Dynamic contrast enhanced CT measurement of blood flow during interstitiallaser photocoagulation: comparison with an Arrhenius damage model

One effect of heating during interstitial laser photocoagulation (ILP) is t o directly destroy the tumour vasculature resulting in a loss of viable blo od supply. Therefore, blood how measured during and after treatment can be a useful indicator of tissue thermal damage. In this study, the effect of I LP treatment on rabbit thigh tumours was investigated by measuring blood fl ow changes using dynamic contrast enhanced computed tomography (CT). The CT measured changes in blood flow of treated tumour tissue were fitted to an Arrhenius model assuming first order rate kinetics. Our results show that changes in blood flow of tumour tissue distant from surrounding normal tissue are well described by an Arrhenius model. By contrast, the temperat ure profile of tumour tissue adjacent to normal tissue must be modified to account for heat dissipation by the latter. Finally, the Arrhenius paramete rs derived in the study are similar to those derived by heating tumour tiss ue to a lower temperature (<47 degrees C) than the current study. In conclusion, CT can be used to monitor blood flow changes during ILP and these measurements are related to the thermal damage predicted by the Arrhe nius model.