I-131 Whole Body Scan Lung Metastasis Prepared By Dr Gabriel Castro (Costa Rica)
54 y/o male. History of papillary thyroid carcinoma follicular
variant, with lymphonode metastasis (10/11) treated with total thyroidectomy and
150mCi of 131 I, one month later. TSH: 125 IU/ml. He has no prior evidence of
distant metastasis.
Although most well-differentiated thyroid cancers follow a slow clinical course,
approximately 1% to 8% of papillary and 8% to 33% of patients with follicular
thyroid carcinoma present with distant metastasis at the time of diagnosis (1).
In planning the follow-up strategy, one should firstly rely on the results of
the WBS obtained a few days after the administration of the ablative dose of
131-I and on individual prognostic factors. Posttherapy WBS should always be
performed because it has greater sensitivity than the diagnostic scan (2).
Whole Body Scan (WBS) : 3 days after ablative 131 I dose. Several abnormal areas
of 131-I irregular uptake are seen in both lung bases (arrows in spot posterior
view), compatible with metastasis, also focal moderate uptake in left neck
region (arrow head above).
References:
1) Lin J, Chao T. Papillary Thyroid Carcinomas with Lung Metastases. 2004: 14:
1091-1096.
2) Sherman SI, Tielens ET, et al. Clinical utility of post-treatment radioiodine
scans in the management of patients with thyroid cancer. J Clin Endocrinol
Metab 1994; 78:629.