Pigs as Clinically Relevant Models for Synergizing Interventional Oncology and Immunotherapy.

Traditionally, rodent cancer models have driven preclinical oncology research. However, they do not fully recapitulate characteristics of human cancers, and their size poses challenges when evaluating tools in the interventional oncologists' armamentarium. Pig models, however, have been the gold standard for validating surgical procedures. Their size enables the study of image-guided interventions using human ultrasound (US), computed tomography (CT), and magnetic resonance (MR) imaging platforms. Furthermore, pigs have immunologic features that are similar to those of humans, which can potentially be leveraged for studying immunotherapy. Novel pig models of cancer are being developed, but additional research is required to better understand both the pig immune system and malignancy to enhance the potential for pig models in interventional oncology research. This review aims to address the main advantages and disadvantages of using a pig model for interventional oncology and outline the specific characteristics of pig models that make them more suitable for investigation of locoregional therapies.

Bronchial or Pulmonary Artery Chemoembolization for Unresectable and Unablatable Lung Metastases: A Phase I Clinical Trial.

Background Lung chemoembolization is an emerging treatment option for lung tumors, but the optimal embolic, drug, and technique are unknown. Purpose To determine the technical success rate and safety of bronchial or pulmonary artery chemoembolization of lung metastases using ethiodized oil, mitomycin, and microspheres. Materials and Methods Patients with unresectable and unablatable lung, endobronchial, or mediastinal metastases, who failed systemic chemotherapy, were enrolled in this prospective, single-center, single-arm, phase I clinical trial (December 2019-September 2020). Pulmonary and bronchial angiography was performed to determine the blood supply to the lung metastases. Based on the angiographic findings, bronchial or pulmonary artery chemoembolization was performed using an ethiodized oil and mitomycin emulsion, followed by microspheres. The primary objectives were technical success rate and safety, according to the National Cancer Institute Common Terminology Criteria for Adverse Events. CIs of proportions were estimated with the equal-tailed Jeffreys prior interval, and correlations were evaluated with the Spearman test. Results Ten participants (median age, 60 years; interquartile range, 52-70 years; six women) were evaluated. Nine of the 10 participants (90%) had lung metastases supplied by the bronchial artery, and one of the 10 participants (10%) had lung metastases supplied by the pulmonary artery. The technical success rate of intratumoral drug delivery was 10 of 10 (100%) (95% CI: 78, 100). There were no severe adverse events (95% CI: 0, 22). The response rate of treated tumors was one of 10 (10%) according to the Response Evaluation Criteria in Solid Tumors and four of 10 (40%) according to the PET Response Criteria in Solid Tumors. Ethiodized oil retention at 4-6 weeks was correlated with reduced tumor size (ρ = -0.83, P = .003) and metabolic activity (ρ = -0.71, P = .03). Pharmacokinetics showed that 45% of the mitomycin dose underwent burst release in 2 minutes, and 55% of the dose was retained intratumorally with a half-life of more than 5 hours. The initial tumor-to-plasma ratio of mitomycin concentration was 380. Conclusion Lung chemoembolization was technically successful for the treatment of lung, mediastinal, and endobronchial metastases, with no severe adverse events. Clinical trial registration no. NCT04200417 © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Georgiades et al in this issue.

Transarterial Embolization of Liver Cancer in a Transgenic Pig Model.

PURPOSE: To develop and characterize a porcine model of liver cancer that could be used to test new locoregional therapies. MATERIALS AND METHODS: Liver tumors were induced in 18 Oncopigs (transgenic pigs with Cre-inducible TP53R167H and KRASG12D mutations) by using an adenoviral vector encoding the Cre-recombinase gene. The resulting 60 tumors were characterized on multiphase contrast-enhanced CT, angiography, perfusion, micro-CT, and necropsy. Transarterial embolization was performed using 40-120 µm (4 pigs) or 100-300 µm (4 pigs) Embosphere microspheres. Response to embolization was evaluated on imaging. Complications were determined based on daily clinical evaluation, laboratory results, imaging, and necropsy. RESULTS: Liver tumors developed at 60/70 (86%) inoculated sites. Mean tumor size was 2.1 cm (range, 0.3-4 cm) at 1 week. Microscopically, all animals developed poorly differentiated to undifferentiated carcinomas accompanied by a major inflammatory component, which resembled undifferentiated carcinomas of the human pancreatobiliary tract. Cytokeratin and vimentin expression confirmed epithelioid and mesenchymal differentiation, respectively. Lymph node, lung, and peritoneal metastases were seen in some cases. On multiphase CT, all tumors had a hypovascular center, and 17/60 (28%) had a hypervascular rim. After transarterial embolization, noncontrast CT showed retained contrast medium in the tumors. Follow-up contrast-enhanced scan showed reduced size of tumors after embolization using either 40-120 µm or 100-300 µm Embosphere microspheres, while untreated tumors showed continued growth. CONCLUSIONS: Liver tumors can be induced in a transgenic pig and can be successfully treated using bland embolization.

