Impact of F-18 FDG-PET for the Clinical Multidisciplinary Evaluation of Dementia

PURPOSE       

Dementia is a challenging clinical diagnosis. Compared with conventional clinical evaluations, F-18 Fluorodeoxyglucose (FDG) PET has been reported to improve not only the diagnostic accuracy of dementia but also help better define the underlying  type. This is because FDG PET demonstrates metabolic patterns reflecting neuronal function specific to different dementias.To assess the impact of PET on a multidisciplinary  dementia clinic for patients with suspected dementia by comparing it with the initial clinical evaluation and paraclinical tests.

              METHOD AND MATERIALS       

So far we have included 16 patients (13 male: 3 female, average age 63 years) who had suspected dementia and/or unclear type of dementia of at least 6 months duration and were assessed in a neurologist led dementia clinic. All patients had MRI, including 7 with perfusion imaging. All patients had FDG-PET scans with visual and automated analyses. At a multidisciplinary meeting attended by a neuroradiologist and PET specialist, a pre-PET diagnosis, type of dementia and management plan was composed by a neurologist on the basis of clinical assessment, MRI, neuropsychometry and cerebrospinal fluid results. This process was repeated after PET review and the management plans were compared. Management impact was rated as nil (discordant result ignored), low (PET concordant but no change in management), moderate (PET changed diagnosis or dementia type or followup plan) and high (PET changed diagnosis from normal to dementia or vice versa).

              RESULTS       

Management impact was nil in 0 patients, low in 9, moderate in 7 and high in 0.The majority of these changes were of a moderate level influencing the type of dementia diagnosed.

              CONCLUSION       

F-18 FDG-PET changed management in 44 % of patients seen in a specialist mutlidisciplinary dementia clinic.PET has promising clinical value for management decisions in patients where clinical evaluations combined with lab CSF results and dedicated MR imaging are equivocal for Alzheimers or Frontotemporal dementia.

              CLINICAL RELEVANCE/APPLICATION       

F18-FDG Brain PET with visual and automated analyses can be valuable  in a diagnostic algorithim for the work up of dementia when the cause is uncertain.