Spin echo based cardiac diffusion imaging at 7T: An ex vivo study of the porcine heart at 7T and 3T

• Published in: PloS one Vol. 14; no. 3; p. e0213994
• Main Authors: Lohr, David, Terekhov, Maxim, Weng, Andreas Max, Schroeder, Anja, Walles, Heike, Schreiber, Laura Maria
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25.03.2019; Public Library of Science (PLoS)
• Subjects: Acceleration; Animals; Anisotropy; Biology and Life Sciences; Computer and Information Sciences; Diagnostic imaging; Diffusion; Diffusion coefficient; Diffusion Tensor Imaging - methods; Diffusion Tensor Imaging - statistics & numerical data; Echo-Planar Imaging - methods; Echo-Planar Imaging - statistics & numerical data; Eigenvectors; Euthanasia; Feasibility Studies; Heart; Heart - anatomy & histology; Heart - diagnostic imaging; Heart biopsy; Heart failure; Hospitals; Image acquisition; Image processing; Image segmentation; Imaging, Three-Dimensional - methods; Imaging, Three-Dimensional - statistics & numerical data; In Vitro Techniques; Magnetic permeability; Magnetic resonance; Magnetic resonance imaging; Male; Medicine; Medicine and Health Sciences; Models, Animal; Models, Cardiovascular; Myocardium; NMR; Noise; Nuclear magnetic resonance; Physical Sciences; Research and Analysis Methods; Signal-To-Noise Ratio; Statistical analysis; Studies; Sus scrofa - anatomy & histology; Tensors; Ventricle; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0213994

Purpose of this work was to assess feasibility of cardiac diffusion tensor imaging (cDTI) at 7 T in a set of healthy, unfixed, porcine hearts using various parallel imaging acceleration factors and to compare SNR and derived cDTI metrics to a reference measured at 3 T. Magnetic resonance imaging was performed on 7T and 3T whole body systems using a spin echo diffusion encoding sequence with echo planar imaging readout. Five reference (b = 0 s/mm2) images and 30 diffusion directions (b = 700 s/mm2) were acquired at both 7 T and 3 T using a GRAPPA acceleration factor R = 1. Scans at 7 T were repeated using R = 2, R = 3, and R = 4. SNR evaluation was based on 30 reference (b = 0 s/mm2) images of 30 slices of the left ventricle and cardiac DTI metrics were compared within AHA segmentation. The number of hearts scanned at 7 T and 3 T was n = 11. No statistically significant differences were found for evaluated helix angle, secondary eigenvector angle, fractional anisotropy and apparent diffusion coefficient at the different field strengths, given sufficiently high SNR and geometrically undistorted images. R≥3 was needed to reduce susceptibility induced geometric distortions to an acceptable amount. On average SNR in myocardium of the left ventricle was increased from 29±3 to 44±6 in the reference image (b = 0 s/mm2) when switching from 3 T to 7 T. Our study demonstrates that high resolution, ex vivo cDTI is feasible at 7 T using commercial hardware.