Signal intensity, clinical activity and cross-sectional areas on MRI scans in thyroid eye disease

Application of Quantitative MRI in Thyroid Eye Disease: Imaging Techniques and Clinical Practices

Thyroid eye disease (TED) is a complex autoimmune disorder that impairs various orbital structures, leading to cosmetic damage and vision loss. Magnetic resonance imaging (MRI) is a fundamental diagnostic tool utilized in clinical settings of TED, for its accurate demonstration of orbital lesions and indication of disease conditions. The application of quantitative MRI has brought a new prospect to the management and research of TED, offering more detailed information on morphological and functional changes in the orbit. Therefore, many researchers concentrated on the implementation of different quantitative MRI techniques on TED for the exploration of clinical practices. Despite the abundance of studies utilizing quantitative MRI in TED, there remain considerable barriers and disputes on the best exploitation of this tool. This could possibly be attributed to the complexity of TED and the fast development of MRI techniques. It is necessary that clinical and radiological aspects of quantitative MRI in TED be better integrated into comprehensive insights. Hence, this review traces back 30 years of publications regarding quantitative MRI utilized in TED and elucidates this promising application in the facets of imaging techniques and clinical practices. We believe that a deeper understanding of the application of quantitative MRI in TED will enhance the efficacy of the multidisciplinary management of TED. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 3.

Euthyroid graves' ophthalmopathy in a Chinese population: A cross-sectional follow-up study

OBJECTIVES

A subtype of patients with thyroid eye disease (TED) were found to be euthyroid without prior thyroid dysfunction or treatment, known as Euthyroid Graves' Ophthalmopathy (EGO). We report the prevalence, clinical and serological phenotypes of EGO in a Chinese population.

METHODS

A cross-sectional follow-up study. Ethnic Chinese TED patients were managed at the Thyroid Eye Clinic(TEC), Prince of Wales Hospital and TEC, the Chinese University of Hong Kong between September 2007 and July 2021.

RESULTS

A total of 66 (5%) patients among the 1266 ethnic Han Chinese TED cohort were diagnosed as EGO, and 6 (9%)of them become dysthyroid over an average of 74-month follow-up. EGO patients were associated with a longer duration between onset of the symptoms to our first consultation (P < 0.0001), a higher male-to-female ratio (P = 0.0045) and a higher age of disease onset (P = 0.0092). Family history of thyroid disease was more common in TED patients (P = 0.0216) than in EGO patients. EGO patients were more likely to present unilaterally (P < 0.0001), and they have a larger difference in MRD1 (P < 0.0001), and extraocular motility (P < 0.0001) between the 2 eyes when compared to the TED patients. Notably, the extraocular motility restriction of the worst eye was more affected in EGO patients (P = 0.0113). The percentages of patients who received IVMP, ORT and emergency or elective surgeries(decompression or squint operation) between EGO and TED were similar.

CONCLUSIONS

Understanding the important clinical phenotypes of EGO may help the clinician to make the correct diagnosis. Further study to compare EGO and TED is warranted.

Performance of T2 mapping in the staging of Graves' ophthalmopathy based on different region of interest selection methods

BACKGROUND

Discriminating the stage of Graves' ophthalmopathy (GO) is crucial for clinical decision. Application of conventional T2-weighted imaging in the staging is still limited.

PURPOSE

To evaluate the performance of T2 mapping based on two different regions of interest (ROIs) for staging GO.

MATERIAL AND METHODS

In total, 56 GO patients were retrospectively enrolled and divided into two groups according to the clinical activity score (CAS). T2 relaxation time (T2RT) of extraocular muscle (EOM) on T2 mapping based on two different ROIs (T2RTROI-1: ROIs were drawn separately in the four EOMs; T2RTROI-2: ROI was drawn in the most inflamed EOM) was measured and compared between active and inactive groups.

RESULTS

Both T2RTROI-1 and T2RTROI-2 values in the active GO were significantly higher than those of inactive GO (P <0.001). T2RTROI-1 and T2RTROI-2 values were positively correlated with CAS (rs=0.73, 0.69; P <0.001). When the T2RTROI-1 value of 83.3 ms and T2RTROI-2 value of 106.3 ms were used as cutoff values for staging GO, respectively, the best results were obtained with areas under the curve (AUCs) of 0.822 and 0.827. There was no significant difference for AUCs between T2RTROI-1 and T2RTROI-2 (P = 0.751). Excellent and good inter-observer agreements were achieved in quantitative measurements for T2RTROI-1 and T2RTROI-2 values, respectively, with intraclass correlation coefficients of 0.954 and 0.882.

CONCLUSION

The T2RT values derived from two different ROIs were useful for assessment of disease activity. Taking reproducibility and diagnostic performance into consideration, T2RTROI-1 would be an ideal image biomarker for staging GO compared to T2RTROI-2.

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.

Quantitative assessment of extraocular muscles in Graves' ophthalmopathy using T1 mapping

OBJECTIVE

To evaluate the performance of T1 mapping in the characterization of extraocular muscles (EOMs) of Graves' ophthalmopathy (GO) patients and investigate its feasibility in assessing the response to glucocorticoid therapy in active GO patients.

METHODS

A total of 133 participants (78 active GO, 23 inactive GO, 18 Graves' disease (GD) patients, and 14 healthy volunteers) were consecutively enrolled from July 2018 to December 2020. Native T1 (nT1) and postcontrast T1 (cT1) values of EOMs were measured and compared. The variations in T1 mapping metrics of EOMs were compared pre/post glucocorticoid treatment in 23 follow-up active GO patients. Logistic regression analysis and receiver operating characteristic (ROC) curve analysis were performed.

RESULTS

The nT1 of EOMs in GO patients was higher than that in GD patients and healthy volunteers. The nT1 of superior rectus (SR) in active GO was higher than that in inactive GO patients, and it could be used as a potential marker of GO activity (OR: 1.003; 95% CI: 1.001, 1.004), with a diagnostic sensitivity of 86.3% and specificity of 43.7%. Meanwhile, the cT1 of SR, inferior rectus (IR), and medial rectus (MR) in inactive GO patients were higher than those in active GO patients. The nT1 of EOMs achieved sufficient diagnostic performance in evaluating the response to glucocorticoid therapy for follow-up active GO patients (AUC, 0.797; sensitivity, 71.9%; specificity, 85.7%).

CONCLUSIONS

T1 mapping could quantitatively assess the activity of GO and the response to glucocorticoid therapy in active GO patients and may even potentially reflect the fibrosis of EOMs.

CLINICAL RELEVANCE STATEMENT

T1 values can reflect the pathological status of the extraocular muscle. T1 mapping could help to quantitatively assess the clinical activity of GO and the response to glucocorticoid therapy in active GO patients.

KEY POINTS

• Graves' ophthalmopathy patients had greater nT1 of extraocular muscles than Graves' disease patients and healthy volunteers, and nT1 of the superior rectus could be a potential marker of Graves' ophthalmopathy activity. • The cT1 of extraocular muscles in inactive Graves' ophthalmopathy patients was higher than that in active Graves' ophthalmopathy patients, and it might be associated with muscle fibrosis. • nT1 of extraocular muscles could offer sufficient diagnostic performance in evaluating the response to glucocorticoid therapy for follow-up active Graves' ophthalmopathy patients.

Dysthyroid Optic Neuropathy

PURPOSE

Dysthyroid optic neuropathy (DON) is a sight-threatening complication of thyroid eye disease (TED). This review provides an overview of the epidemiology, pathogenesis, diagnosis, and current therapeutic options for DON.

METHODS

A literature review.

RESULTS

DON occurs in about 5% to 8% of TED patients. Compression of the optic nerve at the apex is the most widely accepted pathogenic mechanism. Excessive stretching of the nerve might play a role in a minority of cases. Increasing age, male gender, smoking, and diabetes mellitus have been identified as risk factors. Diagnosis of DON is based on a combination of ≥2 clinical findings, including decreased visual acuity, decreased color vision, relative afferent pupillary defect, visual field defects, or optic disc edema. Orbital imaging supports the diagnosis by confirming apical crowding or optic nerve stretching. DON should be promptly treated with high-dose intravenous glucocorticoids. Decompression surgery should be performed, but the response is incomplete. Radiotherapy might play a role in the prevention of DON development and may delay or avoid the need for surgery. The advent of new biologic-targeted agents provides an exciting new array of therapeutic options, though more research is needed to clarify the role of these medications in the management of DON.

