Laura Sacolick

Yasuhiko Terada

Keywords: Image acquisition: Reconstruction, Image acquisition: Fast imaging

Magnetic resonance imaging (MRI) suffers from long acquisition times, leading to patient discomfort and motion artifacts. This lecture explores acceleration strategies, including non-Cartesian sampling (radial, spiral) for efficient k-space coverage and parallel imaging (SENSE, GRAPPA) to reduce scan time using multiple receiver coils. We will also discuss compressed sensing-based reconstruction methods for further acceleration. Additionally, we will briefly address correction techniques for artifacts arising from hardware imperfections. By combining these approaches, accelerated MRI can achieve high-quality imaging with improved scan efficiency, benefiting both clinical and research applications.

Matt Bernstein

Keywords: Image acquisition: Artefacts, Physics & Engineering: Physics

Concomitant fields and eddy currents are distinct effects, but they are similar in that they both affect resonant frequency and can cause image artifacts. The concomitant field is a fundamental physical effect and arises whenever a gradient is activated. Eddy currents are a system-dependent effect that result from currents induced within conducting structures by gradient ramping. As such, eddy current measurement techniques are important. Eddy currents are problematic at all field strengths, while the concomitant field is more problematic at low-field. This talk will focus on the origin and correction of these two effects, while comparing their similarities and differences. 

Nikolai Avdievich

Fraser Robb

Yigitcan Eryaman

Keywords: Physics & Engineering: Physics, Physics & Engineering: Gradient & B0 Safety, Physics & Engineering: RF Safety

MR safety concerns regarding static, gradient, and radio-frequency (RF) fields will be discussed. This includes an explanation of the forces and torques exerted on ferromagnetic objects in the MRI scanner. The impact of static field exposure, particularly from UHF, on both animals and humans will also be addressed. Next, the effects of gradient field excitation, such as peripheral nerve stimulation and acoustic noise, will be covered. Lastly, safety considerations related to RF fields will be presented.

Yaohui Wang

Keywords: Physics & Engineering: Hardware

Gradient coil is a critical bridge that transforms a NMR to MRI. With the gradient magnetic field, the spatial nuclear information is encoded and the differences are then reflected on the image. A good gradient coil design will enhance the imaging function, process and outcome. This course will discuss different methodologies in the gradient coil design including boundary element method, finite difference method and discrete wire method and the corresponding design cases will be illustrated. Some real application effects in the integral MRI system will be presented.