Principles of Interpretation - Nc State Universityradfileshare.cvm.ncsu.edu/PRINT/2010/Week 1...
Transcript of Principles of Interpretation - Nc State Universityradfileshare.cvm.ncsu.edu/PRINT/2010/Week 1...
Roentgen Signs and Interpretation
Principles
January 11, 2010
Radiographic Opacities
Air Least opaque
FatWaterBoneMetal Most opaque
The absolute blackness or whiteness of any specific opacity is also affected by thickness
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All 5 opacities can
be seen in this
radiograph
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All 5 opacities can
be seen in this
radiograph
Air
Fat Soft tissue or water
Bone
Metal
Opacities are important because…
without different opacities, radiographs would have no information
a lesion’s opacity gives a clue to the abnormality
Radiograph of dog with pneumonia…huh?
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A dog with a huge lipoma of the
thigh
Radiographic Geometry
Radiographs are 2-dimensional Patients are 3-dimensional Some problems of 2D radiographs
• Loss of depth perception
• Superimposition
• Summation shadows
Depth Perception
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Superimposition
A normal structure appears in an unexpected location and is misinterpreted as a lesion
Superimposition
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Cystic calculi?No, nipples
superimposed on bladder.
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Superimposition
Chip Fracture?No, ergot superimposed
on joint.
Ergot
Fibrous tissue under ergot
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R
Lung Nodule?
Superimposition
No, a tick
Summation Sign
A special case of superimposition where overlapping structures create a summationopacity that is not really present in the patient.
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Abdominal mass?
No, summation of kidneys
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Lytic lesion in ischium?
No, overlying anal sac gas
Silhouette Sign
The effacement (loss of visualization) of the border of two structures of the same radiographic opacity that are in contact.
X-RAY BEAM
HEART
LUNG
CORONARY ARTERY
PULMONARY ARTERY
PULMONARY ARTERY
Naming Radiographs
Point of EntrancePoint of ExitUse correct anatomic terminology
Naming Radiographs
DorsopalmarPalmarodorsal
DorsoplantarPlantarodorsal
CraniocaudalCaudocranial
Interpretation Signalment and history Physical examination Is the radiograph normal?
• Hardest call Describing abnormalities
• Roentgen signsWe rarely make a diagnosis from
radiographs
Is It Normal or Not? Reference books Build a
collection…not done Radiograph opposite
limb…not done Experience…difficult Can’t decide …get
help
Roentgen SignsSize
Shape
Number
Location
Margination
OpacityA66208
Roentgen SignsSize
Shape
Number
Location
Margination
Opacity75437
Roentgen SignsSize
Shape
Number
Location
Margination
Opacity66195
Roentgen SignsSize
Shape
Number
Location
Margination
Opacity73874
Summing It Up What is signalment and history
• Could be misleading Compile roentgen signs Formulate a list of possibilities
• D,A,M,N,I,T,V Plan on how to get to the next step
• More imaging• Invasive procedure
Principles of Interpretation
Review SessionJanuary 13, 2010
Be able to point out the 5 radiographic
opacities in the following image
Identify the object in the following image
and, if you can identify it, what
gender is it?
The following cat’s thoracic aorta appears more conspicuous than
the aorta in a normal cat. What could cause this?
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The owner of the following cat reports that the cat was playing with
some pills that had spilled from a container and may have eaten
some. You radiograph the cat’s abdomen. What is your assessment
of the stomach.
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The liver, spleen, kidneys and bladder are not visible
in the following feline abdominal radiograph.
Why?
The opacities in a patient that are created as a result of the overlapping of structures are
called…..
The radiographic principle that leads to the obscuring of
small intestinal serosal margin detail by the
accumulation of peritoneal fluid is the…
Which of the following structures would not be visible in a lateral thoracic
radiograph of a normal dog?
Left coronary artery Left cranial lobe pulmonary artery Caudal vena cava Descending aorta
This dog in the next image became acutely paralyzed.
What do you tell the owner?
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This dog was hit by car and cannot
walk…what diagnosis can be made from
this image?
What roentgen sign(s) is/are illustrated in each
of the following radiographs?
Here is a lesion
What is this? Use
• D• A• M• N• I• T• V
Name the following radiographic projections