In this paper, we present a zero-padding technique and cross-correlation technique based correlation mapping optical coherence tomography (ZPCC-cmOCT) to reconstruct microcirculation maps of human skin in vivo, which can remove the background decorrelation noise caused by motion artifacts.
In conventional correlation mapping optical coherence tomography (cmOCT) method, two adjacent B-scans of intensity-based structure signal are correlated to isolate blood flow signals from static tissue background. The correlation coefficients range from Symbol, where 0 indicates low correlation degree and ±1 indicate high correlation degree. However, the correlation degree of static tissue may be lowered by the motion artifacts due to cardiac and respiratory motion, resulting in background decorrelation noise in microcirculation maps.
In the proposed method, zero-padded interference fringes are first transformed to generate structural images in which the distance sensitivity in axial direction is increased, and then the local areas in two adjacent structural images are aligned by cross-correlation based image registration, after that blood flow information can be extracted by cmOCT method. In addition, the advantage of the zero-padding technique is that the accuracy of the image registration can be improved.
Both phantom experiments and in vivo experiments were implemented to test the noise rejection performance of the proposed method. In phantom experiments, one side of the sample is put on one finger of a volunteer so that the motion artifacts can be caused during imaging. In in vivo experiments, both a B-scan of blood vessel maps and en face MIP view images obtained by both methods are provided to make comparisons. All results demonstrate that the proposed method is capable of offering microcirculation maps with the background decorrelation noise caused by motion artifacts removed.