Recent advances in MRI technology: Implications for image quality and patient safety

Abstract

Recent advances in MRI technology are presented, with emphasis on how this new technology impacts clinical operations (better image quality, faster exam times, and improved throughput). In addition, implications for patient safety are discussed with emphasis on the risk of patient injury due to either high local specific absorption rate (SAR) or large cumulative energy doses delivered during long exam times. Patient comfort issues are examined as well.

Keywords: Coils; MRI; Magnets; PNS; Patient safety; Peripheral nerve stimulation; SAR; Specific absorption rate.

Figure 1

An Optima 450w wide bore 1.5T MRI scanner, manufactured by GE Healthcare. Image courtesy of GE Healthcare.

Figure 2

Wide bore MRI systems have a large, 70 cm in diameter, magnet bore (measured at the walls of a finished product). This makes patient access and comfort levels much better in comparison to legacy MRI systems. The picture shows the bore of an SMS Aera 1.5T MRI system. Image courtesy of Siemens Medical Solutions.

Figure 3

Wide bore magnets, equipped with large load carrying patient tables, allow scanning of very large patients, as illustrated with this picture of a PMS Ingenia system. Image courtesy of Philips Medical Systems.

Figure 4

The principle of operation of multi-segmented MRI receiver resonators, called “phased array coils”.

Figure 5

An example of modular approach to receiver coil design, showing elements of a SMS TIM system. (a) The spine array is located under the cushion on the tabletop, additional elements (in this case, two flex coils) can be added as needed and plugged into receptacles visible at the far end of the table. (b) Patient setup using a spine array (under the patient), posterior and anterior head arrays, neurovascular array on top of patient neck, and torso array on the patient’s chest. All coils are plugged in and could be used at the same time. Images courtesy of Siemens Medical Solutions.

Figure 6

An example of a modular design, showing elements of a PMS dStream system. A head receiver coils has a posterior element, called a Base (visible a bottom part of the head assembly) and exchangeable top elements, either a Head (a), or HeadNeck (b). In the Head configuration the system uses up to 15 receiver channels, in the HeadNeck configuration – up to 20 channels. Images courtesy of Philips Medical Systems.

Figure 7

New design of the receiver pathways, as illustrated by the GEHC Discovery 750w system. The digitizing circuitry is located close to the receiver coils, shortening the analog signal path which leads to improved SNR in produced images. Image courtesy of GE Healthcare.