Aaron H. Lay

Oncologic Efficacy of Radio Frequency Ablation for Small Renal Masses: Clear Cell vs Papillary Subtype

PURPOSE Current radio frequency ablation series do not distinguish renal cell carcinoma subtypes when reporting oncologic efficacy. Papillary neoplasms may be more amenable to radio frequency ablation than clear cell carcinoma because they are less vascular, which may limit heat energy loss. We report the long-term outcomes of patients treated with radio frequency ablation for small renal masses by renal cell carcinoma subtype. MATERIALS AND METHODS The records of patients undergoing radio frequency ablation for small renal masses (cT1a) at 2 institutions from March 2007 to July 2012 were retrospectively reviewed. Patients were included in analysis if they had biopsy confirmed clear cell or papillary renal cell carcinoma histology. Patients had at least 1 contrast enhanced cross-sectional image following radio frequency ablation. Demographic data between tumor subtypes were compared using the paired t-test. Oncologic outcomes were determined by Kaplan-Meier survival analysis and survivor curves were compared with the log rank test. RESULTS A total of 229 patients met study inclusion criteria. There were 181 clear cell tumors and 48 papillary tumors. Median followup was 33.2 months. There was no difference between tumor groups based on patient age, tumor size or grade, or months of followup. Five-year disease-free survival was 89.7% for clear cell tumors and 100% for papillary tumors (p = 0.041). There was no significant difference in overall survival (88.4% vs 89.6%, p = 0.764). CONCLUSIONS Radio frequency ablation outcomes seem to be determined in part by renal cell carcinoma subtype with clear cell renal tumors having less favorable outcomes. We hypothesize that this is due to differences in tumor vascularity. Our experience suggests that future tumor ablation studies should consider reporting outcomes based on tumor cell types.

Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging to Identify Clear Cell Renal Cell Carcinoma in cT1a Renal Masses

Purpose: The detection of small renal masses is increasing with the use of cross‐sectional imaging, although many incidental lesions have negligible metastatic potential. Among malignant masses clear cell renal cell carcinoma is the most prevalent and aggressive subtype. A method to identify such histology would aid in risk stratification. Our goal was to evaluate a likelihood scale for multiparametric magnetic resonance imaging in the diagnosis of clear cell histology. Materials and Methods: We retrospectively reviewed the records of patients with cT1a masses who underwent magnetic resonance imaging and partial or radical nephrectomy from December 2011 to July 2015. Seven radiologists with different levels of experience who were blinded to final pathology findings independently reviewed studies based on a predefined algorithm. They applied a clear cell likelihood score, including 1—definitely not, 2—probably not, 3—equivocal, 4—probably and 5—definitely. Binary classification was used to determine the accuracy of clear cell vs all other histologies. Interobserver agreement was calculated with the weighted &kgr; statistic. Results: A total of 110 patients with 121 masses were identified. Mean tumor size was 2.4 cm and 50% of the lesions were clear cell. Defining clear cell as scores of 4 or greater demonstrated 78% sensitivity and 80% specificity while scores of 3 or greater showed 95% sensitivity and 58% specificity. Interobserver agreement was moderate to good with a mean &kgr; of 0.53. Conclusions: A clear cell likelihood score used with magnetic resonance imaging can reasonably identify clear cell histology in small renal masses and may decrease the number of diagnostic renal mass biopsies. Standardization of imaging protocols and reporting criteria is needed to improve interobserver reliability.

