Raymond H. Thornton

Irreversible Electroporation Near the Heart: Ventricular Arrhythmias Can Be Prevented With ECG Synchronization

OBJECTIVE Irreversible electroporation is a nonthermal ablative tool that uses direct electrical pulses to create irreversible membrane pores and cell death. The ablation zone is surrounded by a zone of reversibly increased permeability; either zone can cause cardiac arrhythmias. Our purpose was to establish a safety profile for the use of irreversible electroporation close to the heart. MATERIALS AND METHODS The effect of unsynchronized and synchronized (with the R wave on ECG) irreversible electroporation in swine lung and myocardium was studied in 11 pigs. Twelve lead ECG recordings were analyzed by an electrophysiologist for the presence of arrhythmia. Ventricular arrhythmias were categorized as major events. Minor events included all other dysrhythmias or ECG changes. Cardiac and lung tissue was submitted for histopathologic analysis. Electrical field modeling was performed to predict the distance from the applicators over which cells show electroporation-induced increased permeability. RESULTS At less than or equal to 1.7 cm from the heart, fatal (major) events occurred with all unsynchronized irreversible electroporation. No major and three minor events were seen with synchronized irreversible electroporation. At more than 1.7 cm from the heart, two minor events occurred with only unsynchronized irreversible electroporation. Electrical field modeling correlates well with the clinical results, revealing increased cell membrane permeability up to 1.7 cm away from the applicators. Complete lung ablation without intervening live cells was seen. No myocardial injury was seen. CONCLUSION Unsynchronized irreversible electroporation close to the heart can cause fatal ventricular arrhythmias. Synchronizing irreversible electroporation pulse delivery with absolute refractory period avoids significant cardiac arrhythmias.

Subtyping of Non-small Cell Lung Carcinoma: A Comparison of Small Biopsy and Cytology Specimens

Background: There is growing evidence that lung adenocarcinoma and squamous cell carcinoma (SQCC) have distinct oncogenic mutations and divergent therapeutic responses, which is driving the heightened emphasis on accurate pathologic subtyping of non-small cell lung carcinoma (NSCLC). The relative feasibility and accuracy of NSCLC subtyping by small biopsy versus cytology is not well established, particularly in current practice where immunohistochemistry (IHC) is becoming routinely used to aid in this distinction. Methods: Concurrent biopsy and cytology specimens obtained during a single procedure and diagnosed as NSCLC during a 2-year period (n = 101) were reviewed. Concordance of diagnoses in the two methods was assessed. Accuracy was determined based on subsequent resection or autopsy diagnosis (n = 21) or IHC for thyroid transcription factor 1 and p63 on a subset of cases (n = 43). Results: The distribution of definitive versus favored versus unclassified categories (reflecting the degree of diagnostic certainty) was similar for biopsy (71% versus 23% versus 6%, respectively) and cytology (69% versus 19% versus 12%, respectively), p = 0.29. When results from paired specimens were combined, the rate of definitive diagnoses by at least one method was increased to 84% and the unclassified rate was decreased to 4%. NSCLC subtype concordance between biopsy and cytology was 93%. Kappa coefficient (95% confidence interval) for agreement between methods was 0.88 (0.60–0.89) for adenocarcinoma and 0.76 (0.63–0.89) for SQCC. In pairs with discordant diagnoses (n = 7) the correct tumor type was identified with a similar frequency by biopsy (n = 4) and cytology (n = 3). Factors contributing to mistyping were poor differentiation, necrosis, low cellularity, and lack of supporting IHC. All concordant diagnoses for which verification was available (n = 57) were correct. IHC was used more frequently to subtype NSCLC in biopsy than cytology (32% versus 6%; p = 0.0001). Conclusions: Small biopsy and cytology achieve comparable rates of definitive and accurate NSCLC subtyping, and the optimal results are attained when the two modalities are considered jointly. The lower requirement for IHC in cytology highlights the strength of cytomorphology in NSCLC subtyping. Whenever clinically feasible, obtaining parallel biopsy and cytology specimens is encouraged.