CONCLUSIONS

Even with appropriate management, DON can result in irreversible loss of visual function. Prompt diagnosis and management are pivotal and require a multidisciplinary approach. Methylprednisolone infusions still represent first-line therapy, and surgical decompression is performed in cases of treatment failure. Biologics may play a role in the future.

Inter-observer Variability of Clinical Activity Score: Assessments in Patients With Thyroid Eye Disease

PURPOSE

Thyroid eye disease (TED) can be difficult to manage. The range of available treatments is expanding rapidly; however, cost is a concern and some patients do not respond. The Clinical Activity Score (CAS) was devised as a measure of disease activity and a potential predictor of response to anti-inflammatory treatment. Despite the widespread use of the CAS, inter-observer variability has not been investigated. The aim of the study was to determine the inter-observer variability of the CAS in patients with TED.

DESIGN

Prospective reliability analysis.

METHODS

Nine patients with a spectrum of clinical features of TED were assessed by 6 experienced observers on the same day. Agreement among the observers was analyzed using the Krippendorff alpha.

RESULTS

The Krippendorff alpha for the total CAS was 0.532 (95% CI = 0.199-0.665), whereas alpha values for the individual components of the CAS varied between 0.171 (CI = 0.000-0.334) for lid redness and 0.671 (CI = 0.294-1.000) for spontaneous pain. Assuming that a CAS value ≥3 implies suitability of the patient for anti-inflammatory treatment, the calculated Krippendorff alpha for agreement among assessors on whether treatment should be given or not given was 0.332 (95% CI = 0.0011-0.5862).

CONCLUSIONS

This study has shown unreliable inter-observer variability in total CAS and most individual CAS components, thus highlighting the need for improving the performance of the CAS or seeking other methods to assess activity.

Efficacy and Safety of 6-Weekly versus 12-Weekly Intravenous Methylprednisolone in Moderate-to-Severe Active Thyroid-Associated Ophthalmopathy

PURPOSE

To compare the efficacy and safety of 6-weekly and 12-weekly intravenous methylprednisolone (IVMP) regimens in moderate-to-severe, active thyroid-associated orbitopathy (TAO) patients.

BASIC PROCEDURES

Retrospective comparative study of patients who received IVMP between January 2011 and July 2021 at the Thyroid Eye Clinic, the Chinese University of Hong Kong. Outcome measures included the 7-item clinical activity score (CAS), exophthalmos, extraocular muscle motility (EOMy), marginal reflex distance (MRD), best corrected visual acuity (BCVA), intraocular pressure (IOP), the requirement of additional treatment, and complications.

MAIN FINDINGS

A total of 65 (63% (41/65) females) moderate-to-severe, active TAO patients aged 50 ± 13 (25-74) years received 6-weekly (n = 22) or 12-weekly (n = 43) IVMP. Sex, age, smoking status, and Graves' disease status were comparable in the two groups (all p > 0.05). CAS at week 6 (p = 0.0279), 12 (p = 0.00228), and 52 (p = 0.0228) were lower at each time for the 12-weekly group. Exophthalmos improved more at week 6 (p = 0.0453) and 12 (p = 0.0347) in the 12-weekly group. The improvement of diplopia, MRD1, MRD2, and EOMy were comparable between the two groups. More patients in the 6-weekly group (p = 0.00169) required additional treatments including IVMP+/-ORT. Patients in the 6-weekly group who did not require additional treatment had a lower presenting CAS (p = 0.0193) than those who required additional treatment. The total numbers of adverse events were comparable between the two groups.

Computed tomography and magnetic resonance imaging of the orbit in the diagnosis and treatment of thyroid-associated orbitopathy - experience from practice. A Review

The purpose is to acquaint readers with the contribution of imaging methods (IMs) of the orbit, specifically computed tomography (CT) and magnetic resonance imaging (MRI), in the diagnosis of thyroid-associated orbitopathy (TAO). Methods: IMs of the orbit are an indispensable accessory in the clinical and laboratory examination of TAO patients. The most frequently used and probably most accessible method is an ultrasound examination of the orbit (US), which, however, has a number of limitations. Other methods are CT and MRI. Based on the published knowledge implemented in our practice and several years of experience with the diagnosis and treatment of TAO patients, we would like to point out the benefits of CT and MRI in the given indications: visualisation of the extraocular muscles, assessment of disease activity, diagnosis of dysthyroid optic neuropathy and differential diagnosis of other pathologies in the orbit. Our recommendation for an ideal MRI protocol for disease activity evaluation is also included.  Conclusion: IMs play an irreplaceable role not only in the early diagnosis of TAO, but also in the monitoring of the disease and the response to the applied treatment. When choosing a suitable IM for this diagnosis, a number of factors must always be taken into account; not only availability, cost and burden for the patient, but especially the sensitivity and specificity of the given method for the diagnosis of TAO.

Turbo Gradient and Spin-Echo BLADE-DWI for Extraocular Muscles in Thyroid-Associated Ophthalmopathy

Purpose: To investigate feasibility and diagnostic performance of turbo gradient and spin-echo BLADE (proprietary name for Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction [PROPELLER] in Siemens MR systems)-diffusion weighted imaging (TGSE-BLADE-DWI) for depicting extraocular muscle (EOM) involvement and activity in thyroid-associated ophthalmopathy (TAO), and to compare TGSE-BLADE-DWI with readout-segmented echo-planar imaging (RESOLVE). Materials and methods: Thirty-five patients with identified TAO underwent the two DWI scans. Two radiologists visually scored the image quality of the two DWIs with respect to the susceptibility artifacts and geometric distortions on a three-point scale. The maximum size (Size_max) of EOMs and corresponding ADCs (cADCs) of each patient were compared between the active and inactive phases. The clinical activity score (CAS) was used as a reference to assess the diagnostic performance of EOM ADCs for grading TAO activity. ROC analysis, Pearson correlation, and Wilcoxon signed-rank test were used for statistical analyses. Results: For scores of EOMs, the image quality of TGSE-BLADE-DWI was significantly higher than that of RESOLVE. There were no statistically significant differences between the AUCs of the two DWIs, Size_max, or cADCs between the active and inactive phases. TGSE-BLADE-DWI ADCs were significantly higher than the RESOLVE ADCs in the right superior rectus, right lateral rectus, left superior rectus, and left inferior rectus. There were no statistically significant correlations between the cADC or Size_max, and CAS. The highest AUC was 0.697 for RESOLVE and 0.657 for TGSE-BLADE-DWI. The best performing ADC threshold was 1.85 × 10^-3 mm²/s with 85.7% sensitivity, 58.8% specificity and 66.67% accuracy for RESOLVE and 1.99 × 10^-3 mm²/s with 79.0% sensitivity, and 55.6% specificity and 65.27% accuracy for TGSE-BLADE-DWI. Conclusion: Compared to RESOLVE, TGSE-BLADE-DWI provided improved image quality with fewer susceptibility artifacts and geometric distortions for EOM visualization and showed an equivalent performance in detecting active TAO.

MRI in the assessment of thyroid-associated orbitopathy activity

Management of patients with thyroid-associated orbitopathy (also called Graves' disease) is dependent on the assessment of the disease activity. Evaluation of disease activity is based on ophthalmological examination. Magnetic resonance imaging (MRI) is an auxiliary method that may help quantify the activity and is also helpful in obtaining anatomical information concerning muscle thickness, exophthalmos, or optic neuropathy. We present a review of MRI techniques of the orbits with emphasis on the evaluation of disease activity. The most convincing seems to be the group of T2-weighted techniques such as conventional T2 weighting, T2 relaxometry, and T2 mapping. Dynamic contrast-enhanced MRI is another promising method.

