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J Alzheimers Dis. 2016;49(3):695-705. doi: 10.3233/JAD-150302.

Clinical Impact of a Second FDG-PET in Atypical/Unclear Dementia Syndromes.

Author information

1
Clinique Interdisciplinaire de Mémoire (CIME), CHU de Québec, PQ, Canada.
2
Département d'imagerie médicale, CHU de Québec, PQ, Canada.
3
Service de médecine nucléaire, Institut de Cardiologie et de Pneumologie de Québec (IUCPQ), PQ, Canada.
4
Département des Sciences Neurologiques, Université Laval, PQ, Canada.

Abstract

Diagnosis of atypical/unclear dementia is often difficult and this delays treatment initiation. Several authors have shown that beyond standard dementia workup, 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) reduces the number of unclear diagnoses, leads to earlier treatment, and has a beneficial impact on families. However, it is not uncommon that the FDG-PET findings are equivocal in this setting. For those cases, a repeat FDG-PET may clarify the diagnosis and prevent treatment delay. We retrospectively assessed the clinical impact of a repeat FDG-PET in 59 patients with atypical/unclear dementia syndromes and inconclusive initial FDG-PET. Changes in primary diagnosis, diagnostic confidence, and management following the second FDG-PET were examined. Conducting a second FDG-PET reduced the number of unclear diagnoses from 80% to 34% , led to diagnostic change in 24% of cases, and treatment modification in 22% of patients. Overall, the clinical impact was higher when initial diagnostic confidence was low and the second FDG-PET repeated ≥12 months after the first one. In tertiary care memory clinic settings, when diagnostic incertitude persists despite extensive evaluation and an equivocal FDG-PET, repeating the FDG-PET 12 months later can greatly clarify the diagnosis and improve management.

KEYWORDS:

Atypical dementia; FDG-PET; brain imaging; differential diagnosis

PMID:
26484904
DOI:
10.3233/JAD-150302
[Indexed for MEDLINE]

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