March 12 , 2007

A Better Way to Image Aching Backs? — The Benefit of Seated or Standing MRI Exam Raises an Interesting Question
By Beth W. Orenstein
Radiology Today
Vol. 8 No. 5 P. 28

Each year, nearly 14 million people consult a physician because they are experiencing back pain. Back pain is the second most common complaint (behind the common cold) that brings patients to the doctor’s office. For 85% of back pain sufferers, the primary site of back pain is the lower back.

For the past 30 years, physicians have relied on MRI to help diagnose the cause of the pain in the lumbar region. Nearly 10 million patients are scanned in an MRI machine for back pain each year.

Conventional MRIs require the patient to lie supine in the scanner. However, their pain may disappear or at least be minimized when they lie flat, says Professor Francis W. Smith, MD, of the Centre for Spinal Research at the University of Aberdeen in Scotland. Smith believes a better way to image patients suffering from lower back pain is to have them sit upright—the position that causes their pain.

“It just always struck me as the better way to image people with lower back pain,” says Smith, who was instrumental in developing MRI technology. The world’s first clinical diagnostic MRI service was started at the Aberdeen Royal Infirmary.

One company, Fonar Corporation in Melville, N.Y., manufactures an open configuration scanner based on a 0.6 Tesla (T) resistive magnet that allows patients to be imaged sitting, standing, or lying down. Smith’s center has been using Fonar’s UPRIGHT Multi-Position MRI since 2003. Its physicians are finding problems in many patients that would otherwise go unrecognized, Smith says. It has conducted a number of comparative studies and found that “in just over 30% of the patients, we find things that are not evident in the recumbent position,” he says.

Smith says imaging back patients in an upright position has greatly benefited its patients because “once you have the correct diagnosis, you’re more than halfway to getting better.” Studies show that early aggressive treatment of back injuries results in quicker recovery and fewer lost work days.

Pressure Points Out Problems
Raymond Damadian, MD, president of Fonar Corporation, explains that the pressure on the anatomy of the lower back is different when lying and standing, and that, in many cases, that difference is measurable enough to change the correct diagnosis. “Conventional MRI machines are not capable of visualizing the full extent of the spine pathology that exists, and often miss the key pathology altogether,” he says.

Some radiologists are skeptical about the UPRIGHT scanner because of the lower strength of its magnetic field. “There is a perception in radiology that all MRI has to be done at high field—ie, over 1.5 Tesla,” Smith says, “because that’s what we’ve been brainwashed into believing.” However, Smith says, because of its unique design, the image quality of the UPRIGHT scanner is excellent. “Having a horizontal magnetic field allows Fonar to use the same receiver coils used at 1.5 Tesla. Therefore, the image quality is exceptionally good.” Also, Smith says, the image quality is more than adequate for alterations in alignment and positions of the discs.

Damadian says that when he shows experienced radiologists images of the brain taken from Fonar’s UPRIGHT scanner and from a 1.5T scanner, they cannot distinguish them. That’s why, he says, “I always say the best image depends not only on the strength of the magnet but also on being able to see the patient’s problem.”

It takes longer to scan a patient in the UPRIGHT, Smith says. “You’re making three examinations and it takes twice as long to do the exam as a conventional MRI would.” But it still is not that long, Smith says.

The UPRIGHT scanner is a walk-in machine. The patient can be scanned in virtually any position. “The patient can lie flat or you can have the patient sit, which is the most common,” Damadian says. An MRI-compatible, motorized patient handling system has been developed for the scanner, which allows for both load-bearing vertical positioning and supine positioning of the patients, he explains.

Taking Advantage of Physics
A beltlike receiver coil is placed around the region of interest. The receiver coil is designed so its axis is perpendicular to the direction of the scanner’s magnetic field. “It is a fundamental fact of physics that optimal signal-to-noise ratios [SNR] are achieved when the axis of the receiver coil is perpendicular to the direction of the scanner’s magnetic field, and there is no signal at all when the receiver coil and magnetic field have the same axis,” Damadian says.

Scans in the UPRIGHT cost a facility roughly the same to provide as with a conventional MRI—approximately $600 to $700. The cost of the UPRIGHT or Fonar STAND-UP scanner is $1.55 million, which is comparable to similar strength magnets from GE Healthcare or Siemens, Damadian says.

Some physicians are concerned about putting their patients in pain while being scanned. Smith says most patients want to discover what is wrong with them so they willingly comply. The scanner is configured so the patient looks directly at a 42-inch flat-screen TV that is 10 to 12 feet in front of them. “They can watch the news or whatever, and that helps take their mind off the pain. As long as it’s not a comedy that would make them laugh and move, it’s fine,” he says. The scanner is open, reducing the claustrophobia some MRI patients experience in MRI tubes.

Interpreting the images from the Fonar system requires no special training. “Any radiologist who is conversant with the anatomy of the spine should have no difficulty making the interpretation,” Smith says.

