Role of magnetic resonance imaging in the assessment of disease activity in thyroid-associated ophthalmopathy

Whole-orbit radiomics: machine learning-based multi- and fused- region radiomics signatures for intravenous glucocorticoid response prediction in thyroid eye disease

BACKGROUND

Radiomics analysis of orbital magnetic resonance imaging (MRI) shows preliminary potential for intravenous glucocorticoid (IVGC) response prediction of thyroid eye disease (TED). The current region of interest segmentation contains only a single organ as extraocular muscles (EOMs). It would be of great value to consider all orbital soft tissues and construct a better prediction model.

METHODS

In this retrospective study, we enrolled 127 patients with TED that received 4·5 g IVGC therapy and had complete follow-up examinations. Pre-treatment orbital T2-weighted imaging (T2WI) was acquired for all subjects. Using multi-organ segmentation (MOS) strategy, we contoured the EOMs, lacrimal gland (LG), orbital fat (OF), and optic nerve (ON), respectively. By fused-organ segmentation (FOS), we contoured the aforementioned structures as a cohesive unit. Whole-orbit radiomics (WOR) models consisting of a multi-regional radiomics (MRR) model and a fused-regional radiomics (FRR) model were further constructed using six machine learning (ML) algorithms.

RESULTS

The support vector machine (SVM) classifier had the best performance on the MRR model (AUC = 0·961). The MRR model outperformed the single-regional radiomics (SRR) models (highest AUC = 0·766, XGBoost on EOMs, or LR on OF) and conventional semiquantitative imaging model (highest AUC = 0·760, NaiveBayes). The application of different ML algorithms for the comparison between the MRR model and the FRR model (highest AUC = 0·916, LR) led to different conclusions.

CONCLUSIONS

The WOR models achieved a satisfactory result in IVGC response prediction of TED. It would be beneficial to include more orbital structures and implement ML algorithms while constructing radiomics models. The selection of separate or overall segmentation of orbital soft tissues has not yet attained its final optimal result.

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.

Correlation Analysis between Intraocular Pressure and Extraocular Muscles Based on Orbital Magnetic Resonance T2 Mapping in Thyroid-Associated Ophthalmopathy Patients

Background: The correlation between intraocular pressure (IOP) and the magnetic resonance imaging (MRI) parameters in thyroid-associated ophthalmopathy (TAO) patients was explored. Methods: This study included 82 eyes in 41 TAO patients who had a large difference in the IOP between each eye. We measured the T2 relaxation time (T2RT) of the extraocular muscles (EOMs), the orbital fat, and the area of the EOMs. Results: There was a positive correlation between IOP and exophthalmos, the clinical activity score (CAS), the T2RT (of the medial rectus (MR)), the area of the MR, inferior rectus (IR) and lateral rectus, and the mean area. We established a regression model with IOP as the dependent variable, and the area of the IR was statistically significant. Conclusions: High IOP in TAO patients was positively correlated with the degree of exophthalmos and EOM inflammation (especially the inferior rectus). The state of the EOMs in an orbital MRI may partially explain high IOP and provide the necessary clinical information for subsequent high IOP treatment.

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.

Observation study of using a small dose of rituximab treatment for thyroid-associated ophthalmopathy in seven Chinese patients: One pilot study

OBJECTIVE

To report the efficacy, long-term safety, and tolerability of using a small dose (125 mg/m2 weekly for 4 weeks) of rituximab to treat Chinese patients with thyroid-associated ophthalmopathy (TAO).

METHODS

Seven patients with active moderate-to-severe TAO were prospectively recruited in this study. A small dose of rituximab (125mg/m2 body surface area) was given weekly with a duration of four weeks. Thyroid function, thyrotropin receptor antibody (TRAb), B cell and T cell subsets, ophthalmological examination, magnetic resonance imaging derived parameters, and adverse reactions were recorded at each visit.

RESULTS

Seven patients were followed for an average of 224 weeks. B-cell depletion was observed in all patients following rituximab infusion. The clinical activity score (CAS) decreased from 4.86 ± 0.69 to 3.00 ± 0.82 at 5 weeks after treatment (P = 0.033) and remained significantly lower than baseline values at the end of follow-up (P = 0.001). Compared to baseline values, significant decreases in exophthalmos of the right eye, the thickness of extraocular muscles with maximum signal intensity, and the highest signal intensity ratio (SIR) of extraocular muscle to ipsilateral temporal muscle values were observed at the last follow-up (all P < 0.05). Disease progressions or recurrences were not observed during follow-up. Only mild fatigue was observed after the first infusion as a side effect (n = 1).

