Radiographic analysis of fatty infiltration of the extraocular muscles in thyroid eye disease

Orbital Liposarcoma Progression From a Well-Differentiated to a Dedifferentiated Type in a Young Patient

A young male patient presented with unilateral proptosis of the left eye. Laboratory tests and an initial computed tomography scan of the orbit were compatible with euthyroid orbitopathy. He subsequently underwent decompression surgery for unfavorable cosmesis and corneal exposure symptoms with good results, but returned 1 year later for recurrence of proptosis. There was a superomedial fatty density extraconal mass on computed tomography scan. A biopsy done a year later confirmed the diagnosis of well-differentiated liposarcoma from the previously noted mass and a dedifferentiated component in the newly appeared mass in the intraconal space. Orbital exenteration with radial forearm free flap was performed followed by orbital radiotherapy. No disease recurrence or metastasis was seen on follow-ups for 7 years since undergoing treatment.

Reduction in Extraocular Muscle Cross-sectional Area and Correlation With Extraocular Motility and Diplopia Following Teprotumumab for Thyroid Eye Disease

PURPOSE

To quantify changes in extraocular muscle (EOM) cross-sectional areas (CSA) on orbital imaging in patients with thyroid eye disease before and after teprotumumab treatment, and assess for correlation with clinical outcomes.

METHODS

This retrospective study included thyroid eye disease patients treated with teprotumumab who had pre- and post-treatment CT imaging. Reformatted oblique coronal images were created for each orbit in a plane perpendicular to the optic nerve. EOM CSA measurements were performed by 2 radiographic reviewers and averaged. Primary outcomes included change in ratio of total EOM to orbit CSA, and of each individual muscle group to orbit CSA, before and after treatment. Secondary outcomes included subanalysis based on age (≥40, <40 years) and Clinical Activity Score (CAS) (≥4, <4), and comparison with clinical outcomes including CAS, Hertel exophthalmometry, Gorman diplopia score, and extraocular motility.

RESULTS

Forty-eight orbits of 24 patients (16 female, mean age 57.9 years) were included. There was a significant reduction in the total EOM to orbit CSA ratio ( p < 0.01) and for each individual rectus muscle to orbit CSA ratio ( p < 0.01 for all groups). Total EOM to orbit CSA ratios were reduced for 21 patients (87.5%); this was statistically significant in 13 patients (54.2%). There was significant improvement in CAS, proptosis, diplopia, and EOM motility ( p < 0.01 for all categories). There was a significant correlation between reduction of EOM CSA, and reduction of diplopia ( p < 0.01) and EOM motility ( p < 0.01).

CONCLUSIONS

EOM CSA is significantly reduced following treatment with teprotumumab, and correlates with clinical findings including improvement in extraocular motility and diplopia.

Current imaging methods for assessing Graves` orbitopathy activity with particular emphasis on FDG-PET

The most frequent extrathyroidal Graves' disease manifestation is Graves' orbitopathy (GO). The treatment of GO is determined by its severity and activity. There is currently no reliable, impartial method for assessing it clinically or distinguishing fibrosis from active inflammatory disorders. Today, imaging methods including orbital ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) are frequently employed to show pathological abnormalities in the ocular adnexa of GO patients. In addition, a not widely accepted technique - 99mTc-DTPA SPECT - has some potential to evaluate retrobulbar inflammation in GO patients. However, FDG-PET/CT is possibly superior to other imaging modalities in detecting inflammation in GO and it may be useful in assessing disease activity in case of clinical or serological uncertainty. It might also act as an early indicator of GO development and its aggravation before irreversible tissue alterations take place and may be used in the differential diagnosis of inflammatory disorders of the orbit. However, before FDG-PET/CT could be applied in daily clinical practice, the methodology of GO activity assessment with defined cut-off values for radionuclide concentration - standardized units of value (SUV) have to be established and validated. In addition, the limitations of this technique have to be recognized.

Graves' Eye Disease: Clinical and Radiological Diagnosis

Graves' disease is an autoimmune disorder in which hyperthyroidism results in various systematic symptoms, with about 30% of patients presenting with Graves' eye disease (GED). The majority of patients with GED develop mild symptoms, including eyelid retraction, exposure of the globe, superior rectus-levator muscle complex inflammation, and fat expansion, leading to exophthalmos. More severe cases can result in extraocular muscle enlargement, restricted ocular movement, eyelid and conjunctival edema, and compression of the optic nerve leading to compressive optic neuropathy (CON). GED severity can be classified using the Clinical Activity Score, European Group on Graves' Orbitopathy scale, NO SPECS Classification system, and VISA system. CT and MRI aid in the diagnosis of GED through the demonstration of orbital pathology. Several recent studies have shown that MRI findings correlate with disease severity and can be used to evaluate CON. Mild cases of GED can be self-limiting, and patients often recover spontaneously within 2-5 years. When medical treatment is required, immunomodulators or radiotherapy can be used to limit immunologic damage. Surgery may be needed to improve patient comfort, preserve the orbit, and prevent vision loss from optic nerve compression or breakdown of the cornea.

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.

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.

Extrathyroidal Manifestations of Thyroid Disease: Graves Eye Disease

Graves disease is an autoimmune disorder caused by the breakdown of immune tolerance to thyroid antigens against the TSH receptor. In approximately 25% of patients, an inflammatory condition, Graves eye disease (GED), affects the orbital soft tissues. About 60% of patients develop mild symptoms including fat expansion and inflammation of the levator muscle complex with resultant proptosis, eyelid retraction, and exposure of the globe. The remaining patients experience enlargement of one or more of the extraocular muscles, leading to conjunctival and eyelid edema and congestion, restricted ocular movement with resultant diplopia, and optic nerve compression leading to compressive optic neuropathy.