Syllabus

This talk will cover the following areas, using brain imaging as an example or target system to assemble various technologies: ·
- Targets for imaging: spatial resolution and image SNR. Discussion of what factors affect these imaging requirements drive the system design ·
- Magnet field strength: Love the field strength you have or go for higher field strength ·
- Gradient performance: What is needed, what is possible, and factors that relate to achieving gradient performance. Trade-offs are also discussed in terms of concomitant gradient fields, eddy currents, gradient linearity, gradient uniformity. Power and thermal considerations are also discussed. ·
- The design and implementation of RF receiver coils for SNR and acceleration are discussed. Issues with increasing SNR and decreasing coil g-factor noise are also discussed. ·
- Combining hardware and software solutions to achieve further SNR gains are also discussed.

Imaging performance relies on the ability to achieve a given spatial resolution with acceptable SNR. Achieving these performance metrics depends on the systems capabilities of the MRI system, which includes the magnet, gradient, transmit and receive RF coils, and also the systems electronics that are usually hidden away in the equipment room. All of these subsystems interact with each other and affects what can be achieved. The discussion focuses on the implications of each imaging performance requirement and what can be achieved. An example of a brain imaging system that addresses the “wish list” of requirements is used to illustrate the approach. The dependencies of each subsystem can be listed as:
· Magnetic field strength, bore size, homogeneity --> impacts magnet weight, size
· Gradient performance --> design trade-offs in eddy currents, homogeneity, torque/force balancing, gradient efficiency and slew rate
· Gradient performance --> peak power requirements, cooling, site power
· RF coils --> RF power, receivers, digital vs analog, size and noise figure trade-offs
· Operational issues --> SAR, duty cycle limits, site cooling and HVAC
· Designing a brain scanner --> trade-offs on magnet, gradient, and systems power

References

No reference found.