shape_stats = sitk.LabelShapeStatisticsImageFilter()
vol_roi = shape_stats.GetPhysicalSize(1)
to get a Region of interest volume. However, I am not sure of the unit. I looked at the same mask in ITK Snap and it is in mm3. But I am not sure if it is accurate as it seems the physical size is the number of voxels within the mask.
Should I multiply it with the voxel size to get accurate volume measurement?