Clinical Routine FDG-PET Imaging of Suspected Progressive Supranuclear Palsy and Corticobasal Degeneration: A Gatekeeper for Subsequent Tau-PET Imaging?

• Main Authors: Leonie Beyer, Johanna Meyer-Wilmes, Sonja Schönecker, Jonas Schnabel, Eva Brendel, Catharina Prix, Georg Nübling, Marcus Unterrainer, Nathalie L. Albert, Oliver Pogarell, Robert Perneczky, Cihan Catak, Katharina Bürger, Peter Bartenstein, Kai Bötzel, Johannes Levin, Axel Rominger, Matthias Brendel
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2018-06-01
• Series: Frontiers in Neurology
• Subjects: atypical parkinsonian syndrome; progressive supranuclear palsy; corticobasal degeneration; F-18-FDG; PET; clinical routine
• Online Access: https://www.frontiersin.org/article/10.3389/fneur.2018.00483/full

Background: F-18-fluordeoxyglucose positron emission tomography (FDG-PET) is widely used for discriminative diagnosis of tau-positive atypical parkinsonian syndromes (T+APS). This approach now stands to be augmented with more specific tau tracers. Therefore, we retrospectively analyzed a large clinical routine dataset of FDG-PET images for evaluation of the strengths and limitations of stand-alone FDG-PET.Methods: A total of 117 patients (age 68.4 ± 11.1 y) underwent an FDG-PET exam. Patients were followed clinically for a minimum of one year and their final clinical diagnosis was recorded. FDG-PET was rated visually (positive/negative) and categorized as high, moderate or low likelihood of T+APS and other neurodegenerative disorders. We then calculated positive and negative predictive values (PPV/NPV) of FDG-PET readings for the different subgroups relative to their final clinical diagnosis.Results: Suspected diagnoses were confirmed by clinical follow-up (≥1 y) for 62 out of 117 (53%) patients. PPV was excellent when FDG-PET indicated a high likelihood of T+APS in combination with low to moderate likelihood of another neurodegenerative disorder. PPV was distinctly lower when FDG-PET indicated only a moderate likelihood of T+APS or when there was deemed equal likelihood of other neurodegenerative disorder. NPV of FDG-PET with a low likelihood for T+APS was high.Conclusions: FDG-PET has high value in clinical routine evaluation of suspected T+APS, gaining satisfactory differential diagnosis in two thirds of the patients. One third of patients would potentially profit from further evaluation by more specific radioligands, with FDG-PET serving gatekeeper function for the more expensive methods.