Normal Magnetic Resonance Contrast Enhancement of Extraocular Muscles: A Quantitative Analysis

The purpose was to evaluate quantitatively the magnetic resonance contrast enhancement of normal extraocular muscles and the use of temporal muscles as a reference of enhancement. Eighty extraocular and 20 temporal muscles were taken into analysis. Before contrast administration, mean intensity of extraocular muscles was found to be higher than that of temporal muscles (p < 0.000). With contrast agent, all extraocular muscles were enhanced more (111% enhancement) than the temporal muscles (45% enhancement, p < 0.000). Lateral recti had the lowest signal intensity, both in pre- and postcontrast images (p < 0.005). Normal extraocular muscles showed prominent enhancement on contrast-enhanced T(1)-weighted images. Temporal muscles were also enhanced in all subjects, urging the observers to compare the enhancement of extraocular muscles not with the latter.