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Clin D III > Dartmouth Introduction to Imaging > Flashcards

Dartmouth Introduction to Imaging Flashcards

1
Q

Radiographs

xrays are discrete quantities of what?

A

electromagnetic radiation that are produced outside the nucleus of an atom

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2
Q

Radiographs

what are xrays produced via?

A

in a generator by the interaction of an electron beam

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3
Q

Radiographs

describe screen film radiography

A

the cassette contains film and intensifying screens. when the xrays hit the film, a photochemical rxn occurs which causes the metallic silver in the film to precipitate which renders the film black when developed

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4
Q

Radiographs

describe digital (computed) radiography

A

the cassette contains a photo-stimulable phosphor detector system. when the xray hits the cassette, a fraction of the absorbed energy is trapped in the detector. A red laser light stimulates the emission of trapped energy and blue-green light is converted into an electric signal which is digitalized

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5
Q

Radiographs

when viewing an image, you cannot tell whether a structure is what or what?

A

anterior or posterior

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6
Q

Radiographs

the pts R side is displayed on which side of the image?

A

left

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7
Q

Radiographs

which structures look white on xray? why?

A

more dense (bone); because they absorb more

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8
Q

Radiographs

which structures appear black on xray? why?

A

air, fat; because they do not absorb as much

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9
Q

Radiographs

what color would each be?
* air
* fat
* soft tissue/organs
* metal, calcium, bones

A
  • black
  • gray/black
  • gray
  • white
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10
Q

Radiographs

what are low density structures called?

A

radiolucent

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11
Q

Radiographs

how does the thickness of something impact its appearance?

A

thicker structures absorb more, so it will appear whiter

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12
Q

Radiographs

which structures are the easiest to evaluate on radiograph?

A
  1. radiodense (bone/clacium)
  2. radiolucent
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13
Q

Radiographs

simply- how can you tell if a bone is broken on xray?

A

disruption in the smooth outer edge

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14
Q

Radiographs

a break in the bone is less dense… why? (so darker on xray)

A

space fills with blood and marrow

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15
Q

Radiographs

medulla vs cortex of bone

A
  • medulla: inner portion, less dense (appears darker)
  • cortex: outer portion, more dense, appears lighter
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16
Q

Radiographs

how to tell if a child’s growth plate is still open?

A
  • smooth, undulating lucent line separating the epiphysis from the metaphysis
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17
Q

Radiographs

how to determine bone age using xray

A

evaluation of bony structures and growth plates of the hand

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18
Q

Radiographs

how should normal lungs appear?

A

black

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19
Q

Radiographs

how do abnormalities appear in the lungs?

A

typically varying shades of gray

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20
Q

Radiographs

what can CXR be used for?

A
  • evaluate size/shape of the heart
  • evaluating the pleura
  • evaluating the lungs
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21
Q

Radiographs

what can abdominal xray evaluate?

A
  • small and large intestines (because they are air filled, so appear darker)
  • kidney stones
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22
Q

Radiographs

are abd xrays good for seeing organs?

A

no- all similar densities so hard to differentiate. sometimes adjacent fat can allow you to see borders

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23
Q

Computed Tomography

how are images obtained?

A

xray detectors located 180 deg from each other rotate around a patient to create axial slices of a patient

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24
Q

Computed Tomography

how to interpret the images? (like anterior/posterior/right side/left side)

A

the images are viewed as though the patient is lying down on their back and you are standing at their feet.

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25
Q

Computed Tomography

what can be used to enhance images?

A

contrast

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26
Q

Computed Tomography

colors according to density?

A

since xray is used… it’s the same!
so air/less dense = dark
bone/more dense= light

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27
Q

Computed Tomography

what makes up contrast?

A

iodine

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28
Q

Computed Tomography

how does contrast work?

A

dye is administered via IV and the tissues in the body take up the contrast at differing amounts. The more contrast that is taken up, the lighter the tissue will appear. this allows us to differentiate structures of similar densities that are right next to each other.