CONCLUSION

Small dose of rituximab may be a promising option with adequate safety, tolerability, and long-term efficacy for patients with active moderate-to-severe TAO.

Texture analysis of orbital magnetic resonance imaging for monitoring and predicting treatment response to glucocorticoids in patients with thyroid-associated ophthalmopathy

PURPOSE

To evaluate the value of MRI-based texture analysis of extraocular muscle (EOM) and orbital fat (OF) in monitoring and predicting the response to glucocorticoid (GC) therapy in patients with thyroid-associated ophthalmopathy (TAO).

METHODS

Thirty-seven active and moderate-to-severe TAO patients (responders, n = 23; unresponders, n = 14) were retrospectively enrolled. MRI-based texture parameters (entropy, uniformity, skewness and kurtosis) of EOM and OF were measured before and after GC therapy, and compared between groups. Correlations between the changes of clinical activity score (CAS) and imaging parameters before and after treatment were assessed. Receiver operating characteristic curves were used to evaluate the predictive value of identified variables.

RESULTS

Responsive TAOs showed significantly decreased entropy and increased uniformity at EOM and OF after GC therapy (P < 0.01), while unresponders showed no significance. Changes of entropy and uniformity at EOM and OF were significantly correlated with changes of CAS before and after treatment (P < 0.05). Responders showed significantly lower entropy and higher uniformity at EOM than unresponders before treatment (P < 0.01). Entropy and uniformity of EOM and disease duration were identified as independent predictors for responsive TAOs. Combination of all three variables demonstrated optimal efficiency (area under curve, 0.802) and sensitivity (82.6%), and disease duration alone demonstrated optimal specificity (100%) for predicting responsive TAOs.

CONCLUSION

MRI-based texture analysis can reflect histopathological heterogeneity of orbital tissues. It could be useful for monitoring and predicting the response to GC in TAO patients.

Baseline Volumetric T2 Relaxation Time Histogram Analysis: Can It Be Used to Predict the Response to Intravenous Methylprednisolone Therapy in Patients With Thyroid-Associated Ophthalmopathy?

OBJECTIVE

Prediction of therapy response to intravenous methylprednisolone pulses (ivMP) is crucial for thyroid-associated ophthalmopathy (TAO). Image histograms may offer sensitive imaging biomarkers for therapy effect prediction. This study aimed to investigate whether pretherapeutic, multiparametric T2 relaxation time(T2RT) histogram features of extraocular muscles (EOMs) can be used to predict therapy response.

MATERIALS AND METHODS

Forty-five active and moderate-severe TAO patients, who were treated with standard ivMP and underwent orbital MRI before therapy, were retrospectively included in this study. The patients were divided into responsive (n = 24, 48 eyes) and unresponsive group(n = 21, 42 eyes) according to clinical evaluation. Baseline clinical features of patients and histogram-derived T2RT parameters of the EOMs were analyzed and compared. Logistic regression model was conducted to determine independent predictors, and a histogram features nomogram was formulated for personalized prediction.

RESULTS

Responsive group displayed lower values for 5^th, 10^th percentiles (P < 0.050, respectively), and higher values for 75^th, 90^th, and 95^th percentiles, skewness, entropy, and inhomogeneity (P < 0.050, respectively) than unresponsive group. Multivariate logistic regression analysis showed that 95^th percentile of >88.1 [odds ratio (OR) = 12.078; 95% confidence interval (CI) = 3.98-36.655, p < 0.001], skewness of >0.31 (OR = 3.935; 95% CI = 2.28-6.788, p < 0.001) and entropy of >3.41 (OR = 4.375; 95% CI = 2.604-7.351, p < 0.001) were independent predictors for favorable response. The nomogram integration of three independent predictors demonstrated optimal predictive efficiency, with a C-index of 0.792.

CONCLUSIONS

Pre-treatment volumetric T2RT histogram features of EOMs could function to predict the response to ivMP in patients with TAO. The nomogram based on histogram features facilitates the selection of patients who will derive maximal benefit from ivMP.

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.

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.

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.

