• Nuclear Medicine and Molecular Imaging
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• v.42 no.4
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• pp.267-274
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• 2008

Purpose: Transient neurological deterioration (TND) is one of the complications after extracranial-intracranial bypass surgery, and it has been assumed to be caused by postoperative transient hyperperfusion. This study was performed to evaluate the relationship between TND and preoperative and postoperative cerebral perfusion status on brain perfusion SPECT following superficial temporal artery - middle cerebral artery (STA-MCA) anastomosis surgery. Materials and Methods: A total of 60 STA-MCA anastomosis surgeries of 56 patients (mean age: $50{\pm}16$ yrs; M:F=29:27; atherosclerotic disease: 33, moyamoya disease: 27) which were done between September 2003 and July 2006 were enrolled. The resting cerebral perfusion and cerebral vascular reserve (CVR) after acetazolamide challenge were measured before and 10 days after surgery using 99mTc-ethylcysteinate dimer (ECD) SPECT. Moreover, the cerebral perfusion was measured on the third postoperative day. With the use of the statistical parametric mapping and probabilistic brain atlas, the counts for the middle cerebral artery (MCA) territory were calculated for each image, and statistical analyses were performed. Results: In 6 of 60 cases (10%), TND occurred after surgery. In all patients, the preoperative cerebral perfusion of affected MCA territory was significantly lower than that of contralateral side (p=0.002). The cerebral perfusion on the third and tenth day after surgery was significantly higher than preoperative cerebral perfusion (p=0.001, p=0.02). In TND patients, basal cerebral perfusion and CVR on preoperative SPECT were significantly lower than those of non-TND patients (p=0.01, p=0.05). Further, the increases in cerebral perfusion on the third day after surgery were significant higher than those in other patients (p=0.008). In patients with TND, the cerebral perfusion ratio of affected side to contralateral side on third postoperative day was significantly higher than that of other patients (p=0.002). However, there was no significant difference of the cerebral perfusion ratio on preoperative and tenth postoperative day between patients with TND and other patients. Conclusion: In patients with TND, relative and moderate hyperperfusion was observed in affected side after bypass surgery. These finding may help to understand the pathophysiology of TND.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.6
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• pp.293-301
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• 2006

Purpose: The aim of the study was to evaluate the hemodynamic changes after successful bypass surgery in patients with atherosclerotic stenosis in ICA using $^{99m}Tc-ECD$ SPECT. Materials and Methods: Fourteen patients (M:F=8:6, mean age; $60{\pm}9$ years) who underwent STA-MCA anastomosis for unilateral atherosclerotic cerebrovascular disease were enrolled. $^{99m}Tc-ECD$ 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. Results: The mean resting perfusion and decrease in perfusion reserve in affected ICA territory on preoperative scan was $52.4{\pm}3.5\;and\;-7.9{\pm}4.7%$, respectively. The resting perfusion was significantly improved after surgery on early-postoperative scan (mean $53.7{\pm}2.7$) and late-postoperative scan (mean $53.3{\pm}2.5$) compared with preoperative images (p<0.05, respectively). Resting perfusion did not showed further improvement on late-postoperative scan compared with early-postoperative scan. The perfusion reserve was $-3.7{\pm}2.6%$ on early-postoperative scan, and $-1.6{\pm}2.3%$ on late-postoperative scan, which was significantly improved after surgery. Additionally, further improvement of perfusion reserved as observed on late-postoperative scan (p<0.05). While, in the unaffected ICA territory, no significant changes in the resting perfusion and perfusion reserve was observed. Conclusion: 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.