Optimized three-dimensional sodium imaging of the human heart on a clinical 3T scanner

Abstract

Purpose: Optimization of sequence and sequence parameters to allow three-dimensional (3D) sodium imaging of the entire human heart in vivo in a clinically reasonable time. Theory and Methods: A stack of spirals pulse sequence was optimized for cardiac imaging by considering factors such as spoiling, nutation angles, repetition time, echo time, T1/T2 relaxation, off-resonance, data acquisition window, motion, and segmented k-space acquisition. Simulations based on Bloch equations as well as the exact trajectory used for data acquisition provided the basis for choice of parameter combinations for sodium imaging. Sodium phantom scanning was used to validate the choice of parameters and for corroboration with simulations. In vivo cardiac imaging in six volunteers was also performed with an optimized sequence. Results: Phantom studies showed good correlation with simulation results. Images obtained from human volunteers showed that the heart can be imaged with a nominal resolution of 5 x 5 x 10 mm3 and with a signal-to-noise ratio >15 (in the septum) in about 6-10 minutes. Long axis views of the reformatted human heart show true 3D imaging capability. Conclusion: Optimization of the sequence and its parameters allowed in vivo 3D sodium imaging of the entire human heart in a clinically reasonable time.