Damadian says that very often with back pain, conventional imaging studies reveal several possible causes and it can be difficult to determine which problem needs to be treated to provide relief.

Patients with back pain are typically treated first with analgesics and nonsteroidal anti-inflammatory drugs. Manipulative treatments and epidural spinal injections may be tried depending on the problem. Patients who fail to respond to conservative treatment may undergo surgery.

Acronym for Failure
More than 916,000 spine surgeries are performed in the United States each year, Damadian says. “However, the results of those spine surgeries are often less than you would like them to be. In fact, there’s a syndrome, FBSS [Failed Back Surgery Syndrome], which is in the range of 10% to 40%.” Back surgery is the only category that has an acronym, FBSS, dedicated to its failures, Damadian notes.

The major identifiable cause of FBSS is the failure to identify the structural source of the pain correctly, Damadian says. “These failed back surgeries can be tragic.”

However, not all radiologists are convinced of the need for positional MRI for diagnosing back pain.

William Palmer, MD, director of musculoskeletal radiology at Massachusetts General Hospital in Boston, agrees that back pain is often a “great diagnostic quandary” for patients and their physicians. People with back pain often have numerous abnormalities, which requires careful correlation of symptoms with imaging findings, he says.

Many abnormalities—degenerative disc disease, endplate changes, arthritis, etc—will present themselves whether the patient is supine or upright, Palmer says. Some causes of back pain such as herniations may increase slightly in size if the patient is seated, but they still would be evident on conventional MRIs, he says.

Palmer says conventional MRI remains an excellent diagnostic tool for demonstrating anatomical abnormalities of the discs, disc contours, and posterior elements.

More Than Position
Trying to image a person in the exact position that causes the pain could be problematic, he says, because it’s not always possible to reproduce the pain at the time of the scan. “Some patients may have pain in the morning, but not later in the day, or have pain later in the day and not in the morning. Sometimes their pain is related to the physical activity that they do and not necessarily whether they are upright or lying down,” he says.

Palmer says that approximately 10 years ago, a manufacturer sought to reproduce axial load in the spine while someone was lying down with a device that used a harness and straps to crank up the pressure. The system was cumbersome and did not create enough of a benefit to catch on, though it remains available in the marketplace. Also, Palmer says, some patients had a tough time tolerating the pain while being scanned.

Palmer does believe at least one common disease may be detected with greater confidence if the patient is scanned seated. That disease is segmental instability, which usually occurs in older individuals due to the combination of disc dysfunction involving the anterior spinal column, and facet arthritis involving the posterior spinal column, therefore creating an abnormal motion segment that can slip depending on patient position and cause spondylolisthesis and spinal stenosis. People with spinal stenosis have a narrowing in their spinal canal. In segmental instability, spinal stenosis may worsen when the patient is leaning forward, Palmer says, pinching nerves and causing back pain or sciatica.

Palmer says additional scientific studies may show that positional or upright MRI could be used to demonstrate whether or not the degree of narrowing is position-dependent, clinically relevant, or severe enough to require surgical treatment.

Imaging Scoliosis
Damadian says UPRIGHT MRI is also beneficial in diagnosing scoliosis in children—approximately 2% of females and 0.5% of males get scoliosis. Children with scoliosis often receive chest x-rays several times per year. A study by the National Cancer Institute found that as a result of the x-rays, women with scoliosis were nearly twice as likely (90% more) to develop breast cancer as those who did not have scoliosis. “The beauty of UPRIGHT MRI is that you don’t get radiation and you get a much better diagnosis of scoliosis because of the upright weight-bearing posture,” Damadian says.

The one disadvantage is that a Fonar MRI costs substantially more than a chest x-ray. “But we’re working on a high-speed sequence where we expect to do the scan in under 10 minutes and have comparable economics, so all children can have MRI with no danger every year instead of having the risk of getting breast cancer,” he says.

In light of the Americans with Disabilities Act, which was enacted in 1990, the American Medical Association (AMA) has issued guidelines for evaluating the permanent impairment when someone is injured on the job. Back pain is the second-leading cause of work absenteeism. The guidelines state that the “dominant motions at both the lower cervical and entire lumbar spine, where most clinical pathology occurs, are flexion and extension.” Interestingly, Damadian says, “that’s what conventional MRI cannot do. Conventional MRI machines are not capable of visualizing where most of the pathology occurs, according to the AMA.”

When Smith and his colleague, Waseem A. Bashir, MD, presented a study on the best way to sit at RSNA 2006 in November, it received quite a bit of media attention. They used the Fonar UPRIGHT Multi-Position MRI to examine a range of positions, including standing and sitting. Smith hopes to return to RSNA this year with new information as a result of using positional back and joint scanning.

— Beth W. Orenstein is a freelance medical writer and regular contributor to Radiology Today. She writes from her home in Northampton, Pa.