Comparison of temperature change and resulting ablation size induced by a 902-928 MHz and a 2450 MHz microwave ablation system in in-vivo porcine kidneys.

INTRODUCTION: Microwave ablation (MWA) uses heat to ablate undesired tissue. Development of pre-planning algorithms for MWA of small renal masses requires understanding of microwave-tissue interactions at different operating parameters. The objective of this study was to compare the performance of two MWA systems in in-vivo porcine kidneys. METHODS: Five ablations were performed using a 902-928 MHz system (24 W, 5 min) and a 2450 MHz system (180 W, 2 min). Nonlinear regression analysis of temperature changes measured 5 mm from the antenna axis was completed for the initial 10 s of ablation using the power equation ΔT=atb and after the inflection point using an exponential equation. Thermal damage was calculated using the Arrhenius equation. Long and short axis ablation diameters were measured. RESULTS: The average 'a' varied significantly between systems (902-928 MHz: 0.0299 ± 0.027, 2450 MHz: 0.1598 ± 0.158), indicating proportionality to the heat source, but 'b' did not (902-928 MHz: 1.910 ± 0.372, 2450 MHz: 2.039 ± 0.366), signifying tissue type dependence. Past the inflection point, average steady-state temperature increases were similar between systems but reached more quickly with the 2450 MHz system. Complete damage was reached at 5 mm for both systems. The 2450 MHz system produced significantly larger short axis ablations (902-928 MHz: 2.40 ± 0.54 cm, 2450 MHz: 3.32 ± 0.41cm). CONCLUSION: The 2450 MHz system achieved similar steady state temperature increases compared to the 902-928 MHz system, but more quickly due to higher output power. Further investigations using various treatment parameters and precise thermal sensor placement are warranted to refine equation parameters for the development of an ablation model.

Small renal mass biopsy--how, what and when: report from an international consensus panel.

To discuss the use of renal mass biopsy (RMB) for small renal masses (SRMs), formulate technical aspects, outline potential pitfalls and provide recommendations for the practicing clinician. The meeting was conducted as an informal consensus process and no scoring system was used to measure the levels of agreement on the different topics. A moderated general discussion was used as the basis for consensus and arising issues were resolved at this point. A consensus was established and lack of agreement to topics or specific items was noted at this point. Recommended biopsy technique: at least two cores, sampling different tumour regions with ultrasonography being the preferred method of image guidance. Pathological interpretation: 'non-diagnostic samples' should refer to insufficient material, inconclusive and normal renal parenchyma. For non-diagnostic samples, a repeat biopsy is recommended. Fine-needle aspiration may provide additional information but cannot substitute for core biopsy. Indications for RMB: biopsy is recommended in most cases except in patients with imaging or clinical characteristics indicative of pathology (syndromes, imaging characteristics) and cases whereby conservative management is not contemplated. RMB is recommended for active surveillance but not for watchful-waiting candidates. We report the results of an international consensus meeting on the use of RMB for SRMs, defining the technique, pathological interpretation and indications.

Emerging needle ablation technology in urology.

PURPOSE OF REVIEW: Thermal ablation of urologic tumors in the form of freezing (cryoablation) and heating (radiofrequency ablation) have been utilized successfully to treat and ablate soft tissue tumors for over 15 years. Multiple studies have demonstrated efficacy nearing that of extirpative surgery for certain urologic conditions. There are technical limitations to their speed and safety profile because of the physical limits of thermal diffusion. RECENT FINDINGS: Recently, there has been a desire to investigate other forms of energy in an effort to circumvent the limitations of cryoblation and radiofrequency ablation. This review will focus on three relatively new energy applications as they pertain to tissue ablation: microwave, irreversible electroporation, and water vapor. High-intensity-focused ultrasound nor interstitial lasers are discussed, as there have been no recently published updates. SUMMARY: Needle and probe-based ablative treatments will continue to play an important role. As three-dimensional imaging workstations move from the advanced radiologic interventional suite to the operating room, surgeons will likely still play a pivotal role in the +-application of these probe ablative devices. It is essential that the surgeon understands the fundamentals of these devices in order to optimize their application.

