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On probing intravoxel incoherent motion in the heart‐spin‐echo versus stimulated‐echo DWI
Author(s) -
Spinner Georg R.,
Stoeck Christian T.,
Mathez Linda,
von Deuster Constantin,
Federau Christian,
Kozerke Sebastian
Publication year - 2019
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.27777
Subject(s) - intravoxel incoherent motion , echo (communications protocol) , nuclear magnetic resonance , spin echo , physics , magnetic resonance imaging , medicine , diffusion mri , radiology , computer science , computer network
Purpose Mapping intravoxel incoherent motion (IVIM) in the heart remains challenging despite advances in cardiac DWI and DTI. In the present work, simulations and experimental imaging are used to compare the IVIM encoding efficiency of spin‐echo– and stimulated‐echo–based DWI/DTI for assessing myocardial perfusion. Methods Using normalized phase distributions and statistical models of capillary networks derived from histological studies, along with typical diffusion gradient waveforms for in vivo cardiac DWI/DTI, Monte Carlo simulations were performed. The simulation results were compared to IVIM measurements of perfused porcine hearts regarding both magnitude and phase modulation. An IVIM tensor model was used to account for anisotropy of the capillary network, and potential bias of parameter estimation was reported based on simulations. Results Both computer simulations and experimental data demonstrate a low sensitivity of spin‐echo DWI/DTI sequences for IVIM parameters, whereas stimulated‐echo–based DWI/DTI with typical mixing times can differentiate between no‐flow baseline and perfused myocardium (+129% IVIM‐derived flow). In addition, ischemic territories induced by coronary occlusion could be successfully detected. With increasing order of motion compensation (M0/M1/M2) of the diffusion encoding gradients, as required for cardiac in vivo spin‐echo DWI/DTI, the low IVIM sensitivity of spin‐echo DWI/DTI decreased further in simulations: maximum attenuations of perfusion compartment 52/13/5% ( b = 500 s/mm 2 ). Conclusion Given the short encoding time of spin‐echo–based DWI/DTI sequences, a limited perfusion sensitivity results, in particular in combination with motion‐compensated diffusion gradients. In contrast, stimulated‐echo based DWI/DTI has the potential to identify perfusion changes in cardiac IVIM in vivo.