NRF2 Dysregulation in Hepatocellular Carcinoma and Ischemia: A Cohort Study and Laboratory Investigation.

Background Intermediate stage hepatocellular carcinomas (HCCs) are treated by inducing ischemic cell death with transarterial embolization (TAE) or transarterial chemoembolization (TACE). A subset of HCCs harbor nuclear factor E2-related factor 2 (NRF2), a major regulator of the oxidative stress response implicated in cell survival after ischemia. NRF2-mutated HCC response to TAE and/or TACE is unknown. Purpose To test whether ischemia resistance is present in individuals with NRF2-mutated HCC and if this resistance can be overcome by means of NRF2 inhibition in HCC cell lines. Materials and Methods This was a combined retrospective review of an institutional database (from January 2011 to December 2018) and prospective study (from January 2014 to December 2018) of participants with HCC who underwent TAE and a laboratory investigation of HCC cell lines. Imaging follow-up included liver CT or MRI at 1 month after the procedure followed by 3-month interval scans. Tumor radiologic response was assessed on the basis of follow-up imaging. The time to local progression after TAE for individuals with and individuals without NRF2 pathway alterations was estimated by using competing risk analysis (Gray test). The in vitro response to ischemia in four HCC cell lines with and without NRF2 overexpression was evaluated, and the combination of ischemia with NRF2 knockdown by means of short hairpin RNA or an NRF2 inhibitor was tested. Doubling time estimates, dose response curve regression, and comparison analyses were performed. Results Sixty-five individuals (median age, 69 years [range, 19-84 years]; 53 men) were evaluated. HCCs with NRF2 pathway mutation had a shorter time to local progression after TAE compared to those without mutation (6-month cumulative incidence of local progression, 56% [range, 19%-91%] vs 22% [range, 12%-34%], respectively; P < .001) and confirmed ischemia resistance in NRF2-overexpressing HCC cell lines. However, ischemia and NRF2 knock-down worked synergistically to decrease proliferation of NRF2-overexpressing HCC cell lines. Dose response curves of ML385, an NRF2 inhibitor, showed that ischemia induces addiction to NRF2 in cells with NRF2 alterations. Conclusion Hepatocellular carcinoma with nuclear factor E2-related factor 2 (NRF2) alterations showed resistance to ischemia, but ischemia simultaneously induced sensitivity to NRF2 inhibition. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Weiss and Nezami in this issue.

Autologous Blood Patch Injection versus Hydrogel Plug in CT-guided Lung Biopsy: A Prospective Randomized Trial.

Purpose To compare the effect of autologous blood patch injection (ABPI) with that of a hydrogel plug on the rate of pneumothorax at CT-guided percutaneous lung biopsy. Materials and Methods In this prospective randomized controlled trial ( https://ClinicalTrials.gov , NCT02224924), a noninferiority design was used for ABPI, with a 10% noninferiority margin when compared with the hydrogel plug, with the primary outcome of pneumothorax rate within 2 hours of biopsy. A type I error rate of 0.05 and 90% power were specified with a target study population of 552 participants (276 in each arm). From October 2014 to February 2017, all potential study participants referred for CT-guided lung biopsy (n = 2052) were assessed for enrollment. Results The data safety monitoring board recommended the trial be closed to accrual after an interim analysis met prespecified criteria for early stopping based on noninferiority. The final study group consisted of 453 participants who were randomly assigned to the ABPI (n = 226) or hydrogel plug (n = 227) arms. Of these, 407 underwent lung biopsy. Pneumothorax rates within 2 hours of biopsy were 21% (42 of 199) and 29% (60 of 208); chest tube rates were 9% (18 of 199) and 13% (27 of 208); and delayed pneumothorax rates within 2 weeks after biopsy were 1.4% (three of 199) and 1.5% (three of 208) in the ABPI and hydrogel plug arms, respectively. Conclusion Autologous blood patch injection is noninferior to a hydrogel plug regarding the rate of pneumothorax after CT-guided percutaneous lung biopsy. © RSNA, 2018 Online supplemental material is available for this article.

