Artikel
Volumetric color-Doppler imaging in glaucoma
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Autoren
Veröffentlicht: | 22. September 2004 |
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Gliederung
Text
Objective
Previous studies have postulated volumetric color-Doppler imaging (vCDI) as suitable method to determine the blood flow of in orbital vessels. Blood flow is calculated in vCDI from cross sectional area of the vessel and blood flow velocity. In the present study, the degree of fitness of this method for clinical use is evaluated systematically.
Methods
Evaluation of vCDI by the present study was done in four steps: 1) Reproducibility of results was tested in 20 patients. 2) Results from two different investigators were compared in 20 patients. 3) Results from vCDI were correlated with measurements of ocular pulse amplitude by the Langham method (OPA) in 69 patients. 4) Finally, in 15 patients the capability of the method to identify changes of ocular perfusion was tested by applying topically dorzolamide. OPA-measurements were performed with an OBF Tonometer 3000 with a pneumatic probe. CDI was done with a Siemens Elegra (Siemens, Erlangen Germany) at 7.5 MHz.
Results
Velocity measurements using CDI in ophthalmic artery and central retinal artery were highly reproducible (n=20, Single Measure Intraclass Correlation (SMIC) >0.70 for all parameters) and independent of the observer (n=20). In contrast, low reproducibility and high observer dependence in measuring diameter and thus in volume were found (n=20). Reproducibility improved if five consecutive measures were averaged. No correlation between the vCDI parameters and the LOBF readings could be identified (n=69). Dorzolamide accelerated blood flow as expected (n=15). Nevertheless, the blood volume per time determined by vCDI remained unchanged (n=15).
Conclusions
As reported previously, standard CDI-measurements were highly reproducible. Reliability of vCDI measurements is low due to the low reproducibility of vessel diameter measurements. Thus vCDI in its present form is not suitable for use in clinic and research.