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Spectrally encoded confocal microscopy (SECM) is a novel approach for obtaining high resolution, depth-sectioned images of microstructure within turbid samples. By encoding one spatial dimension in wavelength, imaging probes can be greatly simplified compared to standard scanning confocal microscopes, potentially enabling endoscopic implementation. The use of a diffraction grating for spectral encoding, however, skews the optical axis through the probe, thus complicating the design of narrow diameter instruments. In this Letter, we describe a novel use of a single-optical-axis element based on high index-of-refraction prisms and a transmission holographic grating for the design of narrow diameter SECM devices. Confocal images obtained with a 10.0 mm probe demonstrate a transverse resolution of 1.1 microm and a field of view of 650 microm.

Background: Optical coherence tomography (OCT) is a high-resolution imaging technique that produces cross-sectional images in vivo. This is a report of the first use of OCT to acquire images of the biliary tree during ERCP., Methods: A 2.6-mm diameter OCT catheter delivered through the accessory channel of a duodenoscope was used to acquire images of the intrahepatic and extrahepatic bile ducts in 5 patients. Histology-correlated OCT images of 5 cadaveric livers, each imaged at 3 sites, were used to guide interpretation of the in vivo images., Results: Biliary ductal epithelium and subepithelial structures, including peribiliary glands, vasculature, and hepatic parenchyma, were visualized in vivo. The papillary architecture of cholangiocarcinoma was identified by OCT. There were no OCT-related complications., Conclusions: High-resolution OCT imaging of the biliary tree is feasible and may provide useful diagnostic information during ERCP.