Extraocular muscle enlargement

Extraocular muscle enlargement can occur secondary to a range of orbital and systemic diseases. Although the most common cause of extraocular muscle enlargement is thyroid eye disease, a range of other inflammatory, infective, neoplastic, and vascular conditions can alter the size and shape of the extraocular muscles. Imaging with computed tomography and magnetic resonance imaging plays an essential role in the workup of these conditions. This article provides an image-rich review of the wide range of pathology that can cause enlargement of the extraocular muscles.

Insights into Current Management Strategies for Dysthyroid Optic Neuropathy: A Review

Dysthyroid optic neuropathy (DON) is a potentially sight-threatening eye disease associated with Graves’ orbitopathy (GO). DON is not common in GO patients, reportedly occurring in only about 5% of patients. The pathogenesis of severe DON is considered to involve both muscular nerve strangulation and impaired blood flow. There is some objective grading of physical examination findings and the severity of GO, including a clinical activity score (CAS) and EUropean Group On Graves’ Orbitopathy (EUGOGO), but no specialized protocol completely characterizes DON. Most clinicians have decided that the combination of clinical activity findings, including visual acuity, color vision, and central critical fusion frequency, and radiological findings, including magnetic resonance imaging (MRI), can be used to diagnose DON. MRI has the most useful findings, with T2-weighted and fat-suppressed images using short-tau inversion recovery (STIR) sequences enabling detection of extraocular changes including muscle and/orbital fat tissue swelling and inflammation and, therefore, disease activity. The first-choice treatment for DON is intravenous administration of steroids, with or without radiotherapy. Unfortunately, refractoriness to this medical treatment may indicate the need for immediate orbital decompression within 2 weeks. Especially in the acute phase of DON, thyroid function is often unstable, and the surgeon must always assume the risk of general anesthesia and intra- and post-operative management. In addition, there are currently many possible therapeutic options, including molecular-targeted drugs. The early introduction and combination of these immunomodulators, including Janus kinase inhibitors and insulin-like growth factor-1 receptor antibody (teprotumumab), may be effective for GO with DON. However, this is still under investigation, and the number of case reports is small. It is possible that these options could reduce systemic adverse events due to unfocused glucocorticoid administration. The pathophysiology of DON is not yet fully understood, and further studies of its treatment and long-term visual function prognosis are needed.

T2 -Weighted MR Imaging-Derived Radiomics for Pretreatment Determination of Therapeutic Response to Glucocorticoid in Patients With Thyroid-Associated Ophthalmopathy: Comparison With Semiquantitative Evaluation

BACKGROUND

MR imaging has been applied to determine therapeutic response to glucocorticoid (GC) before treatment in thyroid-associated ophthalmopathy (TAO), while the performance was still poor.

PURPOSE

To investigate the value of T₂ -weighted imaging (T₂ WI)-derived radiomics for pretreatment determination of therapeutic response to GC in TAO patients, and compare its diagnostic performance with that of semiquantitative parameters.

STUDY TYPE

Retrospective.

POPULATION

A total of 110 patients (49 ± 12 years; male/female, n = 48/62; responsive/unresponsive, n = 62/48), divided into training (n = 78) and validation (n = 32) cohorts.

FIELD STRENGTH/SEQUENCE

3.0 T, T₂ -weighted fast spin echo.

ASSESSMENT

W.C. and H.H. (6 and 10 years of experience, respectively) performed the measurements. Maximum, mean, and minimum signal intensity ratios (SIRs) of extraocular muscle (EOM) bellies were collected to construct a semiquantitative imaging model. Radiomics features from volumes of interest covering EOM bellies were extracted and three machine learning-based (logistic regression [LR]; decision tree [DT]; support vector machine [SVM]) models were built.

STATISTICAL TESTS

The diagnostic performances of models were evaluated using receiver operating characteristic curve analyses, and compared using DeLong test. Two-sided P < 0.05 was considered statistically significant.

RESULTS

The responsive group showed higher minimum signal intensity ratio (SIR_min ) of EOMs than the unresponsive group (training: 1.46 ± 0.34 vs. 1.18 ± 0.39; validation: 1.44 ± 0.33 vs. 1.19 ± 0.20). In both cohorts, LR-based radiomics model demonstrated good diagnostic performance (area under the curve [AUC] = 0.968, 0.916), followed by DT-based (AUC = 0.933, 0.857) and SVM-based models (AUC = 0.919, 0.855). All three radiomics models outperformed semiquantitative imaging model (SIR_min : AUC = 0.805) in training cohort. In validation cohort, only LR-based radiomics model outperformed that of SIR_min (AUC = 0.745). The nomogram integrating LR-based radiomics signature and disease duration further elevated the diagnostic performance in validation cohort (AUC: 0.952 vs. 0.916, P = 0.063).

DATA CONCLUSION

T₂ WI-derived radiomics of EOMs, together with disease duration, provides a promising noninvasive approach for determining therapeutic response before GC administration in TAO patients.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 4.

Current insights of applying MRI in Graves' ophthalmopathy

Graves' ophthalmopathy (GO) is an autoimmune disease related to Grave's disease (GD). The therapeutic strategies for GO patients are based on precise assessment of the activity and severity of the disease. However, the current assessment systems require development to accommodate updates in treatment protocols. As an important adjunct examination, magnetic resonance imaging (MRI) can help physicians evaluate GO more accurately. With the continuous updating of MRI technology and the deepening understanding of GO, the assessment of this disease by MRI has gone through a stage from qualitative to precise quantification, making it possible for clinicians to monitor the microstructural changes behind the eyeball and better integrate clinical manifestations with pathology. In this review, we use orbital structures as a classification to combine pathological changes with MRI features. We also review some MRI techniques applied to GO clinical practice, such as disease classification and regions of interest selection.

Role of Structural, Metabolic, and Functional MRI in Monitoring Visual System Impairment and Recovery

The visual system, consisting of the eyes and the visual pathways of the brain, receives and interprets light from the environment so that we can perceive the world around us. A wide variety of disorders can affect human vision, ranging from ocular to neurologic to systemic in nature. While other noninvasive imaging techniques such as optical coherence tomography and ultrasound can image particular sections of the visual system, magnetic resonance imaging (MRI) offers high resolution without depth limitations. MRI also gives superior soft-tissue contrast throughout the entire pathway compared to computed tomography. By leveraging different imaging sequences, MRI is uniquely capable of unveiling the intricate processes of ocular anatomy, tissue physiology, and neurological function in the human visual system from the microscopic to macroscopic levels. In this review we discuss how structural, metabolic, and functional MRI can be used in the clinical assessment of normal and pathologic states in the anatomic structures of the visual system, including the eyes, optic nerves, optic chiasm, optic tracts, visual brain nuclei, optic radiations, and visual cortical areas. We detail a selection of recent clinical applications of MRI at each position along the visual pathways, including the evaluation of pathology, plasticity, and the potential for restoration, as well as its limitations and key areas of ongoing exploration. Our discussion of the current and future developments in MR ocular and neuroimaging highlights its potential impact on our ability to understand visual function in new detail and to improve our protection and treatment of anatomic structures that are integral to this fundamental sensory system. LEVEL OF EVIDENCE 3:   TECHNICAL EFFICACY STAGE 3:  .

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

OBJECTIVE

Quantitatively staging TAO using MRI remains limited. Our study aims to identify the cut-off signal intensity value for staging TAO using STIR sequence scan.

METHODS

Between 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.

RESULTS

Compared 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.

CONCLUSIONS

the 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.

Magnetic resonance imaging of the orbit, Part 2: Characterization of orbital pathologies

In this article we focus on a systematic approach to assess common orbital lesions on magnetic resonance imaging (MRI). The identification of the probable compartment or structure of origin helps narrow the differential diagnosis of a lesion. Analyzing the morphology, appearance, and signal intensity on various sequences, the pattern, and degree of contrast enhancement are key to characterize lesions on MRI. Imaging features suggesting cellularity and vascularity can also be determined to help plan for biopsy or surgery of these lesions. MRI can also distinguish active from chronic disease in certain pathologies and aids in selecting appropriate medical management. MRI may thus serve as a diagnostic tool and help in guiding therapeutic strategies and posttreatment follow-up.

