Comparison of Anticoagulation Regimens Following Stent Placement for Nonthrombotic Lower Extremity Venous Disease.

PURPOSE: To determine whether subtherapeutic anticoagulation regimens are noninferior to therapeutic anticoagulation regimens following stent placement for nonthrombotic lower extremity venous disease. MATERIALS AND METHODS: Fifty-one consecutive patients (88% women; mean age, 44 years) who underwent stent placement for nonthrombotic lower extremity venous disease between 2002 and 2016 were retrospectively identified. The patients were divided into 2 cohorts: those who received prophylactic enoxaparin or no anticoagulation (subtherapeutic) after the procedure and those who received therapeutic doses of anticoagulation with enoxaparin, warfarin, and/or rivaroxaban (therapeutic) after the procedure. Baseline demographic characteristics, procedure characteristics, and outcomes were compared between the 2 groups using the Student t test, Fisher exact test, and χ2 test. The subtherapeutic and therapeutic anticoagulation groups did not differ significantly in the baseline demographic characteristics (eg, sex, race, and age) or procedure characteristics (eg, number of stents placed, stent brand, stent diameter, etc). RESULTS: The mean clinical follow-up time was 4.4 years (range, 0-16.3 years). There were no thrombotic adverse events or luminal obstructions due to in-stent restenosis in either group. There were 5 minor bleeding adverse effects in the therapeutic group and no bleeding adverse effects in the subtherapeutic group (P = .051). There were no statistically significant differences in subjective symptom improvement (P = .75). CONCLUSIONS: In this retrospective cohort, the subtherapeutic and therapeutic anticoagulation regimens produced equivalent outcomes in terms of adverse event rates, reintervention rates, and symptomatic improvement, suggesting that therapeutic doses of anticoagulation do not improve outcomes compared with subtherapeutic anticoagulation regimens following nonthrombotic venous stent placement.

Society of Interventional Radiology Clinical Practice Guideline for Inferior Vena Cava Filters in the Treatment of Patients with Venous Thromboembolic Disease: Developed in collaboration with the American College of Cardiology, American College of Chest Physicians, American College of Surgeons Committee on Trauma, American Heart Association, Society for Vascular Surgery, and Society for Vascular Medicine.

PURPOSE: To provide evidence-based recommendations on the use of inferior vena cava (IVC) filters in the treatment of patients with or at substantial risk of venous thromboembolic disease. MATERIALS AND METHODS: A multidisciplinary expert panel developed key questions to address in the guideline, and a systematic review of the literature was conducted. Evidence was graded based on a standard methodology, which was used to inform the development of recommendations. RESULTS: The systematic review identified a total of 34 studies that provided the evidence base for the guideline. The expert panel agreed on 18 recommendations. CONCLUSIONS: Although the evidence on the use of IVC filters in patients with or at risk of venous thromboembolic disease varies in strength and quality, the panel provides recommendations for the use of IVC filters in a variety of clinical scenarios. Additional research is needed to optimize care for this patient population.

Deep Learning for Automated Classification of Inferior Vena Cava Filter Types on Radiographs.

PURPOSE: To demonstrate the feasibility and evaluate the performance of a deep-learning convolutional neural network (CNN) classification model for automated identification of different types of inferior vena cava (IVC) filters on radiographs. MATERIALS AND METHODS: In total, 1,375 cropped radiographic images of 14 types of IVC filters were collected from patients enrolled in a single-center IVC filter registry, with 139 images withheld as a test set and the remainder used to train and validate the classification model. Image brightness, contrast, intensity, and rotation were varied to augment the training set. A 50-layer ResNet architecture with fixed pre-trained weights was trained using a soft margin loss over 50 epochs. The final model was evaluated on the test set. RESULTS: The CNN classification model achieved a F1 score of 0.97 (0.92-0.99) for the test set overall and of 1.00 for 10 of 14 individual filter types. Of the 139 test set images, 4 (2.9%) were misidentified, all mistaken for other filter types that appear highly similar. Heat maps elucidated salient features for each filter type that the model used for class prediction. CONCLUSIONS: A CNN classification model was successfully developed to identify 14 types of IVC filters on radiographs and demonstrated high performance. Further refinement and testing of the model is necessary before potential real-world application.

Lower Extremity Venous Stent Placement: A Large Retrospective Single-Center Analysis.

