CONTRAST MEDIA :X-RAY,CT,USG
Shivaprakash.B.HPG-BIR
• Contrast means act of distinguishing by comparing the differences,
Or is a perceptual effect of juxtaposition of different colors.
How do I define?• A contrast medium (or contrast
agent) is a substance used to enhance the contrast of structures or fluids within the body
Necessity for use• The contrast in the imaging is
dependent on the variable attenuation of the x-ray beam(number of electrons in path of beam).
Factors affecting• Thickness of the substance
being studied• Its density• Number of electrons per atom
of the element
Where do we use• Intravascular Intravenous CT DSA Intravenous urography Venography (phlebography)
Intra-arterial Angiocardiography Computed
tomography Coronary angiography Pulmonary angiography Aortography Visceral and peripheral arteriography Digital subtraction angiography
• Intrathecal (Use USFDA-approved contrast media only)
Myelography (myelographic nonionic only)
Cisternography (myelographic nonionic only)
• Other Oral, rectal, or ostomy – gastrointestinal tract
Conventional fluoroscopy CT Herniography Peritoneography
Vaginography Hysterosalpingography Arthrography ERCP Cholangiography Nephrostography Pyelography – antegrade, retrograde
Urethrography – voiding, retrograde Cystography Sialography Ductography (breast)
• Miscellaneous Sinus tract injection Cavity delineation (including
urinary diversions, such as loop and pouch)
How do we classify• Water insoluble available in form suspensions
of large insoluble particles as Barium
• Water soluble Iodinated contrast materials
Iodinated contrast materials
Classification of RCM
No of iodine atoms
Osmotic particles
I:P ratio
Mol.wt Iodine content
osmolality
Ionic monomer
3 2 3:2 600-800 70 1500-1700
HOCM
Diatrizoate
Iothalamate
Metrizoate
Non ionic monomer(LOCM)
3 1 3:1 700-800 150 600-700
Iohexol
Iomeron
Ionic dimer LOCM
6 2 3:1 1269 150 560
Ioxaglate
Non ionic dimer LOCM
6 1 6:1 1550-1626
300 300
Iodixanol
Iotrolan
Preference for iodine• High efficacy in absorbing X-
rays within diagnostic energy spectrum
• Chemical versatility allowing allowing stable binding of multiplicity of atoms to one organic molecule
• Low toxicity if released from RCM
Physico-chemical properties• Solubility• Water content• Electrolytes• Calcium binding• O2 tension• Viscosity• Osmolality• Mixing with other fluids• pH and buffering capacity
Does our body react to it? The reactions to contrast
material can be classified as• By systems with various
manifestations• With intensity of reaction and
treatment essence• Mode of reaction to the RCM
• On intensity Mild reaction Signs and symptoms appear
self-limited without evidence of progression
• Nausea, vomiting, Altered taste, Sweats Cough, Itching, Rash, Warmth, Pallor Nasal stuffiness, Headache, Flushing Swelling: eyes, face Dizziness Chills Anxiety Shaking
• Rx-Requires observation Patient reassurance
Moderate • Signs and symptoms are more
pronounced. Tachycardia/bradycardia
Bronchospasm, wheezing, Hypertension Laryngeal edema, Generalized or diffuse erythema, Mild hypotension, Dyspnea
• Rx-require prompt treatment. close, careful observation
for possible progression to a life-threatening event.
• Severe Signs and symptoms are often
life-threatening, including: Laryngeal edema Convulsions
(severe or rapidly progressing) Profound hypotension Unresponsiveness Clinically manifest arrhythmias Cardiopulmonary arrest
• Rx-prompt recognition and aggressive treatment; manifestations and treatment frequently require hospitalization.
To proceed with severe reaction• Airway secured, on artificial
ventilation.• External cardiac massage and
external DC version• IV fluid infusion to restore
blood volume and IV drug administration
• a powerful diuretic frusemide 20–40 mg IV slowly or IM for pulmonary oedema
• diazepam and barbiturates for convulsions
• adrenaline • salbutamol (b2 agonist metered
dose inhaler) • hydrocortisone or methyl
prednisolone (100–1000 mg) • aminophylline (very slowly,
250–500 mg)
• chlorpheniramine for allergic or anaphylactic symptoms
• vasopressors, e.g. noradrenaline (or metaraminol 0.5–5 mg slow IV infusion)
• dihydroxyphenylaline (or dopamine) infusion (2.5–5μg kg-
1 min-1) for hypotension with monitoring of the blood pressure
• Adrenaline is main stay in treatment of the condition dosage being 0.3-0.5 ml of 1/1000 solution.
