CONTRAST MEDIUM-1

contrast

The word contrast media means chemical substance sthat due to its high attenuation of X-ray or differential absorption of X-rays from the surrounding tissues permit clear demonstration of an organs or tubular structure .

Types of contrast media :1. Intravascular : A. High osmolar-cm or ionic.

B. Low osmolar or nonionic.

2. Oral.

HOCM or ionic:

Sodium iodide and sodium acetrizoate (UROKON) were the first ionic contrast media. Later various benzoic acid derivatives were introduced which were combine with Na+ and Meg+

Various HOCM are:Diatrazoate (urografin)Iothalmate (Hypaoue)Metrizoate (Conry)Iodamide

These are monomeric ionic contrast

RCoo

I

I

I

RR

+

Na

• Ionic contrast media are hypertonic with osmolality of 1200-2000 per lit wich is 4-7 time more than osmolality of plasma.

• Almost all the adverse effect of these contrast media are due to hyper tonicity.

An ideal contrast agent should be :1. Non toxic.2. Painless to patient.3. Low osmolar.4. It should not be expensiveThe ratio of iodine atoms to ions in HOCM is 3:2

HOCM or ionic:

Low Osmolar Nonionic Contrast

• In order to reduce the osmolarity and increase the ratio of iodin atom to particle in solution dimericionic contrast agent were produced such as ioxgalate.These compound were having 6 iodine atom for two molecules

Coo

I

I

II

I

I

R

+

Na

+

MEG

Dimeric Compound

This Agent is low osmolar but ionic

Coo

I

I

I

RR

+

Na

Monomeric

nonionic

Iodine 3:1

(Ioversol)

ROH

I

I

II

I

I

R

ROH

ROHROH

DIMERIC

NONIONIC IODINE RITIO

6:1

These Compound are :

1.Iopamidol )Niopam(

2.Iohexol )omnipaque(

3.Iopromide )Ultravist(

4.Ioversol 5 Iotrolon)isovist( 6 .Iodoxinal

These agent have low osmolality as compared to HOMC and fewer side effect.

The only disadvantage is there cost these agent are very expensive.

Clinical ApplcationUrinary system: IVU \ EU. Ascending Uretnrography. Cystography. Micturating cystouretnorography. Antegraded Retbograde Pyeldgraph.

Biliary system: Intravenous cholangiography. T .Tube cholangiography. P.T.C E.R.C.P

Cardiovascular system : Arteriography. Venography. Angiocardiography. Contrast enhanced CT . Contrast enhanced M.R.I .

Clinical Applcation

Minor Reaction / Effect

Moderate adverse effects : Maintain I / v line Antihistamine 10-20 mg paeds 2 mg / kg body wite Wheeze :Hydrocortisone 100 I / V , O2 therapy.Hypotension with bradycardia O2 , I / V Flaid Atropine 0.6 mg repeat sm total 3 mg.

Contrast Media Used In M.R.I

It enhanced the inherent tissue contrast causes T1 and T2 shortening .

Type : A. ParamagneticEX : Gadolinium D.TPA. Causes T1 shortening signal appear bright.

B. Super paramagneticEX : Iron oxide manganese for causes T2 shortening signal appear dark

.

Adverse Reactions

1. Minor : Nausea Vomiting Sneezing Urticaria Pain in arm Sensation of warmness

2. Moderate Reactions : Persistant headache Severe urticaria and bronchospasm Wheezes abdominal cramps Hypotension with bradycardia………… Severe vomiting G

3. Severe and life threatening Laryngeal edema Angioneurotic edema Hypotension with tachycardia Anaphylaxis (2nd) severe Seizure Cardiac arrest Pulmonary edema Unconciousness / no response / pulse less /cardiopulmonary collapse and

death

Adverse Reactions

Mechanism of contrast media reactions:

1:Over dose

2:Anxiety

3:Chemotoxicity

4:Endothelial damage

5:Release of histamine and other enzymes

6:Anaphylaxis.

Risky group of patients to whom HOCM is not recommended.

•Extreme age eg infants and old people

•Hypertension

•DM

•Asthma

•Renal failure

•Liver failure

•Multiple myeloma

•Dehydration

MRI contrast media

•Generally two type of MRI contrast agents

•Paramagnetic. Eg Gadolinium and mangnese agents

•Gadolinium ion is a paramagnetic agent which has 7 unpaired electrons

•It is chelated with DTPA because GAD alone is toxic.It cause T1 shortening due to that T1 weighted

image appear bright.Different agents in this group are Gadopentate and Gadodamide.These

compound are injected by I/v route

MRI cont,

The second group are Superparamagnetic Iron oxide.This agent is specifically used

for liver and mainly cause T2 shortening.This has opposing effect and

the enhanced area appear black .

