Imaging Lecture Test 4

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What are four special concerns w/ equine radiography?: proper restraint, possible injury to personnel, damage to machine, need more time & patience
Name two positioning devices for equine radiography: positioning block and cassette tunnel
What is the most common type of xray machine for equine?: portable
What is the most common cassette size for equine xray?: 10x12
What are three machine options for equine xray?: small portable, mobile unit, mounted unit on rails
Four safety considerations for equine xray?: protect personnel 1st (equip 2nd), take safest view possible, avoid views from behind rear leg, never hold xray tube
Why is labeling esp important for equine xray?: all legs look the same from cannon bone distally
3 technique consideration for equine xray?: clean debris from area of interest, pick foot & pack w/ playdough, and views of joints should be done weight bearing
Why are special contrast techniques needed?: give more info than flat films, used to highlight a lesion, increases contrast w/i a specific organ
What are two types of contrast media?: pos and neg
What type of contrast media makes area white?: Positive
What type of contrast media makes area black?: Negative
Give 2 examples of positive contrast medias: Organic Iodine & Barium
What contrast media is used for excretory urography, angiography, and cystography?: Organic Iodine
What contrast media is usually used for the GI tract? When would it not be used and what would be used in its place?: Usually barium, but contraindicated if perforation suspected - then iodine would be used
Examples of neg contrast medias: room air, oxygen, CO2, nitrous oxide
What 2 neg contrast medias are safer because they are easily absorbed and have lest chance of air emboli?: CO2 and nitrous oxide
What type of contrast media is used for pneumocystography, double contrast studies, and pneumography?: Negative
What contrast media has side effect or air embolism?: Air
What are some side effects of iodine?: nausea, allergic reaction, anaphylactic reaction, hypotension, and shock
What are some side effects of barium?: aspiration (make sure tube is in stomach), peritonitis (from perforation - leaks into abdomen)
What change of exposure technique is used w/ contrast media?: Increase MAS by 30%
Describe general patient prep for abdominal study & what views taken?: fast for 12-24 hours if possible, enema 4 hours prior, VD and right lateral views taken
When is excretory urography indicated?: to check kidney function and size
What is procedure for excretory urography?: place indwelling IV catheter, give bolus injection of iodine contrast agent, take films
What are the 3 phases of excretory urography?: nephogram (see renal vasculature), pyelogram (see renal pelvis), drainage phase (see ureters)
When is cystography indicated?: to examine bladder wall for abnormalities or tears
What are 2 precautions for cystography?: don't over fill bladder - it can rupture, use nitrous rather than air because of air embolism
What is the procedure for cystogram?: sedation necessary, do survey films first, clean penis, pass urinary catheter, remove urine, infuse contrast agent until bladder is moderately full
Name and describe 3 kinds of cystograms: pos contrast (iodine), pneumocystogram (gas), double contrast (both)
When is a urethrogram indicated?: to examine internal structure of urethra
Name the 2 types of urethrograms: retrograde and antegrade
describe a retrograde urethrogram: + or - contrast inserted w/ a balloon-tipped catheter, film taken at end of injection
Describe retrograde urethrogram: + contrast is placed into bladder (must use enough to induce urination), film is taken at voiding
When is esophagography indicated?: to examine esophageal function
Describe esophagography procedure: barium or iodine used, pt. in lateral recumbency slowly infuse contrast agent into cheek or mix into food, take film at pt swallows
When is an upper GI study indicated?: to evaluate stomach and small intestine
In what situations are barium and iodine not used in an upper GI?: don't use iodine in a dehydrated pt, don't use barium if perforation is suspected
Describe patient prep for an upper GI?: 21-24 hr fast, enema 4 hours prior, sedation if needed
Describe procedure for upper GI: do survey film first, use barium or iodine, place stomach tube, induce agent into stomach
What views are taken in an upper GI series?: VD, DV, & rt lateral
Describe a double contrast gastrogram: same as upper GI except pt needs empty stomach and gas introduced right after barium - films done right away (don't wait)
When is a barium enema contraindicated?: when rupture/perforation is suspected
Describe procedure for a barium enema: survey films first, pt in lateral recumbency, lubricated enema cath inserted and balloon inflated, infuse media slowly
What is a pneumoperitonealgram: the injection of CO2 or nitrous into the peritoneal cavity to improve the contrast of abdominal organs
What is a myelogram?: induction of iodine contrast into the subarachnid space around the spinal cord
What is a non-selective angiogram?: injection of a bolous of iodine contrast into a vessel - film is taken at time of injection and is effective for identifying occulsions or aneurisms
How does US work?: Short bursts of ultra-high frequency sound waves are xmitted into patient. When they hit something they bounce back and are converted into a white dot on monitor screen.
In US, the greater the difference in density and composition between two adjoining tissues, the ____ the echo will be.: stronger
In US, the stronger the echo, the ____ the white dot on the monitor screen.: brighter
In US, what determines the position of the white dot on the monitor screen?: the length of time between the production of the sound burst and the return of the echo
In US, echos from deeper tissues take ____ to return to the transducer and will be be placed as white dots ____ on the monitor screen.: longer, lower
In US, echos from more superficial structures tissues return ____to the transducer and will be be placed as white dots ____ on the monitor screen.: faster, closer to the top
What is the appearance of fluid on an US?: Black
What is the appearance of soft tissue on an US?: shades of grey
What is the appearance of bone/stone/gas on an US?: white
What is acoustic impendance?: How well a substance xmits sound
What is acoustic interface?: the boundary between two tissues w/ different xmitting properties (causes returning echo)
What is echogenicity?: the ability to produce echos
What is anechoic?: produces no echos (no dots on screen)
What is hypoechoic?: Produces weak echoes (grey dots on screen)
What is isoechoic?: produces echoes similar to background echoes
What is hyperechoic?: produces intense echoes (bright white dots on screen - bones)
What is resolution?: The degree of image detail and quality
One cycle per second is called a ____.: hertz
One million cycles/second is called a ____.: megahertz
Diagnostic US uses sound waves at what frequency?: 2-10 MHz (2-10 million cycles/second)
What is attenuation?: sound waves are attenuated or decreased as the travel through tissue
What three thing can cause attenuation?: absorption, reflection, and scatter
What are three common transducer frequencies?: 3.5, 5, and 7.5 MHz
The higher the transducer frequency, the ____ the sound wave is attenuated, but the ____ the detail.: faster, better
lower transducer frequency = ____ penetration and thus ____ poorer resolution: better penetration, poorer resolution
higher transducer frequency = ____ penetration and thus ____ poorer resolution: lower penetration, better resolution
US does not penetrate what three things?: bones, stones, and air
In US, you must have gel between transducer and skin in order to eliminate what?: air gap
What is an acoustic window?: clear path for sound wave around bones or lungs to get to structure of interest
What is acoustic shadowing useful in identifying?: bladder stones
What is acoustic enhancement and what is it used for?: Concept that sound waves travel through fluid more readily thus they have higher remaining energy when they pass through an area composed of fluid. Useful in differentiating a solid tumor from an abscess.
What is the most common display format in US?: Real Time - produces a moving picture - can see fetal movement and heart beating
In US, what type of display format isn't used much anymore.: A Mode
In US, what display format isn't used very often, produces a still life picture, and is also called "brightness mode"?: B Mode
In US, what display format is used w/ echocardiography, produces an "ice pick" view of the heart, and makes a line tracing of heart wall and valve action?: M Mode

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