Plasma glycosaminoglycans in endocrine ophthalmopathy

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.

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.

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.

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.

The cost of immunosuppressive therapies currently used in patients with thyroid eye disease

Thyroid eye disease (TED) is an inflammatory condition of the orbit occurring in patients with autoimmune disease. In patients with mild TED, the most important therapeutic measure is reassurance. In severe cases, immunosuppressive therapy is the mainstay of treatment and around 10 immunosuppressive regimens have been suggested and used in such patients so far. The efficacy of these regimens varies according to the number of studies that have addressed these issues. "Response" to the treatment is also variably defined. However, to the best of our knowledge, no study has reported on the cost of immunosuppressive therapy in such patients. The aim of this study was mainly to provide information concerning the cost of different immunosuppressive regimens that patients with active thyroid ophthalmopathy undergo in different European countries. We have shown that the cheapest treatment is oral glucocorticoids (GC) and the most expensive is iv immunoglobulins. Cyclosporine is the second cheapest treatment. Radiotherapy plus oral GC have a cost between 850-3200 Euro; while SS analogues (SS-a) are expensive with a cost between 5000-10000 Euro. However, it is worth noting that the patients studied so far in this group were only few and most of them selected on a basis of a positive octreoscan, the cost of which has to be considered when choosing this type of treatment. Germany is by far the most expensive country as regards the costs of the main remedies, whereas Greece is the cheapest. Denmark is the most expensive country concerning radiotherapy, while Germany is the cheapest.

Graves' disease-associated changes in the serum lysosomal glycosidases activity and the glycosaminoglycan content

BACKGROUND

This study was undertaken to elucidate the influence of Graves' hyperthyroidism upon the metabolism of proteoglycans (PGs), the extracellular matrix (ECM) components. We determined the serum activity of lysosomal hydrolases contributing to GAGs degradation (N-acetyl-beta-D-glucosaminidase, beta-D-glucuronidase, beta-D-galactosidase, alpha-D-mannosidase, beta-D-xylosidase and alpha-L-fucosidase). An effect of Graves' hyperthyroidism on total serum GAGs content was also analysed.

METHODS

Blood samples were taken from 30 patients with newly diagnosed Graves' disease, prior to antithyroid treatment and after attainment of euthyroid state, as well as from 30 healthy individuals.

RESULTS

The activity of all investigated enzymes involved in GAGs degradation was found markedly increased in blood serum of patients with hyperthyroidism, except for alpha-D-mannosidase, which was not significantly modified. Antithyroid treatment with thiamazole resulted in normalization of the lysosomal glycosidases activity, so they no longer differed from the healthy subjects. The total glycosaminoglycans content in blood serum of patients with newly diagnosed untreated Graves' disease significantly increased compared to control group. Following thiamazole therapy total serum amount of GAGs decreased significantly, but was still markedly increased as compared to serum of healthy individuals.

CONCLUSIONS

The obtained results indicate that Graves' hyperthyroidism is associated with extracellular matrix components' alterations. Furthermore, we suggest that general increase of the serum lysosomal glycosidases activity and serum GAG concentration may both result from the same reason, i.e. excessive reactive oxygen species formation in the course of hyperthyroidism due to Graves' disease.

Development and validation of a photometric titration method for the quantitation of sodium chondroitin sulfate (bovine) in Cosequin DS chewable tablet

A photometric titration method was developed and validated to quantitate sodium chondroitin sulfate in raw materials and Cosequin DS chewable tablet(1). About 0.1% (w/v) cetylpyridinium chloride was used to titrate sodium chondroitin sulfate with photometric indication at wavelength 420 nm. The standard curves for sodium chondroitin sulfate showed linearity (r> or = 0.99) over the selected concentration range from 0.6 to 1.4 mg/ml. The chewable tablet was ground to fine powder and extracted with water and the resulting solutions filtered through a 0.45 microm membrane filter. Recovery between 97 and 103%,. The intra- and inter- day precision as indicated by the relative standard deviation (R.S.D.) were not greater than 0.33 and 0.78%, respectively. The method was found to be specific and with excellent linearity, accuracy and precision and is well suited for the quantitation of sodium chondroitin sulfate in raw material and Cosequin DS chewable tablet.

