MAGNETIC RESONANCE APPARATUS AND METHOD FOR QUANTIFYING AN ORGAN FUNCTION

Abstract

In a magnetic resonance method and apparatus for determination of a measurement variable that is relevant to a function of an organ of a patient, a first longitudinal relaxation rate R.sub.1.sup.1 is determined before a contrast medium is administered to the patient. A second longitudinal relaxation rate R.sub.1.sup.2 is determined after a contrast medium is administered to the patient. A property of the contrast medium in the organ is determined based on R.sub.1.sup.1 and R.sub.1.sup.2. The measurement variable is determined based on the property of the contrast medium in the organ.

Claims

1. A method for determining a measurement variable relevant to a function of an organ of a patient, by operation of a magnetic resonance (MR) apparatus, said method comprising: operating an MR data acquisition scanner, while a patient is situated therein, to acquire first MR data representing a first longitudinal relaxation rate R.sub.1.sup.1 of nuclear spins in an organ of the patient at a first contrast medium concentration; operating the MR data acquisition scanner while the patient is situated therein to acquire second MR data representing a second longitudinal relaxation rate R.sub.1.sup.2 of the nuclear spins of the organ at a second contrast medium concentration; providing said first and second MR data to a processor and, in said processor, determining a property of the contrast medium in the organ based on R.sub.1.sup.1 and R.sub.1.sup.2; in said processor, determining a measurement variable that is relevant to a function of the organ based on said property of the contrast medium in the organ; and making an electronic signal representing said measurement variable available from the processor as an output.

2. A method as claimed in claim 1 comprising using a hepatocyte-specific contrast medium as said contrast medium.

3. A method as claimed in claim 1 wherein the organ is the liver of the patient.

4. A method as claimed in claim 3 wherein said measurement variable is a concentration of healthy liver cells.

5. A method as claimed in claim 1 comprising also acquiring at least one parameter of the organ and using said at least one parameter in said processor to make at least one determination selected from the group consisting of a determination of R.sub.1.sup.1 before administering the contrast medium to the patient, determining R.sub.1.sup.2 after the contrast medium is administered to the patient, determining the property of the contrast medium in the organ based on R.sub.1.sup.1 and R.sub.1.sup.2, and determining said measurement variable based on said property.

6. A method as claimed in claim 1 comprising determining each of R.sub.1.sup.1 and R.sub.1.sup.2 in a spatially-resolved manner in a region encompassed by said organ, and determining said measurement variable also in a spatially-resolved manner in said region.

7. A method as claimed in claim 6 comprising segmenting the organ into at least two segments of the organ, and determining said measurement variable in each of said at least two segments.

8. A method as claimed in claim 1 comprising, in said processor, determining a volume of the organ and, based on said volume and said measurement variable, determining a value that is also relevant to the function of the organ.

9. A magnetic resonance (MR) apparatus comprising: an MR data acquisition scanner; a control computer configured to operate said MR data acquisition scanner, while a patient is situated therein, to acquire first MR data representing a first longitudinal relaxation rate R.sub.1.sup.1 of nuclear spins in an organ of the patient at a first contrast medium concentration; said control computer being configured to operate the MR data acquisition scanner while the patient is situated therein to acquire second MR data representing a second longitudinal relaxation rate R.sub.1.sup.2 of the nuclear spins of the organ at a second contrast medium concentration; a processor provided with said first and second MR data, said processor being configured to determine a property of the contrast medium in the organ based on R.sub.1.sup.1 and R.sub.1.sup.2; said processor being configured to determine a measurement variable that is relevant to a function of the organ based on said property of the contrast medium in the organ; and said processor being configured to make an electronic signal representing said measurement variable available from the processor as an output.

10. A computer for determining a measurement variable relevant to a function of an organ of a patient, by operation of a magnetic resonance (MR) apparatus, said method comprising: an input interface that receives first MR data, acquired from an MR data acquisition scanner while a patient is situated therein, representing a first longitudinal relaxation rate R.sub.1.sup.1 of nuclear spins in an organ of the patient at a first contrast medium concentration; said input interface also receiving second MR data representing a second longitudinal relaxation rate R.sub.1.sup.2 of the nuclear spins of the organ, acquired from said MR data acquisition scanner while the patient is situated therein, at a second contrast medium concentration; a processor configured to determine a property of the contrast medium in the organ based on R.sub.1.sup.1 and R.sub.1.sup.2; said processor being configured to determine a measurement variable that is relevant to a function of the organ based on said property of the contrast medium in the organ; and an output interface at which said processor is configured to make an electronic signal representing said measurement variable available from the processor as an output.

