Handheld optical coherence tomography scanner for primary care diagnostics

Abstract

The goal of this study is to develop an advanced point-of-care diagnostic instrument for use in a primary care office using handheld optical coherence tomography (OCT). This system has the potential to enable earlier detection of diseases and accurate image-based diagnostics. Our system was designed to be compact, portable, user-friendly, and fast, making it well suited for the primary care office setting. The unique feature of our system is a versatile handheld OCT imaging scanner which consists of a pair of computer-controlled galvanometer-mounted mirrors, interchangeable lens mounts, and miniaturized video camera. This handheld scanner has the capability to guide the physician in real time for finding suspicious regions to be imaged by OCT. In order to evaluate the performance and use of the handheld OCT scanner, the anterior chamber of a rat eye and in vivo human retina, cornea, skin, and tympanic membrane were imaged. Based on this feasibility study, we believe that this new type of handheld OCT device and system has the potential to be an efficient point-of-care imaging tool in primary care medicine.

Fig. 1

Schematic and photograph of the cart-based SD-OCT system and handheld scanner. The optical setup, including the spectrometer and reference optical path, is contained within a small portable medical cart. The handheld scanner has a 2 m-long connecting cable with optical fiber and electrical wires, so that the physician can readily access multiple tissue sites on the patient. Abbreviations: DG, diffraction grating; PC, polarization controller; DC, dispersion compensation materials; NDF, neutral density filter.

Fig. 2

(a) Photographs of handheld OCT scanner and lens mounts. All lens mounts were packaged in threaded lens tubes for convenient interchange. (b) Photograph of OCT imaging procedure. Physician positions handheld scanner on tissue, orients to the desired imaging location, and clicks a save button mounted on the scanner handle while monitoring both video and OCT images. (c) Schematic of optical paths for the OCT and LED beams in the lens mount. Two red LEDs are permanently mounted in the handheld scanner for video imaging. The lens in the interchangeable tube guides and focuses the OCT beam as well as the LED beams to scan and uniformly illuminate the tissue.

Fig. 3

In vitro 3-D OCT images of a rat eye (a) and in vivo OCT and video images acquired from normal human tissue (b–i). (a) Reconstructed 3-D OCT images of anterior chamber of a rat eye at angled view (left) and a top view (right), (b) fingernail plate and fold, (c) uvula, (d) oral mucosa along gumline, (e) skin on arm, (f) cornea, (g) tympanic membrane in ear, (h) foveal region of retina, and (i) optic nerve head. Abbreviations: NFL, nerve fiber layer; GCL, ganglion cell layer; INL, inner nuclear layer; ONL, outer nuclear layer; ELM, external limiting membrane; IS/OS, junction between the inner and outer segment of the photoreceptors; RPE, retinal pigment epithelium.