A model of the temperature rise in the head due to magnetic resonance imaging procedures.

A simple model of power deposition in the head is presented in which the temperature increase in the head in general and, in particular, in a small spherical region of unperfused tissue contained within the head is calculated. The result of the calculation provides a limit on the SAR needed to ensure that a 1°C temperature rise is not exceeded for unperfused spheres of different sizes, imaging sessions of different lengths of time, and different blood flow rates to the head. The model assumes that the rest of the body during a head imaging session can act as a perfect heat sink at 37°C. The model suggests that current practices in MRI imaging will not cause a temperature rise in the center of small unperfused regions such as the eye of more than 1°C. © 1989 Academic Press, Inc.