• Who react very often Patients with a previous ADR
to RCM Asthmatics Allergic and atopic patients Cardiac patients with
decompensation, unstable arrhythmia, recent myocardial infarction
Renal patients in failure, diabetic nephropathy, on metformin
Feeble infants and aged patients
Patients with various metabolic and haematological disorders
Thyrotoxic: goitrous patients
Premedications• 1.Prednisone – 50 mg orally at
13 hours, 7 hours, and 1 hour before contrast media injection, plus
Diphenhydramine – 50 mg intravenously, intramuscularly, or by mouth 1 hour before contrast medium injection.
• 2. Methylprednisolone – 32 mg orally 12 hours and 2 hours before contrast media injection. An antihistamine can also be added to this regimen.
Patient selection and preparation strategies
• History – A careful, focused history is the necessary first step.
• Hydration – This should be adequate in all patients and is especially important in patients with renal dysfunction or paraproteinemias & in others (e.g., neonates, elderly, & debilitated individuals) who would be compromised by dehydration.
• Have equipment and expertise ready
• Heads up! – Be aware of specific risks, the patient’s status, possible reactions & the best response to them, & where & how to get help.
Special conditions• Pregnancy-iodinated contrast
can be given.Thyroid function of the neonate should be checked in first week of life
• Treatment with beta blockers-may impair response to treatment of bronchospasm induced by RCM
• Lactation-no special precaution required
• Thyrotoxicosis-IV contrast C/I in hyperthyroid.
• Avoid thyroid uptake studies & treatment for two months after iodinated contrast administration
• Pheochromocytoma-advised alpha & beta blockers with orally administered drugs before iodinated contrast
• Sickle cell anemia-risk of ppting crisis,iso-osmolar contrast indicated
• Myelomatosis-Bence jones proteins can ppt in the tubules,adequate hydration required
Why react?• Inhibition of enzymes such as
cholinesterase, resulting in increased concentration of acetylcholine;
• Release of vasoactive substances such as histamine, serotonin or bradykinin may result in vasomotor collapse.
• Activation of physiological cascade systems including the complement activation system
the kinin system with bradykinin release, the coagulation system inducing intravascular coagulation and the fibrinolytic system causing lysis of fibrin and blood clots.
• The immune system disturbances.
• Anxiety, apprehension and fear of the radiological procedure.
• Chemotoxicity depends on intrinsic structure.
Effects on erythrocytes and endothelium depends on hyperosmolaltity.
Due to cation and the anion.• Hyperosmolar reactions Endothelial damage Erythrocyte damage• Blood brain barrier damage• Vasodilatation & hypervolemia• Cardiac depression
Contrast induced nephropathy• Definition CIN is a condition in which an
impairment in renal function (increase in serum creatinine >25% or 44 micromol/L) occurs within 3 days after IV administration of contrast medium in the absence of an alternative cause.
• Markers
• Risk factors Increased serum creatinine
levels,particularly secondary to diabetic nephropathy
Dehydration Congestive heart disease Age older than 70 yrs Concurrent administration of
nephrotoxic drugs(e.g,NSAIDS,Aminoglycosides)
Hypertension Hyperuricemia Multiple myeloma
• Reducing the risk of CIN Identifying pts at risk normal serum creatinine
<1.2mg/dl for females & <1.4mg/dl for males.
serum creatinine >1.5 mg/dl or clearance <60ml/min/1.73 m2 is defined as renal impairment
patients with clearance <30ml/min/1.73 m2 are definitely at risk.
Choice & dose of contrast media. Hydration - normal saline iv 4-6 hrs before
and after contrast medium at rate of ml/kg/hr.
- isotonic bicarbonate 1 hr before at the rate of 1 mL/kg/hr for 6 hrs after infusion
- isotonic bicarbonate with NAC (dose of 1200 mg twice a day for 48 hrs,starting 24 hrs before contrast administration)
• Outpatients with moderate renal impairment (GFR 45-60 mL/min) 1000 mL/hr before & after contrast medium
• Patients receiving larger doses or with advanced chronic renal disease ( GFR < 45 mL/min ) better hydrated with IV saline.
• Pharmacological manipulation NAC reduces nephrotoxicity
through anti oxidant and vasodilatory effects
theophylline fenoldopam & CCB’s can be used.
