Extraocular Muscle Signal Intensity May Predict Thyroid-Associated Ophthalmopathy

A cut-off signal intensity ratio value higher than 2.9 in the inferior rectus could be applied to evaluate the active stage of the disease, researchers believe.

Extraocular muscle signal intensity is a good predictor of thyroid-associated ophthalmopathy (TAO) activity, according to results of a study published in BMC Endocrine Disorders.

Patients (n=51) with treatment-naïve TAO and healthy volunteers (n=19) were recruited between 2018 and 2020 at the First Affiliated Hospital of Chongqing in China. Study participants were assessed for clinical and biochemical parameters, clinical activity scores, and underwent a corneal orbital magnetic resonance imaging (MRI). Extraocular muscle signal intensities were scanned using short-tau inversion recovery (STIR) of MRI images.

The patients with active (n=25) and inactive (n=26) TAO and controls were aged mean 51.56±10.23, 43.00±12.93, and 46.10±15.45 years and 56.00%, 38.46%, and 38.71% were men, respectively.

Compared with controls, patients with TAO had elevated free triiodothyronine, thyroid peroxidase antibody, thyroglobulin antibody, thyroid stimulating receptor antibody, intraocular pressure, and exophthalmos (all P ≤.03). The active and inactive TAO patients differed significantly for proportion of smokers, eyesight, intraocular pressure, exophthalmos, and disease severity (all P ≤.02).

Signal intensity ratios (SIRs) of extraocular muscles did not differ between controls and those with inactive TAO. Patients with active TAO had increased superior, inferior, medial, and lateral recti SIRs compared with controls (all P <.001) and patients with inactive disease (all P <.001).

After adjusting for age and smoking status, active disease associated with SIRs of superior (adjusted odds ratio [aOR], 3.76; 95% CI, 1.86-7.60; P <.01), medial (aOR, 2.93; 95% CI, 1.43-6.01), inferior (aOR, 1.91; 95% CI, 1.17-3.12; P <.01), and lateral (aOR, 2.69; 95% CI, 1.24-5.85; P =.01) recti.

Active TAO could be predicted with SIR cutoffs of 2.48 for superior (area under the curve [AUC], 0.83; specificity, 80.50%; sensitivity, 74.50%), 2.90 for inferior (AUC, 0.83; specificity, 84.07%; sensitivity, 76.47%), 2.57 for medial (AUC, 0.80; specificity, 77.00%; sensitivity, 70.60%), and 2.74 for lateral (AUC, 0.76; specificity, 83.20%; sensitivity, 60.80%) recti (all P <.001).

This study was likely limited by power due to the low sample size.

These findings indicated that STIR sequence of the signal intensity of extraocular muscles may be an effective prediction strategy for TAO activity.


Ge Q, Zhang X, Wang L, et al. Quantitative evaluation of activity of thyroid-associated Ophthalmopathy using short-tau inversion recovery (STIR) sequence. BMC Endocr Disord. 2021;21(1):226. doi:10.1186/s12902-021-00895-3