Abstract

With a high-performance gradient system, gradient-induced eddy current in the RF shield can cause a substantial temperature rise in the patient bore. Especially, a multi-echo EPI sequence involving intense gradient switching and long echo trains, usually lasts for >10 minutes in many resting-state functional MRI studies. The temperature change caused by RF shield heating can jeopardize patient safety and hardware reliability. Based on theoretical and experimental investigation, we demonstrated two main factors that could contribute to the RF shield heating in a high-performance compact 3T scanner, namely the shield surface conductivity and mean-square slew rate of the gradient waveform.