What Is the Difference Between an Open MRI & a Stand Up One?

When health care providers need to see inside the human body, today's common methods are through X-ray or MRI technologies. Magnetic resonance imaging (MRI) is a noninvasive diagnostic procedure that achieves very high visualization of body structures in two and three dimensions. Open MRIs are designed to avoid the claustrophobic environment of tunnel MRIs, which require the patient's entire body to be confined within the MRI's magnetic field during the procedure.

Identification

• Traditional tunnel MRIs are long, cylindrical tubes in which the patient is fully inserted, surrounded totally by the walls of the unit. The large magnets usually require a dedicated room within a hospital.

  Open MRIs do not totally encompass the patient's body, but usually lose imaging quality that tunnel MRIs can provide. Open MRIs are more prevalent in imaging centers and freestanding clinics because of their smaller size and lower costs. Stand-up MRIs are essentially open MRIs that allow the patient to stand up through the procedure.

Mechanisms of Action

• MRI scans produce magnetic fields that cause the body's cellular nuclei to resonate in a fashion that radio waves can detect. They are relatively harmless to the patient since they do not use radiation ionization. To produce images, an MRI scan usually takes between 30 and 90 minutes, with the patient remaining motionless.

  In order to obtain clearly defined images, the patient may be give an oral or injected contrast agent to highlight and refine images of targeted anatomical features.

Significance

• Both open and stand-up MRIs avoid the patient's potentially claustrophobic experience with tunnel MRIs. The major characteristic of the stand-up MRI is allowing the patient to bear weight on the body's pathology by simply "standing up," (Ordinary open MRIs typically require the patient to lie down.) This feature of stand-up MRIs is important in obtaining images of the human spine and joints in positions of normal stress. For lower back pain, it is especially useful in determining the underlying causes of pain symptoms, according to a 2008 article in Clinical Radiology.

  Quite often, an upright position is the only position in which the patient's symptoms occur. This is especially true for certain neurological and cardiovascular conditions as well as the gastrointestinal tract and other organs. With stand-up MRI imaging, physicians can examine the function of gravity and position on most of the body's anatomy.

Considerations

• During any MRI procedure, the patient must remove all metal objects. Hip implants, pacemakers and other metal in the patient can cause serious repercussions if hospital personnel are not aware of their presence. Positioners are used to immobilize limbs and music is provided to distract from the loud noise produced by the MRI's magnets. A major advantage for the patient in a stand-up MRI is the ability to watch television during the somewhat lengthy procedure.

  Despite the features of open MRIs, the tunnel MRIs are often preferred by physicians because of the higher image resolution obtained by using their much larger magnets.

Precautions and Warnings

• Instructions from the physicians and technicians should be diligently followed. During an MRI scan, the patient should expect loud, unfamiliar sounds such as hammering and clanking. Avoiding any movement throughout the procedure is extremely important as motion will blur the images being recorded.