Potential of MR mammography to predict tumor grading of invasive breast cancer.

PURPOSE: Tumor grading (TG) is one of the most widely used prognostic factors in the case of breast cancer. This study aims to identify the potential of magnetic resonance mammography (MRM) to non-invasively assess TG. MATERIALS AND METHODS: 399 invasive breast cancers were included (IRB approval; standardized clinical MRM protocols). All breast cancers were prospectively evaluated by two experienced (> 500 MRM) and blinded radiologists in consensus. In every cancer a set of 18 previously published MRM descriptors was assessed. These were assessed by univariate and multivariate analysis to identify the potential of MRM to predict TG (X2 statistics; binary logistic regression; area under the ROC curve [AUC]). RESULTS: 8 of 18 MRM descriptors were associated with TG, e. g. internal structure, edema (p < 0.001), as well as skin thickening and destruction of the nipple line (p < 0.05). MRM was feasible to predict TG by multivariate analysis (p < 0.001). The highest potential could be identified to predict well differentiated breast cancers with good prognosis (AUC = 0.930). CONCLUSION: MR mammography was able to non-invasively assess tumor grading in a standard protocol. Since tumor grading is a surrogate for overall survival, these results provide further evidence to the clinical application of MR mammography as a noninvasive prognostic tool.

Clinical MR mammography: impact of hormonal status on background enhancement and diagnostic accuracy.

PURPOSE: Hormonal stimulation can induce background enhancement (BE) in MR mammography (MRM). This fact has been assumed to decrease the accuracy of MRM. Consequently, this report investigates: 1. The prevalence of BE in postmenopausal vs. premenopausal women in correlation to hormonal cycle phase (CP). 2. The impact of hormonal status (HS) and BE on diagnostic accuracy. MATERIALS AND METHODS: Consecutive patients over 22 months with complete HS information (week of CP or postmenopausal) were included in this prospective investigation. Exclusion criteria were any hormonal therapy, hysterectomy as well as cancer proven by biopsy. The standard of reference was histopathology. All MRM scans were acquired using the same protocol (1.5 T, dynamic T 1w GRE after 0.1 mmol/kg bw Gd-DTPA i. v.). Two radiologists rated all examinations in consensus according to BI-RADS. BE was defined as: 0 = missing, 1 = moderate, 2 = distinct. RESULTS: 224 patients (150 postmenopausal, 74 premenopausal, 45 in the second week of CP) were included in this study (83 benign and 141 malignant findings). BE was more frequent in premenopausal women (p = 0.006), but did not differ between CP (p = 0.460). Neither HS nor BE had a significant impact on the diagnostic parameters of MRM (p ≥ 0.375). However, regarding BE, the relative number of false positive (FP) findings was highest (5 / 10; 50 %) in the distinct BE group. Regarding HS, 17 % more FP findings were observed in premenopausal women examined outside the second week of CP. CONCLUSION: In premenopausal women, HS leads to increased BE of breast tissue, independent of CP. Distinct BE and less pronounced, non-optimal CP may lead to an increased number of false positive findings.

Magnetic resonance mammography in small vs. advanced breast lesions - systematic comparison reveals significant impact of lesion size on diagnostic accuracy in 936 histologically verified breast lesions.

PURPOSE: This study was conducted to investigate the appearance of breast lesions in MR mammography (MRM) as a function of size and to identify the potential impact on diagnostic accuracy. MATERIALS AND METHODS: 936 histologically verified breast lesions (standardized MRM protocol; consecutive 12-year period at our institution, diameter 5 - 50 mm) were prospectively evaluated in consensus by two radiologists with significant MRM experience. For this purpose previously published descriptors (n = 17) were used. These were summarized as the "basic catalog and extended catalog" of descriptors (BC vs. EC). According to a cut-off of 20 mm, the database was divided into the subgroups "small" (n = 669) and "advanced" (n = 267). The diagnostic accuracy of MRM in these two subgroups was then determined using BC and EC, separately (binary logistic regression analysis; AUC analysis). RESULTS: The majority of descriptors (n = 11) showed a significantly different prevalence in correlation with size (p < 0.05). The diagnostic accuracy of MRM for "advanced" lesions (AUC = 0.969) was significantly higher (p < 0.001). This difference was significantly decreased (p < 0.001), if instead of BC (AUC = 0.865) EC was applied for the assessment of "small" lesions (AUC: 0.908 vs. 0.865). CONCLUSION: The typical appearance of breast lesions in MRM depends on lesion size. This resulted in lower diagnostic accuracy in small lesions compared to advanced findings. This difference was able to be significantly decreased by applying the catalog of extended descriptors.

Value of ductal obstruction sign in the differentiation of benign and malignant breast lesions at MR imaging.

