MXR Imaging acquired Oxford Instrument Healthcare in May 2020

4 Different Types of MRI Systems – An Exploration of Options 

A Breakdown of Four Common Types of MRI Systems

If your facility is considering investing in a new MRI system, you're going to have to put some serious thought into what type of MRI system is going to best fit your needs. In addition to the traditional closed MRI system, you'll want to weigh the benefits of an open MRI system, a upright imaging  MRI system, and an extremity MRI system. The following is a breakdown of the pros and cons of each to help you decide what type of MRI unit will best suit your facility:

Closed MRI

Closed MRI systems are built almost like tubes in which the patients are positioned  inside, thereby enclosing them almost completely. The bore in a closed MRI system is typically between 50 and 60 cm, which means the space within the system may feel tight for individuals who are a little bit on the larger side.

However, because of the way it's enclosed, the system is able to use a higher-powered magnet to produce high quality MRI images. It can take anywhere between 15 and 90 minutes to perform an MRI scan in a closed MRI system depending on the imaging procedure being performed.

The following are a few reasons why you might want to consider a more traditional closed MRI system instead of some of the alternatives that are out there:

• High-quality images - A closed MRI system uses a magnet that generate a magnetic field between 1.5T and 3.0T, allowing for more accurate diagnosis of a wide range of conditions , including hepatic metastases, fibrocartilage lesions, single or multi-vessel diseases, and more.
• Faster scanning - A stronger magnetic field means that a closed MRI system will be able to scan certain areas of the body much quicker than other types of MRI systems.

Unfortunately, there is a tradeoff to the advantages of a closed MRI system. As high-quality as the scans are, the comfort of the patient can sometimes be a concern. The following are a few of the drawbacks of using a closed MRI system:

• Some Patients May Not Fit - Larger patients may not be able to fit into a standard MRI system. Wide bore MRI systems, while not mainstream, are an alternative.
• The enclosure can cause discomfort - Patients who suffer from claustrophobia or anxiety issues may have difficulty staying inside an MRI system as long as is required. On top of that, if they fidget, it could cause the images to blur, requiring them to go through the entire process again. In some instances, physicians are able to sedate patients to make it easier for them to get through the scanning process. Wide bore MRI systems can also help overcome issues with claustrophobia.
• Closed MRI systems are loud - Closed MRI systems tend to make loud banging sounds while scanning, which can be particularly bothersome for patients since this banging may be intensified as a result of them being inside of the MRI. Many facilities  offer specially designed entertainment systems and in some cases some thing as simple as earplugs as a solution to this particular problem.

Open MRI

Open MRI systems were designed in a way that would more effectively address the comfort levels of patients during the MRI scanning process. Although patients still have to enter the system on their back, only half of their body will be enclosed by the system -- the sides remain open, unlike a closed MRI system. If only their legs need to be scanned, it means that their upper torso can remain outside of the system.

The open MRI system looks like a large disc that hovers over the patient with magnets positioned above and below them. The following are a few of the benefits of choosing an open MRI system:

• They cause less discomfort - Because they are more open, patients with claustrophobia or anxiety issues are more comfortable.They're also quieter, which helps make the process less stressful as well.
• They are more child-friendly - Parents can accompany children who are undergoing an MRI. Unlike a closed MRI system, the child being scanned will be able to see their parents and interact with them, especially if only their lower torso is being scanned.

Although open MRI systems address many of the comfort issues patients have with the closed MRI systems, they still have some issues. For example:

• Image quality isn't as high - Open MRI systems use magnets that can only generate a magnetic field strength of 0.3T to 0.7T, although there are some higher-end versions that can reach 1.2T. Either way, the scans produce lower resolution images than those generated by a closed MRI system.
• Ittakes longer to perform scans - As a result of the fact that an open MRI system uses magnets that are not as strong, it takes longer to complete the MRI.

Upright Imaging MRI

The upright imaging MRI system provides more flexibility for the patient than even the open MRI system. This is because an upright MRI utilizes Positional Imaging, meaning, besides just laying down, the patient can be scanned in numerous positions including sitting and standing.

The system essentially has two large discs about the height of the average person that sit in vertical positions to the left and right side of the patient. Think of it as an open MRI system that's been tilted on its side. The gap between the discs is where the patient can sit, stand or bend. Once placed into position, a "coil" will be placed around the area of the patient's body that needs to be scanned. Generally speaking, most upright MRI procedures take between 30 and 60 minutes.