Aspirin Is Associated With Improved Liver Function After Embolization of Hepatocellular Carcinoma.

OBJECTIVE. The purpose of this study was to assess the mechanism by which aspirin therapy improves survival when combined with transarterial chemoembolization or transarterial embolization (TAE) for hepatocellular carcinoma (HCC). MATERIALS AND METHODS. A retrospective review included 304 patients with HCC who were treated with TAE. The patients were divided into two groups on the basis of whether the patient took aspirin (n = 42) or did not take aspirin (n = 262) at the time of initial TAE. For each patient, response of embolized tumors, time to progression, initial site of progression, survival time, and liver function test results before and after embolization were evaluated. RESULTS. Patients taking aspirin and those not taking aspirin at the time of initial TAE for HCC had no difference in initial response rate (88% vs 90% complete response or partial response, p = 0.59), median time to progression (6.2 vs 5.2 months, p = 0.42), initial site of progression (p = 0.77), or fraction of patients dying with disease progression (88% vs 89%, p = 1.00). Before embolization, there was no difference in mean bilirubin level (0.8 vs 0.9 mg/dL, p = 0.11) for patients taking versus not taking aspirin. Among patients taking aspirin, bilirubin level was significantly lower 1 day (0.9 vs 1.3, p < 0.001), 1 month (0.9 vs 1.2, p = 0.048), and 1 year (0.8 vs 1.0, p = 0.021) after embolization. The median overall survival period after initial embolization was longer for patients taking aspirin (57 vs 23 months, p = 0.008). CONCLUSION. Aspirin use is associated with improved liver function test results and survival after TAE for HCC. It is not associated with differences in response or time to progression.

Association of PI3K Pathway Mutations with Early Positron-Emission Tomography/CT Imaging Response after Radioembolization for Breast Cancer Liver Metastases: Results of a Single-Center Retrospective Pilot Study.

PURPOSE: To describe imaging response and survival after radioembolization for metastatic breast cancer and to delineate genetic predictors of imaging responses and outcomes. MATERIALS AND METHODS: This retrospective study included 31 women (average age, 52 y) with liver metastasis from invasive ductal carcinoma who underwent resin and glass radioembolization (average cumulative dose, 2.0 GBq ± 1.8) between January 2011 and September 2017 after receiving ≥ 3 lines of chemotherapy. Twenty-four underwent genetic profiling with MSK-IMPACT or Sequenom; 26 had positron-emission tomography (PET)/CT imaging before and after treatment. Survival after the first radioembolization and 2-4-month PET/CT imaging response were assessed. Laboratory and imaging features were assessed to determine variables predictive of outcomes. Unpaired Student t tests and Fisher exact tests were used to compare responders and nonresponders categorized by changes in fluorodeoxyglucose avidity. Kaplan-Meier survival analysis was used to determine the impact of predictors on survival after radioembolization. RESULTS: Median survival after radioembolization was 11 months (range, 1-49 mo). Most patients (18 of 26; 69%) had complete or partial response based on changes in fluorodeoxyglucose avidity. Imaging response was associated with longer survival (P = .005). Whereas 100% of patients with PI3K pathway mutations showed an imaging response, only 45% of wild-type patients showed a response (P = .01). Median survival did not differ between PI3K pathway wild-type (10.9 mo) and mutant (undefined) patients (P = .50). CONCLUSIONS: These preliminary data suggest that genomic profiling may predict which patients with metastatic breast cancer benefit most from radioembolization. PI3K pathway mutations are associated with improved imaging response, which is associated with longer survival.

DAXX Mutation Status of Embolization-Treated Neuroendocrine Tumors Predicts Shorter Time to Hepatic Progression.

