Extrathyroidal manifestations of thyroid disease: thyroid ophthalmopathy

Disorders with Ophthalmic and Thoracic Involvement

A variety of systemic conditions involve the thorax and the eyes. While subtle or nonspecific eye symptoms can be the initial clinical manifestation of some disorders, there can be additional manifestations in the thorax that lead to a specific diagnosis and affect patient outcomes. For instance, the initial clinical manifestation of Sjögren syndrome is dry eye or xerophthalmia; however, the presence of Sjögren lung disease represents a fourfold increase in mortality. Likewise, patients with acute sarcoidosis can initially present with pain and redness of the eye from uveitis in addition to fever and parotitis. Nearly 90% of patients with sarcoidosis have thoracic involvement, and the ophthalmologic symptoms can precede the thoracic symptoms by several years in some cases. Furthermore, a diagnosis made in one system can result in the screening of other organs as well as prompt genetic evaluation and examination of family members, such as in the setting of Marfan syndrome or Ehlers-Danlos syndrome. Multimodality imaging, particularly CT and MRI, plays a vital role in identification and characterization of these conditions. While it is helpful for ophthalmologists to be knowledgeable about these conditions and their associations so that they can order the pertinent radiologic studies, it is also important for radiologists to use the clues from ophthalmologic examination in addition to imaging findings to suggest a specific diagnosis. Systemic conditions with thoracic and ophthalmologic manifestations can be categorized as infectious, inflammatory, autoimmune, neoplastic, or hereditary in origin. The authors describe a spectrum of these conditions based on their underlying cause. ©RSNA, 2024.

Atypical Asymmetric Presentation of Severe Graves' Orbitopathy

Graves' disease is a self-limiting autoimmune thyroid disorder caused by stimulating antibodies to the thyroid-stimulating hormone receptor. It usually affects middle-aged females in the fourth to sixth decade of life. It is distinguished by keratopathy, chemosis, proptosis, and eyelid swelling, in addition to ocular discomfort. A total of 3-5% of cases present with a severe form of Graves' orbitopathy, which manifests with diminution of vision, optic nerve compression, optic neuropathy, and exposure keratopathy. We describe a case of a 34-year-old female patient who presented with the chief complaint of rapid deterioration of vision over a period of three months in the right eye. Ocular examination revealed proptosis, widened palpebral aperture, elevation of intra-ocular pressure (IOP) in the upgaze, restricted eye movements, and signs of optic nerve compression. Findings were confirmed on a CT scan of the orbit. The unusual presentation in this case was that she had rapid, significant deterioration of vision in the right eye, with a progression of proptosis more marked in the contralateral eye. This underlies the importance of thoroughly examining for any possible orbital apex syndrome in both eyes, not just the eye with marked proptosis. The patient, being reluctant for orbital decompression, was prescribed IV methylprednisolone 1 g for three consecutive days, which reduced her proptosis and improved her vision. This acted as a temporary measure to increase the duration of the surgical window until the time the patient undergoes the surgery.

Clinical and imaging clues to the diagnosis and follow-up of ptosis and ophthalmoparesis

Ophthalmoparesis and ptosis can be caused by a wide range of rare or more prevalent diseases, several of which can be successfully treated. In this review, we provide clues to aid in the diagnosis of these diseases, based on the clinical symptoms, the involvement pattern and imaging features of extra-ocular muscles (EOM). Dysfunction of EOM including the levator palpebrae can be due to muscle weakness, anatomical restrictions or pathology affecting the innervation. A comprehensive literature review was performed to find clinical and imaging clues for the diagnosis and follow-up of ptosis and ophthalmoparesis. We used five patterns as a framework for differential diagnostic reasoning and for pattern recognition in symptomatology, EOM involvement and imaging results of individual patients. The five patterns were characterized by the presence of combination of ptosis, ophthalmoparesis, diplopia, pain, proptosis, nystagmus, extra-orbital symptoms, symmetry or fluctuations in symptoms. Each pattern was linked to anatomical locations and either hereditary or acquired diseases. Hereditary muscle diseases often lead to ophthalmoparesis without diplopia as a predominant feature, while in acquired eye muscle diseases ophthalmoparesis is often asymmetrical and can be accompanied by proptosis and pain. Fluctuation is a hallmark of an acquired synaptic disease like myasthenia gravis. Nystagmus is indicative of a central nervous system lesion. Second, specific EOM involvement patterns can also provide valuable diagnostic clues. In hereditary muscle diseases like chronic progressive external ophthalmoplegia (CPEO) and oculo-pharyngeal muscular dystrophy (OPMD) the superior rectus is often involved. In neuropathic disease, the pattern of involvement of the EOM can be linked to specific cranial nerves. In myasthenia gravis this pattern is variable within patients over time. Lastly, orbital imaging can aid in the diagnosis. Fat replacement of the EOM is commonly observed in hereditary myopathic diseases, such as CPEO. In contrast, inflammation and volume increases are often observed in acquired muscle diseases such as Graves' orbitopathy. In diseases with ophthalmoparesis and ptosis specific patterns of clinical symptoms, the EOM involvement pattern and orbital imaging provide valuable information for diagnosis and could prove valuable in the follow-up of disease progression and the understanding of disease pathophysiology.

