Harnessing the abscopal effect for gastrointestinal malignancies in the era of immunotherapy.

Gastrointestinal (GI) cancers are among the leading causes of cancer-related mortality and have traditionally been treated using a combination of surgical resection and chemoradiotherapy (CRT). While the introduction of immunotherapies over the last decade have dramatically changed the treatment landscape for some GI malignancies, including esophageal, gastric, and colorectal cancer, treatment resistance remains a major unaddressed obstacle for many patients. There has thus been emerging interest in determining the optimal treatment strategy for the delivery of immunotherapy in combination with traditional therapies. In this regard, a growing number of preclinical and clinical studies have suggested that combining radiation therapy (RT) with immunotherapy may work synergistically to improve treatment response through amplification of the abscopal effect. In this review, we discuss the rationale for RT in combination with immunotherapy. We further discuss how this knowledge may lead to a paradigm shift in the application of RT and highlight remaining issues pertaining to the delivery of combination therapy.

Dynamic Contrast-Enhanced MR Imaging Evaluation of Perfusional Changes and Ablation Zone Size after Combination Embolization and Ablation Therapy.

PURPOSE: The objectives of this study were to assess the utility of dynamic contrast-enhanced magnetic resonance (MR) imaging in quantifying parenchymal perfusional changes after embolization and to characterize the association between pharmacokinetic (PK) parameters and final microwave ablation volume. MATERIALS AND METHODS: PK parameters from dynamic contrast-enhanced MR imaging were used to quantify perfusional changes in the liver after transarterial embolization of the right or left lobe in a swine liver model (n = 5). Each animal subject subsequently underwent microwave ablation (60 W for 5 minutes) of the embolized and nonembolized liver lobes. Changes in PK parameters from dynamic contrast-enhanced MR imaging were correlated with their respective final microwave ablation volumes in each liver lobe. RESULTS: Microwave ablation volumes of embolized liver lobes were significantly larger than those of nonembolized liver lobes (28.0 mL ± 6.2 vs 15.1 mL ± 5.2, P < .001). PK perfusion parameters were significantly lower in embolized liver lobes than in nonembolized liver lobes (Ktrans = 0.69 min-1 ± 0.15 vs 1.52 min-1 ± 0.37, P < .001; kep = 0.69 min-1 ± 0.19 vs 1.54 min-1 ± 0.42, P < .001). There was a moderate but significant correlation between normalized kep and ablation volume, with each unit increase in normalized kep corresponding to a 9.8-mL decrease in ablation volume (P = .035). CONCLUSIONS: PK-derived parameters from dynamic contrast-enhanced MR imaging can be used to quantify perfusional changes after transarterial embolization and are directly inversely correlated with final ablation volume.

Percutaneous direct puncture and embolization of vascularly inaccessible abdominal visceral pseudoaneurysms: A single-center experience and literature review.

BACKGROUND: To evaluate the techniques, efficacy, and safety for treating vascularly inaccessible abdominal visceral pseudoaneurysms by direct puncture and embolization. METHODS: A retrospective study of 5 consecutive patients who underwent percutaneous direct puncture embolization for intra-abdominal pseudoaneurysms in our institution between January 2009 and December 2016. Technical aspects, success, clinical outcome, and complications were discussed. RESULTS: Four patients (80%) were men, and the mean age of all five patients was 57.2 years (range, 47-72 years). The mean diameter of the pseudoaneurysms was 2.5 cm (range, 1.9-3.4 cm). All the pseudoaneurysms were punctured under the imaging guidance of fluoroscopy, ultrasound, or computed tomography. Coils and glue were used in four of the patients, the remaining one with coil only. The mean injected glue volume was 1.5 (range, 0.8-2) mL. The overall technical and clinical success rate was 100% without major complications or mortality. CONCLUSION: Our single-center experience and the literature review demonstrate that percutaneous direct puncture embolization is feasible and effective to serve as an alternative for treating abdominal vascular pseudoaneurysms when the traditional endovascular embolization fails. In this approach, fluoroscopy is the most needed guidance technique.

Effects of irreversible electroporation on femoral nerves in a rabbit model.