Predictive factors of prognosis after radiation and steroid pulse therapy in thyroid eye disease

To identify predictive factors of prognosis after radiotherapy with concurrent steroid pulse therapy for thyroid eye disease, retrospective analyses were performed among 77 patients. Clinical activity score and magnetic resonance imaging were used to evaluate degrees of orbital inflammation. As a pre-treatment work-up, the thyroid-stimulating antibody (TSAb) level was measured. During a median follow-up of 25.0 months, the 2-year cumulative relapse-free rate (CRFR) was 80.9%. In the univariate analysis, a worse 2-year CRFR was significantly associated with the presence of optic neuropathy (P = 0.001), a higher TSAb rate (P = 0.001), and lower standard deviation (SD) of signal intensity at the extraocular muscle in T2-weighted images (P = 0.006). In the multivariate analysis, TSAb rate and SD affected the CRFR independently. When TSAb activity of 2800% was set as a cut-off at 2 years after treatment, the predictive sensitivity and specificity of relapse were 81.2% and 90.6%, respectively. With regard to SD, the respective sensitivity and specificity values were 81.2% and 82.7% when 100 was set as a cut-off. In conclusion, high TSAb and low SD were significant risk factors for cumulative relapse in orbital radiotherapy. Cut-off values of 2800% for TSAb and 100 for SD may be suitable.

Efficacy of 99mTc-DTPA SPECT/CT in diagnosing Orbitopathy in graves' disease

BACKGROUND

The most frequently used methods of assessing Graves' orbithopathy (GO) include: Clinical Activity Score (CAS), ultrasonography (USG), computed tomography (CT), and magnetic resonance imaging (MRI). There exists another, slightly forgotten, imaging method: single-photon emission computed tomography (SPECT) with the use of diethylenetriaminepentaacetic acid tagged with ^99mTc (^99mTc-DTPA). These days it is possible to conduct a SPECT examination fused with a CT scan (SPECT/CT), which increases the diagnostic value of the investigation. The aim of this paper is to evaluate the usefulness of ^99mTc-DTPA SPECT/CT in diagnosing Graves orbitopathy, as compared with other methods.

METHODS

Twenty-three patients with suspected active (infiltrative-edematous) Graves' orbithopathy were included in the study. Each patient underwent a CAS, an MRI, and a SPECT/CT. The obtained results were analysed statistically, with the assumed statistical significance of p < 0.05.

RESULTS

The SPECT/CT and MRI were found to have the highest sensitivity: 0.93 each. The SPECT/CT had the highest specificity: 0.89. MRI and CAS had lower values: 0.78 and 0.56, respectively. The occurrence of an active form of GO had no impact on the exacerbation of exophthalmos or the thickness of the oculomotor muscles.

CONCLUSIONS

The ^99mTc-DTPA SPECT/CT method provides a very good tool for assessing the active form of GO and can, alongside the MRI scan, be used as a referential diagnostic procedure in GO.

Color Doppler imaging in thyroid eye disease and its correlation to disease activity

Purpose: To evaluate alterations in orbital color Doppler imaging (CDI) parameters and their correlation to disease activity and severity in patients with thyroid eye disease (TED). Methods: Seventy-six orbits of 45 TED patients and 40 orbits of 40 normal controls were enrolled in this cross-sectional study. According to clinical activity score (CAS), patients were categorized to active (CAS ≥ 3) or inactive disease (CAS < 3). Patients were also classified as having mild, moderate or severe disease. Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) in ophthalmic artery and central retinal artery, and maximum and minimum velocity in superior ophthalmic vein and central retinal vein were determined in all subjects. Results: There was a significant difference in maximum velocity of superior ophthalmic vein and EDV and RI of ophthalmic artery between patients with TED and normal subjects. Superior ophthalmic vein maximum and minimum velocity and ophthalmic artery RI were significantly higher in patients with active disease than inactive cases. Disease severity did not affect the blood flow parameters independently. A cutoff point of 3.99 cm/s in superior ophthalmic vein maximum velocity yielded a sensitivity of 91.2% and specificity of 81.2% in detecting active disease. Conclusion: Retrobulbar blood flow is altered in TED and is related to disease activity. Superior ophthalmic vein maximum velocity could be helpful in differentiation of active and inactive cases.

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.

Evaluating the Microcirculation of Normal Extraocular Muscles Using Quantitative Dynamic Contrast-Enhanced Magnetic Resonance Imaging

PURPOSE

The purpose of this work was to evaluate the microcirculation of normal extraocular muscles using quantitative dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) (DCE-MRI).

