Multimodal neuroimaging in Alzheimer's disease: A practical, case-illustrated review of quantitative MRI and molecular PET

Alzheimer's disease (AD) accounts for 60-70% of dementia cases worldwide. Current diagnostic pathways rely on structural magnetic resonance imaging (MRI) to exclude secondary causes, amyloid positron emission tomography (PET) to confirm pathology, and tau PET for disease staging. However, these approaches are limited by subjectivity, cost, accessibility, and variability in interpretation. Quantitative imaging tools such as volumetric MRI and NeuroQuant offer reproducible metrics that may enhance diagnostic precision and standardization. This review synthesizes literature published between 2000 and 2026 evaluating structural MRI, quantitative volumetric MRI, amyloid PET, tau PET, FDG PET, and emerging adjunctive imaging techniques, supplemented by illustrative clinical cases demonstrating multimodal integration in practice. Particular emphasis is placed on the role of NeuroQuant in standardized atrophy quantification and its integration with molecular imaging modalities. Volumetric MRI enhances PET-based diagnosis and staging by contextualizing amyloid and tau pathology within patterns of selective neurodegeneration. Quantitative metrics correlate with cognitive decline and disease progression. Multimodal imaging strategies improve diagnostic specificity, longitudinal monitoring, and phenotypic stratification across the AD. Multimodal imaging provides a comprehensive framework for AD management. Quantitative MRI using NeuroQuant bridges structural and molecular domains, supporting standardized assessment and integration with emerging precision diagnostic approaches.