Nonmass Enhancement Breast Lesions: Diagnostic Performance of Kinetic Assessment on Ultrafast and Standard Dynamic Contrast-Enhanced MRI in Comparison With Morphologic Evaluation.

Abstract

<b>OBJECTIVE.</b> The purpose of this article was to evaluate the diagnostic performance of the kinetic parameters of ultrafast and standard dynamic contrast-enhanced MRI (DCE-MRI) compared with morphologic evaluation in differentiating benign from malignant nonmass enhancement (NME) breast lesions. <b>MATERIALS AND METHODS.</b> A total of 77 consecutive patients with 77 NMEs (23 benign and 54 malignant) underwent 3-T MRI, including one unenhanced and eight contrast-enhanced ultrafast DCE-MRI scans (7-second scans) and standard DCE-MRI scans. The two readers evaluated the lesions' likelihood of malignancy on a continuous scale from 0 to 100% as the morphologic score using standard DCE-MRI. The kinetic curves of ultrafast DCE-MRI were fitted using an empirical mathematical model, Δ<i>S</i>(<i>t</i>) = <i>A</i> × (1 - <i>e</i>^-α<i>^t</i>), where <i>A</i> is the upper limit of signal intensity, <i>e</i> is the Euler number, and alpha (s^-1) is the rate of signal increase. The initial slope of the kinetic curve (<i>A</i> × α) and the initial AUC (AUC₃₀, which is the integration of the kinetic curve from 0 to 30 seconds) were calculated. From standard DCE-MRI, initial enhancement rate and signal enhancement ratio (SER) were calculated. These parameters were compared between benign and malignant NMEs. <b>RESULTS.</b> The morphologic score of malignant NME was statistically significantly higher than that of benign NME (<i>p</i> < 0.0001). The upper limit of signal intensity, rate of signal increase, initial slope of the kinetic curve, and AUC₃₀ of ultrafast DCE-MRI, initial enhancement rate, SER of standard DCE-MRI of malignant NMEs were statistically significantly higher than those of benign NMEs (<i>p</i> = 0.0011, 0.0045, < 0.0001, < 0.0001, 0.0017, and < 0.0001, respectively). AUC ROC analysis found no statistically significant difference between morphologic score, AUC₃₀ of ultrafast DCE-MRI, or SER of standard DCE-MRI. <b>CONCLUSION.</b> The kinetic parameters of ultrafast and standard DCE-MRI were as effective as morphologic evaluation for differentiation between benign and malignant NMEs.