Ablation Of Renal Cell Carcinoma Research Articles

Contrast-Enhanced Ultrasound of the Indeterminate Renal Mass, From the AJR "How We Do It" Special Series.

Contrast-enhanced ultrasound (CEUS) is distinguished from CT and MRI by the use of microbubble ultrasound contrast agents (UCAs) with intravascular blood pool distribution. When performing CEUS, low-intensity ultrasound allows real-time tissue subtraction imaging, whereas high-intensity ultrasound leads to microbubble destruction, enabling visualization of the contrast inflow pattern. CEUS has exceptional contrast resolution that enables the detection of even minimal blood flow, achieving very high NPV for ruling out vascular perfusion and providing high frame rates in the evaluation of tissue perfusion dynamics. UCAs undergo hepatic metabolism and pulmonary clearance, ensuring safety in patients with renal impairment. CEUS excels in distinguishing solid from cystic renal masses, with higher sensitivity than CT or MRI for detection of lesion enhancement. CEUS can aid the further characterization of both solid and cystic lesions and may have particular applications in the surveillance of cystic masses and surveillance after renal cell carcinoma ablation. This review describes the use of CEUS to help characterize indeterminate renal masses, based on the authors' institutional experience. The article highlights key differences between CEUS and CT or MRI, and provides practical insights for performing and interpreting CEUS of renal masses.

Assessment of Local Tumor Progression After Image-Guided Thermal Ablation for Renal Cell Carcinoma.

Focal enhancement typically suggests local tumor progression (LTP) after renal cell carcinoma is percutaneously ablated. However, evaluating findings that are false positive or negative of LTP is less familiar to radiologists who have little experience with renal ablation. Various imaging features are encountered during and after thermal ablation. Ablation procedures and previous follow-up imaging should be reviewed before determining if there is LTP. Previous studies have focused on detecting the presence or absence of focal enhancement within the ablation zone. Therefore, various diagnostic pitfalls can be experienced using computed tomography or magnetic resonance imaging examinations. This review aimed to assess how to read images during or after ablation procedures, recognize imaging features of LTP and determine factors that influence LTP.

Effectiveness of Thermal Ablation for Renal Cell Carcinoma after Prior Partial Nephrectomy

BackgroundRepeat partial nephrectomy (PN) for tumors recurring in the ipsilateral kidney is associated with surgical complexity and a higher rate of complications. ObjectiveTo evaluate the local oncologic efficacy of thermal ablation (TA) for renal cell carcinoma (RCC) in the ipsilateral kidney following PN. Design, setting, participationWe included patients who underwent ablation for renal tumors in the ipsilateral kidney after PN between January 2005 and December 2019. Demographics, tumor size, procedural details, complications, pathology, local oncologic outcomes, and survival outcomes are described. Outcome measurements and statistical analysisThe procedural, pathologic, and oncologic outcomes are described. Survival rates were estimated using the Kaplan-Meier method. Results and limitationsA total of 66 patients (46 male and 20 female) with a median age of 62 yr (interquartile range [IQR] 52–69) met our inclusion criteria. In these patients, 74 TA procedures were performed for 86 lesions (median tumor size 1.9 cm, IQR 1.6–2.5). Radiofrequency ablation and cryoablation accounted for 60 (81%) and 14 (19%) procedures, respectively. Three patients (3.7%) had Clavien-Dindo grade III complications. Of 65 lesion biopsies, 62 (95.5%) were diagnostic. The most common subtype was clear cell RCC (n = 37). The median imaging follow-up duration was 60 mo (IQR 43–88). Recurrence in the ablation zone occurred for four lesions (4.6%) at a median of 6.9 mo (IQR 6.4–10.7). The rates of overall, recurrence-free, and disease-free survival were 93.1%, 94.4%, and 65.6% at 5 yr, and 71.6%, 94.4%, and 60.1% at 10 yr, respectively. Limitations include the retrospective design and the lack of a control group. ConclusionsTA is effective for the treatment of RCC in the ipsilateral kidney following PN. Patient summaryHeat treatment to remove tumor tissue is an effective option for small kidney masses recurring after partial kidney removal for cancer. Long-term follow-up data revealed that this treatment resulted in low recurrence and complication rates.

