Reduced Blood Flow and Preserved Vasoreactivity Characterize Oxygen Hypometabolism Due to Incomplete Infarction in Occlusive Carotid Artery Diseases

Journal of Nuclear Medicine

Tatsuya Ishikawa¹  Tohru Shiga¹  Takuhito Narita¹  Yoshinobu Iwasaki¹  Nagara Tamaki¹  Chietsugu Katoh¹  Satoshi Kuroda¹  Kiyohiro Houkin¹ 

关键词: acetazolamide;    incomplete infarction;    oxygen metabolism;    PET;    cerebral ischemia;   

DOI  :  

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

Recent studies have clarified that hemodynamically compromised patients are at high risk for subsequent stroke. The acetazolamide test is widely used to detect the patients with hemodynamic compromise due to occlusive carotid artery disease. Previous studies have suggested that patients with impaired reactivity to acetazolamide had an increased oxygen extraction fraction (OEF) on PET. However, the underlying pathophysiology has not been defined in patients with reduced blood flow and preserved reactivity to acetazolamide due to carotid occlusive diseases regardless of a normal appearance on MRI. This study aimed to clarify hemodynamic and metabolic parameters in such patients, using 15O gas and 11C-flumazenil (FMZ) PET. Methods: Our study included 15 patients who had reduced cerebral blood flow (CBF) and preserved cerebrovascular reactivity (CVR) to acetazolamide in the ipsilateral middle cerebral artery territory due to occlusive carotid diseases on N-isopropyl-p-123I-iodoamphetamine (123I-IMP) SPECT. We determined the CBF, cerebral metabolic rate for oxygen (CMRo2), cerebral blood volume (CBV), and OEF using 15O gas PET. The binding potential for 11C-FMZ was also measured in 5 patients. All patients were medically treated and followed-up during a mean period of 2.7 y. Results: 15O gas PET scans revealed that the ipsilateral CBF and CMRo2 were reduced to 80% ± 11% (P < 0.0001) and 78% ± 8% (P < 0.0001) of the contralateral side, respectively. However, there was no significant side-to-side difference in the CBV and OEF. The ipsilateral binding potential for 11C-FMZ was also significantly reduced to 82% ± 2% of the contralateral side (P < 0.05), being very similar to the asymmetry of the CBF and CMRo2. No patients suffered further ischemic stroke in the ipsilateral hemisphere during the follow-up period. Conclusion: Our results strongly suggest that a reduced CBF and a normal CVR characterize oxygen hypometabolism probably due to ischemia-related neuronal lossnamely, incomplete infarction. Such an ischemic lesion is not hemodynamically compromised and is at very low risk for a subsequent ischemic stroke even if the patient is medically treated.

【 授权许可】

Unknown