venous leaning magnetic field that signal that (flow) produce reduces that flows.

Establish pulse sequence be GRE, static magnetic field strength be TE under the situation of 1.5T under the situation of TOF method for less than 10, be 20 under the situation of FS-BB method.

Fig. 3 is the figure that represents an example of pulse sequence at this moment.Waveform shown in Figure 3 from the leaning magnetic field waveform (Ge) of the leaning magnetic field waveform (Gs) of the last echo-signal of sequentially representing the short pulse to the high frequency that subject 200 applies (flip pulse) and subject 200, producing, slice direction, phase-encoding direction, read the leaning magnetic field waveform (Gr) of direction.

At this, be complex phase with respect to the TOF method, the FS-BB method is a dephasing.

Fig. 4 is that expression is based on the complex phase/vessel inner blood of dephasing GRE sequential and the signal intensity of the stationary figure with respect to the variation of TE.

In complex phase, the signal of blood does not reduce the ground former state and collects.In contrast, in dephasing, suppress blood signal ground and collect.Thus, as shown in Figure 3, the signal that produces in blood by complex phase is the signal higher than the signal that produces in immobilized tissue.In addition, the signal that produces in blood by dephasing is the signal lower than the signal that produces in immobilized tissue.

In step Sa2, computing unit 11 is according to the data of using the TOF method to collect as described above, and than the image shown in the high signal of background, promptly the WB image is reconstructed to the blood vessel signal.In addition, computing unit 11 is according to the data of using the FS-BB method to collect as described above, and than the image shown in the low signal of background, promptly the BB image is reconstructed to the signal of blood vessel.

In step Sa3, computing unit 11 calculates the proportional zoom difference of WB image and BB image.Below, will be called by this image that calculates and mix the MRA image.

Specifically, for each pixel relevant with same position, the signal value in the WB image relevant with this pixel is made as S (WB), the signal value in the BB image is S (BB), and to establish the proportional zoom coefficient be α, then calculates difference value Δ S according to following formula (1).

ΔS＝S(WB)-α×S(BB) …(1)

Fig. 5 is the figure of the relation of expression blood vessel diameter, signal value S (WB), signal value S (BB).

As shown in Figure 5, the vasculature part of the signal value S (WB) in the WB image is than signal value Sbase (WB) height of background parts.The vasculature part of signal value S (BB) in the BB image is lower than the signal value Sbase (BB) of background parts.In addition, the condition difference during owing to the MR signal collection so signal value Sbase (WB) and signal value Sbase (BB) are as shown in Figure 5, generally is different.In addition, contrast for the big blood vessel of the such blood vessel diameter of trunk tremulous pulse, is the big of equal extent to noise ratio (CNR) in WB image and BB image, but for the little blood vessel of the such blood vessel diameter of peripheral vessel, medium and small at the WB image.In addition, can replace Sbase (WB) and Sbase (BB) with the signal intensity of WB image and BB image low-pass pictures separately.

In addition, for difference value Δ S, as shown in Figure 6, vasculature part is all bigger than any one of signal value S (WB) and signal S (BB) with respect to the contrast of the difference value Δ Sbase of background parts.

In addition, make α * Sbase (BB) big, then can access the effect that increases contrast unlike Sbase (WB) if proportional zoom value α is set.Therefore, proportional zoom value α can at random be set in satisfying the scope of above-mentioned condition.For example also can establish α=0, not be weighted.But, it is desirable to proportional zoom value α and be set to the difference value Δ Sbase of background parts as far as possible near 0.This is because do not pay close attention to background parts, can further improve the image quality of mixing the MRA image.

In addition, at each mixing MRA image more than the self-generating of the whole sections in the layer piece.

In step Sa4, computing unit 11 as object, carries out a plurality of mixing MRA images MIP and handles.Below will handle the image that obtains and be called mixing MRA MIP image by this MIP.The mixing MRA image of the object that MIP handles can be all or part of of mixing MRA image of whole sections of generating in step Sa3.Perhaps, also can in the mixing MRA image of the object that MIP handles, comprise at least one mixing MRA image of other sections that generate by the section conversion.

In step Sa5, computing unit 11 generates mask (mask) image according to the WB image.For example under the situation that the blood vessel in the brain is made a video recording, this mask images is the image in the expression zone suitable with brain essence.The BB image is owing to reasons such as the signal difference around brain essence and its are little, so be difficult to extract out the zone of brain essence from the BB image.But in the WB image, brain essence and blood vessel are high signal, therefore can be from the WB image the simple zone of extracting brain essence and blood vessel out of handling such as passing threshold processing.

In step Sa4, carry out MIP when handling, also can the reference mask image, zone that only will be suitable with brain essence is as object.In addition, for example showing under the situation of other images that the minIP image etc. of BB image is such, also can the reference mask image this minIP be being handled and carry out with mixing MRA MIP image.

Fig. 7 is the figure of MIP image (hereinafter referred to as the TOF_MRA image) that represents the MRA image of above-mentioned such mixing MRA MIP image that generates and existing TOF method side by side.The upside of Fig. 7 is the TOF_MRA image, and downside is to mix the MRA image.The TOF_MRA image and mix the MRA image begin from a left side all be axially, the top to radial MIP image.

In addition, 3 first order (3 axis 1st order) GMN according to TR=50ms, TE=6.8ms, FA=20deg make a video recording and obtain the TOF_MRA image.According to being made as TE=26ms, b-factor=2sec/mm ²And BB image of making a video recording and above-mentioned TOF_MRA image are established α=1 and generate to be mixed MRA as described above.

As known to according to this Fig. 7, mix the MRA image and be with based on the same WB image of the MRA image of TOF method, in mixing the MRA image, use than contrast and at length depict blood vessel, particularly trickle peripheral vessel based on the MRA figure image height of TOF method.

In addition, generally in the TOF method, flow in the inflow part of layer piece at blood, the blood vessel signal is big.But for blood, known to the traveling according to peripheral vessel increases the number of times that continues excitation by RF, the blood vessel signal of peripheral vessel diminishes.Therefore, if, be provided with forr a short time, then can access the high-quality mixing MRA image of considering above-mentioned character than the proportional zoom value that is suitable for to section far away for suitable proportional zoom value α being set near inflow section partly to layer piece.Fig. 8 represents to exist with ... layer piece position as described above and figure that the object lesson of proportional zoom value is set.

In addition, as the value of proportional zoom value α optimum relation, all different for each pixel according to WB image and BB image.Therefore, it is desirable to each pixel is provided with the proportional zoom value, it is applicable to the proportional zoom difference.

Below, the processing of the proportional zoom value that each pixel is set is described.

In embodiment 1, measure blood vessel diameter, WB image and BB image each signal intensity self or with the CNR of surrounding tissue, based on it proportional zoom value is set more suitably.Because the upper frequency composition is many,, can extract the blood vessel signal out so same image is implemented the image of low-pass filtering treatment and do not implemented difference between the same pixel of image of low-pass filtering treatment by obtaining.Perhaps, handle the background signal that reduces low frequency, can extract the blood vessel signal out by high-pass filtering.In addition, the difference value of obtaining like this in the WB image in positive direction, big more on negative direction in the BB image, then be that the probability of blood vessel is big more.Noise contribution is certain, so the signal intensity former state is CNR.

Fig. 9 is the flow chart of treatment step that expression is used for any one pixel is provided with the master computer 16 of proportional zoom value.

In the step Sa3 of Fig. 2, calculate before the proportional zoom difference, according to reconstruct in step Sa2 WB image and BB image, carry out this processing.

In step Sb1, master computer 16 is implemented high-pass filtering to WB image and BB image respectively and is handled, and background signal is reduced at WB image and BB image in separately thus, extracts the blood vessel signal out.

In addition, also can be only in WB image and the BB image any one being implemented this high-pass filtering handles.In this case, fuzzy in order to reduce low frequency, it is desirable to the BB image is implemented.In addition, also can replace high-pass filtering to handle, WB image or BB image be implemented low-pass filtering treatment and the processing of the difference of the image that obtains and WB image or BB image and obtain.Perhaps, replace high-pass filtering to handle, also can carry out as abs[Sorig]-abs[Slow] obtain with the image-related absolute value images that WB image and BB image enforcement low-pass filtering treatment are obtained respectively between the processing of difference dS.And then, after high-pass filtering is handled, also can carry out the phase place correction and obtain real image.The phase place that for example can use the data according to the spatial core of k to make is carried out this phase place correction.

In addition, by such Filtering Processing, can revise the fuzzy of low-frequency component because of generations such as susceptibility.

In step Sb2, pixel value in the image that will obtain will implement high-pass filtering to handle as described above to the WB image is as Sb (WB), and under the situation of pixel value as Sd (BB) in the image that will obtain BB image enforcement high-pass filtering processing, master computer 16 calculates the value k suitable with CNR according to following formula (2).

k＝Sd(BB)/Sd(WB) …(2)

Then, in step Sb3, as Sbase (BB)/Sbase (WB), master computer 16 is obtained the ratio of signal value Sbase (BB) and signal value Sbase (WB).