Predictors for complication in renal cancer surgery: a national register study.

Nationwide register data provide unique opportunities for real-world assessment of complications from different surgical methods. This study aimed to assess incidence of, and predictors for, post-operative complications and to evaluate 90-day mortality following different surgical procedures and thermal ablation for renal cell carcinoma (RCC). All patients undergoing surgical treatment and thermal ablation for RCC in Sweden during 2015-2019 were identified from the National Swedish Kidney Cancer Register. Frequencies and types of post-operative complications were analysed. Logistic regression models were used to identify predictors for 90-day major (Clavien-Dindo grades III-V) complications, including death. The overall complication rate was 24% (1295/5505), of which 495 (8.7%) were major complications. Most complications occurred following open surgery, of which bleeding and infection were the most common. Twice as many complications were observed in patients undergoing open surgery compared to minimally invasive surgery (20% vs. 10%, P < 0.001). Statistically significant predictors for major complications irrespective of surgical category and technique were American society of anesthiologists (ASA) score, tumour diameter and serum creatinine. Separating radical and partial nephrectomy, surgical technique remained a significant risk factor for major complications. Most complications occurred within the first 20 days. The overall 90-day readmission rate was 6.2%, and 30- and 90-day mortality rates were 0.47% and 1.5%, respectively. In conclusion, bleeding and infection were the most common major complications after RCC surgery. Twice as many patients undergoing open surgery suffer a major post-operative complication as compared to patients subjected to minimally invasive surgery. General predictors for major complications were ASA score, tumour size, kidney function and surgical technique.

Computed tomography-guided percutaneous microwave ablation for renal cell carcinoma: evaluating the performance of nephrometry scores.

The purpose of the current study is to evaluate the performance of RENAL and mRENAL scores, in the prediction of oncological outcomes in patients treated with microwave ablation (MWA) for (T1) renal cell carcinomas (RCC). Institutional database retrospective research identified 76 patients with a biopsy-proven solitary T1a (84%) or T1b (16%) RCC; all patients underwent CT-guided MWA ablation. Tumor complexity was reviewed by calculating RENAL and mRENAL scores. The majority of the lesions were exophytic (82.9%), with > 7mm nearness to the collecting system (53.9%), located posteriorly (73.6%), and lower to polar lines (61.8%). Mean RENAL and mRENAL scores were 5.7 (SD = 1.9) and 6.1 (SD = 2.1) respectively. Progression rates were significantly higher with greater tumor size (> 4cm), with < 4mm nearness to the collecting system, for tumors crossing a polar line and with the anterior location. None of the above was associated with complications. RENAL and mRENAL scores were significantly higher in patients with incomplete ablation. The ROC analysis showed the significant prognostic ability of both RENAL and mRENAL scores for progression. In both scores, the optimal cut-off point was 6.5. Univariate Cox regression analysis for progression showed a hazard ratio of 7.73 for the RENAL score and 7.48 for the mRENAL score. The results of the present study show that the risk of progression was higher in patients with RENAL and mRENAL score of > 6.5, in T1b tumors, close to the collective system (< 4mm), crossing polar lines and anterior location. CT-guided percutaneous MWA is a safe and effective technique for the treatment of T1a renal cell carcinomas.Different morphometric parameters of RCC tumors includingRENAL and mRENAL score > 6.5, size, proximity to the collecting system, and crossing of polar linesimpact the efficacy of MWA and progressionsurvival rates. • The risk of progression is higher in patients with RENAL and mRENAL score > 6.5, in T1b tumors, close to the collective system (< 4mm), crossing polar lines and anterior location. • The significant prognostic ability of the mRENAL score for progression was higher than the respective of the RENAL score. • Complications were not associated with any of the above factors.

