Princess Margaret Cancer Center, University Health Network, Toronto, Ontario, Canada.
Department of Medical Biophysics, University of Toronto, Faculty of Medicine, Toronto, Ontario, Canada.
J Biophotonics. 2019 May;12(5):e201800271. doi: 10.1002/jbio.201800271. Epub 2019 Mar 20.
The rate of complete resection of glioma has improved with the introduction of 5-aminolevulinic acid-induced protoporphyrin IX (PpIX) fluorescence image guidance. Surgical outcomes are further enhanced when the fluorescence signal is decoupled from the intrinsic tissue optical absorption and scattering obtained from diffuse reflectance measurements, yielding the absolute PpIX concentration, [PpIX]. Spatial frequency domain imaging was used previously to measure [PpIX] in near-surface tumors under blue fluorescence excitation. Here, we extend this to subsurface [PpIX] fluorescence under red-light excitation. The decay rate of the modulation amplitude of the fluorescence signal was used to calculate the PpIX depth, which was then applied in a forward diffusion model to estimate [PpIX] at depth. For brain-like optical properties in phantoms with PpIX fluorescent inclusions, the depth can be recovered up to depths of 9.5 mm ± 0.4 mm, with [PpIX] ranging from 5 to 15 μg/mL within an average deviation of 15% from the true [PpIX] value.
随着 5-氨基酮戊酸诱导的原卟啉 IX（PpIX）荧光图像引导的引入，神经胶质瘤的完全切除率得到了提高。当荧光信号与从漫反射测量获得的固有组织光吸收和散射解耦时，手术效果进一步增强，从而获得绝对的 PpIX 浓度[PpIX]。先前曾使用空间频域成像在蓝光荧光激发下测量近表面肿瘤中的[PpIX]。在这里，我们将其扩展到红光激发下的亚表面[PpIX]荧光。荧光信号调制幅度的衰减率用于计算 PpIX 的深度，然后将其应用于正向扩散模型以估算深度处的[PpIX]。对于具有 PpIX 荧光内含物的类似脑组织的光学特性的体模，深度可以恢复到 9.5 毫米深度，并且[PpIX]在 5 到 15 微克/毫升之间，平均偏差为真实[PpIX]值的 15%。
