Contrast‐enhanced ultrasonography for evaluation of blood perfusion in normal canine eyes

OBJECTIVE: This study was performed to evaluate ocular structures using contrast‐enhanced ultrasonography (CEUS) in dogs to assess the feasibility of CEUS for investigating the blood perfusion of canine eyes. ANIMAL STUDIED: Eight purpose‐bred beagles were used. PROCEDURES: Blood perfusion and vascularity of the right eye were evaluated using color Doppler, power Doppler, and CEUS with Sonazoid®. Vascular changes were quantitatively evaluated by measuring peak intensity, time to initial upslope, and time to peak from the ciliary body, iris, choroid, retina, and the retrobulbar region by CEUS. RESULTS: On CEUS images, all parts of the examined ocular structures were markedly enhanced and clearly identified from the adjacent region. After injection, the contrast agent initially flowed to the choroid and retina at 14.2 seconds, then to the ciliary body and iris at 20 seconds. The blood signal reached its peak intensity in the ciliary body at 27.2 seconds (47.4 ± 10.63), in the iris at 31.6 seconds (74.00 ± 41.85), and in the retrobulbar region at 23.4 seconds (149 ± 24.59). The optic nerve was clearly distinguished from the retrobulbar region over 5 minutes after the initiation of CEUS. Significantly, more vascular signals were detected in the ciliary body and iris by CEUS than by color and power Doppler. CONCLUSION: Blood perfusion of the intraocular structures and the retrobulbar region can be quantitatively and qualitatively analyzed by CEUS. CEUS may be a useful, noninvasive, and sensitive tool for the evaluation of blood perfusion in ocular diseases.