Improvement in breast lesion characterization with dynamic contrast‐enhanced MRI using pharmacokinetic modeling and bookend T 1 measurements

Dynamic contrast‐enhanced breast MR imaging was performed on 14 patients (five cancerous lesions, nine benign) with slice‐selective spoiled gradient‐recalled echo (2D SPGR) imaging. Adiabatic saturation recovery T 1 measurements were performed before ( T 1pre ) and after ( T 1post ) 2D SPGR imaging. These two “bookend” T 1 measurements were used to calibrate the equations which were employed to convert the time course of the 2D SPGR signal strength to T 1 ‐vs.‐time, which in turn was used to compute the gadolinium concentration‐vs.‐time ([C](t)) in the lesion. The extraction‐flow product (EF) was computed for each lesion by pharmacokinetic modeling of [C](t). For this study, EF provided a sensitivity and specificity for cancer of 100% and 78%, respectively. When only T 1pre was used to estimate [C](t) (which assumes a priori knowledge of the shape and amplitude of the slice profile), the sensitivity and specificity fell to 80% and 56%, respectively. This is presumably due to unexpected variations in the shape and/or amplitude of the slice profile, which could be caused by factors such as patient‐to‐patient variations in breast geometry or inconsistently set transmit gains. Therefore, both T 1pre and T 1post measurements are necessary for optimum sensitivity and specificity using pharmacokinetic analysis. Magn Reson Med 51:1066–1070, 2004. © 2004 Wiley‐Liss, Inc.