18F-THK5351 PET Can Identify Core Lesions in Different Amyotrophic Lateral Sclerosis Phenotypes

Two patients with different amyotrophic lateral sclerosis (ALS) phenotypes underwent 18F-THK5351 PET to visualize lesions undergoing astrogliosis by measuring monoamine oxidase B activity. Patient 1 was a 57-year-old man with flail leg syndrome. Elevated uptake was observed inside the motor cortex, corresponding to the leg area in a cortical homunculus. Patient 2 was a 64-year-old man with ALS-frontotemporal dementia semantic variant. Elevated uptake was observed around the left anterior temporal lobe. Both core lesions were consistent with their respective neurological features. Hence, 18F-THK5351 PET is a useful technique to assess ALS pathophysiology by visualizing the core lesions.