PURPOSE: To identify common gene mutations in patients with neuroendocrine liver metastases (NLM) undergoing transarterial embolization (TAE) and establish relationship between these mutations and response to TAE. MATERIALS AND METHODS: Patients (n = 51; mean age 61 y; 29 men, 22 women) with NLMs who underwent TAE and had available mutation analysis were identified. Mutation status and clinical variables were recorded and evaluated in relation to hepatic progression-free survival (HPFS) (Cox proportional hazards) and time to hepatic progression (TTHP) (competing risk proportional hazards). Subgroup analysis of patients with pancreatic NLM was performed using Fisher exact test to identify correlation between mutation and event (hepatic progression or death) by 6 months. Changes in mutation status over time and across specimens in a subset of patients were recorded. RESULTS: Technical success of TAE was 100%. Common mutations identified were MEN1 (16/51; 31%) and DAXX (13/51; 25%). Median overall survival was 48.7 months. DAXX mutation status (hazard ratio = 6.21; 95% confidence interval [CI], 2.67-14.48; P < .001) and tumor grade (hazard ratio = 3.05; 95% CI, 1.80-5.17; P < .001) were associated with shorter HPFS and TTHP on univariate and multivariate analysis. Median HPFS was 3.6 months (95% CI, 1.7-5.3) for patients with DAXX mutation compared with 8.9 months (95% CI, 6.6-11.4) for patients with DAXX wild-type status. In patients with pancreatic NLMs, DAXX mutation status was associated with hepatic progression or death by 6 months (P = .024). DAXX mutation status was concordant between primary and metastatic sites. CONCLUSIONS: DAXX mutation is common in patients with pancreatic NLMs. DAXX mutation status is associated with shorter HPFS and TTHP after TAE.

Comparison of biliary brush biopsy and fine needle biopsy in the diagnosis of biliary strictures.

PURPOSE: The purpose of this study is to evaluate the accuracy of percutaneous fine needle biopsy (FNB) and brush biopsy (BB) at a cancer center. MATERIAL AND METHODS: Retrospective analysis of all bile duct biopsies performed in Interventional Radiology between January 2000 and January 2015 was performed. FNB was performed under real-time cholangiographic guidance using a notched needle directed at the bile duct stricture. BB was performed by advancing a brush across the stricture and moving it back and forth to scrape the stricture. Biopsy results were categorized as true positive (TP), true negative (TN), false positive (FP) and false negative (FN) based on pathology reports and confirmed by surgical specimens or clinical follow-up of at least six months. Fisher's exact test was used to compare the rate of TP in FNB and BB. RESULTS: One-hundred and nineteen patients underwent FNB or BB. Fifteen were censored because of lack of follow-up. The remaining 104 patients underwent a total of 117 bile duct biopsies during the study period: 34 FNB and 83 BB. There were no complications in either group. In the FNB group 22/34 (64%) biopsies were TP, 4/34(12%) were TN and there were 8(24%) FN biopsies. In the BB group, 20/83 (24%) were TP, 38/83 (46%) TN and 25/83 (30%) FN biopsies. There were no FP biopsies in either group. The sensitivity of detecting malignancy by FNB was significantly higher than that by BB (73% vs 44%, p < .0005). There were no complications associated with FNB or BB. CONCLUSIONS: FNB of bile duct strictures is safe and has a higher sensitivity for detecting malignancy than BB.

Lung Adenocarcinoma: Predictive Value of KRAS Mutation Status in Assessing Local Recurrence in Patients Undergoing Image-guided Ablation.

Purpose To establish the relationship between KRAS mutation status and local recurrence after image-guided ablation of lung adenocarcinoma. Materials and Methods This study consisted of a HIPAA-compliant institutional review board-approved retrospective review of 56 primary lung adenocarcinomas in 54 patients (24 men, 30 women; median age, 72 years; range, 54-87 years) treated with percutaneous image-guided ablation and with available genetic mutational analysis. KRAS mutation status and additional clinical and technical variables-Eastern Cooperative Oncology Group (ECOG) status, smoking history, stage at diagnosis, status (new primary or not), history of radiation, history of surgery, prior systemic treatment, modality of ablation, size of nodule, ablation margin, and presence of ground-glass appearance-were recorded and evaluated in relation to time to local recurrence, which was calculated from the time of ablation to the first radiographic evidence of recurrence. Predictors of outcome were identified by using a proportional hazards model for both univariate and multivariate analysis, with death as a competing risk. Results Technical success was 100%. Of the 56 ablated tumors, 37 (66%) were wild type for KRAS and 19 (34%) were KRAS mutants. The 1-year and 3-year cumulative incidences of recurrence were 20% and 35% for wild-type KRAS compared with 40% and 63% for KRAS mutant tumors. KRAS mutation status was a significant predictor of local recurrence at both univariate (P = .05; subdistribution hazard ratio [sHR], 2.32) and multivariate (P = .006; sHR, 3.75) analysis. At multivariate analysis, size (P = .026; sHR, 2.54) and ECOG status (P = .012; sHR, 2.23) were also independent significant predictors, whereas minimum margin (P = .066) was not. Conclusion The results of this study show that there is a relationship between KRAS mutation status and local recurrence after image-guided ablation of lung adenocarcinoma. Specifically, KRAS mutation status of the ablated lesion is a significant predictor of time to local recurrence, independent of size and margin. © RSNA, 2016.

