The Difference Between Open and Closed MRI Scanners

Open and closed MRI systems have both advantages and disadvantages, with the difference stemming from the shape of the magnet configuration of each. Ultimately, the advisability of using either of these scanners will depend on the needs of the specific patient and the diagnostic goals involved. Patients should discuss the pros and cons of open vs. closed MRI with their physicians, who may also consult MRI specialists as needed.

Open MRI Scanners

In an open MRI machine, the magnets used are usually either resistive electromagnets or permanent magnets with a magnetic field strength of about 0.3 Tesla. These magnets are configured in the form of two large horizontal metal discs. These discs are the two poles of the magnet and the patient is placed between them, with the sides remaining open.

The chief advantage of the open vs. closed MRI is the lack of confinement experienced by the patient. Open MRI can be preferable for claustrophobic patients. It is also optimal for some types of joint studies since it offers a greater freedom of movement. Some patients’ size does not allow them to fit into the closed MRI, making the open MRI the only choice for this type of imaging.

Closed MRI Scanners

The more traditional closed MRI scanner uses a tube-shaped container, around which magnets are placed in a closed circle, creating a field strength of up to 1.5 Tesla. Due to this greater field strength, a closed MRI performs its scans faster than an open one. High field superconducting closed MRI scanners are also able to provide better resolution and thinner slices. In some cases, this capability is essential, while other types of imaging studies are adequately performed at lower resolutions. A high field closed MRI is the only machine that can perform MR myelograms, as well as for certain detection methods for early stroke, cartilage degeneration in the knee and subtle multiple sclerosis plaques.

While some kinds of imaging may only be performed using a closed MRI, in other cases the decision between open vs. closed MRI may take into account the patient’s preferences and specific medical needs. Patients should discuss this issue with their physician and radiologist.