Feature Of The Week 4/5/09: In-vivo Optical Coherence Tomography from a Hand-Held Probe
Feature of the week 4/5/09: Many OCT systems, particularly microscopy systems, have fixed probe modules where samples are brought to the OCT system. Several papers have been published on hand-held probes which instead bring the OCT system to the sample. Applications such as cardiology and endoscopy have long brought the light to the sample, but the engineering challenges of hand-held microscopy, ophthalmology, or NDE application are quite different. Several factors enable hand-held probes including: fiber-optic systems decouple the OCT engine from the probe; speed capabilities of Fourier domain detection minimize motion induced artifacts; and improvements in miniature scanning technology allow for small light-weight probes. Both Bioptigen and Michelson Diagnostics have announced commercially available hand-held probes. Michelson Diagnostics' new ‘Vivosight’ probe (Slide 2) uses multiple beams focused at different tissue depths to produce a composite OCT image twice the lateral resolution possible with conventional single-beam OCT systems over the same imaging depth (Slide 3). The image set shown here is of healthy skin tissue: Slide 5) B-scan of skin at knuckle joint, with clearly visible stratus corneum, dermal/epidermal junction, and papillary dermis with capillaries visible. The tops of large blood vessels in the subcutaneous layer are just visible. Slide 6) 3D rendering of a 5 mm x 5 mm region of skin at the base of the wrist. The topographic detail shows fine wrinkle structure. Slide 7) Video sequence of a superficial hemangioma (strawberry mark), captured at about 20 fps. The ‘twinkling’ areas are assumed to be blood flow. Slide 8) A 3D rendering of a small region of the upper lip. The animated cutaway reveals a hair follicle, recently shaved, embedded at a shallow angle below the skin. Slide 9) A 3D rendering of a raised mole. The animated cutaway reveals sub-surface clinical details.