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A. Wiermann, O. Zeitz, P. Galambos, N. Matthiesen, L. Wagenfeld, G. Richard, M. Klemm; Alternative Models for the Evaluation of CDI: Graphical Analysis of the Spectral Waveform. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2296.
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© ARVO (1962-2015); The Authors (2016-present)
Color Doppler imaging (CDI) is classically evaluated by extracting parameters like peak systolic velocity and end-diastolic velocity from the spectral waveforms. This leads to a loss of lots of the information included in the measurements, particularly the distribution of blood flow over the cardiac cycle. Therefore we developed a conception to evaluate the shape of the spectral waveform curve (ARVO 2006 poster #487). Since our recent work is based on arbitrary decisions, we propose four automated algorithms for the evaluation of CDI measurements in this study and also report on a preliminary application of these algorithms in a comparison of glaucoma patients and healthy controls.
10 glaucoma patients and 10 healthy volunteers were enrolled in the study. Color Doppler Imaging was performed with a Siemens Elegra set-up (transducer 7.5L40 at 6.5 MHz). The central retinal artery (CRA) and the short posterior ciliary artery (SPCA) were investigated in color doppler mode, registering PSV, EDV, RI and the spectral waveform of blood flow velocity over the whole cardiac cycle. A digital image of this waveform was analysed with an image analysing computer program regarding to the proportion of black and white pixels within a defined area. Therefore different frames were used: 33% and 50% height of the PSV versus the evaluation of the diastole only, and the curve without background noises.
Six out of 40 curves consisted of poor contrast and couldn’t be evaluated.
Differences between glaucoma patients and normal subjects were found with all algorithms. If the frame with the height of 33% of the PSV is used to evaluate the spectral waveform of blood flow velocity over the whole cardiac cycle, the highest discriminatory power can be achieved.
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