Patient-specific variability in breath-hold positions during cardiac magnetic resonance imaging has a negligible effect on measures of cardiac mechanics

Background Cardiac magnetic resonance (CMR) can be used to quantify cardiac mechanics from images that are generally acquired during an end-expiratory breath-hold. Unfortunately, it is difficult for subjects to hold their breath at the exact same position when undergoing a series of breath-holds during a typical CMR study. The effect of patient-specific variability in breath-hold positions on measures of cardiac mechanics has not been investigated. We hypothesized that normal variability in breath-hold positions would significantly affect estimates of left ventricular strains and torsion.