Differential diagnosis of Alzheimer's disease with PET.
PET studies have demonstrated bilateral temporo-parietal hypoperfusion and hypometabolism in probable and definite Alzheimer's disease (AD), a pattern that may help differentiate AD from other dementias.


METHODS
To evaluate the diagnostic power of cerebral metabolic distribution patterns for "cortical" degenerative dementias, PET scans obtained from 129 patients referred for differential diagnosis of dementia were analyzed visually.


RESULTS
Sixty-five patients had a final clinical diagnosis of probable AD. Ninety-seven percent (97%) of those had abnormal metabolic scans and 94% showed a suggestive pattern of bilateral or unilateral temporo-parietal hypometabolism (with or without frontal involvement). Hypometabolism was unilateral in 23% of patients. Five subjects with a neuropathologically proven diagnosis of Alzheimer's disease had a suggestive metabolic pattern. One of those was an early case with frontal hypometabolism exceeding temporo-parietal involvement. Two patients with Alzheimer's-type dementia had isolated bilateral frontal hypometabolism.


CONCLUSIONS
This alternative metabolic pattern may correspond to a non-Alzheimer pathology occurring in 10%-20% of patients suffering from clinically probable Alzheimer's disease. Most of the patients with possible but atypical Alzheimer's-type dementia showed isolated bilateral frontal involvement. This metabolic pattern probably corresponds to different diseases, such as Pick's disease, frontal lobe dementia or progressive subcortical gliosis.
Salmon
E
E
Cyclotron Research Centre, Department of Neurology, University of Liege, Belgium.
Sadzot
B
B
Maquet
P
P
Degueldre
C
C
Lemaire
C
C
Rigo
P
P
Comar
D
D
Franck
G
G
D000544:Alzheimer Disease / Q000000981:diagnostic imaging*; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D003704:Dementia / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014055:Tomography, Emission-Computed