Comparison of Area Dilution Analysis with Color Doppler Imaging

Abstract

Abstract: : Purpose: To assess whether area dilution analysis (ADA) of indocyanine green (ICG) angiograms are correlated with posterior ciliary artery blood velocity in primary open angle glaucoma (POAG). Methods: All procedures were approved by an IRB, and informed consent was obtained. Fifteen patients with POAG (58.4 ± 7.2 years, 7 m, 8 f) were recruited for this double blind randomized cross–over study. All patients received a 4 week run in of 0.5% timolol BID, followed by 8 weeks treatment of 0.2% brimonidine TID or continuation of 0.5% timolol BID plus placebo QD. Blood flow velocites were assessed at baseline and 8 weeks post treatment by measuring the end diastolic velocity (EDV) and peak systolic velocity (PSV) of the nasal and temporal short posterior ciliary arteries (NPCA and TPCA respectively) using a Siemens Quantum 2000 Color Doppler Imaging technology (Siemens Quantum, Inc., Issaquah WA) with a 7.5 MHz linear probe. The resistive indices (RI) were then calculated using the equation RI=(PSV–EDV)/PSV. ICG angiography was attained at baseline and 8 weeks post drug using a Rodenstock scanning laser ophthalmoscope (SLO 101, Germany). The recorded images were analyzed using a digital image analysis system where six 63x63 pixel areas, two peripapillary and four perifoveal, are selected for measurement (figure 1). After correction for eye movements, the digital image analysis system recorded brightness levels at all six areas over time. The brightness was plotted over time to attain 10 and 63 percent maximum brightness times. Linear regression analysis was used to determine correlations between retrobulbar hemodynamics and ICG measurement parameters. Results: NPCA RI correlated with 15 of 16 ICG measurement values. This includes significant correlations for all 63% values, and all but one 10% value with p values ranging from 0.025 to 0.049. Conclusions: Agreement between CDI assessment of PCAs and ADA assessment of local choroidal hemodynamics supports the validity of each technique.  

Keywords: imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • blood supply