Ilia S. Zeltser

Effect of freezing parameters (freeze cycle and thaw process) on tissue destruction following renal cryoablation.

BACKGROUND AND PURPOSE Renal cryoablation is a successful nephron-sparing treatment alternative for selected patients with small renal tumors. The purpose of this study was to compare the effects of the number of freeze cycles (one v two) and the thaw process (active v passive) on renal tissue following cryodestruction. MATERIALS AND METHODS Sixteen female mongrel dogs (19.9 +/- 2.1 kg) were randomly divided into four groups and underwent transabdominal laparoscopic access by standard techniques. Tissue freezing was performed using argon gas following interstitial cryoprobe (3 mm) placement into the upper and lower poles of the left kidney. Single active (SA), single passive (SP) double active (DA) or double passive (DP) 15-minute treatment cycle(s) were carried out via the CRYOcare Cryosurgical Unit (Endocare, Irving, CA) on eight kidneys each. An active thaw process with helium gas or a passive thaw process was initiated after each freeze period. The cryoprobe was removed when the temperature reached 0 degrees C. Four weeks following cryosurgery, animals were sacrificed, and the renal tissue was evaluated grossly and histologically. RESULTS Interstitial cryoprobe temperatures decreased from 31.3 degrees C +/- 1.4 degrees C to -142 degrees C +/- 1.0 degrees C following the 15-minute freeze cycle. The temperature reached 0 degrees C significantly faster following active thaw than with the passive process (2.13 +/- 0.24 min/freeze cycle and 15.18 +/- 2.97 min/freeze cycle, respectively; P < 0.0001). Grossly, each lesion consisted of a central area of necrosis surrounded by a rim of white tissue. On microscopic examination, each lesion consisted of a central area of liquefaction necrosis (LN) surrounded by various degrees of fibrosis and granulation tissue admixed with residual parenchyma. The size of the LN was significantly different in tissues subjected to double and single freeze cycles when compared across both thaw processes (active and passive). There was no significant difference in the overall lesion volume following DA, DP, SA, or SP. CONCLUSIONS Renal cryodestruction via laparoscopic access achieves complete tissue ablation without complications. The double freeze cycle produced significantly larger areas of LN than the single freeze regardless of the thaw process. The type of thaw process did not affect the amount of tissue damage. Utilizing a double 15-minute freeze cycle with the faster active thaw process will effectively cryoablate renal tissue as well as significantly reduce overall operative time.

Absence of Viable Renal Carcinoma in Biopsies Performed More Than 1 Year Following Radio Frequency Ablation Confirms Reliability of Axial Imaging

PURPOSE Radio frequency ablation is an emerging nephron sparing treatment option in select patients with small renal tumors. Some have questioned the completeness of cell death and the reliability of axial imaging for radio frequency ablation followup. We present results in patients with no evidence of radiographic active disease who underwent biopsy more than 1 year following ablation. MATERIALS AND METHODS Patients who had no clinical evidence of disease, defined as absent lesion growth and contrast enhancement on computerized tomography, 1 year or more following radio frequency ablation underwent percutaneous renal biopsy to evaluate cell viability in the ablative zone. A total of 19 patients (20 lesions) were included in the study. Histological comparison of pre-ablation and post-ablation specimens was performed using hematoxylin and eosin staining. RESULTS Pre-ablation biopsies confirmed that 17 of 20 tumors were renal cell carcinoma, while the remaining 3 were oncocytoma. Following ablation at a mean followup of 26.9 months (range 13.1 to 58.0) all 20 lesions were stable in size without evidence of contrast enhancement on computerized tomography. At repeat biopsy all histology specimens showed unequivocal tumor eradication with no evidence of cellular viability. Histological changes beyond 1 year demonstrated coagulative necrosis, hyalinization, inflammatory cell infiltration and residual ghost cells. CONCLUSIONS Pathological examination of radiographically negative lesions biopsied more than 1 year following radio frequency ablation confirmed no evidence of disease in all specimens. Therefore, axial imaging can reliably monitor treatment efficacy in the long term. Chronic changes after radio frequency ablation demonstrate coagulative necrosis and nonviable cells. This suggests an evolution of pathological changes that renders early post-ablative biopsy unreliable.

