Objective:To evaluate the clinical value of 99Tcm-MIBI double-phase imaging on anatomical diagnosis of primary hyperparathyroidism(PHPT).Methods:Double phase 99Tcm-MIBI imaging was performed in 15 normal controls and 51 patients with primary hyperparathyroidism proven by physical examination and biochemical blood tests(for the latter group

the examination was performed in 1 week before the operation).Tomographic scanner was arranged for part of the patients.The uptake ratio was calculated and compared by ROI sequence.Results:Comparing the imaging results with those of histopathology

the sensitivity percentages of early and delayed phases to parathyroid adenomas were 78.3%(36/46)and 91.3%(42/46)

and those to parathyroid hyperplasia were 23.8%(5/21)and 47.6%(10/21)respectively.Six lesions of parathyroid were demonstrated by SPECT tomographic imaging.The positive rate of lesions(weighting between 500 to 1500 mg)was 82.4%

and all lesions over 1500 mg appeared to be positive

those less than 500mg appeared to be negative in 99Tcm-MIBI double-phase imaging.For positive parathyroid adenoma group

the uptake ratio of delayed phase was significant higher than that of early phase(P<0.01)

and the ratio of both phases were significant higher than that of the normal controls(P<0.01).Conclusion:99Tcm-MIBI double-phase imaging had higher clinical value on anatomical diagnosis of PHPT

and the measurement of uptake ratio and tomographic imaging were beneficial for improving the positive diagnosis rate.