Contrast-enhanced CT measurement of blood-brain permeability in human brain tumors

A contrast enhanced CT method was developed for measuring the blood-brain permeability (K) and cerebral plasma volume (V;In a preliminary study of 12 patients, the average K and V;To increase the efficiency of the CT method in a clinical environment, an absorptiometry method was developed to measure contrast concentration in blood automatically. This method was based on the principle of single photon absorptiometry and was found to measure the arterial contrast concentration with a 5% uncertainty in patient studies.;Error analysis on the K estimate by the CT method was studied with sensitivity functions, computer simulations and covariance matrix formalism. The CT method was found to determine K in brain tumor with negligible bias and 5% uncertainty. In contrast, it determined K in normal brain with 14% bias and 73% uncertainty.;The CT method was used to study the effect of steroids on K in 10 patients. Each patient was studied twice: before and after 7 days of dexamethasone treatment of 16 mg/day orally. The results showed that K and V...