General anesthesia and contrast-enhanced computed tomography to optimize renal percutaneous radiofrequency ablation: Multi-institutional intermediate-term results

INTRODUCTION Percutaneous renal ablation is often performed under conscious sedation and without contrast-enhanced imaging. We evaluated intermediate-term outcomes of patients undergoing percutaneous contrast-enhanced computed tomography (CT)-guided radiofrequency ablation (RFA) under general anesthesia (GA) at two high-volume centers. MATERIALS AND METHODS Prospectively maintained Institutional Regulatory Board-approved databases were searched to identify patients treated with percutaneous RFA using contrast-enhanced CT under GA. A total of 163 masses in 151 patients were treated. Enhancement on imaging or a positive biopsy at 4 to 6 weeks was considered incomplete ablation. Positive findings beyond this interval were defined as local recurrence. RESULTS The median follow-up was 18 months (range, 1.5-70). Median tumor size was 2.3 cm (range, 1-5.4). Of the 130 (80%) masses with definitive pathology, 70% were renal cell cancer. Five masses had evidence of viable tumor at 4 to 6 weeks posttreatment for a complete initial ablation rate of 97%. Three of these five lesions were endophytic. Five masses (3.3%) showed evidence of local recurrence, and metastases developed in two patients (1.3%). Overall 1- and 3-year recurrence-free survival was 97% and 92%, respectively. Masses that were in the central region and were endophytic had the highest risk for recurrence (hazard ratio, 6.3; p = 0.016). CONCLUSIONS Intermediate-term outcomes of percutaneous RFA are excellent. GA-assisted, contrast-enhanced CT-guided percutaneous RFA demonstrates a high initial ablation success rate. However, endophytic and interpolar lesions are at higher risk for recurrence.

Training on a Virtual Reality Laparoscopic Simulator Improves Performance of an Unfamiliar Live Laparoscopic Procedure

PURPOSE Virtual reality simulators provide a safe and efficient means of acquiring laparoscopic skills. We evaluated whether training on a virtual reality laparoscopic cholecystectomy simulator (Lap Mentor) improves the performance of a live, unrelated laparoscopic urological procedure. MATERIALS AND METHODS A total of 32 medical students with no previous laparoscopic experience were oriented to the Lap Mentor, and then performed virtual reality laparoscopic cholecystectomy which was assessed by 2 experienced laparoscopists using the previously validated Objective Structured Assessment of Technical Skills scoring. Subjects were randomized to group 1, in which participants completed 6, 30-minute virtual reality training sessions within 3 weeks, or group 2, in which participants received no training. All participants then performed live laparoscopic nephrectomy in a porcine model and performance was evaluated using Objective Structured Assessment of Technical Skills by 2 experts blinded to training status. RESULTS Mean total pretraining laparoscopic cholecystectomy Objective Structured Assessment of Technical Skills scores were comparable between the groups (16.9 +/- 4.3 for group 1 vs 15.4 +/- 6.2 for group 2, p = 0.4). After training total Objective Structured Assessment of Technical Skills scores for live porcine laparoscopic nephrectomy were significantly higher in group 1 compared to group 2 (21.0 +/- 6.8 vs 15.7 +/- 6.6, respectively, p = 0.03). Likewise, individual subcategory Objective Structured Assessment of Technical Skills scores were higher in group 1 than in group 2, although significant differences were noted only in the categories of instrument handling and knowledge of the procedure. CONCLUSIONS Surgical skills acquired as a result of training on a virtual reality laparoscopic simulator are not procedure specific but improve overall surgical skills, thereby translating into superior performance of an unrelated live laparoscopic urological procedure.

Evaluation of costs and morbidity associated with laparoscopic radiofrequency ablation and laparoscopic partial nephrectomy for treating small renal tumours.

To compare the costs and morbidity of laparoscopic radiofrequency ablation (LRFA) and laparoscopic partial nephrectomy (LPN) for treating small localized renal tumours.

Optical Reflectance Spectroscopy to Differentiate Benign From Malignant Renal Tumors at Surgery

OBJECTIVES Optical reflectance spectrophotometry (ORS) is part of a group of novel techniques that have demonstrated promise for the assessment and differentiation of various solid tumors. In this study, we evaluated the ability of ORS to differentiate malignant from benign kidney tumors at surgery. METHODS From January to April 2007, we completed optical spectroscopy measurements (OSM) at several standardized tumoral and normal parenchymal locations immediately after specimen removal during radical or partial nephrectomy. The depth of tissue penetration with our specific probe was 1 mm. We compared the slopes of the optical reflectance curves between 630- and 900-nm wavelengths and assessed the correlation between benign and malignant tumors. RESULTS There were 8 partial and 13 radical nephrectomies for 6 benign (oncocytomas) and 15 malignant (14 clear cell and 1 papillary) tumors. Overall, benign and malignant OSM slopes were significantly different (P = .005). In the near-infrared region, there was excellent correlation among benign (r = .99) and malignant OSM (r = .97). On the contrary, there was a poor correlation coefficient when we compared benign and malignant tumors (r = .49). CONCLUSIONS Optical reflectance spectrophotometry may be a novel real-time method to distinguish malignant from benign tumors in vivo. However, we performed these pilot study measurements immediately after specimen removal, and therefore expansion to in situ assessments is necessary.

