[Practical problems of determining liver volume from computed tomographic transverse sections].

The article confronts the traditional methods of volume calculation ("layer method"); addition of partial volumes derived from the thickness of the individual strata and their area) with a new method of including the longitudinal extension of the liver into the calculations ("topographic method"). Using a model of a liver with defined volume as basis (continuous examination every 8 mm.), various constellations of layer sequence to be expected in CT practice, are simulated and the volumes calculated from the changed data by means of both methods. It has been found that calculation of volume according to the topographic method is superior to the layer method if the respiratory position of the patient changes from layer to layer during an examination and/or if the distances between the individual layers are irregular in the course of an examination. Recommendations are given for the procedure to be followed during CT examination carried out for computing the liver volume, and for a liver volume calculation to be based on a CT examination which has already been performed.