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CD III > Lecture 11- Ultrasounds > Flashcards

Lecture 11- Ultrasounds Flashcards

1
Q

Training for Medical Sonographer

A
  • typically 2 yr education program tied to bachelor’s degree
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2
Q

example certifications

A
  • RDMS: OB/GYN, abd
  • RVT: vascular
  • RDCS: echo, peds echo
  • can get certs in neuro, B mode/eye
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3
Q

Ultrasound Provider

A

UP, mid level provider (only really find these in echos)
master’s degree

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4
Q

OB/GYN

transabd approach

A
  • TAS- transabdominal approach
  • requires full urinary bladder
  • used in later pregnancy (very late may not need full bladder), ovaries, uterus
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5
Q

OB/GYN

endovaginal sonography

A
  • requires empty bladder
  • use in early pregnancy, ovaries, uterus
  • frquencies 5-10MHz, limited FOV
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6
Q

OB/GYN

First trimester studies

A
  • Ectopic pregnancy
  • Threatened AB (cervix open/closed, fetal viability/death, anembryonic pregnancy/blighted ovum)
  • Sonographic dates (gestational sac size, crown rump length)
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7
Q

OB/GYN

Crown rump length

A

measured as the greatest length in a straight line from the cranial to the caudal end of the body in the straightest possible position of the embryo/fetus

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8
Q

OB/GYN

2nd and 3rd trimester US use

A

Fetal measurements
* biparietal diameter (BPD)
* head circumference (HC)
* abd circumference (AC)
* femoral length to humeral length ratio (FL/HL)

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9
Q

OBGYN

Other uses

A
  • Intrauterine growth retardation (IUGR)
  • premature rupture of membranes (PROM)
  • multiple gestations (seen on volume ultrasound mode)
  • congenital anomalies
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10
Q

OB/GYN

Biophysical Profile Fetal Assessment

A
  • Level II US
  • Fetal Assessment: number, position, lie; breathing, movement, tone, reactive heart rate
  • Fetal Data: measure BPD, FL, AC; systematic organ review
  • Placenta, amniotic fluid, cord
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11
Q

OB/GYN

US guided OB procedures

A
  • Amniocentesis: AFP level abnormal, fetal lung maturity check, level of fluid
  • Chorionic Villus Sampling (CVS): prenatal test that involves taking a sample of tissue from the placenta to test for chromosomal abnormalities and certain other genetic problems
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12
Q

OB/GYN

purpose of US for GYN exams

A
  • uterine abnormalities
  • adnexa-ovarian pathology (tumor vs cyst)
  • IUD placement
  • PID changes
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13
Q

US Overview

Transducers

A
  • change one form of energy into another
  • Piezoelectric crystals creat a voltage when mechanically deformed and is the active component of the transducer (emits US frequency waves)
  • requires conductivity gel
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14
Q

US Overview

Frequency

A
  • Number of cycles per sec
  • Hertz/Hz (hearing is 30-20,000 Hz; US is > 20,000 Hz- usually 2MHz-10MHz)
  • determined by sound source (variable frequency based on what you’re imaging)
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15
Q

US Overview

Beam Anatomy

A
  • beam starts as size of transducer
  • converges to focal point (focal length, diverges in far zone, larger diameteres have further focal length)
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16
Q

US Overview

US transducer beam

A
  • sound waves in transducers don’t diffract
  • most energy transmitted along main central beam
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17
Q

US Overview

Resolution

A
  • Lateral Resolution : 2 points distinguishable when side by side
  • Depth resolution : 2 points distinguishable when front to back
  • Wavelength influences resolution (higher frequency –> higher resolution, but lower penetration)
  • Ex: thyroid use 10MHz bc it’s superficial; liver might require 2MHz bc it’s deeper
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18
Q

US Overview

Pulsed Waves

A
  • collection of number of cycles that travel together
  • On time: transducer sending
  • Off time: receiving (capturing return trip information)
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19
Q

US Overview

receiver

A
  • as image depth increases, the pulse repetition frequency decreases (# of pulses per second) so requires more listening time
  • operator determines maximum imaging depth
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20
Q

US Overview

Acoustic Propagation Properties

A

Effects of medium upon sound wave
* propagation speed
* attenuation (absorption, reflection, scattering)
* impedance

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21
Q

US Overview

propagation speed

A
  • determined by density and stiffness of medium
  • lungs (0.5 km/sec), fat (1.45 km/sec), soft tissue (1.54 km/sec), bone (3.0 km/sec)
  • speed m/s = frequency (Hz) x wavelength (m)
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22
Q

