Scan immediately for stroke using MRI when possible

EDITOR—We agree with Wardlaw and Farrall that a strategy to scan all patients immediately for stroke is optimal.1 They say that magnetic resonance imaging (MRI) has some perceived disadvantages in imaging acute stroke, despite its advantages.

In our experience, the advantages of an early imaging strategy with magnetic resonance imaging outweigh its disadvantages. By combining diffusion weighted imaging with a T2 weighted gradient sequence the sensitivity for both infarction and haemorrhage is high (figure). The room times for this technique are similar to computed tomography, and most patients can be scanned by magnetic resonance imaging.2 The interpretation of the scans is more straightforward and their reproducibility high.3

Top: MRI T2 gradient image showing intracerebral haemorrhage as low signal due to deoxyhaemoglobin susceptibility. Bottom: Diffusion MRI image (B1000) showing acute infarction as high signal (acquisition time 1 minute

In a British district general hospital where there may not be ready access to a specialist neuroradiologist or stroke specialist, we believe that magnetic resonance imaging with diffusion weighted imaging carries advantages in ease of interpretation, with a higher sensitivity and specificity than computed tomography, particularly in patients in whom the diagnosis is less obvious.