Purpose To perform a systematic review and meta-analysis to determine if there are differences in rates of immediate allergic events between classes of gadolinium-based contrast agents (GBCAs). Materials and Methods PubMed and Google Scholar databases were searched for studies in which rates of immediate adverse events to GBCAs were reported. The American College of Radiology classification system was used to characterize allergic-like events as mild, moderate, or severe, and the total number of administrations of each GBCA was recorded. Where necessary, authors of studies were contacted to clarify data and eliminate physiologic reactions. Relative risks of GBCA types were estimated by using the Mantel-Haenszel type method. Results Nine studies in which immediate reactions to GBCA were recorded from a total of 716 978 administrations of GBCA met the criteria for inclusion and exclusion. The overall rate of patients who had immediate allergic-like reactions was 9.2 per 10 000 administrations and the overall rate of severe immediate allergic-like reactions was 0.52 per 10 000 administrations.. The nonionic linear chelate gadodiamide had the lowest rate of reactions, at 1.5 (95% confidence interval [CI]: 0.74, 2.4) per 10 000 administrations, which was significantly less than that of linear ionic GBCAs at 8.3 (95% CI: 7.5, 9.2) per 10 000 administrations (relative risk, 0.19 [95% CI: 0.099, 0.36]; P< .00001) and less than that for nonionic macrocyclic GBCAs at 16 (95% CI: 14, 19) per 10 000 administrations (relative risk, 0.12 [95% CI: 0.05, 0.31]; P < .001). GBCAs known to be associated with protein binding had a higher rate of reactions, at 17 (95% CI: 15, 20) per 10 000 administrations compared with the same chelate classification without protein binding, at 5.2 (95% CI: 4.5, 6.0) per 10 000 administrations (relative risk, 3.1 [95% CI: 2.4, 3.8]; P < .0001). Conclusion These data show the lowest rate of immediate allergic adverse events with use of the nonionic linear GBCA gadodiamide in comparison with those of ionic linear or nonionic macrocyclic GBCAs. A higher rate of immediate allergic adverse events was associated with ionicity, protein binding, and macrocyclic structure. RSNA, 2017 An earlier incorrect version of this article appeared online. This article was corrected on August 31, 2017.

Background:This systematic review combines data from multiple papers on contrast media extravasation to identify factors contributing to increased extravasation risk.Methods:Data were extracted from 17 papers reporting 2191 extravasations in 1,104,872 patients (0.2%) undergoing computed tomography (CT) or magnetic resonance imaging (MRI).Results:Extravasation rates were 0.045% for gadolinium-based contrast agents (GBCA) and nearly 6-fold higher, 0.26% for iodinated contrast agents. Factors associated with increased contrast media extravasations included: older age, female gender, using an existing intravenous (IV) instead of placing a new IV in radiology, in-patient status, use of automated power injection, high injection rates, catheter location, and failing to warm up the more viscous contrast media to body temperature.Conclusion:Contrast media extravasation is infrequent but nearly 6 times less frequent with GBCA for MRI compared with iodinated contrast used in CT.

BackgroundTo analyse the clinical characteristics of COVID-19 with acute ischaemic stroke (AIS) and identify factors predicting functional outcome.MethodsMulticentre retrospective cohort study of COVID-19 patients with AIS who presented to 30 stroke centres in the USA and Canada between 14 March and 30 August 2020. The primary endpoint was poor functional outcome, defined as a modified Rankin Scale (mRS) of 5 or 6 at discharge. Secondary endpoints include favourable outcome (mRS ≤2) and mortality at discharge, ordinal mRS (shift analysis), symptomatic intracranial haemorrhage (sICH) and occurrence of in-hospital complications.ResultsA total of 230 COVID-19 patients with AIS were included. 67.0% (154/230) were older than 60 years, while 33.0% (76/230) were younger. Median (IQR) National Institutes of Health Stroke Scale (NIHSS) at presentation was 12.0 (17.0) and 42.8% (89/208) presented with large vessel occlusion (LVO). Approximately 50.2% (102/203) of the patients had poor outcomes with an observed mortality rate of 38.8% (35/219). Age >60 years (aOR: 4.60, 95% CI 1.89 to 12.15, p=0.001), diabetes mellitus (aOR: 2.53, 95% CI 1.14 to 5.79, p=0.025), increased NIHSS at admission (aOR: 1.10, 95% CI 1.05 to 1.16, p<0.001), LVO (aOR: 3.02, 95% CI 1.27 to 7.44, p=0.014) and no IV tPA (aOR: 2.76, 95% CI 1.06 to 7.64, p=0.043) were significantly associated with poor functional outcome.ConclusionThere may be a relationship between COVID-19 associated AIS and severe disability or death. We identified several factors that predict worse outcomes, and these outcomes were more frequent compared with global averages. We found that elevated neutrophil-to-lymphocyte ratio, rather than D-dimer, predicted both morbidity and mortality.