MATERIALS AND METHODS

The institutional review board approved the study. Forty-eight eyes were examined using quantitative DCE-MRI on a 3-T MRI system. Quantitative parameters, including the volume transfer constant (Ktrans), the fractional volume of extravascular extracellular space (Ve), and the rate constant (Kep) of each extraocular muscles, were analyzed. The type of DEC time-intensity curve (TIC) was evaluated. The parameters of bilateral extraocular muscles were compared using the Wilcoxon test. The difference in quantitative values of different extraocular muscles was compared using independent-samples Kruskal-Wallis test.

RESULTS

No statistical differences of parameters were found between the left and right extraocular muscles (P > 0.05). Volume transfer constant values in medial rectus (MR) muscles and inferior rectus (IR) muscles were significantly higher than those in the lateral rectus (LR) muscles and superior rectus (SR) muscles (P < 0.05). The median Ktrans value of the MR (0.170) was higher than that of the IR (0.151); however, the difference was not significant (P > 0.05). In the 4 extraocular muscles, the Ve values of MR are the largest, followed by the IR, LR, and SR values. The DCE time-intensity curves of extraocular muscles are type II or type III. Medial rectus and IR are mainly type III, and LR and SR are mainly type II.

CONCLUSION

The quantitative DCE-MRI can be used as an important and noninvasive technique to evaluate the microcirculation of extraocular muscles. Further investigations for other extraocular muscles diseases by using quantitative DCE-MRI are warranted.

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.

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.

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.

Disease activity in Graves' ophthalmopathy: diagnosis with orbital MR imaging and correlation with clinical score

In Graves' ophthalmopathy (GO) it is important to distinguish acute inflammation at an early stage, responsive to immunosuppressive treatment, from inactive fibrotic end stage disease, unresponsive to the same treatment. The purpose of this study was to identify the most relevant signal intensities on orbital MR imaging with contrast administration both to classify patients according to their clinical activity score (defined by a cut-off value of 3) and to make a prediction of patient's CAS. Such threshold was considered as widely used in literature. Sixteen consecutive patients with a diagnosis of GO in different phases of thyroid disease based on clinical and orbital MR imaging signs, and six normal volunteers were examined. Orbital MR imaging was performed on a 1.5 Tesla MR Unit. MR scans were assessed by an experienced neuroradiologist, blinded to the clinical examinations. We found a statistical correlation between CAS and both STIR and contrast enhanced T1-weighted sequences. There was also a statistically significant correlation between STIR and contrast-enhanced T1 images disclosing the possibility of avoiding the injection of contrast medium. Our study proved that signal intensity values on STIR sequence increase in the inflammatory oedematous phase of disease. We confirmed the correlation between signal intensities on this sequence and CAS, showing an increase in signal intensity proportional to the CAS value. So we validated MRI use to establish the activity phase of disease more sensitively than CAS alone.

Signal intensity and T2 time of extraocular muscles in assessment of their physiological status in MR imaging in healthy subjects

Background:

Lack of standardised orbital MR protocols leads to a situation, when each institution/centre may arbitrarily choose sequence parameters. Therefore, the results obtained and published by the authors may not be compared freely, and what is most important may not be considered fully reliable. Signal intensity (IS) and T2 time (T2) are important parameters in estimation of inflammatory processes of extraocular muscles in the clinical practice.

The aim of this study was to determine the reference values (i.e. cut-off values) for absolute signal intensity and T2 relaxation time in healthy subjects, their relativised values to white matter (WM) and temporal muscles (TM) and to evaluate the correlation between those parameters.

Material/Methods:

The orbital examination was performed in healthy volunteers according to the protocol prepared in the Radiology-Imaging Diagnostic Department of the Medical University of Lodz for patients with suspected/diagnosed thyroid orbitopathy. Using two of the standard sequences IS and T2 time were calculated for the muscles and two relativisation tissues in realtion to WM and TM. Subsequently cut-off values for healthy volunteers were calculated.

Results:

The differences between muscles for IS, IS MAX, IS/TM, IS/WM, IS MAX/TM, IS MAX/WM and T2 MAX/WM were not statistically significant. Therefore one cut-off value of these parameters for all the rectus muscles was calculated. T2-relaxation time and T2 relativised to white matter had to be calculated separately for each muscle.

