Joint Annual Meeting ISMRM-ESMRMB 2018

Joint Annual Meeting ISMRM-ESMRMB • 16-21 June 2018 • Paris, France

Weekend Educational Course
MR Systems Engineering

MR Systems Engineering: Part 1
Weekend Course

ORGANIZERS: Gregor Adriany, Christoph Juchem, Mary McDougall, Greig Scott

Saturday, 16 June 2018

N04

08:00 - 09:30

Moderators: Christoph Juchem, Sebastian Littin

Skill Level: Basic to Intermediate

Session Number: WE-02A

Overview
This one-day educational course is targeted at scientists and clinicians interested in understanding the engineering of magnetic resonance systems on a subsystems level. In a series of lectures from experts in MR Systems Engineering, attendees will first be provided with an overview of an MR system, and then learn about the design of magnet, gradients and shim systems, as well as the operation of the radiofrequency (RF) electronic subsystems that interface with RF coils. Issues relating to the site preparation and installation of new MR systems will also be discussed. In addition attendees will be taught about the key elements of MR safety as it relates to peripheral nerve stimulation (low frequency electromagnetic field interactions with the body) as well as energy deposition in the body from high frequency electromagnetic field interactions. The compatibility of medical devices and implants with an MRI scanner will be discussed. This course is aimed at scientists and clinicians with a technical background and interest in MR systems hardware. It is expected to provide attendees with an understanding of fundamental aspects of MR system operation.

Target Audience
Scientists and clinicians who are starting to work in the field of MRI and would like to have an overview of the engineering of an MR system. More experienced researchers in particular areas of MR Engineering will also benefit from hearing about recent advances in the engineering of MR systems.

Educational Objectives
As a result of attending this course, participants should be able to:
-Discuss the basic subsystems hardware components of an MRI scanner, including how they interact and function;
-Describe issues related to installing a new MR scanner, including space, venting, power and cooling considerations;
-Recognize practical limitations in the design and construction of magnets, gradients and shim systems;
-Identify the basic mechanisms by which medical devices interact with the magnet and gradients within an MRI scanner;
-Describe the interactions of electromagnetic fields (both low frequency gradient switching and high frequency RF) with the human body; and
-Explain the RF electronic subsystems that interface with RF coils, including interactions between separate transmit and receive coils.

08:00		MR Systems Overview Hubertus Fischer This educational talk provides a comprehensive overview on the building blocks of a clinical MR system. It concentrates on the essential functions to generate and to detect an MR signal, and how to achieve spatial resolution. It provides short look into the field generating unit, the RF transmit and receive system as well as the real time control unit. These topics outlined briefly as it is covered in detailed lectures of this session. The MR Systems overview is completed by covering the patient interface (patient table, communication and physiological triggering) and support functions as cooling, component supervision and RF shielding.
	Magnets & Shims
08:30		Magnets: Design, Manufacturing, Installation, Present & Future Technology Ben Parkinson This is an educational presentation to give ISMRM participants an understanding of the design and manufacturing processes required to produce a typical MRI magnet. The presentation explains the background to the magnetic field requirements for MRI and, using a worked example, explains typical MRI magnet design and the constraints under which that design occurs. In addition to the electromagnetic design, focus is placed on different cryogenic solutions for MRI magnets, and practical implementation of magnet design aspects.
09:00		Shimming: Superconducting & Passive Shims; Higher-Order Shims, Shim Arrays & Dynamic Shimming Vincent Boer Magnetic resonance imaging (MRI) and spectroscopy (MRS) rely on a strong and highly homogeneous magnetic field inside the scanner. Although magnets have a highly sophisticated design, there are still several techniques used to homogenize the field. Secondly, all biological samples will induce (dynamic) distortion in the field due to the tissue magnetic susceptibility. In this part of the course both passive shimming of a magnet, as well as active shimming with a subject in the magnet, will be discussed. Furthermore, several new advanced shimming strategies have emerged recently, some of the most promising ones will be discussed.
09:30		Break & Meet the Teachers

