Incomplete renal tumor destruction using radio frequency interstitial ablation

PURPOSE: We evaluate the efficacy of temperature based radio frequency ablation as a potential treatment modality for small (less than 3.5 cm.) renal tumors. MATERIALS AND METHODS: We treated 15 patients with a total of 20 tumors with radio frequency ablation through an open surgical approach immediately before partial nephrectomy. All tumors were biopsied before radio frequency ablation treatment. Tumors were heated to 90 to 110C for 6 to 16 minutes (mean 9.1). Tumor ablation was monitored by direct vision and ultrasound. Partial nephrectomy was performed in standard fashion. All specimens were stained with hematoxylin and eosin, and 5 specimens were stained for nicotinamide adenine dinucleotide (NADH) diaphorase activity. RESULTS: Tumors ranged from 1.5 to 3.5 cm. (mean 2.4) in greatest dimension. All 20 specimens had evidence of morphologically unchanged tumor and normal renal parenchyma on standard hematoxylin and eosin staining. Of the 5 specimens 4 stained positively for NADH in areas confirmed to be tumor in hematoxylin and eosin stained neighboring sections. There was 1 intraoperative renal pelvic thermal injury requiring pyeloplasty and 2 postoperative caliceal leaks requiring stent placement. CONCLUSIONS: In our series radio frequency therapy did not result in total tumor destruction when specimens were examined with hematoxylin and eosin or NADH staining. We believe that radio frequency interstitial tumor ablation of renal cell carcinoma without subsequent tissue resection should continue to be an investigational treatment modality for those who would otherwise undergo partial or radical nephrectomy.     

Phase II trial of radio frequency ablation of renal cancer: evaluation of the kill zone

PURPOSE: We report on the pathological evaluation of renal tumors after intraoperative radio frequency ablation performed immediately before surgical nephrectomy. MATERIALS AND METHODS: Ten patients with renal tumors were enrolled in a prospective, Institutional Review Board approved phase II trial of radio frequency ablation. Following surgical exposure of the kidney a single 12-minute radio frequency ablation of the tumor was performed using the Radionics Cool-tip RF Radio Frequency Ablation System (Radionics, Burlington, Massachusetts). The tumor was then excised via radical or partial nephrectomy. Gross and histological evaluations of the tumor were performed, including evaluation with nicotinamide adenine dinucleotide vital staining. RESULTS: All 10 tumors were confirmed histologically to be renal cell carcinoma. Mean tumor size was 3.2 cm. (range 1.4 to 8.0). Of the 10 tumors 8 were completely ablated with a mean treatment margin of 6.75 mm. (range 2 to 13). Of the 2 tumors that were incompletely treated 1 never attained a temperature sufficient for tissue destruction and the other measured 8 cm., far exceeding the expected ablation volume of treatment protocol. CONCLUSIONS: This study represents the initial report of the histological outcome of saline cooled radio frequency ablation of renal tumors. Our data indicate that it can completely destroy renal cancers while transmitting minimal collateral damage to surrounding renal parenchyma. Further investigation is required to determine long-term oncological outcome.     

Percutaneous radio frequency ablation of small renal tumors: initial results.

PURPOSE: Thermal tissue ablation with radio frequency energy is an experimental treatment of renal tumor. We report early results of an ongoing trial of percutaneous radio frequency ablation for small renal tumors. MATERIALS AND METHODS: Patients with percutaneously accessible renal tumors were evaluated for radio frequency ablation. Tumors were solid on computerized tomography (CT), 3 cm. or less in diameter and enlarging during at least 1 year. Ablation was performed at the Interventional Radiology suite under ultrasound and/or CT guidance. A 50 W., 460 kHz. electrosurgical generator delivered radio frequency energy via a percutaneously placed 15 gauge coaxial probe. At least 2, 10 to 12-minute ablation cycles were applied to each lesion. Patients were observed overnight before discharge from hospital and reevaluated 2 months later. RESULTS: A total of 24 ablations were performed in 21 patients with renal tumor, including solid von Hippel-Lindau clear cell tumor in 19 and hereditary papillary renal cancer 2. Most (22 of 24) procedures were performed with patients under conscious sedation. At 2 months postoperatively mean tumor diameter plus or minus standard deviation decreased from 2.4 +/- 0.4 to 2.0 +/- 0.5 cm. (p = 0.001), and a majority of tumors (19 of 24, 79%) ceased to be enhanced on contrast CT. Mean serum creatinine plus or minus standard deviation was unchanged during this interval (1.0 +/- 0.2 mg./dl.). No major and 4 minor complications were encountered, including 2 episodes each of transient psoas pain and flank skin numbness. CONCLUSIONS: Percutaneous radio frequency ablation of small renal tumor is well tolerated and minimally invasive. It will remain experimental until procedural and imaging parameters that correlate with tumor destruction are validated.     

