Predictive value of quantitative cisternography in normal pressure hydrocephalus

Abstract
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.