Clinical implications of brown tumor uptake in whole-body 99mTc-sestamibi scans for primary hyperparathyroidism.

OBJECTIVES

Technetium-99m (Tc)-sestamibi is the current radionuclide of choice for parathyroid localization in primary hyperparathyroidism (PH). However, there are only sporadic reports about brown tumor visualization in whole-body Tc-sestamibi scans. This study aimed to systematically evaluate brown tumor uptake in whole-body Tc-sestamibi scans and in whole-body bone scans as well. Clinical factors were statistically analyzed for imaging outcome predictions.

METHODS

Forty-two patients with PH were recruited consecutively. A dual-tracer, dual-phase parathyroid imaging protocol was applied. A Tc-sestamibi whole-body scan was performed immediately after delayed phase acquisition. A Tc-methylene diphosphonate bone scan was performed on day 3. Parathormone (PTH), calcium, alkaline phosphatase (ALP), and parathyroid lesion volume were compared. The t-test, one-way analysis of variance, and receiver operating characteristic curves were performed for statistical analyses.

RESULTS

Brown tumors showed Tc-sestamibi uptake in 10 cases, and Tc-methylene diphosphonate uptake in 17 cases. All parameters in double-scan positive cases were significantly higher than in double-scan negative cases; PTH and ALP were significantly higher in only bone scan positive cases than in double-scan negative cases. Data from receiver operating characteristic curves showed the order of PTH>ALP>Ca>parathyroid lesion volume for diagnostic accuracies of both positive Tc-sestamibi scans and positive bone scans. PTH showed the best positive predictive value and ALP showed the best negative predictive value.

CONCLUSION

A Tc-sestamibi whole-body scan could be used to assess brown tumors in PH, although it may be less sensitive than a bone scan. PTH possessed the best diagnostic accuracy and predictive value for a positive imaging outcome. ALP was useful for negative imaging outcome prediction.