Evaluation of successive Tc-99m brain angiography and vasoactive drugs on occlusive cerebrovascular disease

Cerebral circulation in the patients with unilateral occlusive cerebrovascular disease (CVD) in chronic stage was evaluated by radionuclide angiography (RNA) using Tc-99m pertechnetate. RNA (each Tc-99m dose = 20 mCi) was repeated in short time interval. Employed parameters were as follows; appearance to peak time (APT), brain transit time (BTT), peak count (PC) and up slope (US). These parameters were calculated from time activity curve (TAC) of ''region of interest'' on each hemisphere and the values obtained in affected side were compared with those of normal side and control hemisphere. Reproducibility of these values were satisfactory in PC and US. The results obtained were as follows: In affected hemisphere, PC and US were significantly reduced, while APT and BTT were not significantly affected. The ratio of PC and US between left and right hemispheres increased in the patients with CVD and the latter was particularly significant to detect the abnormality. Effect of vasoactive drugs such as papaverine, acetazolamide, angiotensin II or methoxamine on these parameters was studied in 24 patients with CVD and 16 patients without CVD. Papaverine and acetazolamide increased significantly PC and US in normal hemisphere of patients without CVD and US in normal hemisphere of patients with CVD, while US in these hemispheres were decreased under high blood pressure induced by angiotensin II and methoxamine. These responses, however, were mild or not detected in the affected hemispheres. (J.P.N.)