BOLD MRI--APPLICATION TO INTRA-RENAL OXYGENATION

急性肾功能衰竭(ARF)是一种综合征，可以广泛地定义为 肾功能迅速恶化，导致肾积聚 含氮废物，如尿素和肌酐。这是一个重要的临床 是一种常见的医院获得性综合征，死亡率很高 房费(约50%)。急性缺血性脑病的病理生理学研究进展 肾功能衰竭是临床ARF最常见的形式，它很复杂，不是 然而，这一点很好理解。基于之前对动物模型的研究，它是 知道急性肾功能衰竭会对延髓造成损害，甚至 在正常情况下必须在低氧环境中发挥作用。 从而对影响髓质缺氧的机制有了一定的了解 在ARF的病理生理学研究中具有重要意义。 到目前为止，仅对肾内氧分压进行了测量。 将氧气敏感的微电极植入肾脏 动物的薄壁组织，这是一个微妙而繁琐的过程，不切实际 用于人体研究。BOLD(血液氧合水平依赖)MRI具有 显示出作为一种非侵入性方法在区域基础上进行评估的潜力 氧气供需平衡的变化。我们有 之前证明了大胆的核磁共振成像与 人体肾脏和早期动物数据的活体测量 侵入性微电极。这些研究为第一种观点提供了证据 表示人类肾脏有相当程度缺氧的时间 延髓。 在这项建议中，我们将通过比较来进一步评估这项技术 在氧合动物模型中获得的BOLD MRI数据 先前使用侵入性微电极获得的测量结果 技术。然后我们将把这项技术应用于动物模型和 人类受试者将获得有关肾脏生理的新信息/ 病理生理学，尤其与急性肾功能衰竭有关。 一种非侵入性方法评估区域的有效性 体内肾脏的氧合作用应有助于确定治疗的特征 和保护机制，从而导致改善治疗和 急性肾功能衰竭的预防措施。

Acute renal failure (ARF) is a syndrome that can be broadly defined as rapid deterioration of renal function resulting in the accumulation of nitrogenous wastes such as urea and creatinine. It is a major clinical problem and is a common hospital acquired syndrome with high mortality rates (approximately 50 percent). The pathophysiology of ischemic acute renal failure, the most common form of clinical ARF, is complex and not yet well understood. Based on previous studies on animal models, it is known that acute renal failure involves damage to the medulla which even under normal circumstances must function in an hypoxic environment. Hence an understanding of mechanisms that influence medullary hypoxia is important in the study of pathophysiology of ARF. To date, measurements of intrarenal oxygen tension have been made only with oxygen-sensitive microelectrodes implanted into the renal parenchyma of animals, a delicate and tedious procedure and impractical for human studies. BOLD (Blood Oxygenation Level Dependent) MRI has shown potential as a noninvasive method to assess on a regional basis the changes in the balance of oxygen supply and demand. We have previously demonstrated a strong correspondence between BOLD MRI measurements in vivo in human kidneys and earlier animal data using invasive microelectrodes. These studies provided evidence for the first time indicating a substantial degree of hypoxia in the human renal medulla. In this proposal, we will further evaluate this technique by comparing the BOLD MRI data obtained in an animal model with oxygenation measurements previously obtained with an invasive microelectrode technique. We will then apply the technique to both animal models and human subjects to derive new information about renal physiology/ pathophysiology especially related to ARF. The availability of a noninvasive method to evaluate regional oxygenation in kidneys in vivo should help to characterize therapeutic and protective mechanisms and thus lead to improved therapeutic and preventive measures for acute renal failure.