For research use only. Not for use in diagnostic procedures.
In vivo Imaging out in the open. Solaris™ open-air fluorescence imaging system is a,high impact research tool that enables translational,in vivo preclinical imaging. Solaris is a multispecies,imaging system designed for use with a broad,spectral range of fluorescent probes enabling versatility in imaging,application development and surgical research.
palpate the tumor and tumor margins. Small tumor nodules can be missed or tumor margins may be inadequately removed, resulting in the need for secondary treatment. Intraoperative fluorescence imaging can help improve the initial resection and, therefore, both improve outcomes and reduce cost. Unconjugated fluorescent dyes have been previously used for this type of study to identify tumors in first-in-human studies. However, dyes conjugated to a targeting moiety have better specificity for the tumor itself and provide better guidance for the surgeon to locate the tumor and remove margins.,The new SolarisTM imaging system is an open air fluorescence imaging instrument designed specifically for intraoperative imaging in small to large animals. The system supports 4 different fluorescence channels to image common dyes (e.g. indocyanine green [ICG] and Fluorescein isothiocyanate [FITC]) and more unique near-infrared (NIR) fluorescent dyes. All of these can be imaged in ambient light to achieve sensitivities of 10 nM for single, long exposures and 10-100 nM for videos. The imaging head is attached to an adjustable arm so that it be can be positioned 75 cm above the object plane, far enough to be considered outside of the sterile field. The imaging head also has two cameras for simultaneous fluorescence and bright field (color) imaging; these images can be overlaid in the software. Single, long exposure images acquired from 2 different wavelengths can be overlaid to enable multiplexing and improve tumor identification; previously published studies have shown this to be useful for sentinel lymph node detection. For FITC, a custom liquid crystal tunable filter (LCTF) is included in the system in tandem with spectral unmixing software to separate tissue autofluorescence from fluorescence emitted by the dye.,Although this system is designed for larger animals, proof of concept intraoperative tumor resection has been performed in rodents. Subcutaneous tumors have been resected while imaging rats injected with the targeted agent IntegriSense™ 680. During the surgical procedures, both the residual tumor bed (in vivo) and the resected tumors (ex vivo) can be imaged to confirm complete resection in an ambient light environment. To investigate a more challenging model, tumor cell lines have also been implanted intraperitoneally in rats. After injection with either the targeted agent BombesinRSense™ 680 and the activatable agent ProSense® 750, deep tissue tumors were readily identified during a comprehensive necropsy. Although there are depth limitations due to the absorption and scattering of light in tissue, some tumors are still visible non-invasively. These results suggest that intraoperative resection of tumors detected with both targeted and activatable fluorescent agents is feasible using the new Solaris imaging system.
Intraoperative tumor resection relies on the ability of the surgeon to discriminate tumor from healthy tissue, either visually or by palpation. Small tumor nodules can be missed or tumor margins may be inadequately removed, resulting in the need for secondary treatment. Intraoperative fluorescence imaging can help improve the initial resection, both improving outcomes and reducing cost. First-in-human studies have examined this theorem using unconjugated fluorescent dyes. However, dyes conjugated to a targeting moiety have superior specificity for the tumor itself and provide enhanced guidance for the surgeon to locate the tumor and determine the margin of resection.,The new Solaris system was recently introduced specifically for intraoperative imaging in research environments. The system supports 4 different fluorescence channels to image common dyes (e.g. indocyanine green [ICG] and Fluorescein isothiocyanate [FITC]) and more unique functionalized targeted or activated near-infrared (NIR) fluorescent agents in an ambient light environment. Recent data illustrate sensitivities of 10 nM for static snapshots and 10-100 nM for real-time acquisition at video frame rates, all under ambient lighting conditions. To achieve increased sensitivity focused fluorescence images are required, therefore an algorithmic autofocus approach has been implemented to find the ideal focal plane. Additionally, snapshots acquired at different wavelengths can be overlaid to enable multiplexing and improve tumor identification; previously published studies have shown this to be useful for sentinel lymph node mapping. For FITC, where the emission spectra overlaps with tissue autofluorescence, spectral unmixing software has been used to process narrow band images acquired through a liquid crystal tunable filter (LCTF).,Although this system is designed for translational research in larger animals, proof of concept intraoperative tumor resection has been performed in rodents. Dosing and timing effects for epi-fluorescence images of subcutaneous and intraoperative surgical imaging has been investigated with both targeted and activatable agents. Subcutaneous tumors have been resected with the aid of intraoperative imaging in animals injected with IntegriSense 680. Tumor cell lines have also been implanted intrasplenically in rats; the subsequent deep tissue tumors were identified intraoperatively and removed after injection with either BombesinRSense 680 or ProSense 750. Lymphatic draining, a common problem in tumor metastasis, was also investigated in mice using AngioSense 680. These results suggest that intraoperative resection of tumors identified with both targeted and activatable fluorescent agents is feasible using the new Solaris imaging system.
In vivo studies have traditionally been limited to rodents due to the limitations of light penetration in tissue and have also utilized enclosed instruments to reduce background signals. There has been interest in extending fluorescent angiography into the clinic using naked fluorescent dyes (e.g. indocyanine green [ICG], FITC, methylene blue) although the depth limitations sometimes require X-ray angiography techniques. Clinical utilization of fluorescence guided surgery, on the other hand, has tremendous potential and can leverage targeted fluorescent probes that are much more specific. These probes are becoming increasingly relevant in translational studies as characterization advances and the mechanisms of action become better understood. In fact, some early first-in-human studies using naked fluorescent dyes and/or targeted agents for image guided surgery show potential. Utilization has not been widespread, due in part to the lack of instrumentation for preclinical imaging. Some recent handheld systems are available but preclude simultaneous imaging and resection of tumors. Surgical microscopes have longer working distances but are less natural to use. Other open-field commercial systems have working distances of less than 25 cm, limiting an operator’s visibility of the surgical field while imaging. We have previously reported on a system suitable for translational imaging that used pulsed illumination to interweave white and fluorescent lighting. White light pulsing reduces the illumination brightness and therefore makes utilization more challenging. In this paper we report on a system using filtered white light illumination to remove leakage into the fluorescence image and detect (and overlay) color and monochrome fluorescence images using the latest generation of sCMOS cameras. A distributed arrangement of low power LEDs can generate as much white illumination as a surgical lamp and also have good shadow control. Fluorescent excitation light in visible wavelengths can be pulsed at rates fast enough to appear continuous to the naked eye. To improve sensitivity in the band corresponding to FITC emission (500-600nm), long exposure snapshots can be used to acquire multispectral data using a customized liquid crystal tunable filter (LCTF) and unmix autofluorescence from the fluorophore signal. As a proof of concept, we use intrasplenic mouse models injected with targeted fluorescent agents and resect the tumors during the imaging procedure.