Abstract: AIM:To observe the early changes of local cerebral blood supply in dogs during the acute vertebral artery stenosis by ⁹⁹T^cm-ECD cerebral blood flow perfusion imaging (CBFPI). METHODS:Twenty- four dogs were randomized into groups of normal controls (A), moderate stenosis (B), severe stenosis (C) and arterial occlusion (D), with 6 in each group. Group A were free from any intervention, but Group B, C and D were undergone ligation of the right vertebral arteries by the extent of 50% ～ 69% (Group B), 70% ～ 99% (Group C) or 100% (Group D). The imaging agents were injected intravenously 0. 5-1 h after ligation and the single photon emission computed tomography (SPECT) was performed after 1 h. RESULTS: CBFPI examination of the early changes of cerebral blood supply during the acute vertebral artery stenosis by visualization showed that the sensitivity was 33. 3%, 83. 3% and 100% in Group B, C and D, respectively, with an average sensitivity of 72. 2%, while semi-quantitative assessment suggested that the sensitivity was 50%, 100% and 100% in the three groups, respectively, with an average sensitivity of 83. 3% .When examining the activity ratio for regions of interest(ROI) by semi-quantitative ⁹⁹T^cm-ECD CBFPI, the findings suggested that Group D and C decreased significantly (exception in cerebellum in Group C), but Group B had no evident changes, as compared with Group A. By comparison of the groups of B-C, BD and C-D, differences were observed in the right temporal lobes, whereas the changes in left temporal lobes were seen in Group B-C or B-D. The changes were seen in occipital lobes when groups of B and D were compared, but with no differences in cerebellum. CONCLUSION:The degree of stenosis in vertebral arteries may involve varied regions, the temporal lobe is susceptive, followed by occipital lobe, while cerebellum is somewhat resistant from the involvement.

Key words: single photon emission computed tomography (SPECT), ⁹⁹T^cm-ethyl cysteinate dimer (ECD), cerebral blood flow perfusion imaging, vertebral artery stenosis