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29
Q

Computed Tomography

which abd organ absorbs the most dye?

A

kidneys so they’ll be the lightest

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30
Q

Computed Tomography

in general- CT vs xray in terms of visualization

A

CT better shows all structures than xray.

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31
Q

Computed Tomography

can you see blood vessels on CT?

A

yes & differentiate them from other structures.

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32
Q

Computed Tomography

what density is subarachnoid space and lateral ventricles in the brain?

A

low density, appears darker than other brain matter

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33
Q

Computed Tomography

do white and gray matter actually show up differently on CT?

A

YES- white matter is darker than gray matter. (white is less dense = darker)

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34
Q

Computed Tomography

generally what is CT used for

A

everything lol

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35
Q

Computed Tomography

what can chest CT identify?

4 general

A
  1. tumors/masses of the lung
  2. infection
  3. emphysema/other chronic lung diseases
  4. evaluate blood vessels for artherosclerosis, clots
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36
Q

Computed Tomography

When might CT be used for bone fractures? (4)

A

intra-articular fractures of the hip, ankle, knee or if tumor is suspected

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37
Q

Computed Tomography

why might CT of the abdomen be used?

6

A
  1. abd pain
  2. inflammatory conditions (appedicitis, diverticulitis)
  3. tumor assessment
  4. organomegaly
  5. kidney stones
  6. organ/bowel obstruction
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38
Q

Computed Tomography

what is 3D rendered imaging most commonly used for?

A

pre-op surgical planning

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39
Q

Computed Tomography

describe CT angiography

A

CT technique targeted to display the arteries so that catherters can be placed more safely

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40
Q

Ultrasounds

how are images created with US?

A

high frequency sound waves which are directed into the body and reflected back. The reflected sound waves provide information about the depth, type of tissue, and tissue interfaces which gets converted into grayscale images

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41
Q

Ultrasounds

do US use radiation?

A

no

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42
Q

Ultrasounds

what is the purpose of gel?

A

goes between the skin and the transducer to prevent air from intervening between the two

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43
Q

Ultrasounds

differentiate high frequency and low frequency sound waves

A
  • high frequency: high resolution images, best for superficial images (do not deeply penetrate)
  • low frequency: lower resolution images, deeply penetrate
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44
Q

Ultrasounds

characterize high intensity echos

A
  • echogenic or hyperechoic
  • appear white
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45
Q

Ultrasounds

characterize low intensity echos

A
  • hypoechoic
  • appear dark
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46
Q

Ultrasounds

how might the gallbladder look on US?

A
  • fluid filled center: no echo returned, black
  • walls: return echo, gray to white
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47
Q

Ultrasounds

how does the composition of adjacent tissues affect the appearance of the image?

A
  • the greater the difference between the two adjacent structures, the greater the reflected sound waves are (more echogenic) and the whiter their borders appear
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48
Q

Ultrasounds

what structures are best visualized with US?

2 generalities

A
  • solid organs (liver, kidneys, spleen)
  • superficial structures (thyroid, testicles)
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49
Q
A
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50
Q

Ultrasounds

describe how US looks in pregnancy

A
  • amniotic fluid appears black (no echo)
  • uterine wall/abdominal wall appear gray
  • fetus will be gray
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51
Q

Ultrasounds

which fluid filled structures can and can’t be visualized with US

A
  • can: superficial like gallbladder, urinary bladder, heart
  • poor: thoracic aorta because it is deep to bone/air
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52
Q

Ultrasounds

describe when US is used in pregnancy

A
  • early pregnancy: confirm presence of embryo
  • mid pregnancy: evaluate for fetal abnormalities
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53
Q

Ultrasounds

why can we US through the skull in a fetus?

A

not yet ossified

54
Q

Ultrasounds

how is US used in gynecology?