INTRODUCTION: Irreversible electroporation (IRE) is a novel technique that uses a non-thermal ablation to avoid adjacent major structure injury. The aim of this study was to sequentially evaluate the effects of IRE on the femoral nerve during acute-to-delayed periods in a rabbit model. MATERIAL AND METHODS: Ultrasound-guided IRE of femoral neurovascular bundles was performed in seven rabbits. Functional and histopathologic evaluation was performed sequentially after IRE. The extent of nerve fiber affected, and the proportion of perineurial inflammation and surrounding tissue injury were recorded. RESULTS: After IRE, femoral nerve function was damaged before four weeks, but then gradually returned to normal. Perineural inflammatory cell infiltration was most severe three days after IRE (80-85%), and was normalized after eight weeks. Surrounding tissue injury was prominent at three days and one week after IRE (80-90%), and then gradually recovered. However, peripheral nerve fibers were markedly damaged at one and two weeks (80-100%). Nerve fibers then recovered and were normalized at eight weeks. CONCLUSION: Nerve tissue injury with transient functional impairment can occur after IRE. However, endoneurial and epineurial extracellular matrix were preserved with Schwann cell regeneration, which could lead to regeneration of nerve tissues within eight weeks.

North American Practice-Based Recommendations for Transjugular Intrahepatic Portosystemic Shunts in Portal Hypertension.

Complications of portal hypertension, including ascites, gastrointestinal bleeding, hepatic hydrothorax, and hepatic encephalopathy, are associated with significant morbidity and mortality. Despite few high-quality randomized controlled trials to guide therapeutic decisions, transjugular intrahepatic portosystemic shunt (TIPS) creation has emerged as a crucial therapeutic option to treat complications of portal hypertension. In North America, the decision to perform TIPS involves gastroenterologists, hepatologists, and interventional radiologists, but TIPS creation is performed by interventional radiologists. This is in contrast to other parts of the world where TIPS creation is performed primarily by hepatologists. Thus, the successful use of TIPS in North America is dependent on a multidisciplinary approach and technical expertise, so as to optimize outcomes. Recently, new procedural techniques, TIPS stent technology, and indications for TIPS have emerged. As a result, practices and outcomes vary greatly across institutions and significant knowledge gaps exist. In this consensus statement, the Advancing Liver Therapeutic Approaches group critically reviews the application of TIPS in the management of portal hypertension. Advancing Liver Therapeutic Approaches convened a multidisciplinary group of North American experts from hepatology, interventional radiology, transplant surgery, nephrology, cardiology, pulmonology, and hematology to critically review existing literature and develop practice-based recommendations for the use of TIPS in patients with any cause of portal hypertension in terms of candidate selection, procedural best practices and, post-TIPS management; and to develop areas of consensus for TIPS indications and the prevention of complications. Finally, future research directions are identified related to TIPS for the management of portal hypertension.

Consensus Guidelines for the Definition of Time-to-Event End Points in Image-guided Tumor Ablation: Results of the SIO and DATECAN Initiative.

There is currently no consensus regarding preferred clinical outcome measures following image-guided tumor ablation or clear definitions of oncologic end points. This consensus document proposes standardized definitions for a broad range of oncologic outcome measures with recommendations on how to uniformly document, analyze, and report outcomes. The initiative was coordinated by the Society of Interventional Oncology in collaboration with the Definition for the Assessment of Time-to-Event End Points in Cancer Trials, or DATECAN, group. According to predefined criteria, based on experience with clinical trials, an international panel of 62 experts convened. Recommendations were developed using the validated three-step modified Delphi consensus method. Consensus was reached on when to assess outcomes per patient, per session, or per tumor; on starting and ending time and survival time definitions; and on time-to-event end points. Although no consensus was reached on the preferred classification system to report complications, quality of life, and health economics issues, the panel did agree on using the most recent version of a validated patient-reported outcome questionnaire. This article provides a framework of key opinion leader recommendations with the intent to facilitate a clear interpretation of results and standardize worldwide communication. Widespread adoption will improve reproducibility, allow for accurate comparisons, and avoid misinterpretations in the field of interventional oncology research. Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Liddell in this issue.

