Initial maximum slope of the contrast enhancement versus time curve for dynamic evaluation of breast lesions on ultrafast breast MRIs

Purpose: Modern viewsharing sequences allow dynamic whole breast MRI at diagnostic spatial resolution within 5 seconds, showing the inflow of contrast in breast abnormalities. We evaluate the maximum slope of initial contrast enhancement as a heuristic parameter for differentiating benign from malignant disease and compare its value to classic 3 timepoint analysis. Methods and Materials: We employed a bi-temporal breast MRI protocol on a 3 T MRI using a 16 channel bilateral breast coil. High-resolution VIBE acquisitions (0.80.81.0 mm, temporal resolution 94s) were interleaved with a series of ultrafast TWIST acquisitions (112.5 mm, temporal resolution 4.2s) during the inflow of the contrast agent. Forty-two consecutive patients with 43 enhancing abnormalities (21 benign and 22 malignant) presenting between November 2010 and July 2011 were included. We measured the maximum slope of the relative enhancement versus time curve on the TWIST acquisitions and recorded curve type of the lesions on the VIBE acquisitions. ROC analysis was performed to compare diagnostic performance. Results: The maximum slope of the relative enhancement versus time curve was significantly better in discriminating between benign and malignant disease than the curve type (Az 0.865 vs. Az 0.723, p = 0.036). Cutoff values of 15%/sec and 3.15%/sec can be used to differentiate high-risk lesions (>85% malignancies) from intermediate and low-risk lesions (<10% malignancies). This simplification yields an Az of 0.808. Conclusion: The initial maximum slope provides more diagnostic information than the curve types and can therefore be used to assess lesion dynamics. This can substantially shorten current scan protocols.