Advances in magnetic resonance imaging of orbital disease

Magnetic resonance imaging (MRI) is increasingly used by the orbital surgeon to aid in the diagnosis, surgical planning, and monitoring of orbital disease. MRI provides superior soft tissue detail compared with computed tomography or ultrasound, and advancing techniques enhance its ability to highlight abnormal orbital pathology. Diffusion-weighted imaging is a specialized technique that uses water molecule diffusion patterns in tissue to generate contrast signals and can help distinguish malignant from benign lesions. Steady-state free precession sequences such as Constructive Interference in Steady-State (CISS) and Fast Imaging Employing Steady-state Acquisition (FIESTA) generate highly detailed, 3-dimensional reconstructed images and are particularly useful in distinguishing structures adjacent to cerebral spinal fluid. Magnetic resonance angiography can be used to characterize vascular lesions within the orbit. New developments in magnetic field strength as well as the use of orbital surface coils achieve increasingly improved imaging resolution.

Clinical and Radiological Findings in Patients with Newly Diagnosed Graves' Ophthalmopathy

BACKGROUND

Graves' ophthalmopathy is the most common extrathyroidal manifestation of Graves' disease. The objective of this study was to investigate the clinical ophthalmological and MRI findings in newly diagnosed Graves' ophthalmopathy.

METHODS

This study included 36 newly diagnosed Graves' disease patients and 23 control participants. Patients and control participants underwent detailed ophthalmologic examination. In addition, all subjects underwent orbital MRI examination; and sizes, cross-sectional areas, and signal intensities of extraocular muscles were also measured.

RESULTS

Based on MRI measurements, the mean exophthalmos in the left eye was significantly higher in the patient group when compared to those of controls (2.04 ± 0.29 vs. 1.85 ± 0.15 cm, p = 0.003). The mean long diameter of inferior oblique muscle in both the right and left eyes were significantly shorter in patients when compared to those of controls (p = 0.001, p = 0.002, resp.); however, the mean long diameter of superior oblique in the left eye was longer in patients than those of controls (p = 0.001). Patients had significantly higher superior oblique muscle signal intensity than those of controls in the right eye (p = 0.01). There was no significant difference for the other parameters between the patient and control groups.

CONCLUSION

Our findings suggest that there is no obvious change in MRI examination despite clinical ophthalmological findings in patients with newly diagnosed Graves' ophthalmopathy. Unnecessary MRI examination should be avoided in this patient group due to unsatisfactory cost-effectiveness.

Usefulness of two-point Dixon T2-weighted imaging in thyroid-associated ophthalmopathy: comparison with conventional fat saturation imaging in fat suppression quality and staging performance

OBJECTIVE

To compare the two-point Dixon T₂ weighted imaging (T₂WI) with conventional fat-sat T₂WI in fat suppression (FS) quality and staging performance for patients with TAO.

METHODS

We enrolled 37 thyroid-associated ophthalmopathy (TAO) patients and 15 healthy controls who underwent both coronal two-point Dixon and fat-sat T₂WI. Qualitative (overall imaging quality, FS uniformity) and quantitative [signal intensity ratio of extraocular muscle (EOM-SIR)] parameters were assessed between the two-point Dixon T₂WI and fat-sat T₂WI. Additionally, water fraction of intraorbital fat (IF-WF) was measured on Dixon image. Dixon-EOM-SIR, Fat-sat-EOM-SIR and Dixon-IF-WF values were compared between active and inactive TAO groups, and the diagnostic efficiency for the active phase were evaluated.

RESULTS

Two-point Dixon T₂WI showed significantly higher overall image quality score, FS uniformity score as well as EOM-SIR value than fat-sat T₂WI in both TAO and control groups (all p < 0.05). Active TAOs had significantly higher Dixon-EOM-SIR (p < 0.001), Fat-sat-EOM-SIR (p < 0.001) and Dixon-IF-WF (p = 0.001) than inactive TAOs. ROC curves analyses indicated that Dixon-EOM-SIR ≥3.32 alone demonstrated the highest staging sensitivity (75.0%). When integrating Dixon-EOM-SIR ≥3.32 and Dixon-IF-WF ≥0.09, improved staging efficiency and specificity could be achieved (area under the curve, 0.872; specificity, 97.1%).

CONCLUSION

Compared with conventional fat-sat technique, two-point Dixon T₂WI offers better image quality, as well as improved staging sensitivity and specificity for TAO. Dixon T₂WI is suggested to be used to evaluate the patients with TAO in clinical practice.

ADVANCES IN KNOWLEDGE

Two-point Dixon T₂WI offers better image quality than fat-sat T₂WI. Dixon-EOM-SIR alone demonstrated the highest staging sensitivity. Combining with Dixon-IF-WF showed improved staging efficiency and specificity. Dixon T₂WI is suggested to be used to evaluate TAO patients in clinical practice.

Application of Magnetic Resonance Imaging in the Evaluation of Disease Activity in Graves' Ophthalmopathy

OBJECTIVE

To evaluate magnetic resonance imaging parameters, T2 signal intensity ratios (SIRs), and normalized apparent diffusion coefficients (n-ADC) of the extraocular muscles (EOMs) in the identification of different stages of Graves' ophthalmopathy (GO) and to find out the correlation of T2-SIRs and n-ADC values with disease changes after anti-inflammatory treatment.

METHODS

Altogether, 43 patients (86 orbits) were enrolled and classified into "active" or "inactive" stages by clinical activity score (CAS). Twenty-three (53.5%) patients received anti-inflammatory treatment and underwent a follow-up evaluation. Fifteen age- and gender-matched control participants (30 orbits) were included. T2-SIRs and n-ADC values of EOMs were calculated among GO and healthy controls and were correlated with CAS. Changes in these parameters were also evaluated before and after anti-inflammatory treatment.

RESULTS

Mean T2-SIRs and n-ADC values were both significantly higher in GO patients than in controls and higher in active GO than in inactive GO. In the inactive stage, n-ADC values of inferior rectus muscles were still higher than those in healthy controls. Both T2-SIRs and n-ADC values decreased after intravenous steroid pulse therapy. The cutoff value of pretreatment n-ADC was 1.780 to detect stages with specificity of 93.7% and sensitivity of 48.3% (P = .035).

CONCLUSION

T2-SIRs and n-ADC values are valuable magnetic resonance imaging indicators of the inflammatory activity in GO by detecting involvement of EOMs. They are also ideal tools to monitor the efficacy of anti-inflammatory treatment in patients with active stage GO. n-ADC values, when combined with CAS, can be promising predictive factors in the detection of stages of diseases.

Histogram analysis of T2 mapping for detecting early involvement of extraocular muscles in patients with thyroid-associated ophthalmopathy

Using histogram analysis of T2 values to detect early involvement of extraocular muscles (EOMs) in patients with thyroid-associated ophthalmopathy (TAO). Five EOMs of each orbit were analyzed for 45 TAO patients and 22 healthy controls (HCs). Patients’ EOMs were grouped into involved or normal-appearing EOMs (NAEOMs). Histogram parameters and signal intensity ratios (SIRs) of EOMs were compared; receiver operating characteristic (ROC) curve analysis was performed to differentiate NAEOMs from EOMs of HCs. 24 patients were reassessed following immunosuppressive treatment. For SIRs, involved muscles showed higher values than those of NAEOMs and HCs (p < 0.05); there were no differences between NAEOMs and HCs (p = 0.26). Parameters of involved muscles showed no different from those of NAEOMs excluding 25th, 50th percentiles, and standard deviation (SD) (p < 0.05). NAEOMs displayed higher values of 90th, 95th percentiles, SD, skewness, inhomogeneity, and entropy than HCs (p < 0.05). ROC curve analysis of entropy yielded the best area under the ROC curve (AUC; 0.816) for differentiating NAEOMs and HCs. After treatment, histogram parameters including 5th, 75th, 90th, and 95th percentiles, SD, kurtosis, inhomogeneity, and entropy were reduced in NAEOMs (p < 0.05). T2 histogram analysis could detect early involvement of EOMs in TAO prior to detection on conventional orbital MRI.

Artificial intelligence CT screening model for thyroid-associated ophthalmopathy and tests under clinical conditions

PURPOSE

Thyroid-associated ophthalmopathy (TAO) might lead to blindness and orbital deformity. The early diagnosis and treatment are conducive to control disease progression, but currently, there is no effective screening method. The present study aimed to introduce an artificial intelligence (AI) model for screening and testing the model with TAO patients under clinical conditions.