Outcomes of balloon occlusion in the University of California Morbidly Adherent Placenta Registry.

BACKGROUND: Morbidly adherent placenta, also known as placenta accreta spectrum, is associated with severe maternal morbidity and mortality. Multiple adjunctive procedures have been proposed to improve outcomes, and at many institutions, interventional radiologists will play a role in assisting obstetricians in these cases. OBJECTIVE: The objective of the study was to evaluate the outcomes of women with morbidly adherent placenta who underwent cesarean hysterectomy with aortic balloon occlusion or internal iliac artery balloon occlusion catheters, compared with cesarean hysterectomy with surgical ligation of the iliac arteries, or cesarean hysterectomy without adjunctive procedures. STUDY DESIGN: A retrospective review of women with morbidly adherent placenta treated with cesarean hysterectomy was performed at 5 institutions from May 2014 to April 2018. The balloon occlusion group had either prophylactic aortic or iliac balloons placed prior to cesarean hysterectomy. Comparison groups included those who underwent internal iliac artery ligation prior to hysterectomy or a control group if they underwent cesarean hysterectomy without adjuvant procedures. Evaluated outcomes include estimated blood loss, transfusion requirements, intensive care unit admission, and adverse event rates. RESULTS: There were 171 women with morbidly adherent placenta included in the study. Twenty-eight had balloon placement prior to cesarean hysterectomy, 18 had intraoperative internal iliac artery ligation, and there were 125 control women who underwent cesarean hysterectomy without any adjunctive procedures. Compared with the women who underwent cesarean hysterectomy without adjunctive procedures, women who underwent aortic or iliac artery balloon occlusion prior to hysterectomy had significantly lower estimated blood loss (30.9% decrease, P < .001), transfusion requirements (76.8% decrease, P < .001), intensive care unit admission rates (0% vs 15.2%, P < .001), and intensive care unit stay lengths (0.0 vs 3.1 days, P < .001). Compared with women who underwent surgical ligation of the internal iliac arteries prior to hysterectomy, women who underwent aortic or iliac artery balloon occlusion prior to cesarean hysterectomy had lower estimated blood loss (54.2% decrease, P < .01), transfusion requirements (90.5% decrease, P < .001), operating room times (40.0% decrease, P < .01), intensive care unit admissions rates (0% vs 77.8%, P < .001), intensive care unit stay lengths (0.0 vs 1.4 days, P < .001), and adverse events (3.6% vs 44.4%, P < .01). CONCLUSION: Aortic and iliac artery balloon occlusion are associated with lower estimated blood loss, transfusion requirements, intensive care unit admission rates, and adverse event rates compared with women who underwent internal iliac artery ligation prior to cesarean hysterectomy or women who had no adjunctive interventions prior to cesarean hysterectomy for morbidly adherent placenta.

4D Flow MR Imaging to Improve Microwave Ablation Prediction Models: A Feasibility Study in an In Vivo Porcine Liver.

PURPOSE: To characterize the effect of hepatic vessel flow using 4-dimensional (4D) flow magnetic resonance (MR) imaging and correlate their effect on microwave ablation volumes in an in vivo non-cirrhotic porcine liver model. MATERIALS AND METHODS: Microwave ablation antennas were placed under ultrasound guidance in each liver lobe of swine (n = 3 in each animal) for a total of 9 ablations. Pre- and post-ablation 4D flow MR imaging was acquired to quantify flow changes in the hepatic vasculature. Flow measurements, along with encompassed vessel size and vessel-antenna spacing, were then correlated with final ablation volume from segmented MR images. RESULTS: The linear regression model demonstrated that the preablation measurement of encompassed hepatic vein size (ß = -0.80 ± 0.25, 95% confidence interval [CI] -1.15 to -0.22; P = .02) was significantly correlated to final ablation zone volume. The addition of hepatic vein flow rate found via 4D flow MRI (ß = -0.83 ± 0.65, 95% CI -2.50 to 0.84; P = .26), and distance from antenna to hepatic vein (ß = 0.26 ± 0.26, 95% CI -0.40 to 0.92; P = .36) improved the model accuracy but not significantly so (multivariate adjusted R2 = 0.70 vs univariate (vessel size) adjusted R2 = 0.63, P = .24). CONCLUSIONS: Hepatic vein size in an encompassed ablation zone was found to be significantly correlated with final ablation zone volume. Although the univariate 4D flow MR imaging-acquired measurements alone were not found to be statistically significant, its addition to hepatic vein size improved the accuracy of the ablation volume regression model. Pre-ablation 4D flow MR imaging of the liver may assist in prospectively optimizing thermal ablation treatment.