Then, in step Sb4, master computer 16 calculates the proportional zoom value α (k) corresponding with the value k that obtains in step Sb2.It is Sd (WB)＞0 that mobile internal blood vessel is arranged, Sd (BB)＜0, so k＜0.Relative therewith, stationary is the probability height of k 〉=0.That is, symbol is for negative in the pixel suitable with blood vessel for the above-mentioned value k that obtains like that, and symbol is for just in the pixel suitable with stationary.Therefore, if k 〉=0, then proportional zoom value α can be that Sbase (WB)-a * Sbase (BB) is 0 value, the i.e. value of obtaining in step Sb3.If k＜0, then along with k increases to negative direction, α (k) increases to positive direction.

Consider to mix the CNR of MRA image and the relation of proportional zoom value α, the α (k) of k＜0 o'clock is set as follows.

At first, establish with the blood vessel of 2 kinds of original image S1, S2 be C1, C2 with respect to the contrast of surrounding tissue S1base, S2base, noise SD is σ n1, σ n2, CNR is under the situation of CNR1, CNR2, the relation of CNR, the CNR (Δ S) of the blood vessel among derivation and the weighted difference image Δ S=S1-α * S2.According to the definition of problem, be C1=S1-S1base, C2=S2-S2base, Δ S=S1-α * S2.With the contrast of original image, represent the contrast of Δ S image like that as shown in the formula (3).

C(ΔS)＝ΔS-ΔSbase＝{S1-αS2}-{S1base-αS2base} …(3)

＝{S1-S1base}-α{S2-S2base}＝C1-α×C2

Blood vessel in the Δ S image is with respect to the CNR of surrounding tissue, and CNR (Δ S) is such as shown in the formula (4).

$\mathrm{CNR}\left(\mathrm{\&Delta;S}\right)=C\left(\mathrm{\&Delta;S}\right)/\mathrm{\&sigma;}\left(\mathrm{\&Delta;S}\right)=(C1-\mathrm{\&alpha;}\&CenterDot;C2)/\sqrt{{{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="S2007101693500E00011.png,S2007101693500E00031.png"\; state="\{\{state\}\}">n</figure-callout>}1}}^2+{\mathrm{\&alpha;}}^2{{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="S2007101693500E00011.png,S2007101693500E00051.png"\; state="\{\{state\}\}">n</figure-callout>}2}}^2}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

At this, the CNR of Δ S image is the situation of following formula (5) for maximum condition.

δ{CNR(ΔS)}/δα＝(-C1×α×σ _n2 ²-C2×σ _n1 ²)/(σ _n1 ²+α ²×σ _n2 ²) ^3/2＝0 …(5)

If obtain the α=α that satisfies this formula (5) _OptIf it is then denominator is not 0,, then such as shown in the formula (6) promptly if not the image that does not have noise.

α _opt＝-(C2/σ _n2 ²)/(C1/σ _n1 ²) …(6)

Special under the situation of σ n1=σ n2=σ n, formula (4) and formula (6) are respectively following formula (4 ') and formula (6 ').

$\mathrm{CNR}\left(\mathrm{\&Delta;S}\right)=(C1-\mathrm{\&alpha;}\&CenterDot;C2)/\sqrt{(1+{\mathrm{\&alpha;}}^2)}{\mathrm{\&sigma;}}_n\&CenterDot;\&CenterDot;\&CenterDot;\left(4^{\&prime;}\right)$

α _opt＝-C2/C1 …(6’)

By same coil under the situation of under the same receiving gain subject 200 being made a video recording and the situation of making a video recording by 2 echoes, can think that noise SD is identical, therefore above-mentioned formula (4 ') and formula (6 ') establishment.

In a word, the CNR that the contrast of blood vessel among the weighted difference image Δ S=S1-α * S2 of 2 kinds of original images and surrounding tissue is relevant in the sign-inverted of the ratio of the relevant CNR of the contrast that equals 2 kinds of original images blood vessel separately and background value the time for maximum.

As an example, if hypothesis image S1 is the WB image, figure S2 is the BB image, and CNR1=10, CNR2=-10, and then just can in α=1.That is, simple difference S1-S2 just can provide maximum CNR.The CNR of the difference image under this situation is CNR=10-(10)/√ 2=14.1, rises to 1.41 times before the difference.On the other hand, when in WB, depicting blood vessel, if in the image of difference side, do not depict the state of blood vessel fully, i.e. CNR1=10, CNR2=0, then just can in α=0.That is, S2 is not carried out difference and former state ground uses S1 that the CNR of maximum just can be provided.

Figure 10 is the figure that expression mixes the relation of the CNR of MRA image and proportional zoom value α.

The CNR that Figure 10 has represented to establish the blood vessel in the WB image respectively is 10, and the contrast C of BB image (BB) and ratio C (the BB)/C (WB) of the contrast C (WB) of WB image are respectively CNR that mixes the MRA image under 0 ,-0.50 ,-0.75 ,-1.00 ,-1.25 ,-1.50 ,-1.75 ,-2.00 the situation and the relation of proportional zoom value α.

As according to this Figure 10 as can be known, make the α of the CNR maximum of mixing the MRA image _OptSuch as shown in the formula (7).

α _opt＝-C(BB)/C(WB) …(7)

Wherein, as according to Figure 10 as can be known, if C (BB)/C (WB)＜-1, if then establish α＞1, then CNR changes hardly.

Figure 11 is the proportional zoom value α (k) that calculates in step Sb4 of expression master computer 16 and the figure of the relation of value k.

If implement as above-mentioned theory, then master computer 16 can such value calculate proportional zoom value α (k) like that shown in the dotted line among Figure 11.But, in fact, near k=0, consider noise, and proportional zoom value α (k) changed.Meanwhile, in the zone of k＜0, in order to form the image of nature, for example the value of representing with solid line among Figure 11 calculates proportional zoom value α (k) like that.

In addition, each pixel is provided with proportional zoom value α, does not therefore need to be provided with especially its higher limit α max, but in Figure 11, be provided with suitable value as fault processing.

In addition, for the pixel of k＜0, be that the probability of stationary is big.Therefore, do not carry out the proportional zoom difference,, can be replaced into the value of the suitable pixel in the low-pass filtering image of WB image or BB image, can be replaced into 0 yet in order to reduce the noise that mixes in the MRA image.

If the proportional zoom value α (k) of each pixel so suitably is set, even then the blood vessel intricately changes direction, flow into the two end portions that part and thin blood vessel not necessarily are positioned at layer piece, also proportional zoom value α can be set suitably, and generate high-quality mixing MRA image.

But, being not more than WB image or BB image if mix the MRA image, then relevant with the contrast of blood vessel and background CNR is nonsensical when generating mixing MRA image.

The CNR based on TOF of the trunk portion of blood vessel is big, but in peripheral vessel, based on the CNR of TOF near 0.Therefore, the proportional zoom of BB image is big more, and the CNR that the contrast of blood vessel and background is relevant is good more.That is, in peripheral vessel, can not carry out difference, and use the BB image separately as can be known.In this case, if α=1, then the CNR of difference image is 1/ √ 2=0.71.Therefore, if it is bigger than 2 times of the √ of the CNR of WB image or BB image to mix the CNR of MRA image, the CNR of blood vessel that then mixes the MRA image is bigger than WB image or BB image.Because background is near 0, big with the difference of blood vessel signal, be 0 such proportional zoom so carry out making the signal value of background when being preferably in MIP according to difference.

Under the situation of 2 echo GRE, the signal intensity of background is Sbase (WB)＞Sbase (BB).Establishing background is that α＞1 is weighted peripheral vessel under 0 the situation.In this case, in difference image, need fully in MIP, not depicted blood vessel, so it is desirable to be provided with α≤Sbase (WB)/Sbase (BB), the upper limit makes that signal intensity is background＞air＞0 by air with hindering.

As described above, in embodiment 1, the BB image of the signal that the WB image of the signal that the use blood vessel is higher than background and blood vessel are lower than background is compared with image separately, can depict blood vessel with higher CNR.The signal of background tissues is reduced in the middle particular importance of describing of thin blood vessel among MIP or the miniIP.

In addition,, compare, improved the ability of describing of sinuous flow part, thin blood vessel or the secondary bloody path of side with the TOF method according to embodiment 1.Camera time is compared with the TOF method and is more or less prolonged (being directly proportional with TR).In addition, compare with the TOF method, in embodiment 1, blood vessel increases with respect to the CNR of background tissues, and fat and background tissues reduction.Need be in the TOF method in embodiment 1 necessary MTC pulse.Compare with the TOF method, in embodiment 1, also improved sinuous flow part and the ramose ability of describing of break-through.

In addition, according to embodiment 1, compare with the FS-BB method, blood vessel increases with respect to the CNR of background tissues, and background tissues reduces.

In addition, under the situation of having used contrast agent, the situation that becomes WB, BB is arranged also, can improve the CNR of tissue such as blood vessel.For example, if paramagnetic contrast medium is WB under T1W then, under T2*W BB.Therefore, can realize having utilized under the 2 echo sequential of the GRE the same with the situation of non-radiography.

Embodiment 2

The action of the embodiment 2 of MRI device 100 then, is described.

(A) the theoretical preparation

Prepare as the theory before the concrete action of explanation, definition susceptibility is inhomogeneous and the MR signal model of mobile voxel (voxel), the signal model of complex phase/dephasing arranged.

(A-1) susceptibility is inhomogeneous and the MR signal model of mobile voxel arranged

Definition is inhomogeneous with susceptibility and the relevant parameter of MR signal model of mobile voxel arranged at first, as follows.

