Contrast-enhanced Magnetic Resonance Mammography Research Articles

Breast Lesion Detection and Characterization at Contrast-enhanced MR Mammography: Gadobenate Dimeglumine versus Gadopentetate Dimeglumine

To prospectively and intraindividually compare equivalent (0.1 mmol per kilogram of body weight) doses of gadobenate dimeglumine and gadopentetate dimeglumine for accuracy of detection and characterization of breast lesions at contrast material-enhanced magnetic resonance (MR) mammography. Ethics committee approval and informed consent were obtained. Twenty-six consecutive women (mean age, 47.8 years) suspected of having a breast tumor at mammography and sonography underwent two identical MR examinations at 1.5 T; examinations were separated by more than 48 hours but less than 72 hours. A T1-weighted three-dimensional gradient-echo sequence was used, and images were acquired before and at 0, 2, 4, 6, and 8 minutes after randomized injection of gadopentetate dimeglumine or gadobenate dimeglumine at an identical flow rate of 2 mL/sec. Separate and combined assessment of unenhanced, contrast-enhanced, and subtracted images was performed blindly by two readers in consensus. Accuracy for lesion detection was determined against a final diagnosis based on findings at conventional mammography, sonography, and surgery. Sensitivity, specificity, positive and negative predictive values, and overall accuracy for malignant lesion identification were determined against histologic results. Data were analyzed with the McNemar test, proportional odds models, and analysis of variance. MR mammography with gadobenate dimeglumine depicted significantly (P = .003) more lesions (45 of 46) than did that with gadopentetate dimeglumine (36 of 46), and detected lesions were significantly (P < .001) more conspicuous with gadobenate dimeglumine. Confidence for characterization was significantly (P = .031) greater with gadobenate dimeglumine. Comparison of the contrast agents for their ability to help identify malignant lesions revealed significant (P = .02) superiority for gadobenate dimeglumine: Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy for malignant lesion identification were, respectively, 94.7%, 100%, 100%, 80.0%, and 95.6% with gadobenate dimeglumine and 76.3%, 100%, 100%, 47.1%, and 80.4% with gadopentetate dimeglumine. Quantitative evaluation of signal intensity-time curves revealed significantly (P < .001) greater lesion enhancement with gadobenate dimeglumine. Detection of breast lesions and accurate identification of malignant lesions at MR imaging are significantly superior with gadobenate dimeglumine in comparison with gadopentetate dimeglumine.

Color-Coded Automated Signal Intensity Curves for Detection and Characterization of Breast Lesions

The objective of this study was to evaluate the value of a color-coded automated signal intensity curve software package for contrast-enhanced magnetic resonance mammography (CE-MRM) in patients with suspected breast cancer. Thirty-six women with suspected breast cancer based on mammographic and sonographic examinations were preoperatively evaluated on CE-MRM. CE-MRM was performed on a 1.5-T magnet using a 2D Flash dynamic T1-weighted sequence. A dosage of 0.1 mmol/kg of Gd-BOPTA was administered at a flow rate of 2 mL/s followed by 10 mL of saline. Images were analyzed with the new software package and separately with a standard display method. Statistical comparison was performed of the confidence for lesion detection and characterization with the 2 methods and of the diagnostic accuracy for characterization compared with histopathologic findings. At pathology, 54 malignant lesions and 14 benign lesions were evaluated. All 68 (100%) lesions were detected with both methods and good correlation with histopathologic specimens was obtained. Confidence for both detection and characterization was significantly (P < or = 0.025) better with the color-coded method, although no difference (P > 0.05) between the methods was noted in terms of the sensitivity, specificity, and overall accuracy for lesion characterization. Excellent agreement between the 2 methods was noted for both the determination of lesion size (kappa = 0.77) and determination of SI/T curves (kappa = 0.85). The novel color-coded signal intensity curve software allows lesions to be visualized as false color maps that correspond to conventional signal intensity time curves. Detection and characterization of breast lesions with this method is quick and easily interpretable.

Classification of Signal-Time Curves Obtained by Dynamic Magnetic Resonance Mammography

This study compares the performance of quantitative methods for the characterization of signal-time curves acquired by dynamic contrast-enhanced magnetic resonance mammography from 253 females. Signal-time curves obtained from 105 parenchyma, 162 malignant, and 91 benign tissue regions were examined (243 lesions were histopathologically validated). A neural network, a nearest-neighbor, and a threshold classifier were applied to either the entire signal-time curve or pharmacokinetic and descriptive parameters calculated from the curves to differentiate between 2 (malignant or benign) or 3 tissue classes (malignant, benign, or parenchyma). The classifiers were tuned and evaluated according to their performance on 2 distinct subsets of the curves. The accuracy determined for the neural network and the nearest-neighbor classifiers was nearly identical (approximately 80% in case of 3 tissue classes, and approximately 76% in case of the 2 classes). In contrast, the accuracy of the threshold classifier applied to the discrimination of 3 classes was low (65%). Quantitative classifiers can support the radiologist in the diagnosis of breast lesions.

