MR Visualization of CSF Flow Through a Ventriculo-cisternostomy
The MRI findings in a 6 year old boy with an astrocytoma of the mesencephalon are reported. A ventriculo-cisternostomy had been performed in order to reduce the hydrocephalus. The MR examination was performed with a 0.5 T GE-CGR Magniscan imager. T1- and T2-weighted sequence were obtained in the sagittal plane. The T1-weighted images showed an heterogeneous lesion of the tectum. On the 12 weighted images, the lesion had an heterogeneous increased signal and was surrounded by high intensity edema. At the site of the ventriculo-cisternostomy, the T2-weighted images showed low signal in the anterior part of the third ventricle, the interpeduncular and pontine cistern (Figure). The other parts of the ventricular system and the subarachnoid spaces had a normal increased signal. This low signal was probably due to spin phase shifts and time of flight effects created by CSF turbulence and increased velocity of the flow at the level of the ventriculocisternostomy.