Transurethral needle ablation (TUNA): thermal gradient mapping and comparison of lesion size in a tissue model and in patients with benign prostatic hyperplasia.

A new device has been development for treating benign prostatic hyperplasia (BPH) that is performed as an outpatient procedure. the device (transurethral needle ablation or TUNA) employs needles that deliver low-level radiofrequency (RF) power locally at high temperature to ablate hyperplastic prostate tissue. During the TUNA procedure the temperature proximal to the needle tips is measured with thermocouples within the needle's protective shields and urethral temperature is measured via a thermocouple contained within the catheter tip. Tissue impedance is also measured by the TUNA catheter since it is well known from other thermal treatment methods that thermal destruction of prostatic tissue depends upon a particular prostate's tissue composition and thermoregulation. Because of this variation in prostates, a nomogram guide for setting the TUNA device was created using a turkey breast tissue model. Lesion sizes created at particular settings in the turkey breast model were similar to those created at the same settings in patients with BPH. In addition, local thermal gradients within the TUNA lesions were visualized and mapped using an infrared thermal imaging system which demonstrated that central lesion temperature with the device is approximately 80-100 degrees C.