Abstract
In this paper, a multi-beam scanning technique is proposed to optimize the microvascular images of human skin obtained with Doppler effect based methods and speckle variance processing. Flow phantom experiments were performed to investigate the suitability for combining multi-beam data to achieve enhanced microvascular imaging. To our surprise, the highly variable spot sizes (ranging from 13 to 77 μm) encountered in high numerical aperture multi-beam OCT system imaging the same target provided reasonably uniform Doppler variance and speckle variance responses as functions of flow velocity, which formed the basis for combining them to obtain better microvascular imaging without scanning penalty. In vivo 2D and 3D imaging of human skin was then performed to further demonstrate the benefit of combining multi-beam scanning to obtain improved signal-to-noise ratio (SNR) in microvascular imaging. Such SNR improvement can be as high as 10 dB. To our knowledge, this is the first demonstration of combining different spot size, staggered multiple optical foci scanning, to achieve enhanced SNR for blood flow OCT imaging.
Highlights
Optical coherence tomography (OCT) [1] as an emerging medical imaging modality is well suited for non-invasive in vivo applications with high imaging speed and near histological resolution
We experimentally investigate the dependence of Doppler and speckle variance OCT imaging with different beam spot sizes occurring along the optical axis away from the focal spot
After establishing the relative independence to spot size changes, we demonstrate the potential of utilizing the multiple optical beams to provide better microvascular imaging of normal human skin and non-melanoma skin cancer in vivo
Summary
Optical coherence tomography (OCT) [1] as an emerging medical imaging modality is well suited for non-invasive in vivo applications with high imaging speed and near histological resolution. Multi-channel or multi-beam OCT techniques [32, 33] were proposed previously to resolve conflicting requirements of high numerical aperture and optimal light source power utilization In these setups, the multiple optical beams did not have a mutual focal point, and each beam had an optimal structural OCT imaging range near its focal zone with tight beam waist and four or more beams’ data were stitched together to provide the final structural OCT image. When the focal points were staggered in the depth direction, any blood vessel within the imaging volume would be scanned across by multiple beams regardless of whether it was within the optimal focal zone This effect provided an interesting opportunity where such multiple measurements of blood flow by the different optical beams can be exploited. After establishing the relative independence to spot size changes, we demonstrate the potential of utilizing the multiple optical beams to provide better microvascular imaging of normal human skin and non-melanoma skin cancer in vivo
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