Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, Pasadena, CA, USA.
Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
Nat Biomed Eng. 2022 May;6(5):584-592. doi: 10.1038/s41551-021-00735-8. Epub 2021 May 31.
Blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging of the human brain requires bulky equipment for the generation of magnetic fields. Photoacoustic computed tomography obviates the need for magnetic fields by using light and sound to measure deoxyhaemoglobin and oxyhaemoglobin concentrations to then quantify oxygen saturation and blood volumes. Yet, the available imaging speeds, fields of view (FOV), sensitivities and penetration depths have been insufficient for functional imaging of the human brain. Here, we show that massively parallel ultrasonic transducers arranged hemispherically around the human head can produce tomographic images of the brain with a 10-cm-diameter FOV and spatial and temporal resolutions of 350 µm and 2 s, respectively. In patients who had a hemicraniectomy, a comparison of functional photoacoustic computed tomography and 7 T BOLD functional magnetic resonance imaging showed a strong spatial correspondence in the same FOV and a high temporal correlation between BOLD signals and photoacoustic signals, with the latter enabling faster detection of functional activation. Our findings establish the use of photoacoustic computed tomography for human brain imaging.
人脑的血氧水平依赖（BOLD）功能磁共振成像需要大型设备来产生磁场。光声计算机断层扫描通过使用光和声来测量脱氧血红蛋白和氧合血红蛋白浓度，从而量化氧饱和度和血液量，从而避免了磁场的需求。然而，现有的成像速度、视野（FOV）、灵敏度和穿透深度对于人脑的功能成像来说还不够。在这里，我们展示了可以围绕人头半球排列的大量并行超声换能器，以产生具有 10cm 直径 FOV 的大脑层析图像，空间和时间分辨率分别为 350μm 和 2s。在接受半脑切除术的患者中，功能光声计算机断层扫描和 7T BOLD 功能磁共振成像的比较显示，在相同的 FOV 中具有很强的空间对应关系，BOLD 信号和光声信号之间具有很高的时间相关性，后者能够更快地检测到功能激活。我们的发现为光声计算机断层扫描在人脑成像中的应用奠定了基础。
