Cerebral blood volume measurements using dynamic contrast-enhanced x-ray computed tomography: application to isoflurane anaesthetic studies

A convenient and simple method of measuring cerebral blood volume (CBV) wil l aid in the clinical management of patients with cerebrovascular diseases and head trauma. Using a two-compartment model to characterize the distribu tion of x-ray contrast agent in the brain, we have developed a non-equilibr ium (dynamic) x-ray CT method to measure CBV and have applied this method t o study the effects of isoflurane. CBV and cerebral blood flow (CBF, ex vivo) measurements were made in two gr oups of New Zealand White rabbits at varying (study group) and constant (co ntrol group) arterial CO2 concentration. ANOVA for repeated measures was us ed on the control data to determine the precision of our two-compartment CT -CBV method. The results showed that the precision of our CT-CBV measuremen t was 9.8%. In addition a paired t-test analysis of the control data reveal ed that the duration of isoflurane anaesthesia had no effect on the repeate d measurements of CBV or CBE The rate of change in CBV (0.049 ml/100 g/mmHg ) and CBF (6.2 ml/min/100 g/mmHg) with respect to changes in arterial CO2 c oncentration under the influence of isoflurane anaesthesia was similar to t hose reported in previous studies, thus validating our experimental CT-CBV and CBF measurements. Our CT-CBV method will lead to more information on th e relationship between CBV and CBF under different pharmacological interven tions in both normal and disease conditions.