FIGURE 4.

Lithium-induced hyperparathyroidism (patient #12). A, FCH-PET and PET/CT fused images (MIP, coronal and transversal slice, early dynamic image in the left column, upper static images in the right column): a large focus with early and intense uptake extending over the thyroid isthmus and the adjacent part of the thyroid left lobe (thyroid nodule or hyperfunctioning parathyroid gland?). B, ¹²³I/^99mTc-sestaMIBI scintigraphy: similar focus corresponding to an iodine-negative part of the thyroid gland. By discontinuing lithium therapy, PTH serum levels decreased from 165 pg/mL to 90 pg/mL at the time of PET/CT and to 40 pg/mL on the day after surgery. This focus actually corresponded to a large oncocytic adenoma and a smaller follicular adenoma of the thyroid. Four small bilateral lesions of thyroid carcinoma with lymph nodes metastases were discovered at histology (all < 2 mm in size), but no abnormal parathyroid gland. FCH-PET/CT = ¹⁸F-fluorocholine hybrid positron emission tomography/X-ray computed tomography; PTH = parathyroid hormone; sestaMIBI = sesta-methoxyisobutylisonitrile.