MRI Choosing a Scan

Types of MRI Scanners: Closed MRI Scanner, Open MRI Machine, Wide Bore MRI, and Choosing the Right MRI Scanner Machine

We give you multiple MRI options all in one place, but knowing which type of MRI scanner machine to choose can be difficult. This guide will help you decide.

Written by Chelsea Okonkwo
Last updated 30 Jul, 2024

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What does mri stand for? MRI stands for 'magnetic resonance imaging,' a non-invasive and painless procedure that uses a strong magnetic field, high-frequency radio waves, and a computer to visualise changes in organs and tissues inside a patient’s body. Compared to X-rays and computerised tomography (CT) scans, MRI scans don’t involve radiation use, making them a safer option for pregnant women, children, and people who may require repeated scans.

But MRI machines aren't all created equal! There are several different types of mri scanners, each with its own unique features, strengths,   and use cases. This article explores the differences between closed MRI scanners, wide-bore MRI machines, and open MRI machines so you can confidently choose the one that best fits your specific needs and comfort level. We also answer the questions: ‘what does an mri machine look like?’ and ‘how does an mri machine work?’.

Closed MRI machine

A closed MRI machine, also known as a 'closed bore' MRI scanner, is a large, tube-shaped machine that resembles a hollow cylinder. It is enclosed on all sides except for an opening (the bore opening) on both ends, which is about 60 cm (~23.6 inches) wide. At the entrance of this opening, there is a padded table where patients lie down and are slid into the machine. Depending on what part of your body needs to be scanned, you might enter the machine head-first or feet-first.

The interior of the closed-bore mri scanner houses a ring of powerful magnets that generate a strong magnetic field, along with specialised coils that send radio waves and receive magnetic resonance (MR) signals. These two components work together like a super-sensitive camera system to take pictures of what's happening inside a patient's body. If you are curious about the science that makes this possible, check out our blog post: MRI Scans: The Complete Guide.

The closed mri machine is the standard, traditional MRI, so it is well-established and widely used in medical imaging. It is suitable for high-quality, detailed three-dimensional (3D) imaging of the body’s bones, internal organs, and soft tissues like blood vessels, spinal cord, nerves, muscles, and tendons. It can be used to diagnose a range of conditions, such as neurological disorders, vascular abnormalities, spinal and nerve injuries, tumours, musculoskeletal injuries, and diseases of the internal organs (e.g., small bowel, breasts, adrenal glands, ovaries, gallbladder, etc.).

The only drawback of the closed mri scanning machine is its enclosed, tube-like design. If a patient goes into the machine head first, there might be only a few inches between their face and the machine's interior. This can induce anxiety in patients, especially those who are claustrophobic. Larger patients and those with mobility issues may also find it too confining and uncomfortable, or they may not fit inside at all. 

MRI machines have varying magnetic field strengths (MFS), measured in Tesla (T). Closed MRI machines are considered high-field scanners, with magnet strengths ranging from 1.5T to 3T in commercial settings.

A 1.5T closed MRI machine generates a magnetic field more than 30,000 times greater than the Earth’s magnetic field, and it is suitable and effective for most types of MRI imaging. The 3t mri scanner, being twice as powerful, is often recommended for certain intricate body parts like the brain, as it can produce significantly clearer and more detailed images in about half the scan time. Patients with chronic pain or children who find it challenging to stay still for long periods may also be recommended a quicker 3T scan.

For more information on the differences between 1.5T and 3T MRI scanners, read: What is the difference between a 3 Tesla and 1.5 Tesla scanner?

Wide bore MRI machine

Wide bore MRI machines look and work just like the closed bore mri machines, except they feature a wider bore (hole) opening, typically around 70 cm (~27.6 inches) in diameter, and are more spacious inside. While a 10 cm difference in space may not seem a lot, for patients with claustrophobia, wide-bore mri machines provide a more comfortable alternative to traditional MRI scanners while still delivering high-quality images.

Additionally, in providing more headroom and space, the wide-bore machine accommodates larger and taller patients more comfortably. People with mobility issues may also have less difficulty getting and staying in position for their scan. 

