Molecular breast imaging (MBI) with high resolution dedicated breast camera (DBC) vs breast dynamic magnetic resonance imaging (MRI) in the preoperative local staging of breast cancer

Objectives We compared the performance of MBI with high resolution DBC and dynamic breast MRI in preoperative local staging of breast cancer.

Methods We prospectively studied a consecutive series of 29 female patients (38-74 yrs) with breast cancer scheduled to surgery. All patients preoperatively underwent both 99mTc-tetrofosmin MBI in craniocaudal and mediolateral oblique views using a CZT DBC and dynamic contrast-enhanced breast MRI imaging at 1.5 T using a three-dimensional gradient-echo sequence before and after intravenous gadoteridol injection. In all cases, MBI and MRI findings were mutually compared and both of these were correlated with definitive histopathological findings.

Results MBI and MRI were true positive in 28/29 (96.5%) and in 27/29 (93.1%) breast cancer patients, respectively. Both procedures were false negative in a patient with a T1b invasive ductal carcinoma, whereas only MRI was false negative in further one patient with DCIS. According to surgical findings, MBI correctly assessed cancer extent in 25/28 (89.3%) and MRI in 22/27 (81.5%) of positive cases. MBI overstaged local disease in 1 case and downstaged disease in 2 cases, while MRI overstaged disease in 4 cases and downstaged disease in 1 case. Only MBI correctly staged 4 patients, including 3 patients with an invasive tumor each overstaged at MRI and the patient with a DCIS false negative at MRI. The correct staging was achieved only by MRI in one patient who was dowstaged by MBI which missed the intraductal component around an invasive carcinoma. The 2 procedures gave concordant findings in 24/29 overall cases (82.7%).

Conclusions Both MBI with high resolution DBC and breast dynamic MRI proved valuable diagnostic tools in the preoperative local staging of breast cancer with concordant results in a high percentage of cases. However, in our patients, MBI demonstrated better performance than MRI which showed a higher tendency to overstaging local disease extension in respect of surgical findings