Optical coherence tomography. Optical coherence tomography (OCT) permits cross-sectional imaging of articular cartilage at resolutions comparable with low-power histology. (a) Arthroscopically firm and surface-intact cartilage shows OCT form birefringence. (b) Loss of birefringent banding on OCT correlates to softened cartilage. (c) Subsurface voids and fissures can be visualized with OCT.