Perineural tumour spread in head and neck cancer: a pictorial review.

Perineural tumour spread in head and neck cancer can be a challenging diagnosis for radiologists; head and neck anatomy is intimidating and perineural tumour spread can be subtle and difficult to detect. It results in significant morbidity for patients, can upstage disease and will frequently result in more prolonged treatment courses. This pictorial review provides a thorough examination of the imaging characteristics of perineural tumour spread in head and neck malignancy. It highlights key imaging features, from initial diagnosis to its post-therapy appearance, emphasising the clinical relevance and role of imaging in post-therapy assessment. Multi-modality imaging examples are included with a focus on magnetic resonance imaging (MRI) and positron-emission tomography (PET)/computed tomography (CT). MRI features of perineural tumour spread include intermediate T2 signal expansion of a nerve, abnormal enhancement extending along a nerve, expansion of a skull or neural foramen and loss of normal fat planes surrounding nerve pathways. 18F-fluorodeoxyglucose (FDG) PET/CT is a useful adjunct to MRI, perineural tumour spread results in abnormal FDG accumulation in a linear fashion anatomically spreading along a nerve pathway. Knowledge of these features and useful check areas will ensure that radiologists can be confident both in making the diagnosis and re-assessment post-therapy. • Perineural tumour spread results in morbidity for patients and can upstage disease. • Fat pad check areas are critical for identifying perineural tumour spread. • 18F-FDG PET/CT is a very useful adjunct to MRI in post-therapy assessment. [ABSTRACT FROM AUTHOR]