Core Needle Lung Biopsy Specimens: Adequacy for EGFR and KRAS Mutational Analysis

OBJECTIVE The purpose of this study was to prospectively compare the adequacy of core needle biopsy specimens with the adequacy of specimens from resected tissue, the histologic reference standard, for mutational analysis of malignant tumors of the lung. SUBJECTS AND METHODS The first 18 patients enrolled in a phase 2 study of gefitinib for lung cancer in July 2004 through August 2005 underwent CT- or fluoroscopy-guided lung biopsy before the start of gefitinib therapy. Three weeks after gefitinib therapy, the patients underwent lung tumor resection. The results of EGFR and KRAS mutational analysis of the core needle biopsy specimens were compared with those of EGFR and KRAS mutational analysis of the surgical specimens. RESULTS Two specimens were unsatisfactory for mutational analysis. The results of mutational assay results of the other 16 specimens were the same as those of analysis of the surgical specimens obtained an average of 31 days after biopsy. CONCLUSION Biopsy with small (18- to 20-gauge) core needles can yield sufficient and reliable samples for mutational analysis. This technique is likely to become an important tool with the increasing use of pharmacotherapy based on the genetics of specific tumors in individual patients.

Comparing Strategies for Operator Eye Protection in the Interventional Radiology Suite

PURPOSE To evaluate the impact of common radiation-shielding strategies, used alone and in combination, on scattered dose to the fluoroscopy operators eye. MATERIALS AND METHODS With an operator phantom positioned at the groin, upper abdomen, and neck, posteroanterior low-dose fluoroscopy was performed at the phantom patients upper abdomen. Operator lens radiation dose rate was recorded with a solid-state dosimeter with and without a leaded table skirt, nonleaded and leaded (0.75 mm lead equivalent) eyeglasses, disposable tungsten-antimony drapes (0.25 mm lead equivalent), and suspended and rolling (0.5 mm lead equivalent) transparent leaded shields. Lens dose measurements were also obtained in right and left 15° anterior obliquities with the operator at the upper abdomen and during digital subtraction angiography (two images per second) with the operator at the patients groin. Each strategys shielding efficacy was expressed as a reduction factor of the lens dose rate compared with the unshielded condition. RESULTS Use of leaded glasses alone reduced the lens dose rate by a factor of five to 10; scatter-shielding drapes alone reduced the dose rate by a factor of five to 25. Use of both implements together was always more protective than either used alone, reducing dose rate by a factor of 25 or more. Lens dose was routinely undetectable when a suspended shield was the only barrier during low-dose fluoroscopy. CONCLUSIONS Use of scatter-shielding drapes or leaded glasses decreases operator lens dose by a factor of five to 25, but the use of both barriers together (or use of leaded shields) provides maximal protection to the interventional radiologists eye.

Current Management of Pyogenic Liver Abscess: Surgery is Now Second-Line Treatment

BACKGROUND The objective of this study was to examine the current treatment for liver abscess and to assess the factors associated with failure of percutaneous drainage. STUDY DESIGN Records of 58 patients with pyogenic hepatic abscess, from 1998 to 2009, were examined. Clinicopathologic variables were analyzed as predictors of failure of percutaneous drainage using multivariable logistic regression. The results of surgical intervention after failure of percutaneous treatment were also examined. RESULTS Fifty-one patients (88%) had a history of malignancy including pancreas (36%), cholangiocarcinoma (17%), colon (12%), and gallbladder (10%). Recent hepatic artery embolization or radiofrequency ablation preceded development of abscess in 13 patients (22%). Fifteen patients (26%) had evidence of biliary tract communication, and 14 of 15 (93%) of these patients had concomitant biliary tract obstruction. Percutaneous drainage was successful in 38 patients (66%) with a median drain dwell time of 26 days (range 3 to 319 days). Five patients (9%) required operative intervention and 2 of these patients (3% overall) died postoperatively from septic complications. Fifteen patients (26%) died with percutaneous drains in place; 9 (60%) of these patients died of cancer progression without evidence of sepsis. Independent predictors of failure of percutaneous drainage included abscesses containing yeast (p = 0.003) and communication of the abscess cavity with the biliary tree (p = 0.02). CONCLUSIONS Pyogenic hepatic abscess was treated successfully in the majority of patients with advanced malignancy, although mortality remained high. The presence of yeast and communication with an untreated obstructed biliary tree were associated with failure of percutaneous drainage. The need for surgical salvage was associated with a high mortality.