Clinical applications of robotic surgery platforms: a comprehensive review.

Robotic surgery has expanded globally across various medical specialties since its inception more than 20 years ago. Accompanying this expansion were significant technological improvements, providing tremendous benefits to patients and allowing the surgeon to perform with more precision and accuracy. This review lists some of the different types of platforms available for use in various clinical applications. We performed a literature review of PubMed and Web of Science databases in May 2023, searching for all available articles describing surgical robotic platforms from January 2000 (the year of the first approved surgical robot, da Vinci® System, by Intuitive Surgical) until May 1st, 2023. All retrieved robotic platforms were then divided according to their clinical application into four distinct groups: soft tissue robotic platforms, orthopedic robotic platforms, neurosurgery and spine platforms, and endoluminal robotic platforms. Robotic surgical technology has undergone a rapid expansion over the last few years. Currently, multiple robotic platforms with specialty-specific applications are entering the market. Many of the fields of surgery are now embracing robotic surgical technology. We review some of the most important systems in clinical practice at this time.

Preoperative patient counseling for diagnostic renal biopsy and complications with renal radiofrequency ablation.

PURPOSE: To identify preoperative factors associated with surgical complications and successful diagnostic renal biopsy in both laparoscopic and percutaneous radiofrequency ablation (RFA) of renal masses in order to help aid in preoperative patient counseling for renal RFA. METHODS: We reviewed our Institutional Review Board approved database from November 2001 to January 2011, containing 335 tumors treated with either laparoscopic (LRFA) or percutaneous RFA (CTRFA). Preoperative patient demographics, tumor characteristics, and intraoperative surgical data were collected along with biopsy results and clinicopathologic outcomes. RESULTS: RFA was performed on 335 renal tumors (124 LRFA, 211 CTRFA). Non-diagnostic biopsy occurred in 18 (5.5%) tumors. Of the 317 procedures performed, 121 complications occurred in 103 (30.7%) procedures. Multivariate analysis only showed CTRFA (vs LRFA) to increase the likelihood of non-diagnostic biopsy (OR 5.1, 95% CI 1.2-22, p = 0.032). Increased tumor size (p = 0.007) and synchronous ablations (p = 0.019) increased the risk for major complications, while decreased surgeon experience (p = 0.003) and tumors close to the collecting system (p = 0.005) increased the risk of any complication. CONCLUSIONS: Preoperative recommendations can be made to patients in the future. We suggest counseling patients that when undergoing RFA, percutaneous approach increases the risk of non-diagnostic biopsy, increased tumor size increases the risk of major complications, having more than 1 tumor ablated increases the risk of a major complication, and tumors close to the collecting system may increase the risk of complications.

Comparison of safety, renal function outcomes and efficacy of laparoscopic and percutaneous radio frequency ablation of renal masses.

PURPOSE: With the increased incidence of low stage renal cancers, thermal ablation technology has emerged as a viable treatment option. Current AUA (American Urological Association) guidelines include thermal ablation as a treatment modality for select individuals. We compared the laparoscopic and percutaneous approach for the radio frequency ablation of renal tumors under the guidance of urological surgeons. MATERIALS AND METHODS: We reviewed our radio frequency ablation database of patients with renal masses undergoing laparoscopic or computerized tomography guided percutaneous radio frequency ablation with simultaneous peripheral fiberoptic thermometry from November 2001 to January 2011 at a single tertiary care center. Data were collected on patient demographics, and surgical and clinicopathological outcomes stratified by approach. RESULTS: A total of 298 patients with 316 renal tumors underwent laparoscopic (122 tumors) or computerized tomography guided (194 tumors) radio frequency ablation. There were no statistically significant differences between the laparoscopic and computerized tomography guided radio frequency ablation groups with respect to patient demographics, complication rates and renal functional outcomes (p>0.05). The 3-year Kaplan-Meier estimation of radiographic recurrence-free probability was 95% for computerized tomography guided radio frequency ablation and 94% for laparoscopic radio frequency ablation (p=0.84). Subanalysis of the 212 (67%) renal cell carcinoma tumors showed a 3-year Kaplan-Meier estimation of oncologic recurrence-free probability (post-ablation biopsy proven viable tumor) of 94% for computerized tomography guided radio frequency ablation and 100% for laparoscopic radio frequency ablation (p=0.16). Median followup was 21 months for laparoscopic radio frequency ablation) and 19 months for computerized tomography guided radio frequency ablation. CONCLUSIONS: Laparoscopic and computerized tomography guided radio frequency ablation appear safe and effective with statistically equivalent rates of complications and recurrence.

