Vertebral fracture identification rounds out osteoporosis Dx

Dr. Harry Genant, emeritus professor of radiology at the University of California, San Francisco and a pioneer in the development of bone density measurement, spoke with Diagnostic Imaging about the increasing availability of bone densitometry tests and the need to standardize vertebral fracture measurement to improve the accuracy of osteoporosis diagnosis as well as patient compliance with therapy.

DI: What is the current status of osteoporosis diagnosis?

Genant: The last decade has witnessed extremely rapid growth in the distribution of bone densitometry equipment. This can be seen in the number of radiologic facilities, specialized physicians, and general-practice physicians who are now engaged in diagnosing the disease. We are reaching a point where there is reasonably good access for many postmenopausal women to bone densitometry tests and equipment. This widespread distribution is being driven by an increasing awareness of the magnitude of the problems of osteoporosis and, secondly, by the approval for reimbursement of bone densitometry tests, particularly for women over 65. Also, there are now very effective treatments for osteoporosis directed at women who have low bone density and vertebral fractures.

We've made a lot of progress at this point, but there is still a substantial segment of the population at risk for the disease or who have osteoporosis and are still not being identified. As a silent epidemic, it's often not at the forefront of the patient's mind. But we have made considerable strides in detecting and treating the disease in recent years.

DI: An October 2004 American Journal of Roentgenology article you coauthored focuses on the importance of diagnosing vertebral fractures in detecting and managing osteoporosis (AJR 2004 Oct;183[4]:949-958). How large a part do vertebral fractures play in osteoporosis diagnosis?

Genant: The identification of vertebral fractures is one of the most important aspects in bringing patients under the care of physicians to receive treatment for the disease. Radiologists have a very important role to play in this area, and that role has perhaps not been fully achieved.

A number of publications have documented that the current practice of radiologic interpretation often does not recognize and/or report adequately the presence of vertebral fractures. Clinicians need to request imaging for the identification of vertebral fractures, particularly for women and/or elderly men who may be at risk. Also, radiologists need to be attentive for the assessment of fractures.

There is a global initiative under the auspices of the International Osteoporosis Foundation (IOF) in conjunction with the European Society for Skeletal Radiologists to increase awareness of the importance of fractures.

DI: How important is it to have a standard method of approaching the diagnosis of these types of fractures?

Genant: In most large clinical trials that have been performed both nationally and internationally in bringing osteoporosis drugs to market, vertebral fracture efficacy has been the primary end point. In the process of developing and performing these studies, some form of standardization of nomenclature was necessary. One standard approach to radiologic interpretation is one we have developed (semiquantitative method of Genant et al). It is an approach that is relatively easily applied and provides a commonality that can be understood across different studies and regions. And many physicians already are familiar with the terminology used for mild, moderate, and severe fractures.

DI: Measurement of bone mineral density at the hip with dual x-ray absorptiometry is currently the gold standard for the diagnosis of osteoporosis using World Health Organization criteria. How do you see this standard evolving in the future?

Genant: I believe that BMD is going to continue to be a very important part of the diagnosis and assessment of osteoporosis, with a focus on DXA for the hip and/or spine. But we need to recognize that the identification of vertebral fractures is also important, because the presence of such fractures substantially increases the risk of future fractures and may require more aggressive therapeutic intervention.

DI: How large a role will MRI and CT play in the future of osteoporosis diagnosis?

Genant: MRI application and CT may be helpful in the differential diagnosis for vertebral fractures. They can also be useful for dating the appearance of vertebral fractures. For example, if the fractures in question are highly symptomatic fractures and there is contemplation of vertebroplasty, MRI can be applied to document this. However, right now, conventional radiograph is the first approach, with MRI and CT used for differential diagnosis.

While there has been a swing back toward quantitative CT in clinical research because it provides more information about the evolution of the disease as well as information about therapeutic response, I think that DXA is and will continue to be the most widely used tool for measuring bone density.

DI: What are the most pressing future issues for osteoporosis diagnosis?

Genant: Even women who are diagnosed with the disease often don't stay on the treatment. We need to develop methods to improve compliance. Conventional radiography and documentation of the presence of fractures can often enhance patient compliance with therapy.

Additionally, there are new drugs in the later stages of development. These may provide for greater convenience to the patient, resulting in greater patient acceptance.

We have to recognize that with an aging population, osteoporosis is a major issue. It deserves to have consistent attention and focus.