US 11,874,353 B2
Multi-shot echo planar imaging using reordered segments and recursive radio frequency pulse design giving matched slice profiles across segments
Avery J. L. Berman, Jamaica Plain, MA (US); Jonathan R. Polimeni, Cambridge, MA (US); William A. Grissom, Nashville, TN (US); Kawin Setsompop, Charlestown, MA (US); and Thomas Witzel, Boston, MA (US)
Assigned to The General Hospital Corporation, Boston, MA (US)
Appl. No. 17/598,035
Filed by THE GENERAL HOSPITAL CORPORATION, Boston, MA (US); and Vanderbilt University, Nashville, TN (US)
PCT Filed Mar. 27, 2020, PCT No. PCT/US2020/025345
§ 371(c)(1), (2) Date Sep. 24, 2021,
PCT Pub. No. WO2020/198631, PCT Pub. Date Oct. 1, 2020.
Claims priority of provisional application 62/824,589, filed on Mar. 27, 2019.
Prior Publication US 2022/0179024 A1, Jun. 9, 2022
Int. Cl. G01V 3/00 (2006.01); G01R 33/483 (2006.01); G01R 33/48 (2006.01); G01R 33/56 (2006.01); G01R 33/561 (2006.01)
CPC G01R 33/4835 (2013.01) [G01R 33/4818 (2013.01); G01R 33/5608 (2013.01); G01R 33/5616 (2013.01)] 21 Claims
OG exemplary drawing
 
1. A method for designing radio frequency (RF) pulses for use in a multi-shot pulse sequence implemented with a magnetic resonance imaging (MRI) system, the method comprising:
recursively designing a plurality of RF pulses with a processor of a computer system by:
(a) selecting a desired number of RF pulses to design for a series of RF pulses, wherein the series of RF pulses comprises a last RF pulse and one or more preceding RF pulses;
(b) selecting a flip angle for the last RF pulse using the computer system;
(c) recursively assigning a flip angle for each of the one or more preceding RF pulses based on the flip angle selected for the last RF pulse, using the computer system;
(d) computing a target slice profile using the computer system, the target slice profile defining a desired spatial profile of transverse magnetization in an imaging slice;
(e) computing an RF pulse waveform for each of the plurality of RF pulses to achieve the target slice profile by:
computing an RF pulse waveform for an initial RF pulse in the plurality of RF pulses based on the target slice profile;
for each successive RF pulse in the plurality of RF pulses, measuring a residual longitudinal magnetization remaining after each one of the plurality of RF pulses preceding a current RF pulse and incorporating the residual longitudinal magnetization into the RF pulse waveform design for the current RF pulse; and
(f) storing in a memory of the computer system as RF pulse parameters:
the flip angle for the last RF pulse;
each flip angle for the one or more preceding RF pulses;
the RF pulse waveform for the initial RF pulse in the plurality of RF pulses; and
each RF pulse waveform for each successive RF pulse in the plurality of RF pulses.