Diagnostic Imaging

     While diagnostic imaging is not currently something physical therapists can order, it is important to know what diagnostic imaging is available and understand how the results relate to treatment. It is important for physical therapists to have an understanding of when a specific diagnostic imaging is used because they may be able to recommend certain imaging when consulting with the patient's primary care physician. Diagnostic imaging can serve as a useful tool when making a diagnosis, however it is important to keep in mind that diagnostic imaging should not replace a careful history and physical exam.
     Standard radiographs are often the initial diagnostic test of choice.  In cases where plain radiographs do not confirm a suspected diagnosis, radionuclide imaging may be required.  CT scan may be necessary in the case of hip dislocation to evaluate the reduction and to rule out the presence of an intrarticular fragment.  MR imaging can also be used as it may be beneficial in early detection of conditions such as avascular necrosis of the femoral head or in the evaluation of soft tissue masses that may be encountered.

Radiograph of the Hip                         

Image 2
A radiograph is defined as an x-ray film that contains an anatomic part of a patient. The production of a radiograph requires 3 things:
  1. the x-ray beam source
  2. the patient
  3. the x-ray film or other image receptor
The important thing to remember is that a radiograph is a snapshot of anatomic structures.

Good for detecting the following conditions:


             Fluoroscopy of the hip

Image 3
Fluoroscopy is similar to a radiograph. The difference between a radiograph and a fluoroscopic image is that the fluoroscopy tube is left on or pulsed rapidly allowing for a live, continuously changing image, rather than a snapshot like the radiograph. Fluoroscopy is commonly used during surgical procedures to assess cardiac catheterization, placement of IV catheters, as well as for orthopedic assessments.


Nuclear Medicine: Bone Scan of the Body                 

Image 4
Nuclear Medical Imaging differs from radiographs by way in which things are diagnosed. Where radiographs diagnosis based on anatomical changes, Nuclear Medical Imaging diagnoses based on physiological or functional changes of the tissue or organ.
Good for detecting the following conditions:

(19, 20)

   Computed Axial Tomography (CAT Scan) of the Hip

Image 5
A CAT scan combines x-rays and computer technology. This form of imaging produces cross-sectional images both horizontally and vertically, of the body. Computed Tomography addresses two of the shortcomings of plain film radiography:
  1. lack of soft tissue contrast
  2. overlap of anatomic structures present in projection images
Good for detecting the following conditions:


Magnetic Resonance Imaging (MRI) of the Hip           

Image 6
MRI is similar to CAT scan in that it produces high-quality, cross-sectional images of anatomical structures. The contrast between the organs and other soft tissues is much better in a MRI than a CAT scan. Where CAT scans can only produce images in a transverse section, a MRI produce good quality images at any orientation as well as superb three-dimensional images. MRI uses a magnetic field and radiofrequency signals to cause the hydrogen nuclei to emit their own signal and thus be converted in to images (DeLee, 2006).


                   Ultrasound of the Hip

Image 7
Ultrasound is unlike other forms of imaging in that it does not use radiation to produce an image. Ultrasound instead uses high-frequency sound waves to produce the image. Medical ultrasound works similarly to sonar in that it sends out high-frequency sound to gain information from the returning "echoes." Ultrasound is the most sensitive tool for confirming a hip joint effusion (although a large effusion can sometimes be suspected from the plain x-ray). However, in most cases, ultrasound cannot differentiate the causes of an effusion. Transient synovitis and septic arthritis cannot be distinguished with certainty and Perthe's disease may also be complicated by an effusion in the acute setting.
Good for detecting:

(6, 19, 21)

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