DE102009015516A1 - Method and device for determining T2 and T2 * by means of magnetic resonance tomography - Google Patents

Abstract

The present invention essentially relates to a method for determining T2 and T2 * by means of magnetic resonance tomography (MRT). T2 and T2 * are determined from measurements on echo trains within a single image read sequence 90, with at least two measurements 40, 50 taking place on the same echo train 80. The measurements are preceded by an ASL preparation. One form of use of the method is the measurement of the physiological parameters perfusion and / or oxygenation.

Description

Field of the invention

The The invention relates in essence to a method of detection from T2 and T2 * using magnetic resonance imaging (MRI) and a corresponding device. Such methods and devices serve primarily the visualization of anatomical conditions or physiological parameters.

State of the art

In Arterial Spin Labeling (ASL) ( Detre, JA, JS Leigh, et al. (1992). "Perfusion imaging." Magn Reson Med 23 (1): 37-45 / Williams, DS, JA Detre, et al. (1992). "Magnetic resonance imaging of perfusion using spin inversion of arterial water." Proc Natl Acad Sci USA 89 (1): 212-6 ), a bolus of arterial blood is magnetized by inversion of the water proton spins. This makes it possible to measure perfusion using magnetic resonance tomography without contrast administration, which is of particular interest in the diagnosis and examination of vascular diseases.

The BOLD effect (Blonde Oxygenation Level Dependent Effect) ( Ogawa, S., RS Menon, et al. (1993). "Functional brain mapping by blond oxygenation level-dependent contrast magnetic resonance imaging. A comparison of signal characteristics with a biophysical model. "Biophys J 64 (3): 803-12 ) indicates the influence of the magnetic properties of blood by its oxygen content (oxygenation). This effect is done z. In functional imaging, for example, they use the measurement of the parameter T2 * by means of magnetic resonance tomography to conclude activation of various areas of the brain.

Conventional methods for quantifying the BOLD effect, such. B. the GESSE method ( Yablonskiy, DA and EM Haacke (1997). "Magnetic field inhomogeneities." Magn Reson Med 37 (6): 872-6 ), have the disadvantage that they are very time consuming and distribute the necessary measurements over several acquisition phases.

• 1. zu einem erhöhten physiologischen Rauschen,
• 2. zu einer verringerten zeitlichen Auflösung (höherer Messzeitbedarf) und
• 3. zu ungenaueren Ergebnissen, da eine genaue Kalibrierung der einzelnen Messungen notwendig ist.

By combining several physiological parameters, such as perfusion and oxygenation, it is possible to make important statements about local metabolism. However, the measurement of perfusion by ASL and the determination of oxygenation using the BOLD effect are based on different parameters. Existing methods for evaluating these effects typically measure these parameters separately and sequentially (eg. Mandell, DM, JS Han, et al. (2008). "Mapping cerebrovascular reactivity using MRI in arterial steno-occlusive disease:" with arterial spin labeling MRI. "Stroke 39 (7): 2021-8 ) or by interleaved signal readouts ( Hoge, RD, J. Atkinson, et al. (1999). "Investigation of BOLD signal dependence on cerebral blood flow and oxygen consumption: the deoxyhemoglobin dilution model." Magn Reson Med 42 (5): 849-63 ). this leads to

• 1. to increased physiological noise,
• 2. to a reduced temporal resolution (higher measurement time required) and
• 3. to more inaccurate results, since an accurate calibration of the individual measurements is necessary.

