Special procedures (contrast studies) Flashcards
How much of an emergency is barium leakage?
What does it cause, what is mortality rate, etc
Barium leakage results in peritonitis/mediastinitis, fibrosis, granuloma formation.
50% mortality rate
How much of an emergency is barium leakage?
What does it cause, what is mortality rate, etc
Barium leakage results in peritonitis/mediastinitis, fibrosis, granuloma formation.
50% mortality rate
Describe two situations where administration of ORAL hypertonic iodinated contrast could be fatal?
1) Shocky patients - if administered orally - will pull fluid into the intestinal tract - further dehydrating them
2) Where aspiration may occur - esophagrams, bronchoesophageal fistulas –> pulmonary edema
Describe two situations where administration of hypertonic iodinated contrast could be fatal?
1) Shocky patients - if administered orally - will pull fluid into the intestinal tract - further dehydrating them
2) Where aspiration may occur - esophagrams, bronchoesophageal fistulas –> pulmonary edema
Metrizamide was one of the first non-iodinated contrast agents used - and was seen causing neurotoxic effects when used for myelography.Why did this occur?
2-deoxy-D-glucose side chain that inhibited glucose metabolism in the brain
What are the two categories of iodinated contrast media?What characteristics separate these groups?
Ionic and non-ionic.
Ionic: When in solution - dissociates into the negative iodinated anion, and positively charged cation (sodium) Dissociation = greater osmoliaity (2-3x that of non-ionic)
Non-ionic - do not dissociate in solution
What is range of osmolality of ionic contrast agents vs non-ionic media?
Ionic: 1900-2100mOsm/kg
Non-ionic: 290-900mOsm/kg (closer to blood)
Blood: 275-300mOsm/kg
How frequently are contrast reactions seen in human patients, and what is that number related to?
What are examples of idiosyncratic and non-idiosyncrati reactions?
Idiosyncratic - true allergic reaction - histamine release, complement cascade, immune-mediated, hypertonicity
Non-idiosyncratic:
acute renal failure - due to vasoconstriction, direct toxic effects on renal tubular cells
anti-coagulant effects - ionic agents have more anti-coagulant effects,
BBB damage - ionic agents increase BBB permeability, Bradycardia - vasovagal reaction
CHF - osmotic hypervolemia and worsen CHF
ECG changes - increased HR and prolonged QT interval
Endothelial lesions - increased permeability and thrombi formation,
Rigid erythrycotyes (difficulty moving through capillaries),
Decreased left ventricular function (after intracoronary injections),
Nausea/vomiting,
Peripheral vasodilation - agents have direct effect on endothelium - increasing their permeatility
When should ionic agents NOT be used and why? (4 examples)
1) Dehydrated/renal disease patients - may result in acute renal failure
2) Intrathecal injection - seizures can be 1400x as toxic than IV injection
3) Anytime the BBB may be damaged - can result in increased intracranial pressure and decreased glucose uptake/metabolism (metrimazole)
4) CHF
What are generic and brand names most commonly used for intrathecal injections?
Which has a higher LD50 for intrathecal injection?
Iohexol - Omnipaque
(stupid ass mnemonic - people who are omnipotent could put a hex on you)
LD50: 840mg I/kg
Iopamidol - Isovue
LD50: 1490mgI/kg
Describe two situations where administration of hypertonic iodinated contrast could be fatal?
1) Shocky patients - if administered orally - will pull fluid into the intestinal tract - further dehydrating them
2) Where aspiration may occur - esophagrams, bronchoesophageal fistulas –> pulmonary edema
Metrizamide was one of the first non-iodinated contrast agents used - and was seen causing neurotoxic effects when used for myelography.Why did this occur?
2-deoxy-D-glucose side chain that inhibited glucose metabolism in the brain
What are the two categories of iodinated contrast media?What characteristics separate these groups?
Ionic and non-ionic.
Ionic: When in solution - dissociates into the negative iodinated anion, and positively charged cation (sodium) Dissociation = greater osmoliaity (2-3x that of non-ionic)
Non-ionic - do not dissociate in solution
What is range of osmolality of ionic contrast agents vs non-ionic media?
