Double-Balloon Catheter-Mediated Transarterial Chemotherapy Delivery in a Swine Model: A Mechanism Recruiting the Vasa Vasorum for Localized Therapies

PURPOSE

Treatment of hypovascular tumors, such as pancreatic adenocarcinoma, is challenging owing to inefficient drug delivery. This report examines the potential mechanism of localized drug delivery via transarterial microperfusion (TAMP) using a proprietary adjustable double-balloon occlusion catheter in a porcine model.

MATERIALS AND METHODS

Adult Yorkshire swine (N = 21) were used in the Institutional Animal Care & Use Committee-approved protocols. The RC-120 catheter (RenovoRx, Los Altos, California) was positioned into visceral, femoral, and pulmonary arteries with infusion of methylene blue dye, gemcitabine, or gold nanoparticles. Transmural delivery was compared under double-balloon occlusion with and without side-branch exclusion, single-balloon occlusion, and intravenous delivery. Intra-arterial pressure and vascular histologic changes were assessed.

RESULTS

Infusion with double-balloon occlusion and side-branch exclusion provided increased intra-arterial pressure in the isolated segment and enhanced perivascular infusate penetration with minimal vascular injury. Infusates were predominantly found in the vasa vasorum by electron microscopy.

CONCLUSIONS

TAMP enhanced transmural passage mediated by localized increase in arterial pressure via vasa vasorum.

ACR Appropriateness Criteria® Lower Extremity Chronic Venous Disease

Lower extremity venous insufficiency is a chronic medical condition resulting from primary valvular incompetence or, less commonly, prior deep venous thrombosis or extrinsic venous obstruction. Lower extremity chronic venous disease has a high prevalence with a related socioeconomic burden. In the United States, over 11 million males and 22 million females 40 to 80 years of age have varicose veins, with over 2 million adults having advanced chronic venous disease. The high cost to the health care system is related to the recurrent nature of venous ulcerative disease, with total treatment costs estimated >$2.5 billion per year in the United States, with at least 20,556 individuals with newly diagnosed venous ulcers yearly. Various diagnostic and treatment strategies are in place for lower extremity chronic venous disease and are discussed in this document. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Coaxial Placement of Balloon-Expandable and Self-Expanding Stents: Impact on Crush Resistance and Luminal Recovery in a Benchtop Model

During endovascular interventions, coaxial deployment of stents may be required to preserve luminal gain. This study characterized in vitro the effect on crush resistance and postcompression recovery when 316L stainless steel balloon-expandable (BE) and laser-cut nitinol self-expanding (SE) venous stents were deployed coaxially. Various stent configurations were parallel-plate compressed from a fully expanded state to 50% diameter reduction (Criterion, Model 42; MTS, Eden Prairie, Minnesota) in a 37 °C ± 1 water bath. Coaxial deployments of SE stent inside BE stent and BE stent inside SE stent demonstrated higher crush resistances compared with each stent individually or their mathematical summation (analysis of variance P < .0001; pairwise comparison P < .01). The configuration of SE stent inside BE stent showed higher postcompression luminal recovery at 48.7% compared with that of BE stent inside SE stent at 27.5% (P = .0001). Coaxial deployment of SE stent inside BE stent may improve crush resistance and luminal recovery after compression in the appropriate clinical context.

Updated Management of Colorectal Cancer Liver Metastases: Scientific Advances Driving Modern Therapeutic Innovations

Colorectal cancer is the second leading cause of cancer-related deaths in the United States and accounts for an estimated 1 million deaths annually worldwide. The liver is the most common site of metastatic spread from colorectal cancer, significantly driving both morbidity and mortality. Although remarkable advances have been made in recent years in the management for patients with colorectal cancer liver metastases, significant challenges remain in early detection, prevention of progression and recurrence, and in the development of more effective therapeutics. In 2017, our group held a multidisciplinary state-of-the-science symposium to discuss the rapidly evolving clinical and scientific advances in the field of colorectal liver metastases, including novel early detection and prognostic liquid biomarkers, identification of high-risk cohorts, advances in tumor-immune therapy, and different regional and systemic therapeutic strategies. Since that time, there have been scientific discoveries translating into therapeutic innovations addressing the current management challenges. These innovations are currently reshaping the treatment paradigms and spurring further scientific discovery. Herein, we present an updated discussion of both the scientific and clinical advances and future directions in the management of colorectal liver metastases, including adoptive T-cell therapies, novel blood-based biomarkers, and the role of the tumor microbiome. In addition, we provide a comprehensive overview detailing the role of modern multidisciplinary clinical approaches used in the management of patients with colorectal liver metastases, including considerations toward specific molecular tumor profiles identified on next generation sequencing, as well as quality of life implications for these innovative treatments.

Double-Barrel Nitinol Stent Placement for Iliocaval Reconstruction: The Effect of Deployment Sequence and Direction on Final Configuration

Double-barrel stent placement across the iliocaval confluence is commonly used for the treatment of chronic bilateral iliocaval occlusion. The difference in the deployment outcomes of synchronous parallel stent deployment versus asynchronous or antiparallel deployment and the underlying stent interactions are poorly understood. In this study, 3 strategies of double-barrel nitinol self-expanding stent deployment across the iliocaval confluence (synchronous parallel, asynchronous parallel, and synchronous antiparallel) were contrasted in vivo in 3 swine followed by assessment of the explanted stent construct. Synchronous parallel stent deployment achieved a desired double-barrel configuration. The asynchronous parallel and antiparallel deployment strategies both resulted in a crushed stent despite subsequent simultaneous balloon angioplasty. These animal model results suggested that in patients who undergo double-barrel iliocaval reconstruction, synchronous parallel stent deployment may provide the desired stent conformation and increase the chance for clinical success.

