Quantitative T₁ and T₂* carotid atherosclerotic plaque imaging using a three-dimensional multi-echo phase-sensitive...

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.