contrast media(1).pptx

Contrast media
Prepared By Ashenafi Abrha(MSc MRT)
6/17/2023 Prepared by Ashenafi Abrha(MSc MRT) 1

Objectives
At the end of this session you will be able to:
 Discuss about contrast agent and their effect
 Differentiate types of contrast media
 Identify the routes of administration of contrast media for various radiographic examinations
 Compare and contrast the use of ionic and nonionic iodinated contrast media
 Describe possible reactions to contrast media and categorize them according to their severity

INTRODUCTION
 Contrast studies are those examinations in which contrast media are used to enhance
visualization of specific body structures.
 Because of the low subject contrast of the abdomen, contrast media are used to
demonstrate the anatomic structures of
 The urinary,
 Digestive, and biliary systems.
Its also used to evaluate other areas of the body, such as
 The spinal canal,
 Female reproductive system, and vasculature.

Basic principle of contrast media
 It is a pharmaceutical agent that is administered to a patient for a radiographic
examination to enhance the contrast of a particular structure.
 It is depending on x-ray absorption and penetration that reach on the film.
 Its use allows for differentiation between a structure and surrounding tissues by
altering the density of the structure, which in turn alters the absorption of x-rays.

Cont`d…
 It is a chemical substance of very high or very low atomic number or
weight, therefore it increase or decrease the density of the organ under
examination.
 A substance which when introduced into the body will increase the
radiographic contrast in an area where it was absent or low before.

Effect of Contrast media
Without CM With CM
B
A

Cont`d…
 Structures & organs within the body have similarly low tissue densities.
 Tissue densities are depends on atomic number
 When x-ray pass through the structures some of the beam will be
 Absorbed (Denser structures) appear White on the radiograph
 Penetrated (lighter structures) appear dark on the radiograph

Requirements of a Contrast Media
 Easy to administer
 No toxicity(neurotoxicity)
 Stable compound. – Will not dissociate into toxic ions
 When injected the media concentrates in the required areas.
 The agent’s physical features allow the organ to be properly
demonstrated
 even barium coating of the stomach in the presence of an acid environment.

Requirements of a Contrast Media
 The agent should have rapid elimination.
 The agent should not be carcinogenic.
 The agent should have a viscosity appropriate to the patient when introduced.
 The agent should cause minimal distress to the patient when introduced.
 The agent should be cost-effective.
 Must possess a suitable half life for storage.
 Low or iso- osmolar to blood plasma.

Types of contrast media
 The two basic classifications of contrast media are
1. Negative contrast agents and
2. Positive contrast agents.

1. Negative contrast agent
 It is radiolucent,
 Has a low atomic number, and
 Allows x-rays to pass through quite easily.
 As more x-radiation reaches the film, the structure that is filled with a
negative contrast agent appears dark (black) on radiography.

Cont`d…
 Gases, such as oxygen, carbon dioxide, and nitrous oxide, may be used as
negative contrast media, although room air is the most common agent.
 Gas crystals , the normally present gas bubble in the stomach.
 Calcium, magnesium citrate and carbonate crystals are frequently used to
produce CO2 gas.
 For example, the air in the lungs serves as a negative contrast medium on chest
radiography.

Cont`d…
 A negative contrast medium may be used alone, as in the case of
an air arthrogram,
 It can also be combined with a positive contrast agent to produce
a double-contrast effect, such as a barium enema examination
with air.

Cont`d…
 The uses of negative contrast media are limited, however, as
they may not provide sufficient contrast of a structure when
used singly.
 They must never be injected intravenously; doing so will
have serious, if not fatal, consequences.

2. Positive Contrast Agent
 Is radiopaque
 Has a high atomic number.
 As it absorbs approximately three times more x-rays than bone and five times as
many x-rays as soft tissue,
 An organ filled with a positive contrast agent appears light on the resulting
radiography.
 Barium sulfate (BaSO4) and Iodinated compounds are most commonly used.

BARIUM SULFATE
Properties
 Barium is a heavy metal having an atomic number of 56.
 It is combined with oxygen and sulfate to form the inert compound barium
sulfate (BaSO4).
 It is a white, crystalline powder that is insoluble in water.
 For use in radiography, it is mixed with water and stabilizing agents to form a
suspension.
 Barium sulfate is used for examination of the entire alimentary canal.

