Diagnostic Performance of Ultrasound in Neck Node NI-RADS Category 2.

[BACKGROUND AND PURPOSE] The Neck Imaging Reporting and Data System (NI-RADS) scoring system standardized imaging surveillance of head and neck (H&N) cancer with risk classification. A nodal NI-RADS 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 is recommended. The unclear follow-up imaging findings and/or mild FDG uptake raise the patient's anxiety about potential delay in diagnosis and intervention while adding high imaging costs. Therefore, at our institution, diagnostic ultrasound (US)/US-guided fine-needle aspiration (US-FNA) is incorporated into our paradigm. We aim to evaluate US performance in nodal NI-RADS 2 on CECT as an 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 neck CECT, and a neck US/US-FNA performed within 3 months afterward for evaluation of the NI-RADS 2 node. We categorized US/US-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. Eighteen (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. Two 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 NI-RADS 2, surpassing the published rate of 14.3%. The sensitivity, accuracy, and negative predictive value 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.