Objective      To investigate the differences in calcification and pathologic features of

99

Tc

m

-MIBI SPECT/CT fusion imaging between secondary hyperparathyroidism (SHPT) and primary

hyperparathyroidism (PHPT).       Methods      Clinical data of 53 patients with hyperparathyroidism (HPT)

including 23 SHPT patients and 30 PHPT

who underwent dual-phase

99

Tc

m

-MIBI scintigraphy and SPECT/CT fusion imaging in our department from December 2011 to May 2013 were collected and retrospectively analyzed. All of the 53 patients were confirmed by postoperative pathology. The number of calcifications within parathyroid and the pathological findings were analyzed and compared between PHPT patients and SHPT patients.       Results      The dual-phase parathyroid scintigraphy was positive (positive rate 79.2%) in 42 cases of 53 HPT patients. All of the patients with positive uptake in dual-phase images presented positive in the SPECT/CT fusion images. In SPECT/CT fusion images

48 patients showed

99

Tc

m

-MIBI uptake within parathyroid. CT scans detected soft tissue density nodules in the remaining 5 patients without

99

Tc

m

-MIBI uptake in parathyroid area. Among the 23 SHPT patients

the pathological findings were parathyroid adenoma in 10 cases (43.5%)

parathyroid hyperplasia in 12 cases (52.2%) and containing both parathyroid adenoma and parathyroid hyperplasia tissues in 1 case (4.3%). Of them

calcifications were found in the parathyroid of 9 (39.1%) patients. In 30 PHPT patients

29  cases (96.7%) had parathyroid adenoma and 1 case (3.3%) had parathyroid hyperplasia. No parathyroid calcification was found in these PHPT patients. The number of calcifications in the adenoma and the occurrence of parathyroid adenoma between SHPT and PHPT patients had statistical significance (Chi-square=11.50 and 15.13

both P0.05).       Conclusion      Compared with PHPT patients

SHPT patients are more likely to be found having calcification. Most of pathological findings of PHPT are parathyroid adenoma. The pathological findings of SHPT are mostly parathyroid hyperplasia

followed by parathyroid adenoma.