• iperparatiroidismo primario
• paratiroidectomia mininvasiva
• SPECT/TC

Primary hyperparathyroidism, i.e. autonomous overproduction of parathyroid hormone, is caused in 80%-90% of patients by a single adenoma. Pre-operative imaging for localization of parathyroid adenomas is critical for successful surgery, especially in the case of minimally invasive parathyroidectomy.
This study evaluated whether the accuracy of an optimized scintigraphic protocol based on planar imaging with dual-phase, dual-tracer scintigraphy (99mTc-Sestamibi/99mTcO4), plus an early SPECT/CT study, can precisely identify the anatomic localization of the parathyroid adenoma before surgery and thus prevent the use of intraoperative parathyroid hormone measurement during minimally invasive radioguided parathyroidectomy (MIRP).
From September 2004 to January 2010 we evaluated 29 patients with biochemical diagnosis of PHPT and a high likelihood of a solitary parathyroid adenoma (M:F=1:4, mean age 57.9±12.4 years). All patients underwent an ultrasonographic study and planar and SPECT/CT parathyroid scintigraphy 2–5 days before MIRP. Anterior planar images of the neck and chest were acquired for 10 min, at 10 and 150 min after intravenous injection of 740 MBq 99mTc-Sestamibi. A SPECT/CT study was carried out immediately after the first planar image. In addition, after acquiring the late (ca 150 min) 99mTc-Sestamibi image, dual-isotope subtraction was performed using a 10-min image obtained after injection of 370 MBq 99mTc-pertechnetate.
MIRP technique consisted in injecting 37-110 MBq 99mTc-Sestamibi 30 minutes before the start of the surgery in patients in whom the preoperatively 99mTc-Sestamibi scan showed for a solitary parathyroid adenoma. Through a skin incision < 3 cm, dissection of the adenoma was guided by a 14-mm collimated gamma-probe alone, without the aid of intraoperative quick parathyroid hormone (IQPTH) assay. Patients were given the choice of general or local anesthesia.
Our scintigraphic protocol identified a solitary adenoma in all patients, even in cases of ectopic localizations (8/29, 5 of which in pararetrotracheal space, 2 in pararetroesophageal space, and 1 intrathymic). The correct evaluation and high sensitivity in localizing ectopic glands was due in these cases to the use of SPECT/CT.
MIRP was successfully performed in all patients without the help of IQPTH. No patient presented persistent hypercalcemia during long-term postsurgical follow-up, and therefore was considered to be cured. About 10% of the MIRP procedures were performed under local anesthesia.