11. A non-transitory, computer-readable data storage medium encoded with programming instructions, said storage medium being loaded into a computer of a magnetic resonance (MR) apparatus that comprises an MR data acquisition scanner, said programming instructions causing said computer to: receive first MR data, acquired from an MR data acquisition scanner while a patient is situated therein, representing a first longitudinal relaxation rate R.sub.1.sup.1 of nuclear spins in an organ of the patient at a first contrast medium concentration; receive second MR data, acquired from said MR data acquisition scanner while the patient is situated therein, representing a second longitudinal relaxation rate R.sub.1.sup.2 of the nuclear spins of the organ at a second contrast medium concentration; determine a property of the contrast medium in the organ based on R.sub.1.sup.1 and R.sub.1.sup.2; determine a measurement variable that is relevant to a function of the organ based on said property of the contrast medium in the organ; and make an electronic signal representing said measurement variable available from the computer as an output.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIG. 1 shows an inventive magnetic resonance device in a schematic illustration.

[0050] FIG. 2 is a flowchart of a first embodiment of the inventive method.

[0051] FIG. 3 is a flowchart of a second embodiment of the inventive method.

[0052] FIG. 4 schematically illustrates a segmented organ.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] FIG. 1 schematically illustrates an inventive magnetic resonance apparatus 11 for carrying out the inventive method. The magnetic resonance apparatus 11 has a scanner 13 with a basic field magnet 17 that generates a strong and constant basic magnetic field 18. The scanner 13 has a cylindrical patient receiving area 14 for receiving a patient 15. The patient receiving area 14 is circumferentially surrounded by the scanner 13. The patient 15 has an organ 12 and can be moved by a patient support 16 into the patient receiving area 14. The patient support 16 has a patient table that is movable within the scanner 13. The scanner 13 is screened from the outside by a housing 31.

[0054] The scanner 13 furthermore has a gradient coil arrangement 19, for spatially encoding the magnetic resonance signals. The gradient coil arrangement 19 is activated by a gradient controller 28. Furthermore the scanner 13 has a radio-frequency antenna 20, which in this embodiment is a body coil permanently integrated into the scanner 13, and a radio-frequency antenna controller 29. The radio-frequency antenna 20 is activated by the radio-frequency antenna controller 29 so as to radiate radio-frequency pulses into an examination space, which is essentially formed by the patient receiving area 14. The radiation radio-frequency pulses give certain nuclear spins in the patient 15 a magnetization that deflects those nuclear spins from the direction of the basic magnetic field 18 by a defined angle, called a flip angle. As the excited nuclear spins relax and thereby return to the steady state, they emit radio-frequency signals, which are the aforementioned magnetic resonance signals. These magnetic resonance signals may be detected by the same antenna that was used to radiate the radio-frequency pulses, or may be detected by a different antenna in the scanner 13.

[0055] For control of the basic field magnet 17, the gradient controller 28 and the radio-frequency antenna controller 29, the magnetic resonance apparatus 11 has a computer 24.

[0056] The computer 24 centrally controls the magnetic resonance apparatus 11, such as to execute MR control sequences. Control information such as imaging parameters, as well as reconstructed image data, can be displayed to the user on a display 25, for example on at least one monitor. In addition, the magnetic resonance apparatus 11 has an input unit 26, via which information and/or imaging parameters can be entered by a user during a measurement process. The computer 24 can include the gradient controller 28 and/or the radio-frequency antenna controller 29 and/or the display 25 and/or the input unit 26. The computer 24 further has a determination processor 33. The magnetic resonance apparatus 11 is thus designed, together with the determination processor 33, to implement the inventive method. The computer 24 preferably has a neural network 27 with a self-learning algorithm, which is designed to carry out the inventive method independently.