Uterine Fibroid Embolization or Myomectomy: How Much Marketing Is Enough? Comparative Analysis of Public Search Trends in Google and Medical Publications in PubMed

To compare public popularity and volume of scientific publications regarding uterine fibroid embolization (UFE) and myomectomy. Google Trends and PubMed data were queried to assess temporal variations in online public search volumes and number of research publications for UFE and myomectomy. Time series analysis was used to identify meaningful temporal trends and forecast a future trend. Compared with UFE, myomectomy had significantly higher volumes of public online search and research publications, with an increasing trend over time (P < .0001). The forecasting models predicted a continuing increase in both public search volumes and number of research publications for myomectomy and static future trends in these metrics for UFE. This study signals significantly lower public popularity and research efforts for UFE compared with myomectomy for uterine fibroids. More effective marketing strategies and further research support will be needed to fill this gap.

The multidisciplinary management of cholangiocarcinoma

Cholangiocarcinoma is a lethal malignancy of the biliary epithelium that can arise anywhere along the biliary tract. Surgical resection confers the greatest likelihood of long-term survivability. However, its insidious onset, difficult diagnostics, and resultant advanced presentation render the majority of patients unresectable, highlighting the importance of early detection with novel biomarkers. Developing liver-directed therapies and emerging targeted therapeutics may offer improved survivability for patients with unresectable or advanced disease. In this article, the authors review the current multidisciplinary standards of care in resectable and unresectable cholangiocarcinoma, with an emphasis on novel biomarkers for early detection and nonsurgical locoregional therapy options.

An Advanced Thermal Decomposition Method to Produce Magnetic Nanoparticles with Ultrahigh Heating Efficiency for Systemic Magnetic Hyperthermia

Due to the limited heating efficiency of available magnetic nanoparticles, it is difficult to achieve therapeutic temperatures above 44 °C in relatively inaccessible tumors during magnetic hyperthermia following systemic administration of nanoparticles at clinical dosage (≤10 mg kg-1 ). To address this, a method for the preparation of magnetic nanoparticles with ultrahigh heating capacity in the presence of an alternating magnetic field (AMF) is presented. The low nitrogen flow rate of 10 mL min-1 during the thermal decomposition reaction results in cobalt-doped nanoparticles with a magnetite (Fe3 O4 ) core and a maghemite (γ-Fe2 O3 ) shell that exhibit the highest intrinsic loss power reported to date of 47.5 nH m2 kg-1 . The heating efficiency of these nanoparticles correlates positively with increasing shell thickness, which can be controlled by the flow rate of nitrogen. Intravenous injection of nanoparticles at a low dose of 4 mg kg-1 elevates intratumoral temperatures to 50 °C in mice-bearing subcutaneous and metastatic cancer grafts during exposure to AMF. This approach can also be applied to the synthesis of other metal-doped nanoparticles with core-shell structures. Consequently, this method can potentially be used for the development of novel nanoparticles with high heating performance, further advancing systemic magnetic hyperthermia for cancer treatment.

Coagulopathy and hemostasis management in patients undergoing liver transplantation: Defining a dynamic spectrum across phases of care

Patients with acute and chronic liver disease present with a wide range of disease states and severity that may require liver transplantation (LT). Physiologic alterations occur that are dynamic throughout all phases of perioperative care, creating complex management scenarios that necessitate multidisciplinary clinical care. Specifically, alterations in hemostasis in liver disease can be pronounced and evolve with disease progression over time. Recent studies and society guidance address this emerging paradigm and offer recommendations to assist with hemostatic management in patients with liver disease. However, patients undergoing LT are unique and diverse, often with unstable disease that requires specialized approaches. Our aim is to provide a focused review of hemostatic management of the LT patient, distinguish unique aspects of the three main phases of care (before LT, perioperative, and after LT), and identify knowledge gaps and critical areas of future research.

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.

Targeted Nanoparticles with High Heating Efficiency for the Treatment of Endometriosis with Systemically Delivered Magnetic Hyperthermia

Endometriosis is a devastating disease in which endometrial-like tissue forms lesions outside the uterus. It causes infertility and severe pelvic pain in ≈176 million women worldwide, and there is currently no cure for this disease. Magnetic hyperthermia could potentially eliminate widespread endometriotic lesions but has not previously been considered for treatment because conventional magnetic nanoparticles have relatively low heating efficiency and can only provide ablation temperatures (>46 °C) following direct intralesional injection. This study is the first to describe nanoparticles that enable systemically delivered magnetic hyperthermia for endometriosis treatment. When subjected to an alternating magnetic field (AMF), these hexagonal iron-oxide nanoparticles exhibit extraordinary heating efficiency that is 6.4× greater than their spherical counterparts. Modifying nanoparticles with a peptide targeted to vascular endothelial growth factor receptor 2 (VEGFR-2) enhances their endometriosis specificity. Studies in mice bearing transplants of macaque endometriotic tissue reveal that, following intravenous injection at a low dose (3 mg per kg), these nanoparticles efficiently accumulate in endometriotic lesions, selectively elevate intralesional temperature above 50 °C upon exposure to external AMF, and completely eradicate them with a single treatment. These nanoparticles also demonstrate promising potential as magnetic resonance imaging (MRI) contrast agents for precise detection of endometriotic tissue before AMF application.