The relationship of apparent diffusion coefficient values of renal cell carcinoma before and after cryotherapy ablation

IntroductionThe diagnosis of renal cell carcinoma (RCC) is increasing due to incidental findings with more frequent use of cross-sectional imaging. Therefore improvements to diagnostic and follow up imaging techniques is necessary. MRI diffusion weighted imaging (DWI) is a recognised method of measuring the diffusion of water within lesions using the apparent diffusion coefficient (ADC), and may have a role in monitoring the efficacy of cryotherapy ablation of RCC. MethodsA retrospective cohort study of 50 patients was approved to investigate if the ADC value can determine the success of cryotherapy ablation treatment for RCC. DWI was performed at a single centre using 1.5 T MRI before and after cryotherapy ablation to the RCC. The control group was considered as the unaffected kidney. The ADC value of the RCC tumour and normal kidney tissue prior to and after cryotherapy ablation was measured, and compared to the result of the MRI. ResultsA statistically significant change in the ADC values was observed, pre ablation (1.562 × 10¯mm2/sec) to the post ablation (1.126 × 10¯³mm2/sec), p < 0.0005. There was no statistical significance in any of the other outcomes measured. ConclusionAlthough a change of ADC value occurred this is likely due to cryotherapy ablation causing coagulative necrosis at the site, and does not determine the success of the cryotherapy ablation. This can be considered a feasibility study for future research. Implications for practiceDWI is a quick addition to routine protocols, does not require intravenous gadolinium based contrast agent, and provides qualitative and quantitative data. Further research is required to establish the role of ADC for treatment monitoring.

Safety and efficacy of RFA versus MWA for T1a renal cell carcinoma: a propensity score analysis

ObjectivesPercutaneous radiofrequency ablation (RFA) is stated as a treatment option for renal cell carcinoma (RCC) smaller than 4 cm (T1a). Microwave ablation (MWA) is a newer technique and is still considered experimental in some guidelines. The objective of this study was to compare the safety and efficacy of RFA and MWA for the treatment of RCC.MethodsPatients with T1a RCC treated by RFA or MWA in two referral centers were retrospectively analyzed. Patient records were evaluated to generate mRENAL nephrometry scores. Local tumor progression (LTP) was considered when new (recurrence) or residual tumor enhancement within/adjacent to the ablation zone was objectified. Differences in LTP-free interval (residual + recurrence) between ablation techniques were assessed with Cox proportional hazards models and propensity score (PS) methods.ResultsIn 164 patients, 87 RFAs and 101 MWAs were performed for 188 RCCs. The primary efficacy rate was 92% (80/87) for RFA and 91% (92/101) for MWA. Sixteen patients had residual disease (RFA (n = 7), MWA (n = 9)) and 9 patients developed recurrence (RFA (n = 7), MWA (n = 2)). LTP-free interval was significantly worse for higher mRENAL nephrometry scores. No difference in LTP-free interval was found between RFA and MWA in a model with inverse probability weighting using PS (HR = 0.99, 95% CI 0.35–2.81, p = 0.98) and in a PS-matched dataset with 110 observations (HR = 0.82, 95% CI 0.16–4.31, p = 0.82). Twenty-eight (14.9%) complications (Clavien-Dindo grade I–IVa) occurred (RFA n = 14, MWA n = 14).ConclusionPrimary efficacy for ablation of RCC is high for both RFA and MWA. No differences in efficacy and safety were observed between RFA and MWA.Key Points• Both RFA and MWA are safe and effective ablation techniques in the treatment of T1a renal cell carcinomas.• High modified RENAL nephrometry scores are associated with shorter local tumor progression-free interval.• MWA can be used as heat-based ablation technique comparable to RFA for the treatment of T1a renal cell carcinomas.

Abstract No. 62 Percutaneous ablation of renal cell carcinoma: a comparative study of effectiveness and safety of cryoablation and microwave ablation

Abstract No. 62 Percutaneous ablation of renal cell carcinoma: a comparative study of effectiveness and safety of cryoablation and microwave ablation

Split-bolus CT urography after microwave ablation of renal cell carcinoma improves image quality and reduces radiation exposure.

