[Preoperative localization of parathyroid lesions with Tc-99m-MIBI/iodine 123].

OBJECTIVE Assess the sensitivity of MIBI-Tc for the detection of parathyroid lesions and define the threshold of detection by evaluating contrast uptake at 20 minutes and 2 hours. METHODS Fifty-five operated and cured patients were studied. Image acquisitions were made 20 minutes and 2 hours after injection of 555 MBq MIBI-Tc then 2 hours after injection of 5.55 MBq iodine 123. RESULTS A total of 87 pathological glands were found including 47 adenomas (80 to 8820 mg) and 40 hyperplasias (44 to 2175 mg). Detection sensitivity was 81% for adenomas and 30% for hyperplasia, but the cell type did not appear to be a determining factor. CONCLUSION Scintigraphic visualization of parathyroid lesions is more frequent when there is a single lesion. At least one lesion was seen in 80% of the patients. The threshold of detection was 225 mg. Enhancement of parathyroid uptake with MIBI-Tc compared with the thyroid between 20 minutes and 2 hours was not a constant and of unknown origin.