Radiolucent

Radiopaque

Gas in an xray is________________(radiopaque/radiolucent)

and __________(black/white)

Bone in an xray is________________(radiopaque/radiolucent)

and __________(black/white)

1. evaluate GIT abnormalities (including vomting, regurgitation, persitant diarrhea, ineffectual/pain during defecation, abd pain, abd masses, abd distention

2. screening procedure for diseases with obscure clinical signs

3. survey rads prior to contrast radiography

-fast 12 hours

-sedation/general anaesthesia (maybe)

-min 2 views, lateral (RL or LR) and VD (or DV but VD is preferred for GIT)

1. readily available

2. relatively eay to preform

3. interpretation difficult at first, but improves with experience

4. cost effective

5. multiple indications; provides lots of information

1. 2D of 3D structures which mean there is silhouetting and summation of overlapping structures

2. rarely give final etiologic disgnosis (although can indicate next step and give limited number of differential diagnoses)

3. may need GA or at least sedation

4. soft tissue structures can be difficult to visualize due to lack of contrast

5. uses ioinizing radiation

substances that are more radiopaque than bone therefore appear white on film

eg barium (liquid or BIPS) or organic iodinated contrast

substances with low specific gravity that are more radiolucent than fat and soft tissue

eg air, CO2 O2

-aid in visualization of internal architecture of an organ; allow detection of changes in size, shape, location, and mecosal pattern of an organ; to asses the mucosal surface and luminal contents of an organ 

-evaluate organ fucntion (motility, rate)

-investigate # of GIT abnormalities and clinic signs (vomiting, suspected abd masses, foreign bodies, abd pain, diarrhea, intussusception {where the one part of intestine invaginates another}, colitis)

-supplement of confirm information from plain rads

What is the general procedure of contrast radiography?

Upper GIT:

fasted for 12-22 hours

contrast admin'ed orally or via tube

rads taken at intervals

final is taken 12 hours after admin of contrast

Lower GIT:

fasted for 36 hours

admin'd rectally

rads taken at intervals

both require:

evacuation of colon

cessation of drugs affected GIT

Fill in the parts of the GIT that each of these types of procedures assess

barium swallow_____1______

gastrogram______2_____

Upper GIT series ______3______

Barium enema  _____4_______

barium swallow 1. Esophagus

gastrogram 2. Stomach

Upper GIT series 3. SI and to some extent the colon

Barium enema 4. Large intestine

1. multiple indications and can provide more info than plain rads

2. relatively easy to preform

3. readily available

4. cost effective

1. more invasive and still can have the problem of superimposed structures as with plain rad

2. aspiration of barium (potential for pneumonia and pulmonary granuloma formation)

3. if GIT perforation exists, leaking barium can lead to severe rxns

4. multiple rads make it time consuming and more expensive than plain rads

5. may require GA or sedation

- assessment of swallowing

- complete functional examination of esophagus

- investigation of megaesophagus and presence of air/food in esophagus

- investigation of both site and functional problem involved in swallowing disorder

- investigation of regurgitation

- direct observation of gastric peristalsis and gastric emptying

-fasted for 12-24 hous

-for esophagus, 3-6 completed swallows of both solid and liquid boluses (barium impregnated)

1. enables direct assessment of esophagus FUNCTION

2. enables visualization of sequential changes in the shape of the stomach

3. enables good assesssment of motility

4. animal is conscious, so decreased chance of aspiration

5. cost effective (after equipment is purchased)

1. limited availablity

2. longer periods of radiation exposure for staff

3. limited indications

4. equipment is expensive

hyperechoic (or echogenic or echo rich)- white

hypoechoic (or echo poor)-blacker than above

echolucent (anechoic or echo free)-black

-assess motility (eg peristalsis in real time), assess wall thickness and architecture of the layers of the GIT, examination of luminal contents

-diagnose # of GIT abnormalities including gastric and intestinal foreign bodies, intussusception, GIT neoplasia, gastric ulcers and ileus

-fasted

+/- sedation

abd is clipped

acousti gel is applied

-superior to rads for studying soft tissue

-economical (cheaper and faster than contrast series)

- enables imaging in tomographic (cross sectional) plane

- permits id of internal structure of an organ or mass

- enables non-invasive evaluation of organ motility

-u/s guided biopsy

-portable

-safe, no radiation

-min prep is needed

- gas and feces can prevent imaging of deeping structures

-hard to learn how to interpret (to use the tool and the know the normal anatomy)

-requires significant experience and expertise

- directly examine mucosal surface and some submucosal tissue

- investigate a # of problems including chronic regurgitation or chonic vomiting

- investigate animals with hx of straining to defecate, blood in feces, constipation or chronic dirrahea

upper GIT:

fasted for 18-24 hrs

deprived of water for 4-8 hrs

lower GIT:

complete evacuation of feces

fasted for 36 hours (for above) or pref 48-72 hours

multiple enemas

GA

-permits examination of the mucosal surface, direct visualization of lesions and biopsy collection with min disturbance

-more likely to get definite diagnosis (compared to rad)

-no radiation or harmful chemicals

- rapid and relatively non-invasive technique with few post-op complications

- becoming more affordable

portable

What are the disadvantages of endoscopy?

- not readily available

- thorough knowledge of anatomy required

- risks associated with GA

- very high contrast resolution

- once data is collected, can be displayed in numerous ways

-CT uses very short scan times and therefore less chance of movement artefact

-oral/rectal contrast studies can be preformed

-$$

-limited availability

-GA

- radition

- soft tissue not as good as MRI

- images are only obtained in the tranverse plane in which the patient is lying

- difficult to visualize abd organs without contrast studies

bright/white increased signal intensity

dark/black structures have decreased signal intensity

- provides superior soft tissue anatomic detail, contrast and resolution

- no ionizing radiation

- images can be transverse, sagittal and dorsal planes with equally good definition

- contrast studies are also available

-$$$$

-Limited availability

- GA
- motion artefacts (esp with upper abd)

Radiopaque

mineral

bone

muscle

fat

gas

radiolucent

contrast (radiopaque)- fundus and pylorus

gas (radiolucent)- greater curvature

typical of linear obstruction

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