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Shuichi Makita, Shinnosuke Azuma, Masahiro Miura, Tatsuo Yamaguchi, Toshihiro Mino, Yoshiaki Yasuno; Motion-free, multi-contrast optical coherence tomography by Lissajous scan. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1284.
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© ARVO (1962-2015); The Authors (2016-present)
En face mapping with optical coherence tomography (OCT) is frequently suffered by eye motion and appeared with motion artifacts. This paper aims at demonstrating motion-free en face mapping of multi-contrast OCT. The motion-free imaging performance with patients’ eyes is discussed.
The Lissajous OCTA scan pattern previously demonstrated by the authors was used. Two consecutive Lissajous curve cycles scan the same position, and OCTA signal is obtained by applying OCTA algorithm to the cycle pair. Any arbitrary pair of sets of the Lissajous scan cycles has overlapping regions. The eye motion is estimated by registration of the overlapped regions. En face maps of OCT can be corrected by the estimated motion amounts.Sixty-four patients were scanned with the simple multi-contrast OCT system, which is a custom-made 1.0-µm swept-source OCT with a scan speed of 100,000 A-line/s. The long acquisition time is applied to enable the robust motion correction and high-resolution en face imaging by using redundant data. The system provides images of OCT, OCTA, and degree-of-polarization uniformity (DOPU) which contrasts melanin.
Several volumes were acquired from each patient’s eye. Motion estimation and correction were applied for all volumes of 64 patients. The successful rate of the motion correction was 78.7 %.Figure 1 shows motion-free en face images of a choroidal neovascularization (CNV) subject provided by multi-contrast OCT. By employing additional contrast of DOPU, the composite image of OCTA and DOPU called as pigment and flow (PAF) image (Fig. 1B), choroidal vesselness (CV) map (Fig. 1D), and melano-layer thickness (MLT) map (Fig. 1E) were obtained. The PAF image contrasts blood flow of abnormal vessel and the retinal pigment epithelium (RPE) defects. The motion-free images are suitable for comparison with other modalities. A near-infrared fundus auto-fluorescence imaging (NIR-FAF) of the same eye is shown in Fig. 1F. The location of thick melanin in MLT is in good agreement with that of hyper-autofluorescence in NIR-FAF (green arrow).
Lissajous scan multi-contrast OCT provides several motion-free en face maps of tissue futures. This method will be suitable to survey eye disease condition.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Motion-free en face multi-contrast OCT imaging results of a subject with CNV. (A) OCT, (B) PAF, (C) retinal OCTA of the inner retina, (D) choroidal vasculature, (E) RPE melanin thickness, and (F) NIR-FAF.
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