Pneumodissection for skin protection in image-guided cryoablation of superficial musculoskeletal tumours.

PURPOSE: Pneumodissection is described as a simple method for preventing skin injury during cryoablation of superficial musculoskeletal tumours. METHODS: Superficial tumour cryoablations performed from 2009 to 2015 were retrospectively reviewed. Pneumodissection was performed in 13 patients when the shortest tumour-skin distance was less than 25 mm. Indications were pain palliation (n = 9) and local tumour control (n = 4). Patients, target tumours, technical characteristics and complications up to 60 days post ablation were reviewed. The ice ball-skin distances with and without pneumodissection were compared by a paired t-test and further assessed for association with covariates using ANCOVA. RESULTS: Technical success for ablation was 12 of 13. The mean shortest tumour-skin distance was 15.0 mm (3.2-24.5 mm). The mean thickness of pneumodissection was 9.6 mm (5.2-16.6 mm) resulting in mean elevation of skin of 3.4 mm (1.2-5.3 mm). Mean shortest ice ball-skin distance after pneumodissection was 10.5 mm (4.2-19.7 mm). No infection or systemic air embolism was noted. No intraprocedural frostbite was observed. CONCLUSION: Pneumodissection is feasible, effective and safe in protecting the skin during image-guided cryoablation of superficial tumours. KEY POINTS: • Frostbite during image-guided cryoablation of superficial tumours is commonly under-reported. • Frostbites are painful and may introduce infection into the superficial ablation zone. • Warm compress, saline and CO 2 have shortcomings in protecting the skin. • Pneumodissection is free, readily available, easy to use and safe and effective.

Adjuvant Medications That Improve Survival after Locoregional Therapy.

PURPOSE: To determine if outpatient medications taken at the time of liver tumor embolization or ablation affect survival. MATERIALS AND METHODS: A retrospective review was done of 2,032 liver tumor embolization, radioembolization, and ablation procedures performed in 1,092 patients from June 2009 to April 2016. Pathology, hepatocellular carcinoma (HCC) stage (American Joint Committee on Cancer), neuroendocrine tumor (NET) grade, initial locoregional therapy, overall survival after initial locoregional therapy, Child-Pugh score, Eastern Cooperative Oncology Group performance status, Charlson Comorbidity Index, and outpatient medications taken at the time of locoregional therapy were analyzed for each patient. Kaplan-Meier survival curves were calculated for patients taking 29 medications or medication classes (including prescription and nonprescription medications) for reasons unrelated to their primary cancer diagnosis. Kaplan-Meier curves were compared using the log-rank test. RESULTS: For patients with HCC initially treated with embolization (n = 304 patients), the following medications were associated with improved survival when taken at the time of embolization: beta-blockers (P = .0007), aspirin (P = .0008) and other nonsteroidal antiinflammatory drugs (P = .009), proton pump inhibitors (P = .004), and antivirals for hepatitis B or C (P = .01). For colorectal liver metastases initially treated with ablation (n = 172 patients), beta-blockers were associated with improved survival when taken at the time of ablation (P = .02). CONCLUSIONS: Aspirin and beta-blockers are associated with significantly improved survival when taken at the time of embolization for HCC. Aspirin was not associated with survival differences after locoregional therapy for NET or colorectal liver metastases, suggesting an HCC-specific effect.

Gene Signature Associated with Upregulation of the Wnt/ß-Catenin Signaling Pathway Predicts Tumor Response to Transarterial Embolization.

