Case 1

This is an axial non-contrast CT brain study showing bilateral symmetrical low attenuation in the subcortical white matter in the posterior regions within the parietal and occipital lobes- the gray / white matter interface is preserved. This finding indicates the presence of vasogenic oedema. There is also incidental physiological calcification in the right basal ganglia.

While there is a wide differential diagnosis for vasogenic oedema including neoplastic, infectious / inflammatory, and hypertensive / vascular causes, the distribution in this case is suggestive of PRES (posterior reversible encephalopathy syndrome). I would discuss this case with the referring physician and recommend obtaining an MRI brain in the first instance. I would also ask about the clinical picture – which is typically acute neurological symptoms - to correlate with the suspected diagnosis.

This is an MRI brain study showing high T2 and FLAIR signal intensity in the subcortical white matter, in the same previously mentioned distribution. The signal is high on DWI and ADC, indicating shine through which is in keeping with oedema. No underlying lesions are detected. These findings are characteristic of PRES. I would convey these findings to the referring physician urgently.

There is also serpiginous, linear T1 hyperintensity running along the cortex in the involved regions of the cerebrum, indicating cortical laminar necrosis. The scattered deep white matter FLAIR hyperintensities are most likely due to chronic small vessel arteriopathy.