PURPOSE: MR-Mammography (MRM) is regarded as the most sensitive method for detection of breast cancer without a broad consensus on specificity. There is room for improvement of the existing ACR BIRADS lexicon by adding new and specific descriptors. Dilated ducts have been described in association with papillomas. However, the differential diagnostic value of this finding has not been investigated yet. MATERIALS AND METHODS: 316 consecutive patients, undergoing histopathologic workup after MR-Mammography were included in this prospective, ethical review board approved study. Two blinded radiologists rated the images in consensus. Ductal obstruction was defined as dilated liquid filled ducts proximal an enhancing lesion. Sensitivity, specificity as well as positive and negative likelihood ratio (LR+, LR-) were calculated. RESULTS: Dilated ducts were found in 60 cases (19%), 20 of these showed an association with enhancing lesions and were categorized as ductal obstruction (6.3%). Malignancy was found in two cases (one invasive ductal carcinoma and one DCIS) and benign tissue in 18 cases (15 papillomas). The difference of ductal obstruction between these groups was found to be highly significant in two-sided Fisher's exact test (p<0.001). Because of the clear association with benign lesions, benign lesions showing ductal obstruction were characterized as true positive findings. Therefore, following diagnostic parameters were calculated: sensitivity 15.4%, specificity 99.0%, LR+ 15.3, LR- 0.9. DISCUSSION: If ductal obstruction is found to be positive, the associated lesion is most likely benign. Therefore, though a rare finding, this descriptor should be taken into account for improved lesion differentiation.

Can color-coded parametric maps improve dynamic enhancement pattern analysis in MR mammography?

PURPOSE: Post-contrast enhancement characteristics (PEC) are a major criterion for differential diagnosis in MR mammography (MRM). Manual placement of regions of interest (ROIs) to obtain time/signal intensity curves (TSIC) is the standard approach to assess dynamic enhancement data. Computers can automatically calculate the TSIC in every lesion voxel and combine this data to form one color-coded parametric map (CCPM). Thus, the TSIC of the whole lesion can be assessed. This investigation was conducted to compare the diagnostic accuracy (DA) of CCPM with TSIC for the assessment of PEC. MATERIALS AND METHODS: 329 consecutive patients with 469 histologically verified lesions were examined. MRM was performed according to a standard protocol (1.5 T, 0.1 mmol/kgbw Gd-DTPA). ROIs were drawn manually within any lesion to calculate the TSIC. CCPMs were created in all patients using dedicated software (CAD Sciences). Both methods were rated by 2 observers in consensus on an ordinal scale. Receiver operating characteristics (ROC) analysis was used to compare both methods. RESULTS: The area under the curve (AUC) was significantly (p=0.026) higher for CCPM (0.829) than TSIC (0.749). The sensitivity was 88.5% (CCPM) vs. 82.8% (TSIC), whereas equal specificity levels were found (CCPM: 63.7%, TSIC: 63.0%). CONCLUSION: The color-coded parametric maps (CCPMs) showed a significantly higher DA compared to TSIC, in particular the sensitivity could be increased. Therefore, the CCPM method is a feasible approach to assessing dynamic data in MRM and condenses several imaging series into one parametric map.

[Clinical value of computer-assisted analysis in MR mammography. A comparison between two systems and three observers with different levels of experience]. / Klinische Wertigkeit computergestützter Analysen in der MR-Mammografie. Ein Vergleich zwischen zwei Systemen und drei Untersuchern mit unterschiedlicher Erfahrung.

PURPOSE: The value of computer-assisted detection (CAD) used in magnetic resonance (MR) mammography in a clinical setting is currently a subject of controversy. This study evaluated the extent to which color-coded CAD systems aid radiologists with different levels of experience in their reading of MR mammographies. MATERIALS AND METHODS: In this prospective study, 48 patients with a total of 88 lesions (43 malignant, 45 benign) were included. All examinations were performed on a 1.5 Tesla MR scanner with intravenous application of 0.1 mmol gadopentetate dimeglumine/kg body weight. Three readers independently analyzed the images without knowledge of the clinical data; radiologists 1 and 2 were much more experienced in the interpretation of MR mammographies than radiologist 3. Initially, the observers visually categorized the lesions as benign or malignant following classification of BI-RADS (Breast Imaging Reporting and Data System). The readers also scored their own confidence level using a dichotome score (1: unsure vs. 2: sure) according to the BI-RADS classification. The images were then analyzed in a blinded manner with two technically different CAD systems: the full-time point (FTP) method (Cadsciences; White Plains, NY, USA) and the Dynacad version 1.1 (Invivo; Pewaukee, WI, USA). RESULTS: After CAD, all three readers classified more malignant lesions as BI-RADS 4 or 5 (suspicious or highly suggestive of malignancy). However, this increase in sensitivity revealed only statistical significance for observer 3 (p < 0.05). After CAD, the two experienced readers categorized about the same quantity of benign lesions correctly as BI-RADS 2. Observer 3 classified less benign lesions as BI-RADS 2 after both CAD analyses; i. e. the specificity decreased. The subjective confidence of all observers increased after analysis with Dynacad. Observer 3 also reported to be more confident after the FTP method. CONCLUSION: Computer-assisted detection can be a useful additional diagnostic tool for the radiologist in the interpretation of MR mammographies, but does not have the potential to replace the professional experience of a radiologist.