Enhancement Pattern of Normal Extraocular Muscles in Dynamic Contrast-Enhanced Mr Imaging with Fat Suppression

Abstract

Purpose: To evaluate the internal structure of normal extraocular muscles on fat-suppressed dynamic contrast-enhanced MR imaging.

Material and Methods: Ten subjects were examined using fat-suppressed dynamic contrast-enhanced MR imaging. We evaluated the enhancement pattern (C-shaped or ring-like) of extraocular muscles and quantified the maximum ratios of enhancement (R_max) and maximum ratios of signal increase (V_max). We also quantified R_max and V_max in the central and peripheral portions of medial rectus muscles.

Results: In the early phase of dynamic contrast-enhanced MR imaging, a C-shaped or ring-like pattern was observed in 100% of inferior rectus, 95% of medial rectus, 55% of superior rectus, 20% of lateral rectus, and 15% of superior oblique muscles. Overall mean R_max and V_max values showed statistically significant differences to the temporal muscles. For the peripheral portion of medial rectus muscles, mean R_max and V_max values were greater than for the central portion.

Conclusion: Using fat-suppressed dynamic contrast-enhanced MR imaging, the C-shape or ring-like internal structure of the extraocular muscles could be visualized, and were considered to reflect their structure of orbital and global layers. Potential usefulness of the fat-suppressed dynamic contrast-enhanced MR imaging for detecting pathological status is suggested.