X-ray Contrast Studies - define!
To instill radiopaque or radiolucent media into an anatomic site to cause a change in radiopacity, thus contrast, between two adjacent tissues.
Radiolucent
Negative Contrast
Air or CO2
Area is black as x-rays go through it
Radiopaque
Positive Contrast
Iodine or Barium
Area is light gray or white as x-rays are stopped
Radiopacity has to do with iodine content
Double Contrast
Using both +/-
Give + contrast first, then - contrast
Used in cystograms, for example
To better define or outline the structure (filling a lumen defines lumen and mucosa vs. the wall and serosa)
See shapes and contours of organs (strictures, scars, obstructions or out-pocketings of viscera)
Crude estimates of motility and emptying times (= transit times)
Common contrast studies
Esophagus
Stomach, small intestines, colon
Kidneys (size, position, orientation, are they working?)
- Nephrogastric phase of the execratory urogram
Ureters and Bladder
- Excretional phase of the execratory urogram
Bladder, Urethra (e.g. looking for bladder stones)
- usually done via retrograde catheterization
Epidural Space (Myelography)
Heart, Central and Peripheral Vessels (PAD)
- Angiograms
Do you use a technique chart for contrast studies?
Yes!
Use regular technique chart, however, add 2 kVp!
Define myelo
White matter of nervous system
Iodinated Contrast Media
Or “dye” = layman’s term
Atomic number for Iodine is 53 (important for parenteral administration as hyperosmolality gives rise to hypersensitivity reactions)
Iodinated Media for Intravascular Use
Soluble and relatively harmless but hypertonic
Ionic (non-organic)
Non ionic (organically bound iodine) produce fewer side effects, therefore are agents of choice, but are more expensive than ionics
Name some iodinated contrast media
Barium and iodine are most common
Barium is only used in GI tract
Iodine only used when study requires IV or injection
Name some common positive contrast media
**Ionic:
Diatrizoate (Hypaque 50)
Metrizoate (Isopaque 370)
**Non-ionic:
Iopamidol (Isovue 370)
Iohexol (Omnipaque 350)
Angiogram
Arthrogram
GASTROGRAFIN
Not for parenteral use!
Cysto-Conray II
Not for parenteral use!
Define KUB
Kidney
Urinary
Bladder
Allergic/hypotensive reactions
May happen shortly after giving contrast media
- vomiting
- ulcers, blisters, swelling on body and limbs
- Pt suddenly crashing
If given IV, reactions only happen internally
Barium Contrast Media
Atomic number is 56
- dense
- will not allow x-rays through
Formulations vary
- viscosity
- Ba++ content
- Flavor
Liquid EZ
Draw up 12 mL of contrast media
Gastroesophageal tube
Work clean/do not spill
Esophagus
Swallows of food with barium
Always take 2 views (orthagonal) at right angles to each other
Also used for motility studies (=fluoroscopy)
Deadly complication of Ba++ “Swallow”
Large bore stomach tube (feel the esophagus in neck during placement)
If animal is intubated into lungs, barium will get into lungs and Pt dies!
Gastrogram: Air, Barium or Iodide?
Do not use barium, if GI tract is perforated
Barium leaking out = create raging peritonitis
Use iodine, if it leaks out, will only cause slight irritation
Gastrographic phase
Needed positions:
DV
VD
R + L lateral
Get films at timed intervals after admin of barium or iodine
Need a series of films (5, 15, 30, 60 min intervals for 2 -3 hours)
Stomach and Small Intestines
Studies are timed
Films taken at intervals to measure transit times
Software can time stamp your shots
Colon: Positive and Double Contrast
Stress colitis
Rough, ulcerated
What has the barium enema been largely replaced with?
Colonscopy
Excretory Urogram
Have the abdomen prepped for radiography - empty stomach and colon
Iodinated contrast media given as an IV bolus
- Immediate imaging begun and continued at timed intervals
This study needs prep time and focus
- no multitasking or distractions
- several films in that series
IVP Nephrogram
Nephrogram and Ureterogram
Diminishing nephrogram and emerging ureterographic phase
Ureterographic Obliques
Intentional lateral abdominal oblique positioning to remove the superimposition of ureters
Should take two views to profile both of them
Retrograde Cystography
retrograde = backwards
Pneumocystogram (- contrast)
Contrast Cystogram (+ contrast)
Double Contrast Cystogram (+ first, then -)
Positive Contrast Cystogram
Filling defects
Irregular
Transitional cell carcinoma (TCC) = bladder cancer
Urethrogram and Pullback Urethrogram
Looking for stones, strictures, kinks, …
Actively injecting contrast media while pulling back out, leaving a trail of contrast media!
Myelogram
For Spinal cord compression
(MRI is better than this)
Usual suspects: Dachshunds
- thoracolumbar spine is usual area of injury
Myelography
Injection around the meninges to profile the spinal cord
- injecting a calculated dose of positive contrast media into the subarachnoid space to define flow and distribution of the dye column around and profile the meninges of the spinal cord
Can be organic or inorganic but must be spinal cord compatible
Injecting between L6,7
Filling defect of contrast material
Contrast material suddenly stops
Myelogram of a dog’s cervical neck region showing spinal cord compression by a herniated disc lesions particularly at C5 & also at C6.
MRI provides superior image
No radiation
Magnetic Resonance Imaging
Magnetic field is distorted by radiowaves (go from excited to stationary state), then image is captured!
Power is determined by magnetic field
Do not bring anyting steel into MRI room!
Hemilaminectomy to Remove Disc Extrusion
Rehabs & Permanent Paraplegics
Water therapy
Wheelchairs
…
Ultrasonography
Uses:
- CV
- Obstetrical
- Neurological
Advantages:
- machine is about $40,000 (less than an MRI machine)
- versatile
- non-invasive
- non-injurious
- easy to sell
- good image in places, radiographs didn’t show
- no ionizing radiation
Disadvantage:
- training it takes to use it properly
Define:
Sonogram
Ultra
Echo
Sonogram = sound energy
Ultra = silent to us
Echo = Sound in, pic out
U/S machine and transducers
Valuable tool
Use U/S gel
Generator inside produces sound energy at a certain frequency
Transducer crystal converts electrical signal into sound
Takes U/S energy to skin to body, then reverses it to listen for echoes
Happens in real time (movie not photograph)
The bigger the machine, the better/deeper
The lower the sound frequency, the deeper the penetration, the lower the resolution (fuzzy, blurry pic)
Reflected sonics produce an image
Look for fluid-filled structures = hypoechoic (black)
Look for reflections = hyperechoic (white)
Flexible Endoscopy
More than 180* flexible (can look at itself)
Direct imaging technology
Operating channel to insert instruments
Water, air and suction in tip
Snake light is covered with vinyl
Powerful light source
Camera
Endoscope facts
2 Types:
- flexible
- rigid
Procedures are always done under anesthesia!
Xenon arc lamp (may have been replaced w/LED) connected to fiber-optic fibers (extremely delicate)
Don’t let dog bite it or be harsh washing or storing them
The meaning of flexible
180*
Can look at itself
Can get a piece of tissue
Send grasping forceps through here to grap foreign objects
Ears, rears, horse’s nose to larynx, esophagus, stomach, duodenum, colon, vagina (full flexibility, light, …)
Flexible endoscopy - horse!
Rigid Endoscopy
Stiff pipe
Light source
Camera
Water supply
Suction
Viewing system
Used for athroscopy, video otoscope, bladder
It’s called a band aid Sx (minimally invasive)
Which type, flexible or rigid, would you use?
Sx = rigid!
Tube, diagnositc = flexible!
