Toxic Adenoma other imaging findings

Radionuclide imaging and quantitative radioisotopic uptake studies are always required to establish the diagnosis of toxic adenoma or toxic nodular goiter. Radionuclide imaging can be performed with radioactive iodine-123 or with technetium-99m. In patients with hyperthyroidism caused by a toxic adenoma, there is a characteristic restriction of radionuclide uptake to the responsible hyperfunctioning nodule with suppression of radionuclide uptake in the remainder of the gland.

• Radionuclide imaging and quantitative radioisotopic uptake studies are always required to establish the diagnosis of toxic adenoma or toxic nodular goiter.^[1]
• Radionuclide imaging can be performed with radioactive iodine-123 or with technetium-99m.^[2][3]
• Radionuclide imaging performed with iodine-123 or technetium-99m, are trapped by the sodium-iodide symporter in functioning thyroid tissue, although only radioiodine is subsequently organified.
• In patients with hyperthyroidism caused by a toxic adenoma, there is a characteristic restriction of radionuclide uptake to the responsible hyperfunctioning nodule with suppression of radionuclide uptake in the remainder of the gland.
• In a patient with a low serum TSH concentration, not only does the scan appearance support the diagnosis of toxic adenoma, but in almost all cases it also excludes malignancy in the nodule.
• If some thyroid nodules are hypo-functioning, it is necessary to rule out cancer by fine-needle aspiration cytology.