Estimation of the regional cerebral metabolic rate of oxygen consumption with proton detected ¹⁷O MRI during precision ¹⁷O₂ inhalation in swine

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• 作者：Eric A. Mellon ; R. Shashank Beesam ; James E. Baumgardner ; Arijitt Borthakur ; Walter R. Witschey 2nd ; Ravinder Reddy
• 关键词：Oxygen-17 ; ¹⁷O MRI ; ¹⁷O MRS ; Cerebral metabolic oxygen consumption ; Arterial input function
• 刊名：Journal of Neuroscience Methods
• 出版年：2009
• 出版时间：30 April 2009
• 年：2009
• 卷：179
• 期：1
• 页码：29-39
• 全文大小：729 K

文摘

Despite the importance of metabolic disturbances in many diseases, there are currently no clinically used methods for the detection of oxidative metabolism in vivo. To address this deficiency, ¹⁷O MRI techniques are scaled from small animals to swine as a large animal model of human inhalation and circulation. The hemispheric cerebral metabolic rate of oxygen consumption (CMRO₂) is estimated in swine by detection of metabolically produced H₂¹⁷O by rapid T_1ρ-weighted proton magnetic resonance imaging on a 1.5 T clinical scanner. The ¹⁷O is delivered as oxygen gas by a custom, minimal-loss, precision delivery breathing circuit and converted to H₂¹⁷O by oxidative metabolism. A model for gas arterial input is presented for the deeply breathing large animal. The arterial input function for recirculation of metabolic water is measured by arterial blood sampling and high field ¹⁷O spectroscopy. It is found that minimal metabolic water “wash-in” occurs before 60 s. A high temporal resolution pulse sequence is employed to measure CMRO₂ during those 60 s after delivery begins. Only about one tidal volume of ¹⁷O enriched oxygen gas is used per measurement. Proton measurements of signal change due to metabolically produced water are correlated with ¹⁷O in vivo spectroscopy. Using these techniques, the hemispheric CMRO₂ in swine is estimated to be 1.23 ± .26 μmol/g/min, consistent with existing literature values. All of the technology used to perform these CMRO₂ estimates can easily be adapted to clinical MR scanners, and it is hoped that this work will lead to future studies of human disease.