MR Systems Engineering: Part 2
Weekend Course

ORGANIZERS: Gregor Adriany, Christoph Juchem, Mary McDougall, Greig Scott

Saturday, 16 June 2018

N04

10:00 - 11:30

Moderators: Christoph Juchem, Sebastian Littin

Skill Level: Basic to Intermediate

Session Number: WE-02B

Overview
This one-day educational course is targeted at scientists and clinicians interested in understanding the engineering of magnetic resonance systems on a subsystems level. In a series of lectures from experts in MR systems engineering, attendees will first be provided with an overview of an MR system, and then learn about the design of magnet, gradients and shim systems, as well as the operation of the radiofrequency (RF) electronic subsystems that interface with RF coils. Issues relating to the site preparation and installation of new MR systems will also be discussed. In addition, attendees will be taught the key elements of MR safety as it relates to peripheral nerve stimulation (low frequency electromagnetic field interactions with the body) as well as energy deposition in the body from high frequency electromagnetic field interactions. The compatibility of medical devices and implants with an MRI scanner will be discussed. This course is aimed at scientists and clinicians with a technical background and interest in MR systems hardware. It is expected to provide attendees with an understanding of fundamental aspects of MR system operation.

Target Audience
Scientists and clinicians who are starting to work in the field of MRI and would like to have an overview of the engineering of an MR system. More experienced researchers in particular areas of MR engineering will also benefit from hearing about recent advances in the engineering of MR systems.

Educational Objectives
As a result of attending this course, participants should be able to:
-Discuss the basic subsystems hardware components of an MRI scanner, including how they interact and function;
-Describe issues related to installing a new MR scanner, including space, venting, power and cooling considerations;
-Recognize practical limitations in the design and construction of magnets, gradients and shim systems;
-Identify the basic mechanisms by which medical devices interact with the magnet and gradients within an MRI scanner;
-Describe the interactions of electromagnetic fields (both low frequency gradient switching and high frequency RF) with the human body; and
-Explain the RF electronic subsystems that interface with RF coils, including interactions between separate transmit and receive coils.

	Gradients
10:00		Gradient Coil Design Considerations, Manufacturing & Limitations Richard Bowtell Magnetic resonance imaging relies on the use of magnetic field gradients – that is a magnetic field, B (r) which varies linearly withposition, r, such that B (r) = G.r – to spatially encode the NMR signal. Such gradients are generated by passing currents throughspecially arranged coils of wire, placed on a former that surrounds the imaging subject. Three separate coils are needed in order toproduce a linear variation of the z-component of the magnetic field along each of the three Cartesian directions (x, y and z). Theperformance of the gradient coils and the amplifiers that are used to drive them dictates the kind of gradient waveforms that can beused in an MR scanner, particularly controlling the maximum gradient strength and rate of change of gradient with time that can be employed. Since the use of strong and rapidly switched gradients generally improves image quality and the speed of imagea cquisition, considerable benefits can result from optimising gradient coil performance.
10:30		Gradient Drivers: Amplifier Considerations, Power, Tuning & Cooling Juan Sabate Improvements in magnetic resonance imaging (MRI) require increased performance of the gradient amplifier. The objective of the presentation is to provide a description of the gradient amplifier functionality as part of the gradient system and to explain the design of the amplifier to meet the MRI requirements. PSDs reproduction fidelity and power needed for gradient fields requires switched amplifiers. The fidelity is achieved using digital control with high control bandwidth, feedforward and adequate compensations. New SiC semiconductors reduce losses keeping high performance and reducing volume and cost. The presentation provides detailed description of high-performance amplifier implementation and test results.
11:00		Eddy Currents & Interactions: Characterization & Compensation S. Johanna Vannesjo Magnetic resonance imaging relies on the ability to produce spatially linear magnetic fields (i.e. gradient fields) with a defined temporal evolution. This is achieved with room-temperature gradient coils, through which time-varying currents are passed. The resulting change in magnetic field will however induce eddy currents in nearby conducting structures according to Faraday’s Law of induction. This distorts the time-course of the gradient fields, leading to artefacts in imaging and spectroscopy. This presentation will give an overview of how eddy currents are generated, how to characterize them and how to compensate for their effects on the field.
11:30		Lunch & Meet the Teachers

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