The utility of radioiodine whole body scans prior to 131-I ablation in patients with well-differentiated thyroid cancer

Abstract

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Objectives: For patients with well-differentiated thyroid cancer (WDTC), the utility of radioiodine (RAI) whole body scans (RWBS) prior to 131-I ablations is controversial, and the objective of this study was to evaluate that utility. Methods: RWBS performed prior to 131-I ablation from Jul 2000 to Nov 2006 at Wash Hosp Ctr were reviewed retrospectively. Patients were excluded who were strongly suspected of having (1) distant metastases and/or (2) physiological uptake that might alter management prior to the pre-ablation RWBS. RWBSs were performed 24 hours after dosing with 1-4 mCi of I-123 with imaging of the whole body, the thyroid bed/neck with a pinhole collimator, and the neck and chest with a parallel-hole collimator. One reviewer (dvn) evaluated each set of scans blindly using 5 criteria: (1) # of foci of RAI uptake in the neck, (2) location of these foci in the neck (e.g. within or outside thyroid bed), (3) the % uptake in the thyroid bed/neck, (4) uptake suggestive of distant metastases, and (5) significant altered biodistribution such as breast, marked salivary gland, or marked bowel uptake. For each finding, the reviewer noted in his opinion whether or not and how the patient’s management would have been altered prior to the 131-I ablation. Results: Of 205 scans reviewed (mean age = 48, range 17-78), 94 (46%) of patients had findings on the RWBS that could have altered the patient’s management prior to the 131-I ablation. Of these 94 patients, the management of the patient was altered in the following number (%) of patients: Criteria 1: 39 (19%) [26 (13%) with six or more foci suggesting local metastases [LM] and 13 (6%) with no foci of uptake at all]. Criteria 2: 31 (15%) [suggestive of LM]. Criteria 3: 20 (10%) [>15% uptake]. Criteria 4: 10 (5%). Criteria 5: 31 (15%) [10 (5%) breast, 5 (2%) salivary, 17 (8%) GI, 1 (0.5%) other]. We will also report how each finding altered management. Conclusions: Pre-ablation RWBS demonstrate a significant number of findings that can alter the management of patients with WDTC prior to 131-I ablation.

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