Straightened Segmentation in 4D Cardiac CT: A Practical Method for Multiparametric Characterization of the Landing Zone for Transcatheter Pulmonary Valve Replacement

Cardiac computed tomography angiography (C-CTA) is crucial in assessing the right ventricular outflow tract (RVOT) prior to a transcatheter pulmonary valve replacement (TPVR), as an incorrect evaluation can make the procedure more challenging and can lead to device-related complications. This study aimed to evaluate the feasibility and accuracy of 4D straightened segmentation for a landing zone analysis over anatomical segmentation. Seven pre-operative CTAs and seven post-operative CTAs were used to measure the cross-sectional area, circumference, and diameters at five selected planes as the landing zone for TPVR and compared these to the 4D straightened model with the anatomical model. Furthermore, the right ventricular volume, stent volume, and 4D ellipticity index were calculated from the 4D straightened model. The 4D straightened segmentation had comparable accuracy and efficacy for the measurements at the landing zone. The cross-sectional area and the circumference varied greatly at the RVOT and the basal plane of the pulmonary valve compared with the other three planes of the 4D straightened models from the pre-operative CTAs; however, only the values at the RVOT were found to vary greatly from the post-operative CTAs. The 4D straightened model can provide accurate measurements and is thus a useful method for the periprocedural evaluation of TPVR.