Enhancing surgical vision by using real-time imaging of α_vβ₃-integrin targeted near-infrared fluorescent agent

Background: This study was designed to improve the surgical procedure and outcome of cancer surgery by means of real-time molecular imaging feedback of tumor spread and margin delineation using targeted near-infrared fluorescent probes with specificity to tumor biomarkers. Surgical excision of cancer often is confronted with difficulties in the identification of cancer spread and the accurate delineation of tumor margins. Currently, the assessment of tumor borders is afforded by postoperative pathology or, less reliably, intraoperative frozen sectioning. Fluorescence imaging is a natural modality for intraoperative use by directly relating to the surgeon's vision and offers highly attractive characteristics, such as high-resolution, sensitivity, and portability. Via the use of targeted probes it also becomes highly tumor-specific and can lead to significant improvements in surgical procedures and outcome. Methods: Mice bearing xenograft human tumors were injected with α_vβ₃-integrin receptor-targeted fluorescent probe and in vivo visualized by using a novel, real-time, multispectral fluorescence imaging system. Confirmatory ex vivo imaging, bioluminescence imaging, and histopathology were used to validate the in vivo findings. Results: Fluorescence images were all in good correspondence with the confirming bioluminescence images in respect to signal colocalization. Fluorescence imaging detected all tumors and successfully guided total tumor excision by effectively detecting small tumor residuals, which occasionally were missed by the surgeon. Tumor tissue exhibited target-to-background ratio of ∼4.0, which was significantly higher compared with white-light images representing the visual contrast. Histopathology confirmed the capability of the method to identify tumor negative margins with high specificity and better prediction rate compared with visual inspection. Conclusions: Real-time multispectral fluorescence imaging using tumor specific molecular probes is a promising modality for tumor excision by offering real time feedback to the surgeon in the operating room.