Stefan Skare

Keywords: Image acquisition: Sequences, Physics & Engineering: Pulse design, Neuro: Brain

The single-shot echo-planar imaging (EPI) sequence was invented by Peter Mansfield in 1977 and has many clinical and research applications in MRI today. The GE-EPI variant is the most common and time-efficient pulse sequence for fMRI and perfusion,  but also for clinical bleeding detection workup. The spin-echo EPI variant has been almost exclusively used for clinical and research diffusion-weighted MRI. Emphasizing the freezing of physiological motion and MRI with less need for anesthesia, Mansfield got many of the benefits of contemporary EPI correct. Notably, EPI's efficiency stems from the high relative fraction of data collection during the scan.

Lipeng Ning

Keywords: Neuro: Brain Connectivity, Contrast mechanisms: Diffusion, Contrast mechanisms: fMRI

In this course, we first describe several echo planar imaging techniques, including parallel imaging and simultaneous multi-slice imaging. We then overview the physics and modeling techniques for diffusion MRI, including diffusion tensor imaging and advanced microstructural modeling techniques. Further, we will provide an overview of neural physiology related to functional MRI, data acquisition and modeling techniques.  

Benjamin Ellingson

Keywords: Image acquisition: Fast imaging, Neuro: Brain, Image acquisition: Sequences

Motivation: Echoplanar imaging (EPI) is instrumental to neuroimaging and applications that require high speed imaging including DTI and BOLD functional MRI. 

Goal(s): In this lecture, we will discuss additional sequence modifications and advanced applications beyond DTI and BOLD with the specific goal of characterizing the brain tumor microenvironment (i.e. vascularity, hypoxia, acidity, and salinity). 

Approach: The lecture will discuss the use of standard and modified EPI techniques for DSC perfusion imaging, pH-weighted amine CEST, and interleaved multinuclear imaging. 

Results: New EPI and image contrasts can be combined to increase spatiotemporal resolution, optimize image acquisition, and provide critical information into brain tumor biology. 

Impact: EPI has been instrumental to neuroimaging and applications that require high speed imaging including diffusion and BOLD-based functional MRI. In this lecture, we will discuss sequence modifications with the goal of characterizing brain tumor biology within clinically realistic scan times. 

Alexander Lin

Jie Luo

Keywords: Image acquisition: Artefacts, Image acquisition: Image processing

The Echo Planar Imaging (EPI) sequence is a cornerstone of MRI studies, widely employed in functional MRI (fMRI) and diffusion MRI (dMRI). However, static field inhomogeneities leads to serious image distortions, leading to impaired data integrity, difficulty registering functional images to structural images, and errors in downstream analyses. In addition, MR spectroscopic imaging (MRSI) that employs EPSI readout also suffer from static field inhomogeneities induced spectral distortions. In this course, we will illustrate the common distortions of EPI sequences, review state-of-the-art distortion correction methods, and touch upon some of the efforts that leverage machine learning in EPI distortion correction.

Hua Guo

Keywords: Image acquisition: Fast imaging, Image acquisition: Sequences, Physics & Engineering: Physics

EPI is one of the most important MRI techniques, widely used in functional MRI and DWI. Unlike conventional Cartesian sampling methods, EPI can cover k-space in just a single or a limited number of excitations. This distinctive sampling approach also results in a unique signal sampling acceleration mechanism, differentiating it from traditional techniques. This lecture will introduce how parallel imaging is used in EPI. We will begin by discussing the use of conventional parallel imaging for EPI, followed by an introduction of simultaneous multislice imaging. Finally, we will delve into undersampling strategies in 3D EPI for fMRI and DWI.

Jana Hutter

Keywords: Physics & Engineering: Pulse design, Body: Body, Contrast mechanisms: Diffusion

Echo Planar Imaging is a key tool for a range of imaging techniques such as diffusion MRI, elastography and functional MRI outside of the brain. Its efficiency and ability to freeze motion within the slice but also challenges such as vulnerability to susceptibility artifacts, T2* blurring and limits in possible resolution are all emphasized outside of the brain and trigger exciting novel technical developments. EPI is a standard part of the diagnostic pathway in eg breast and prostate cancer. Novel insights into the fiber architecture of the beating heart and the transfer of oxygen across the placenta are enabled.

Fuyixue Wang

Keywords: Image acquisition: Sequences

Echo Planar Time-resolved Imaging (EPTI) is a novel readout technique that addresses the limitations of EPI such as distortion and T2/T2* blurring by time-resolving across the EPI readout, while providing additional capability including multi-contrast multi-echo imaging. EPTI was initially introduced as a multi-shot technique highly suitable for high spatial resolution applications, and recent developments have also enabled single-shot EPTI acquisition to achieve high temporal resolution comparable to single-shot EPI, making it highly efficient for dynamic imaging applications as well. This talk will review EPTI-related techniques, the recent developments, and their applications in diffusion MRI, functional MRI, and multi-parametric quantitative imaging.