A Frequency Modulation HArd Pulse ENcoding Sequence for Ultra-Short Echo Time High-Resolution Three-Dimensional MR Imaging

Due to its short T2* value and low proton density, MR imaging of the lung is quite challenging. Recently, ultra-short echo time (UTE) techniques, such as stack-of-spiral, were used to conduct lung MRI with good image quality. Here, based on stack-of-spiral, a frequency modulation hard pulse encoding (HAPEN) 3D UTE was proposed to optimize the echo time of different phase encoding steps in the slice direction. As a result, HAPEN can achieve shorter TE and get better SNR in human lung MRI compared to the traditional stack-of-spiral UTE sequence.