Conclusions:

No statistical correlation was found between IS and T2-time for extraocular muscles in healthy volunteers. We calculated the reference ranges (cut-off values) for absolute IS and T2-time values and relativised parameters. In the clinical practice the objectification of IS and T2-time values should be done to WM, than to IS or T2 of the temporal muscle. The T2 MAX/WM seems to have the highest clinical utility for the assessment of the pathophysiological status of extraocular muscles.

Neuroimaging of Graves' orbitopathy

Neuroimaging of Graves' orbitopathy (GO) plays an important role in the differential diagnosis and interdisciplinary management of patients with GO. Orbital imaging is required in unclear or asymmetric proptosis, in suspected optic neuropathy and prior to decompression surgery. Especially computed tomography and magnetic resonance (MR) imaging show the actual objective morphological findings, quantitative MR imaging giving additional information concerning the acuteness or chronicity of the disease. Major morphological diagnostic criteria include a spindle like spreading of the rectus muscles without involvement of the tendon, a compression of the optic nerve in the orbital apex (crowded orbital apex syndrome) and the absence of any space occupying intraorbital process. A longer lasting course of the disease may lead to a corresponding impression of the lamina papyracae, the normally parallel configured medial wall of the orbit, similar to a spontaneous decompression.

Severe thyroid-associated orbitopathy in Hashimoto's thyroiditis. Report of 2 cases

Thyroid-associated orbitopathy (TAO) is characterized by immune-mediated inflammation of the extraocular muscles surrounding orbital connective tissue and adipose tissue. Severe orbitopathy related to autoimmune thyroid disease often occurs in patients with Grave's disease, but it is rare in patients with Hashimoto's thyroiditis. The pathogenesis of TAO is unclear. Several studies have noted a strong correlation between the levels of antibodies to thyrotropin receptor antibody (TRAb) and TAO in Graves' disease. Mild upper eyelid retraction has been reported to be common in Hashimoto's thyroiditis patients, however severe orbitopathy is rare. We report two cases of severe TAO in patients with Hashimoto's thyroiditis who required systemic glucocorticoid therapy and orbital irradiation to treat the TAO. The activity of the TAO was high in both patients, because their clinical activity scores (CAS) for the orbitopathy were high, and magnetic resonance imaging (MRI) showed enlargement of the extraocular muscles and an increase in T2 signal intensity and prolonged T2 relaxation time which indicate an active stage of inflammation. We tested the presence of TRAb by three different assays and were negative in both patients. Since the eye muscle damage cannot be due to TSH receptor antibodies, other pathogenetic mechanisms may be responsible for the orbitopathy in patients with Hashimoto's thyroiditis.

Thyroid eye disease

Thyroid eye disease (TED) is the most common cause of proptosis in adults, and should always be a consideration in patients with unexplained diplopia, pain, or optic nerve dysfunction. At least 80% of TED is associated with Graves disease (GD), and at least 50% of patients with GD develop clinically evident symptomatic TED. The most confusing patients for doctors of all subspecialties are the patients with eye symptoms and signs that precede serum evidence of a thyroid imbalance. Management of TED may include immunosuppressive medications, radiation, or surgery. Although the prognosis for optic nerve function is excellent, the restrictive dysmotility can result in permanent disability. Orbit and eyelid reconstruction are reserved for stable, inactive patients and are the final steps in minimizing facial alterations and enhancing the patient's daily functioning.

Orbital magnetic resonance imaging combined with clinical activity score can improve the sensitivity of detection of disease activity and prediction of response to immunosuppressive therapy for Graves' ophthalmopathy

The aim of this study was to demonstrate that the addition of orbital magnetic resonance (MR) imaging can provide improvement in sensitivity of detection of active disease and the prediction of the response to intravenous glucocorticoid therapy (ivGC), over clinical activity score (CAS) alone. A prospective case series was studied at our institution. Forty eight patients were examined by CAS and orbital MR imaging. The maximum of T2 relaxation times of extraocular muscles (maxT2RT) and other parameters were evaluated by MR imaging. Thirty five of 48 patients underwent ivGC. Twenty of 35 patients, whose CAS was 2 points or less, were evaluated for the response to ivGC. The correlation between CAS and maxT2RT was evaluated. Differentiation of active and inactive GO was performed by CAS and orbital MR imaging. The response to ivGC was evaluated by CAS, orbital MR imaging and ophthalmic parameters. As a result, CAS and maxT2RT showed significant positive correlation (r=0.58, p<0.0001), and 15 patients were positive by CAS and orbital MR imaging. However, 20 patients were positive by only MR imaging. In those 20 patients, there was significant improvement after ivGC. We concluded that orbital MR imaging combined with CAS could improve the sensitivity of detection of active disease and the prediction of the response to ivGC. In addition, even if only one parameter of CAS is positive, further examination with orbital MR imaging is advised.

