Training for renal ablative technique using an agarose-based renal tumour-mimic model.

OBJECTIVE: To assess whether a recently developed porcine tumour-mimic model can serve as a training model for radiofrequency ablation (RFA) of renal masses, as the increased diagnosis of small occult renal masses has led to the development of nephron-sparing treatments, including RFA, and the techniques required for effective tumour ablation can be difficult to master. MATERIALS AND METHODS: Tumour mimics were created by injecting 0.7 mL of an agarose mixture into the parenchyma of a porcine kidney, producing 1-cm spherical lesions which were hyperechoic on ultrasonography (US). The ex vivo experiment included creating 40 tumour mimics followed by RFA using US-guided needle placement. The ablation diameter was set to 15 mm to produce a margin of grossly ablated tissue around the mimic lesions. The in vivo portion involved creating 20 tumour mimics and ablating them under direct laparoscopic vision with US-guided probe placement. In each case, the mimic lesion size by US and gross examination, ablation diameter, and completion (accuracy) of ablations were recorded. RESULTS: Accurate placing of the RFA needle by US guidance was difficult to learn, as all tumour-mimic lesions were either endophytic or completely intraparenchymal. The ex vivo model required approximately 15 ablations before the needle was placed consistently into the lesions. The in vivo model was equally difficult to learn, with five positive margins by gross examination in the first 10 ablations, while the subsequent 10 had no positive margins. CONCLUSION: The agarose-based tumour mimic is a useful target model for learning and improving US-guided ablative techniques in both the ex vivo and in vivo settings. The tumour-mimic allows the surgeon to assess targeting accuracy in an animal model. Further studies are needed to determine this model's utility as a clinical training aid.

Cytokine response to surgical stress: comparison of pure laparoscopic, hand-assisted laparoscopic, and open nephrectomy.

BACKGROUND AND PURPOSE: Laparoscopic surgery has been shown to induce less immune suppression than open surgery, presumably because there is less tissue trauma, a factor that may impact oncologic-disease control. The objective of this study was to compare the cytokine and stress response associated with pure laparoscopic, hand-assisted laparoscopic (HAL), and open nephrectomy. MATERIAL AND METHODS: Fifteen female farm pigs (45-50 kg) underwent transperitoneal laparoscopic, handassisted (HAL), or open nephrectomy (N = 5 in each group). At 1, 4, 24, and 48 hours post-nephrectomy, blood and peritoneal fluid samples were collected for measurement of tumor necrosis factor (TNF) alpha, interleukin (IL)-1beta, and IL-6 using enzyme-linked immunosorbent assay (ELISA) techniques. Body temperature and serum glucose and cortisol were also measured. RESULTS: No evidence of perioperative infection was detected in any animal through temperature and glucose monitoring. Operating time and blood loss were comparable among the three groups. Peak serum cortisol concentrations were significantly higher in the HAL group than in the pure laparoscopic group at 24 hours (P = 0.02). Serum TFNalpha concentrations were significantly lower in the pure laparoscopy group (40 +/- 6 pg/mL) than in the HAL and open-nephrectomy groups (81 +/- 6 pg/mL and 83 +/- 17 pg/mL, respectively; P < 0.05), although no differences between groups were found in the serum IL-1beta and IL-6 concentrations. Peritoneal IL-1beta was significantly higher in the HAL than in the open-nephrectomy group (2993 +/- 507 pg/mL and 733 +/- 185 pg/mL, respectively; P = 0.05). Peritoneal IL-6 was significantly lower in the pure laparoscopy group (694 +/- 234 pg/mL) than in the open-surgery group (1668 +/- 312 pg/mL) (P = 0.04). CONCLUSION: Pure laparoscopic surgery in pigs elicits a less-robust cytokine response than HAL or open nephrectomy with respect to serum TNFalpha and peritoneal IL-6 concentrations, perhaps reflecting less impairment of the immune system. Clinical confirmation is required, and the implications with regard to oncologic tumor surveillance in humans require further study.

Hand-assisted laparoscopic nephrectomy for renal masses >9.5 cm: series comparison with open radical nephrectomy.

OBJECTIVE: To assess the feasibility of hand-assisted laparoscopic nephrectomy (HALN) for large renal masses (stage T2, mean size 9.7 cm) and compare outcomes with a similar cohort undergoing open radical nephrectomy (ORN). METHODS: A nonrandomized comparison of 19 consecutive patients who underwent nephrectomy for renal masses >or=7 cm was performed. The HALN group was compared to the ORN group regarding demographic parameters and perioperative data, including blood loss, operating time, narcotic usage, hematocrit change, return to standard oral intake, length of hospital stay, and complications. Data collected prospectively and statistics used 2-tailed t-test analysis. RESULTS: Patients underwent either ORN (mean tumor size 12.3 cm) or HALN (mean tumor size 9.7cm). Tumors up to 14 cm (n = 2) and pT3b, with renal vein thrombosis (n = 2), could be safely excised with HALN. There were no differences between the HALN and ORN groups regarding any demographic parameter. Blood loss, operating time, length of stay, parenteral narcotic use, and time to tolerating regular diet were all less statistically significant in the HALN group as compared to the ORN group (P < 0.05). Tumors >15 cm necessitated ORN. CONCLUSIONS: HALN is technically feasible even for tumors with mean size >9.5 cm. There is a significant advantage to HALN over ORN regarding the intraoperative and postoperative morbidity. Tumors >or=15 cm should, in most cases, be performed with an open approach.

