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Intro Classes > Anatomy > Flashcards

Anatomy Flashcards

1
Q

types of medical imaging

A

X-rays (Radiography)

Fluoroscopy

Computer tomography (CAT scans or CT)

Ultrasound (US)

Magnetic resonance imaging (MRI or MR)

Nuclear medicine (PET, SPECT)

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2
Q

conventional radiology overview

A

a highly penetrating beam of X-rays transilluminates the patient, showing tissues of differing densities of mass within the body as images of differing intensities (areas of relative light and dark) on the film or monitor

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3
Q

X-rays either pass through the body or are absorbed by the various tissues in different amounts depending on what factors

A

density (g/cc3) (higher -> more absorption)

atomic number of elements in tissue (higher -> more absorption/scattering)

thickness (layering -> more absorption)

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4
Q

conventional radiology mechanism

A

a tissue or organ that is relatively dense in mass (e.g., compact bone) absorbs or reflects more X-rays than does a less dense tissue (e.g., spongy bone), thus denser tissues/organs produce a somewhat transparent area on the X-ray film or bright area on a monitor because fewer X-rays reach the film or detector

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5
Q

principles of X-ray image formation

A

portions of the beam of X-rays traversing the body become attenuated to varying degrees based on tissue thickness and density

the beam is diminished by structures that absorb or reflect it, causing less reaction on the film or by the detector compared with areas that allow the beam to pass relatively uninterrupted.

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6
Q

posteroanterior (PA) projection

A

refers to a radiograph in which the X-rays traversed the patient from posterior (P) to anterior (A); the X-ray tube was posterior to the patient and the Xray film or detector was anterior

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7
Q

radiopaque

A

a dense substance, regarding X-rays

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8
Q

radiolucent

A

a substance of less density, regarding X-rays

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9
Q

anteroposterior (AP) projection

A

refers to a radiograph in which the X-rays traversed the patient from anterior (A) to posterior (P); the X-ray tube was anterior to the patient and the X-ray film or detector was posterior

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10
Q

an X-ray image can be made on:

A

Film in cassette

Computer screen (digital imaging)

Fluorescent screen (fluoroscopy)

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11
Q

contrast radiography definition

A

a contrast material is used to enhance the imaging of the conventional radiology

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12
Q

contrast radiology overview

A

radiodense material and/or lucent material (air) are injected in a cavity

barium or iodine, plus air, for bowel

iodine for everywhere else: joints, vasculature, spinal canal

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13
Q

single contrast definition

A

the use of barium only to outline the gastrointestinal system tract

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14
Q

double contrast definition

A

the use of barium to coat the GI system followed by air to distend the inner lumen

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15
Q

type of radiography using contrast for GI

A

esophogram

cologram

endoscopic retrograde cholangiopancreatography (ERCP)

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16
Q

type of radiography using contrast for vascular system

A

angiogram

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17
Q

type of radiography using contrast for urinary tract

A

intravenous pyelogram (IVP)

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18
Q

type of radiography using contrast for reproductive tract

A

hysterosalpingogram

vasogram

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19
Q

type of radiography using contrast for joints

A

arthrogram

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20
Q

type of radiography using contrast for respiratory tract

A

bronchogram

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21
Q

type of radiography using contrast for spinal canal or cord

A

myelogram

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22
Q

ERCP

A

an endoscopic retrograde cholangiopancreatography

contrast is used to image the pancreas, bile duct and gallbladder

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23
Q

IVP

A

intravenous pyelogram

used to image the kidney and urinary tract

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24
Q

hysterosalpingogram

A

uses contrast to study the uterine tube and uterus

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25
Q

vasogram

A

images the ductus deferens, formerly called vas deferens

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26
Q

double contrast esophogram purpose

A

assess:

motility
reflux
stricture
masses

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27
Q

double contrast UGI purpose

A

assess for:

ulcers
tumors
gastritis

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28
Q

double contrast UGI procedure

A

barium then air

often, the patient is rolled in the bed after the barium and air are introduced. This can help to coat the walls of the organ with barium, while the air spreads the walls apart

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29
Q

small bowel series purpose

A

assess for:

bleeding
lesions
obstruction
malabsorption
post-op evaluation
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30
Q

small bowel series procedure

A

AKA small bowel follow-through

a descriptive term for a series of images taken at intervals following barium ingestion; the barium is followed through the small intestine

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31
Q

double contrast lower GI purpose

A

assess for:

bleeding
cancer
inflammatory bowel dz

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32
Q

double contrast lower GI process

A

barium can go into the GI tract in either direction, and a barium enema followed by air insufflation reveals the walls of the large bowel, especially if the patient is rolled to coat the walls with barium

