Fig. 4

The process of obtaining the manual centerline length. Initial centerline is obtained by tracing a poly-line on the multi-slice scan (red), dotted line indicates that the anchor points are out-of-plane (a). Multi-planer reformatted (MPR) image obtained using the initial centerline, sampled at a distance of 1 mm (overlaid in red) (b). Refining the centerline on the MPR axial slice by dragging points (red) in the middle of the lumen when required (c). MPR image stack generated using the refined centerline points (d)