Dynamic computed tomography predicts tumor temperature and response to thermoradiotherapy in superficial and subsurface tumors.

Abstract

Dynamic computed tomography (CT) was performed on patients undergoing thermoradiotherapy for superficial or subsurface tumors, and the correlation between tumor enhancement and tumor temperature during hyperthermia was evaluated. The authors further investigated whether tumor enhancement by dynamic CT is predictive of tumor response to thermoradiotherapy. Thermoradiotherapy was given to 26 patients. Radiotherapy consisted of 40-70 gray. Hyperthermia was conducted over 3-5 sessions, and tumor temperature was measured at each session. Dynamic CT was performed prehyperthermia (within 1 week before the initiation of hyperthermia) and midtherapy (within 1 week after 2 sessions of hyperthermia). A complete response (CR) was obtained in 11 patients (42%) and either a partial response or no response (non-CR) in 15 (58%). There was no correlation between tumor enhancement obtained by prehyperthermia CT and tumor temperature parameters or response. However, the deltaCTmax (maximum increased enhancement) by prehyperthermia and midtherapy CT was 39.0 +/- 18.9 HU and 26.1 +/- 14.2 HU, respectively, in CR patients, and 46.4 +/- 21.1 HU and 49.6 +/- 19.1 HU, respectively, in non-CR patients. This change in deltaCTmax at midtherapy was significantly different between groups (P < 0.01). The deltaCTmax ratio for prehyperthermia and midtherapy CT studies correlated with the average tumor temperature (P < 0.05). Tumor enhancement by prehyperthermia and midtherapy dynamic CT predicted tumor temperature during hyperthermia and response to thermoradiotherapy for superficial or subsurface malignancies.