Objective: There is still a lack of sensitive and specific biological markers for the (differential) diagnosis of dementia. In this prospective study, we set out to evaluate correlations between antemortem ‘clinical diagnosis’ based on history, clinical and, neuropsychological examination and structural neuroimaging and postmortem neuropathological diagnosis. In addition, we specifically addressed the question whether perfusion SPECT has additional diagnostic value to the mere clinical diagnosis. Moreover, we evaluated whether structural imaging is only useful for exclusion of disorders that mimic dementia or whether it yields diagnostic information in relation to dementia.
Design: The study population was prospectively selected based on neuropathological examination of the brains of patients, who had presented to our Memory Clinic and who had been diagnosed clinically as having dementia. Retrospectively, diagnoses were made with consensus by two specialists in psychogeriatry based on clinical data, SPECT-images and CT-protocol and were afterwards correlated to neuropathological diagnoses.
Materials and methods: Subjects underwent full clinical work-up including structural neuroimaging and were subjected to Tc99-HMPAO or ECD perfusion brain SPECT. More than hundred cases were enrolled. Etiological diagnoses were in decreasing order of frequency: Dementia of the Alzheimer Type (DAT), Vascular Dementia, Mixed Dementia, Diffuse Lewy Body Disease, Frontotemporal dementia, and other.
Results: While results on more than hundred cases will be presented during the symposium, we only report in this abstract our preliminary observations involving 43 subjects. Overall, the clinical diagnosis was correct in 63%, the SPECT diagnosis in 56%, the combination clinical-SPECT in 58%, the CT-protocol in 33%, the combination clinical-CT in 51%. Apart from the result for CT, none of these percentages were significantly different. Concerning the subpopulatoin of DAT patients versus non-DAT patients, the clinical diagnosis had a sensitivity of 81%, a specificity of 65%; for SPECT the sensitivity was 88,5%, the specificity 35%; for CT the sensitivity was 31%, the specificity 76,5%. Only the sensitivity of CT was significantly different from clinical diagnosis and SPECT.
Conclusion: The correlation between antemortem and postmortem in the preliminary evaluation of 43 subjects did not differ significantly for clinical diagnosis and SPECT alone, or the combination of clinical and SPECT diagnosis. CT-scan, as applied in clinical practice, is only apt to exclude structural lesions, that can cause dementia. The sensitivity for the diagnosis of DAT was high for clinical diagnosis and SPECT and comparable with other studies. As blinded SPECT rating is still in progress, we will present the final results of this prospective study of more than hundred patients at the 11th International IPA congress. This data set will allow us to further address the additional (differential) diagnostic value of SPECT in a large variety of dementia syndromes.
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