High resolution ultrasound and magnetic resonance imaging of the optic nerve and the optic nerve sheath: anatomic correlation and clinical importance.
OBJECTIVE
We performed a cadaver study to evaluate the accuracy of measurements of the optic nerve and the optic nerve sheath for high resolution US (HRUS) and magnetic resonance imaging (MRI).


METHODS
Five Thiel-fixated cadaver specimens of the optic nerve were examined with HRUS and MRI. Measurements of the optic nerve and the ONSD were performed before and after the filling of the optic nerve sheath with saline solution. Statistical analysis included the calculation of the agreement of measurements and the evaluation of the intraobserver and interobserver variation.


RESULTS
Overall a good correlation of measurement values between HRUS and MRI can be found (mean difference: 0.02-0.97 mm). The repeatability coefficient (RC) and concordance correlation coefficient (CCC) values were good to excellent for most acquisitions (RC 0.2-1.11 mm; CCC 0.684-0.949). The highest variation of measurement values was found for transbulbar sonography (RC 0.58-1.83 mm; CCC 0.615/0.608).


CONCLUSIONS
If decisive anatomic structures are clearly depicted and the measuring points are set correctly, there is a good correlation between HRUS and MRI measurements of the optic nerve and the ONSD even on transbulbar sonography. As most of the standard and cut-off values that have been published for ultrasound are significantly lower than the results obtained with MRI, a reevaluation of sonographic ONSD measurement with correlation to MRI is necessary.
Department of Pediatric Radiology, Städtisches Klinikum Munich Schwabing. steinborn@lrz.tum.de
M
M
Steinborn
J
J
Fiegler
V
V
Kraus
C
C
Denne
A
A
Hapfelmeier
L
L
Wurzinger
H
H
Hahn
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009186:Myelin Sheath / Q000000981:diagnostic imaging*; D009900:Optic Nerve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D012016:Reference Values; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D014463:Ultrasonography / Q000379:methods*