University of Toronto, Department of Medical Biophysics, Faculty of Medicine, Ontario, CanadabUniversity Health Network, Princess Margaret Cancer Center, Ontario, Canada.
University Health Network, Princess Margaret Cancer Center, Ontario, Canada.
J Biomed Opt. 2017 Jul 1;22(7):76007. doi: 10.1117/1.JBO.22.7.076007.
5-Aminolevelunic acid-induced protoporphyrin IX (PpIX) fluorescence-guided resection (FGR) enables maximum safe resection of glioma by providing real-time tumor contrast. However, the subjective visual assessment and the variable intrinsic optical attenuation of tissue limit this technique to reliably delineating only high-grade tumors that display strong fluorescence. We have previously shown, using a fiber-optic probe, that quantitative assessment using noninvasive point spectroscopic measurements of the absolute PpIX concentration in tissue further improves the accuracy of FGR, extending it to surgically curable low-grade glioma. More recently, we have shown that implementing spatial frequency domain imaging with a fluorescent-light transport model enables recovery of two-dimensional images of [PpIX], alleviating the need for time-consuming point sampling of the brain surface. We present first results of this technique modified for <italic<in vivo</italic< imaging on an RG2 rat brain tumor model. Despite the moderate errors in retrieving the absorption and reduced scattering coefficients in the subdiffusive regime of 14% and 19%, respectively, the recovered [PpIX] maps agree within 10% of the point [PpIX] values measured by the fiber-optic probe, validating its potential as an extension or an alternative to point sampling during glioma resection.
5-氨基酮戊酸诱导的原卟啉 IX（PpIX）荧光引导切除（FGR）通过提供实时肿瘤对比，使胶质瘤的最大安全切除成为可能。然而，由于主观的视觉评估和组织的固有光学衰减的变化，这种技术只能可靠地描绘出显示强荧光的高级别肿瘤。我们之前已经使用光纤探头表明，通过对组织中绝对 PpIX 浓度进行非侵入性点光谱测量进行定量评估，进一步提高了 FGR 的准确性，使其能够扩展到可手术治愈的低级别胶质瘤。最近，我们已经表明，使用荧光光传输模型实现空间频域成像可以恢复 [PpIX] 的二维图像，从而减轻了对大脑表面进行耗时的点采样的需求。我们展示了对 RG2 大鼠脑肿瘤模型进行<italic<体内</italic<成像的这项技术的初步结果。尽管在 14%和 19%的亚扩散范围内分别恢复吸收和散射系数的误差适中，但恢复的 [PpIX] 图谱与光纤探头测量的点 [PpIX] 值的差异在 10%以内，验证了它作为胶质瘤切除过程中替代或补充点采样的潜力。
