[Analysis of influencing factors for preoperative negative 99mTc-MIBI imaging in patients with single parathyroid tumor].

Objective

To explore the influencing factors of negative preoperative technetium-99m methoxyisobutyl isonitrile（99mTc-MIBI） imaging in patients with single parathyroid adenoma.

Methods

A total of 378 patients with single parathyroid tumors who underwent primary open cervical surgery were retrospectively enrolled. According to the results of preoperative 99mTc-MIBI imaging results, the patients were divided into the 99mTc-MIBI negative group and positive group. The baseline data, laboratory indicators, imaging findings and pathological characteristics were compared between the two groups to analyze the correlative and independent influencing factors of preoperative negative 99mTc-MIBI results. ROC curve analysis was performed to evaluate the predictive value of preoperative serum calcium and tumor volume for 99mTc-MIBI negativity.

Results

Of the 378 enrolled patients, postoperative pathology confirmed 372 cases（98.4%） of parathyroid adenoma and 6 cases（1.6%） of atypical parathyroid tumor. Among them, 70 patients（18.5%） presented with negative preoperative 99mTc-MIBI scintigraphy results. Compared with the 99mTc-MIBI positive group, the negative group had a milder elevation of preoperative serum calcium, lower alkaline phosphatase（ALP） levels, a lower proportion of tumor cystic degeneration and smaller tumor volume, with all differences being statistically significant（P<0.05）. Multivariate Logistic regression analysis demonstrated that mild preoperative hypercalcemia and small tumor volume were independent risk factors for 99mTc-MIBI negativity. ROC curve analysis showed that the area under the curve（AUC） of preoperative serum calcium for predicting99mTc-MIBI negativity was 0.612（95%CI 0.538-0.687, P<0.01）, with an optimal cut-off value of 2.59 mmol/L. The AUC of tumor volume was 0.750（95%CI 0.692-0.808, P<0.01）, and the optimal cut-off value was 563 mm³. The median follow-up duration was 39.5 months, and the biochemical cure rate was 99.7%.

Conclusion

In patients with single parathyroid tumors, the correlated factors for negative preoperative 99mTc-MIBI imaging included mild elevation of preoperative serum calcium, low ALP level, absence of tumor cystic degeneration and small tumor volume. Among these factors, mild preoperative hypercalcemia and small tumor volume were independent risk factors for negative 99mTc-MIBI imaging.