Abstract
PURPOSE: This work reports for the first time on the implementation and application of cardiac diffusion-weighted MRI on a Connectom MR scanner with a maximum gradient strength of 300 mT/m. It evaluates the benefits of the increased gradient performance for the investigation of the myocardial microstructure. METHODS: Cardiac diffusion-weighted imaging (DWI) experiments were performed on 10 healthy volunteers using a spin-echo sequence with up to second- and third-order motion compensation ( M2 and M3 ) and b = 100, 450 , and 1000 s/mm2 (twice the bmax commonly used on clinical scanners). Mean diffusivity (MD), fractional anisotropy (FA), helix angle (HA), and secondary eigenvector angle (E2A) were calculated for b = [100, 450] s/mm2 and b = [100, 1000] s/mm2 for both M2 and M3 . RESULTS: The MD values with M3 are slightly higher than with M2 with ΔMD = 0.05 ± 0.05 [ × 10-3 mm2/s] (p = 4e - 5) for bmax = 450 s/mm2 and ΔMD = 0.03 ± 0.03 [ × 10-3 mm2/s] (p = 4e - 4) for bmax = 1000 s/mm2 . A reduction in MD is observed by increasing the bmax from 450 to 1000 s/mm2 ( ΔMD = 0.06 ± 0.04 [ × 10-3 mm2/s] (p = 1.6e - 9) for M2 and ΔMD = 0.08 ± 0.05 [ × 10-3 mm2/s] (p = 1e - 9) for M3 ). The difference between FA, E2A, and HA was not significant in different schemes ( p > 0.05 ). CONCLUSION: This work demonstrates cardiac DWI in vivo with higher b-value and higher order of motion compensated diffusion gradient waveforms than is commonly used. Increasing the motion compensation order from M2 to M3 and the maximum b-value from 450 to 1000 s/mm2 affected the MD values but FA and the angular metrics (HA and E2A) remained unchanged. Our work paves the way for cardiac DWI on the next-generation MR scanners with high-performance gradient systems.