Diagnosis, evaluation and follow-up of asymptomatic microhematuria (AMH) in adults: AUA guideline.

PURPOSE: The purpose of this guideline is to provide a clinical framework for the diagnosis, evaluation and follow-up of asymptomatic microhematuria. MATERIALS AND METHODS: A systematic literature review using the MEDLINE® database was conducted to identify peer reviewed publications relevant to the definition, diagnosis, evaluation and follow-up for AMH. The review yielded 191 evidence-based articles, and these publications were used to create the majority of the guideline statements. There was insufficient evidence-based data for certain concepts; therefore, clinical principles and consensus expert opinions were used for portions of the guideline statements. RESULTS: Guideline statements are provided for diagnosis, evaluation and follow-up. The panel identified multiphasic computed tomography as the preferred imaging technique and developed guideline statements for persistent or recurrent AMH as well as follow-up. CONCLUSIONS: AMH is only diagnosed by microscopy; a dipstick reading suggestive of hematuria should not lead to imaging or further investigation without confirmation of three or greater red blood cells per high power field. The evaluation and follow-up algorithm and guidelines provide a systematic approach to the patient with AMH. All patients 35 years or older should undergo cystoscopy, and upper urinary tract imaging is indicated in all adults with AMH in the absence of known benign causation. The imaging modalities and physical evaluation techniques are evolving, and these guidelines will need to be updated as the effectiveness of these become available. Please visit the AUA website at http://www.auanet.org/content/media/asymptomatic_microhematuria_guideline.pdf to view this guideline in its entirety.

Factors that impact the outcome of minimally invasive pyeloplasty: results of the Multi-institutional Laparoscopic and Robotic Pyeloplasty Collaborative Group.

PURPOSE: We compared laparoscopic and robotic pyeloplasty to identify factors associated with procedural efficacy. MATERIALS AND METHODS: We conducted a retrospective multicenter trial incorporating 865 cases from 15 centers. We collected perioperative data including anatomical and procedural factors. Failure was defined subjectively as pain that was unchanged or worse per medical records after surgery. Radiographic failure was defined as unchanged or worsening drainage on renal scans or worsening hydronephrosis on computerized tomography. Bivariate analyses were performed on all outcomes and multivariate analysis was used to assess factors associated with decreased freedom from secondary procedures. RESULTS: Of the cases 759 (274 laparoscopic pyeloplasties with a mean followup of 15 months and 465 robotic pyeloplasties with a mean followup of 11 months, p <0.001) had sufficient data. Laparoscopic pyeloplasty, previous endopyelotomy and intraoperative crossing vessels were associated with decreased freedom from secondary procedures on bivariate analysis, with a 2-year freedom from secondary procedures of 87% for laparoscopic pyeloplasty vs 95% for robotic pyeloplasty, 81% vs 93% for patients with vs without previous endopyelotomy and 88% vs 95% for patients with vs without intraoperative crossing vessels, respectively. However, on multivariate analysis only previous endopyelotomy (HR 4.35) and intraoperative crossing vessels (HR 2.73) significantly impacted freedom from secondary procedures. CONCLUSIONS: Laparoscopic and robotic pyeloplasty are highly effective in treating ureteropelvic junction obstruction. There was no difference in their abilities to render the patient free from secondary procedures on multivariate analysis. Previous endopyelotomy and intraoperative crossing vessels reduced freedom from secondary procedures.

