MR imaging of perineural tumor spread.

Perineural tumor spread (PNS) is a common and potentially devastating complication of head and neck cancer. Because perineural tumor spread may be asymptomatic, the radiologist plays a critical role in the evaluation of the head and neck cancer patient. Although PNS may be seen on CT, MR imaging is far more sensitive and is the imaging modality of choice in the evaluation of perineural tumor spread.