CONTRAST MEDIA

Dr. Ahmed Refaey

FRCR

Types of contrast media

* Iodinated

: * HOCM * LOCM

* GIT contrast agents

* Barium sulphate * water soluble contrast media ( Gastrographin) *

MRI contrast agent * Ultrasound contrast agent

IODINATED CONTRAST AGENTS

Classification

High osmolar contrast agents ( HOCA )

* Ionic

Low osmolar contrast agents ( LOCA )

* Ionic * Non-ionic

HOCM • HOCA are in use since the 1950.

* Urovist.

* Urogarfin * Angiovist.

* Conray.

* Renografin.

* Renovist.

* Hypaque.

LOCA Non-ionic Ultravist Omnipaque Visipaue Oxilan Ionic Hexabrix

• LOCA have a lower incidence of adverse reactions by a factor of 6 for all reactions , and by a factor of 9 for the severe reactions.

Toxic effects • • • • • • Vascular toxicity Soft tissue toxicity Cardiovascular toxicity Haematological changes Thyroid function Nephrotoxicity

Nephrotoxicity • • • Incidence of contrast induced nephrotoxicity 5% In the majority, renal impairment is temporary Predisposing factors : * impairment of renal function * DM * dehydration * old age * large doses of CM * multiple myeloma

Reactions of CM •

Fatal reactions ( death )

-1/140,000 for HOCM 1/300,000 for LOCM -occur in minutes -old age -causes ( cardiac arrest – pulmonary edema – respiratory arrest – coagulopathy – laryngeal edema- bronchospasm )

•

Non- fatal reactions

1-flushing, metallic taste in the mouth, nausea, sneezing, cough—common & related to dose and speed of injection.

2- urticaria 3- angioneurotic edema 4- bronchospasm 5- pulmonary edema 6- arrythmia 7- hypotension 8- delayed reactions: rashes , headaches, itching

*Excluding death, adverse reactions can be classified in terms of severity as: • • • 1-

major reactions

: those that interfere with the examination and require treatment.

2-

intermediate reactions

: those that interfere with the examination but do not require treatment.

3-

minor reactions

: those that do not interfere with the examination and require only assurance

Risk factors • • • • • • • allergy , asthma Cardiac disease Hepatic failure Poor hydration Co-administration of: glucophage Previous reaction to contrast media - HOCM----- 20% - LOCM ----- 5 % Other factors: * pheochromocytoma * sickle cell disease * hyperprotinemia ( multiple myeloma )

•

High risk patients should either:

1 – be premeicated with steroids 2- to be evaluated with other modality ( U/S – MRI )

•

Route of administration

: intravenous •

Uses :

* CT study * urography ( IVP- urethrography_ cystography ) * angiography ( arteriography – venography ) * PTC, ERCP, T-tube cholangiography * hystrosalpingography * sialography * fistulography

Urography

IVU

Cystogram

Urethrogram

Angiography

Sialogram

Sialogram

Fistulogram

PTC

PTC

ERCP

T-tube cholangiogram

HSG

HSG

GIT contrast agents

Gastrointestinal contrast agents

•

BARIUM SULPHATE

•

WATER SOLUBLE CONTRAST MEDIUM (GASTROGRAFIN )

BARIUM SULPHATE

Barium sulphate •

Thin barium

: for upper GI studies, small bowel follow through, barium enema --- 40% BaSO4 solution.

•

Thick barium

: for double contrast studies ---- 85% BaSO4 solution

•

Advantages

: * excellent coating, allowing the demonstration of normal and abnormal mucosal patterns.

* cost

• Complications: • • Exacerbation of GI obstruction above a preexisting bowel obstruction Intraperitoneal extravasation through gut perforation results in extensive fibrosis

• Contraindication : • • Bowel obstruction Bowel perforation

Water soluble contrast medium (gastrografin )

Water soluble contrast medium (Gastrografin ) • • • • • Oral contrast medium for opacification of GIT Hygroscopic agent Undiluted or diluted Can be used as a substitute for barium if GI perforation is suspected.

In CT , diluted by 1:40

Complications • • • Aspiration can cause chemical pneumonitis Diarrhea Hypovolemic shock if used undiluted

CT contrast agents • • IV contrast medium Oral water soluble contrast medium (gastrografin)

MRI contrast agent

MRI contrast agent • Gadolinium • • Gd-DTPA IV

ULTRASOUND CONTRAST AGENT • • Levovist / echovist IV

• • All agents consist of radiodense iodinated Benzene ring.

Ionic agent typically formulated as Sodium and or meglumine salts.