Long-term followup of patients with renal cell carcinoma treated with radio frequency ablation with curative intent

PURPOSE: We defined the role of radio frequency ablation in the treatment of renal cell carcinoma. MATERIALS AND METHODS: A total of 16 patients with biopsy proven renal cell carcinoma were treated with radio frequency ablation in an outpatient setting and followed for a minimum of 4 years. RESULTS: Of the 16 patients 5 died before 4 years of followup of unrelated causes. All except 1 tumor was successfully treated. All patients with exophytic tumors were successfully treated. CONCLUSIONS: Radio frequency ablation of exophytic renal cell carcinomas less than 5 cm in diameter is effective in eradicating the tumor and comparable to surgical extirpation at 4 years.     

Laparoscopic application of radio frequency energy enables in situ renal tumor ablation and partial nephrectomy

PURPOSE: To our knowledge we present the initial series of renal mass in situ laparoscopic radio frequency ablation. We also discuss the indications for and results of subsequent laparoscopic partial nephrectomy. MATERIALS AND METHODS: Laparoscopic radio frequency ablation was performed in 13 patients with a mean age of 59 years (range 18 to 81) and a total of 17 small enhancing renal masses. In 5 patients the tumor was subsequently excised completely, whereas in 7 it was left in situ after treatment. In 1 patient with 5 lesions only the largest lesion was excised, while the other 4 were left in situ. RESULTS: Mean tumor size was 1.96 cm. (range 0.9 to 3.6). Tumors that remained in situ tended to be endophytic and located in the mid pole. Pathological analysis revealed renal cell carcinoma in 10 patients, angiomyolipoma in 2 and oncocytoma in the patient with multiple lesions. None of the 8 patients with renal cell carcinoma who had at least 6 weeks of followup (mean 9.8 months, range 1.5 to 22) had any evidence of persistent tumor enhancement on surveillance computerized tomography or any other evidence of disease progression. There was 1 focal positive margin in a patient who underwent radio frequency ablation and excision of renal cell carcinoma but the patient remained disease-free 1 year after treatment. CONCLUSIONS: Early experience with laparoscopic radio frequency ablation in situ or combined with partial nephrectomy shows that it appears to be a safe method of managing small enhancing renal masses. Radio frequency assisted laparoscopic partial nephrectomy is reserved for easily accessible exophytic tumors, while strict surveillance is required for lesions remaining in situ after ablation. Additional followup is required to assess long-term effectiveness.     

The uncertainty of radio frequency treatment of renal cell carcinoma: findings at immediate and delayed nephrectomy

PURPOSE: Radio frequency thermal therapy for the ablation of renal cell carcinoma has been reported. Outcomes are usually measured by imaging alone. We have performed ex vivo and in vivo experiments using radio frequency in porcine models in our laboratory. We now report our early experience in the treatment of renal cell carcinoma in patients who underwent post-radio frequency radical or partial nephrectomy. MATERIALS AND METHODS: We treated 10 patients diagnosed with small renal masses with radio frequency. All masses were biopsied before treatment. In 4 patients 5 renal cell carcinomas were treated with radio frequency after surgical exposure of the tumor followed immediately by partial or radical nephrectomy (acute group). Six other patients were treated percutaneously with ultrasound or computerized tomography guided radio frequency under local anesthesia and intravenous sedation 7 days before partial or radical nephrectomy (delayed group). A median of 2 radio frequency cycles was applied. Mean total heating time was 17 minutes 15 seconds. Specimens were analyzed grossly and histologically. Triphasic contrast-enhanced computerized tomography and/or magnetic resonance imaging was performed before and 7 days after radio frequency treatment in the delayed group. RESULTS: Mean radiological largest diameter of all 11 masses was 2.4 cm. and mean gross diameter was 2.2 cm. Pathological examination demonstrated residual viable tumor in approximately 5% of the volume in 4 of the 5 tumors in the acute group and in 3 of the 6 masses of the delayed group. In 1 delayed case the viable tumor appeared to be in contact with the renal vein. No significant complications were observed in 9 of the 10 patients. In 1 delayed case, a subcapsular hepatic hematoma, biliary fistula and pneumonia developed and resolved. CONCLUSIONS: Based on our experience, we continue to consider percutaneous radio frequency for the treatment of small renal cell carcinomas as a potentially curative therapy. However, complete tumor cell death appears to be difficult to achieve with our current treatment protocol. More phase II testing is indicated to ensure that this technique is an effective and reproducible treatment alternative.     

