Myocardial tagging with SSFP provided better tag- and blood-myocardium contrast-to-noise ratios than standard FGRE tagging at equal or twice the receiver bandwidth.
Does myocardial tagging with SSFP improve myocardium-tag CNR and tag persistence compared to FGRE tagging?
Myocardial tagging with SSFP improves myocardium-tag contrast-to-noise ratio and tag persistence compared to standard FGRE tagging, allowing for decreased breath-hold duration or increased temporal resolution.
This work presents the first implementation of myocardial tagging with refocused steady-state free precession (SSFP) and magnetization preparation. The combination of myocardial tagging (a noninvasive method for quantitative measurement of regional and global cardiac function) with the high tissue signal-to-noise ratio (SNR) obtained with SSFP is shown to yield improvements in terms of the myocardium-tag contrast-to-noise ratio (CNR) and tag persistence when compared to the current standard fast gradient-echo (FGRE) tagging protocol. Myocardium-tag CNR and tag persistence were studied using numerical simulations as well as phantom and human experiments. Both quantities were found to decrease with increasing imaging flip angle (alpha) due to an increased tag decay rate and a decrease in myocardial steady-state signal. However, higher alpha yielded better blood-myocardium contrast, indicating that optimal alpha is dependent on the application: higher alpha for better blood-myocardium boundary visualization, and lower alpha for better tag persistence. SSFP tagging provided the same myocardium-tag CNR as FGRE tagging when acquired at four times the bandwidth and better tag- and blood-myocardium CNRs than FGRE tagging when acquired at equal or twice the receiver bandwidth (RBW). The increased acquisition efficiency of SSFP allowed decreases in breath-hold duration, or increases in temporal resolution, as compared to FGRE.
Herzka et al. (2003) studied this question. Myocardial tagging with steady-state free precession (SSFP) vs. Fast gradient-echo (FGRE) tagging protocol was evaluated on Myocardium-tag contrast-to-noise ratio (CNR) and tag persistence. Myocardial tagging with SSFP provided better tag- and blood-myocardium contrast-to-noise ratios than standard FGRE tagging at equal or twice the receiver bandwidth.