PURPOSE: To identify gene mutations in tumors undergoing transarterial embolization and explore the relationship between gene mutations and tumor response to embolization. MATERIALS AND METHODS: This was a retrospective review that included 17 patients with primary or metastatic liver tumors treated with embolization and had specimens analyzed for a 341-gene panel next-generation sequence assay. Pathologic conditions included hepatocellular, carcinoid, pancreatic neuroendocrine, melanoma, medullary thyroid, and liver acinar-cell carcinoma. Disease, procedure data, and tumor response data were collected. Dimensionality reduction was performed by using principal component analysis. A linear support vector machine was used to learn a prediction rule and identify the genes most predictive of objective tumor response (partial or complete) per modified Response Evaluation Criteria In Solid Tumors. Cross-validation was used to test the prediction on the holdout set. Permutation testing was used to determine statistical significance of prediction accuracy. Recursive feature elimination was used to identify the most predictive genes. RESULTS: At 4 months after embolization, 9 tumors showed a response and 8 did not. Using the top two principal components, prediction accuracy of the gene mutation signature was 70% (±11%), which was statistically significant (P < .05). The most predictive genes were CTNNB1, MEN1, and NCOR1: three genes associated with the Wnt/ß-catenin and hypoxia signaling pathways. CONCLUSIONS: This study identifies gene mutations in tumors treated with transarterial embolization. A gene-mutation signature obtained from the mutation data suggests that upregulation of the Wnt/ß-catenin signaling pathway may be associated with sensitivity to embolization.

Therapeutic Application of Percutaneous Peritoneovenous (Denver) Shunt in Treating Chylous Ascites in Cancer Patients.

PURPOSE: To evaluate the safety and efficacy of percutaneous peritoneovenous shunt (PPVS) placement in treating intractable chylous ascites (CA) in patients with cancer. MATERIALS AND METHODS: Data from 28 patients with refractory CA treated with PPVS from April 2001 to June 2015 were reviewed. Demographic characteristics, technical success, efficacy, laboratory values, and complications were recorded. Univariate and multivariate logistic regression analysis was performed. RESULTS: Technical success was 100%, and ascites resolved or symptoms were relieved in 92.3% (26 of 28) of patients. In 13 (46%) patients with urologic malignancies, whose ascites had resulted from retroperitoneal lymph node dissection, the ascites resolved, resulting in shunt removal within 128 days ± 84. The shunt provided palliation of symptoms in 13 of the remaining 15 patients (87%) for a mean duration of 198 days ± 214. Serum albumin levels increased significantly (21.4%) after PPVS placement from a mean of 2.98 g/dL ± 0.64 before the procedure to 3.62 g/dL ± 0.83 (P < .001). The complication rate was 37%, including shunt malfunction/occlusion (22%), venous thrombosis (7%), and subclinical disseminated intravascular coagulopathy (DIC) (7%). Smaller venous limb size (11.5 F) and the presence of peritoneal tumor were associated with a higher rate of shunt malfunction (P < .05). No patient developed overt DIC. CONCLUSIONS: PPVS can safely and effectively treat CA in patients with cancer, resulting in significant improvement in serum albumin in addition to palliation of symptoms.

Quantitative Measurements of Enhancement on Preprocedure Triphasic CT Can Predict Response of Colorectal Liver Metastases to Radioembolization.

OBJECTIVE: Colorectal liver metastases (CLM) have a variable response to radioembolization. This may be due at least partly to differences in tumor arterial perfusion. The present study examines whether quantitative measurements of enhancement on preprocedure triphasic CT can be used to predict the response of CLM to radioembolization. MATERIALS AND METHODS: We retrospectively reviewed patients with CLM treated with radioembolization who underwent pretreatment PET/CT and triphasic CT examinations and posttreatment PET/CT examinations. A total of 31 consecutive patients with 60 target tumors were included in the present study. For each tumor, we calculated the hepatic artery coefficient (HAC), portal vein coefficient (PVC), and arterial enhancement fraction (AEF) based on enhancement measurements on pretreatment triphasic CT. HAC and PVC are estimates of the hepatic artery and portal vein blood supply. AEF, which is the arterial phase enhancement divided by the portal phase enhancement, provides an estimate of the hepatic artery blood supply as a fraction of the total blood supply. For each tumor, the metabolic response to radioembolization was based on findings from the initial follow-up PET/CT scan obtained at 4-8 weeks after treatment. RESULTS: A total of 55% of CLM had a complete or partial metabolic response. Arterial phase enhancement, the HAC, and the PVC did not predict which tumors responded to radioembolization. However, the AEF was statistically significantly greater in tumors with a complete or partial metabolic response than in tumors with no metabolic response (i.e., those with stable disease or disease progression) (p = 0.038). An AEF of less than 0.4 was associated with a 40% response rate, whereas an AEF greater than 0.75 was associated with a 78% response rate. CONCLUSION: Response to radioembolization can be predicted using the AEF calculated from the preprocedure triphasic CT.

