Scintigraphy of parathyroids in secondary hyperparathyroidism

Use of pre-surgery imaging of parathyroids is still questioned. The goal of this study is to evaluate the sensitivity of the scintigraphy in the detection of secondary parathyroid anomalies with renal insufficiency. Thirty two patients (20 F, 12 M) of 14 - 74 years old were operated of secondary hyperparathyroidism with renal insufficiency. It was a matter of re-intervention in 9 cases. The acquisitions were achieved 20 min and 2 h after injection of 550 MBq of MIBI-99mTc or of Tetrofosmine - 99mTc and 2 h after injection of 5.5 MBq of iodine 123. Eighty seven glands of 28 to 3820 mg were pulled out in 23 first surgeries while the parathyroid tissue was found in thymic prolongations in 5 of these patients. The masses of 41 glands, positive by scintigraphy (from 69 to 3829 mg), were significantly higher (Wilcoxon's test, p < 10-8) than the 46 not-seen (from 28 to 1050 mg). The sensitivity of total detection is 47%, of 85% for the 33 glands of 500 mg or more and of 24% for the 54 glands of less than 500 mg. In 9 re-interventions, 12 abnormal glands were pulled out: 11 (of 430 to 4500 mg were positive by scintigraphy, while only one gland of 80 mg was not seen. In conclusion, the scintigraphy realised before first surgery for secondary hyperparathyroidism with renal insufficiency presents low sensitivity, related partly, at least, to the low mass of glands and justifies itself only by search for positive ectopic parathyroids. Instead, it appears performing and indispensable in case of re-intervention