Measurements of intracranial pressure and compliance index using 1.5-T clinical MRI machine

To assess a newly proposed noninvasive technique for evaluating intracranial pressure (ICP) index and brain compliance (BC) index based on an inverse analysis of a brain-circulation-equivalent electrical circuit (EC) model, in which cerebrospinal fluid (CSF) flow and arterial flow rates measured by using the phase contrast method are used as currents.

Quantitative phase contrast flow measurements were performed by using a 1.5-T scanner for 25 volunteers and 23 patients with chronic increased ICP state. Bilateral carotid and verrtebral arteries and CSF flows were modeled by a pair of electrical circuits inductively coupled by a transformer. The ICP index was defined as the voltage of the second order circuit, while the BC index was calculated as the ratio between the mutual indeuctance of the transformer and the reactance in the second order circuit.

The ICP index obtained by the EC correlated well with the pressure gradient obtained by the Navier-Stokes Technique (NS-PG). The combination of NS-PG and BC index by the EC appeared to be appropriate for characterizing the brain circulation status of the volunteers.

This noninvasive ICP and BC index measurement technique is more useful for asessment of intracranial condition.