Objective: Numerous studies have suggested that temporoparietal hypoperfusi
on seen on brain imaging with SPECT may be useful in diagnosing AD during l
ife. However, these studies have often been limited by lack of pathologic v
alidation and unrepresentative samples. The authors performed this study to
determine whether SPECT imaging provides diagnostically useful information
in addition to that obtained from a clinical examination. Methods: Clinica
l data and SPECT images were collected prospectively, and patients were fol
lowed to autopsy. Clinical history, pathologic findings, and SPECT images w
ere each evaluated by raters blind to other features, and clinical and SPEC
T diagnoses were compared with pathologic diagnoses. The study population c
onsisted of 70 patients with dementia, followed to autopsy; 14 controls fol
lowed to autopsy; and 71 controls (no autopsy performed). The primary outco
me was the likelihood of a pathologic diagnosis of AD given a positive clin
ical diagnosis, a positive SPECT diagnosis, and bath. Results: When all par
ticipants (patients and controls) were included in the analysis, the clinic
al diagnosis of "probable" AD was associated with an 84% likelihood of path
ologic AD. A positive SPECT scan raised the likelihood of AD to 92%, wherea
s a negative SPECT scan lowered the likelihood to 70%. SPECT was more usefu
l when the clinical diagnosis was "possible" AD, with the likelihood of 67%
without SPECT, 84% with a positive SPECT, and 52% with a negative SPECT. S
imilar results were found when only patients with dementia were included in
the analysis. Conclusions: In the evaluation of dementia, SPECT imaging ca
n provide clinically useful information indicating the presence of AD in ad
dition to the information that is obtained from clinical evaluation.