Imaging Flashcards
What is ultrasonography and what is the benefit of this type of imaging?
Ultrasound! Useful because it’s inexpensive, portable, and non-ionizing
How do overlapping structures appear? Contrast front vs back
The overlapped region is more dense so it is more of a solid white. If the more dense object (block) is behind then you will clearly see the boarder of the less dens object (heart). If dense object is in font then the image will be obscured or look like one larger object.
Which position shows a magnification of the heart?
AP view. Most heart images are taken from PA for this reason.
Where do you want the image you’re viewing to be in relation to the plate?
You want the object to be closer to the plate for a more accurate dimension
What is DS angiography and what is a concern with this type of imaging?
DS= Digital Subtraction. You inject the contrast directly into the artery so you have to close puncture after removing catheter.
Hounsfield scale
Scale developed to measure CT density levels
Hounsfield scale: middle gray
Window LEVEL
Hounsfield scale: range of gray
Window WIDTH
All CT numbers below window width display how?
They display as black
All CT numbers above the window width display how?
They display as white
Wide window width is good for?
Imaging bone
Narrow window width is good for?
Soft tissue
CT is not useful for imaging what structure?
The brain
Large drawback to MRI?
Parameters need to be set in advance and cannot be adjusted after the image is produced… not as dynamic as CT scans.
What occurs during T1 weighted MR?
Longitudinal relaxation time. FLUID IS DARK
