CONTRAST MEDIA Flashcards
What are CONTRAST MEDIA (AGENTS)?
are substances which are added to the body during radiographic studies to visualize a specific part.
WHAT ARE 5 RADIOGRAPHIC DENSITIES?
Air (gas)
Fat
Water
Mineral
Metal
WHAT IS THE Purpose of contrast study?
To visualize anatomic structures that are not normally seen on a diagnostic medical image
CONTRAST MEDIA
-Visualizes anatomy normally not seen
-Requires the administration of media(agent) into patient
-Requires attention to indications and contraindications
-Warrants serious attention to patient reactions
Radiographic images without contrast media will have what type of contrast?
“low subject contrast” which means it will be difficult to the different areas within the body.
Adding contrast media or a contrast agents will permit the visualization of organs and structures such as?
such as vessels that could not be visualized without the addition of contrast media.
Two Types of Contrast Media
- Negative
- Positive
When must a pre-test patient interview be done?
prior to all contrast studies to R/O the possibility of previous allergic reactions and to identify any medical conditions that the patient may have that may alter the procedure
-Such as asthma or diabetes.
WHAT KIND OF FORM WILL PATIENTS BE REQUIRED TO SIGN?
Patients will be required to sign a consent form for all radiographic studies that will require the administration of contrast media.
INFORMED CONSENT IS NEEDED FOR?
Usually for invasive procedures such as special procedures and IV contrast injection procedures and the instillation of a contrast agent other than orally or rectally.
The consent form is separate from the general admissions forms signed by the patient.
The patient must be of sound mind and legal age.
Consent must be signed by the parent or legal guardian for minors.
Adult patients may also have a legal guardian.
The patient must give consent freely (voluntarily).
The patient must be adequately informed about the procedure about to take place.
Explanation of the procedure must be in terms the patient understands.
WHY IS A IMPLIED CONSENT NEEDED?
It Provides care when the patient is unconscious.
Based on the assumption that the patient would approve if able or conscious.
Even with a signed consent, if during a radiographic exam, the patient decides to stop a radiographic procedure (with or without contrast) the radiographer must stop the exam as soon as it is safe to do so.
Radiographer Responsibilities in the Administration of Contrast Media:
Know considerations
Knowledge of potential adverse reactions
Preparation of patient
Know indications
Preparation of contrast material(s).
Patient education and support
Obtain patient consent
Obtain and record patient history
Record the patient’s BUN and Creatine levels.
Monitor patients throughout exam.
JCAHO (Joint Commission on Accreditation of Healthcare Organizations) Medication Management Standard
All contrast agents (i.e., iodinated for injection and Oral Barium) are consideration medications.
Each contrast agent must have a written order for the drug to be administered and the contrast agents must be handled in accordance with the protocol for any prescription medication.
This includes having a written order and a thorough medication and health history. Many other prescription and over-the-counter drugs may interact with or have contraindications to the contrast agents.
WHAT ARE THE TYPES OF CONTRAST MEDIA?
-NEGATIVE
-POSITIVE
-SPECIALTY CONTRAST AGENTS
NEGATIVE
Radiolucent – (negative) contrast agents transmit x-rays.
Negative contrast agents are
- air and carbon dioxide.
Negative contrast agents are composed of elements with low atomic number.
Negative contrast agents will appear dark on radiographs.
When do negative contrast agents combine with a positive contrast?
Negative contrast agents may be combined with positive contrast agents
(i.e. air added to barium)
(To produce double-contrast studies)
NEGATIVE
- Air and Carbon dioxide
- May be used by themselves or combined with a positive contrast
The atomic number of Hydrogen is 1.
The atomic number of carbon Dioxide is 6.
The atomic number of Oxygen is 8.
Complications of using negative contrast:
-Embolus (air injected into the bloodstream)
-Because of the risk of air emboli, negative contrast media is never introduced (injected) into the blood stream.
-Joint distention, pain will occur after the injection of air into the joint space
POSITIVE ( BARIUM)
Radiopaque – (positive) contrast absorbs x-rays
Positive contrast agents are composed of elements with high atomic numbers
.
Positive contrast agents will appear whit on radiographs
Specialty Contrast Agents
ULTRASOUNDS
-MICROBUBBLES
MR SCANNING
-gadolinium-DTPA.
those agents used for specialty exam such as MRI and Sonography
MRI – the contrast agent most often used is gadolinium-DTPA.
