Application of Fluorescein Fluorescence in Vascular Neurosurgery

Abstract

Background: Fluorescein sodium (FNa) is a fluorescent drug with a long history of use for assessing retinal blood flow in ophthalmology; however, its application in vascular neurosurgery is only now gaining popularity. This review summarizes the current knowledge about using FNa videoangiography in vascular neurosurgery.Methods: We performed a literature review on the usage of FNa for fluorescent videoangiography procedures in neurosurgery. We analyzed methods of injection, dosages of FNa, visualizing platforms, and interpretation of FNa videoangiography. We also reviewed practical applications of FNa videoangiography during various vascular neurosurgeries.Results: FNa videoangiography can be performed with intraarterial (intracarotid) or intravenous dye injections. Both methods provide excellent resolution with enhanced fluorescence that shows intravascular blood flow on top of visible surrounding anatomy, and both allow simultaneous purposeful microsurgical manipulations. Although it is invasive, an intracarotid FNa injection results in faster contrast appearance and higher-intensity fluorescence and requires a lower dose per injection (reported range, 1–50 mg) compared with peripheral intravenous FNa injection (reported range, 75–2,000 mg or 1–1.5 mg/kg body weight). Four optical excitation/detection tools for FNa videoangiography have been successfully used: conventional xenon-light operating microscope with a special filter set, pencil-type light-emitting diode probe with a filter set, laser-illumination operating microscope, and an endoscope with a filter set. FNa videoangiography was reported to be feasible and useful in various clinical scenarios, such as examining the feeders and drainers in arteriovenous malformation surgery, checking the patency of a microvascular anastomosis, and assessing blood flow during aneurysm clipping. FNa videoangiography can be repeated during the same procedure and used along with indocyanine green (ICG) videoangiography.Conclusions: Compared with ICG videoangiography, FNa videoangiography has the advantages of enabling real-time inspection and better visualization at deep locations; however, thick vessel walls limit visualization of FNa in larger vessels. FNa videoangiography is a useful tool in multiple neurovascular scenarios and merits further studies to establish its clinical value.

In Vivo Visualization of the Pericardium Meridian with Fluorescent Dyes

“…The emitted photons from excited fluorescein at 500 nm range are prone to absorption and scattering by the skin and underlying tissues [ 32 , 35 ]. Fluorescein dye was not well delineated at greater depths [ 31 ] and may not, for this reason, have been visualized proximal to the elbows or at the forearm in some individuals where it likely traversed at deeper levels. The fact that the dye re-emerged at PC3 in many suggests that the migratory pathways have a shared pattern across individuals of accessing superficial loci.…”

“…To re-evaluate this tracer-dye phenomenon, we employed clinical-grade, fluorescent contrast agents—fluorescein sodium [ 31 ] and indocyanine green (ICG) [ 32 ]—at the pericardium channel on the forearms of healthy human volunteers. This study hypothesizes that fluorescent dyes will migrate along meridian pathways when injected at acupuncture points but not at adjacent controls.…”

Visualization of brain microvasculature and blood flow in vivo: Feasibility study using confocal laser endomicroscopy

“…Furthermore, intraoperative fluorescence angiography is used to assess the blood flow state in vascular territories during bypass procedures 35,36 . Interestingly, fluorescein‐based wide‐field angiography can provide better resolution of small perforating vessels as well as afford real‐time visualization as an adjunct to ICG video angiography 37,38 …”

“…35,36 Interestingly, fluorescein-based wide-field angiography can provide better resolution of small perforating vessels as well as afford realtime visualization as an adjunct to ICG video angiography. 37,38 Further interrogation of the microvasculature and blood flow during fluorescence angiographies with fluorescein using CLE pres- vascular area, including microvasculature and capillaries". 39 The clinical benefits of this new intraoperative imaging modality would seem to be advantageous and merit investigation.…”

Potato Starch Edible Films as Environmentally Friendly Carriers for Model Drug: In vitro Release Study

“…Fluorescein dye was used as a model drug to investigate the release characteristics from the both methods. Fluorescein dye was chosen in this study due to its photosensitivity and its application as drug with a long history of usage for evaluating retinal blood flow in ophthalmology [22].…”