[0057] The magnetic resonance apparatus 11 shown can of course include further components, common to magnetic resonance apparatuses. The general manner in which a magnetic resonance apparatus functions is known to those skilled in the art, so that a more detailed description is not necessary herein.

[0058] The method described herein can also be available in the form of a computer program product, which implements the respective method on the computer 24, when it is executed by the computer 24. A non-transitory, computer-readable data storage medium 21 with electronically-readable control information stored thereon is designed such that, when the data storage medium 21 is loaded into the computer 24, the control information cause the computer 24 to execute the described method.

[0059] FIG. 2 is a flowchart of a first embodiment of an inventive method for a determination of a measurement variable 401 relevant for a function of an organ 12 of a patient 15 by operating the magnetic resonance apparatus 11. In this case, the method proceeds in accordance with the following method steps.

[0060] In method step 100 a first longitudinal relaxation rate R.sub.1.sup.1 will be determined at a first contrast medium concentration. At a second contrast medium concentration a second longitudinal relaxation rate R.sub.1.sup.2 will be determined in method step 200. R.sub.1.sup.1 and R.sub.1.sup.2 will preferably be determined such that these rates are present spatially-resolved in a region covered by the organ 12. Based on R.sub.1.sup.1 and R.sub.1.sup.2, in method step 300, a property of the contrast medium 301 in the organ 12 will be determined. Based on the property of the contrast medium 301 in the organ 12, in method step 400 the measurement variable 401 will be determined. If R.sub.1.sup.1 and R.sub.1.sup.2 are present spatially-resolved, the measurement variable 401 will preferably be determined such that this is present spatially-resolved in the region covered by the organ 12. The organ 12 is preferably a liver. The administered contrast medium is preferably a hepatocyte-specific contrast medium. The measurement variable 401 is preferably a concentration of the healthy liver cells.

[0061] FIG. 3 is a flowchart of a second embodiment of the inventive method. The flow diagram of the second form of embodiment is based on the flowchart of the first embodiment and supplements that flowchart by further method steps. These further method steps are optional.

[0062] Before the determination of the first longitudinal relaxation rate R.sub.1.sup.1 in accordance with method step 100, a parameter 501 of the organ 12 is preferably available to the method, which was preferably acquired at the beginning of the method in method step 500. The acquired parameter 501 will preferably be taken into account in the determination of R.sub.1.sup.1 and/or R.sub.1.sup.2 in the method steps 100 and/or 300. Method step 500 can also be integrated into method step 100 or at least be partly executed at the same time. The parameter 501 typically influences R.sub.1.sup.1 and/or R.sub.1.sup.2 and/or their determination, so that deviations of R.sub.1.sup.1 and/or R.sub.1.sup.2 are produced as a result of the parameter 501. These deviations are preferably compensated in the determination of R.sub.1.sup.1 and/or R.sub.1.sup.2 in the method steps 100 and/or 300.

[0063] Furthermore, in method step 600, a volume 601 of the organ 12 can be determined. This can be done, for example, based on magnetic resonance imaging data, wherein the organ 12 will be segmented. Taking account of the volume 601 and the measurement variable 401, in method step 700, a value 701 for the function of the organ 12 can be determined. The value is preferably an absolute value, which quantifies the function of the organ 12 and can be employed for example for a comparison of the organ function between different patients. The parameter 501 can also be taken into account in the method steps 400 and/or 600 and/or 700.

[0064] FIG. 4 schematically illustrates a segmented organ 12 with a first segment 121 and a second segment 122. Within the framework of the inventive method, in an independent method step, a segmentation of the organ 12 into at least two segments 121, 122 covered by the organ can take place and on determination of the measurement variable 401, for each of the at least two segments 121, 122, a segmented measurement variable can be determined. The first segment 121 and the second segment 122 are preferably disjoint from one another. The segmentation can be done for example on the basis of a spatially-resolved R.sub.1.sup.1 and/or R.sub.1.sup.2, so that for example the second segment 122 differs from the first segment 121 in R.sub.1.sup.1 and/or R.sub.1.sup.2. The union of sets of the two segments 121, 122 preferably produces the volume 601 of the organ 12.

[0065] Although modifications and changes may be suggested by those skilled in the art, it is the intention of the Applicant to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of the Applicant's contribution to the art.