Improved Protoporphyrin IX-Guided Neurosurgical Tumor Detection with Frequency-Domain Fluorescence Lifetime Imaging

Abstract

Precise intraoperative brain tumor visualization supports surgeons in achieving maximal safe resection. In this sense, improved prognosis in patients with high-grade gliomas undergoing protoporphyrin IX fluorescence-guided surgery has been demonstrated. Phase fluorescence lifetime imaging in the frequency-domain has shown promise to distinguish weak protoporphyrin IX fluorescence from competing endogenous tissue fluorophores, thus allowing for brain tumor detection with high sensitivity. In this work, we show that this technique can be further improved by minimizing the crosstalk of autofluorescence signal contributions when only detecting the fluorescence emission above 615 nm. Combining fluorescence lifetime and spectroscopic measurements on a set of 130 ex vivo brain tumor specimens (14 low- and 56 high-grade gliomas, 39 meningiomas and 21 metastases) coherently substantiated the resulting increase of the fluorescence lifetime with respect to the detection band employed in previous work. This is of major interest for obtaining a clear-cut distinction from the autofluorescence background of the physiological brain. In particular, the median fluorescence lifetime of low- and high-grade glioma specimens lacking visual fluorescence during surgical resection was increased from 4.7 ns to 5.4 ns and 2.9 ns to 3.3 ns, respectively. While more data are needed to create statistical evidence, the coherence of what was observed throughout all tumor groups emphasized that this optimization should be taken into account for future studies.

Imaging the rotational mobility of carbon dot-gold nanoparticle conjugates using frequency domain wide-field time-resolved fluorescence anisotropy

“… 31 Nonetheless, there are a variety of works that signify the use of FD measurements for the resolution of fluorescence intensity (FI) and FA decays thus probing cell behavior and monitoring changes in its microenvironment. 16 , 32 – 37 Furthermore, the measurement procedures and the data analysis in the FD method are significantly faster, and hence more suitable for clinical applications. 38 In both FD apparatuses, 27 , 31 the images at different polarizations are acquired using two sets of measurements.…”

Computational macroscopic lifetime imaging and concentration unmixing of autofluorescence

“…Of note, the fluorescence lifetime of naturally occurring substances in tissues, or autofluorescence, has been shown to be a promising tool for label-free diagnostic and classification of tissues for over three decades [2]. Currently the main implementations of autofluorescence lifetime imaging are performed using well-established microscopic techniques [3,4] but the use of macroscopic lifetime imaging and quantification is key in numerous clinical applications, including Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) [5][6][7] fundus autofluorescence imaging, characterization of skin lesions [8], assessment of carotid arteries and their composition [9] and fluorescence guided surgery of brain tumors [10][11][12]. These implementations must appropriately tackle both the inherent challenges of autofluorescence lifetime imaging while imaging large field of views (FOV) with high sensitivity.…”

Deep‐learning FRET visualization in flow cytometry: At the cross road of the signaling and FRET pathways

“…The ultimate aim of basic research in molecular biology and medicine is the application of the results in diagnostics and therapies, the "translation" of the achievements of basic science to the every-day or "real life" level. Examples are the application of fluorescence polarization in cancer diagnostics [2,3], and fluorescence lifetime for detecting various physiological parameters in the human bodies, for example, when delineating tumor boundaries during surgical intervention [4]. Huge data sets might arise here not only due to the high number of monitored parameters, but also due to the size of the monitored (scanned) areas of body surfaces.…”