In vivo diffusion MRI of the human heart using a 300 mT/m gradient system.

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$$ {M}_2 $$ and M3$$ {M}_3 $$ ) and b=100, 450$$ b=100,450 $$ , and 1000 s/mm2$$ \mathrm{s}/\mathrm{m}{\mathrm{m}}^2 $$ (twice the bmax$$ {b}_{\mathrm{max}} $$ 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$$ \mathrm{s}/\mathrm{m}{\mathrm{m}}^2 $$ and b = [100, 1000] s/mm2$$ \mathrm{s}/\mathrm{m}{\mathrm{m}}^2 $$ for both M2$$ {M}_2 $$ and M3$$ {M}_3 $$ .

Results

The MD values with M3$$ {M}_3 $$ are slightly higher than with M2$$ {M}_2 $$ with ΔMD=0.05±0.05[×10-3mm2/s](p=4e-5)$$ \Delta \mathrm{MD}=0.05\pm 0.05\kern0.3em \left[\times 1{0}^{-3}\kern0.3em {\mathrm{mm}}^2/\mathrm{s}\right]\kern0.3em \left(p=4e-5\right) $$ for bmax=450s/mm2$$ {b}_{\mathrm{max}}=450\kern0.3em \mathrm{s}/{\mathrm{mm}}^2 $$ and ΔMD=0.03±0.03[×10-3mm2/s](p=4e-4)$$ \Delta \mathrm{MD}=0.03\pm 0.03\kern0.3em \left[\times \kern0.3em 1{0}^{-3}\kern0.3em {\mathrm{mm}}^2/\mathrm{s}\right]\kern0.3em \left(p=4e-4\right) $$ for bmax=1000s/mm2$$ {b}_{\mathrm{max}}=1000\kern0.3em \mathrm{s}/{\mathrm{mm}}^2 $$ . A reduction in MD is observed by increasing the bmax$$ {b}_{\mathrm{max}} $$ from 450 to 1000 s/mm2$$ \mathrm{s}/{\mathrm{mm}}^2 $$ ( ΔMD=0.06±0.04[×10-3mm2/s](p=1.6e-9)$$ \Delta \mathrm{MD}=0.06\pm 0.04\kern0.3em \left[\times \kern0.3em 1{0}^{-3}\kern0.3em {\mathrm{mm}}^2/\mathrm{s}\right]\kern0.3em \left(p=1.6e-9\right) $$ for M2$$ {M}_2 $$ and ΔMD=0.08±0.05[×10-3mm2/s](p=1e-9)$$ \Delta \mathrm{MD}=0.08\pm 0.05\kern0.3em \left[\times \kern0.3em 1{0}^{-3}\kern0.3em {\mathrm{mm}}^2/\mathrm{s}\right]\kern0.3em \left(p=1e-9\right) $$ for M3$$ {M}_3 $$ ). The difference between FA, E2A, and HA was not significant in different schemes ( p>0.05$$ p>0.05 $$ ).

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$$ {M}_2 $$ to M3$$ {M}_3 $$ and the maximum b-value from 450 to 1000  s/mm2$$ \mathrm{s}/{\mathrm{mm}}^2 $$ 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.

SUBMITTER: Afzali M 

PROVIDER: S-EPMC7617480 | biostudies-literature | 2024 Sep

REPOSITORIES: biostudies-literature