Ionic: 1900-2100mOsm/kg
Non-ionic: 290-900mOsm/kg (closer to blood)
Blood: 275-300mOsm/kg
How frequently are contrast reactions seen in human patients, and what is that number related to?
What is the difference between idiosyncratic and non-idiosyncratic reactions?
Idiosyncratic - non-dose dependent
Non-idiosyncratic - dose dependent
What are examples of idiosyncratic and non-idiosyncrati reactions?
Idiosyncratic - true allergic reaction
Non-idiosyncratic:
acute renal failure - due to vasoconstriction, direct toxic effects on renal tubular cells
anti-coagulant effects - ionic agents have more anti-coagulant effects,
BBB damage - ionic agents increase BBB permeability, Bradycardia - vasovagal reaction
CHF - osmotic hypervolemia and worsen CHF
ECG changes - increased HR and prolonged QT interval
Endothelial lesions - increased permeability and thrombi formation,
Rigid erythrycotyes (difficulty moving through capillaries),
Decreased left ventricular function (after intracoronary injections),
Nausea/vomiting,
Peripheral vasodilation - agents have direct effect on endothelium - increasing their permeatility
When should ionic agents NOT be used and why? (4 examples)
1) Dehydrated/renal disease patients - may result in acute renal failure
2) Intrathecal injection - seizures can be 1400x as toxic than IV injection
3) Anytime the BBB may be damaged - can result in increased intracranial pressure and decreased glucose metabolism (metrimazole)
4) CHF
What are generic and brand names most commonly used for intrathecal injections?
Iohexol - Omnipaque (stupid ass mnemonic - people who are omnipotent could put a hex on you) LD50 - 840mg I/kg Iopamidol - Isovue LD50: 1490 - mg I /kg
What are brand names for Diatrizoate, and is it ionic or non-ionic
Ionic
Cystograffin, renograffin, gastrograffin
How do you measure barium using weight-to-volume?
Give example
Certain amount of barium sulfate added to enough water to obtain predetermined total volume.
20% w/v suspension can be prepared by adding 20g of barium sulfate to water to = 100mL
20% w/v suspension can be prepared by adding 40g of barium sulfate to wter to =200mL
How do you measure barium using weight-to-weight?
Give example
A certain weight of barium sulfate is added to enough water to obtain a total weight.
20% w/w solution can be prepared by adding 20g of barium sulfate to 80g (80mL) of water to obtain a final weight of 100 grams, and a volume slightly more than 80mL
What is dose for a pneumocolon?
10cc/lb
30cc small dog
200-300 large dog
What is dose for double contrast gastrogram? for dogs and cats
40kg - 1.5ml/kg
cats - 6ml
inflate with air - 20ml/kg
Dose for upper GI with iodinated contrast for both cats and dogs?
Dogs - 700-875mg I/kg diluted to 10ml/kg
Cats - 600-800 mg I/kg diluted to 10ml/kg
What is dose for upper GI with barium?
5-6cc/lb
10ml/kg
increase kVP by 7-8
What is dose for static esophagram with barium paste?
15ml per swallow in small dogs
20-30mL per swallow in large dogs
What is dose for esophagram with barium or ionic suspension?
5-15cc/lb
What is dose for excretory urogram?
600-800mg I /kg
What is dose for positive contrast cystogram?
5 cc /lb
What is dose of double contrast cystogram?
Inject 3-5mL of 2% lidocaine
5-10cc of contrast
distend with air (CO2 or NO2 preferred to room air) - 5ml/kg
What is dose for celiogram?
350-400mg I /kg
What is dose of contrast for a dynamic esophagram using barium in dogs vs cats
Dogs - 10ml
Cats - 5ml
What is normal GI transit time for each portion of the tract in an upper GI study in dogs
Immediate - stomach 15 minutes - duodenal 1 hour - should reach colon 0.5-2 hours - stomach should be empty 0.5-2 hours post duodenal filling - complete small intestinal transit
What is normal GI transit time for each portion of the tract in an upper GI study in cats
immediate - stomach
10m - duodenumal
30-60m - stomach empty
30-60m post duodenal filling - complete small intestinal transit
What is transit time for iodinated contrast upper GI study in dogs?