Cont`d…
 High atomic number
 Not soluble in water
 Used to coat the lining of organs
 Supplied in different thicknesses
 Used
 Esophogram, UGI, Small Bowel,Lower GI or BE

Cont`d…
 Ideally, the suspension should be dense to coat the mucosa and outline the visceral walls, yet
it must have the ability to flow smoothly through the alimentary canal.
 The products are available commercially in paste, liquid, powder, and tablet form.
 Paste, having a viscosity approximate to that of honey, may be recommended for an
esophagram.
 A liquid barium sulfate suspension can also be used for radiographic examination of the
esophagus, as well as the stomach and both small and large intestines.

Cont`d…
 Barium sulfate tablets are helpful in evaluating foreign objects or
strictures in the esophagus.
 They dissolve in either the esophagus or stomach when mixed with
water.

Contraindications
Because of its inability to be absorbed by the body, barium sulfate cannot be used
intravascularly or intrathecally.
Also, its use is contraindicated in the case of
 A suspected perforation in the alimentary canal.
 Recent or impending abdominal surgery.
 Obstruction of GIT.
 Mediastinal leakage.
 Aspiration.
 Peritoneal leakage and hypersensitivity.

IODINATED COMPOUNDS
Properties
 Iodine is the element of choice for use as a contrast agent, as it forms stable
compounds and does not break down in the body. Like barium sulfate,
 It has a relatively low toxicity and
 High atomic number.
 Unlike barium sulfate, it is generally absorbed by the body and excreted by the
kidneys within 24 hours of intravascular administration.

Cont`d…
 As iodinated contrast media have a tendency to break down in the light,
they should be shielded from bright light.
 The viscosity, or thickness, of the contrast medium is greatly determined by
the size the concentration of the molecules in the solution.
 It is recommended that the liquid iodinated contrast media be prewarmed to
body temperature prior to use.

Cont`d…
 An iodinated contrast agent with a higher concentration is
generally used for cardiovascular studies, whereas a lower
concentration is used for urography and cholegraphy.

Cont`d…
 Iodinated contrast media are available as either oil-based or
water-soluble agents.
 Each type of medium is selected for use based on the anatomy
to be examined.

Oil-based Iodinated Contrast Media
 The use of oil-based iodinated contrast media in radiography is relatively limited.
 They are used primarily for studies of the lymphatic system (lymphangiography).
In the past, they were also used for studies of the
 Hysterosalpingography,
 Myelography),
 Bronchography
 Sialography, and
 Dacryocystography, but have been replaced by water-soluble iodinated nonionic contrast media.

Cont`d…
 The oil-based iodinated contrast medium is used in hollow anatomic areas,
enhancing the radiographic contrast of the structure.
 The oily base of the contrast medium is a fatty acid, which is responsible for
making the solution viscous (thick) and insoluble in water and body fluids.
 Because it is not miscible with blood, it should never be injected intravenously
or intraarterially.

Water-soluble iodinated contrast media
Water–Soluble (aqueous) iodinated contrast media are routinely used for
radiographic examinations of the
 Urinary,
 Biliary, and cardiovascular systems,
 as well as the digestive system if barium sulfate is contraindicated.
 It also used in special examinations of the skeletal system such as
myelography and arthrography.

 They are available in liquid, tablet or granule form depending
on the intended use.
 The injectable liquid media can be divided in to
 Ionic and
 Nonionic contrast agents.

An ionic contrast agent is an organic iodine compound that has triiodinated
benzoic acid as its base.
 The compound dissociates or separates in water into two electrically
charged particles.
 One of the particles, called a cation, has a positive change; the other
particle, an anion has a negative charge.

A nonionic contrast agent also contains iodine and is derivative of the
triiodinated benzoic acid base,
 but it does not contain an ionizing group.
 It is more soluble in water and
 Does not dissociate into changed particles;
 It has a lower osmolality than an ionic contrast agent.

Triiodinated benzoic acid

Classification of iodinated contrast agents by
their molecular structure

 Osmolality refers to the concentration or number of particles (cations and
anions) in the solution per kilogram of water and is directly related to
occurrence of adverse patient reactions.
 It is measured in osmoles, which are units of osmotic pressure.
 A contrast agent with a high osmolality has an increased number of particles
and more osmoles in the solution.

 Any time a foreign substance is injected into the bloodstream, the
homeostasis of the body can be affected.
 Because of their hyperosmolality, ionic contrast agents can cross the blood-
brain barrier, which is also a factor in the occurrence of adverse reactions.
 Nonionic contrast agents have a much lower level of neurotoxicity.

 Although the osmolality of nonionic contrast agents is still
higher than that of blood plasma, it is significantly lower than
the osmolality of ionic contrast agents.
 For this reason, the use of nonionic contrast agents tends to
produce fewer physiologic reactions than use or their ionic
counter parts.

