Geometry-independent inclusion of basal myocardium yields improved cardiac magnetic resonance agreement with echocardiography and necropsy quantified left-ventricular mass

Abstract

Objectives LV mass (LVM) is widely used to guide clinical decision-making. Cardiac magnetic resonance (CMR) quantifies LVM by planimetry of contiguous short axis images, an approach dependent on reader-selection of images to be contoured. Established methods have applied different binary cutoffs using circumferential extent of LV myocardium to define the basal LV, omitting images containing lesser fractions of LV myocardium. This study tested impact of basal slice variability on LVM quantification. Methods CMR was performed in patients and laboratory animals. LVM was quantified with full inclusion of LV myocardium, and by established methods that use different cutoffs to define the LV basal-most slice: (1) 50% circumferential myocardium at end-diastole alone (ED50), (2) 50% circumferential myocardium throughout both end-diastole and end-systole (EDS50). Results 150 patients and 10 lab animals were studied. Among patients, fully inclusive LVM (172.6±42.3gm) was higher vs. ED50(167.2±41.8gm) and EDS50(150.6±41.1gm; both p<0.001). Methodological differences yielded discrepancies regarding proportion of patients meeting established criteria for LV hypertrophy and chamber dilation (p<0.05). Fully inclusive LVM yielded smaller differences with echocardiography (Δ=11.0±28.8gm) than did ED50 (Δ=16.4±29.1gm) and EDS50 (Δ=33.2±28.7gm, both p<0.001). Among lab animals, ex-vivo LV weight (69.8±13.2gm) was similar to LVM calculated using fully inclusive (70.1±13.5gm, p=0.67) and ED50 (69.4±13.9gm, p=0.70) methods, whereas EDS50 differed significantly (67.9±14.9gm, p=0.04). Conclusions Established CMR methods that discordantly define the basal-most LV produce significant differences in calculated LVM. Fully inclusive quantification, rather than binary cutoffs that omit basal LV myocardium, yields smallest CMR discrepancy with echocardiography-measured LVM and non-significant differences with necropsy-measured LV weight.

Clinical Validation of a 3-Dimensional Ultrafast Cardiac Magnetic Resonance Protocol Including Single Breath-Hold 3-Dimensional Sequences

“…The image quality obtained with the ESSOS technique translated into very good agreement between 3D and 2D cine measurements. The documented observer variability was comparable to the reproducibility obtained with the standard (2D) technique ( 20 , 21 , 22 ) and other validation studies using accelerated approaches ( 6 , 23 ), with most of the observer variability in ESSOS resulting from discrepancies in the definition of the basal-most short-axis slices ( 24 ). Despite the overall good agreement and reliability between 3D and 2D LGE measures, 3D LGE imaging tended to slightly overestimate the LGE area.…”

Fully automated quantification of biventricular volumes and function in cardiovascular magnetic resonance: applicability to clinical routine settings

“…Furthermore, ED and ES time points were manually pre-selected. However, the correct definition of the most basal slice is amongst the most challenging steps in SAX volume assessments and one of the most important source of observer variability [ 22 ], therefore representing a clear bias in testing the reliability of an automated algorithm. In the present study, we sought to simulate a real-world clinical scenario by randomly selecting patients from clinical routine imaging.…”

Impact of advanced imaging techniques on cardiac surgery—New insights provided by cardiac magnetic resonance

“…Despite these strengths, it should be noted that echo can be compromised by a number of shortcomings, including artifacts that can obscure cardiac chamber visualizations and quantitative formulae (e.g., ejection fraction) that rely on global geometrical assumptions which may be inaccurate in a number of clinical settings-including in postmyocardial infarction and/or heart failure patients, in whom LV shape can be regionally altered. CMR provides high resolution functional ("cine") imaging with excellent endocardial definition, enabling identification of subtle changes in regional wall motion (pre-or postoperatively) that can be challenging to discern on echo.Regarding global LV size and function, cine-CMR enables volumetric quantification without geometric assumptions-an approach that our group and others have shown to be more reproducible than echo, and to closely agree with necropsy evidenced LV mass and phantomverified chamber size [7][8][9][10]. CMR has also been shown to provide precise quantification of valvular flow, for which it has been shown to identify patients who deem particular benefit from valve surgery as evidenced by LV reverse remodeling 11.…”