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CB Pesavento, A Harris, C Cole, L Kagemann; Circulation Time Analysis: The effect of Deinterlacing and Time Base Correction . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4338.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate the effects of time based correction (TBC) and de-interlacing on variability of arteriovenous passage(AVP) time analysis of SLO angiograms. Methods: In one healthy subject, a series of six 40 SLO fluoroscein angiograms were acquired with a Rodenstock SLO (SLO 101, Rodenstock GmbH, Munich Germany) and recorded on a SVHS VCR. To quantify variablility, discrepencies between AVP read from the video timer (manual) and calculated graphically from dilution curves were assessed. The video sequences were analysed by three techniques:1-a SVHS VCR was connected directly to a Scion image L-3 frame grabber to digitize each video segement, 2-de-interlacing was added to method one , and 3- time based correction was added to method 2. The discrepency between graphical and manual analysis for each of the three methods was compared by paired students' T-test, with an alpha of 0.05 or less considered significant. Coefficient of variation for each method was calculated. Results: The discrepancy between manual and graphical AVP analysis was significantly reduced with the addition of TBC and de-interlacing (p=0.0207), with a coefficient of variance reduction from 7.57% to 0.15%. Conclusion: The variability of AVP analysis can be reduced dramatically by utilizing TBC and de-interlacing. This reduction in variability may imply an improvement in the statistical power necessary to detect physiological changes.
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