To compare image quality and radiation dose between single-bolus 2-phase and split-bolus 1-phase CT Urography (CTU) performed immediately after microwave ablation (MWA) of clinically localized T1 (cT1) RCC. Forty-two consecutive patients (30M, mean age 67.5 ± 9.0) with cT1 RCC were treated with MWA from 7/2013 to 12/2013 at two academic quaternary-care institutions. Renal parenchymal enhancement, collecting system opacification and distention and size-specific dose estimate (SSDE) were quantified and image quality subjectively assessed on single-bolus 2-phase versus split-bolus 1-phase CTU. Kruskal-Wallis and Pearson's Chi-squared tests were performed to assess differences in continuous and categorical variables, respectively. Two-sample T test with equal variances was used to determine differences in quantitative and qualitative image data. Median tumor diameter was larger [2.9cm (IQR 1.7-5.3) vs 3.6cm (IQR 1.7-5.7), p = 0.01] in the split-bolus cohort. Mean abdominal girth (p = 0.20) was similar. Number of antennas used and unenhanced CTs obtained before and during MWA were similar (p = 0.11-0.32). Renal pelvis opacification (2.5 vs 3.5, p < 0.001) and distention (4mm vs 8mm, p < 0.001) were improved and renal enhancement (Right: 127 HU vs 177 HU, p = 0.001; Left: 124 HU vs 185 HU, p < 0.001) was higher for the split-bolus CTU. Image quality was superior for split-bolus CTU (3.2 vs 4.0, p = 0.004). Mean SSDE for the split-bolus CTU was significantly lower [163.9mGy (SD ± 73.9) vs 36.3mGy (SD ± 7.7), p < 0.001]. Split-bolus CTU immediately after MWA of cT1 RCC offers higher image quality, improved opacification/distention of the collecting system and renal parenchymal enhancement at a lower radiation dose.

Computed Tomography-Guided Percutaneous Microwave Ablation for Renal Cell Carcinoma: Impact of Tumor Size on the Progression Survival Rates.

The aim of the present study was to evaluate the safety and efficacy of computed tomography (CT)-guided percutaneous microwave ablation (MWA) of renal cell carcinoma (RCC) along with identifying prognostic factors affecting the progression survival rate. Institutional database retrospective research identified 69 patients with a biopsy proven solitary T1a (82.6%) or TIb (17.4%) RCC who have underwent percutaneous CT-guided MWA. Kaplan–Meier survival estimates for events were graphed and Cox regression analysis was conducted. Mean patient age was 70.4 ± 11.5 years. Mean size of the lesions was 3 ± 1.3 cm. Mean follow up time was 35.6 months (SD = 21.1). The mean progression free survival time from last ablation was 84.2 months. For T1a tumors, the cumulative progression free survival rate for 1, 6, 12 and 36 months were 100% (SE = 0%), 91.2% (SE = 3.7%), 91.2% (SE = 3.7%) and 87.5% (SE = 4.4%); the recurrence free survival rate for T1a RCC was 94.9%. For T1b tumors, the cumulative progression free survival rate for 1, 6, 12 and 36 months were 100% (SE = 0%), 63.6% (SE = 14.5%), 63.6% (SE = 14.5%) and 63.6% (SE = 14.5%). Grade 1 complications were recorded in 5 (7.2%) patients. Significantly greater hazard for progression was found in cases with a tumor size > 4 cm (HR = 9.09, p = 0.048). No statistically important difference regarding tumor progression was recorded between T1a tumors with a diameter ≤3 cm and >3 cm. In summary, the results of the present study show that CT guided percutaneous MWA is an effective technique for treatment of T1a renal cell carcinomas, irrespective of tumor size. T1b tumors were associated with higher progression rates.

PD10-05 RECURRENCE PATTERNS FOLLOWING MICROWAVE ABLATION OF T1A RENAL MASSES: A MULTICENTER ANALYSIS

INTRODUCTION AND OBJECTIVE:The recommended frequency of imaging surveillance following percutaneous ablation of renal cell carcinoma (RCC) is variable among institutions. The purpose of this study ...

