Teaching Neuroimages: Obscured Cerebral Infarction on MRI

Excerpt

An 87-year-old man presented with dysarthric speech for 1 day and underwent magnetic resonance imaging (MRI) using a 3-Tesla MRI scanner. Diffusion-weighted imaging (DWI) using a b-value of 1000 s/mm² showed a small abnormality with high intensity on the left side of the deep white matter (Fig. 1a). The DWI using a b-value of 1500 s/mm² and different diffusion times showed that the infarction was obscured in some images (Fig. 1b) and clear in others (Fig. 1c). The effective diffusion time was 8.5 ms for the image shown in Fig. 1b and 47.3 ms for the image shown in Fig. 1c. The infarction was shown clearly in DWI and T2-weighted images obtained during an MRI examination that was completed 2 days after the initial examination (Fig. 1d).

…