Impact of Postthrombotic Vein Wall Biomechanics on Luminal Flow during Venous Angioplasty and Stent Placement: Computational Modeling Results

This study characterized the impact of vein wall biomechanics on inflow diameter and luminal flow during venous angioplasty and stent placement, using postthrombotic and healthy biomechanical properties from an ovine venous stenosis and thrombosis model. Finite element analysis demonstrated more pronounced inflow channel narrowing in the postthrombotic vein compared with the healthy control vein during angioplasty and stent placement (relative inflow diameter reduction of 42% versus 13%, P < .0001). Computational fluid dynamics modeling showed increased relative areas of low wall shear rate in the postthrombotic vein compared with the normal vein (0.46 vs 0.24 for shear rate < 50 s^-1; 0.13 vs 0.07 for shear rate < 15 s^-1; P < .05), with flow stagnation and recirculation. Since inflow narrowing and low wall shear rate are associated with in-stent restenosis and reintervention, these computational results based on experimentally obtained biomechanical values highlight the significance of postthrombotic venous properties in optimizing venous intervention outcomes.

Bridge-to-transplant stereotactic body radiation therapy in patients with hepatocellular carcinoma and advanced cirrhosis

TPS496

Background: Liver cancer is the third most common cause of cancer related death worldwide, and hepatocellular carcinoma (HCC) accounts for 90% of all primary liver cancers, with pre-existing cirrhosis being a very strong risk factor for HCC development. Liver transplantation (LTx) is the best treatment for patients with HCC and advanced cirrhosis as both conditions can be very effectively treated at once. As LTx wait-lists can be many months, liver-directed therapies (LDT), including stereotactic body radiation therapy (SBRT) to one or few lesions are essential as oncologic temporizing measures to bridge patients to LTx and prevent progression outside of LTx criteria. However, due to the fear of further hepatic decompensation, many patients with advanced cirrhosis are excluded from receiving LDT. Rather, recent studies suggest that SBRT be of safe and practical use in this fragile patient population with advanced cirrhosis and HCC, and thereby reduce the rate of transplantation drop-out. This pilot prospective study will assess the feasibility, safety and efficacy of bridge-to-transplantation SBRT for patients with advanced cirrhosis and HCC. Methods: Patients with non-metastatic and unresectable HCC and Child-Pugh (CP)-B8 or worse cirrhosis who are within Milan criteria (one tumor ≤ 5 cm in diameter or no more than 3 tumors each ≤ 3 cm in diameter) and have been listed or recommended to be listed for liver transplantation will be eligible for participation. Eligible participants will undergo SBRT consisting of 40 Gy to be given in 5 fractions every other day to the only or largest lesion, provided that criteria for normal organ constraints are met. In cases where normal organ constraints are not met, the dose will be iteratively de-escalated to two dose levels (35 Gy in 5 fractions, then 30 Gy in 5 fractions). If normal organ constraints are unable to be met at 30 Gy in 5 fractions, the participant will be considered ineligible for SBRT and considered a screen failure. The primary endpoint is the proportion of participants who are transplanted or with localized disease control that meets Milan criteria within a year of SBRT. Secondary endpoints will include localized control rate (mRECIST), incidence of intra- or extra-hepatic progressive disease (mRECIST), overall survival, incidence of liver toxicity per CTCAE v5.0, incidence of non-classical radiation-induced liver disease (defined as CTCAE grade 4 AST/ALT elevation or an increase in CP score of ≥ 2 within 3 months of SBRT) and quality of life scores per QLQ-C30 and FACT-Hep questionnaires. The study is open, aiming to enroll 15 patients with 8 patients enrolled at time of submission. Clinical trial information: NCT03812289.

Endovascular Venous Stenosis and Thrombosis Large Animal Model: angiographic, histological, and biomechanical characterization

PURPOSE

Characterize an ovine endovascular radiofrequency ablation based venous stenosis and thrombosis model for studying venous biomechanics and response to intervention.

MATERIALS AND METHODS

Unilateral short-segment (n= 2) or long-segment (n = 6) iliac vein stenoses were created in eight adult sheep using an endovenous radiofrequency (RF) ablation technique. Angiographic assessment was performed at baseline, immediately after venous stenosis creation, and after 2-week (n = 6) or 3-month (n = 2) survival. Stenosed iliac veins and contralateral healthy controls were harvested for histological and biomechanical assessment.

RESULTS

At follow-up, the short-segment RF ablation group showed stable stenosis without occlusion. The long-segment group showed complete venous occlusion/thrombosis with formation of collateral veins. Stenosed veins showed significant wall thickening (0.28 mm vs 0.16 mm; p = 0.0175) and confluent collagen deposition compared to healthy controls. Subacute non-adherent thrombi were apparent at 2 weeks, which were replaced by fibrous luminal obliteration with channels of recanalization at 3 months. Stenosed veins demonstrated increased longitudinal stiffness (448.5 ± 5.4 kPa vs. 314.6 ± 1.5 kPa, p < 0.0001) and decreased circumferential stiffness (140.8 ± 2.6 kPa vs. 246.0 ± 1.6 kPa, p < 0.0001) compared to healthy controls.

