Contrast media are substances used in medical imaging to increase the visibility of internal structures. There are different types of contrast media including iodine-based contrast agents used for CT scans and X-rays, gadolinium-based contrast for MRI, and barium sulfate for imaging the gastrointestinal tract. The properties of contrast media including iodine concentration, viscosity, osmolality, and miscibility determine their radiopacity and potential toxicity. Patients with renal impairment or allergies may require premedication such as steroids prior to contrast administration to reduce risks.

1. BY: MOHAMAD YUSRI AMRI BIN GHZALI

2. A substance placed in the body to increase image
differentiation of anatomical structures.
It increases the differentiation between the areas
containing contrast media and the areas not containing
contrast media.

5. High Osmolar Contrast Media (HOCM)
 Composed of salts which dissociate in water
into anions (radiopaque) and cations
(osmotically active).
 Osmolality up to 5x serum -toxicity.
 Non-intravascular route – oral / rectal.
 Not for use in subarachnoid space.
 E.g. Gastrografin, Urografin, Isteropac

7. Low Osmolar Contrast Media (LOCM)
 -Non-dissociating.
 -Only about 2x serum osmolality.
 -Less side effects, less nephrotoxic.
 E.g. Ultravist, Omnipaque
Iso-osmolar Contrast Media
 -Osmolality approximately serum osmolality.
 -Preferred in renal impaired patients.
 E.g. Visipaque

9. 1.Iodine concentration
 the change that more x-ray photons will be
absorbed therefore that particular CM maybe
more radiopaque than a comparative low
iodine concentrated CM. The higher the
iodine concentration, the greater the risk of an
adverse reaction .

10. 2.Viscosity
◦ Describes the THICKNESS or RESISTANCE
to flow of contrast agent.
◦ Related to the concentration, the size of the
molecules in a specific contrast agent and the
temperature of the contrast agent.
◦ Determine the force that is required to inject it
through a needle or catheter into a patient.
◦ Viscosity can be reduced by lowering the
concentration of the contrast medium BUT
reducing the iodine concentration may also
result in unsatisfactory opacification.

11. 3.Osmolality (related to blood plasma)
◦ Measurement of the number of MOLECULES
and PARTICLES in a solution per kilogram of
water.
◦ May also be described as a measurement of the
number of molecules that can crowd out or
displaced water molecules in a kilogram of
water.
◦ Osmolality of contrast media solution is being
simply a function of the concentration of
particles within it.
◦ Concentration of particles (osmoles) per unit
weight (kilograms) of solvent (mOsm/kg H2O)

12. 4. Miscibility
 Contrast agents should be readily miscible with
blood.
5. Toxicity
 Potential toxicity is greater with higher-
concentration agents and ionic agents, viscosity
also increase as room temperature decrease.

13.  Barium CM are used to diagnose
abnormalities of the gastrointestinal tract, such
as tumors, ulcers and other inflammatory
conditions, polyps, hernias, and strictures.
With the use of barium sulfate, a metallic
chemical that x-rays cannot pass through, x-
rays are taken of the area under examination.

15. 1.AIR
 As in the picture on the right where both air and barium
are used together air can be used as a contrast material
because it is less radio-opaque than the tissues it is
defining. In the picture it highlights the interior of the
colon.
2. CARBON DIOXIDE
 Carbon dioxide also has a role in angiography. It is
low-risk as it is a natural product with no risk of
allergic potential. However, it can be used only below
the diaphragm as there is a risk of embolism in
neurovascular procedures. It must be used carefully to
avoid contamination with room air when injected.

16.  Proven/suspected hypersensitivity to iodine
 Previous severe reaction to contrast media
 Asthma/significant allergy history
 Heart disease
 Infants/children/elderly
 Liver failure
 Renal impairment (moderate-severe) – NIDDM on Metformin
 Myelomatosis
 Poor hydration
 Sickle cell anaemia
 Thyrotoxicosis
 Pregnancy
 Phaeochromocytoma

17. 1 Adults:
 50mg Prednisone PO 13, 7 and 1 hour before
the injection.
 50mg Benadryl (Diphenhydramine) IV/PO
within 1 hour of the injection.
2. In an emergency setting an alternative faster
(but less proven) regime is:
 200mg Hydrocortisone IV 4 hours before
injection.
 50mg Benadryl (Diphenhydramine) IV/PO
within 1 hour of the injection.

18.  50mg Benadryl (Diphenhydramine) IV/PO
within 1 hour of the injection.
3. Pediatrics (For patients less than 50kg):
 Prednisone 0.7mg/kg (not to exceed 50mg) PO
13, 7 and 1 hour before the injection.
 Benadryl (Diphenhydramine) 1mg/kg IV/PO
(not to exceed 50mg) within 1 hour of the
injection.
4. In an emergency setting an alternative faster
(but less proven) regime is:
 Hydrocortisone 1mg/kg (not to exceed 200mg)
IV 4 hours before injection.
 Benadryl (Diphenhydramine) 1mg/kg IV/PO
(not to exceed 50mg) within 1 hour of the
injection.

19. 1.Fasting 4-6 hrs
2.Steroid cover – allergy, asthma
 T. prednisolone 50 mg 13, 7, 1 hr before
examination
 IV hydrocortisone 200mg stat
3. Renal impairment
 N-acetyl cysteine 600mg the day before and 1
day after examination

20. 1.Hypersensitivity reaction
2.Nephrogenic systemic fibrosis
 -Recently reported serious late adverse
reaction of gadolinium-based contrast.
 -Seen in patients with renal failure and on
dialysis.
 Fibrosis of skin and organs.

21.  Clinical symptoms developed 2-8 weeks after
exposure to gadodiamide.
 Avoid in patient with creatinine clearance
<15mL/min