Simultaneous quantitative mapping of conductivity and susceptibility using a double-echo ultrashort echo time sequence: Example using a hematoma evolution study.

Abstract

The primary purpose of this study is to propose a method for the simultaneous quantitative three-dimensional (3D) mapping of conductivity and susceptibility using double-echo ultrashort echo time (UTE) imaging. The secondary purpose is to investigate the changes of these properties over time during in vitro hematoma evolution in blood samples. The first and second set of echo data for a UTE sequence were used to perform quantitative conductivity mapping (QCM) and quantitative susceptibility mapping (QSM), respectively. A simulation study was conducted to determine the echo time (TE) range that was acceptable for QCM. Subsequently, a NaCl phantom experiment and in vivo 3D QCM and QSM demonstrations were performed. The changes in electromagnetic (EM) properties over time were studied using in vitro blood coagulation experiments with venous blood from healthy volunteers. Quantitative and qualitative analyses showed small differences in the QCM for TE values up to 300 μs. The estimated conductivity and susceptibility values monotonically increased during the first few hours of the hematoma evolution experiments. However, although the susceptibility values continued to increase, the conductivity values were steady after 24 h. The proposed method can be useful for determining EM property changes (including those during hemorrhage) and providing additional information about the state of the blood. Magn Reson Med 76:214-221, 2016. © 2015 Wiley Periodicals, Inc.