Radiofrequency ablation (RFA) therapy for renal angiomyolipoma (AML): an alternative to angio-embolization and nephron-sparing surgery.

OBJECTIVES: To show that radiofrequency ablation (RFA) is safe and effective treatment for renal angiomyolipoma (AML). Current treatments to reduce the risk of haemorrhage include tumour extirpation, angio-embolization, or ablative therapy. PATIENTS AND METHODS: Review of our prospective database revealed 15 patients with intraoperative biopsy confirmed renal AML undergoing RFA from February 2002 to March 2010. Patients underwent either laparoscopic or computed tomography (CT)-guided percutaneous RFA using either the Cool-tip™ (Covidien, Inc. Boulder, CO, USA) or RITA™ (Angiodynamics(®), Latham, NY, USA) RFA probe. CT at 1 month, 6 months, 1 year, and annually thereafter. RESULTS: In all, two male and 13 female patients with seven left-sided and eight right-sided tumours with a mean (range) size of 2.6 (1.0-3.7) cm underwent laparoscopic (five) or CT-guided (10) RFA. No intraoperative complications occurred. Minor complications included transient haematuria and intercostals nerve transection. Surgical complications included pneumonia and myocardial infarction. There was no radiographic evidence of persistent AML (CT enhancement) at a mean follow-up of 21 months. CONCLUSIONS: The haemostatic effect of RFA allows renal lesions suspicious for AML to be treated without bleeding complications. Avoids surgical risk of extirpation or embolization. RFA for renal AML is safe and effective.

Salvage robot-assisted partial nephrectomy for the management of renal cell carcinoma following failed stereotactic radiotherapy.

Nephron-sparing surgery is currently the standard of care for the management of small renal masses. While both neoadjuvant and adjuvant conventional external beam radiotherapy have failed to demonstrate an oncologic benefit for the treatment of renal cell carcinoma, more recent work aims to explore the utility of stereotactic radiotherapy. We present the case of a 70-year-old woman who failed primary treatment of a small renal mass with the CyberKnife radiotherapy system and describe her successful salvage treatment with robot-assisted partial nephrectomy. This case demonstrates the safety of robotic surgery for the management of renal tumors following failed stereotactic radiotherapy.

Laparoscopic and image-guided radiofrequency ablation of renal tumors: patient selection and outcomes.

Multiple modalities exist for the management of small renal tumors, including active surveillance, extirpation (radical nephrectomy and partial nephrectomy), and ablative therapies. Radiofrequency ablation (RFA) is an alternative to extirpative surgery for renal tumors. This article presents the current literature on RFA for renal tumors. We reviewed 28 RFA series in the English literature from 2003 to 2010 to assess patient selection, biopsy, renal outcomes, and oncologic outcomes.

Renal functional outcomes for tumours in a solitary kidney managed by ablative or extirpative techniques.

