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Diagnostic imaging > Contrast Studies > Flashcards

Contrast Studies Flashcards

1
Q

what are the 3 most common types of contrast studies?

A

GI, urogenital, spinal cord

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2
Q

why do we use contrast agents?

A

they cause a difference in the density and organ visibility

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3
Q

types of contrast agents

A

positive (appears white or radiopaque) and negative (appears black or radiolucent)

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4
Q

what are the two positive contrast medias?

A
  1. Barium sulfate and BIPs (barium impregnated polyethylene spheres)
  2. water-soluble organic iodides (can be ionic or non-ionic)
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5
Q

Barium sulfate

A

used for GI studies, administered orally or rectally, high atomic # (high atomic # = higher density), insoluble

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6
Q

what are the 2 systems to measure Barium sulfate?

A
  1. weight to volume (w/v)
  2. weight to weight (w/w)
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7
Q

what forms is Barium sulfate available in?

A

powder, liquid suspension, paste

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8
Q

disadvantages of Barium sulfate

A

can’t use if perforation is suspected, aspiration in lung can be fatal, and blocks ultrasound waves

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9
Q

advantages of Barium sulfate

A

low cost, delineates mucosal walls well, palatable, not absorbed through intestine, doesn’t become diluted with secretions

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10
Q

BIPS

A

used to determine motility issues
comes in capsule form
better evaluation of gastric emptying times

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11
Q

water-soluble organic iodides

A

mix readily with blood/body fluids and are excreted through the kidneys

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12
Q

what are the 2 types of water-soluble organic iodides?

A

ionic (molecules dissociate and cause changes in osmolality) and non-ionic (molecules remain whole)

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13
Q

ionic water-soluble organic iodides

A

triiodinated compounds derived from benzoic acid ring structure
made up of an anion (-) and a cation (+)
cation: salt (sodium or megulumine)
anion: includes benzene ring with 3 iodine atoms + carboxyl group + other side chains (Diatrizoate or iothalamate)

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14
Q

when are ionic water-soluble organic iodides used?

A

when GI perforations are suspected
comes in oral form: Meglumine diatrizoate and sodium diatrizoate (Gastrografin)
disadvantages: bitter taste, expensive, hypertonicity effects

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15
Q

injectable form of ionic water-soluble organic iodides

A

used for excretory urography, intraarticular studies, draining wound studies, and fistulography
ex: sodium diatrizoate (Hypaque), meglumine diatrizoate (Hypaque M), iothalamate meglumine (Conray)
advantages: less viscous
disadvantages: hypertonicity effects, irritating to brain and spinal cord, anaphylaxis

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16
Q

nonionic water-soluble organic iodides

A

doesn’t dissociate
doesn’t increase osmolality of plasma
ideal for studies involving spinal cord (myelography) and respiratory tract

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17
Q

injectable form of nonionic water-soluble organic iodides

A

Iohexol (Omnipaque), iopamidol (Isovue), ioversol (Opitray), iopromide (Ultravist), Iotrolan (Isovist, Osmovist), ioxilan (Oxilan), nonionic dimer iodixanol (Visipaque)
advantages: fewer side effects, rapid transit time, reabsorbed after extraluminal leakage, doesn’t become dilute
disadvantages: expensive

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18
Q

how else can ionic and nonionic injectable contrast media be classified?

A

monomer and dimer
monomer: 1 benzene ring
dimer: 2 benzene ring
osmolality decreases when there are more iodine molecules
ionic monomer has highest osmolality and nonionic dimer has the lowest

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19
Q

negative contrast media

A

radiolucent gases: air, nitrous oxide, oxygen, CO2)
less mucosal detail compared to positive
cons: overinflation, use of room air can produce air embolism that can cause cardiac arrest

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20
Q

what is it called when negative contrast medias are used with positive contrast medias?

A

a double contrast study

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21
Q

esophagography

A

used to assess status of esophagus, potential motility issues, and surrounding tissues
ideal to use fluoroscopy
lateral and DV positioning used

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22
Q

indications of an esophagography

A

abnormal swallowing, foreign body obstruction, dysphagia (difficulty swallowing), megaesophagus, regurgitation of undigested food, head/neck trauma

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23
Q

media and doses for an esophagography

A

barium sulfate liquid or paste, oral aqueous iodine if perforation suspected
standard dose: 5-20 mL
use organic iodine agent instead if aspiration and asphyxiation of contrast agent is of concern

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24
Q

double contrast study esophagography

A

obtain images during swallowing and during pause that follows swallowing of contrast
usually anesthetized
if reflux patient, administer only air

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25
Q

upper GI

A

evaluates the morphology of the stomach and small intestines, visualizes extramural/ mural/ intramural lesions of GI tract, gastric emptying and pyloric function

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26
Q

what could be affected in the GI tract if sedation is used?

