Wide-field near-infrared fluorescence endoscope for real-time in vivo imaging

摘要

A diode-pumped solid state laser is used to deliver excitation at λ_(ex)= 671 nm. The beam is expanded by a pair of relay lenses (f_1 = 30 and f_2 = 50 mm) to 3 mm diameter, filling the aperture of a fluid light cable that is coupled to a Hopkins~® II rigid endoscope. Near-infrared fluorescence images are collected by the endoscope and transmitted by another set of relay lenses onto a CCD detector that has dimensions of 8.7×6.9 mm~2 (1388×1040 pixels). A zoom lens system (F#1.6-16 aperture) with a tunable focal length (20-100 mm) magnifies the image to fill the dimensions of the CCD. A band pass filter allows fluorescence with spectral range λ_(em) = 696 to 736 nm to be collected. The system achieves a resolution of 9.8 μm and field-of-view of 3.6 mm at a distance of 2.5 mm between the distal end of the endoscope and the tissue. Images are collected at a rate of 10 frames per second. A filter wheel is incorporated into the handle of the instrument housing to rapidly switch between reflectance and fluorescence images. Cy5.5-labeled peptides were delivered through the 1 mm diameter instrument channel in the endoscope. Near-infrared fluorescence images demonstrated specific peptide binding to spontaneous adenomas that developed beginning at 2 months of age in a genetically-engineered mouse with mutation of one allele in the APC gene. This integrated methodology represents a powerful tool that can achieve real time detection of disease in the colon and other hollow organs.