Phase-contrast and three-dimensional driven equilibrium (3D-DRIVE) sequences in the assessment of paediatric obstructive hydrocephalus.

backgroundRecently, most cases of hydrocephalus are related to obstruction. Accurate localization of the site of obstruction is crucial in determination of the treatment strategy. PURPOSE: To describe the phase-contrast and 3D-DRIVE findings in cases of obstructive hydrocephalus in paediatric patients and to determine their functional and anatomical correlates. MATERIAL AND

methodsBrain MRIs of 25 patients (2 months to 11 years) with obstructive hydrocephalus were retrospectively reviewed. Phase-contrast and 3D-DRIVE were performed to assess cerebrospinal (CSF) pathways through the aqueduct of Sylvius and subarachnoid spaces. In addition to flow velocity measurement at the aqueduct of Sylvius, functional and anatomical correlation was analysed at the level of aqueduct of Sylvius, infracerebellar CSF space and at the third ventriculostomy using Spearman's rank test.

resultsAqueduct of Sylvius was the most common site of obstruction (19 patients) either secondary to focal, multifocal or tubular stenosis, adhesions, or secondary to extrinsic compression. Functional and anatomical correlation was analysed in 58 regions revealing strong correlation (ro = 0.8, p < .001). Functional anatomical mismatch was found in nine regions. Flow velocity measurements revealed diminished flow in most of the cases with obstruction at the aqueduct and normal velocity in cases with obstruction proximal to aqueductal level, while accelerated flow was seen in cases with infra-aqeuductal obstruction.

conclusionPhase-contrast and 3D-DRIVE sequences are essential sequences in the diagnosis of hydrocephalus enabling perfect localization of the site of obstruction. Both sequences should be interpreted in conjunction to avoid false results. Velocity measurements through the aqueduct can help understand CSF hydrodynamics.