Examples of ionic (high osmolar)
Iodinated contrast agents
Name Type Iodine content Osmolality
Ditrizoate(Hypaque 50) Monomer 300 mg/ml 1550
Iothalamate (Conray 60) Monomer 370 mg/ml 2100
Ioxaglate (Hexabrix ) Dimer 320 mg/ml 580

Examples of non-ionic (low osmolar)
Iodinated contrast agents
Name Type Iodine content Osmolality
Iopamidol (Isovue 370) Monomer 370 mg/ml 796
Iohexol (Omnipaque
350)
Monomer 350 mg/ml 884
Ioversol (Optiray) Monomer 320 mg/ml 796
Iopromide (Ultravist
370)
Monomer 370 mg/ml 774
Iodixanol (Visipaque
320)
Dimer 320 mg/ml 290

Classification
High osmolar contrast agents
( HOCA )
Low osmolar contrast agents (
LOCA )
* Ionic * Ionic
* Non-ionic

HOCM
• HOCA are in use since the 1950.
* Urovist.
* Urogarfin
* Angiovist.
* Conray.
* Renografin.
* Renovist.
* Hypaque.

LOCA
Non-ionic Ionic
Ultravist
Omnipaque
Visipaue
Oxilan
Hexabrix

Contraindications
The most significant contraindication to the use of iodinated contrast media is an
 Allergic history to iodine.
 Renal disease(Abnormal RFT)
 Congestive heart failure
 severe dehydration
 Asthmatic patients
 Diabetes - get a hx of medications taken
 glucophage must be stopped 48 hrs before contrast injection
 Multiple Myeloma
 Anuria (no urine production)
 Older patient age

Summary on iodinated CM
1. Most of the i.v. contrast media contain iodine which has an atomic
number 53 and atomic weight 127.
2. Total iodine content in the body is 50 mg.
3. It's preferred because
 High contrast density due to high atomic number
 Allows firm binding to highly variable benzene ring
 Low toxicity.
4. It's not suitable for MRI.

The advantages of non ionic contrast media
over ionic contrast media
 Well tolerated by the patient
 Less heat and discomfort on injection
 Low osmolality
 Does not dissociate in to charged particles
 Low neurotoxicity
 Approximately one-fifth fewer adverse reactions than with the use of ionic
contrast media

Types of contrast media used in MRI
 MRI contrast agents are contrast agents used to improve the visibility of
internal body structures in magnetic resonance imaging (MRI).
 The most commonly used compounds for contrast enhancement are
gadolinium-based.
 Such MRI contrast agents shorten the relaxation times of nuclei within
body tissues following oral or intravenous administration.

Cont`d…
 Most clinically used MRI contrast agents work by shortening the T1 relaxation
time of protons inside tissues via interactions with the nearby contrast agent.
 MRI contrast agents may be administered by injection into the blood stream or
orally, depending on the subject of interest.
 Oral administration is well suited to G.I. tract scans, while intravascular
administration proves more useful for most other scans.
 A variety of agents of both types enhances scans routinely.

Cont`d…
MRI contrast agents can be classified in many ways, including by their:
 Chemical composition
 Route administration
 Magnetic properties
 Effect on the image
 Presence or absence metal atoms
 Biodistribution and applications

Gadolinium
• Is the standard exogenous contrast agent used in clinical MR imaging.
It is T1 relaxing agent
Paramagnetic.
It belongs to lanthanide metal group with atomic no. 64.
It has a high spin contrast number which produces desirable relaxivity
contrast agents.

Classification of MRI contrast
agents
 Extracellular fluid agents (also known as intravenous contrast agents)
 Blood pool agents (also known as intravascular contrast agents)
 Organ specific agents (i.e. gastrointestinal contrast agents and hepatobiliary
contrast agents)
 Active targeting/cell labeling agents (i.e. tumor-specific agents)
 Responsive (also known as smart or bioactivated) agents
 PH-sensitive agents

Types by body compartment
Gadolinium(III) contrast agents can be categorized into:
Extracellular fluid agents
• gadoterate (Dotarem, Clariscan)
• gadodiamide (Omniscan)
• gadobenate (MultiHance)
• gadopentetate (Magnevist)
• gadoteridol (ProHance)
• gadoversetamide (OptiMARK)
• gadobutrol (Gadovist [EU] / Gadavist [US])
• gadopentetic acid dimeglumine (Magnetol)

Blood pool agents
 These agents reversibly bind to plasma albumin achieving a substantial
improvement in magnitude and duration of blood pool enhancement.
EXAMPLE:
1)SPIO-super paramagnetic iron oxide crystals
2)USPIO
3)Magnetite
These cause predominant T2 shortening.

