Low bone density is most commonly associated with osteoporosis, an age-related disorder that consists of decreased bone mass and increased susceptibility to fractures. Although osteoporosis is most commonly seen in postmenopausal Caucasian women, about 1.2 million fractures per year are attributed to the condition, and of these fractures, about one-third are compressed fractures of the spine. Lately, doctors are finding that the trend of those diagnosed with low bone density is changing: An increasingly large amount of men, younger women, and even children are being diagnosed with decreased bone mass. Many of those diagnosed with the condition were not fully aware of their susceptibility.

After the first bone fracture, patients have a 20% chance of another occurring within 1 year, leading to a cascade of fractures. Of patients undergoing a hip replacement surgery due to low bone density, 20% will die within 1 year of the surgery. Medical professionals are unanimous in their claims that bone densitometry exams need to gain more exposure to men, women, and children. New technology developments make it easier to detect bone loss in patients that don’t classify as the typical candidate for osteoporosis. This technology allows for patients to be diagnosed and treated in a more efficient manner, thus offsetting the morbidity that results in osteoporosis-related fractures.

Over the next several pages, we’re highlighting the importance of bone densitometry in an effort to increase awareness amongst radiology professionals and the role they play in making patients aware of both the need and the technology available for diagnosing low bone density.

f01a.JPG (10463 bytes) Dr Jannice Aaron remembers back to about 20 years ago, when she was the only clinician in Kentucky performing bone densitometry. “That was before the arrival of DXA [dual-energy X-ray absorptiometry] and reimbursement, and the procedure was much more laborious,” she explains. “Back then, we had to do all the calculations by hand, but now everything is computer-automated.”

Aaron, a neuroradiologist for CT and open MRI, interprets films at five imaging facilities in and around La Grange, Ky. She has seen the necessity of the application grow along with technological advancements over the past 2 decades.

“Back in the 1980s, bone densitometry was a nuclear medicine procedure, almost experimental,” explains Eric von Stetten, PhD, VP and general manager of osteoporosis assessment for Hologic Inc (Bedford, Mass), a developer of bone-densitometry equipment and technology. “When the first machine with an X-ray tube was introduced in 1987, it became a radiology department procedure. Now, with advancements in drug therapies, 50% of bone-densitometry procedures are performed by primary-care providers.”

The 1995 passage by Congress of the Bone Mass Measurement Pact, which paved the way for reimbursement for the procedures, has led to use of the technology in other departments and facilities, such as endocrinology, rheumatology, orthopedics, and women’s health centers.

Increasing Awareness of the Need
As the use of bone mineral density testing becomes more widespread, clinicians become more aware of its importance to their patients’ health. But such awareness still needs to increase among practitioners and patients.

Dr Brad Richmond, director of bone densitometry of the Metabolic Bone Disease and Osteoporosis Clinic at the Cleveland Clinic, says one problem is that primary-care physicians are too busy, which might eliminate any time to consider bone densitometry for a patient. “The doctor will simply treat the patient according to the presenting complaint or symptoms and won’t necessarily be thinking about the need for a screening, because his or her time is so limited,” he explains.

Compounding the problem is the fact that some postmenopausal women can look fit and healthy but actually be osteoporotic. Having patients fill out a screening form on which they can indicate health concerns as well as current and previous problems, Richmond suggests, would be helpful to cue clinicians about a patient’s desire for or the necessity of bone-density screening.

Educating the community needs to be a priority, agrees Matt McKinney, director of radiology at Hamilton Hospital (Webster City, Iowa). “Because [we’re] a small community facility, we don’t have a big budget for educational or marketing activities, but occasionally we will run advertisements locally about scanning services,” he says. “We also host a ‘lunch and learn’ program monthly for practitioners and local residents, and at least once each year, the topic will involve bone health. By offering educational opportunities to the physicians and the community, we hope that some of the awareness and information will trickle down to the patients.”

McKinney also believes that with other health concerns, such as heart disease, at the forefront of health management, bone-loss intervention sometimes is overlooked. “We need to make patients aware that bone loss is more common than they think but that we have the means to combat it with lifestyle changes and medications,” he says. “The earlier we can have patients assessed for risk, the better.”

The Goals of Bone Densitometry
“The real goal is to prevent fracture,” explains Jean Weigert, MD, director of women’s imaging at Mandell and Blau MDs PC, a network of five imaging centers around Hartford, Conn. “But there are three basic reasons to perform bone densitometry. First is to measure bone density, and, thus, the strength of the bone. Is the bone of low mass or osteoporotic? Second, and integral with the first goal, is to get a handle on fracture risk. And third is to monitor patients undergoing therapy for osteoporosis, to determine whether the bone density is stable, increasing, or decreasing.”

