Amyloid imaging in distinguishing atypical prion disease from Alzheimer disease.
OBJECTIVE
To compare the in vivo uptake of two amyloid-binding PET agents, PIB and FDDNP, in human subjects with a prion protein (PrP) gene (PRNP) mutation that produces a clinical syndrome similar to Alzheimer disease (AD).


BACKGROUND
Amyloid imaging with specific PET ligands offers great promise for early detection and differential diagnosis of AD. Genetic forms of prion disease can present with clinical features that resemble AD, and at autopsy may show deposition of mutant PrP-amyloid. FDDNP binds to PrP-amyloid in postmortem human specimens, but has not been reported in vivo in prion disease. The ability of PIB to bind PrP-amyloid is not known.


METHODS
Two brothers with a 6 octapeptide repeat insertion mutation (6-OPRI) in the PRNP gene underwent clinical, structural MRI, and FDG-PET evaluations. One brother received a PIB-PET evaluation, while the other received an FDDNP-PET scan. PET results were compared with five normal subjects and five individuals with AD scanned with either agent.


RESULTS
PIB uptake was similar to controls in one brother, while FDDNP uptake was intermediate between AD and controls in the other brother.


CONCLUSIONS
Different amyloid-binding agents may have differential sensitivity to prion-related brain pathology. A combination of amyloid imaging agents may be useful in the diagnosis of early-onset dementia.
Boxer
A L
AL
Memory and Aging Center, Department of Neurology, University of California, San Francisco, CA 94143-1207, USA. aboxer@memory.ucsf.edu
Rabinovici
G D
GD
Kepe
V
V
Goldman
J
J
Furst
A J
AJ
Huang
S-C
SC
Baker
S L
SL
O'neil
J P
JP
Chui
H
H
Geschwind
M D
MD
Small
G W
GW
Barrio
J R
JR
Jagust
W
W
Miller
B L
BL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000235:genetics; D000682:Amyloid / Q000032:analysis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D009154:Mutation; D049268:Positron-Emission Tomography / Q000379:methods*; D017096:Prion Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000235:genetics
D000682:Amyloid