Aside from the difference in bore diameter, there are other differences between closed and wide-bore MRI machines:

  • Weight limit. While closed MRI machines typically support weights ranging from 300 to 450 pounds (lbs), wide-bore MRI scanners can accommodate up to 550 lbs.

  • Image quality. Like the closed MRI machine, the wide-bore MRI is a high-field scanner and can be trusted to deliver high-quality, detailed images. However, the image quality of the closed MRI is slightly superior because  the magnets and coils are  closer to the scanned body part, resulting in better signal reception.

Open MRI machine

Diagnostic imaging centres and hospitals with open MRI scanners offer a more spacious and comfortable alternative to both closed and wide-bore MRI machines. 

Open mri scanners often have a C-shaped design with magnets above and below a padded bed, rather than surrounding it completely. All the sides are completely open except for the area above and below the patient, where the magnets are located. Similar to closed and wide-bore MRI machines, patients are moved into an open mri scanner head-first or feet-first, depending on the body part that needs to be examined.

Another type of the open MRI machine, the open upright MRI machine, has magnets standing vertically at either side with a chair or bed in the middle. 

Open upright MRI machines are called 'truly open mri scanners,' as they are open at the top, front, and back. Patients can be scanned lying down, sitting, standing, or bending in different positions, and can even watch television during the procedure. This makes it an ideal choice for extremely claustrophobic patients, as well as those who are obese, elderly, young, or have mobility issues.

An open upright MRI machine is a valuable tool for diagnosing spinal and joint problems, as it can easily visualise dynamic changes that occur when the spine supports body weight (i.e. while standing up).

Here are some major differences between the closed and open MRI machines:

  • Patient comfort and accessibility. Being inside the 60 cm-wide bore of the closed mri machine can make patients feel claustrophobic, and some larger patients may not fit in the scanner at all. The open MRI machine was invented as a new mri machine for claustrophobia and is a more comfortable choice for larger, claustrophobic or reduced mobility patients as it allows them to be scanned in whichever position they prefer. 

  • Weight-bearing capabilities. When it comes to suitability for larger patients, the traditional closed bore MRI scanning machine can typically support weight of 300 to 450 pounds (lbs), while the open MRI machine can hold up to 770 lbs. Although, these weight limits vary depending on the manufacturer.

  • Noise level. A closed mri scanner machine makes loud clicking, clanking, and thumping noises which are amplified and reverberated due to its tunnel-like design. Its noise level ranges from 82 to 113 decibels—comparable to rattling garbage cans or live rock music. Most scanning centres will usually offer earplugs or headphones to protect your hearing during your scan. Conversely, an open mri machine is about 70% quieter (around 25 decibels), comparable to a quiet conversation or rustling leaves.

  • Image quality. The only downside to open MRI scanners is their lower image quality and longer scan times compared to traditional closed-bore mri machines. This is because they are low-field scanners with magnetic strengths ranging from 0.2 to 0.35T, though some may be as high as 0.7T or even 1.2T. Their lower magnetic strengths make them less suitable for investigating complex cases involving the brain, heart, blood vessels, joints, and small body structures, where high image contrast, clarity and resolution is crucial. They may also miss subtle abnormalities like early-stage tumours. 

Closed MRI machines, on the other hand, produce higher-quality images. An open MRI scanner is only able to rival this quality by allowing patients to feel more comfortable and remain still during the procedure, resulting in clear images free from motion blur or distortion. 

Extremity MRI Scanners

An extremity MRI scanner is a smaller, more compact version of the traditional closed MRI machine used for imaging the peripheral joints (wrists, elbows, ankles, and knees), ligaments, bones, and tendons of the upper and lower extremities (limbs). During a scan, patients are typically seated comfortably in a chair or reclined position next to the machine, with one of their limbs placed inside the small bore (hole) of the scanner and the other beside them or on a footrest.

The extremity mri scan machine is highly sensitive to soft tissue changes in the arms and legs and is often used to diagnose conditions, including fractures, tumours, bone infections, inflammation, bleeding, muscle tears, nerve injury, and degenerative joint diseases like arthritis. It is also more convenient and comfortable, especially for claustrophobic patients, as it eliminates the need to insert a large portion of the body into an enclosed space. 

