Upright (Weight-Bearing) MRI

An upright, or weight-bearing, MRI is a scan performed while you are standing or sitting rather than lying flat. The idea is to image the spine under the everyday load of gravity, in the positions in which symptoms actually occur. Some machines can also scan while you bend forwards or backwards. It is used in selected cases where a person's symptoms clearly depend on posture but a conventional lying-down scan looks normal or does not explain the problem.

The scanner uses the same magnet-and-radio-wave principle as any MRI, but is engineered so that the magnet can image you in an upright position. When you stand, the weight of the upper body loads the discs and joints and the spine settles into its natural standing alignment. This can bring out changes that disappear when you lie down — for example a vertebra that slips further forward on standing, a canal that narrows more under load, or ligaments that buckle inward. These position-dependent changes are the reason the test exists.

Rather than lying in a tunnel, you are scanned sitting or standing in the open front of the machine, which many people find less claustrophobic. You may be asked to hold a position, or sometimes to lean forwards or backwards, and to keep still while each set of images is taken. As with all MRI, it is painless, uses no radiation, and requires the usual metal-safety checks beforehand.

Standard MRI is done lying down, which unloads the spine and can hide problems that only appear when a person is upright — such as certain cases of spondylolisthesis (a slipped vertebra) or "dynamic" spinal stenosis that narrows on standing. Upright MRI can capture these. Its limitation is that these scanners usually run at a lower field strength than a standard machine, so image detail can be lower; it is therefore used to answer a specific postural question rather than as a routine first scan.

• —Royal College of Radiologists — iRefer: Making the Best Use of Clinical Radiology
• —MHRA — Safety Guidelines for Magnetic Resonance Imaging Equipment in Clinical Use
• —British Association of Spine Surgeons (BASS)

This information is for general patient education and is not a substitute for an individual consultation. Always seek personalised advice from a qualified spinal specialist.