US – the contrast agent most often used is gas-filled micro bubbles.
Specialty contrast agents such as gadolinium diethylenetriaminepentaacetic acid (gadolinium-DTPA) used in MRI
Why Is Air Not Used More Often as a Contrast Material?
Low Persistence
Perfect Contrast Material
- Very–high-contrast visualization
- Extremely low toxicity to patient
- Persistence in patient anatomy until imaging is completed
- Low cost
- Minimal or no side effects
KEY CONTRAST CHARACTERISTICS
Ability of agent to mix with body fluids
Viscosity - the thickness of a liquid or resistance to the flow of a contrast agent.
Ionic strength
Persistence in the body
Iodine content
Potential for toxicity
Osmolality
Osmolality
is the measurement of the number of particles in a solution per kilogram of water.
Contrast agents have osmolalities much higher than those of other body fluids.’
Most allergic reactions occur with contrast agents that have high osmolality.
Osmosis
the process by which water moves from an area of greater concentration to an area of lesser concentration.
Viscosity
describes the thickness of a liquid or resistance to the flow of a contrast agent.
(Viscosity (thickness) may be significantly reduced by warming the solution to near body temperature.)
Contrast agents are also highly viscous (thick and Sticky).
Common Contrast Choices
- BARIUM SULFATE
- AIR/GAS (CO2)
- OIL-BASED IODINE CONTRAST AGENT
- WATER SOLUBLE CONTRAST AGENT
CONTRAST MEDIA CHOICES
BARIUM- 56
IODINE-58
AIR/GAS- AVERAGE Z#8
The atomic number of Hydrogen is 1.
The atomic number of carbon Dioxide is 6.
The atomic number of Oxygen is 8.
Barium sulfate (INERT SALT)
POSITIVE CONTRAST
Barium is the commonly used contrast medium used to visualize the GI tract.’
Barium is an inert compound radiopaque substance.
The atomic number of BaSO4 is 56.
Barium mixed with water is a suspension.
-Push fluid following barium studies
BARIUM
High atomic number enhances the photoelectric effect.
Chemically inert
Insoluble in water
Tends to flocculate in acid pH
Contraindicated in cases of bowel perforation
Typically mixed with flavors, coloring, and so on to improve palatability
Hypervolemia must be considered in colon examinations.
Barium Studies of the GI Tract
Be aware of extravasation of barium in suspected cases of bowel perforations
- CHANGE TO iodine if contraindicated
COMPLICATIONS OF BARIUM
-Barium is contraindicated if there is a perforation of the digestive tract.
-Barium cannot be absorbed into the body.
-Peritonitis may occur if barium enters the pelvic or peritoneal cavity. The barium will need to be surgically removed.
-
Complications of Barium
Barium may pass into the peritoneal cavity or bloodstream through a break in the mucosa.
In place of barium a water soluble iodine contrast will be used such as Gastrographin.
Barium Peritonitis is an extravasation of BaSO4 into the abdominal cavity.
Aspiration
inhalation of BASO4 into the lungs during a UGI, Esophagram or Small Bowel Series may occur if the patient aspirates during the procedure.
Allergic Reaction
allergies to BASO4 are rare but may occur and are usually
caused by the additives to the barium.
Over-inflation of the retention balloon of the enema catheter (tip) may cause perforation of the rectum or colon.
Latex enema tip allergy.
Patients must be screened from possible latex allergies. Nonlatex enema tips are available.
Constipation
patients should be instructed to drink plenty of water for a few days following an exam in which BASO4 is used. The main symptom of obstruction of the colon is constipation.
WATER SOLUBLE IODATED CONTRAST AGENTS
IONICS VS NONIONICS
IONIC CONTRAST AGENTS
Uses iodine as the contrast material
Dissociates into two ions:
Anion and Cation
Viscosity
Osmotic effects
Dehydrated patients are vulnerable to hypovolemic shock.
Be aware of concentration of molecular particles in contrast agent.
IONIC CONTRAST AGENTS
The higher the iodine concentration, the greater the risk of adverse reactions.
Any contrast agent that contains iodine increases the risk for anaphylactic reactions.
Iodine has an atomic number of 53 which means iodine is a radiopaque substance.
