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radiology and ultrasound Flashcards

1
Q

which unit of measure quantifies occupational exposure to electromagnetic radiation

A

Rem (radiation equivalent)
yearly max 5 rem
pregnant/fetus: .5rem/year or .05rem/month

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2
Q

roentgen (R)

A

unit of radiation exposure

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3
Q

Rad

A

radiation absorbed dose/amount of radiation received by individual

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4
Q

Curie (Ci)

A

quantity of radioactive material

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5
Q

describe xrays

A

short wavelength, high frequency ionizing radiation that penetrate matter at the molecular level
-can damage cellular components (DNA/RNA), cause reactive oxidizes species, and predispose someone to cancer

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6
Q

effective barriers between X-rays or gamma rays

A

lead or concrete

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7
Q

very high sensitivity to biological effects of EMR

A

bone marrow
intestinal epithelium
reproductive cells
fetal tissue

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8
Q

high sensitivity to biological effects of EMR

A

optic lens
thyroid epithelium
mucous membranes

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9
Q

medium sensitivity to biological effects of EMR

A

glial cells
liver
lung
pancreas

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10
Q

low sensitivity to biological effects of EMR

A

mature RBC’s, bone, cartilage

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11
Q

3 ways to limit radiation exposure

A

distance (6ft)
duration
shielding

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12
Q

review parts of normal CXR

A
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13
Q

review A part of ABCDEFGHI approach

A

assessment of quality and airway
airway: trachea, carina, mainstem bronchi, ETT
PIER: position, inspiration, exposure, rotation
adequate inspiration on X-ray is determined by ID’ing right hemidiaphragm at 9th or 10th rib counted posteriorly

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14
Q

review B part of ABCDEFGHI approach

A

bones examination for symmetry and fractures. examine for foreign bodies and SQ air

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15
Q

review C part of ABCDEFGHI approach

A

cardiac
normal: width of heart is less then 50% the width of the thorax (PA) and 60% (AP)
PA view most accurate assessment of heart size

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16
Q

ID RA, ascending aorta, aortic arch, pulmonary arteries, LV borders

A
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17
Q

review D part of ABCDEFGHI approach

A

diaphragm
-right is usually higher than left due to liver
-bilateral flattening consistent with chronic COPD or asthma (picture)
-look for air

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18
Q

review E part of ABCDEFGHI approach

A

effusions
-costophrenic angles are formed where chest wall and diaphragm meet. sharp, clearly defined angles are normal while blunted angles signify effusions
-effusions tend to rise higher on sides creating a U shape- also need to verify with a lateral angle

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19
Q

review F part of ABCDEFGHI approach

A

fields, fissures, foreign bodies
-infiltrates, masses, consolidation, PTX, vascular markings
-interstitial pulmonary edema ex LV failure is characterized by peribronchial cuffing and/or linear patterns (Kerley lines)
-kerley A lines are 2-6cm oblique lines in upper lobes, kerley B lines are 1.5-2cm horizontal lines in lung periphery

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20
Q

review G part of ABCDEFGHI approach

A

great vessels and gastric bubble
-size and shape of aorta as well as outline of pulmonary vessels.
-aortic knob (distal aortic arch that becomes descending thoracic aorta)
-gastric bubble is radiolucent region under left hemidiaphragm caused by gas in fundus of stomach

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21
Q

what causes enlargement of aortic knob (4)

A

aortic dissection, valvular insufficiency, PDA, or severe TOF

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22
Q

review H part of ABCDEFGHI approach

A

hila and mediastinum
-hila consist of major pulmonary vessels and bronchi
-eval mediastinum for widening (aortic dissection) or tracheal deviation

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23
Q

review I part of ABCDEFGHI approach

A

impression overall- synthesize findings

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24
Q

what type of appliance is present on this xray

A

PAC and ETT

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25
Q

ID of properly placed ETT on CXR

A

mid trachea about 4-5cm above carina (can use T4-T5 as surrogate and count up 4-5cm from there)

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26
Q

ID of properly placed CVC on CXR

A

distal tip of CVC should be in distal 1/3 of SVC between right atrium and most proximal venous valves. usually 1 inch from end of SC and IJ veins before they join brachiocephalic vein