M ₀: proton density

A _T1: the decay that exists with ... T1

A _T1＝1-exp(-TR/T1)

A _T2: the decay that exists with ... T2

A _T2＝exp(-TE/T2)

A _D: the decay that exists with ... diffusion

A _D＝exp[-bD]

A _SUS: the decay that exists with ... susceptibility

A _sus＝exp[-TE(γΔB _0σ)] ^*

Φ _SUS: the phase place that exists with ... susceptibility

φ _sus＝-TE(γΔB _0m)

Wherein, be the situation of Lorenzian model.

T2 ^*: comprise T2 and based on relaxation time of the composition of susceptibility effect.

1/T2 ^*＝1/T2+γΔB ₀(T2 ^*＜T2)

In addition, if use T2 ^*, then be A _T2A _Sus=exp (TE/T2 ^*).

A _Flow: exist with ... mobile decay.

A _flow＝exp[-bD _flow]

B: according to the coefficient (gradientfactor) that goes out with the leaning magnetic field mode computation that spreads definition.

D _Flow: based on the phase place coefficient of dispersion (in not having mobile part, being equivalent to coefficient) of flow (flow) with the diffusion coefficient equivalence that defines

Φ _Flow: exist with ... mobile phase deviation (Flow dependent phase shift)

${\mathrm{\&Phi;}}_{\mathrm{flow}}=-\mathrm{\&gamma;}{\&Integral;}_0^{\mathrm{TE}}G\left(t\right)\&times;\left(t\right)\mathrm{dt}$

V: susceptibility is inhomogeneous and comprise mobile tissue.Be Δ B ₀＜＞0, and the tissue of F＜＞0.For example be equivalent to vein etc.

In this case, like that the MR signal S that comes self-organizing V is carried out standardization as shown in the formula (8).

S＝(M ₀?A _T1?A _T2?A _D?A _sus?A _flow)exp[i(Φ ₀+Φ _sus+Φ _flow)] …(8)

At this, be created in the composition of related (coherent) in susceptibility and the mobile effect in the phase place, in amplitude fading, produce the composition of dereferenced (incoherent).That is, in contrast, the Δ B in the voxel (voxel) ₀It is big more to distribute, or IVIM (intravoxel incoherentmotion) composition is big more, and then term amplitude more produces dominating role than phase term.In addition, the IVIM composition becomes big according to the order of vein → thin vein → blood capillary.

(A-2) signal model of complex phase/dephasing

The signal model of complex phase/dephasing then, is described.

In ideal model, in complex phase, make amplitude and phase place all eliminate the composition that produces because of flowing, only become the composition that produces because of susceptibility.But, in fact,, also can produce the variation that exists with ... GMN (gradient moment nulling) grade and sinuous flow even in complex phase.On the other hand, in dephasing, amplitude and phase place all can add the composition that flows in the susceptibility composition, therefore represent signal S in complex phase/dephasing ideal model separately like that as shown in the formula (9) and (10) _Re, S _De

S _re＝(M ₀?A _T1?A _T2?A _D?A _sus)exp[i(Φ ₀+Φ _sus)] …(9)

S _de＝(M ₀?A _T1?A _T2?A _D?A _sus?A _flow)exp[i(Φ ₀+Φ _sus+Φ _flow)] …(10)

At this, if because the cycle time T R in the sequential condition of complex phase/dephasing is identical with echo time TE, the b value of dephasing is fully little, and can ignore A _DEffect, S then _DeSuch as shown in the formula (11).

S _de＝S _reA _flowexp[iΦ _flow] …(11)

That is S, _DeBe at S _ReIn added flow effect.

The change of MR signal (amplitude, phase place) has following such character.

Flow into proportion by subtraction M in the voxel _Flow/ (M _Flow+ M _St) many more, then the change of MR signal is big more.

The b value is big more, and then the change of MR signal is big more.

If the IVIM composition is big, then the change of the MR signal of the amplitude fading effect that produces because of dephasing grad. is big.

If the IVIM composition is big, then the change of the MR signal of the phase place variation effect that produces because of dephasing grad. is big.

(B) data collection of complex phase/dephasing and facture

With respect to the existing situation of having only complex phase or having only dephasing,, can produce new application by being used in combination complex phase and dephasing.Such as mentioned above, complex phase is only to change because of the signal that T1 relaxes, T2 relaxes and the susceptibility effect produces.Dephasing is to have added mobile effect to complex phase.Therefore, by the calculating between the data of complex phase and dephasing, can access the image that composition beyond the flow effects such as making the composition relevant with stationary and susceptibility effect has separated with flow effect.And then, by aforementioned calculation, express the general parametric image of susceptibility and flow effect with accessing the amount of revising and deciding.Clinically, use complex phase and the flow effect physically of dephasing and the size of susceptibility effect to carry out separating of vein and tremulous pulse etc.At this, enumerate the method and the clinical practice example thereof of collection.

(B-1) theory

Before the concrete treatment step of explanation, first talk about sensible opinion.

The MR signal of complex phase and dephasing is the complex signal with amplitude and phase place.If establishing the gain of MR signal is K, A ₀=M ₀, A _T1, A _T2, formula (9), (10) are expressed as the K and as TR, the TE of the variable element of sequential, the function of b value of gaining arbitrarily, then such as shown in the formula (9 ') and (10 ').

S _re(TR，TE)＝A _re(TR，TE)exp[iΦ _re(TE)]＝K?A ₀(TR，TE)A _sus(TE)exp[i{Φ ₀(TE)+Φ _sus(TE)}] …(9’)

S _de(TE，TE，b)＝A _de(TE，TE)exp[iΦ _de(TE)]＝K?A0(TE，TE)A _sus(TE)A _flow(b)exp[i{Φ ₀(TE)+Φ _sus(TE)+Φ _flow(b)}] …(10’)

In addition, at this, because b value can have the signal attenuation effect because of mobile generation, thus fully little, can ignore the effect A of the shared molecular diffusion of A0 _DThat is A, ₀In complex phase and dephasing is the same.In addition, as M ₀A _T1Obtain longitudinal magnetization (longitudinalmagnetization) Mz, under the situation of GRE, also comprise inflow (inflow) effect ground and determine A with TR _T1

(B-1-1) bodily tissue and susceptibility, mobile

If the different of susceptibility and mobile character are investigated on the intravital tissue of difference body ground, then tremulous pulse so can there not be the apparent magnetic susceptibility effect, is not therefore depicted tremulous pulse owing to comprise a lot of HbO2 Oxyhemoglobins (oxyHb) in complex phase.On the other hand, the venous flow effect is littler than tremulous pulse, and then, also add the susceptibility effect that produces because of HbO2 Oxyhemoglobin.Therefore,, change, then depict to the dominant trait veneous signal (susceptibility effect composition) if in complex phase, pay close attention to the phase place that produces because of flowing fully once more for blood vessel.Consequently in dephasing, depict any one of tremulous pulse and vein (the susceptibility effect+composition flows).In any one of complex phase and dephasing, also depict stationary comparably.

Vein since flow slow, so in it is optionally described except the susceptibility effect, not have the method for getting well.In addition, because only by complex phase, the poor contrast of vein and stationary is insufficient, so be difficult to separate tremulous pulse and stationary.

(B-1-2) optimum timing parameter: TE

For TE, the optimal conditions of amplitude, phase place both sides' the TE that makes the CNR maximum is TE=T2 ^*That is, at TE and T2 as the tissue of object ^*Under the situation about equating, with have its T2 nearby ^*Tissue between produce maximum CNR.Depend on the kind ground of collection condition and tissue, at T2 ^*In distribution is arranged, but important blood also has the scope of susceptibility when vessel delineation, it is certain that white matter and cinereum matter are almost regarded as, therefore establishing under the certain situation of voxel size, roughly can determine TE under these conditions.

(B-1-3) flow effect and susceptibility effect separates

If camera parameters such as receiving gain, TR, TE and b value are fixed, then former state ground can be to comparing between complex phase and the dephasing mutually.But, for indexing more quantitatively, can be according to D _FlowCalculate the mobile composition of demonstration, according to T2 ^*, Δ χ etc. calculates and shows the susceptibility composition.In this case, substitute b=0 in complex phase, TE needs minimum 3 images more than 2.

(B-1-3-1) quantification of flow effect

If obtain amplitude ratio and phase contrast between complex phase and the dephasing, then according to formula (11), as shown in the formula (12) and (13) that works separated flow effect.

Dephasing/complex phase amplitude ratio: A (de)/A (re)=A _Flow(12)

Dephasing/complex phase phase contrast: Φ (de)-Φ (re)=Φ _Flow(13)

At this, can be as PS-MRA (phase contrast MR angiography) method, 3 directions of operating speed coded pulse VENC are measured and are obtained phase contrast Φ _FlowBut, almost be unpractical at this, so omit, such relation shown in the following formula (14) is arranged, obtain expression because of various flow velocity with to the D of the dispersive degree of phase place at random of the mobile generation of various direction _Flow

A _flow＝exp[-b*D _flow] …(14)

At this, be b (be) if establish the b value of dephasing, the signal intensity of dephasing and complex phase (amplitude) is respectively A (de), A (re), then can substitute b=0 in complex phase, therefore calculates D according to following formula (15) _Flow

D _flow[mm ²/sec]＝-ln[A(de)/A(re)]/b(de) …(15)

(B-1-3-2) quantification of susceptibility effect

At first, the situation of using amplitude meter to calculate the quantitative indices of susceptibility effect is described.

