Aaron W.P. Maxwell

Renal Cell Carcinoma: Comparison of RENAL Nephrometry and PADUA Scores with Maximum Tumor Diameter for Prediction of Local Recurrence after Thermal Ablation

Purpose To evaluate the performance of the radius, exophytic or endophytic, nearness to collecting system or sinus, anterior or posterior, and location relative to polar lines (RENAL) nephrometry and preoperative aspects and dimensions used for anatomic classification (PADUA) scoring systems and other tumor biometrics for prediction of local tumor recurrence in patients with renal cell carcinoma after thermal ablation. Materials and Methods This HIPAA-compliant study was performed with a waiver of informed consent after institutional review board approval was obtained. A retrospective evaluation of 207 consecutive patients (131 men, 76 women; mean age, 71.9 years ± 10.9) with 217 biopsy-proven renal cell carcinoma tumors treated with thermal ablation was conducted. Serial postablation computed tomography (CT) or magnetic resonance (MR) imaging was used to evaluate for local tumor recurrence. For each tumor, RENAL nephrometry and PADUA scores were calculated by using imaging-derived tumor morphologic data. Several additional tumor biometrics and combinations thereof were also measured, including maximum tumor diameter. The Harrell C index and hazard regression techniques were used to quantify associations with local tumor recurrence. Results The RENAL (hazard ratio, 1.43; P = .003) and PADUA (hazard ratio, 1.80; P < .0001) scores were found to be significantly associated with recurrence when regression techniques were used but demonstrated only poor to fair discrimination according to Harrell C index results (C, 0.68 and 0.75, respectively). Maximum tumor diameter showed the highest discriminatory strength of any individual variable evaluated (C, 0.81) and was also significantly predictive when regression techniques were used (hazard ratio, 2.98; P < .0001). For every 1-cm increase in diameter, the estimated rate of recurrence risk increased by 198%. Conclusion Maximum tumor diameter demonstrates superior performance relative to existing tumor scoring systems and other evaluated biometrics for prediction of local tumor recurrence after renal cell carcinoma ablation.

Evaluation of a Novel Thermal Accelerant for Augmentation of Microwave Energy during Image-guided Tumor Ablation

The primary challenge in thermal ablation of liver tumors (e.g. hepatocellular carcinoma and hepatic colorectal cancer) is the relatively high recurrence rate (~30%) for which incomplete ablation at the periphery of the tumor is the most common reason. In an attempt to overcome this, we have developed a novel thermal accelerant (TA) agent capable of augmenting microwave energy from a distance normally unattainable by a single microwave ablation antenna. This cesium-based block co-polymer compound transforms from a liquid to a gel at body temperature and is intrinsically visible by computed tomography. Using an agarose phantom model, herein we demonstrate that both the rate and magnitude of temperature increase during microwave ablation were significantly greater in the presence of TA when compared with controls. These results suggest robust augmentation of microwave energy, and may translate into larger ablation zone volumes within biologic tissues. Further work using in vivo techniques is necessary to confirm these findings.

Primary extraskeletal Ewing sarcoma of the stomach: a rare disease in an uncommon location.

We report the case of a 63-year-old female undergoing evaluation of symptomatic anemia, gastroesophageal reflux disease, and abdominal pain. After a thorough diagnostic workup, a large, ulcerated mass was identified in the patients stomach, and surgical pathology in combination with molecular analysis yielded a diagnosis of primary extraskeletal Ewing sarcoma. In our report, we discuss the epidemiologic, clinicopathologic, and radiographic features of this rare disease and provide a review of the existing literature.

The in vivo performance of a novel thermal accelerant agent used for augmentation of microwave energy delivery within biologic tissues during image-guided thermal ablation: a porcine study

Abstract Objectives: To investigate the effects of a novel caesium-based thermal accelerant (TA) agent on ablation zone volumes following in vivo microwave ablation of porcine liver and skeletal muscle, and to correlate the effects of TA with target organ perfusion. Materials and methods: This prospective study was performed following institutional animal care and use committee approval. Microwave ablation was performed in liver and resting skeletal muscle in eight Sus scrofa domesticus swine following administration of TA at concentrations of 0 mg/mL (control), 100 mg/mL and 250 mg/mL. Treated tissues were explanted and stained with triphenyltetrazolium chloride (TTC) for quantification of ablation zone volumes, which were compared between TA and control conditions. Hematoxylin and eosin (H&E) staining was also performed for histologic analysis. General mixed modelling with a log-normal distribution was used for all quantitative comparisons (p = 0.05). Results: A total of 28 ablations were performed in the liver and 18 in the skeletal muscle. The use of TA significantly increased ablation zone volumes in a dose-dependent manner in both the porcine muscle and liver (p < 0.01). Both the absolute mean ablation zone volume and percentage increase in ablation zone volume were greater in the resting skeletal muscle than in the liver. In one swine, a qualitative mitigation of heat sink effects was observed by TTC and H&E staining. Non-lethal polymorphic ventricular tachycardia was identified in one swine, treated with intravenous amiodarone. Conclusions: The use of a novel TA agent significantly increased mean ablation zone volumes following microwave ablation using a porcine model. The relationship between TA administration and ablation size was dose-dependent and inversely proportional to the degree of target organ perfusion, and a qualitative reduction in heat-sink effects was observed.

