99mTechnetium Sestamibi-123Iodine Scintigraphy Is More Accurate Than 99mTechnetium Sestamibi Alone before Surgery for Primary Hyperparathyroidism

Objectives. Studies comparing outcome of single-(99m)Tc-methoxyisobutylisonitrile ((99m)Tc-sestamibi) and dual-tracer (99m)Tc-sestamibi scintigraphy in combination with (123)I before primary surgery of primary hyperparathyroidism (PHPT) are scarce. Methods. We compared (99m)Tc-sestamibi/(123)I and (99m)Tc-sestamibi in a single-centre retrospective series of 269 PHPT patients. The results were related to laboratory, surgical and histological findings. Results. (99m)Tc-sestamibi/(123)I and (99m)Tc-sestamibi were positive in 206 (76.6%) and 111 (41.3%) of 269 patients, respectively (P < 0.001). Accuracies for (99m)Tc-sestamibi/(123)I and (99m)Tc-sestamibi were 63.4% and 34.9%, respectively (96% CI, P < 0.001). Prevalence of multiglandular disease was 15.2%. In multiglandular disease, (99m)Tc-sestamibi/(123)I and (99m)Tc-sestamibi revealed 43.8 and 22.1% of pathological glands, respectively (P < 0.001). Cure rate was similar for patients with (191/206; 92.7%) and without (59 of 63; 93.7%) a positive (99m)Tc-sestamibi/(123)I finding. Duration of targeted surgery (one or two quadrants) was 21 and 15 minutes shorter than bilateral neck exploration, respectively (both P < 0.001). Higher serum calcium (P = 0.014) and PTH (P = 0.055) concentrations and larger tumours (P < 0.001) characterized the 206 patients with a positive preoperative scan who were cured by removal of a single adenoma. Conclusions. (99m)Tc-sestamibi/(123)I scintigraphy is more accurate than (99m)Tc-sestamibi before surgery of PHPT. However, outcome of surgery is not determined by scintigraphy alone.