Quantitative evaluation of activity of thyroid-associated Ophthalmopathy using short-tau inversion recovery (STIR) sequence

Qian Huang,Xiaohui Zhang,Lu Wang,Qian Ge,Yao Fan,Chun Liu,Jian Long,Ning Yao

doi:10.1186/s12902-021-00895-3

Abstract

ObjectiveQuantitatively staging TAO using MRI remains limited. Our study aims to identify the cut-off signal intensity value for staging TAO using STIR sequence scan.MethodsBetween June 2018 and July 2020, a number of 51 patients with TAO (102 eyes) and 19 volunteer controls (38 eyes) were recruited. The clinical and biochemical parameters were measured in each patient. Disease activity was diagnosed based on the Clinical Activity Score (CAS). The signal intensities of extraocular muscles were scanned using short-tau inversion recovery (STIR) sequences from MRI.ResultsCompared to the inactive TAO patients and the controls, the signal intensity ratios (SIRs) of the superior rectus, inferior rectus, medial rectus, lateral rectus on STIR images were significantly increased in the active TAO patients. After adjustment for age and smokers, the SIRs of four extraocular muscles showed strong associations with CAS. By receiver operator characteristic (ROC) curve analysis, all four muscle SIRs demonstrated good efficiency for predicting disease activity [area under curve (AUC) 0.75–0.83, all P < 0.01]. The identified cut-off SIR values were further validated in a new group of TAO patients (30 eyes) enrolled between September 2020 and January 2021. The cut-off SIR value of > 2.9 in the inferior rectus showed optimal diagnostic value for staging the active TAO.Conclusionsthe signal intensity of extraocular muscles on STIR sequence was a good predictor for TAO activity. A cut-off SIR value of > 2.9 in the inferior rectus could be applied to evaluate the active stage of TAO.

Highlights

Thyroid-associated ophthalmopathy (TAO) is a chronic inflammatory autoimmune disease of periorbital tissue [1,2,3]
We took advantage of the short-tau inversion recovery (STIR) sequence of Magnetic resonance imaging (MRI) to scan the extraocular muscles because the high signal intensity indicates edema caused by inflammation in extraocular muscles
Several studies in European patients observed that changes in signal intensity of the extraocular muscles on STIR closely correlate with Clinical Activity Score (CAS) [9, 10, 14, 15], demonstrating that the STIR sequence was a valuable tool for evaluating disease activity

Summary

Introduction

Thyroid-associated ophthalmopathy (TAO) is a chronic inflammatory autoimmune disease of periorbital tissue [1,2,3]. The course of the disease can be divided into two stages: active inflammation and inactive fibrosis. The active stage is characterized by lymphocytic infiltration, edema in the extraocular muscles, and orbital fat expansion. The inactive stage is featured with fibrosis and fatty degeneration in the extraocular muscles [4]. Patients in the active stage have a good response to immunosuppressive treatment of glucocorticoid. In the subsequently inactive phase, patients can no longer benefit from glucocorticoid treatment, with surgical decompression being the only solution [5, 6]. It is crucial in clinical practice to accurately diagnose the two stages and give the appropriate therapy

Methods

Results

Conclusion