The attenuation term Asus that produces because of the susceptibility effect exists with ... TE, under single TE, can't eliminate the A of the effect that has added T1 mitigation and T2 mitigation etc. ₀Therefore, can obtain more at large and comprise γ Δ B ₀The T2 of σ or T2 ^*

2 TE in using complex phase (below be called TE1, TE2, and establish under the situation of TE2＞TE1), determine TE1 and TE2 signal intensity (amplitude) A1, A2 separately according to following formula (16) and (17).

A1＝K?A ₀?exp[-TE1/T2 ^*] …(16)

A2＝K?A ₀?exp[-TE2/T2 ^*] …(17)

According to these formula (16) and (17), with the index of following formula (18) expression because of the amplitude fading effect of susceptibility effect generation.

T2 ^*＝(TE2-TE1)/ln[A1(TE1)/A2(TE2)] …(18)

In addition, calculating T2 ^*The time, can obtain the above many echoes of 3 echoes, use least squqre approximation.

On the other hand, the situation of using phase place is described.

As other forms of expression of susceptibility effect, according to single TE, or deducted the phase place of the phase component of low frequency from the phase contrast of 2 echoes from complex phase, obtain Φ sus.Represent Φ sus under the situation of the situation of single echo and 2 echoes by following formula (19) and (19 ') respectively.

Φ _sus＝-2 _πγΔ _χB ₀(cos ²θ-1/3)TE …(19)

Φ _sus＝-2 _πγΔ _χB ₀(cos ²θ-1/3)(TE2-TE1) …(19’)

According to this Φ sus, represent Δ χ under the situation of the situation of single echo and 2 echoes by following formula (20) and (20 ') respectively.

Δ _χ[ppm]＝-Φ _sus/{2 _πγ?B ₀(cos ²?θ-1/3)TE} …(20)

Δ _χ[ppm]＝-Φ _sus/{2 _πγ?B ₀(cos ²?θ-1/3)(TE2-TE1)} …(20’)

Can think that this Δ χ represents the average susceptibility in the voxel.

At this, γ is that magnetic rotation is than (gyromagnetic ratio), B ₀The expression static magnetic field strength is by device decision uniquely arbitrarily.But θ is B ₀Therefore the traveling angle of direction and blood vessel needs the method for the dependency between voxel by inquiry etc. to measure the method difficulty that beguine is obtained according to amplitude.

In addition, if just susceptibility distributes, if then only in complex phase TE be more than 2 stages, can realize that then this technology is known.

Then, according to Figure 12 concrete treatment step is described.

(B-2) collection of dephasing and complex phase data

In step Sc1, clock generator 10 is collected dephasing data and complex phase data.

Can make a video recording the continuously independently dephasing of same TE and the sequential of complex phase.Perhaps, in order to make the minimum that influences of motion, can be divided into and alternately collect 1 data set and synthetic a plurality of sections (segment).The section of cutting apart is 1 row (TR) unit in the k space, or is 2 dimensional plane units etc., is arbitrarily.

The stage of b value can be a plurality of.If also obtain a plurality of TE, then to correctly calculating T2 ^*Also can work.If in TR, collect many echoes, then can once obtain a plurality of TE according to Gradient Echo method.In addition, if use the Look-Locker method, then also can once obtain a plurality of b values.In addition, according to " Measurement of Gd-DTPA dialysisclearance rates by using a look-locker imaging technique. ", MagnReson, Med.1996 Oct; 36 (4): 571-8., Look-Locker method as can be known.

(B-2-1) dephasing/complex phase alternate segments is collected (one group of dephasing, complex phase is same TE)

In order only to calculate flow effect D _Flow, clock generator 10 is collected the dephasing and the complex phase of 2 images under same TE.At D _FlowThe basis on also calculate T2 ^*Situation under, clock generator 10 is established TE1, TE2 with the complex phase side in 2 echoes, dephasing becomes any one of TE1, TE2.In this case, also can cut apart the sequential of dephasing and complex phase and make a video recording respectively.Perhaps, alternately collect 1 data set and synthetic in order to make the minimum that influences of motion between image, can be divided into a plurality of sections (segment).The section of cutting apart is 1 row (TR) unit in the k space, or is 2 dimensional plane units etc., is arbitrarily.

(B-2-2) mix the situation (TE is all different) of collecting continuously based on complex phase, the dephasing of the many echoes of GRE

Be illustrated in the embodiment that GRE handles with the many echoes more than 2 of combination complex phase and dephasing down.

Compare with the situation of above-mentioned (B-2-1), if collect under many echoes, then the TE of complex phase and dephasing can't be identical, can access quantitative parameter for identical but collect when calculating under a plurality of TE.Can obtain many echoes in the promptly same TR 1 time RF excitation.Therefore, the acquisition time with sweep time and 1 echo is the such great advantage of equal extent.On this basis, compare with separating the situation that the time collects independently, the body that also can ignore between data is moving, the advantage of the error in the time of therefore can alleviating the calculating between the data not of the same race in addition.Certainly, even obtain, also can commonly carry out the computing of analytical parameters image described later as data separately.

(B-2-2-1) 2 methods

(B-2-2-1-1) situation of pointwise ground collection complex phase TE and dephasing TE

As shown in Figure 13, collect the A of TE=TE1 respectively _De(TE1), the A of TE=TE2 _Re(TE2).

In this case, because the data of same pattern do not have more than 2,, can't calculate the T2 in the quantitative parameter so mainly be that 2 images are observed on former state ground ^*, D _FlowDeng.But, if the condition of establishing is TE2=2 * TE1, then can be only to mobile phase term Φ _FlowCarry out quantification.

By establishing TE (de)＜TE (re), dephasing becomes and has suppressed the susceptibility effect and strengthen mobilely, and complex phase becomes and suppressed flow effect and strengthen susceptibility.Under the such situation of TE (re)＜TE (de), if be provided with TE (re) short (＜10ms), then complex phase will substitute to tremulous pulse by the TOF-MRA (time of flight-magnetic resonanceangiography) that usual method is collected and describe usefulness, might not need common TOF-MRA.And then, dephasing also can with flow and the susceptibility effect describe usefulness as enhanced arteriovenous, can also control according to the setting of TE and describe vein.In addition, if also use phase information, then can strengthen the CNR of vein with respect to background tissues.And then, by between dephasing and complex phase, carrying out computing as described later mutually, can also carry out tremulous pulse and separate demonstration with venous.In addition, under the situation of 2 echoes, the TE of complex phase and dephasing does not need consistent scrupulously, if two TE are fully approaching, and T2 ^*Difference little, then can show to sxemiquantitative.

(B-2-2-1-2) situation of 2 dephasing TE of collection

As shown in Figure 14, collect the A relevant respectively with TE=TE1 _De(TE1) with the A relevant with TE=TE2 _De(TE2).

If (the b value of 2 echoes of TE1＜TE2) is identical, then A to establish De TE=TE1, TE2 _Flow=exp[-bD _Flow].In addition, if gradient moment is also identical, then the flow effect amount Φ flow of phase place is also roughly the same.Therefore, obviously can eliminate flow effect according to following formula (21).

S _de(TE2，b)/S _de(TE1，b)＝exp[-(TE2-TE1)/T2 ^*]exp[-i(TE2-TE1) _γΔB _0m]

…(21)

In addition, because TE1, TE2 are known, so can calculate T2 according to the amplitude of formula (20) ^*, and then can calculate Δ B according to phase term ₀, can calculate Δ χ.

(B-2-2-1-3) situation of 2 complex phase TE of collection

As shown in Figure 15, collect the A relevant respectively with TE=TE1 _Re(TE1) with the A relevant with TE=TE2 _Re(TE2).

Owing under A2, see b=0 as, so except Aflow=1, Φ flow=0, also the subscript de in (B-2-2-1-2) is replaced into re.

(B-2-2-2) 3 methods

Collect 3 points if mix complex phase and dephasing, then at T2 ^*Or Δ B ₀The basis on, promptly on the basis of Δ χ, can also calculate flow effect.In addition, with the many echoes that use GRE irrespectively, can make complex phase image and the dephasing image of same TE.3 TE can combination in any.

In 3 methods, each echo is 2 * 2 * 2=8 kind by the combination in any of dephasing and complex phase, as does not have the problem of order, then is 4 kinds.Enumerate wherein these 2 kinds of complex phase, complex phase, dephasing and dephasing, dephasing, complex phases.

(B-2-2-2-1) situation of 2 complex phase TE of collection and 1 dephasing TE

2 according to initial complex phase calculate T2 ^*,, calculate D with its dephasing that is updated at the 3rd _FlowIn addition, if know T2 according to complex phase ^*, then can generate the signal of the TE arbitrarily of complex phase, therefore obtain complex phase with the identical TE of dephasing.That is,, can access the image that has only flow effect different according to identical T2 alleviation effects and susceptibility effect.

Figure 16 represents an example of many echoes of GRE sequential at this moment.

