MR Elastography in Disorders of CSF Dynamics: Current Evidence, Pitfalls, and the Road to Clinical Adoption.

Disorders of cerebrospinal fluid (CSF) dynamics, including idiopathic normal pressure hydrocephalus (iNPH), idiopathic intracranial hypertension (IIH), and spontaneous intracranial hypotension (SIH) frequently present clinical and imaging phenotypes that overlap with other disease processes. Although conventional MRI remains central for identifying characteristic morphologic features, many imaging findings have variable sensitivity, particularly across disease stages. As a result, current diagnostic pathways and treatment selection is still often reliant on invasive, snapshot-based physiologic tests. Magnetic resonance elastography (MRE) provides a noninvasive, quantitative approach to probe brain viscoelastic properties reflecting tissue microstructure and mechanical strain. These properties are influenced by intracranial pressure-volume states within the Monro-Kellie constraints, offering a potential "systems-level" biomarker of intracranial compliance and CSF-venous coupling. This review summarizes the technical foundations of brain MRE relevant to radiologists, including the fundamentals and technical aspects of the technique, and the key sources of measurement variability that influence interpretability and reproducibility. It synthesizes the current clinical evidence supporting MRE for diagnosis, phenotyping, and longitudinal treatment assessment across CSF dynamics disorders, with emphasis on practical integration into contemporary imaging workflows and standardized region-of-interest reporting. Finally, we highlight limitations of existing literature and priorities for future research for MRE in this patient population.