Incremental diagnostic value of quantitative analysis of double phase Tc-99m MIBI scintimammography for the detection of primary breast cancer additive to visual analysis

Tc-99m MIBI scintimammography (SMM) is known to be a useful diagnostic tool for primary breast cancer. We conducted this study to establish optimal visual grades for the detection of primary breast cancer and to investigate whether the quantitative indices of double phase SMM could provide incremental diagnostic value additive to visual analysis. Five hundred and twenty highly suspected breast cancer patients (malignant: 370; benign: 150) were included in this study. Double phase Tc-99m MIBI SMM (early: 10 min; delayed: 3 h) was performed after injection of 750 MBq of Tc-99m MIBI. For visual analysis, five scoring method was used. The early and delayed lesion to non-lesion ratios (L/N) and retention index (RI) were calculated. Receiver operating characteristic curve (ROC) analyses was performed to determine the optimal visual grade, to calculate cut-off value of quantitative indices for differentiation malignant and benign diseases and to investigate whether the quantitative indices could provide incremental diagnostic value additive to visual analysis. To investigate the incremental diagnostic value of quantitative index in variable tumor size groups, the patients were subdivided into four groups (group A: size