Microwave Ablation of Renal Cell Carcinoma.

Management options for small renal masses include active surveillance, partial nephrectomy, radical nephrectomy, and thermal ablation. For tumors typically ≤3 cm in size, thermal ablation is a good option for those desiring an alternative to surgery or active surveillance, especially in patients who are considered high surgical risk. We favor microwave ablation because of the more rapid heating, higher temperatures that overcome the heat sink effect of vessels, reproducible cell kill, and a highly visible ablation zone formed by water vapor that corresponds well to the zone of necrosis. For central tumors, we favor cryoablation because of the slower formation of the ablation zone and less likelihood of damage to the collecting system. With microwaves, it is important to monitor the ablation zone in real time (ultrasound is the best modality for this purpose), avoid direct punctures of the collecting system, and to place probes tangential to the collecting system to avoid burning open a persistent tract between the urothelium and extrarenal spaces or causing strictures. The surgical steps described in this video cover our use of high-frequency jet ventilation with general anesthesia to minimize organ motion, initial imaging and targeting, probe insertion, hydrodissection (a technique that enables displacement of adjacent structures), the ablation itself, and finally our dressing. Postoperative cares typically consist of observation with a same-day discharge or an overnight stay. Follow-up includes a magnetic resonance imaging abdomen with and without contrast, chest X-ray, and laboratories (basic metabolic panel, complete blood count, and C-reactive protein) 6 months postablation. Overall, percutaneous microwave ablation is an effective and safe treatment option for renal cell carcinoma in both T1a and T1b tumors in selected patients with multiple studies showing excellent oncologic outcomes when compared with partial and radical nephrectomy.

A multicenter 10-year oncologic outcome of ultrasound-guided percutaneous microwave ablation of clinical T1 renal cell carcinoma: will it stand the test of time?

We updated the experience on percutaneous microwave ablation for renal cell carcinoma with five-center data and long-term follow-up. This retrospective study reviewed the T1N0M0 renal cell carcinoma patients who underwent microwave ablation between April 2006 and December 2019. Clinicopathological and procedural data were collected. Technical effectiveness and complications were assessed, and the Kaplan-Meier method was used for cancer-specific survival, disease-free survival, overall survival, and local neoplastic process analyses. A total of 323 consecutive patients (mean age, 62.9 years ± 14.0) with 371 biopsy-proved tumors (mean diameter, 2.9 cm ± 1.2) were enrolled, and 42.6% of the tumors were located adjacent to collecting system/bowel and technical effectiveness was achieved in 360 (97.0%) tumors. For 275 cT1a patients, during median follow-up time of 66.0 months (IQR, 58.4-73.6), 10-year local neoplastic processes, cancer-specific survival, disease-free survival, and overall survival rates were 1.9%, 87.4%, 71.8, and 67.5%, respectively. For 48 cT1b patients, during the median follow-up time of 30.4 months (IQR, 17.7-44.8), 5-year local tumor progression, cancer-specific survival, disease-free survival, and overall survival rates were 11.3%, 91.4%, 69.1, and 89.2%, respectively. Major complications showed no differences between cT1a (3.5%) and cT1b (6.9%) patients (p = 0.28). A clinical risk stratification system was developed based on multivariable model to predict DFS and CSS with c-indexes of 0.78 (95% CI: 0.71-0.85) and 0.77 (95% CI: 0.65-0.90), respectively. With matured follow-up at five institutions, ultrasound-guided percutaneous microwave ablation is a reliable treatment option for cT1a renal cell carcinoma even in dangerous location and appears to be promising for cT1b tumors. • To our knowledge, this is the first multicenter cohort of long-term oncologic outcomes with percutaneous MWA of cT1 RCC. • The predicting model we developed is accurate to predict the long-term DFS and CSS, which can help to provide a better MWA prognostication over routinely available clinical information. • The available evidence shows that microwave ablation of clinical stage T1 RCC is safe and reliable with promising long-term oncologic outcomes, especially for cT1a RCC with excellent 10-year results.