(B-2-2-2-2) situation of 2 dephasing TE of collection and 1 complex phase

The same with above-mentioned (B-2-2-1-2), 2 points of the dephasing that TE is different calculate T2 according to initial b value is identical ^*In addition, according to this T2 ^*Complex phase with the 3rd calculates D _FlowIn addition, if know T2 according to dephasing ^*, then can generate the signal of the TE arbitrarily of dephasing, therefore obtain dephasing with the identical TE of complex phase.That is, relax (T2 relaxation) effect and susceptibility effect, can access the image that has only flow effect different according to identical T2.

(B-2-2-3) 4 above methods

Respectively dephasing, complex phase are all collected more than 2, obtained T2 according to it ^*Image with identical TE.At unknown number is 2, is least squqre approximation under the situation more than 4.Certainly if necessary, then also can calculate M0, the T2 of unknown parameter or D etc.

Figure 17 is the figure of an example of the data collection in 4 methods of expression, collects the A relevant with TE=TE1 respectively _Re(TE1), the A relevant with TE=TE2 _De(TE2), the A relevant with TE=TE3 _Re(TE3), the A relevant with TE=TE4 _De(TE4).

In addition, the above various time series patterns that illustrated any one down, the TE of many echoes all is set, make to be included in T2 ^*The TE (=T2 of the optimum that uses during calculating ^*).T2 at object ^*Long (time lengthening, SNR prolong), or too short (do not add RF, leaning magnetic field do not occur, sufficient b value etc. do not occur) are difficult to be provided with under the situation of optimal T E, and the image of the TE arbitrarily that can make according to calculating makes TE=T2 ^*Image.

In addition, when phase calculation, it is desirable to all not turn back in all cases, or revise and turn back.Under many echoes of GRE, the TE of complex phase and dephasing does not need consistent scrupulously yet, if two TE are fully approaching, and T2 ^*Difference little, then can show to sxemiquantitative.Sequential also not only can be GRE, also can change on 1 time RF excitation back number stage ground under many shooting EPI (multi-shot echo planar imaging) of actual effect TE the k space segmentation is a plurality of sections etc., suitably short timeization and high-resolutionization is controlled.

In addition,, exist in the tissue of water and fat, importantly water and fat are set to same phase in mixing for TE.To be shown ΔΦ=n2 π γ δ B with the chemical phase meter of compiling the material that moves (chemical shift) δ ppm based on the water (proton) of static magnetic field strength ₀TE.Its condition that becomes same phase is that n is an integer, and therefore δ Φ=n2 π can be set to TE=n/ (γ δ B ₀) multiple.In brain essence, almost there is not fat, therefore almost no problem, but in voxel, mix in the bone marrow and abdominal organs that has water and fat, occur the situation of problem, so this condition is essential.If establish γ=42.6MHz/T, establish γ=3.6ppm and B for fat for water ₀=1.5T, then TE=n4.3ms.And then, there is the different material of susceptibility if also mix in external voxel at fat, then can produce phase contrast, but the chemical deviation that produces because of oxygen concentration is about δ=0.1ppm, suitably selects TE, quantitative para meter is the T2 of amplitude ^*Also almost no problem.Carrying out under the situation of quantification problem being arranged scrupulously according to phase place, therefore can be as required, it is known establishing δ, obtains based on the phase place of this effect and revises.

(B-3) image reconstruction

In step Sc2, computing unit 11 uses each data that suitably adopt above such the whole bag of tricks to collect, and carries out known reconstruction processing, reconstructs thus that m opens the dephasing image and n opens the complex phase image.In addition, the value of m and n all is to comprise 0 integer, and determines according to the method for data capture that is adopted.

(B-4) calculating of analytical parameters image

In step Sc3, computing unit 11 uses the 1～m that reconstructs to open the dephasing image and 1～n opens the complex phase image, the computational analysis parametric image.

Figure 18 is the figure of notion of the computing of expression analytical parameters image.

Computing unit 11 uses dephasing image and complex phase image, carries out flow parameter computing P1, calculates D thus _Flow Image.Computing unit 11 uses dephasing image and complex phase image, carries out the susceptibility calculation of parameter and handles P2, calculates T2 thus ^*Image and Δ χ image.Computing unit 11 uses dephasing image, complex phase image and T2 ^*Image carries out any TE image and makes processing P3, calculates thus and any relevant dephasing image and complex phase image of TE.

Below, the object lesson of the computing of the explanation analytical parameters image corresponding respectively with above-mentioned various methods of data capture.

(B-4-1) 2 methods

(B-4-1-1) situation of 2 of dephasings

(a) computing unit 11 according to the amplitude image of the TE=TE1 relevant with the dephasing of same b value as the amplitude image of A1 (TE1) and TE=TE2 as A2 (TE2), according to following formula (22) and (23), calculate T2 respectively ^*And K _De

T2 ^*＝(TE2-TE1)/ln[A _de(TE1)/A _de(TE2)] …(22)

K _de＝A _de(TE1)/exp[-TE1/T2 ^*] …(23)

(b) computing unit 11 according to following formula (24) and (25), calculates dephasing amplitude and phase place at any TE respectively.

A _de(TE)＝K _de?exp[-TE/T2 ^*] …(24)

Φ _de(TE)＝(TE/TE1)Φ _de(TE1) …(25)

(B-4-1-2) situation of 2 of complex phases

(a) computing unit 11 according to the amplitude image of the TE=TE1 relevant with the dephasing of same b value as the amplitude image of A1 (TE1) and TE=TE2 as A2 (TE2), according to following formula (26) and (27), calculate T2 respectively ^*And K _Re

T2 ^*＝(TE2-TE1)/ln[A _re(TE1)/A _re(TE2)] …(26)

K _re＝A _re(TE1)/exp[-TE1/T2 ^*] …(27)

(b) computing unit 11 according to following formula (28) and (29), calculates dephasing amplitude and phase place at any TE respectively.

A _re(TE)＝K _re?exp[-TE/T2 ^*] …(28)

Φ _re(TE)＝(TE/TE1)Φ _re(TE1) …(29)

That is, be suitable for the formula that the subscript de in (B-4-1) is replaced into re.

(B-4-2) 3 methods

(B-4-2-1) situation of 2 complex phase TE of collection and 1 dephasing TE

Figure 19 represents the flow process of the processing under this situation.

(a) in step Sd1, computing unit 11 is according to the amplitude image A of the TE=TE1 relevant with complex phase _Re(TE1) and the amplitude image A of TE=TE2 _Re(TE2), according to following formula (30) and (31), calculate T2 respectively ^*And K _Re

T2 ^*＝(TE2-TE1)/ln[A _re(TE1)/A _re(TE2)] …(30)

K _re＝A _re(TE1)/exp[-TE1/T2 ^*] …(31)

At this, according to the T2 that obtains ^*, obtain T2 ^*Image.

(b) in step Sd2, computing unit 11 for example makes the amplitude image A of the TE=TE3 relevant with complex phase as shown in Figure 20 according to following formula (32) _Re(TE3).In addition, in step Sd3, computing unit makes phase image Φ re (TE3) according to formula (33) under the situation of the background phase that does not exist with ... TE, under the situation that the background phase that does not exist with ... TE is arranged, make phase image Φ re (TE3) according to formula (34).

A _re(TE3)＝K _re?exp[-TE3/T2 ^*] …(32)

Φ _re(TE3)＝(TE3/TE1)Φ _re(TE1) …(33)

Φ _re(TE3)＝{TE3/(TE2-TE1)}{Φ _re(TE2)-Φ _re(TE1)} …(34)

In addition, in step Sd2 and Sd3, computing unit 11 also can make any one the amplitude image picture and the phase image of complex phase of arbitrary value that TE is not TE1, TE2, TE3.Can be updated to TE3 in above-mentioned formula (25)～(27) by the TE that will wish arbitrarily calculates and realizes.

(c) in step Sd4, computing unit 11 is according to the amplitude image A of TE=TE3 _Re(TE3), A _De(TE3), according to following formula (35) and (36), calculate flow dispersion coefficient D _FlowImage.

A _flow＝A _de(TE3)/A _re(TE3) …(35)

D _flow[mm ²/sec]＝-ln[A _flow]/b _de …(36)

(d) in step Sd5, computing unit 11 calculates blood vessel and B ₀Orientation angle θ.

(e) and then, in step Sd5, computing unit 11 calculates Δ χ [ppm] according to the phase image of the complex phase of θ, TE=TE3 according to following formula (37).

Δ _χ[ppm]＝-Φ _re(TE3)/{2πγB ₀(cos ²θ-1/3)TE3} …(37)

At this, obtain Δ χ image according to the Δ χ that obtains.

(f) in step Sd6, computing unit 11 makes the amplitude image picture of the dephasing of any TE.

The A that use is obtained according to formula (35) _Flow, calculate the amplitude image picture of any TE of dephasing according to following formula (38).

A _de(TE)＝A _re(TE)A _flow ...(38)

In step Sd7, computing unit 11 uses Φ de (TE3), calculates the phase image of any TE of dephasing according to following formula (39).Can only under the situation of the background phase that does not exist with ... TE, calculate.

Φ _de(TE)＝(TE/TE3)Φ _de(TE3) …(39)

In addition, also can only calculate the various parameters of in above-mentioned (c)～(f), obtaining in the case of necessary.

(B-4-2-2) situation of 2 dephasing TE of collection and 1 complex phase TE

Figure 21 represents the flow process of the processing under this situation.

