What is mild chronic small vessel cerebral ischemic disease,but without focal or acute cerebral abnormality?

[Hooter24]

Findings from recent multiple MR imaging sequences of the brain were performed with and without 20 cc IV contrast with the following findings:

There are mild foci of T2 dependent periventricular/subcortical white matter hyperintensity.  There is no evidence of cerebral mass mass effect, ferromagnetic blood products, increased diffusion-weighted signal, extracerebral collection, or abnormal contrast enhancement.

Please help me to understand the radiologist's impression.  Many thanks.