Diagnostic performance and interreader agreement of a standardized MR imaging approach in the prediction of small renal mass histology

Purpose To assess the diagnostic performance and interreader agreement of a standardized diagnostic algorithm in determining the histologic type of small (≤4 cm) renal masses (SRMs) with multiparametric magnetic resonance (MR) imaging. Materials and Methods This single-center retrospective HIPAA-compliant institutional review board-approved study included 103 patients with 109 SRMs resected between December 2011 and July 2015. The requirement for informed consent was waived. Presurgical renal MR images were reviewed by seven radiologists with diverse experience. Eleven MR imaging features were assessed, and a standardized diagnostic algorithm was used to determine the most likely histologic diagnosis, which was compared with histopathology results after surgery. Interreader variability was tested with the Cohen κ statistic. Regression models using MR imaging features were used to predict the histopathologic diagnosis with 5% significance level. Results Clear cell renal cell carcinoma (RCC) and papillary RCC were diagnosed, with sensitivities of 85% (47 of 55) and 80% (20 of 25), respectively, and specificities of 76% (41 of 54) and 94% (79 of 84), respectively. Interreader agreement was moderate to substantial (clear cell RCC, κ = 0.58; papillary RCC, κ = 0.73). Signal intensity (SI) of the lesion on T2-weighted MR images and degree of contrast enhancement (CE) during the corticomedullary phase were independent predictors of clear cell RCC (SI odds ratio [OR]: 3.19; 95% confidence interval [CI]: 1.4, 7.1; P = .003; CE OR, 4.45; 95% CI: 1.8, 10.8; P < .001) and papillary RCC (CE OR, 0.053; 95% CI: 0.02, 0.2; P < .001), and both had substantial interreader agreement (SI, κ = 0.69; CE, κ = 0.71). Poorer performance was observed for chromophobe histology, oncocytomas, and minimal fat angiomyolipomas, (sensitivity range, 14%-67%; specificity range, 97%-99%), with fair to moderate interreader agreement (κ range = 0.23-0.43). Segmental enhancement inversion was an independent predictor of oncocytomas (OR, 16.21; 95% CI: 1.0, 275.4; P = .049), with moderate interreader agreement (κ = 0.49). Conclusion The proposed standardized MR imaging-based diagnostic algorithm had diagnostic accuracy of 81% (88 of 109) and 91% (99 of 109) in the diagnosis of clear cell RCC and papillary RCC, respectively, while achieving moderate to substantial interreader agreement among seven radiologists.

The Usefulness of Chest X-Rays for T1a Renal Cell Carcinoma Surveillance

PURPOSE The overall incidence of pulmonary metastasis of T1 renal cell carcinoma is low. We evaluated the usefulness of chest x-rays based on the current AUA (American Urological Association) guidelines and NCCN Guidelines® for T1a renal cell carcinoma surveillance. MATERIALS AND METHODS Between 2006 and 2012, 258 patients with T1a renal cell carcinoma were treated with partial nephrectomy, radical nephrectomy or radio frequency ablation with surveillance followup at our institution. A retrospective chart review was performed to identify demographics, pathological findings and surveillance records. The primary outcome was the incidence of asymptomatic pulmonary recurrences diagnosed by chest x-ray in cases of T1a disease. Our secondary outcome was a comparison of diagnoses by treatment modality (partial nephrectomy, radical nephrectomy or radio frequency ablation). RESULTS Pulmonary metastases developed in 3 of 258 patients (1.2%) but only 1 (0.4%) was diagnosed by standard chest x-ray surveillance. Median followup in the entire cohort was 36 months (range 6 to 152) and 193 of 258 patients (75%) had greater than 24 months of followup. A mean of 3.3 surveillance chest x-rays were completed per patient. When assessed by treatment type, there was no significant difference in the recurrence rate for partial nephrectomy (0 of 191 cases), radical nephrectomy (0 of 22) or radio frequency ablation (1 of 45 or 2.2%) (p = 0.09). CONCLUSIONS Chest x-rays are a low yield diagnostic tool for detecting pulmonary metastasis in patients treated for T1a renal cel carcinoma. Treatment mode does not appear to influence the need for chest x-ray surveillance.

