WO2005039646A1 - 磁気共鳴組織灌流画像法のための造影剤および装置 - Google Patents
磁気共鳴組織灌流画像法のための造影剤および装置 Download PDFInfo
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- WO2005039646A1 WO2005039646A1 PCT/JP2004/015948 JP2004015948W WO2005039646A1 WO 2005039646 A1 WO2005039646 A1 WO 2005039646A1 JP 2004015948 W JP2004015948 W JP 2004015948W WO 2005039646 A1 WO2005039646 A1 WO 2005039646A1
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- contrast agent
- magnetic resonance
- imaging
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- gas
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/5601—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution involving use of a contrast agent for contrast manipulation, e.g. a paramagnetic, super-paramagnetic, ferromagnetic or hyperpolarised contrast agent
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/41—Detecting, measuring or recording for evaluating the immune or lymphatic systems
- A61B5/411—Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K49/00—Preparations for testing in vivo
- A61K49/06—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations
- A61K49/18—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by a special physical form, e.g. emulsions, microcapsules, liposomes
- A61K49/1818—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by a special physical form, e.g. emulsions, microcapsules, liposomes particles, e.g. uncoated or non-functionalised microparticles or nanoparticles
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/026—Measuring blood flow
- A61B5/0263—Measuring blood flow using NMR
Definitions
- the present invention relates to a contrast agent used for diagnosis using a nuclear magnetic resonance (hereinafter, also referred to as “MR”) technique and a nuclear magnetic resonance imaging (hereinafter, also referred to as “MRI”) technique.
- MR nuclear magnetic resonance
- MRI nuclear magnetic resonance imaging
- the present invention relates to a contrast agent for nuclear magnetic resonance imaging capable of safely obtaining tissue perfusion information such as blood flow at various parts of a human body.
- the contrast agent of the present invention can be widely used in general animals, it is particularly effective in mammals, especially humans, and is extremely effective in diagnosing blood flow in humans having allergic diseases.
- a gadolinium (Gd) chelate preparation has conventionally been widely used as a contrast agent.
- a product with a product name of Magnevist registered trademark
- Magnevist registered trademark
- gadolinium contrast agents involve a considerable risk that their safety to the human body is not sufficient.
- gadolinium contrast agent may cause nausea even in a healthy person, and the ratio of 5,000 to 1 in 10,000 in an intensive care unit may be increased. It is known that serious injuries requiring treatment and deaths from gadolinium contrast agent administration occur in about one in 50,000 people. In Magnevist (R), 1.21% incidence of side effects, specifically nausea (0.29%), vomiting (0.13%), hot sensation (0.06%), Side effects such as measles (0.29%) have been reported. Serious side effects Shock, convulsive seizures, and anaphylactoid symptoms (dyspnea, pharyngeal laryngeal edema, facial edema), and three deaths have been identified so far.
- Subjects with allergic predisposition to allergic rhinitis, rash, rash, etc. (2) Bronchial asthma, allergy to parents and siblings Subjects with allergies predisposing to rhinitis, rash, rash, etc., (3) Subjects with a history of drug hypersensitivity, (4) Subjects with a history of convulsions, epilepsy and its predisposition, It states that it should be administered with caution to 5) the elderly and (6) infants and young children.
- Patent Documents 416 suggest that ribosomes can be used as MR contrast agents.
- no specific studies have been reported on specific MRI contrast agents, especially as contrast agents in tissue perfusion imaging.
- an ultrasonic diagnostic method is known as a method of measuring a state in a human body. This method measures the state of reflection of ultrasonic waves in the human body, and is based on the principle of measuring magnetic field changes based on the interaction between the magnetic field and the state of nuclei present in the body. The mechanism is completely different from resonance.
- Patent Documents 7 to 11 describe contrast agents suitable for such ultrasonic diagnosis.
- US Pat. No. 6,059,064 describes a composition for infusion of blood that forms microbubbles, comprising a physiologically acceptable material.
- Galactose is described as a specific example of the material. This composition is used to enhance the ultrasound image.
- Patent Document 8 describes a contrast agent for ultrasonic diagnostics comprising a surfactant and a non-surfactant solid substance and containing bubbles.
- Patent Document 9 describes a contrast agent for ultrasonic diagnostics containing a surfactant and a non-surfactant solid substance, and containing bubbles.
