Objective:
To determine the degree of agreement between measurements of the optic nerve sheath diameter by ultrasonography (US) and magnetic resonance imaging (MRI).
Material and Methods:
72 eyes of 36 patients who had undergone cranial MRI study for various reasons and undergone orbita USG maximum 1 week after MRI, were involved in the study. During study, only the best-quality MRI and ultrasound images were used.All subjects ONSD were measured by transbulbar sonography (9.11 and 13 MHz) and 1.5 Tesla MRI (axial plane) 3 mm below the globe. The measurements of ONSD were compared for agreement between the 2 modalities using the method by ICC and Bland-Altman.
Results:
ONSD measurements made with 9 MHz linear probe were found as 6.04±0.75 (4.4-7.3 mm), with 11 MHz probe as 6.08±0.74 (4-7 mm), with 13 MHz probe as 6.06±0.73 (4.3-7.3 mm) and with MRI found as 6.16±0.73 (5-7 mm). Significant correlation was found between MRI and 9 MHz (97.7 %, ICC: 0.977; p<0.01), 11 MHz (99 %, ICC: 0.990; p<0.01) and 13 MHz (98.6 %, ICC: 0.986; p<0.01) linear probe measurements.
Conclusion:
When good quality USG images that correctly depict retrobulbar anatomic structures exist, ONSD can be accurately measured with USG and there is a good correlation between transbulbar sonography and MRI measurements of the ONSD.
Keywords: optic nerve sheath diameter, transbulbar sonography, MRI