PURPOSE: To study short-term and long-term outcomes of lower extremity venous stents placed at a single center and to characterize changes in vein diameter achieved by stent placement. MATERIALS AND METHODS: A database of all patients who received lower extremity venous stents between 1996 and 2018 revealed 1,094 stents were placed in 406 patients (172 men, 234 women; median age, 49 y) in 513 limbs, including patients with iliocaval stents (9.4% acute thrombosis, 65.3% chronic thrombosis, 25.3% nonthrombotic lesions). Primary, primary assisted, and secondary patency rates were assessed for lower extremity venous stents at 1, 3, and 5 years using Kaplan-Meier analyses and summary statistics. Subset analyses and Cox regression were performed to identify risk factors for patency loss. Vein diameters and Villalta scores before and up to 12 months after stent placement were compared. Complication and mortality rates were calculated. RESULTS: Primary, primary assisted, and secondary patency rates at 5 years were 57.3%, 77.2%, and 80.9% by Kaplan-Meier methods and 78.6%, 90.3%, and 92.8% by summary statistics. Median follow-up was 199 days (interquartile range, 35.2-712.0 d). Patency rates for the subset of patients (n = 46) with ≥ 5 years of follow-up (mean ± SD 9.1 y ± 3.4) were nearly identical to cohort patency rates at 5 years. Patients with inferior vena cava stent placement (hazard ratio 2.11, P < .0001) or acute thrombosis (hazard ratio 3.65, P < .0001) during the index procedure had significantly increased risk of losing primary patency status. Vein diameters were significantly greater after stent placement. There were no instances of stent fracture, migration, or structural deformities. In patients with chronic deep vein thrombosis, Villalta scores significantly decreased after stent placement (from 15.7 to 7.4, P < .0001). Perioperative mortality was < 1%, and major perioperative complication rate was 3.7%. CONCLUSIONS: Cavo-ilio-femoral stent placement for venous occlusive disease achieves improvement of vein disease severity scores, increase in treated vein diameters, and satisfactory long-term patency rates.

Toward Data-Driven Learning Healthcare Systems in Interventional Radiology: Implementation to Evaluate Venous Stent Patency.

We developed a code and data-driven system (learning healthcare system) for gleaning actionable clinical insight from interventional radiology (IR) data. To this end, we constructed a workflow for the collection, processing and analysis of electronic health record (EHR), imaging, and cancer registry data for a cohort of interventional radiology patients seen in the IR Clinic at our institution over a more than 20-year period. As part of this pipeline, we created a database in REDCap (VITAL) to store raw data, as collected by a team of clinical investigators and the Data Coordinating Center at our university. We developed a single, universal pre-processing codebank for our VITAL data in R; in addition, we also wrote widely extendable and easily modifiable analysis code in R that presents results from summary statistics, statistical tests, visualizations, Kaplan-Meier analyses, and Cox proportional hazard modeling, among other analysis techniques. We present our findings for a test case of supra versus infra-inguinal ligament stenting. The developed pre-processing and analysis pipelines were memory and speed-efficient, with both pipelines running in less than 2 min. Three different supra-inguinal ligament veins had a statistically significant improvement in vein diameters post-stenting versus pre-stenting, while no infra-inguinal ligament veins had a statistically significant improvement (due either to an insufficient sample size or a non-significant p value). However, infra-inguinal ligament stenting was not associated with worse restenosis or patency outcomes in either a univariate (summary-statistics and Kaplan-Meier based) or multivariate (Cox proportional hazard model based) analysis.

Endovascular Removal of Fractured Inferior Vena Cava Filter Fragments: 5-Year Registry Data with Prospective Outcomes on Retained Fragments.