Examples of Iodinated Contrast Agents:
Hypaque
Renografin
OIL BASED IONIC CONTRAST AGENTS
Insoluble in water
High viscosity – oil based iodinated contrasts do not flow easily through the syringe.
Oil based contrast agents are used infrequently in radiography.
Oil based contrasts are used for i.e. Bronchography and Lymphography.
OIL BASED CONTINUE
Store in a cool, dark area. When exposed to air, heat, and light the contrast breaks down or decomposes.
Do not use it if a color change occurs, should be a pale yellow or amber.
A dark color change indicates a decomposition of the contrast material.
Use only glass syringes, not plastic.
Toxic substances from plastic syringes may dissolve into the Oil-based contrast.
ANAPHYLACTOID REACTIONS
Urticaria
Wheezing
Throat swelling (edema)
Bronchospasm
Nausea
Vomiting
Cardiac arrest
It is critical to take a thorough patient history when contrast media is a part of any examination
NONIONIC CONTRAST AGENTS
Do not dissociate into anions and cations
Water soluble
No ionic breakdown and less toxic at the cellular level
Warmed to increase viscosity
High contrast effect resulting from
number of iodine atoms per molecule
Reduced injection volumes
NON IONIC CONTINUE
Also called lower-osmolality contrast media.
They cost two to three times more than iodinated contrasts but are less likely to cause allergic reactions.
More tolerable by patients
Examples of Non-Iodinated Contrast Agents:
Isovue
Omnipaque
Ultravist
Non-Iodinated Contrast agents are used when patients have:
Hx of adverse reactions to contrast
Hx of asthma or allergies
Known cardiac problems
Diabetes mellitus
Renal disease
Sickle cell disease
Elevated creatine levels
Patients that will have a Helical CT
Patients at increased risk for reactions should receive nonionic contrast agents.
Contrast Considerations
Patient history
Renal function
Contrast cost
Metformin (Glucophage) should be discontinued for 48 hours before and 48 hours after the use of iodine contrast media.
Contrast-enhanced CT studies
Contrast Reactions
Generally, occur within the first minute of injection
Can be unpredictable
Mild reaction may worsen to severe at any time.
Reaction is different from a side effect.
Monitor patient continually.
Types of Reactions to Contrast Media
Minor Reactions
Rash, Hives (urticaria)
Vomiting, Nausea
Cough
Itchy palms/soles
Metallic or altered taste
Warmth, heat
Headache
Dizziness
Shaking
Pallor
Flushing of the skin
Chills, sweats
Nasal stuffiness
Swelling, eyes and face
Anxiety
Vasovagal Reaction
Sudden episodes of hypotension and fainting that may occur during a radiographic procedure induced by the response of the nervous system to abrupt emotional stress, pain, or trauma.
The Vasovagal nerve becomes overstimulated, and the patient may become extremely lightheaded and may pass out.
The Vasovagal reaction is also called a Vasovagal attack.
Radiographers Response to a Vasovagal Reaction (Syncope)
Check the person’s airway, breathing and circulation.
If necessary, call a code and begin rescue breathing and CPR.
Loosen tight clothing around the neck.
Keep the affected person lying down for at least 10-15 minutes, preferably in a cool and quiet space.
If the person cannot lie down, have him sit forward and lower his head below the levels of the shoulders, between the knees.
If the person has vomited, turn him or her to one side to prevent choking and aspiration.
Elevate the feet above the level of the heart (about 12 inches).
Moderate (intermediate) Reactions
Respiratory
Tachycardia/Bradycardia
Hypotension
Hypertension
Persistent hives
Facial swelling
Dyspnea
Bronchospasm, wheezing
Laryngeal edema
Severe Reactions
Convulsions
Laryngeal edema
Severe respiratory symptoms
Severe hypotension
Cardiac arrhythmia’s
Shock
Unconsciousness, unresponsiveness
Cardiopulmonary Arrest
Radiographer response to Severe Reactions:
Immediately obtain medical assistance. Inform the radiologist or MD of any reactions that the patient is having from the contrast agent.
Clinical findings will indicate the need for immediate medical treatment including drug therapy.
Treatment of Severe Reactions
Maintain an open airway
Maintain an open IV
Monitor vital signs
Antihistamines are used to counteract hives and urticaria.
Blood pressure must be monitored and the patient should be checked for heart irregularities.
CPR as indicated by patient’s condition.