CONCLUSION

Endovenous radiofrequency ablation is a reliable technique for creating venous stenosis and thrombosis in a large animal model with histological and biomechanical attributes similar to those seen in humans. This platform can facilitate understanding of venous biomechanics and testing of venous specific devices and interventions.

Percutaneous Therapies for Hepatocellular Carcinoma: Evolution of Liver Directed Therapies

Percutaneous ablation is a mainstay of treatment for early stage, unresectable hepatocellular carcinoma (HCC). Recent advances in technology have created multiple ablative modalities for treatment of this common malignancy. The purpose of this review is to familiarize readers with the technical and clinical aspects of both existing and emerging percutaneous treatment options for HCC.

Lateral tilt during IVC filter placement does not predict the need for advanced filter retrieval techniques

PURPOSE

We aimed to determine if lateral inferior vena cava (IVC) filter tilt at placement predicts the need for subsequent advanced retrieval techniques.

METHODS

A retrospective chart review was performed of all Gunther Tulip IVC filter placements with subsequent retrievals between February 2015 and October 2017. Chart and imaging review was performed for patient, filter placement, and filter retrieval demographics/characteristics. Degree of agreement between two measurement sets was evaluated with the intraclass correlation (ICC) analysis. Categorical variables were compared with chi-square or Fisher exact test, as appropriate. Kendall rank correlation was used to measure correlation between categorical variables.

RESULTS

There was poor agreement between filter tilt angle at the time of placement and retrieval (ICC coefficient, 0.54). Mean difference ± standard deviation between tilt angle at the time of placement and retrieval was 4.6°±4.3° (p = 0.35). Among patient- or procedure-related factors, a common femoral vein access on placement (regression coefficient, -2.90; p = 0.039) was associated with a lower difference between placement and retrieval filter tilt angles compared to internal jugular vein access. Higher filter tilt angle measured at the time of retrieval (OR: 1.19, p = 0.025), hook embedment (OR: 77.3, p < 0.001), and a longer dwell time (OR: 1.25, p = 0.002) were associated with the need for advanced retrieval techniques. However, in univariate and multivariate analysis filter tilt angle at the time of placement was not associated with the subsequent need for advanced retrieval technique (p = 0.16).

CONCLUSION

Lateral tilt at the time of placement is poorly associated with lateral tilt at the time of retrieval and does not correlate with the need for advanced retrieval technique.

Splenic trauma: endovascular treatment approach

The spleen is a commonly injured organ in blunt abdominal trauma. Splenic preservation, however, is important for immune function and prevention of overwhelming infection from encapsulated organisms. Splenic artery embolization (SAE) for high-grade splenic injury has, therefore, increasingly become an important component of non-operative management (NOM). SAE decreases the blood pressure to the spleen to allow healing, but preserves splenic perfusion via robust collateral pathways. SAE can be performed proximally in the main splenic artery, more distally in specific injured branches, or a combination of both proximal and distal embolization. No definitive evidence from available data supports benefits of one strategy over the other. Particles, coils and vascular plugs are the major embolic agents used. Incorporation of SAE in the management of blunt splenic trauma has significantly improved success rates of NOM and spleen salvage. Failure rates generally increase with higher injury severity grades; however, current management results in overall spleen salvage rates of over 85%. Complication rates are low, and primarily consist of rebleeding, parenchymal infarction or abscess. Splenic immune function is felt to be preserved after embolization with no guidelines for prophylactic vaccination against encapsulated bacteria; however, a complete understanding of post-embolization immune changes remains an area in need of further investigation. This review describes the history of SAE from its inception to its current role and indications in the management of splenic trauma. The endovascular approach, technical details, and outcomes are described with relevant examples. SAE is has become an important part of a multidisciplinary strategy for management of complex trauma patients.

ACR Appropriateness Criteria® Radiologic Management of Lower Gastrointestinal Tract Bleeding: 2021 Update

Diverticulosis remains the commonest cause for acute lower gastrointestinal tract bleeding (GIB). Conservative management is initially sufficient for most patients, followed by elective diagnostic tests. However, if acute lower GIB persists, it can be investigated with colonoscopy, CT angiography (CTA), or red blood cell (RBC) scan. Colonoscopy can identify the site and cause of bleeding and provide effective treatment. CTA is a noninvasive diagnostic tool that is better tolerated by patients, can identify actively bleeding site or a potential bleeding lesion in vast majority of patients. RBC scan can identify intermittent bleeding, and with single-photon emission computed tomography, can more accurately localize it to a small segment of bowel. If patients are hemodynamically unstable, CTA and transcatheter arteriography/embolization can be performed. Colonoscopy can also be considered in these patients if rapid bowel preparation is feasible. Transcatheter arteriography has a low rate of major complications; however, targeted transcatheter embolization is only feasible if extravasation is seen, which is more likely in hemodynamically unstable patients. If bleeding site has been previously localized but the intervention by colonoscopy and transcatheter embolization have failed to achieve hemostasis, surgery may be required. Among patients with obscure (nonlocalized) recurrent bleeding, capsule endoscopy and CT enterography can be considered to identify culprit mucosal lesion(s). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