- Patent Document 10 describes small particles of galactose containing bubbles, which are used for ultrasonic manometry.
- Patent Document 11 discloses that fatty acids (for example, palmitic acid) and non-surface-active solids
- a contrast agent for ultrasonic diagnosis comprising (eg, galactose) is described.
- liposomes have only been studied as a contrast agent in tissue perfusion imaging by nuclear magnetic resonance, and there has been no study using other substances as contrast agents. In this field, it was still common sense to use gadolinium as a contrast agent.
- the contrast agent passes through fine capillaries and minimizes the adverse effects of interaction with the tissue, for example, as flexible as possible with ribosomes. It is thought that it should be.
- Patent document 1 Patent 3383954 (Claim 1, column 3, 32-50 lines)
- Patent Document 2 Japanese Translation of International Patent Application No. 7-505136 (Claim 1, page 2, lower right column, lines 4-1-24)
- Patent Document 3 Japanese Translation of International Patent Application No. 7-505137 (Claim 1, page 2, lower right column, lines 7-9)
- Patent Document 4 Japanese Translation of International Patent Application No. 9-510204 (Claim 1, Claim 2, Claim 8)
- Patent Document 5 Japanese Patent Application Laid-Open No. 10-505900 (Claim 29, Claim 31, 3 lines from the bottom of page 7, 2 lines from the bottom)
- Patent Document 6 Japanese Patent Application Laid-Open No. 11-501839 (Claim 1, Claim 11, page 16, line 6-8)
- Patent Document 7 JP-B-63-44731 (Claims 1, Claims 2 and 3 columns 35-44)
- Patent Document 8 Japanese Patent Publication No. 4 25934 (Claim 1)
- Patent Document 9 Japanese Patent Publication No. 4-17164 (Claim 1)
- Patent Literature 10 Tokiohei 3-500010 (Claim 20)
- Patent Document 11 Japanese Patent Publication No. 7-37394 (Claim 1)
- An object of the present invention is to provide a contrast agent for nuclear magnetic resonance diagnosis excellent in safety.
- a further object of the present invention is to provide a nuclear magnetic resonance diagnostic apparatus which can use such a highly safe contrast medium.
- the present invention provides a subject with extremely poor general condition, a subject with bronchial asthma, a subject with severe hepatic impairment, a subject with severe renal impairment, Subjects with allergies predisposed to rhinitis, rash, juniper, etc., subjects with allergies predisposed to bronchial asthma, allergic rhinitis, rash, juniper, etc. in their parents and siblings, drug sensitivity Can be administered to subjects with a history of illness, including those with a history of convulsions, subjects with convulsions, epilepsy and its qualities, the elderly, and young children * without concern for side effects An object is to apply an extremely safe contrast agent.
- a contrast agent for magnetic resonance tissue perfusion imaging comprising gas-containing fine particles mainly composed of sugar.
- the contrast agent according to item 1 wherein the sugar is galactose, and the content of the galatatose is 99% to 99.99% in the fine particles.
- a magnetic resonance imaging apparatus for imaging a blood flow containing the contrast agent according to item 1 above comprising: means for irradiating an RF pulse to excite a magnetic field in a body; An apparatus comprising: means for relaxing the magnetic field in the body until a predetermined time elapses after the irradiation is completed, collecting MR signals, and measuring a change in the magnetic field in the body due to the gas.
- the present invention provides a contrast agent for nuclear magnetic resonance diagnosis manufactured from a material harmless to the human body. Therefore, it becomes possible to perform a nuclear magnetic resonance diagnosis with virtually no side effects. Has a remarkable effect.
- FIG. 1 is a flowchart of an MRI measurement method using a contrast agent of the present invention.
- FIG. 3 is a graph showing a temporal change of an MR signal.
- FIG. 4 is a graph showing a temporal change of an MR signal.
- FIG. 5 is a schematic diagram showing an outline of a phantom used in Example 1.
- FIG. 6 is a graph showing the results of T2 * relaxation characteristics of Example 1.
- FIG. 7 is a graph showing a signal strength result and a signal strength image of Example 1.
- FIG. 8 is a graph and a phase image showing a result of a phase shift in Example 1.
- the term "contrast agent” refers to a contrast agent used for diagnosis using nuclear magnetic resonance (MR) technology and nuclear magnetic resonance imaging (MRI) technology.
