System and method for imaging tissue

A system for detecting a portion within a tissue that has a variation of local magnetic susceptibility, comprising:

• a magnetic resonance imaging (MRI) device having a nonhomogeneous magnetic field in a measurement volume such that, if conventional susceptibility-weighted-imaging were to be performed using the MRI device on a tissue located in the measurement volume, phase shifts caused by the variation of local magnetic susceptibility would need to be larger than phase shifts caused by the nonhomogeneous magnetic field in order to detect such variation, making conventional susceptibility-weighted imaging unreliable for detecting such variation of local magnetic susceptibility using such MRI device, the MRI device further configured to:
• transmit a first spin-echo pulse sequence to the tissue, wherein the first spin-echo pulse sequence comprises a first number of refocus pulses and a first echo time (TE) value;
• obtain a first image of the tissue;
• transmit a second spin-echo pulse sequence to the tissue, wherein the second spin-echo pulse sequence comprises a second number of refocus pulses and a second TE value;
• obtain a second image of the tissue;
• determine one or more locations within the second image of the tissue having a signal intensity that is different than the signal intensity of the same one or more locations within the first image of the tissue;
• and
• identify a portion of tissue that has a varied local magnetic susceptibility based on the determined one or more locations within the second image of the tissue,
• wherein the first number of refocus pulses and the second number of refocus pulses are different, and
• wherein neither the first image nor the second image are based on a signal with a non-zero phase shift caused by the nonhomogeneous magnetic field.

A non-transitory computer program product for detection of a portion within a tissue that has a variation of local magnetic susceptibility, the non-transitory computer program product comprising instructions which, when executed by a computer, cause the computer to:

• cause one or more components of a magnetic resonance imaging (MRI) device to transmit a first spin-echo pulse sequence to the tissue, wherein the first spin-echo pulse sequence comprises a first number of refocus pulses and a first echo time (TE) value, wherein the MRI device has a nonhomogeneous magnetic field in a measurement volume such that, if conventional susceptibility-weighted-imaging were to be performed using the MRI device on the tissue located in the measurement volume, phase shifts caused by the variation of local magnetic susceptibility would need to be larger than phase shifts caused by the nonhomogeneous magnetic field in order to detect such variation, making conventional susceptibility-weighted imaging unreliable for detecting such variation of local magnetic susceptibility using such MRI device;
• obtain a first image of the tissue;
• cause the one or more components of the MRI device to transmit a second spin-echo pulse sequence to the tissue, wherein the second spin-echo pulse sequence comprises a second number of refocus pulses and a second TE value;
• obtain a second image of the tissue;
• determine one or more locations within the second image of the tissue having a signal intensity that is different than the signal intensity of the same one or more locations within the first image of the tissue;
• and
• identify a portion of tissue that has a varied local magnetic susceptibility based on the determined one or more locations within the second image of the tissue,
• wherein the first number of refocus pulses and the second number of refocus pulses are different, and
• wherein neither the first image nor the second image are based on a signal with a non-zero phase shift caused by the nonhomogeneous magnetic field.