We studied the pre and post-operative perfusion reserve using Diamox 99mTc-HMPAO SPECT in 7 patients with chronic occlusive cerebral arteries and then compared the results with PET. STAMCA anastomosis was performed on 5 patients, while a carotid endarterectomy was done on 2 patients. The cerebral blood flow, the vascular response to CO2 or Diamox, the oxygen extraction fraction and transit time (CBV/CBF) were measured by PET. In the pre-operative state, the visual evaluations for hypoperfusion area at rest were agreed in 5 out of 7 patients in HMPAO SPECT and PET studies. In the remaining 2 patients, hypoperfusion areas were only detected in the PET study. The pre-operative evaluation of perfusion reserve was agreed in 2 patients. In the remaining 5 patients, 3 patients showed definite positive (++) in PET and positive (+) in HMPAO SPECT, and one patient showed positive (+) in PET and negative (-) in HMPAO SPECT. The post-operative change of hypoperfusion areas was well agreed in HMPAO SPECT and PET studies. However, the change of perfusion reserve was underestimated in HMPAO SPECT compared with PET. In the semiquantitative and quantitative analyses, the count rate ratios (affected/unaffected side) in HMPAO SPECT were apparently higher than those of CBF in PET. The postoperative change of the count rate ratios in HMPAO SPECT were smaller than those of CBF in PET. There was no significant correlation between the change in the ratio of the HMPAO SPECT after the administration of Diamox and the oxygen extraction fraction, and it was thus thought to be impossible to predict the areas with an increased oxygen extraction fraction. Thus, Diamox HMPAO SPECT may underestimate the areas of hypoperfusion or decrease in perfusion reserve when compared with PET. We should consider these limitations in the evaluation of pre and post operative cerebral hemodynamics.
|Number of pages||12|
|Publication status||Published - 1994|
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