8/9/16 Imaging - Willett

Question 1

x ray

• mechanism
• common uses
• utility
• toxicity

Answer 1

• 2D, differentiate air/fat/fluid_solid organ/bone
• toxicity: radiation, minimal
• common for chest, abd, bone
• problem: all organ/fluid density looks similar

Question 2

ultrasound

• mechanism
• common uses
• utility
• toxicity

Answer 2

• 2D, sound wave reflectio
• toxicity: none
• pregnancy, heart, gallbladder
• problem: areas with bone (brain) or lots of air (lungs/abd) can be hard to visualize
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Question 3

angiography

• mechanism
• common uses
• utility
• toxicity

Answer 3

• xray with intravasc contrast; 2D or 3D
• differentiates blood vessel or rupture from surrounding tissues
• toxicity: radiation (higher bc youre taking multiple frames), contrast (nephropathy, allergy), vessel puncture
• common uses : atherosclerosis, bleeding (sometimes interventional)

Question 4

CT +/- contrast

• mechanism
• common uses
• utility
• toxicity

Answer 4

• 3D, xray
• differentiates tissues of diff Hounsfield units (more sensitive than xray)
• toxicity: radiation (high), contrast
• common for trauma, brain, tumors

Question 5

nuclear medicine

• mechanism
• common uses
• utility
• toxicity

Answer 5

• administration of radiation-emitting material and scanning for emission, 2D or 3D
• differentiates tissues with more/less uptake
• toxicity: radiation (usually less than CT)
• common for myocardium, pulmo embolism, cancer/infl

Question 6

MRI

• mechanism
• common uses
• utility
• toxicity

Answer 6

• 3D
• differentiates tissues by water content, arrangement
• gadolinium highlights areas of infl (can also use for angiogram)
• toxicity: mostly none; metal could heat; gadolinium can rarely cause permanent systemic sclerosis (renal)
• common for brain, spinal cord

Question 7

influences on radiation risk

Answer 7

• age (young more at risk than old)
• gender (breast is v radio-sensitive)
• site of radiation - what was imaged?
• underlying risk (ex. BRCA)

Question 8

populations at higher risk from imaging

Answer 8

young

female (breasts)

pregnant

renal dysfx

Question 9

“incidentalomas”

why a problem?

general principles

Answer 9

when imaging studies turn up a finding that has nothing to do with why the test was ordered in the first place

problem because…often involves followup → more radiation and/or more invasive procedure :(

• sn tends to correlate negatively with sp
  
  • finer the test, more liable you are to see something!
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