METHODS

A total of 1435 computed tomography (CT) scans were obtained from the hospital. These CT scans were preprocessed by resampling and extracting the region of interest. CT from 193 TAO patients and 715 healthy individuals were adopted for three-dimensional (3D)-ResNet model training, and 49 TAO patients and 178 healthy people were adopted for external verification. Data from 150 TAO patients and 150 healthy people were utilized for application tests under clinical conditions, including non-inferiority experiments and diagnostic tests, respectively.

RESULTS

In the external verification of the model, the area under the receiver operating characteristic (ROC) curve (AUC) was 0.919, indicating a satisfactory classification effect. The accuracy, sensitivity, and specificity were 0.87, 088, and 0.85, respectively. In non-inferiority experiments: the accuracy was 85.67% in the AI group and 84.33% in the resident group. The model passed both non-inferiority experiments (p = 0.001) and diagnostic test (the AI group sensitivity = 0.87 and specificity = 0.84%).

CONCLUSIONS

A promising orbital CT-based TAO screening AI model was established and passed application tests under clinical conditions. This may provide a new TAO screening tool with further validation.

Utility of T2 mapping in the staging of thyroid-associated ophthalmopathy: efficiency of region of interest selection methods

BACKGROUND

Discriminating the stage of thyroid-associated ophthalmopathy (TAO) is crucial for the treatment strategy and prognosis prediction. Utility of conventional magnetic resonance imaging in the disease staging is limited.

PURPOSE

To investigate the performance of T2 mapping based on different region of interest (ROI) selection methods in the staging of TAO.

MATERIAL AND METHODS

Thirty-two patients with TAO were retrospectively enrolled. Two radiologists independently measured the T2 relaxation time (T2RT) of extraocular muscles using two different ROIs (hotspot [ROI_HS]: T2RT-hot; single-slice [ROI_SS]: T2RT-mean, T2RT-max, T2RT-min). Independent-samples t test, Wilcoxon signed rank test, Spearman correlation analysis, receiver operating characteristic (ROC) curves analyses, multiple ROC comparisons, and intra-class correlation coefficient (ICC) were used for statistical analyses.

RESULTS

No significant difference was found in the measuring time between ROI_HS and ROI_SS methods (P = 0.066). T2RT-mean demonstrated the highest ICC for measurement, followed by T2RT-max and T2RT-min, and T2RT-hot showed the poorest reproducibility. Active TAOs showed significantly higher values for all the T2RTs than inactive mimics (all P < 0.001). Significant positive correlations were found between T2RTs and CAS (all P < 0.005). T2RT-hot and T2RT-max showed significantly higher areas under the curve than that of T2RT-mean (P = 0.013 and 0.024, respectively), while the difference between T2RT-hot and T2RT-max was not significant (P = 0.970).

CONCLUSION

The T2RTs derived from both ROI selection methods could be useful for the staging of TAO. The results of measuring time, reproducibility, and diagnostic performance suggest that T2RT-max would be the optimal indicator for staging.

Predicting the response to glucocorticoid therapy in thyroid-associated ophthalmopathy: mobilizing structural MRI-based quantitative measurements of orbital tissues

PURPOSE

We aimed to evaluate the performance of structural magnetic resonance imaging (MRI)-based quantitative measurements at extraocular muscle (EOM), orbital fat (OF), and especially lacrimal gland (LG) in predicting response to glucocorticoid (GC) in patients with active and moderate-severe thyroid-associated ophthalmopathy (TAO).

METHODS

Forty-seven active and moderate-severe TAOs (responsive group, 29 patients and 58 eyes; unresponsive group, 18 patients and 36 eyes) were enrolled. Pretreatment MRI-based parameters of EOM, OF, and LG, and clinical factors were retrospectively collected and compared between two groups. Logistic regression and receiver operating characteristic curve analyses were used to assess the predictive value of identified independent variables.

RESULTS

Responsive group showed significantly higher minimum signal intensity ratio of EOM (EOM-SIR_min) (p < 0.001), higher EOM-SIR_mean (p = 0.034), higher LG herniation (LGH) (p = 0.019), lower OF thickness (OFT) (p = 0.017), higher LGH/OFT ratio (p = 0.001), and shorter disease duration (p = 0.004) than unresponsive group. Multivariate analysis showed that EOM-SIR_min, LGH/OFT ratio, and disease duration were independent predictors for responsive TAOs (all p < 0.05). Integration of three independent predictors demonstrated optimal predictive efficiency (area under curve, 0.829). Combining EOM-SIR_min ≥1.43 and LGH/OFT ratio ≥1.65, optimal predictive specificity (94.4%) could be obtained, while optimal predictive sensitivity (82.8%) was achieved when integrating disease duration ≤3.5 and LGH/OFT ratio ≥1.65.

CONCLUSIONS

Structural MRI-based quantitative measurements at EOM, OF, and LG, specially EOM-SIR_min and LGH/OFT ratio, together with disease duration, may serve as promising markers to predict response to GC in patients with active and moderate-severe TAO.

Optic neuropathy and exophthalmos edematous: symptom or complication?

The article is concentrated on the mechanism of the development of optic neuropathy in patients with edematous proptosis one of the clinical forms of endocrine ophthalmopathy. All probable options for the pathogenesis of optic neuropathy are reviewed in detail: increased intraorbital pressure, compression of the optic nerve by enlarged extraocular muscles, the formation of the apical syndrome with compression of the optic nerve in the zone of the Zinns ring, an increase in the volume of orbital fat, tension of the optic nerve by an anteriorly shifted eye (exophthalmos), and arterial blood flow impairment in the ophthalmic artery, impaired venous blood flow in the orbit. Based on 103 follow-ups of patients with edematous proptosis and optic neuropathy (68 of them had initial optical neuropathy), the author offers her concept of the pathogenesis of optic neuropathy in patients with sub- and decompensated edematous proptosis, considering optic neuropathy as a complication of endocrine ophthalmopathy. The signs of optical neuropathy in the initial stage of its development are conceived.

Radiological Staging of Thyroid-Associated Ophthalmopathy: Comparison of T1 Mapping with Conventional MRI

BACKGROUND

Accurate staging of patients with thyroid-associated ophthalmopathy (TAO) is crucial for clinical decision. Full cognition of pathologic changes and staging TAO using conventional T2-weighted imaging is still limited.

PURPOSE

To investigate the feasibility of using T1 mapping to evaluate changes of extraocular muscles (EOMs) in TAO patients, as well as to compare T1 mapping and conventional T2-weighted imaging in staging TAO.

MATERIALS AND METHODS

Forty TAO patients were retrospectively enrolled. "Hot spot" and "cold spot" T1 relaxation times (T1RT_HS and T1RT_CS) of EOMs, as well as conventionally applied highest signal intensity ratio (SIR) of EOMs, were measured and compared between active and inactive groups.

RESULTS

T1RT_CS and SIR were significantly higher in active TAOs than in the inactive ones (P < 0.001), while T1RT_HS was not (P=0.093). Meanwhile, T1RT_CS and SIR were positively correlated with clinical activity score (r = 0.489, 0.540; P < 0.001). TIRT_CS and SIR showed no significant area under curve for staging TAO (0.830 vs. 0.852; P=0.748). T1RT_CS ≥ 1000 alone showed optimal staging specificity (90.0%), while integration of T1RT_CS ≥ 1000 and SIR ≥ 2.9 demonstrated optimal staging efficiency and sensitivity (area under curve, 0.900; sensitivity, 86.0%).

CONCLUSIONS

Our findings suggest that the T1-mapping technique holds the potency to be utilized in TAO. The derived T1RT_CS of EOMs, which may be associated with fat infiltration, could be a useful biomarker to stage the disease, serving added efficiency, sensitivity, and specificity to single usage of conventional SIR.

