Imaging solid tissues with an OCT imaging needle

Optical coherence tomography (OCT) is an emerging technology capable of imaging tissue architectural morphology at micron scale resolution . OCT was first developed to image the relatively transparent suctures in the eye 2,3 and later applied extensively in highly scattering tissues for moiphologic and functional imaging with unprecedented resolution 48 Real-time, in vivo imaging and ultrahigh (1 tm) resolution imaging have also been demonstrated. A variety of applications of OCT imaging have been made possible by designing novel OCT delivery/collection probes. Examples include a forward imaging hand-held probe for assessing tissue during open field surgery 11,12 and a transverse scanning OCT endoscope/catheter for imaging hollow organs such as the gastrointestinal tract and cardiovascular system 1318 oT applications have been limited to the surfaces or lumina of organ systems because the penetration depth of OCT is 2-3 mm and also because high transverse resolution is only achievable within a short confocal length. To date, it has not been possible to image structures inside solid tissues or organs. However, there are many clinical scenarios where high resolution internal imaging of solid tissues is required. One such application of OCT is to image pathology and guide biopsy in solid tissues. Other applications include optical imaging where excisional biopsy is hazardous, and surgical guidance such as in cryosurgery or interstitial photodvnmic therapy.