Predictive value of quantitative cisternography in normal pressure hydrocephalus.

Twenty-five patients with normal pressure hydrocephalus (NPH) and 16 patients with cerebral atrophy were investigated by quantitative cisternography using anterior images of the head 3, 6 and 24 h after a lumbar injection of 200 MBq 99mTc DTPA (diethylene-triamine-penta-acetic acid). The activity in the lateral ventricles, basal cisterns, hemispheric convexities and total intracranial region was measured. Ratios between these regions/quantities were calculated. Fifteen of the NPH patients improved while 10 were unchanged after ventriculo-peritoneal shunt surgery. The ratio between ventricular and total intracranial activity (V/T) correlated positively with the degree of improvement after shunt surgery. All NPH patients with a V/T ratio higher than 32% improved after the operation but a V/T ratio less than 32% did not exclude the possibility of improvement. With regard to quantitative measurements, the radionuclide cisternography procedure can be reduced to imaging at 24 h.