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42 Cards in this Set
- Front
- Back
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What is contrast? |
Degree of perceptable difference between 2 colour tones |
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What is object contrast? |
The difference in radiographic gray tones between 2 radiographed structures due to physiological differences |
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What is film contrast? |
Ability of an X ray film to produce a degree of image contrast |
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What can decrease image contrast? |
Under or over exposure High KvP Excessive fat |
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How can small amounts of fat be beneficial for contrast? |
Separate organs for less border obliteration, sillouhetting |
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How can gas enhance contrast |
Used as negative contrast medium |
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What is contrast medium? |
A substance applied to patient to enhance the natural contrast of the organ of interest |
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What can you apply negative contrast to? |
Pneumo/capnocytsogram Pneumocolon Pneumogastrogram |
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What are negative contrast medias? |
Gas - air and co2 |
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What is the problem with gas contrast? |
Overdistension, rupture, gas embolism |
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What is a positive contrast media? |
High absorbtion of Xrays, very radiopaque Barium sulphate or iodinated compounds |
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What is the purpose of using positive contrast media? |
Outlining internal surface of hollow organs Organ displacement Filling defects |
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What are the applications of barium sulphate? |
Oral and rectal applications Outline wall and lumen of the GIT Coats mucosa to give detail Binds to toxins |
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What are the properties of barium sulphate? |
Biologically inert, not hypertonic, metabolised or absorbed |
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What are the adverse effects of barium sulphate? |
Aspiration can lead to airway hypoxia Granulomas an adhesion in peritoneal cavity |
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What are the other types of contrast media? |
Iodinated ionic and non ionic contrast media -more expensive |
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What is the problem with ionic contrast media? |
Dissocaites and can create hyperosmolality Higer allergy risk |
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What is the problem with non ionic contrast media |
Does not dissociate but is expensive |
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What can occur due to iodine allergy? |
Renal failure, edema, fomiting, hypotension, seizures |
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What are the applications of iodinated contrast media? |
Intravenous urogram Positive contrast cystography Retrograde urethrogram Angiography Portography Gastrogram Duodenogram |
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What would you see with a filling defect? |
Lucent if less opaque than medium downstream of the efect |
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What is double contrast study? |
Positive and negative contrast media |
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What are the advantages of double contrast studies? |
Mucosal detail and dark background Demonstration of filling defects in positive contrast puddle |
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What are the applications of contrast in CT |
Inflammation Abscesses Cysts Vascular anatomy Vascular filling defects Neoplasia |
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What contrast should be used for MRI |
do not use iodine - gadolinium |
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What would cause increased contrast uptake in MRI? |
Increased vascularity Leaky Vessels BBB disruption |
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What would you use for contrast in ultrasound? |
Agitated saline - bubbles reflect sound and create harmonic wave |
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What are the clinical applications of using contrast ultrasound? |
Portosustemic shunts ECG Perfusion imaging |
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What kinds of peridontal disease are there? |
Gingival retraction Alveolar bone and tooth root lysis |
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What kinds of congenital diseases would you pick up on imaging of the head? |
Hydrocephalus Occipital malformation Occipital dysplasia |
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What would you see when imaging metabolic bone disease? |
General bone demineralization Fibrous tissues hyperplasia |
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What would you see when imaging nasal neoplasia? |
Increased opacity Turbinate destruction Local bone lysis Nasal septum deviation |
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What are the 2 types of rhinitis? |
Destructive and non destructive |
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What would you see with otitis? |
Thickened sclerotic bullae Ear canal mineralisation Larger and inflamed bullae Increased opacity due to fluid |
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What is myelography? |
Contrast medium injected into the subarachnoid space, to see if there is deviation, thinning, splitting of the spinal cord |
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What are the pros of myelography? |
Relatively inexpensive No special equipment needed Nicely outlines SC Localising most SC lesions |
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What are the cons of myelography? |
Invasive, Lots of manpower May be Non diagnostic challenging techically less info than other methods |
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What does the split on a myelogram show? |
Abaxial extradural compression |
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What would you diagnose from doral and ventral thinning on a myelogram |
Extradural compression |
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What is the gold tee sign? |
Intradural extramedullary compression Caused by neoplasia Blockage of passing of the media |
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What would you see with an intramedullary lesion? |
Swollen sc pushing out abaxially |
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What causes intramedullary lesions |
Oedema, haemorrhage, neoplasia, inflammation |
