AGR 324 Exam 3

What is echogenicity?

appearance of the tissues on ultrasound, based on the ability of the tissues to reflect sound waves. (think of it as the brightness)

What does it mean if a structure is “anechoic”? Can you give an example of an anatomical structure that is “anechoic”?

a structure that has very few or no echos, will appear black. this could be like a blood vessel, or the bladder.

Is a tissue that is “hyperechoic” is brighter or darker than the tissue around it? Are the sound waves that are being reflected back more or less intense (relatively speaking)?

appears brighter than the tissue around it. the sound waves are more intense that are reflected back.

What if the structure is “hypoechoic”?

reflects back less intense sound waves and appears darker than the tissue around it

What does it mean if 2 structures are “isoechoic”?

they have similar echogenicity toward each other

What is attenuation? What causes it?

the loss of sound wave energy as it traverses the tissue (can be due to absorption, reflection, or scattering)

What is reverberation? Give an example.

the sound wave is repeatedly reflected between two high reflective surfaces (ex. air and the probe)

Which is closer to the probe: the near field or the far field?

near field

which is farther to to the probe: the near field or the far field?

far field

What are the advantages of ultrasound?

real time imaging possible via a “cine loop”

can move the probe in any direction thats needed

can see fine anatomical detail

no safety precautions required

What type of waves are produced by the US probe? And what does the US actually measure?

transducer waves are produced, the US measures the soundwave thats reflected back to the probe from the tissue

How do you prep a patient for US? Does the probe need to be in contact with the skin? How can you make the probe have better contact with the skin?

for small animals have them in ventra, standing or lateral, for large animals usually standing. probe must have direct contact with the skin, so you shave the fur, spray with alcohol, and use ultrasound gel.

How many shades of gray are possible in an ultrasound?

256 different shades

What is B mode?

“brightness”, hyperechoic or hypoechoic, full 256 shades of gray

What is M mode?

“motion” creates continuous wave form indicating motion where the cursor is setting

What does doppler measure? What’s the difference in 4 types?

measure the velocity of blood, the 4 types are color, power color, pulsed wave, and continuous wave.

When is harmonic mode used?

reduces artifacts in large or obese patients

What does the gain knob adjust?

brightness

What does the depth knob change?

limit the depth so the area of interest fills the screen

Which probe will penetrate deeper: a lower frequency or a higher frequency?

lower frequency probe penetrates deeper into tissue

Which probe will have a better resolution: a lower frequency or a higher frequency?

a higher frequency probe provides better resolution

What is a focal zone?

allows the beam to converge more at a particular depth

What does the optimization button do?

auto adjustment

What should a “probe” actually be called?

transducer

What are the elements in a probe that vibrate to create the sound waves?

the crystals in the ceramic

How do you know which end of the probe is on which side of the view screen?

What are the different types/shapes of transducers?

linear transducers, convex transducers, phased array and 3D/4D transducers

What can you use to clean a transducer? Why can’t you go past the 2cm mark with the cleaner?

wipe off gel after each use with a soft cloth (dry or damp), use 10% bleach solution or 70%. alcohol. you can damage the transducer if go past the 2 cm mark

Can transducers be autoclaved or gas sterilized?

no

What are some indications for US in small animals? Horses? Pigs? Cattle?

small animals - GI studies, liver/GB studies, urinary tract, reproduction, cardiac evaluation, abdominal bleeding/trauma

horses - reproductive work, sports medicine

pigs - measurement of back fat (has to do with the meat production)

cattle - reproductive work, US-guided biopsies

What 2 tissues types can US NOT penetrate?

air or bone

What is reverberation?

repeated back and forth reflection of echoes between 2 strong reflective surfaces, like the reflection that happens where beam comes into contact with air

What is a comet tail artifact?

group closely interspaced and intense reverberations

What is an edge shadowing artifact?

form of refraction as beam passes through a fluid tissue interface

What causes acoustic enhancement?

beam traveling through a fluid filled tissue

What causes mirror image artifact?

sound beams reflected back from an interface makes the machine misinterpret what its reading

What causes acoustic shadowing artifacts?

beam hits a highly attenuating surface most of it is reflected away or absorbed, so theres no info distal to the object

What causes a side lobe artifact?

can be due to a high frequency beam

What are the advantages of endoscopy?

minimal invasive

examine an organs or body cavities

obtain tissue samples

retrieve foreign bodies or stones

aid in feeding tube placement

What are the major components of an endoscope?

insertion tube, handpiece, and umbilical cord

Where are you more likely to use a flexible endoscope? What about a rigid endoscope?

works well for most vet clinics, good for common procedures, used to evaluate non tubular structures

What is another name of a rigid endoscope?

telescope

What viewing angels are common in rigid endoscopes?

