Validation of estimated 3D temperature maps during hepatic cryo surgery

A simple model for estimating temperature distribution within the frozen re gion during cryo ablation was tested for accuracy. Freezing experiments wer e conducted in both ex vivo and in vivo porcine livers. Temperature was mea sured during freezing using a fiber-optic temperature sensor. Three-dimensi onal MR images were obtained at the end of each freezing cycle. From the MR image volumes, three-dimensional temperature maps were calculated numerica lly using a simplified bio-heat model. Estimated temperatures were compared to measured temperatures. The median difference between measured and estim ated temperature was 3.03 degreesC. The median distance from a sensor eleme nt to the closest point on a isotherm surface with the corresponding estima ted temperature was 0.70 mm. The accuracy of this model is acceptable. Temp erature maps as outlined here may be used for monitoring of cryotherapy in order to increase clinical effectiveness. (C) 2001 Elsevier Science Inc. Al l rights reserved.