9/12 Introduction To Medical Imaging - Brauer (Completed)

Question 1

What are the contrasts that can be used with X-ray? How are they administered? 2

Answer 1

Barium sulfate - orally & rectally

Iodine compounds - intravascularly, orally, rectally, vaginally

Question 2

What is the role of barium sulfate as a contrast in X-rays? 2

Answer 2

To study hollow organs (Hernias)

Question 3

What is the role of iodine compounds as a contrast in X-rays? 2

Answer 3

To Study vessels (angiography)

Question 4

What’s happening during Fluoroscopy? Where is the source? 5

Answer 4

Continuous stream of x-rays using a tracer or contrast medium

Source is below the patient

Question 5

How many frames per second is used for coronary artery study using fluoroscopy? 5

Answer 5

15 - 30 frames/second

Question 6

How many frames per second is used for peripheral vascular studies? 5

Answer 6

2 - 3 frames/second

Question 7

What is MDCT? 6

Answer 7

Multi-detector computed tomography

Patient moves through a rotating tube and then a computer can make 3-D renderings

Question 8

What does the Hounsfield Scale measure? 7

Answer 8

Measures the density of a CT

Question 9

What does CT stand for? 7

Answer 9

CT - computed tomography

Question 10

What are the different values for the density of water, air, compact bone, and soft tissue in reference to the Hounsfield Scale? 7

Answer 10

Water –> 0

Air (of the lungs) –> (-1000)

Compact bone –> +3095

Soft tissue –> -100 - +100

Question 11

What is a wide window good for in CT imaging? 7

Answer 11

Good for imaging bone

Question 12

What is a narrow window width good for in CT imaging? 7

Answer 12

Good for soft tissue imaging

Question 13

What are the benefits of CT? 8

Answer 13

Fast imaging

Some motion ok

Good resolution, gray scale can be adjusted on viewing screen

Widely available and cheap

Question 14

What are the disadvantages to using CT? 8

Answer 14

Uses ionizing radiation

Contrast requires renal function eval

Iodine allergies w/ some patients

Question 15

How does MRI work? 9

Answer 15

Patient is put in a magnetic field to align the spins of their atoms within all their tissue

A radio pulse is sent into the body which momentarily knocks the spins out of alignment

The atoms immediately re-align themselves and emit an energy as they do so

The energy changes for different tissue types that contain different varieties and concentrations of atoms

Imaging is received on a coil and sent to a computer

Question 16

What are the contrast agents used in MRI? 9

Answer 16

Intravenous gadolinium

Oral Agents (juice, water)

Question 17

What will appear Dark and Bright on a T1-weighted image? 10

Answer 17

Dark:
Tumor, inflammation,
infection,hemorrhage

Bright:
Fat, melanin, subacute hemorrhage, protein-rich fluid

Question 18

What will appear dark and bright on a T2-weighted image? 10

Answer 18

Dark:
Calcification, fibrous tissue, protein-rich fluid

Bright:
Tumor, inflammation, infection, subdue all collection, edema (water)

Question 19

What are the advantages of MRI? 11

Answer 19

No ionizing radiation

Better for soft tissue than CT

Very versatile (can view everything or nothing)

Question 20

What are the disadvantages of MRI? 11

Answer 20

Data collection takes a long time

More costly than with CT

Only specific data is collected (wide range collected with CT)

Loud/hot/claustrophobic

No metal

Question 21

Quiz yourself on CT vs MRI. What is the contrast that was used? 12

Answer 21

Open lecture

Question 22

How is nuclear medicine chiefly different from CT and MRI? 13

Answer 22

Measures physiological process instead of anatomy

Question 23

What is Digital Subtraction (DS) Angriography? 16

Answer 23

X-rays viewed in realtime

X-rays taken before contrast then with contrast and then bone and other tissue as are digitally subtracted out

Question 24

What is a downside of DS? 16

Answer 24

You have to inject contrast using an IV

Question 25

Why would you use volume-rendering algorithms for CT? 17

Answer 25

To get better depth perception within an image

Question 26

During an Angiography using MRI how is a 3D perspective achieved 17

Answer 26

Using an MRI this can only be achieved by rotating the view

Question 27

What is Functional Magnetic Resonance Imaging (fMRI) used for? 18

Answer 27

Detects changes in blood oxygenation and flow

Used to produce activation maps of the brain

Question 28

How is it possible to use fMRI on hemoglobin? 18

Answer 28

Hemoglobin is:
diamagnetic when oxygenated
Paramagnetic when deoxygenated

Question 29

Which methods use X-ray for image production?

Answer 29

Flouroscopy

CT

Nuclear medicine can be used in addition to CT

Question 30

What’s the difference between AP and PA film radiograph?

Answer 30

PA (posterioranterior)
Film>front>back> xray tube
6ft distance
Pt. stands

AP (anteriorposterior)
Film>back>front>xray tube
3 ft distance
pt supine
enlarged heart and mediastinum (NOT PREFERRED)

Question 31

What’s the difference between flouroscopy and X-ray?

Answer 31

Both use X-rays, but X-ray alone is a single image w/ pt. sitting or standing. Fluoroscopy usually has the pt. lying and numerous images are taken each second

Question 32

When would fluoroscopy be preferred over X-ray?

Answer 32

for vascular or coronary artery studies

Question 33

How does CT build on plain film? How is a CT usually read? 6

Answer 33

CT’s builds a bunch of slices starting from the superior aspect of the pt. The computer allows for sagital or coronal views to be constructed

CTs are usually read transversely from cephalic to caudal

Question 34

How does the Hounsfield Scale utilize Grey Scale? 7

Answer 34

Hounsfield scale uses series of greys, monitors only show 256 levels of grey therefore the “window” is adjusted to see different tissue