Contrast Media in Imaging

1. IN THE NAME Of GOD
Amir al-Muminin, peace be upon him, said:
There is no wealth like wisdom, no destitution like ignorance, no
inheritance like refinement and no support like consultation.
‫املومنين‬‫ر‬‫امي‬(‫ع‬)‫فرمودند‬:
‫هيچ‬‌‫ي‬‫‌نياز‬‫ي‬‫ب‬‌‫ن‬‫چو‬،‫عقل‬‌‫و‬‫هيچ‬‌‫ي‬‫فقر‬‌‫ن‬‫چو‬‫ناداني‬،‫نيست‬‫هيچ‬‫ثي‬‫ر‬‫ا‬‌‫ن‬‫چو‬،‫ادب‬‌‫و‬‫هيچ‬
‫پشتيباني‬‌‫ن‬‫چو‬‫ت‬‫ر‬‫مشو‬‫نيست‬.

2. Contrast Media
September, 2014
Prepared by:
Behzad Ommani
Bachelor of Radiology
Master of Medical Engineering
Instructor Radiology Group

3. Extravasation

4. Patient Factors
Infants, small children and unconscious patients are more likely to develop
extravasation.
Patients receiving chemotherapy are also at a higher risk of extravasation
because chemotherapy may cause fragility of the vein wall.
Patients with arterial insufficiency (e.g. atherosclerosis, diabetes mellitus) or
compromised venous drainage (e.g. thrombosis) or lymphatic drainage (e.g.
radiation therapy, surgery or regional node dissection) are less able to tolerate
extravasation than those with normal circulation.

5. Mechanisms and Toxicity
Multiple factors are involved in the pathogenesis of extravasation
injuries.
The first factor is osmolality above water.
The second factor is the cytotoxicity of contrast media.
The third factor is the volume of extravasated contrast medium.
The fourth factor is the mechanical compression caused by large-
volume extravasations.

6. Clinical Picture
Symptoms of extravasation are very variable.
On physical examination, the extravasation site appears swollen, red
and tender.
Most extravasation injuries resolve spontaneously within 2–4 days.
These symptom include skin blistering, altered tissue perfusion,
paresthesia, and increasing or persistent pain after 4 h.

7. Treatment
There is no consensus about the best approach for the management of
extravasation. The methods described in the following sections
have been used:
 Elevation of the Affected Limb
Elevation is often useful to Reduce Edema by decreasing the hydrostatic pressure in
capillarie.

8.  Topical Application of Heat or Cold
Heat produces vasodilatation and thus resorption of extravasated fluid and edema,
while cold produces vasoconstriction and limits inflammation.
The immediate application of warm compresses reduced the volume of extravasated
fluid in healthy volunteers.
In patients, who have suffered from extravasation, cooling can be produced with ice
packs placed at the injection site for 15–60 min three times a day for 1–3 days or
until symptoms resolve.
Treatment

9.  Prevention of Secondary Infection
Applications of silver sulfadiazine ointment are recommended by many plastic
surgeons whenever blistering is evident
Treatment

10.  Aspiration of Fluid from the Extravasation Site
Aspiration of fluid from the injection site is controversial, as it usually removes only
a small amount of extravasated fluid and carries a risk of infection.
Treatment

11.  Hyaluronidase and DMSO (Di methyl sulfoxide)
Hyaluronidase is an enzyme that breaks down connective tissue and facilitates
absorption of extravasated drugs into the vascular and lymphatic systems.
It should be administered within 1 h of extravasation to obtain quick dissipation of
the skin swelling.
Treatment

12. DMSO is a free-radical scavenger and an effective solvent.
It is effective in preventing ulceration caused by extravasated doxorubicin, but its
efficacy has not been proven for treating extravasation of contrast media.
Treatment

13.  Surgery
Surgical drainage or emergency suction applied within 6 h can be effective (Loth
and Jones 1988) and the use of emergency suction alone or combined with saline
flushing have also been helpful.
Treatment

14. Risk Factors for Acute Idiosyncratic
Reactions

15. Type of Contrast Agent
With the older high osmolality ionic agents the rate of reactions of
all types is in the range 5%–12%.
Concluded that 80% of contrast media reactions could be
prevented by using low osmolality agents.
In Katayama et al.’s (1990) series there was no significant
difference in mortality between the ionic and nonionic agents, but
other data suggests a lower mortality with nonionic agents.

16. Previous Contrast Medium Reaction
A previous reaction to an iodinated contrast medium is
the most important patient factor predisposing to an
acute idiosyncratic reaction.
When a patient who previously reacted to an ionic agent
is given a nonionic agent, the risk of a repeat reaction is
reduced to approximately % 5.

17. Asthma
Asthma is another important risk factor. Research (1975) show
that 11% of asthmatics had a reaction to ionic contrast media.
(1980) stated that the risk of reaction to ionic agents was increased
five times in an asthmatic.
In patients with asthma, Katayama et al. (1990) described an 8.5
times increased risk with ionic agents and a 5.8 times increased
risk with nonionics.
 Other conditions, such as hay fever, eczema,
etc. are associated with an increased risk of
reaction, but by a lesser amount than asthma.

18. Allergy
A history of allergy to foods, drugs or other substances is
associated with an increased risk of contrast medium
reaction, usually by a lesser amount than a history of
asthma.
Allergy to foodstuffs which contain iodine, e.g., seafood,
often causes particular anxiety. However, the available
data suggests that allergy to seafood is no more
significant than allergy to other foodstuffs.

19. Drugs
Whether or not ά blockers affect the incidence of idiosyncratic
contrast medium reactions is controversial.
found that ά blockers did increase the risk of reaction. It is
however agreed that the use of ά blockers can impair the response
to treatment if a reaction does occur.
Patients who are receiving or have received interleukin-2 are at
increased risk of adverse events following iodinated contrast
media.

20. Prevention of Acute Idiosyncratic Reactions

21. Choice of Contrast Medium
The single most important method of reducing the risk of
idiosyncratic contrast medium reactions is to use nonionic low
osmolality agents which are associated with a four to five times
lower risk of reactions.
When there has been a previous reaction to nonionic iodinated
contrast medium, the use of a different agent is appropriate.

22. Premedication
Most frequently steroids with or without additional H1
antihistamines have been recommended, and other drugs, such as
ephedrine and H2 antagonists have also been tried.
In patients who had previously reacted, or who had a history of
allergy or severe cardiopulmonary disease, H1 and H2 antagonists
reduced the reactionrate to 2% in 1047 patients, as compared to a
reaction rate of 4.37% in those who were not premedicated .
(Fink et al. 1992).

23. In patients who have previously reacted to ionic contrast media, a
combination of steroid and H1 antihistamine reduces the repeat
reaction rate, estimated to be 16%–35% without premedication.
The addition of the below drug pre medication recommended :
 H2 antagonist cimetidine
 Steroid
 Antihistamine
 ephedrine
Premedication

24. Pretesting and Injection Rate
The practice of pretesting – giving a small preliminary test dose of
contrast medium intravenously before the full dose is given – has
been shown to be of no value (Shehadi 1975; Fischer and Doust
1972; Yamaguchi et al. 1991).
Fischer and Doust (1972) found the mortality after contrast
medium was unaffected by pretesting and that deaths could occur
following a negative pretest or following the pretest itself.
Yamaguchi et al. (1991) found no benefit of pretesting either with
ionic or nonionic agents.
Injection rate does not appear to have any effect on the rate of
adverse reactions (Jacobs et al. 1998).