Radiology in Arizona

Skeletal Radiography

The section of Skeletal Radiography perform and interprets the following studies and procedures:

• Plain radiographs of bones and joints
• Fluoroscopic-guided joint injections and aspirations for diagnosing and/or treating joint conditions with anesthetics and corticosteroids.
• Bone Mineral Analysis (BMA)

Frequently Asked Questions about Bone Mineral Analysis (BMA) Exams:

Q: What is a Bone Mineral Analysis Exam?
A: A Bone Mineral Analysis (BMA) Exam, is also known as a Bone Mineral Density (BMD) Exam that is performed on Hologic DEXA (Dual Energy X-Ray Absorptiometry) equipment that is identical at the Mayo Clinic and Thunderbird sites. The exam consists of measurement of a small amount of low dose of x-rays passed through a patient’s lumbar spine, one hip and sometimes a forearm. A patient’s BMD value is compared with peak BMD values of a population of patients of similar sex and ethnicity, resulting in a T-score value.

Q: Is a BMA Exam the same as a Bone Scan?
A: No. A bone scan is a Nuclear Medicine Exam, consisting of an injection of a radiopharmaceutical. No injection is required for a BMA Exam.

Q: Why is the left hip examined?
A: Most patients’ left hip is their non-dominant side, allowing for slightly earlier detection of osteoporosis. The right hip is occasionally measured if the left hip is not suitable (eg. prior left hip surgery or fracture).

Q: Why is a forearm sometimes examined?
A: If the hips or lumbar spine are not suitable for measurement, then it may be necessary to examine a forearm.

Q: Why are radiographs of the lumbar spine obtained prior to a BMD Exam?
A: To rule out fracture, help in the choice of which vertebrae and hip are measured, and screen for diseases or conditions which may affect a BMD measurement.

Q: Why not obtain only radiographs of the lumbar spine and hips to assess BMD?
A: Skeletal radiographs are not accurate or precise in assessing BMD, but apparent osteoporosis on radiographs may be a reason for performing a Bone Mineral Analysis Exam.

Q: Why not measure a patient’s heel?
A: The most accurate correlation between measured BMD and osteoporosis is with the lumbar spine and femoral neck. The lumbar spine and femoral neck are also locations where osteoporosis may occur earlier than elsewhere in a patient’s body.

Q: Why not use computed tomography or ultrasound to measure BMD?
A: Computed tomography (CT) for BMD measurement is more expensive and has a comparatively higher radiation dose. The use of ultrasound for monitoring osteoporosis treatment has not been established as a standard of patient care.

Q: How is a significant change in BMD calculated?
A: A change in BMD is statistically significant (95% confidence) if it is larger than 2 x square root x P, where P is the precision ( in g/cm2) of the BMD measurement. P is the value obtained by replicate phantom BMD measurements. 

Q: Who cannot receive a BMA Exam?
A: Patients may not be tested if:

1. undergoing radioactive iodine thyroid therapy.
2. scheduled less than 5 days after Barium procedures.
3. weight is more than 300 lbs.

References

1. Ross, PD, Davis JW, Epstein RS, Wasnich, RD. Pre-existing fractures and bone mass predict vertebral fracture incidence in women. Ann Intern Med. 1991;114(11):919-23.
2. National Osteoporosis foundation, www.nof.org
3. World Health Organization, www.who.int/home-page
4. National Institute of Health, www.osteo.org