Drawing the central line of SV. A. P0 indicates the starting point of the SV, located in the first axial slice where both prostate and SV are visible. It is determined by referencing the coronal and the sagittal views to ensure that it is centered in the SV contour in both planes. B. Pend indicates the ending point of the SV in the last slice. The exact location needs to be determined by referencing the morphology in both the coronal and the sagittal planes. C. After locating the starting and ending points, an oblique coronal plane containing both endings is obtained by rotating the cut lines in the sagittal window. The central line is determined by drawing a curve connecting P0 and Pend along the middle line of the SV.