Do lesions seen on diffusion-weighted imaging affect the outcome after stroke

This paper studied whether a lesion seen on magnetic resonance imaging with diffusion-weighting in patients with stroke is associated with worse outcomes. 

Magnetic resonance imaging (MRI) is a procedure that uses magnetic fields to look at structures in the body. Diffusion-weighted imaging is a form of magnetic resonance imaging. MRI with diffusion weighting is recommended for the diagnosis of stroke (not enough blood to the brain). It can detect more ischemic stroke lesions (damage or injury due to lack of blood supply). It is suggested that patients who don’t have a lesion seen on MRI may have better prognosis than patients with a lesion. 

Patients with stroke were studied. These patients underwent a brain MRI scan with diffusion-weighted imaging and were followed-up for 1 year. They also had an MRI scan after this 1 year. Of the 264 patients who had a stroke, 29% of patients had no lesion seen at the start of the study. Most of the lesions were seen on diffusion-weighted imaging. 

Patients with lesions seen on diffusion-weighted imaging were more likely to have narrowing of the carotid arteries, irregular heart-beat, and more severe stroke. Patients with no lesions seen on diffusion-weighted imaging were more likely to have reduced blood supply to the heart or a previous stroke. They were more likely to be scanned later.

198 patients were scanned after 1 year. Patients without lesion seen at the start were just as likely to have persistent symptoms, brain impairment, or another stroke during follow-up as patients who had a lesion seen on diffusion-weighted imaging. In addition, 14% of participants with a lesion on diffusion-weighted imaging had a new lesion seen on 1-year follow-up MRI. On the other hand, 2% of patients who did not have a lesion on diffusion-weighted imaging had a new lesion seen on 1 year follow-up MRI. 

The authors concluded that nearly one third of patients did not have a lesion seen on diffusion-weighted imaging. Patients with no lesion seen on diffusion-weighted imaging did not have better outcomes than patients with a lesion. 

Talk to your doctor about preventing stroke from occurring in the future, even if there are no lesions seen on diffusion-weighted imaging.