Oftalmopatia tireoidea revisitada

A oftalmopatia tireoidea é doença orbitária autoimune intimamente associada com o hipertireoidismo, porém podendo existir separadamente. Pode preceder, coincidir ou suceder o início da disfunção tireoidea, raramente ocorrendo em eutireoideos ou hipotireoideos. Os músculos extraoculares são os principais alvos acometidos e tornam-se aumentados de volume, determinando oftalmoplegia e proptose. Outros sinais importantes incluem retração palpebral, hiperemia conjuntival e edema periorbitário. Perda visual pode ocorrer se há compressão do nervo óptico no ápice orbitário. A oftalmopatia tireoidea é caracterizada por inflamação, congestão, hipertrofia e fibrose da gordura e músculos orbitários. A atividade da doença é dividida em fase aguda ou inflamatória, seguida pela fase inativa associada com alterações fibróticas e infiltração gordurosa. O diagnóstico é clínico, e quando este é difícil ou se suspeita de neuropatia óptica os métodos de imagem são indicados. A tomografia computadorizada e a ressonância magnética podem confirmar o diagnóstico e avaliar a área crítica do ápice orbitário. A ressonância magnética é superior, em virtude da resolução tecidual e da sua capacidade de avaliar a atividade da doença (mediante sequências com TR longo) e detectar alterações inflamatórias, auxiliando o planejamento terapêutico no momento certo, melhorando o prognóstico.

Orbital Inflammatory Disease

OBJECTIVES

To familiarize rheumatologists and internists with the signs, symptoms, and management of orbital inflammatory disease (OID).

METHODS

A comprehensive literature review related to OID was performed and reported from the perspectives of rheumatology, ophthalmology, and radiology.

RESULTS

OID is a general term encompassing inflammatory diseases that affect some or all of the structures contained within the orbit external to the globe. Orbital involvement as a part of the initial symptom complex is not uncommon for systemic diseases such as Graves' disease, Wegener's granulomatosis, and sarcoidosis. The management of these and other causes of OID, such as idiopathic orbital inflammation (formerly known as "orbital pseudotumor"), orbital myositis, and Tolosa-Hunt syndrome frequently involves systemic immunosuppression. Before immunosuppression is considered, however, infectious and malignant causes of inflammation must be ruled out.

DISCUSSION

Rheumatologists should be familiar with the differential diagnosis of OID and often need to assist colleagues in ophthalmology and internal medicine with the management of this group of diseases.

Radiologic measurement of extraocular muscle volumes in patients with Graves' orbitopathy: a review and guideline

OBJECTIVE

To evaluate and compare techniques for extraocular muscle (EOM) volume measurement and to provide guidelines for future measurements.

DESIGN

Systematic review.

RESULTS

Existing techniques used to measure extraocular muscle volumes on radiologic scans can be divided into manual outlining, computer assisted and automated segmentation. Both computed tomography (CT) and magnetic resonance (MR) image datasets can be used. On CT scans, one best measures muscle volume using region grow segmentation, accepting an overestimation of true volume by inevitable inclusion of non-muscular tissue. On high resolution MRI scans, single muscles can be outlined manually, but measurements include only part of the muscle due to poor tissue contrast at the orbital apex. Measurement errors can be reduced 3.5% by exact horizontal repositioning. A measured volume change of at least 6-17% is required to demonstrate a significant difference.

CONCLUSION

Currently the best choice for EOM volume measurements on CT images is computer assisted grey value segmentation and on MRI images is manual outlining of individual muscles. Because of the time required and the complexity of the measurements, present EOM volume measurement is as yet only suitable for research purposes.

