Abstract: Inventive technology is directed to diffusion weighted magnetic resonance measurements. In an embodiment, a method for performing a diffusion weighted magnetic resonance measurement on a sample includes operating a magnetic resonance scanner to apply a diffusion encoding sequence to the sample. The method also includes operating the magnetic resonance scanner to acquire from the sample one or more echo signals. The diffusion encoding sequence includes a diffusion encoding time-dependent magnetic field gradient g(t) with non-zero components gl(t) along at least two orthogonal directions y and z, and a b-tensor having at least two non-zero eigenvalues, the magnetic field gradient comprising a first and subsequent second encoding block.
Type:
Grant
Filed:
April 24, 2020
Date of Patent:
September 5, 2023
Assignee:
Random Walk Imaging AB
Inventors:
Irvin Teh, Samo Lasic, Markus Nilsson, Filip Szczepankiewicz
Abstract: Disclosed is a method for generating a time-dependent magnetic field gradient in diffusion weighted magnetic resonance imaging G(t)=[Gx(t)Gy(t)Gz(t)]T, which is asymmetric in time with respect to a refocusing pulse, by meeting one or more of the requirements: A=?0TEh(t)G(t)G(t)Tdt is zero, where TE is an echo time and h(t) is a function of time which is positive during an interval prior to the refocusing pulse and negative during a time interval after the refocusing pulse); minimize A or m=(Tr[AA])1/2 where A=?P1G(t)G(t)Tdt??P2G(t)G(t)Tdt where P1 and P2 represent time intervals prior to and subsequent to the refocusing pulse; m is smaller than a threshold value. an attenuation factor AF p = exp ? ( - t T ? 2 * ) due to T2* relaxation is one. Signal attenuation due to concomitant field gradients, regardless of the shape or orientation of the diffusion encoding b-tensor and the location of signal is hereby minimized.