Toxic multinodular goiter other imaging findings

Radioiodine uptake may be helpful in the diagnosis of multinodular goiter.Patchy pattern of increased radionuclide uptake in more than one nodule associated with decreased uptake in the surrounding extranodular thyroid tissue is characteristic of toxic multinodular goiter.

• Radioiodine uptake may be helpful in the diagnosis of multinodular goiter.^[1]
• Findings on a thyroid nuclear scintigraphy suggestive of multinodular goiter include enlarged gland, with heterogeneous uptake that determines the activity of the gland.
• Patchy pattern of increased radionuclide uptake in more than one nodule associated with decreased uptake in the surrounding extranodular thyroid tissue is characteristic of toxic multinodular goiter.
• Commonly used isotopes are Tc-99m pertechnetate or radioiodine (I123).These isotopes are preferred over isotope sodium iodide-131 (Na 131 I) due to their shorter half-life and comparitively lower radiation exposure.
• Iodine-123 scanning is preferred over 99m Tc scan. 99m Tc scanning may provide misleading results as 99m Tc is trapped in the thyroid but is not organified. Some nodules that appear hot or warm on 99m TC scan results may be cold on 123 I scan results.
• Based on uptake of radioactive isotope thyroid nodule can be divided into:
  • Hot nodule: suggestive of autonomously functioning nodules.
  • Warm nodule: indicates normal thyroid function.
  • Cold nodule: suggestive of hypofunctional or nonfunctional thyroid tissue.
• 5-8% of warm or cold nodules are malignant, however hot nodules are rarely malignant.

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