MSK Imaging Flashcards
What are the imaging modalities?
Radiography, Magnetic Resonance Imaging, Ultrasound, Nuclear medicine
How many types of X-rays are there?
5
What are the types of X-rays?
Radiograph(plain film), Fluoroscopy, Digital subtraction angiography, DEXA, CT/CAT (computer tomography)
What absorbs X-rays?
High density structures – bone/metal
Structures closer to X-ray projector appear how?
Larger than their actual size
-Single still image for a high density structure
pros = fast, cheap, portable
cons = only 1 perspective obtained
Plain film/radiograph
-constant stream of x-rays to produce a live image
pros = live image, high penetration
cons = increased cancer risk due to many x rays
Fluoroscopy
-Iodine based contrast injected to make vessels visible to x-rays and then the computer subtracts bone from image
pros = allows imaging of blood vessels
cons = contrast is BAD for kidneys
Digital Subtraction Angiography
-Bone density scan when concerned for osteoporosis
pros = bone density measurement
cons = ionizing radiation
DEXA - dual energy x-ray absorbiometry
-Numerous x-rays shot as cross sectional slices assembled via computers to create a high resolution 3D image
pros = 3D, affordable, QUICK
cons = contrast sometimes used, high risk of radiation
CT/CAT scan - computer tomography
What does MRI stand for?
Magnetic Resonance Imaging
Describe the process of an MRI
- Magnetic field aligns protons in body
- Radiofrequency pulse disrupts them and changes alignment
- Radiofrequency stops and the protons realign and release energy as they do so that is captured by the MRI machine for an image
Which 2 modalities take image slices to create a 3D image?
CT scan and MRI
If you are looking at the left side of an MRI image, what side of the patient are you looking at?
Right side
What is MRI great for imaging?
Soft tissue, joints and small fractures
Pros of MRI?
Highest resolution, no ionizing radiation
Cons of MRI?
Expensive and slow, not good for claustrophobic patients and cannot be used with patients who have metal implants
How does ultrasound work?
Uses echolocation; waves travel into body and reflect back to make a single, live, 2D image
If a lower frequency wave is used for ultrasound, what results?
More penetration, lower resolution
If a higher frequency wave is used for ultrasound, what results?
Less penetration, higher resolution
Pros of ultrasound?
Cheap, fast, portable, no ionizing radiation
Cons of ultrasound?
Not able to visualize structures behind bone or bigger anechoic structures because waves are blocked or scatter
Not able to penetrate bone structures, image looks white for ultrasound
Hyperechoic
Fully penetrates structures such as air and fluid to create a black image for ultrasound
Anechoic
Organs and soft tissue create a darkish image for ultrasound
Hypoechoic
What is nuclear medicine used for?
Physiology, not anatomy
What is the process of nuclear medicine?
Radiotracers are injected into the body, they then bind target organs, and emit gamma radiation that is visualized
A common way to monitor cancer, radiotracer is glucose analog
Positron Emission Tomography (PET)
Pros of nuclear medicine?
Targets absorption structures
Cons of nuclear medicine?
Radiotracers produce ionizing radiation