Cont`d…
USES:
1)To image small vessels (eg:coronary artery).
2)Vessels with slow flow (eg pulmonary embolism, DVT),
3)Arteriovenous malformation
4)Perfusion studies
DISADVANTAGE:
 Overlap b/w arterial and venous structures and separation is difficult

Cont`d…
Blood pool agents
 Albumin-binding gadolinium complexes
 Gadofosveset (Ablavar, formerly Vasovist)
 Gadocoletic acid
 Polymeric gadolinium complexes
 Gadomelitol
 Gadomer 17

Cont`d…
• Hepatobiliary (liver) agents
 Gadoxetic acid (Primovist [EU] / Eovist [US]) is used as a
hepatobiliary agent as 50% is taken up and excreted by the
liver and 50% by the kidneys.

Ultrasound contrast agents
 It is Echo Enhancing Agents.
 These agents Increase The Echogenicity Of Blood, which heightens the
tissue contrast & allows better delineation of body cavities.
• Consist of Microscopic Gas Filled Bubbles.
• Their Extremely High Reflectivity(backscatter) arises from the fact that
microbubbles easily change their size, contracting in compression part of
the ultrasonic cycle & expanding in the rarefaction part.

Ideal ultrasound contrast agents
1) Be injectable by a peripheral vein
2) Be non toxic
3) Small enough to pass through pulmonary, cardiac & capillary systems
4) Stable enough to undergo the shear forces, hydrostatic pressure changes &
diameter changes
5) Half life should be sufficient to allow complete examination
6) Should require little preparation

Doppler rescue
 Application of ultrasound contrast agents results in
enhancement of colour, power & spectral Doppler waveform
& this improves Doppler imaging & is termed as ``Doppler
rescue ˮ

Applications
1) Evaluating normal, increased or decrease vascularity.
2) Detecting vascular stenosis & occlusions.
3) Improving neoplasm detection.
4) Analysing & characterizing tumour neovascularity.
5) Differentiating normal variants such as renal column of bertin from neoplasm.
6) Echocardiography – cardiac cavities, valves, coronary artery & myocardial
viability

ROUTES OF ADMINISTRATION
 Contrast media are considered to be pharmaceuticals (drugs), and as such they must
be administered appropriately to achieve the desired effect and to avoid unwanted
complications.
The five rights of medicine administration
1. The right patient should receive
2. The right medication
3. In the right amount
4. Via the right route
5. At the right time

Cont`d…
 The route of administration depends on the anatomy of interest, type of
examination, and particular contrast medium.
Contrast medium can be administered
 Orally,
 Rectally,
 Intravascularlly, or Intramuscularly
 Mechanically:- Introduced directly in to the intended site.

ORAL/RECTAL ROUTE
Barium sulfate products are administered by means of the oral route for
examinations of the
 Esophagus ,stomach, and
 Small interesting.
 Iodinated contrast agents such as Gastrografin and Hypaque can also be
administered orally for these same examinations. (and also for OCG)
 It is administered rectally as an enema for an examination of the large
intestine.

INTRAVASCULAR ROUTE
 Only water- soluble iodinated contrast media can be administered
intravascularly.
 Intravascular injection of contrast media includes both intravenous and
intra-arterial routes.
 The intravenous route is employed for excretory urography, as well as for
CT and MRI Examinations using contrast media.

Cont`d…
 The intra-arterial route is used for special radiographic procedures of the
cardiovascular system.
 Access to the artery is accomplished via the seldinger technique which is
described in angiography.
 In lymphangiography, the contrast medium is injected intravascularly into
the lymphatic vessels.

DIRECT ROUTE
 Some radiographic examinations require that the contrast medium be introduced
directly into the anatomy of interest.
 This can be achieved by means of a catheter or needle. For example, in a
cystogram a catheter is inserted into the urinary bladder and a water-soluble
iodinated contrast medium is allowed to flow into the bladder until it is full.

Direct route
 During a myelogram, an intrathecal injection is performed by inserting a
spinal needle into the subarachnoid space.
Examples of other examination in which contrast media are directly
administered include
 Arthrography,
 Hysterosalpingography,
 Sialography, and percutaneous transhepatic cholangiograhy.

