Preliminary Diagnosis: Osteoporosis

I. What imaging technique is first-line for this diagnosis

  • DEXA (Dual Energy X-ray absorptiometry)

II. Describe the advantages and disadvantages of this technique for diagnosis of osteoporosis.

  • Most accurate and valuable method available for the diagnosis of osteoporosis and other such conditions. It is one of the best methods to estimate the risk of fracture.

  • Noninvasive procedure

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  • Simple and quick process

  • The amount of radiation used is small

  • Widely available bone densitometry test available for the diagnosis of bone density abnormalities

  • Certain conditions may interfere with the accuracy of test, like spinal deformities or previous spinal surgery, vertebral compression fractures or degenerative diseases such as osteoarthritis, and calcium in the blood vessels that overlie the area being scanned.

III. What are the contraindications for the first-line imaging technique?

  • Pregnancy, although radiation exposure with central DEXA assessments is minimal.

  • Individuals who have recently had gastrointestinal contrast or a nuclear medicine test should wait at least 72 hours to perform a DEXA scan, as these tests can affect the results of the scan.

IV. What alternative imaging techniques are available?

  • Quantitative computed tomography (QCT)

  • Quantitative ultrasonography (QUS)

  • Magnetic resonance Imaging (MRI)

V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of osteoporosis.

Quantitative computed tomography (QCT)
  • The result is a true bone mineral density (BMD) (in milligrams of hydroxyapatite per unit volume) thatis measured only in the bone tissue of interest (trabecular bone); thus it is useful in identifying low BMD in patients with extensive degenerative changes of the spine.

  • The precision and accuracy of the CT method are high.

  • QCT is also used to follow up patients previously diagnosed with osteoporosis or low BMD to determine whether their current treatment is effective in preventing continued BMD decrease.

  • The amount of radiation exposure is higher than DEXA

  • Cost is greater than DEXA

Quantitative Ultrasonography (QUS)
  • Non-ionizing method in which the calcaneus is the measurement site

  • Cost-effective and accurate for identifying patients at risk for osteoporotic fracture

  • Sensitive to age-related changes; thus they may be useful in distinguishing osteoporotic subjects and offer a prospective prediction of fracture risk comparable to that of axial DEXA

  • Potential false negatives and positives

  • Lack of standardization

Magnetic Resonance Imaging
  • Valuable in the assessment of vertebral body fractures, nonspinal insufficiency fractures, bone mass and strength, and bone marrow edema

  • Does not make use of ionizing radiation

  • Because the features of osteoporotic fractures and fractures due to other infiltrative processes overlap, false-positive and false-negative results are possible.

  • Expensive

  • Time consuming

  • Requires significant patient cooperation to minimize motion artifact

VI. What are the contraindications for the alternative imaging techniques?

Quantitative computed tomography (QCT)
  • Contraindicated in pregnant women, especially within the first two trimesters.

Quantitative Ultrasonography (QUS)
  • There are no contraindications.

Magnetic Resonance Imaging
  • Contraindicated in patients with non–MR-compatible metallic hardware or foreign bodies