Real-time intraoperative guidance during minimally invasive neurosurgical procedures (e.g., endonasal transsphenoidal surgery) is often limited to endoscopy and CT-guided image navigation, which can be suboptimal at locating underlying blood vessels and nerves. Accidental damage to these critical structures can have severe surgical complications, including patient blindness and death. Photoacoustic image guidance was previously proposed as a method to prevent accidental injury. While the proposed technique remains promising, the original light delivery and sound reception components of this technology require alterations to make the technique suitable for patient use. This paper presents simulation and experimental studies performed with both an intact human skull (which was cleaned from tissue attachments) and a complete human cadaver head (with contents and surrounding tissue intact) in order to investigate optimal locations for ultrasound probe placement during photoacoustic imaging and to test the feasibility of a modified light delivery design. Volumetric x-ray CT images of the human skull were used to create k-Wave simulations of acoustic wave propagation within this cranial environment. Photoacoustic imaging of the internal carotid artery (ICA) was performed with this same skull. Optical fibers emitting 750 nm light were inserted into the nasal cavity for ICA illumination. The ultrasound probe was placed on three optimal regions identified by simulations: (1) nasal cavity, (2) ocular region, and (3) 1 mm-thick temporal bone (which received 9.2%, 4.7%, and 3.8% of the initial photoacoustic pressure, respectively, in simulations). For these three probe locations, the contrast of the ICA in comparative experimental photoacoustic images was 27 dB, 19 dB, and 12 dB, respectively, with delay-and-sum (DAS) beamforming and laser pulse energies of 3 mJ, 5 mJ, and 4.2 mJ, respectively. Short-lag spatial coherence (SLSC) beamforming improved the contrast of these DAS images by up to 15 dB, enabled visualization of multiple cross-sectional ICA views in a single image, and enabled the use of lower laser energies. Combined simulation and experimental results with the emptied skull and >1 mm-thick temporal bone indicated that the ocular and nasal regions were more optimal probe locations than the temporal ultrasound probe location. Results from both the same skull filled with ovine brains and eyes and the human cadaver head validate the ocular region as an optimal acoustic window for our current system setup, producing high-contrast (i.e., up to 35 dB) DAS and SLSC photoacoustic images within the laser safety limits of a novel, compact light delivery system design that is independent of surgical tools (i.e., a fiber bundle with 6.8 mm outer diameter, 2 mm-diameter optical aperture, and an air gap spacing between the sphenoid bone and fiber tips). These results are promising toward identifying, quantifying, and overcoming major system design barriers to proceed with future patient testing.

微创神经外科手术（例如鼻内经蝶窦手术）中的实时术中指导通常仅限于内窥镜检查和CT引导的图像导航，在定位下方的血管和神经方面可能不理想。这些关键结构的意外损坏可能导致严重的手术并发症，包括患者失明和死亡。先前提出了光声图像引导作为防止意外伤害的方法。虽然提出的技术仍然很有希望，但是该技术的原始光传输和声音接收组件需要进行更改，以使该技术适合患者使用。本文介绍了使用完整的人类头骨（从组织附件中清除）和完整的人体尸体头部（内容物和周围组织完整）进行的模拟和实验研究，以便研究在光声成像和超声成像中超声探头放置的最佳位置。测试改进的光传输设计的可行性。人体颅骨的体积X射线CT图像用于创建在此颅内环境中传播的声波的k波模拟。颈内动脉（ICA）的光声成像是用同一头颅骨进行的。将发射750 nm光的光纤插入鼻腔以进行ICA照明。将超声探头放置在通过模拟确定的三个最佳区域上：（1）鼻腔，（2）眼部区域，（3）1毫米厚的颞骨（在模拟中，它们分别接受了初始光声压的9.2％，4.7％和3.8％）。对于这三个探头位置，对比实验光声图像中ICA的对比度分别为27 dB，19 dB和12 dB，其中延迟和（DAS）波束形成和激光脉冲能量分别为3 mJ，5 mJ，和4.2 mJ。短时滞空间相干（SLSC）波束成形将这些DAS图像的对比度提高了15 dB，可以在单个图像中可视化多个横截面ICA视图，并可以使用较低的激光能量。空的颅骨和厚度大于1毫米的颞骨的模拟和实验结果相结合，表明眼部和鼻部区域比颞部超声探头的位置更为理想。同一块充满了羊脑和眼睛的头骨以及人类尸体头部的结果验证了眼部区域是我们当前系统设置的最佳声学窗口，可在其中产生高对比度（即高达35 dB）的DAS和SLSC光声图像新颖，紧凑的光传输系统设计的激光安全极限，与手术工具无关（例如，外径为6.8 mm，直径为2 mm的光纤束以及蝶骨和光纤尖端之间的空气间隙）。这些结果有望用于识别，量化和克服主要的系统设计障碍，以进行未来的患者测试。在新颖，紧凑的光传输系统设计的激光安全范围内，产生高对比度（即高达35 dB）的DAS和SLSC光声图像，该系统设计与手术工具无关（例如，外径为6.8 mm的光纤束，2直径的光学孔径，以及蝶骨和纤维尖端之间的气隙间隔）。这些结果有望用于识别，量化和克服主要的系统设计障碍，以进行未来的患者测试。在新颖，紧凑的光传输系统设计的激光安全范围内，产生高对比度（即，高达35 dB）的DAS和SLSC光声图像，而与手术工具无关（例如，外径为6.8 mm的光纤束，2直径的光学孔径，以及蝶骨和纤维尖端之间的气隙间隔）。这些结果有望用于识别，量化和克服主要的系统设计障碍，以进行未来的患者测试。