• DO’s hydrate use low/iso-osmolar RCM stop nephrotoxic drugs 24 hrs
before RCM consider alternatives
• DON’TS use of High osmolar RCM administer large doses of
contrast administer mannitol &
diuretics perform multiple studies within
72 hrs
Contrast agents & renal tract• Intravenous urography better delineation Average adult dose being 20g
of iodine independent of kidney function
- the nephrogram has two components
->vascular blush which is most prominent in 20-60 sec after contrast injection
->tubular opacification which begins 1-2 min after injection.
• Diagnostic quality is related to filtered load,amount of the contrast excreted.
• UV=GFR*P
Contrast agents & the GIT• Contrast agents to consider are• Barium Practical properties - adherence of barium to
mucosal surface - must not flocculate when in
contact with the mucosa
Factors governing• Particle size & shape ranging between 0.1-20 micro
m.• Density of barium w/v or w/w. high density barium >200%w/v medium density 100-200%w/v low density 50-100%w/v• Gums for adherence
• Flocculation of barium usually negatively
charged,flocculates if positive ions are added to the suspension.
• Stabilising agents• Clinical applications for esophagus both single &
double contrast 100%w/v is adequate
for stomach high density barium 240%w/v
• For small bowel if follow through low density barium 40%w/v if small bowel enema higher density about 100%w/v• For large bowel moderate density 80-120%w/v
Complications • Leakage into the pleural or
peritoneal spaces• Leakage into the mediastinum• Possible pulmonary aspiration• Given orally in suspected large
bowel obstruction
Role of iodinated contrast • Investigations of possible leaks
from the upper GI tract, esophagus & duodenum.
• Gastrograffin (75% aqueous solution of sodium & methylglucamine diatrizoate with 0.1% Tween 80)
Uses • Esophageal tear• Duodenal perforation• Small bowel ileus vs mechanical
obstruction• In CT 3% solutions 1 hr before
the procedure• Investigation & treatment of
meconium ileus• Post surgical anastomosis
C/I’s• Causes severe chemical
pneumonitis so c/i in case of suspicion that aspiration into bronchial tree may occur.
• Hyperosmolar effect draws water into the bowel loops in a small child & infant may cause severe electrolyte disturbance & death.
• In this cases Non ionic contrast iopamidol with flavouring agent is used.
Biliary system• Cholecystographic agents
(iopadate & iopanic acid)• Cholangiographic agents
(meglumine iotroxate) Contraindications & adverse
effects• Oral agents Hepatic dysfunction Parotitis skin rash & most
commonly GI symptoms diarrhoea.
• IV agents Acute anaphylactoid reactions Bronchospasm &
cardiovascular collapse• Absolute contraindications myeloma & waldenstrom’s
macroglobulinemia
Contrast agents in Ultrasound• Requirements Easily introducible Stable in the duration of
examination Low toxicity Modify one or more acoustic
properties of tissues
Blood pool agents• Free gas bubbles normal saline indocyanine green renograffin• Limitations large in size effectively filtered
by lungs unstable,go back into the
solution withinn second or so.
• Encapsulated air bubbles Levovist 99.9%
microcrystalline galactose microparticles & 0.1% palmitic acid
microbubble size 3 to 4 micro m.
Echovist a galactose agent with larger bubbles used for visualisation of non vascular structures
• Low solubility gas bubbles To increase back scatter &
longevity of the bubbles,low solubility gases as perfluorocarbons with low diffusion rate & increased longevity are used.
Sonovue with sulfur hexafluoride & phospholipid
Optison with perfluoropropane filled albumin shell
• Selective uptake agents Colloidal suspension of liquids
are taken up by the reticulo endothelial system from where they are excreted
Levovist provides late phase of enhancement in liver parenchyma & spleen.
Bubble behaviour & incident pressure
• Microbubbles scatter ultrasound in a manner dependent on the sound to which they are exposed
• At low incident pressures they produce linear back scatter enhancement,resulting in augmentation of the echo from the blood
• As it increases the beyond 50 to 100 kPa contrast agent back scatter begins to show non linear characters,such as emission of harmonics
• As peak pressure reaches near 100 kPa transient non linear scattering resulting in destruction of the bubble
Peak pressure Bubble behaviour
Acoustic behaviour
Application
<100 kPa Linear oscillation
Linear backscatter enhancement
Doppler signal enhancement
0.1-0.5 mPa Non linear oscillation
Harmonic backscatter
Real time vascular imaging
>0.5 mPa Disruption Transient non linear echoes
Interval delay perfusion imaging
Thank you