Abstract

P 163

An observer independent evaluation of the distribution of blood flow over the cardiac cycle in glaucoma patients – an alternative approach of evaluation of color doppler imaging results

Wiermann A., Klemm M., Galambos P., Wagenfeld L., Richard G., Zeitz O.
Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Hamburg-Eppendorf

Objective: Color Doppler imaging results are usually expressed by the determination of peak systolic velocity (PSV) and end-diastolic velocity (EDV). This does not allow an individual evaluation of the results since the variance of measures is high. At last year’s DOG meeting the authors presented an alternative approach of evaluating color Doppler results (DOG 2006, Poster Nr. 063). This approach is based on an arbitrary morphologic classification of the distribution of blood flow over the cardiac cycle (spectral waveforms). A more objective computer aided algorithm was developed. This algorithm and its first application are presented in this work.
Methods: Fifty spectral waveforms from the short posterior ciliary artery of 23 healthy volunteers and 27 glaucoma patients were included in this study. The spectral waveform was imported into DigitizeIT^®. This software allows quantitative operations with bitmaps after introduction of a scale. In this scaled files background noise was quantified. The intersection of the spectral waveform with the background noise signal was determined. If the spectral waveform is above the background signal over more than 95% of the duration of the cardiac cycle it was judged as physiologic, if not as potential pathologic.
Results: The results from the algorithm were in 96% in accordance with the results from the data achieved arbitrarily. 81.5% (22 of 27) of the glaucoma population were judged as “potential pathologic”, while only 34.8% (8 of 23) of the healthy volunteers were assigned to this attribute.
Conclusions: The algorithm appears to mimic the arbitrary system in an almost perfect manner. It allows classifying the result from each patient individually. The clinical value of this system needs to be investigated further.

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