Cortical edge-anchored ADC profiling in idiopathic intracranial hypertension: A longitudinal matched-control pilot...

To determine whether cortical apparent diffusion coefficient (ADC) profiles differ between patients with idiopathic intracranial hypertension (IIH) and matched controls, and whether these profiles change after ventriculoperitoneal (VP) shunt treatment.

This retrospective single-center matched-control pilot study included 16 patients with IIH who underwent baseline MRI before VP shunt placement and follow-up MRI after shunt treatment, as well as 16 matched controls with baseline MRI. Cortical ADC profiles were extracted from axial ADC maps using an in-house line profile-based edge-anchored profiling approach (LEAP). A short pial anchor was placed at the high convexity, and distance-resolved profiles were sampled from the cerebrospinal fluid (CSF) side across cortex into superficial white matter. Prespecified primary metrics were the mean tissue-side profile value in the 0-3 mm range, the inner profile peak, and the positive-side area under the profile. Prespecified raw-profile windows were 0-1.5 mm and 1.5-3.0 mm.

Broad baseline summary metrics did not clearly separate IIH from controls. In contrast, exploratory raw-profile analysis showed focal tissue-side differences, with the strongest baseline pointwise effect at 2.0 mm from the pial boundary. Longitudinally, patients with IIH showed significant increases after VP shunt treatment in the mean 0-3 mm tissue-side profile value (mean paired difference, -46.3; 95% CI, -81.7 to -10.9; p = 0.014), the inner profile peak (mean paired difference, -70.4; 95% CI, -124.7 to -16.0; p = 0.015), and the positive-side area under the profile (mean paired difference, -215.7; 95% CI, -419.7 to -11.6; p = 0.040). In the prespecified raw-window analysis, the strongest longitudinal changes were observed in the 0-1.5 mm range. Raw profiles were more informative than CSF-adjusted profiles.

Cortical LEAP profiling suggests subtle, spatially localized ADC alterations in IIH. The dominant signal in this pilot study is a treatment-associated longitudinal increase in superficial tissue-side raw-profile measures after VP shunt placement rather than a clear cross-sectional baseline separation from controls.