Thyroid-associated Orbitopathy: Quantitative Evaluation of the Orbital Fat Volume and Edema Using IDEAL-FSE

Dixon MRI-based quantitative parameters of extraocular muscles, intraorbital fat, and lacrimal glands for staging thyroid-associated ophthalmopathy

OBJECTIVE

To investigate the value of Dixon magnetic resonance imaging (MRI)-based quantitative parameters of extraocular muscles (EOMs), intraorbital fat (IF), and lacrimal glands (LGs) in staging patients with thyroid-associated ophthalmopathy (TAO).

METHODS

Two hundred patients with TAO (211 active and 189 inactive eyes) who underwent Dixon MRI for pretreatment evaluation were retrospectively enrolled and divided into training (169 active and 151 inactive eyes) and validation (42 active and 38 inactive eyes) cohorts. The maximum, mean, and minimum values of the signal intensity ratio (SIR), fat fraction (FF), and water fraction (WF) of EOMs, IF, and LGs were measured and compared between the active and inactive groups in the training cohort. Binary logistic regression analysis, receiver operating characteristic curve analysis, and the Delong test were used for further statistical analyses, as appropriate.

RESULTS

Compared with inactive TAOs, active TAOs demonstrated significantly greater EOM-SIRmax, EOM-SIRmean, EOM-SIRmin, IF-SIRmax, IF-SIRmean, LG-SIRmax, LG-SIRmean, EOM-WFmean, EOM-WFmin, IF-WFmax, IF-WFmean, and LG-WFmean and lower EOM-FFmax, EOM-FFmean, IF-FFmean, IF-FFmin, and LG-FFmean values (all p < 0.05). The EOM-SIRmean, LG-SIRmean, and LG-FFmean values were independently associated with active TAO (all p < 0.05). The combination of the EOM-SIRmean, LG-SIRmean, and LG-FFmean values showed better performance than the EOM-SIRmean value alone in staging TAO in both the training (AUC, 0.820 vs 0.793; p = 0.016) and validation (AUC, 0.751 vs 0.733, p = 0.341) cohorts.

CONCLUSION

Dixon MRI-based parameters of EOMs, LGs, and IF are useful for differentiating active from inactive TAO. The integration of multiple parameters can further improve staging performance.

CRITICAL RELEVANCE STATEMENT

In this study, the authors explored the combined value of quantitative parameters of EOMs, IF, and LGs derived from Dixon MRI in staging TAO patients, which can support the establishment of a proper therapeutic plan.

KEY POINTS

The quantitative parameters of EOMs, LGs, and IF are useful for staging TAO. The EOM-SIRmean, LG-SIRmean, and LG-FFmean values were found to independently correlate with active TAO. Joint evaluation of orbital tissue improved the ability to assess TAO activity.

MRI quantitative assessment of the effects of low-carbohydrate therapy on Hashimoto's thyroiditis

Objective

Hashimoto's thyroiditis is an inflammatory disease, and research suggests that a low-carbohydrate diet may have potential anti-inflammatory effects. This study aims to utilize Dixon-T2-weighted imaging (WI) sequence for a semi-quantitative assessment of the impact of a low-carbohydrate diet on the degree of thyroid inflammation in patients with Hashimoto's thyroiditis.

Methods

Forty patients with Hashimoto's thyroiditis were recruited for this study and randomly divided into two groups: one with a normal diet and the other with a low-carbohydrate diet. Antibodies against thyroid peroxidase (TPOAb) and thyroglobulin (TgAb) were measured for all participants. Additionally, thyroid water content was semi-quantitatively measured using Dixon-T2WI. The same tests and measurements were repeated for all participants after 6 months.

Results

After 6 months of a low-carbohydrate diet, patients with Hashimoto's thyroiditis showed a significant reduction in thyroid water content (94.84 ± 1.57% vs 93.07 ± 2.05%, P < 0.05). Concurrently, a decrease was observed in levels of TPOAb and TgAb (TPOAb: 211.30 (92.63-614.62) vs 89.45 (15.9-215.67); TgAb: 17.05 (1.47-81.64) vs 4.1 (0.51-19.42), P < 0.05). In contrast, there were no significant differences in thyroid water content or TPOAb and TgAb levels for patients with Hashimoto's thyroiditis following a normal diet after 6 months (P < 0.05).

Conclusion

Dixon-T2WI can quantitatively assess the degree of thyroid inflammation in patients with Hashimoto's thyroiditis. Following a low-carbohydrate diet intervention, there is a significant reduction in thyroid water content and a decrease in levels of TPOAb and TgAb. These results suggest that a low-carbohydrate diet may help alleviate inflammation in patients with Hashimoto's thyroiditis.

Deep-Learning Based Automated Segmentation and Quantitative Volumetric Analysis of Orbital Muscle and Fat for Diagnosis of Thyroid Eye Disease

Purpose

Thyroid eye disease (TED) is characterized by proliferation of orbital tissues and complicated by compressive optic neuropathy (CON). This study aims to utilize a deep-learning (DL)-based automated segmentation model to segment orbital muscle and fat volumes on computed tomography (CT) images and provide quantitative volumetric data and a machine learning (ML)-based classifier to distinguish between TED and TED with CON.