- the magnetic resonance (MR) phenomenon is also called a nuclear magnetic resonance phenomenon (NMR), and there is a magnetic resonance diagnostic method (or a magnetic resonance imaging method or a magnetic resonance imaging method) (MRI) as a method of imaging it.
- MRI is synonymous with nuclear magnetic resonance diagnosis, nuclear magnetic resonance imaging, or nuclear magnetic resonance imaging.
- MR described in this specification includes all the concepts such as magnetic resonance, magnetic resonance phenomena, and nuclear magnetic resonance phenomena used as a Japanese translation of Magnetic Response in English.
- MRI includes all the concepts such as magnetic resonance imaging, magnetic resonance diagnostics, and magnetic resonance imaging, which are used as Japanese translations of Magnetic Resonance Imaging in English.
- Clinical MR devices generally use a magnetic resonance expression of hydrogen nuclei (also called protons). We use elephants. However, the magnetic resonance phenomenon is observed when either the number of protons or the number of neutrons is an odd nuclide, and can be applied to imaging.
- nuclides that cause magnetic resonance phenomena they may be described as hydrogen nuclei as a representative, but unless otherwise specified, they refer to all nuclides that cause magnetic resonance phenomena. Should be understood to include.
- MR magnetic resonance
- Magnetic resonance imaging unlike X-rays, does not use ionizing radiation! Similar to computed tomography (CT), MRI captures tomographic images of the body. Force MRI is performed on any scan plane (ie, transverse, coronal, sagittal, or oblique). And has the additional advantage of being able to capture images.
- CT computed tomography
- MRI Magnetic resonance imaging
- the use of MRI for diagnostics on the body is limited due to the toxicity of common gadolinium based contrast agents. As a result, it is often difficult to use MRI to discriminate target tissue from adjacent tissues without the appropriate drug.
- MRI uses a magnetic field, high-frequency energy, and a magnetic field gradient to capture an image of the body.
- Differences in contrast or signal intensity between tissues are T1 (longitudinal) relaxation time (time), T2 and T2 * (horizontal) relaxation value (time), tissue proton density (effectively free water content), and Reflects the effects of diffusion and flow of the molecules that make up the tissue.
- the difference between the T2 relaxation value and the T2 * relaxation value is due to the imaging method described later, i.e., the former is when the spin echo method is used, and the latter is the lateral relaxation observed when the gradient echo method is used. Value.
- T2 relaxation includes the concept of T2 * relaxation.
- the contrast agent is designed to change either Tl, ⁇ 2, or proton density, or any number of forces.
- the paramagnetic contrast agent In order to shorten the longitudinal (T1) and transverse ( ⁇ 2) relaxation values, the paramagnetic contrast agent has a small size within the main magnetic field. Including unpaired electrons acting as local magnets. Most paramagnetic contrast agents are often toxic metal ions. To reduce toxicity, these metal ions are generally chelated using ligands. Metal oxides, most notably acid oxide
- saccharide may be any of monosaccharides, oligosaccharides, and polysaccharides, and is preferably a monosaccharide.
- Preferred as the saccharide of the present invention are monosaccharides such as galatose or a mixture thereof, and most preferred is galactose.
- a sugar derivative may be used in addition to the above sugar, if necessary.
- gas contained in gas-containing microparticles refers to any gas that can cause a change in the magnetic field in the body in MRI tissue perfusion imaging and is harmless to the human body.
- Any gas can be used.
- gases can be used.
- gases not only air but also Ne, Xe, O, SF, Ar, and N are not limited thereto.
- Ne, Xe, O, SF, Ar, and N are not limited thereto.
- Ne, Xe, O, SF, Ar, and N are not limited thereto.
- O oxygen
- fatty acid refers to aliphatic monocarboxylic acids and aliphatic dicarboxylic acids obtained by hydrolysis of natural lipids.
- the fatty acid of the present invention may be a saturated fatty acid or an unsaturated fatty acid, and may or may not contain a branched chain.
- the fatty acid has a chain length of 10-20 carbon atoms, more preferably the fatty acid is palmitic acid. A mixture of these fatty acids may be used.
- the amount is preferably 0.01 to 10% by weight, more preferably 0.03 to 3% by weight.
- a specific contrast agent used in the present invention a known contrast agent as a conventional contrast agent for ultrasonic diagnosis can be used.