Weigert emphasizes how important it is to ensure that the therapy is working properly so that unnecessary side effects can be avoided and new treatments considered if necessary.

The key to determining low bone mass, says Ben Arnold, PhD, president and founder of Image Analysis Inc (Columbia, Ky), is to compare patients’ measurements with those of young, normal subjects. The latter’s bones are measured with various techniques to establish density as a function of age and sex. Most frequently, bone-density measurements in patients are done in the spine and hip, the “hot spots” for earliest detection of osteoporosis and of response to therapy.

Still, one common misconception, Weigert notes, is that men are not at risk for osteoporosis. In fact, just as many fractures occur in men as in women, but they occur earlier in women because of the increased risk after menopause. “Men have larger bones, so they generally are much older at onset of osteoporosis, which occurs usually in the seventh to ninth decades of life,” she says.

The Cleveland Clinic’s Richmond concurs about the serious risk for men. “Men have increased rates of hip fracture as they approach the seventh and eighth decades of life,” he says. “In fact, the resulting mortality is higher than that among women with hip fracture. In addition, 30% of men have low bone mass.”

Consideration of Comorbidities
Physicians and patients alike should not underestimate the importance of considering conditions related to the occurrence of fractures due to osteoporosis, such as changes in self-image, depression, changes in pulmonary and cardiac status, and comorbidities, Richmond explains.

“Because of the amount of morbidity and mortality related to fractures, it is vital to prevent fractures by early identification of low bone density,” he says. “Bone densitometry provides us with lots of useful information that enables us to address issues that will help us manage the patient’s risk, such as by improving balance or instituting an exercise or physical-therapy program.” The technology then becomes a tool for prevention as well.

Just as physicians need to be aware of the effects and expense of conditions that might occur along with fractures, society must have a greater awareness of factors that can have an impact on risk of osteoporosis. For instance, Richmond says, parents and physicians must become proactive and watchful of children’s diets in order to maximize their bone health from an early age.

Technology Face-Off: QCT vs DXA
Although clinicians who rely on bone densitometry for managing their patients’ health agree on the benefits of such measurements, opinions differ on the optimal technology. To some degree, the choice of technology is based on cost considerations.

“At a small facility like ours, it is more cost-efficient and space-efficient to use QCT [quantitative computed tomography],” explains Hamilton Hospital’s McKinney. “The set-up cost of this technology is about one-third of that of DXA and involves just hooking up a personal computer to the CT scanner, instead of installing a large piece of equipment that would need a dedicated space. It is simply a better utilization of space and budget.”

Dr Aaron, who has used DXA but now has QCT systems at all five of her imaging centers, points out some other cost advantages to using QCT. “Our CT technologists can perform QCT with minimal additional training,” she says. “And the procedures are a good way to utilize our existing CT scanners, which is ideal for facilities without an extremely high scanning volume. Even during evenings or weekends, when a physician is not on site, the technologists can be performing these procedures.”

The situation is quite different at the Cleveland Clinic, however, where about 12,000–14,000 bone densitometry procedures are performed system-wide each year. The radiology department relies on 13 DXA densitometers. “We handle up to 1.5 million patient visits per year, so we can’t tie up the CT systems with densitometry,” Richmond explains.

But patient load is not the only reason the clinic uses DXA. “DXA is the gold standard,” he says. “The World Health Organi-zation criteria for diagnosis of osteoporosis are applicable to this technology, but not to QCT, although the latter is fine for following treatment.” Richmond also notes that his facility has been involved in all major research projects in the field since 1986 and has used DXA since 1988. “DXA really has the largest database for reference values as well as the largest research base,” he says.

Mandell and Blau’s Weigert offers a different view. “Central measurements, which are used for assessment of progress, can be done with QCT or DXA,” she says. “But QCT is best because it measures trabecular bone—the metabolically active bone—which loses density first and is the first to respond to medical therapies.” Weigert adds that although she believes both technologies are strong tools and DXA is suitable for many patients, QCT is better suited to measuring in more patients because it is volumetric.

“In addition, for patients who have arthritis or scoliosis or who are obese, fewer artifacts occur with QCT,” she explains. “It would be okay to use DXA for a person of average height and weight who has no bone abnormalities, such as arthritis, but many more patients would be more accurately evaluated with use of QCT.”

Aaron adds, “With QCT, we can see conditions in other organs that we wouldn’t see on a DXA image, such as aortic aneurysms or kidney stones.”

And Image Analysis’ Arnold explains that QCT produces a 3-D image, rather than the 2-D image seen with DXA; therefore, “bone components that you don’t want to measure—such as arthritic changes—can be excluded instead of leading to a misdiagnosis.”