Transjugular Liver Biopsy: Safe Even in Patients With Severe Coagulopathies and Multiple Biopsies.

OBJECTIVES: To investigate the safety profile and diagnostic efficacy of transjugular liver biopsy (TJLB), with a focus on patients with severe coagulopathies and with multiple biopsies. METHODS: Clinical, laboratory, and demographic information was collected on 1,321 TJLBs in 932 patients (mean age 43.5 ± 23.2 years) performed between January 2009 and May 2017 to determine the diagnostic success rate and incidence of both major and minor complications in the 3-day and 30-day period post-biopsies. These outcomes were also analyzed for severely coagulopathic patients and a subgroup of patients who underwent multiple biopsies. RESULTS: The overall success rate (diagnostic yield) of the TJLB procedure was 97.7% (1,291/1,321). Overall, the major and minor complication rates were 1.0% (13/1,321) and 9.5% (126/1,321), respectively. In patients with multiple biopsies, the overall complication rate was similar to the entire study cohort, which was 10.4% (57/550). Patients were also stratified according to the platelet counts of 0-50, 51-100, 101-200, 201-300 and >300 × 10 platelets/µL. The overall complication rates were 8.0% (10/124), 11.6% (36/310), 9.9% (54/547), 11.9% (28/235), and 14.3% (11/77), respectively, and these were not statistically significant from each other. Patients were also stratified by international normalized ratio into 0-1, 1.1-2, 2.1-3, and >3. The overall complication rates of these patients were 8.0% (19/237), 11.8% (113/954), 16.3% (7/43), and 0% (0/9), respectively, and were not statistically significant from each other. DISCUSSION: TJLB is a highly efficacious, well-tolerated and safe procedure. It can be safely performed multiple times in the same patient or in critically ill, severely coagulopathic patients with no significant increase in the rate of complication while maintaining an extremely favorable diagnostic yield.

A reality check in transradial access: a single-centre comparison of transradial and transfemoral access for abdominal and peripheral intervention.

OBJECTIVES: The purpose of this study was to describe a single institution's experience with transradial access (TRA) for angiographic interventions, and to compare technical success, complication rate and radiation dose of procedures performed with TRA to those performed with transfemoral access (TFA). METHODS: A retrospective cohort study of patients undergoing peripheral interventions via TRA or TFA from 2015 to 2017 was performed. The cohort comprised 33 patients undergoing 44 procedures via TRA and 37 patients undergoing 44 procedures via TFA. Outcome measures were technical success, access-related complications, fluoroscopy time and radiation exposure. Differences at p < 0.05 were considered to be statistically significant. RESULTS: Baseline characteristics were similar between patients who had procedures via TRA versus those who had procedures via TFA, including age, sex and body mass index. Technical success was achieved in 41/44 (93.2%) of procedures performed via TRA, compared to 44/44 (100%) of procedures performed via TFA (p = 0.241). There were three access-related complications (6.8%) when TRA was performed, compared to none when TFA was performed (p = 0.241). Fluoroscopy time was longer in procedures performed with TRA compared to those performed with TFA (27.3 vs 20.4, p = 0.033). Dose area product (DAP) did not differ with access site choice (p = 0.186). CONCLUSIONS: TRA is a safe and feasible alternative to TFA for a range of peripheral interventions. However, TRA must be performed with prudence as it is not without complications and is technically challenging, leading to longer fluoroscopy time. KEY POINTS: • Transradial access (TRA) is feasible in a variety of peripheral interventions, achieving success in 93.2% of cases. • Access-related complications are comparable between transfemoral access (TFA) and TRA (p = 0.241), but prudence must be taken during TRA as it could be technically challenging. • Procedures performed with TRA tend to have longer fluoroscopy time compared to those performed with TFA (p = 0.033), but the DAPs are comparable (p = 0.186).