- the air-containing contrast agents described in Patent Documents 7 to 11 can be used.
- Levovist registered trademark
- the dose of the contrast agent can be almost the same as the dose administered in conventional ultrasonic diagnostic diagnosis.
- the dose of the contrast agent of the present invention is about 5 ml to 25 ml, preferably about 8 ml to 25 ml, more preferably about 8 ml to 25 ml per adult, as in the case of a commonly used gadolinium contrast agent. Is between 10ml and 25ml. However, it is not limited to these, depending on the size (volume) and concentration of the contained gas, the magnetic field strength of the MR device used, and the imaging method.
- the contrast agent is administered as a carrier suspended in a liquid such as physiological saline.
- the concentration in the liquid to be administered is preferably about 10 mg / ml-500 mg / ml, more preferably about 100 mg Zml-400 mg Zml. However, it is not limited to these depending on the size and concentration of the contained gas, the magnetic field strength of the MR device used, and the imaging method.
- the contrast agent of the present invention is administered basically in the same manner as a conventional administration method of an ultrasonic diagnostic contrast agent. A typical method of administration is intravenous injection.
- the timing of administration is preferably 5 minutes before the start of the MRI measurement and 1 minute before the end of the MRI measurement, and more preferably 1 minute before the start of the MRI measurement and 1 minute after the start of the measurement.
- the tissue perfusion imaging method is remarkably different from other MRI imaging methods in that a state in which a fluid such as a blood flow flows is imaged.
- MRI uses an imaging method that obtains high signal strength to maintain a sufficient contrast between tissues or between a normal part and a lesion part and increases the signal-to-noise ratio, and minimizes noise that hinders diagnosis.
- the image is taken so as to keep the sharpness of the image, that is, the spatial resolution sufficiently.
- the time required for one imaging is approximately several minutes to several ten minutes.
- the spin echo method is widely used in general MRI because it is less susceptible to the influence of the magnetic effect than the gradient echo method, that is, less susceptible to signal degradation.
- One of the imaging parameters, TE (echo time) is an important factor. Even in the presence of a high concentration of a dream contrast agent, the effect of signal drop can be suppressed by setting TE short, and the signal is enhanced by the interaction between the gadolinium contrast agent and the surrounding spin system. The effect is obtained.
- the tissue perfusion imaging method using a gadolinium contrast agent measures perfusion blood flow and the like by measuring the amount of signal decrease caused by the gadolinium effect caused by gadolinium.
- gadmium contrast agent is rapidly administered, and a high concentration of the contrast agent reaches the blood vessels perfusing the desired organ (e.g., brain), observing how the signal of surrounding brain tissue is reduced. I do. Assume that the amount of signal reduction caused by the gadolinium contrast agent reflects the volume of perfused blood. At this time, in order to effectively observe the signal reduction caused by the gadolinium contrast agent, it is preferable to perform the imaging using the gradient echo method, which is susceptible to the effect of the magnetic effect. For the same reason, it is preferable to set TE to be slightly longer.
- the gradient echo method in which it is preferable to shorten the imaging time as much as possible and perform repetitive imaging of the same part, is preferable. Effective for shortening.
- the gradient echo method which is sensitive to the magnetic field effect and can shorten the imaging time, is widely used.
- a contrast medium is rapidly administered intravenously, and an MR tomogram of a target site (for example, the head) is taken with time.
- a target site for example, the head
- the rapid administration of the contrast agent it is transported to the brain at a high concentration, reducing the signal intensity (pixel value) of the MR image.
- the amount of signal reduction caused by the administration of the contrast agent is quantified, and the blood flow at the site (eg, brain) is measured. More specifically, the MR signal intensity does not decrease in the portion where blood is not flowing. On the other hand, in the part where blood is flowing, the signal intensity of MR decreases. By observing this difference, the blood flow at that site can be evaluated.
- TR repetition time
- the MR signal attenuated after excitation is restored and observed.
- a spin echo method restoring by an RF pulse
- a gradient echo method restoring by a gradient magnetic field
- the spin echo method is the most basic pulse sequence, has the advantage that an excellent signal-to-noise ratio can be obtained, and has the characteristic that the imaging time is relatively long.
- the gradient echo method also called the field echo method, is a method of restoring the MR signal by reversing the magnetic field gradient.