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.

The value of SPECT/CT imaging of lacrimal glands as a means of assessing the activity of Graves' orbitopathy

BACKGROUND

Graves' orbitopathy (GO) is an autoimmune disease with mechanical impairment of orbital muscles and lacrimal gland dysfunction. The frequently used methods of assessing GO activity include Clinical Activity Score (CAS), CT, and MRI. These approaches are mainly associated with orbital muscles; however, there are not many studies that focus on the lacrimal gland inflammation of GO patients.

OBJECTIVE

The aim of this study is to assess the usefulness of 99mTc-DTPA single-photon emission (SPE) CT/CT in evaluating the lacrimal gland inflammation in GO, as compared with other methods.

METHODS

A retrospective analysis of 48 patients with active GO compared with 33 controls was conducted. All subjects underwent clinical-endocrinological analyses, CAS evaluation, CT scans, and SPECT/CT examination. Lacrimal gland dimensions were determined and analyzed.

RESULTS

The lacrimal glands in patients with GO were significantly larger in all measured dimensions (P < 0.001) on CT scans relative to those in controls. Increased lacrimal gland diethylene triamine pentaacetic acid (DTPA) uptake ratios (P < 0.001) were displayed in active GO patients compared to controls and were also correlated with thyrotropin receptor antibody levels. The cut-off value for discriminating active and inactive disease was calculated to be 1.735, with specificity of 82.6% and sensitivity of 74.2%. SPECT/CT uptake ratios and CAS values were positively correlated in all GO patients. SPECT/CT uptake ratios were also positively correlated with CT measurements including lacrimal gland volume and coronal width in GO patients.

CONCLUSIONS

These data indicated that lacrimal gland SPECT/CT images can serve as a good tool for assessing the inflammation and disease activity of GO.

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

PURPOSE

Fatty infiltration of the extraocular muscles has been described radiographically in patients with thyroid eye disease (TED), yet it has not been studied on a large scale nor quantified. Our purpose was to define and characterize this entity in patients with TED.

METHODS

An IRB-approved cross-sectional retrospective review of medical records identified patients with a clinical diagnosis of TED and at least one CT of the orbits. A 2:1 age and sex-matched control population consisted of patients without a history nor radiographic evidence of orbital disease or systemic thyroid abnormality. The presence of fatty infiltration in each extraocular rectus muscle was defined using Hounsfield units (HU). Laterality, muscles involved, and pattern of fatty infiltration were also evaluated. Student's t-tests, Chi-square, and Fisher's exact tests were used to compare TED and control groups.

RESULTS

The study population consisted of 252 patients with TED and 504 age and sex-matched controls. Fatty infiltration was significantly more prevalent in TED patients (36/252, 14.3%) compared to controls (11/504, 2.2%) (p < .001). The mean density of fat infiltration was significantly lower in TED patients (-40.4 HU) than controls (-34.8 HU) (p = .048). In TED patients, the frequency of muscle involvement was inferior rectus (61.8%), lateral rectus (19.7%), superior rectus (11.8%) and medial rectus (6.6%), which was not significantly different than controls (p > .05). Most muscles (88.2%) in the TED group exhibited a heterogeneous pattern of infiltration, which did not differ from controls (p = .34).

CONCLUSIONS

This study characterizes fatty infiltration of the extraocular muscles in patients with TED.

