Evaluating the clinical utility of iodine-123 scans in follow-up for differentiated thyroid cancer: a single-centre study.

Objective: To evaluate the impact of iodine-123 (I-123) diagnostic scintigraphy on management outcomes in patients undergoing follow-up for differentiated thyroid carcinoma (DTC), and to assess whether multidisciplinary team (MDT) discussion influences subsequent clinical pathways. Methods: A retrospective analysis was conducted of patients with DTC who underwent I-123 scintigraphy at an NHS trust. Demographic data, scan findings, and subsequent clinical actions were collected. Scans were categorised as MDT endorsed or requested by individual clinicians. Outcomes were assessed by distinguishing initial diagnostic actions prompted by I-123 imaging from definitive management outcomes following completion of downstream investigations. Results: A total of 55 I-123 scans from 51 patients were included. New or abnormal findings were identified in 21 scans (38.2%). Initial diagnostic actions followed 23 scans (41.8%), most commonly further imaging. When management outcomes were reassessed after completion of downstream investigations, no definitive change in management occurred in 40 scans (72.7%), while 13 scans (23.6%) resulted in a definitive management change; in 2 scans (3.6%), outcomes were unclear. MDT-endorsed scans more frequently prompted initial diagnostic actions, although this difference was not statistically significant. Outcomes for MDT-requested scans and individually requested scans were near-identical (definitive change in management in 20% vs 20.7). Conclusions: I-123 scintigraphy can influence clinical decision-making during follow-up of patients with differentiated thyroid cancer, most commonly by prompting further diagnostic investigation. However, definitive changes in management occur in a minority of cases. These findings support a selective rather than routine role for I-123 imaging in follow-up.