急性期脳梗塞におけるポジトロンCTを利用した脳血流，脳酸素代謝，脳糖代謝そしてpHについての研究

STUDIES OF CEREBRAL BLOOD FLOW, CEREBRAL OXYGEN METABOLISM, CEREBRAL GLUCOSE METABOLISM, AND TISSUE PH IN HUMAN ACUTE CEREBRAL INFARCTION USING POSITRON EMISSION TOMOGRAPHY

　抄録　脳梗塞急性期の脳循環代謝を検討するため，positron emission tomographyを利用し¹⁵O study，¹⁸FDG study，そして¹¹C-DMO studyを行ない，CBF,CMRO₂，OER,CMRGlu，そしてtissue pHを発症より48時間以内の脳梗塞患者について測定した。また，CBFとCMRGluの関係，CMRO₂とCMRGluの関係についてそれぞれMCIイメージ，OGIイメージを作り検討した。病側では，再開通例を除き，CBF,CMRO2,CMRGluの低下を認め，OERの増加を示した例を認めた。CMRO₂が65μmol以上の皮質とそれ未満の皮質では，MCIとOGIは異なった傾向がみられた。また，脳梗塞のtissue pHは反対側と比ベアシドーシスを示した例とアルカローシスを示した例があった。tissue pHに対するCBFの閾値は14ml前後にあることも示唆された。まだ多くのmethodologicalな問題があるが，このpreli—minary studyは，CBF,CMRO₂，CMRGluそしてtissue pHの相互の関係について検討することは脳梗塞における脳循環代謝を明らかにするために必要であることを示唆していると考える。

It is necessary for treatment and deciding prog-nosis to make clear about changes of cerebral blood flow and metabolism in acute cerebral infarction. This preliminary PET study was designed to investigate physiological and bioche-mical changes in acute cerebral infarction by positron emission tomography (PET). PET stu-dies were performed in six patients with acute cerebral infarction within 48 hours after onset of stroke using continuous inhalation of C¹⁵O₂ for cerebral blood flow (CBF),¹⁵O₂ for cerebral meta-bolic rate for oxygen (CMRO₂), ¹¹CO for cerebral blood volume, the intravenous injection of ¹¹C-dimethyloxazolidinedione for tissue pH and the intravenous injection of ¹⁸F-fluorodeoxyglucose for cerebral metabolic rate for glucose (CMRGlu). Metabolic coupling index (MCI) image was made from CBF image and CMRGlu image to investi-gate relation between CBF and CMRGlu. Also oxygen glucose index (OGI) image was made from CMRO₂ image and CMRGlu image to investigate relation between CMRO₂ and CMRGlu.

Preliminary results demonstrate that reduction of CBF, CMRO₂, and CMRGlu in the affected cortex except for reperfusion case. Increase of OER was recognized four of six cases. Patterns of MCI and OGI in the cortex which CMRO₂ value is less than 65 mol/100 ghnin were diffe-rent from those in the cortex which CMRO₂ value is more than 65. MCI of the affected cortex (CMRO₂<65) decreased relative to that of the cortex (CMRO₂≧65). OGI of the affected cortex (CMRO₂<65) significantly decreased in comparison with that of the cortex (CMRO₂≧65). Two patients showed decrease of tissue pH and reperfusion case showed increase of tissue pH in infarcted area as compared to contralateral cortex. In addition it was suggested that threshold of CBF for tissue pH was approximately 14 ml/100g/min.

However there are methodological limitations of PET, this preliminary study suggests importance to investigate relation between CBF, CMRO₂, CMRGlu, and tissue pH.