Adverse effect of MRI contrast

•Metalic taste in mouth

•Nausea vomitting

•Itchin

•Nephrogenic fibrosis

•Urticaria etc

Indication of MRI contrast

•CNS tumors

•Crdiac imaging

•Vascular imaging

•Musculoskeletal imaging

Ultrasound Contrast agents

•Small microbulles

•Leovist.Most commonly used

•Echovist

•Albunex

•Echogen

Indication

•Vascular US)Doppler(

•Harmonic imaging

•Sonohysterosalphingography

ORAL contraST AGENT

•.IWater soluble.Gastromiro.It is iopamidol

•61% w/v

•Gastrographine.It is mixture of sodium and

• meglumine diatrozoate 66%w/v

Indication

•Suspected perforation

•LOCM is used if aspiration is a possibility

•Complications are hypovolumia,pulmonary edema and allergic reaction

Barium sulphate

•Baritop 100 100%w/v for barium follow through

•E-Z-HD 250%w/v for barium sallow and barium meal examination.

•E-Zpaque 100% w/v for barium follow through

•E-Z paque 60% w/v for small boel enema

•Plibar 115% w/v for barium enema.

Advantages and disadvantages of barium

•Barium has excellent coating of mucosa as compared to water soluble contrast.

•It is cheap

•High mortality if leak occure in to the peritoneal cavity

•Make subsequent CT examination difficult

Complications

•Perforation.The escape of barium in to the peritoneal cavity is dangerous

•Aspiration is harmless

•Intravasation can result in pulmonary emb

Contrast 2

Pharmacological agents

Pharmacological agents

•Hyoscine –N-butyle bromide)Buscopan(•Adult dose 20mg I/V•It inhibit intestinal motility and gastric secretion•Advantages. Immediate action,short duration of

action and it is not expensive•Disadvantages. Blurring of vision,dry

mouth,tachycardia and urinary retention.• Contraindications.close angle

glaucoma,myasthenia gravis,pyloris stenosis etc• glucogon can be used in these situations

Glucogon

•Adult dose. .3—1mg•Childern dose ,5—1microgram/kg•Advantages.more potent smooth muscle

relaxant than glucogan,,short duration of action and it do not interfer with ttransit time

of bowel•Disadvantages.hypersensetivity teaction is

possible,long onset of action and expensive

Contraindication of glucogan

•Adrenal tumors.glucogan can cause sudden hypertension.if hypertension

occure,phentolamine can be used for treatment

•Endocrine tumors of pancrease

Contrast 3

Treatment of contrast media reactions

Emergency drugs used in X-ray department

•Metacloperamide.For sever vomiting and for fascilitation of barium follow through.

•Adrenaline.1:1000 sc or i/m injection.used in cardiac arrest

•Atropine.600micg in 1ml.used for treatment of vasovagal shock)hypotension

with bradycardia(•Chlorophenirmine.10mg in 1ml.used for

sedation and vomiting

Drugs

•Sodium bicarbonate 200ml.used to prevent or treat acidosis

•Aminophyline.250mg in 10ml.for the treatment of bronchospasm

•Diazepam i/v 10mg.For the sedation and treatment of convulsion

•Hydrocortisone 100mg.In any emergency condition.

• Dopamine.800mg in 5ml.For treatment of hypotension with tachycardia

Drugs

•Frusemide. For pulmonary edema and diuresis

•Nalaxone.400micg in 1ml.used as antidote for morphine.

•Protamine sulphate.used as antidote for heparine.

•Dextrose5% 50ml.for I/V fluid replacement

•Dextrose 50%.as I/V fluid replacement

•Normal saline 500ml as fluid replacement.

Treatment of toxic reaction of contrast

•Angioneurotic edema. I/V line I/V hydrocortisone I/V antihistamine

sc adrenaline Oxygen

Bronchospasm I/V line Oxygen Aminophyline Hydrocortisone

Severe urticaria.antihistamine or sc adrenaline

Toxic reactions

•Hypotension.

•Elevation of legs

• No improvement and bradycardia,then give I/v fluid and atropine

•If no improvement and tachycardia,then give I/v fluid or dopamine infusion.