What does it mean when a MRI (brain) says there are ten small t2 hyperintense foci within the periventricular deep white matter?

Why was MRI done? The spots could well be associated with prior head injury , migraine, cigarette smoking, hypertension, but could be c/w ms. Return to your doctor and spend some sufficient time to clarify significance in your case.
MRI brain. Hyperintensity or bright spots in the t2 white matter of the brain is a nonspecific finding that may indicate low blood flow or loss of myelin (insulation) on the coverings of the nerves in the brain. This is a part of normal aging but can be seen in neurological diseases (multiple sclerosis) and psychiatric conditions. See your neurologist to explain the findings on the MRI scan.