Patient’s demographic data
This retrospective study was approved by our institution’s ethics committee. The medical records and the preoperative MRI studies of 125 female patients with primary breast cancer and prepared for surgery (MRM, SSM, or NSM) were reviewed from the period of August 2018 till September 2020. Their age ranged from 28 to 70 years (mean ± SD = 44.8 ± 8.96). Out of the 125 female patients, 77 patients underwent MRM, 30 patients underwent SSM, and 18 patients underwent NSM. After reviewing the pathological reports, we found that 33 cases (26.4%) showed malignant NAC invasion and 92 cases (73.6%) showed free NAC. We had 9 cases with DCIS, 109 cases with IDC, and 7 cases with invasive lobular carcinoma.
Inclusion criteria included female patients with primary breast cancer and prepared for surgery (MRM, SSM, or NSM).
Exclusion criteria included patients who were referred to other hospitals and their pathological reports were not available, patients who received neoadjuvant chemotherapy, and patients with advanced disease stage (stage IV) because they were not amenable for surgery.
MRI breast for 125 female patients was performed using 1.5 T MR imaging unit (Philips Ingenia). All patients were examined in the prone position by using a dedicated breast coil. All patients underwent the following: (A) localizing sagittal protocol (scout view); (B) axial non-fat-suppressed T1W fast spin-echo images, with the following parameters: TR/TE 450/14 ms, slice thickness 3 mm, field of view (FOV) 300–360 mm, and matrix 307 × 512; (C) axial non-fat-suppressed T2W turbo spin-echo images with the following parameters: TR/TE 4500/97 ms, slice thickness 3 mm, and matrix 384 × 512; (D) axial STIR images with the following parameters: TR/TE 7000–9000/70 ms, TI 150 ms, slice thickness 3–4 mm, inter-slice gap 1 mm, FOV 300–360 mm, and matrix 307 × 512; and (E) dynamic MR images were obtained in the axial plane with fat suppression. The sequence used was FLASH 3-D GRE-T1WI with the following parameters: TR/ TE 4–8/2 ms, flip angle 20–25, slice thickness 2 mm, no inter-slice gap, FOV 300–360 mm, and matrix 307 × 512. Dynamic MR images were obtained after injecting a bolus of gadopentetate dimeglumine at a dose of 0.2 mmol/kg using an automated injector at a rate of 3–5 ml/s. This was followed by a bolus injection of saline (total of 20 ml at 3–5 ml/s).
Image post-processing includes (A) image subtraction obtained by subtracting each of the pre-contrast images from each post-contrast series image and (B) maximum intensity projection (MIP) images obtained through each orthogonal plane, producing sagittal, coronal, and axial projection.
Using a secondary workstation (Phillips Advantage windows workstation with functional tool software), MR images were analyzed by two radiologists (ME, DE) with breast imaging experience for 14 and 9 years. They were blinded to the clinical and pathological data of the patients. The two radiologists joined and reached a correspondence for controversial cases.
The assessed signs on dynamic MR images were (A) malignant mass pattern (mass lesion or non-mass enhancement); (B) tumor size (TS) (maximum diameter of the lesion, if multiple lesions present we took the maximum diameter of the largest lesion); (C) nipple morphology (NM) (normal or retracted nipple) was assessed on axial T1WI and axial STIR image; (D) symmetry of nipple morphology was assessed on MIP images; (E) tumor nipple enhancement (TNE) (presence of enhancement between tumor and nipple base assessed on early subtraction MR images); (F) tumor nipple distance (TND) (measured from the tumor margin to the base of the nipple on early subtraction MR images); (G) abnormal asymmetric nipple enhancement assessed on early subtraction MR images; and (H) thickening of the periareolar skin when compared with the contralateral NAC, it was assessed on early subtraction MR images.
The pathological reports after surgery were reviewed and the following data were collected: (1) presence of malignant NAC invasion (malignant NAC invasion was defined on pathology as the presence of IDC, DCIS, or invasive lobular carcinoma within the retro-areolar tissue), (2) histologic tumor type, (3) tumor grade, (4) presence of lymphovascular metastasis, (5) presence of lymph node metastasis, and (6) hormone receptor status (ER, PR, Her 2, and Ki67).
Data were fed to the computer and analyzed using IBM SPSS Corp., released 2013, IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp. Qualitative data were described using number and percent. Quantitative data were described using median (minimum and maximum), interquartile range for non-parametric data, and mean and standard deviation for parametric data after testing normality using the Shapiro-Wilk test. The significance of the obtained results was judged at the (0.05) level. Student t test was used to compare 2 independent groups. The diagnostic performance (accuracy) of a test to discriminate diseased cases from non-diseased cases is evaluated using receiver operating characteristic (ROC) curve analysis. Sensitivity and specificity were detected from the curve. PPV, NPV, and accuracy were calculated through cross-tabulation. The multivariate logistic regression model was done to determine the best combined parameters for the prediction of malignant NAC invasion by generating AUC with 95% confidence intervals.