A
  • used with a transvaginal transducer
  • inserted into the vagina and positioned in the vaginal fornix
  • transvaginal allows you to get closer to the ovaries and and uterus allowing for better images
55
Q

Ultrasounds

how is US used for abdominal organs?

A
  • can routinely evaluate the liver, kidneys, spleen
  • common findings include cysts, tumors, kidney stones, calculi
56
Q

Ultrasounds

why would it be abnormal to see the pancrease on US?

A

usually obscured by gas in the stomach

57
Q

Ultrasounds

what is doppler used for?

A

to determin the velocity and direction of blood flow, to evaluate for stenosis of blood vessels, and vascular resistance and patency

58
Q

Ultrasounds

describe the doppler effect

A

change in frequency of sound waves as the object moves
* blood moving toward transducer = higher frequency, shorter wavelength
* blood moving away from transducer = lower frequency, longer wavelength

59
Q

Ultrasounds

what does a spectral doppler provide info on?

A

direction of blood flow and flow velocity in cm/sec

60
Q

Mammography

what type of image is mammogram?

A

low dose xray that is used to screen for breast cancer

61
Q

Mammography

what law oversees compliance with screening mammography?

A

the mammography quality standards act

62
Q

Mammography

what does the federal low govern?

A
  • equipment
  • procedures
  • personnel
63
Q

Mammography

how are images obtained?

A

breast is compressed between a plastic plate and the xray detector

64
Q

Mammography

why is the breast compressed?

A
  • decreases xray dose because it’s closer to the tissue
  • reduces patient movement during imaging
65
Q

Mammography

what are the two standard views?

A
  • cranio-caudal (CC)
  • medio-lateral oblique (MLO)
66
Q

Mammography

describe cranio caudal view

A

breast is compressed from top to bottom

67
Q

Mammography

describe mediolateral oblique view

A

breast is compressed obliquely

68
Q

Mammography

how are CC images viewed?

A
  • R breast and L breast are viewed side by side to view abnormalities
  • RCC and LCC are always added at the lateral aspect (top of the image)
69
Q

Mammography

how are MLO images viewed?

A
  • R breast and L breast are viewed side by side to view abnormalities
  • RMLO and LMLO are always added
  • xray beam passes medally to laterally
  • axilla is at the top of the image, inferior breast is as the bottom of the image
70
Q

Mammography

describe magnification views

A
  • increasing the distance from the breast to the receptor plate allows for mangification and increased spatial resolution to help characterize masses
71
Q

Mammography

describe the lateral medial (LM) view

A
  • beam passes laterally to medially
  • helps depict lesions in a orthogonal view
  • benign milk of calcium!
72
Q

Mammography

describe spot compression

A
  • use a small paddle to provide focal additional compression
73
Q

Mammography

describe rolled view

A
  • top of breast is rolled relative to the bottom to spread of tissues
74
Q

Mammography

describe cleavage view

A
  • optimizes inclusion of medial tissues in CC view
75
Q

Mammography

what anatomical features do we look for with CC view?

A

all normal features of a breast like:
* nipple
* subq fat
* fibroglandular tissue
* retroglandular fat
* cooper’s ligaments

76
Q

Mammography

what anatomical features do we look for with MLO view?

A
  • nipple
  • fibroglandular tissue
  • Cooper’s ligaments
  • axillary lymp
  • pectoralis major muscle
77
Q

Mammography

most specific sign of malignancy?

A

lobulated (bumpy) spiculated (linear strand/spikes extending outward) mass

78
Q

Mammography

describe architectural distortion

A
  • perceived as straightened lines or lines converging onto a central point
  • seen with breast carcinomas
79
Q

Mammography

describe microcalcifications

A
  • fairly common
  • usually benign
  • pleomorphic (weird shapes/sizes) clusters can be a sign of cancer
80
Q

Mammography

what are the four categories of breast density?