A novel multimodal nanoplatform for targeting tumor necrosis

Peri-necrotic tumor regions have been found to be a source of cancer stem cells (CSC), important in tumor recurrence. Necrotic and peri-necrotic tumor zones have poor vascular supply, limiting effective exposure to systemically administered therapeutics. Therefore, there is a critical need to develop agents that can effectively target these relatively protected tumor areas. We have developed a multi-property nanoplatform with necrosis avidity, fluorescence imaging and X-ray tracking capabilities to evaluate its feasibility for therapeutic drug delivery. The developed nanoparticle consists of three elements: poly(ethylene glycol)-block-poly(ε-caprolactone) as the biodegradable carrier; hypericin as a natural compound with fluorescence and necrosis avidity; and gold nanoparticles for X-ray tracking. This reproducible nanoparticle has a hydrodynamic size of 103.9 ± 1.7 nm with a uniform spherical morphology (polydispersity index = 0.12). The nanoparticle shows safety with systemic administration and a stable 30 day profile. Intravenous nanoparticle injection into a subcutaneous tumor-bearing mouse and intra-arterial nanoparticle injection into rabbits bearing VX2 orthotopic liver tumors resulted in fluorescence and X-ray attenuation within the tumors. In addition, ex vivo and histological analysis confirmed the accumulation of hypericin and gold in areas of necrosis and peri-necrosis. This nanoplatform, therefore, has the potential to enhance putative therapeutic drug delivery to necrotic and peri-necrotic areas, and may also have an application for monitoring early response to anti-tumor therapies.

Au-Hyp-NP developed by encapsulation of gold and hypericin into PEG-PCL nanoplatform for fluorescence and X-ray tracking with tumor necrosis targeting.

Lower-Extremity Edema Is Common after Transjugular Intrahepatic Portosystemic Shunt Creation and Is Associated with Lower Survival: A Two-Institution Study

Background Transjugular intrahepatic portosystemic shunt (TIPS) creation is an accepted treatment of portal hypertension. Lower-extremity edema (LEE) is an underreported complication of TIPS creation. Purpose To assess the epidemiologic findings of LEE after TIPS creation and their association with patient survival. Materials and Methods The medical records of patients who underwent TIPS creation between January 2003 and April 2019 at Oregon Health and Science University and patients who underwent TIPS creation between January 2006 and December 2016 at University of Minnesota were retrospectively reviewed. Clinical, laboratory, and technical parameters, development and outcome of edema, and survival data were collected. LEE was defined as new-onset or worsened edema up to 1 year after TIPS creation. Cardiac ventricular function was evaluated with transthoracic echocardiography. Risk factors for LEE were evaluated with logistic regression analysis, and critical P values were additionally assessed by using the false discovery rate. Survival curves were compared by using the log-rank test. Results Three hundred thirty-four patients were included (mean age, 55 years ± 11 [standard deviation]; 208 men). TIPS creation was primarily performed for ascites (159 of 334 patients, 48%), gastrointestinal bleeding (127 of 334 patients, 38%), or a combination of bleeding and ascites (38 of 334 patients, 11%). One hundred seventy of the 334 patients (51%) developed LEE (new onset, 120; worsened edema, 50). Three of 170 patients (2%) had abnormal left ventricular ejection fraction. Multivariable analysis showed TIPS creation for ascites (odds ratio, 1.7; 95% CI: 1.04, 2.7; P = .03) and hepatic hydrothorax (odds ratio, 2.2; 95% CI: 1.1, 4.2; P = .02) was likely associated with LEE; however, it did not reach significance at a critical P value of .009. Among 164 patients with data on the outcome of LEE, LEE eventually improved in 94 (57%). The median survival of patients with LEE was lower than that of patients without LEE (38 months vs 71 months, respectively; P = .02). Conclusion Lower-extremity edema developed in more than 50% of study patients who underwent transjugular intrahepatic portosystemic shunt (TIPS) creation, regardless of left ventricular function. There was suggestion that TIPS creation for ascites might be an underlying risk factor. Lower-extremity edema portends worse survival. © RSNA, 2020 Online supplemental material is available for this article.

Diagnostic and Interventional Radiology Case Volume and Education in the Age of Pandemics: Impact Analysis and Potential Future Directions

RATIONALE AND OBJECTIVES

To assess the immediate impact of the COVID-19 pandemic on Diagnostic and Interventional Radiology education, and to propose measures to preserve and augment trainee education during future crises.

MATERIALS AND METHODS

Diagnostic Radiology (DR) studies and Interventional Radiology (IR) procedures at a single tertiary-care teaching institution between 2015 and 2020 were reviewed. DR was divided by section: body, cardiothoracic, musculoskeletal (MSK), neuroradiology, nuclear medicine, pediatrics, and women's imaging. IR was divided by procedural types: arterial, venous, lymphatic, core, neuro, pediatrics, dialysis, cancer embolization or ablation, noncancer embolization, portal hypertension, and miscellaneous. Impact on didactic education was also assessed. ANOVA, t test, and multiple comparison correction were used for analysis.

RESULTS

DR and IR caseloads decreased significantly in April 2020 compared to April of the prior 5 years (both p < 0.0001). Case volumes were reduced in body (49.2%, p < 0.01), MSK (54.2%, p < 0.05), neuro (39.3%, p < 0.05), and women's imaging (75.5%, p < 0.05) in DR, and in arterial (62.6%, p < 0.01), neuro IR (57.6%, p < 0.01) and core IR (42.6%, p < 0.05) in IR. IR trainee average caseload in April 2020 decreased 51.9% compared to April of the prior 5 years (p < 0.01). Utilization of online learning increased in April. Trainees saw significant increases in overall DR didactics (31.3%, p = 0.02) and no reduction in IR didactics, all online. Twelve major national and international DR and IR meetings were canceled or postponed between March and July.