Radiofrequency Ablation in the Management of Liver Metastases from Breast Cancer

OBJECTIVE Systemic chemotherapy remains the standard treatment for patients with breast cancer hepatic metastases. Resection of metastases has survival advantages in a small percentage of selected patients. Radiofrequency ablation has been used in small numbers of selected patients. This small series was undertaken to review our experience with radiofrequency ablation in the management of patients with breast cancer hepatic metastases. CONCLUSION Radiofrequency ablation of breast cancer hepatic metastases is safe and may be used to control hepatic deposits in patients with stable or no extrahepatic disease.

Fears, feelings, and facts: interactively communicating benefits and risks of medical radiation with patients.

OBJECTIVE As public awareness of medical radiation exposure increases, there has been heightened awareness among patients and physicians of the importance of holistic benefit-and-risk discussions in shared medical decision making. CONCLUSION We examine the rationale for informed consent and risk communication, draw on the literature on the psychology of radiation risk communication to increase understanding, examine methods commonly used to communicate radiation risk, and suggest strategies for improving communication about medical radiation benefits and risk.

Split-Dose Technique for FDG PET/CT–guided Percutaneous Ablation: A Method to Facilitate Lesion Targeting and to Provide Immediate Assessment of Treatment Effectiveness

PURPOSE To describe a split-dose technique for fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT)-guided ablation that permits both target localization and evaluation of treatment effectiveness. MATERIALS AND METHODS Institutional review board approved the study with a waiver of consent. From July to December 2011, 23 patients (13 women, 10 men; mean age, 59 years; range, 35-87 years) with 29 FDG-avid tumors (median size, 1.4 cm; range, 0.6-4.4 cm) were targeted for ablation. The location of the lesion was the liver (n = 23), lung (n = 4), adrenal gland (n = 1), and thigh (n = 1). Radiofrequency ablation was performed in 17 lesions; microwave ablation, in six; irreversible electroporation, in five; and cryoablation, in one. The pathologic condition of the tumor was metastatic colorectal adenocarcinoma in 18 lesions, primary hepatocellular carcinoma in one lesion, and a variety of metastatic tumors in the remaining 10 lesions. A total of 4 mCi (148 MBq) of FDG was administered before the procedure for localization and imaging guidance. At completion of the ablation, an additional 8 mCi (296 MBq) of FDG was administered to assess ablation adequacy. Results of subsequent imaging follow-up were used to determine if postablation imaging after the second dose of FDG reliably helped predict complete tumor ablation. Descriptive statistics were used to summarize the results. RESULTS Twenty-eight of 29 (97%) ablated lesions showed no residual FDG activity after the second intraprocedural FDG dose. One patient with residual activity underwent immediate biopsy that revealed residual viable tumor and was immediately re-treated. Follow-up imaging at a median of 155 days (range, 92-257 days) after ablation showed local recurrences in two (7%) lesions that were originally negative at postablation PET. CONCLUSION Split-dose FDG PET/CT may be a useful tool to provide both guidance and endpoint evaluation, allowing an opportunity for repeat intervention if necessary. Further work is necessary to validate these concepts.

Treatment of pulmonary colorectal metastases by radiofrequency ablation.

