PurposeTo investigate associations between the clinicopathologic features and MRI features of triple-negative breast cancer (TNBC) and ER-positive breast cancer (BC) via apparent diffusion coefficient (ADC) histogram analysis.Materials and methodsIn this study, 221 breast cancer patients with pre-operative MRI performed from August 2009 to March 2015 were included in a retrospective analysis. All patients had a pathologically confirmed diagnosis of invasive carcinoma and were grouped into ER-positive (149) or triple-negative (72) subtypes. DWI rim sign and various ADC parameters (mean; mode; 25, 50, and 75 percentiles; skewness; and kurtosis) between ER-positive and TNBC were compared using whole-lesion ADC histogram analysis. Univariate and multivariate regression analyses were used for statistical comparison.ResultsDWI rim signs were detected in 42.3% and 41.7% of ER-positive subtype and TNBC, respectively (P = 0.931). TNBC had poorer histologic grade (P<0.001) and higher Ki-67 expression (P <0.001) than ER-positive subtype BC. TNBC displayed higher ADC parameters (mean, mode, 50th & 75th percentiles, kurtosis on univariate analysis, all P<0.001; only kurtosis on multivariate anaylsis; P<0.001) than ER-positive subtype BC. TNBC had significantly more recurrence events than ER-positive subtype BC on univarate analysis (9.7% (7/72) vs. 2.7% (4/149), P = 0.035).ConclusionPoorer clinicopathologic outcomes were found in TNBC. Whole-lesion ADC histogram analysis revealed ADC kurtosis to be higher in TNBC than ER-positive subtype BC.

Purpose To investigate the diagnostic performance and tissue changes in early (1 year or less) breast magnetic resonance (MR) imaging surveillance in women who underwent breast conservation therapy for breast cancer. Materials and Methods This prospective study was approved by the institutional review board, and written informed consent was obtained. Between April 2014 and June 2016, 414 women (mean age, 51.5 years; range, 21-81 years) who underwent 422 early surveillance breast MR imaging examinations (median, 6.0 months; range, 2-12 months) after breast conservation therapy were studied. The cancer detection rate, positive predictive value of biopsy, sensitivity, specificity, accuracy, and area under the curve of surveillance MR imaging, mammography, and ultrasonography (US) were assessed. Follow-up was also obtained in 95 women by using positron emission tomography (PET)/computed tomography (CT). Background parenchymal enhancement (BPE) changes in the contralateral breast were assessed according to adjuvant therapy by using the McNemar test. Results Of 11 detected cancers, six were seen at MR imaging only, one was seen at MR imaging and mammography, two were seen at MR imaging and US, one was seen at mammography only, and one was seen at PET/CT only. Three MR imaging-depicted cancers were observed at the original tumor bed, and two MR imaging-depicted cancers were observed adjacent to the original tumor. Among two false-negative MR imaging diagnoses (two cases of ductal carcinoma in situ), one cancer had manifested as calcifications at mammography without differentiated enhancement at MR imaging, and the other cancer was detected at PET/CT, but MR imaging results were negative because of marked BPE, which resulted in focal lesion masking. The positive predictive value of biopsy and the sensitivity, specificity, accuracy, and area under the curve for MR imaging were 32.1% (nine of 28), 81.8% (nine of 11), 95.1% (391 of 411), 94.7% (400 of 422), and 0.88, respectively. The sensitivity of surveillance MR imaging (81.8%; 95% confidence interval [CI]: 48.2%, 97.7%) was higher than that of mammography (18.2%; 95% CI: 2.3%, 51.8%) and US (18.2%; 95% CI: 2.3%, 51.8%), with an overlap in CIs. The BPE showed a significant decrease in the group of patients who received adjuvant chemotherapy (43 BPE decreases and four BPE increases) and the group of patients who received hormone therapy (55 BPE decreases and two BPE increases) (P < .0001 for both). Conclusion Early MR imaging surveillance after breast conservation therapy can be useful in patients who have breast cancer, with superior sensitivity compared with that of mammography and US. The BPE tends to be decreased at short-term follow-up MR imaging in patients who receive adjuvant therapy. RSNA, 2017.

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