Abstract
PURPOSE: This study is to compare the accuracy of four different black-blood T(2) mapping sequences in carotid vessel wall. METHODS: Four different black-blood T(2) mapping sequences were developed and tested through phantom experiments and 17 healthy volunteers. The four sequences were: 1) double inversion-recovery (DIR) prepared 2D multi-echo spin-echo (MESE); 2) DIR-prepared 2D multi-echo fast spin-echo (MEFSE); 3) improved motion-sensitized driven-equilibrium (iMSDE) prepared 3D FSE and 4) iMSDE prepared 3D fast spoiled gradient echo (FSPGR). The concordance correlation coefficient and Bland-Altman statistics were used to compare the sequences with a gold-standard 2D MESE, without blood suppression in phantom studies. The volunteers were scanned twice to test the repeatability. Mean and standard deviation of vessel wall T(2), signal-to-noise (SNR), the coefficient of variance and interclass coefficient (ICC) of the two scans were compared. RESULTS: The phantom study demonstrated that T(2) measurements had high concordance with respect to the gold-standard (all r values >0.9). In the volunteer study, the DIR 2D MEFSE had significantly higher T(2) values than the other three sequences (P < 0.01). There was no difference in T(2) measurements obtained using the other three sequences (P > 0.05). iMSDE 3D FSE had the highest SNR (P < 0.05) compared with the other three sequences. The 2D DIR MESE has the highest repeatability (ICC: 0.96, [95% CI: 0.88-0.99]). CONCLUSION: Although accurate T(2) measurements can be achieved in phantom by the four sequences, in vivo vessel wall T(2) quantification shows significant differences. The in vivo images can be influenced by multiple factors including black-blood preparation and acquisition method. Therefore, a careful choice of acquisition methods and analysis of the confounding factors are required for accurate in vivo carotid vessel wall T(2) measurements. From the settings in this study, the iMSDE prepared 3D FSE is preferred for the future volunteer/patient scans.