Correlations between biochemical testing, pathology findings and preoperative sestamibi scans: a retrospective study of the minimally invasive radioguided parathyroidectomy (MIRP) approach.

BACKGROUND: Sestamibi imaging is the most widely used preoperative localization study for patients with hyperparathyroidism. Previous reports examine the relationship between the weight and volume of excised parathyroid glands and preoperative serum calcium and parathyroid hormone (PTH) levels. The aim of this study was to examine whether these variables correlate with the results of preoperative Sestamibi scans.
MATERIAL AND METHODS: A retrospective review of 150 consecutive patients who underwent preoperative sestamibi imaging for primary hyperparathyroidism between 1998 and 2007 was performed. Variables studied included patient demographics, diagnostic test (sestamibi) results, operative/pathology findings and surgical outcome (normocalcaemia vs. persistent hypercalcaemia). Sestamibi scans were designated as either "negative" (NSS) or "positive" (PSS), where PSS correctly localized abnormal gland(s) enabling a focused neck exploration. The results of sestamibi imaging were correlated with calcium/PTH levels, weight/volume of excised glands and patient outcomes and demographics.
RESULTS: Total excised gland weight/volume and preoperative serum calcium levels were significantly higher with PSS (all, p < 0.04). Higher preoperative serum calcium levels and greater total gland weight/volume were significantly associated with successful operative outcome (presence of postoperative normocalcaemia; all, p < 0.01). Factors associated with operative failure included multi-gland disease (p < 0.01) and NSS (p < < 0.01). Higher diagnostic PTH levels (> 150 pg/mL) were associated with greater excised gland mass (p < 0.05) and volume (p < 0.05). Male gender was associated with higher preoperative serum calcium levels (p < 0.02). Of interest, patients with single-gland disease had significantly higher preoperative PTH levels than patients with multi-gland disease (155 vs. 109 pg/mL, p < 0.05).
CONCLUSION: Positive sestamibi scans are associated with heavier/larger parathyroid glands and higher preoperative serum calcium levels. Male gender was associated with higher preoperative serum calcium levels, while single-gland disease was associated with higher preoperative PTH levels. In addition, successful surgical outcome was associated with higher preoperative serum calcium levels and with greater excised parathyroid gland mass/volume. Surgical failure was associated with multi-gland disease and negative sestamibi.