Abstract No. 467 Analysis of healthcare cost and resource utilization associated with thermal ablation of renal cell carcinoma

To compare hospital expenditures and resource utilization associated with radiofrequency (RFA), cryoablation (CA), and microwave (MWA) for cT1N0M0 renal cell carcinoma (RCC) A retrospective evaluation was conducted in 470 of computer tomography (CT)-guided thermal ablations of biopsy-proven RCC treated with between October 2006 and June 2019. Components of direct and indirect costs were tabulated and compared across the three different ablation modalities. Deterministic sensitivity analysis was performed to evaluate the effect of the individual cost components in the overall cost of ablative treatment. In-hospital resource utilization incurred from the start of the procedure to 30 days after hospital discharge was examined for each ablative technique. Continuous variables were analyzed using the one-way ANOVA test, and categorical variables were analyzed using Pearson’s chi-squared test and the Kruskal-Wallis test. A total of 470 T1N0M0 RCCs with a mean size of 3.2 cm (range, 0.5–6.9 cm) were treated with MWA (n = 86, 18%), RFA (n = 344, 73%) or CA (n = 40, 9%). Baseline patient or tumor characteristics did not differ significantly between the three groups. The median cost of MWA was significantly lower than that of RFA and CA with a cost advantage of $3835 and $2714, respectively (P = 0.0001). The number of ablation probes used was a major determinant of the overall cost, and MWA used the least number of probes (P = 0.0001). Additionally, MWA was associated with the lowest utilization of procedure room time, anesthesia medications, and radiation dose when compared to RFA and CA (P = 0.001, P = 0.001, and P = 0.001, respectively). Hospital spending and resource utilization in the 30 days immediately after the procedure are similar among the three ablative techniques. Microwave ablation is associated with lowest procedural costs and resource utilization compared to RFA and CA for the treatment of T1 RCC. These findings may incentivize wider use of MWA to optimize value-based care in ablation practice.

Cryoablation for the Treatment of Residual or Recurrent Disease After Prior Microwave Ablation of Renal Cell Carcinoma

Cryoablation for the Treatment of Residual or Recurrent Disease After Prior Microwave Ablation of Renal Cell Carcinoma

Thermal Ablation of Renal Cell Carcinoma in Patients With Morbid Obesity: Assessment of Technique, Safety, and Oncologic Outcomes.

BACKGROUND. Obesity is a worldwide problem that impacts patient health as well as the morbidity associated with surgical procedures. Thus, patients with morbid obesity may not be suitable candidates for curative surgery. For this patient population, thermal ablation may be an effective alternative to nephrectomy. OBJECTIVE. The purpose of this study was to determine the feasibility, oncologic outcomes, and survival of patients with morbid obesity and renal cell carcinoma treated with thermal ablation. MATERIALS AND METHODS. A retrospective analysis was performed of 107 patients treated with CT-guided renal ablation for clinical T1 renal cell carcinoma between February 2005 and December 2017. Patients were stratified into two cohorts on body mass index of ≥ 40 kg/m2 (morbidly obese) and body mass index (weight in kilograms divided by the square of height in meters) of ≥ 40 (morbidly obese) and 18.5-24.9 (normal weight). Anesthetic and radiation dosages, procedure time, residual disease, and local recurrence, and adverse events were analyzed between the two groups. Kaplan-Meier statistics were used to evaluate cancer-related outcomes for each group. RESULTS. Thirty-four patients were morbidly obese, and 73 patients had normal weight. Morbid obesity was associated with longer procedural duration (p = .001), sedative doses (p = .002) and radiation exposure (p = .001) than normal weight. Hematomas were more prevalent in patients with morbid obesity than in those of normal weight (p = .01), but treatment efficacy and local recurrences were comparable with those for normal-weight individuals (p = .81 and p = .12, respectively). Cancer-related outcomes were equivalent between the two groups based on 5 years of imaging observation data. CONCLUSION. CT-guided thermal ablation remains technically feasible, well-tolerated, and effective in patients with morbid obesity and renal cell carcinoma, with the caveat of increased risk of perinephric hematoma, anesthesia dose, and radiation exposure. CLINICAL IMPACT. CT-guided thermal ablation can be considered a safe and effective treatment for renal cell carcinoma in patients with morbid obesity.

