USG plays an important role in the detection of subclinical neck nodes (inflammatory or neoplastic). The ease and wide availability of this modality makes it the natural choice for initial evaluation.
CT and MR are generally preferred for the assessment of advanced neck disease (both inflammatory and neoplastic).
Additional advantage of CT and MR in a suspected case of metastatic cervical lymphadenopathy is to aid in the detection of a possible primary.
PET-CT is more sensitive and preferred in the evaluation of metastasis from unknown primary (MUO). It is also the preferred modality in post-CTRT and postsurgical nodal relapse to differentiate recurrence from fibrosis and in the staging of lymphomas.