Diagnostic Imaging for Physical Therapists

Diagnostic Imaging for Physical Therapists

Imaging is a very useful resource for musculoskeletal conditions and can be an invaluable tool for physical therapists when used appropriately.  Imaging such as MRI, radiographs, CT scans, and bone scans are prime examples of useful diagnostic mapping that can assist with diagnoses, prognoses, interventions, and assessments of conditions physical therapists' treat.  In many cases diagnostic imaging is under utilized, such as cases where x-rays may identify fractures or bone scans identifying osteoperosis.  There are also many studies that indicate over utilization of imaging, such as x-rays for actue and uncomplicated low back pain.

Magnetic Resonance Imaging (MRI)

An MRI is a map of hydrogen atoms within a body.  Hydrogen atoms are ideal because they have a single proton and a large magnetic moment.  Since approximately 75% of our bodies are made of H₂0, MRI machines are able to take very detailed images of the viewed body region.  The magnetic field created by the magnet causes resonance from each proton in the hydrogen atom.  There are multiple types of MRI based on an image captured at different decay's of signal.  A T1 weighted MRI captures early signal decay.  A T2 weighted MRI captures the late stage of signal decay.

T1 Weighted MRI

• Demonstrates good anatomic structures
  
• H₂0, cortical bone, CSF, and ligaments appears darker
• Fat and meniscal tears appears bright

T2 Weighted MRI

• Demonstrates contrast between normal and abnormal
• H₂0, CSF appears bright

Contra-Indications

• Pacemaker
• Aneurysm clip
• Cochlear implant
• Orbital foreign body 
  

Avoid Projectiles

• IV poles
• Scissors
• Oxygen tanks
• Stethoscopes
• Pens
• Paper clips

Radiography

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Computerized Axial Tomography (CT Scan)

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Bone Scan

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