DEXA Bone Density Scan
 

Advanced Imaging Center offers one of the world's most sophisticated DEXA scanners.

DEXA (stands for Dual Energy X-ray Absorptiometry) is the safest and most accurate method to measure Bone Mineral Density, an overall measure of how much calcium there is in the bones.

A low level of BMD below a certain threshold (below 2 standard deviations from peak bone mass) indicates osteoporosis.

DEXA provides low cost, state-of-the-art Bone Densitometry with insignificant radiation, unlike CT or nuclear bone densitometry.

Osteoporosis is a common disorder affecting a large number of adults. In the United States more than 25 million people are afflicted, particularly women. Many suffer disabling fractures of the spine, which is the most common site of involvement. Osteoporosis is believed to be responsible for about 1.3 million fractures annually including more than 500,000 spine, 250,000 hip, and 240,000 wrist fractures.

Up to 30% of elderly people with hip fractures die within 6 months of their injury. The difference in sex distribution in osteoporosis is especially significant as women who are 65 years of age or older represent the fastest growing segment of the population in the United States. The worldwide increase in life expectancy will most likely result in an accompanying rise in the prevalence of osteoporotic fractures of all kinds over the next decades.

During the past decades, osteoporosis, called the "silent epidemic," has gained increased attention. The involvement chiefly of women and the insidious loss of bone manifested primarily as "crush fractures" of the spine, hip and wrist are widely known facts. Public awareness of this disorder also has been heightened by the resulting increase in health care expenditure that is currently estimated to be in excess of 7 billion dollars.

Indications for DEXA:

• Patients receiving long term glucocorticoid therapy.
• Patients with primary asymptomatic hyperparathyroidism
• Patients at high risk for osteoporosis such as amenorrhea, anorexia nervosa or alcoholism
• Patients with atraumatic fractures, disuse atrophy, and similar conditions
• Assessment of early postmenopausal bone loss as an indication to initiate estrogen replacement therapy
• Diagnosis of osteoporosis suspected from radiographic findings or from clinical risk factors
• Serial assessment of bone density, i.e., during treatment for osteoporosis or in anticipation of rapid bone loss

A variety of metabolic disorders such as hyperparathyroidism, renal insufficiency, Cushing's syndrome, and amenorrhea in premenopausal women as well as chronic immobilization and chronic steroid or thyroid therapy are known to influence calcium metabolism and may affect the skeleton adversely. In these cases of secondary osteoporosis, bone density measurements are of particular importance because they may prompt therapeutic decisions such as reduction in medication or surgery.

Bone turnover increases significantly at menopause with a greater increase in bone resorption than bone formation resulting in accelerated loss of bone. One-third to one-half of bone loss in women may be attributable to the loss of ovarian function. Several studies have established the bone mass-preserving effect of estrogen therapy; if begun soon after menopause it reduces the subsequent rate of vertebral fractures by 50%. The benefits derived from estrogen therapy clearly seem to outweigh its adverse effects. However, it is unacceptable for many women and the level of bone mineral density at menopause and the magnitude of subsequent loss are important considerations in assessing the future risk of fracture and a decision to begin prophylaxis can be based on such considerations.

Serial measurement of bone density is accurate, providing guidance for clinical treatment. Measurements every 1-2 years are useful depending on the disease process. Studies have shown large annual loss of bone density from sites rich in trabecular bone in patients receiving high dose steroids. Similarly, large annual gains of bone have been observed in osteoporotic patients receiving treatment with a variety of therapeutic agents such as calcitonin, fluoride, biphosphonates, or parathyroid hormone. Considering the marked effect of some types of intervention, the magnitude of postmenopausal loss of bone, and the continued improvements in measurement precision, serial DEXA bone densitometry is valuable in determining therapeutic efficacy.
 

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