A Novel Approach to Energy Ablative Therapy of Small Renal Tumours: Laparoscopic High-Intensity Focused Ultrasound

Abstract

ObjectiveHigh-intensity focused ultrasound (HIFU) permits targeted homogeneous ablation of tissue. The objective of this phase 1 study was to evaluate the feasibility of HIFU ablation of small renal tumours under laparoscopic control. Patients and methodsTen kidneys with solitary renal tumours were treated with a newly developed 4.0MHz laparoscopic HIFU probe. In the first two patients with 9-cm tumours, a defined marker lesion was placed prior to laparoscopic radical nephrectomy. In eight patients with a mean tumour size of 22mm (range, 11–40), the tumour was completely ablated as in curative intent, followed by laparoscopic partial nephrectomy in seven tumours. One patient had post-HIFU biopsies and was followed radiologically. Specimens were studied by detailed and whole-mount histology, including NADH stains. ResultsMean HIFU insonication time was 19min (range, 8–42), with a mean targeted volume of 10.2cm3 (range, 9–23). At histological evaluation both marker lesions showed irreversible and homogeneous thermal damage within the targeted site. Of the seven tumours treated and removed after HIFU, four showed complete ablation of the entire tumour. Two had a 1- to 3-mm rim of viable tissue immediately adjacent to where the HIFU probe was approximated, and one tumour showed a central area with about 20% vital tissue. There were no intra- or postoperative complications related to HIFU. ConclusionThe morbidity of laparoscopic partial nephrectomy mainly comes from the need to incise highly vascularized parenchyma. Targeted laparoscopic HIFU ablation may render this unnecessary, but further studies to refine the technique are needed.