Ferumoxytol MR Angiography versus Duplex US for Vascular Mapping before Arteriovenous Fistula Surgery for Hemodialysis.

Background Duplex US is performed routinely for vascular mapping prior to arteriovenous fistula (AVF) creation for hemodialysis but cannot demonstrate the central vasculature. Ferumoxytol, an iron oxide nanoparticle, provides an alternative to gadolinium contrast material for MR angiography for safe use in chronic kidney disease (CKD). Purpose To assess the clinical utility of ferumoxytol-enhanced MR angiography compared with duplex US for vascular mapping before upper limb AVF creation in participants with CKD. Materials and Methods In a prospective comparative study (ClinicalTrials.gov: NCT02997046) from December 2016 to August 2018, participants with CKD underwent ferumoxytol-enhanced MR angiography and duplex US. Two independent readers evaluated vessels for diameter, stenosis or occlusion, arterial disease, and central stenosis. Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to assess intra- and interreader variability. On the basis of accepted standards for AVF creation, an algorithm was developed to predict AVF outcome based on imaging findings. Multivariable regression models used AVF success as the dependent variable and age, sex, and duplex US or ferumoxytol-enhanced MR angiography findings as independent variables. Results Fifty-nine participants with CKD (mean age, 59 years ± 13 [standard deviation]; 30 women) were evaluated. A total of 51 fistulas were created, of which 24 (47%) were successful. Ferumoxytol-enhanced MR angiography showed excellent inter- and intrareader repeatability (ICC, 0.84-0.99) for all variables assessed. In addition to revealing 15 central vasculature stenoses, ferumoxytol-enhanced MR angiography resulted in characterization of 88 of 236 (37%) of the arterial sections examined as unsuitable for AVF creation compared with 61 of 236 (26%) sections with duplex US (P = .01). Ferumoxytol-enhanced MR angiography independently predicted AVF success in models including (odds ratio, 6.5; 95% confidence interval: 1.7, 25; P = .006) and those excluding (odds ratio, 4.6; 95% confidence interval: 1.3, 17; P = .02) the central vasculature. Conclusion In addition to enabling identification of central vessel pathologic features, ferumoxytol-enhanced MR angiography revealed peripheral arterial disease not recognized with duplex US and was more predictive than duplex US of the outcome of arteriovenous fistula surgery. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Finn in this issue.

Use of Direct Oral Anticoagulants Versus Traditional Therapies for Acute Venous Thromboembolism After Direct Discharge From the Emergency Department or After Hospitalization: An Audit of 16 Canadian Hospitals.

PURPOSE: This study compares and describes the use of direct oral anticoagulants (DOACs) versus traditional therapies (parenteral anticoagulant with or without warfarin) for acute venous thromboembolism (VTE) between individuals discharged directly from the emergency department (ED) versus those hospitalized. This study also reports patterns based on discharge from an academic, community, or rural-based site. METHODS: This retrospective medical records study included patients discharged with acute VTE (2015-2016) from 16 institutions across 4 provinces. Patients with atypical clots, other indications for anticoagulants, or an anticipated lifespan <3 months or those who were pregnant or breastfeeding were excluded. FINDINGS: Overall, 590 individuals (30.0%) discharged from the ED and 809 (53.8%) discharged after hospitalization were studied. Hospitalized patients were significantly older, had more comorbidities (cancer, pulmonary disease, and heart failure), and were more likely to have pulmonary embolism than deep vein thrombosis. DOAC use was significantly higher in the ED cohort versus the hospitalized cohort (51.4% vs 44.3%; P < 0.004) and more common for those having lower risk of pulmonary embolisms (simplified Pulmonary Embolism Severity Index score of 0 compared with ≥1) in the ED (58.0% and 26.5%; P < 0.0001) and hospitalized cohorts (57.1% and 35.7%; P < 0.0001). Use of DOACs was lowest in academic settings (46.2%) and highest in rural sites (56.7%). Follow-up patterns were different, with specialists and VTE clinics being most common in academic sites and family physicians being most common in rural practices. IMPLICATIONS: DOACs were used in less than half of all patients, with more use in EDs and rural sites. Follow-up patterns (VTE clinic or specialist vs family physician) varied and likely contributed to therapy selection. Over time, use of DOACs is likely to increase, and patient factors (eg, those younger with fewer comorbidities) and health care contact (eg, place of discharge or availability of an ambulatory VTE clinic) will likely continue to influence practice patterns.