Contrast-enhanced ultrasound evaluation of radiofrequency ablation of the kidney: reliable imaging of the thermolesion.

BACKGROUND AND PURPOSE: Radiofrequency ablation (RFA) is limited by the inability to monitor progression of the thermal lesion. Contrast-enhanced ultrasonography (CEUS) imaging has considerable potential as a monitoring modality for RFA. We report our experience using CEUS to evaluate the lesion produced by RFA in a porcine model. MATERIALS AND METHODS: Five pigs underwent laparoscopic RFA twice, spaced by a 1-week interval. Post- RFA ultrasound imaging was performed transcutaneously immediately after ablation. The kidneys were assessed for a contrast void corresponding to the ablated tissue. The kidneys were then harvested and the gross RFA lesions measured to compare lesion size with that measured using CEUS. RESULTS: A clear lesion was identified at the site of each RFA application. As measured by CEUS, the acute lesions averaged 1.8 +/- 0.4, 1.7 +/- 0.4, and 1.8 +/- 0.3 cm in length, height, and width, respectively, compared with 2.0 +/- 0.5, 1.8 +/- 0.4, and 1.9 +/- 0.3 cm, respectively, by measurement in the gross specimen (P = 0.33, 0.13, and 0.44, respectively). At 1 week, the CEUS-measured dimensions of the lesions were 2.7 +/- 0.5, 2.6 +/- 0.6, and 2.6 +/- 0.6 cm, and the gross measurements of the lesion were 2.7 +/- 0.4, 2.7 +/- 0.9, and 2.6 +/- 0.4 cm (P = 0.75, 0.92, and 0.40, respectively). CONCLUSIONS: Contrast-enhanced ultrasonography appears to be an accurate modality for immediate monitoring of RFA defects. Further study is necessary to assess the clinical utility of CEUS for monitoring RFA of small renal lesions.

Hand assisted laparoscopic cystectomy with minilaparotomy ileal conduit: series report and comparison with open cystectomy.

PURPOSE: To achieve less patient morbidity our initial experience with hand assisted laparoscopic (HAL) cystectomy was compared with our results of open cystectomy with similar urinary diversion. MATERIALS AND METHODS: During 18 months 36 cystectomies were performed, including 20 with open continent diversion. A prospective, nonrandomized comparison of the remaining 16 consecutive cystectomies with ileal conduit diversion (hand assisted laparoscopic cystectomy and open cystectomy in 8 cases each) was performed. Of the 16 cystectomies 13 were performed for muscle invasive bladder cancer. Standard parameters were compared concerning patient operative and postoperative courses using statistical analysis with the 2-tailed t test. A novel surgical technique for completing these HAL procedures is described and compared to standard open cystectomy and ileal conduit diversion. RESULTS: A total of 16 patients successfully underwent open (8) and HAL (8) cystectomy with an ileal conduit. Mean estimated blood loss in the HAL and open groups was 637 and 957 cc, respectively (p = 0.23). The mean postoperative parenteral analgesia administered was 31 mg in the HAL group vs 149 mg in the open group (p = 0.01). The HAL and open groups had a mean length of stay of 6.4 vs 9.8 days (p = 0.06). Mean operative time did not differ significantly between the HAL and open groups (403 and 420 minutes, respectively). Regular diet was resumed at 4.5 days in the HAL group vs 7.9 days in the open group (p = 0.05). Hospital length of stay was 6.4 vs 9 days for HAL vs open cases (p = 0.06). CONCLUSIONS: To our knowledge this represents the first reported series of patients undergoing HAL cystectomy with urinary diversion. HAL cystectomy with an ileal conduit appears to have less estimated blood loss and postoperative analgesic requirements, shorter length of stay and earlier return of bowel function than open cystectomy. Oncological efficacy was preserved in the short term.

The radiographic evolution of radio frequency ablated renal tumors.

