Dynamic Contrast-Enhanced Magnetic Resonance Imaging of the Breast Combined with Pharmacokinetic Analysis of Gadolinium-DTPA Uptake in the Diagnosis of Local Recurrence of Early Stage Breast Carcinoma

Abstract

This study was designed to assess the efficacy of dynamic contrast-enhanced magnetic resonance imaging (MRI) of the breast combined with pharmacokinetic analysis of gadolinium (Gd)-DTPA uptake in the diagnosis of local recurrence of early stage breast carcinoma. Fifty women treated with breast-conserving surgery and radiotherapy underwent breast MRI. Dynamic magnetic resonance data obtained at four preselected slice locations were analyzed to examine Gd-DTPA uptake based on a pharmacokinetic model using three parameters: wash-in rate, wash-out rate, and amplitude of uptake. Synthetic images were produced from the above parameters and their derivatives--maximum uptake and reciprocal of half the time to maximum. For each region of interest (ROI), median parameter values were calculated. The mean pixel signal intensity of each ROI was plotted against time, and an enhancement index was determined. Sixty ROIs were selected: 49 lesions were benign, and 11, malignant. Significant differences between benign and malignant lesions were found for the enhancement index (P < 0.0001), maximum uptake (P < 0.0001), amplitude of uptake (P < 0.0001), wash-in rate (P = 0.03), wash-out rate (P = 0.01), and the reciprocal of half the time to maximum (P = 0.0005). The respective sensitivities and specificities were as follows: for the enhancement index, 1.00 and 0.96; for maximum uptake, 1.00 and 0.96; for amplitude of uptake, 0.91 and 0.94; for wash-in rate 0.82 and 0.47; for wash-out rate 0.91 and 0.59; and for the reciprocal of half the time to maximum, 1.00 and 0.51. Dynamic scanning proved essential for the detection and differential diagnosis of local tumor recurrence. Pharmacokinetic analysis of Gd-DTPA uptake can be used to produce parametric images that retain the spatial resolution of the original images while providing additional information about lesion permeability and vascularity, and helping to avoid the observer variability associated with ROI analysis.