Radio frequency ablation of renal cell carcinoma: preliminary clinical experience

PURPOSE: We assess the feasibility, safety and efficacy of radio frequency ablation of small peripheral renal cell carcinomas. MATERIALS AND METHODS: Five patients with a histologically proven renal cell carcinoma 30 to 40 mm. in diameter were treated with radio frequency ablation. A triple needle electrode was percutaneously advanced into each tumor under sonographic (4 cases) or computerized tomography (CT) (1) guidance. The radio frequency generator was activated for 15 minutes in each location where the electrode had been placed. Patients were then followed with CT and blood tests every 2 months for 6 months and every 3 months thereafter. RESULTS: Four tumors required 1 radio frequency delivery and 1 required 2 applications during the same session. No complications were encountered except for a subcapsular hematoma in 1 patient, which resolved spontaneously. Two patients experienced transient hematuria. Of the patients 4 were discharged from the hospital after 2 days and 1 after 1 day. After 6 to 18 months (median 9) all patients were tumor-free on CT without suppress additional treatment. CONCLUSIONS: In this small preliminary study radio frequency ablation of small peripheral renal cell carcinomas appears to be a feasible, safe and promising technique.     

Defining the complications of cryoablation and radio frequency ablation of small renal tumors: a multi-institutional review

PURPOSE: Ablative treatments (cryoablation or radio frequency ablation) for renal cell carcinoma aim to decrease morbidity by treating renal tumors in situ, eliminating the need for extirpation. These technologies have potential for complications previously unassociated with renal tumor treatment. We identified complications associated with percutaneous and laparoscopic ablative treatment of renal tumors. MATERIALS AND METHODS: Groups at medical centers with reported experience with ablation of renal tumors were invited to participate in this study. Each group submitted retrospective data regarding overall ablative treatment experience and associated complications. For each incident the nature of the complication, its associated morbidity, the necessity and nature of any subsequent interventions, and the final patient outcome were evaluated. Complications were divided into minor and major categories. Data were collected from groups at 4 institutions with a combined experience of 271 cases. Of these cases 139 were cryoablation and 133 were radio frequency ablation. There were 181 procedures performed percutaneously and 90 performed laparoscopically. RESULTS: A total of 30 complications occurred (11.1%) with 5 major (1.8%) and 25 minor (9.2%) complications, and 1 death (0.4%). Overall 26 of the 30 complications (86.7%) were directly attributable to the ablation procedure. The most common complication was pain or paraesthesia at the probe insertion site. CONCLUSIONS: Ablation technologies appear to have a low complication profile when used to treat small renal tumors. The majority of complications are minor and require observation only. Further study and followup are necessary to determine long-term oncological efficacy.     

Predicting postoperative renal insufficiency in patients undergoing nephrectomy for renal malignancy: assessment by renal scintigraphy using 99mtechnetium-mercaptoacetyltriglycine