Method in which the measurement takes place simultaneously ( Yang, Y., H.G., et al. (2002). "Simultaneous perfusion and BOLD imaging using reverse spiral scanning at 3T: characterization of functional contrast and susceptibility artifacts." Magn Reson Med 48 (2): 278-89 .), have only a limited volume coverage and also have different measurement times for the individual layers. The different measurement times cause different degrees of perfusion weighting, since the blood has penetrated different layers in the vascular tree at different levels (variable inflow time TI). Furthermore, the analysis of temporal correlations is made more difficult.

task

task The invention is to provide a method which has a determination of T2 and T2 *, in particular the physiological parameters to efficiently identify perfusion and oxygenation to let.

solution

These Task is by the inventions with the characteristics of the independent Claims solved. Advantageous developments The inventions are characterized in the subclaims. The wording of all claims hereby by reference to the content of this description. The invention also includes all meaningful and especially all mentioned Combinations of independent and / or dependent Claims.

in the Following are individual process steps and features of the process described in more detail. The process steps must not necessarily performed in the order given be, and the process to be described may be more, not have mentioned steps. The features can be in individual Procedural steps may be included, but may also be on refer to several process steps.

The inventive method determined by MRI the MRI-relevant parameters T2 and T2 * or equivalent Parameters. The experts are the meanings of T2 and T2 * known. The parameter T2 represents a time constant representing the course of the decay of the transverse magnetization of a precessing Spin ensembles assuming a homogeneous basic magnetic field describes (spin-spin relaxation). The present value of T2 is characteristic of the material of the examined sample. Usually T2 is also used as a generic term for the Phenomenon of spin-spin relaxation used. Synonyms for T2 are about the "transversal relaxation time" or the "spin-spin relaxation time". Instead of the parameter T2 could alternatively be equivalent, i. H. The progress the decay of the transverse magnetization of a precessing Spin ensembles assuming a homogeneous basic magnetic field descriptive parameters are determined. Which includes in particular those parameters from which T2 can be deduced leaves. For example, T2 results from inversion of the Relaxation rate R2. It is also possible to change the parameter T2 from the so-called reversible relaxation time T2 'with the addition of Calculate parameter T2 * (see below). This applies analogously for the relaxation rates R2, R2 'and R2 *.

Of the Parameter T2 *, also known as "effective relaxation time", "effective transversal relaxation time "or" effective Spin-spin relaxation time "is a time constant which observed in the FID (Free Induction Decay) decay signal Course of the decay of the transverse magnetization of a precessing Spin ensembles describes. In one - for example, by Susceptibility differences of the examined sample conditioned - inhomogeneous Magnetic field deviates T2 * from the transversal relaxation time T2. T2 * is usually used as a generic term for relaxation the transverse magnetization component in the inhomogeneous magnetic field used. Instead of the parameter T2 *, alternative equivalent, d. H. the effective course of the decay of the transverse magnetization of a precessing spin ensemble in the inhomogeneous magnetic field descriptive Parameters are determined. These include in particular such Parameters from which T2 * can be deduced. For example, T2 * results from inversion of the relaxation rate R2 *. It is also possible to derive the parameter T2 * from the parameter T2 '. with the addition of T2. This applies analogously for the relaxation rate R2, R2 'and R2 *.

to Determination of T2 and T2 * will take measurements on echo trains take place within a picture reading sequence. Under a picture reading sequence (also MR sequence or pulse sequence) is understood to mean a sequence of electromagnetic Excitation and Refokussierungspulse, magnetic field gradients and Measurements of the magnetization of the examined sample. The excitation pulses serve the initial structure of a transverse magnetization by the atomic nuclei of the examined sample to a precession movement be stimulated. The measurable transverse magnetization of the studied Probe disintegrates due to effects such as magnetic Alternating effects of precessing atomic nuclei or inhomogeneities of the applied magnetic field faster than the Transversalmagne tization individual atomic nuclei. To still receive a measurement signal, must the phase position of the precession movements of the atomic nuclei be synchronized. Refocusing pulses in the examined sample irradiated. The physical effects of a Refocusing pulses differ during the value curve Observe parameters. Such a course of values becomes an echo train designated. For example, with some image readout sequences an increase in the amount of the FID decay signal to a value be observed, the spin-spin relaxation according to the Parameter T2 corresponds to then drop again. One on one Echo train measurement measures the value curve of a parameter after an excitation and / or refocusing pulse.

The Method involves at least two measurements on the same echo train. Preferably, exactly two measurements take place.

