What are the possible causes of t2 hyperinensities on an mri of the brain (aside from ms)?

Non specific: Migraine, hypertension, antiphosphipid syndrome, sjogren, vitamin B12 deficiency, all infectious, vasculitic conditions--or just old age--depending if periventricular and affecting corpus callosum, their number, distribution, age of the patient, enhencement, you can guess---this is very frequent clinical question.

Many perhaps: You describe the presence of leukoariosis, which depending on quantity and location may be a marker for ms, migraine, prior head trauma, "hardening of the arteries"/angiopathy, vasculitis, and even benign coincidental lesions of unclear etiology. However, just to be clear, ms can start with maybe 1 solitary lesion initially, and over a 14 yr history, perhaps 60% of some pts will prove to have ms.