Nuclear Imaging in the Management of Thyroid Carcinoma

Abstract

The avidity of differentiated thyroid carcinoma for iodine is the basis for the use of radioiodine (131I) both for the detection and the treatment of recurrent thyroid cancer in patients following initial surgical treatment (thyroidectomy). Because recurrence of this type of cancer may be delayed for many years, long-term follow-up is needed. Nowadays such surveillance involves clinical assessment, monitoring of serum thyroglubulin, and, when indicated, whole-body imaging with 131I. Sensitivity of 131I imaging depends on proper preparation of the patient and careful attention to imaging technique. Interpretation of images requires knowledge of physiologic sites of radioiodine concentration and causes of artifacts. Because of the potential suppressive effect of the radiation from a diagnostic administration of 131I on the uptake of a subsequent therapeutic administration (so-called stunning of thyroid tissue) many centers limit the amount given for scanning to 2-3 mCi (74-111 MBq). Several tumor-seeking radioisotopic agents other than radioiodine have shown promise for improving the detection of metastases, and some of these agents offer a useful adjunct to 131I in the management of selected patients, particularly in those with suspected metastatic disease and negative 131I scans.

Radioiodine Treatment with 30 mCi after Recombinant Human Thyrotropin Stimulation in Thyroid Cancer: Effectiveness for Postsurgical Remnants Ablation and Possible Role of Iodine Content inl-Thyroxine in the Outcome of Ablation

“…In fact, the role of the amount of the iodine intake in the uptake of both tracer and therapeutic dose of 131 I has been clearly shown (19,25). Our results using a protocol in which l-T4 has been interrupted for a few days, from the day before rhTSH until iodine administration, seem to emphasize the interference of iodine content of T 4 on the effectiveness of radiometabolic treatment.…”

“…Approximately 95% of thyroid cancers originate in follicular cells, and the majority of cases are DTC: papillary cancer and a minority of follicular cancer (18). DTC maintains the capability of trapping iodine and synthesizing Tg, and these two features represent the crucial points of DTC management (18,19). The capability of trapping iodine allows ablation of postsurgical normal and neoplastic remnants with 131 I and allows for the discovery of pathological tissue with WBS.…”

Coexistence of an Autonomously Functioning Thyroid Nodule in a Patient with Graves' Disease: An Unusual Presentation of Marine-Lenhart Syndrome.

“…The nodule might be more sensitive to MMI than extranodular tissues although the in vivo pharmacokinetics of AFTN and Graves' disease in the same patient as in the present case would be complex. Radioiodine scintigraphy might have been useful in evaluating the pathophysiology in more detail in the present patient [13].…”

Are Posttherapy Radioiodine Scans Informative and Do They Influence Subsequent Therapy of Patients with Differentiated Thyroid Cancer?

“…Because therapeutic doses of 131I may delineate foci of disease not seen on a diagnostic WBS, performing PTS after therapeutic doses has become a common practice in DTC management (2,3,7,8). Nemec and colleagues (4) identified new uptake in 16% of PTS.…”