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Background  Improved motion-sensitized driven-equilibrium (iMSDE) preparations have been successfully used in carotid artery wall imaging to achieve blood suppression, but it causes notable signal loss, mostly due to inherent T 2  decay, eddy current effects and B 1  +  inhomogeneity. In this study, we investigate the signal to noise ratio (SNR) and blood suppression performance of iMSDE using composite RF pulses and sinusoidal gradients. Optimized first moment (m 1 ) values for iMSDE prepared T 1 - and T 2 - weighted (T 1 - and T 2 -w) imaging are presented.    Methods  Twelve healthy volunteers and six patients with carotid artery disease underwent iMSDE and double inversion recovery (DIR) prepared T 1 - and T 2 -w fast spin echo (FSE) MRI of the carotid arteries. Modified iMSDE module using composite RF pulses and sinusoidal gradients were evaluated with a range of m 1 . SNR of adjacent muscle, vessel wall and the lumen were reported. The optimized iMSDE module was also tested in a 3D variable flip angle FSE (CUBE) acquisition.    Results  The SNR of muscle was highest using sinusoidal gradients, and the relative improvement over the trapezoidal gradient increased with higher m 1  (p<0.001). Optimal SNR was observed using an iMSDE preparation scheme containing two 180° composite pulses and standard 90° and -90° pulses (p=0.151). iMSDE produced better blood suppression relative to DIR preparations even with a small m 1  of 487 mT*ms 2 /m (p<0.001). In T 1 -w iMSDE, there was a SNR decrease and an increased T 2  weighting with increasing m 1.  In T 2 -w iMSDE, by matching the effective echo time (TE), the SNR was equivalent when m 1  was <= 1518 mT*ms 2 /m, however, higher m 1  values (2278 – 3108 mT*ms 2 /m) reduced the SNR. In the patient study, iMSDE improved blood suppression but reduced vessel wall CNR efficiency in both T 1 -w and T 2 -w imaging. iMSDE also effectively suppressed residual flow artifacts in the CUBE acquisition.    Conclusions  iMSDE preparation achieved better blood suppression than DIR preparation with reduced vessel wall CNR efficiency in T 1- w and T 2 -w images. The optimized m 1 s are 487 mT*ms 2 /m for T 1 -w imaging and 1518 mT*ms 2 /m for T 2 -w imaging. Composite 180° refocusing pulses and sinusoidal gradients improve SNR performance. iMSDE further improves the inherent blood suppression of CUBE.

Optimization of Improved Motion-sensitized Driven-equilibrium (iMSDE) blood suppression for carotid artery wall imaging