PURPOSE: We performed Tc-mercaptoacetyltriglycine (MAG3) renal scintigraphy in patients with renal malignancy to evaluate the function of each renal unit before and after nephrectomy to see if postoperative functional deterioration could be predicted based on scintigraphy results and creatinine clearance. MATERIALS AND METHODS: A total of 22 men and 13 women with renal malignancy, including 32 with renal cell carcinoma and 3 with urothelial cancer, were prospectively enrolled in this study. Average patient age was 64.3 years (median 65, range 43 to 88). All patients underwent MAG3 renal scintigraphy before and after unilateral nephrectomy. At the same time serum creatinine and endogenous creatinine clearance were determined. RESULTS: Mean serum creatinine was 0.93 mg/dl before and 1.31 after nephrectomy (p <0.0001). Preoperative endogenous creatinine clearance was 70.8 ml per minute per 1.73 m, which decreased to 49.0 ml per minute per 1.73 m after nephrectomy (p <0.0001). Mean MAG3 clearance of the remaining kidney increased 35.1% above baseline from 156.5 to 211.5 ml per minute per 1.73 m following nephrectomy. Spearman rank core analysis revealed that preoperative MAG3 clearance of the remaining kidney significantly correlated with postoperative creatinine clearance (r = 0.596, p = 0.0005). Preoperative MAG3 clearance of the remaining kidney more than 130 ml per minute per 1.73 m coincided with postoperative creatinine clearance above 40 ml per minute per 1.73 m. CONCLUSIONS: MAG3 renal scintigraphy may be useful for predicting renal insufficiency after nephrectomy. The findings in this study suggest that preoperative MAG3 clearance of the remaining kidney less than 130 ml per minute per 1.73 m is a risk factor for postoperative renal insufficiency.     

Nephron sparing surgery for central renal tumors: experience with 33 cases

PURPOSE: Nephron sparing surgery is standard treatment for small, peripherally located renal cell carcinoma. In patients with a solitary kidney, bilateral tumors or impaired renal function nephron sparing surgery provides the only option to nephrectomy and subsequent hemodialysis or transplantation. We retrospectively investigated the value of nephron sparing surgery for centrally located renal cell carcinoma. MATERIALS AND METHODS: Between 1969 and 1997, 311 renal tumor enucleations were performed at our institution. The tumor was centrally located in 33 cases. The indication for enucleation was elective in 7 cases and imperative in 26, including bilateral tumor in 16 (metachronous in 9 and synchronous in 7), chronic renal failure in 4 and solitary kidney in 6. Four patients had metastasis at enucleation. RESULTS: Convalescence was unremarkable in 28 cases. Hemorrhage occurred in 1 patient, a urinary fistula in 2 and a local abscess secondary to a urinary fistula in 1. One patient died postoperatively of heart failure. Average serum creatinine was 1.25, 1.63 and 1.33 mg./dl. preoperatively, at hospital discharge and at a mean followup of 33 months, respectively. Hemodialysis was necessary transiently during convalescence in 1 patient and permanently starting 6 years after enucleation in another. Definitive histology revealed oncocytoma in 4 cases and renal cell carcinoma in 29. Disease was stages pT1 to pT3 in 9, 18 and 2 cases, and grades 1 to 3 in 6, 18 and 5, respectively. Local recurrence developed in 2 patients. Mean followup was 5.2 years (range 0.3 to 16.7). At a mean followup of 6.2 years (range 0.7 to 16.7) 20 patients were free of disease. In addition to the patient who died postoperatively, 9 died of renal cell carcinoma at a mean of 1.6 years (range 0.3 to 5.3) and 3 died of other causes at 5, 11 and 12 years postoperatively, respectively. No patient who underwent elective enucleation died. CONCLUSIONS: Nephron sparing surgery for centrally located kidney tumors is technically feasible and associated with an acceptable complication rate. Local tumor control is excellent, and the overall prognosis depends on contralateral disease and metastasis. Benign tumors may be diagnosed and removed without loss of the kidney. By avoiding hemodialysis quality of life is improved.     

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.     

Nicotinamide adenine dinucleotide staining immediately following radio frequency ablation of renal tumors-is a positive stain synonymous with ablative failure?

