Quantitative analysis of 99mTc-HMPAO kinetics in epilepsy.

A convection-diffusion model is applied for the determination of cerebral circulation parameters in patients with frontal lobe epilepsy. The method employs 99mTc-HMPAO, dynamic brain imaging and SPECT. The model takes into account both the capillary and cell permeabilities of HMPAO. Experiments were performed in 41 patients with epilepsy and 10 patients without evident cerebrovascular disease. The results indicate that in the inter ictal epileptic foci, cerebral blood flow was reduced (18% +/- 19%), cerebral blood volume was increased (21% +/- 14%), and the capillary permeability of HMPAO in the affected side was on the average 50% of the value in the contralateral side, whereas the reflux from brain tissue to blood was increased. These findings mean that HMPAO diffusion across the blood brain barrier is restricted and HMPAO slackly interacts with the intra cellular component of the inter ictal epileptic foci.