Contrast

contrast media

a diagnostic agent that can be injected using several different routes into the vascular system, joints, ducts and organs to enhance subject contrast in anatomic areas where low subject contrast exists

ASRT scope of practice

Scopes of practice delineate the parameters of practice and identify the boundaries for practice

ASRT advisory opinion

Interpretations of the practice standards. They are intended for clarification and guidance for specific practice issues

routes of contrast administration

enteral

parenteral

enteral

ingested

rectal

retrograde

rectal

parenteral

intravenous

intrathecal

intra-articular

intra-arterial

PO

by mouth

advantage of oral route

Safest, most economical, and most convenient way of giving medication

disadvantages of oral route

May have bad taste, odor, or may be large quantities

May irritate gastric mucosa – nausea and vomiting

Seriously ill or uncooperative person might aspirate

Digestive enzymes may destroy them

advantages of rectal route

Meds can be given when stomach is traumatized

Good method if drug has bad taste or odor

Good method if digestive enzymes can destroy drug

Avoids irritation of UGI tract

disadvantage of rectal route

Unpredictable retention of drug; absorption is erratic

parenteral

most hazardous route

intravenous

Directly into bloodstream

Through a vein; allows patient to respond rapidly to medications

Used for delivering emergency meds when rapid response is necessary

Can be most hazardous method; most rapid

Venipuncture can be done w/ hypodermic needle, butterfly set, or IV catheter

intravenous

most common parenteral route in radiology

intrathecal

spine

extravasation

Leakage of the contrast (vesicant) into the surrounding tissues

• Remove the needle, apply pressure, and a cold compress to relieve discomfort.

• Elevate the affected area

6 rights of drug administration

right medication

right dose

right patient

right time

right route

right documentation

Contrast or Medication name

Strength (if applicable)

Amount/quantity (if not readily apparent from the container)

Expiration date (if not used within 24hrs)

Expiration time (if less than 24hrs)

Whenever a contrast product or medication is transferred to another container and not immediately administered, set down for any reason or period, the new container must be labeled immediately, including the minimum:

no

does RT determine the time drug is given?

Name and dose of medication/drug

Route of administration (if parenterally include site)

Date and time

If the patient refused

Adverse effects or errors must also be documented thoroughly

Any time a drug is administered to a patient, relevant information must be recorded in patient’s chart/EPIC:

yes

is contrast considered a medication?

Absorption characteristic of the tissues

Technical factors used

Characteristics of the image receptor

Automatic image processing

Contrast media agents used

Factors that affect the radiographic densities:

higher

Tissue with higher/ lower atomic numbers absorb more x-ray photons than tissues with low atomic numbers

contrast studies

diagnostic agents are administered into body orifices or injected into vascular system, joints, or ducts to enhance subject contrast in areas where it is low

better anatomic definition

can assess function

advantages of contrast studies:

subject contrast

radiographic contrast

contrast media changes the density of the organs → which also changes:

positive

negative

classifications of contrast

radiolucent

negative

radiopaque

positive

decreases attenuation

radiolucent/ negative

increase attenuation

radiopaque/ positive

darker/ black

radiolucent appearance

Gas-filled microbubbles (U/S)

Gas-producing tablets

Soda water (EZ Gas)

Carbon dioxide crystals

gaseous types of compounds

yes, but typically not done because cells absorb O2 quickly

can we use gas alone as a contrast agent?

air can cause an emboli

complications with negative contrast agents

light/ white

radiopaque contrast appearance

barium sulfate

gad

ionic

nonionic

positive contrast compounds

barium sulfates

gad

metallic salts

ionic

nonionic

organic iodides

kVp

image contrast

radiographic object (patient)

influences contrast

90-120

barium kVp range

<90

iodines kVp range

white

barium will appear white/ black on an image

black

air will appear white/ black on an image

BaSO4

barium sulfate

56

barium sulfate atomic number

suspension

flocculation

physical properties of barium sulfate

Diverticulitis / ulcerative colitis / toxic megacolon

Elderly or long-term steroid use

Unknown fistula

Recent surgery

Uncooperative pt (sedated/mentally handicapped)

barium contraindications

Colon absorbs water from waste

• Ba can dry and cause constipation or obstruction

• Increase in H2O absorption by the colon (Lower GI Studies) = excess fluid entering circulatory system = hypervolemia (fluid overload) , pulmonary edema (fluid in the lungs)

• Colon perforation; extravasation into abdominal cavity = peritonitis

Allergic reactions – rare, most due to flavor additives

Vaginal rupture – rare complication, usually due to incorrect placement of catheter prior to lower GI exam

barium adverse reactions

weight/ weight

indicates the number of grams of active ingredient in 100g of product

• used for powdered barium

weight/ volume

indicates the number of grams of active ingredient found in a volume of 100mL

• used for liquid barium

• weight of Ba compared to the total volume of Ba mixture

53

iodine atomic number

citrate and calcium disodium edetate

Iodinated contrast agents have additives to prevent iodine atoms from being removed from contrast molecules:

oil based

water soluble

types of iodine

oil based iodine

injected in ducts (NEVER VESSELS)

not ingested

water soluble iodine

injected in vessels and/or ducts

ingested

shows organ flow/ function

oil based iodine

Made from fatty acids commonly found in plants and animals

Iodinated – containing iodine

Viscous – friction; oil based is thicker

Not used w/ plastic syringes because toxic parts of plastic can mix w/ oil-based media

Not used at RH anymore

persist in the body

disadvantage of oil based iodine

brochography

lymphography

dacracystography (tear ducts)

myelograms

sialogram (salivary glands)

oil based iodine specific procedures:

osmolality

Measure of total number of dissolved particles in a solution per kg of water

Osmolality of a solution determines osmotic pressure, which controls the movement of water in the body

Higher osmolality media (ionic) have larger # of particles in a solution, which pulls water toward them

homeostasis

any self-regulating process by which biological systems tend to maintain stability while adjusting to conditions that are optimal for survival

anion

radiopaque part of ionic contrast

anion

absorbs x-rays and creates the image contrast during iodine procedures

cation

role is mostly to balance the negative charge of the contrast anion so the compound is electrically neutral before injection

cation

often sodium (Na⁺) or methylglucamine (meglumine)

benzene ring

6 carbon bonded hexagon base (anion)

fat

water

muscle

bone

atomic numbers lowest to highest