Myofiber strain in healthy humans using DENSE and cDTI

Purpose: Myofiber strain, E-ff, is a mechanistically relevant metric of cardiac cell shortening and is expected to be spatially uniform in healthy populations, making it a prime candidate for the evaluation of local cardiomyocyte contractility. In this study, a new, efficient pipeline was proposed to combine microstructural cDTI and functional DENSE data in order to estimate E-ff in vivo. Methods: Thirty healthy volunteers were scanned with three long-axis (LA) and three short-axis (SA) DENSE slices using 2D displacement encoding and one SA slice of cDTI. The total acquisition time was 11 minutes +/- 3 minutes across volunteers. The pipeline first generates 3D SA displacements from all DENSE slices which are then combined with cDTI data to generate a cine of myofiber orientations and compute E-ff. The precision of the post-processing pipeline was assessed using a computational phantom study. Transmural myofiber strain was compared to circumferential strain, E-cc, in healthy volunteers using a Wilcoxon sign rank test. Results: In vivo, computed E-ff was found uniform transmurally compared to E-cc (-0.14[-0.15, -0.12] vs -0.18 [-0.20, -0.16], P<.001, -0.14 [-0.16, -0.12] vs -0.16 [-0.17, -0.13], P<.001 and -0.14 [-0.16, -0.12] vs E-cc_(C) -0.14 [-0.15, -0.11], P=.002, E-ff_(C) vs E-cc_(C) in the endo, mid, and epi layers, respectively). Conclusion: We demonstrate that it is possible to measure in vivo myofiber strain in a healthy human population in 10 minutes per subject. Myofiber strain was observed to be spatially uniform in healthy volunteers making it a potential biomarker for the evaluation of local cardiomyocyte contractility in assessing cardiovascular dysfunction.

Automated summary

A new efficient pipeline combining microstructural cDTI and functional DENSE data was proposed to measure in vivo myofiber strain in healthy populations within 10 minutes per subject. The study found uniform transmural myofiber strain in healthy volunteers, suggesting its potential as a biomarker for evaluating local cardiomyocyte contractility in assessing cardiovascular dysfunction.