OBJECTIVE: To present the renal functional outcomes for patients treated with open partial nephrectomy (OPN) or radiofrequency ablation (RFA) for tumours in a solitary kidney, as renal masses in a solitary kidney present a challenging treatment dilemma. PATIENTS AND METHODS: A retrospective review of institutional databases identified 89 patients with 98 renal tumours in a solitary kidney managed by RFA or OPN under cold ischaemia between January 1997 and September 2007. The choice of therapy was based on patient and surgeon preference, tumour characteristics and comorbidities. Renal function was calculated using the modified Modification of Diet in Renal Disease equation. RESULTS: Outcomes from 47 patients treated by RFA and 42 by OPN were analysed at a median follow-up of 18.1 and 30.0 months, respectively (P = 0.02). The median age (65.9 vs 59.6 years, P = 0.03) and American Society of Anesthesiology score (3.0 vs 2.0, P = 0.01) were both higher in patients treated with RFA. The median tumour size was greater for tumours managed by OPN (3.9 vs 2.8 cm, P = 0.001), while the median preoperative glomerular filtration rate (GFR) was lower in the RFA group (46.5 vs 55.9 mL/min/1.73 m(2) for OPN, P = 0.04). Compared to RFA, patients treated with OPN had a greater decline in GFR at all times evaluated, including soon after the procedure (15.8% vs 7.1%), 12 months after surgery (24.5% vs 10.4%) and at the last follow-up (28.6% vs 11.4%, all P < 0.001). For patients with a pretreatment GFR of > 60 or > 30 mL/min/1.73 m(2), there was a new onset of decline in GFR of <60 and <30 mL/min/1.73 m(2) in none and 7% of patients after RFA, and in 35% and 17% after OPN. CONCLUSION: Ablative techniques, which obviate ischaemic insults, might be a particularly attractive option for managing tumours in solitary renal units at risk of declining function. Renal functional outcomes compare favourably to extirpative surgery using cold ischaemia.

Results of radiofrequency kidney tumor ablation: renal function preservation and oncologic efficacy.

OBJECTIVES: Radiofrequency ablation (RFA) is increasingly finding a place in the treatment of small renal masses (SRM). RFA may be able to provide better renal preservation, while achieving appropriate cancer control. This investigation takes a critical look at pertinent aspects of RFA principles and reviews oncological and renal function outcomes. METHODS: A review of the most current English literature using a PubMed search was done. Oncological and renal function outcomes were reviewed from selected articles published between 2003 and 2009. Oncological outcome was determined by "single treatment" success rate at first follow-up and "After single treatment" success rate after first follow-up. Renal function outcome was determined by either change in creatinine, creatinine clearance, or GFR after RFA. RESULTS: The mean tumor size was 2.5 cm for 16/17 studies. Average mean and median follow-up was 23.3 months in 13/17 studies and 19.8 months for 4/17 studies. "Single Treatment" success rates of 90-100% (average = 97.2%) were noted in 13 studies. Average increase in serum creatinine was +0.14 mg/dL in four studies. Serum creatinine and creatinine clearance change in one solitary kidney study was +11 mmol/L and -8 mL/min., respectively. CONCLUSIONS: RFA is fast emerging as a safe and efficacious treatment for small renal masses. Compared to extirpative treatment options, RFA seems to provide the lowest rate of renal impairment, while providing acceptable rates of tumor ablation. As long-term results emerge, this may become one of the treatment modalities for renal tumors in patients with solitary kidneys and renal impairment.

A review of methods for hemostasis and renorrhaphy after laparoscopic and robot-assisted laparoscopic partial nephrectomy.

The techniques for management of small renal masses (SRMs) have evolved over the past several years. Radical nephrectomy can lead to an increased risk of chronic kidney disease, and the emphasis is now shifting to nephron-conserving techniques. Partial nephrectomy is now considered a standard of care for the management of SRMs, and laparoscopic techniques are becoming popular because they are minimally invasive. The kidneys are extremely vascular organs, and renal hemorrhage is a major cause of morbidity after laparoscopic partial nephrectomies. Control of bleeding and management of calyceal injuries can be difficult and make the procedure technically challenging. This review looks at the various modalities that are available to reduce bleeding and reviews some advances in the area of hemostatic maneuvers during laparoscopic partial nephrectomies.

Management of Residual or Recurrent Disease Following Thermal Ablation of Renal Cortical Tumors.

