18F-FDG PET/CT findings of perineural involvement in head and neck malignancies

Learning Objectives 1. Understand the prognostic value of perineural invasion in head and neck cancer. 2. Recognize different imaging patterns of FDG uptake in perineural invasion on head and neck malignancies. 3. Correlate PET/CT with other cross sectional (CT and MRI) modalities.

Perineural invasion (PNI) is the process of neoplastic invasion of nerves and is an under-recognized route of metastatic spread. It is emerging as an important pathologic feature of many malignancies, particularly in head and neck cancers, associated with decreased survival, increased and earlier recurrence. PNI status often significantly affects surgical strategies and adjuvant treatments in head and neck cancers. MRI has been the gold standard imaging modality for the evaluation of PNI. FDG PET/CT has been increasingly used for staging and restaging of head and neck cancers. Beyond locoregional disease and lymph node metabolic characterization, different PET imaging patterns suggesting PNI can also be identified. Our goal is to demonstrate different examples of PNI visualized by PET/CT and the correlation with other cross sectional imaging modalities, such as CT and MRI. Also, increased awareness of such patterns can be helpful in PNI evaluation in conjunction with other modalities. We will use cases collected in our institution in a case-based approach. The key points of this exhibit are: (1) PNI is poor prognostic indicator in head neck malignancies. (2) PET/CT findings can suggest PNI and could be described as such. (3) Cross sectional correlation is important for cases suggestive of PNI