Real-time reference A-line subtraction and saturation artifact removal using graphics processing unit for high-frame-rate Fourier-domain optical coherence tomography video imaging

Variations in the spectral shape and the amplitude of the optical coherence tomography (OCT) signal and reference cause fixed-pattern noise and light reflected from a highly specular surface might cause saturation artifacts. In real-time video-rate OCT imaging, these effects make the OCT video image appear unstable and difficult to view. To eliminate these problems, we implemented real-time reference A-line subtraction and saturation detection and correction on standard Fourier-domain optical coherence tomography (FD-OCT) video imaging frame-by-frame. This real-time OCT data processing method eliminates the need for the physical reference measurement procedure and automatically detects and corrects saturated A-scans if there is any within one frame. This technique is also robust to the reference and signal amplitude variations, and provides higher signal-to-noise ratio compared to the normal fixed-reference subtraction method. To implement an effective interventional OCT imaging system, the technique was integrated along with other graphics processing unit-based OCT processing techniques [resampling, dispersion compensation, fast Fourier transform, log-scaling, and soft-thresholding]. The real-time fixed-pattern artifact-free FD-OCT imaging was achieved at 70 frames/s for a frame size of 1000 (lateral) by 1024 (axial) pixels. The theoretical maximum processing and rendering rate was measured to be 266,000 A-scans/s.