Spine University s Guide to Kinetic MRIs Detect Disc Herniations

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1 Spine University s Guide to Kinetic MRIs Detect Disc Herniations

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3 Introduction Traditionally, doctors use a procedure called magnetic resonance imaging (MRI) to diagnose disc injuries. Kinetic magnetic resonance imaging (KMRI) is designed to have images taken while the patient is in a standing, weight-bearing, natural stance. When the images are taken, the discs are in their usual position, allowing the physicians to see what is really going on with the spine. Anatomy What parts make up the spine? The entire spine is built with vertebrae, or small bones that stack on top of each other. There are 33 vertebrae that form your spinal column. There is a cushion between the vertebrae. It's called an intervertebral disc. These discs are made of connective tissue. Connective tissue is the material that holds the living cells of the body together. Most connective tissue is made of fibers of a material called collagen. These fibers help the disc withstand tension and pressure. The discs provide the cushion that allows you to bend and twist. The disc is made up of two parts. The spongy center is called the nucleus. The nucleus is held in place by the annulus a series of strong ligament rings. The disc acts like a shock absorber as you walk, run, and jump. Causes One of the most common reasons for lower back pain in North America is a problem with the intervertebral discs between the vertebrae. The discs can become compressed or fractured due to problems with the bones. They can become misaligned, or the gel can slip out from between the discs and put pressure on the nerves that lie alongside. This is called a herniated disc, ruptured disc, slipped disc, or bulging disc. Symptoms Lower back pain is one of the most common complaints of pain and causes of disability in developed countries. It s estimated that everyone will experience at least one episode of lower back pain sometime during their life. Lower back pain is also listed as second only to colds and flu as a reason to visit a healthcare professional. Often, acute (sudden onset) or chronic (pain that has been present, either constant or off and on, for more than three or six months) lower back pain cannot be diagnosed. There are a wide variety of patients who are affected with back injuries and back pain. They have been injured or developed the back pain through a wide variety of causes. Physicians have yet to develop a set "one-size fits all" approach to diagnosing, managing, and predicting the outcome. It isn t unusual, however, to find some mild bulging of discs in both the lumbar (lower back) or cervical (neck and extreme upper back) region once people have reached early adulthood, around 20 years old. They may not be aware of it. While the bulging might be found on examination, the patients may be completely without symptoms. Diagnosis Traditionally, doctors use a procedure called magnetic resonance imaging (MRI) to diagnose disc injuries. The MRIs are preferred over x-rays and computed tomography (CT) myelography. To perform a CT myelography, a contrast media, or dye, must be injected into the space round the spinal cord. Images are then taken with the dye circulating around the spinal column, showing where there may be problems. This is an invasive procedure with risks. The advantages of MRIs are 1) no radiation is used, the images are formed by using magnetic fields; 2) MRIs can make images of the soft 3

4 tissues, not just firmer, more dense body parts, like bone; and 3) MRIs are not invasive. That being said, MRIs still do have limitations. According to study findings, only 70 percent of patients who had herniated discs were diagnosed with an MRI, leaving a significant number of patients undiagnosed and, therefore, untreated. MRIs are normally performed with the patients in a recumbent position (lying down). Part of the problem identified with using a standard MRI is that when patients are examined in the lying-down position, this takes stress off the spine and the discs. Disc herniations can appear anywhere around the disc (front, back, sides), and when a patient is lying down, the area where the disc bulge is can be hidden from view. In order to improve MRI findings of disc problems, researchers found success with kinetic MRIs. KMRIs are designed to have images taken while the patient is in a standing, weight-bearing, natural stance. When the images are taken, the discs are in their usual position, allowing the physicians to see what is really going on with the spine. An added benefit is images are then also taken with the patient bending or stretching, giving an even more complete view of the discs. As with all tests and techniques, the kmris needed studies to confirm their effectiveness in helping doctors diagnose herniated discs. One such study looked at over 500 patients who complained of lower back pain. They underwent the kmris and experienced spinal surgeons reviewed the results. After reviewing the images, the surgeons identified several more problems with some discs that would not have been noted if they had been using a standard MRI. Researchers looked at various ways of using the kmri, from neutral views, with the patients standing, to more dynamic views with the patients stretching and bending. When using the extension images, the researchers noted that they found up to almost 20 percent more disc herniations than they would have with a standard, lying-down MRI. Using flexion (bending) MRI views, slightly more than 15 percent of herniations were found compared with the standard MRI. Another study, published in 2005, evaluated the differences between people who were lying down (traditional MRI) compared with upright standing MRI and kinetic MRI. This study found that the kinetic MRI was better at diagnosing abnormalities in the spine. In fact, they found that the standard MRI missed some problems altogether if they were caused by movement. 4

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