Using the OsirixTM software, one can calculate volume from a CT scan. The procedure of the volume assessment of a specific structure is performed in the axial projection of the CT scan. The procedure has three steps:
First, the user manually outlines the structure in various axial CT scan views, using the “Closed Polygon” tool from the “ROI tools”.
Then, the software, automatically, creates the total volume of the structure by generating the missing regions of interest, choosing the option “Generate Missing ROIs” from the ROI menu.
Last, the calculation of total volume and the assessment of the structure radiodensity (in Hounsfield Units, HU) is done automatically, choosing the option “Compute Volume” from the ROI menu. The following pieces of information are given: total volume of the outlined structure (cm3), and radiodensity of the structure.