The hypoglossal canal: normal MR enhancement pattern.
OBJECTIVE
To review the anatomy of the hypoglossal canal and present the normal precontrast and postcontrast MR appearance of axial posterior fossa images.


METHODS
Thirty-one axial MR examinations of the normal posterior fossa were retrospectively reviewed.


RESULTS
The hypoglossal canals are well seen on 3-mm-thick axial MR images of the posterior fossa (28 [90%] of 31 patients). Symmetric intense intracanalicular enhancement after intravenous administration of gadopentetate dimeglumine is routine, typically with minor anterior extension into the nasopharyngeal region (28 [100%] of 28). A linear filling defect traversing the enhanced canal often is seen (21 [75%] of 28) and may represent hypoglossal nerve rootlets. Circumferential enhancement of the meninges at the level of the foramen magnum was a common finding (19 [64%] of 28).


CONCLUSIONS
Enhancement within the hypoglossal canal with anterior extension beneath the skull base is a normal finding. This pattern is characteristic enough on MR imaging to aid interpretation of skull base lesions and to exclude the possibility of a mass within the hypoglossal canal.
Voyvodic
F
F
Department of Radiology, Flinders Medical Centre, Bedford Park, South Australia.
Whyte
A
A
Slavotinek
J
J
D000328:Adult; D000368:Aged; D002552:Cerebral Ventricles / Q000033:anatomy & histology*; D003287:Contrast Media; D003388:Cranial Fossa, Posterior / Q000033:anatomy & histology*; D004338:Drug Combinations; D005260:Female; D005539:Foramen Magnum / Q000033:anatomy & histology*; D019786:Gadolinium DTPA; D006801:Humans; D007002:Hypoglossal Nerve / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008536:Meglumine; D008875:Middle Aged; D009942:Organometallic Compounds; D004369:Pentetic Acid / Q000031:analogs & derivatives; D012016:Reference Values; D012189:Retrospective Studies; D013126:Spinal Nerve Roots / Q000033:anatomy & histology
D003287:Contrast Media; D004338:Drug Combinations; D009942:Organometallic Compounds; D008536:Meglumine; D004369:Pentetic Acid; D019786:Gadolinium DTPA