EFFICACY OF B-SCAN ULTRASONOGRAPHY VERSUS COMPUTED TOMOGRAPHY AMONG PATIENTS WITH THYROID ORBITOPATHY

Abstract

Background: Thyroid orbitopathy is the most common orbital manifestation of thyroid disease, and accurate assessment of extraocular muscle enlargement is essential for diagnosis and management, necessitating evaluation of the diagnostic efficacy of B-scan ultrasonography compared with computed tomography.

Objective: To compare the efficacy of B-scan ultrasonography and computed tomography (CT) in the assessment of orbital changes among patients with thyroid orbitopathy.

Methods: This prospective comparative cross-sectional study was conducted over six months (February to July 2026) at Mayo Hospital, Lahore. A total of 57 adults were enrolled using non-probability consecutive sampling. The sample size was calculated using G*Power version 3.1.9.4 (effect size = 0.5). All participants underwent comprehensive ophthalmic examination, including visual acuity assessment, slit-lamp biomicroscopy, and intraocular pressure measurement. Extraocular muscle thickness was measured using 10-MHz B-scan ultrasonography (Sonomed Ascalon) and orbital computed tomography (Toshiba Aquilion 128-slice) performed within one week. Agreement between B-scan ultrasonography and CT scan measurements was assessed using the paired t-test and Intraclass Correlation Coefficient (ICC), with p < 0.05 considered statistically significant.

Result: Right MR thickness increased significantly with severity on B-scan (4.73 to 5.89 mm; F = 88.890, p < 0.001) and CT (4.63 to 5.79 mm; F = 74.357, p < 0.001), while right SR also showed significant changes (B-scan: F = 5.682, p = 0.006; CT: F = 7.602, p = 0.001). CT additionally showed significant left LR changes (2.67 to 2.83 mm; F = 3.310, p = 0.044). B-scan measurements were significantly higher than CT measurements for all muscles (all p < 0.001), with differences of 0.10–0.30 mm.

Conclusion: B-scan ultrasonography demonstrated comparable performance to computed tomography in evaluating extraocular muscle involvement in thyroid orbitopathy, with similar patterns of progressive medial rectus enlargement despite slightly higher muscle thickness measurements