Conventional imaging of the pediatric spine has long been a challenge because of the well-documented cancer risk related to radiation exposures, which are cumulative over a lifetime.
Management of scoliosis in children typically entails repeated scans of the spine multiple times a year. This possibly exposes the youngest patients to as many as 20 imaging sessions throughout treatment. Clinicians and parents are therefore urgently looking for new imaging options.
Mayo Clinic orthopedics in Rochester, Minn., now uses the low-dose, three-dimensional (3-D), head-to-toe imaging option of the EOS technology for its pediatric spine patients. Mayo Clinic orthopedic specialists have always aimed for using the lowest possible radiation dose in pediatric radiographs.
Data show that EOS supports this goal. A 2010 study in the journal Spine of 50 teenage scoliosis patients compared images from EOS with standard computed radiography (CR). Patients underwent both EOS and CR scans 15 minutes apart, then had their radiation skin dose levels monitored in 13 locations. Results showed EOS had superior image quality and six to nine times less radiation entrance dose than did the CR system.
EOS reduces the amount of radiation a child receives because it is more efficient at capturing radiation. Mayo is among a small number of advanced orthopedic centers to offer EOS in the U.S. "The EOS technology provides accurate and reproducible 3-D modeling of spine deformity, giving us a tool to achieve a more precise understanding of spinal deformity, which until now has been very difficult to obtain without significant radiation exposure for patients," explains Anthony A. Stans, M.D., a Mayo Clinic orthopedic surgeon who specializes in pediatric surgery. A major EOS strength is the enhanced detail of its visualizations.
This new level of visual detail improves understanding of spinal pathology, aids diagnosis and helps evaluate treatment strategies. With EOS data, physicians can conduct more accurate spinal deformity assessments pre-operatively, and then critically review results post-operatively to determine the effectiveness of a given intervention, compare outcomes and possibly revise approaches if data suggest it is warranted.
Developed in France, the EOS device has been used in Europe for approximately a decade. The Food and Drug Administration first approved EOS technology for imaging the spine of pediatric patients in 2010 and for use in the leg in early 2011. Using two perpendicular X-ray beams, the EOS system simultaneously captures two orthogonal X-ray images when the patient is standing in an upright, weight-bearing position. Standard two-dimensional images are adequate for routine use, but when indicated, EOS computer software permits rendering of a 3-D representation from the two planar images. Prior to EOS, physicians could obtain 3-D images only by using computerized tomography, which carries a significant radiation burden.
Dr. Stans' Mayo colleague, orthopedic surgeon Amy L. McIntosh, M.D., believes this advance will help specialists think about spinal deformity differently and lead to changes in practice. Says Dr. McIntosh: "We will be able to compare pre- and postoperative images from EOS with pre- and postoperative images of the past and see a level of detail that was previously missing. As a result, the goals and methods of our practice in the future may change."
Mayo Clinic physicians are also beginning to use EOS for lower extremity imaging. "As with the spine, this application will likely improve our understanding and treatment of lower extremity deformity," she notes. While early results generate cautious enthusiasm for EOS, the Mayo team notes that more data and clinical experience are needed to fully assess its contributions.
Advances at Mayo Clinic Department of Orthopedic Surgery in the management of spinal deformity are fueling the growth and development of its collaborative, state-of-the-art spinal deformity center of excellence. Care for spinal deformity is available to patients across the age spectrum, from infantile scoliosis to complex congenital cases and revision surgery.
Highlights of this practice include:
These developments open exciting opportunities to optimize and further individualize patient care. Notes Mayo pediatric orthopedic specialist, A. Noelle Larson, M.D.: "The addition of new technology such as EOS and a center for excellence in spine helps us provide the highest level of care for each patient, to better understand both the 3-D nature of the deformity and how it impacts other organ systems. Historic treatments for small children with severe deformity included fusion surgery, which restricted pulmonary growth. We have a new appreciation of the importance of preserving spinal growth while restoring coronal and sagittal plane alignment. A multidisciplinary approach with collaboration with pulmonology and nutrition is essential to providing safe and effective treatment for growing children with severe deformity."
Deschenes S, et al. Diagnostic imaging of spinal deformities: Reducing patients radiation dose with a new slot-scanning X-ray imager. Spine. 2010:35;989.