4D optical coherence tomography-based micro-angiography achieved by 1.6-MHz FDML swept source.

We demonstrate the use of an ultra-high-speed swept-source optical coherence tomography (OCT) to achieve optical micro-angiography (OMAG) of microcirculatory tissue beds in vivo. The system is based on a 1310-nm Fourier domain mode-locking (FDML) laser with 1.6-MHz A-line rate, providing a frame rate of 3.415 KHz, an axial resolution of ∼10  μm and signal to noise ratio of 102 dB. Motion from blood flow causes change in OCT signals between consecutive B-frames acquired at the same location. Intensity-based inter-frame subtraction algorithm is applied to extract blood flow from tissue background without any motion correction. We demonstrate the capability of this 1.6-MHz OCT system for 4D OMAG of in vivo tissue at a volume rate of 4.7 volumes/s (volume size: 512×200×720 voxels).