PURPOSE: Nicotinamide adenine dinucleotide diaphorase staining is arguably the standard for assessing tissue viability following radio frequency ablation, yet the accuracy of this test is questionable. Thus, it is imperative to examine the reliability of nicotinamide adenine dinucleotide to predict ablation success. To evaluate the observation that immediate nicotinamide adenine dinucleotide staining may not be clinically reliable, we compared results from immediate post-ablation biopsies of renal tumors to radiological and clinical followup. MATERIALS AND METHODS: Laparoscopic radio frequency ablation was performed in 9 patients and 10 tumors using a temperature modulated radio frequency system. Cold cup biopsies were taken immediately following ablation, and processed for nicotinamide adenine dinucleotide and hematoxylin and eosin staining. Patients were then followed using contrast enhanced computerized tomography at regular intervals. RESULTS: Median tumor size was 2.3 cm. Hematoxylin and eosin stain diagnosed 8 renal cell carcinomas and 2 angiomyolipomas. A quarter of the renal cell carcinomas and both angiomyolipomas stained positive for scattered nicotinamide adenine dinucleotide diaphorase activity immediately after RFA. Mean followup for the nicotinamide adenine dinucleotide positive tumors was 28.5 months (range 24 to 30) and for the nicotinamide adenine dinucleotide negative tumors was 25 months (range 18 to 30). There was no evidence of local tumor recurrence in any patient. CONCLUSIONS: Four lesions had nicotinamide adenine dinucleotide diaphorase activity on post-ablation biopsy suggesting retained viable tissue, yet there has been no recurrence during an average 2-year followup. While negative nicotinamide adenine dinucleotide staining is consistent with nonviability, these results suggest that false-positive staining can occur immediately following RFA, making the predictive value of positive nicotinamide adenine dinucleotide diaphorase staining unclear.     

Surgical management of renal tumors 4 cm. or less in a contemporary cohort

PURPOSE: We evaluated a patient cohort with renal tumors 4 cm. or less treated with partial or radical nephrectomy. We compared patient and tumor characteristics, and survival in these 2 groups. MATERIALS AND METHODS: We retrospectively analyzed the records of 670 patients with a median age of 63 years treated surgically for renal cell carcinoma between July 31, 1989 and July 31, 1997. Renal tumors 4.0 cm. or less were noted in 252 patients (38%) who underwent a total of 262 procedures, including 183 radical (70%) and 79 partial (30%) nephrectomies. Ten patients required 2 operations each because of bilateral renal cell carcinoma. Median followup was 40 months. We compared clinicopathological parameters in the partial and radical nephrectomy groups using chi-square or Wilcoxon analysis as appropriate. Survival analysis was determined by the log rank test and Cox regression model. RESULTS: The partial and radical nephrectomy groups were comparable with respect to gender ratio, tumor presentation, histological classification, pathological stage and complication rate. Median tumor size was 2.5 and 3.0 cm. in the partial and radical nephrectomy groups, respectively (p = 0.0001). Resection was incomplete in 1 patient (1.3%) in the partial and none in the radical nephrectomy group. There was no local recurrence after either procedure, and no significant difference in disease specific, disease-free and overall survival (p = 0.98, 0.23 and 0.20, respectively). CONCLUSIONS: Patients with a small renal tumor have similar perioperative morbidity, pathological stage and outcome regardless of treatment with partial or radical nephrectomy. Therefore, partial nephrectomy remains a safe alternative for tumors of this size.     

The accuracy of 250 fine needle biopsies of renal tumors

PURPOSE: In some cases of uncertain lesions in the kidney it would be helpful to perform biopsies for preoperative histopathological evaluation. In this study we evaluated the accuracy of and the impact on tumor management of core biopsy for histopathological evaluation of small solid renal masses. MATERIALS AND METHODS: After radical or partial nephrectomy 250 renal tumor biopsies were performed in 50 patients. All biopsies were performed by 1 urologist after preparation of the kidney ex situ on back table visually guided. Formalin fixed paraffin embedded biopsies were evaluated by 1 pathologist. RESULTS: In 49 of 50 cases (98%) we could define the malignant behavior of the tumor when performing 1 central and 4 peripheral biopsies of each tumor. In 85.2% the grading was correctly defined. A benign lesion was revealed in 4 cases (8%, all oncocytoma). In renal tumors 4 cm or smaller in diameter the accuracy of 1 central and 1 peripheral biopsy each regarding definition of tumor origin, tumor grading and cell type/growth pattern was 96% and 95.5%, 84% and 84.4%, and 87.5% and 89.5%, respectively. In renal tumors more than 4 cm in diameter the accuracy was 100% and 98.1%, 85% and 94.3%, and 71.4% and 88.7%, respectively. CONCLUSIONS: Core biopsy of renal lesions is accurate enough for histopathological evaluation and determination of therapeutic procedure. Additionally, biopsy could be used for identifying benign renal lesion for observation.     