PURPOSE: To evaluate the safety and efficacy of attempted percutaneous filter fragment removal during retrieval of fractured inferior vena cava (IVC) filters and to report outcomes associated with retained filter fragments. MATERIALS AND METHODS: Over a 5-year period, 82 consecutive patients presenting with a fractured IVC filter were prospectively enrolled into an institutional review board-approved registry. There were 27 men and 55 women (mean, 47 y; range, 19-85 y). After main filter removal, percutaneous removal of fragments was attempted if they were deemed intravascular and accessible on preprocedural computed tomography (CT), cone-beam CT, and/or intravascular ultrasound; distal pulmonary artery (PA) fragments were left alone. A total of 185 fragments were identified (81 IVC, 33 PA, 16 cardiac, 2 hepatic vein, 1 renal vein, 1 aorta, 51 retroperitoneal). Mean filter dwell time was 2,183 days (range, 59-9,936 d). Eighty-seven of 185 fragments (47%) were deemed amenable to attempted removal: 65 IVC, 11 PA, 8 cardiac, 2 hepatic, and 1 aortic. Primary safety outcomes were major procedure-related complications. RESULTS: Fragment removal was successful in 78 of 87 cases (89.7%; 95% confidence interval [CI], 81.3-95.2). There were 6 minor complications with no consequence (6.9%; 95% CI, 2.6-14.4) involving intraprocedural fragment embolization and 1 major complication (1.1%; 95% CI, 0.0-6.2), a cardiac tamponade that was successfully treated. The complication rate from attempted cardiac fragment removal was 12.5% (1 of 8; 95% CI, 0.3-52.7). Among patients with retained cardiopulmonary fragments (n = 19), 81% remained asymptomatic during long-term clinical follow-up of 845 days (range, 386-2,071 d). CONCLUSIONS: Percutaneous removal of filter fragments from the IVC and proximal PAs is safe and effective overall, but attempted intracardiac fragment removal carries a higher risk of complication. Most residual filter fragments not amenable to percutaneous removal remain asymptomatic and may be monitored clinically.

Stratification, Imaging, and Management of Acute Massive and Submassive Pulmonary Embolism.

While pulmonary embolism (PE) causes approximately 100 000-180 000 deaths per year in the United States, mortality is restricted to patients who have massive or submassive PEs. This state of the art review familiarizes the reader with these categories of PE. The review discusses the following topics: pathophysiology, clinical presentation, rationale for stratification, imaging, massive PE management and outcomes, submassive PE management and outcomes, and future directions. It summarizes the most up-to-date literature on imaging, systemic thrombolysis, surgical embolectomy, and catheter-directed therapy for submassive and massive PE and gives representative examples that reflect modern practice. © RSNA, 2017.

Endovascular Management of May-Thurner Syndrome in Adolescents: A Single-Center Experience.

PURPOSE: To report a single-center experience in regard to the technique, safety, and clinical outcomes of endovascular therapy for treatment of May-Thurner syndrome (MTS) in adolescent patients. MATERIALS AND METHODS: A retrospective review identified 10 patients (6 female; mean age, 16 y; range, 12-18 y; mean weight, 73 kg; range, 50-116 kg) treated by endovascular therapy for MTS from 1998 to 2015. Clinical presentations consisted of acute thrombotic MTS (n = 6) and nonthrombotic MTS (n = 4). Catheter-directed thrombolysis was performed in all cases of thrombosis. Venoplasty and stent placement were performed in all cases. Self-expanding stents 12-16 mm in diameter and 4-9 cm in length were deployed. RESULTS: No major periprocedural complications were observed. Median follow-up was 32 months (range, 6-109 mo). Primary and secondary patency rates were 79% and 100% at 12 months and 79% and 89% at 36 months, respectively. In a single patient with permanent loss of flow in the treated segment, multiple risk factors for thrombosis were identified. Rates of posttreatment symptoms were 0% by Villalta score and 60% (n = 6; mild symptoms) by modified Villalta score at the last clinical follow-up. CONCLUSIONS: Endovascular therapy for the treatment of MTS in our adolescent cohort was safe and effective in relieving venous obstruction. Stent placement in patients with underlying thrombophilic disorders is associated with loss of secondary patency, suggesting the need for further consideration in this population.

Superselective Chemoembolization of HCC: Comparison of Short-term Safety and Efficacy between Drug-eluting LC Beads, QuadraSpheres, and Conventional Ethiodized Oil Emulsion.

