Assessment of optic nerve compression in Graves' ophthalmopathy. The usefulness of a quick T1-weighted sequence

Computed tomography and magnetic resonance imaging approaches to Graves' ophthalmopathy: a narrative review

Graves' ophthalmopathy (GO) affects up to 50% of patients with Graves' disease (GD) ranging from mild ocular irritation to vision loss. The initial diagnosis is based on clinical findings and laboratory tests. Orbital imaging, such as magnetic resonance imaging (MRI) and computed tomography (CT), is an important tool to assess orbital changes, being also useful for understanding disease progression and surgical planning. In this narrative review, we included 92 studies published from 1979 to 2020 that used either MRI and/or CT to diagnose and investigate GO, proposing new methods and techniques. Most of the methods used still need to be corroborated and validated, and, despite the different methods and approaches for thyroid eye disease (TED) evaluation, there is still a lack of standardization of measurements and outcome reports; therefore, additional studies should be performed to include these methods in clinical practice, facilitating the diagnosis and approach for the treatment of TED.

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.

Eyeball muscles' diameters versus volume estimated by numerical image segmentation

PURPOSE

To determine the clinical usefulness of the numerical segmentation image technique (NSI) in estimating the volume of extraocular muscles and to compare this value to widely used measurements of single diameters of the muscles.

METHODS

Forty-five patients underwent magnetic resonance examinations in 1.5-T scanner. SE T1 sequences in transversal and coronal planes were provided and data were sent to a personal computer, where the degree of exophthalmos, horizontal diameter of medial rectus muscles, and vertical diameter of inferior rectus muscles were determined on the basis of two-dimensional images. The quantity estimation of all eye muscles volumes using NSI application in three-dimensional space was carried out with use of level set segmentation algorithm.

RESULTS

A strong correlation between the total eye muscle volume and degree of exophthalmos was determined. The usefulness of measuring single diameters for estimating the muscles' enlargement was confirmed. The difference between a single muscle's volume and its width also was confirmed. Estimates of muscle volume correlate with the degree of exophthalmos more accurately than measurements of single diameters.

CONCLUSIONS

The NSI technique is a clinically useful application, providing objective data calculated individually for each orbit. It allows an objective estimation of the pathologic processes leading to exophthalmos and may be especially helpful in monitoring discrete changes in the muscles volume during treatment.

Graves ophthalmopathy

Graves ophthalmopathy (GO) is an autoimmune disease that typically affects the thyroid gland and the orbit. The roles of the thyroid stimulating hormone receptor and cellular and humoral immunity in the pathogenesis of GO are being investigated. Investigators are gaining insights into the epidemiology of GO as it relates to other ocular and autoimmune diseases. Several possible tools for assessing GO disease activity are being studied. Medical and radiation therapy for GO recently have been evaluated prospectively. Orbital surgeons continue to refine orbital decompression techniques to improve patient outcomes and minimize surgical complications.