ROLE OF MAGNETIC RESONANCE IMAGING IN THE ASSESSMENT OF ACTIVE THYROID-ASSOCIATED OPHTHALMOPATHY PATIENTS WITH LONG DISEASE DURATION

Objective: In thyroid-associated ophthalmopathy (TAO), long disease duration is negatively correlated with the response to immunosuppression treatment. The current treatment decision-making process does not involve magnetic resonance imaging (MRI); thus, we investigated the predictive value of MRI parameters for the immunosuppressive response in active moderate to severe TAO patients with different disease durations. Methods: We retrospectively analyzed the baseline MRI parameters of active TAO patients treated with guideline-recommended weekly glucocorticoid therapy in our center. Data were stratified by the quartile of disease duration. The signal intensity ratio (SIR) of T2-weighted images was used to describe the activity of extraocular muscles (EOMs). Results: Compared to the lowest quartile of disease duration, SIR values of EOMs were significantly lower in quartile 3 (Q3) and quartile 4 (Q4). Meanwhile, the clinical activity score (CAS) curve did not change in parallel and was not correlated with the SIR curve. In the highest quartile of disease duration, nonresponders had significantly lower SIR values of the most inflamed muscle (P = .03) and the medial rectus (P = .004) than did the responders, while no such significance was observed in patients within the lower 3 quartiles. A multivariable predictive model (including CAS, TAO duration, and SIR value) was established in each quartile. The fit of the model was better than CAS with regard to prognostic prediction and showed a high positive predictive value (Model 1: 86.67%; Model 2: 92.86%) and negative predictive value (Model 1: 88.89%; Model 2: 90%) in the top quartile. Conclusion: The anterior manifestation assessed by CAS is not always consistent with retro-orbital activity in long-term TAO patients. CAS is sufficient to reflect disease activity in short-term TAO patients. The supplementation of CAS with orbital MRI would be valuable in selecting appropriate active patients with a long disease duration. Abbreviations: AUC = area under the curve; CAS = clinical activity score; EOM = extraocular muscle; FT3 = free triiodothyronine; FT4 = free thyroxine; GC = glucocorticoid; ivGC = intravenous glucocorticoids; MRI = magnetic resonance imaging; NPV = negative predictive value; PPV = positive predictive value; SIR = signal intensity ratio; TAO = thyroid-associated ophthalmopathy; TRAb = thyroid-stimulating hormone receptor antibody; TSH = thyroid-stimulating hormone.

Improvement of the MRI and clinical features of Asian Graves' ophthalmopathy by radiation therapy with steroids

PURPOSE

To evaluate the effectiveness of radiation therapy and steroids for Asian patients with Graves' ophthalmopathy using the clinical activity score (CAS), and changes in external ocular muscles and eye proptosis determined by magnetic resonance imaging (MRI).

MATERIALS AND METHODS

We retrospectively reviewed 48 patients who received combined orbital radiation and systemic glucocorticoids in our hospital. MRI was performed both before and 1 month after treatment in all patients. We calculated the areas of five extraocular muscles and the degree of proptosis on transverse sections, and we evaluated the activity of the disease using CAS before and 1 month after treatment and toxicity.

RESULTS

The areas of external ocular muscles, the length of eye prominence and CAS were significantly improved by the combination of orbital radiation and steroids. The change in the area of the medial rectus muscle had a significant correlation with the change in CAS (P < 0.05). Graves' ophthalmopathy progressed again in 4 of the 48 patients; however, there were no patients with serious side effects in a median observation period of 41.5 months.

CONCLUSION

Treatment with the combination of orbital radiation and systemic glucocorticoids is subjectively and objectively effective for Asian Graves' ophthalmopathy without severe toxicity.

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

Background and Purpose

To compare orbital quantitative data obtained by fast spin-echo iterative decomposition of water and fat with echo asymmetry and least-squares estimation (FSE-IDEAL) in patients with thyroid-associated orbitopathy (TAO) and healthy controls and to investigate the characteristics of these data in TAO patients.

Materials and Methods

Twenty-two TAO patients (4 males and 18 females; median age 51.0 years) and 22 healthy subjects (5 males and 17 females; median age 50.5 years) underwent orbital T2-weighted FSE-IDEAL. The water fraction in orbital fat was defined as the signal intensity (SI) water / (SI water + SI fat). The orbital fat volume was measured on fat images. The degree of proptosis was evaluated using in-phase imaging. Mann–Whitney U test was used to compare these quantitative data in the two groups. In TAO patients we ascertained the correlation among these values with the Spearman's rank correlation coefficient.

Results

In TAO patients, the water fraction (right and left, p = 0.04), fat volume (right and left, p = 0.03) and degree of proptosis (right and left, p < 0.01) were higher than in the controls. In TAO patients, only the water fraction and the fat volume of left orbit showed negative correlation (p = 0.01).

Conclusion

The water fraction of orbital fat, the orbital fat volume and the degree of proptosis obtained with FSE-IDEAL were higher in TAO patients than in the controls. The water fraction was a new parameter for differentiating between TAO patients and healthy subjects.

T2-relaxation mapping and fat fraction assessment to objectively quantify clinical activity in thyroid eye disease: an initial feasibility study

Imaging in thyroid eye disease (TED) is used to exclude other diagnoses, assess for apical crowding and plan surgery. But to quantify TED activity objectively, subjective clinical scoring assessments remain the norm. Magnetic resonance imaging (MRI) T2-relaxation times correlate with extra-ocular muscle (EOM) inflammation, but are confounded by signal from fat. We investigated whether T2-relaxation mapping in combination with fat fraction (FF) measurements could quantify disease activity in EOMs objectively. Sixty-two TED patients and six controls were enroled for coronal short tau inversion recovery (STIR), T2 multi-echo fast-spin echo and multi-echo fast-gradient echo MRI of the orbits. STIR signal intensity ratios (SIRs), T2-relaxation times and percentage FF were derived for inferior, lateral, superior and medial recti bilaterally. Twelve patients were re-scanned following immunosuppressive treatment. The results found a positive correlation for all subjects between T2 and SIR (p < 0.001), but only mean T2 differed significantly between patients and controls (p < 0.001). We measured FF in EOMs for the first time and found it greater in TED (p < 0.001). There was also a significant reduction in mean T2 after treatment, with a corresponding reduction in the clinical activity score (CAS) in almost all patients. We show that T2-relaxation times differentiate between normal and inflamed EOMs and are responsive to treatment. Combined, uniquely, with FF measurement in EOMs, an objective, quantitative marker of inflammation in TED-affected muscles could be derived. T2-relaxation times mirrored improvements in CAS after treatment, occasionally preceding them. Rarely, they diverged, suggesting limitations in the CAS as a disease burden marker.

Quantitative MR imaging of intra-orbital structures: Tissue-specific measurements and age dependency compared to extra-orbital structures using multispectral quantitative MR imaging

The orbit can be affected by unique pathologic conditions and often requires MRI evaluation. The purpose of this study was to investigate the age-related changes in multiple intra-orbital structures using quantitative MRI (qMRI). Thirty-eight subjects (20 males, 18 females; ages 0.5-87 years) underwent MRI with a mixed turbo spin echo sequence. T1 and T2 measurements were obtained within ROI in 6 intra-orbital structures (medial and lateral rectus muscles, medial and lateral retrobulbar fat, lacrimal gland, and optic nerve), and compared with those of corresponding extra-orbital structures (masseter muscle, subcutaneous cheek fat, buccal fat, parotid gland, and frontal white matter). Statistical analyses were performed using Pearson's correlation coefficients. T1 and T2 values of the extra-ocular muscles increased with age, with higher T1 and T2 values compared to the masseter muscles. Retrobulbar fat showed significant age-associated increases in T1 values in the lateral side and in T2 values in both sides. T1 and T2 values in the lacrimal gland increased with age, while the parotid gland showed an age-associated increase in T2 values and decrease in T1 values. Optic nerves demonstrated age-related changes, similar to that of frontal white matter; rapid decreases with age in T1 and T2 times in early stages of life, and slight increases in T1 and T2 times later in life. Intra-orbital structures demonstrated specific qMRI measurements and aging patterns, which were different from extra-orbital structures. Location-specific age-related changes of intra-orbital structures should be considered in the qMRI assessment of the orbital pathology.