CONCLUSION

Decreases in caseload and widespread cancellation of conferences have had significant impact on DR/IR training during COVID-19 restrictions. Remote learning technologies with annotated case recording, boards-style case reviews, procedural simulation and narrated live cases as well as online lectures and virtual journal clubs increased during this time. Whether remote learning can mitigate lost opportunities from in-person interactions remains uncertain. Optimizing these strategies will be important for potential future restricted learning paradigms and can also be extrapolated to augment trainee education during unrestricted times.

Transjugular Intrahepatic Portosystemic Shunt Creation Using a Radiofrequency Wire: Prospective Clinical Safety and Feasibility Trial in Cirrhosis

PURPOSE

To assess the safety and feasibility of using a radiofrequency (RF) wire for portosystemic shunt creation.

MATERIALS AND METHODS

Ten patients undergoing elective creation of a transjugular intrahepatic portosystemic shunt (TIPS) or a direct intrahepatic portosystemic shunt (DIPS) were prospectively enrolled. Primary outcomes were the safety and feasibility of RF wire used for the creation of TIPS and DIPS. Median age was 66.5 ± 6.1 years. Causes of liver disease included alcohol (n = 5), nonalcoholic steatohepatitis (n = 2), hepatitis C virus (n = 1), primary biliary cirrhosis (n = 1), autoimmune hepatitis (n = 1). The median score for model for end-stage liver disease was 11 ± 4.3. The Rosch-Uchida TIPS set was used with intravascular ultrasonography guidance in all cases. A 0.035-inch RF wire was used in lieu of the trocar needle through the 5-F TIPS set catheter to create a track between the hepatic vein and the portal vein. All shunts were created using stent grafts.

RESULTS

Technical success rate was 100%. In 7 of 10 patients, portal vein access was achieved with a single pass. A DIPS was created in 2 patients based on anatomic favorability. Median fluoroscopy time was 13.3 ± 3.8 min, and median total procedure time was 102 ± 19 min. The wire passed through parenchyma without subjective deflection. There was 1 case of extracapsular puncture with no clinical consequence. The RF wire was too stiff to curve into the main portal vein, requiring wire exchange in all but 1 case. Mean portosystemic gradient decreased from 13.9 ± 3.3 to 5.9 ± 2.1 mm Hg. No immediate complications were encountered. Shunt patency was 100% at 30 days.

CONCLUSIONS

Creation of TIPS and DIPS using an RF wire was safe and feasible, enabling creation of an intrahepatic track without subjective deflection in cirrhotic patients.

Venous Biomechanics of Angioplasty and Stent Placement: Implications of the Poisson Effect

PURPOSE

To characterize the Poisson effect in response to angioplasty and stent placement in veins and identify potential implications for guiding future venous-specific device design.

MATERIALS AND METHODS

In vivo angioplasty and stent placement were performed in 3 adult swine by using an established venous stenosis model. Iron particle endothelium labeling was performed for real-time fluoroscopic tracking of the vessel wall during intervention. A finite-element computational model of a vessel was created with ADINA software (version 9.5) with arterial and venous biomechanical properties obtained from the literature to compare the response to radial expansion.

RESULTS

In vivo angioplasty and stent placement in a venous stenosis animal model with iron particle endothelium labeling demonstrated longitudinal foreshortening that correlated with distance from the center of the balloon (R² = 0.87) as well as adjacent segment narrowing that correlated with the increase in diameter of the treated stenotic segment (R² = 0.89). Finite-element computational analysis demonstrated increased Poisson effect in veins relative to arteries (linear regression coefficient slope comparison, arterial slope 0.033, R² = 0.9789; venous slope 0.204, R² = 0.9975; P < .0001) as a result of greater longitudinal Young modulus in veins compared with arteries.

CONCLUSIONS

Clinically observed adjacent segment narrowing during venous angioplasty and stent placement is a result of the Poisson effect, with redistribution of radially applied force to the longitudinal direction. The Poisson effect is increased in veins relative to arteries as a result of unique venous biomechanical properties, which may be relevant to consider in the design of future venous interventional devices.

Correction to: Yttrium-90 Radioembolization for BCLC Stage C Hepatocellular Carcinoma Comparing Child-Pugh A Versus B7 Patients: Are the Outcomes Equivalent?

The name of one of the co-authors was slightly misspelled. Kristian Enestvedt is listed currently as "Kristian K. Enestvedt" and should be listed instead as "C. Kristian Enestvedt."

ACR Appropriateness Criteria® Radiologic Management of Iliofemoral Venous Thrombosis

Iliofemoral venous thrombosis carries a high risk for pulmonary embolism, recurrent deep vein thrombosis, and post-thrombotic syndrome complicating 30% to 71% of those affected. The clinical scenarios in which iliofemoral venous thrombosis is managed may be diverse, presenting a challenge to identify optimum therapy tailored to each situation. Goals for management include preventing morbidity from venous occlusive disease, and morbidity and mortality from pulmonary embolism. Anticoagulation remains the standard of care for iliofemoral venous thrombosis, although a role for more aggressive therapies with catheter-based interventions or surgery exists in select circumstances. Results from recent prospective trials have improved patient selection guidelines for more aggressive therapies, and have also demonstrated a lack of efficacy for certain conservative therapies. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Biodegradable Hypericin-Containing Nanoparticles for Necrosis Targeting and Fluorescence Imaging