PURPOSE: To study the comparative short-term safety and efficacy of transcatheter arterial chemoembolization (TACE) with drug-eluting LC Beads loaded with doxorubicin (DEBDOX), doxorubicin-eluting QuadraSpheres (hqTACE), and conventional TACE using ethiodized oil for superselective C-arm computed tomography (CT)-guided treatment of hepatocellular carcinoma (HCC) after the onset of drug shortages. MATERIALS AND METHODS: From March 2010 to March 2011, 166 patients with HCC were treated with 232 superselective TACE procedures using C-arm cone-beam CT at one institution. Patients underwent treatment depending on the availability of materials after the onset of drug shortages. Conventional TACE with doxorubicin, cisplatin, and Ethiodol was performed for 159 procedures, DEBDOX TACE was performed for 47, and hqTACE was performed for 26. Toxicity and objective response were compared at 3 months after treatment. Data were stratified for the high-risk population (Child-Pugh class B, performance status 1, bilobar disease, and/or post-resection recurrence) and initial versus repeat treatment. Kruskal-Wallis H test, Mann-Whitney U test, and Fisher exact test were used to compare the groups, with Bonferroni correction where needed. RESULTS: Whole liver response rates trended higher for conventional TACE (conventional TACE, 65.4%; DEBDOX, 63.8%; hqTACE, 53.8%) (P = .085). Only minor trends for differences in toxicity were observed between the three groups. Low-risk patients had higher whole liver (P = .001) and treated lesion (P = .007) response rates when treated with conventional TACE, but no significant differences were seen for DEBDOX and hqTACE. Treatment-naive patients also had higher whole liver (P = .012) and treated lesion (P = .056) response rates. No advantages for drug-eluting microspheres were found. CONCLUSION: Within statistical power limitations, overall toxicity and efficacy were equivalent in patients treated with LC Beads, QuadraSpheres, or ethiodized oil emulsions, including in high-risk patients, when performed superselectively with cone-beam C-arm CT guidance.

Inferior Vena Cava Filter Elucidation: How to Identify Specific Inferior Vena Cava Filter Types on Multi-Detector-Row Computed Tomography Imaging.

The use of inferior vena cava (IVC) filters in the United States has increased substantially over the last 3 decades. In addition, the number of Food and Drug Administration-approved devices has also increased during this time, and there are now more than 24 different IVC filter types that may be encountered in clinical practice. These devices vary substantially with regard to design, retrievability, and risk of potential complications that include fracture, penetration, embolization, migration, recurrent venous thromboembolism, and chronic IVC occlusion. A myriad of devices are now routinely encountered on multi-detector-row computed tomography imaging, but it can be challenging to properly identify a specific IVC filter type. Proper device identification has important clinical consequences because each filter type has associated risks that may otherwise be overlooked. Identifying the specific filter type may allow further radiographic surveillance for known device-specific complications and may identify patients who can benefit from further medical treatment or prompt filter retrieval. Therefore, our purpose was to present a practical method to identify the various IVC filter types that may be encountered on multi-detector-row computed tomography imaging.

Bard Denali inferior vena cava filter fracture and embolization resulting in cardiac tamponade: a device failure analysis.

A 46-year-old woman underwent inferior vena cava filter placement before bariatric surgery and returned within 6 months for routine removal. She complained of a 1-week history of severe chest pain, and during retrieval, two fractured filter components were identified including one arm in the right ventricle. The filter body and one fragment were successfully retrieved, but the fragment in the right ventricle was refractory to percutaneous retrieval. During open-heart surgery, the fragment was found traversing through the ventricular wall resulting in cardiac tamponade. Electron microscopic fragment analysis revealed high-cycle metal fatigue indicating the filter design failed to withstand this patient's natural inferior vena cava biomechanical motions.

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.

Vena Tech LGM filter retrieval 16 years after implantation: piecemeal removal by intentional mechanical fracture.

A 48-year-old man presented with symptomatic inferior vena cava (IVC) occlusion from a chronically thrombosed and embedded Vena Tech LGM filter resulting in exercise intolerance from diminished cardiac preload and postthrombotic syndrome from chronic venous insufficiency. The patient was treated using a new PRIME technique--Piecemeal Removal by Intentional MEchanical fracture--to achieve successful filter retrieval 16 years after implantation. Removal of the obstructing filter permitted endovascular IVC recanalization with restoration of venous outflow and alleviation of venous obstructive symptoms. Cardiac preload was restored, allowing the patient to resume long-distance running, and he successfully completed a half-marathon 3 months after treatment.

Complex retrieval of fractured, embedded, and penetrating inferior vena cava filters: a prospective study with histologic and electron microscopic analysis.

