A clinical role for 99mTc-HMPAO SPECT in the investigation of dementia?
OBJECTIVE
To provide the clinician with a guide to the clinical utility of 99mTc-HMPAO single photon emission computed tomography (SPECT) and to the interpretation of specific test results in the differential diagnosis of dementia.


METHODS
Three hundred and sixty three patients with dementia were studied prospectively for a median three (range 1-6) years and classified into disease groups on the basis of established clinical criteria. The degree to which different patterns of cerebral blood flow (CBF) abnormality found on 99mTc-HMPAO SPECT imaging at the time of initial patient presentation modified clinical diagnoses was determined by calculating the likelihood ratios for pairwise disease group comparisons. The optimal clinical usage of 99mTc-HMPAO SPECT was determined by calculating the percentage of significant test results for each pairwise disease group comparison.


RESULTS
Bilateral posterior CBF abnormality was found to significantly increase the odds of a patient having Alzheimer's disease as opposed to vascular dementia or frontotemporal dementia. Bilateral anterior CBF abnormality significantly increased the odds of a patient having frontotemporal dementia as opposed to Alzheimer's disease, vascular dementia, or Lewy body disease. "Patchy" CBF changes significantly increased the odds of a patient having vascular dementia as opposed to Alzheimer's disease. Unilateral anterior, unilateral anterior plus unilateral posterior, and generalised CBF abnormality failed to contribute to the differentiation of any of these forms of dementia.


CONCLUSIONS
99mTc-HMPAO SPECT was found to be most useful in distinguishing Alzheimer's disease from vascular dementia and fronto temporal dementia, and least useful in differentiating between Alzheimer's disease and Lewy body disease, and between vascular dementia, frontotemporal dementia, and progressive aphasia. It is suggested that CBF SPECT should be used selectively and as an adjunct to clinical evaluation and CT.
Talbot
P R
PR
Department of Neurology, Manchester Royal Infirmary, UK.
Lloyd
J J
JJ
Snowden
J S
JS
Neary
D
D
Testa
H J
HJ
D000368:Aged; D000544:Alzheimer Disease / Q000000981:diagnostic imaging; D018888:Aphasia, Primary Progressive / Q000000981:diagnostic imaging; D003704:Dementia / Q000145:classification / Q000000981:diagnostic imaging* / Q000209:etiology; D015140:Dementia, Vascular / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010300:Parkinson Disease / Q000000981:diagnostic imaging; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon
D019690:Technetium Tc 99m Exametazime