Necrosis targeting and imaging has significant implications for evaluating tumor growth, therapeutic response, and delivery of therapeutics to perinecrotic tumor zones. Hypericin is a hydrophobic molecule with high necrosis affinity and fluorescence imaging properties. To date, the safe and effective delivery of hypericin to areas of necrosis in vivo remains a challenge because of its incompatible biophysical properties. To address this issue, we have developed a biodegradable nanoparticle (Hyp-NP) for delivery of hypericin to tumors for necrosis targeting and fluorescence imaging. The nanoparticle was developed using methoxy poly(ethylene glycol)-b-poly(ε-caprolactone) and hypericin by a modified solvent evaporation technique. The size of Hyp-NP was 19.0 ± 1.8 nm from cryo-TEM and 37.3 ± 0.7 nm from dynamic light-scattering analysis with a polydispersity index of 0.15 ± 0.01. The encapsulation efficiency of hypericin was 95.05% w/w by UV-vis absorption. After storage for 30 days, 91.4% hypericin was retained in Hyp-NP with nearly no change in hydrodynamic size, representing nanoparticle stability. In an ovarian cancer cell line, Hyp-NP demonstrated cellular internalization with intracellular cytoplasmic localization and preserved fluorescence and necrosis affinity. In a mouse subcutaneous tumor model, tumor accumulation was noted at 8 h postinjection, with near-complete clearance at 96 h postinjection. Hyp-NP was shown to be tightly localized within necrotic tumor zones. Histological analysis of harvested organs demonstrated no gross abnormalities, and in vitro, no hemolysis was observed. This proof-of-concept study demonstrates the potential clinical applications of Hyp-NP for necrosis targeting.

Characterization of Iodide-induced Sialadenitis: Meta-analysis of the Published Case Reports in the Medical Literature

PURPOSE

To evaluate the patient presentation of postcontrast sialadenitis and factors associated with its duration of symptoms through meta-analysis of case reports.

BACKGROUND

Acute iodide sialadenitis, or "iodide mumps," is a rare adverse reaction to iodinated contrast causing salivary gland swelling. The condition may be underdiagnosed, with researchers postulating that its true incidence may be close to 1-2%.

METHODS AND MATERIALS

This study was a meta-analysis performed using PRISMA Reporting Standards. A literature search with no language restriction was performed of the Medline database, primarily through PubMed, using keywords: "iodide mumps," "iodide sialadenitis," "sialadenitis," "salivary enlargement," "contrast reaction," "parotid swelling," and "submandibular swelling." Matching case reports and case series were reviewed, and data regarding the subjects' demographics, renal function, contrast administration, and symptoms were extracted. Uni- and multivariate linear regression analyses were applied to assess the predicting factors of a prolonged symptoms duration.

RESULTS

Sixty-five case reports and case series were identified, with 77 cases of iodide-induced sialadenitis. Two cases were unpublished and from the author's institution. Reported subjects' median age was 63 years, and 61% (47/77) were males. Median time to onset was 16 hours, and symptoms resolved in a median of 3 days after the initial onset. Twenty-seven subjects (35%, 27/77) were reported to have an impaired renal function at baseline. Administration of nonionic, low osmolarity contrast medium was reported most frequently (53%, 41/77). There was no difference in resolution of symptoms among subjects with impaired versus normal renal function. Symptoms were resolved in all cases over a median of 3 days with no statistically significant difference between those who received therapeutic intervention and those who did not (p = 0.430). Older age and longer time to onset were significantly associated with longer duration of symptoms in both uni- and multivariate linear regression models, and presence of tenderness demonstrated statistical significance associated with longer duration of symptoms in the univariate model.

CONCLUSION

Postcontrast sialadenitis is a rare reaction to iodinated contrast media. Older age and a longer time to onset of symptoms are associated with longer duration of symptoms.

Treatment of pulmonary arteriovenous malformations: clinical experience using different embolization strategies

PURPOSE

To evaluate embolization efficacy of pulmonary arteriovenous malformations (PAVM) using Amplatzer vascular plugs (AVP) and coils.

MATERIALS AND METHODS

Eighty-eight embolized simple PAVMs in 38 patients were retrospectively analyzed by follow-up CT. Mean age was 50.2 ± 15.6 years and 22 (57.9%) patients were females. Mean follow-up interval was 38.2 ± 28.4 months (median 29.9 months). Embolization devices included AVP I, AVP II, AVP 4, and coils. Technical success was defined as no visualization of an early draining vein at angiography after embolization. Treatment success was defined as complete disappearance or decrease in size of the venous aneurysm ≥ 70% at follow-up CT.

RESULTS

Technical success rate was 100% and treatment success rate evaluated by CT for the various embolization strategies was 100% for AVP I (n = 6), 100% for AVP I + coils (n = 5), 83.3% for AVP II (n = 6), 40.0% for AVP II + coils (n = 5), 87.5% for AVP 4 (n = 8), 50.0% for AVP 4 + coils (n = 8), and 78.0% for coils alone (n = 50). No statistically significant difference in embolization efficacy was seen between different devices (P = 0.083). Although not statistically significant, combination use of coils with AVPs demonstrated lower rates of clinical embolization success (P = 0.053).

CONCLUSION

Embolization of PAVMs demonstrated high technical and treatment success rates with available embolic devices. No significant statistical differences were demonstrated between AVPs. However, the need for both coils and AVPs may suggest a more complicated underlying lesion at risk for recurrence.

