Endocrine Abstracts

The aim of this study was comparison of sensitivity of subtraction parathyroid scintigraphy (SBPS), vs. two-phase parathyroid scintigraphy (2FPS), related to histological type of hyperfunctioning parathyroid tissue.

Materials and methods: Fifty patients, thirty with primary hyperparathyroidism and twenty on dialysis and secondary hyperparathyroidism underwent parathyroid scintigraphy (PS) before surgery. Static scintigrams of neck and chest were performed, fifteen minutes and two hours after iv. injection of 740 MBq of Tc99m-MIBI. Four hours latter, after iv. injection of 185 MBq Tc99m, thyroid scintigraphy was performed. After normalization and motion correction, subtraction Tc99m from Tc99m-MIBI scintigrams was done. Scintigraphic results of both PS methods were graded from one to five: grade 1-normal finding, grade 2-probably normal finding, grade 3-suspicious finding, grade 4-probably abnormal finding and grade 5-abnormal finding. Scintigraphic findings graded 3, 4 and 5 were considered as pathologic. Pathohistological analyses were done microscopically on standard haematoxylin-eosin stained slides to determine the substrate: adenoma and type of hyperplasia.

Results: Postoperatively 96 hyperfunctioning paratiroid glands (PG): 24% adenomas, 62.5% with nodular hyperplasia (NHPL) and 13.5% with diffuse hyperplasia (DHPL), were found. Overall sensitivity of SBPS was 74%; 91.3% for adenoma, 70% for NHPL and 61.5% for DHPL, with no statistically significant difference in sensitivity between groups of PG. Overall sensitivity of 2FPS was 67.7%; 100% for adenoma, 61.5% for NHPL, and 38.5% for DHPL. Statistically significant difference was found in sensitivity of 2FPS findings between these three groups, P<0.0001. SBPS had statistically significantly higher sensitivity of 61.5% for diffuse hyperplasia, comparing to 2FPS, with sensitivity of 38.5%, P<0.0001.

Conclusion: SBPS and 2FPS showed similar sensitivity in detection of PG adenoma and nodular hyperplasia of parathyroid glands. Superiority of subtraction parathyroid scintigraphy in detection of PG with diffuse hyperplasia is important finding, knowing that these glands are the smallest one and often remain undetected prior surgery, both in secondary, and importantly in primary hyperplasia.