High‐Resolution IVIM MRI Characterizes Diffusion–Perfusion Properties of the Parasagittal Dura

The objectives of this study were to characterize the diffusion-perfusion properties of the parasagittal dura (PSD) using high-resolution intravoxel incoherent motion (IVIM) MRI and to explore whether PSD-specific IVIM metrics reflect distinct fluid-transport-related signal behavior compared with CSF and brain parenchyma. Ten healthy volunteers underwent 3 T MRI, including high-resolution 3D T2-FLAIR for anatomical localization and multi-b-value diffusion-weighted imaging using MUSE and FOCUS IVIM sequences. Apparent diffusion coefficients (ADCs) and IVIM parameters-true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f)-were quantified in the PSD, CSF, gray matter (GM), and white matter (WM). A pseudo-diffusion residual analysis was performed to estimate the perfusion-related b-value transition. Tissue-specific differences were assessed using nonparametric statistics. The PSD showed diffusion-perfusion characteristics distinct from those of both CSF and brain parenchyma. ADC values decreased with increasing b values and were intermediate between those of CSF and GM/WM. IVIM analysis demonstrated higher perfusion fractions and pseudo-diffusion coefficients in the PSD than in GM and WM, indicating substantial microcirculatory or fluid-transport contributions. The perfusion-related b-value transition thresholds in the PSD were higher than those in CSF but lower than those in GM and WM, supporting its intermediate perfusion behavior. MUSE and FOCUS acquisitions produced comparable quantitative metrics, with MUSE demonstrating reduced geometric distortion and FOCUS providing higher signal-to-noise ratios. In conclusion, the PSD exhibits a distinct diffusion-perfusion profile consistent with its role as a transitional interface among CSF pathways, dural lymphatics, and venous outflow. PSD-specific IVIM metrics may provide a rapid, noncontrast approach for characterizing dural fluid-transport-related signal behavior at the interface between CSF spaces, meningeal lymphatics, and venous outflow.