Dysthyroid optic neuropathy: update on pathogenesis, diagnosis, and management

INTRODUCTION

Dysthyroid optic neuropathy (DON) is a severe manifestation of thyroid eye disease (TED) that can result in permanent vision loss. Management is complex, multidisciplinary, and involves medical and/or surgical therapies. This review describes current concepts in the epidemiology, pathophysiology, diagnosis, and treatment of DON.

AREAS COVERED

An extensive review of the literature was performed to detail current concepts on the diagnosis and management of DON. This includes utilization of various medical and surgical modalities for disease management.

EXPERT COMMENTARY

DON can result in permanent blindness and often requires the use of corticosteroids and surgical decompression. We favor the use of intravenous corticosteroids and a transcaruncular approach when surgical decompression is indicated. The use of orbital radiation for DON is often reserved for patients that are poor surgical candidates and/or patients with refractory disease.

Fractional anisotropy and diffusivity changes in thyroid-associated orbitopathy

INTRODUCTION

To investigate the extraocular muscle (EOM) changes in thyroid-associated orbitopathy (TAO) on DTI and the correlations between DTI parameters and clinical features.

METHODS

Twenty TAO patients and 20 age- and sex-matched controls provided informed consent and were enrolled. Ten-directional DTI was acquired in orbit. Fractional anisotropy (FA), mean, axial, and radial diffusivities were obtained at medial and lateral EOMs in both orbits. EOM thickness was measured in patients using axial CT images. FA and diffusivities were compared between patients and controls. The relationships between DTI values and muscle thickness and exophthalmos were evaluated. DTI values compared between patients in active and inactive phases by clinical activity score of TAO. DTI values were also compared between acute and chronic stages by the duration of disease.

RESULTS

In medial EOM, FA was significantly lower in patients (p < 0.001) and negatively correlated with muscle thickness (r = -0.604, p < 0.001). Radial diffusivity was significantly higher in patients (p = 0.010) and correlated with muscle thickness (r = 0.349, p = 0.027). In lateral EOM, DTI values did not differ between patients and controls. In the acute stage, the diffusivities of the medial rectus EOM were increased compared with the chronic stage. DTI values of the medial and lateral rectus EOM did not differ significantly between active and inactive phases.

CONCLUSION

DTI can be used to diagnose TAO with FA and radial diffusivity change in EOM. Diffusivities can be used to differentiate acute and chronic stage of TAO. However, DTI values showed limitation in reflecting TAO activity according to the CAS.

Orbital Fat Volumetry and Water Fraction Measurements Using T2-Weighted FSE-IDEAL Imaging in Patients with Thyroid-Associated Orbitopathy

BACKGROUND AND PURPOSE

The quantitative evaluation of orbital fat proliferation and edema and the assessment of extraocular muscles are useful for diagnosing and monitoring thyroid-associated orbitopathy. To evaluate therapy-induced quantitative changes in the orbital fat of patients with thyroid-associated orbitopathy, we performed volumetric and water fraction measurements by using T2-weighted FSE iterative decomposition of water and fat with echo asymmetry and least-squares estimation (FSE-IDEAL) imaging.

MATERIALS AND METHODS

Orbital FSE-IDEAL images of 30 volunteers were acquired twice within 1 week. Nine patients with thyroid-associated orbitopathy underwent FSE-IDEAL imaging before and after methylprednisolone pulse therapy, and the treatment results were assessed by using their pre- and post-methylprednisolone pulse therapy clinical activity scores. We performed volumetric and water fraction measurements of orbital fat by using FSE-IDEAL imaging and evaluated interscan differences in the volunteers. In patients with thyroid-associated orbitopathy, we compared pre- and posttherapy orbital fat measurements and assessed the correlation between the pretherapy values and clinical activity score improvement.

RESULTS

The reproducibility of results obtained by the quantitative evaluation of orbital fat in volunteers was acceptable. After methylprednisolone pulse therapy, the water fraction in the orbital fat of patients with thyroid-associated orbitopathy was significantly decreased (P < .001). There was a significant positive correlation between the pretherapy water fraction and clinical activity score improvement (right, r = 0.82; left, r = 0.79) and a significant negative correlation between the pretherapy volume and clinical activity score improvement (bilateral, r = -0.84).

CONCLUSIONS

Volumetric and water fraction measurements of orbital fat by using FSE-IDEAL imaging are feasible and useful for monitoring the effects of therapy and for predicting the response of patients with thyroid-associated orbitopathy to methylprednisolone pulse therapy.

Overall safety and efficacy of high-dose and low-dose intravenous glucocorticoid therapy in patients with moderate-to-severe active Graves' ophthalmopathy

The objective of this study was to compare the safety and efficacy of high-dose and low-dose intravenous (iv) glucocorticoid (GC) therapy in patients with Graves' ophthalmopathy (GO) and to investigate which factors may help determine appropriate iv GC doses. The medical records of 43 patients who received different doses of iv GCs for GO were retrospectively reviewed. Twenty patients received high-dose iv GCs (HD group, cumulative dose 9.0-12.0 g) and 18 received low-dose iv GCs (LD group, cumulative dose 4.5 g). Five patients with previous treatment for GO were excluded. Changes in ophthalmic parameters after treatment and frequencies of adverse effects due to GCs of the 2 groups were compared. We also reviewed the incidence of GO progression and hepatic dysfunction after patients were discharged. We evaluated correlations among pretreatment (before treatment) ophthalmic parameters and investigated useful predictive factors for determining iv GC doses. There were no significant differences in ophthalmic parameters reflecting treatment efficacy or overall safety between the groups. Among baseline ophthalmic parameters, corrected signal intensity ratio (cSIR) correlated well with magnetic resonance imaging findings and were more strongly associated with changes in ophthalmic parameters after treatment in the HD group than in the LD group, indicating that pretreatment cSIR might be useful for determining iv GC doses. In conclusion, there were no significant differences in overall safety and efficacy between high-dose and low-dose iv GC therapy in patients with active GO. Further randomized clinical trials with longer observation periods are required to establish the optimal treatment regimen of GO.

Diagnosis and stage of Graves' ophthalmopathy: Efficacy of quantitative measurements of the lacrimal gland based on 3-T magnetic resonance imaging

The aim of the present study was to determine the efficacy of quantitative measurements of the lacrimal gland based on 3-T magnetic resonance (MR) imaging in the diagnosis and staging of Graves' ophthalmopathy (GO). The study retrospectively enrolled 33 patients with GO (the GO group) and 24 healthy volunteers [the healthy control (HC) group] with orbit MR imaging performed using a 3-T MR scanner. Quantitative parameters of the lacrimal gland, including axial length, axial width, axial area, coronal length, coronal width, coronal area, volume and signal intensity ratio (SIR) of the lacrimal gland to the ipsilateral temporal muscle were measured. The difference of quantitative parameters between the GO and HC groups, or between active and inactive GO groups were evaluated using a Student's t-test. Receiver operating characteristic analyses were used to evaluate the diagnostic value of the significant parameters in discriminating patients with GO from healthy controls, or discriminating active from inactive GO. All the quantitative measurements of the GO patients were significantly larger than those of the healthy controls (P<0.05), with the exception of the coronal length (P=0.150). Axial and coronal width had the best efficacy in discriminating patients with GO from healthy controls. Only SIR was found to be different between the active and inactive GO groups (P=0.001). Setting a SIR of 2.57 as the threshold value, the optimal efficacy was achieved (area under the curve, 0.711; sensitivity, 57.7%; specificity, 77.5%) in discriminating between active and inactive GO. Quantitative measurements of the lacrimal gland based on 3-T MR imaging may assist in the diagnosis and stage of GO.

Relationship between magnetic resonance imaging signal intensity and volume of extraocular muscles in thyroid-associated ophthalmopathy with methylprednisolone pulse therapy

Purpose

To characterize the relationship between inflammation and swelling of extraocular muscles in thyroid-associated ophthalmopathy before and after methylprednisolone pulse therapy.

Methods

The signal intensities and volumes of the superior rectus (SR), inferior rectus (IR), lateral rectus (LR), medial rectus (MR), and superior oblique (SO) muscles were measured with magnetic resonance imaging in 25 eyes of 25 patients with thyroid-associated ophthalmopathy in the acute inflammatory phase before and after methylprednisolone pulse therapy. The signal intensity ratios (SIRs) of muscles and brain white matter were calculated.

