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Radiology/Imaging > Radiology Grad Class > Flashcards

Radiology Grad Class Flashcards

1
Q

What is the difference between a pixel and a voxel?

A

A pixel is a 2D structure; a voxel incorporates a third dimension (the slice thickness of that tissue).

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2
Q

What is the approximate window level for air?

A

-1000

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3
Q

What is the approximate window level for fat?

A

-100

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4
Q

What is the approximate window level for soft tissue [brain]?

A

+30-40

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5
Q

What is the approximate window level for bone?

A

500-1000

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6
Q

What is pitch?

A

The distance of table movement per rotation

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7
Q

What does changing the pitch from 1 to >1 do to image quality? What about

A

1 - normal

>1 - worse quality (gaps)

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8
Q

What is the relationship between photoelectric effect and atomic number?

A

PE effect is related to the cube of the atomic number

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9
Q

What are three contraindications for IV use of an iodinated contrast agent?

A

Dehydration/hypovolemia
Renal failure (ARF or CRF)
Disruption of BBB

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10
Q

In very general terms, what do T1 and T2 refer to regarding electron behavior?

A

T1 is how long the electrons take to come back up. T2 is related to their spin.

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11
Q

What is the safest position if performing a negative contrast (air) cystogram? Why?

A

Left lateral recumbency. If air embolizes it will get trapped in uppermost part of right ventricle and is less likely to go to lungs.

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12
Q

What is the normal diameter (relative to another anatomic structure) of the small intestine in dogs? Cats?
What is definitive for ileus in dog?

A

Dogs - no more than 2x width of rib
Cats - no more than 2x height of central L4
Dog ileus - 4x width of rib

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13
Q

What is the barium dose for a GI series?

A

5-6 ml/lb

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14
Q

On the “mushroom” view on echo, what is normal L ventricle size relative to R ventricle?

A

L should be 3x the size of R

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15
Q

What is normal fractional shortening for

  • small breed dogs?
  • large breed dogs?
  • cats?
A

small breed: 35-45%
large breed: >25%
cat: 45-55%

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16
Q

What is the normal ratio of aorta to left atrium in dogs?

A

1 : 1.3

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17
Q

What is the normal left atrium diameter in cats?

A

less than or equal to 1.5 cm

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18
Q

What is the limitation of pulsed-wave doppler for echocardiogram?

A

It can’t measure high velocities

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19
Q

What is the normal thickness for septum and left ventric free wall in systole for cats?

A

less than or equal to 0.6 cm

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20
Q

On echo, what is the diagnostic view for diagnosis of PDA?

A

RVOT

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21
Q

What is particulate radiation?

A

Beta articles/electrons

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22
Q

What is electromagnetic radiation?

A

X rays and gamma rays

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23
Q

What is the definition of a Gy?

A

100 J/kg

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24
Q

Give 3 examples of teletherapy?

A

Orthovoltage, Cobalt, Linac

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25
Q

Give 2 examples of brachytherapy?

A

Strontium 90, Iridium 192

26
Q

Give 2 examples of internal radiation

A

I-131, Samarium-153

27
Q

What predominates at higher energy - Compton effect or photoelectric effect?

A

Compton

28
Q

What is the difference between lymphocytes and other cells regarding response to radiation therapy?

A

Lymphocytes experience immediate interphase cell death; other cells have to proceed to mitosis.

29
Q

What is the law of Bergonie and Tribondeau?

A

radiosensitivity is directly related to mitotic activity and inversely related to cell differentiation.

30
Q

By what factor are well-oxygenated cells more sensitive to radiation therapy?

A

2.5 to 3 times more sensitive when well oxygenated

31
Q

In what phase of the cell cycle are cells most sensitive to RT?

A

G2-S transition

32
Q

What percentage of congenital shunts are extrahepatic? What is typical signalment?

A

60% of congenital shunts, tend to be small breeds

33
Q

What percentage of congenital shunts are intrahepatic? What is typical signalment?

