Preoperative detection of sporadic parathyroid adenomas using technetium-99m-sestamibi : What role in clinical practice?

Preoperative localization of pathologic parathyroid glands remains controversial. Because experienced parathyroid surgeons can identify and cure parathyroid pathology in sporadic primary hyperparathyroidism in better than 95 per cent of first-time explorations, few consider preoperative localization studies cost effective in this population. However, the primary reason for failure at the initial exploration is the inability of the surgeon to identify an adenoma in a normal anatomical location. Recent reports have indicated that operative time can be reduced and initial success improved with preoperative localization of adenomas using the highly sensitive technetium-99m (Tc)-sestamibi scan. We evaluated 16 consecutive patients with sporadic primary hyperparathyroidism using a double-phase Tc-sestamibi scan with delayed images, hypothesizing that 90 per cent of adenomas would be accurately detected, and furthermore that a negative scan would predict multigland disease. Of the 16 scans, 13 showed a focal delayed washout of the tracer, constituting a positive scan. Eleven of 13 were true positive (85%), with two false positive scans (15%), both of which also had nodular thyroid disease. The three negative scans were indeed hyperplastic multigland disease, determined at exploration. The mean operative time for a bilateral exploration for the true positive cases was 109 minutes, compared to 148 minutes for a small cohort group without imaging (not significant). In conclusion, 85 per cent of adenomas can be successfully localized with the Tc-sestamibi delayed-image technique, and may decrease operative time. Additionally, a negative scan is a likely predictor of multigland disease, which allows for improved preoperative patient education and preparation for cryopreservation. These data suggest that preoperative Tc-sestamibi scanning may improve the success rate for the occasional parathyroid surgeon, and that an extended prospective trial is warranted.