Volumetry of brain tumors on CT

The present authors have developed a system of estimating the growth rate of malignant brain tumors by calculating the volume of the tumor from serial CT scanning. The given cell-cycle time and the growth curve of the malignant neoplasm are important factors in evaluating the efficacy of the treatment and in predicting the final outcome in a relatively reliable fusion. An accurate determination of the volume of a particular tumor is imperative if we are to obtain a reliable value in measuring the cell-cycle time. In order to attain this goal, we assessed the following items: 1) The calculated volumes of some brain tumors on CT were compared with the measured volume of surgically resected specimens. 2) The same comparison was performed in several kinds of phantoms; furthermore, the relative values of the actual volume ratio of 2 different sizes of phantoms and the volume ratio on CT of them were appraised. Eight cases were examined in the former study. The results showed that the magnifying rates of the tumor volume by CT were near in all cases. In the latter study, several different sizes of phantoms made of the same substance were enlarged by CT to almost the same degree; moreover, either of the above-cited volume ratios resulted in significantly approximated that. That is to say, it is conceivable that the volume ratio of the tumor in 2-serial CT scanning can be taken as close to the ratio of the tumor proper. (author)