Management Impact of Imaging Brain Vesicular Monoamine Transporter Type 2 in Clinically Uncertain Parkinsonian Syndrome with 18F-AV133 and PET

Idiopathic Parkinson disease is a common neurodegenerative disorder for which misdiagnosis occurs in up to 30% of patients after initial assessment and in 10%-15% even after long-term follow-up. Vesicular monoamine transporter type 2 (VMAT2) imaging with PET allows assessment of the integrity of the presynaptic dopaminergic pathway. We investigated the management impact of VMAT2 imaging in patients with clinically uncertain Parkinsonian syndromes. Methods: Forty-seven patients with clinically uncertain Parkinsonian syndromes (mean age ± SD, 56.9 ± 14.9 y; age range, 21-80 y) were referred from movement disorder specialists. All participants underwent a 20-min PET acquisition 2 h after injection of 250 MBq of 18F-AV-133, and the resulting images were quantitatively assessed. Clinical impact was recorded as high, moderate, or low based on diagnosis and management questionnaires completed by the referring specialists before and after release of the PET results. Management impact was high if there was a change in diagnostic category, moderate if there was a change in medication, and low if there was no change. Results: VMAT2 PET changed the diagnosis in 11 (23%) and medication in 25 (53%) participants. Management impact was high in 23%, moderate in 38%, and low in 39% of the participants. High diagnostic confidence increased from 11% of patients to 80% after the release of the scan results. Conclusion:18F-AV-133 had substantial management impact in patients with clinically uncertain Parkinsonian syndromes. VMAT2 imaging with 18F-AV133 might improve diagnosis, prognosis, and appropriate use of medication, translating into better patient outcomes.