Chapter 31Chapter 31

Imaging Studies in Imaging Studies in OrthopaedicsOrthopaedics

OverviewOverview

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

Imaging StudiesImaging Studies

The results from imaging studies The results from imaging studies should be used in conjunction should be used in conjunction with other clinical findingswith other clinical findings

In general, imaging tests have a In general, imaging tests have a high sensitivity (few false high sensitivity (few false negatives), but low specificity negatives), but low specificity (high false-positive rate)(high false-positive rate)

RadiologyRadiology

Conventional (plain film) radiography is generally considered to be the first order diagnostic imaging modality.– X-rays are part of the electromagnetic X-rays are part of the electromagnetic

spectrum and have the ability to penetrate spectrum and have the ability to penetrate through body tissues of varying densitiesthrough body tissues of varying densities

– Exposure to the x-ray particles causes the Exposure to the x-ray particles causes the film to darken, while those areas of film to darken, while those areas of absorption appear lighter on the x-ray film absorption appear lighter on the x-ray film or radiographor radiograph

The denser a tissue is, the lighter it appears on The denser a tissue is, the lighter it appears on the film or radiograph. the film or radiograph.

RadiologyRadiology The following structures are in order of The following structures are in order of

descending density:descending density:– MetalMetal– Bone. Bone can have varying densities within the Bone. Bone can have varying densities within the

body. For example, cancellous bone is less dense body. For example, cancellous bone is less dense than cortical bone, and will thus appear lighter than cortical bone, and will thus appear lighter than the cortical bonethan the cortical bone

– Soft tissueSoft tissue– Water or body fluidWater or body fluid– FatFat– Air. As air is the least dense material in the body, Air. As air is the least dense material in the body,

it absorbs the least amount of x-ray particles, it absorbs the least amount of x-ray particles, resulting in the darkest portion of the filmresulting in the darkest portion of the film

RadiologyRadiology

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

RadiologyRadiology

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

RadiologyRadiology

A stress radiograph 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

RadiologyRadiology

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

Computed Computed Tomography (CT)Tomography (CT) Also known as computerized axial Also known as computerized axial

tomography (CAT) and tomography (CAT) and computerized transaxial computerized transaxial tomography (CTI).tomography (CTI).– Uses a fan-like beam of x-rays to Uses a fan-like beam of x-rays to

provide an almost three-dimensional provide an almost three-dimensional or tomographic imageor tomographic image

– Helpful in the examination of acute Helpful in the examination of acute fractures, aneurysms, infections, fractures, aneurysms, infections, hematomas, cysts and tumors hematomas, cysts and tumors

Computed Computed Tomography (CT)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

Computed Computed Tomography (CT)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

CT MyelogramCT Myelogram

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

Magnetic Resonance Magnetic Resonance ImagingImaging (MRI) (MRI)

MRI images are the result of the MRI images are the result of the interaction of body tissues with interaction of body tissues with electromagnetic forceselectromagnetic forces

Commonly used to assess the Commonly used to assess the central nervous system, and soft central nervous system, and soft tissue injuriestissue injuries

Magnetic Resonance Magnetic Resonance ImagingImaging (MRI) (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

Diagnostic UltrasoundDiagnostic Ultrasound

Based on the transmission of sound Based on the transmission of sound waves through tissue and the time it waves through tissue and the time it takes for the waves to be reflected takes for the waves to be reflected back to the transducing probeback to the transducing probe

Currently used to help detect soft Currently used to help detect soft tissue injuries, tumors, bone tissue injuries, tumors, bone infections, bone mineral density, and infections, bone mineral density, and arthropathy arthropathy

Radionuclide ScanningRadionuclide Scanning

Involve the diagnostic use of Involve the diagnostic use of radioactive material or isotopes radioactive material or isotopes that are administered orally or that are administered orally or intravenouslyintravenously

This test is used to detect This test is used to detect particular areas of abnormal particular areas of abnormal metabolic activity within a bonemetabolic activity within a bone