Management of residual or recurrent disease following thermal ablation of renal cortical tumors includes surveillance, repeat ablation, or surgical extirpation. We present a multicenter experience with regard to the management of this clinical scenario. Prospectively maintained databases were reviewed to identify 1265 patients who underwent cryoablation (CA) or radiofrequency ablation (RFA) for enhancing renal masses. Disease persistence or recurrence was classified into one of the three categories: (i) residual disease in ablation zone; (ii) recurrence in the ipsilateral renal unit; and (iii) metastatic/extra-renal disease. Seventy seven patients (6.1%) had radiographic evidence of disease persistence or recurrence at a median interval of 13.7 months (range, 1-65 months) post-ablation. Distribution of disease included 47 patients with residual disease in ablation zone, 29 with ipsilateral renal unit recurrences (all in ablation zone), and one with metastatic disease. Fourteen patients (18%) elected for surveillance, and the remaining underwent salvage ablation (n = 50), partial nephrectomy (n = 5), or radical nephrectomy (n = 8). Salvage ablation was successful in 38/50 (76%) patients, with 12 failures managed by observation (3), tertiary ablation (6), and radical nephrectomy (3). At a median follow-up of 28 months, the actuarial cancer-specific survival and overall survival in this select cohort of patients was 94.8 and 89.6%, respectively.

Training, credentialing, proctoring and medicolegal risks of robotic urological surgery: recommendations of the society of urologic robotic surgeons.

PURPOSE: With the exponential growth of robotic urological surgery, particularly with robot assisted radical prostatectomy, guidelines for safe initiation of this technology are a necessity. Currently no standardized credentialing system exists to our knowledge to evaluate surgeon competency and safety with robotic urological surgery performance. Although proctoring is a modality by which such competency can be evaluated, other training tools and guidelines are needed to ensure that the requisite knowledge and technical skills to perform this procedure have been acquired. We evaluated the current status of proctoring and credentialing in other surgical specialties to discuss and recommend its application and implementation specifically for robot assisted radical prostatectomy. MATERIALS AND METHODS: We reviewed the literature on safety and medicolegal implications of proctoring and the safe introduction of surgical procedures to develop recommendations for robot assisted radical prostatectomy proctoring and credentialing. RESULTS: Proctoring is an essential mechanism for robot assisted radical prostatectomy institutional credentialing and should be a prerequisite for granting unrestricted privileges on the robot. This should be differentiated from preceptoring, wherein the expert is directly involved in hands-on training. Advanced technology has opened new avenues for long-distance observation through teleproctoring. Although the medicolegal implications of an active surgical intervention by a proctor are not clearly defined, the role as an observer should grant immunity from malpractice liability. CONCLUSIONS: The implementation of guidelines and proctoring recommendations is necessary to protect surgeons, proctors, institutions and, above all, the patients who are associated with the institutional introduction of a robot assisted radical prostatectomy program. With no current guidelines we anticipate this article will serve as a catalyst of interorganizational discussion to initiate regulatory oversight of surgeon certification and proctorship.

Role of robotics for ureteral pelvic junction obstruction and ureteral pathology.

PURPOSE OF REVIEW: To review the role of robotics for the management of ureteral pathology, in particular, ureteropelvic junction obstruction and ureteric stricture disease. RECENT FINDINGS: Minimally invasive surgery has an expanding role in the management of ureteric pathology. Minimally invasive surgery modalities are associated with decreased morbidity when compared with open reconstructive techniques. Robotics solves many of the technical complexities that may be prohibitive with standard laparoscopic surgery such as intracorporeal suturing. Several studies have demonstrated equivalent or superior short-term outcomes in comparison to traditional open techniques. Encouraging long-term data are now emerging for robotic pyeloplasty. SUMMARY: In 2008, robotic surgery appears to be a feasible and effective alternative to laparoscopy for reconstructive procedures of the ureter and may represent a potential solution to some of the drawbacks associated with ureteric reconstruction.

Renal thermal ablative therapy.

