A multimodal clinical diagnostic approach using MRI and 18F-FDG-PET for antemortem diagnosis of TDP-43 in cases with low-intermediate Alzheimer's disease neuropathologic changes and primary age-related tauopathy

Anna Lavrova; Nha Trang Thu Pham; Cynthia J Vernon; Arenn F Carlos; Ronald C Petersen; Dennis W Dickson; Val J Lowe; Clifford R Jack Jr; Jennifer L Whitwell; Keith A Josephs

doi:10.1007/s00415-024-12312-5

A multimodal clinical diagnostic approach using MRI and ¹⁸F-FDG-PET for antemortem diagnosis of TDP-43 in cases with low-intermediate Alzheimer's disease neuropathologic changes and primary age-related tauopathy

J Neurol. 2024 Apr 5. doi: 10.1007/s00415-024-12312-5. Online ahead of print.

Affiliations

¹ Department of Radiology, Mayo Clinic, Rochester, MN, USA.
² Department of Neurology, College of Medicine and Science, 200 First Street S.W., Rochester, MN, 55905, USA.
³ Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA.
⁴ Department of Neurology, College of Medicine and Science, 200 First Street S.W., Rochester, MN, 55905, USA. josephs.keith@mayo.edu.

PMID: 38578498
DOI: 10.1007/s00415-024-12312-5

Abstract

Objective: To evaluate the utility of clinical assessment scales for MRI and ¹⁸F-FDG-PET as potential in vivo predictive diagnostic tools for TAR DNA-binding protein of 43 kDa (TDP-43) proteinopathy in cases with low-intermediate Alzheimer's disease neuropathologic changes (ADNC) and primary age-related tauopathy (PART).

Methods: We conducted a cross-sectional analysis on patients with antemortem MRI and ¹⁸F-FDG-PET scans and postmortem diagnosis of low-intermediate ADNC or PART (Braak stage ≤ III; Thal β-amyloid phase 0-5). We employed visual imaging scales to grade structural changes on MRI and metabolic changes on ¹⁸F-FDG-PET and statistically compared demographic and clinicopathological characteristics between TDP-43 positive and negative cases. Independent regression analyses were performed to assess further influences of pathological characteristics on imaging outcomes. Within-reader repeatability and inter-reader reliability were calculated (CI = 0.95). Additional quantitative region-of-interest analyses of MRI gray matter volumes and PET ligand uptake were performed.

Results: Of the 64 cases in the study, 20 (31%) were TDP-43 ( +), of which 12 (60%) were female. TDP-43 ( +) cases were more likely to have hippocampal sclerosis (HS) (p = 0.014) and moderate-severe medial temporal lobe atrophy on MRI (p = 0.048). TDP-43( +) cases also showed a trend for less parietal atrophy on MRI (p = 0.086) and more medial temporal lobe hypometabolism on ¹⁸F-FDG-PET (p = 0.087) than TDP-43( - ) cases. Regression analysis showed an association between medial temporal hypometabolism and HS (p = 0.0113). ICC values for MRI and PET within one reader were 0.75 and 0.91; across two readers were 0.79 and 0.82. The region-of-interest-based analysis confirmed a significant difference between TDP-43( +) and TDP-43( - ) cases for medial temporal lobe gray matter volume on MRI (p = 0.014) and medial temporal metabolism on PET (p = 0.011).

Conclusion: Visual inspection of the medial temporal lobe on MRI and FDG-PET may help to predict TDP-43 status in the context of low-intermediate ADNC and PART.

Keywords: 18F-FDG-PET; LATE; MRI; Primary age-related tauopathy; TAR DNA-binding protein 43.

Grants and funding

U01 AG006786/AG/NIA NIH HHS/United States