Old Bottle, New Wine: Diplopia Sans Proptosis as the Sole Presentation of Thyroid Orbitopathy

Thyroid orbitopathy holds a dominant place in the list of causes for external ophthalmoplegia and is commonly accompanied by eye surface signs such as congestion, lacrimation, and proptosis. An elderly male presented to us with painless diplopia in the absence of proptosis, conjunctival congestion, tearing or irritative symptoms. He had bilateral complete external ophthalmoplegia. He was evaluated to have hypothyroidism with elevated anti-thyroid peroxidase antibodies. MRI revealed bulky extraocular muscles in a pattern of sparing of tendinous insertions, highly suggestive of thyroid orbitopathy. He was managed with IV steroid pulse and thyroxine supplementation with minimal improvement. Through this case report, we highlight an unusual presentation of thyroid eye disease in the form of isolated diplopia, in the absence of other usual eye signs. We also emphasize the characteristic typical neuroimaging signs, such as the 'Coca Cola bottle' sign, which strongly augments the diagnosis in an atypical setting.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

KEY POINTS

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

The feasibility of quantitative MRI of extra-ocular muscles in myasthenia gravis and Graves' orbitopathy

Although quantitative MRI can be instrumental in the diagnosis and assessment of disease progression in orbital diseases involving the extra-ocular muscles (EOM), acquisition can be challenging as EOM are small and prone to eye-motion artefacts. We explored the feasibility of assessing fat fractions (FF), muscle volumes and water T2 (T2_water ) of EOM in healthy controls (HC), myasthenia gravis (MG) and Graves' orbitopathy (GO) patients. FF, EOM volumes and T2_water values were determined in 12 HC (aged 22-65 years), 11 MG (aged 28-71 years) and six GO (aged 28-64 years) patients at 7 T using Dixon and multi-echo spin-echo sequences. The EOM were semi-automatically 3D-segmented by two independent observers. MANOVA and t-tests were used to assess differences in FF, T2_water and volume of EOM between groups (P < .05). Bland-Altman limits of agreement (LoA) were used to assess the reproducibility of segmentations and Dixon scans. The scans were well tolerated by all subjects. The bias in FF between the repeated Dixon scans was -0.7% (LoA: ±2.1%) for the different observers; the bias in FF was -0.3% (LoA: ±2.8%) and 0.03 cm³ (LoA: ± 0.36 cm³ ) for volume. Mean FF of EOM in MG (14.1% ± 1.6%) was higher than in HC (10.4% ± 2.5%). Mean muscle volume was higher in both GO (1.2 ± 0.4 cm³ ) and MG (0.8 ± 0.2 cm³ ) compared with HC (0.6 ± 0.2 cm³ ). The average T2_water for all EOM was 24.6 ± 4.0 ms for HC, 24.0 ± 4.7 ms for MG patients and 27.4 ± 4.2 ms for the GO patient. Quantitative MRI at 7 T is feasible for measuring FF and muscle volumes of EOM in HC, MG and GO patients. The measured T2_water was on average comparable with skeletal muscle, although with higher variation between subjects. The increased FF in the EOM in MG patients suggests that EOM involvement in MG is accompanied by fat replacement. The unexpected EOM volume increase in MG may provide novel insights into underlying pathophysiological processes.

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.

Management of graves myopathy: Orbital imaging in thyroid-related orbitopathy

A broad understanding of the different imaging modalities used to assess the physiologic changes seen in Graves' orbitopathy complement clinical examination. Subtle applications of radiographic imaging techniques allow for a better understanding of the overall physiology of the orbit, quantify progression of disease, and differentiate it from orbital diseases with overlapping features. A nuanced approach to interpreting imaging features may allow us to delineate inactive from active thyroid eye disease, and advances within this field may arm clinicians with the ability to better predict and prevent dysthyroid optic neuropathy.

Characterizing Intraorbital Optic Nerve Changes on Diffusion Tensor Imaging in Thyroid Eye Disease Before Dysthyroid Optic Neuropathy

OBJECTIVE

The aim of this study was to determine whether the optic nerve is affected by thyroid eye disease (TED) before the development of dysthyroid optic neuropathy with diffusion-tensor imaging (DTI).

METHODS

Twenty TED patients and 20 controls were included. The mean, axial, and radial diffusivities and fractional anisotropy (FA) value were measured at the optic nerves in DTI. Extraocular muscle diameters were measured on computed tomography. The diffusivities and FA of the optic nerves were compared between TED and controls and between active and inactive stages of TED. The correlations between these DTI parameters and the clinical features were determined.

