Microcirculation imaging based on full-range high-speed spectral domain correlation mapping optical coherence tomography

Abstract

Publication InformationSubhash HM, Leahy MJ; Microcirculation imaging based on full-range high-speed spectral domain correlation mapping optical coherence tomography. J. Biomed. Opt. 0001;19(2):021103-021103. Abstract. Microcirculation imaging is a key parameter for studying the pathophysiological processes of various disease conditions, in both clinical and fundamental research. A full-range spectral-domain correlation mapping optical coherence tomography (cm-OCT) method to obtain a complex-conjugate-free, full-range depth-resolved microcirculation map is presented. The proposed system is based on a high-speed spectrometer at 91 kHz with a modified scanning protocol to achieve higher acquisition speed to render cm-OCT images with highspeed and wide scan range. The mirror image elimination is based on linear phase modulation of B-frames by introducing a slight off-set of the probe beam with respect to the lateral scanning fast mirror's pivot axis. An algorithm that exploits the Hilbert transform to obtain a complex-conjugate-free image in conjunction with the cm-OCT algorithm is used to obtain full-range imaging of microcirculation within tissue beds in vivo. The estimated sensitivity of the system was around 105 dB near the zero-delay line with ∼20 dB roll-off from AE0.5 to AE3 mm imagingdepth position. The estimated axial and lateral resolutions are ∼12 and ∼30 μm, respectively. A direct consequence of this complex conjugate artifact elimination is the enhanced flow imaging sensitivity for deep tissue imaging application by imaging through the most sensitive zero-delay line and doubling the imaging range. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Artefacts Removal from Optical Coherence Tomography Angiography

“…the correlation measures between frame 1 and frame 2, frame 2 and frame 3, and frame 3 and frame 4. This is different and in contrast to the method proposed in [9] where correlation is computed between the two OCT B-frames obtained by the averaging of frames 1 and 2 and the averaging of frames 3 and 4. We found that our proposed approach produces better results.…”

“…Firstly, we compute the correlation for consecutive frames of B-scans [9] using the following equation (2):…”

“…The correlation matching OCT (cmOCT) method [3,9] allows differentiation of flow regions since the static regions will have high correlation values while the flow regions will usually have low correlation values. The cmOCT method is achieved solely through the processing of the OCT amplitude and does not require phase information.…”

“…To compute the OCT angiography, firstly, two full-range amplitude OCT images were calculated by averaging the two consecutive frames of the four OCT images captured at the same lateral position. Then, the correlation between these two full-range OCT B-frames is determined by cross-correlating a grid from frame A (average of frames 1 and 2) to the same grid position from frame B (average of frames 3 and 4) [9].…”

Developing cross-correlation as a method for microvessel imaging using clinical intravascular optical coherence tomography systems

“…Intensity based correlation approaches have been reported for transverse flow measurements [17,18]. Recently vascular imaging using the correlation approach has also been reported [19][20][21][22].…”