γγThe significance of residual thyroid gland cleared by iodine 131 (1) Reduce the recurrence rate and metastasis possibility of thyroid cancer, and reduce the mortality rate (2) Improve the iodine uptake function of metastatic foci of thyroid cancer: facilitate the detection and treatment of metastatic foci (3) Facilitate follow-up: after clearing the thyroid tissue, cut off the normal source of thyroglobulin (TG), improve the detection of recurrence and metastatic foci by TG, and facilitate the follow-up of disease with TG development.γγ(4) Whole-body imaging after iodine 131 treatment can detect small metastases in the thyroid gland, which is helpful for the formulation of patient treatment and follow-up plans.