Wong, Matthew L.

Abstract Background The objective was to systematically evaluate the sensitivity of diffusion‐weighted magnetic resonance imaging (DW‐MRI) for transient global amnesia (TGA) across various time frames compared to the reference‐standard clinical criteria. Methods All indexed publications related to TGA and MRI through June 2020 were retrieved by a medical librarian. Two independent reviewers identified original research studies of adults with a clinical diagnosis of TGA using Caplan and Hodges and Warlow criteria (reference standard) who were evaluated with DW‐MRI. Pooled estimates and its 95% confidence intervals (CI) for the proportion of acute TGA patients with positive DW‐MRI (i.e., sensitivity) were obtained using random‐effects meta‐analysis for various time frames. Quality assessment was performed using the revised Quality of Assessment of Diagnostic Accuracy Studies (QUADAS‐2) tool. Results After screening 665 reports, we identified 81 potentially relevant studies. Twenty‐three studies representing 1688 patients met eligibility criteria, but not all studies had data available for meta‐analysis. The pooled sensitivity (also described as positivity rate) of DW‐MRI was 15.6% (95% CI = 2.6%–35.0%) between 0 and 12 h from symptom onset, 23.1% (95% CI = 6.1%–45.7%) at 0–24 h, 72.8% (95% CI = 40.8%–96.3) at 12–24 h, 68.8% (95% CI = 44.8%–88.8%) at 24–36 h, 72.4% (95% CI = 59.8%–83.5%) at 36–48 h, 82.8% (95% CI = 54.7%–99.6%) at 48–60 h, 66.9% (95% CI = 47.5%–83.9%) at 60–72 h, and 72.0% (95% CI = 30.1%–100.0%) at 72–96 h. There was significant concern for risk of bias in the QUADAS‐2 domains of patient selection and index test, yielding a low level of certainty in the pooled estimates. Conclusion DW‐MRI lesions are uncommon in patients with TGA early after symptom onset, but the sensitivity (i.e., positivity rate) of DW‐MRI increases with time. Despite the limited quality of existing evidence, obtaining an early DW‐MRI in patients with clinical diagnosis of TGA in the acute setting is likely a low‐yield test.