Feasibility of Simple Linear Measurements to Determine Ventricular Enlargement in Patients With Idiopathic Normal Pressure Hydrocephalus.

To evaluate the feasibility and reproducibility of linear measurements for determining ventricular enlargement in patients with idiopathic normal pressure hydrocephalus (iNPH) and their correlation to ventricular volume (VV).Preoperative brain computed tomography scans were retrospectively evaluated in 36 patients with iNPH. The quantitative markers of Evan index (EI), VV, frontal and occipital horn ratio (FOR), modified cella media index (mCMI), third ventricular width (TVW), temporal horn width (TPH), frontal horn width (FHW), and callosal angle (CA) at the posterior commissure (PC) were independently measured by a neurosurgeon and a radiologist. Intraclass correlation coefficients were calculated to establish inter-rater agreement among the 2 investigators. Pearson correlation coefficients were used to assess the relationship of each linear measurement with total VV.The overall inter-rater agreement among investigators was almost perfect for EI, VV, FOR, mCMI, TVW, substantial for FHW and moderate for TPH, and CA at PC. Pearson correlation coefficients showed excellent correlation between mCMI and VV. Moderate correlation was found between the VV and FHW, TVW, FOR, EI, and CA at PC. Fair correlation was found between the VV and TPH.Simple linear measurements could serve as effective alternative to volumetric analysis to determine ventricular size in patients with iNPH. The quantitative marker of mCMI is more reasonable and accurate than EI, FOR, and other simple linear measurements.