Autopsy as Gold Standard in FDG-PET Studies in Dementia

Abstract

Cognitive impairment is an area of great concern in the media and for clinicians around the world. In the past 20 years, many articles have been written about positron emission tomography (PET) imaging with F18-fluorodeoxyglucose (FDG), either to investigate its qualities as a diagnostic tool or, more recently, as inclusion criteria in clinical trials 1 . However, the routine use of FDG-PET in the investigation of dementia is not recommended in the guidelines published by the American Academy of Neurology 2 or by the Third Canadian Consensus Conference on Dementia 3 . Several publications have studied the ability of FDG-PET to differentiate Alzheimer's disease (AD) from other dementia 4 , most of them using clinical diagnosis as gold standard. However, to this day, clinical diagnosis, even when combined with extensive neuropsychological testing, is neither sensitive nor specific enough to be considered a gold standard in dementia. In studies of clinicopathological correlation, the sensitivity of clinical diagnosis for AD varies between 75 and 98%, with an average of 82% when adjusted for the number of ABSTRACT: Positron emission tomography (PET) imaging with F18-fluorodeoxyglucose (FDG) is increasingly used as an adjunct to clinical evaluation in the diagnosis of dementia. Considering that most FDG-PET studies in dementia use clinical diagnosis as gold standard and that clinical diagnosis is approximately 80% sensitive or accurate, we aim to review the evidence-based data on the diagnostic accuracy of brain FDG-PET in dementia when cerebral autopsy is used as gold standard. We searched the PubMed and Medline databases for dementia-related articles that correlate histopathological diagnosis at autopsy with FDG-PET imaging and found 47 articles among which there were only 5 studies of 20 patients or more. We were able to conclude that sensitivity and specificity of FDG-PET for Alzheimer's disease are good, but more studies using histopathological diagnosis at autopsy as gold standard are needed in order to evaluate what FDG-PET truly adds to premortem diagnostic accuracy in dementia.RÉSUMÉ: L'autopsie comme étalon or dans les études TEP-FDG dans la démence. La tomographie par émission de positrons (TEP) au F18-fluorodésoxyglucose est de plus en plus utilisée comme examen d'appoint de l'évaluation clinique dans le diagnostic de la démence. Comme la plupart des études TEP-FDG dans la démence utilisent le diagnostic clinique comme étalon or et que le diagnostic clinique a une sensibilité ou une exactitude d'environ 80%, le but de notre étude était de revoir les données fondées sur des evidences au sujet de l'exactitude de la TEP-FDG du cerveau dans la démence quand l'autopsie cérébrale est utilisée comme étalon or. Nous avons effectué une recherche dans les bases de données PubMed et Medline afin de trouver les articles sur la démence qui évaluaient la corrélation entre le diagnostic histopathologique à l'autopsie et l'imagerie TEP-FDG. Nous avons identifié 47 articles dont seulement 5 portaient sur 20 patients ou pl...

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