Mapping vascular perfusion territories using magnetic resonance imaging

1. A magnetic resonance imaging (MRI) method for estimating a location of at least one source vessel in a tagging plane of a subject, the method comprising:

using a first set of coils to apply a plurality of encoding steps in the tagging plane, each encoding step comprising application of gradient and radio frequency (RF) pulses to generate an MRI signal with modulation across the tagging plane, the MRI signal characterized by an orientation based on an orientation randomization scheme, a wavelength based on a wavelength randomization scheme and a phase based on a phase randomization scheme, wherein the phase randomization scheme includes selecting phases in encoding step pairs such that a first phase of a first RF pulse of a first encoding step from a given encoding step pair in the encoding step pairs is randomly selected, and a second phase of a second RF pulse of a second encoding step from the given encoding step pair is selected to be 180 degrees away from the first phase, and wherein a difference signal between the encoding step pair facilitates removing a static tissue signal;

using a second set of coils to acquire a plurality of scan images based on the applied plurality of encoding steps;

processing, using a processor, the acquired plurality of scan images to produce a processed data output; and

estimating, using the processor, based on the processed data output, the location of the at least one source vessel.

2. The MRI method in claim 1 , wherein the orientation randomization scheme includes randomly selecting an orientation angle between 0 and 360 degrees.

3. The MRI method in claim 1 , wherein the phase randomization scheme includes randomly selecting a phase between 0 and 360 degrees.

4. The MRI method in claim 1 , wherein the wavelength randomization scheme includes randomly selecting a wavelength between a minimum value and a maximum value.

5. The MRI method in claim 4 , wherein the minimum value is 15 mm and the maximum value is 85 mm.

6. The MRI method in claim 1 , wherein the processing operation includes pairwise subtracting scan images from the acquired plurality of scan images.

7. The MRI method of claim 1 , wherein the estimating the location of the at least one source vessel includes:

generating a plurality of possible outputs based on an encoding scheme and assumed vessel locations in the tagging plane;

comparing the processed data output with results from a plurality of possible theoretical image signals based on the encoding scheme and assumed vessel locations; and

selecting the location of the vessel to correspond to an assumed vessel location at which the comparison shows a maximum correlation.

8. The MRI method of claim 1 , further comprising:

measuring a resonance offset of the at least one source vessel.

9. An apparatus for magnetic resonance imaging (MRI) that includes a first set of coils, a second set of coils, a processor and a non-transitory computer-readable storage medium storing instructions that when executed by a computer cause the apparatus to estimate a location of at least one source vessel in a tagging plane of a subject:

cause the first set of coils to apply a plurality of encoding steps in the tagging plane, each encoding step comprising application of gradient and radio frequency (RF) pulses to generate an MRI signal with modulation across the tagging plane, the MRI signal characterized by an orientation based on an orientation randomization scheme, a wavelength based on a wavelength randomization scheme and a phase based on a phase randomization scheme, wherein the phase randomization scheme includes selecting phases in encoding step pairs such that a first phase of a first RF pulse of a first encoding step from a given encoding step pair in the encoding step pairs is randomly selected, and a second phase of a second RF pulse of a second encoding step from the given encoding step pair is selected to be 180 degrees away from the first phase, and wherein a difference signal between the encoding step pair facilitates removing a static tissue signal;

cause the second set of coils to acquire a plurality of scan images based on the applied plurality of encoding steps; and

cause the processor to:

process the acquired plurality of scan images to produce a processed data output, and

estimate, based on the processed data output, the location of the at least one source vessel.

10. The apparatus for MRI in claim 9 , wherein the orientation randomization scheme includes randomly selecting an orientation angle between 0 and 360 degrees.

11. The apparatus for MRI in claim 9 , wherein the phase randomization scheme includes randomly selecting a phase between 0 and 360 degrees.

12. The apparatus for MRI in claim 9 , wherein the wavelength randomization scheme includes randomly selecting a wavelength between a minimum value and a maximum value.

13. The apparatus for MRI in claim 12 , wherein the minimum value is 15 mm and the maximum value is 85 mm.

14. The apparatus for MRI in claim 9 , wherein the processor is configured to

process the acquired plurality of scan images by pairwise subtracting scan images from the acquired plurality of scan images.

15. The apparatus for MRI in claim 9 , wherein the processor is configured to estimate the location of the at least one source vessel by:

generating a plurality of possible outputs based on an encoding scheme and assumed vessel locations in the tagging plane;

comparing the processed data output with results from a plurality of possible theoretical image signals based on the encoding scheme and assumed vessel locations; and

selecting the location of the vessel to correspond to an assumed vessel location at which the comparison shows a maximum correlation.

16. The apparatus for MRI in claim 9 , wherein the apparatus is configured to measure a resonance offset of the at least one source vessel.