INTERPRETATION VARIABILITY OF (18)FDG-POSITRON EMISSION TOMOGRAPHY STUDIES IN DEMENTIA

RATIONALE AND OBJECTIVES. Functional imaging studies such as F-18-fluo ro-18-labeled-deoxyglucose-positron emission tomography ((18)FDG-PET) are being used increasingly in the evaluation of patients with dementi a, The authors evaluate inter- and intraobserver interpretation agreem ent in a diverse group of patients with clinically diagnosed dementia and subjective memory complaints, as well as two healthy control subje cts. METHODS. Ninety-sis patients with clinical diagnoses of probable Alzheimer's disease (n = 18), possible Alzheimer's disease (n = 33), d ementia (n = 26), and mild memory impairment (n = 17), as well as two healthy control subjects were studied using (18)FDG-PET. Three observe rs graded all studies for regional (18)FDG uptake in the temporal, par ietal, and frontal regions bilaterally, The studies also were interpre ted for the presence of bilateral temporoparietal hypometabolism, whic h typically is present in Alzheimer's disease, The kappa statistic was used to determine intra- and interobserver agreement for regional (18 )FDG uptake and bilateral temporoparietal hypometabolism. RESULTS. The re was excellent intraobserver (kappa = .56, P < 0.0005) and interobse rver (kappa = .51, P < 0.0005) interpretation agreement for bilateral temporoparietal hypometabolism. There also was excellent intraobserver (kappa = .61, P < 0.000) and interobserver (kappa = .55; P < 0.000) i nterpretation agreement of regional (18)FDG; uptake, Interobserver agr eement was extremely high in those patients who were considered clinic ally to hale possible (kappa = .42, P < 0.001) or probable (kappa = .4 2, P < 0.01) Alzheimer's disease. CONCLUSIONS. Results confirm that bi lateral temporoparietal hypometabolism is the metabolic abnormality as sociated with the diagnosis of probable Alzheimer's disease, Furthermo re, intra- and interobserver agreement of visual interpretation of (18 )FDG-PET images indicates that (18)FDG-PET is acceptable as an imaging technique in tile clinical evaluation of the dementia patient.