Improvement in breast lesion characterization with dynamic contrast‐enhanced MRI using pharmacokinetic modeling and bookend T1 measurements

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Abstract
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 T1 measurements were performed before (T1pre) and after (T1post) 2D SPGR imaging. These two “bookend” T1 measurements were used to calibrate the equations which were employed to convert the time course of the 2D SPGR signal strength to T1-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 T1pre 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 T1pre and T1post measurements are necessary for optimum sensitivity and specificity using pharmacokinetic analysis. Magn Reson Med 51:1066–1070, 2004.