TY - JOUR T1 - Variability of Normal Pressure Hydrocephalus Imaging Biomarkers with Respect to Section Plane Angulation: How Wrong a Radiologist Can Be? JF - American Journal of Neuroradiology JO - Am. J. Neuroradiol. SP - 1201 LP - 1207 DO - 10.3174/ajnr.A7095 VL - 42 IS - 7 AU - P. Ryska AU - O. Slezak AU - A. Eklund AU - J. Salzer AU - J. Malm AU - J. Zizka Y1 - 2021/07/01 UR - http://www.ajnr.org/content/42/7/1201.abstract N2 - BACKGROUND AND PURPOSE: Systematic analysis of angulation-related variability of idiopathic normal pressure hydrocephalus imaging biomarkers has not been published yet. Our aim was to evaluate the variability of these radiologic biomarkers with respect to imaging plane angulation.MATERIALS AND METHODS: Eighty subjects (35 with clinically confirmed idiopathic normal pressure hydrocephalus and 45 age- and sex-matched healthy controls) were prospectively enrolled in a 3T brain MR imaging study. Two independent readers assessed 12 radiologic idiopathic normal pressure hydrocephalus biomarkers on sections aligned parallel or perpendicular to the bicallosal, bicommissural, hypophysis-fastigium, and brain stem vertical lines, respectively.RESULTS: Disproportionately enlarged subarachnoid space hydrocephalus, simplified callosal angle, frontal horn diameter, z-Evans Index, and cella media vertical width did not show significant systematic differences in any of 6 section plane combinations studied. The remaining 7 biomarkers (including the Evans Index and callosal angle) showed significant differences in up to 4 of 6 mutually compared section plane combinations. The values obtained from sections aligned with the brain stem vertical line (parallel to the posterior brain stem margin) showed the most deviating results from other section angulations.CONCLUSIONS: Seven of 12 idiopathic normal pressure hydrocephalus biomarkers including the frequently used Evans Index and callosal angle showed statistically significant deviations when measured on sections whose angulations differed or did not comply with the proper section definition published in the original literature. Strict adherence to the methodology of idiopathic normal pressure hydrocephalus biomarker assessment is, therefore, essential to avoid an incorrect diagnosis. Increased radiologic and clinical attention should be paid to the biomarkers showing low angulation–related variability yet high specificity for idiopathic normal pressure hydrocephalus–related morphologic changes such as the z-Evans Index, frontal horn diameter, or disproportionately enlarged subarachnoid space hydrocephalus.BVRbrain-to-ventricle ratioCAcallosal angleCMWcella media vertical widthCTRcella media-to-temporal horn ratioDESHdisproportionately enlarged subarachnoid space hydrocephalusEIEvans IndexFHDfrontal horn diameterFHVDfrontal horn vertical diameterHChealthy controlHy-Fahypophysis-fastigiumiNPHidiopathic normal pressure hydrocephalusISDinner skull diameterMSIDmaximum supratentorial intracranial diameterPBSMposterior brain stem marginsimpCAsimplified callosal angleSVWsupraventricular brain vertical widthTHWtemporal horn vertical widthZEIz-Evans Index ER -