View from inside mri machine

If you’re wondering, "What does a person inside an MRI machine see?" The view can vary depending on the type of scanner being used.

  • Closed MRI machine: The inside of a closed MRI machine is brightly lit with smooth, rounded walls. If you are moving into the machine head-first, your primary—and ideally, only —view will be the blank white roof/ceiling of the machine, which will be close to your face. 

If you are having a brain scan, you may need to wear an mri head cage to amplify the scanner’s signals. No worries! Although it can potentially add to the feeling of confinement, it won’t cause any harm and you will be able to see out of the cage at the machine’s ceiling space.

  • Wide-bore MRI Scanner machine: The view inside a wide-bore MRI scanner is similar to that of a closed MRI machine, but with more space between your face and the top of the machine, reducing the feeling of confinement.

  • Open MRI scanner: Since all sides of the machine are open, you will see less of the machine itself and can look around to observe your surroundings.

It’s important to note that for both the closed and wide-bore mri machines, your entire body will not be positioned inside the scanner. For instance, during a knee MRI, only your leg-to-knee area will be inside the scanner, while a head or abdominal MRI will typically involve just your head-to-torso area being positioned within the machine.

Many hospitals and diagnostic imaging centres prioritise patient comfort, so you may be offered an eye mask where there are light effects or screens that cause you to feel anxious. Also, an emergency buzzer will be placed in your hand at the start of the scan, allowing you to call the attention of your MRI technologist if needed.

How much does an MRI machine cost?

There is no straightforward answer to the question, "What is the cost of MRI scanner machines?" MRI machine prices can range from £30,000 to £700,000, depending on factors such as field strength, coil type, manufacturer, year of manufacture (YOM), bore diameter, gradient strength, slew rate, and whether the machine is new or refurbished. 

Additional costs, including installation, preparation of the scan room, logistics, ongoing maintenance and service contracts, and technical support, may add to the upfront cost of getting an MRI machine. Understanding that scanning costs vary depending on the type of machine you need or choose can help you approach your MRI scan with more informed expectations.

Additional MRI equipment

During an MRI scan, some additional mri equipment may be used to ensure patient comfort, image quality, and diagnostic accuracy. They include: 

  • Props such as cushions, blocks, and straps to support your body, ease your pain, minimise discomfort, and prevent movement. If the exam table is cold, you can even request a blanket to keep warm. Meanwhile, straps are used to secure the body part being scanned in the correct position throughout the procedure. 

  • Coils. Some MRI scans may require the use of specialised coils. These coils improve the signal-to-noise ratio (i.e., to maximise signal strength over unwanted interferences), thereby optimising the quality and diagnostic accuracy of the images taken by the machine.  

For example, the closed mri head cage (or head coil), resembling an American football helmet, is used during brain or cervical spine (neck bones) scans to obtain the clearest possible images. Other coils designed for specific body parts include knee coils for the knees, extremity coils for imaging the hands, feet, and peripheral joints, and body coils for chest, spine, abdominal, and pelvic scans.

  • Contrast IV. If a contrast agent is to be used for your scan, a nurse or the MRI technologist will insert an intravenous catheter (i.e., an IV line) into a vein in your hand or arm to administer the agent. Contrast agents (or dyes) are chemical substances used to enhance the appearance of certain organs, blood vessels and tissues. It is important to note that contrast agents are not always necessary for producing highly detailed MRI images. Moreover, they are unsafe for pregnant women and people with impaired kidney function.

Scan.com is the UK’s largest imaging network, with over 150 scanning centres nationwide. No matter which MRI machine you prefer, you can book an MRI scan—at a top scanning facility near you for the earliest available appointment date—to investigate your symptoms or screen for abnormalities. No GP referral needed. No waiting lists. No hidden costs. 

If you are not sure which scan to book, consider booking a consultation for £50 to speak with an expert clinician. They’ll call in to discuss your medical history, provide tailored advice on the benefits and risks of the available options, and refer you to the scan that is best suited to your needs. You are not obligated to follow through with this referral, but if you do decide to book your scan with us, we'll help you find the most convenient option.

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