The relationship between I-131 uptake in postoperative residue thyroid tissue and absorbed doses calculated with MIRDOSE3 and pre-ablation thyroglobulin levels in patients with differential thyroid cancer: A retrospective comparison study

Abstract

Objective: The aim of this study was to compare I-131 uptake in postoperative residue thyroid tissue and absorbed doses calculated with MIRDOSE3 and pre-ablation thyroglobulin levels in patients with differential thyroid cancer and was to investigate whether there is a relationship in terms of effectiveness to treatment efficacy. Method: Seventy-four patients were included in the study. Serum thyroglobulin and thyroid stimulating hormone levels before ablation were measured in patients. Uptake values were calculated using I-131 whole body scan scintigraphy images taken on the 8th day after ablation. The findings were evaluated with low dose I-131 whole body scan scintigraphy at 8th-12th months after ablation. Also the effective half-life of I-131, cumulative activity and I-131 residence time were calculated for each patient. The values found were used in the MIRDOSE3 program to calculate total body absorptive doses and comparison was made between the parameters. Results: Thyroglobulin values and uptake values were compared with sperman analysis. There was intermediate correlation between them (r = 0.616, p = 0.01). There was a low correlation in the negative direction between thyroid stimulating hormone levels and uptake values of patients before ablation (r =-0.218, p = 0.05). In 74 patients 8th-12th. Month whole body scan scintigraphy and thyroglobulin results are evaluated; 3 (4.1%) patients were not complete ablated and 71 patients (95.9%) were complete ablated. There was a significant difference only in the thyroglobulin value between complete ablated and non-ablated patient groups (p =0.001). There was a low correlation between absorbed doses and thyroglobulin values (r = 0.212, p = 0.05). Conclusions: As a result, we observed that thyroglobulin values measured before I-131 treatment inform about residual tissue after surgery and residual tissue size may affect treatment efficacy. We also think that attention should be paid to the treatment and follow-up protocol in terms of complete ablation success in patients with high pre-treatment thyroglobulin values.