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27
Q

ID of properly placed PAC on CXR

A

from SCV though RA to pulmonary artery. think of anatomy as you look for placement

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28
Q

ID of properly placed cardiac implantable device on CXR

A

need 2 views (usually PA and lateral) to eval misplaced lead

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29
Q

what’s going on in this CXR

A

single lead coming from pacer with two shocking coils- one in SVC and one in RV

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30
Q

what is the first radiographic sign of p.edema

A

cephalization aka redistribution of vascular markings in upper lung

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31
Q

describe the abnormality occurring in this CXR

A

atelectasis, which features segmental, sub segmental, or lobar opacities with loss of volume and displacement of fissures on affected side
-cannot see anesthesia induced bibasilar atelectasis on CXR

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32
Q

describe the abnormality occurring in this CXR

A

PTX.
-pleural line beyond which no vascular markings are seen (region appears hyper lucent)
-collapsed lung retains general shape of lung
-deep sulcus sign: air collects in anterior inferior thorax adjacent to the diaphragm. abnormal lucency on costophrenic angle of affected side.

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33
Q

describe the abnormality occurring in this CXR

A

tension PTX.
-depression of diaphragm
-flattening of cardiac border
-mediastinal shift to contralateral side with tracheal deviation

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34
Q

cardiogenic pulmonary edema stage 1

A

cephalization always occurs first
p. blood vessels larger in upper lobes than in lower lobes

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35
Q

cardiogenic pulmonary edema stage 2

A

interstitial edema
peribronchial cuffing (donuts)- interstitial edema around bronchial walls
-butterfly pattern around hila
-septal lines:
kerley a lines (oblique lines 2-6cm in upper lobes near hila)
kerley b lines (horizontal lines <2cm long in lung periphery near costophrenic angles

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36
Q

cardiogenic pulmonary edema stage 3

A

alveolar edema
alveolar consolidation
blunted costophrenic angles
rounded LV (increased heart size)

37
Q

3 stages of ARDS

A

stage 1: exudative. diffuse patchy alveolar infiltrates manifest peripherally ~12 hours after initial insult
stage 2: primary alveolar infiltrates with atelectasis and air bronchograms appear after 24-48h
stage 3: complete alveolar consolidation

38
Q

ID the abnormality in the CXR

A

fracture boi

39
Q

compression and rarefaction on sound wave/ultrasound wave

A

compression is peak (high pressure) while rarefaction is trough (low pressure)

40
Q

frequency

A

-measure of pitch
-mesured in hz (cycles/second)
-humans can hear between 20-20,000hz
-ultrasound frequencies range between 1-20million hz (or 1-20Mhz)

41
Q

wavelength

A

distance between 2 points on adjacent cycles
-higher frequency = shorter wavelength

42
Q

amplitude

A

loudness (measured in decibels)
-determined by degree of pressure fluctuations from the displacement of molecules within the medium
-higher amplitude = greater pressure change and louder sound

43
Q

propagation velocity of sound through
air
soft tissue
bone

A

air: 343 m/sec
soft tissue: 1540 m/sec (this is a reference average value)
bone: 3,000-5,000 m/sec

44
Q

what material is used in modern ultrasounds to employ a piezoelectric effect

A

lead zirconate titanate
(if you apply electrical current to pizoelectric material, it emits sound waves and vibrates)

45
Q

what determines the placement of the vertical and horizontal dots on the ultrasound

A

vertical placement is determined by time delay- how long it takes echo to return to transducer
horizontal placement: determined by which piezoelectric crystal receives the returning echo

46
Q

examples of things that usually appear hypo echoic

A

solid organs, skin, adipose, cartilage, muscle itself is hypo echoic but fascial lines appear hyper echoic

47
Q

examples of things that usually appear anechoic

A

vessels, cysts, ascites

48
Q

how to differentiate a tendon versus a nerve

A

nerves can appear honey comb and as you scan up they dont change in size
-tendons become flat and disappear as they connect to muscle

49
Q

what does axial resolution help with

A

beam depth- differentiates structures that exist along the length of the US beam.
-axial resolution is improved by using higher frequency (shorter wavelength)

