Elderly patients often present with ventriculomegaly, not only with normal aging, but also due to a multitude of neurological disorders. Flow-sensitive magnetic resonance imaging (MRI) techniques have been increasingly applied to quantitatively and qualitatively assess cerebrospinal fluid (CSF) flow dynamics ^(1-4). The aim of this work was to study the role of MR CSF flow studies in assessment of elderly patients with ventriculomegaly.MR CSF flow study was conducted on 20 subjects (16 males and 4 females, age range 55-82 years) who presented with various clinical manifestations, and ventriculomegaly (Evans index ≥ 0.3) on initial conventional brain imaging. Image acquisitions were carried out on a 1.5 Tesla MR System (Magnetom Avanto, Siemens Medical Solutions) and included: axial and sagittal T1-weighted spin echo (T1 SE), axial and coronal T2-weighted turbo spin echo (T2 TSE), axial FLAIR, midsagittal 3D-CISS (steady-state free precession three-dimensional constructive interference in a steady state), and phase-contrast MRI (PC-MRI) with in-plane (sagittal) and through-plane (axial) gradient echo sequences. Retrospective cardiac gating was performed via a peripheral pulse transducer. In all cases, CSF flow was evaluated qualitatively following acquisition of phase and magnitude images. The midsagittal phase-contrast images obtained with in-plane velocity encoding were displayed in a closed-loop cine format. A circular region of interest (ROI) was placed manually in a magnified through-plane phase image perpendicular to the cerebral aqueduct, so as to include pixels that reflected the CSF flow signals with maximum flow rates. The acquired images were then transferred to a post-processing program and CSF flow changes throughout one cardiac cycle were extracted from the software by peak velocity-time and flow-time graphics. The CSF hydrodynamics were quantitatively analyzed using peak systolic velocity (PSV in cm/s), mean flow (MF in ml/min), and aqueductal stroke volume (SV in μL/cycle).The cause of the ventriculomegaly was identified in all patients and summarized in Table 1. The most common cause of ventriculomegaly was found to be NPH in 11 patients (55%) (Figure 1). Eight patients showed obstructive hydrocephalus. Of these, 6 showed aqueductal webs (Figure 2), 1 showed aqueductal stenosis, and 1 showed a third ventricle colloid cyst. The remaining patient showed cerebral atrophy. Five patients (25%) showed no recorded CSF flow through the aqueduct, all of which were caused by obstruction due to aqueductal webs/stenosis. The aqueductal stroke volume (SV) recorded in the other 15 patients ranged from 5 to 165 μL/cycle (mean: 51.5 μL/cycle). The peak systolic velocity (PSV) ranged from 0.01 to 9.1 cm/s (mean: 4.28 cm/s), and mean flow (MF) ranged from 0.06 to 3.66 ml/min (mean: 1 ml/min). In the NPH patients, the range of aqueductal SV measured was between 26-165 μL with a mean of 66.2 μL. Seven of the NPH patients showed very high SV (above 42 μL/cycle) indicating potential shunt-responsiveness ⁽⁵⁾. Incidental spontaneous third ventriculostomy (STV) was found in 1 patient with aqueductal web obstruction. Another patient had undergone endoscopic third ventriculostomy (ETV) for treatment of aqueductal stenosis, and the ETV was identified as patent with high SV across the stoma (161 μL/cycle) ⁽⁶⁾.MR CSF flow study is a useful imaging technique in evaluating CSF dynamics associated with ventriculomegaly, especially in patients with hyperdynamic aqueductal flow or aqueductal obstruction. It provides valuable additional information to conventional MRI in the diagnosis, follow-up, surgical decision and post-operative survey in patients with abnormal CSF flows. Furthermore, it plays an important role in evaluating the patency and functionality of third ventriculostomies, whether spontaneous or endoscopic.