Annual changes in the retention of [18F]THK-5117 in AD brains were seen in the middle and inferior temporal gyri and the fusiform gyrus, suggesting that tau pathology originates in the medial temporal cortex and accumulates laterally.47 Reports of [18F]THK-5117 in parkinsonian disorders have not been published; however, due to the possible off-target binding in white matter, this radiotracer may not be optimal for imaging disorders such as PSP and CBD, which present with white matter tau pathology. This evidence concerns the gene MAPT and parkinsonian disorder.