射频消融治疗功能性孤立肾肾细胞癌的临床分析

目的 探讨射频消融治疗功能性孤立肾肾细胞癌的可行性及临床疗效. 方法对5例功能性孤立肾肾细胞癌患者实施射频消融治疗.B超、CT扫描检查肿瘤位于左肾3例,右肾2例.肿瘤最大径3.0～6.0 cm,未发现远处转移灶.T1aN0M0 3例,T1bN0M0 2例.术前常规实验室检查,术后采用增强CT扫描(CECT)、超声造影(CEUS)定期随访. 结果 5例平均手术时间(100.0±28.5)min,平均出血量(95.0±30.5)ml,术中、术后均未输血.术后均有发热,体温(38.2±0.7)℃.术后1周CEUS示5例肾癌病灶均完全消融.血红蛋白(Hb)、血肌酐(SCr)、患侧ECT-肾小球滤过率(ECT-GFR)和肌酐清除率(Ccr)较术前均无明显变化(P>0.05).随访5～19个月,中位数11.5个月,均未见复发,SCr维持(87.5±17.3)μmol/L. 结论 射频消融治疗功能性孤立肾肾细胞癌具有保留肾单位、并发症少及恢复快等优势,是目前治疗功能性孤立肾肾细胞癌一种可选择的方法.     

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.     

Residual and recurrent disease following renal energy ablative therapy: a multi-institutional study

PURPOSE: In this study we detail the incidence and pattern of residual and recurrent disease after radio frequency ablation or cryoablation of a renal mass and, using this information, determine reasonable minimum recommendations for when to perform surveillance imaging during year 1 after treatment. To our knowledge no evidence based guidelines exist for determining how or when followup abdominal imaging should be performed after renal energy ablative therapy. MATERIALS AND METHODS: We reviewed treatment and followup information of patients who underwent radio frequency ablation or cryoablation for a renal mass at 7 institutions. Postoperative monitoring was performed using a variety of surveillance schedules. RESULTS: Of 616 patients 63 were found to have residual or recurrent disease after primary radio frequency ablation (13.4%) or cryoablation (3.9%) for a median of 8.7% in 7 institutions. Most incomplete treatments (70%) were detected within the first 3 months. After salvage ablative therapy was rendered, therapy failed in only 4.2%. At a mean followup of 2 years patients with residual or recurrent disease had an overall survival rate of 82.5% and a 2-year metastasis-free survival rate of 97.4% for those with localized, unilateral renal tumors. CONCLUSIONS: In most cases initial treatment failure was detected within the first 3 months after treatment. Our findings support a minimum of 3 to 4 imaging studies in year 1 after ablative therapy, and at months 1, 3, 6 (optional) and 12.     

Radio-frequency ablation of renal cell carcinoma: early clinical experienc.