By the determination of the parameters T2 and T2 * from measurements on the same Echo train within a picture reading sequence can be found in the same measurement time more information is recorded and processed become. This increases the temporal resolution or reduces the measuring time and makes the measurement more robust disturbing influences by the measuring object. For this For example, the so-called physiological noise, which is due to changes in blood flow, respiratory movements, Heartbeat or caused by body movements. In addition, the determination of T2 allows and T2 * from measurements on the same echo train for a more robust quantification the absolute values of the reversible relaxation time T2 '.

By means of at least one Arterial Spin Labeling (ASL) preparation, the at least two measurements can be assigned to specific areas within a vascular tree. If one marks a blood bolus by means of ASL, the measured values can be localized along an artificial vascular tree. A bolus of arterial blood is magnetically labeled at a defined distance from a region of a body to be examined by inversion of the hydrogen spins. After a freely selectable inflow time, the marked bolus flows into the read range of the MRI device and is detected by the at least two measurements. By choosing a cure zen inflow time, the at least two measurements of arterial blood can be assigned. A long inflow time allows an assignment of the at least two measurements to capillary blood. The magnetic marking of a bolus can be dispensed with the administration of a contrast agent, which is often associated with undesirable side effects. In order to separate the signal of the labeled blood from the signal of the stationary tissue, a control measurement is performed in which the magnetic marking (inversion of the blood spins) is omitted.

The Method allows the determination of local frequency changes. An inhomogeneous magnetic field causes local changes in the Frequencies with which the FID decay signal of a precessing Spin ensembles oscillate. As a result of these frequency changes there are phase shifts of the precession movements, which are also reflected in the FID decay signal. Conversely, these are Phase shifts and / or the frequency changes Measure of the local variations of an inhomogeneous one Magnetic field (local magnetic field inhomogeneity).

The reversible relaxation time T2 'characterizes the decay of the transverse magnetization, which is caused by local magnetic field inhomogeneities. T2 'is also commonly used as a generic term for such local magnetic field inhomogeneities as well as the associated local frequency changes and local phase shifts:
In an advantageous development of the invention, the at least two measurements which take place on the same echo train within an image read sequence follow one another in time. The measurements can be carried out by means of spiral readout, also called spiral scan echo planar imaging or spiral MRI. In spiral selection, the trajectory in k-space is described by a spiral function. Compared to traditional Cartesian techniques, which scan the data points in k-space on a Cartesian grid, this method allows for improved contrast imaging when the examined samples or parts of a sample being examined are in motion during the measurement. For example, spiral selection improves the contrast in the examination of blood. Another benefit of spiral readout is the reduction of motion and pulsation artifacts achieved by oversampling the k-space center. In addition, the k-space center is picked up very early, allowing a high SNR to be achieved.

A the at least two measurements on the same echo train within a Image readout sequence can be between a refocusing pulse and the followed by a spin echo. In a common one Form of use is the term "spin echo" local maximum in the curve of the parameter T2 * (T2 * decay). A local maximum of the T2 * decay occurs approximately when phase coherence in response to a refocusing pulse within a precessing spin ensemble. For some image reading sequences, it is true at the time of the spin echo the value of the T2 * decay with the value of the curve of the parameter T2 match. In particular, one of the at least two Measurements take place on a rising edge of the T2 * decay.

A Another of the at least two measurements can be between the spin echo and a subsequent second refocussing pulse. follows no further refocusing pulse towards the end of the image read sequence, the further measurement may take place before the end of the refocussing pulse. Preferably, the further measurement takes place at the time of the spin echo. The beginning of the further measurement is correct in this case with the time match the spin echo. In particular, the further of the at least two measurements at the maximum of the T2 * decay and / or on a falling edge of the T2 * decay.