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33
Q

angiogram

A

readily reveals blockages in vessels

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34
Q

aneurisms

A

bulging areas in vessel walls can be found

through interventional means such as selective embolization, they can be treated

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35
Q

digital subtraction angiography

A

process in which a mask image of the same area made prior to contrast administration can be used to “subtract” the background, non-contrast structures

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36
Q

computed tomography (CT) scans

A

the scans show radiographic images of the body that resemble transverse anatomical sections

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37
Q

CT mechanism

A

A beam of X-rays passes through the body as the X-ray tube and detector rotate around the axis of the body, and multiple overlapping radial energy absorptions are measured, recorded, and compared by a computer to determine the radiodensity of each volumetric pixel (voxel) of the chosen body plane

the computer maps the voxels into a planar image (slice) that is displayed on a monitor or printout

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38
Q

the radiodensity of each voxel in CT

A

determined by factors that include the amount of air, water, fat, or bone in
that element

39
Q

CT images

A

relate well to conventional radiographs, in that areas of great absorption (e.g., bone) are relatively transparent (white) and those with little absorption are black

40
Q

how are axial CT (and MRI) images always viewed

A

as if one is standing at a supine patient’s feet—that is, from an inferior view

41
Q

how are coronal CT (and MRI) images viewed

A

as if the patient is facing you

42
Q

how are sagittal CT (and MRI) usually viewed

A

as if you are standing at the patient’s left side

43
Q

why would one have the computer adjust CT images to highlight certain
structures

A

the adjustments produce windows

the common windows are soft-tissue, lung, and bone, each one showing its namesake well

44
Q

common CT windows

A

soft-tissue

lung

bone

45
Q

nuclear medicine imaging overview

A

a radioactive agent is given IV, swallowed, or inhaled, and the scanner detects the radioactive agent and reveals function

E.g. PET, SPECT

46
Q

nuclear medicine imaging purpose

A

can reveal unusual patterns of metabolic activity and possible pathologies, especially neoplasms

47
Q

diagnostic radiology ionizing radiation

A

radiation used in diagnostic radiology is potentially harmful but adverse effects from ionizing radiation used in diagnostic radiology are extremely rare

but since ionizing radiation used in some imaging modalities is potentially harmful, steps should be taken to reduce patient and physician exposure

48
Q

how much does a standard 0.5-mm lead apron reduce radiation exposure from the ionizing radiation of diagnostic radiology

A

by 95%

49
Q

what width standard lead apron reduces radiation exposure from the ionizing radiation of diagnostic radiology by 95%

A

a standard 0.5-mm lead apron

50
Q

whole body lethal dose of radiation

A

400 rads or 8 Sieverts (Sv)

51
Q

cancer therapy radiation dose

A

6000 rads (not lethal because it is focal)

52
Q

CXR radiation dose

A

0.1 mSv

53
Q

abdominal CT radiation dose

A

10 mSv

54
Q

natural radiation radiation dose

A

3 mSv/year

55
Q

radiation dose enough to cause skin damage

A

10,000 x-rays = 100 CTs = 30 minutes fluoroscopy

56
Q

RAD

A

Radiation Absorbed Dose (energy absorbed/mass)

57
Q

Sievert (Sv)

A

measure of “effective dose” on various tissues, taking into account varying sensitivities.

58
Q

Radiation exposure is measured in what unit/units

A

RADs or more commonly Sieverts or milliSieverts

59
Q

CT scans involve approximately what times dose of ionizing radiation that standard plain film X-rays do

A

100 times

60
Q

ultrasound overview

A

images created by a combination of high-frequency soundwaves and computer manipulation

61
Q

US sound waves frequency

A

1- 10 MHz

62
Q

what interferes with US transmission

A

air and bone

63
Q

what tissues are seen best by US

A

fluid and water-like tissues

64
Q

US benefits

A

no biologic effects; i.e completely safe to tissues

excellent for fluid containing structures (i.e. gallbladder, cysts, bladder, pregnancy)

no patient discomfort

dynamic (real time)

portable device

65
Q

US ideal applications

A

pregnancy/neonatal

solid or fluid-filled internal organs

blood vessels (Doppler)

joints

procedure guidance/intra-operative assistance since it is a live imaging modality

66
Q

US mechanisms

A

US waves are generated by applying an electric field to a piezoelectric crystal in a transducer, causing the crystal to vibrate and generate sound waves

the transducer also functions as a detector, which receives the echoes reflected from within the patient [like sonar!]

a thin layer of gel is placed on the skin to serve as a coupling medium to transmit the sound waves from the hand-held transducer into the patient

