Preoperative scintigraphic and intraoperative scintimetric localization of parathyroid adenoma with cationic Tc-99m...

The aim of our study was to evaluate the possibility of intraoperative scintimetric detection of parathyroid adenomas with Tc-99m labelled tracers for its usefulness in dystropic or ectopic adenomas.

12 women with biochemically confirmed hyperparathyroidism were included in our study. After injection of 370 MBq Tc-99m tetrofosmin e.g. sestamibi, preoperative scintigraphy (double phase study and SPECT) was performed and T/NT ratios were evaluated for early, delayed and SPECT images. Surgery was performed using a hand-held gamma-probe after preoperative injection of 555-925 MBq Tc-99m tetrofosmin e.g. sestamibi. Count rates (cts/10 sec) were measured and used for calculating in situ- and ex situ-T/NT ratios.

In 9 out of 12 patients, adenoma could be detected on static images. Mean T/NT ratios for Tc-99m tetrofosmin were 1.29 for early and 1.23 for delayed images, respectively 1.39 and 1.23 for early and delayed Tc-99m sestamibi scan. Three cases could only be detected with SPECT reconstruction, 11 of 12 parathyroid adenomas could be confirmed intra-operatively.

SPECT with Tc-99m labelled cationic complexes showed advantages in detection, precise localization and contrast over static scintigraphy and should therefore be performed at least in cases with poor or no uptake on static images to avoid failures in detection of deeply sited, dislocated glands or adenomas with low uptake. Intraoperative localization and confirmation of parathyroid adenoma with Tc-99m labelled cationic complexes and a gamma probe is possible an 1 may be useful in case of dys- or ectopic adenoma by influencing surgical approach and operating time.