Assessment of the regional distribution of normalized circumferential strain in the thoracic and abdominal aorta using DENSE cardiovascular magnetic resonance

• Type of Material: Article
• Authors: John S. Wilson, Virginia Commonwealth University; William Taylor, Emory University; John Oshinski, Emory University
• Language: English
• Date: 2019-09-16
• Publisher: BMC (part of Springer Nature)
• Publication Version: Final Published Version
• Copyright Statement: Copyright © The Author(s). 2019
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1186/s12968-019-0565-0
• Title of Journal or Parent Work: Journal of Cardiovascular Magnetic Resonance
• ISSN: 1097-6647
• Volume: 21
• Issue: 1
• Start Page: 59
• End Page: 59
• Grant/Funding Information: Additional funding during data analysis and preparation of the manuscript was provided by start-up funds from the Department of Biomedical Engineering and College of Engineering at Virginia Commonwealth University (JSW).; This project was supported, in part, by funds from an NIH-NHLBI Institutional Training Grant T32HL007745 (JSW/WRT); a seed grant from the Emory University Department of Radiology & Imaging Sciences (JSW/JO); a Shared Instrumentation Grant (S10) 1S10OD016413–01 to the Emory University Center for Systems Imaging Core; and a grant for DENSE research from Siemens Healthcare (JO/JSW).
• Keywords: WALL-MOTION; RUPTURE; ANEURYSM; DENSE MRI; Aortic mechanics; Strain distribution; Life Sciences & Biomedicine; Cardiovascular System & Cardiology; SPECKLE TRACKING; DISSECTION; Cardiovascular magnetic resonance imaging; Science & Technology; Cardiac & Cardiovascular Systems; Radiology, Nuclear Medicine & Medical Imaging
• Research Categories: Health Sciences, Medicine and Surgery; Engineering, Biomedical; Health Sciences, Radiology

Abstract

BACKGROUND: Displacement Encoding with Stimulated Echoes (DENSE) cardiovascular magnetic resonance (CMR) of the aortic wall offers the potential to improve patient-specific diagnostics and prognostics of diverse aortopathies by quantifying regionally heterogeneous aortic wall strain in vivo. However, before regional mapping of strain can be used to clinically assess aortic pathology, an evaluation of the natural variation of normal regional aortic kinematics is required. METHOD: Aortic spiral cine DENSE CMR was performed at 3 T in 30 healthy adult subjects (range 18 to 65 years) at one or more axial locations that are at high risk for aortic aneurysm or dissection: the infrarenal abdominal aorta (IAA, n = 11), mid-descending thoracic aorta (DTA, n = 17), and/or distal aortic arch (DAA, n = 11). After implementing custom noise-reduction techniques, regional circumferential Green strain of the aortic wall was calculated across 16 sectors around the aortic circumference at each location and normalized by the mean circumferential strain for comparison between individuals. RESULTS: The distribution of normalized circumferential strain (NCS) was heterogeneous for all locations evaluated. Despite large differences in mean strain between subjects, comparisons of NCS revealed consistent patterns of strain distribution for similar groupings of patients by axial location, age, and/or mean displacement angle. NCS at local systole was greatest in the lateral/posterolateral walls in the IAAs (1.47 ± 0.27), medial wall in anteriorly displacing DTAs (1.28 ± 0.20), lateral wall in posteriorly displacing DTAs (1.29 ± 0.29), superior curvature in DAAs < 50 years-old (1.93 ± 0.22), and medial wall in DAAs > 50 years (2.29 ± 0.58). The distribution of strain was strongly influenced by the location of the vertebra and other surrounding structures unique to each location. CONCLUSIONS: Regional in vivo circumferential strain in the adult aorta is unique to each axial location and heterogeneous around its circumference, but can be grouped into consistent patterns defined by basic patient-specific metrics following normalization. The heterogeneous strain distributions unique to each group may be due to local peri-aortic constraints (particularly at the aorto-vertebral interface), heterogeneous material properties, and/or heterogeneous flow patterns. These results must be carefully considered in future studies seeking to clinically interpret or computationally model patient-specific aortic kinematics.