A digital frequency ramping method for enhancing Doppler flow imaging in Fourier-domain optical coherence tomography

1Department of Biomedical Engineering, Stony Brook University, NY, Stony Brook, NY 11794, USA.
Optics Express (Impact Factor: 3.49). 04/2009; 17(5):3951-63. DOI: 10.1364/OE.17.003951
Source: PubMed


A digital frequency ramping method (DFRM) is proposed to improve the signal-to-noise ratio (SNR) of Doppler flow imaging in Fourier-domain optical coherence tomography (FDOCT). To examine the efficacy of DFRM for enhancing flow detection, computer simulation and tissue phantom study were conducted for phase noise reduction and flow quantification. In addition, the utility of this technique was validated in our in vivo clinical bladder imaging with endoscopic FDOCT. The Doppler flow images reconstructed by DFRM were compared with the counterparts by traditional Doppler FDOCT. The results demonstrate that DFRM enables real-time Doppler FDOCT imaging at significantly enhanced sensitivity without hardware modification, thus rendering it uniquely suitable for endoscopic subsurface blood flow imaging and diagnosis.

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    • "Compared with the previous DFR algorithm(Yuan et al., 2009), the two sets of summation operations in Eq.(6) accumulate the results from each step and further reduce the noise level because of the averaging effect. Here, (v f − i · Δ v)>0 and (v f − i · Δ v)<0 are both Boolean functions (i.e., 1 for 'true', 0 for 'false'), and the sign of v f can be determined by "
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    • "Furthermore, recently we used laser-speckle imaging and also observed decreases of cortical blood flow in tissue in response to an acute cocaine challenge in ISO-anesthetized animals (Luo et al., 2009). Most recently, by using 3D Doppler Optical Coherent tomography (DOCT), a technique that permits to quantitatively image CBF and vascular profiles (Yuan et al., 2009) we visualized what appears to be cocaine-induced cortical vasoconstriction in ISO-anesthetized rat brain (data not shown). Our current results are in agreement with the previous finding of a negative BOLD signal on the immediate cortical surface (Schmidt et al., 2006) in ISO-anesthetized rats that used a similar experimental condition (ISO=1.1%, "
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