(a) in step Se1, computing unit 11 is according to the amplitude image A of the TE=TE1 relevant with dephasing _De(TE1) and the amplitude image A of TE=TE2 _De(TE2), according to following formula (40) and (41), calculate T2 ^*And K _De

T2 ^*＝(TE2-TE1)/ln[A _de(TE1)/A _de(TE2)] …(40)

K _de＝A _de(TE1)/exp[-TE1/T2 ^*] …(41)

At this, according to the T2 that obtains ^*Obtain T2 ^*Image.

(b) in step Se2, computing unit 11 is according to following formula (42), and is such as shown in figure 22, makes the amplitude image A of the TE=TE3 relevant with dephasing _De(TE3).In addition, in step Se3, computing unit 11 makes phase image Φ according to following formula (43) _De(TE3).

A _de(TE3)＝K _de?exp[-TE3/T2 ^*] …(42)

Φ _de(TE3)＝(TE3/TE1)Φ _de(TE1) …(43)

In addition, in step Se2 and step Se3, computing unit 11 also can make any one the amplitude image picture and the phase image of dephasing of arbitrary value that TE is not TE1, TE2, TE3.Can be updated to TE3 in above-mentioned formula (42) and (43) by the TE that will wish arbitrarily calculates and realizes.

(c) in step Se4, computing unit 11 is according to the amplitude image A of TE=TE3 _Re(TE3), A _De(TE3), according to following formula (44) and (45), calculate flow dispersion coefficient D _FlowImage.

A _flow＝A _de(TE3)/A _re(TE3) …(44)

D _flow[mm ²/sec]＝-ln[A _flow]/b _de …(45)

(d) in step Se5, computing unit 11 calculates blood vessel and B ₀Aspect angle θ.

(e) and then in step Se5, computing unit 11 calculates Δ χ [ppm] according to the phase image of θ, TE=TE3 according to following formula (46).

Δ _χ[ppm]＝Φ _re(TE3)/{2πγ?B ₀(cos ²θ-1/3)TE3} …(46)

At this, obtain Δ χ image according to the Δ χ that obtains.

(f) in step Se6, computing unit 11 makes the amplitude image picture of the complex phase of any TE.

The A that use is obtained according to formula (44) _Flow, calculate the amplitude image picture of any TE of complex phase according to following formula (47).

A _re(TE)＝A _de(TE)/A _flow …(47)

In step Se7, computing unit 11 uses Φ _Re(TE3), calculate the phase image of any TE of complex phase according to following formula (48).Can only under the situation of the background phase that does not exist with ... TE, calculate.

Φ _re(TE)＝(TE/TE3)Φ _re(TE3) …(48)

In addition, also can only calculate the parameter of in above-mentioned (c)～(f), obtaining in the case of necessary.

And then, under complex phase and dephasing are respectively situation more than 3, unknown parameter is set in the model, calculate by method of least square.K _Re, K _De, T2 ^*Can use the model of 1 time decaying exponential function, Δ χ can use the model of 1 function.

As described above, calculate at least each one complex phase image and dephasing image (comprising amplitude image picture and phase image respectively), T2 respectively ^*Image, Δ χ image and D _FlowImage etc.In addition, below, these images are generically and collectively referred to as the analytical parameters image.

In addition, also can not use many echoes, and each echo is collected and image conversion respectively one by one.Perhaps, also can carry out the 2D collection of cutting into slices more, collect based on the body (volume) of 3DFT method etc.As pulse sequence, also can use asymmetric spin echo (ASE) method to replace GRE.

(B-5) the synthetic processing and the demonstration of analytical parameters image

After calculating various analytical parameters images, these analytical parameters picture original ground can be shown and observe.In addition, also can show A _Flow, Φ _Flow, Δ _FlowEtc. parameter self.

And then, for auxiliary diagnosis, in step Sc4, computing unit 11 can make various analytical parameters images the usefulness color separated the composograph of 2D, former state ground shows the 2D image.Can only carry out the synthetic processing of this step Sc4 where necessary.

Perhaps, special in being under the situation of purpose with the blood-vessel image, in step Sc5, computing unit 11 carries out 3D and handles for blood vessel being shown as successive pipe.Representational is maximum projection (MIP) or minima projection (minIP).Computing unit 11 also can generate in step Sc5 on the basis of a plurality of 3D renderings, uses these a plurality of 3D renderings in step Sc6, merges (fusion) and handles.

(B-5-1) phase place is synthetic handles and demonstration

Illustrate according to the complex phase image of any TE and the function that the dephasing image makes the phase place composograph.

(a) each makes common MR image: So=A at complex phase and dephasing ₀Exp[i Φ ₀], applied the MR image of low-pass filtering: S ₁=A ₁Exp[i Φ ₁].

(b) phase place pseudomorphism correction

According to following formula (49), from the phase diagram (map) of the MR image of complex phase, deduct the phase diagram of the image that applies low-pass filtering.

Φ＝Φo-Φ _l＝arg[S]-arg[S ₁] …(49)

After the calculating of carrying out this formula (49), skip to revise by phase place and converge to-processing of π＜Φ＜=π.That is, if Φ be-below the π, then Φ is replaced into Φ+π, under the Φ situation bigger, Φ is replaced into Φ-π than π.

In addition, also can replace formula (49), and calculate Φ according to following formula (50).

Φ-arg[S/S ₁] …(50)

(c) phase mask (phase masking)

Make any one mask M of symmetric form asymmetric or shown in Figure 24 shown in Figure 23, obtain the heavy long-pending I of n of amplitude image picture and mask M according to following formula (51).

I＝A×M ⁿ …(51)

In addition, make A, make M according to the phase place of complex phase according to the phase place of dephasing.

Thus, can not have to skip or phase mask mobile and the phase place elimination that susceptibility produces because of phase place.

(B-5-2) colored synthetic the processing and demonstration

With color the above-mentioned analytical parameters image that obtains is like that carried out color separation and merge (fusion) demonstration.For example, the A of mobile composition _Flow, Φ _Flow, and D _FlowDominant trait ground becomes big in vein and tremulous pulse.In vein or stationary, the T2 of susceptibility composition ^*Become big with Δ χ in the part of hemorrhage grade.Therefore, the image setting by the mobile composition that image shown in Figure 25 21 is such is red, and the image setting of the susceptibility composition that Figure 22 is such is that cyan etc. is painted like that and carried out that colour is synthetic to be handled, and for example fusion is shown as image 23.At this moment show be physically mobile composition (redness) and the composograph of susceptibility composition (cyan).Under the situation of the image of only representing blood vessel, represent tremulous pulse with redness, represent vein with purple.Susceptibility hemorrhage, stationary that the susceptibility component portion also comprises is not the pseudomorphism of 0 part, therefore can merge demonstration after the vein that carries out threshold process etc. is extracted out as required.

In addition, make according to following formula (52) or (53) and from image 21 and image 22, to have extracted tremulous pulse and venous image 24 out, and this image 24 and image 22 are carried out colour synthesize, also can access image 23 thus.

A _flow＝A _de/A _re …(52)

Φ _flow＝Φ _de-Φ _re …(53)

According to the ratio of composition that flow, decide color mixture with the susceptibility composition.In above-mentioned color assignment example, the variation of expression redness → purple → cyan, but many more near the mobile composition of red expression, represent that near cyan the susceptibility composition is many more.When illness such as cerebral infarction, might not be corresponding with each tremulous pulse and vein, become the index of reflection oxygen metabolism state.Color assignment has more than and is limited to this, also can be can correlatedly to make up arbitrarily.The method of depicting tremulous pulse is also arranged in TOF-MRA, but be to depict slow tremulous pulse on the principle.In the method, owing to use signal attenuation or phase place to change, so the secondary bloody path of side that can also depict arteriole, spiral from the top can provide the important clinically information towards the diagnosis of cerebral infarction etc. based on dephasing.In addition,, then thrombosis or hemorrhage etc. information can be obtained simultaneously, therefore information important when working out treatment plan can be provided according to the susceptibility effect if be set to a certain degree long TE.

In addition, as image 21, can utilize the amplitude phase place composograph and the D of dephasing amplitude image picture, dephasing phase image, dephasing _FlowImage etc.As image 22, can utilize the amplitude phase place composograph and the T2 of complex phase amplitude image picture, complex phase phase image, complex phase ^*Image etc.

(B-5-3) 3D handles and shows

In the amplitude image picture of dephasing, tremulous pulse and vein all become low image value with respect to surrounding tissue, so minIP is fit to.In the amplitude image picture of complex phase, vein is a low signal, so minIP is fit to, but because TOF effect tremulous pulse becomes high signal, so also can utilize MIP simultaneously.Also can extract surface etc. out and utilize body to play up or surface rendering.In addition, observe in hope under the situation of original image signal, it also is effective merely using section conversion (MPR) according to purposes.Merge to show to be 2D as described above, but also can after making 3D rendering, carry out.

In addition, can carry out the demonstration of various images, but show in browser device that also can be externally etc. by display 13.

As mentioned above, according to embodiment 2, can separate the mobile effect of blood flow etc. and carry out quantification.In addition, according to this quantification result, can provide medical diagnosis Useful Information and image.

According to embodiment 2,, can make the parameter that does not exist with ... device category and sequential for susceptibility and mobile.Therefore, become common data base, can easily important opinion be stored as evidence.