Transtail Artery Access in Rats: A New Technique for Repeatable Selective Angiography

Transtail artery approach successfully enables selective arterial catheterization and angiography in the rat. This technique is effective and repeatable. In addition to its utility in imaging, it may also have a wide range of applications in transcatheter therapy and experimental cerebral stroke models.

Transarterial Delivery of a Biodegradable Single-Agent Theranostic Nanoprobe for Liver Tumor Imaging and Combinatorial Phototherapy

PURPOSE

To assess selective accumulation of biodegradable nanoparticles within hepatic tumors after transarterial delivery for in vivo localization and combinatorial phototherapy.

MATERIALS AND METHODS

A VX2 hepatic tumor model was used in New Zealand white rabbits. Transarterial delivery of silicon naphthalocyanine biodegradable nanoparticles was performed using a microcatheter via the proper hepatic artery. Tumors were exposed via laparotomy, and nanoparticles were observed by near-infrared (NIR) fluorescence imaging. For phototherapy, a handheld NIR laser (785 nm) at 0.6 W/cm² was used to expose tumor or background liver, and tissue temperatures were assessed with a fiberoptic temperature probe. Intratumoral reactive oxygen species formation was assessed using a fluorophore (2',7'-dichlorodihydrofluorescein diacetate).

RESULTS

Nanoparticles selectively accumulated within viable tumor by NIR fluorescence. Necrotic portions of tumor did not accumulate nanoparticles, consistent with a vascular distribution. NIR-dependent heat generation was observed with nanoparticle-containing tumors, but not in background liver. No heat was generated in the absence of NIR laser light. Reactive oxygen species were formed in nanoparticle-containing tumors exposed to NIR laser light, but not in background liver treated with NIR laser or in tumors in the absence of NIR light.

CONCLUSIONS

Biodegradable nanoparticle delivery to liver tumors from a transarterial approach enabled selective in vivo tumor imaging and combinatorial phototherapy.

Muscle Gain after Transjugular Intrahepatic Portosystemic Shunt Creation: Time Course and Prognostic Implications for Survival in Cirrhosis

PURPOSE

To examine the association of transjugular intrahepatic portosystemic shunt (TIPS) creation with muscle gains and patient mortality, and to identify the timeframe of these changes.

MATERIALS AND METHODS

Patients with cirrhosis undergoing TIPS creation with available abdominal computed tomography before and after TIPS from 2004-2015 were included (n = 76). The primary indications for TIPS included refractory ascites (52.6%) or variceal bleeding (47.4%). Axial truncal muscle area and attenuation were measured at the L4 level using free-hand region of interest technique, and pre- and post-TIPS values were compared. The association of TIPS-related muscle changes with mortality was evaluated using Cox multiple regression. Logistic regression analysis was performed to evaluate associations of baseline muscle area and clinical variables with post-TIPS changes.

RESULTS

TIPS creation was associated with significant increases in psoas, paraspinal, and total muscle areas (P < .001, 0.004, and 0.002), and psoas muscle attenuation (P = .022) at a median of 13.5 months after TIPS. Maximal muscle gains occurred within 6 months after TIPS creation (P < .001). Muscle gain at 1-year after TIPS was independently associated with lower mortality (psoas hazard ratio [HR] 0.14, P = .016; paraspinal HR 0.15, P = .016; abdominal HR 0.05, P = .005; core HR 0.06, P = .001; and total HR 0.05, P = .003). Baseline demographic or clinical variables were not associated with muscle gain after TIPS.

CONCLUSIONS

TIPS creation was strongly associated with truncal muscle gains and attenuation in patients with cirrhosis. Maximal muscle gain occurred within 6 months after TIPS creation. TIPS-related increased muscle mass was independently associated with lower patient mortality.

Palmar Warming for Radial Artery Vasodilation to Facilitate Transradial Access: A Randomized Controlled Trial

PURPOSE

To investigate the efficacy of palmar warming to induce radial artery vasodilation.

MATERIALS AND METHODS

After informed consent was obtained, healthy volunteers (n = 45) were randomized 2:1 in palmar warming and control groups, respectively, for this prospective, randomized, single-blind clinical trial (NCT03620383). The palmar warming group was given a warm, commercially available, air-activated heat pack (Kobayashi Consumer Products LLC, Dalton, Georgia) to hold in the left hand for palmar warming. The control group was given a deactivated version of the same heat pack. Left radial artery cross-sectional area (CSA) measurements were obtained at baseline and in 5-minute intervals up to 20 minutes in both groups. Differences in the trends of changes in the radial artery CSA between palmar warming and control groups were examined with the age- and sex-adjusted repeated measure analysis of variance. Propensity score-matched treatment effect analysis was conducted to quantify the effect of heat on radial artery CSA.

RESULTS

The palmar warming group and the control group were significantly different in terms of subject sex (males/females: 7/23 and 10/5, respectively; P = .005) and baseline CSA (2.5±0.2 mm² vs 3.2±0.3 mm², respectively; P = .014). Radial artery CSA showed an increasing trend over time in the palmar warming group compared to a stable trend over time in the control group (P < .0001). Propensity score-matched comparison showed a 43.9% increase (95% confidence interval: 34.1%-53.8%) in CSA in the palmar warming group compared to the control group (P < .0001).

CONCLUSIONS

The palmar warming technique is effective at dilating the radial artery and may be a beneficial technique to facilitate transradial access.