Contribution of neck ultrasonography to patient management in patients with differentiated thyroid carcinoma with excellent response to therapy.

Purpose: To assess the contribution of intense neck ultrasonography (US) follow-up in the clinical management of differentiated thyroid carcinoma (DTC) patients with the American Thyroid Association (ATA) low-intermediate-risk of recurrence and an excellent response after total thyroidectomy and radioiodine therapy.

Materials and methods: Medical records of patients who underwent serial follow-up neck US examinations between 1996 and 2022 were analyzed retrospectively. The utility of serial US examinations in detecting structural recurrence was assessed in all patients and different subgroups-categorized per the initial risk of recurrence and stimulated thyroglobulin (sTg) level at 1-year response assessment.

Results: Among 2823 US examinations in 296 patients, 2 (0.1%) were categorized as true-positive, 2670 (94.6%) as true-negative, and 151 (5.3%) as false-positive, whereas no false-negative results were observed. Thus, sensitivity, specificity, positive predictive value (PPV), negative predictive value, and accuracy [confidence interval] in all patients were 100% [34.2-100%], 94.7% [93.8-95.4%], 1.3% [0.36-4.6%], 100% [99.9-100%], and 94.7% [93.8-95.4%], respectively. Non-significant higher PPVs were calculated in intermediate-risk patients and patients having sTg ≥0.1 ng/mL, while slightly lower specificity and accuracy were demonstrated in the former group. No recurrence was identified in patients with a low risk of recurrence and those having sTg <0.1 ng/mL.

Conclusion: Frequent US examination yields remarkably low PPVs in identifying recurrences in ATA low-intermediate-risk patients with DTC and attaining excellent response after total thyroidectomy and radioiodine ablation. Therefore, US surveillance protocol should be individualized per the initial risk of recurrence and Tg levels at response assessment.