What are tiny foci of hyperintense signal at periventricular are subcortical white matter less than 0.5?

Answer 1

these are signs of Multiple Sclerosis on MRI.

Answer 2

Well, it looks like a report for a MRI (magnetic resonance imaging) of the head. The radiologist reports a possible mass (i.e. a tiny foci of hyperintense signal) located near the ventricles (i.e. areas of the brain with cerebro spinal fluid) of the brain. The mass is 0.5 in length; you did not include the units but it is most likely 0.5 cm (medical reports usually use the metric system). Important, the radiologist is not reporting a mass but rather that there are findings on the MRI that suggest that there is one.