[Reference line for delineation of the intraparotid facial nerve on MRI]

Exact identification of intraparotid facial nerve is important in surgical management of parotid tumors. To delineate the intraparotid facial nerve on MRI, we proposed a new reference line, which was drawn between the inferior margin of the bone marrow of the atlas and superior margin of the bone marrow of the mandible on midsagittal section. This reference line crossed with orbito-meatal line at the mean angle of 37 +/- 3 degrees. By scanning parallel to this line, intraparotid facial nerve was clearly identified in 19 (79%) of 24 normal parotid glands.