Potential Use of 18F-THK5351 PET to Identify Wallerian Degeneration of the Pyramidal Tract Caused by Cerebral Infarction.

A 41-year-old man underwent F-THK5351 PET 2 years after a right middle cerebral artery infarction. F-THK5351 PET imaging revealed intense radioligand uptake along the ipsilateral pyramidal tract from the corona radiata to the medulla; intense uptake changed from the right side to the left side with descending axial sections at the level of the pyramidal decussation. F-THK5351 reportedly binds to monoamine oxidase B, which is highly expressed in astrocytes, suggesting that F-THK5351 concentrates in the lesion where gliosis occurs. Hence, in this case, F-THK5351 uptake may represent Wallerian degeneration accompanied with gliosis in the ipsilateral pyramidal tract.