REACTIONS TO CONTRAST MEDIA
 The potential exists for an adverse reaction to occur when a contrast
medium is administered to a patient.
 Although reactions can take place with the use of any contrast agent, they
are more likely to occur after intravascular injection.

Cont`d…
The technologist or radiographer should be aware of the possibility of adverse
reactions and be prepared to handle them according to the institution’s
protocol.
 An emergency drug box or crash cart should be in the examination room or
readily available.
 It is recommended that the patient’s blood pressure, pulse, and respiration be
assessed prior to contrast medium administration.

Cont`d…
 Following any examination in which barium sulfate is
administered; the patient should be advised to drink plenty of
fluids to prevent a bowel obstruction.

Cont`d…
The reactions seem to be directly related to the following factors.
 Degree of chemotoxicity of the contrast medium
 Concentration of iodine in the contrast medium
 Certain properties of the contrast medium including osmolality, viscosity, and
purity of the solution
 Dosage administered
 Pace of the injection
 Physical condition of the patient

Cont`d…
 An anaphylactic reaction closely resembles a true allergic reaction in
which the patient demonstrates hypersensitivity when a foreign substance is
injected.
 Although such a reaction cannot be predicted, certain patients seem to be
predisposed to experiencing adverse reactions.

Cont`d…
 A vasovagal reaction is one that occurs in response to anxiety or fear.
 It generally involves a vascular as well as a neurogenic response, with the
patient experiencing mild symptoms of pallor, dizziness, diaphoresis,
nausea ,and possibly bradycardia.

Cont`d…
 Extravasations Occurs during injection if some of the contrast medium
seeps out of the vein to the surrounding tissue.
 This reaction usually involves pain and discoloration at the site of
injection.
 The technologist or radiographer should apply a warm, moist compress to
the site to decrease pain and aid in the absorption of the extravasated
contrast medium.

Cont`d…
 Adverse reactions are usually acute, with the majority occurring 5 to 20
minutes after injection of the contrast medium.
 Although delayed reactions are possible, they are rare and typically mild
,moderate, or severe according to the symptoms experienced by the
patient and the treatment needed to alleviate them.

Mild
• Signs and symptoms appear self-limited without evidence of progression
• Nausea, vomiting ,altered taste, sweats, cough, itching, rash, hives
• Warmth (heat) Pallor, Nasal stuffiness
• Headache, Flushing, Swelling: eyes, face
• Dizziness Chills Anxiety
• Shaking
• Treatment: Observation and reassurance.
• Usually no intervention or medication is required; However, these reactions may progress into a
more severe category.

Moderate
• Reactions which require treatment but are not immediately life-
threatening
• Tachycardia/bradycardia, Hypotension Bronchospasm, wheezing
• Hypertension. Dyspnea Laryngeal edema
• Pronounced cutaneous Pulmonary edema reaction
• Treatment: Prompt treatment with close observation

Severe
• Life-threatening with more severe signs or symptoms including:
– Laryngeal edema, Profound hypotension
– Unresponsiveness
– severe or progressive Convulsions
– Cardiopulmonary arrest
• Clinically manifest arrhythmias (irregular heart beat)
• Treatment: Immediate treatment. Usually requires hospitalization.

Patients at increased risk
 History of a previous reaction to iodinated contrast agents or
 History of allergy
 History of asthma
 History of renal disease or conditions predisposing to renal impairment such as:
 − Previous renal surgery
 − Diabetes Mellitus
 − Proteinuria
 − Hypertension
 − Gout
 − Dehydration, Cardiac Failure

Patient care before administering
CM
 Hydrate the body prior to administration
 Warm CM to body temperature
 Keep emergency drugs like adrenalin
 Ask patient history

During anaphylactic reaction
 Stop the injection immediately
 Monitor vital sign
 Observe for respiratory distress
 Call emergency team (physicians and nurses)
 Place the patient in Semi-fowler’s or sitting position (for cardiopulmonary
distress)
 If the patient becomes breath less and pulse less, administer cardiopulmonary
resuscitation

General three principle of reaction treatment
1. Oxygen
2. Epinephrine
3. Corticosteriods

Patient care and instruction after
receiving iodinated contrast agent
 Instruct the patient to increase fluid intake to 3000ml for at
least 24 hours to assist with the dilution and excretion of the
agent from the body.

Summary
1. What is contrast medium
2. Define basic principle of CM
3. List and explain types of CM
4. Differentiate main advantage of oil-based and water soluble iodinated
contrast
5. Differentiate major difference between ionic and non ionic water soluble CM
6. Identify categories of CM reactions

THANK YOU!!

contrast media(1).pptx

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