UNLABELLED We evaluated the local tumor control and the survival benefit achieved with radiofrequency ablation (RFA) for nonoperable lung metastases in 45 patients with colorectal cancer. Median survival from the time of RFA was 46 months. One-, 2- and 3-year local tumor progression (LTP)-free survival rates were 92%, 77%, and 77%, respectively. RFA offers very good local control in patients with pulmonary metastases from colorectal cancer. BACKGROUND Radiofrequency ablation has emerged as a potential, lung function-preserving treatment of colorectal lung metastases. PATIENTS AND METHODS Forty-five patients with colorectal pulmonary metastases underwent computed tomography-guided RFA from December 2004 to June 2010. A baseline posttreatment scan was obtained 4-6 weeks after RFA and follow-up imaging studies every 3 months thereafter were obtained and compared to evaluate the tumor progression at site of ablation or elsewhere. The primary end points were LTP-free survival and overall survival from RFA procedure. The Kaplan-Meier method was used to analyze the end points. A Cox proportional hazard model with robust inference was used to estimate the associations between baseline factors and survival end points. RESULTS Sixty-nine metastases were ablated in 45 patients. Tumor size ranged from 0.4 to 3.5 cm. The median number of metastases ablated per patient was 1 (range, 1-3). Median follow-up after RFA was 18 months. Median survival from the time of RFA was 46 months (95% confidence interval [CI], 27.8-47.3). One-, 2- and 3-year overall survival rates from the time of RFA were 95% (95% CI, 82%-99%), 72% (95% CI, 52%-85%), and 50% (95% CI, 26%-71%), respectively. Nine of 69 lesions (13%) progressed and 4 were retreated with no progression after second RFA. Median time to progression was not reached. LTP-free survival from RFA was 92% (95% CI, 82%-97%) at 1 year, 77% (95% CI, 58%-88%) at 2 years, and 77% (95% CI, 58%-88%) at 3 years. CONCLUSION Radiofrequency ablation of lung metastases is an effective minimally invasive, parenchymal-sparing technique that has very good local control rates in patients with pulmonary metastases from colorectal cancer, with LTP-free survival of 77% at 3 years.

Selective Arterial Embolization for Pseudoaneurysms and Arteriovenous Fistula of Renal Artery Branches Following Partial Nephrectomy

PURPOSE We describe the presentation, endovascular management and functional outcomes of 15 patients with renal arterial pseudoaneurysm following open and laparoscopic partial nephrectomy. MATERIALS AND METHODS An institutional review board approved, Health Insurance Portability and Accountability Act compliant retrospective review of a prospectively maintained database revealed that 7 of 1,160 patients who underwent open partial nephrectomy and 8 of 301 treated with laparoscopic partial nephrectomy were diagnosed with a pseudoaneurysm of a renal artery branch between 2003 and 2010. Some cases were associated with arteriovenous fistula. RESULTS Diagnosis of pseudoaneurysm was made a median of 14 days after surgery. Gross hematuria was the most frequent symptom. Median estimated glomerular filtration rate measurements at the preoperative evaluation, postoperatively, on the day the vascular lesion was diagnosed, after embolization and at the last followup were 62, 55, 55, 56 and 58 ml/minute/1.73 m(2), respectively. Median followup was 7.8 months. All patients underwent angiography and superselective coil embolization of 1 or more pseudoaneurysms with or without arteriovenous fistula. Eleven patients had immediate cessation of symptoms while 4 had persistent gross hematuria after the procedure. Of these 4 patients 2 were treated with bedside care, 1 required repeat embolization with thrombin, which was successful, and the remaining patient had coagulopathy and underwent radical nephrectomy for persistent bleeding. CONCLUSIONS Pseudoaneurysms and arteriovenous fistulas of the renal artery are rare complications of partial nephrectomy. Presentation is often delayed. Superselective coil embolization is a safe, minimally invasive treatment option that usually solves the clinical problem and preserves renal function.