Diffusion-weighted imaging and diagnosis of transient ischaemic attack

Miriam Brazzelli, Francesca M. Chappell, Hector Miranda, Kirsten Shuler, Martin Dennis, Peter A. G. Sandercock, Keith Muir, Joanna M. Wardlaw

Research output: Contribution to journalArticlepeer-review

Abstract

Objective: Magnetic resonance (MR) diffusion‐weighted imaging (DWI) is sensitive to small acute ischemic lesions and might help diagnose transient ischemic attack (TIA). Reclassification of patients with TIA and a DWI lesion as “stroke” is under consideration. We assessed DWI positivity in TIA and implications for reclassification as stroke.
Methods: We searched multiple sources, without language restriction, from January 1995 to July 2012. We used PRISMA guidelines, and included studies that provided data on patients presenting with suspected TIA who underwent MR DWI and reported the proportion with an acute DWI lesion. We performed univariate random effects meta‐analysis to determine DWI positive rates and influencing factors.
Results: We included 47 papers and 9,078 patients (range = 18–1,693). Diagnosis was by a stroke specialist in 26 of 47 studies (55%); all studies excluded TIA mimics. The pooled proportion of TIA patients with an acute DWI lesion was 34.3% (95% confidence interval [CI] = 30.5–38.4, range = 9–67%; I2 = 89.3%). Larger studies (n > 200) had lower DWI‐positive rates (29%; 95% CI = 23.2–34.6) than smaller (n < 50) studies (40.1%; 95% CI = 33.5–46.6%; p = 0.035), but no other testable factors, including clinician speciality and time to scanning, reduced or explained the 7‐fold DWI‐positive variation.
Interpretation: The commonest DWI finding in patients with definite TIA is a negative scan. Available data do not explain why ⅔ of patients with definite specialist‐confirmed TIA have negative DWI findings. Until these factors are better understood, reclassifying DWI‐positive TIAs as strokes is likely to increase variance in estimates of global stroke and TIA burden of disease.
Original languageEnglish
Pages (from-to)67-76
Number of pages10
JournalAnnals of Neurology
Volume75
Issue number1
Early online date2 Jan 2014
DOIs
Publication statusPublished - 31 Jan 2014

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