*Imaging Flashcards
What type of tests are imaging tests?
X-rays (plain radiography, contrast studies e.g. braium enema, IVU, arthrography, CT)
US
MRI
Nuclear medicine
What is used in tayside to store and view digital imaging?
PACS (picture archiving and communications system)
To be seen on an x-ray, what must the pathology be in comparison to the surrounding?
A different density
How is a double contrast image created?
Barium is first put in to line mucosa and then emptied before squeezing in air - makes soft tissue more visible
What is IVU?
X-ray of the urinary tract after an IV injection of iodine
What is arthrogram?
Series of pictures of a joint after a contrast material e.g. iodine has been injected directly into it
What type of scanner tends to be used more often in a paediatric hospital?
Why?
An MRI scanner
X-rays are radiation and can therefore lead to cancerous mutations - as children have a high rate of new cell formation they have the highest risk of tumour formation
What material is used to stop x-rays?
Lead
Why are CT scans better than plain x-rays?
They fire x-rays from all round the body and process them on a computer to form a set of cross-sectional pictures with no superimposition - it has superior contrast resolution compared to a radiograph
Why don’t we just use CT for everything? (3)
Gives a large dose of ionising radiation
Soft tissues of very similar density cannot be distinguished e.g. pelvic organs, muscles and tendons, etc.
CT cannot resolve bone marrow disease
Do US or MRI use ionising radiation?
No
How does US work?
The transducer transmits sound pulses which reflect off objects returning at different times due to distant travelled
An image can then be built up on a computer due to this information
Main imaging for chest/ abdo/ pelvis imaging
What is US especially food for imaging?(5)
MSK soft tissue structures (tendons and muscles)
Gallstones in the gallbladder
Tumours of the bladder
Abnormal fluid collections e.g. pleural effusion, ascites, abscess, cysts
Soft tissue tumours
What are the weaknesses of US?
Bone blocks US (can’t see the brain, spinal canal, inside joint or assess bone marrow)
Gas blocks US so windy patients are difficult assess and gas containing structures like the lungs or bowel
Very fat patients
What does an MRI scanner use to produce the images?
A strong magnetic field created from electrical current passed through coiled metal wire surrounding the bore
Uses this to energise the body’s protons
What must patents remove before entering the MRI machine/
Any ferrous metal e.g. dental plates, ear rings, belts
Can surgical ferrous material e.g. pacemakers, heart valves and missile injuries
What must a patient fill in before having an MRI?
A card safety questionnaire
What must staff do before entering the MRI room?
Wear the appropriate safety equipment e.g. vest
Remove all possible metal items e.g. watch, keys, credit cards, etc.
MRI strengths? (6)
Most complete image of the brain possible
Can accurately assess pelvic organs
Can assess bone marrow abnormality in the absence of bone destruction
Sensitive way to assess acute muscle and tendon tears
Excellent imaging of spinal canal disease
Can image the interior of joint so injuries to cartilage and ligaments can be seen
Weaknesses of MRI?
Expensive can harm some patients claustrophobic take a long time Shows little detail of the lungs
Where do the bronchial arteries branch from?
How many do you have?
The aorta
1 right and 2 left bronchial arteries
How many pulmonary arteries are there?
How many pulmonary veins are there?
2 pulmonary arteries (right and left)
4 pulmonary veins (2 right and 2 left - upper and lower)
What are the 3 parts of the thoracic aorta?
Ascending
Arch
Descending
How many cusps does the aortic valve have?
3