Likelihood of Incomplete Kidney Tumor Ablation with Radio Frequency Energy: Degree of Enhancement Matters

PURPOSE Larger size and clear cell histopathology are associated with worse outcomes for malignant renal tumors treated with radio frequency ablation. We hypothesize that greater tumor enhancement may be a risk factor for radio frequency ablation failure due to increased vascularity. MATERIALS AND METHODS A retrospective review of patients who underwent radio frequency ablation for renal tumors with contrast enhanced imaging available was performed. The change in Hounsfield units (HU) of the tumor from the noncontrast phase to the contrast enhanced arterial phase was calculated. Radio frequency ablation failure rates for biopsy confirmed malignant tumors were compared using the chi-squared test. Multivariate logistic analysis was performed to assess predictive variables for radio frequency ablation failure. Disease-free survival was calculated using Kaplan-Meier analysis. RESULTS A total of 99 patients with biopsy confirmed malignant renal tumors and contrast enhanced imaging were identified. The incomplete ablation rate was significantly lower for tumors with enhancement less than 60 vs 60 HU or greater (0.0% vs 14.6%, p=0.005). On multivariate logistic regression analysis tumor enhancement 60 HU or greater (OR 1.14, p=0.008) remained a significant predictor of incomplete initial ablation. The 5-year disease-free survival for size less than 3 cm was 100% vs 69.2% for size 3 cm or greater (p <0.01), while 5-year disease-free survival for HU change less than 60 was 100% vs 92.4% for HU change 60 or greater (p=0.24). CONCLUSIONS Biopsy confirmed malignant renal tumors, which exhibit a change in enhancement of 60 HU or greater, experience a higher rate of incomplete initial tumor ablation than tumors with enhancement less than 60 HU. Size 3 cm or greater portends worse 5-year disease-free survival after radio frequency ablation. The degree of enhancement should be considered when counseling patients before radio frequency ablation.

Detecting positive surgical margins: utilisation of light‐reflectance spectroscopy on ex vivo prostate specimens

To assess the efficacy of light‐reflectance spectroscopy (LRS) to detect positive surgical margins (PSMs) on ex vivo radical prostatectomy (RP) specimens.

Three-Dimensional Printing of Surgical Clips: An in Vitro Pilot Study and Trial of Efficacy

INTRODUCTION AND OBJECTIVE Three-dimensional (3D) printing applications have increased over the past decade. Our objective was to test rapid prototyping of a 3D printed surgical clip for intraoperative use. MATERIALS AND METHODS Our prototype was modeled after the 10 mm Weck® Hem-o-lok® polymer clip (Teleflex, Inc., Wayne, PA). A 3D computer-aided design model of the Hem-o-lok clip was reverse engineered using commercial microscopy and printing was done using an Objet Connex500 multijetting system (Stratasys, Eden Prairie, MN). The initial polymer was Objet VeroWhitePlus RGD835; the addition of Objet TangoBlackPlus FLX980 during the design process improved hinge flexibility. The 3D printed clips were then pressure tested on rubber Penrose tubing and compared in vitro versus commercial Hem-o-lok clips. RESULTS Initial 3D printed clips were not functional as they split at the hinge upon closure of the clip jaws. Design changes were made to add Objet TangoBlackPlus FLX980 at the hinge to improve flexibility. Additional modifications were made to allow for clips to be compatible with the Hem-o-lok endoscopic clip applier. A total of 50 clips were tested. Fracture rate for the printed clips using a clip applier was 54% (n = 27), whereas none of the commercial Hem-o-lok clips broke upon closure. Of the 23 printed clips that closed, mean leak was at 20.7 κPa (range 4.8-42.7). In contrast, none of the commercial clips leaked, and fill continued until Penrose rupture at mean 46.2 κPa (44.8-47.6). CONCLUSIONS This pilot study demonstrates feasibility of 3D printing functional surgical clips. However, the performance of our first generation clips is poor compared with commercial grade product. Refinement in printers and materials available may allow for customization of such printed surgical instruments that could be economically competitive to purchasing and stocking product.

