Tc-99m Sestamibi Thyroid Imaging in Patients on Chronic Amiodarone Treatment

Abstract

This study suggests that Tc-99m sestamibi may be an alternative tracer for thyroid scintigraphy and uptake measurement of patients on chronic use of amiodarone. Tc-99m sestamibi seems to be better than Tc-99m pertechnetate for the scintigraphic evaluation of the thyroid of euthyroid and hyperthyroid patients.

2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis

“…Among European thyroidologists surveyed on the use of diagnostic imaging in the differential diagnosis of AIT, approximately 20% preferred RAIU alone, 20% preferred CFDS alone, nearly 40% utilized both methods simultaneously, and 20% thought both techniques were useless (602). Recently, sestamibi uptake by the thyroid, which is diminished with thyroiditis, has been applied for distinguishing AIT subtypes with preliminarily promising results (603,604).…”

Dual-Isotope 99mTc-MIBI/123I Parathyroid Scintigraphy in Primary Hyperparathyroidism

“…Indeed, 99m Tc-MIBI is lipophilic and diffuses passively through cellular membranes. 21 In opposition, 123 I uptake is decreased by iodine excess. Low iodine radioactivity count leads to very noisy image and prevents an optimal thyroid subtraction.…”

Amiodarone-Induced Thyroid Dysfunction: A Clinical Update

“…However, these tests are expensive and may not be freely available in many small centres. Radioiodine uptake and 99m Technetium sestamibi scans are reported to be helpful in the differentiation between the main two types of AIT, with 99m Technetium scan showing better results [26][27][28][29]. ▶ Fig.…”

“…Therefore, RAIU study is not very dependable as patients with high dietary iodine intake may have subnormal uptake values because the uptake of radioiodine tracer is inhibited by high intrathyroidal iodine concentrations. This can lead on to mislabelling of the patient with a diagnosis of AIT-2 instead of AIT-1 that can create problems with therapeutic intervention [6,15,[26][27][28][29][30].…”

“…AIT-1 is associated with hyperactive thyroid tissue, and therefore, shows increased MIBI retention, whereas, AIT-2 resulting from destructive thyroiditis shows reduced uptake in the necrotic tissue [27]. Although this scan is claimed to help differential diagnosis of various forms of AIT including AIT-Int (indeterminate, a mixed subtype of AIT) in different studies, the number of cases included in these studies were relatively small which may reduce the statistical power to make high quality evidence-based recommendations for clinical practice [28,29,31]. Other investigations such as measurement of interleukin-6 (IL-6) and c-reactive protein are nonspecific and would not help in differential diagnosis greatly [32,33].…”