Methods

Subjects with TED who underwent clinical evaluation and orbital CT imaging were included. Patients with clinical features of CON were classified as having severe TED, and those without were classified as having mild TED. Normal subjects were used for controls. A U-Net DL-model was used for automatic segmentation of orbital muscle and fat volumes from orbital CTs, and ensemble of Random Forest Classifiers were used for volumetric analysis of muscle and fat.

Results

Two hundred eighty-one subjects were included in this study. Automatic segmentation of orbital tissues was performed. Dice coefficient was recorded to be 0.902 and 0.921 for muscle and fat volumes, respectively. Muscle volumes among normal, mild, and severe TED were found to be statistically different. A classification model utilizing volume data and limited patient data had an accuracy of 0.838 and an area under the curve (AUC) of 0.929 in predicting normal, mild TED, and severe TED.

Conclusions

DL-based automated segmentation of orbital images for patients with TED was found to be accurate and efficient. An ML-based classification model using volumetrics and metadata led to high diagnostic accuracy in distinguishing TED and TED with CON. By enabling rapid and precise volumetric assessment, this may be a useful tool in future clinical studies.

Computed tomography and magnetic resonance imaging approaches to Graves' ophthalmopathy: a narrative review

Graves' ophthalmopathy (GO) affects up to 50% of patients with Graves' disease (GD) ranging from mild ocular irritation to vision loss. The initial diagnosis is based on clinical findings and laboratory tests. Orbital imaging, such as magnetic resonance imaging (MRI) and computed tomography (CT), is an important tool to assess orbital changes, being also useful for understanding disease progression and surgical planning. In this narrative review, we included 92 studies published from 1979 to 2020 that used either MRI and/or CT to diagnose and investigate GO, proposing new methods and techniques. Most of the methods used still need to be corroborated and validated, and, despite the different methods and approaches for thyroid eye disease (TED) evaluation, there is still a lack of standardization of measurements and outcome reports; therefore, additional studies should be performed to include these methods in clinical practice, facilitating the diagnosis and approach for the treatment of TED.

Dixon-T2WI magnetic resonance imaging at 3 tesla outperforms conventional imaging for thyroid eye disease

OBJECTIVES

To determine the diagnostic performances of a single Dixon-T2-weighted imaging (WI) sequence compared to a conventional protocol including T1-, T2-, and fat-suppressed T2-weighted MRI at 3 T when assessing thyroid eye disease (TED).

MATERIALS AND METHODS

This IRB-approved prospective single-center study enrolled participants presenting with confirmed TED from April 2015 to October 2019. They underwent an MRI, including a conventional protocol and a Dixon-T2WI sequence. Two neuroradiologists, blinded to all data, read both datasets independently and randomly. They assessed the presence of extraocular muscle (EOM) inflammation, enlargement, fatty degeneration, or fibrosis as well as the presence of artifacts. The Wilcoxon signed-rank test was used.

RESULTS

Two hundred six participants were enrolled (135/206 [66%] women, 71/206 [34%] men, age 52.3 ± 13.2 years). Dixon-T2WI was significantly more likely to detect at least one inflamed EOM as compared to the conventional set (248/412 [60%] versus 228/412 [55%] eyes; (p = 0.02). Dixon-T2WI was more sensitive and specific than the conventional set for assessing muscular inflammation (100% versus 94.7% and 71.2% versus 68.5%, respectively). Dixon-T2WI was significantly less likely to show major or minor artifacts as compared to fat-suppressed T2WI (20/412 [5%] versus 109/412 [27%] eyes, p < 0.001, and 175/412 [42%] versus 257/412 [62%] eyes, p < 0.001). Confidence was significantly higher with Dixon-T2WI than with the conventional set (2.35 versus 2.24, p = 0.003).

CONCLUSION

Dixon-T2WI showed higher sensitivity and specificity and showed fewer artifacts than a conventional protocol when assessing thyroid eye disease, in addition to higher self-reported confidence.

KEY POINTS

• Dixon-T2WI has better sensitivity and specificity than a conventional protocol for assessing inflamed extraocular muscles in patients with thyroid eye disease. • Dixon-T2WI shows significantly fewer artifacts than fat-suppressed T2WI. • Dixon-T2WI is faster and is associated with significantly higher self-reported reader confidence as compared to a conventional protocol when assessing inflammatory extraocular muscles.

Identification of differentially expressed long non-coding RNAs and mRNAs in orbital adipose/connective tissue of thyroid-associated ophthalmopathy

Extracellular matrix remodeling and orbital adipose/connective tissue expansion are two key features of thyroid-associated ophthalmopathy (TAO). Recent studies have indicated the critical role of long non-coding RNAs (lncRNAs) in the pathogenesis of ocular disorders. However, little is known about the roles of lncRNAs in orbital adipose/connective tissue of TAO. In this study, the profiles of lncRNAs and mRNAs in the orbital adipose/connective tissue of TAO were identified by RNA sequencing. A total of 809 differential lncRNAs and 607 differential mRNAs were identified, among which 52 genes were found to be significantly related to the extracellular matrix. Co-expression network analysis suggested that lncRNAs might regulate extracellular matrix remodeling in orbital adipose/connective tissue of TAO. Additionally, the target genes of lncRNAs involved in the lipid metabolism and cytokine-cytokine receptor interaction were also identified. These results may provide potential regulatory mechanisms of lncRNAs in the orbital adipose/connective tissue of TAO.