Is Late Phase Information Necessary for Dynamic Evaluation of Breast Cancer?

Purpose: Novel breast MRI protocols evaluate early contrast uptake of lesions, using a short acquisition time and high tempor al resolution (tRes). However, these acquisitions do not provide information about late phase enhancement (curve- type). In this study we investigated whether adding late phase information to early contrast uptake dynamics improves the differentiation between benign and malignant lesions as measured with a computer aided diagnosis (CADx) system. Methods and Materials: 106 malignant and 44 benign lesions were evaluated, which were imaged with a 4.3 seconds tRes sequence for the initial 100 seconds and a high spatial resolution sequence for the subsequent 510 seconds. The locations of the lesions were marked manually. The CAD system automatically segmented the lesions and extracted six features that describe the early contrast uptake. These features were used in a random forest classifier for malignant/benign classification. In the second step, washout rate (WR) of the lesions obtained from the late phase acquisitions were added to these features and classification was repeated. The classification accuracies of both methods were compared using ROC analysis. Results: The area under the curve (AUC) was 0.816 with high tRes early contrast uptake dynamics features alone. Adding the WR feature slightly increased the AUC value to 0.824, where the difference was not statistically significant. Conclusion: Addition of late phase information on top of high tRes early uptake dynamics did not increase the diagnostic performance significantly. This result supports the feasibility of shorter MRI protocols for classification of breast lesions.