Diagnostic Performance of Ultrasound in Neck Node NIRADS Category 2.

Background and purpose: The NI-RADS scoring system standardized imaging surveillance of head and neck (H&N) cancer with risk classification. A nodal NIRADS score of 2 on contrast-enhanced CT (CECT) of the neck indicates low suspicion for recurrence/persistent disease and close follow-up or addition of PET are recommended. The unclear follow-up imaging findings and/or mild FDG uptake raise patient's anxiety of potential delay in diagnosis and intervention while adding high imaging cost. Therefore, at our institution, diagnostic US/US-guided fine needle aspiration (US-FNA) is incorporated in our paradigm. We aim to evaluate US performance in nodal NI-RADS 2 on CECT as alternative valuable tool in surveillance imaging guidelines.

Materials and methods: We conducted a retrospective database search (2019-2024) for patients with primary H&N cancer (excluding thyroid cancer and melanoma), a single index neck node NI-RADS 2 on surveillance CECT neck, and a neck US/US-FNA performed within 3 months afterwards for evaluation of the NI-RADS 2 node. We categorized US/US-guided FNA results as positive or negative and reviewed clinical and imaging follow-up, management and nodal disease status up to 1 year following US. The incidence of nodal recurrence and US diagnostic performance were evaluated.

Results: Of 90 patients, 36 (40%) had normal diagnostic US with no FNA performed and were thus considered negative, and 54 patients (60%) had abnormal US and hence concurrent US-FNA. 18 (33.3%) US-FNAs were positive for tumor; 27 with normal lymphoid tissue and 9 with indeterminate cytology (no viable malignant cells, acellular or atypia) were considered negative (66.7%). All positive US-FNAs resulted in management changes. 2 patients with normal diagnostic US, 1 with negative FNA and 1 with indeterminate FNA developed recurrence in these nodes within 1 year. The incidence of US-detected malignancy was 20% in patients with a nodal NIRADS 2, surpassing the published rate of 14.3%. The sensitivity, accuracy and NPV of US/US-FNA in detecting tumor recurrence/persistence in nodal NI-RADS 2 are 81.8%, 95.6% and 94.4% respectively.

Conclusions: Ultrasound demonstrated good diagnostic performance in the detection of nodal recurrence in patients with NI-RADS 2 on CECT. Its role as an alternative tool in surveillance should be considered.

Abbreviations: CECT = contrast-enhanced CT; CEMR = contrast-enhanced MR; ENE = extranodal extension; FNA = fine-needle aspiration; NI-RADS = Neck Imaging Reporting and Data System; NPV = negative predictive value; PPV = positive predictive value; SCC = squamous cell carcinoma; RVU = relative value units; US = ultrasound.