US 12,248,047 B2
Magnetic resonance imaging with prior knowledge and oversampling
Fernando Galve, Valencia (ES); Joseba Alonso, Valencia (ES); José Miguel Algarín, Valencia (ES); and José Maria Benlloch, Valencia (ES)
Assigned to CONSEJO SUPERIOR DE INVESTIGACIONES CIENTÍFICAS (CSIC), Madrid (ES); and UNIVERSITAT POLITÈCNICA DE VALÈNCIA, Valencia (ES)
Appl. No. 18/010,118
Filed by CONSEJO SUPERIOR DE INVESTIGACIONES CIENTÍFICAS (CSIC), Madrid (ES); and UNIVERSITAT POLITÈCNICA DE VALÈNCIA, Valencia (ES)
PCT Filed Jun. 21, 2021, PCT No. PCT/EP2021/066762
§ 371(c)(1), (2) Date Dec. 13, 2022,
PCT Pub. No. WO2021/259828, PCT Pub. Date Dec. 30, 2021.
Claims priority of application No. 20382540 (EP), filed on Jun. 22, 2020.
Prior Publication US 2023/0341493 A1, Oct. 26, 2023
Int. Cl. G01R 33/561 (2006.01); G01R 33/48 (2006.01)
CPC G01R 33/561 (2013.01) [G01R 33/482 (2013.01); G01R 33/4824 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A magnetic resonance imaging, MRI, method for performing an image reconstruction of a sample described by its spin density distribution within a field of view, FoV, from magnetic resonance signals acquired with at least one detector,
the method comprising performing the following steps, in any technically possible order:
a) applying an electromagnetic pulse sequence to the sample, wherein said electromagnetic pulse sequence comprises a plurality of radio frequency and encoding gradient pulses;
b) computing the NS-limit for the dwell time, δtNS=π/bw, wherein bw is the expected maximum bandwidth of the expected acquired magnetic resonance signals derived from the electromagnetic sequence applied in step a);
c) defining a target oversampling rate, OR, along a readout direction as δtNS/δt, wherein δt is the dwell time, and wherein said target oversampling rate, OR, is higher than 1;
d) performing a prior knowledge analysis step comprising the calculation of interactions between the electromagnetic pulse sequence applied in step a) to the sample and the spins of said sample, as well as the time evolution of the spins depending on their position for said electromagnetic pulse sequence; and wherein the results of the calculation are discretized in time steps and stored as an encoding matrix, Φ, oversampled along the readout direction, whose matrix elements Φij correspond to the phase accumulated by the sample spins in the j-th pixel when only the i-th k-space data point is sampled;
e) acquiring, with the at least one detector, the magnetic resonance signals derived from each encoding gradient pulse applied in step a), and storing and discretizing said acquired magnetic resonance signals as a vector S, at a dwell time such that the sampling rate associated to said dwell time is equal to the target oversampling rate, OR, defined in step c);
f) performing an image reconstruction step based on solving for ρ from S and Φ, where ρ is the discretized spin density distribution, wherein said discretized spin density distribution ρ comprises predefined phases associated to the acquired magnetic resonance signals.