Occlusion Angiography Using Intraoperative Contrast-enhanced Ultrasound Scan (CEUS): A Novel Technique Demonstrating Segmental Renal Blood Supply to Assist Zero-ischaemia Robot-assisted Partial Nephrectomy

Background Recent innovations in technology and operative techniques have enabled safe performance of robot-assisted zero-ischaemia partial nephrectomy (PN), thus preventing the deleterious effect of warm ischaemia time. Objective To describe a novel technique of occlusion angiography using intraoperative contrast-enhanced ultrasound scan (CEUS) for zero-ischaemia robot-assisted PN (RAPN). Design, setting, and participants We used a prospective cohort evaluation of five patients who had imaging suspicious of renal cell carcinoma (RCC) treated at a single centre. Surgical procedure We used computed tomography with three-dimensional reconstruction to identify renal arterial anatomy and its relationship to the tumour. Then, RAPN was performed with selective clamping and demonstration of a nonperfused segment of kidney (occlusion angiography) using intraoperative CEUS. Outcome measurements and statistical analysis We prospectively collected data on baseline, perioperative, and postoperative parameters. Results and limitations We describe the effects seen on ultrasound contrast administration. Contrast flare is seen in the segment of the kidney that is perfused. When selective clamping is performed, a watershed (line of demarcation) between the perfused and nonperfused segments of the kidney is clearly seen, allowing excision of the tumour in a relatively avascular plane and ensuring an adequate oncologic margin, when feasible. The mean age was 68.2 yr of age (range: 36–85), and the mean tumour size was 29.6mm (range: 20–42). The mean intraparenchymal extension of the tumour was 22.6mm (range: 12–30). Three tumours were located on the right kidney and two on the left. The mean blood loss was 420ml (range: 200–1000). The histology revealed clear cell RCC in two patients, oncocytoma in two patients, and type 1 papillary RCC in one patient. All the surgical specimens had negative surgical margins. The mean decrease in glomerular filtration rate was 8.4ml (range: 0–24). The mean follow-up was 6.4 mo (range: 5–8), with no evidence of recurrence in any patient. The only limitation in adopting this technique is the need for an intraoperative ultrasound probe with a CEUS mode. However, most specialists who perform minimally invasive surgery for small renal tumours believe that intraoperative ultrasound scan imaging is essential to achieving adequate resection margins. Conclusions Intraoperative CEUS can be a useful adjunct in determining whether zero-ischaemia RAPN is feasible by delineating the area of nonperfusion. This technique has several advantages over the currently available techniques, such as indigo carmine green and Doppler probes.