Objective: To evaluate the impact of positron emission tomography with ¹⁸F-FDG, ¹¹C-PiB, and ¹⁸F-THK 5351 on the diagnosis of Alzheimer’s disease, primary tauopathies, and other dementia subtypes.

Materials and Methods: The authors recruited 30 patients with varying degrees of cognitive impairment that included 14 males and 16 females, aged 50 to 77 years and with a mean age ±SD: 66.6±6.9 years). All patients underwent ¹⁸F-FDG, ¹¹C-PiB, and ¹⁸F-THK 5351 PET/CT scans. Quantitative and visual analyses of the PET images were performed and reported back to the neurologists responsible for the initial diagnoses. Outcome measures were changed between pre- and post-PET clinical diagnoses and treatment.

Results: The primary diagnoses changed after the disclosure of ¹⁸F-FDG, ¹¹C-PiB, and ¹⁸F-THK 5351 PET scan results in 18 of 30 patients (60%) and was able to resolve 20 of 21 (95.2%) pre-PET diagnostic dilemmas. No new diagnostic dilemmas were created. All changes in clinical diagnoses were accompanied by changes in treatment plan. PET imaging results confirmed the initial diagnoses of six patients.

Conclusion: Combined ¹¹C-PiB, ¹⁸F-THK 5351, and ¹⁸F-FDG-PET are of additional diagnostic value over standard diagnostic work-up, especially in diagnostic dilemmas or difficult-to-diagnose dementia patients.

Keywords: ¹⁸F-FDG; ¹¹C-PiB; ¹⁸F-THK 5351; Positron emission tomography; Tauopathy

DOI: doi.org/10.35755/jmedassocthai.2021.12.12161

Received 26 October 2020 | Revised 20 August 2021 | Accepted 23 August 2021