Normal gastric emptying time - 30-120m
Small intestinal transit time - 60-90m
What is transit time for iodinated contrast upper GI study in cats?
Normal gastric emptying time 30-90m
Small intestinal transit time 15-75m
What is EU appearance of acute pyelonephritis?
pelvic dilation
proximal ureteral dilation
absent/incomplete filling of pelvic recesses
What is EU appearance of chronic pyelonephritis
Pelvic dilation with irregular borders
Proximal ureteral dilation
Short blunted pelvic recesses
What is EU appearance of hydronephrosis
pelvic dilation
dilation of pelvic recesses
uretera dilation
What is EU appearance of renal parenchymal neoplasia?
distortion or deviation of renal pelvis +/- dilation.
Distorition or deviation or pelvic recesses
What is EU appearance of renal pelvic neopalsia
Distorition or dilation of renal pelvis
Filling defects in renal pelvis
What is dose for positive contrast urethrography?
cat - 5ml
Small dog - 10ml
medium dog -20ml
large dog - 30ml
what is the difference between idiosyncratic and non-idiosyncratic reactions to contrast media?
idiosyncratic - allergic reaction - non-dose dependent, will occur with test dose
non-idiosyncratic - dose dependent - less likely to have reaction with a lower dose
How much more soluble is CO2 and NO2 versus air?
CO2 - 20x more soluble than room air
NO2 - 40x more soluble than room air
Describe the contrast utilized in CE-US
Description of the use of CE-US in 4 dogs with pancreatic tumors. JSAP 55
Tiny gas filled microbubbles that are stabilized by outer shell that are injected into systemic circulation - traverse pulmonary capillary criculation and reach organ vascular supply. Once in the vascular supply, they remain at this level (unlike CT or MRI).
Gas content is removed from blood by the lungs
Stabilizing components removed by kidneys and liver.
Microbubbles are detected following vibration and bursting - which increases SNR
What are the 3 major phases of swallowing?
Oropharyngeal, esophageal, gastroesophageal
What are hte 3 phases of the oropharyngeal phase of swallowing?
oral, pharyngeal, cricopharyngeal
What abnormalities will you see with an oral dysphagia?
Bolus not formed
bolus not propelled caudally to pharynx
weak plungerlike activity of tongue (not pressing against dorsal aspect of the oral cavity)
Subsequent stages are normal
What abnormalities will you see with a pharyngeal dysphagia?
Normal oral stage
Synchronous with cricopharyngeal opening
Retention of contrast within the pharynx
Inadequate pharyngeal contraction (high contraction ratio) (>0.6)
Misdirection of the bolus into larynx or nasopharynx, or aspirated
What abnormalities will you see with a cricopharyngeal dysphagia?
Depends on the form
Chalasia (flaccidity) -
Relaxation/incompetence of sphincter - large, air filled
Prolonged time to cricopharyngeal sphincter opening
Achalasia (failure to open - congenital)
incomplete/lack of opening of the sphincter
Vigorous attempsts to pass bolus
Synchrony or dyssynchrony between pharyngeal contraction and opening
What is the pharyngeal contraction ratio? How is it measured?
Measurement of the air within the pharynx during the most constricted phase of the pharynx (when dorsal pharyngeal wall is at its most ventral and caudal)
of pixels of the pharynx at maximum contraction / # of pixels at time of relaxation (hold frame)
What phases have abnormal pharyngeal contraction ratios?
Both pharyngeal and cricopharyngeal phases
How do you differentiate between abnormalities of only pharyngeal and cricopharyngeal phases?
Both will have elevated contraction ratios
Pharyngeal - normal opening of the UES
Cricopharyngeal - delay of opening of hte UES
How do you differentiate between abnormalities of only pharyngeal and cricopharyngeal phases?
Both will have elevated contraction ratios
Pharyngeal - normal opening of the UES (0.07s)
Cricopharyngeal - delay of opening of hte UES (0.28s)
What is appropriate dose of contrast given to both cats and dogs for an esophagram?
Depends on agent
Small-large breed dogs - 10-20mL if given barium suspension
Cats - 5-7mL if suspension
Paste - 10mL for dogs, 5mL for cats
Iodine - 10-15ml for dogs, 5-10 for cats 50/50 contrast:water dilution
