Quantitative, noninvasive assessment of intra‐ and extraocular perfusion by contrast‐enhanced ultrasonography and its clinical applicability in healthy dogs

Abstract

ObjectiveTo assess quantitative perfusion of intra‐ and extraocular regions of interest (ROIs) in conscious, healthy dogs utilizing contrast‐enhanced ultrasonography (CEUS); to compare varying enhancement with the first and second bolus injection and in the right and left eye; and to determine the most appropriate examination time.ProceduresGray scale ultrasonography and contrast harmonic imaging using sulfur hexafluoride were performed randomly assigned in both eyes in 10 university‐owned beagles. Perfusion parameters including slope time, time to peak (TTP), peak intensity (PI), and area under the curve (AUC) were measured at individually drawn ROIs (retrobulbar cone = ROI 1, choroid‐retina complex = ROI 2, medial = ROI 3, and lateral anterior uvea = ROI 4).ResultsTime‐intensity curve parameters revealed no significant differences in eyes examined by the first or second bolus injection (P > 0.05) or in the right or left eye (P > 0.05). Pooled data from all eyes were analyzed. Peak intensity of ROI 2 was significantly higher compared to all other ROIs (P < 0.001). Area under the curve at ROI 2 was significantly higher compared to all other ROIs (P < 0.05), and AUC at ROI 1 was significantly higher than at ROI 4 (P < 0.05). No significant differences in TTP were observed between different ROIs (P > 0.05). Ratios relative to different ROI sizes showed fastest enhancement in the retrobulbar cone and most intense perfusion in the anterior uveal regions. The first minute after contrast injection provided the highest diagnostic value.ConclusionQuantitative perfusion in nondiseased canine eyes revealed consistent parameters. Application of standardized CEUS protocols may be a promising diagnostic tool to differentiate ocular lesions.

Clinical utility, dose determination, and safety of ocular contrast‐enhanced ultrasonography in horses: A pilot study

“…According to the bodyweights of individual horses that received 15 mL, this dose was equivalent to dosages from 0.024 to 0.028 mL/kg. Although the decibel values cannot be compared directly to previous canine studies, contrast enhancement, as a measure of microbubble concentration, seemed to be less intense in equine eyes. Strikingly, diagnostic unilateral and bilateral ocular CEUS sequences were obtained in horses administered 0.019, 0.026, 0.028, and 0.034 mL/kg, whereas the eyes of other individuals showed no contrast enhancement following dosages of 0.024, 0.026, and even 0.036 and 0.043 mL/kg.…”

“…Despite being a straightforward technique in small animals the applicability of ocular CEUS in horses was uncertain. In anesthetized and conscious beagles using commercial decafluorobutane (Sonazoid®) and SF6 (SonoVue®), respectively, ocular CEUS resulted in 100% visible and measurable enhancement. Technically, it was feasible to perform ocular CEUS in sedated horses of our study population.…”

“…The direct comparison of both eyes within the same horse showed that the higher dose yielded successful enhancement in all animals, which exhibited unilateral contrast detection only. A confounding accumulative effect in the second eye, after the elapse of at least five minutes between bolus injections, is unlikely according to our previous results of bilateral ocular CEUS in dogs and the crossover allocation of the lower and higher dose in this study.…”

“…This pilot study investigated if SF6 dosages utilized in other species do apply to the horse. The current findings caused us to scrutinize our hypothesis that SF6 dosages used for CEUS in feline (0.03 mL/kg) and canine (0.03 mL/kg; 0.05 mL/kg) eyes can be extrapolated to examine ocular perfusion in horses. In a clinical study, 0.1 mL/kg was given to distinguish retinal detachment vs vitreous membrane in cats and dogs, but applying corresponding 50 mL of SonoVue® in a horse is barely affordable.…”

“…Globe rupture, lens luxation, lens rupture, retinal detachment, and retrobulbar lesions have been depicted by conventional ultrasonography. Despite being noninvasive, cost‐effective, and widely available, the B‐mode echogenicity is often equivocal which indicates extended modalities (Doppler and contrast imaging), providing additional information on blood flow and perfusion …”