RESULTS

The mean, axial, and radial diffusivities were lower in TED compared with the controls (P < 0.05). In contrast, FA was higher in TED (P = 0.001). Radial diffusivity was lower in the active stage of TED than the inactive stage (P = 0.035). The FA was higher in the TED group than in the control group (P = 0.021) and was positively correlated with clinical activity score (r = 0.364, P = 0.021), modified NOSPECS score (r = 0.469, P = 0.002), and extraocular muscle thickness (r = 0.325, P = 0.041) in the TED group. Radial diffusivity was negatively correlated with modified NOSPECS score (r = -0.384, P = 0.014), and axial diffusivity was positively correlated with exophthalmos degree (r = 0.363, P = 0.025).

CONCLUSIONS

The diffusivities and FA reflected changes in the optic nerve before dysthyroid optic neuropathy in TED. The FA, in particular, reflected TED activity and severity.

Diagnostic imaging in neuro-ophthalmology

Neuro-ophthalmology is a field combining neurology and ophthalmology that studies diseases that affect the visual system and the mechanisms that control eye movement and pupil function. Imaging tests make it possible to thoroughly assess the relevant anatomy and disease of the structures that make up the visual pathway, the nerves that control eye and pupil movement, and the orbital structures themselves. This article is divided into three sections (review of the anatomy, appropriate imaging techniques, and evaluation of disease according to clinical symptoms), with the aim of providing useful tools that will enable radiologists to choose the best imaging technique for the differential diagnosis of patients' problems to reach the correct diagnosis of their 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.

Ophthalmic manifestations of systemic diseases--part 2: metabolic, infections, granulomatoses, demyelination, and skeletal dysplasias

The orbit and globe can be secondarily involved in various systemic diseases. These range from tumor and tumorlike conditions, metabolic, infective, inflammatory, granulomatous demyelinating diseases, and skeletal dysplasias. In this article, we discuss the imaging appearances of the remaining systemic pathologies affecting the orbit such as (1) endocrine or metabolic, (2) infectious, (3) inflammatory or granulomatous, (4) demyelinating diseases, and (5) skeletal dysplasias. As the imaging appearances of various systemic diseases tend to overlap, we also introduce a list of pattern-based systemic differential diagnoses for commonly encountered orbital imaging findings. Awareness of the imaging appearances of the various ophthalmic manifestations of systemic diseases can help a radiologist to suggest the most appropriate differential diagnosis to guide further workup and facilitate correct treatment.

Magnetic resonance imaging with diffusion-weighted imaging in the evaluation of thyroid-associated orbitopathy: getting below the tip of the iceberg

OBJECTIVES

To compare extraocular muscles (EOMs) T2, post-contrast T1 (T1Gad) signal intensity ratios (SIRs) and normalized-apparent diffusion coefficient (n-ADC) values in patients with thyroid-associated orbitopathy (TAO) at different phases of activity and severity and correlate MRI modifications to clinical evolution during follow-up.

METHODS

A total of 74 TAO patients were classified as active or inactive on the basis of the clinical activity score (CAS). Severity of EOM impairment was evaluated by assigning a functional score to each rectus. T2, T1Gad SIRs and n-ADC of EOMs were compared in patients with active inflammation, those with inactive disease and 26 healthy controls, and correlated with clinical scores. MRI parameter variation was correlated with clinical modifications during follow-up.

RESULTS

All MRI parameters in TAO EOMs were significantly higher than in healthy subjects and correlated with muscle dysfunction and CAS. EOMs of active patients showed higher T2 and T1Gad SIRs than those with inactive disease. The T2 SIR and n-ADC of normally functioning TAO EOMs were higher than those of healthy controls. SIRs decreased in clinically improved and clinically stable EOMs after therapy.

CONCLUSIONS

T2 SIR, T1Gad SIR and n-ADC are objective measures of activity and severity of EOMs in TAO patients. MRI shows clinically silent muscle involvement and modifications.

KEY POINTS

• MRI and DWI measures are objective, quantitative parameters of TAO activity and severity • MRI and DWI measures significantly correlate with clinical scores in TAO patients • MRI and DWI can identify clinically silent inflammation of deep orbital structures • MRI and DWI can depict subclinical modifications during follow-up • MRI and DWI may aid clinicians in choosing the most appropriate treatment.

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.