title: Diagnosing Alzheimer's disease in elderly, mildly demented patients: the impact of routine single photon emission computed tomography.
abstract: Based on the observation of bilateral temporoparietal hypoperfusion in Alzheimer's disease (AD), single photon emission computed tomography (SPECT) is advocated by some as a powerful diagnostic tool in the evaluation of demented patients. We studied whether routine brain SPECT in elderly, mildly demented outpatients increases the a priori diagnostic sensitivity and specificity of a careful clinical examination. 99mTc-HMPAO SPECT imaging was performed in 110 patients for a first evaluation for dementia. A semiquantitative measure of temporoparietal (TP) perfusion was calculated as the ratio of the activity in the temporoparietal cortex to activity in the cerebellum. A diagnosis of probable AD according to the McKhann criteria was made in 68 patients (mean age of 79.3 years) based on the results of a clinical examination, ancillary investigations and a 6-month follow-up. TP perfusion was significantly lower in AD patients than in 18 age-matched, non-demented controls. However, at a specificity of 89%, sensitivity was only 43% for detecting probable AD. The clinicians judged that SPECT had contributed to the final diagnosis in only 8% of the demented patients investigated. Routine brain SPECT in elderly, mildly demented outpatients does not contribute substantially to diagnostic accuracy after a careful clinical examination using current diagnostic criteria. Clinical guidelines have to be developed for the use of SPECT in patients with (suspected) dementia.
authors.affiliation: Department of Neurology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: W A
authors.initials: WA
authors.lastname: Van Gool
authors.forename: G J
authors.initials: GJ
authors.lastname: Walstra
authors.forename: S
authors.initials: S
authors.lastname: Teunisse
authors.forename: F M
authors.initials: FM
authors.lastname: Van der Zant
authors.forename: H C
authors.initials: HC
authors.lastname: Weinstein
authors.forename: E A
authors.initials: EA
authors.lastname: Van Royen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging*; D006801:Humans; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon