Parathyroid Imaging For Preoperative Evaluation Of Primary Hyperparathyroidism

Objective:Surgery has been considered the definitive treatment for symptomatic primary hyperparathyroidism (PHPT). The traditional surgery protocol is bilateral exploration of the neck. However, given the high proportion of the solitary parathyroid adenoma as the cause of PHPT, a better treatment may be the direct excision of the hyperfunction adenoma after its preoprative identification and localization.99mTc-MIBI and ultrasound scan are the imaging modalities most often used for preoprative localization. Knowledge of the clinical and biochemical chemistry characters of PHPT may help in the identification and localization of hyperfunction parathyroid glands. The aim of this study is to analyse the clinical feature of PHPT patient, and evaluate the role of 99mTc-MIBI and ultrasound scan for abnormal parathyroid identification and localization.Methods:Medical records of hospitalized patients suspecting of PHPT from January 1st 2004 to March 1st 2010 were carefully reviewed. Forty six patients had neck surgery for PHPT, and 39 patients were confirmed by surgery and histopathology as PHPT. The left 7 patients were diagnosed as nodular goiter. Evaluate the sensitivity and specificity of the imaging modalities used in these patients. Statistically analysis the clinical features and evaluate there impact on 99mTc-MIBI imaging.Results:Ninety percent of the 39 PHPT patients had overt symptom, including bone disease (59%), urolithiasis (29%), and hypercalcemia symptom (12.8%). Only 4 patients were asymptomatic (10%). Serum calcium and PTH level decline significantly after surgery. Patients had bone disease manifestation had higher PTH and ALP level (p<0.01).In this study, the cause of PHPT was comprised of single parathyroid adenoma(84%), parathyroid hyperplasia(13%) and parathyroid adenocarcinoma(3%). The sensitivity of 99mTc-MIBI and ultrasonography for localization of hyperfunctioning glands to the correct side of neck was 87.5% and 77.5%, respectively. The specificity of 99mTc-MIBI and ultrasonography for localization of hyperfunctioing glands to the correct side of neck was 87% and 97.6%, respectively. Thirty two in 33 single adenoma cases were correctly identified and localized by 99mTc-MIBI dual phase scintygraphy. Ultrasound scan only detected 24 single adenomas. Ultrasound scan recognized all 5 hyperplasia cases, when MIBI scintigraphy missed 3 cases. Nodular goiter cases were the main false positive cases recognized by MIBI scintigraphy.99mTc-MIBI positive or ultrasound scan positive PHPT patients had higher serum calcium level than those who were negative.Conclusion:99mTc-MIBI dual phase scintigraphy and ultrasound scan are effective for preoprative abnormal parathyroid gland identification and localization. Serum calcium level may have impact on 99mTc-MIBI dual phase scintigraphy result.