A

the GI tract motility could be altered

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27
Q

indications of an upper GI study

A

recurrent vomiting, hematemesis, anorexia, melena, chronic weight loss, suspected foreign body, or if survey radiographs are non-conclusive

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28
Q

media and dose for upper GI study

A

barium sulfate suspension 60%
8-10 mL/kg for dogs and cats <10kg
5-7 mL/kg for dogs 10-40kg
3-5 mL/kg for dogs >40kg
iodinated contrast agents: 2-4 mL/kg of body weight added to water to equal 13 mL/kg
double/ negative contrast: 20 mL/kg via orogastric tube

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29
Q

what is the common patient prep for GI studies?

A

fast for 12-24 hours before and perform an enema the night before and the day of the procedure

30
Q

positioning for an upper GI study

A

measurement done at the thickest part of the abdomen over the thoracolumbar region or liver area for both lateral and VD

31
Q

double contrast upper GI study

A

better visualizes gastric lesions
shouldn’t be performed if patient hasn’t fasted
requires sedation
tips: slightly increasing the kVp may be needed, administer the entire volume of the barium, set a timer, iodinated agents’ transit times are faster than barium

32
Q

BIPS in upper GI studies

A

used to assist in the diagnosis of GI obstructions as well as motility and gastric emptying disorders
eliminates potential for aspiration
given with no food for gastric obstruction
given with soft food for gastric emptying disorder

33
Q

lower GI study

A

evaluates the cecum, colon, and rectum
done through a process of retrograde administration of a positive contrast agent
helps identify and evaluate extramural masses, mucosal lesions, disease of ileocolic valves, and overall morphology of ascending and transverse colon
important to remove feces to enhance visualization
sedation required

34
Q

indications of a lower GI study

A

abnormal defecation, excessive mucus, strictures, tenesmus, obstructions, rectal neoplasia, colitis, pelvic/abdominal trauma
can also use to view narrowing lumen that prevents passage of endoscope

35
Q

media and dose for lower GI study

A

barium sulfate 20% warmed to room temp
cats and small dogs: 10-20 mL
dogs: 30-60 mL
double contrast study: 1/2 barium dose is used and 25-50 mL of air for cats

36
Q

positioning for lower GI study

A

caudal abdomen

37
Q

precautions for lower GI study

A

avoid perforation of colon during catheterization, avoid overdistention

38
Q

urinary system contrast studies

A

evaluates kidneys, bladder, ureters, prostate, and urethra
contrast agents assist in visualization of size, shape, function, and opacity of renal system
use of ultrasound, MRI, and CT has become more common

39
Q

excretory urography

A

2 stage study of nephrogram and pyelogram

40
Q

indications of an excretory urography

A

abnormal urine/urination, suspected renal or urethral calculi, dysuria/pyuria, intra-abdominal mass

41
Q

media and dose for excretory urography

A

water-soluble iodide: 600-700 mg/kg up to 800 mg/kg
max dose: 90 mL in dogs and 15 mL in cats
ionic iodide: Diatrizoate (sodium hypaque)
nonionic iodide: Iohexol (Omnipaque), iopamidol (Isovue), iodizanol (Visipaque)

42
Q

patient prep for urinary studies

A

enema performed prior, fasted 24 hours prior, removal of urine, place an indwelling IV catheter

43
Q

positioning for an excretory urography

A

standard abdominal imaging techniques

44
Q

precautions for excretory urography

A

don’t do if anuria/ severe dehydration/ severe uremia/ urethral obstruction present, temperature decreases in renal function may occur after, make sure patient is hydrated, contrast reactions can occur, can be used in both azotemic and non-azotemic patients

45
Q

tips for excretory urography

A

compression done by using radiolucent sponge and elastic bandaging of an abdomen, right lateral recumbency gives greater imaging of kidney due to separation of right and left kidney, warming solution helps decrease viscosity and allows for easier administration

46
Q

retrograde cystography

A

evaluates the bladder with positive, negative, or double contrast study
can be used in absence of an ultrasound to determine masses

