Probing cardiomyocyte mobility with multi-phase cardiac diffusion tensor MRI

• Published in: PloS one Vol. 15; no. 11; p. e0241996
• Main Authors: Moulin, Kévin, Verzhbinsky, Ilya A, Maforo, Nyasha G, Perotti, Luigi E, Ennis, Daniel B
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 12.11.2020; Public Library of Science (PLoS)
• Subjects: Adult; Anisotropy; Biology and Life Sciences; Cardiac function; Cardiomyocytes; Cardiomyopathy; Cell Movement; Contraction; Diffusion; Diffusion Magnetic Resonance Imaging - methods; Diffusion Tensor Imaging; Eigenvalues; Female; Healthy Volunteers; Heart; Heart cells; High resolution; Humans; Image acquisition; Image resolution; Magnetic resonance imaging; Magnetic Resonance Imaging, Cine; Male; Mathematical analysis; Medical research; Medicine and Health Sciences; Mobility; Multiphase; Muscle contraction; Myocytes, Cardiac - cytology; Myocytes, Cardiac - physiology; Observations; Physical Sciences; Radiology; Research and Analysis Methods; Systole; Tensors; Thickening; Ventricle; Ventricular Function, Left; United States; Los Angeles California; United States > US; California
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0241996

Cardiomyocyte organization and performance underlie cardiac function, but the in vivo mobility of these cells during contraction and filling remains difficult to probe. Herein, a novel trigger delay (TD) scout sequence was used to acquire high in-plane resolution (1.6 mm) Spin-Echo (SE) cardiac diffusion tensor imaging (cDTI) at three distinct cardiac phases. The objective was to characterize cardiomyocyte organization and mobility throughout the cardiac cycle in healthy volunteers. Nine healthy volunteers were imaged with cDTI at three distinct cardiac phases (early systole, late systole, and diastasis). The sequence used a free-breathing Spin-Echo (SE) cDTI protocol (b-values = 350s/mm2, twelve diffusion encoding directions, eight repetitions) to acquire high-resolution images (1.6x1.6x8mm3) at 3T in ~7 minutes/cardiac phase. Helix Angle (HA), Helix Angle Range (HAR), E2 angle (E2A), Transverse Angle (TA), Mean Diffusivity (MD), diffusion tensor eigenvalues (λ1-2-3), and Fractional Anisotropy (FA) in the left ventricle (LV) were characterized. Images from the patient-specific TD scout sequence demonstrated that SE cDTI acquisition was possible at early systole, late systole, and diastasis in 78%, 100% and 67% of the cases, respectively. At the mid-ventricular level, mobility (reported as median [IQR]) was observed in HAR between early systole and late systole (76.9 [72.6, 80.5]° vs 96.6 [85.9, 100.3]°, p<0.001). E2A also changed significantly between early systole, late systole, and diastasis (27.7 [20.8, 35.1]° vs 45.2 [42.1, 49]° vs 20.7 [16.6, 26.4]°, p<0.001). We demonstrate that it is possible to probe cardiomyocyte mobility using multi-phase and high resolution cDTI. In healthy volunteers, aggregate cardiomyocytes re-orient themselves more longitudinally during contraction, while cardiomyocyte sheetlets tilt radially during wall thickening. These observations provide new insights into the three-dimensional mobility of myocardial microstructure during systolic contraction.