Disclosure of the significant thermal effects of large blood vessels during cryosurgery through infrared temperature mapping

During cryosurgery the large blood vessels entering the frozen volume can be an important source of temperature non-uniformity and possible under-dosage for the target tissues. In this study, the thermal effects of large vessels during cryosurgery were experimentally investigated by introducing infrared thermography system on monitoring both simulated and animal experiments. For all experiments, the freezing was supplied by a 5 mm diameter cryoprobe with liquid nitrogen running through. Tissue temperature responses during freezing and thawing were recorded by an infrared thermography system. It was demonstrated that for different geometrical configurations between the simulated vessels and the positioning of the cryoprobe, a very different temperature profile will be induced even under the same freezing. The results for the cases with single vessel and with count-current vessel pairs indicated that different vascular models produce significantly different temperature responses for a given freezing pattern. Both the simulated and animal experiments suggested that the heating nature of the flowing blood in the large vessels can produce steep temperature gradients and inadequate cooling to the frozen tissues, and therefore may seriously contribute to failed-killing of tumor during cryosurgery. The physical pictures disclosed in this paper may help planning more successful cryosurgery in the near future.