IEEE Trans Pattern Anal Mach Intell. 2021 Jul;43(7):2206-2219. doi: 10.1109/TPAMI.2021.3075366. Epub 2021 Jun 9.
Light scattering by tissue severely limits how deep beneath the surface one can image, and the spatial resolution one can obtain from these images. Diffuse optical tomography (DOT) is one of the most powerful techniques for imaging deep within tissue - well beyond the conventional ∼ 10-15 mean scattering lengths tolerated by ballistic imaging techniques such as confocal and two-photon microscopy. Unfortunately, existing DOT systems are limited, achieving only centimeter-scale resolution. Furthermore, they suffer from slow acquisition times and slow reconstruction speeds making real-time imaging infeasible. We show that time-of-flight diffuse optical tomography (ToF-DOT) and its confocal variant (CToF-DOT), by exploiting the photon travel time information, allow us to achieve millimeter spatial resolution in the highly scattered diffusion regime ( mean free paths). In addition, we demonstrate two additional innovations: focusing on confocal measurements, and multiplexing the illumination sources allow us to significantly reduce the measurement acquisition time. Finally, we rely on a novel convolutional approximation that allows us to develop a fast reconstruction algorithm, achieving a 100× speedup in reconstruction time compared to traditional DOT reconstruction techniques. Together, we believe that these technical advances serve as the first step towards real-time, millimeter resolution, deep tissue imaging using DOT.
组织的光散射严重限制了人们能够对表面以下多深的区域进行成像，以及从这些图像中获得的空间分辨率。漫射光学断层扫描（DOT）是用于对组织深处成像的最强大技术之一——远远超过了诸如共聚焦和双光子显微镜等弹道成像技术所允许的常规 10-15 个平均散射长度。不幸的是，现有的 DOT 系统受到限制，只能实现厘米级的分辨率。此外，它们还存在采集时间慢和重建速度慢的问题，使得实时成像变得不可行。我们表明，利用飞行时间漫射光学断层扫描（ToF-DOT）及其共聚焦变体（CToF-DOT），通过利用光子飞行时间信息，使我们能够在高度散射的扩散区域（平均自由程）实现毫米级的空间分辨率。此外，我们还展示了另外两项创新：关注共聚焦测量，以及复用照明源，使我们能够显著减少测量采集时间。最后，我们依赖于一种新颖的卷积近似，使我们能够开发出一种快速重建算法，与传统的 DOT 重建技术相比，重建时间提高了 100 倍。总的来说，我们相信这些技术进步是实现使用 DOT 进行实时、毫米分辨率、深层组织成像的第一步。
