5-ALA fluorescence and laser Doppler flowmetry for guidance in a stereotactic brain tumor biopsy

Abstract

A fiber optic probe was developed for guidance during stereotactic brain biopsy procedures to target tumor tissue and reduce the risk of hemorrhage. The probe was connected to a setup for the measurement of 5-aminolevulinic acid (5-ALA) induced fluorescence and microvascular blood flow. Along three stereotactic trajectories, fluorescence (n = 109) and laser Doppler flowmetry (LDF) (n = 144) measurements were done in millimeter increments. The recorded signals were compared to histopathology and radiology images. The median ratio of protoporphyrin IX (PpIX) fluorescence and autofluorescence (AF) in the tumor was considerably higher than the marginal zone (17.3 vs 0.9). The blood flow showed two high spots (3%) in total. The proposed setup allows simultaneous and realtime detection of tumor tissue and microvascular blood flow for tracking the vessels.

Spectral complexity of 5-ALA induced PpIX fluorescence in guided surgery: a clinical study towards the discrimination of healthy tissue and margin boundaries in high and low grade gliomas

“…This technique is the actual clinical standard for PpIX-based surgical assistance. It is also investigated for intracranial stereotactic biopsies [19,20]. However, its sensitivity is still limited when applied to low density infiltrative parts of HGG [21,22] or to LGG [23].…”

“…It has also been used in LGG but its sensitivity is yet only up to 45% [29]. Some works proposed normalization procedures or other qualitative or semiquantitative biomarkers to increase the robustness of PpIX fluorescence measurement [19,[30][31][32]. It should be pointed out that both approaches are relevant because all these measurements are intermediary steps toward the final aim of PpIX fluorescence measurements, which is the classification of measurements into relevant pathological status.…”

Intraoperative detection of blood vessels with an imaging needle during neurosurgery in humans

“…Our approach of miniaturizing the imaging probe and encasing it within the needle offers an alternative solution to the issue of limited penetration depth in high-resolution optical techniques, placing the imaging probe at the point of tissue sampling. A similar approach has been demonstrated using a miniaturized, forward-facing laser Doppler flowmetry probe, both in deep brain stimulation ( 27 – 29 ) and brain biopsy interventions ( 30 ). However, our design is the first to combine the optical probe into the biopsy needle, integrating it into the clinical workflow and avoiding the need for additional needle insertions.…”

Rise of Raman spectroscopy in neurosurgery: a review

“…18 Other optical technologies that have investigated blood vessel detection in neurosurgery are LDF and DRS; however, the ability to measure blood vessel size using OCT is a significant advantage for risk assessment. 12,71,72 To minimize the number of optical probes used during a single procedure, it would be ideal to have a probe capable of both blood vessel detection during needle descent and tumor margin detection. Such a probe could be either Raman or OCT, or size permitting, a multimodal combination.…”