Purpose To compare the pathology and kinetic characteristics of breast lesions with focus, mass and nonmass-like enhancement. Materials and Methods 852 MRI detected breast lesions in 697 patients were selected for an IRB approved review. Patients underwent dynamic contrast enhanced MRI using one pre and three to six post-contrast T1 weighted images. The ‘type’ of enhancement was classified as mass, non-mass or focus, and kinetic curves quantified by the initial enhancement percentage (E1), time to peak enhancement (Tpeak) and signal enhancement ratio (SER). These kinetic parameters were compared between malignant and benign lesions within each morphologic type. Results 552 lesions were classified as mass (396 malignant, 156 benign), 261 as nonmass (212 malignant,49 benign) and 39 as focus (9 malignant,30 benign). The most common pathology of malignant/benign lesions by morphology: for mass, invasive ductal carcinoma/fibroadenoma; for nonmass, ductal carcinoma in situ (DCIS)/fibrocystic change(FCC); for focus, DCIS/FCC. Benign mass lesions exhibited significantly lower E1, longer Tpeak and lower SER compared with malignant mass lesions (p < 0.0001). Benign nonmass lesions exhibited only a lower SER compared to malignant nonmass lesions (p<0.01). Conclusions By considering the diverse pathology and kinetic characteristics of different lesion morphologies, diagnostic accuracy may be improved.

OBJECTIVE The purpose of this study was to compare MRI kinetic curve data acquired with three systems in the evaluation of malignant lesions of the breast. MATERIALS AND METHODS The cases of 601 patients with 682 breast lesions (185 benign, 497 malignant) were selected for review. The malignant lesions were classified as ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), and other. The dynamic MRI protocol consisted of one unenhanced and three to seven contrast-enhanced images acquired with one of three imaging protocols and systems. An experienced radiologist analyzed the shapes of the kinetic curves according to the BI-RADS lexicon. Several quantitative kinetic parameters were calculated, and the kinetic parameters of malignant lesions were compared across the three systems. RESULTS Imaging protocol and system 1 were used to image 304 malignant lesions (185 IDC, 62 DCIS); imaging protocol and system 2, 107 lesions (72 IDC, 21 DCIS); and imaging protocol and system 3, 86 lesions (64 IDC, 17 DCIS). Compared with those visualized with imaging protocols and systems 1 and 2, IDC lesions visualized with imaging protocol and system 3 had significantly less initial enhancement, longer time to peak enhancement, and a slower washout rate (p < 0.004). Only 47% of IDC lesions imaged with imaging protocol and system 3 exhibited washout type curves, compared with 75% and 74% of those imaged with imaging protocols and systems 2 and 1, respectively. The diagnostic accuracy of kinetic analysis was lowest for imaging protocol and system 3, but the difference was not statistically significant. CONCLUSION The kinetic curve data on malignant lesions acquired with one system showed significantly lower initial contrast uptake and a different curve shape in comparison with data acquired with the other two systems. Differences in k-space sampling, T1 weighting, and magnetization transfer effects may be explanations for the difference.

#4025 Background: Dynamic contrast enhanced magnetic resonance imaging (DCEMRI) has demonstrated superior sensitivity for detecting earlier cancers compared with x-ray mammography, and is being used increasingly for high-risk screening, diagnostic imaging and to evaluate extent of malignant disease. When assessing lesion malignancy both the morphology and contrast uptake and washout—or kinetics—of the lesion are important. At our institution DCEMRI breast examinations have been performed on three different MR systems. The purpose of this study was to compare the MR kinetic curve data of malignant lesions acquired by these systems.&#x2028; Methods: 445 patients with 485 malignant lesions were selected for an IRB approved review. The lesions were classified as ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC) and 'other'. Dynamic MR protocol: 1 pre and 3-7 post-contrast images, acquired on a system using a non fat-suppressed dynamic sequence (NFS) and 2 newer systems by different manufacturers using fat suppressed dynamic sequences (FS1 and FS2). Kinetic curve data was processed and displayed on a CADstream workstation. Analysis of kinetic curve shape was made by an experienced radiologist according to the BI-RADS lexicon. Several quantitative kinetic parameters were calculated, both directly from the curve data and after fitting to an empirical mathematical model (EMM). The kinetic parameters of malignant lesions were compared between the three systems.&#x2028; Results: 299 malignant lesions (185 IDC, 57 DCIS) were imaged on NFS, 104 lesions (69 IDC, 21 DCIS) on FS1, and 82 on FS2 (61 IDC, 17 DCIS). Compared to both systems NFS and FS1, IDC lesions acquired on FS2 demonstrated significantly lower initial enhancement, longer time to peak enhancement and slower washout rate (p &lt; 0.0004). 80% of IDC lesions acquired on FS1 were classified as 'washout', compared with only 46% of IDC lesions on FS2. On both FS1 and FS2, we did not find a difference in the kinetic parameters of IDC vs. DCIS lesions. However, IDC lesions imaged on NFS exhibited significantly higher contrast uptake, shorter time to peak and stronger washout compared to DCIS lesions (p &lt; 0.0001).&#x2028; Discussion: The kinetic curve data of malignant lesions acquired by one system exhibited significantly lower initial contrast uptake and different curve shape compared with the other two. In addition, on both newer systems, the kinetic parameters of DCIS were comparable with IDC, which is contrary to what was found on the older system. Differences in k-space sampling, T1 weighting or magnetization transfer effects may be possible explanations. The results of this study underscore the importance of developing standardized acquisition and analysis methods, to ensure that across all available systems (i) malignant lesions are sufficiently conspicuous and thus reliably detected and (ii) interpretation of kinetic data is consistent. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4025.