Single-center comparison of the efficacy and complications of arterial vascular closure devices in interventional radiology.

INTRODUCTION: Vascular closure devices (VCDs) are commonly used to achieve hemostasis of arterial access sites, but there is little comparative data on the variety of VCDs currently in clinical use. We reviewed the VCD experience at our institution to determine the safest and most effective VCD. MATERIALS AND METHODS: Retrospective analysis of 907 consecutive arterial procedures in interventional radiology from June 2012 to June 2014 was performed. Five VCDs were used: Angio-Seal (n = 478), FISH (n = 56), Mynx (n = 56), Perclose (n = 61), and Starclose (n = 68). Patients who underwent manual compression (n = 188) without use of VCDs were also studied as a comparison group. Patient demographics and pre-procedural laboratory parameters were recorded. The technical success rate for achievement of hemostasis and complication rates were noted. RESULTS: Complete hemostasis rate (aka technical success rate) was 93.5% for Angio-Seal, 83.9% for FISH, 53.6% for Mynx, 73.7% for Perclose, 76.5% for Starclose, and 91.5% for manual compression. The differences among the devices were statistically significant (p<0.001). Fourteen major complications (1.5%) were encountered: nine with Angio-Seal (1.9%), one with Mynx (1.8%), one with Starclose (1.5%), and three with manual compression (1.6%); these differences were not statistically significant. Of the demographic and laboratory parameters studied, none were significantly correlated with hemostasis failure or development of complications. CONCLUSIONS: In our single-center institutional experience, Angio-Seal is the device with the best technical success rate. Major complications of VCDs were rare, with no statistically significant difference between devices.

Yttrium-90 Radioembolization for Metastatic Colorectal Cancer: Outcomes by Number of Lines of Therapy.

Metastatic colorectal cancer represents the most common liver malignancy, and imparts a very poor prognosis for those who develop this disease. Unlike primary liver tumors such as hepatocellular carcinoma, which largely develops in patients with underlying cirrhosis, most metastatic liver tumor patients have normal underlying liver function. Owing to this, most will succumb to tumoral replacement of the liver rather than from underlying liver dysfunction. Radioembolization represents a treatment modality that can be used in multiple fashions to treat one or both lobes of the liver. Techniques depend on whether the procedure is used as first-line, second/third-line, or as salvage therapy. Outcomes and complications of radioembolization are presented in this article, as well as background information on colorectal cancer and systemic therapies.

Age-related Morbidity and Mortality After Transjugular Intrahepatic Portosystemic Shunts.

AIM: To compare age-related morbidity and mortality after transjugular intrahepatic portosystemic shunts (TIPS). METHODS: We performed a retrospective chart review of patients who underwent TIPS at the University of California Los Angeles Medical Center between 2008 to 2014. Elderly patients (65 y and older) were matched with nonelderly patients (controls, below 65 y) by model for end-stage liver disease (MELD) score (±3), indication for TIPS (refractory ascites vs. variceal bleeding), serum sodium level (±5), in a ratio of 1:1. Endpoints measures were hospital stay post-TIPS, rifaximin, or lactulose use, TIPS failure at 30 days, readmission at 90 days, MELD at 90 days, and mortality at 90 days. RESULTS: A total of 30 patient matches were included in this study: 30 control and 30 elderly patients. The median [interquartile (IQR)] MELD scores for controls and elderly were 11 (9, 13.8) for the controls and 11.5 (9, 14.8) for elderly patients (P=0.139). There were no significant differences in serum sodium and indication for TIPS. Thirty and 90-day follow-up laboratory test results were also similar between elderly and control patients. Event-free survival at 90 days was similar between controls and elderly patients [odds ratio (OR), 0.86; 95% confidence interval (CI), 0.3-2.5; P>0.05]. There was a trend toward greater hospitalization (OR, 1.76; 95% CI, 0.52-5.95; P=0.546) and mortality (OR, 3.3; 95% CI, 0.3-14.01; P=0.182). CONCLUSIONS: The results of this study suggest event-free survival is similar between nonelderly and elderly patients. Although statistically significant, there is a tendency toward greater mortality and hospitalization in the elderly.

