Main System Components
Mathias Blasche, Ralph Kimmlingen
Siemens Healthineers | 10-05-2017
A typical MR system consists of three components or sub-systems:
- a magnet with a main magnetic field,
- a gradient system, and
- the radio-frequency (RF) system
The magnet is the most prominent – and most expensive – part of an MRI system. It creates the main magnetic field, B0, which serves as the basis for all magnetic resonance imaging.
There are several features and specifications of the magnet design that have an influence on different criteria: Image quality, patient comfort, and economic aspects. In this article, the aspects of magnet homogeneity, shimming capabilities, and their respective relevance for MRI will be addressed.
When talking about gradient performance, most will only state the maximum amplitude (strength) of the gradient system and the maximum slew rate (speed). But actually, there is much more to a gradient system. There are numerous design criteria for a gradient coil to be considered. In addition, there is the gradient power amplifier (GPA) that ‘drives’ the gradient coil. The performance of the gradient system and the power of the gradient amplifier are closely related.
This paper discusses the key characteristics of the gradient coil as well as the gradient amplifier, with their inter-dependencies and their clinical benefits.
The number of RF receiver channels is one of the key purchasing criteria. Multi-channel RF systems offer clear clinical benefits with regard to coverage, image quality, and speed. We have defined meaningful and relevant definitions for the terms “RF channels” and “coil density” that are clearly related to clinical benefits. This standard should help to achieve a better comparability of RF systems and coils across different vendors.
Read about the development of Connectome gradients and the work of the five institutions in the US and in Europe currently using MAGNETOM Connectom scanners by Siemens Healthcare MR.