The complementary role of parathyroid scintigraphy and ultrasound (US) in the evaluation of primary hyperparathyroidism

Objectives To evaluate the role of Tc-99m Sestamibi scintigraphy and ultrasound in primary hyperparathyroidism and analyze role of gland weight in the accuracy of imaging diagnosis.

Methods Retrospective HIPAA-compliant review of 229 consecutive patients between 2007 and 2009 who underwent planar parathyroid scintigraphy, ultrasound and parathyroidectomy. A total of 270 resected glands were analyzed.

Results Sestamibi scans were positive for 175 glands (65%), of which 172 (98%) were true positives, confirmed by pathology and postoperative biochemical cure. Ultrasound was positive for 191 glands (71%) of which 163 (85%) were true positives. Sestamibi scans were falsely negative for 70 glands (26%) with ultrasound positive in 42 of the 70 sestamibi-negative glands (60%), of which 39/42 (93%) were true positives. The mean weight for sestamibi-positive glands was 1148 mg and 452 mg for the sestamibi-negative culprit glands (p value <0.01), whereas for ultrasound positive and negative glands, mean weights were 912 and 463 mg respectively (p value <0.01).

Conclusions The Sestamibi scan is slightly more accurate than ultrasound in primary hyperparathyroidism and should be the first test performed. Ultrasound is particularly useful in the Sestamibi-negative cases. Both sestamibi and ultrasound tend to miss small sized glands.