Diffusion-weighted imaging and diagnosis of transient ischemic attack
Version of Record online: 2 JAN 2014
© 2013 The Authors. Annals of Neurology published byWiley Periodicals, Inc. on behalf of the American Neurological Association
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Annals of Neurology
Volume 75, Issue 1, pages 67–76, January 2014
How to Cite
Brazzelli, M., Chappell, F. M., Miranda, H., Shuler, K., Dennis, M., Sandercock, P. A. G., Muir, K. and Wardlaw, J. M. (2014), Diffusion-weighted imaging and diagnosis of transient ischemic attack. Ann Neurol., 75: 67–76. doi: 10.1002/ana.24026
- Issue online: 12 FEB 2014
- Version of Record online: 2 JAN 2014
- Accepted manuscript online: 1 OCT 2013 10:05AM EST
- Manuscript Accepted: 10 SEP 2013
- Manuscript Revised: 27 AUG 2013
- Manuscript Received: 4 JUN 2013
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.
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.
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.
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. ANN NEUROL 2014;75:67–76