Evaluation of microwave thermotherapy with histopathology, magnetic resonance imaging and temperature mapping.

PURPOSE

Interstitial temperature mapping was used to determine the heat field within the prostate by the Coretherm (ProstaLund, Lund, Sweden) transurethral microwave thermotherapy device. Gadolinium enhanced magnetic resonance imaging (MRI) and histopathology were used to determine the extent and pattern of coagulation necrosis following treatment. The cell kill assessment feature of the device was compared with MRI and histopathology.

MATERIALS AND METHODS

A total of 12 patients were treated, including 5 with adenocarcinoma of the prostate and 7 with benign prostatic hyperplasia. Temperature sensors were inserted from the perineum to map the temperature distribution. The 5 patients with adenocarcinoma underwent prostatectomy and subsequent histopathology 3 to 6 weeks after treatment. MRI and cell kill calculations were performed in all patients.

RESULTS

Therapeutic temperatures were found in a bowl-like shape with a wide circumference of highest temperatures at the base of the prostate, and decreasing temperature and circumference toward the apex. Tissue necrosis assessed by histopathology, MRI and cell kill calculations overlapped reasonably well in shape and size. Histopathology showed that the prostatic urethra was destroyed by treatment.

CONCLUSIONS

Coretherm microwave treatment causes significant tissue necrosis of the prostate, bladder neck and urethral mucosa. The cell kill calculation provides an on-line estimate of the amount of necrosis caused during treatment.