Brief Answer:
Not dangerous.

Detailed Answer:
Hello! I read your question carefully and I understand your concern in front of unknown medical terms.

I'll start right away by saying that those findings do not indicate anything dangerous, you should rest assured about that.

Every human being undergoes some changes with age, the brain and its blood vessels included. These changes include some narrowing of the blood vessels more noticeable in the smallest vessels which have the smallest caliber. This is what the term "microangiopathy" refers to, scattered changes in the brain matter due to narrowing of blood vessels.
The term chronic means it is something which has happened slowly over many years, as I said part of aging.
The supratentorial white matter refers to the location of these changes, it is the usual location where these changes happen first, nothing uncommon about that.

Now of course it would be preferable if you had no such changes at all, but as I said almost all have some changes, some sooner some a little later as they age. It would have been worrying if the report said that the changes were advanced, but it says they are minimal, so nothing alarming, it is only a coincidental finding, doesn't cause any symptoms.

So you do not need to do anything particular about the report. The only thing is pay attention to conditions which might influence there vessel changes, accelerate them in time. Such conditions (if present) are high blood pressure, diabetes, smoking, high cholesterol, sedentary lifestyle should be addressed, otherwise nothing to be done about that.

I remain at your disposal for other questions.

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