DIRECT IN-VIVO OBSERVATION OF TRANSVENTRICULAR ABSORPTION IN THE HYDROCEPHALIC DOG USING MAGNETIC-RESONANCE-IMAGING

RATIONALE AND OBJECTIVES. A model of chronic noncommunicating hydrocep halus in canines was developed, and gadolinium-DTPA (Gd-DTPA) enhanced magnetic resonance imaging, physiologic and morphologic studies were performed-to investigate transventricular absorption of cerebrospinal fluid. METHODS. Chronic hydrocephalus was induced in 12 mongrel dogs b y injection of a silastic mixture into the prepontine cisterns. Ventri cular pressure was measured during the development of hydrocephalus, a nd lateral ventriculo-ventricular perfusions with Gd-DTPA were perform ed under controlled conditions during serial magnetic resonance imagin g studies. RESULTS. Hydrocephalus developed over an average of 129 +/- 24 days after induction, and the intraventricular pressure increased from an initial level of 14 +/- 4 cm H2O to a stabilized plateau of 25 +/- 5 cm H2O. Increased signal intensity in the brain matter, as seen on magnetic resonance images of chronic hydrocephalic dogs perfused w ith Gd-DTPA in the lateral ventricles, was consistent with the presenc e of the contrast agent in the periventricular extracellular space. Th is increased signal intensity was not observed in control animals. CON CLUSIONS. These results provide direct evidence of transventricular ab sorption in chronic hydrocephalus.