Musculoskeletal Imaging: Technique Selection

TECHNIQUE SELECTION

In general, as in most other organ systems, the radiograph is the initial imaging test after history and physical exami-nation. The selection of subsequent (often more expen-sive) imaging tests depends not only on medical need but also on a variety of other factors, including availability, expense, and the preferences of the radiologist, clinician, and patient.

Trauma

Rely on conventional radiography. When a strongly sus-pected fracture is not identified, you may choose among rep-etition of conventional radiograph in 7 to 10 days, nuclear medicine bone scanning, and MRI. CT may be substituted for MRI if the latter is unavailable or there are contraindica-tions to its use. If a fracture is noticed and more information is needed concerning the location of fragments, CT is useful.

Bone or Soft-Tissue Tumors

For local staging of both bone and soft-tissue neoplasms, MRI is the best technique. When a bone tumor is suspected but is not discovered with conventional radiographs, MRI is a useful secondary screening tool.

Metastatic Tumors

Symptomatic sites suspected of being involved by metastatic neoplasm are best evaluated initially with radiographs. An overall survey for osseous metastases may be performed by nuclear medicine bone scan or by MRI. Conventional radi-ography is then used to evaluate sites of possible tumor involvement. Suspected soft-tissue metastases are best evalu-ated by MRI. PET/CT scans are also useful in staging of many tumors.

Infection

Conventional radiographs should be obtained first for sus-pected osteomyelitis. If these are normal or inconclusive, then MRI, nuclear medicine bone scan, or white blood cell scanning may be helpful. MRI is also useful for detecting the soft-tissue extent of infection and for finding complications including abscesses or necrotic tissue.