The Cost-Effectiveness Factor
Additional financial considerations can affect the decision of a practice or facility to offer bone densitometry, regardless of the technology used. “Mammography centers, for instance, have been hurt by low reimbursement,” explains Hologic’s von Stetten. “Performing spine imaging and bone-density testing can increase their reimbursement and make the centers more financially viable. The patient population is already there, and now the technology is available, so it’s a natural fit.”

Although bone densitometry is usually a reimbursed procedure, reimbursement is not necessarily a given. “Some insurance companies evaluate claims on a case-by-case basis, while others have set reimbursement policies,” notes Hamilton Hospital’s McKinney. “But they follow the Medicare guidelines, which generally provide coverage if the assessment is postmenopausal.” Because bone-density assessment is much more prevalent among women, Medicare does not yet cover the procedure for men, even though their risk is just as high.

With all the advancements in bone-densitometry technology and increasing recognition of its usefulness and necessity for optimal patient care, experts have just one remaining concern. “We have good technology, good reimbursement, and some very effective therapies available now for osteoporosis,” von Stetten concludes. “It’s all good news. We just need to get the message out better.”

Aubrey C. Patrick is a contributing writer for Medical Imaging.

Osteoporosis Screening: It’s Not Just for Women Anymore
Sally M. exercises regularly, has a healthy diet, is of normal weight, and looks fit. What’s the problem? She might be osteoporotic, and she doesn’t have a clue. According to the National Osteoporosis Foundation, about 55% of all women and men older than 50 years are at risk for osteoporosis, yet a very small fraction of them undergo bone-density testing to establish that risk.

“Although some organizations suggest that women over the age of 65 years, or who are postmenopausal and have one risk factor, should be screened for bone density, the significant genetic component to low bone density should be taken into account,” says Christopher Cann, PhD, CEO and director of research at Mindways Software Inc (San Francisco). “Younger women who are predisposed by family history or who have clinical risk factors, such as amenorrhea or abnormal menstrual cycles, might want to undergo bone-density testing at a younger age, when it is still possible for the density to improve, rather than waiting until they are older and bone loss is already occurring.”

f01b.JPG (16834 bytes)f01b.JPG (16834 bytes)Bone mineral densitometry (BMD) images (top, of the hip) provide physicians with quantitative results that are commonly used for the diagnosis of osteoporosis. Instant Vertebral Assessment (IVA) images (bottom, of the spine) are used to identify fractures, which frequently are the first indication of osteoporosis. Both images were taken with Hologic’s Discovery, a bone densitometer that can provide both BMD and IVA images. The IVA image clearly identifies a fracture, which was confirmed through analysis by Hologic’s Cadfx system.

Dr Jannice Aaron, a neuroradiologist in La Grange, Ky, believes that bone mineral densitometry (BMD) examinations should be ordered periodically along with mammograms, with an initial screening of the spine and hipbone mineral density by age 50. “Osteoporosis is extremely common and disabling among the elderly,” she says, “and [BMD] is an excellent way to determine risk and establish a diagnosis by means of the spine and hip images—and to monitor treatment once it is initiated.”

One of every two women will have a fracture in her lifetime due to osteoporosis, reports Eric von Stetten of Hologic Inc. “It’s really quite a story,” he says. “For years, kyphosis [aka, hunching], which essentially is collapsing of the spine from its own weight, was accepted as an inevitable part of aging—but it’s not. If we can find the first spinal fracture or evidence of low bone mass, then we can do something to prevent this.

“After the first fracture,” von Stetten continues, “there is a 20% chance that another will occur within 1 year, leading to a cascade of fractures.” Another frightening statistic he presents is that 20% of persons undergoing a hip replacement will die within 1 year; yet, in 2002, there were billings for six times as many mammographies as bone densitometries.

“We need to educate the community about bone-density testing and about requesting screening earlier, say around age 45, or as soon as possible after menopause,” states Hamilton Hospital’s Matt McKinney. “It needs to be more at the forefront of health concerns.”

An important consideration is the consequence of findings reported from the Women’s Health Initiative, says Jean Weigert, MD. “Because hormone therapy was linked with an increased risk of cancer, many women are choosing to stop hormone therapy and, thus, are at risk of losing bone density,” she says. What physicians must do now, Weigert emphasizes, is identify these women whose risk has increased and find therapies that will be effective against loss of bone mass.

The key will be to make it simpler for women—and men—to access osteoporosis-screening services. “What we’re seeing now, because of improvements in reimbursement and technology, is more community-centered imaging centers,” says Dr Brad Richmond, director of bone densitometry of the Metabolic Bone Disease and Osteoporosis Clinic at the Cleveland Clinic. “Patients don’t have to travel for miles now to a large hospital in order to undergo bone-density testing; soon it will be available in close proximity to their neighborhoods.”