Role of Dual-Phase 18F FP-CIT PET for Subtyping of Multiple System Atrophy

Area of Science:

• Neurology
• Nuclear Medicine
• Neuroimaging

Background:

• Multiple system atrophy (MSA) is a progressive neurodegenerative disorder with cerebellar (MSA-C) and parkinsonian (MSA-P) subtypes.
• Current dual-tracer PET imaging (18F FDG and DAT scans) is valuable but resource-intensive.
• Dual-phase 18F FP-CIT PET offers a cost-effective alternative by combining perfusion-like and DAT signals.

Purpose of the Study:

• To assess the diagnostic and phenotypic utility of dual-phase 18F FP-CIT PET in early-stage MSA.
• To differentiate between MSA subtypes using imaging patterns.
• To correlate imaging findings with clinical severity and MRI data.

Main Methods:

• Retrospective study of 39 early-stage MSA patients undergoing dual-phase 18F FP-CIT PET.
• Early-phase (0-10 min) assessed perfusion-like uptake; delayed-phase (90 min) measured DAT uptake.
• PET patterns (normal, presynaptic, trans-synaptic) were classified and compared with clinical subtypes, MRI, and severity scores.

Main Results:

• Striatal PET patterns significantly differed between MSA subtypes (P<0.001), with trans-synaptic patterns in MSA-P and normal/presynaptic in MSA-C.
• Early-phase putaminal abnormalities on PET were observed in all patients with MRI-confirmed putaminal abnormalities.
• Asymmetric cerebellar perfusion on early PET was higher in MSA-C than MSA-P (P<0.001), and levodopa responsiveness correlated with trans-synaptic PET patterns.

Conclusions:

• Dual-phase 18F FP-CIT PET effectively captures perfusion and DAT status in a single session for early MSA.
• This technique aids in MSA subtype classification and disease severity assessment.
• Asymmetric cerebellar perfusion may aid in differentiating MSA subtypes, particularly in ataxic presentations.