Management of Graves' ophthalmopathy: reality and perspectives

Graves' ophthalmopathy is an debilitating disease impairing the quality of life of affected individuals. Despite recent progress in the understanding of its pathogenesis, treatment is often not satisfactory. In mild cases, local therapeutic measures (artificial tears and ointments, sunglasses, nocturnal taping of the eyes, prisms) can control symptoms and signs. In severe forms of the disease (3-5%), aggressive measures are required. If the disease is active, high-dose glucocorticoids and/or orbital radiotherapy, or orbital decompression represent the mainstay of treatment. If the disease is severe but inactive, orbital decompression is preferred. Novel treatments such as somatostatin analogs or intravenous immunoglobulins are under evaluation. Rehabilitative (extraocular muscle or eyelid) surgery is often needed after treatment and inactivation of eye disease. Correction of both hyper- and hypothyroidism is crucial for the ophthalmopathy. Antithyroid drugs and thyroidectomy do not influence the course of the ophthalmopathy, whereas radioiodine treatment may cause the progression of preexisting ophthalmopathy, especially in smokers. The exacerbation, however, is prevented by glucocorticoids. In addition, thyroid ablation may prove beneficial for the ophthalmopathy in view of the pathogenetic model relating eye disease to autoimmune reactions directed against antigens shared by the thyroid and the orbit.

An ultrastructural and systemic analysis of glycosaminoglycans in thyroid-associated ophthalmopathy

PURPOSE

To determine the ultrastructural localisation of glycosaminoglycans (GAGs) in the extraocular muscles (EOMs) of patients with thyroid-associated ophthalmopathy (TAO) and to see whether the quantity and type of GAGs present in blood and urine are markers of the disease.

METHODS

Biopsies of affected EOMs were taken and studied by transmission electron microscopy (TEM). These were either fixed conventional for TEM, or in 0.5% tannic acid and others for immunogold staining. Serum hyaluronan (HA) was measured using a radioimmunoassay in patients with TAO as well as control subjects, and urinary GAG levels assessed by photometric quantitation of hexuronic acid after reaction with carbazole. The excretion pattern of the urinary GAGs was determined by discontinuous electrophoresis.

RESULTS

TEM showed that there is a marked expansion of the endomysial space in TAO EOM biopsies as compared with non-TAO strabismus specimens. This is caused by an increased number of collagen fibres, interspersed with a granular amorphous material surrounding striated collagen fibres shown to be hyaluronan by immunogold staining. In contrast, serum hyaluronan concentrations were similar in TAO and control patients, although there was a statistically significant difference in the urinary GAG excretion between the two groups of patients examined. By discontinuous electrophoresis, chondroitin sulphate and heparan sulphate were present in both patients and controls.

CONCLUSION

GAGs and in particularly HA are present at the EOM level in patients with recently inactive TAO. However, serum levels of HA and urinary GAGs are not sensitive indicators for their presence within the EOMs.

[Endocrine orbitopathy 1998]

BACKGROUND

Ophthalmopathy is the most common extrathyroidal manifestation of Graves' disease, also called thyroid-associated ophthalmopathy.

CLINICS

This autoimmune disorder is characterized by a lymphocyte infiltration of the retrobulbar space. Activated T cells react with the target organ and secrete cytokines, leading to accumulation of glycosaminoglycans, interstitial edema of the peri- and retrobulbar tissue and enlargement of the extraocular muscles. During the inflammatory stage, the increased orbital pressure results in the clinical manifestation of the eye disease.

DIAGNOSIS AND TREATMENT

Thus, therapeutic immunosuppression is often used initially, and by suppressing inflammatory changes, it can result in subjective and objective improvement of the thyroid eye disease. In recent years, new pathogenetic aspects and clinical randomized trials led to modified therapy concepts.

CONCLUSION

Interdisciplinary management is recommended for rapid diagnosis and effective therapy of patients with thyroid-associated ophthalmopathy.