The at least two measurements produce values which are preferably at least span a three-dimensional raw data space. In the generated Values are not necessarily measured values, such as taken by means of a measuring device of an MRI device physical parameters. Instead, at least in particular one of the raw data spaces called k-space has three dimensions exhibit. The term "k-space" is the expert common.

through of the at least one three-dimensional raw data space the parameters T2, T2 * and / or T2 'are generated. For example it is possible by applying a Fourier transform or a variant of a Fourier transform the at least to transform a three-dimensional k-space into T2, T2 * and / or T2'-maps.

The by means of T2, T2 * and / or T2 'maps representable parameter T2 and / or T2 * can be assigned to a three-dimensional volume. Is located a sample examined in the MRI machine correspond to parts this three-dimensional volume of the examined sample.

Compared to the prior art methods, such as 2D EPI, the generation of the parameters T2, T2 * and / or T2 'from a three-dimensional raw data space and Assigning to a three-dimensional volume a higher signal-to-noise ratio (SNR). The SNR represents a measure of the signal quality and thus the quality of the imaging of an MRI device.

The Image reading sequence of the process can be considered essentially one GRASE or 3D GRASE sequence. Indeed GRASE or 3D GRASE sequences usually use the Selection of values using echo planar imaging (EPI). Instead of a EPI train, d. H. a trajectory of k-space according to EPI, At least two spiral readouts can be used.

In an advantageous embodiment of the method, the absolute Values of T2, T2 * and / or T2 'are quantified.

The Determination of T2, T2 * and / or T2 'from measurements on the same Echo train allows in a further advantageous development a direct determination of the phase shift between the signals the measurements. The phase shift between the signals is directly proportional to the local magnetic field inhomogeneity. This allows a quantification of the local magnetic field inhomogeneity. In many cases (especially at low SNR) leave the phase shifts of the (complex-valued) measurement signal much more stable and reliable than the Signal intensities.

In an advantageous embodiment of the method the amount of time allocated to the ASL-labeled blood bolus less than 1 second ("short bolus ASL"). this makes possible a more accurate identification of the blood bolus within the vascular tree and thus improves the assignability to specific areas of the vessel tree. In particular, a more accurate Differentiation between arterial and capillary blood allows.

The Method can be used to determine the physiological parameter perfusion and / or oxygenation. This can be done to estimate the local metabolism within the tissue and perform a noninvasive vitality test.

Especially is a use of the method for determining the physiological Parameter perfusion and / or oxygenation of a brain, preferably of a human brain, possible. By combination the parameter perfusion and oxygenation can be important Statements about local metabolism are taken. This allows in particular a determination of the activation and changing the activation of various brain areas.

Moreover, by means of the method it is possible, using suitable models (eg. Yablonskiy, DA and EM Haacke (1994) "MRI method for measuring T2 in the presence of static and RF magnetic field inhomogeneities." Magn Reson Med 37 (6): 872-6 and Kiselev, VG, R. Strecker, et al. (2005). "Vessel size imaging in humans." Magn Reson Med 53 (3): 553-63 .) To gain insights into the structural properties of the underlying vascular structures. As a result, statements about the average vessel size can be made, so that phenomena such. B. angiogenesis (vascularization), can be detected. Today's conventional methods use contrast-based methods (see Kiselev, VG, R. Strecker, et al. (2005) "Vessel size imaging in humans." Magn Reson Med 53 (3): 553-63 ), which are usually associated with undesirable side effects.

Farther is claimed a computer software product comprising an inventive Procedures implemented when using on a resonance tomography device connected computing device is running.

Further According to the invention, a magnetic resonance tomography device which is used for carrying out the inventive Method is suitable.

Further Details and features will become apparent from the following description of preferred embodiments in connection with the dependent claims. Here, the respective features alone or in combination with each other be realized. The possibilities to solve the task are not limited to the embodiments. For example, ranges always include all - not - intermediate values and all conceivable subintervals.

