Regional strain (RS) can be rapidly obtained from standard gated coronary CCTA protocols using 4DCT SQUEEZ processing. We estimate that 95% of normal LV end-systolic RS values will fall between -23% and -43%; therefore, we hypothesize that an RS value higher than -23% will indicate a hypokinetic segment in the human heart.

Abstract:Background: Measuring local RV function in adult congenital heart disease (ACHD) 25 with echocardiography or MRI is challenging because of the complex geometry and existing pacing devices. Visual assessment of ventricular function via low-dose cardiac CT has been recently performed. This pilot study assessed whether low-dose 4D cine CT combined with automatic measurement of regional shortening could quantify rightventricular function in ACHD patients. 30

Aims To develop an automated method for bloodpool segmentation and imaging plane re-slicing of cardiac CT via deep learning (DL) for clinical use in coronary artery disease (CAD) wall motion assessment and reproducible longitudinal imaging. Methods and Results 100 patients who underwent clinically indicated cardiac CT scans with manually segmented left ventricle (LV) and left atrial (LA) chambers were used for training. For each patient, long-axis (LAX) and short-axis (SAX) planes were manually defined by an imaging expert. A DL model was trained to predict bloodpool segmentations and imaging planes. DL bloodpool segmentations showed close agreement with manual LV (median Dice: 0.91, Hausdorff distance: 6.18mm) and LA (Dice: 0.93, HD: 7.35mm) segmentations and strong correlation with manual EF (Pearson r: 0.95 LV, 0.92 LA). Predicted planes had low median location (6.96mm) and angular orientation (7.96 °) errors which were comparable to inter-reader differences (p > 0.71). 84 – 97% of DL-prescribed LAX planes correctly intersected American Heart Association (AHA) segments, which was comparable (p > 0.05) to manual slicing. In a test cohort of 144 patients, we evaluated the ability of the DL approach to provide diagnostic imaging planes. Visual scoring by two blinded experts determined ≥94% of DL-predicted planes to be diagnostically adequate. Further, DL enabled visualization of LV wall motion abnormalities due to CAD and provided reproducible planes upon repeat imaging. Conclusion A volumetric, DL approach provides multiple chamber segmentations and can re-slice the imaging volume along standardized cardiac imaging planes for reproducible wall motion abnormality and functional assessment.