Parallel RF transmission in body MRI for reduced dielectric shading, improved B1 homogeneity and accelerated imaging at 3.0T: Initial clinical experience in 40 patients using MultiTransmit

Introduction Electromagnetic wave propagation in tissue is known to cause dielectric resonance effects if the wavelength reaches the object dimension. At 3.0T, dielectric resonance effects are visible in body MR imaging predominantly in heavier patients and in patients with intraabdominal fluid collections (i.e. ascites). The use of multiple transmit channels can provide better control of the radio frequency (RF) field by allowing to send independent RF pulses and therefore yielding more uniform excitation and receive fields. Improved homogeneity and consistency of the images obtained by multisource transmit RF technology has been previously shown in phantom studies and healthy volunteers, but has not been evaluated in patients. Our study was carried out to test the clinical usefulness of a parallel RF transmit body MRI system with patient-adaptive RF shimming and parallel transmission as compared to conventional single transmit MRI using standard sequences for routine clinical use in body applications including liver, pelvis, colon and spine imaging in patients at 3.0T.