Role of pre-operative imaging using 99mTc-MIBI and neck ultrasound in patients with secondary hyperparathyroidism who are candidates for subtotal parathyroidectomy.

PURPOSE: The purpose of this study was to assess whether pre-operative (99m)Tc-methoxyisobutylisonitrile (MIBI) scintigraphy and neck ultrasound (US) are of value in improving the outcome of subtotal parathyroidectomy in patients with secondary hyperparathyroidism.

METHODS: Forty-eight consecutive haemodialysis patients with severe secondary hyperparathyroidism prospectively underwent "blinded" subtotal parathyroid surgery, with 1-year follow-up to establish cure or relapse of their secondary hyperparathyroidism. Double-phase (99m)Tc-MIBI scintigraphy and neck US were performed pre-operatively in all patients. When the preserved gland showed (99m)Tc-MIBI uptake or an abnormal size on US, it was considered that "(99m)Tc-MIBI advice" and "US advice", respectively, had not been followed. Pre-operative and follow-up parathyroid hormone (PTH) levels were obtained in all patients. All data were evaluated on a patient by patient basis.

RESULTS: Four parathyroid glands were identified in each patient at primary surgery, resulting in an operative success rate of 100%. Their weight ranged from 15 to 7,300 mg (mean 1,120+/-900 mg). Nine of the 48 patients (19%) showed a recurrence of their secondary hyperparathyroidism. The recurrence rate was 2% (1/48) and 10% (5/48), respectively, when (99m)Tc-MIBI and US advice was followed. The sensitivity, specificity, NPV and PPV for pre-operative imaging were 72%, 95%, 97% and 80% respectively for (99m)Tc-MIBI, and 55%, 67%, 87% and 28% for US.

CONCLUSION: (99m)Tc-MIBI scintigraphy is a reliable non-invasive exploratory tool and its preoperative use results in a significant reduction in the number of recurrences in haemodialysis patients with secondary hyperparathyroidism who are candidates for subtotal parathyroidectomy. The use of neck US did not significantly improve the results obtained with (99m)Tc-MIBI alone.