0-120

What type of bulb is found in an endoscope light source?

zenon or halogen

What is “insufflation” in endoscopy?

blowing of gas (like co2) into a body cavity (used for GI endoscopy to keep the kumen open)

What is “irrigation” in endoscopy?

flushing fluids (like distilled water) through an insertion tube, allows you to clear off the lens so you can see better

Why do we use CO2 for insufflation instead of oxygen?

used for GI endoscopy to keep the lumen open

What is the purpose of the deflection knobs in endoscopy?

large knob moves the scope up/down

smaller knob moves the scope left/right

What type of cleaner should you use for a “quick clean” of an endoscope?

enzymatic cleaner (nonabrasive, neutral pH, EZ-Zyme, enzol, metriZyme)

How can you sterilize an endoscope?

cold disinfection with glutaraldehyde, rinse after with sterile water than dry well, gas sterilization

What general technique do you use to image the skull?

use high mAs (you’re actually using a longer time and small focal spot) so lower mA

What are some possible artifacts in skull radiographs?

ears, tongue, ET tube, microchips and collars

Where does the marker go in skull rads?

goes towards the nose, if an oblique view use both right and left markers

As a general rule, where should you measure for skull radiographs?

measure at the widest area of the cranium

Are most issues the brain bilateral or unilateral?

unilateral

What are the 3 basic skull shapes? Be able to recognize an example of each.

brachycephalic, mesaticephalic, and dolichocephalic

Which skull view is best to evaluate the nasopharynx, retropharyngeal area and hyoid apparatus?

lateral view of the skull (on side)

In which skull views is the affected side positioned UP?

idk

How can you tell a lateral view of the skull is positioned correctly?

the rami of the mandible and the tympanic bullae should be superimposed

Which is preferred: VD or DV when imaging the skull?

DV

What type of dog might a VD be preferred in?

idk

What is a VD view good for imaging?

evaluating the nasal sinus/nasal passages

In which skull view do you aim the beam into the mouth parallel to the mandible? Where do you measure for this view? What does it image?

idk

What is the alternative to the above view that is recommended for brachycephalic breeds?

closed-mouth caudoventral-to-rostrodorsal oblique (CdV-RDO)

Where do you aim the beam in a rostrocaudal frontal sinus view?

aim the beam 2-3 cm rostral to the angular process of the mandible

What is another name for the front-occipital view? Where do you aim the beam?

idk

What is another name for the basilar view? What does it image?

rostrocaudal open mouth view, shows the tympanic bullae, base of the skull, odontoid process

What would you modify for cats and brachycephalics to still take a basilar view?

keep mouth closed, less kV, hard palate at a10 degree angle from perpendicular

How should you label the image in the lateral oblique view for the tympanic bullae, frontal sinus? Which side is “up”?

label left and right sides, unaffected dorsal and affected ventral unaffected side down

In the lateral oblique view for the mandible, how should you label the teeth?

dependent dorsally, upper ventrally

Can you take dental rads with a regular x-ray unit?

yes

What are the parts of the dental x-ray unit?

generator, extension arm, scissor arm, and x-ray tube

What technique setting do you routinely change (and which 2 do you NOT change)?

idk

Does the dental unit have a rotating or stationary anode?

stationary anode

What is the extension arm vs. the scissor arm?

extension arm - extends from generator and swings 180 degrees

scissor arm - at the end of the extension arm

What is the standard distance from the tooth (SID)?

2 inches

Does it take any special wiring for a dental unit?

yes

What is on the unit instead of a collimater light?

idk

What type of film/plates can be used in dental rads?

nonscreen dental film, computed radiography (CR) photostimulable plates (PSP), and direct digital receptors (DR)

What are the most common sizes of dental x-ray film?

0, 2, 4, are most common

What are the layers of a dental film packet?

plastic outer covering - with dot

paper

film

paper

lead foil

plastic outer covering

Which side of the dental film has a convex dot? What is on a digital plate instead of a dot?

the front side with writing on it

Where should the dot be positioned?

on the outside of the tooth facing up

What are the liquids in a chairside dark room?

developer, water, fixer, and water

What are some advantages of digital dental rads?

film can be manipulated digital for better visualization of structures, exact tooth being imaged can be easily labeled on the films, can be emailed to referral hospitals, easily stored in electronic medical record

What is the standard size digital image receptor?

size 2 sensor

How can you protect the sensor while taking dental rads?

use sleeve, glove, condom, anything waterproof

What changes/disease states are we looking for when we take dental rads?

periodontal disease, missing teeth, resorptive lesions, tumors, malformed teeth

What are the 4 types of teeth and their functions?

incisors, canine teeth, premolar teeth, molar teeth

incisors (I or i)

grooming, grasping, cutting food

canine teeth (C or c)

grasping/holding prey

premolar teeth (P or p)

cutting/shearing meat

molar teeth (M or m)

grinding

dog dental formulas deciduous

2 x (i3/3 c1/1 p3/3 m0/0) = 28 total

dog dental formula permanet

2 x (I3/3 C1/1 P4/4 M2/3) = 42 total

cat dental formula deciduous

2 x (i3/3 c1/1 p3/2 m0/0) = 26 total

cat dental formula permanent

2 x (I3/3 C1/1 P3/2 M1/1) = 30 total

what is the modified triadan system

first number = quadrant, second two numbers = tooth position

what are cats missing?

missing their upper first premolar so there is no 105 or 205 for them. cats are also missing their first and second mandibular premolars, so there is no 305, 306, 405, 406 for them either

Which teeth have 2 roots? 3 roots?

idk