1. RAD 323
Lecture. 1
CONTRAST MEDIUM

2. References Radiographic procedures: By Stephen Chapman
Positioning in Radiography: By k.C.clarke.
Text book of radiographic positioning and related
anatomy;bykenneth L.Bontrager,5th edition
Websites

3. Learning objectives
By the end of this Lecture the student will be able to:
Define the term contrast
Differentiate between subject and radiographic contrast
Identify the subject contrast chart in relation to material type
Differentiate between long scale and short scale contrast
Explain contrast Media Properties
Explain different types of contrast media used in GIT exams
Explain pharmacological agents used in GIT exams
Differentiate between Retrograde and Antegrade GIT studies

4. Contrast Definitions "contrast" "radiographic contrast"
exhibit noticeable differences when compared
"radiographic contrast"
visible differences between densities on an image
"subject contrast"
difference in the transmission of x rays due to the tissue type in the body part

5. Subject Contrast Definitions
radiolucent
tissues that x rays easily penetrate
appear dark gray to black on the image
radiopaque
tissues that x rays do not penetrate easily
appear light gray to white on the image

6. Subject Contrast Chart
Very radiolucent
Moderately radiolucent
Intermediate
Moderately radiopaque
Very radiopaque
Black
Dark grays
Gray
Light gray
White (clear)
Gasses
Air
Fatty tissue
Muscle
Cartilage
Blood
Cholesterol stones
Uric Acid
Stones
Bone
Calcium stones
Metals

7. Radiation Quality Low kVp High contrast Black and White Short Scale
Great differences in adjacent structures
High kVp
Low contrast
Many shades of gray
Long Scale
Little differences in adjacent structures

8. Radiographic Contrast vs. Contrast Media
Difference between adjacent densities in a radiograph.
The films or images have different levels of density – different shades of gray
X-rays show different features of the body in various shades of gray.
The gray is darkest in those areas that do not absorb X-rays
well – and allow it to pass through
The images are lighter in dense areas (like bones) that absorb more of the X-rays.

9. Radiographic Contrast vs. Contrast Media
Contrast Media: Diagnostic agents that are instilled into body orifices or injected into the vascular system, joints, and ducts to enhance subject contrast in anatomic areas where there is low subject contrast.
CONTRAST
X-RAY DYE
DYE

10. Purpose of Contrast Media
To enhance subject contrast or render high subject contrast in a tissue that normally has low subject contrast.

11. Contrast Media Properties
able to show organ better
physiologically
no permanent alteration of organ
non toxic
able to be eliminated / excreted

12. Contrast Media Negative contrast Radiolucent -AIR
Low atomic # material
Black on film
Positive contrast
Radiopaque
-BARIUM
High atomic # material
White on film

13. Contrast Media and Pharmacological Agents for GIT Exams

14. Barium Sulfate: BaSO4 contraindications perforations of GI tract
High atomic number
Not soluble in water = suspension
Used to coat the lining of organs
Supplied in different thicknesses
Used
Esophogram, UGI, Small Bowel, Lower GI or BE
contraindications
perforations of GI tract
proximal to an obstructed bowel
precautions
adequate hydration post examination

15. Gastrografin or Hypaque
High atomic #
Close to iodine
Water soluble
Similar usage as Barium
Water soluble, safe in the abdominal cavity
Safe to use if perforation is suspected
Very harmful to the lung tissue
Do not use if aspiration is possible

16. Why use Barium Sulphate?
It has a high atomic number (Z=56)
Non-toxic
Relatively cheap
body cannot metabolize BaSO4

17. Pharmacological agents
Buscopan
Glucagon
Maxalon
Why are they given?

18. Pharmacological agents
Buscopan (20mg iv) & Glucagon (0.3mg iv) both relax smooth muscle (Glucagon more potent & can be used on patients with glaucoma & cardiovascular disease).
Useful in barium enema examinations.
Maxalon (20mg iv/oral) increases gastric peristalsis (useful in follow through examinations)

19. Exams of the GI tract Antegrade studies
(with the normal flow)
esophagus, stomach, small bowel
contrast
barium
barium + air
oral iodine solution
BaSO4 Only
BaSO4 + Air

20. GI Studies (cont.) Retrograde studies (against the flow) colon
contrast
barium
barium + air
BaSO4 Only
BaSO4 + Air

21. Classification of C.M 1.Negative Contrast Media:
These are contrast media which have:
- Low atomic numbers.
- So low densities.
- Provides negative contrast.
Examples: air, nitrogen, oxygen, and carbon
dioxide, etc.
UNIT VII

22. 2. Positive Contrast media: These are contrast media which have:
- High atomic numbers.
- High densities.
- Provides positive contrast.
Examples:
i) Barium sulphate.
ii) Organic iodine compounds.
UNIT VII

23. UNIT VII

24. Routes of introduction of C.M.
Positive contrast media may be introduced by one of the following methods:
1- Intra-vascular injection:
Examples: Arteriograms, venogram, and lymphangiogram.
2- Ingestion:
Examples: Ba meal oral cholecystography.
UNIT VII

25. Routes of introduction (continues)
3-Injection directly into the site of interest:
Examples: Cystogram and retrogradepyelography.
4- Administered I.V. or ingested and then excreted or concentrated by the organ(s) under examination: Examples: Excretion urography and oral cholecystography.
5- Injected and then caused to move (usually by postural changes) to the site of interest: Example: Myelography.
UNIT VII

26. Factors Influencing the choice of Contrast Media
1. Appropriateness:
The C.M chosen should be appropriate for the necessary examination or investigation e.g Ba-sulphate for Ba meal, Omnipaque for myelogram
2.Acheivable radio-opacity:
The contrast medium should provide the desirable degree of radio-opacity.
UNIT VII

27. 4.Viscosity: 3.Toxicity and /or side effects:
The contrast medium must be safe and non-toxic both locally where it is administered and elsewhere in the body that it may reach.
i.e. it should not produce any unwanted effect on the body in general.
4.Viscosity:
For some examinations such angiocardiography
a relatively low viscosity is desirable to enable rapid injection of a large volume of contrast medium .
UNIT VII

28. For examinations where the contrast medium is injected and stays in the organ or dissipates slowly from it (e.g H.S.G.) , a more viscous contrast medium can be used.
5. Cost:
The C.M. should be reasonably priced and affordable.
6. Persistence:
Some contrast may remain in the body for several years and are thus of use in assessing progress by continuing to show any change in the size of the contrast filled lesion without further injection.
UNIT VII

29. 7. Miscibility:
For some examinations like cyst puncture, the contrast should mix with the fluid into which it is injected.
In other words it should mix with the body fluid (e.g. CSF and urine )
UNIT VII