Energy targeting is greatly enhanced through imaging modalities, which greatly assist needle placement or energy delivery to the optimal location for maximal effectiveness. When vital structures obscure access to the renal lesion, laparoscopic mobilization of these structures with direct visualization of the tumor can increase the likelihood of ablation success and minimize complication risk. Ablative therapies are attractive because of their minimal impact on patient quality of life in addition to their morbidity and cost. Although they show promise of efficacy, they must be evaluated with long-term follow-up before they are considered the standard of oncologic care. Renal masses can be treated with a laparoscopic or percutaneous approach depending on tumor location, size, and the available technology and experience of the center.

Preparation of artificial kidney stones of reproducible size, shape, and mass by precision injection molding.

PURPOSE: To prepare artificial kidney stones of defined shape, size, mass, and material composition via precision injection molding of Ultracal 30 cement slurries into an inexpensive biodegradable mold. MATERIALS AND METHODS: A calcium alginate and silica-based mold was used to prepare casts of varying shapes in a reproducible manner. Ultracal 30 cement slurries mixed 1:1 with water were injected into these casts and allowed to harden. The artificial stones were recovered and their physical properties determined. Ex-vivo and in-vivo responses to holmium laser lithotripsy were examined. RESULTS: Spheres, half spheres, cylinders, cubes, tapered conical structures, and flat angulated structures were prepared with high precision without post-molding manipulations. Large spheres of average mass 0.661 g (+/- 0.037), small spheres of average mass 0.046 g (+/- 0.0026), and hexagons of average mass 0.752 g (+/- 0.0180) were found to have densities (1610-1687 kg/m(3)) within the expected range for Ultracal 30 cement stones. Ex-vivo holmium laser lithotripsy of small spheres in saline showed uniformly reproducible efficiencies of comminution. Implantation of a tapered conical stone into the ureter of a porcine model demonstrated stone comminution in vivo consistent with that seen in the ex-vivo models. CONCLUSIONS: We present an environmentally safe, technically simple procedure for the formation of artificial kidney stones of predetermined size and shape. The technique does not require the use of hazardous solvents or postprocedural processing of the stones. These stones are intended for use in standardized experiments of lithotripsy efficiency in which the shape of the stone as well as the mass can be predetermined and precisely controlled.

First prize: direct real-time temperature monitoring for laparoscopic and CT-guided radiofrequency ablation of renal tumors between 3 and 5 cm.

PURPOSE: To evaluate our experience with radiofrequency ablation (RFA) of renal tumors in the range of 3 to 5 cm. PATIENTS AND METHODS: A series of 96 patients underwent 104 tumor laparoscopic or percutaneous CT-guided RFAs. We identified 37 tumors between 3 and 5 cm at the time of the ablation. Non-conducting temperature probes, independent of the radiofrequency (RF) electrode, were placed at the peripheral and deep margins of the tumor in order to achieve real-time temperature monitoring of the ablation zone. All ablations were continued until the peripheral and deep temperature probes reached 60 degrees C. RESULTS: All 37 patients (100%) achieved complete necrosis at the initial session. There were two radiographic failures at 9 months and 30 months that required a second treatment (95% radiographic success rate). Tissue samples taken at the time of the re-treatment (one partial nephrectomy with numerous biopsies of the deep and peripheral margins and one repeat ablation with eight core biopsies) showed no evidence of viable tumor with hematoxylin and eosin or nicotinamide adenine dinucleotide viability stains. The average length of follow-up was 11.3 months (range 1-44 months). No patient with localized disease at the time of the RFA developed local extension or metastatic disease in follow-up. CONCLUSIONS: The majority of renal tumors between 3 and 5 cm can be ablated with complete necrosis in a single session. Placement of independent temperature probes at the peripheral and deep margins of the tumor provides real-time monitoring that assists in the deployments of the RF electrode and determining the appropriate duration of the ablation cycles. Attention to real-time thermometry decreases the need for repeat sessions to achieve complete necrosis for larger tumors. Likewise, real-time thermometry decreases the incidence of overtreatment of normal parenchyma and prevents collateral damage to adjacent vital structures (ureter, pancreas, bowel, spleen, nerves) outside the desired zone of ablation.