Volume changes in intra- and extraorbital compartments in patients with Graves' ophthalmopathy: effect of smoking

The objective of this study was to demonstrate the effect of smoking history on soft tissue expansion in specific orbital compartments in patients with Graves' ophthalmopathy. The volumes of the rectus muscles, intra and extraorbital connective, and soft tissues were measured in 110 orbits of 35 patients and 20 control subjects. Data sets from current smokers, ex-smokers, and non-smokers were compared. The total number of cigarettes smoked was calculated, and it was used as an estimate for the severity of smoking (cumulative smoking). The volume measurements were performed on T1-weighted contiguous transversal magnetic resonance images of the orbits. Connective tissue volumes were influenced by smoking history, while muscle volumes were not affected. Ex-smokers had larger amount of extraorbital connective tissue than current smokers (p = 0.012), and this volume showed a good correlation with the number of cigarettes smoked (r = 0.539, p < 0.05). In current smokers, the amount of intraorbital connective tissue correlated well with the cumulative smoking (r = 0.635, p < 0.001). We conclude that connective tissue volumes in certain orbital compartments correlate well with cumulative smoking. Extraocular muscle volumes are not influenced by smoking in patients with Graves' ophthalmopathy.

Evaluation of extraocular muscles in the edematous phase of Graves ophthalmopathy on contrast-enhanced fat-suppressed magnetic resonance imaging

OBJECTIVE

Extraocular muscles (EOMs) reveal characteristic contrast-enhancement patterns on magnetic resonance (MR) imaging due to their rich vascular supply. The objective of this study was to evaluate contrast-enhancement patterns of EOMs in patients with edematous phase of Graves ophthalmopathy (GO) using contrast-enhanced fat-suppressed MR imaging in comparison with normal volunteers.

METHODS

EOMs of 15 patients with edematous phase of GO and those of 15 normal volunteers were evaluated using coronal T1-weighted MR images with fat suppression before and after intravenous administration of gadolinium. The image sequence was a fast spin-echo with chemical shift selective fat saturation. The degree of contrast enhancement for EOMs and temporal muscles (TMs) was assessed via a 4-step grading system and by 2 reviewers.

RESULTS

There were statistically significant differences for the degrees of contrast enhancement in all EOMs between the patients with GO and normal volunteers. The degrees of contrast enhancement for all EOMs were significantly decreased in patients with edematous phase of GO.

CONCLUSIONS

The microcirculation within the EOMs tends to be impaired during the progress of disease, and the MR imaging pattern gives a semiquantitative measurement of the microcirculatory impairment of the EOMs during the edematous phase of the disease.

Ophthalmological evaluation in thyroid-associated ophthalmopathy

PURPOSE

Thyroid-associated ophthalmopathy (TAO) is an autoimmune disorder associated with Graves' disease and can seriously decrease quality of life. Current therapeutic regimens have considerable side-effects and are not always able to restore normal function and appearance. Timing and a proper choice of therapy are critical but require careful patient evaluation. The present paper aims to describe clinical symptoms and signs of TAO and their relevance for management.

RESULTS AND CONCLUSIONS

Thyroid-associated ophthalmopathy has an initial active inflammatory phase which usually lasts for 6-24 months but which may not infrequently continue for several years. The severity of the subsequent clinical manifestations is determined by the degree of optic nerve involvement, corneal involvement, eye muscle dysfunction and exophthalmus, and also by the degree of subjective illness and disfigurement. Disease severity is the key determinant of indication for therapy, while inflammatory activity is the key determinant of therapeutic choice. Immunosuppressive therapy may be used in the inflammatory stage, while reconstructive surgery should be postponed to the inactive phase. Emergency surgery may be needed for vision-threatening situations during the active stage.

A new MRI method for the quantitative evaluation of extraocular muscle size in thyroid ophthalmopathy

In cross section, extraocular muscles are more or less elliptical, with short and long diameters. We studied the ratio (R) of short to long diameter and investigated its use in quantitative assessment of the extraocular muscles in patients with Graves's disease. We measured the diameters on T1-weighted axial and coronal MRI and computed R for each extraocular muscle in 80 patients without and 40 with Graves's disease. We compared the measurements and R of the right and left orbits, and of men and women. The short diameter of all extraocular muscles apart from the superior oblique showed significant differences between men and women, and that of the inferior rectus varied significantly with age. R, however, was unrelated to sex or age. All patients with Graves's disease and an increased short diameter also had an increased R, but 6% of the muscles showed an increase in R, even though their short diameter was within the normal range.