Comparison of diffusion tensor imaging by cardiovascular magnetic resonance and gadolinium enhanced 3D image intensity approaches to investigation of structural anisotropy in explanted rat hearts

Journal of Cardiovascular Magnetic Resonance

Technical Notes

Gregory B Sands¹  Mark L Trew¹  Ian J LeGrice²  Bruce H Smaill²  Olivier Bernus³  Aleksandra Radjenovic⁴  Stephen H Gilbert⁵  Derek R Magee⁶ 

[1] Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand;Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand;Department of Physiology, University of Auckland, Auckland, New Zealand;Inserm U1045 - Centre de Recherche Cardio-Thoracique, L’Institut de rythmologie et modélisation cardiaque LIRYC, Université de Bordeaux, PTIB - campus Xavier Arnozan, Avenue du Haut Leveque, 33604, Pessac, France;Institute of Cardiovascular and Medical Sciences, University of Glasgow, BHF Glasgow Cardiovascular Research Centre, 126 University Place, G12 8TA, Glasgow, UK;Mathematical Cell Physiology, Max-Delbrück-Center for Molecular Medicine (MDC), Robert-Rössle-Straße 10, 13125, Berlin, Germany;School of Computing, The University of Leeds, LS2 9JT, Leeds, UK;

关键词: Diffusion tensor imaging;    Cardiovascular magnetic resonance;    Myocardium;    Myolaminar;   

DOI  :  10.1186/s12968-015-0129-x

 received in 2014-06-02, accepted in 2015-03-11,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundCardiovascular magnetic resonance (CMR) can through the two methods 3D FLASH and diffusion tensor imaging (DTI) give complementary information on the local orientations of cardiomyocytes and their laminar arrays.MethodsEight explanted rat hearts were perfused with Gd-DTPA contrast agent and fixative and imaged in a 9.4T magnet by two types of acquisition: 3D fast low angle shot (FLASH) imaging, voxels 50 × 50 × 50 μm, and 3D spin echo DTI with monopolar diffusion gradients of 3.6 ms duration at 11.5 ms separation, voxels 200 × 200 × 200 μm. The sensitivity of each approach to imaging parameters was explored.ResultsThe FLASH data showed laminar alignments of voxels with high signal, in keeping with the presumed predominance of contrast in the interstices between sheetlets. It was analysed, using structure-tensor (ST) analysis, to determine the most (v1ST), intermediate (v2ST) and least (v3ST) extended orthogonal directions of signal continuity. The DTI data was analysed to determine the most (e1DTI), intermediate (e2DTI) and least (e3DTI) orthogonal eigenvectors of extent of diffusion. The correspondence between the FLASH and DTI methods was measured and appraised. The most extended direction of FLASH signal (v1ST) agreed well with that of diffusion (e1DTI) throughout the left ventricle (representative discrepancy in the septum of 13.3 ± 6.7°: median ± absolute deviation) and both were in keeping with the expected local orientations of the long-axis of cardiomyocytes. However, the orientation of the least directions of FLASH signal continuity (v3ST) and diffusion (e3ST) showed greater discrepancies of up to 27.9 ± 17.4°. Both FLASH (v3ST) and DTI (e3DTI) where compared to directly measured laminar arrays in the FLASH images. For FLASH the discrepancy between the structure-tensor calculated v3ST and the directly measured FLASH laminar array normal was of 9 ± 7° for the lateral wall and 7 ± 9° for the septum (median ± inter quartile range), and for DTI the discrepancy between the calculated v3DTI and the directly measured FLASH laminar array normal was 22 ± 14° and 61 ± 53.4°. DTI was relatively insensitive to the number of diffusion directions and to time up to 72 hours post fixation, but was moderately affected by b-value (which was scaled by modifying diffusion gradient pulse strength with fixed gradient pulse separation). Optimal DTI parameters were b = 1000 mm/s2 and 12 diffusion directions. FLASH acquisitions were relatively insensitive to the image processing parameters explored.ConclusionsWe show that ST analysis of FLASH is a useful and accurate tool in the measurement of cardiac microstructure. While both FLASH and the DTI approaches appear promising for mapping of the alignments of myocytes throughout myocardium, marked discrepancies between the cross myocyte anisotropies deduced from each method call for consideration of their respective limitations.

【 授权许可】

Unknown   
© Bernus et al.; licensee BioMed Central. 2015. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.