Joint Iterative Reconstruction and Motion Compensation for Optical Coherence Tomography Angiography

Joint Iterative Reconstruction and Motion Compensation for Optical Coherence Tomography Angiography

(Third Party Funds Single)

Titel des Gesamtprojektes:
Projektleitung: ,
Projektbeteiligte: , ,
Projektstart: August 1, 2017
Projektende: July 31, 2019
Akronym: Joint Reco & MoCo for OCT(A)
Mittelgeber: DFG-Einzelförderung / Sachbeihilfe (EIN-SBH)
URL:

Abstract

Optical coherence tomography (OCT) is a non-invasive 3-D optical imaging modality that is a standard of care in ophthalmology [1,2]. Since the introduction of Fourier-domain OCT [3], dramatic increases in imaging speed became possible, enabling 3-D volumetric data to be acquired. Typically, a region of the retina is scanned line by line, where each scanned line acquires a cross-sectional image or a B-scan. Since B-scans are acquired in milliseconds, slices extracted along a scan line, or the fast scan axis, are barely affected by motion. In contrast, slices extracted orthogonally to scan lines, i. e. in slow scan direction, are affected by various types of eye motion occurring throughout the full, multi-second volume acquisition time. The most relevant types of eye movements during acquisition are (micro-)saccades, which can introduce discontinuities or gaps between B-scans, and slow drifts, which cause small, slowly changing distortion [4]. Additional eye motion is caused by pulsatile blood flow, respiration and head motion. Despite ongoing advances in instrument scanning speed [5,6] typical volume acquisition times have not decreased. Instead, the additional scanning speed is used for dense volumetric scanning or wider fields of view [7]. OCT angiography (OCTA) [8–11] multiplies the required number of scans by at least two, and even more scans are needed to accommodate recent developments in blood flow speed estimation which are based on multiple interscan times [12,13]. As a consequence, there is an ongoing need for improvement in motion compensation especially in pathology [14–16].

We develop novel methods for retrospective motion correction of OCT volume scans of the anterior and posterior eye, and widefield imaging. Our algorithms are clinically usable due to their suitability for patients with limited fixation capabilities and increased amount of motion, due to their fast processing speed, and their high accuracy, both in terms of alignment and motion correction. By merging multiple accurately aligned scans, image quality can be increased substantially, enabling the inspection of novel features.

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