Post-Therapeutic I-131 Whole Body Scan in Patients with Differentiated Thyroid Cancer

Therapy with radioiodine (I-131) has been used for patients with well-differentiated thyroid cancer such as papillary and follicular thyroid carcinoma to ablate normal thyroid tissue or to treat metastatic lesions. The improvement of survival rates and decrease of recurrence rates after I-131 therapy has been documented by retrospective studies (Mazzaferri & Jhiang, 1994; Samaan et al., 1992). Even those patients categorized as low risk also had significantly lower recurrence and death rates after they received I-131 (Dietlein et al., 2005). Diagnostic I-123 or I-131 whole body scan (DxWBS) can be performed to detect persistent disease before radioiodine therapy. The post-therapeutic I-131 whole body scan (RxWBS) can be done after administration of therapeutic dose of I-131.