Direct imaging and quantification of carotid plaque calcification

Abstract Carotid plaque calcification normally appears as a signal void with clinical MR sequences. Here, we describe the use of an adiabatic inversion recovery prepared two‐dimensional ultrashort echo time sequence to image and characterize carotid plaque calcification using a clinical 3‐T scanner. T 1 , T , and free water content were measured for seven carotid samples, and the results were compared with micro‐CT imaging. Conventional gradient echo and fast spin echo images were also acquired for comparison. Correlations between T 1 , T , free water concentration, and mineral density were performed. There was a close correspondence between inversion recovery prepared two‐dimensional ultrashort echo time morphologic and micro‐CT appearances. Carotid plaque calcification varied significantly from sample to sample, with T 1 s ranging from 94 ± 19 to 328 ± 21 msec, T s ranging from 0.31 ± 0.12 to 2.15 ± 0.25 msec, and free water concentration ranging from 5.7 ± 2.3% to 16.8 ± 3.4%. There was a significant positive correlation between T 1 ( R = 0.709; P < 0.074), T ( R = 0.816; P < 0.025), and free water concentration, a negative correlation between T 1 ( R = 0.773; P < 0.042), T ( R = 0.948; P < 0.001) and CT measured mineral density, and a negative correlation between free water concentration ( R = 0.936; P < 0.002) and mineral density. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.