Combined striatal binding and cerebral influx analysis of dynamic 11C-raclopride PET improves early differentiation between multiple-system atrophy and Parkinson disease.
Striatal dopamine D(2) receptor (D2R) PET has been proposed to differentiate between Parkinson disease (PD) and multiple-system atrophy with predominant parkinsonism (MSA-P). However, considerable overlap in striatal D(2) binding may exist between PD and MSA-P. It has been shown that imaging of neuronal activity, as determined by metabolism or perfusion, can also help distinguish PD from MSA-P. We investigated whether the differential diagnostic value of (11)C-raclopride PET could be improved by dynamic scan analysis combining D2R binding and regional tracer influx.


METHODS
(11)C-raclopride PET was performed in 9 MSA-P patients (mean age +/- SD, 56.2 +/- 10.2 y; disease duration, 2.9 +/- 0.8 y; median Hoehn-Yahr score, 3), 10 PD patients (mean age +/- SD, 65.7 +/- 8.1 y; disease duration, 3.3 +/- 1.5 y; median Hoehn-Yahr score, 1.5), and 10 healthy controls (mean age +/- SD, 61.6 +/- 6.5 y). Diagnosis was obtained after prolonged follow-up (MSA-P, 5.5 +/- 2.0 y; PD, 6.0 +/- 2.3 y) using validated clinical criteria. Spatially normalized parametric images of binding potential (BP) and local influx ratio (R(1) = K(1)/K'(1)) of (11)C-raclopride were obtained using a voxelwise reference tissue model with occipital cortex as reference region. Stepwise forward discriminant analysis with cross-validation, with and without the inclusion of regional R(1) values, was performed using a predefined volume-of-interest template.


RESULTS
Using conventional BP values, we correctly classified 65.5% (all values given with cross-validation) of 29 cases only. The combination of BP and R(1) information increased discrimination accuracy to 79.3%. When healthy controls were not included and patients only were considered, BP information alone discriminated PD and MSA-P in 84.2% of cases, but the combination with R(1) data increased accuracy to 100%.


CONCLUSIONS
Discriminant analysis using combined striatal D2R BP and cerebral influx ratio information of a single dynamic (11)C-raclopride PET scan distinguishes MSA-P and PD patients with high accuracy and is superior to conventional methods of striatal D2R binding analysis.
Van Laere
Koen
K
Division of Nuclear Medicine, Leuven University Hospital and Katholieke Universiteit Leuven, Leuven, Belgium. koen.vanlaere@uzleuven.be
Clerinx
Kristien
K
D'Hondt
Eduard
E
de Groot
Tjibbe
T
Vandenberghe
Wim
W
D000368:Aged; D001692:Biological Transport; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation; D003937:Diagnosis, Differential; D016002:Discriminant Analysis; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D017072:Neostriatum / Q000378:metabolism* / Q000503:physiopathology; D010300:Parkinson Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D049268:Positron-Emission Tomography; D020891:Raclopride / Q000378:metabolism*
D020891:Raclopride