Diagnostic Imaging Flashcards
What color are dense objects?
Radio-opaque, white
What color are non-dense objects?
Black (transparent), radio-lucent
What are the structures on the grey scale? From black to white in order?
Air>fat>blood>muscle>bone>lead
What is the role of the PT?
-No role in ordering or assessment of radiographic studies
-Vital to appreciate implications of study findings
Why is diagnostic imaging utilized?
-To localize an anatomic problem
-To identify the tissue involved
-To identify the nature of the tissue damage (ex. tendinitis vs tear)
-to direct treatment (don’t do a test if it won’t alter your treatment)
What are the types of imaging?
-X ray
-CT
-MRI
-Ultrasound
-Nuclear imaging
What is X-ray?
Form of electromagnetic radiation
What is the purpose of routine radiography?
Documenting bony defects
What is “visualize the view?”
Need to understand the 3-D object being presented in a 2-D image
How many and what type of views are used for diagnostic radiology for musculoskeletal pathology?
-A minimum of 2 views are required, perpendicular to one another
-Additional oblique views often considered (routine radiography)
What is a common and valuable tool to screen the thoracic cavity?
Standard chest x-ray
What is the gold standard for soft tissue injury?
MRI
What are the advantages of X-rays? Disadvantages?
-Advantages: Quick, inexpensive, Ideal for bony changes
-Disadvantages: Does not show soft tissue changes, radiation exposure (small)
What does CT scan stand for?
Computerized (axial) tomography
What is a CT scan?
-A moving x-ray
-Provides detailed planar images by progressive visual “slices.”
What does “metastasis into bones” mean?
Increased metabolic activity uptakes isotope
What are the advantages of CT?
-Cross sectional images
-Can enhance with contrast
-Better sensitivity than x-ray
-Ok w/ metal
-Fast
What are the disadvantages of CT?
-High radiation exposure
-Less sensitive than MRI
What does MRI stand for?
Magnetic resonance imaging
What is MRI used for?
No radiation involved and ideal for soft tissue contrasts
How does MRI work?
-Applies a powerful magnetic field to the patient
-Detects the rate of magnetization and demagnetization
-Produce “slice” images in any plane
What are the advantages of MRI?
-The grey scale does not apply so any structure can be highlighted
-No radiation exposure involved
-High sensitivity to slight tissue differences
-Can image in several planes
-Can image through bone
What are the disadvantages of MRI?
-Cost
-Time lying still
-Limited tube size
-Can’t use w/ metal
-Can be too sensitive/not specific
-Not good for bone/calcified tissue
What is ultrasound? How does it work?
-Picks up and examines timing and amplitude of reflections for echo, examines frequency change for doppler
-Produces a 2-D image in real time, can be moving
