Usefulness of preoperative Tc-mibi parathyroid scintigraphy in secondary hyperparathyroidism

The usefulness of Tc-mibi parathyroid scintigraphy (Tc-PS) in planning parathyroidectomy for secondary hyperparathyroidism is not well known. The aim of this study was to review our experience with Tc-PS concerning: (1) the identification of hyperplastic glands, (2) detection of major ectopias and (3) prevention of recurrences.

Thirty-three consecutive patients undergoing first-time subtotal parathyroidectomy for renal hyperparathyroidism had a dual-phase planar Tc-PS performed, and glands were classified as detected, weak, or not detected. The number and position of visualized glands were determined. Parathyroid weight, histology, and their relationship to Tc-PS were recorded after surgery.

Of 132 potential glands, 48 (35%) were localized on the Tc-PS and 128 (96.9%) were identified intraoperatively. Tc-PS positive/weak glands were heavier than nonlocalized glands. Tc-PS contributed to successful surgery in four patients with a single difficult gland each (three retrieved from the neck and one--fifth gland--requiring mediastinotomy). There was one persistence (3%) because of a missed fourth undescended inferior parathyroid gland. Two recurrences 2 years after surgery were due to a fifth thoracic gland not shown in the preoperative Tc-PS.

Preoperative Tc-PS helped in the intraoperative identification of moderate or major ectopias in 4/33 patients but was not useful to prevent recurrences from highly ectopic glands not visualized before first-time surgery.