Pharmacokinetic mapping for lesion classification in dynamic breast MRI

Purpose:

To prospectively investigate whether a rapid dynamic MRI protocol, in conjunction with pharmacokinetic modeling, could provide diagnostically useful information for discriminating biopsy‐proven benign lesions from malignancies.

Materials and Methods:

Patients referred to breast biopsy based on suspicious screening findings were eligible. After anatomic imaging, patients were scanned using a dynamic protocol with complete bilateral breast coverage. Maps of pharmacokinetic parameters representing transfer constant (K^trans), efflux rate constant (k_ep), blood plasma volume fraction (v_p), and extracellular extravascular volume fraction (v_e) were averaged over lesions and used, with biopsy results, to generate receiver operating characteristic curves for linear classifiers using one, two, or three parameters.

Results:

Biopsy and imaging results were obtained from 93 lesions in 74 of 78 study patients. Classification based on K^trans and k_ep gave the greatest accuracy, with an area under the receiver operating characteristic curve of 0.915, sensitivity of 91%, and specificity of 85%, compared with values of 88% and 68%, respectively, obtained in a recent study of clinical breast MRI in a similar patient population.

Conclusion:

Pharmacokinetic classification of breast lesions is practical on modern MRI hardware and provides significant accuracy for identification of malignancies. Sensitivity of a two‐parameter linear classifier is comparable to that reported in a recent multicenter study of clinical breast MRI, while specificity is significantly higher. J. Magn. Reson. Imaging 2010;31:1371–1378. © 2010 Wiley‐Liss, Inc.