I get a pressure feeling in my head any time my head is lower than my heart. The position in a MRI tunnel would not put your head lower than your heart. There is no way they can position your head any higher because they need it to be in the proper location in the magnet and sensors.

I would not be concerned if this feeling is only when your head is lower than your heart.

You stats are fabulous. Count your blessings that you do not have higher blood pressure.