Contrast-enhanced magnetic resonance imaging of the breast: the value of pharmacokinetic parameters derived from fast dynamic imaging during initial enhancement in classifying lesions

Abstract

The value of pharmacokinetic parameters derived from fast dynamic imaging during initial enhancement in characterizing breast lesions on magnetic resonance imaging (MRI) was evaluated. Sixty-eight malignant and 34 benign lesions were included. In the scanning protocol, high temporal resolution imaging was combined with high spatial resolution imaging. The high temporal resolution images were recorded every 4.1 s during initial enhancement (fast dynamic analysis). The high spatial resolution images were recorded at a temporal resolution of 86 s (slow dynamic analysis). In the fast dynamic evaluation pharmacokinetic parameters (K(trans), V(e) and k(ep)) were evaluated. In the slow dynamic analysis, each lesion was scored according to the BI-RADS classification. Two readers evaluated all data prospectively. ROC and multivariate analysis were performed. The slow dynamic analysis resulted in an AUC of 0.85 and 0.83, respectively. The fast dynamic analysis resulted in an AUC of 0.83 in both readers. The combination of both the slow and fast dynamic analyses resulted in a significant improvement of diagnostic performance with an AUC of 0.93 and 0.90 (P = 0.02). The increased diagnostic performance found when combining both methods demonstrates the additional value of our method in further improving the diagnostic performance of breast MRI.

Figures

Fig. 1

Relative enhancement versus time curves of a benign (a) and malignant (b) lesion. Note that the slope of enhancement and the level of enhancement is higher for the malignant lesion compared with the benign lesion. These fast dynamic acquisitions were analyzed as described in the Materials and methods section and resulted in the color overlays as presented in Figs. 4 and 5. The data used in this figure were respectively derived from a histopathology proven fibroadenoma and an invasive ductal carcinoma. The same lesions as presented in Figs. 4 and 5

Fig. 2

Scatter plots from the extracellular volume (V) versus the transfer constant (Ktrans) for reader 1 (a) and reader 2 (b). Benign and malignant cases were clustered. Clusters were summarized with an iso-probability contour computed from the cluster mean and covariance at a squared normalized radius of 2. The continuous-line ellipsoid represents the benign subgroup, the dotted-line ellipsoid represents the malignant subgroup

Fig. 3

ROC curve for reader 1 (a) and reader 2 (b) displaying the fast dynamic, slow dynamic and combined analysis. No significant differences were found between the fast and slow dynamic analysis in both readers. A significant difference was found between the slow dynamic analysis and the combined analysis for both readers (P = 0.02 for both readers). The comparison between the fast dynamic analysis and the combined analysis also resulted in a significant difference for both readers (P = 0.01 and P = 0.02). No significant differences were found between the two readers

Fig. 4

a Transverse reconstruction of the high-resolution subtraction sequence of the right breast. b Time versus relative enhancement curve of the slow dynamic series. Ktrans (c) and V (d) color overlay images of the right breast, including a scalar bar, to demonstrate the parameter values. The subtraction image shows a rounded, mostly sharp delineated lesion. The time versus signal intensity curve demonstrates a type 1 curve, indicative for a benign lesions. The readers classified this lesion as benign (BI-RADS 2) or probably benign needing follow up (BI-RADS 3) based on the slow dynamic analysis. The Ktrans and V parameter color overlays demonstrate relatively low values for both parameters (see Table 2 for comparison) indicative for a benign lesion. Histopathology proved this lesion to be a fibroadenoma

Fig. 5

a Transverse reconstruction of the high-resolution subtraction sequence of the right breast. b Time versus relative enhancement curve of the slow dynamic series. Ktrans (c) and V (d) color overlay images of the right breast, including a scalar bar, demonstrates the parameter values. The subtraction image shows a spiculated lesion retromammillar. The time versus signal intensity curve demonstrates a type 3 curve (wash-out) suggestive for a malignancy. Both readers classified this lesion as malignant (BI-RADS 4) based on the slow dynamic analysis. The Ktrans and V parameter color overlays demonstrate high values for both parameters (see Table 2 for comparison), indicative for a malignant lesion. Histopathology proved this lesion to be an invasive ductal carcinoma