Department of Ophthalmology, Clinical Sciences Lund, Lund University, Sweden.
Department of Ophthalmology, Clinical Sciences Lund, Lund University, Sweden; Skåne University Hospital, Department of Clinical Sciences Lund, Ophthalmology Lund, Sweden.
Microvasc Res. 2023 Nov;150:104573. doi: 10.1016/j.mvr.2023.104573. Epub 2023 Jun 28.
Optical spectroscopy is commonly used clinically to monitor oxygen saturation in tissue. The most commonly employed technique is pulse oximetry, which provides a point measurement of the arterial oxygen saturation and is commonly used for monitoring systemic hemodynamics, e.g. during anesthesia. Hyperspectral imaging (HSI) is an emerging technology that enables spatially resolved mapping of oxygen saturation in tissue (sO), but needs to be further developed before implemented in clinical practice. The aim of this study is to demonstrate the applicability of HSI for mapping the sO in reconstructive surgery and demonstrate how spectral analysis can be used to obtain clinically relevant sO values.
Spatial scanning HSI was performed on cutaneous forehead flaps, raised as part of a direct brow lift, in eight patients. Pixel-by-pixel spectral analysis, accounting for the absorption from multiple chromophores, was performed and compared to previous analysis techniques to assess sO.
Spectral unmixing using a broad spectral range, and accounting for the absorption of melanin, fat, collagen, and water, provided a more clinically relevant estimate of sO than conventional techniques, where typically only spectral features associated with absorption of oxygenated (HbO) and deoxygenated (HbR) hemoglobin are considered. We demonstrate its clinical applicability by generating sO maps of partially excised forehead flaps showed a gradual decrease in sO along the length of the flap from 95 % at the flap base to 85 % at the flap tip. After being fully excised, sO in the entire flap decreased to 50 % within a few minutes.
The results demonstrate the capability of sO mapping in reconstructive surgery in patients using HSI. Spectral unmixing, accounting for multiple chromophores, provides sO values that are in accordance with physiological expectations in patients with normal functioning microvascularization. Our results suggest that HSI methods that yield reliable spectra are to be preferred, so that the analysis can produce results that are of clinical relevance.
光学光谱学常用于临床监测组织中的氧饱和度。最常用的技术是脉搏血氧饱和度测定法，它提供动脉氧饱和度的单点测量，常用于监测全身血液动力学，例如在麻醉期间。高光谱成像（HSI）是一种新兴技术，可实现组织中氧饱和度的空间分辨映射（sO），但在临床实践中应用之前需要进一步开发。本研究旨在证明 HSI 在重建手术中用于映射 sO 的适用性，并展示如何进行光谱分析以获得临床相关的 sO 值。
对作为直接额部提升一部分而升高的皮肤额部皮瓣进行空间扫描 HSI。对每个像素进行光谱分析，考虑到多个色团的吸收，与以前的分析技术进行比较以评估 sO。
使用宽光谱范围并考虑黑色素、脂肪、胶原和水的吸收进行光谱解混，提供了比传统技术更具临床相关性的 sO 估计，传统技术通常仅考虑与氧合（HbO）和去氧（HbR）血红蛋白吸收相关的光谱特征。我们通过生成部分切除的额部皮瓣的 sO 图来证明其临床适用性，皮瓣的 sO 从皮瓣底部的 95%逐渐减少到皮瓣尖端的 85%。完全切除后，整个皮瓣中的 sO 在几分钟内降至 50%。
这些结果表明 HSI 在具有正常功能的微血管化患者的重建手术中进行 sO 映射的能力。考虑到多个色团的光谱解混提供了与生理预期相符的 sO 值。我们的结果表明，应优先选择能产生可靠光谱的 HSI 方法，以便分析能够产生具有临床相关性的结果。
