Acute occipital demyelinating lesion appearing as an infarct on diffusion magnetic resonance imaging.

PURPOSE: To report a case of a 27-year-old woman who presented with an acute right homonymous visual field deficit due to demyelination diagnosed by postprocessing analysis of the magnetic resonance imaging (MRI).

DESIGN

Observational case report.

METHODS

Magnetic resonance imaging analysis with an exponential diffusion-weighted imaging.

RESULTS

On MRI, a left occipital lesion with mild enhancement after gadolinium infusion on the T1-weighted image, bright signal with some mass effect on the T2-weighted image, and the diffusion-weighted imaging suggested a diagnosis of an acute infarct. With the use of the exponential image technique, the T2 hyperintense signal present on the diffusion study was almost completely eliminated, changing the diagnosis and treatment plan. Subsequent examinations and MRI confirmed the diagnosis of demyelinating disease.

CONCLUSIONS

In diseases such as cerebral ischemia and demyelination, MRI diffusion is often abnormal because such diseases modify the integrity of central nervous system structures. A technique that subtracts the T2 contribution to the diffusion-weighted imaging analysis supported a diagnosis of an acute demyelinating episode that was subsequently confirmed.