50
Q

what does lateral resolution help with

A

beam width- ability to differentiate structures that exist in the width of the US beam.
-lateral resolution is improved by positioning sonoanatomy of interest in focal zone

51
Q

what does elevational resolution help with (beam thickness)

A

ability to differentiate structures in thickness of US beam
fixed value determined by transducer

52
Q

ID the 3 zones of the US beam

A

near zone (fresnel zone): region between transducer and focal zone
focal zone: where beam is narrowest (x and y axis) and thinnest (z axis)
far zone (fraunhofer zone): region beyond focal zone

53
Q

describe attenuation and which structures produce the greatest degree of it

A

some of the sound waves never return to the transducer.
-bone > soft tissue > fluid
-greater with higher frequency sound waves than with lower frequency sound waves
-can think of it as the process of absorption, reflection, scatter, refraction

54
Q

absorption

A

-waves are lost to body as heat

55
Q

reflection

A

sound wave bounces off a tissue body of differing acoustic impedance
-applying gel reduces this

56
Q

scatter

A

when US wave encounters something smaller than the US wave.
-causes scatter and signal never returns to transducer
-explains why fluid filled structures appear anechoic

57
Q

refraction

A

bending of US wave that encounters tissue boundary at oblique angle
-concept is called snells law. formula used to calculate refraction of light when passing between two mediums with different refractive indices

58
Q

high frequency transducer
mHz
depth range
when to use

A

> 10mHz
< or = 3cm below skin
when to use: ISB, supraclav, axillary, forearm, wrist, femoral, ankle, superficial blood vessels

59
Q

medium frequency transducer
mHz
depth range
when to use

A

5-10mHz
~3-6cm below skin
when to use: infraclav, popliteal, sciatic, deeper BV’s

60
Q

low frequency transducer
mHz
depth range
when to use

A

<5mHz
> or = 6cm below skin
when to use: lumbar plexus, celiac ganglion, neuraxial block, patients with high BMI

61
Q

liner array transducer
piezoelectric crystal arrangement
image specs
frequency

A

pizoelectric crystals arranged in a linear fashion, flat foot print
image same width as transducer to its geometrically accurate
operate in higher frequencies

62
Q

curvilinear array transducer
piezoelectric crystal arrangement
image specs
frequency

A

piezoelectric crystal arrangement convex, has convex foot print
image specs: fan like
frequency: in lower frequency range

63
Q

phased array transducer
image specs
best used for
frequency

A

narrow in near field and fans out with increasing depth
used when you have a small acoustic window to visualize deep structures like cardiopulmonary imaging between ribs
frequency: in lower frequency range

64
Q

B mode

A

most bedside US procedures use this mode. stands for brightness of pixels on screen. produces real time imaging of sonoanatomy

65
Q

M mode

A

M stands for movement. think of it as time lapse that shows relative movement of structures over time.
y axis represents degree of movement, x axis represents time

66
Q

when to use M mode

A

frequently used in echocardiography, providing useful information about valve integrity, ventricular function, wall thickness, chamber size, aortic root diameter
-also useful for POC like dx of PTX or evaluating fluid responsiveness

67
Q

define the doppler effect and when its used

A

change in perceived frequency of a sound wave when theres relative motion between sounds source and the observer. aka observer will perceive a change in the sounds frequency.
-used to ID vascular structures

68
Q

what determines the degree of doppler shift

A
  1. frequency of US beam
  2. BF velocity.
  3. angle of insonation (shift is greatest if US beam is parallel to flow, shift is zero if US beam is perpendicular to flow. this is because cosine of 90 degrees is 0.)
69
Q

negative versus positive doppler shift

A

remember this is all in relativity so dont assume red = arterial

70
Q

according to standard convention, orientation marker on US should point towards (2)

A

patients’ head (long axis)
patients’ right (short axis)

71
Q

define angle of incidence

A

highest quality image achieved at perpendicular (90 degree) angle

72
Q

when is tilting the transducer helpful

A

optimizing angle of incidence relative to structure you are trying to ID

73
Q

when is rocking the transducer helpful

A

promotes better contact between patient and transducer and helpful for imaging inside narrow acoustic window (rocking is in long axis way)

74
Q

define sliding of transducer

A

maintaining short axis view

75
Q

how to remedy this image

A

more gel, my dude

76
Q

what artifact is this and how do we fix it

A

shadow. adjust scanning plane to find a better acoustic window.

