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Christoph Mitsch, Jan Lammer, Laurin Ginner, Daniel Fechtig, Cedric Blatter, Rainer A Leitgeb, Ursula Schmidt-Erfurth; Comparison of the manually delineated Foveal Avascular Zone on Traditional Fluorescein Angiography and Doppler Optical Coherence Tomography Images acquired using a 1060nm Swept-Source Speckle-Variance Doppler-OCT Angiography Prototype. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5271.
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© ARVO (1962-2015); The Authors (2016-present)
Doppler-optical coherence angiography (DOCT-A) represents a non-invasive alternative to traditional, dye-based fluorescein angiography (FA). Due to the considerable difference of the image acquisition and computation techniques of both modalities, the comparability of the results needs to be evaluated.
On a single-day visit, patients underwent both FA and DOCT-A examinations. Early phase FA images were exported and en-face projections of of the DOCT-A image stacks were generated. The resulting dataset was duplicated and masked. Two graders delineated the foveal avascular zone (FAZ) on every image of each patient and modality two times. The resulting FAZ area values were compared by calculating the Spearman Product-Moment Correlation Coefficient to illustrate inter- and intra-grader reproducibility in both modalities and the intra-modality reproducibility.
22 eyes of 18 patients with different retinal pathologies were imaged. The FAZ areas (in square degrees) delineated in DOCT-A images measured 2.97±1.98 (range 0.68-9.24) in grader 1 and 3.69±2.62 (range 0.99-11.89) in grader 2. On FA, the areas measured 3.51±2.32 (range 0.83-10.33) in grader 1 and 5.15±3.89 (range 1.58-17.47) in grader 2, respectively. The intra-grader FAZ delineation correlation coefficients in DOCT-A and FA were 0.88 and 0.99 in grader 1 and 0.8 and 0.83 in grader 2. The resulting inter-grader DOCT-A and FA correlation coefficients were 0.75 and -0.25, respectively. Inter-modality correlation coefficients were 0.36 in grader 1, 0.1 in grader 2 and 0.29 for the means.
The FAZ area delineated on DOCT-A images showed strong inter-grader correlation, higher than in FA images, which was only weak. Inter-modality correlation was weak in one grader and in the grader means and very weak in the other grader. Although these results may reveal a wide range of interpretability differences for both modalities, the strong inter-grader correlation in DOCT-A FAZ delineation detected in our data is promising. The weak intra-modality comparability needs to be interpreted accounting for the elemental differences of both image acquisition techniques and their resulting individual sources of quality- and interpretability cutbacks.
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