Strain and Shear Wave Elastography in Diagnosis of Retrobulbar Neuritis

Abstract

In the early stages of retrobulbar neuritis (RN), the optic disc appears normal on ophthalmoscopy. Therefore, the diagnosis of RN is usually made clinically. However, imaging tools are needed for precise diagnosis of RN, and usually MRI is used. In this study, we investigated the diagnostic performance of strain elastography (SE) and shear wave elastography (SWE) in patients with RN. Elastography is a new sonographic technique and a noninvasive ultrasound method for evaluating the elastic properties of tissues based on static compression: the elastographic techniques of SE compress the tissues axially, and SWE uses waves that are generated by transducers and interact with the tissue. The study included 40 eyes of 20 patients with sudden visual loss, who were diagnosed with RN. The eyes of the patients were divided into 2 groups: the eye with a diagnosis of RN was the group of RN eyes, and the healthy second eye was the group of control eyes. Ophthalmologic examination, orbital and brain MRI, SE, and SWE were performed. SE color mapping was divided into 3 types: blue-hardest tissue (Type 1), blue/green-hard tissue (Type 2), and green-intermediate tissue (Type 3). All patients were treated with high-dose corticosteroids. The measurements of SE and SWE were made immediately after diagnosis and 1 month after treatment. The mean age of 11 male and 9 female patients was 38.3 ± 12.2 years. At the time of diagnosis, the mean shear wave values for the control eyes were 18.47 ± 7.26 kPa (kilopascals), and the mean shear wave values for the RN eyes were 37.21 ± 8.24 kPa. There was a statistically significant difference between the control and RN eyes at the time of diagnosis (P < 0.001). The mean shear wave value was 19.92 ± 4.77 kPa in the RN eyes after treatment. There was a statistically significant difference in values at the time of diagnosis and after treatment (P < 0.001). Strain types found in the RN eyes before treatment were Type 1 in 60% of eyes, Type 2 in 25%, and Type 3 in 15%; at the end of the treatment, Type 2 was observed in 25% of eyes and Type 3 in 75%, while Type 1 was not observed. SE and SWE may be important alternative diagnostic tools in the diagnosis of RN.