Neurorad Anatomy

Question 1

CT

• Shape of machine?
• How is an image produced?
• What “windows” are used for the image?
• What can enhance imaging?
• Speed, availability, expense?

Answer 1

• Circular gantry (donut)
• X-rays
  
  • Ionizing radiation
• Axial scan
  
  • Coronal & sagittal reformats
• Iodinated contrast
• Fast, available, expensive

Question 2

MRI

• Shape of machine?
• How is an image produced?
• What “windows” are used for imaging?
• What can enhance imaging?
• Speed, availability, and expense?
• What are the drawbacks?

Answer 2

• Cylindrical magnet (coffin)
• Strong magnetic field, radio waves
• Multiplanar images
• Gadolinium contrast
• Slower (ptmotion), less available, really expensive
• Drawbacks:
  
  • safety issues with metal
  • compatibility with sick patients

Question 3

What is the difference in a how a CT scan is conducted, compared to an MRI?

Answer 3

• CT
  
  • Scan once (maybe twice if giving IV contrast)
  • View images using different “windows” (brightness and contrast settings)
    
    • Brain, bone, soft tissue, lung….
• MRI
  
  • Scan several times (3 to 8+)
    
    • Multiple planes
    • Different “pulse sequences”: T1-weighted, FLAIR, etc.
  • View each image set with only one window

Question 4

What are the strengths of a CT scan?

Answer 4

1. Bone (cortex)
2. Acute hemorrhage
3. Trauma
4. Fluid (e.g., CSF)
5. +/-soft tissue

Question 5

What are the strengths of an MRI?

Answer 5

1. Soft tissues (including bone marrow)
2. Contrast enhancement

Question 6

What appears brighter on CT?

Answer 6

from brightest ⇒ bright

1. Bone (or any metal)
2. Hemorrhage
3. Gray Matter > White Matter (brain)

Question 7

What appears darker on CT?

Answer 7

from darker ⇒ darkest

1. CSF
2. Fat
3. Air

Question 8

What appears brighter on MRI –T1WI?

Answer 8

from brightest ⇒ bright

1. Fat
2. White Matter > Gray Matter (brain)

Question 9

What appears darker on MRI –T1WI?

Answer 9

from darker ⇒ darkest

1. CSF
2. Air, cortical bone (no free water protons)

Question 10

What appears brighter on MRI –T2WI?

Answer 10

from brightest ⇒ bright

1. CSF
2. Fat
3. Gray Matter > White Matter (brain)

Question 11

What appears darker on MRI –T2WI?

Answer 11

from darker ⇒ darkest

• Air, cortical bone

Question 12

What is totally and completely confusing to evaluate on MRI?

Answer 12

hemorrhage

Question 13

Which of the MRI image scans is the best for brain anatomy?

Answer 13

MRI - FLAIR

Question 14

Describe what is seen in this image:

Answer 14

• Bright part of the lesion ⇒ hemorrhage
• Darker part of the lesion ⇒ edema

Question 15

• What kind of images are these?
• What is the brightest part of the image?

Answer 15

• CT scans
• Brightest part: Bone

Question 16

• What type of images are these?
• What is the brightest part of this image?

Answer 16

• MRI-T2WI
• Brightest part: CSF, fat