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. Mixing Contrast Media with Other Drugs
Contrast media should not be mixed with other drugs before
intravascular use (Kim et al. 1992). A mixture may change the
stability of the drugs. It is also advisable not to inject other drugs
through the same venous access used for contrast media injection.
If the same venous access is used, there
should be adequate flushing with normal
saline first.

4. Classification of Drug Interaction
The interactions between drugs and contrast agents are subdivided
into the following:
Drugs which will be retained in the body when there is contrast
medium induced reduction in renal function.
Drugs which enhance the renal effects of contrast media.
Drugs which enhance allergic-like reactions to contrast media.
Drugs which interfere with the hematological effects of contrast
media.
Contrast media and neuroleptic drugs.
Drugs which enhance the cardiac effects of contrast media.

5. Drugs which will be retained in the body when there is contrast medium
induced reduction in renal function
Contrast media may interfere with the pharmacokinetics
(distribution, metabolism and elimination of the drug) of other
drugs, particularly those which are eliminated from the body
through the kidneys.
One of the important potential – but rare – pharmacodynamic
effects of iodinated contrast media is reduction of renal function,
particularly in patients with preexisting reduced renal function.
A good example is the indirect interaction between contrast media
and metformin.
If contrast media reduce renal function, there is retention of
metformin potentially leading to the serious complication of lactic
acidosis

6. Drugs which enhance the renal effects of contrast media
Nephrotoxic drugs such as non-steroidal anti-inflammatory drugs
(NSAIDs) have the potential to increase the renal effects of
contrast media.
This class of drugs inhibits the intrarenal synthesis of vasodilatory
prostaglandins and augments the renal vasoconstrictor effect of
iodinated contrast media which may facilitate the development of
contrast media nephrotoxicity.
Other nephrotoxic drugs such as gentamicin, cyclosporine and
cisplatin may also augment the nephrotoxic effects of contrast
media.

7. Drugs which enhance the renal effects of contrast media
Diuretics such as acetazolamide, furosemide and spironolactone
may augment the diuretic effect of contrast media, particularly
those of high osmolality, leading to dehydration, increased risk of
contrast medium nephropathy, electrolyte imbalance and
hypotension.

8. Drugs Which Enhance Allergy-Like Reactions to Contrast Media
Patients receiving α-receptor blockers, interleukins or
interferons have an increased tendency to develop allergy
like reactions following the administration of contrast
media.
Delayed reactions to contrast media are more likely to develop in
patients who have received interleukin-2 (IL-2) treatment (Choyke
et al. 1992).
Hypersensitivity reactions to iodine-containing compounds have
also been described in patients with systemic lupus erythematosus.

9. Drugs Which Enhance Allergy-Like Reactions to Contrast Media
• Patients on hydralazine treatment
•systemic lupus erythematosus
 Prototypic autoimmune disease
Eitology of SLE unknown
Each patient unique

10. Drugs Which Alter the Hematological Effects of Contrast Media
Effects of Contrast Media on Coagulation
It is well established that contrast media interact with the
coagulation mechanism, with platelet activation and degranulation
and with thrombolytic drugs.
Both ionic and nonionic contrast media can prolong clotting time
and may exaggerate the effects of anticoagulant and antiplatelet
drugs.
In addition, clotting tests will be falsely elevated after the
administration of contrast media and should only be performed 6 h
or more after contrast media have been given (Parvez et al. 1982)

11. Drugs Which Alter the Hematological Effects of Contrast Media
Effects of Contrast Media on Fibrinolysis
Contrast media impede fibrinolysis and delay the onset of lysis by
recombinant tissue-type plasminogen activator (rt-PA), urokinase
and streptokinase (Dehmeret al. 1995).
In clinical practice, if coronary angiography is performed before
starting thrombolysis, the recent administration of contrast media
may reduce therapeutice success
Reocclusion of coronary arteries was more common after contrast
media administration despite concomitant aspirin and heparin
therapy.

12. Contrast Media and Drugs Acting on the Central Nervous System
Cerebral angiography may lower the fit threshold in
patients receiving antipsychotics.
Phenothiazines (chlorpromazine, perfenazine, prochlorperazine,
thioridazine)
Antihistamines (promethazine, trimeparazine)
Thioxanthenes (chlorprothixene,haloperidol, thiothrixene)
Tricyclic antidepressants (amitryptyline, desipramine, doxepin,
imipramine, protryptiline)
Butyrophenones, or analeptics (amphetamine, methamphetamine,
cocaine, methylphenidate)

13. Contrast Media and Drugs Acting on the Central Nervous System
During the time when high-osmolar content media were in general
use it was suggested that these drugs should be discontinued for
48 h before and 24 h after cerebral angiography.
However, stopping antipsychotics may lead to an increased rate of
suicide.
Today where modern nonionic contrast media are used,
antipsychotics are no longer stopped.

14. Drugs which Enhance the Cardiac Effects of Contrast Media
Calcium channel blockers prevent influx of calcium ions into the
cell affecting the tone of heart and vascular smooth muscle cells
and leading to vasodilatation and negative inotropic effects on the
myocardium.
These effects are not significant with modern low osmolar nonionic
contrast media which are less vasoactive and have minimal
negative inotropic effect on the myocardium.

15. Effects of Contrast Media on Isotope Studies
The administration of iodinated contrast media interferes with both
diagnostic scintigraphy and radioiodine treatment. The reduced
uptake of the radioactive tracer is caused by free iodide in the
contrast medium solution.
A delay before undertaking scintigraphy of 4–6 weeks for water
soluble and 12 weeks for cholangiographic contrast media is
advocated, depending on the indication for scintigraphy and
whether the patient is euthyroid or hyperthyroid.
Intravascular administration of contrast media shortly after
injection of isotope material (99mTcpyrophosphate) for bone
imaging can interfere with the distribution of the 99mTc-
pyrophosphate.

16. Effects of Contrast Media on Isotope Studies
Increased uptake of the isotope material in kidneys and liver with
low uptake in bones was observed. The diuretic effect of contrast
media may increase the elimination of the isotope material in urine
so less is available for deposition in skeleton.
 99mTc labeling of red blood cells should
not be performed within 24 h after contrast
media injection. How contrast media
interfere with red blood cell labeling is not
fully understood