Preoperative imaging of parathyroid glands with technetium-99m-labelled sestamibi and iodine-123 subtraction scanning in secondary hyperparathyroidism.

BACKGROUND

Parathyroidectomy is unsuccessful in 10-30% of uraemic patients operated on for secondary hyperparathyroidism. We investigated the usefulness of preoperative radionuclide imaging, with simultaneous recording of the distribution images of iodine-123 and technetium-99m-labelled sestamibi.

METHODS

11 patients with secondary hyperparathyroidism underwent prospective imaging and parathyroidectomy. Plasma concentrations of intact parathyroid hormone (PTH) were measured in all patients before and 6 months after subtotal parathyroidectomy.

FINDINGS

Preoperative scanning showed 42 hot-spots suggesting enlarged parathyroid glands. 45 glands were discovered at surgery, and the parathyroidectomy was deemed successful in ten patients. Among the latter, one patient had a supernumerary parathyroid gland detected by scanning and resected from the left thymus. Another patient showed ectopic uptake corresponding to a large parathyroid gland in the upper mediastinum, and another had a parathyroid gland well above the thyroid. No false-positive scan findings were documented. In the patient for whom parathyroidectomy failed, preoperative scanning suggested five enlarged parathyroid glands, though the surgeon found only four glands, in their normal positions. Hyperparathyroidism persisted (intact PTH 527 ng/L, 6 months after surgery). A second scan confirmed the preoperative scan, showing a fifth parathyroid gland in the middle of the right thyroid lobe.

INTERPRETATION

Simultaneous recording of 99mTc-sestamibi and 123I improved the imaging of parathyroid glands in secondary hyperparathyroidism. The technique can identify ectopic and supernumerary parathyroid glands.