Fluorodeoxyglucose-positron emission tomography in the differential diagnosis of early-onset dementia: a prospective, community-based study.
BACKGROUND
The aim of this study was to evaluate the diagnostic accuracy of positron emission tomography (PET) using F18 fluorodeoxyglucose (FDG) in the differential diagnosis of early-onset Alzheimer's disease (AD) and other dementias in a community-dwelling population.


METHODS
A prospective sample of 102 individuals presenting consecutively to a primary care centre for examination of suspected early-onset dementing diseases. The mean age of symptom onset of dementia in our patients was 60.06 +/- 4.28 years (mean +/- 1 SD, 95% lower confidence intervals (CI) 54.75, upper 63.37). Patients were evaluated using standard clinical criteria for the diagnosis of dementia. Functional neuroimaging data was obtained and nuclear medicine physicians blind to the clinical diagnosis generated FDG-PET diagnoses. Final clinical diagnoses based on all available data were then established and compared against PET diagnoses.


RESULTS
Forty-nine patients received a final clinical diagnosis of early-stage AD (MMSE score 20.97 +/- 5.10). There were 29 non-AD demented patients, 11 depressed patients and a miscellaneous group of 13 patients. Among patients with AD, the sensitivity and specificity of FDG-PET was 78% (95% CI: 66-90%) and 81% (95% CI: 68-86%), respectively. The positive likelihood ratio (PLR) for a FDG-PET scan positive for the diagnosis of AD was 4.11 (95% CI: 2.29-7.32) and negative likelihood ratio (NLR) for a negative FDG-PET scan in the absence of AD was 0.27 (95% CI: 0.16-0.46). The pre-test probability was 48% and post-test probability was 79.02%. The specificity of FDG-PET in the differential diagnosis of other dementias, including frontotemporal dementia, was greater than 95%. Recruitment methods in this study provide a sample that may be more representative of patients in the general population and indicate that FDG-PET imaging can contribute to the diagnosis of AD in younger adults with major increases in the positive likelihood rates and post-test probability.


CONCLUSIONS
The high specificity of FDG-PET suggests this technique might help in the diagnosis of frontotemporal dementia and other forms of early-onset dementia.
Panegyres
Peter K
PK
Neurodegenerative Disorders Research, 185 York St, Subiaco WA, Australia. publications@panegyres.com.au
Rogers
Jeffrey M
JM
McCarthy
Michael
M
Campbell
Andrew
A
Wu
Jing Shan
JS
D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology; D003704:Dementia / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011446:Prospective Studies
D019788:Fluorodeoxyglucose F18
Prog Neuropsychopharmacol Biol Psychiatry. 2001 Feb;25(2):447-56
11294488
Brain. 2007 Oct;130(Pt 10):2616-35
17704526
Eur Neurol. 2001;45(1):19-27
11150836
Am J Alzheimers Dis Other Demen. 2008 Apr-May;23(2):184-91
18192445
Neurology. 1993 Feb;43(2):250-60
8094895
J Nucl Med. 2000 Nov;41(11):1920-8
11079505
J Nucl Med. 1998 Nov;39(11):1875-8
9829574
Exp Neurol. 2000 Apr;162(2):247-56
10739631
Brain Lang. 2005 Jul;94(1):54-60
15896383
J Nucl Med. 2005 Jun;46(6):936-44
15937303
Am J Alzheimers Dis Other Demen. 2007 Feb-Mar;22(1):48-56
17534002
N Engl J Med. 2003 Oct 16;349(16):1535-42
14561797
Clin Positron Imaging. 1999 May;2(3):119-130
14516535
Eur J Neurol. 2000 Mar;7(2):133-44
10809933
Ann Neurol. 2001 Sep;50(3):358-65
11558792
Neuroimage. 2002 Sep;17(1):302-16
12482085
Radiology. 1996 Mar;198(3):837-43
8628880
J Clin Epidemiol. 1991;44(8):763-70
1941027
Neurology. 1998 Dec;51(6):1546-54
9855500
Ann Emerg Med. 1999 Jan;33(1):85-91
9867892
J Cereb Blood Flow Metab. 2006 Sep;26(9):1213-21
16525414
J Nucl Med. 1995 Jul;36(7):1238-48
7790950
JAMA. 2001 Nov 7;286(17):2120-7
11694153
Neurology. 2001 May 8;56(9):1143-53
11342678
J Neurol Neurosurg Psychiatry. 2003 Oct;74(10):1371-81
14570828
J Neurol. 2002 Sep;249(9):1263-7
12242551
Dement Geriatr Cogn Disord. 2005;20(2-3):63-70
15908747
Alzheimer Dis Assoc Disord. 1995 Spring;9(1):6-16
7605624
Neurology. 1996 Nov;47(5):1113-24
8909416
Neuroimage. 2004 May;22(1):409-18
15110034
Neurology. 1984 Jul;34(7):939-44
6610841
Exp Neurol. 2005 Feb;191 Suppl 1:S95-S103
15629765
J Nucl Med. 1997 May;38(5):797-802
9170449
Neurology. 1994 Nov;44(11):2203-6
7969988
Radiology. 2004 Apr;231(1):73-80
15068942
Eur Neurol. 2008;59(1-2):31-7
17917455
Alzheimer Dis Assoc Disord. 2007 Oct-Dec;21(4):S8-S11
18090430
Neurology. 1992 Feb;42(2):329-32
1736160
Acta Psychiatr Scand. 2002 Jul;106(1):35-44
12100346
J Nucl Med. 2005 Feb;46(2):233-9
15695781
Eur J Nucl Med. 1994 Oct;21(10):1052-60
7828614
J Nucl Med. 2000 Nov;41(11):1929-32
11079506
Int J Psychophysiol. 2000 Jul;37(1):87-98
10828377
Semin Nucl Med. 1992 Oct;22(4):233-46
1439869