67
Q

what is crucial in determining the image produced in US

A

the angle at which the transducer is held

68
Q

US higher frequencies use

A

the frequencies penetrate less but reveal fairly shallow anatomy well

69
Q

US low frequency use

A

transducers penetrate deeper and are useful for some deep or large structures, such as liver or kidney

70
Q

Doppler US use

A

shows blood flow within the heart and blood vessels

71
Q

reading an US

A

the intensity of the echoes reflected back to the transducer is proportional to the whitening of the film (i.e. no internal echoes = black; internal echoes = grey to white)

US images are sectional, but the axis of the slice is controlled by the angle of the transducer

72
Q

MRI overview

A

magnetic resonance imaging (MRI) provides images of the body similar to those of CT scans, but MRI is better for tissue differentiation

MRI studies closely resemble anatomical sections, especially of the brain

73
Q

MRI process overview

A

the person is placed in a scanner with a strong magnetic field, and the body is pulsed with radio waves

signals subsequently emitted from the patient’s tissues are stored in a computer and reconstructed into various images of the body

the appearance of tissues on the generated images can be varied by controlling how radiofrequency pulses are sent and received

74
Q

reading an MRI

A

signal intensity refers to the brightness of signal generated by specific tissues

I.e. tissues that are:

bright = hyperintense (trabecular bone)
dark = hypointense (Cortical bone, ligaments)
middle = isointense
75
Q

MRI mechanism of functioning

A

the powerful magnet causes an alignment of hydrogen atoms with the patient’s body

when the magnetic field is switched off, the hydrogen returns to its original state and gives off a slight amount of energy, which is picked up by sensitive detectors

terms usually refer to a signal of pathologic process relative to surrounding tissues

76
Q

MRI strengths and weaknesses

A

easily image in any plane

no biologic effects, no radiation

imaging does not depend on tissue density — but on hydrogen content

bone, calcifications hard to see (hydrogen poor tissue, i.e. other than cortical bone and metal)

77
Q

T1 and T2 MRI overview

A

refer to physical properties of the tissues after the exposure to a series of pulses at different intervals (TE)

different tissues have different T1 and T2 properties – primarily, water is dark in T1 (solids lighter) and bright in T2 (solids darker)

78
Q

CSF T1 and T2

A

T1 weighted: dark

T2 weighted: bright

79
Q

muscle T1 and T2

A

T1 weighted: gray

T2 weighted: dark gray

80
Q

spinal cord T1 and T2 (MRI)

A

T1 weighted: gray

T2 weighted: light grey

81
Q

fat T1 and T2

A

T1 weighted: bright

T2 weighted: light

82
Q

disc T1 and T2 (MRI)

A

T1 weighted: gray

T2 weighted: bright

83
Q

air T1 and T2

A

T1 weighted: very dark

T2 weighted: very dark

84
Q

inflammation T1 and T2

A

T1 weighted: dark

T2 weighted: bright

85
Q

T2 weighting often replaces radiological procedure

A

myelograms, which introduces a contrast agent into the CSF to produce images somewhat like T2 images

86
Q

multiple ways to manipulate the magnet for MRI sequences

A

spin echo (T1 & T2 weighting)

gradient echo

inversion recovery (STIR, FLAIR, TIRM)

fat suppressed

MR angiography - contrast enhanced (gadolinium)

87
Q

functional MRI

A

the area of the brain being used lights up, so brain functions can be studied

88
Q

MR-angiography (MRA)

A

3D MR-angiography

gadolinium is a contrast agent used in MR angiography imaging that reveals vascular patterns in great detail

89
Q

differentiating btw CT scans and MRI scans

A

cancellous bone and marrow spaces will usually glow white on MRI due to fat within these spaces, so focus on the cortical compact bone which is white on CT and black in MR

90
Q

CT benefits

A

detailed cross-sectional anatomy

computer analysis of tissue differences with
reconstruction

91
Q

CT limitations

A

high cost
radiation exposure
contrast reactions
patient discomfort from IV

92
Q

US limitations

A

cannot penetrate air or bone

relatively expensive vs plain film (less expensive than CT,
MRI, nuclear medicine)

93
Q

MRI benefits

A

no radiation

excellent differentiation of soft tissue structures with subtle differences in density (tendons, cartilage, muscle)

many possible views (axial, sagittal, coronal, oblique)

94
Q

MRI limitations

A

time consuming

images are very motion sensitive (i.e. breathing, heartbeat, peristalsis, tremors, movement)

calcium is poorly evaluated due to lack of signal

limited availability and very expensive

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