Cycloid scanning for wide field optical coherence tomography endomicroscopy and angiography in vivo

Devices that perform wide field of view optical scanning are important for the endoscopic in situ assessment and diagnosis of luminal organ disease such as in the gastrointestinal tract. Optical scanning for imaging of organ lumens in vivo has traditionally relied on one or more mechanical actuations at the proximal end of the catheter device, limiting scan accuracy and imaging speed. There is an unmet need for rapid and precise 2-dimensional (2-D) micro-scanning technologies that could enable the translation of benchtop scanning microscopies to in vivo endoscopic imaging. We demonstrate high speed, side-viewing endomicroscopy in vivo, using a new cycloid scanning optical coherence tomography (OCT) tethered capsule. The cycloid capsule incorporates a piezoelectrically actuated resonant fiber scanner to perform a precision, small field of view, fast scan and a micromotor scanner to generate a wide field of view, slow scan, which together distally scan the beam in a 2-D cycloid pattern, generating an unwrapped ~38 mm2 strip field-of-view (FOV). Using ultrahigh speed swept-source OCT at 1.17 MHz axial scan rate, imaging of the human rectum was performed at 3 volumes/sec. Multiple continuously acquired volumes were mosaicked to generate a larger FOV. We further demonstrate OCT angiography at 0.5 volumes/sec, producing volumetric images of vasculature without contrast agents. Cycloid micro-scanning technology promises to enable 2-D beam scanning for endoscopic side viewing using not only OCT but other scanning modalities