Magnetic resonance imaging rightly holds its place near the top of the medical imaging modality value chain. It offers exceptional quality in terms of resolution, particularly in brain imaging, and its use of a strong magnetic field, as opposed to ionising radiation, eliminates a major safety concern for patients. Such imaging advantages come at a cost, however. The modality hardware itself for high end equipment comfortably exceeds $ 1 million. With this capital expenditure comes an additional expenditure of energy; the headache of correctly siting a scanner so that the hospital / radiology practice can accommodate the equipment’s strong magnetic field. This is proving an extra strain on the hard-stretched budgets of hospitals across Europe, and is a significant barrier to the acquisition of a new MRI unit, or - increasingly so with the advent of 3 Tesla machines - upgrading to a new one. Despite these provisos, the stringent following of siting and safety guidelines can ensure that the maximum potential of an MRI scanner is realised, both in terms of image quality and patient throughput.
Complex imaging equates to complex installation
Siting concerns for MRI contrast sharply with those for CT and X-ray. The latter two modalities have levels of radiation believed to be detrimental after prolonged exposure. As such, sufficient shielding must be in place to ensure that radiation does not reach outside the examination room. Conversely, this concept of protection has a two way dynamic with MRI: Not only must the spread of magnetic field be contained (as will be elaborated upon subsequently), but the MRI unit itself must be shielded form outside interference. The magnetic field of the MRI unit is extremely sensitive to radio frequencies (RF), which necessitates the installation of an RF shield in the MRI room itself in order to maintain acceptable levels of image quality.
The need for vigilance is not over once this set up is established either. Great care and consideration must be taken in terms of any hospital building and construction work. Any vibrations from such work, as well as any large quantities of metal being moved near the site of the MRI scanner, can cause extreme disruption to the sensitivity of the magnetic field, and hence the quality of the attendant MRI image. Equally, close attention must be paid to the location of adjacent and nearby power lines, as the severance of power from an MRI unit can cause critical damage to its super-conductor systems if left unchecked for more than 48 hours.
These factors can be of severe detriment to hospitals already extremely hard pressed in terms of administration and infrastructure, and a pause for thought for many wishing to install an MRI.
Patient and staff safety concerns
Whereas the potential dangers linked to CT and X-ray are of a slow-burning nature – the disputed risk of radiation exposure increasing the risk of cancer – dangers associated with MRI are of a more immediate and dramatic nature. Insufficient screening before entry into the magnet room can all too often trigger the "missile phenomenon", whereby ferrous patient possessions fly onto the magnet, irresistibly drawn by the magnetic field. Such seemingly small accidents can endanger patient safety, and be very costly in terms of downtime whilst objects are recovered. In extreme cases, this "missile" effect requires a modality vendor representative to step in and ramp down the magnet; costly in terms of increased call-out related downtime, and potentially crippling damage to the machine itself.
MRI in the zone (all four of them)
Combating these risks is an elaborate, and again potentially off-putting, process. The American College of Radiology’s annual white paper is keen to expound on the benefits of its "four-zone" MRI suite safety protocol. This stipulates that zone 1 represents the world outside the MRI suite, zones 2 and 3 provide two spaces between zone 1 and the magnet room itself (zone 4). These rooms can accommodate a variety of incarnations; they can consist of patient screening areas, waiting/ changing rooms, the MRI control room itself, and a long list of preparation or holding areas. These all designed to protect the MRI equipment from the outside world, and the outside world from it. This is of increased urgency when one takes into account the effect the MRI scanner’s magnetic field has on surrounding imaging equipment. In fact the scanner does not even need to be directly adjacent to PET or CT scanners to negatively impact upon the performance of these other modalities, both of which have proven extremely sensitive to any magnetism that exceeds the normal levels of ambient magnetism related to polar forces.
As is evident from the range of acceptable areas qualifying for inclusion in the four-zone principle, setting up a safe and functioning radiology suite that can effectively accommodate MRI need not be too taxing. The mindset, prevails however, that setting up such a scenario is incredibly difficult; sensitivity exacerbated by the heavy demands already made on European public hospital infrastructure.
Siting difficulties also house potential
Whilst the proceeding exhaustive list of complications paints a rather gloomy scenario for the further growth potential for MRI, diligent adherence to these safety principle will prove a boon to both the modality and equipment service sectors for MRI. A well-integrated and functioning MRI set-up brings enormous efficiency gains. An infrastructure set-up that allows for better patient visualisation and supervision from the control room, coupled with a smooth patient screening procedure will increase throughput noticeably. This will, in the long term, bring financial benefits that will be further enhanced as the uptime percentage of the scanner is increased by avoiding accidents wrongly perceived as inevitable.
Indeed, the daunting upfront costs involved in such safety contingency can be offset to a significant degree if allowed for in the initial planning process. The European market for medical imaging is mature. This has created an environment where technological specification brooks little comparison between the major OEMs. As such, these same companies now strive for differentiation in two principal areas; workflow, and equipment services. The latter is represented by a full array of multi-vendor and asset-management services, offering implementation, maintenance, financial assistance and training to different levels corresponding to different budgets. Health care providers can furnish themselves with a better financial deal if they are willing to consider the implications of proper implementation from an early stage.
Indeed, it would seem that providers are increasingly concerned about implementation issues, a trend reflected in the rise in the number of independent service organisations in the late 1990s in the USA and (to a lesser extent) Europe. Health care providers are therefore in an ever stronger position, with more players competing for installation contracts.
In the light of these arguments, MRI has some way to go before ease of installation matches its clinical excellence. Vendors are playing an increasingly active role, however, in making MRI installation less demanding both financially and in terms of infrastructure. A greater vendor effort to educate physicians and radiologists, thereby discrediting the myths that have built up around the difficulty of setting up a safe and efficient suite, will go along way to helping the MRI modality settle fully into the very heart of the mainstream imaging markets in the future.
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