n.123 – INTRAOPERATIVE 99MTC-SESTAMIBI SCINTIGRAPHY WITH MINIATURE GAMMA CAMERA FOR RADIOGUIDED PARATHYROIDECTOMY: OUR EXPERIENCE



Abstract

BACKGROUND-AIM
The widely accepted procedure for the treatment of primary hyperparathyroidism (PHPT) is the excision of the gland responsible of the parathormone (PTH) hyperproduction and subsequently of the hypercalcemia. Preoperative location studies (the combination of 99mTc-sestamibi [MIBI] scintigraphy scans and high resolution ultrasonography is the gold standard) allow the proper identification of pathologic gland. Intraoperative parathormone assay (ioPTH) is used to confirm the removal of the pathologic gland. We have used intraoperatively a new miniature gamma camera (MGC) to locate parathyroid adenomas and confirm their correct excision.
The objective of this study was to evaluate the utility and feasibility of this technique.
METHODS
Five female patients suffering from PHPT were enrolled for our study. The mean age of the patients is 63,4 years (range 50-73). The mean PTH pre-operation is 382 pg/mL (142-684), Ca 11,04 mg/dL (10-12,9). All the patients underwent a preoperative ultrasonography and parathyroid scintigraphy. The scintigraphy was performed using a intravenous injection of 370 MBq of 99mTc-MIBI (Technemibi, Mallinkrodt) with the double phase technique, through the acquisition of early and late images, to show the wash out of the radiopharmaceutical from the thyroid and the persistence of the parathyroid image.
In order to assess the value and the usefulness of the MGC intraoperative scintigraphy, the surgeons carried out all surgical procedures following the usual protocol they would have applied in each specific situation. In addition, we used the portable MGC (Sentinella 102, Oncovision) to conduct the intraoperative study. This device has the following characteristics: Caesium iodide detector; flexible arm provided with a pinhole collimator at its distal end for capturing images; computerized system with 2 screens, enabling the simultaneous display of scintigraphic images, for both nuclear physician and surgeon. After anaesthesia the nuclear physician administered an intravenous dose of 185 MBq of 99mTc-MIBI. After 15-20 minutes the first scan in the anterior projection began. Once the pathological parathyroid gland was located and excised, images of the excised material and the surgical fields were performed, confirming that the excised material was truly responsible for the initial detection, as swell as the absence of the previous hot spot in the surgical field. All patients underwent ioPTH and study of the surgical specimen, to confirm the removal of the pathologic gland.
RESULTS
In all cases the MGC provided the same information of the preoperative imaging, allowing the surgeon to identify the pathologic gland and, after its excision, checking the absence of the previous uptake.
All patients were monitored intraoperatively with serials controls of PTH levels and postoperatively with calcium and PTH levels that show their drop.
CONCLUSION
No false result (neither positive, nor negative) have been observed in our short case series.
We can state that the intraoperative use of MGC in primary hyperparathyroidism is a very useful and feasible tool to confirm the removal of the pathologic parathyroid.

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