Purpose: To report the authors' early experience with radio-frequency (RF) ablation of renal cell carcinoma.Materials and Methods: Twenty-four percutaneous RF ablation treatments for nine tumors were performed in eight patients with renal cell carcinoma. Indications included coexistent morbidity, previous surgery, or solitary kidney in patients with a life expectancy shorter than 10 years. Smaller (⩽3-cm) peripheral lesions (n = 3) were treated with single electrodes. All but one of the larger (>3 cm) and/or central lesions (n = 6) were treated with cluster or multiple electrodes. Patients returned for a second treatment when follow-up imaging depicted tumor enhancement. Follow-up imaging was performed at 1 and 3 months and then at 6-month intervals, with a mean follow-up of 10.3 months. Seven patients were alive at least 6 months after their initial treatment.Results: All five exophytic tumors were free of enhancement. One of three central tumors was free of enhancement. One tumor had both central and exophytic components and was free of enhancement. Three tumors were 3 cm or smaller and free of enhancement. Of the six tumors larger than 3 cm, four were free of enhancement.Conclusion: Percutaneous RF ablation is a promising treatment for select patients with renal cell carcinoma. The ultimate role of this modality will continue to evolve and warrants further study.CommentaryNew minimally invasive technologies are currently being applied to the field of nephron-sparing surgery (NSS) for renal cell carcinoma (RCC) in an effort to decrease operative time, pain, morbidity and hospital stay. Methods of tumor ablation have included cryotherapy, radio-frequency ablation (RFA), high intensity focused ultrasound (HIFU), laser and microwave coagulation. These new modalities are currently being administered laparoscopically or percutaneously; ultimately, completely extracorporeal techniques may be feasible.The primary mechanism of tissue destruction with RFA is thermonecrosis. Radio-frequency energy causes high frequency current flow from the needle electrode into the surrounding tissue. This causes ionic agitation, molecular friction, cellular warming with rapid dessication and cell death. The size and configuration of the lesion are related to the amount of energy delivered, ablation time, tissue impedance, electrolyte content of the tissue and surface area of the electrode. It is a major technical challenge to control for each of these variables independently.The major concern with RFA and related ablative technologies is the ability to image the destructive process precisely as it is being administered, thereby minimizing injury to normal adjacent parenchyma while assuring complete tumor ablation. Since a surgical specimen is not removed for pathologic study, histologic documentation of complete tumor destruction and accurate tumor staging/grading are not available. Meticulous long-term clinical and radiographic follow-up of treated patients is ultimately needed to validate the efficacy of ablative techniques such as RFA for treating renal malignancy.Andrew C. Novick, M.D.     

High intensity focused ultrasound as noninvasive therapy for multilocal renal cell carcinoma: case study and review of the literature

PURPOSE: Noninvasive tumor ablation can be achieved by extracorporeally induced high intensity focused ultrasound. Clinical high intensity focused ultrasound performed to date for renal tumors have only been experimental in nature. We present specific details on a patient with renal cell carcinoma who underwent high intensity focused ultrasound with curative intent and long-term followup examinations. MATERIALS AND METHODS: Ultrasound waves were generated by a cylindrical piezoelectric element focused by a paraboloid reflector. High intensity focused ultrasound was applied to 3 tumors in 3 sessions with the patient under general anesthesia or sedation analgesia, followed by magnetic resonance imaging for 6 months. RESULTS: After treatment magnetic resonance imaging showed necrosis in the 2 tumors in the lower kidney pole within 17 and 48 days, respectively. The necrotic tumor area shrank thereafter within 6 months. The tumor in the upper pole was not affected by treatment due to absorption of the ultrasound energy by the interposed ribs. General anesthesia was required to apply high energy levels of focused ultrasound. Absorption of high intensity focused ultrasound in the tissue induced sharply demarcated thermonecrosis. For 50 years patients have been treated with high intensity focused ultrasound for different indications, focusing on the brain, eyes, prostate, liver and bladder. For the kidney experimental but only few clinical studies indicate sufficient tissue ablation. CONCLUSIONS: In our case contactless noninvasive application of high intensity focused ultrasound to 2 renal carcinomas achieved thermal ablation. When high intensity focused ultrasound energy was coupled correctly, no lesions occurred outside of the target area. Successful high intensity focused ultrasound application depended on optimum energy coupling, a sufficiently high ultrasound energy level and general anesthesia.     

高龄复发性小肝癌再治疗方式的择取与安全性比较

目的探讨高龄复发性小肝癌再治疗术式的择取,并对其安全性进行比较。方法回顾性分析2015年9月至2017年8月接受治疗的106例高龄复发性小肝癌患者资料,根据治疗方式不同分为再切除组(n=55例,再切除手术治疗)和射频组(n=51例,射频消融治疗)。用SPSS 23.0统计软件分析数据,住院时间、总生存时间等以(x±s)表示,采用独立样本t检验;并发症、复发率等以率表示,采用χ²检验。累积生存率采用Log Rank检验。P<0.05为差异有统计学意义。结果再切除组住院时间比射频组长(P<0.05),两组患者总生存时间相比,差异无统计学意义(P>0.05)。再切除组患者术后1年、2年生存率及复发率与射频组相比,差异均无统计学意义(P>0.05)。射频组患者治疗后并发症总发生率为9.8%低于再切除组25.5%(P<0.05).结论与二次手术切除相比,采用经皮射频消融治疗高龄复发性小肝癌患者在术后恢复、降低并发症方面具有明显优势,但两者近期疗效相似。