Contrast Imaging Of The Head And Spine

Question 0

What is object contrast?

Answer 0

Difference in radiographic grey tones between two radiographer structures due to their physical differences

Question 1

What is the definition of image contrast?

Answer 1

Degree of perceptible difference between two colour tones.
High is black and white
Low is grey and grey

Question 2

What is film contrast?

Answer 2

The ability of an X-ray film to produce a degree I image contrast

Question 3

How do fat and radiographic contrast interact?

Answer 3

Fat enables soft tissue contrast by preventing silhouetting. But in excessive quantities it decreases contras due to the high Kv necessary for penetration

Question 4

How does gas and contrast interact?

Answer 4

Gas surrounding abdominal organs enhances contrast and it can be used as a negative contrast medium

Question 5

What is a contrast medium and how are they applied?

Answer 5

Substance that is applied to the patient to enhance the natural contrast of the organ. Applied by iv, per vagina, rectal urethral
Always take normal X-ray first

Question 6

What is negative contrast media?

Answer 6

Do not absorb X-rays = radiolucent such as air or carbon dioxide. They outline hollow organ walls- displacement, distension or wall mass
Simple and cheap
Don’t over fill or you will rupture the organ or cause a gas embolism

Question 7

Why is positive contrast media?

Answer 7

High absorption of X-rays they are very radiopaque. Barium sulphate ONLY for GI tract, iodinated compounds. For outlining surface of hollow organs, vessels and ducts. Organ displacement or filling defect.

Question 8

What is barium sulphate used for?

Answer 8

Only the GI tract, it will form granulomas if it leaks- only use if no risk of puncture. It coats the mucosa. It is inert and not metabolised or absorbed used for barium enema study

Question 9

What are the positive and adverse effects of barium?

Answer 9

Muco protective coating- prevents toxin binding
Causes granulomas or adhesions in the peritoneal cavity
Aspiration can cause airway obstruction and hypoxia

Question 10

What are BIPS?

Answer 10

Barium impregnated polyethylene spheres- given orally and radiographs taken at intervals to show any abnormalities

Question 11

How does iodinated contrast media work?

Answer 11

The ionic contrast ones- They dissociate into cations and anions-hyperosmolar. Target are cheap e.g. Iothalamate
The non ionic ones do not dissociate and are isosmolar but more expensive and safer and should be used for myelography

Question 12

How is iodinated contrast media excreted?

Answer 12

90% via glomerular filtration. Specific contrast media for biliary excretion, if there is renal failure it will be biliary and GI

Question 13

What are the adverse reactions to iodinated contrast media?

Answer 13

Iodine allergy-rare but they are reduced withy the non ionic ones. Can show acute renal failure, vomiting and hypotension

Question 14

What are some applications of iodinated contrast media?

Answer 14

Intravenous urogram, positive contrast cystography, angiography

Question 15

How is contrast media used for filling defects?

Answer 15

The structures surrounded by the positive contrast will appear less opaque than the contrast medium. Otherwise they would by be noticed. Lots of positive contrast can overshadow the defect

Question 16

What is a double contrast study?

Answer 16

Positive and negative media for the GI tract.
It highlights the mucosa with positive contrast while giving a dark background with negative contrast. No overshadowing occurs with filling defects

Question 17

How is contrast media user in computed tomography?

Answer 17

Following a survey scan. For looking a neoplasia, vascular anatomy and abnormalities and filling defects, inflammation, abscesses and cysts

Question 18

What type of diseases affect the cranium and associated structures?

Answer 18

Inflammatory, congenital, metabolic and neoplastic

Question 19

What would you see in periodontal disease?

Answer 19

Gingival retraction, alveolar bone lysis, tooth root lysis

Question 20

What can be seen in congenital diseases?

Answer 20

Occipital dysplasia
Occipital malformation
Hydrocephalus shows. Done shaped cranium, thin cortices and open frontalles

Question 21

What is seen with metabolic bone disease?

Answer 21

Primary which is rare and the secondary which is the more common form.
Increased PTH, increased calcium reabsorption from bone and hypercalcaemia

Question 22

What materials are used for contrast media in Magnetic Resonance Tomography and what can it show?

Answer 22

No iodine, paramagnetic metals are used such as gold to enhance compared to the neighbouring molecules. It works by increased contrast uptake- increased vascularity, leaky vessels and BBB disruption.

Question 23

How is contrast media used in ultrasound and how does it work?

Answer 23

It is given by IV and enhances blood flow. It works by sound reflection by gas bubbles- saline ones will burst in lung capillaries so expensive encapsulated ones are used. As the bubbles oscillate they create a harmonic wave, max signal if the bubble is destroyed sonographically

Question 24

What would be seen on X-ray of an animal with secondary hyperparathyroidism?

Answer 24

General bone demineralisation, lamina dura loss, fibrous tissue hyperplasia- seen more in young than old.

Question 25

What type of neoplastic diseases can be seen in the nasal cavity?

Answer 25

Carcinomas- more common e.g. adenocarcinoma, squamous cell carcinoma.
Sarcomas- less common e.g. fibrosarcoma, osteosarcoma.

Question 26

What are the Roentgen signs of nasal neoplasia?

Answer 26

Increased opacity, Turbinate destruction, local bone lysis of the cribiform plate, nasal septal deviation. (look at on CT or MRI)

Question 27

What are the two types of Rhinitis and what is seen in each case?

Answer 27

Destructive- fungal (aspergillus spp) difficult to differentiate from neoplasia. Turbinates are eroded.
Non destructive- Bacterial, inflammatory response and lymphoplasmoltyic due to the foreign body.

Question 28

What are the Roentgen signs of otitis?

Answer 28

Thickened bullae and ear canal mineralisation. (chronic otitis externa or otitis media)

Question 29

How successful is radiography when looking at the spinal column?

Answer 29

Good for bony lysis or proliferation, collapsed disc spaces and fractures. There is very good spatial recognition but the superimposition of structures hinder the resolution. Insensitive for localising and diagnosing many neurological diseases.

Question 30

What is myelography?

Answer 30

Contrast medium is injected into the subarachnoid space which outlines the spinal chord.

Question 31

What are the pros of Myelography?

Answer 31

It is relatively inexpensive,
requires no special equipment
outlines the chord well
sufficient for localising most lesions

Question 32

What are the cons of myelography?

Answer 32

It is invasive,
there are sides effects that include seizures,
technically challenging
can be non-diagnostic and gives less info than other methods (not really used)

Question 33

What are the Roentgen signs used in myelography?

Answer 33

Contrast column signs:
deviation (give direction)
thinning or stop
split

Question 34

What problems occur that can be seen in myelography?

Answer 34

extradural compression- intervertebral disc disease (small dogs), if abaxial extradural compression- the split sign (chord is in two parallel strands)
Intradural-extramedullary (very rare)- caused by neoplasia “golf tee”
Intramedullary- swelling and distension due to oedema, haemorrhage, neoplasia. (uncommon) Will see thinning of the ventral and dorsal chord due to compression