Ultrasound-guided Thermocouple Placement for Cryosurgery

BACKGROUND: Although cryosurgical methods have high cure rates, imprecise estimates of both skin lesion depth and destructive temperature front location result in subjective technique in skin malignancy treatments. OBJECTIVE: We evaluated the possibility of newer ultrasound equipment to assist in the precise placement of thermocouples in human skin. METHODS: DermaScan C ver. 3 ultrasonographic equipment fitted with a sharp focus probe with a frequency of 20 MHz and a scan length of 12.1 mm was used to locate thermocouples with 27- and 30-gauge needles. RESULTS: We successfully and reproducibly located thermocouples and thin needles, and accurately measured their distance from the skin surface. CONCLUSION: Ultrasound is a useful method for the accurate placement of thermocouples, and needles as thin as 30 gauge for monitoring in cryosurgery.