The 18F-FDG PET cingulate island sign and comparison to 123I-beta-CIT SPECT for diagnosis of dementia with Lewy bodies.
Neuroimaging is increasingly used to supplement the clinical diagnosis of dementia with Lewy bodies (DLB) by showing reduced occipital metabolism and perfusion and reduced striatal dopaminergic innervation. We aimed to optimize the interpretation of (18)F-FDG PET images for differentiating DLB from Alzheimer disease (AD) and to compare the results with dopamine transporter imaging using (123)I-beta-carbomethoxy-3ss-(4-iodophenyl)tropane ((123)I-beta-CIT) SPECT.


METHODS
Fourteen subjects with a clinical diagnosis of DLB and 10 with AD underwent both (18)F-FDG PET and (123)I-beta-CIT SPECT. Four DLB and 1 AD diagnoses were subsequently confirmed at autopsy. Diagnostic accuracy was calculated for visual interpretation by 3 readers of standard 3-plane and stereotactic surface projection (18)F-FDG PET images, receiver-operating-characteristic analysis of regional (18)F-FDG uptake, and a cutoff value for the striatal-to-occipital binding ratio of beta-CIT defined by receiver-operating-characteristic analysis.


RESULTS
Visual interpretation of 3-plane (18)F-FDG PET images had a sensitivity of 83% and specificity of 93% for DLB, slightly higher than the results with the stereotactic surface projection images. Regionally, hypometabolism in the lateral occipital cortex had the highest sensitivity (88%), but relative preservation of the mid or posterior cingulate gyrus (cingulate island sign) had the highest specificity (100%). Region-of-interest analysis revealed that occipital hypometabolism and relative preservation of the posterior cingulate both had a sensitivity of 77% and specificity of 80%. beta-CIT achieved 100% accuracy and greater effect size than did (18)F-FDG PET (Cohen d = 4.1 vs. 1.9).


CONCLUSIONS
Both (18)F-FDG PET and (123)I-beta-CIT SPECT appear useful for the diagnosis of DLB, although the latter provides more robust results. The cingulate island sign may enhance the specificity of (18)F-FDG PET.
Lim
Seok Ming
SM
Department of Nuclear Medicine and Centre for PET, Austin Health, Victoria, Australia.
Katsifis
Andrew
A
Villemagne
Victor L
VL
Best
Rene
R
Jones
Gareth
G
Saling
Michael
M
Bradshaw
Jennifer
J
Merory
John
J
Woodward
Michael
M
Hopwood
Malcolm
M
Rowe
Christopher C
CC
D000368:Aged; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000378:metabolism; D001344:Autopsy; D003042:Cocaine / Q000031:analogs & derivatives*; D015331:Cohort Studies; D003937:Diagnosis, Differential; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism; D005260:Female; D019788:Fluorodeoxyglucose F18; D006179:Gyrus Cinguli / Q000000981:diagnostic imaging*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D020961:Lewy Body Disease / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D008297:Male; D049268:Positron-Emission Tomography; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013194:Staining and Labeling; D015899:Tomography, Emission-Computed, Single-Photon
D050483:Dopamine Plasma Membrane Transport Proteins; D019788:Fluorodeoxyglucose F18; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; D003042:Cocaine