Percutaneous Thermal Ablation for Small-Cell Lung Cancer: Initial Experience with Ten Tumors in Nine Patients

PURPOSE To evaluate outcomes in a small cohort of patients with local or disseminated small-cell lung cancer (SCLC) who received percutaneous thermal ablation therapy. MATERIALS AND METHODS Ten biopsy-proven SCLC tumors in 9 consecutive patients (5 men, 4 women; average age, 73.8 y ± 12.4) were retrospectively evaluated. Average tumor sizes were 1.8 cm ± 0.5 and 2.6 cm ± 1.2 among patients with local and disseminated disease, respectively. Microwave and radiofrequency ablation were each used for 5 tumors. None of the patients with local SCLC received adjuvant therapy following thermal ablation. Median follow-up duration was 16 months (range, 2-48 mo). Median and 1-year overall survival (OS) were compared for patients in the local and disseminated disease groups. RESULTS Median and 1-year OS were better among patients treated for local SCLC compared with disseminated disease (47.0 vs 5.5 mo and 3 [100%] vs 2 [40%], respectively). Pneumothorax occurred in 5 patients (55.6%), and 3 patients received successful outpatient thoracostomy tube placement. No patients were hospitalized, and there were no major complications. CONCLUSIONS This preliminary analysis suggests favorable outcomes in selected patients with local SCLC who undergo percutaneous thermal ablation without adjuvant therapy.

Should Renal Mass Biopsy Be Performed prior to or Concomitantly with Thermal Ablation

PURPOSE To determine diagnostic yield of renal biopsies performed in patients referred for image-guided tumor ablation (IGTA) and the frequency with which biopsy results would have obviated the need for subsequent ablation. MATERIALS AND METHODS Retrospective review of an internal ablation database of a single institution revealed 401 consecutive percutaneous renal mass IGTAs performed from April 2000 to April 2015. Of 401 ablations, 32 were excluded, yielding 369 ablation events in 342 patients, which represented the study cohort. Patients were subdivided into groups according to whether or not biopsy was performed. Lesions were categorized according to size, malignancy/benignity, and pathology. RESULTS IGTA was performed with biopsy for 317/369 (85.9%) and without biopsy for 52/369 (14.1%) lesions. Overall diagnostic yield for percutaneous biopsy was 94.3% (299/317). Based on biopsy results, 82.6% (262/317) were classified as malignant or suspicious, 9.5% (30/317) were classified as likely benign, and 2.2% (7/317) were classified as definitively benign. Only definitively benign lesions were designated as obviating the need for IGTA. IGTA was supported by biopsy results in the remaining 97.8% (310/317), including renal cell carcinomas, oncocytic neoplasms, metastases, and nondiagnostic biopsy results. CONCLUSIONS Biopsy of renal masses with suspicious imaging features rarely (2.2%) obviated the need for IGTA. For patients who have undergone counseling and have elected to forgo active surveillance and surgical options, biopsy can safely be performed concomitantly with ablation.

Clinico-radiologic factors in paraclinoid aneurysms associated with aneurysm rupture: A CTA study

BACKGROUND AND PURPOSE Paraclinoid aneurysms are commonly noted as incidental findings by computed tomography angiography (CTA), and there exists disagreement in the literature as to which patient and aneurysm characteristics predict subsequent rupture. This question is of particular significance given the complex anatomy of the paraclinoid region and the associated risks of aneurysm treatment. The purpose of this study was to determine significant associated risk factors for paraclinoid aneurysm rupture. MATERIALS AND METHODS Medical records and CTA imaging from 179 patients with 205 paraclinoid aneurysms. Patient and aneurysm characteristics including aneurysm size, morphology, and multiplicity were gathered for analysis of rupture risk. Factors influencing the decision to treat or observe unruptured aneurysms were also evaluated. A Cox regression analysis was used, and results were corrected for multiple comparisons using the Bonferroni method. RESULTS Aneurysm size, diameter:neck ratio, and multilobularity were significantly associated with increased rupture risk; however, only multilobularity remained significant after Bonferroni correction for multiple comparisons. Intervention for unruptured aneurysms was significantly more likely to occur among younger patients and multilobulated aneurysms, or those having a larger diameter, height, height:neck ratio, or diameter:neck ratio. CONCLUSIONS Multilobularity constitutes a significant associated risk factor for rupture among paraclinoid aneurysms. Younger age, larger size and multilobulated aneurysms are characteristics that favored treatment over observation in this cohort.

A novel thermal accelerant for augmentation of microwave energy during image-guided tumor ablation

The greatest challenge in image-guided thermal ablation (IGTA) of liver tumors is a relatively high recurrence rate (ca. 30%) due to incomplete ablation. To meet this challenge, we have developed a novel Thermal Accelerator (TA) to demonstrate its capability to, 1) augment microwave (MW) energy from a distance unattainable by antenna alone; 2) turn into a gel at body temperature; 3) act as a CT or US contrast. We have examined the TA efficiency using in vitro and ex vivo models: microwave power, TA dose, frequencies and TA-to-tip distance were varied, and temperature readings compared with and without TA. Using the in vitro model, it was established that both the rate and magnitude of increase in ablation zone temperature were significantly greater with TA under all tested conditions (p<0.0001). On ultrasound imaging, the TA was echogenic as gel. On CT, TA density was proportional to dose, with average values ranging from 329 HU to 3071 HU at 10 mg/mL and 1,000mg/mL, respectively. TA can be accurately deposited to a target area using CT or US as image-guidance and augment MW energy effectively so that ablation time is significantly reduced, which will contribute to complete ablation. The preliminary results obtained from in vivo experiments using swine as an animal model are consistent with the observations made in in vitro and en vivo studies.