Purpose

Live intra-operative functional imaging has multiple potential clinical applications, such as localization of ischemia, assessment of organ transplantation success and perfusion monitoring. Recent research has shown that live monitoring of functional tissue properties, such as tissue oxygenation and blood volume fraction, is possible using multispectral imaging in laparoscopic surgery. While the illuminant spectrum is typically kept constant in laparoscopic surgery and can thus be estimated from preoperative calibration images, a key challenge in open surgery originates from the dynamic changes of lighting conditions.

Methods

The present paper addresses this challenge with a novel approach to light source calibration based on specular highlight analysis. It involves the acquisition of low-exposure time images serving as a basis for recovering the illuminant spectrum from pixels that contain a dominant specular reflectance component.

Results

Comprehensive in silico and in vivo experiments with a range of different light sources demonstrate that our approach enables an accurate and robust recovery of the illuminant spectrum in the field of view of the camera, which results in reduced errors with respect to the estimation of functional tissue properties. Our approach further outperforms state-of-the-art methods proposed in the field of computer vision.

Conclusion

Our results suggest that low-exposure multispectral images are well suited for light source calibration via specular highlight analysis. This work thus provides an important first step toward live functional imaging in open surgery.

中文翻译：

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手术中多光谱成像的光源校准。

 目的

实时术中功能成像具有多种潜在的临床应用，例如缺血定位、器官移植成功评估和灌注监测。最近的研究表明，在腹腔镜手术中使用多光谱成像可以实时监测组织氧合和血容量分数等功能组织特性。虽然腹腔镜手术中的光源光谱通常保持恒定，因此可以根据术前校准图像进行估计，但开放手术中的一个关键挑战源于照明条件的动态变化。

 方法

本文通过一种基于镜面高光分析的光源校准新方法来解决这一挑战。它涉及采集低曝光时间图像，作为从包含主要镜面反射分量的像素中恢复光源光谱的基础。

 结果

使用一系列不同光源进行的综合计算机和体内实验表明，我们的方法能够准确而稳健地恢复相机视野中的光源光谱，从而减少功能组织估计方面的误差特性。我们的方法进一步优于计算机视觉领域提出的最先进的方法。

 结论

我们的结果表明，低曝光多光谱图像非常适合通过镜面高光分析进行光源校准。因此，这项工作为开放手术中的实时功能成像迈出了重要的第一步。