Assessment of Left Ventricular Function and Mass by MR Imaging: A Stereological Study Based on the Systematic Slice Sampling Procedure

Abstract

Rationale and Objectives: The aim of this study was to combine the stereological technique with magnetic resonance (MR) imaging data for the volumetric and functional analysis of the left ventricle (LV). Materials and Methods: Cardiac MR examinations were performed in 13 consecutive subjects with known or suspected coronary artery disease. The end-diastolic volume (EDV), end-systolic volume, ejection fraction (EF), and mass were estimated by stereology using the entire slice set depicting LV and systematic sampling intensities of 1/2 and 1/3 that provided samples with every second and third slice, respectively. The repeatability of stereology was evaluated. Stereo logical assessments were compared with the reference values derived by manually tracing the endocardial and epicardial contours on MR images. Results: Stereo logical EDV and EF estimations obtained by the 1/3 systematic sampling scheme were significantly different from those by manual delineation (P<.05). No difference was observed between the reference values and the LV parameters estimated by the entire slice set or a sampling intensity of 1/2 (P>.05). For these stereological approaches, a high correlation (r(2) = 0.80-0.93) and clinically acceptable limits of agreement were found with the reference method. Stereological estimations obtained by both sample sizes presented comparable coefficient of variation values of 2.9-5.8%. The mean time for stereological measurements on the entire slice set was 3.4 +/- 0.6 minutes and it was reduced to 2.5 +/- 0.5 minutes with the 1/2 systematic sampling scheme. Conclusion: Stereological analysis on systematic samples of MR slices generated by the 1/2 sampling intensity provided efficient and quick assessment of LV volumes, function, and mass.