What Does MRI Showing Chronic Ischemic Leukoencephalopathy Mean?

My grandmother is 93 yoa and just had an MRI. The results state FLAIR and T2 images show patchy and confluent hyperintensity of the periventricular and subcortical white matter consistent with chronic ischemic leukoencephalopathy. The craniovertebral junction and skill base are unremarkable. There is enlargement of the ventricular system and cortical fissures and sulci consistent with advanced cerebral atrophy, particularly temporal lobes. Could you provide an explanation in laymen's terms? Thank you.