Ex vivo cardiovascular magnetic resonance measurements of right and left ventricular mass compared with direct mass measurement in excised hearts after transplantation: a first human SSFP comparison

Abstract

BackgroundCMR is considered the ‘gold standard’ for non-invasive LV and RV mass quantitation. This information is solely based on gradient-recalled echo (GRE) sequences while contrast dependent on intrinsic T1/T2 characteristics potentially offers superior image contrast between blood and myocardium. This study aims, for the first time in humans, to validate the SSFP approach using explanted hearts obtained from heart transplant recipients. Our objective is establish the correlation between and to validate steady-state free precession (SSFP) derived LV and RV mass vs. autopsy mass of hearts from cardiac transplants patients.MethodsOver three-years, 58 explanted cardiomyopathy hearts were obtained immediately upon orthotopic heart transplantation from the OR. They were quickly cleaned, prepared and suspended in a saline-filled container and scanned ex vivo via SSFP-SA slices to define LV/RV mass. Using an automatic thresholding program, segmentation was achieved in combination with manual trimming (ATMT) of extraneous tissue incorporating 3D cardiac modeling performed by independent and blinded readers. The explanted hearts were then dissected with the ventricles surgically separated at the interventricular septum. Weights of the total heart not excluding papillary and trabecular myocardium, LV and RV were measured via high-fidelity scale. Linear regression and Bland-Altman plots were used to analyze the data. The intra-class correlation coefficient was used to assess intra-observer reliability.ResultsOf the total of 58 explanted hearts, 3 (6%) were excluded due to poor image quality leaving 55 patients (94%) for the final analysis. Significant positive correlations were found between total 3D CMR mass (450 ± 111 g) and total pathology mass (445 ± 116 g; r = 0.99, p < 0.001) as well as 3D CMR measured LV mass (301 ± 93 g) and the pathology measured LV mass (313 ± 96 g; r = 0.95, p < 0.001). Strong positive correlations were demonstrated between the 3D CMR measured RV mass (149 ± 46 g) and the pathology measured RV mass (128 ± 40 g; r = 0.76, p < 0.001). The mean bias between 3D-CMR and pathology measures for total mass, LV mass and RV mass were: 3.0 g, -16 g and 19 g, respectively.ConclusionsSSFP-CMR accurately determines total myocardial, LV and RV mass as compared to pathology weighed explanted hearts despite variable surgical removal of instrumentation (left and right ventricular assist devices, AICD and often apical core removals). Thus, this becomes the first-ever human CMR confirmation for SSFP now validating the distinction of ‘gold standard’.

Acute Reverse Remodelling After Transcatheter Aortic Valve Implantation: A Link Between Myocardial Fibrosis and Left Ventricular Mass Regression

“…Assessment of LV mass by echocardiography is calculated on the basis of a number of anatomical and mathematical assumptions, reducing its accuracy [18]. Due to the excellent endocardial definition afforded by the technique, LV mass quantification using modern CMR SSFP pulse sequences have been shown to have an excellent correlation with autopsy studies [19]. CMR LV mass quantitation is also more reproducible than by echo [20], allowing smaller sample sizes to detect a treatment effect.…”

Assessment of the precision and reproducibility of ventricular volume, function, and mass measurements with ferumoxytol‐enhanced 4D flow MRI

“…T he quantification of ventricular volume, function, and mass is an essential goal of many cardiac magnetic resonance imaging (MRI) examinations, typically achieved with multiple short-axis bright-blood cine steady-state free precession (SSFP) acquisitions. The accuracy of ventricular volume, ejection fraction (EF), and mass measurements by cardiac MRI has been validated, [1][2][3][4][5] and cine SSFP is now widely used in practice as a clinical reference standard. 6,7 However, cardiac MRI exams often require advanced operator skills to identify appropriate scan planes and to optimize acquisition parameters, particularly in the setting of congenital heart disease (CHD).…”

Review of Journal of Cardiovascular Magnetic Resonance 2015

“…The varia section contains papers of interest that do not easily fall into a larger well described category, and includes valve disease, [194] ventricular function, [195–198] mass, [199] and shape, [200] pericardium, [201] position papers, [202] safety papers, [203] summary papers, [204] reviews, [205] and errata [206, 207]. …”