Somatostatin analogues in the treatment of thyroid eye disease

Recent studies have shown successful therapy with the long-acting somatostatin (SM) analogues octreotide and lanreotide in patients with thyroid eye disease (TED). In one such study it was also found that response to low-dose octreotide treatment (300 microg) in these patients was correctly predicted by [111In-DTPA-D-Phe1]-octreotide scintigraphy and concluded that this parameter should be used as a predictive test of the effectiveness of treatment with nonradioactive octreotide. It has also been suggested that octreoscan-111 may be seen as a parameter of disease activity in TED. However, it remains to be clarified whether octreoscan-111 predicts the therapeutic outcome better than the clinical activity score, or magnetic resonance imaging (MRI) or finally measurement of glucosaminoglycan (GAG) in the plasma and/or urine. The exact mechanism of action of SM analogues has not yet been fully clarified. Three explanations may be offered. First, SM suppresses insulin-like growth factor 1 (IGF-1) activity and inhibits IGF-1-mediated effects. A second possible mechanism could be the direct inhibition of the release of cytokines from T-lymphocytes, and finally, SM analogues may act on target cells through specific cell surface receptors. In view of the encouraging therapeutic results reported thus far in several studies, SM analogues may provide a valuable therapeutic alternative to corticosteroids, especially in patients who cannot tolerate the latter. However, further prospective, placebo-controlled studies with a large number of patients are needed before we can reach final conclusions.

Beneficial effect of pentoxifylline on thyroid associated ophthalmopathy (TAO)*: a pilot study

We have previously found that pentoxifylline (Ptx) inhibited cytokine induced HLA-DR expression and glycosaminoglycan (GAG) synthesis by retroorbital fibroblasts. We have now tested the clinical efficacy of Ptx in treating TAO. Ten patients with moderately severe ophthalmopathy were selected for study. All patients were euthyroid before and during the 12 weeks of the Ptx therapy. Serum GAG, TNF-alpha, anti-TSH-receptor, anti-eye muscle, anti-thyroglobulin and anti-thyroid peroxidase antibodies were determined sequentially. At the end of 12 weeks eight of the ten patients showed improvement in soft tissue but not in proptosis or extraocular muscle involvement. At baseline the levels of GAG (5.2+/-0.92 mg/dl v.s. 0.7+/-0.14 mg/dl, p<0.001) and TNF-alpha (33.6+/-6.6 pg/ml v.s. 5.4+/-1.3 pg/ml, p<0.001) were increased in patients compared to controls. They gradually decreased in the eight patients who responded to Ptx: after 4, 8 and 12 weeks of therapy serum GAG was 3.4+/-0.42 mg/dl, 2.5+/-0.77 mg/dl (p<0.01) and 1.1+/-0.2 mg/dl (p<0.001), respectively and serum TNF-alpha was 20.9+/-4.8 pg/ml, 14.9+/-2.2 pg/ml (p<0.05) and 9.7+/-1.8 pg/ml (p<0.01), respectively. Serum GAG and TNF alpha did not fall in the two patients who did not respond. The titre of anti-eye muscle antibodies but not anti-thyroid antibodies were lower at 12 weeks. Ptx has a beneficial effect on inflammatory symptoms of TAO and associated laboratory parameters in the majority of patients.

Role of octreoscan and correlation with MR imaging in Graves' ophthalmopathy

Since the identification of somatostatin receptors on lymphocytes, orbital infiltration with mononuclear cells in Graves' ophthalmopathy has provided a rationale for receptor imaging with the radiolabeled somatostatin analog Octreotide. In 40 patients with Graves' ophthalmopathy and 10 controls, 110 MBq indium-Octreotide were administered i.v., and scans were performed at 4 and 24 h after injection. An uptake ratio between the orbits and the brain was determined. In 20 ophthalmophathy patients, magnetic resonance imaging (MRI) of the orbits was performed and the T2 relaxation time was measured within the rectus muscles. Compared to controls (4 h Octreotide uptake: median 6.0 counts/pixel/MBq, orbit/brain ratio 5.6), ophthalmopathy patients showed a 2- to 3-fold increased uptake (15.8 counts/pixel/MBq vs controls p = 0.0032; ratio 12.6, vs controls p = 0.003). When considering patients with active disease only, a higher uptake was registered (16.8 counts/pixel/MBq vs controls p 0.0048, ratio 15.6 vs controls p = 0.0006). Untreated patients showed a markedly higher uptake (23 counts/pixel/MBq) compared to patients receiving steroid therapy (12.6, p = 0.001). MRI of the orbit revealed a correlation between T2 relaxation time of the eye muscles and orbital uptake of Octreotide (p < 0.001).