Measurement of the CSF Velocity Using Cine-mode MRI
Recently, a to-and-fro motion of cerebrospinal fluid (CSF) in the aqueduct has been observed by means of cine-mode magnetic resonance imaging (MRI). We have studied this phenomenon in order to quantitate the CSF flow in patients with a hydrocephalus. The maximum velocity of the CSF flow passing through the superior part of the fourth ventricle (junction of the aqueduct and the fourth ventricle) was measured in ten normal volunteers as a control group, in seven patients with a communicating hydrocephalus, and in one patient with brain atrophy. Six of the hydrocephalic patients had secondary normal-pressure hydrocephalus (NPH) following subarachnoid hemorrhage (SAH), while the rest had idiopathic high-pressure hydrocephalus. The normal value of the CSF velocity in the ten normal volunteers was 1.9±1.0 mm/s (mean±SEM); on the other hand, in the seven patients with a communicating hydrocephalus, the value of the CSF velocity was increased to 7.5±3.1 mm/s (mean±SEM). The CSF velocity of all patients with a hydrocephalus was higher than that of normal ones. However, the CSF velocity of a patient with a ventriculomegaly due to brain atrophy was 2.0 mm/s, within the normal range. In five patients with NPH who had received a shunt operation (V-P shunt or L-P shunt), the CSF velocity was measured before and after the shunting procedure. Three patients have shown good clinical responses following a functioning shunt, and the CSF velocities have decreased postoperatively; in two of these patients, the CSF velocities returned to normal. In the two remaining patients, with a non-functioning shunt, the CSF velocities have not decreased at all postoperatively.