The Use of Contrast Enhanced Ultrasound for Visualization and Differentiation of Intraocular and Extraocular Circulations

Abstract

Purpose:: To evaluate the use of contrast enhanced ultrasound for the differentiation of bulbar and retrobulbar circulations

Methods:: We administered an ultrasound contrast agent (Levovist) intravenously and real time scans were performed in an intermittent (2Hz) scan frame rate at a reduced Mechanical Index (0.25) with an 8MHz linear transducer tuned to detect 2nd harmonic echoes from the contrast material. Video sequences were recorded for 1 min from which the intrabulbar and retrobulbar component of ocular circulation were easily depicted as separate structures of contrast enhancement. We examined 7 patients with this new modality. Semi quantitative measurements were obtained at specific areas of interest throughout the intra- and retro-bulbar regions by constructing contrast-to-time transit curves from the video recordings. The maximum inclination of the wash-in component of each curve was calculated to represent the blood-flow rate at each area of interest.

Results:: The technique permitted objective measurable data to be retrieved distinctively from the intrabulbar vascular structures. The inclination of the bulbar component in the examined group of patients was ranging from 601 to 3414 (aver. 1989) while the inclination of the retrobulbar component was ranging from 635 to 2479 (aver.1482).

Conclusions:: Contrast enhanced ultrasound imaging can provide a new method for the study of ocular circulation in healthy and diseased individuals.

Keywords: blood supply • retina • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)