Dementia Care Research and Psychosocial Factors

Background: Early detection of Alzheimer's disease (AD) can improve prognosis, given new anti-amyloid therapies. Both positron emission tomography (PET) and magnetic resonance (MR) imaging biomarkers are currently used (1). 48F-Fluorodeoxyglucose-PET (FDG-PET) can detect neurodegeneration-related hypometabolism but is costly and not easily accessible (2). Cerebral blood flow (CBF), assessed using arterial spin labelling magnetic resonance imaging (ASL-MRI), is closely linked to metabolism in neurodegenerative disease (2). In a recent case series of seven neurodegenerative patients, we described concordance between CBF and (i) FDG-PET and (ii) amyloid/tau PET (3). In this clinical cohort, ASL-MRI was used to triage patients with cognitive concerns.

Method: A retrospective analysis included patients aged 25-85 with cognitive symptoms, who underwent ASL-MRI and either (i) FDG-PET (n = 65) and/or (ii) amyloid PET or CSF sampling for amyloid/tau (n = 44). CBF maps were standardized and independently assessed by two neuroradiologists for a typical AD pattern (temporoparietal) or lobar (≥2 lobes) hypoperfusion. FDG avidity was compared against a normative database for regional hypometabolism. The sensitivity and specificity of ASL-MR in identifying AD was assessed, as well as discordance with FDG-PET.

Result: 82 patients met inclusion criteria (mean age 68±13), interrater reliability for lobar hypoperfusion was 84%. Temporoparietal hypoperfusion was 81% specific, but only 52% sensitive for biomarker-proven AD; lobar hypoperfusion increased sensitivity to 78%, but specificity decreased to 43%. Using temporoparietal hypoperfusion, there was 29% discordance with FDG-PET. Using lobar hypoperfusion, there was 38% discordance.

Conclusion: ASL-MRI is a promising, non-invasive screening tool for early detection and diagnosis of AD and other neurodegenerative diseases. Understanding the discordance between ASL-MRI and FDG-PET warrants further attention. In routine assessments for cognitive complaints, ASL-MRI should be added to the screening protocol MRI. Bibliography: 1. Haidar H, Majzoub RE, Hajeer S, Abbas LA. Arterial spin labeling (ASL-MRI) versus fluorodeoxyglucose-PET (FDG-PET) in diagnosing dementia: a systematic review and meta-analysis. BMC Neurol. 2023 Oct 24;23(1):385. 2. Minoshima S, Cross D, Thientunyakit T, Foster NL, Drzezga A. ¹⁸F-FDG PET Imaging in Neurodegenerative Dementing Disorders: Insights into Subtype Classification, Emerging Disease Categories, and Mixed Dementia with Copathologies. J Nucl Med. 2022 Jun;63(Suppl 1):2S-12S. 3. Accepted publication, AJNR.