Figure 1. Regions-of-interest over each masticatory muscle. Registered MR (left) and PET (right) images at the same slice level in the same subject. Black-white and color scales depict the MR signal intensity and the accumulation of FDG, respectively. Regions-of-interest are color-coded as follows: pink and yellow = right and left masseter muscles, purple and blue = right and left temporal muscles, green and orange = right and left medial pterygoid muscles, white and red = right and left lateral pterygoid muscles.