The following are some of the advantages of using an upright MRI system:

• Easier to diagnose certain issues - Scans can be taken in positions that more accurately represent what your symptoms are. For example, if you have lower back problems, laying down helps make them less severe. As a result, the diagnosis may not be as accurate as if you were to stand up during the scan. Any issues with your joints or spine are more accurately evaluated using positional or weight-bearing images.
• More open design - Even in an open MRI system, the patient will still have to lie down facing the system above them. In an upright MRI system, the patient can face the open space of the room, which is much more comfortable and less disorienting for patients who are claustrophobic or have anxiety issues. In fact, patients can even watch TV while they are being scanned.
• More accommodating for larger patients - The need to lay down can be very restricting when it comes to closed and open MRI systems. Upright MRI systems are designed to accommodate patients weighing up to 500 pounds.

An upright MRI system certainly has its benefits, but it's not without its drawbacks. The following are two of the biggest disadvantages of an upright MRI system:

• More difficult to remain still - It's much easier for patients to remain still when they are lying on their backs than in upright MRI systems. This is simply because fidgeting is more natural in a sitting or standing position, especially since you're bearing your own weight. This can result in blurry images that will require the MRI to be redone.
• Quality of image recording not as high - Just like an open MRI system, the drawback of not being able to enclose the patient completely is that the magnet strength won't be as strong. An upright MRI system compares favorably to an open MRI with 0.6T, but this still does not match up to the 1.5T to 3.0T capabilities of a closed MRI system.

Extremity MRI

Extremity MRI systems were designed specifically to take MRI scans of the extremities, meaning the hands, arms, legs, and feet. Accordingly, they are much smaller than any other type of MRI system. The system is built with a small enclosed tube, not unlike a much smaller version of a closed MRI system, in which the extremity is inserted. This allows the patient to sit comfortably next to the system in a chair while the scan is being performed.

The extremity MRI system is extremely useful if the majority of the MRI scans you are doing are on the extremities of patients, such as fractures, bone infections, and nerve-related issues in the arms and legs. The following are some of the many benefits afforded by an extremity MRI system:

• High-quality images - Extremity MRI systems typically use a1.5T magnet which is much greater than both open MRI systems and upright MRI systems. This allows for detailed images of problem areas that are often just as clear as those taken by closed MRI systems.
• More comfortable for patients - Patients with claustrophobia or anxiety problems won't have any issues being scanned by an extremity MRI system since the majority of their body will be outside of the system. This means patients can sit or lie comfortably during the course of the scan. Additionally, extremity MRI systems are great for children as it allows their parents to accompany them and engage with them during the scan.
• Less fidgeting - Images are less likely to turn out blurry because patients have an easier time keeping still. This is because they only have to keep the extremity being scanned still -- they can move the rest of their body around while sitting or lying in place.
• Quieter operation - Because extremity MRI systems are much smaller, they make much less noise than other types of MRI systems, thereby making the experience less agitating for patients.
• Lower costs - Because the systems are much smaller, the initial and ongoing operational costs of an extremity MRI system is much less than other types -- even if you invest in an extremity MRI system that uses cryogens, which increases service costs.

As you can see, an extremity MRI system certainly has plenty going for it. The only major drawback -- and it's a major one -- is that it's only suitable for scanning extremities. Patients with back or head issues will need to be scanned by a larger MRI system since the extremity MRI system isn't built for that purpose. In fact, it won't be able to scan shoulders either. You may also run into issues with obese patients since their arms or legs may be too large to fit into the bore of a standard extremity MRI system.

Why Would a Hospital Choose One Kind of system Over another?

Each one of the four different types of MRI systems has their pros and cons. Some focus on being able to accurately identify specific issues in specific parts of the patient's body, while some more effectively address the comfort issues of the patient.

While having one of each would allow you to address the needs of every type of patient that comes in, this is usually not financially feasible since the upfront costs and ongoing operational costs of just one MRI system can be significant. It's why most hospitals will opt to go with a closed MRI system. Although it may not be the most comfortable for patients, it will allow facilities to image up to 90% of their patient population and provide the highest quality images, which will allow for the most accurate diagnoses.