Dual-phase (99m)Tc-MIBI scintigraphy with delayed neck and thorax SPECT/CT and bone scintigraphy in patients with primary hyperparathyroidism: correlation with clinical or pathological variables.

PURPOSE: The purpose of this study was to assess the relationship between (99m)Tc-MIBI and (99m)Tc-MDP bone scintigraphy and clinical or pathological variables, including preoperative serum PTH levels and tumor diameter, in patients with newly diagnosed PHPT.

METHODS

Dual-phase (99m)Tc-MIBI planar scintigraphy was performed in 244 patients with PHPT. Of these patients, 155 underwent (99m)Tc-MDP bone scintigraphy to detect bone changes before parathyroidectomy. Factors influencing (99m)Tc-MIBI scintigraphy and (99m)Tc-MDP bone scintigraphy detection rate were assessed using univariate and multivariate logistic regression analysis; optimal cutoff values for predicting positive (99m)Tc-MIBI and (99m)Tc-MDP bone scintigraphy were evaluated using ROC analysis.

RESULTS

Among 244 patients, 174 (71.31 %) patients with 181 foci had a positive (99m)Tc-MIBI planar scintigraphy; delayed neck and thorax SPECT/CT could identify and locate the (99m)Tc-MIBI lesions but could not find more lesions than planar scintigraphy. 70 (28.69 %) patients had a negative (99m)Tc-MIBI planar scintigraphy. Tumor diameter, serum PTH level and symptoms were statistically significant predictive factors in predicting positive (9m)Tc-MIBI scintigraphy both univariate and multivariate logistic regression analyses. The optimal thresholds for tumor diameter and serum PTH by ROC analysis were 1.03 cm and 127.60 ng/L, respectively. Among 155 patients with bone scintigraphy, (99m)Tc-MDP bone scintigraphy showed positive finding in 80 (51.61 %) patients and negative finding in 75 patients. Univariate logistic regression analysis showed that patient age, sex, tumor diameter and PTH level (≥150 ng/L) were statistically significant in predicting positive (99m)Tc-MDP bone scintigraphy. Multivariate logistic regression analysis showed both tumor diameter and PTH ≥ 150 ng/L were statistically significant in predicting positive (99m)Tc-MDP bone scintigraphy. The optimal thresholds for tumor diameter and serum PTH by ROC analysis were 1.96 cm and 163.85 ng/L, respectively.

CONCLUSIONS

The utility of delayed neck and thorax SPECT/CT over dual-phase (99m)Tc-MIBI planar scintigraphy is that it can identify and locate a parathyroid tumor in about more than 70 % of patients in PHPT and provide the assistance for surgical planning. These studies also suggest that (99m)Tc-MIBI scintigraphy and (99m)Tc-MDP bone scintigraphy are closely correlated with tumor diameter and PTH; which may show negative results when tumor diameter is small and serum PTH level is low.