The Embodiments are shown schematically in the figures. The same reference numerals in the individual figures indicate same or functionally identical or with regard to their functions corresponding elements. In detail shows:

1 Sequence diagram of an embodiment of the method according to the invention

2 Sequence diagram of an embodiment of the method according to the invention with two measurements for determining the relaxation time T2

3 Sequence diagram of an embodiment of the method according to the invention with temporal symmetry to the occurrence of a Spin echoes arranged spirals to determine the relaxation time T2 within a measurement

The absolute values of T2 'are read out in a preferred embodiment by means of the signal intensities S1 and S2 of the at least two spirals 40 . 50 directly quantified: T2 '= delta t / (ln S1-ln S2), where delta t is the time interval 45 the at least two spiral readouts 40 . 50 describes and ln denotes the natural logarithm.

The exact determination of T2 'or T2 * can be made with the help of known models ( Yablonskiy, DA and EM Haacke (1994). "Theory of NMR signal behavior in magnetically inhomogeneous tissues: the static dephasing regime." Magn Reson Med 32 (6): 749-63 .) create a connection with local Suszeptibilitätsänderungen, as they are caused in particular by differently oxygenated blood. Certain structures or contrast agents also cause local susceptibility changes (compare Tables 1 and 2 in the above-mentioned publication Yablonskiy, DA and EM Haacke (1994) ). The same model also establishes the relationship between the frequency change (measured by the phase change) and the local magnetic properties.

For determining the transverse relaxation (T2 or R2), there are a plurality of methods implemented in preferred exemplary embodiments, which are briefly described below. A determination of T2 or R2 is by means of two measurements 32 and 34 possible. In this case, the readout module of the second measurement 34 ge compared to the readout module of the first measurement 32 delayed. The time delay 35 between the two read-out modules is chosen so that it corresponds to a multiple of the distance between two spin echoes (see 2 ). In this case, R2 is calculated from the ratio of the signal amplitudes S of both measurements: R2 = ln (S (TE1) / S (TE2)) / (TE2-TE1)

TE1 and TE2 are the measurement times of the two measurements. The advantage of this method is that only two spiral readouts are needed within one echo train, but apart from a first measurement 32 a second measurement 34 necessary.

Achievements - as in 3 shown - two spiral readouts 40 . 55 on the same echo train in time symmetry about the occurrence of a spin echo, so T2 or R2 can be directly calculated with only one measurement from the relation of the two signal amplitudes thus obtained as follows ( Yablonskiy, DA and EM Haacke (1997) "MRI method for measuring T2 in the presence of static and RF magnetic field inhomogeneities." Magn Reson Med 37 (6): 872-6 .): R2 = ln (S (TE-dt) / S (TE + dt)) / 2dt.

TE denotes the time of the spin echo 30 , dt the distance 45 the spirals 40 and 55 to the spin echo and S the respectively measured signal amplitude of the spirals 40 and 55 ,

A preferred embodiment of the method implements as image reading sequence a combination of 3D GRASE ( Feinberg, DA and K. Oshio (1991). "GRASE (gradient and spin echo) MR imaging: a new fast clinical imaging technique." Radiology 181 (2): 597-6027 Oshio, K. and DA Feinberg (1991). "GRASE (gradient and spin echo) imaging: a novel near MRI technique." Magn Reson Med 20 (2): 344-9 / Gunther, M., K. Oshio, DA Feinberg (2005). "Single-shot 3D imaging techniques improve arterial spin labeling perfusion measurements." Magn Reson Med 54 (2): 491-8 .) and spiral selection. The 1 . 2 and 3 show corresponding sequence diagrams.

A GRASE sequence represents a combination of a turbo spin echo sequence and a gradient echo train. A variant of this is the so-called 3D GRASE sequence. Normally, GRASE and 3D-GRASE use Echo-Planar-Imaging (EPI) echo trains. This is chosen so that the spin echo is just in the middle of the echo train 80 lies. At this point, the strongest (and purely T2-weighted) signal is picked up. In the variant of the 3D GRASE, the EPI readouts represent parts of the three-dimensional raw data space (k-space).

