Computerized quantification of left ventricular volumes on cardiac magnetic resonance images by level set method

Abstract

Cardiac magnetic resonance imaging (MRI) allows accurate and noninvasive measurements of left ventricular (LV) volumes. Nonetheless, chamber volume quantification is based on manual tracing of endocardial boundaries, which is subjective and time-consuming. We developed a technique for semi-automated detection of 3D endocardial surfaces from MRI data and direct quantification of volumes, and validated it against conventional manual tracing. Eleven patients underwent cardiac MRI (GE, 1.5T FIESTA, short axis views). Custom software was used to semi-automatically detect the LV endocardial surfaces from the MRI data. End-systolic (ESV) and end-diastolic (ESV) volumes were computed directly from voxel counts. Linear regression and Bland–Altman analyses were used to compare semi-automated versus manually traced ventricular volumes and ejection fraction (EF). Semi-automated EDV and ESV showed high correlations with manual values both in EDV and ESV ( r=0.97, 0.99, respectively) and EF ( r=0.93). No biases and narrow limits of agreement in EDV, ESV and EF estimates were found and a small interobserver variability was calculated for both volumes and EF. The method results in an accurate detection of endocardial surfaces and direct measurement of ventricular volumes and EF.