DIAGNOSTIC IMAGING - Image Interpretation Flashcards
This deck will include revision on normal structures on radiographs as well as the steps for interpreting radiographs
How would you describe the opacity of metal on a radiograph?
Brilliant white
How would you describe the opacity of bone on a radiograph?
White
How would you describe the opacity of soft tissue/fluid on a radiograph?
Soft gray
How would you describe the opacity of fat on a radiograph?
Dark gray
How would you describe the opacity of gas on a radiograph?
Black
Identify the anatomical structures on this normal lateral radiograph of the canine abdomen
Identify the anatomical structures on this normal lateral radiograph of the feline abdomen
Identify the anatomical structures on this normal ventrodorsal radiograph of the feline abdomen
How does the appearance of the stomach vary between right and left lateral recumbency?
When the patient in lying in right lateral recumbency, any gas in the stomach will rise to the fundus. However, in left lateral recumbency, any gas in the stomach will move to the pylorus
How can you tell the difference between a left and right lateral radiograph of the thorax?
The crura of the diaphragm appear to be running in parallel in the right lateral view of the thorax while the crura of the diaphragm appear to be diverging in the left lateral view of the thorax, forming a ‘y’ shape
How can you tell the difference between a ventrodorsal and dorsoventral radiograph of the thorax?
For ventrodorsal views of the thorax, the patient is in dorsal recumbency which causes the apex of the heart to fall away from the sternum resulting in the heart appearing longer and narrower. For dorsoventral views, the patient is in sternal recumbency so the heart remains in it’s normal position and therefore is more oval shaped
Identify the following features on this normal right lateral radiograph of the thorax
Identify the specific heart chambers on this normal ventrodorsal radiograph of the thorax
What size should a normal heart appear on a radiograph of a dog?
2/3 height of thorax
1/2-2/3 width of thorax
Take up 3-3.5 intercostal spaces
What size should a normal heart appear on a radiograph of a cat?
2/3 height of thorax
1/2-2/3 width of thorax
Take up 2-3 intercostal spaces
Identify the lungfields on this normal right lateral radiograph of the thorax
Identify the lungfields on this normal ventrodorsal radiograph of the thorax
What are the three stages used to approach image interpretation?
Recognition
Report
Interpretation
Describe the recognition stage of image interpretation
During the recognition step of image interpretation you should carry out a systematic seach of the entire image. You can do this through assessing each individual body system or through assessing the image area by area (i.e. left to right)
Describe the report stage of image interpretation
During the report stage of image interpretation you should identify any abnormalities and describe them
What are the seven Roentgen signs that can be used to guide your description of any abnormalities identified during the report stage of image interpretation?
Size
Shape/margin
Number (of normal stuctures, number of lesions)
Position/location
Opacity/echogenicity
Internal structure
Function
Describe the interpretation stage of image interpretation
During the interpretation stage of image interpretation you should generate a structured list of differential diagnoses with any differentials that explain all of the abnormalities identified ranked higher on the list
Describe the pneumonic that can be used to help construct a differential diagnoses list
Vascular
Inflammation, Infection
Trauma
Anomaly (congeital)
Metabolic
Idiopathic, Iatrogenic
Neoplasia, Nutritional
Degenerative
What are the six components that should be included on an imaging report?
- Patient and study details
- Image quality
- Description of image findings
- Summary or major abnormalities annd a differentials list
- Refined differentials list incorporating other factors (i.e. history, clinical exam, bloods)
- Plan further investigations to get a definitive diagnosis or treatment plan based on your findings
What are the three most common errors in image interpretation?
Search errors
Judgement errors
Analysis errors
What are some of the common search errors that you should be aware of for future clinical practice?
Interpreting the lesion as normal
Not assessing the entire image
Getting distracted by obvious lesions
Not noticing the absence of a normal structure
What are some of the common judgement errors that you should be aware of for future clinical practice?
- Not considering appropriate differentials due to preconceived ideas as to what the diagnosis will be
- Not reconsidering differentials when presented with new evidence
- Not recognising breed/species variations
What are some of the common analysis errors that you should be aware of for future clinical practice?
Generation of incorrect or incomplete differentials Inappropriate further investigations
What are the three factors you should look at when assessing radiograph quality?
- Is the radiograph identified (owner and animal information), dated and labelled (L/R marker)?
- Are the exposure factors satisfactory (background, tissue contrast)?
- Are the animal and the machine positioned correctly?
What are the two circuits of electricity required to take an X-ray?
Milliamperes (mA)
Kilovolts (kV)
What is controlled by the milliamperes-seconds (mAs) settings in regards to the primary x-ray beam?
mAs settings determine the quantity of x-ray photons produced
How does decreased milliamperes-seconds (mAs) impact the quality of a radiograph image?
Decreased mAs results in the radiograph having a pale background
What indicates that the mAs settings are correct in radiography?
Background blackening outside of the collimation area indicates that there are enough photons being produced and thus the mAs settings are correct
What is controlled by the kilovoltage (kV) settings in regards to the primary x-ray beam?
kV settings determine the energy of the x-ray photons as they leave the x-ray tube and thus determine the penetration of the x-ray photons
How does increased kilovoltage (kV) impact the quality of a radiograph image?
Increased kilovoltage (kV) causes the radiograph image to be overexposed
How does decreased kilovoltage (kV) impact the quality of a radiograph image?
Decreased kilovolts (kV) decreases the contrast between the different tissue types on the radiograph
What indicates that the kV settings are correct in radiography?
Contrast between the tissue types on a radiograph indicates that there is optimal photon penetration and thus the kV settings are correct
How can the quality of a radiograph be affected when the area of interest is not in the centre of the x-ray beam?
This can cause geometric distortion
How can the quality of a radiograph be affected when the animal is incorrectly positioned and the area of interest has been obscured?
This can mask lesions or can result in normal structures appearing abnormal
How can the quality of a radiograph be affected by rotation of the animal?
This can result in normal structures appearing abnormal
How can the quality of a radiograph be affected by a movement blur?
A movement blur can mask subtle lesions