In the combination of 3D-GRASE and spiral readout, two spirals are first read out within the TSE-template (combination of excitation and refocusing pulse) during the signal readout instead of one EPI-train. In the 1 . 2 and 3 you can see that the central echo of the first spiral 40 (the beginning of the selection) immediately after the refocusing pulse 20 and thus an area on the signal curve of the T2 * decay 70 scans, which lies on the rising edge. The k-space center of the second spiral 50 becomes the spin echo 30 go through, ie at a local maximum of the signal curve 70 , The decay constant of the signal curve can then be determined from the two recorded spiral data sets, ie a quantitative T2 * map of the examined sample can be calculated. The violation of the CPMG condition associated with the uptake of T2 * weighted data associated with a turbo spin echo sequence is accomplished using the method described herein avoided.

Becomes this readout module, d. H. the 3D-GRASE signal selection incl Spirals now with an Arterial Spin Labeling (ASL) preparation provided, this ensures that only blood signal is measured. This allows the T2 * measurement of blood. By the free selectable inflow time TI (inflow time) between the marking of blood water spins and image selection with above described blood, the measurements can be determined Assign areas within the vascular tree (a short TI equals arterial blood, while a long TI is more likely capillary blood). For better demarcation is one marked short blood bolus. At a preferred bolus length of 500 ms, the properties of the blood can be within a locally limited area of the vascular tree, the determine the short bolus. The use of 3D-GRASE Make sure that the measurements are compared to standard EPI techniques have a significantly higher SNR.

By repeatedly recording measurement data on the same echo train 80 Within an ASL sequence, the oxygenation of blood (from T2 * using the at least two spiral readouts 40 . 50 ) and the strength of blood flow (from ASL perfusion-weighted spin-echo uptake 50 (corresponding to the spiral selection, the beginning of which is usually exactly in the middle of the refocusing interval). With the addition of measurements of the blood volume (eg by means of VASO ( Lu, H., X. Golay, et al. (2003). "Functional magnetic resonance imaging based on changes in vascular space occupancy." Magn Reson Med 50 (2): 263-74 ) or VASO-FLAIR ( Donahue, MJ, H. Lu, et al. (2006). The Resonance Med 56 (6): 1261-73 )), the parameters "cerebral blond flow", "cerebral blond volume" and "CMRO2" can be determined. Furthermore, the measurement of the phase behavior between the first spiral readout (spin echo) and the second spiral readout (gradient echo) is directly possible. Since it is the sampling of the same echo train (once directly at the maximum, once at the rising edge) there is a direct correlation between the two phase measurements. This results in the ability to separately measure and quantify the phase behavior of blood water spins, making it easy to track the altered magnetic environment of these spins.

When Advantageously, a choice of half the distance of the refocusing pulses proven to correspond to the mean T2 * of the blood or tissue. This optimizes the contrast within the generated image and ensures a reliable determination of T2 *.

10

excitation pulse

20

first refocusing

25

second refocusing

30

Spin echo

32

first Measurement

34

second Measurement

35

time delay

36

first partition

38

second partition

40

first spiral

45

time distance

50

second spiral

55

third spiral

60

T2 decay

70

T2 * decay

80

echo train

90

Image readout sequence

List of quoted literature:

