Catheter-based in Vivo Imaging of Enzyme Activity and Gene Expression: Feasibility Study in Mice

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Abstract
PURPOSE: To construct and evaluate an interventional catheter-based imaging system for intravital monitoring of molecularly sensitive near-infrared fluorescent probes and optical marker genes. MATERIALS AND METHODS: An imaging device that was based on a miniaturized fiberoptic sensor (MIFS) was built in which images created with a 2.7-F fiberoptic catheter were relayed through a dichroic mirror, through a bandpass filter, and on two independent cameras. This system permitted simultaneous recording of white-light and fluorescent images. Spatial resolution, spectral transmissions, and sensitivity were determined in vitro. In vivo testing was performed in nude mice bearing intraperitoneal tumors that express green fluorescent protein and in a mouse model of ovarian carcinoma with enzyme-activatable near-infrared probes sensitive to tumoral protease activity. Signal intensity on images of tumors and that on images of normal tissue were measured and compared with t test. RESULTS: The catheter, which was advanc...