  Multi-shot echo planar imaging (msEPI) is a promising approach to achieve
high in-plane resolution with high sampling efficiency and low T2* blurring.
However, due to the geometric distortion, shot-to-shot phase variations and
potential subject motion, msEPI continues to be a challenge in MRI. In this
work, we introduce acquisition and reconstruction strategies for robust,
high-quality msEPI without phase navigators. We propose Blip Up-Down
Acquisition (BUDA) using interleaved blip-up and -down phase encoding, and
incorporate B0 forward-modeling into Hankel structured low-rank model to enable
distortion- and navigator-free msEPI. We improve the acquisition efficiency and
reconstruction quality by incorporating simultaneous multi-slice acquisition
and virtual-coil reconstruction into the BUDA technique. We further combine
BUDA with the novel RF-encoded gSlider acquisition, dubbed BUDA-gSlider, to
achieve rapid high isotropic-resolution MRI. Deploying BUDA-gSlider with
model-based reconstruction allows for distortion-free whole-brain 1mm isotropic
T2 mapping in about 1 minute. It also provides whole-brain 1mm isotropic
diffusion imaging with high geometric fidelity and SNR efficiency. We finally
incorporate sinusoidal wave gradients during the EPI readout to better use coil
sensitivity encoding with controlled aliasing.
