Semi-automated Computed Tomography Volumetry as a Proxy for Intracranial Pressure in Patients with Severe Traumatic Brain Injury: Clinical Feasibility Study.

Abstract

Traumatic brain injury (TBI) is associated with high mortality due to intracranial pressure (ICP). Whether computed tomography (CT) scanning of the brain within the first 24h is indicative of intracranial hypertension is largely unknown. We assessed the feasibility of semi-automated CT segmentation in comparison with invasive ICP measurements. CT volumetry of the brain might provide ICP data when invasive monitoring is not possible or is undesirable. We identified 33 patients with TBI who received a CT scan at admission and ICP monitoring within 24h. Semi-automated segmentation of CT images in Matlab yielded cerebrospinal fluid (CSF) and intracranial volume (ICV) data. The ratio CSF/ICV×100 (expressed as a percentage) was used as a proxy for ICP. The association between invasive ICP and the CSF/ICV ratio was evaluated using a simple linear regression model and a mono-exponential function derived from previous research in animals. ICP is moderately but significantly associated with the CSF/ICV ratio (r=-0.44, p=0.01). The mono-exponential function provided a better fit of the relationship between ICP and the CSF/ICV ratio than the linear model. Our feasibility TBI data show that cross-sectional volumetric CT measures are associated with ICP. This non-invasive method can be used in future studies to monitor patients who are not candidates for invasive monitoring or to evaluate therapy effects objectively.