PURPOSE: Radio frequency ablation (RFA) of renal tumors is a relatively new technology. Few groups are familiar with the posttreatment appearance of these lesions and how they differ from cryoablated renal masses. We describe the evolution of the appearance of these lesions on followup contrast enhanced (CE) computerized tomography (CT). METHODS AND MATERIALS: A total of 64 consecutive renal tumors treated with RFA from April 2000 to September 2003 for which posttreatment CE-CT was done were included in this study. CE-CT was reviewed at 6 weeks, 3 months, 6 months and every 6 months thereafter to determine the characteristic features and evolution of these lesions. RESULTS: Renal tumors were treated with CT guided percutaneous (34), laparoscopic (28) or open (2) RFA. At a median followup of 13.7 months (range 6 weeks to 29 months) 62 RFA lesions demonstrated an absence of contrast enhancement on CE-CT. Treated endophytic tumors developed a low density, nonenhancing, wedge-shaped defect with fat infiltration seen between the ablated tissue and normal parenchyma. Treated exophytic tumors retained a configuration similar to that of the original with a lack of contrast enhancement and minimal shrinkage. Percutaneous treated lesions developed a peritumor scar or halo that demarcated ablated and nonablated tissue (perirenal fat). Persistent tumor was marked by contrast enhancement within the ablation borders of the original mass in 1 case, whereas tumor recurred after initial successful ablation with an enhancing nodule in 1. CONCLUSIONS: The radiographic features and evolution of radio frequency ablated renal tumors are unique. Successfully treated tumors demonstrated no contrast enhancement, minimal shrinkage and occasional retraction from normal parenchyma by fat infiltration.

Development of a renal tumor mimic model for learning minimally invasive nephron sparing surgical techniques.

PURPOSE: New laparoscopic partial nephrectomy and tumor ablation techniques are continuously being developed and evaluated in large animal models. However, to our knowledge no reliable renal tumor model exists to evaluate procedure efficacy. We developed and assessed the reliability of a tumor mimic model to serve as a training tool for minimally invasive kidney surgery. MATERIALS AND METHODS: An agarose based model was created using a mixture of 3% agarose, 3% cellulose, 7% glycerol and 0.05% methylene blue. It is liquid when heated, but solidifies after cooling to physiological temperatures. The agar was injected (0.7 cc) into porcine renal parenchyma to make endophytic or completely intraparenchymal lesions. Three-dimensional ultrasound images of the lesions were obtained during initial development to ensure spherical lesions. A group of 20 lesions was initially placed in an ex vivo setting to assess size consistency and define baseline impedance characteristics. An additional 20 tumor mimics each were established in a laparoscopic model in a laparoscopic box trainer and an in vivo laparoscopic model. They were ablated with a temperature based radio frequency generator to assess impedance characteristics but the efficacy of ablation was not assessed. The in vivo model consisted of placing the agar lesion percutaneously under direct laparoscopic vision. RESULTS: The agarose mixture was easily injected and readily visible on ultrasound as hyperechoic distinct lesions. Lesions had a mean size of 10.8 +/- SD 1.3 mm on ultrasound and 10.9 +/- 1.2 mm grossly. The impedance of normal renal parenchyma and unablated lesions was similar. Mean lesion size in the ex vivo model after radio frequency ablation was 9.8 +/- 2.0 mm on ultrasound, which was similar to the gross mean lesion size of 9.7 +/- 1.0 mm. Similar results were obtained for the in vivo model with a mean size of 10.1 +/- 2.1 and 10.4 +/- 1.5 mm, respectively. The lesions were easily identified grossly as blue solid lesions that replaced renal parenchyma. CONCLUSIONS: The described renal tumor mimic model reproducibly creates ex vivo and in vivo porcine kidney lesions. Lesion size and impedance do not change with the application of radio frequency energy. This model should be a valuable adjunct in the development, assessment and teaching of novel, nephron sparing, minimally invasive surgical techniques.

Applications of laparoscopic surgery in urology: impact on patient care.

From its first use as a diagnostic tool, urologic laparoscopy has developed into a complex therapy for both benign and malignant disease. Most procedures are still performed at large centers with experienced laparoscopists but nonacademic urologists are starting to gain the necessary training and skills. With the clear advantage that laparoscopy shows over open procedures in terms of decreased perioperative morbidity and quicker recovery times, patients are increasingly asking for this approach. The urologic community must meet this challenge and train future urologists to meet the expected demand.

The effects of radio frequency ablation on renal function and blood pressure.

PURPOSE: Radio frequency ablation (RFA) is evolving as a nephron sparing treatment alternative for select patents with small renal tumors. The impact of ablated tissue on the remaining kidney parenchyma is unknown. To assess this impact we evaluated pretreatment and posttreatment serum creatinine (sCr), and blood pressure of patients treated with RFA with at least 6 months of followup. MATERIALS AND METHODS: From our series of 69 tumors treated with RFA 25 patients with a total of 26 tumors and a minimum 6-month followup were identified. RFA was delivered percutaneously or laparoscopically depending on tumor location and patient preference. Blood pressure measurements and sCr levels were obtained at preoperative and postoperative office visits. Values for preoperative and postoperative systolic blood pressure, diastolic pressure and sCr were each compared. Estimated creatinine clearance was calculated for each patient before and after treatment, and compared. RESULTS: No patient experienced new onset hypertension or worsening of existing hypertension. Likewise no changes in mean sCr and estimated creatinine clearance were observed. CONCLUSIONS: Treatment with RFA does not appear to have an effect on renal function or blood pressure. RFA appears to be a medically safe therapy for patients with small renal tumors.