Optical Reflectance Spectroscopy to Differentiate Renal Tumor From Normal Parenchyma

PURPOSE Optical spectroscopy has been evaluated as an innovative technique for the ex vivo study of renal and prostate tumors. In this pilot study we assessed the ability of optical reflectance spectroscopy to reliably differentiate tumor and normal tissue in renal specimens. MATERIALS AND METHODS From January to April 2007 we completed optical reflectance spectroscopy measurements at several standardized tumor and normal parenchymal locations immediately after kidney tumor removal. The slopes of the optical reflectance spectroscopy curves were compared, and the correlation between tumor and normal parenchyma reflectance was assessed. RESULTS Reliable measurements were obtained from 13 radical and 8 partial nephrectomy specimens. Histology was malignant in 15 cases (clear cell in 14 and papillary in 1) and benign in 6 cases of oncocytoma. Overall we found a significant difference between the average optical reflectance spectroscopy slopes of tumor and normal parenchyma (p = 0.03). In individual radical nephrectomy specimens optical reflectance spectroscopy measurements at different locations in the tumor showed an excellent correlation (r = 0.968). Normal parenchymal measurements also correlated well (r = 0.88), although there was poor correlation between tumor and nontumor tissue in the specimen (r = 0.07). In the partial nephrectomy subset we also found a close correlation among measurements made on the normal parenchymal margin of the tumor (r = 0.94) except in 1 case of a positive margin (oncocytoma), in which the measurement from the positive margin site did not correlate with that of the adjacent parenchymal margin (r = 0.48). CONCLUSIONS Optical reflectance spectroscopy can help distinguish tumor from normal renal tissue in specimens immediately removed at surgery. Optical reflectance spectroscopy may allow real-time assessment of positive margins during partial nephrectomy.

Focal Radiofrequency Coagulation–Assisted Laparoscopic Partial Nephrectomy: A Novel Nonischemic Technique

OBJECTIVE HABIB 4X is a laparoscopic focal radiofrequency-coagulation (FRFC) device utilized in liver and kidney resections to facilitate dissection while minimizing blood loss. We evaluated the ergonomics and safety of a laparoscopic FRFC device for a non-ischemic laparoscopic partial nephrectomy (LPN) in a survival porcine model. METHODS Five female pigs (10 renal units) underwent 14 laparoscopic transperitoneal partial nephrectomies using the laparoscopic FRFC device without hilar clamping. In phase 1, either one or multiple segments of the lower, upper, or middle pole were resected following FRFC of the resection plane. Large entries into the collecting system were sutured, while very small rents were left open. Following 2-week survival, a laparoscopic FRFC-assisted heminephrectomy without hilar clamping was performed on the opposite renal unit (phase 2). Both kidneys were then harvested for histologic examination. Retrograde pyelography (RGP) was used to assess the collecting system integrity of the kidneys treated in phase 1. RESULTS All 14 LPNs were performed successfully without hilar clamping or open conversion. On average, the resected segments comprised 12.3% of the kidney in phase 1 and 34.8 % in phase 2, with a mean estimated blood loss of 45 mL and 76.5 mL, respectively. At harvest, no hematomas or perinephric collections were observed. RGP revealed urinary extravasation in two renal units that were not repaired. Histologic examination of the resection margin revealed hemorrhage and inflammation with some hyalinization of the proximal and distal tubules, none extending deeper than 3 mm. CONCLUSION The FRFC-assisted non-ischemic porcine LPN is feasible and safe and can be accomplished with minimal bleeding, even with large resections. The laparoscopic FRFC device holds promise in decreasing the inherent difficulty of LPN by obviating the need for laparoscopic suturing to control small parenchymal vessels, as well as in reducing the deleterious effects of warm renal ischemia. Clinical evaluation of this device is warranted.

Intermediate-term prospective results of radiofrequency-assisted laparoscopic partial nephrectomy: A non-ischaemic coagulative technique

To report the first intermediate‐term oncological outcomes of laparoscopic radiofrequency coagulation followed by laparoscopic partial nephrectomy (RF‐LPN) to treat small renal masses, as LPN is limited by the technical difficulty of efficient tumour resection and parenchymal repair during warm ischaemia of the kidney.

Does topical haemostatic agent have an adverse effect on the function of the prostatic neurovascular bundle

To assess the functional and histological effects of a bovine thrombin topical haemostatic agent used clinically to aid in surgical haemostasis (FloSealTM, Baxter International Inc., Deerfield, IL, USA) on the cavernous nerves in a canine model of survival, as there are concerns that the fibrotic/inflammatory response to this product could affect neural function.