Hemodynamic outcome of successful bypass surgery in patients with atherosclerotic cerebrovascular disease: a study with acetazolamide and 99mTc-ECD SPECT

The aim of the study was to evaluate the hemodynamic changes after successful bypass surgery in patients with atherosclerotic stenosis in ICA using 99mTc-ECD SPECT. Fourteen patients (M:F = 8:6, mean age; 60 ± 9 years) who underwent STA-MCA anastomosis for unilateral atherosclerotic cerebrovascular disease were enrolled. 99mTc-ECD basal/acetazolamide perfusion SPECT studies were performed before, 10 days and 6 months after bypass surgery. Perfusion reserve was defined as the % changes after acetazolamide over rest image. Regional cerebral blood flow and perfusion reserve were compared preoperative, early-postoperative and late-postoperative scans. The mean resting perfusion and decrease in perfusion reserve in affected ICA territory on preoperative scan was 52.4 ± 3.5 and -7.9 ± 4.7%, respectively. The resting perfusion was significantly improved after surgery on early-postoperative scan (mean 53.7 ± 2.7) and late-postoperative scan (mean 53.3 ± 2.5) compared with preoperative images (ρ < 0.05, respectively). Resting perfusion did not showed further improvement on late-postoperative scan compared with early-postoperative scan. The perfusion reserve was -3.7 ± 2.6% on early-postoperative scan, and -1.6 ± 2.3% on late-postoperative scan, which was significantly improved after surgery. Additionally, further improvement of perfusion reserved a observed on late-postoperative scan (ρ < 0.05). While, in the unaffected ICA territory, on significant changes in the resting perfusion and perfusion reserve was observed. The improvement of resting perfusion and perfusion reserve in early-postoperative scan reflects the immediate restoration of the cerebral blood flow by bypass surgery. In contrasts, further improvement of perfusion reserve showing on late-postoperative scan may indicate a good collateral development after surgery, which may indicate good surgical outcome after surgery