A

35% of congenital shunts, tend to be large breeds

34
Q

What percentage of shunts are acquired?

A

20%

35
Q

How is shunt fraction used in scintigraphy for diagnosis of shunts?

A

ROIs are liver and heart

20% is shunt

36
Q

What are the four categories of shunts that are differentiated on scintigraphy, and how do they appear?

A

Splenocaval - looks like a curlie-cue
Azygous - dumps in front of heart
Portocaval - dumps into caudal aspect of heart
Acquired - stays in spleen longer [portal hypertension], then runs caudal and ventral

37
Q

What is the ultrasonographic appearance of the kidney relative to the liver and spleen?

A

hypo to spleen

iso to liver

38
Q

What is normal renal length in cats?

A

3 - 4.3 cm

39
Q

Give 5 differentials for increased renal cortical echogenicity in cats.

A 
FIP
Lymphoma
nephritis
metastatic SCC
fat
40
Q

What causes medullary rim sign?

A

Mineralization of the basement membrane at the corticomedullary junction.

41
Q

Name the 4 layers of the bladder and their appearance on ultrasound

A

mucosa - hypo
submucosa - hyper
muscularis - hypo
serosa - hyper

42
Q

How long after breeding can fetal heartbeats be seen on ultrasound?

A

25 days

43
Q

What are signs of fetal death on ultrasound? Give 4.

A

lack of fetal heartbeat
excessive fluid
excessive gas
lack of expected detail

44
Q

What is standard wall thickness of GB in dogs and cats?

A

Dogs: 2-3 mm
Cats: 1 mm

45
Q

On ultrasound, what causes clean and dirty shadows?

A

Clean - Mineral

Dirty - gas

46
Q

What is normal spleen thickness on ultrasound for cats?

A

1.5 cm)

47
Q

What are three characteristics of splenic nodules that would suggest neoplasia?

A

Complex echotexture
Distortion of capsule
Reactive mesentery

48
Q

What are the layers of the GI tract wall as they appear on ultrasound?

A

lumen-mucosa interface: inner white

mucosa: black (thick)
submucosa: white
muscularis: black
serosa: white

49
Q

What is upper limit of normal for SI wall thickness in dogs? Cats?

A

dogs: 5 mm
cats: 2.1 mm

50
Q

What is normal diameter of common bile duct?

A

no more than 2-4 mm

51
Q

Describe the Salter-Harris fracture patterns

A

I - fracture along physis
II - fracture along physis into metaphysis
III - fracture along physis into epiphysis
IV - fracture from epiphysis into metaphysis (crosses physis)
V - crush fracture along physis

Mneumonic: S   A   L   TE   R
Slip
Above
Lower
Through everything
Rammed
52
Q

What is the Larmor frequency?

A

The radiofrequency transmitted into the patient during MRI; strength is related to the strength of the magnet.

53
Q

What is TR in relation to MRI?

A

Repetition time - the time between one RF pulse and the next.

54
Q

What is TE in relation to MRI?

A

Echo time - the time from the RF pulse until the machine records the signal.

55
Q

What are TR and TE in a T1-weighted image?

A

Short TR and short TE

56
Q

What are TR and TE in a T2-weighted image?

A

long TR and long TE

57
Q

What are TR and TE in a proton density weighted image?

A

long TR and short TE

58
Q

In general, what does a lesion’s presence do to:

  • T1 relaxation time
  • T2 relaxation time
  • number of protons
A

It increases all of them

59
Q

What is the appearance of fat on T1 and T2?

A

bright on T1

moderate on T2

60
Q

What is the appearance of fluid on T1 and T2?

A

dark on T1

bright on T2

61
Q

What is FLAIR good for?

A

It is a T2 weighted image that suppresses CSF, highlighting adjacent lesions

62
Q

What is STIR good for?

A

It is a T2 weighted image that suppresses fat

Radiology/Imaging (3 decks)

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