Purpose: Clinical, radiographic, and molecular studies have shown that patients with thyroid-associated orbitopathy exhibit volumetric expansion of eyebrow tissues. This clinicopathologic entity has been termed thyroid-associated periorbitopathy. The goal of this study was to determine whether high-resolution ultrasonography could be used to reliably quantify thyroid-associated periorbitopathy.
Methods: Institutional review board approval was obtained. The internal case-control study consisted of 12 subjects with unilateral-asymmetric thyroid-associated orbitopathy. High-resolution ultrasonography using a 15-MHz probe (Logiq p6) was performed by a single operator. Measurements were obtained 0.5 cm cephalad to the superior orbital rim at the midpupillary sagittal level. For each subject and tissue layer thickness (total tissue, dermis fat, retro-orbicularis oculi fat), the measured values on the less affected side were subtracted from those on the more severely diseased side. Summary statistics were used to analyze results.
Results: High-resolution ultrasonography effectively demonstrated asymmetric expansion of total eyebrow tissue (p < 0.0001) and retro-orbicularis oculi fat (p = 0.0003). No significant difference in dermis fat thickness was found between the 2 sides (p = 0.2). Hertel exophthalmometry measurements were statistically different between the 2 sides (p = 0.002).
Conclusions: This study demonstrates that high-resolution ultrasonography independently confirms previously published studies of retro-orbicularis oculi fat expansion in patients with thyroid-associated orbitopathy. Compared with CT, MRI, and tissue biopsy, high-resolution ultrasonography is a more practical and cost-effective way to quantify and track thyroid-associated periorbitopathy over time. With its potential for real-time tissue assessment, high-resolution ultrasonography may be best suited for future studies of the dynamic relationship between globe and periorbital structures.