Targeted transgastric drainage of isolated pancreatic duct segments to cure persistent pancreaticocutaneous fistulas from pancreatitis.

Chronic pancreaticocutaneous fistulas can be difficult to treat. This article presents a snare-target technique for draining a nondilated pancreatic duct into the stomach, diverting pancreatic fluid away from the pancreaticocutaneous fistula to allow it to heal. Internal or internal/external transgastric pancreatic duct or fistula drains were placed in six patients. After an average of 4 months of drainage, all six patients experienced resolution of the cutaneous fistula. Two patients developed a pseudocyst but no recurrent fistula after drain removal, and the other four patients had no pseudocyst or fistula after an average 27-month follow-up (range, 6-74 mo).

Optimal imaging surveillance schedules after liver-directed therapy for hepatocellular carcinoma.

PURPOSE: To optimize surveillance schedules for the detection of recurrent hepatocellular carcinoma (HCC) after liver-directed therapy. MATERIALS AND METHODS: New methods have emerged that allow quantitative analysis and optimization of surveillance schedules for diseases with substantial rates of recurrence such as HCC. These methods were applied to 1,766 consecutive chemoembolization, radioembolization, and radiofrequency ablation procedures performed on 910 patients between 2006 and 2011. Computed tomography or magnetic resonance imaging performed just before repeat therapy was set as the time of "recurrence," which included residual and locally recurrent tumor as well as new liver tumors. Time-to-recurrence distribution was estimated by Kaplan-Meier method. Average diagnostic delay (time between recurrence and detection) was calculated for each proposed surveillance schedule using the time-to-recurrence distribution. An optimized surveillance schedule could then be derived to minimize the average diagnostic delay. RESULTS: Recurrence is 6.5 times more likely in the first year after treatment than in the second. Therefore, screening should be much more frequent in the first year. For eight time points in the first 2 years of follow-up, the optimal schedule is 2, 4, 6, 8, 11, 14, 18, and 24 months. This schedule reduces diagnostic delay compared with published schedules and is cost-effective. CONCLUSIONS: The calculated optimal surveillance schedules include shorter-interval follow-up when there is a higher probability of recurrence and longer-interval follow-up when there is a lower probability. Cost can be optimized for a specified acceptable diagnostic delay or diagnostic delay can be optimized within a specified acceptable cost.

Classification of hypervascular liver lesions based on hepatic artery and portal vein blood supply coefficients calculated from triphasic CT scans.

Perfusion CT of the liver typically involves scanning the liver at least 20 times, resulting in a large radiation dose. We developed and validated a simplified model of tumor blood supply that can be applied to standard triphasic scans and evaluated whether this can be used to distinguish benign and malignant liver lesions. Triphasic CTs of 46 malignant and 32 benign liver lesions were analyzed. For each phase, regions of interest were drawn in the arterially enhancing portion of each lesion, as well as the background liver, aorta, and portal vein. Hepatic artery and portal vein blood supply coefficients for each lesion were then calculated by expressing the enhancement curve of the lesion as a linear combination of the enhancement curves of the aorta and portal vein. Hepatocellular carcinoma (HCC) and hypervascular metastases, on average, both had increased hepatic artery coefficients compared to the background liver. Compared to HCC, benign lesions, on average, had either a greater hepatic artery coefficient (hemangioma) or a greater portal vein coefficient (focal nodular hyperplasia or transient hepatic attenuation difference). Hypervascularity with washout is a key diagnostic criterion for HCC, but it had a sensitivity of 72 % and specificity of 81 % for diagnosing malignancy in our diverse set of liver lesions. The sensitivity for malignancy was increased to 89 % by including enhancing lesions that were hypodense on all phases. The specificity for malignancy was increased to 97 % (p = 0.039) by also examining hepatic artery and portal vein blood supply coefficients, while maintaining a sensitivity of 76 %.