Use of magnetic resonance angiography to select candidates with recently symptomatic carotid stenosis for surgery: systematic review

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Abstract
Objective: To determine if sufficient evidence exists to support the use of magnetic resonance angiography as a means of selecting patients with recently symptomatic high grade carotid stenosis for surgery. Design: Systematic review of published research on the diagnostic performance of magnetic resonance angiography, 1990-9. Main outcome measures: Performance characteristics of diagnostic test. Results: 126 potentially relevant articles were identified, but many articles failed to examine the performance of magnetic resonance angiography as a diagnostic test at the surgical decision thresholds used in major clinical trials on endarterectomy. 26 articles were included in a meta-analysis that showed a maximal joint sensitivity and specificity of 99% (95% confidence interval 98% to 100%) for identifying 70-99% stenosis and 90% (81% to 99%) for identifying 50-99% stenosis. Only four articles evaluated contrast enhanced magnetic resonance angiography. Conclusions: Magnetic resonance angiography is accurate for selecting patients for carotid endarterectomy at the surgical decision thresholds established in the major endarterectomy trials, but the evidence is not very robust because of the heterogeneity of the studies included. Research is needed to determine the diagnostic performance of the most recent developments in magnetic resonance angiography, including contrast enhanced techniques, as well as to assess the impact of magnetic resonance angiography on surgical decision making and outcomes. What is already known on this topic Carotid endarterectomy for recently symptomatic carotid stenosis is beneficial in patients with 70-99% stenosis as measured by conventional angiography It is not known whether the less invasive imaging technique of magnetic resonance angiography can accurately identify patients who will benefit from surgery What this study adds Magnetic resonance angiography is highly sensitive and specific in diagnosing 70-99% carotid stenosis However, the studies on which this conclusion is based are of low quality and high heterogeneity