• An, H. and W. Lin (2000). "Quantitative measurements of cerebral blood oxygen saturation using magnetic "J Cereb Blood Flow Metab 20 (8): 1225-36
• Detre, JA, JS Leigh, et al. (1992). "Perfusion imaging." Magn Reson Med 23 (1): 37-45 ,
• Donahue, MJ, H. Lu, et al. (2006). The Resonance Med 56 (6): 1261-73 ,
• Feinberg, DA and K. Oshio (1991). "GRASE (gradient and spin-echo) MR imaging: a new fast clinical imaging technique." Radiology 181 (2): 597-602 ,
• Günther, M .; Oshio, K .; Feinberg, DA (2005). "Single-Shot 3D Imaging Techniques Improve Arterial Spin Labeling Perfusion Measurements." Magn Reson Med 54 (2): 491-8 ,
• Hoge, RD, J. Atkinson, et al. (1999). "Investigation of BOLD signaling on cerebral blood flow and oxygen consumption: the deoxyhemoglobin dilution model." Magn Reson Med. 42 (5): 849-63 ,
• Kiselev, VG, R. Strecker, et al. (2005). "Vessel size imaging in humans." Magn Reson Med 53 (3): 553-63 ,
• Lu, H., X. Golay, et al. (2003). "Functional magnetic resonance imaging based on changes in vascular space occupancy." Magn Reson Med 50 (2): 263-74 ,
• Mandell, DM, JS Han, et al. (2008). "Mapping cerebrovascular reactivity using blood level-dependent MRI in patients with arterial steno-occlusive disease: comparison with arterial spin labeling MRI." Stroke 39 (7): 2021-8 ,
• Ogawa, S., RS Menon, et al. (1993). "Functional brain mapping by blood oxygenation level-dependent contrast magnetic resonance imaging. A comparison of signal characteristics with a biophysical model. "Biophys J 64 (3): 803-12 ,
• Oshio, K. and DA Feinberg (1991). "GRASE (gradient and spin-echo) imaging: a novel almost MRI tech nique. "Magn Reson Med 20 (2): 344-9 ,
• Thomas, D.L., M.F. Lythgoe, et al. (2002). "Rapid simultaneous mapping of T2 and T2 * by multiple acquisition of spin and gradient echoes using interleaved echo planar imaging (MASAGE-IEPI). "Neuroimage 15 (4): 992-1002
• Williams, DS, JA Detre, et al. (1992). "Magnetic imaging of perfusion using spin inversion of arterial water." Proc Natl Acad Sci USA 89 (1): 212-6 ,
• Yablonskiy, DA and EM Haacke (1994). "Theory of NMR signal behavior in magnetically inhomogeneous tissues: the static dephasing regime." Magn Reson Med 32 (6): 749-63 ,
• Yablonskiy, DA and EM Haacke (1997). "Magnetic field inhomogeneities." Magn Reson Med 37 (6): 872-6 ,
• Yang, Y., H.G., et al. (2002). "Simultaneous Perfusion and BOLD imaging using reverse spiral scanning at 3T: characterization of functional contrast and susceptibility artifacts. "Magn Reson Med 48 (2): 278-89

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - Detre, JA, JS Leigh, et al. (1992). "Perfusion imaging." Magn Reson Med 23 (1): 37-45 [0002]
• Williams, DS, JA Detre, et al. (1992). "Magnetic resonance imaging of perfusion using spin inversion of arterial water." Proc Natl Acad Sci USA 89 (1): 212-6 [0002]
• Ogawa, S., RS Menon, et al. (1993). "Functional brain mapping by blond oxygenation level-dependent contrast magnetic resonance imaging. A comparison of signal characteristics with a biophysical model. "Biophys J 64 (3): 803-12 [0003]
• - Yablonskiy, DA and EM Haacke (1997). "Magnetic field inhomogeneities MRI method for measuring T2 in the presence of static and RF." Magn Reson Med 37 (6): 872-6 [0004]
• Mandell, DM, JS Han, et al. (2008). "Mapping cerebrovascular reactivity using blond oxygen level-dependent MRI in patients with arterial steno-occlusive disease: comparison with arterial spin labeling MRI." Stroke 39 (7): 2021-8 [0005]
• Hoge, RD, J. Atkinson, et al. (1999). "Investigation of BOLD signal dependence on cerebral blood flow and oxygen consumption: the deoxyhemoglobin dilution model." Magn Reson Med 42 (5): 849-63 [0005]
• Yang, Y., H.G., et al. (2002). "Simultaneous perfusion and BOLD imaging using reverse spiral scanning at 3T: characterization of functional contrast and susceptibility artifacts." Magn Reson Med 48 (2): 278-89 [0006]
• - Yablonskiy, DA and EM Haacke (1994) "MRI method for measuring T2 in the presence of static and RF magnetic field inhomogeneities." Magn Reson Med 37 (6): 872-6 [0030]
• Kiselev, VG, R. Strecker, et al. (2005). "Vessel size imaging in humans." Magn Reson Med 53 (3): 553-63 [0030]
• Kiselev, VG, R. Strecker, et al. (2005) "Vessel size imaging in humans." Magn Reson Med 53 (3): 553-63 [0030]
• - Yablonskiy, DA and EM Haacke (1994). "Theory of NMR signal behavior in magnetically inhomogeneous tissues: the static dephasing regime." Magn Reson Med 32 (6): 749-63 [0039]
• - Yablonskiy, DA and EM Haacke (1994) [0039]
• - Yablonskiy, DA and EM Haacke (1997) "MRI method for measuring T2 in the presence of static and RF magnetic field inhomogeneities." Magn Reson Med 37 (6): 872-6 [0042]
• - Feinberg, DA and K. Oshio (1991). "GRASE (gradient and spin-echo) MR imaging: a new fast clinical imaging technique." Radiology 181 (2): 597-6027 Oshio, K. [0044]
• - DA Feinberg (1991). "GRASE (gradient and spin-echo) imaging: a novel near MRI technique." Magn Reson Med 20 (2): 344-9 [0044]
• - Gunther, M., K. Oshio, DA Feinberg (2005). "Single-shot 3D imaging techniques improve arterial spin labeling perfusion measurements." Magn Reson Med 54 (2): 491-8 [0044]
• Lu, H., X. Golay, et al. (2003). "Functional magnetic resonance imaging based on changes in vascular space occupancy." Magn Reson Med 50 (2): 263-74 [0048]
• Donahue, MJ, H. Lu, et al. (2006). The Resonance Med 56 (6): 1261-73 [0048]