Radial Scars of the Breast: Contrast-enhanced Magnetic Resonance Mammography Appearance

The purpose of this study was to evaluate the appearance of contrast-enhanced magnetic resonance mammography (CE-MRM) in patients with suspected radial scar on mammography. Thirty women with radial opacities or black star findings at mammography, preoperatively underwent CE-MRM. Examinations were performed with a 1.5 T magnet with a bilateral surface coil using a FS T2-weighted turbo spin echo (TSE) and three-dimensional (3D) dynamic T1-weighted fast low-angle shot (FLASH) sequences. Criteria for lesion evaluation included morphologic patterns and signal intensity curves. Mammography and CE-MRM findings were compared with pathologic findings. CE-MRM suggested the presence of radial scar in 18 of 30 cases and the presence of malignancy in 11 of 30 cases; 1 lesion was classified as borderline. At surgery 22 radial scars (including 4 with associated ductal carcinoma in situ) and 8 carcinomas were detected. CE-MRM provided a specificity of 89%, sensitivity of 83%, and accuracy of 87%. Differently from breast cancer, radial scars are nonenhancing at CE-MRM. Nevertheless, the possibility of nonenhancing carcinomatous foci existing within radial scars implies that surgical excision should be performed in all cases.

Evaluation of tumor angiogenesis with contrast-enhanced dynamic magnetic resonance mammography.

The goal of this research was to correlate dynamic magnetic resonance (MR) mammographic contrast enhancement and microvessel densities in breast masses. Forty-six female patients with breast masses detected by mammography and/or ultrasonography were included in the study. MR contrast enhancements of the lesions were investigated dynamically using axial three-dimensional fast low-angle shot sequences. After excisional biopsy or mastectomy, immunohistochemical staining with factor VIII-RA was performed, followed by microvessel density measurements. Contrast enhancement patterns in dynamic MR mammography were compared with microvessel density measurements using Student's t-test, Pearson's moment correlation coefficients, and one-way analysis of variance (ANOVA). Malignant lesions exhibited three different enhancement patterns: 1) a peak enhancement within 120 seconds (early phase), followed by a decrease in the delayed phase (25 cases); 2) an increase in the early phase, followed by a plateau in the delayed phase (9 cases); and 3) an increase throughout the examination without any peak (5 cases). In benign lesions, signal intensity did not exhibited a peak in five cases, whereas in two cases enhancement was increased in the early phase and made a plateau in the delayed phase. A significant correlation was found between microvessel density and the percentage of maximal signal increase following paramagnetic contrast administration (r=0.322, p<0.05). Dynamic enhancement patterns and rates of maximal signal increase predict microvessel density in breast malignancies and may possibly be used as prognostic indicators.

Contrast-Enhanced Magnetic Resonance Mammography

Rationale and Objectives. We refined and evaluated a spin-echo-based dynamic MR mammography technique for detection and characterization of benign and malignant breast masses. Methods. Analysis was performed on 75 magnetic resonance (MR) mammographies done at 0.5-T on 67 consecutive patients. Histological confirmation of malignancy and MR enhancement data were available on 33 cancers; 29 were infiltrating ductal carcinomas. Precontrast short inversion time (TI) inversion recovery images (TR 2000, TE 30, TI 110) were obtained as well as serial dynamic pre- and postcontrast T1-weighted spin-echo images (TR 600, TE 12) after bolus injection of 0.1 mmol/kg gadolinium chelate. An image subtraction technique was used, and tissue enhancement (expressed as a percentage of baseline signal intensity) was calculated for immediate (0 min) and delayed (8 min) studies. Lesion enhancement was compared to normal parenchyma, fat, muscle, and cysts. Coronal and sagittal reformatted images were also produced. Three cancers were studied during chemotherapy. Results. The mean immediate and delayed tumor enhancement values were 81 ± 22% and 84 ± 23%, respectively. Other tissue values were (immediate, delayed): normal breast, 7% and 19%; fat, 4% and 4%; muscle, 11% and 12%; cysts, 0% and 0%. Fibroadenomas may enhance as quickly and intensely as tumors, but are smooth and usually septated. Image subtraction substantially increased lesion contrast, although motion artifact and misregistration can compromise image quality and quantitation. Conclusion. Breast cancers enhance 10 times or more than normal breast parenchyma; this, together with the image subtraction method, results in high lesion conspicuity. Both quantitative enhancement profiles and morphological criteria are necessary to differentiate benign from malignant lesions. Although the technique, interpretive criteria, and indications are still evolving, MR mammography may play an important role in the future detection and staging of breast cancer.