Optimized and combined T1 and B1 mapping technique for fast and accurate T1 quantification in contrast-enhanced abdominal MRI

Abstract

Fast T1 mapping techniques are a valuable means of quantitatively assessing the distribution and dynamics of intravenously or orally applied paramagnetic contrast agents (CAs) by noninvasive imaging. In this study a fast T1 mapping technique based on the variable flip angle (VFA) approach was optimized for accurate T1 quantification in abdominal contrast-enhanced (CE) MRI. Optimization methods were developed to maximize the signal-to-noise ratio (SNR) and ensure effective RF and gradient spoiling, as well as a steady state, for a defined T1 range of 100-800 ms and a limited acquisition time. We corrected B1 field inhomogeneities by performing an additional measurement using an optimized fast B1 mapping technique. High-precision in vitro and abdominal in vivo T 1 maps were successfully generated at a voxel size of 2.8 x 2.8 x 15 mm3 and a temporal resolution of 2.3 s per T1 map on 1.5T and 3T MRI systems. The application of the proposed fast T1 mapping technique in abdominal CE-MRI enables noninvasive quantification of abdominal tissue perfusion and vascular permeability, and offers the possibility of quantitatively assessing dilution, distribution, and mixing processes of labeled solutions or drugs in the gastrointestinal tract. © 2007 Wiley-Liss, Inc.