Blood vessel tail artifacts suppression in optical coherence tomography angiography

Abstract

. Significance: A long-standing challenge of the blood vessel tail artifacts along the axial direction prevents optical coherence tomography angiography (OCTA) for a comprehensive three-dimensional (3D) vascular mapping. Addressing the blood vessel tail artifacts issue will make OCTA to be a real 3D blood vessel structural imaging technique, which in combination with OCT-based blood flow velocity measurements will pave the way for a simpler and robust 3D imaging of the capillary transit time, one important parameter for the evaluation of micro circulation. Approach: We first described the basic principles of OCTA imaging, discussed the origin of blood vessel tail artifacts in an OCTA image, then reviewed the existing OCTA techniques for tail artifacts suppression, and at last we envisioned the potential solutions for effective OCTA tail artifacts suppression. Results: The origin of blood vessel tail artifacts is due to the multiple scattering of photons with flowing red blood cells, which elongates the light path of the dynamic signal from vessel lumen to the tail regions. High numerical aperture implementation, subtraction-based post-data processing, Hessian filtering, and high acquisition rate-based dynamic analysis methods have been proposed to address the blood vessel tail artifacts issue in OCTA. Conclusions: High acquisition rate-based dynamic analysis in combination with Hessian filtering have the potential to effectively suppress the blood vessel tail artifacts and in the meantime preserve flows in small vessels within the tail region, providing real 3D OCTA imaging of blood vessel structures.

Pupil vignetting artifact on optical coherence tomography angiography

“…It is exacerbated by small pupil size, slow pupillary dynamics as observed in sluggish pupillary reaction to light, and increased field size. [ 14 15 16 17 ]…”

OCT-based measurement of cerebral blood vessel structure, blood flow velocity, and blood transit time

“…Traditional Optical Coherence Tomography angiography (OCTA) often faces the challenge of projection artifacts when reconstructing three-dimensional vascular structures [4] [11]. Recently, several methods have been developed to achieve accurate reconstruction of the threedimensional vascular structure [12], such as enhancing the contrast by adding intralipid [13], and utilizing algorithms based on phase information [2], intensity information [14], and complex-domain decorrelation [15][16] have also played an important role in improving the detection of capillaries. Although two-photon microscopy has high resolution [9][10], its limited depth of field makes it difficult to capture more complex structural information [17].…”

Tail Artifact Removal via Transmittance Effect Subtraction in Optical Coherence Tail Artifact Images

“…OCTA faces a significant challenge-occurrence of imaging artifacts known as projection artifacts or tail artifacts. These artifacts occur for various reasons, including variation of transmitted incident light to deeper layers due to the variable transmittance in the shallow layers with the vasculature [13,14] and elongated light paths from multiple scattering of photons interacting with flowing RBCs [15,16]. Variation of transmitted incident light to deeper layers due to the variable transmittance in the shallow layers causes OCT signal variation even in the absence of reflectivity variation, generating vasculature-like signals beneath the vasculature.…”