US Overview

Attenuation

A
  • decrease in intensity and amplification in soft tissue
  • greater frequency, greater attenuation
  • limits maximum depth from which one can obtain images
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23
Q

US Overview

Absorption

A
  • energy imparted to cell is lost by conversion to another form such as heat/vibration of intracellular particles
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24
Q

US Overview

reflextion

A
  • some of propagating acoustic energy is re-directed back toward transducer
  • smooth reflector (mirror) is specular reflector (diaphragm)
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25
Q

when to do specular reflector longitudinal scan

A
  • diaphragm
  • liver
  • kidney (loss of curve on outline)
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26
Q

US Overview

Scattering

A
  • if boundary between 2 media has irregularities with a size similar to pulses’ wavelength, the wavelength can be redirected into many directions
  • backscatter to transducer
  • rayleigh scatter
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27
Q

US Overview

Impedance

A
  • acoustic resistance to sound as travels through medium
  • intensity increases w/ decreased density and with increased propagation speed
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28
Q

US Overview

media that is difficult to image

A
  • bone: reflects too much, high speed (increased impedance, attenuation)
  • lung: too much scatter, low propagation speed
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29
Q

US Overview

artifact sources

A
  • machine malfunctioning
  • poor engineering
  • acoustic artifacts
  • operator error
  • interpretor error
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30
Q

US Overview

acoustic artifact types

A
  • reverberation
  • shadowing
  • enhancement
  • reflectors
  • propagation speed
  • resolution
31
Q

Acoustic Artifact

describe reverberation

A

multiple echos or reflextion equally spaced (2+ reflectors in US beam)

32
Q

Acoustic Artifact

describe shadowing

A
  • occurs when US can’t pass through first structure
  • occurs when first structure is highly reflective, highly attenuated, highly scattered
  • sound does not penetrate, so acoustic shadow as useful artifact: renal claculi, cholelithiasis
33
Q

Acoustic Artifact

describe enhancement

A
  • appears higher than normal echo amplitude after sound passes through fluid (increased “ease” of sound transmission through fluid; less impedence, faster speed)
  • may have fill in artifact
34
Q

Acoustic Artifact

describe curved/oblique reflextors

A

image may not be present or understated

35
Q

Acoustic Artifact

describe propagation speed errors

A
  • if tissue is not 1.54 km/sec, there will be incorrect depth of image
  • ex: fatty liver disease will change speed
36
Q

Acoustic Artifact

describe resolution

A
  • appears as 1, if closer than resolution of machine (try imaging in different plane to confirm)
37
Q

US Overview

quality assurance

A
  • tissue equivalent phantom: cysts, solids, same resolution lateral and vertical
38
Q

US Overview

biological effects & safety measures

A
  • very high US intensity can cause damage
  • thermal injury: exams that cause < 1 deg C elevation of temp is safe; anything > 41 degC can be harmful to fetus
  • Cavitation: bodies of gas/bubbles which can become excited by US (vibrate/shrink) leading to soft tissue injury
  • do not perform w/out reason, do not prolong scan w/out reason, use minimal output power needed
39
Q

Real Time Imaging Studies

Sector imaging

A
  • transverse, sagittal plane images
  • can obtain obliques
  • array of elements w/in transducer
40
Q

Real Time Imaging Studies

orientation to transabdominal approach fils

A
  • Outer approach
  • Longitudinal: head on L, foot on R
  • Transverse: point toward pt’s R
  • cavity approach changes orientation
41
Q

US Overview

echogenicity

A
  • more white = more echogenic = more dense
  • more black = less echogenic = fluid
  • imaging choice for cystic vs solid
42
Q

US Overview

describe cyst appearance

A

black fluid filled sac

43
Q

US Overview

describe transabdominal sonography (TAS)

A
  • NPO (reduces bowel gas, GB should be “full”)
  • look for free fluid & tap if found
44
Q

US Overview

Biliary System Etiologies

A
  • cholecystitis
  • Cholelithiasis
  • choledocholithiasis
  • GB polyps
  • echogenic bile
45
Q

US Overview

pancreatic etiologies and US use

A
  • pseudocysts
  • tumors
  • acute pancreatitis: swollen/large, less echogenic
  • chronic pancreatitis: damaged, more echogenic areas
  • hard to visualized when normal
46
Q