Effect of Differing Parameters on Irreversible Electroporation in a Porcine Model

INTRODUCTION AND OBJECTIVE Irreversible electroporation (IRE) is a new ablative technology to treat small renal masses. We evaluated differed ablation settings on lesion size and temperature changes in a porcine model. MATERIALS AND METHODS After Institutional Animal Care and Use Committee approval, 36 laparoscopy-guided and 16 open ablations were performed on 13 domestic female pigs. Ablation parameters studied were voltage (1000 V/cm, 1500 V/cm, or 2000 V/cm), probe exposure (1.0 or 1.5 cm), and lesion size over time (survival) (0-, 7-, or 14 day). Temperature changes were monitored during open ablations with differed settings. Gross lesion size was measured, and histologic analysis with hematoxylin and eosin and nicotinamide adenine dinucleotide staining was performed. RESULTS The 1000 V/cm ablations had no gross or histologic lesions. A factorial analysis of variance demonstrated that day (p = 0.56), exposure (p = 0.33), and voltage (p = 0.06) did not demonstrate statistical significance for affecting lesion size. For 1.0 cm probe exposure, 2000 V/cm did more closely approximate expected lesion size (p = 0.02) compared with 1500 V/cm. While significance was not seen for 1.5 cm probe exposure, 2000 V/cm often exceeded expected lesion volume. Only 1 of 4 temperature sensors, located adjacent to one of the IRE probes, noted a significant increase with increased voltage. However, all maximum temperatures remained less than 70°C. CONCLUSIONS Variation in lesion volume was seen with different ablation settings in this porcine model. Maximal energy and probe exposure settings should be utilized to ensure full coverage of target volume/mass, potentially without concern for thermal injury to renal collecting system or nearby structures.

Pain After Percutaneous Irreversible Electroporation of Renal Tumors Is Not Dependent on Tumor Location

INTRODUCTION Irreversible electroporation (IRE) is a non-thermal minimally invasive technique that is used to treat small renal masses (SRMs). Prior work has demonstrated greater narcotic requirements after radiofrequency ablation (RFA) for tumors that are closer to body-wall musculature. We hypothesized that pain after IRE is not dependent on tumor location due to the athermal mechanistic action. MATERIALS AND METHODS A retrospective review of 50 consecutive percutaneous IRE and RFA cases was performed from 2013 to 2014. Eight patients were excluded from analysis due to incomplete anesthesia record and/or multiple ablations per session, leaving 21 patients in each group. Data collected included patient age, sex, body mass index, nephrometry score, shortest distance to the closest body-wall muscle, perioperative narcotic use, and patient-reported pain score. Pearson correlation test and multivariable linear regression were used to identify predictors of postoperative pain, with significance set at p = 0.05. RESULTS There was no difference in the mean distance from tumor edge to the nearest body-wall muscle between IRE and RFA (2.6 cm vs 2.4 cm, p = 0.729, respectively). Total mean perioperative narcotic usage was 20.4 mg after IRE and 26.7 mg after RFA (p = 0.096). Mean postoperative pain score (scale 0-10) was slightly higher after RFA (4.3) compared with IRE (2.4), but this was not statistically significant (p = 0.088). Pearson correlation test identified tumor proximity to be significiantly associated with both pain score (p = 0.011) and postoperative narcotic use (p = 0.049) after RFA but not after IRE. On multivariable analysis, only tumor proximity to the body wall was significantly correlated to pain score (-1.4, p = 0.041) after RFA but was not found to be a factor for pain after IRE. CONCLUSIONS Patients whose tumors lie close to their body-wall musculature do not have greater narcotic requirements or higher pain scores in the perioperative period after IRE. Percutaneous IRE may be preferred over RFA for SRMs that are close to the body wall to minimize pain.

Re: Can Selective Arterial Clamping with Fluorescence Imaging Preserve Kidney Function During Robotic Partial Nephrectomy?

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