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Chapter 31

Chapter 31. Imaging Studies in Orthopaedics. Overview. The availability of diagnostic images to physical therapists greatly depends on the practice setting. Outside of the United States military health system, the ordering of imaging studies is not within the scope of physical therapy practice.

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Chapter 31

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  1. Chapter 31 Imaging Studies in Orthopaedics

  2. Overview • The availability of diagnostic images to physical therapists greatly depends on the practice setting. • Outside of the United States military health system, the ordering of imaging studies is not within the scope of physical therapy practice

  3. Imaging Studies • The results from imaging studies should be used in conjunction with other clinical findings • In general, imaging tests have a high sensitivity (few false negatives), but low specificity (high false-positive rate)

  4. Radiology • Conventional (plain film) radiography is generally considered to be the first order diagnostic imaging modality. • X-rays are part of the electromagnetic spectrum and have the ability to penetrate through body tissues of varying densities • Exposure to the x-ray particles causes the film to darken, while those areas of absorption appear lighter on the x-ray film or radiograph • The denser a tissue is, the lighter it appears on the film or radiograph.

  5. Radiology • The following structures are in order of descending density: • Metal • Bone. Bone can have varying densities within the body. For example, cancellous bone is less dense than cortical bone, and will thus appear lighter than the cortical bone • Soft tissue • Water or body fluid • Fat • Air. As air is the least dense material in the body, it absorbs the least amount of x-ray particles, resulting in the darkest portion of the film

  6. Radiology • Plain-film, or conventional, radiographs are relatively inexpensive and give an excellent view of cortical bone • May be more specific than MRI in differentiating potential causes of bony lesions • Not considered sensitive to the early changes associated with tumors, infections, and some fractures

  7. Radiology • When evaluating radiographs, a systematic approach such as the mnemonic ABCS is recommended; • A = Architecture or alignment • B = Bone density • C = Cartilage spaces • S = Soft tissue evaluation

  8. Radiology • A stress radiograph is a procedure using radiographs taken while stress is applied to a joint • Can be helpful in assessing spinal stability • Video fluoroscopy procedures involve the use of x-rays to evaluate the quality and quantity of joint motion

  9. Radiology • Contrast-enhanced radiography procedures involve the use of a contrasting agent to highlight different structures. Examples include: • Arthrography • Angiography

  10. Computed Tomography (CT) • Also known as computerized axial tomography (CAT) and computerized transaxial tomography (CTI). • Uses a fan-like beam of x-rays to provide an almost three-dimensional or tomographic image • Helpful in the examination of acute fractures, aneurysms, infections, hematomas, cysts and tumors

  11. Computed Tomography (CT) • Image quality in CT imaging depends on a variety of factors which are mostly selected by the operator. Two parameters are used to define the image quality of a given system: • Spatial resolution: the ability of the system to distinguish between two closely spaced objects. • Contrast resolution: the ability of the system to discriminate between two adjacent areas with different attenuation values

  12. Computed Tomography (CT) • CT scan provides good visualization of the shape, symmetry, and position of structures by delineating specific areas • This information can be helpful in the examination of acute trauma, aneurysms, infections, hematomas, cysts, and tumors

  13. CT Myelogram • A diagnostic tool that uses radiographic contrast media (dye) to illuminate the spinal canal, cord, and nerve roots during imaging

  14. Magnetic Resonance Imaging (MRI) • MRI images are the result of the interaction of body tissues with electromagnetic forces • Commonly used to assess the central nervous system, and soft tissue injuries

  15. Magnetic Resonance Imaging (MRI) • The advantages of MRI include its excellent tissue contrast, ability to provide cross-sectional images, noninvasive nature, and complete lack of ionizing radiation. MRI provides an excellent view of anatomic and physiologic tissues

  16. Diagnostic Ultrasound • Based on the transmission of sound waves through tissue and the time it takes for the waves to be reflected back to the transducing probe • Currently used to help detect soft tissue injuries, tumors, bone infections, bone mineral density, and arthropathy

  17. Radionuclide Scanning • Involve the diagnostic use of radioactive material or isotopes that are administered orally or intravenously • This test is used to detect particular areas of abnormal metabolic activity within a bone

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