Lecture 1- Intro to Radiology Imaging

Question 1

Terminology

CXR

Answer 1

chest xray = chest radiograph = chest plain film

Question 2

Terminology

image

Answer 2

any singular image (doesn’t matter type)

Question 3

Terminology

study/examination

Answer 3

collection of images

Question 4

Terminology

wet reading

Answer 4

archaic term for immediate or “stat” intercreptation

Question 5

Terminology

PACS

Answer 5

Picture Archiving, Communications, and Storage System (the system that archives and stores images for later retrieval)

Question 6

Terminology

Films vs Computed Radiography

Answer 6

• films: printed
• computed: electronic (almost everything now)

Question 7

Radiographs/CT

what are the 5 radiographic densities

Answer 7

1. air (least dense, black)
2. fat
3. water
4. bone
5. metal (most dense, white)

Question 8

Radiographs/CT

differentiate radiolucent and radiopaque

Answer 8

• radiolucent: least dense (air); black
• radiopaque: most dense (bone); white

Question 9

Film Quality

3 factors that affect quality of CXR?

Answer 9

1. penetration
2. inspiration
3. rotation

Question 10

Film Quality

differentiate underpenetrated and overpenetrated

Answer 10

• underpenetrated: too white
• overpenetrated: too black

Question 11

Film Quality

how to know if CXR is penetrated correctly?

Answer 11

you can see the thoracic spine faintly through the heart shadow

Question 12

Film Quality

how to evaluate for rotation

Answer 12

• R & L clavicle heads are equally distant from the spinous process

Question 13

why are 2 views often required for xrays

Answer 13

because they are 2D pictures of 3D objects

Question 14

describe silhouette sign

Answer 14

when 2 structures of the same density are in anatomical contact, their margins cannot be seen on film
* ex: the heart rests on the diaphragm, so you cannot see where one starts and the other ends.

Question 15

describe CTs

Answer 15

• digital image generated by multiple xrays which are generated into a slice of the body
• generated to be axial, coronal, sagittal, and 3D images

Question 16

CT

denser structures have higher what?

measurement

Answer 16

hounsfield units (more white)

Question 17

CT

describe windowing

Answer 17

manipulating images to maximize the display of different densities (ex: bone windowing, soft tissue windowing)

Question 18

CT

why is contrast administered

Answer 18

to increase density differences between tissues

Question 19

CT

describe IV Iodinated contrast

Answer 19

• opacifies tissues and organs w/ high blood flow
• excreted by the kidneys

Question 20

CT

potential adverse effects of iodine contrast

Answer 20

• mild reaction: n/v, itching, hives, irritation at injection site
• rare: severe anaphylaxis, death

Question 21

CT

which patients are at a higher likelihood of a contrast rxn?

3

Answer 21

• asthma
• severe atopy
• hx of prior rxns

Question 22

CT

which renal conditions should contrast be used in caution with?

Answer 22

renal insufficiency (diabetes, multiple myeloma)

Question 23

CT

what tests do you order to clear someone with renal insufficiency for contrast?

Answer 23

• BUN (> 21)
• Creatinine (> 1.5 mg/dL)

Question 24

CT

what to do with patients taking metformin?

Answer 24

stop metformin for 48 hrs after contrast dye due to increased risk of lactic acidosis

Question 25

# CT describe barium contrast

Answer 25

* oral or enema contrast used to visualize GI tract * this is not absorbed by the body

Question 26

# CT contraindication of barium contrast

Answer 26

* suspected bowel perforation * before bowel surgery

Question 27

# CT what is a double contrast study (GI)

Answer 27

air + barium

Question 28

# MRI differentiate T1 and T2 imaging

Answer 28

* water is dark on T1 * water is bright on T2

Question 29

# MRI contraindications

Answer 29

* pregnancy * presence of ferromagnetic object

Question 30

# MRI most common contrast agent for MRI?

Answer 30

gadolinium

Question 31

# MRI contraindications of gadolinium?

Answer 31

* severe renal disease * caution in moderate renal disease due to risk of nephrogenic systemic fibrosis (rare)

Question 32

CT vs MRI

Answer 32

1. CT more readily available, faster, cheaper 2. MRI has better soft tissue contrast, no radiation, no iodinated contrast, but can be problematic for pts with claustrophobia

Question 33

# US advantages | 6

Answer 33

* low cost * tolerable * readily available * safe (no rad) * portable * real time imaging

Question 34

# US disadvantages | 4

Answer 34

* operator skill dependent * more difficult to interpret * not good for bone or lung imaging * may be difficult to see in obese patients

Question 35

# US types of US

Answer 35

1. gray scale (B mode) 2. color doppler (blood flow in vessels) 3. spectral doppler (determines direction, velocity, and acceleration of blood flow in vessels)