US Overview

vessels around pancreas on US

A
  • aorta is round w/ thicker wall
  • IVC is “collapsed” w/ thinner wall
  • fat around SMA
  • splenic vein courses opposite
47
Q

US Overview

kidney etiologies

A
  • hydronephrosis
  • parenchymal changes
  • masses
  • cysts
  • congenital deformities
  • adrenals (not usually visualized)
48
Q

US Overview

why does kidney appear different colors

A
  • NOT MEDULLA VS CORTEX
  • center is echogenic due to the collecting system
49
Q

US Overview

what aids in kidney visualization

A
  • liver aids in R kidney (kidney usually less echogenic)
  • spleen aids in L kidney (spleen smaller)
50
Q

US Overview

describe hydronephrosis

A
  • dilated collecting system in renal pelvis
  • +/- hydroureter
51
Q

US Overview

splenic etiologies

A
  • enlargement
  • rupture
  • sickle cell
  • neoplasms
52
Q

US Overview

spleen appearances on US

A

normally homogenous

53
Q

US Overview

retroperitoneum etiologies

A
  • enlarged lymph nodes
  • masses
  • aorta
  • abscess
54
Q

US Overview

use of US in AAA

A
  • visualize lumen walls and blood flow/clots
55
Q

US Overview

high resolution of superficial structures

A
  • thyroid
  • scrotum/testes
  • breast
56
Q

US Overview

Thyroid US

A
  • normally homogenous but can see cysts, malignant lesions, multi-nodular goiter, and developmental cysts
  • Parathyroids are not visible on US
57
Q

US Overview

Scrotum/Testicular US

A
  • normall homogenous but can visualize edema, hydrocele, orchitis, epididymitis, carcinoma, seminoma, variocele
58
Q

US Overview

what is hydrocele

A

fluid in scrotal sac

59
Q

US Overview

Breast US

A
  • breast parenchyma is fairly homogenous
  • can detect masses, cysts, abscesses
60
Q

US Overview

purpose of pelvis studies

A
  • full urinary bladder for acoustic window
  • can do pre and post void for volume/residual volume
61
Q

US Overview

prostate US

A
  • echogenicity is usually homogenous
  • do transrectal approach to view size/masses
62
Q

US Overview

neonatal imaging

A
  • can do because they have fontanelles and cartilage not bone, so we can see through it
  • evaluate for hydrocephalus (enlarged ventricular system w/ CSF)
63
Q

US Overview

Misc uses

eye, vascular

A
  • eye: retinal detachment
  • vascular: venous or arterial doppler
64
Q

US Overview

describe doppler shift

A
  • change infrequency of sound as result of motion between sound and receiver (RBCs bounching)
  • Hz: doppler shifts of -10KHz to +10KHz in doppler studies
  • Negative #s: away from transducer
  • Positive #s: toward transducer
65
Q

US Overview

describe doppler

A
  • 0 or 180 deg: no image as the sound beam and motion are parallel
  • 90deg: velocity is 0, use for imaging
  • motion mode for flow- graphic
66
Q

US Overview

describe aliasing

A
  • artifact when flow appears negative but is actually positive
  • the deeper the sample volume the more and the higher the frequency the more likely aliasing is to occur
67
Q

US Overview

what are duplex studies

A
  • imaging and doppler in same study
68
Q

US Overview

color flow doppler

A
  • color is related to direction of flow in relation to transducer (pos/neg)
  • many times this may correspond to venous vs arterial flow
69
Q
A
70
Q

US Overview

echocardiograms

A
  • heart imaging
  • has motion and imaging modes which show valvular abnormalities, wall motion analysis, ejection fraction, pericardial effusion
  • need to image through cardiac window (aka between bones)
71
Q

US Overview

Echo frequencies

A
  • Peds: diamters 3-6mm; 3.5, 5.0, 7.5 MHz
  • Adults: 3.5, 2.25, 1.6 MHz
  • can do transesophageal approach for best resolution
72
Q

FAST ultrasound

A
  • Focused Assessment w/ Sonography for Trauma (FAST)
  • Hepatorenal recess (morison pouch), peisplenic area, subxiphoid pericardial window, suprapubic window (Douglas pouch)
73
Q

what does E Fast add?

A
  • extended fast
  • Hepatorenal recess (morison pouch), peisplenic area, subxiphoid pericardial window, suprapubic window (Douglas pouch)

PLUS
* bilateral hemithoraces and upper anterior chest wall

CD III (12 decks)

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