ISMRM 25th Annual Meeting & Exhibition • 22-27 April 2017 • Honolulu, HI, USA

Weekend Educational Course: MR Systems Engineering
Weekend Course

ORGANIZERS: Gregor Adriany, Ph.D., Mary P. McDougall, Ph.D. & Graham C. Wiggins, D.Phil.

Saturday, 22 April 2017
Room 313A  08:30 - 12:00 Moderators: Priti Balchandani, James Bankson

Skill Level: Basic to Intermediate

Slack Channel: #e_phys_eng
Session Number: WE02


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
Upon completion of this course, participants should be able to:

-Assess the basic subsystems hardware components of an MRI scanner, including how they interact and function;
-Evaluate 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.



08:30
MR Systems Overview
Seung-Kyun Lee
This educational talk is designed to provide a broad overview of the functions and interactions of the subsystems of a modern clinical MRI scanner and explain various design constraints originating from engineering and physiological limitations.

09:00
Magnets: Design, Manufacturing, Installation, Present & Future Technology
Johan Overweg
The field of an MRI magnet is generated by a circulating current through a sectioned superconducting coil, kept at its operating temperature by a refrigerated cryostat. Active shielding coils confine the stray field to a small volume near the magnet. This presentation covers various aspects of design and operation of these magnets.

09:30
Shimming: Superconducting & Passive Shims; Higher Order Shims, Shim Arrays & Dynamic Shimming
Laura Schreiber
Shimming denotes the technical procedure to improve the homogeneity of the magnetic field in the MRI system. This presentation will give an overview about why the magnetic field is inhomogeneous at all, and what the consequence is. Passive and superconducting shims as technical means to improve the shim in every MRI system are described. Practical information on when shimming is needed, and what the operator can do to optimize the shim of their MRI system will be given as well. Moreover, latest developments like high-order shim systems, shim arrays and dynamic shimming will be presented.

10:00
Break & Meet the Teachers
10:30
Gradient Coil Design Considerations, Manufacturing & Limitations
Richard Bowtell
This presentation will describe the parameters that characterise the performance of the  gradient coils which are used to generate magnetic fields that vary linearly with position in MRI. The methods for designing cylindrical gradient coils, including the incorporation of active magnetic screening, will then be described, along with boundary element methods that can be used to design coils on any surface. The important elements of coil fabrication will also be considered.

11:00
Gradient Drivers: Amplifier Considerations, Power, Tuning, & Cooling
Ian Connell
11:30
Eddy Currents & Interactions: Calibration, Compensation, & Pre-Emphasis
David Brunner
The native accuracy of gradient and shim systems is too low in order to drive MRI sequences. To avoid corresponding image artefacts the gradient chains are feed-backed, pre-distorted and post-corrected based on accurate characterizations or direct measurements of the field evolution in the scanner. In this talk, the underlying principles of the encountered distortions and frequently applied correction methods will be discussed.

12:00
Break & Meet the Teachers
 
MR Systems Engineering
Weekend Course

ORGANIZERS: Gregor Adriany, Ph.D., Mary P. McDougall, Ph.D. & Graham C. Wiggins, D.Phil.

Saturday, 22 April 2017
Room 313A  13:15 - 16:45 Moderators: Priti Balchandani, James Bankson

Skill Level: Basic to Intermediate

Slack Channel: #e_phys_eng
Session Number: WE02


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
Upon completion of this course, participants should be able to:

-Assess the basic subsystems hardware components of an MRI scanner, including how they interact and function;
-Evaluate 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.



13:15
RF Transmit: Power Delivery, Decoupling, & Duty Cycle
Michael Twieg
The RF transmit chain is one of several “black box” systems in the MRI scanner. The implementation of the RF transmit chain has remained fairly consistent since the earliest clinical MRI scanners. The advent of parallel transmission (pTX) provides a compelling opportunity to rethink not only the design of the RF power amplifiers (RFPAs) and coils, but of the entire MRI scanner. In this lecture we will review fundamental RFPA concepts such as linearity and efficiency. We will then explore advanced topics relating to pTX, including control, decoupling, local amplifiers, and switchmode amplifiers.

13:45
RF Receivers: Signal Detection Chain, Digitization, System Noise Figures - from MRI Signal to Bits
Arne Reykowski
This presentation is designed to give an overview of the building blocks of an MRI receive RF chain, starting with the local MRI coil going all the way to the image processor. 

14:15
Controlling the MR Subsystems: Pulse Sequence Control, Waveform Generation & Real-Time Control
Juan Santos, William Overall
Lecture for scientists and clinicians interested in learning more details about the core software structure and control systems of an MRI machine.

14:45
Multi-Modality Imaging in an MRI Scanner: Simultaneous Imaging & Therapy - Making the Systems Compatible
Florian Wiesinger
Although envisioned since the late 1980s, hybrid PET/MR systems only became commercially available in the last few years and more than a decade later than hybrid PET/CT.  This is explained by the technological challenges originating from the combination of these two very different imaging modalities.  Manifold interferences between the two modalities (in terms of B0, Gradient, RF, Temperature, Photon Attenuation, Space Constraints, Workflow, …) needed to identified, understood and solved.  

15:15
Break & Meet the Teachers
15:45
Basic MR Safety: SAR to Temperature, Power Deposition/Monitoring, Effects of RF Coils & Field Strength
Yigitcan Eryaman
This lecture will cover basic safety issues related to MRI, focusing on power deposition and radio-frequency heating in the patients. Specific absorption rate (SAR) and its relation to temperature will be discussed. Various methods to simulate, predict,control and mitigate SAR and temperature will be introduced. Finally, the effects of RF coil geometry, field strength/frequency will be explained.

16:15
Peripheral Nerve Stimulation, Implants & Devices: Safe Use & Considerations for MRI
Ergin Atalar
16:45
Adjournment
 
 

The International Society for Magnetic Resonance in Medicine is accredited by the Accreditation Council for
Continuing Medical Education to provide continuing medical education for physicians.