Scheduling of Exams
(requiring contrast media administration)
- All exams without contrast should be scheduled first.
- Ultrasounds exams are scheduled before barium studies
- Studies involving intra-vascular contrast are done before Barium Studies
- “BE” exams are performed before UPPER GI STUDIES
5.Exams that require patients to fast before the exam should be scheduled in the morning.
Fasting Instructions for Patients with Diabetes
Diabetic patients are at risk for changes to their blood sugar if they fast for a radiographic exam.
All diabetic patients should obtain instruction from their referring MD whether they are to take their usual dose of insulin or other diabetes medication on the day of the exam. All diabetes patients may be closely observed for rapidly developing symptoms of hypoglycemia and hyperglycemia.
Non-insulin dependent diabetic patients that are taking the medication Glucophage (Metformin) will be instructed by their referring MD to discontinue the Glucophage for 48 hours after a radiographic contrast exam using an iodine contrast media.
SEQUENCE OF RADIOGRAPHIC CONTRAST EXAMS
1st IVP
2nd GB
3rd BE
4th GI
RADIOGRAPHIC CONTRAST EXAMS THAT MAY BE PERFORMED TOGETHER
GB and IVP
IVP and BE
GB and GI
2-1
1-3
2-4
LAB TESTS PRIOR TO CONTRAST ADMINISTRATION
Two lab (blood) tests should be done before contrast exams to determine renal function.
Renal function is important because contrast media is filtered through the kidneys.
BUN – blood urea nitrogen
BUN provides information about kidney function and the ability of the kidneys to remove impurities from the body. BUN normal values range between 5 to 25 mg/dl.
Creatine
Creatine – creatine is a waste product stored in the muscles.
Elevated creatine levels indicate impairment of the function of the kidneys.
Creatine normal values range between 0.6 to 1.7 mg/dl
SCREENING FOR CONTRAST AGENTS
The radiographer must ascertain and report to the radiology nurse and radiologist the following:
If the patient has had any prior reactions to a contrast agent or radiology procedure.
If the patient has any known allergies to iodine, barium, latex or shellfish.
If the patient has any of the following pre-existing medical conditions:
Hypertension
Asthma
Sickle cell anemia
Renal impairment
Diabetes
The radiographer’s responsibilities (i.e. obtaining consent, taking a patient history, documentation, screening, preparing the contrast agents etc.) will depend on institutional policy.
PATIENT PREPARATION FOR RADIOGRAPHIC CONTRAST EXAMS
The patient should be given pre-procedural instructions at the time that the appointment for the contrast exam is made.
Pre-procedural Instructions
IVP
NPO after midnight
Cleansing enemas
Empty bladder before scout film
PATIENT PREPARATION FOR RADIOGRAPHIC CONTRAST EXAMS
GB
Patient takes prescribed iodinated contrast (tablets) the evening before scheduled exam
Evening meal is fat free to prevent gallbladder contraction
Water only in the morning of the exam
BE
Cathartics (laxatives) as prescribed by MD
Low residue diet
Cleansing enemas
UGI
NPO after midnight
Radiopharmaceuticals
-Not contrast agents
-Radioactive material chemically attached to a pharmaceutical that is metabolized in the body
-Biodistribution is important
-Typically emit gamma radiation
-Detected by gamma camera in the nuclear department
-Effective for cellular physiology assessment
-Contamination and spillage of critical importance
Handling Radiopharmaceuticals
Time is of the essence.
Be aware of contaminations.
Contaminations can produce image artifacts.
Contaminations increase exposure unnecessarily to patients and personnel.
Two types of contamination:
External
Internal
Health Professional Responsibilities When Administering Contrast Agents
Administered under the supervision of a licensed physician with proper qualifications
Patient assessment and history
Patient comfort and education
Recognize signs and symptoms of reaction and act appropriately.
Patient care and surveillance
Post exam considerations for patient
Remain calm and reassuring during procedures.
CONCLUSION
Contrast materials are an indispensable part of medical imaging.
Classified as positive or negative
Rely on the photoelectric effect for contrast visualization
Iodine-based contrast media can cause anaphylaxis.
Nonionic, low-osmolality contrast agents have reduced patient reactions but still a reality of imaging.
Radiopharmaceuticals are used to assess cellular physiology (perfusion)
.
Patient reactions and care are constant responsibilities of the radiologic sciences professional.
