Model-based optical coherence tomography angiography enables motion-insensitive vascular imaging

We present a significant step toward ultrahigh-resolution, motion-insensitive characterization of vascular dynamics. Optical coherence tomography angiography (OCTA) is an invaluable diagnostic technology for non-invasive, label-free vascular imaging in vivo. However, since it relies on detecting moving cells from consecutive scans, high-resolution OCTA is susceptible to tissue motion, which imposes challenges in resolving and quantifying small vessels. We developed a novel OCTA technique named ultrahigh-resolution factor angiography (URFA) by modeling repeated scans as generative latent variables, with a common variance representing shared features and a unique variance representing motion. By iteratively maximizing the combined log-likelihood probability of these variances, the unique variance is largely separated. Meanwhile, features in the common variance are decoupled, in which vessels with dynamic flow are extracted from tissue structure by integrating high-order factors. Combined with Gabor-domain optical coherence microscopy, URFA successfully extracted high-resolution cutaneous vasculature despite severe involuntary tissue motion and scanner oscillation, significantly improving the visualization and characterization of micro-capillaries in vivo. Compared with the conventional approach, URFA reduces motion artifacts by nearly 50% on average, evaluated on local differences. Three-dimensional (3D) imaging of biological tissue in vivo with high resolution is essential for diagnosing and treating pathological conditions. Various optical imaging techniques have been developed to achieve this purpose, among which optical coherence tomography (OCT) has proven its clinical significance for non-invasive diagnoses in ophthalmology [1], dermatology [2], neurology [3], et al. In addition to the OCT-imaged anatomic structure, the blood vessels in the micro-circulatory tissue bed support crucial tissue metabolism functions by exchanging nutrients and oxygen with proximal cells. The functional extension of OCT to visualize tissue perfusion together with the co-registered structure aids in monitoring the disease progression and accordingly adjusting the medical interventions. Relying upon label-free endogenous flow of blood cells, one promising

Automated summary

A new OCTA technique, URFA, was developed to extract high-resolution cutaneous vasculature, significantly improving the visualization and characterization of micro-capillaries in vivo, and reducing motion artifacts by nearly 50% on average.