Sensitivity, specificity, and positive predictive value of technetium 99-HMPAO SPECT in discriminating Alzheimer's disease from other dementias.
Investigators have reported high sensitivity and specificity values for single photon emission computerized tomography (SPECT) when distinguishing Alzheimer's disease (AD) patients from normal elderly controls or from selected patient groups. The role of SPECT in identifying AD among unselected patients with memory complaints requires investigation. We examined 139 consecutive patients with 99Tc-HMPAO SPECT. NINCDS-ADRDA diagnoses were determined blind to SPECT results, and scans were read and classified by visual inspection blind to clinical diagnoses. Bilateral temporoparietal hypoperfusion (TP) occurred in 75% of probable, 65% of possible, and 45% of unlikely AD patients, yielding a sensitivity of 75% and a specificity of 52% when comparing probable AD versus unlikely AD groups. A positive predictive value of 78% was obtained based on a 69% prevalence of AD in our total clinic population. Patients with false-positive results included a variety of dementing illnesses; all patients with bilateral hypoperfusion had dementia. A pattern of TP on SPECT scans is seen in most patients with AD, but could be found in other dementias as well and cannot be regarded as specific to AD. Reduced TP perfusion discriminated between demented and nondemented individuals. Further strategies for SPECT interpretation that improve diagnostic specificity should be sought.
Masterman
D L
DL
Department of Neurology, University of California, Los Angeles School of Medicine 90095-1769, USA.
Mendez
M F
MF
Fairbanks
L A
LA
Cummings
J L
JL
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D003704:Dementia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D015140:Dementia, Vascular / Q000000981:diagnostic imaging / Q000503:physiopathology; D003937:Diagnosis, Differential; D004292:Dominance, Cerebral / Q000502:physiology; D006801:Humans; D015609:Organotechnetium Compounds; D010091:Oximes; D010296:Parietal Lobe / Q000098:blood supply / Q000000981:diagnostic imaging; D012016:Reference Values; D012039:Regional Blood Flow / Q000502:physiology; D012680:Sensitivity and Specificity; D019690:Technetium Tc 99m Exametazime; D013702:Temporal Lobe / Q000098:blood supply / Q000000981:diagnostic imaging; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data*
D015609:Organotechnetium Compounds; D010091:Oximes; D019690:Technetium Tc 99m Exametazime