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(Stroke. 2008;39:1898.)
© 2008 American Heart Association, Inc.

Research Letters

When to Expect Negative Diffusion-Weighted Images in Stroke and Transient Ischemic Attack

P.N. Sylaja, MD; Shelagh B. Coutts, MD, FRCPC; Andrea Krol, BSc; Michael D. Hill, MD, MSc, FRCPC; Andrew M. Demchuk, MD, FRCPC for the VISION Study Group

From the Calgary Stroke Program, Seaman Family MR Research Centre, Department of Clinical Neurosciences, University of Calgary, Alberta, Canada.

Correspondence to Andrew M. Demchuk, MD, FRCPC, Director, Calgary Stroke Program, Associate Professor, Department of Clinical Neurosciences, Foothills Medical Centre, Room 1162, University of Calgary, Alberta, Canada. E-mail ademchuk{at}ucalgary.ca

Background and Purpose— The frequency of DWI negative cerebral ischemia and clinical factors associated with such a circumstance is not well understood.

Methods— We performed MRI including diffusion-weighted imaging (DWI) in patients with stroke and transient ischemic attack (TIA) within 24 hours of symptom onset and again at 30 days.

Results— Of 401 patients, 103 (25.6%) had an initial negative DWI study. In the DWI negative group, among the stroke patients, 6/26 (23.1%) had infarcts on follow-up MRI (4 lacunar and 2 posterior circulation syndromes) and 1 had a rMTT deficit. Among the TIA patients, 4/63 (6.3%) showed rMTT deficits and 2/63 (3.2%) had infarcts on follow-up MRI.

Conclusions— Baseline perfusion weighted imaging sequences may detect ischemia in a small proportion of DWI negative cases. Only those with brain stem location or lacunar syndrome were DWI negative initially and yet had a follow-up imaging confirmation of infarct or a final clinical diagnosis of stroke.

Key Words: magnetic resonance imaging • stroke • transient ischemic attack • diffusion-weighted imaging • cerebral ischemia