Pulsed-light imaging for fluorescence guided surgery under normal room lighting

Abstract

Fluorescence guided surgery (FGS) is an emerging technology that has demonstrated improved surgical outcomes. However, dim lighting conditions required bycurrent FGS systems are disruptive to standard surgical workflow. We present a novel FGS system capable of imaging fluorescence under normal room lightby using pulsed excitation and gated acquisition. Images from tissue-simulating phantoms confirm visual detection down to 0.25 μM of protopor-phyrin IX under 125 μW/cm2 of ambient light, more than an order of magnitude lower than that measured with the Zeiss Pentero in the dark. Resection of orthotopic brain tumors in mice also suggests that the pulsed-light system provides superior sensitivity in vivo.

Optimization of fluorescent imaging in the operating room through pulsed acquisition and gating to ambient background cycling

“…1. The bulk of the technical details of this system are described in a previous publication, and so only a brief description including updates to the system will be provided here [19]. The system is composed of two separate imaging channels, a 700 nm channel capable of imaging both PpIX and IRDye 680RD as well as an 800 nm channel capable of imaging IRDye 800CW.…”

“…A pulsed imaging system was previously developed [19] to image fluorescence in fast snap shots, enabling real time background subtraction as well the maximization of fluorescence to background signal. The idea was to enable fluorescence imaging under normal surgical background lighting even when utilizing visible light fluorescence or imaging extremely low fluorophore concentrations.…”

“…The additional benefit of the design is that the intensified CCD captures signals with an amplified gain of several orders of magnitude, thereby maximizing the fluorophore sensitivity even at these low integration times. This system was used in an earlier study where it was shown this method of pulsed light imaging was able to reduce the background light contribution to the recorded signal and enable PpIX fluorescence imaging under normal ambient light (~35 µW/cm 2 provided by a series of Sylvania Octron XP 17W 3500K fluorescent overhead room lights) [19].…”

Non-invasive fluorescence imaging under ambient light conditions using a modulated ICCD and laser diode

“…where T P and B P represent the mean intensify from the target and background ROIs, respectively, and the SNR in decibels (dB) was calculated as: 10 20 log…”

“…Current CCD camera based fluorescence imaging systems for intraoperative image-guided tumor detection [4][5][6][7][8][9] employ continuous wave (CW) image acquisition due to its low cost and simple implementation. Recently, a fluorescence-guided system which used pulsed excitation and gated microsecond acquisition to reject ambient light through the subtraction of intensity measurements made in the absence and presence of excitation illumination termed time-domain (TD) approach demonstrated improved performance [10]. While approaches based used upon RF modulated excitation light (termed frequency-domain (FD) approaches) have been proposed and used in small animal tomography studies [11], they can also be operated in a non-light-tight environments because the AC amplitude of the detected fluorescence is insensitive to changing ambient light conditions [12].…”