Douglas Van Nostrand

Radionuclide Imaging of Thyroid Nodules

Thyroid scintigraphy has been used for many years to evaluate thyroid nodules. The clinical value of thyroid scintigraphy has been established based on the knowledge that (1) functioning nodules have not only increased radioiodine uptake relative to normal functioning thyroid tissue but also have a low probability of malignancy; and (2) thyroid cancers have no or very low (e.g., 1 in 100) radioiodine accumulation relative to normal thyroid tissue. This section presents an overview of thyroid scintigraphy in the evaluation of thyroid nodules (see Table 1).

To Perform or Not to Perform Radioiodine Scans Prior to 131I Remnant Ablation? PRO

The utility of radioiodine pre-remnant ablation scans remains very controversial. This chapter argues for performing radioiodine pre-remnant ablation scans. There are five main arguments that are typically presented against the utility of pre-remnant ablation scans: (1) “no useful data is obtained from pre-remnant ablation radioiodine scans that will alter my management,” (2) “everything I need to know is on the post-therapy scan,” (3) stunning, (4) the potential benefit is not worth the costs or inconveniences, and (5) until data are published demonstrating that the pre-131I therapy scans alter patient outcomes, these scans should not be performed. This chapter presents a point by counterpoint discussion of the arguments for and against pre-therapy radioiodine ablation. The chapter concludes with rarely discussed issues that in my opinion may be important points regarding the differences in opinions of the utility of pre-remnant ablation radioiodine scans.

New Approaches in Nuclear Medicine for Thyroid Cancer

When I wrote this chapter for the second edition of this textbook in 2006, I was not necessarily writing about the future developments of nuclear medicine in thyroid cancer within the next 6 years. Rather, I was attempting to communicate the spectrum of potential changes that might develop not only in the near future but also the distant future. Accordingly, the concepts that were the basis for my previous chapter in the second edition of this textbook have not changed significantly, and I have retained that chapter for this edition.

Remnant Ablation, Adjuvant Treatment and Treatment of Locoregional Metastases with 131 I

The two major areas of controversy in the management of patients with differentiated thyroid cancer are when to administer an 131I therapy and, if administered, what should be the amount of prescribed activity of 131I that is administered. Although one of the more frequent factors that is cited for the two controversies is the lack of good prospective studies, these two controversies are complicated by many other factors such as (1) the use of the same terms with different definitions, (2) the use of the same terms with different objectives (e.g., destruction of remnant tissue, reduced recurrence, or decreased disease-specific mortality), (3) the use of a term with the same definition and objectives but different end points as the measure of success for those objectives (e.g., uptake, scan, stimulated or non-stimulated thyroglobulin blood level, recurrence, and/or structural evidence of disease), (4) the end points are measured at different follow-up times (e.g., 6, 9, 12 months), and (5) variability in the extent of initial surgery and different staging systems (risk assessment tools).

Side Effects of 131 I for Therapy of Differentiated Thyroid Carcinoma

The use of radioactive iodine (131I) for remnant ablation, adjuvant treatment, and treatment of metastases from differentiated thyroid carcinoma may be associated with side effects in numerous organ systems. Although many articles address the side effects of 131I, the characterizations of these effects vary widely because of a host of different factors. This chapter attempts to consolidate the literature by presenting, where appropriate, (1) the spectrum of signs and symptoms, as well as the frequency and severity of side effects; (2) a review of selected articles; (3) a discussion of preventive measures to reduce the frequency and severity of side effects; and (4) a discussion of the medical management when selected side effects do occur.

The Utility of SPECT-CT in Differentiated Thyroid Cancer

Single-photon emission computerized tomography (SPECT) in combination with computerized tomography (CT) allows integration of functional and anatomic information, and SPECT-CT is playing an increasingly important role in imaging of differentiated thyroid cancer. This chapter reviews the relevant literature supporting the utility of radioiodine SPECT-CT and its impact on management of patients with differentiated thyroid cancer. Selected images demonstrating the utility of SPECT-CT are presented.

Radionuclide Imaging and 131I Therapy in Follicular Thyroid Carcinoma

Radionuclide imaging and 131I therapy including dosimetry are addressed in multiple separate chapters. This brief chapter addresses the relation of special aspects of radionuclide imaging and 131I therapy to follicular thyroid cancer (FTC). Although papillary and follicular differentiated thyroid cancers are histologically different, their biological behaviors are similar. As a result, most published reports do not differentiate between the two, describing outcomes for “differentiated thyroid carcinoma,” and this is especially true for the literature involving radionuclide imaging and 131I therapy. Accordingly, the other chapters discussing various issues for papillary carcinoma are for the most part also applicable to patients with follicular carcinoma. However, several distinctions between these two types of thyroid malignancy are noteworthy.

A Summary of Rare Sites of Metastasis Secondary to Differentiated Thyroid Cancer

Most patients with differentiated thyroid cancer (DTC) will never have a metastasis. However, if they do, the most frequent sites of metastases are the cervical lymph nodes, lung, and bone. Less frequent sites include the mediastinal lymph nodes and brain, and very rare sites include, but are not limited to, the parathyroid, breast, eye, liver, soft tissue, skin, pleura, heart, kidney, ovary, muscle, pancreas, pericardium, gastrointestinal tract, spleen, parotid gland, and peritoneum. This chapter presents a discussion focusing on rare sites of metastases of differentiated thyroid cancer.

Dosimetrically Determined Prescribed Activity of 131I for the Treatment of Metastatic Differentiated Thyroid Carcinoma

In the absence of definitive studies relating 131I prescribed activity to outcomes, the selection of a specific prescribed activity of 131I to treat metastatic thyroid carcinoma is problematic, and several approaches have historically been adopted. These include empiric fixed prescribed activity and prescribed activity based on dosimetric approaches specific for each patient. This chapter reviews the rationale and technique for “dosimetrically determined” prescribed activity of 131I for the treatment of metastatic thyroid carcinoma and discusses (1) the alternatives for the selection of a prescribed activity, (2) the two major dosimetric approaches for determining 131I prescribed activity, (3) several modifications of these approaches that have been implemented over time, (4) an overview of the literature regarding the results, and (5) recommendations for patient management and future research. This review does not address the use of dosimetrically determined prescribed activity of 131I for the initial (postoperative) remnant ablation of normal thyroid remnant tissue or adjuvant treatment.

Stunning: Does it Exist? A Commentary

Do diagnostic prescribed activities (dosages) of 131I cause stunning or not? In the first part of this section, Drs. Park and Gerard present arguments supporting the presence of stunning secondary to the administration of diagnostic dosages of 131I, and in the second section, Dr. McDougall presents arguments against the presence of stunning as a significant issue. In the end, each physician will most likely select the information that one believes makes the stronger argument or best supports one’s prior viewpoint. However, a third viewpoint exists to either a “yes” or “no” answer. It is a compromised viewpoint that holds: “Diagnostic doses of 131I result in a spectrum ranging from no stunning to significant stunning and even treatment.”