Purpose To evaluate the sensitivity, specificity, and diagnostic odds ratios of US, CT, and MRI as second-line imaging modalities after initial US for assessing acute appendicitis in children and adults. Materials and Methods A literature search was conducted in Medline and Embase to identify articles that used surgery or histopathologic examination alone or in combination with clinical follow-up or chart review to evaluate the diagnostic accuracy of second-line imaging modalities. The quality of articles was assessed by using the Quality Assessment of Diagnostic Accuracy Studies-2 and the Standards for Reporting of Diagnostic Accuracy tools. Results For studies of children, the number of studies and patients were as follows: US, six studies and 548 patients; CT, nine studies and 1498 patients; MRI, five studies and 287 patients. For studies of adults, the number of studies and patients were as follows: US, three studies and 169 patients; CT, 11 studies and 1027 patients; MRI, six studies and 427 patients. Pooled sensitivities and specificities of second-line US for diagnosis of appendicitis in children were 91.3% (95% confidence interval [CI]: 83.8%, 95.5%) and 95.2% (95% CI: 91.8%, 97.3%), respectively; and in adults, the pooled sensitivities and specificities were 83.1% (95% CI: 70.3%, 91.1%) and 90.9% (95% CI: 59.3%, 98.6%), respectively. Regarding second-line CT in children, the pooled sensitivities and specificities were 96.2% (95% CI: 93.2%, 97.8%) and 94.6% (95% CI: 92.8%, 95.9%); and in adults, the pooled sensitivities and specificities were 89.9% (95% CI: 85.4%, 93.2%) and 93.6% (95% CI: 91.2%, 95.3%), respectively. Regarding second-line MRI in children, pooled sensitivities and specificities were 97.4% (95% CI: 85.8%, 100%) and 97.1% (95% CI: 92.1%, 99.0%); and in adults, the pooled sensitivities and specificities were 89.9% (95% CI: 84.8%, 93.5%) and 93.6% (95% CI: 90.9%, 95.5%), respectively. Conclusion Second-line US, CT, and MRI have comparable and high accuracy in helping to diagnose appendicitis in children and adults, including pregnant women. All three modalities may be valid as second-line imaging in a clinical imaging pathway for diagnosis and management of appendicitis.

It remains uncertain whether computed tomography angiography (CTA) in ischemic strokes and transient ischemic attacks (TIAs) benefits patient outcomes beyond those eligible for endovascular therapy. We conducted a systematic review and meta-analysis of observational studies and randomized controlled trials (RCTs) investigating the use of CTA against other imaging modalities for recurrent stroke, mortality, disability, emergency department (ED) revisits, or changes in management in ischemic stroke and TIA. (PROSPERO: 349590) Methods MEDLINE, Embase, and CENTRAL were searched. We included studies evaluating CTA against non-CTA imaging modalities for outcomes of interest in ischemic stroke or TIA. Two reviewers extracted data and assessed study quality. Data were pooled by the generic inverse variance method. Heterogeneity was assessed using Cochran's Q statistic and quantified by I 2 . Quality of the evidence was assessed by GRADE. ResultsWe found 12 eligible cohort studies involving 17,481 patients, and no eligible RCTs. No changes were detected in recurrent stroke, mortality, or disability when CTA was compared against pooled imaging modalities, nor compared to non-contrast computed tomography (NCCT) alone. The evidence for each outcome was graded as low quality to very low quality. ConclusionsCTA use was not associated with significant reductions in recurrent stroke, mortality, or disability in ischemic stroke and TIA patient compared with other imaging modalities. More high-quality studies are needed.