According to embodiment 2,, can separate tremulous pulse and vein by combination complex phase and dephasing.

According to embodiment 2, compare with the method for collecting complex phase and dephasing respectively, by using many echoes, can in once collecting, collect both sides' image, therefore acquisition time is short, and can ignore the time difference between a plurality of images, therefore more is difficult to produce the influence of motion.

According to embodiment 2, owing to use 2 images, so can suppress the TOF effect of the blood of fast flow velocity.For blood, can access and only exist with ... susceptibility or mobile contrast.

According to embodiment 2, can depict the secondary bloody path of side.

According to embodiment 2, can separate susceptibility and mobile.

According to embodiment 2, in the amplitude image picture that obtains with dephasing,, has extremely important speciality by optionally depicting the such method of blood vessel endoporus etc.

Present embodiment can have following so various distortion to implement.

(a) in embodiment 1, also can photograph with in order to generate WB image and the different types of image of BB image that mixes the MRA image and use, generation with this image with mix the image that the MRA image has synthesized.As above-mentioned different types of image, for example the image of having made a video recording according to the SWI method is useful.That is, above-mentioned such mixing MRA image that generates is the WB image, and mainly depicts tremulous pulse, therefore by will as the SWI image of expression venous BB image with mix the MRA image and synthesize (fusion), can access color rendering tremulous pulse and venous image are shown.Distribute different colors to mixing the MRA image with the SWI image respectively, can also generate coloured image.In addition, in the SWI method, obtain T2 being provided with ^*Strengthen on the basis of needed echo time of image, under the pulse sequence that comprises the GRE system that is used to eliminate the dispersive mobile compensating for tilt magnetic field pulse of mobile phase place, carry out data collection.

In addition, in this case,, then the prolongation of photography time can be suppressed little if carry out the collection of 3 echoes by many echo methods.For example, for the TE that establishes under the situation that static magnetic field strength is 1.5T, be less than 10 in the TOF FAXIA, be 20 in the FS-BB FAXIA, be 40 in the SWI FAXIA.In addition, for SWI,, it is desirable to GMN is made as the complex phase type in order to suppress tremulous pulse.In addition, be about 40ms if in the example of 2 above-mentioned echoes, establish the TE of FS-BB method, then mix and have tremulous pulse and vein, strengthen but can carry out blood vessel by the calculating between 2 echoes.

(b) in embodiment 1, distributing on the basis of different colors to WB image and BB image respectively, by merging, also can generate and mix the MRA image.That is,, distribute the redness of per 8 bits and green to show to WB image and BB image, then overlapping demonstration the under the state of having preserved color if for example use RGB24 (8 * 3) bit.Like this, becoming the image of the information that has reflected each mobile speed and oxygen concentration, is useful.If for example in 2 images of WB image and BB image, about one-sided the secondary bloody path of side arranged, then the blood vessel redness of the fast side of flow velocity is many, the blood vessel green of a slow side is many.In addition, and if then comprise the SWI image as described above, then also can for example distribute cyan to it.Thus, represent vein with cyan.

(c) in embodiment 1, can use contrast agent to obtain WB image and BB image.If the different T1W of TE, T2 are arranged under GRE ^*2 echoes of W, then the 1st echo becomes WB owing to the T1 of contrast agent shortens effect, and the 2nd echo is owing to the susceptibility effect becomes BB.

(d) in embodiment 1, the sequential that is used to obtain WB image and BB image and SWI image has more than and is limited to GRE, also can use FSE system, EPI (echo planarimaging) to be or they combination and the collection that hockets.

(e) in embodiment 1, illustrated according to WB image and BB image to generate the situation of mixing MRA image (blood flow picture).But also can generate and mix MRA image (blood flow picture) according to multiple different a plurality of WB images or multiple different a plurality of BB images.For example, also the non-radiography MRA image that can generate according to the data of collecting under the pulse sequence of the TOF method that applies presaturation (presaturation) pulse to the position different with region-of-interest, the T1 that uses contrast agent to obtain strengthen image, generate the mixing MRA image of multiple different a plurality of WB images.In addition, also can according to comprise be used to strengthen flow because of the tremulous pulse of region-of-interest and venous the data generation of collecting under the pulse sequence of GRE system of the dephasing leaning magnetic field pulse that the signal that produces reduces the MRA image, be provided with in order to obtain T2 ^*Strengthen on the basis of needed echo time of image the MRA image that generates according to the data of under the pulse sequence that comprises the GRE system that is used to eliminate the dispersive mobile compensating for tilt magnetic field pulse of mobile phase place, collecting, generate the mixing MRA image of multiple different a plurality of BB images.

Under the situation between the WB image, because contrast C 1, the C2 of 2 WB images are C1＞0, C2＞0, so can be suitable for to former state formula (13) and (13 ').In addition, under the situation between the BB image, the contrast C 1 of 2 BB images, C2 are C1＜0, C2＜0, so can be suitable for to former state formula (13) and (13 ').

(f) in embodiment 1, also can replace mixing MRA MIP image, and generate the mixing MRA3 dimension image of playing up generation by body.

(g) in embodiment 2, under the situation that makes the phase mask image, also can make up the phase place of the amplitude and the complex phase of dephasing, or the phase place of combination dephasing and the amplitude of complex phase.Thus, because the susceptibility and the mobile counteracting that can not produce phase place so the veneous signal of the phase mask image of amplitude further reduces, have improved tremulous pulse and venous separating power.

(h) in embodiment 2, also can be with the purpose that rises to of camera time and SNR, to each frequency shift TR or the TE in the k space.For example when collecting, use the short TE of low frequency, middle TE to collect to high frequency length based on sequential.Change TE smoothly therebetween.Thus, because of low-frequency component is that the inhomogeneous phase place that produces of overriding magnetostatic field diminishes, therefore reduced pseudomorphism.Under the situation of phase place, irrelevant with longitudinal magnetization, so TR also can be the shortest.In addition, the kind of sequential can be GRE (FE) type, can be suitable for any one of many echoes and 1 echo, and k-space trajectory also can be any one of spin warp, spiral or EPI etc.Figure 26 represents the example of the variation of the TR corresponding with k, TE.

In addition, the MR imaging apparatus of various embodiments of the present invention comprises various forms of MR imaging apparatus shown below.

(a) MR imaging apparatus of first form and then possess the display unit that shows the image shown in the 3rd data.

(b) each collects first data and second data to the unit of obtaining in the MR imaging apparatus of first form at a plurality of sections respectively, generation unit generates the 3rd data at each of a plurality of sections, this MR imaging apparatus also possesses: according to three data relevant with at least a portion section in a plurality of sections, generate the unit of 3 d image.

(c) MR imaging apparatus of first form also possesses: according to first and second data any one, make the unit of paying close attention to the regional corresponding mask data of the object of observation of organizing with conduct; According to mask data, be only limited to the unit of regionally the 3rd data being handled of the object of observation.

(d) unit of obtaining in the MR imaging apparatus of first form uses FSE method and any one of EPI method or their combination, obtains first and second data respectively.

(e) scanning of first in the MR imaging apparatus of the 3rd form is carried out data collection under the pulse sequence of the TOF method that applies the presaturation pulse to the position different with region-of-interest, contrast agent is used in second scanning, is being used to obtain to carry out data collection under the pulse sequence that T1 strengthens image.

(f) first in the MR imaging apparatus of the 4th form scanning is carried out data collection under the pulse sequence of gtadient echo system of the dephasing leaning magnetic field pulse that the signal that causes reduces comprising to be used to strengthen flow because of the tremulous pulse of region-of-interest and venous, and second scanning is being set to obtain T2 ^*Strengthen the needed echo time of image and comprise under the pulse sequence of the gtadient echo system that is used to eliminate the dispersive mobile compensating for tilt magnetic field pulse of mobile phase place, carry out data collection.

(g) collector unit in the MR imaging apparatus of the 5th form is alternately collected the magnetic resonance signal of dephasing and complex phase according to row unit of 1 in the 3D k space or face unit under the same echo time.

(h) the Look-Locker method of the collector unit in the MR imaging apparatus of the 5th form by collecting continuously with echo-planar imaging (EPI) method after 1 RF excitation collected the magnetic resonance signal of dephasing.

(i) collector unit in the MR imaging apparatus of the 5th form is set to T2 with one in a plurality of echo times ^*

(j) reconfiguration unit in the MR imaging apparatus of the 5th form is according to based on the magnetic resonance signal of collecting respectively in a plurality of echo times and a plurality of dephasing images or a plurality of complex phase image of reconstruct, dephasing image or complex phase image that the reconstruct echo time different with a plurality of echo times is correlated with.

(k) MR imaging apparatus of the 5th form also possesses: generate the expression quantification the generation unit of quantification image of characteristic; According to reconstruct the dephasing image and at least one of complex phase image, the characteristic relevant with subject carried out the second quantification unit of quantification, generation unit synthesizes the image of representing the unitary quantification result of quantification, the image of representing the result of the unitary quantification of second quantification, generates the quantification image.

(l) collector unit in the MR imaging apparatus of the 5th form is collected magnetic resonance signal according to 2 dimensions or 3 dimensions.

(m) collector unit in the MR imaging apparatus of the 5th form uses the gtadient echo method, collects the magnetic resonance signal of same echo time at each of complex phase and dephasing.