Renal Denervation: A Novel Therapy at the Crossroads of Imaging, Intervention, and Innovation.

Hypertension (HTN) is one of the most significant medical problems affecting society today. The estimated 76 million Americans with hypertension represent a significant public health problem, contributing to cardiac, vascular, renal, and neurovascular morbidity and mortality. HTN is the most common indication for lifelong pharmacologic treatment, mainly because of the incontrovertible reductions in cardiovascular events with blood pressure (BP) reduction and control. However, despite the availability and potency of multiple different antihypertensive drugs, up to half of American patients have BPs above the recommended target. Given the overwhelming evidence of both the cost to society of HTN and the benefits that are accrued from improved BP control, alternatives or adjuncts to current management options have been sought to aid in treatment of these patients. Over the past few years, a device-based approach involving modulation of the autonomic nervous system, termed renal denervation, has evolved to meet this challenge. With early trials showing startlingly good results, with few side effects, multiple devices were fast-tracked to clinical trials and hence to the market. However, larger trials have shone an unfavorable light on the field, with concerns about the short- and long-term effectiveness, diverting attention back to operational and procedural details. Despite this, image-guided manipulation of the sympathetic nervous system to treat HTN remains a fertile area of laboratory and clinical research.

Radiation-Induced Cataractogenesis: A Critical Literature Review for the Interventional Radiologist.

Extensive research supports an association between radiation exposure and cataractogenesis. New data suggests that radiation-induced cataracts may form stochastically, without a threshold and at low radiation doses. We first review data linking cataractogenesis with interventional work. We then analyze the lens dose typical of various procedures, factors modulating dose, and predicted annual dosages. We conclude by critically evaluating the literature describing techniques for lens protection, finding that leaded eyeglasses may offer inadequate protection and exploring the available data on alternative strategies for cataract prevention.

Image-guided high-dose-rate brachytherapy: preliminary outcomes and toxicity of a joint interventional radiology and radiation oncology technique for achieving local control in challenging cases.

PURPOSE: To determine the ability of image-guided high-dose-rate brachytherapy (IG-HDR) to provide local control (LC) of lesions in non-traditional locations for patients with heavily pre-treated malignancies. MATERIAL AND METHODS: This retrospective series included 18 patients treated between 2012 and 2014 with IG-HDR, either in combination with external beam radiotherapy (EBRT; n = 9) or as monotherapy (n = 9). Lesions were located in the pelvis (n = 5), extremity (n = 2), abdomen/retroperitoneum (n = 9), and head/neck (n = 2). All cases were performed in conjunction between interventional radiology and radiation oncology. Toxicity was graded based on CTCAE v4.0 and local failure was determined by RECIST criteria. Kaplan-Meier analysis was performed for LC and overall survival. RESULTS: The median follow-up was 11.9 months. Two patients had localized disease at presentation; the remainder had recurrent and/or metastatic disease. Seven patients had prior EBRT, with a median equivalent dose in 2 Gy fractions (EQD2) of 47.0 Gy. The median total EQD2s were 34 Gy and 60.9 Gy for patients treated with monotherapy or combination therapy, respectively. Image-guided high-dose rate brachytherapy was delivered in one to six fractions. Six patients had local failures at a median interval of 5.27 months with a one-year LC rate of 59.3% and a one-year overall survival of 40.7%. Six patients died from their disease at a median interval of 6.85 months from the end of treatment. There were no grade ≥ 3 acute toxicities but two patients had serious long term toxicities. CONCLUSIONS: We demonstrate a good one year LC rate of nearly 60%, and a favorable toxicity profile when utilizing IG-HDR to deliver high doses of radiation with high precision into targets not readily accessible by other forms of local therapy. These preliminary results suggest that further studies utilizing this approach may be considered for patients with difficult to access lesions that require LC.