Result

The mean SIRs before treatment were 2.28±0.74 in SR, 2.66±0.57 in IR, 2.03±0.42 in LR, 2.45±0.49 in MR, and 1.98±0.48 in SO muscles. The mean SIRs after treatment were 1.82±0.62, 1.84±0.52, 1.70±0.35, 1.95±0.46, and 1.60±0.36, respectively. The mean volumes (cm³) before treatment were 1.35±0.67 in SR, 1.21±0.39 in IR, 0.66±0.13 in LR, 0.94±0.31 in MR, and 0.58±0.14 in SO muscles. Those after treatment were 1.12±0.45, 0.91±0.31, 0.61±0.12, 0.85±0.28, and 0.49±0.11, respectively. The SIRs showed significantly positive correlations with volumes both before and after treatment in SR muscles (before, r=0.77; after, r=0.69), IR muscles (before, r=0.65; after, r=0.60), MR muscles (before, r=0.69; after, r=0.73), and SO muscles (before, r=0.52; after, r=0.50) (P<0.01 for all correlations).

Conclusion

Swelling reflected the inflammation in extraocular muscles of thyroid-associated ophthalmopathy both before and after treatment.

Imaging of Optic Neuropathy and Chiasmal Syndromes

Optic neuropathy involves loss of visual acuity, color vision, and visual field defect with a swollen, pale, anomalous, or normal optic disc seen on fundoscopy. Chiasmal disorders classically present with gradual onset of vision loss, bitemporal hemianopsia, and occasionally, endocrinopathy if the pituitary gland and/or hypothalamus are the causes or are involved. Advance in neuroimaging, especially magnetic resonance (MR) imaging, can reveal pathologic conditions previously detected only clinically. Some entities have imaging characteristics, leading to appropriate treatment without requiring tissue biopsies. Imaging also provides disease surveillance and posttreatment assessment, with computed tomography and MR imaging being complementary to each other.

Imaging Evaluation of the Orbit in Graves Ophthalmopathy

ABSTRACT: Diagnosis of Graves ophthalmopathy is based on the typical eye signs and symptoms, the exclusion of other orbital pathologies and evidence of thyroid autoimmunity. We report the case of a non-smoker 61 years old woman, known with Graves disease, which performed a 3T MRI examination in order to evaluate the orbits. The MRI exam revealed eye protrusion, increased orbital fat with compression on the optic nerve and increased volume of the extraocular muscles. We concluded that MRI, using high-field 3T imaging techniques, is very important for diagnosis of these anomalies, making the differential diagnosis with other pathology and also providing additional information in the decision for therapy.

Graves' ophthalmopathy: the role of diffusion-weighted imaging in detecting involvement of extraocular muscles in early period of disease

OBJECTIVE

To evaluate involvement of the extraocular muscle (EOM) using diffusion-weighted imaging (DWI), to determine whether there is correlation with conventional orbital MRI and apparent diffusion coefficient (ADC) values in patients with Graves' ophthalmopathy (GO).

METHODS

35 patients known clinically with GO and 21 healthy controls were studied. Patients were assessed with clinical activity scores. All subjects underwent conventional MRI and DWI study. Involvement of the EOM was evaluated. The patients were classified as involved or uninvolved on orbital MRI and their ADC values in DWI compared.

RESULTS

There was significant difference in the mean ADC value of all the EOMs in patients vs controls. The ADC values of all the EOMs were higher in patients. There were significant differences in ADC values between uninvolved muscles on conventional MRI and controls for the MR, SR and LR. There was no significant difference in ADC value between the two groups when considering the IR. ADC values of medial, lateral and superior rectus muscles were increased.

CONCLUSION

Increased ADC values of the EOM in patients with GO suggest that EOM damage begins at a very early stage before being detected on routine orbital MRI. The routine MRI with DWI sequence will be a useful adjunct in the selection of a group of patients most likely to benefit from early treatment.

ADVANCES IN KNOWLEDGE

This study can help to evaluate the involvement of GO in early period with MRI added DWI.

Use of MRI signal intensity of extraocular muscles to evaluate methylprednisolone pulse therapy in thyroid-associated ophthalmopathy

PURPOSE

To quantitatively evaluate the efficacy of methylprednisolone pulse therapy for extraocular muscle inflammation in thyroid-associated ophthalmopathy (TAO) using the short-tau inversion-recovery (STIR) technique of magnetic resonance imaging (MRI).

METHODS

The signal intensities of the superior rectus (SR), inferior rectus (IR), lateral rectus (LR), medial rectus (MR), and superior oblique (SO) muscles were measured using the STIR images from 34 eyes of 17 patients with TAO before and after methylprednisolone pulse therapy and 19 eyes of 19 controls. The signal intensity ratio (SIR) of the signal intensity in muscles to that in brain white matter was calculated.

RESULTS

The mean SIRs of the controls were 1.08 ± 0.26 in the SR, 1.32 ± 0.29 in the IR, 1.34 ± 0.19 in the LR, 1.47 ± 0.25 in the MR, and 1.28 ± 0.22 in the SO muscles. SIRs exceeding 2.0 were out of the normal range. The SIRs of the patients with TAO before treatment were 2.19 ± 0.64, 2.44 ± 0.58, 1.96 ± 0.43, 2.24 ± 0.47, and 1.91 ± 0.42, respectively, which was significantly (P < 0.001) higher than those of the controls; after treatment, the mean SIRs were 1.82 ± 0.57, 1.81 ± 0.49, 1.64 ± 0.35, 1.88 ± 0.43, and 1.54 ± 0.33, respectively, significantly (P < 0.001) lower in all muscles than those before treatment. However, the SIRs of some muscles remained over 2.0. Moreover, all cases that had deterioration of TAO had one or more muscles with a SIR exceeding 2.5 after treatment.

CONCLUSION

Extraocular muscle inflammation in TAO improved with treatment. However, inflammation in some muscles persisted after treatment, and a high SIR in the muscle after treatment suggested the risk of deterioration of TAO.

Imaging anatomy and pathology of extraocular muscles in adults

The extraocular muscles (EOM) are involved in a variety of disease processes with characteristic findings on imaging. EOM anatomy is described, followed by a review of adult EOM pathology. The imaging characteristics are explained with examples. The pattern of EOM disease on imaging, in corroboration with clinical findings, can often lead the radiologist towards a specific diagnosis.

Diagnostic accuracy of short-time inversion recovery sequence in Graves' Ophthalmopathy before and after prednisone treatment

INTRODUCTION

In Graves' Ophthalmopathy, it is important to distinguish active inflammatory phase, responsive to immunosuppressive treatment, from fibrotic unresponsive inactive one. The purpose of this study is, first, to identify the relevant orbital magnetic resonance imaging signal intensities before treatment, so to classify patients according to their clinical activity score (CAS), discriminating inactive (CAS < 3) from active Graves' Ophthalmopathy (GO) (CAS > 3) subjects and, second, to follow post-steroid treatment disease.

METHODS

An observational study was executed on 32 GO consecutive patients in different phases of disease, based on clinical and orbital Magnetic Resonance Imaging parameters, compared to 32 healthy volunteers. Orbital Magnetic Resonance Imaging was performed on a 1.5 tesla Magnetic Resonance Unit by an experienced neuroradiologist blinded to the clinical examinations.

RESULTS

In pre-therapy patients, compared to controls, a medial rectus muscle statistically significant signal intensity ratio (SIR) in short-time inversion recovery (STIR) (long TR/TE) sequence was found, as well as when comparing patients before and after treatment, both medial and inferior rectus muscle SIR resulted significantly statistically different in STIR. These increased outcomes explain the inflammation oedematous phase of disease, moreover after steroid administration, compared to controls; patients presented lack of that statistically significant difference, thus suggesting treatment effectiveness.

CONCLUSION

In our study, we proved STIR signal intensities increase in inflammation oedematous phase, confirming STIR sequence to define active phase of disease with more sensibility and reproducibility than CAS alone and to evaluate post-therapy involvement.