PURPOSE: To evaluate clinical outcomes, characterize adherent tissue, and analyze inferior vena cava (IVC) filter fractures in patients undergoing complex retrieval for management of filter-related complications. To elucidate mechanisms of filter fracture by radiographic and electron microscopic (EM) evaluation. MATERIALS AND METHODS: Over 2.5 years, 50 consecutive patients with fractured and/or penetrating filter components were prospectively enrolled into a single-center study. There were 19 men and 31 women (mean age, 42 y; range, 15-73 y). All patients underwent complex filter retrieval after failure of standard methods, and retrieval indications along with resultant clinical outcomes were evaluated. Specimens with adherent tissue underwent histologic analysis, and all fractured components were studied with EM. RESULTS: Retrieval was successful in all 50 cases (mean implantation, 815 d; range, 20-2,599 d) among the following filters: G2X (n = 23),G2 (n = 9), Eclipse (n = 3), Recovery (n = 4), ALN (n = 1), Celect (n = 7), OptEase (n = 2), and Simon Nitinol (n = 1). Mean indwell time in fractured filters (n = 31) was 1,082 days, versus 408 days in nonfractured filters (n = 19; P = .00169). Neointimal hyperplasia/fibrosis was seen in 46 of 48 specimens with adherent tissue (96%). Among 61 fractured components from conical filters, 35 had extravascular penetration whereas 26 remained intravascular (11 free-floating in IVC, 15 embolized centrally), and EM revealed fracture modes of high-cycle fatigue (n = 53), overload (n = 6), and indeterminate (n = 2). Following retrieval, previously prescribed lifelong anticoagulation was discontinued in 30 of 31 patients (97%). Filter-related symptoms from IVC occlusion, component embolization, and penetration-induced abdominal pain, duodenal injury, and/or small-bowel volvulus were alleviated in all 26 cases (100%). There were no long-term complications at a mean follow-up of 371 days (range, 67-878 d). CONCLUSIONS: The risk of filter fracture increases after 408 days (ie,>1 y) of implantation and is associated with symptomatic extravascular penetration and/or intravascular embolization. Complex methods can be used to safely remove these devices, alleviate filter-related morbidity, and allow cessation of anticoagulation.

Endovascular therapy for acute pulmonary embolism.

Acute pulmonary embolism (PE) is the third most common cause of death among hospitalized patients. Treatment escalation beyond anticoagulation therapy is necessary in patients with massive PE (defined by hemodynamic shock) as well as in many patients with submassive PE (defined by right ventricular strain). The best current evidence suggests that modern catheter-directed therapy to achieve rapid central clot debulking should be considered as an early or first-line treatment option for patients with acute massive PE; and emerging evidence suggests a catheter-directed thrombolytic infusion should be considered as adjunctive therapy for many patients with acute submassive PE. This article reviews the current approach to endovascular therapy for acute PE in the context of appropriate diagnosis, risk stratification, and management of acute massive and acute submassive PE.

Correlation of the diameter of the left common iliac vein with the risk of lower-extremity deep venous thrombosis.

PURPOSE: Compression of the left common iliac vein (CIV; LCIV) is a known risk factor for lower-extremity deep vein thrombosis (DVT). This study was performed to model the probability of DVT based on LCIV diameter and apply this to a quantitative DVT risk factor scoring system. MATERIALS AND METHODS: Medical records were used to identify female patients younger than 45 years of age who were diagnosed with lower-extremity DVT (n = 21) and age-matched control subjects (n = 26) who presented to the emergency department with abdominal pain. Minimum CIV diameters were measured on computed tomography. Based on published reporting standards, 13 risk factors were scored for patients diagnosed with left-sided DVT and for control subjects. The association between vein diameter and DVT was examined by Mann-Whitney test. Odds of DVT based on vein diameter was assessed by logistic regression. RESULTS: Mean minimum LCIV diameters were 4.0 mm for patients with DVT and 6.5 mm for patients without DVT (P = .001). The odds of left DVT increased by a factor of 1.68 for each millimeter decrease in LCIV diameter (odds ratio = 1.68; P = .006; 95% confidence interval, 1.16-2.43). As the risk factor score increased, the relationship between diameter and risk for DVT became stronger; identical LCIV diameters were associated wtih a higher probability of developing DVT if the risk factor score was higher. CONCLUSIONS: Stenosis of the LCIV was found to be a strong independent risk factor for development of DVT. Moreover, each millimeter decrease in CIV diameter increased the odds of DVT by a factor of 1.68.