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(Stroke. 2004;35:e72.)
© 2004 American Heart Association, Inc.

Letters to the Editor

How Much Should One Rely on Computed Tomography in Patients with TIA in the Era of Diffusion-Weighted Magnetic Resonance Imaging?

Stroke Service, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

We read with great interest the paper by Douglas et al in Stroke.¹ The authors report that the 90-day risk of stroke in transient ischemic attack (TIA) patients with a new infarction on CT is higher than patients with normal CT. This is an important piece of information, coming out almost 20 years after the original report by Waxman and Toole that first introduced the concept that clinically transient events are not necessarily transient in the brain.² TIAs often leave footprints, small islands of permanent injury, on the brain. Nonetheless, CT is not the best available technique to pursue such footprints of ischemia. Diffusion-weighted imaging (DWI) offers much greater power in classifying patients who have ischemia as the cause of their reversible neurological deficit. Though more expensive, the cost-effectiveness of MRI might rest in using it to prevent stroke in this subgroup with TIA-associated infarction.

Recent studies using DWI reveal that infarctions in patients with TIAs are often very small.^3–5 Rovira et al reported that the lesion size ranged from 2 to 40 mm (mean=15 mm) in their 39 patients with TIA.⁴ A second study reported that infarction size was less than 15 mm in diameter in 85% of 27 TIA patients with a positive DWI, of which 83% were punctate (<5 mm).⁵ These small infarctions will be missed by CT and even by conventional magnetic resonance images (T1-, T2-, FLAIR-weighted). These conventional techniques are limited by lower lesion-to-background signal ratio compared with DWI. Diffusion-weighted imaging . . . [Full Text of this Article]

S. Claiborne Johnston, MD, PhD Vanja Douglas, BS

Neurology Department, University of California, San Francisco, California

This article has been cited by other articles:

				R. Sciolla, F. Melis, and for the SINPAC Group Rapid Identification of High-Risk Transient Ischemic Attacks: Prospective Validation of the ABCD Score Stroke, February 1, 2008; 39(2): 297 - 302. [Abstract] [Full Text] [PDF]