Citations

Abstract Positron emission tomography (PET)-based molecular imaging is a clinically important tool for the evaluation of dementia and other neurodegenerative disorders, using radiotracers that target specific molecular and pathophysiological processes. Fluorodeoxyglucose brain PET has historically supported neurodegenerative disorder evaluation through detection of characteristic patterns of regional glucose hypometabolism. In recent years, the molecular imaging of protein aggregates has taken on an increasingly important role. This is evident with the widespread clinical adoption of amyloid PET and early use of tau PET to provide diagnostic and prognostic information for patients with suspected Alzheimer’s disease. Additional classes of radiotracers relevant to neurodegenerative diseases are under active investigation, including those targeting neuroinflammation, synaptic density, and α-synuclein aggregates. We review the major classes of PET radiotracers for neurodegenerative diseases, describing their molecular mechanisms, diagnostic performance, and their current and emerging clinical roles in dementia evaluation. Case examples for clinically used tracers illustrate imaging features relevant to diagnosis and characterization of prognosis and treatment effect. Finally, we discuss early developments and current challenges in the development of theranostic approaches and novel radiotracers for neurodegenerative diseases.

Importance Myelin oligodendrocyte glycoprotein antibody–associated disease (MOGAD) lacks proven relapse-preventive therapies. While clinical trials are ongoing, safety data may be limited and approved drugs are costly. Studies of interleukin 6 receptor blocker (IL-6RB) in MOGAD are limited by small numbers and no comparative studies, contributing to low use. Objective To evaluate the impact of IL-6RB therapy on relapse rates in MOGAD and compare relapse frequency with intravenous immunoglobulin (IVIG). Design, Setting, and Participants This international, multicenter, retrospective cohort study (January 1, 2015, through December 31, 2025) included a historical IVIG-treated cohort of varying doses. The study took place across sites in North and South America (US, Canada, Mexico, Argentina, Brazil, Chile, Colombia, and Peru). Patients with MOGAD (n = 116, no excluded patients) who received at least 1 dose of an IL-6RB were included. These data were analyzed in January 2026. Exposures Tocilizumab or satralizumab. Main Outcomes and Measures Annualized relapse rate (ARR) during IL-6RB therapy, time to next relapse after treatment initiation, and adverse events. Outcomes were compared with the IVIG cohort using inverse probability of treatment weighting (IPTW) adjusted for age, sex, prior ARR, and concomitant therapies. Results A total of 116 patients with MOGAD (89% relapsing) receiving IL-6RB (tocilizumab, 104 [90%] and satralizumab, 12 [10%]) were included; overall, 60.3% were female, 39.7% were male, and 18% were younger than 18 years. The median (IQR) IL-6RB treatment follow-up was 1.4 (0.7-2.5) years and 23 relapses occurred during 241.8 person-years of IL-6RB therapy. The ARR decreased from 0.64 (95% CI, 0.58-0.70) for relapsing MOGAD before IL-6RB to 0.09 (95% CI, 0.06-0.14) during IL-6RB treatment (incidence rate ratio, 0.08; 95% CI, 0.04-0.16). Adverse events occurred in 58 patients (50%), most commonly mild infections, although 10 (9%) had severe infections. In the IVIG cohort (n = 59), 30 relapses occurred over 133.8 person-years (ARR, 0.22; 95% CI, 0.15-0.32). After IPTW, IL-6RB was associated with a lower hazard ratio (HR) than the group who underwent IVIG therapy less than 1 g/kg every 4 weeks (HR, 4.5; 95% CI, 2.0-9.8), with no significant difference vs the group who underwent IVIG 1 g/kg or more every 4 weeks (HR, 2.0; 95% CI, 0.8-4.5). Conclusions and Relevance In this multicenter observational cohort, IL-6RB use in MOGAD was associated with low relapse rates and a favorable safety profile, though severe infections occurred occasionally. Relapse rates were lower than the group who underwent IVIG less than 1 g/kg every 4 weeks but not significantly different from the group who underwent IVIG 1 g/kg or more every 4 weeks. This supports IL-6RB as a potential relapse-prevention therapy in MOGAD; the wide availability and relative affordability of tocilizumab may enable broad global use.

This case series describes multicenter experience with interleukin 6 (IL-6) receptor blockers used during attacks in aquaporin 4–immunoglobulin G–positive neuromyelitis optica spectrum disorder (AQP4+NMOSD) and myelin oligodendrocyte glycoprotein antibody–associated disease (MOGAD).