Clinical significance of diffuse hepatic visualization and thyroid bed uptake on post-ablative iodine-131 whole body scan in differentiated thyroid cancer.

ABSTRACT

BACKGROUND: The aim of this study was to investigate whether diffuse hepatic and thyroid bed uptake of (131)I on post-ablative whole body scans (PAWBS) of patients with differentiated thyroid cancer (DTC) have any relevance for clinical outcome and parameters. PATIENTS AND METHODS: We retrospectively reviewed 838 patients with DTC, who were treated at Pusan National University Hospital from 2004 to 2009. Grades of hepatic and thyroid bed uptake on (131)I whole body scan were classified from 0 to 3 by visual assessment. Recurrence-free survival was evaluated with the Kaplan-Meier method and Cox regression analysis. RESULTS: Male patients having tumors larger than 4 cm (p = 0.005), multiple tumor foci (p < 0.001), involved margins (p = 0.006), and a higher TNM stage (p < 0.001) were more likely to relapse. Thyroid bed grade (p < 0.001) and liver uptake grade (p = 0.002) were also revealed as significant prognostic factors. Intense thyroid bed uptake and faint hepatic activity were related to poor prognosis. CONCLUSIONS: We suggest that increased retention of (131)I in the thyroid bed and less visualization of liver on PAWBS mean poor prognosis. This would be related to the amount of remnant thyroid tissue and ineffective destruction of it.