Ultrafast Dynamic Contrast-Enhanced Breast MRI: Kinetic Curve Assessment Using Empirical Mathematical Model Validated with Histological Microvessel Density

Rationale and Objectives: To evaluate whether parameters from empirical mathematical model (EMM) for ultrafast dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) correlate with histo-logical microvessel density (MVD) in invasive breast cancer. Materials and Methods: Ninety-eight consecutive patients with invasive breast cancer underwent an institu-tional review board-approved ultrafast DCE-MRI including a pre- and 18 postcontrast whole breast ultrafast scans (3 seconds) followed by four standard scans (60 seconds) using a 3T system. Region of interest was placed within each lesion where the highest signal increase was observed on ultrafast DCE-MRI, and the increase rate of enhancement was calculated as follows: D S = (SIpost-SIpre)/SIpre. The kinetic curve obtained from ultrafast DCE-MRI was analyzed using a truncated EMM: D S (t )= A (1-e-at ), where A is the upper limit of the signal intensity, a (min-1 ) is the rate of signal increase. The initial slope of the kinetic curve is given by Aa . Initial area under curve (AUC30) and time of initial enhancement was calculated. From the stan-dard DCE-MRI, the initial enhancement rate (IER) and the signal enhancement ratio (SER) were calculated as follows: IER = (SIearly-SIpre)/SIpre, SER = (SIearly-SIpre)/(SIdelayed-SIpre). The parameters were com-pared to MVD obtained from surgical specimens. Results: A, a, Aa, AUC30, and time of initial enhancement significantly correlated with MVD (r = 0.29, 0.40, 0.51, 0.43, and-0.32 with p = 0.0027, p < 0.0001, p < 0.0001, p < 0.0001, and p = 0.0012, respectively), whereas IER and SER from standard DCE-MRI did not. Conclusion: The parameters of the EMM, especially the initial slope or Aa , for ultrafast DCE-MRI corre-lated with MVD in invasive breast cancer. (c) 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.