title: Deep-tissue access with confocal fluorescence microendoscopy through hypodermic needles.
abstract: We report on the design and implementation of a gradient-index microendoscope suitable for accessing tissues deep within the body using confocal fluorescence imaging. The 350-μm diameter microendoscope has a length of 27 mm, which enables it to be inserted through a 22-gauge hypodermic needle. A prototype imaging system is demonstrated to obtain images of tissue samples at depths of ~15 mm with a lateral resolution of ~700 nm. To the best of our knowledge, this is the highest resolution and imaging depth reported for a confocal probe of these dimensions. We employ a scanning arrangement using a lensed fiber that can conveniently control the input beam parameters without causing off-axis aberrations typically present in the optical relay lenses used in galvanometer-mirror scanning systems.
authors.affiliation: Optical + Biomedical Engineering Laboratory, School of Electrical, Electronics and Computer Engineering, The University of Western Australia, 35 Stirling Highway, Crawley 6009 WA, Australia.
authors.forename: Rajesh S
authors.initials: RS
authors.lastname: Pillai
authors.forename: Dirk
authors.initials: D
authors.lastname: Lorenser
authors.forename: David D
authors.initials: DD
authors.lastname: Sampson
mesh_terms: D000818:Animals; D002417:Cattle; D004724:Endoscopy / Q000379:methods*; D004867:Equipment Design; D007091:Image Processing, Computer-Assisted; D018613:Microscopy, Confocal / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000379:methods; D015233:Models, Statistical; D009339:Needles; D016011:Normal Distribution; D055100:Optical Fibers; D055095:Optics and Photonics