Pharmacology And Contrast Agents Flashcards
How can we administer contrast?
ORAL – SWOLLOWED,
passing DOWN AN NG/NJ
TUB
› INTRAVENOUS (IV) – VIA A
CANNULA
› Intra-articular – Arthrogram
after joint injection of
contrast
› RECTAL – VIA A CATHETER;
LIQUID/PASTE
› DIRECT (INTO URINARY
(CYSTO-URETHRAL) &
BILIARY ETC.) – CATHETER,
ENDOSCOPE &
› VAGINAL – USING A
CATHETER OR CANNULA
How would contrast appear on X-ray imaging
When describing areas of higher or
lower density on X-rays images we use
the term Radiopaque and Radiolucent
e.g. contrast would be Radiopaque
How would contrast appear on CT imaging
When describing areas of higher or
lower perfusion on CT images we use
the term Hypodense, Isodense and
hyperdense e.g. contrast agent is
hyperdense
Negative contrast media
Negative contrast media
› CT colonography with
carbon dioxide gas (contrast
agent)
› Abdominal CT with water
(contrast agent
What is Barium-Sulfate (swallow/meal) & Gastrografin?
Barium Sulfate
› Insoluble
› Used in single and double contrast studies.
› Bowel perforation can cause peritonitis leading to infection.
› Barium sulphate in lungs can cause aspiration pneumonia
› Side effects diarrhoea and white stool so must eat lots of fiber and drink
water.
› Clear from bowel 2-3 days
› Contraindication: perforation,
pregnancy and complete bowel
obstruction
Iodinated contrast media: ionic and non-ionic contrast
Ionic-contrast
- Dissociates into separate ions
when injected - Creates hypertonic conditions
- Increases in blood osmolarity
- Less expensive
- More reactions/sides effects
Non Ionic-contrast
- Doesn’t dissociate
- Remains near isotonic
- No significant increase in blood osmolarity
- More expensive
- Less reactions/side effects
Pharmacological & Physiological effects of iodinated contrast media
› Clinically we tend to use non-ionic, low viscosity and isoosmolar contrast
media e.g. omnipaque
› Fewer interaction due to chemical composition thus less side effects
› Nausea and vomiting – occurs due to temporary reactions in the GI tract
possibly due to metallic taste
› Hypotension - caused by ↑osmolarity↓heamatocrit leading to vasodilation
› Excretion – filtered from kidneys half
life of 1-2h
Side effects of Iodinated contrast media
Nausea and vomiting
Headache
Itching
Flushing
Mild skin rash or hives
Moderate side effects:
Severe skin rash or hives
Wheezing
Abnormality heart rhythms
High or low blood pressure
SOB/ difficulty breathing
Tell doctor immediately effects:
Difficulty breathing
Profound low blood pressure
Swelling of the throat or in any other areas.
Types 2 Diabetes & Metformin
Metformin acts as an inhibitor molecule and binds to kidney competing with the iodinated contrast.
Contrast Induced Nephropathy (CIN)
› Acute deterioration of the renal function after administration
of contrast
› Definition – elevation of serum by 25 0r 0.5mg/dl (44.2umol)
› Typically occurs 3 days with administration of contrast
› Prevention is HYDRATION
› Damage to the kidneys in particular the medulla through
vasoconstriction
contrast agents - Lipiodol
› Naturally occurring oil-based contrast medium made from
poppyseed + Iodine.
› Lipiodol should be administered into a lymphatic vessel under
X-ray guidance.
› Used in CT examination particularly for the lymphatic system
and salivary glands.
› Very sensitive for hepatocellular carcinoma (HCC)
MR Contrast media: paramagnetic and super paramagnetic
paramagnetic
› Acts as positive contrast
media
› lowers the T1 relaxation
time
› e.g. Gadolinium &
Manganese
super paramagnetic
› Acts as negative contrast
media
› lowers the T2 relaxation
time
› e.g. Iron-oxide (renovist)
Examples of Paramagnetic Imaging - Gadolinium
› Diagnose inflammation, tumors and blood clots
› Helps to diagnose and monitor the progress of serious health conditions such as cancer
› During MRI scans contrast injected into patients.
› Is a rare, silvery-white earth metal called gadolinium.
› It reacts with atoms and molecules in the body to make them easier to see in imaging scans.
Other Sources Of MR imaging - Manganese
› Pineapple, blueberry and cranberry juice
› Used as negative contrast agents
› Taken orally
› Used in MRCP Imaging
› Pineapple juice suppresses the signal intensity in the stomach and duodenum on the T2 weighted images
› Hepatic duct, Gall bladder and the Pancreatic duct appear white due to the water content
Sides effects of Gadolinium
Headache
Nausea
Dizziness
Cold sensation when injected
Rare:
Nephrogenic systemic fibrosis
Itchy skin
What is Ultrasound – CM (SonoVue)?
Ultrasound – CM (SonoVue)
› Administered through IV
› Microbubbles are presented within the vessels
› Ultrasound waves bounce back from the bubbles and increase in power.
› They are mainly used in focal lesions
› Made up from a sulfur-hexafluoride gas and phospholipid shells.
› They are 2-3 microns in diameter which is smaller than Red blood cells.
› They stay in the circulation and exit through lungs.
› Possible Alternative for renal impairment