77
Q

what artifact is this and how do we fix it

A

acoustic enhancement (think of it as opposite of shadow).
when US meets fluid filled structure and underlying tissue, difference in acoustic impedance attenuates the brightness in this region.

78
Q

what artifact is this

A

-mirror image. US beam gets trapped between two highly reflective tissues that causes time delay in some returning echoes.
-true anatomy and artifact will be eqidistant from reflector (pleura in this case)

79
Q

define reverberation

A

sound waves bounce between two strong parallel reflecting surfaces.
-see this when imaging pleura or using wide bore needle

80
Q

define bayoneting

A

-occcurs when needle passes through tissue of different acoustic impedance
-since ultrasound machine assumes that sound travels at 1540 m/sec, it fails to account for the fact that each tissue has unique propagating velocity

81
Q

3 standard imaging windows for cardiac exam

A
  1. parasternal
  2. apical
  3. subcostal
82
Q

POCUS cardiac: parasternal long axis view (PLAX)
patient position
transducer position
structures viewed
interpretation
TEE equivalent

A

patient position: left lateral
transducer position: just left of sternum at 3rd or 4th ICS
structures: LA, LV, mitral valve, aortic valve, aorta, pericardium
interpretation: LV function, mitral and aortic valve lesions, pericardial effusions
TEE equivalent: mid esophageal long axis

83
Q

POCUS cardiac: parasternal short axis view (PSAX)
patient position
transducer position
structures viewed
interpretation
TEE equivalent

A

patient position: left lateral
transducer position: just left of sternum at 3rd or 4th ICS but turn transducer 90 degrees clockwise from PLAX view to have marker point towards patients left shoulder
structures viewed: LV + papillary muscles, RV, pericardium
interpretation: LV and RV function, pericardial effusion
TEE equivalent: trans gastric short axis

84
Q

POCUS cardiac: apical 4 chamber (A4CH)
patient position
transducer position
structures viewed
interpretation
TEE equivalent

A

patient position: left lateral
transducer position: PMI. inferolateral to left nipple in men and under inferolateral quadrant of left breast in women. place US orientation mark on patients left side right US beam pointing towards patients right shoulder
structures viewed: RA, RV, LA, LV, mitral valve, aortic valve, pericardium
interpretation: LV and RV function, AV valve lesions, pericardial effusion
TEE equivalent: mid esophageal 4 chamber

85
Q

POCUS cardiac: subcostal 4 chamber (subcostal 4CH)
patient position
transducer position
structures viewed
interpretation
TEE equivalent

A

patient and transducer position: with the patient supine, place transducer midline just inferior to xiphoid process. transducer orientation mark should point to patients left side. may need to apply a lot of pressure
structures viewed: RA, RV, LA, LV, mitral valves, aortic valves, liver
interpretation: LV function, pericardial effusion
TEE equivalent: mid esophageal 4 chamber

86
Q

POCUS cardiac: subcostal IVC
patient position
transducer position
structures viewed
interpretation
TEE equivalent

A

from subcostal 4 chamber view (patient is supine), rotate transducer 90 degrees to tilt beam in posterior direction
structures viewed: IVC, RA, liver
interpretation: volume status. IVC collapse suggests hypovolemia
TEE equivalent: bicaval

87
Q

POCUS view to eval for lung sliding/PTX

A
88
Q

a lines and b lines in lung POCUS

A

a lines: horizontal lines that result from reverberation artifact due to pleura acting as strong reflector
b lines: (comet tails) vertical. can be normal or suggest pathology such as p.edema

89
Q

POCUS: gastric
patient positioning
empty v clears v particulate
how to calculate how much fluid is ok

A

positioning: right lateral decubitus
gastric volume (mL) = 27 + 14.6 x CSA of stomach - [1.28 x age in years]

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