A
  1. fatty (whiter)
  2. scattered
  3. heterogeneously dense
  4. extremely dense (darker)
81
Q

Mammography

what is the purpose of more lbs of compression?

A

more evenly spreads out tissues

82
Q

Mammography

describe digital mammography

A
  • detector is a photon receptor that convert photons into a digital signal that can be viewed on a high resolution monitor
83
Q

Mammography

describe 3D tomosynthesis

A
  • acquires a variable number of images in an arc-like swing of the camera and recreates the images into 1mm thick slices
  • reduces overlapp of tissue
  • can be viewed as a “movie”
84
Q

Mammography

how to know if there is adequate tissue included in the image?

3 things

A
  1. in MLO view can you see pectoralis major?
  2. is the nipple in the image?
  3. is retroglandular fat included?
85
Q

Mammography

in addition to comparing R and L breasts, what should you do when available?

A

compare old scans to new scans to find subtle changes

86
Q

Magnetic Resonance Imaging

what does MRI rely on for producing images?

A

molecular composition of the tissues

87
Q

Magnetic Resonance Imaging

can produce what type of images?

A

3-D

88
Q

Magnetic Resonance Imaging

how are images obtained?

A
  • extremely powerful magnet
  • protons in the patients tissues will naturally align themselves with the magnetic field
  • radiofrequency pulses are sent into the patient which disrupts the alignment of protons and generates an image
89
Q

Magnetic Resonance Imaging

which molecules emit MRI signal?

A
  • only molecules with an odd number of protons have their own magnetic field
  • Hydrogen (in water) largely
90
Q

Magnetic Resonance Imaging

which fields can images be obtained in?

A
  • axial
  • coronal
  • sagittal
91
Q

Magnetic Resonance Imaging

how are axial images viewed?

A

as though the Dr is looking at the patient from the food towards the head

92
Q

Magnetic Resonance Imaging

how are coronal images viewed

A

as though the Dr is looking at the front of the patient

93
Q

Magnetic Resonance Imaging

how are sagittal images viewed?

A

from the side- anterior is left side of image, posterior is right side of image

94
Q

Magnetic Resonance Imaging

which types of tissues produce the strongest signals?

A

those with the greatest water or fat content

95
Q

Magnetic Resonance Imaging

what color will structures appear?

A
  • high intensity signals: white
  • low intensity signals: dark
96
Q

Magnetic Resonance Imaging

what type of contrast is used for MRIs?

A

gadolinium

97
Q

Magnetic Resonance Imaging

what color will the contrast make tissues that uptake it?

A

brighter/whiter

98
Q

Magnetic Resonance Imaging

what are the two sequences of MRIs? what might be changed between the two of them?

A
  • T1 and T2
  • makes structures different colors
99
Q

Magnetic Resonance Imaging

what cannot be well visualized by MRI?

A
  • air (shows black)
  • bowel due to air & peristalsis
100
Q

Magnetic Resonance Imaging

which imaging techniques allow you to visualize the internal anatomy of joints?

A

only MRI!

101
Q

Magnetic Resonance Imaging

in the uterus, how are the myometrium and endometrium differentiated?

A
  • myometrium is dark
  • endometrium is light
102
Q

Magnetic Resonance Imaging

how is the nucleus pulposis differentiated from the annulus fibrosis in the intervertebral disc?

A

nucleus pulposis is a lighter, fluid filled component whereas the annulus fibrosis is the outer dark fibrous band.

