Radioiodine Planar and a SPECT/CT Imaging With Iodine-123 for Evaluation of Follicular Thyroid Nodules Prior to Surgery

PRIMARY OBJECTIVES:

I. Determine the proportion of benign nodules appearing as hot/warm on radioiodine scans (nodule uptake >= uptake in normal thyroid tissues).

II. To identify a possible relationship between iodine-123 (I-123) uptake on planar and single-photon emission computerized tomography (SPECT)/computerized tomography (CT) images and malignancy on surgical pathology in thyroid nodules that were previously identified by fine-needle aspiration (FNA) as indeterminate follicular neoplasm.

III. Examine correlations between intensity of uptake in follicular nodules before surgery (standard uptake values [SUV] on the quantitative reconstructions from our Veriton SPECT/CT scanner and nodule-to-normal thyroid background ratios on planar and SPECT images) and pathology findings and determine a SUV threshold that best distinguishes between benign and malignant nodules.

IV. Compare the usefulness of conventional planar imaging versus SPECT/CT imaging for thyroid nodules, in order to inform our optimal clinical protocol.

V. Establish an imaging protocol best suited for measuring uptake in small thyroid nodules.

OUTLINE:

Patients receive iodine-123 orally (PO) and then undergo planar imaging and a SPECT/CT scan on study.

Inclusion criteria

• Age > 18 years
• Any gender
• Patients will have had no therapy for their thyroid nodule prior to enrollment
• Negative urine pregnancy test within 48 hours before the administration of radiopharmaceutical in women of childbearing potential
• Follicular neoplasm or suspicious of follicular neoplasm, cytopathology on biopsy of thyroid nodule
• Any outside fine needle aspiration (FNA) reports are to be reviewed by a Mayo pathologist
• Nodules 1-4 cm with solid appearance on ultrasound
• Ultrasound images and report documented in medical record, including the size of the nodule and location (upper, mid or lower portion of the thyroid lobe)
• At least 2/3 of either thyroid lobe without nodules should be present to allow for the measurement of uptake in unaffected thyroid tissue
• Thyroid stimulating hormone (TSH) 0.3-3.0 mIU/L
• Patient is scheduled or being considered for surgical resection of the nodule
• I-123 planar and Single Photon Emission Computed Tomography (SPECT)/Computed Tomography (CT) can be scheduled at least 2 days after biopsy and before surgery

Exclusion criteria

• Recent iodinated contrast, including intravenous (IV) and oral CT contrast or interventional vascular or cardiac study (within 6 weeks)
• Hurthle cell adenoma
• Current thyroid hormone supplementation
• Current use of anti-thyroid medications (methimazole or propylthiouracyl)
• Less than 2 days after thyroid nodule FNA/biopsy
• Presence of another nodule of similar size in the same area of thyroid lobe, which could impair localization of the nodule on SPECT/CT images
• Less than 2/3 of normal thyroid tissue present in either thyroid lobe without nodules
• Positive pregnancy test
• All women who are breastfeeding