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Joby Tsai, Xuemin Zhang, Breanna Tracey, Osamah Saeedi; Variability of Vessel Caliber Measurement in En Face Optical Coherence Tomography Angiography Images. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3200.
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© ARVO (1962-2015); The Authors (2016-present)
Optical coherence tomography angiography (OCTA) provides a noninvasive method of visualizing ocular vasculature. Imperfect image registration and changes in vessel diameter with the cardiac cycle may increase variability of vessel caliber measurements. We performed a prospective observational study determining the intrasession reproducibility of OCTA measurements as well as the variability of vessel caliber comparing OCTA to ICG Angiography.
32 eyes of 19 participants underwent OCTA using two different devices (Heidelberg Spectralis, Zeiss Angioplex) and 13 eyes of 13 additional participants underwent ICG angiography using the Heidelberg Retinal Angiograph 2. Vessel caliber was measured in at least 20 equally spaced locations in nonbranching vessel segments of approximately 400-500 microns in the macula or peripapillary area. A subset of 10 eyes had repeat measurements with OCTA. Image quality was also graded. ImageJ was used to overlay images and to measure vessel caliber in pixels, which was converted into microns using participant-specific conversion factors. Mean, standard deviation (SD), and coefficient of variation (CoV) of vessel caliber for each vessel in both the OCTA and ICG angiography groups was calculated. Intraclass Correlation Coefficient (ICC) was used to determine the intravisit variability for OCTA measurements.
We analyzed 160 vessels of 32 eyes of 19 patients that underwent OCTA and 21 vessels of 13 eyes of 13 patients that underwent conventional ICG angiography. Average patient age was 51.5+/- 15.8 years and average vessel diameter was 57.3 microns wiith standard deviation of 6.8 microns. Intrasession variability for repeated OCT Angiography images was 0.86 for all images and 0.89 when excluding poor quality images. The mean CoV for all OCTA images was 0.14 and the mean CoV for ICG images was 0.10.
Intravisit variability for vessel caliber in OCT Angiography images was measured at 0.89. The coefficient of variation for vessel caliber is similar for OCT angiography and ICG angiography.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Example of vessel caliber measurement. Red lines indicate the segment of interest. Yellow points indicate coordinates used for vessel length measurement. Individual vessels were labelled numerically.
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