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Figures
- Fig 1.
Sagittal midline localizer MR image. Horizontal white lines through the basisphenoid and cranial aspect of the extrinsic tongue muscles serve as an accurate approximation for the CISS craniocaudal slab selection when imaging the facial nerve.
- Fig 2.
Representative sagittal-oblique CISS minimum intensity projection MR image shows the visible course of the facial nerve trunk (curved arrow) from the stylomastoid foramen to the distal aspects of the temporofacial (arrowhead) and cervicofacial (arrow) trunks.
- Fig 3.
Representative segmentations of the left facial nerve of subject 20 with an average Hausdorff distance of 0.64, Dice coefficient of 0.60, length difference of <1%, and segmentation volume difference of 8%. A, Segmentations of observer 1 (green outline) and observer 4 (red outline) superimposed on the CISS image show similar agreement along the main nerve root, bifurcation, and proximal aspects of the temporofacial and cervicofacial roots, with more distal variability along the cervicofacial root, even despite the similar length segmented. B, 3D rendering of the observer 1 segmentation. C, 3D rendering of the observer 4 segmentation. D, Dice overlap map shows the spectrum of agreement, with blue being good agreement and red being poor agreement.
- Fig 4.
Axial CISS images in patients with parotid gland tumors. A, A 55-year-old man with a right parotid gland, 35 × 22 × 44 mm (anteroposterior × transverse × craniocaudal) Warthin tumor (arrowheads) and temporofacial (straight arrow) and superiorly displaced cervicofacial (curved arrow) trunks of the facial nerve (straight arrow), apparently deep to the tumor and just posterior to the retromandibular vein. In the operating room, the distal branches of the facial nerve were confirmed to be in the plane of the tumor with distal divisions displaced above and below the tumor and with superior displacement of the parotid plexus. B, An 83-year-old woman with left parotid gland, 23 × 21 × 29 mm poorly differentiated carcinoma with sarcomatoid features (arrowheads) and an apparently expanded facial nerve with irregular margins (arrows) coursing through the tumor, suggestive of perineural tumor invasion. A radical parotidectomy was performed, and pathology analysis confirmed extensive perineural invasion. C, A 32-year-old woman with a left parotid gland 18 × 19 × 24 mm pleomorphic adenoma (arrowheads) extending into the stylomastoid foramen and anteromedially displacing the facial nerve (arrow). Due to these imaging findings, a postauricular infratemporal fossa surgical approach was used, confirming the location of the nerve and confirming impingement of the nerve as it entered the stylomastoid foramen. D, A 75-year-old man with a right parotid gland, 12 × 11 × 19 mm Warthin tumor (arrowheads) just superficial to and between the distal, small-caliber, low-signal cervicofacial trunk of the facial nerve (straight arrow) and high-signal retromandibular vein (curved arrow). This patient has elected observation, and there is thus no surgical confirmation of facial nerve location.
Tables
Parameters for CISS sequence
Parameter TR 4.97 ms TE 2.19 ms Averages 1 Section thickness 0.8 mm FOV 240 × 240 Matrix 320 × 320 Voxel size 0.8 × 0.8 × 0.8 mm Bandwidth 521 Hz/pixel Flip angle 33° Elliptic scanning On Acquisition time 4:44 minutes
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