Improved accuracy and consistency in T1 measurement of flowing blood by using inversion recovery GE-EPI

Problems associated with techniques currently used to measure the T, of flowing blood are evaluated and a method to improve the consistency and repeatability of measurements is presented. Similar to some currently used techniques, the pulse sequence employs a nonselective adiabatic inversion pulse followed by a series of ECG-gated gradient echo EPI (echo planar imaging) images to obtain images where the blood (fluid) signal exhibits a T-1-dependent inversion recovery signal from which the spin lattice relaxation constant (T-1) of the flowing fluid can be measured. The new method combines curve fitting with a measure of the curve null point to acquire more accurate and consistent T-1 values. Simulation and experimental results show that this combined fitting-nulling method is more stable and consistent in measuring the T, of flowing fluid. The feasibility of temperature measurement of a flowing fluid based on the temperature dependence of the T-1 of water protons is shown in this paper. ECG gating is used to reduce the effects of cyclic intensity changes for measurement of T-1 in pulsatile flowing blood. (c) 2005 American Association of Physicists in Medicine.