MSK Imaging Flashcards
Types of Radiography
X-ray, flouroscopy, digital subtraction angiography, dual energy e-ray absorptiometry, computer tomography
Risk of Chest x-ray
low. 0.3% of yearly exposure
Risk of CT?
3-5 times the amount of yearly exposure
Radiograph color?
White = reflexion and dark is no reflexion (air)
Structure closer to projector on x ray appear…
larger
Pros to Plain film
Pros= Very Fast/Cheap $/Portable (First line)
What is fluoroscopy?
Live action stream of x rays. Iodine dye used to visualize.
What is Digital subtraction angiography?
Iodine based contrast is injected Intravenous
temporarily makes vessels visible to X rays. Bone is subtracted from the image
Cons of Digital subtraction angiography?
Had on kidneys and radiation.
What is Dual energy x-ray absorptiometry? (DEXA)
Two energy levels x ray beams
compare level of bone absorptions
What is DEXA used for?
Indication: Bone density scan when
concerned for osteoporosis and osteopenia
Cons for DEXA?
radiation
What is a CT?
Numerous X rays shots as cross sectional slices
Digital images reassembled by computers
Produces a “3 dimensional” sagittal and transverse
views of the structures
CAN be done with contrast for vasculature/ organ imaging
Pros of CT
Pros: affordable ($$), quick (trauma), 3d image
with good resolution
Cons of CT
Relatively high risk of radiation
–
If used, contrast can damage kidneys
What is a MRI?
Magnetic Resonance Imaging. Uses a powerful magnetic field and radiofrequency waves on
protons abundant in water and fat to generate images
Orientation of MRI
Left side of image is right side of patient
(looking at the patient from their
Indications of MRI
Indications: Excels in visualizing soft tissue structure
(cartilage, tendons, etc) = Best for joint injury. Can find
Pros of MRI
No ionizing radiation
–
Highest resolution , can differentiating soft tissue (i.e.
Cons of MRI
Expensive \$\$$ and slow/ t ime consuming – Difficult for claustrophobic patients – Cannot use in patients with metal implants
Ultrasound resolution is based on …
Lower frequency • more penetration, lower resolution – Higher frequency • less penetration, higher resolution
Color scale of Ultrasound
Produces grey scale image, similar to X ray
Hyperechoic/White Dense , not able to
penetrate Bone, metal
Anechoic/Black Fully penetrates i.e . Air, fluid (
Hypoechoic/Darkish Organs, soft tissue
Pros of Ultrasound
Cheap $, Fast, portable, no ionizing radiation
Cons of Ultrasound
Not always available/user dependent
–
Not able to visual structures behind bone (waves blocked) and
bigger anechoic structures (waves scatter)
What is nuclear medicine?
Used to measure physiology, not anatomy • Radioactive radiotracers injected by IV • Radiotracers will bind on targeted physiologic process • Aggregated radiotracer will produce higher concentration gamma radiation which is visualized by camera
What is Positron Emission Tomography?
Radiotracer is a glucose analog and will
aggregate in areas of most glucose usage
•
Indications: Common way to monitor cancer
as cancerous cells have increase glucose use