(n) collector unit in the MR imaging apparatus of the 5th form uses asymmetric spin-echo method, collects the magnetic resonance signal of same echo time at each of complex phase and dephasing.

(o) MR imaging apparatus of the 5th form also possesses: generate the expression quantification the generation unit of quantification image of characteristic, this generation unit generates that a plurality of amplitudes are independent, phase place separately or the sectioning image that synthesized of amplitude phase place, and handle by 3D, generate the quantification image of 3D based on these a plurality of sectioning images.

(p) generation unit in the MR imaging apparatus of above-mentioned (o) is made as different sequential kinds with amplitude and phase place.

(q) generation unit in the MR imaging apparatus of above-mentioned (p) uses the amplitude of dephasing, uses the phase place of complex phase.

(r) MR imaging apparatus of the 5th form also possesses: generate the expression quantification the generation unit of quantification image of characteristic, this generation unit generates the phase place composograph of complex phase image and dephasing image.

(s) MR imaging apparatus of the 5th form also possesses: generate the expression quantification the generation unit of quantification image of characteristic, this generation unit to represent quantification respectively a plurality of quantification images of characteristic between or carried out colored synthetic image based on the image and the quantification image of complex phase image or dephasing image.

(t) the quantification image of the mobile composition that generated the expression quantification of the generation unit in the MR imaging apparatus of above-mentioned (q), carried out colored synthetic image based on the image of the susceptibility composition of complex phase image or dephasing image.

The present invention has more than and is limited to above explanation and embodiment, in the scope that does not break away from its aim various distortion and combination can be arranged, and these distortion and combination is also contained among the present invention.

Claims (25)

1. MR imaging apparatus is characterized in that comprising:

Respectively at the image of the same area of same subject, obtain the unit of obtaining of the signal of the signal of paying close attention to tissue first data higher, above-mentioned concern tissue second data lower respectively than background than background;

According to above-mentioned first data and above-mentioned second data, generate the generation unit of above-mentioned concern tissue three data all higher than above-mentioned first and second data with respect to the contrast of background.

2. MR imaging apparatus according to claim 1 is characterized in that:

Above-mentioned region-of-interest is a blood vessel.

3. MR imaging apparatus according to claim 1 is characterized in that:

Above-mentioned generation unit is after having carried out weighting to the signal value shown at least one of above-mentioned first and second data and having handled, and above-mentioned first and second data according to having carried out after this weighting is handled generate above-mentioned the 3rd data.

4. MR imaging apparatus according to claim 1 is characterized in that:

Above-mentioned generation unit by respectively to above-mentioned first and second data of a plurality of position calculation in the above-mentioned zone separately at the difference of the signal value shown in the same position in the above-mentioned zone, and generate above-mentioned the 3rd data.

5. MR imaging apparatus according to claim 4 is characterized in that also comprising:

According to the relation of above-mentioned first data and above-mentioned second data, be provided with weighting ratio the unit is set, wherein

Above-mentioned generation unit is after having carried out weighting according to aforementioned proportion to the signal value of above-mentioned first and second data shown in respectively and having handled, at the above-mentioned difference of above-mentioned first and second data computation of having carried out after this weighting is handled.

6. MR imaging apparatus according to claim 5 is characterized in that:

Above-mentioned be provided with the unit be provided with aforementioned proportion make the signal of above-mentioned the 3rd data to noise ratio for maximum.

7. MR imaging apparatus according to claim 4 is characterized in that:

Above-mentioned first data and above-mentioned second data are collected at each of a plurality of sections respectively in the above-mentioned unit of obtaining,

The above-mentioned position that the slice direction of unit and above-mentioned section is set is provided with aforementioned proportion accordingly.

8. MR imaging apparatus according to claim 1 is characterized in that:

The above-mentioned unit of obtaining uses the gtadient echo method, obtains above-mentioned first and second data respectively.

9. MR imaging apparatus according to claim 1 is characterized in that:

The above-mentioned unit of obtaining is obtained above-mentioned first data relevant with same position and above-mentioned second data respectively by a RF excitation.

10. MR imaging apparatus according to claim 9 is characterized in that:

The above-mentioned unit of obtaining uses gradient moment zero-bit (GMN) to obtain above-mentioned first data, obtain added the dephasing gradient data as above-mentioned second data.

11. MR imaging apparatus according to claim 1 is characterized in that also comprising:

From reducing the low-frequency component suitable with background signal by above-mentioned obtaining each of above-mentioned first and second data that obtain the unit, or the spatial filter of the enhancing radio-frequency component suitable with blood vessel, wherein

Above-mentioned generation unit generates above-mentioned the 3rd data according to above-mentioned first and second data that reduced by above-mentioned spatial filter behind the above-mentioned low-frequency component.

12. MR imaging apparatus according to claim 1 is characterized in that:

The above-mentioned unit of obtaining injects contrast agent to above-mentioned region-of-interest, obtains the above-mentioned first and second data both sides by many echo methods.

13. a MR imaging apparatus is characterized in that comprising:

Respectively at the image of the same area of same subject, obtain the unit of obtaining of the signal of the signal of paying close attention to tissue first data higher, above-mentioned concern tissue second data lower respectively than background than background;

Generate expression and distribute different colours and the generation unit of the 3rd data of synthetic image to the image shown in image shown in above-mentioned first data and above-mentioned second data respectively.

14. a MR imaging apparatus is characterized in that comprising:

At the region-of-interest of subject, carry out the scanning element of carrying out first scanning of data collection, carrying out second scanning of data collection according to the pulse sequence different of the signal that is used to obtain above-mentioned blood vessel second view data higher than background parts with above-mentioned first scanning according to the pulse sequence of the signal that is used to obtain blood vessel first view data higher than background parts;

According to above-mentioned first view data and above-mentioned second view data, generate the generation unit of above-mentioned blood vessel three view data all higher than above-mentioned first and second data with respect to the contrast of background parts.

15. a MR imaging apparatus is characterized in that comprising:

At the region-of-interest of subject, carry out the scanning element of carrying out first scanning of data collection, carrying out second scanning of data collection according to the pulse sequence different of the signal that is used to obtain above-mentioned blood vessel second view data lower than background parts with above-mentioned first scanning according to the pulse sequence of the signal that is used to obtain blood vessel first view data lower than background parts;

According to above-mentioned first view data and above-mentioned second view data, generate the generation unit of above-mentioned blood vessel three view data all higher than above-mentioned first and second view data with respect to the contrast of background.

16. a MR imaging apparatus is characterized in that comprising:

Collection is from the collector unit of the magnetic resonance signal of subject emission;

According to the above-mentioned magnetic resonance signal of collecting, the reconfiguration unit of dephasing image of each reconstruct and complex phase image at least;

According to the above-mentioned dephasing image that reconstructs and the both sides of above-mentioned complex phase image, the characteristic relevant with above-mentioned subject carried out the quantification unit of quantification.

17. MR imaging apparatus according to claim 16 is characterized in that also comprising:

Generate the above-mentioned quantification of expression the generation unit of quantification image of characteristic.

18. MR imaging apparatus according to claim 17 is characterized in that also comprising:

The unit that shows above-mentioned quantification image.

19. MR imaging apparatus according to claim 17 is characterized in that:

Above-mentioned collector unit uses many echo methods of gtadient echo (GRE), collects above-mentioned magnetic resonance signal.

20. MR imaging apparatus according to claim 19 is characterized in that:

Above-mentioned collector unit is collected the magnetic resonance signal with each relevant dephasings of a plurality of echo times respectively, perhaps collect magnetic resonance signal respectively with each relevant complex phases of a plurality of echo times, perhaps collect the magnetic resonance signal of the dephasing relevant with at least one echo time, the magnetic resonance signal of the complex phase relevant with at least one other echo time, perhaps collect the magnetic resonance signal of the dephasing relevant and the magnetic resonance signal of relevant complex phase with 2 echo times with echo time, perhaps collect the magnetic resonance signal of the complex phase relevant and the magnetic resonance signal of relevant dephasing, the perhaps magnetic resonance signal of the collection dephasing relevant with 2 above echo times with 2 echo times with 1 echo time, the magnetic resonance signal of the complex phase relevant with other at least 2 above echo times.

21. MR imaging apparatus according to claim 16 is characterized in that:

It is same phase that above-mentioned collector unit is provided with feasible magnetic resonance signal from water and fat of echo time.

22. MR imaging apparatus according to claim 16 is characterized in that:

Above-mentioned quantification unit carries out quantification to the flow effect in the above-mentioned subject.

23. MR imaging apparatus according to claim 22 is characterized in that:

Above-mentioned quantification unit is in order to carry out quantification to above-mentioned flow effect, calculates the phase place coefficient of dispersion of the dispersive degree of phase place at random that expression produces because of various flow velocity or to flowing of various direction.

24. MR imaging apparatus according to claim 16 is characterized in that:

Above-mentioned quantification unit is by calculating the amplitude ratio or the phase contrast of above-mentioned dephasing image and above-mentioned complex phase image, and the characteristic relevant with above-mentioned subject carried out quantification.

25. MR imaging apparatus according to claim 16 is characterized in that:

Under the low situation of the frequency of above-mentioned collector unit in the k space, compare, be provided with circulation time or echo time short with high situation.

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