Quantitative T1 and T2* carotid atherosclerotic plaque imaging using a three-dimensional multi-echo phase-sensitive inversion recovery sequence: a feasibility study.

Magnetic resonance imaging (MRI) is widely used to detect carotid atherosclerotic plaques. Although it is important to evaluate vulnerable carotid plaques containing lipids and intra-plaque hemorrhages (IPHs) using T1-weighted images, the image contrast changes depending on the imaging settings. Moreover, to distinguish between a thrombus and a hemorrhage, it is useful to evaluate the iron content of the plaque using both T1-weighted and T2*-weighted images. Therefore, a quantitative evaluation of carotid atherosclerotic plaques using T1 and T2* values may be necessary for the accurate evaluation of plaque components. The purpose of this study was to determine whether the multi-echo phase-sensitive inversion recovery (mPSIR) sequence can improve T1 contrast while simultaneously providing accurate T1 and T2* values of an IPH. T1 and T2* values measured using mPSIR were compared to values from conventional methods in phantom and in vivo studies. In the phantom study, the T1 and T2* values estimated using mPSIR were linearly correlated with those of conventional methods. In the in vivo study, mPSIR demonstrated higher T1 contrast between the IPH phantom and sternocleidomastoid muscle than the conventional method. Moreover, the T1 and T2* values of the blood vessel wall and sternocleidomastoid muscle estimated using mPSIR were correlated with values measured by conventional methods and with values reported previously. The mPSIR sequence improved T1 contrast while simultaneously providing accurate T1 and T2* values of the neck region. Although further study is required to evaluate the clinical utility, mPSIR may improve carotid atherosclerotic plaque detection and provide detailed information about plaque components.