47
Q

indications of a retrograde cystography

A

abnormal urine, abnormal urination, trauma, abnormalities on survey rads

48
Q

media and dose for retrograde cystography

A

positive contrast: water-soluble organic iodide: 3-12 mL/kg
negative contrast: CO2, N2O, room air: 3-12 mL/kg
double contrast: cat: 0.5-1 mL positive agent + negative agent (3-12 mL/kg)
dog <10kg: 1-3 mL positive agent + negative agent (3-12 mL/kg)
dog >10kg: 3-6 mL positive agent + negative agent (3-12 mL/kg)

49
Q

common patient prep for urinary studies

A

fast 24 hours prior, enema 4 hours prior, sedation recommended, aseptic technique, survey rads, collect urine samples if needed

50
Q

positioning for retrograde cystography

A

standard lateral/ VD imaging of abdomen

51
Q

precautions for retrograde cystography

A

iatrogenic issues due to urinary catheterization and cystographic procedures, mucosal ulceration and inflammation, gas embolism when performing the negative contrast study

52
Q

tips for retrograde cystography

A

use right, left, and VD to identify lesions, administering lidocaine without epinephrine decreases spasms, allow bladder to be fully distended, reduction of 6 kVp in cats and 10-15 kVp in dogs commonly used when performing pneumocystogram, removal of contrast agent and bladder contents prior to waking

53
Q

urethrography

A

evaluates urethra for structures/masses that prevent/alter flow of urine
can be performed by retrograde administration of positive, negative, or double contrast studies or by compression of a positive contrasted full bladder

54
Q

indications of a urethrography

A

abnormal urine passage

55
Q

media and dose for urethrography

A

positive contrast organic ionic or nonionic agent: best to dilute agent to 150-200 mg of iodine/mL
dosing: dogs: 10-15 mL total volume
cats: 5-10 mL total volume

56
Q

positioning for urethrography

A

standard L/VD imaging of abdomen

57
Q

what can you do if a urinary catheter can’t be placed?

A

perform an antegrade/voiding urethrogram
1. gentle pressure applied to bladder filled with positive contrast media using wooden spoon
2. obtain lateral radiograph when urine is noted at urethral orifice

58
Q

precautions for urethrography

A

avoid trauma to urethra, avoid injection of air into torn urethra, voiding urethrogram may be better for females since it’s hard to place catheter

59
Q

tips for urethrography

A

if catheter is not a Foley a larger diameter catheter may be needed to prevent leakage of contrast agent around catheter, don’t leave the balloon on a Foley catheter inflated for an extended time period

60
Q

other contrast studies

A

myelography, angiography, arthrography, celiography, fistulography

61
Q

myelography

A

injection of radiopaque contrast into subarachnoid space either at C1-C2 or in the lumbar region of L6-L7 to assist in evaluation of spinal cord

62
Q

indications of myelography

A

localize and identify the size of the lesion or the extent of cord compression
paresis, paralysis, proprioceptive/sensory deficit, spinal pain

63
Q

media and dose for myelography

A

organic nonionic positive contrast iodine: Iopamidol (Isovue): 200-300 mL
Iohexol (Omnipaque): 240 mg/mL
dog dosage: caudal skull injection: cervical spine: 0.3 mL/kg, TL spine: 0.45 mL/kg
lumbar injection: cervical spine: 0.45 mL/kg, TL spine: 0.3 mL/kg

64
Q

patient prep for myelography

A

general anesthesia (avoid use of phenothiazine-based drugs), shave hair and aseptically prepare area

65
Q

positioning for myelography

A

L/VD imaging prior to collection of CSF or administration of contrast agent, positioning should be over the area of concern

66
Q

precautions for myelography

A

need to be anesthetized, CSF should be evaluated prior, be careful with spinal needle placement, make sure patient is hydrated, best to keep anesthetized with head elevated for 45 minutes-1 hour following procedure to minimize risk of seizures

67
Q

tips for myelography

A

if blood is obtained during placement of spinal needle don’t inject contrast agent, cervical injections tend not to move caudally to the area of concern and have an increased risk of trauma, if thoracolumbar region is the area of concern the best option is to use lumbar region for injection, lateral positioning for lumbar and cervical needle placement is most common

68
Q

angiography

A

identifies cardiac abnormalities, vessel occlusions, lesions, and tumor locations
water-soluble organic iodide injected into cephalic/jugular vein
fluoroscopy is the best method for evaluation

69
Q

celiography

A

identifies abdominal cavity and assists in determining diaphragmatic hernia
water-soluble organic iodide injected into abdominal cavity at site of umbilicus

70
Q

fistulography

A

assists in identifying fistulous tracts, potential foreign bodies in skin/ muscle/ soft tissue regions of body

Diagnostic imaging (13 decks)

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