Optoacoustic monitoring of cerebral blood oxygenation

描述(由申请人提供)： 通过准确和持续地监测脑氧合，可以促进对严重创伤性脑损伤等危及生命的急性神经疾病的治疗。然而，目前的监测系统是侵入性的，需要插入颈内静脉球或直接将探头插入大脑。近红外光谱学是一种无创监测脑血氧含量的方法，前景看好，但尚未得到令人满意的校准，以提供成人的定量测量。目前尚无准确、无创、连续的脑血氧监测系统。我们提出了一种新的光声技术，并在体外和体内进行了测试，该技术直接从上矢状窦准确而连续地测量血液氧合，由于光声技术的高分辨率，这种结构很容易定位。光声技术是基于激光脉冲产生的超声波(光声)波，并由灵敏的声学换能器检测这些波。血氧的光声监测利用氧合和脱氧血红蛋白在近红外光谱范围内的光吸收系数的公认差异。在我们目前的NIH R21项目中，由NINDS根据计划公告PA-98-050(旨在开发包括光声脑监测在内的创新技术)的拨款支持，我们设计、建造并测试了用于准确监测脑血氧的非侵入性光声系统。我们在体外和体内(绵羊)的研究表明：(1)光声波的参数与血液氧合呈线性关系；(2)使用特殊设计的换能器和光声探测器，即使厚骨的光声衰减也能进行灵敏检测；以及(3)这项技术可以高精度地测量血液氧合。在这项拨款申请中，我们建议在这项计划公告下进一步开发这项技术。该项目的具体目标是：(1)改进光声系统，以提供多波长测量并在身体上对该系统进行评估；(2)在志愿者体内对该系统进行评估；以及(3)在创伤性脑损伤患者中评估该系统的性能。到该项目结束时，该系统将得到充分开发，以允许进行多中心临床试验。

DESCRIPTION (provided by applicant): Management of acute, life-threatening neurologic illnesses, such as severe traumatic brain injury, is facilitated by accurate and continuous monitoring of cerebral oxygenation. However, current monitoring systems are invasive, requiring either cannulation of the internal jugular venous bulb or insertion of a probe directly into the brain. Nearinfrared spectroscopy, a noninvasive method of monitoring cerebral blood oxygenation, is promising, but has yet to be satisfactorily calibrated to provide quantitative measurement in adults. At present there is no system for accurate, noninvasive, and continuous monitoring of cerebral blood oxygenation. We proposed and performed in vitro and in vivo testing of a novel optoacoustic technique that accurately and continuously measures blood oxygenation directly from the superior sagittal sinus, a structure that can easily be localized due to the high resolution of the optoacoustic technique. The optoacoustic technique is based on generation of ultrasonic (optoacoustic) waves by laser pulses and detection of these waves by a sensitive acoustic transducer. Optoacoustic monitoring of blood oxygenation utilizes well-established differences in the optical absorption coefficients of oxy- and deoxyhemoglobin in the nearinfrared spectral range. During our current NIH R21 project supported by an NINDS grant under the Program Announcement PA-98-050 (directed at the development of innovative technologies including photoacoustic brain monitoring), we designed, built, and tested a noninvasive optoacoustic system for accurate monitoring of cerebral blood oxygenation. Our in vitro and in vivo (in sheep) studies demonstrated that: (1) the parameters of the optoacoustic waves are linearly dependent on blood oxygenation; (2) the use of specially designed transducers and optoacoustic probes allows sensitive detection despite optical and acoustic attenuation by thick bone; and (3) this technique can measure blood oxygenation with high accuracy. In this grant application, we propose to further develop this technique under this program announcement. The specific aims of the project are: (1) to modify the optoacoustic system to provide multiwavelength measurements and perform evaluation of the system in cadavers; (2) to evaluate it in vivo in volunteers; and (3) to evaluate the system performance in patients with traumatic brain injury. By the end of the project the system will be developed sufficiently to permit multi-center clinical trials.