Meterials and Methods

Subjects

Between October 2010 and February 2011, 85 consecutive breast cancer patients who were referred for preoperative MRI were prospectively enrolled in our study. Among these patients, we excluded those who demonstrated a non-mass enhancement (NME) pattern on MRI (n = 16), those with inflammatory breast cancer (n = 2), and those with bilateral breast cancer (n = 1). Finally, 66 patients (all women; mean age, 52.5 yr; age range, 29-82 yr) were enrolled in our study.

Results

Our study included 66 malignant breast masses in 66 patients; all masses were invasive ductal carcinomas with a mean diameter of 28.92 mm (range, 6-89 mm).

Discussion

Quantitative ADC measurements using DWI are a promising tool for improving the specificity of MRI for the diagnosis of malignant breast masses. Recent studies concerning this technique show the potential for improving the positive predictive value (PPV) of breast MRI for lesions of various types and sizes (6, 7, 22, 23). According to one study, applying an ADC threshold of 1.81×10-3 mm2/sec for 100% sensitivity produced a PPV of 47% vs. 37% for dynamic contrast-enhanced MRI alone (22). Moreover, ADC measurements have the potential to allow monitoring of the malignant breast mass and evaluation of the response to antitumor treatment (10). However, the practical application of ADC measurements remains controversial and requires standardization according to the imaging equipment and institutional protocol (24). Therefore, knowledge of the reproducibility of ADC measurements is of great importance for accurate interpretation of changes in the ADCs. For example, changes in the ADC values on follow-up DWI could result from measurement error or from actual changes caused by the tumor's response to treatment.