Intro To Clinical Imaging Flashcards
What are the strengths of an x-ray
Good at showing things surrounded by gas
Good at showing things surrounded by (white) bone or destroy bone
What are the weaknesses of an x-ray
The abnormality you are trying to see must be very differently dense to the surrounding tissue
How do x-rays distinguish between different structures in the body
Air lets all x-ray pass through
Soft tissues let some x-ray through
Cortical bone lets no x-ray through (hence white)
Are x-rays useful for all tissues
No, especially pathology affecting soft tissues
What are contrast studies
Liquids containing dense elements (iodine) injecting between tissues to give them an outline
What damage can x-ray radiation cause
Damage cell dna leading to mutations which can kill the cell or turn cancerous
Which scan shows 3D structures
CT - can distinguish between tissues of similar density
Why cant radiographs be used to diagnose illness
Produce an image where all structures are superimposed (overlap)
What are the dangers of a CT
Gives large doses of ionising radiation
What is a weakness of a CT
Soft tissues of very similar density cannot be distinguished by a CT
Cannot resolve bone marrow disease
How does an echocardiogram (ultrasound) work
Sound waves
Transmits sound pulses and then listens for reflected sound returning, turned into image
Which type of imagine devices don’t employ ionising radiation
Ultrasound
MRI
What are the advantages of using an MRI
Can show joints and bone marrow disease
Can show all areas of the brain
Why are ultrasounds preferred to an MRI
Whilst an MRI can show more, ultrasound is quick and cheap
What is a weakness of an ultrasound
Obese people have more fat in between the structure being scanned and the skins surface - unclear image
Also unmobile patients
What makes a good ultrasound exam
Good skin (for transducer)
Superficial structures
Slim patient
Ultrasound strengths
High spatial resolution
Imaging muscular skeletal soft tissue structures - tendons and muscles
Do body fluids reflect ultrasound
No - would get no image (unless solid structure was in fluid)
Why can you not see the brain with an ultrasound
Bone blocks US
Gas also blocks US
In an MRI what colour does fluid appear in T1
Black
How does fluid appear in a T2 MRI
Bright
What dangers can occur from an MRI
Frostbite (in unregulated practices)
Deafness
Metallic structures such as pacemakers etc are disturbed
What type of imaging device can allow the interior of joints to be imaged
MRI
