Objective  This study aims to investigate the clinical significance of the semi-quantitative analysis of low-dose ^99mTc-methoxy isobutyl isonitrile(MIBI) double phase tomographic imaging in breast cancer diagnosis.

  Methods  A total of 109 patients with breast lesions and 26 normal breasts underwent double-phase ^99mTc-MIBI tomographic imaging using a self-designed imaging device.The early and the delayed tumor to non-tumor ratios(T/NT) were calculated by semi-quantitative image analysis(SQA).The results were compared with that of the pathological results.

  Results  The early phase T/NT ratios in the normal control, benign, and breast cancer groups were 1.09±0.18, 1.77±1.36, and 3.98±3.11, respectively.The difference was statistically significant(P < 0.05).The difference of the early and delayed phase T/NT ratios in the normal control group was not statistically significant(1.09±0.18 vs.1.08±0.19, > 0.05).The difference in the benign group was statistically significant(1.77±1.36 vs.1.28±0.83, P < 0.05), whereas that of the breast cancer group was not statistically significant(3.98±3.11 vs.3.04±2.46, P > 0.05).The sensitivity of the semi-quantitative analysis in the diagnosis of breast cancer was 97.67%, the specificity was 81.82%, and the accuracy was 88.07%.The positive and negative values were 77.78%(42/54) and 98.18%(54/55), respectively.

  Conclusion  Low dose 99mTc-MIBI double-phase tomography imaging is an effective method to detect breast cancer, and has great clinical value in the differentiation of malignant and benign breast lesions.