Optimizing pulsed‐chemical exchange saturation transfer imaging sequences
Citations Over TimeTop 10% of 2011 papers
Abstract
Chemical exchange saturation transfer (CEST) provides a new imaging contrast mechanism sensitive to labile proton exchange. Pulsed-CEST imaging is better suited to the hardware constraints on clinical imaging systems when compared with traditional continuous wave-CEST imaging methods. However, designing optimum pulsed-CEST imaging sequences entails complicated and time-consuming numerical integrations. In this work, a simplified and computationally efficient technique is provided to optimize the pulsed-CEST imaging sequence. An analysis was performed of the optimal average irradiation power and the optimal irradiation flip angle as a function of the acquisition parameters and sample properties in both a two-pool model and a three-pool model of endogenous amine exchange. Key simulated and experimental results based on a creatine/agar tissue phantom show that (1) the average irradiation power is a more meaningful sequence metric than is the average irradiation field amplitude, (2) the optimal average powers for continuous wave and pulsed-CEST imaging are approximately equal to each other for a relevant range of solute frequency offsets, exchange rates, and concentrations, (3) an irradiation flip angle of 180° is optimal or near optimal, independent of the other acquisition parameters and the sample properties, and (4) higher duty cycles yield higher CEST contrast.
Related Papers
- → Reduced RF power without blurring: Correcting for modulation of refocusing flip angle in FSE sequences(2004)65 cited
- → Transverse relaxation and flip angle mapping: Evaluation of simultaneous and independent methods using multiple spin echoes(2016)53 cited
- → Improvement in B1+ Homogeneity and Average Flip Angle Using Dual-Source Parallel RF Excitation for Cardiac MRI in Swine Hearts(2015)16 cited
- → Optimal flip angle for evaluation of swallowing using ultra-high-speed MRI(2008)
- → Assessing the Impact of Flip Angle and on Image Quality and reliability of Ernst Angle optimization across Varied Conditions in Magnetic Resonance Imaging(2023)