- the signal-to-noise ratio is inferior to the spin echo method. Compared to this, it has the characteristic that it attenuates sharply, is sensitive to non-uniform magnetic fields (significantly decreases the signal due to the magnetic field effect), and has the advantage that the TR can be shortened to shorten the imaging time. There is.
- one cycle is usually designed to be extremely short for the purpose of shortening the measurement time and the like. Since the signal drop caused by the gadmium contrast agent is very strong, it is preferable to set the TE to a relatively short time in order to improve the signal-to-noise ratio. Setting TE to approximately 150 ms or more should be avoided because the signal strength decreases exponentially with respect to TE, as described below. Also in the present invention, it is preferable to shorten the time of one cycle as much as possible for the purpose of shortening the measurement time. For this, TR is preferred Is set to about 500 ms or less, more preferably about 150 ms or less, and still more preferably about 100 ms or less.
- TE in the relaxation step in order to detect sharply the signal drop caused by the inhomogeneity of the magnetic field due to the presence of air, it is preferable to set TE in the relaxation step to be relatively long within a range not exceeding TR. More specifically, it is more preferable to set TE between approximately 10 ms and 100 ms, more preferably between approximately 20 ms and 100 ms. Setting TE to approximately 150 ms or more should be avoided because the signal strength will be too low. Note that the difference between TR and TE is preferably shorter as the cycle can be shortened. Therefore, it can be reduced as long as the performance of the device such as hardware permits.
- the difference between TE and TR can be set to several milliseconds (for example, TE can be set to 20 milliseconds and TR can be set to (20 milliseconds + several milliseconds)). is there.
- the MR signal intensity varies depending on various factors, in the case of the perfusion imaging method, it is mainly a function of "parameter: TE" and "time constant: T2 *".
- the strength S is represented by the following equation.
- k Coefficient determined by many factors such as the density, diffusion, and molecular structure of hydrogen nuclei.
- TE echo time [ms]. The time from irradiation of the RF pulse to acquisition of the MR signal.
- T2 * Time constant [ms] depending on the inhomogeneity of the magnetic field around the hydrogen nucleus. The more the magnetic field is uneven, the smaller it becomes.
- FIG. 4 is a graph showing a change over time in signal intensity when a contrast agent is used.
- FIG. 4 schematically shows a change in the signal intensity when no contrast agent is used (or when no contrast agent is present) by a curved line A, and the signal intensity when the contrast agent of the present invention is present is shown by a curve A.
- Change is schematically represented by curve B
- curve C the change in signal intensity in the presence of a conventional gadolinium-type contrast agent is shown schematically by curve C.
- the gadolinium contrast agent sharply attenuates the MR signal intensity as shown by the curve C. For this reason, immediately after the excitation, the difference in signal intensity between the place where the contrast agent exists and the place where the contrast agent does not exist becomes remarkable, and the presence or absence of the contrast agent can be easily observed. For this reason, when using a gadolinium contrast agent, TE should be set relatively short, that is, signal acquisition should be performed within a relatively fast and powerful time after excitation.
- the contrast agent of the present invention has less attenuation of the signal intensity than the gadolinium contrast agent. For this reason, as shown in FIG. 4, immediately after the excitation, there is almost no difference in the signal intensity from the place where the contrast agent does not exist. Therefore, even if the measurement is performed at the TE setting as in the case of using a gadolinium contrast agent, the difference between the signal where the contrast agent exists and the position where the contrast agent does not exist cannot be observed. From the measurement results, it is extremely difficult to determine whether or not a contrast agent is present at the site (that is, whether or not the blood flows and the force is low).
- TE when the contrast agent of the present invention is used, TE is set relatively long, and signal collection is performed at a timing when the difference between curves A and B in FIG. 4 becomes sufficiently large. Done. However, if TE is too long, curve A approaches force ⁇ , so the difference between curve A and curve B decreases, making it difficult to judge the presence of contrast agent in this case as well. . Therefore, when setting TE, an appropriate length of TE is set so that the difference between the signal intensity at the site where the contrast agent of the present invention is present and the signal intensity at the site where no contrast agent is present can be sufficiently detected. Should be selected.
- useful information on the blood flow in the body can also be obtained by measuring the phase shift.