Claims (14)

Method for determining T2 and T2 * by means of magnetic resonance tomography (MRT), characterized in that a) T2 and T2 * from measurements on echo trains within an image readout sequence 90 be determined, where b) at least two measurements 40 . 50 on the same echo train 80 where c) the measurements are preceded by at least one ASL preparation. Method according to claim 1, characterized in that that frequency changes are determined. A method according to claim 1 or 2, characterized in that the at least two measurements 40 . 50 take place in succession. Method according to one of the preceding claims, characterized in that the at least two measurements 40 . 50 done by spiral selection. Method according to one of the preceding claims, characterized in that a) one of the at least two measurements 40 between a refocusing pulse 20 and the subsequent spin echo 30 takes place, and b) the at least second measurement 50 between the spin echo 30 and a subsequent second refocusing pulse 25 or the end of the image readout sequence, preferably at the time of the spin echo 30 , he follows. Method according to one of the preceding claims, characterized in that a) by means of the at least two measurements 40 . 50 Values are generated which span at least one three-dimensional raw data space, where b) the parameters T2, T2 * and / or T2 'are generated by means of the at least one three-dimensional raw data space, and c) the parameters T2, T2 * and / or T2' are a three-dimensional one Volume to be assigned. Method according to one of the preceding claims, characterized in that a) as a picture readout sequence, a 3D-GRASE sequence is used, wherein b) instead of an echo planar imaging (EPI) readout at least two spiral readouts 40 . 50 be used. Method according to one of the preceding claims, characterized in that a quantification of the absolute Values of T2, T2 * and / or T2 'is made. Method according to one of the preceding claims, characterized in that a phase shift between the at least two measurements 40 . 50 is determined. Method according to one of the preceding claims, characterized in that the arterial spin labeling (ASL) a Time span of less than 1 sec. For the marking of the Blood bolus is assigned. Use of the method according to one of the claims 1 to 10 for the determination of physiological parameters perfusion and / or oxygenation. Use of the method according to claim 11, for Determination of physiological parameters perfusion and / or oxygenation a brain, preferably a human brain. Computer software product, characterized that it is a method according to any one of claims 1 to 10 Implements if it's on a with a magnetic resonance tomography device connected computing device is running. Magnetic resonance tomography device for performing The method according to any one of claims 1 to 10.