Magnetic Resonance Imaging (MRI) is often the best way for a physician to easily diagnose a medical problem, but for many patients, the tight space of the enclosed scanners just doesn't work.
Newer scanner models offer the potential to change this and make diagnostic imaging easier for many patients. Known as open MRI or open air MRI (the name may suggest a field with a gentle breeze blowing, but these procedures still take place in the clinic), this technology has the potential to change the future of MRI.
Whether you're an MRI technologist, radiologist, or student, how do you know which type of scanner is best for a particular patient? Let's take a look at what's on the market.
A Flaw that is Holding Back Open Air Models
There's no question that MRI has brought countless benefits to medicine. Unfortunately some MRI patients are unable to fit inside the traditional closed scanner. Others don’t like the idea of spending 30 minutes or more inside the extremely narrow cylinder of the machine.
Open scanners offer more space and comfort. Their only big downside is that currently, their maximum magnetic strength rarely goes above 1.0 Tesla (compared to 3.0 for closed scanners).
This means closed MRIs produce images with better clarity and detail. However, magnetic strength for some of the open new models has been slowly increasing.
3 Innovative Open MRI Machine Constructions
Unlike closed scanners, open air MRI machines differ greatly in their shape and design.
These are the three most common types of open air scanners:
Semi-Open High Field Scanners
These resemble a closed scanner, but the bore is very short, with widely flared ends. That means that if the patient’s midsection is being examined, their head and legs will stick out of the “tunnel.” The short bore reduces anxiety and claustrophobia, as the patient's body is never fully inside.
Open Low Field MRI
These units are usually composed of two horizontal magnetic disks, connected to a pillar with some space between them. When a patient is lying between the two disks, they will be surrounded by a lot of open space. This design allows for a wider range of positions for imaging.
Advanced Open MRI
The advanced open MRI consists of two vertically placed magnetic disks, attached to a supporting construction with some space between them. The two disks sit on either side of the patient, who can stand or even sit between the disks; the patient's front side remains open. The design also allows for some extra space on the sides. Advanced models are great for people who have difficulty lying down due to certain physical conditions or simply feel more comfortable sitting or standing.
The Common Characteristics of MRI Scanners
There are three basic types of MRI scanners available: open, closed-bore and wide-bore. The main differences between these three are the power of the magnet and the space available for the patient.
Both the closed and wide-bore types have long bores that normally surround the entire length of the patient's body.
The closed-bore MRI is your standard MRI scanner. It provides very clear and detailed images, thanks to its powerful magnet. Closed-bore MRI units have a magnetic strength ranging from 1.0 Tesla to 3.0 Tesla
However, due to the size and toroid shape (think of a huge donut) of these magnets, the bore of the scanner is only 23.5" in diameter.
Closed MRI is inconvenient for larger or claustrophobic patients, while open MRI lacks the high image clarity. Wide-bore MRI machines offer a good compromise. Just like the closed-bore scanners, they are equipped with strong magnets, but offer extra space and comfort.
The average diameter of the bore is 27.5", so they can accommodate larger patients well. The extra 4" also leaves some breathing space and reduces the uneasy feeling of confined space.
Open Vs. Closed Scans: What Are the Differences?
So which type of scanner should you use? That depends on the patient and the procedure; let's look at some of the variables to consider.
Pros of Open MRI
- Better suited to claustrophobic patients
- Provides more space and comfort
- Convenient for longer-lasting procedures
- There’s rarely a need for the patient to be sedated or anesthetized
Cons of Open MRI
- Impractical for scanning certain internal organs
- Lower image clarity
Pros of Closed MRI
- Clear and high-quality images
- Strong closed MRI magnets help examine areas that aren't visible to the weaker open MRI machines
- Generally more advanced compared to open scanners
- Wide-bore models are becoming more popular and increasing in diameter
Cons of CLOSED MRI
- Uncomfortable and especially unsuitable for claustrophobic patients
- Inaccessible to larger or obese patients
Unfortunately, some patients face different physical or mental barriers that prevent them
from undergoing either type of scan. For example, people with above-average height or weight may have trouble fitting in a closer scanner. If their physicians need a clear image of an internal organ to conclude the diagnosis, open air MRI may fail to provide those images.
What Does the Future Look Like?
Healthcare technology is continually evolving and manufacturers are working hard to satisfy the consumers’ demands (both those of patients and hospital workers). Thanks to recent innovations, some brands have found ways to significantly tweak the design of their models without losing magnet strength.
Some of the latest open MRI machines can achieve imaging results close to those of traditional closed models. This could mean that in the next 5-10 years, the gap in the image quality may vanish completely.
There are also highly specialized scanners that are well-suited for certain types of tasks. They allow for imaging in different positions and for sequences of movements. Whichever scanner you choose, MRI is a completely safe procedure for you and your patient, so their comfort and your diagnostic success can stay first on your mind.
To find out more about how MRI works and who are the people behind the equipment, check out MRI: Could It Kill You? Patient Care & MRI Tech Training.