- the MR signal is a signal in the complex number domain, and when plotted on a complex plane, is represented as a vector. Can appear. In clinical practice, we observe images that express the magnitude (absolute value) of this vector in shades. Hydrogen nuclei perform precession in a static magnetic field. This precession can be considered as a circular motion when observed in the main magnetic field direction, and can be analyzed using a complex plane.
- the phase obtained from the RF pulse excitation to the acquisition of the signal is the time integral of the angular frequency of the precession motion (for constant-velocity circular motion, the product of the angular frequency and TE).
- the contrast agent has the function of shifting this phase. Observing this shift can also provide useful information on the state of blood flow in the body.
- the measurement of the amount of phase shift is hardly performed in clinical practice, and even if it is measured, little useful information is obtained as a result of the measurement.
- the non-uniformity of the magnetic field of the contrast agent has the function of shifting the phase, and thus the power of changing the amount of phase
- the force that allows the concentration of the contrast agent to be known Force is difficult to actually use It is.
- the phase information has no power because the angle information is 0 degrees or more and less than 360 degrees, and for example, 361 degrees cannot be distinguished from 1 degree. More specifically, the phase represented by ⁇ + 2 ⁇ radians (where ⁇ is a phase between 0 degrees and less than 360 degrees and ⁇ is any integer) cannot be distinguished by changing ⁇ .
- phase aliasing since the magnetic field inhomogeneity due to the gadolinium contrast agent is very strong, ⁇ easily becomes 1 or more, phase aliasing occurs, and it is difficult to measure the correct phase shift amount. For this reason, it is not used in clinical practice except for special purposes such as flow velocity measurement and management of the inhomogeneity of the magnetic field of the device.
- the inhomogeneity of the magnetic field due to the gas is very small as compared with that of the gadolinium contrast agent, it is easier to suppress the phase aliasing than the gadolinium contrast agent.
- the present invention it is possible to measure the phase shift without phase aliasing, and it is possible to analyze the obtained information of the phase shift and use it for analysis of the state of tissue perfusion in the body. Will be possible.
- By adding information deciphering the phase shift in addition to the information based on the signal strength measurement results it is possible to know the subject's internal state in more detail.
- TE slightly shorter. More specifically, it is preferable to set TE to approximately 10 ms to 80 ms, and more preferably to set TE to approximately 10 ms to 60 ms. Since the same amount of measured data can be obtained for the phase shift amount and the absolute value amount, in the actual condition setting, the optimal TE that does not cause phase aliasing and that can obtain a sufficient signal drop should be selected. That's it.
- the above-described setting is specifically performed, for example, as follows.
- Clinical MRI machines are equipped with control consoles to control them, and most are computer-controlled.
- parameters such as imaging method (spin echo method and gradient echo method), TR and TE.
- TR and TE are factors that directly affect the control of the magnetic field and radio waves generated by the MRI system
- the values that can be set may be limited by physical or equipment reasons. More specifically, for example, the lower limit value of TE is set so that the effect of the excitation RF noise remains and the signal cannot be collected when The value of TR or TE is restricted so that the excitation cannot be performed.
- TR and TE may vary depending on the timing of their insertion. Limited.
- the user sets an arbitrary value within the TR and TE degrees of freedom limited by physical and device factors.
- Phantom double container shown in FIG.
- FIG. 7 shows a graph and an image of the obtained signal intensity. It was observed that the signal intensity changed not only in the test tube but also around the test tube.
- FIG. 8 shows a graph and an image of the obtained phase shift. A strong phase shift was observed inside the test tube, and a slight phase shift was observed outside the test tube
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Citations (2)
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JPH07505137A (ja) * | 1992-01-09 | 1995-06-08 | ニユコメド・イメージング・アクシエセルカペト | 造影剤に関する改良 |
JPH09510204A (ja) * | 1994-03-11 | 1997-10-14 | イマアーレクス・フアーマシユーチカル・コーポレーシヨン | 磁気共鳴画像化造影剤としての気体入りミクロスフェア |
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JPH07505137A (ja) * | 1992-01-09 | 1995-06-08 | ニユコメド・イメージング・アクシエセルカペト | 造影剤に関する改良 |
JPH09510204A (ja) * | 1994-03-11 | 1997-10-14 | イマアーレクス・フアーマシユーチカル・コーポレーシヨン | 磁気共鳴画像化造影剤としての気体入りミクロスフェア |
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