Image Characteristics of T 1 Weighted Magnetic Resonance Imaging Techniques for Plaque Tissue Characterization (Comparison with Conventional Spin Echo Method)

In the tissue characterization of plaques using magnetic resonance imaging (MRI), T1-weighted imaging is important. However, T1-weighted imaging are obtained by various imaging methods, and show different contrasts depending on parameters such as repetition time, echo time, and inversion time. To evaluate the tissue characterization of plaques using MRI, the characteristics are estimated and evaluated using the strength of the plaque-to-muscle signal intensity ratio (PMR), which is the value obtained by dividing the signal intensity of the plaque by that of the sternocleidomastoid muscle or myocardium. In the present research, we aim to obtain the PMR by phantom experiment and grasp the image characteristics for T1 and T2 values of different T1-weighted imaging methods. In addition, since the PMR of the conventional spin echo (SE) method of T1-weighted imaging (two-dimensional (2D) T1WI SE) is reported to have high discrimination ability in plaque tissue characterization, the experimental results were compared with those of 2D T1WI SE. Among the protocols examined, 3D sampling perfection with application optimized contrasts using different flip angle evolutions, T1-variable, motion-sensitized driven equilibrium (1-axis 300 ms(2*)mT/m) + had the same tissue characterization ability as 2D T1 WI SE, and was the most suitable imaging method. Moreover, in the gradient echo method, the effect of T2 values was smaller than that of 2D T1 WI SE, and it was suggested that the PMR of the plaque may be lowered when there is a change in the tissue properties that the T2 value and T1 value are prolonged due to liquefaction. The results of this phantom experiment are expected help in selecting the imaging method aimed at optimization and the image characteristics of different T1-weighted imaging method can be grasped.