Thermal Ablation for Renal Cell Carcinoma: Expert Consensus from the Asian Conference on Tumor Ablation.

Thermal Ablation for Renal Cell Carcinoma: Expert Consensus from the Asian Conference on Tumor Ablation.

Impact of Body Mass Index on Perioperative Complications and Oncologic Outcomes in Patients Undergoing Thermal Ablation for Renal Cell Carcinoma

PurposeTo determine effect of body mass index (BMI) on safety and cancer-related outcomes of thermal ablation for renal cell carcinoma (RRC). Materials and MethodsThis retrospective study evaluated 427 patients (287 men and 140 women; mean [SD] age, 72 [12] y) who were treated with thermal ablation for RCC between October 2006 and December 2017. Patients were stratified by BMI into 3 categories: normal weight (18.5–24.9 kg/m2), overweight (25–29.9 kg/m2), and obese (≥ 30 kg/m2). Of 427 patients, 71 (16%) were normal weight, 157 (37%) were overweight, and 199 (47%) were obese. Complication rates, local recurrence, and residual disease were compared in the 3 cohorts. ResultsNo differences in technical success between normal-weight, overweight, and obese patients were identified (P = .72). Primary technique efficacy rates for normal-weight, overweight, and obese patients were 91%, 94%, and 93% (P = .71). There was no significant difference in RCC specific–free survival, disease-free survival, and metastasis-free survival between obese, overweight, and normal-weight groups (P = .72, P = .43, P = .99). Complication rates between the 3 cohorts were similar (normal weight 4%, overweight 2%, obese 3%; P = .71). ConclusionsCT-guided renal ablation is safe, feasible, and effective regardless of BMI.

CT and MR imaging surveillance of stage 1 renal cell carcinoma after microwave ablation

To describe the CT and MR imaging findings after microwave ablation of clinical stage 1 renal cell carcinoma (RCC). This single-center retrospective study was performed under a waiver of informed consent. 49 patients (38M/11F, mean age 66 ± 9.0) with 52 cT1a RCC and 19 patients (10M/9F, mean age 67 ± 9.7) with 19 cT1b RCC were treated with percutaneous microwave ablation between January 2012 and June 2014. The size and volume of the RCC and ablation zone were measured and the kidney, ablation zones and retroperitoneum were assessed at immediate post-procedure CT and surveillance CT and MRI. Median imaging follow-up was 18months (IQR 12-28). Ablation zones were heterogeneously hyperintense on T1W and hypointense on T2W MRI and hyperdense at CT. Thin peripheral, but no internal enhancement after contrast administration signified successful ablation zones. Ablation zones decreased in size, but did not resolve during surveillance. Immediate post-procedure subcapsular gas and hematoma (5/71, 7%) resolved prior to first follow-up. Focal, enhancing soft tissue within the ablation zone, invariably along the renal margin, signified local recurrence. Local recurrence rates were higher for T1b (2/19, 11%) compared to T1a (1/52, 2%). Urinomas (4/71, 6%) decreased in size and resolved during surveillance. Retroperitoneal fat necrosis (6/71, 9%), with opposed-phase loss of T1W MRI signal, was confirmed at histology after percutaneous biopsy. CT and MR imaging features after microwave ablation of renal cell carcinoma are predictable and reliably demonstrate treatment success, early and delayed complications, and local recurrences that can guide patient management.

Commentary on the Recently Published Society of Interventional Radiology Quality Improvement Standards on Percutaneous Ablation in Renal Cell Carcinoma: Prime Time for Standardized Approach and Quality Improvement.

Commentary on the Recently Published Society of Interventional Radiology Quality Improvement Standards on Percutaneous Ablation in Renal Cell Carcinoma: Prime Time for Standardized Approach and Quality Improvement.