103
Q

Magnetic Resonance Imaging

describe magnetic resonance angiography (MRA)

A
  • used to evaluate arterial blood flow to the CNS and extremities/organs
  • displays the caliber of a blood vessel and can show occlusions, stenosis, aneurysms, clots, artherosclerosis
104
Q

Magnetic Resonance Imaging

describe magnetic resonance venography

A
  • used to evaluate venous drainage from the CNS and in the chest, abdomen, pelvis, extremities
  • blood flow in the arteries is not observed with this technique
105
Q

Magnetic Resonance Imaging

describe magnetic resonance cholangiopancreatography

A
  • used to visualize the bile and pancreatic ducts for stones or obstructions
106
Q

Fluoroscopy

describe

A

specialized xray technique that images moving structures and displays them in real time on a monitor

107
Q

Angiography

describe

A

use of fluoroscopy to place catheters and other interventional devices into blood vessels

108
Q

Fluoroscopy

benefit of fluroscopy

A

can visualize dynamic processes

109
Q

Fluoroscopy

describe how images are obtained?

A

pt lies on a table and the xray machine travels toward the pt and toward the “image intensifier”

110
Q

Angiography

describe how images are obtained

A
  • inject contrast (iodine)
  • use the fluoroscopy imaging to guide placement of catheter
111
Q

Angiography

what is opacified to visualize the vessels?

A

vessel lumen NOT the wall

112
Q

Angiography

why might contrast move slowly through vessels?

A

heart now pumping forcefully or slow blood flow

113
Q

Fluoroscopy

describe barium as a contrast agent

A
  • swallow/stomach studies or enemas into the colon
  • very desne, appears white
114
Q

Fluoroscopy

describe arthrography

A
  • iodine inserted into a joint
  • ROM tested
115
Q

Fluoroscopy

what procedure in the uterus can fluoroscopy assist with?

A

blocked fallopian tubes

116
Q

Nuclear Medicine

3 most common imaging exams?

A
  1. FDG PET for malignancies
  2. Bone scans
  3. Myocardial perfusion scans
117
Q

Nuclear Medicine

how do PET scans work?

A
  • exploits the differencies in the way a tumor functions vs normal tissue
  • tumors require more energy and metabolize more gluicose
  • inject glucose and tumors will “hog” the injection
118
Q

Nuclear Medicine

describe bone scans

A
  • depict bone turnover
  • any damage to the bone is repaired via increased bone turnover
  • administer phosphate compound via IV which will then get incorporated into the bones and areas of increased turnover
119
Q

Nuclear Medicine

describe myocardial perfusion scans

A
  • performed for the evaluation of blood flow to the LV
  • can choose sestamibi or tetrofosmin for tracer
120
Q

Nuclear Medicine

4 most common isotopes used

A
  1. technetium 99m (variety of studies)
  2. indium 111 (WBC scans)
  3. iodine 131/123 (thyroid)
  4. fluorine 18 (PET)
121
Q

Nuclear Medicine

only blank are used to create images?

A

photons

122
Q

Nuclear Medicine

most studies are performed with what type of rays?

A

gamma

123
Q

Nuclear Medicine

how are images created?

A

scanners record the photons being emitted from the patient

124
Q

Nuclear Medicine

differentiate PET scanners and gamma cameras

A
  • Gamma: count photons emitted, one at a time; commonly use Tc-99
  • PET: for positron emitting isotopes (F-18)
125
Q

Nuclear Medicine

what are planar images?

A

2D images of 3D things

126
Q

Nuclear Medicine

what are tomographic images? how are they created?

A
  • 2D images of 2D objects
  • created by rotating a gamma camera around the pt while taking pictures and then computing them
127
Q

Nuclear Medicine

what are nuclear studies often used in conjunction with?

A

anatomic studies (radiographs/CTs) to provide additional anatomic and localizing information

128
Q

Nuclear Medicine

what is the solution to requiring radiograph studies in addition to nuclear medicine studies?

A

combined PET-CT scans

129
Q

Nuclear Medicine

why should you use caution with a PET CT scanner?

A

two sources of radiation to the pt

130
Q

Nuclear Medicine

what do the colors on imaging mean?

A
  • dark: high radiotracer uptake (hot/radiotracer avid)
  • light: low radiotracer uptake (cold/photopenic)
131
Q

Nuclear Medicine

what color would bone turnover be?

A

DARK

Clin D III (11 decks)

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