Stephen R. Tolhurst

High Intensity Focused Ultrasound Renal Tissue Ablation: A Laparoscopic Porcine Model

PURPOSE High intensity focused ultrasound for renal lesions is still experimental. In a porcine model we evaluated the safety and efficacy of a newly designed laparoscopic high intensity focused ultrasound probe and software that allows real-time ultrasound guidance during renal tissue ablation. MATERIALS AND METHODS A Sonatherm 600 high intensity focused ultrasound system with a newly designed laparoscopic high intensity focused ultrasound probe was used through a standard Endopath 18 mm port. A total of 16 lesions were created in 15 kidneys in a total of 8 animals and randomized into 2 groups, including acute with sacrifice 4 days postoperatively and subacute with sacrifice 14 days postoperatively. Lesion size and location varied for each surgical procedure to simulate various treatment scenarios. RESULTS Mean +/- SD planned ablation volume was 7.1 +/- 5.1 cc and mean treatment time was 7.2 +/- 06.88 minutes. For all lesions an injury volume was observed with a central zone of complete necrosis and no viable tissue. Mean total injury volume was 6.5 + 3.5 cc (range 1.1 to 13.7), comparable to preoperative mean planned ablation volume (p = 0.84). Mean necrosis volume was 4.89 +/- 2.9 cc (range 0.8 to 10.5), appreciably lower than preoperative mean planned ablation volume (p = 0.33). Presence of the collecting system interposed with the treatment region did not impact the injury volume-to-planned ablation volume ratio or the necrosis volume-to-planned ablation volume ratio. No animals died before study completion. Two intraoperative complications occurred, including a back wall musculature burn and a ureteral burn. CONCLUSIONS Laparoscopic high intensity focused ultrasound for renal tissue using the newly developed probe was feasible and efficacious. The ability to perform renal high intensity focused ultrasound through an 18 mm laparoscopic port offers a new alternative for renal tumor ablation.

Post-Operative Changes Mimicking the Radiographic Appearance of Recurrent Renal Cell Carcinoma

Partial nephrectomy for small renal tumors is associated with excellent long-term outcomes. In the absence of positive surgical margins, local recurrence is uncommon. Although computed tomography is associated with good diagnostic accuracy, the radiographic evaluation of some renal lesions remains difficult. This difficulty can be greater in the period following surgery, when post-operative tissue changes can result in abnormal radiographic findings. We report a case of benign post-operative changes mimicking the radiographic appearance of recurrent renal cell carcinoma.