Evaluation of the optic nerve using strain and shear wave elastography in patients with multiple sclerosis and healthy subjects

Aims: Our aim was to evaluate the elasticity features of the optic nerve using strain (SE) and shear wave elastography (SWE) in multiple sclerosis (MS) patients in comparison with healthy subjects. Material and methods: One hundred and seven optic nerves from 54 MS patients and 118 optic nerves from 59 healthy subjects were examined prospectively by SE and SWE. Optic nerves were divided into three types in accordance to the elasticity designs, as follows: type 1 predominantly blue (hardest tissue); type 2 predominantly blue/green (hard tissue); and type 3 predominantly green (intermediate tissue). Quantitative measurements of optic nerve hardness with SWE were analyzed in kilopascals. Results: Elastographic images from healthy volunteers showed mostly type 3 optic nerves (61.9%); type 2 was also found (38.1%), but type 1 was not observed. Elastographic examination of MS patients showed mostly type 2 optic nerves (88%), while some type 1 (4.6%) and type 3 optic nerves (6.5%) were rarely observed. There was a statistically significant difference in terms of elasticity patterns between patients and healthy volunteers (p<0.001). Statistically significant differences were observed between patients and healthy volunteers in the analysis of SWE values (10.381±3.48 kPa and 33.87±11.64 p<0.001). The receiver operating characteristic curve analysis was perfect (0.993; 95% confidence interval [CI]=0.971–0.999), and a cut-off value of 18.3 kPa shear had very high sensitivity and specificity for the patient group. No significant differences were observed between patients with and without previous optic neuritis. Conclusion: SE and SWE examination findings concerning the optic nerve in MS patients demonstrated remarkable differences according to the healthy group.