Affiliations: [a] Clinique Interdisciplinaire de Mémoire (CIME), CHU de Québec, PQ, Canada | [b] Département d’imagerie médicale, CHU de Québec, PQ, Canada | [c] Service de médecine nucléaire, Institut de Cardiologie et de Pneumologie de Québec (IUCPQ), PQ, Canada | [d] Département des Sciences Neurologiques, Université Laval, PQ, Canada
Correspondence:
[*]
Correspondence to: David Bergeron, MS, Clinique Interdisciplinaire de Mémoire (CIME), CHU de Québec, 1401, 18ième rue, Québec, G1J 1Z4, Canada. Tel.: +1 418 649 5980; Fax: +1 418 649 5981; E-mail: david.bergeron.5@ulaval.ca
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.
