This document provides an overview of contrast media used in medical imaging, including barium sulfate, iodinated contrast media, and gas agents. It discusses the classification, properties, administration, and adverse reactions of different contrast types. Barium sulfate is described as the preferred oral and rectal contrast due to its insolubility, inertness, and ability to coat the gastrointestinal mucosa. Iodinated contrast media are classified based on osmolality, ionicity, and iodine content. Water-soluble iodinated contrasts are preferred over oil-based agents. An ideal contrast is outlined as having properties like water solubility, chemical stability, biological inertness, and renal excretion.

1. CONTRAST MEDIA, APPLICATION,
ADVERSE REACTIONS AND THEIR
CONTROL
1

2. CONTENTS:
INTRODUCTION
TYPES OF CONTRAST MEDIA
• . INSOLUBLE CONTRAST (BARIUM SULPHATE)
MEDIA
• ADVERSE REACTIONS OF BARIUM
• WATER SOLUBLE IODINATED CONTRAST MEDIA
• ADVERSE REACTIONS OF IODINATED
CONTRAST MEDIA
• TREATMENT OF REACTIONS
• MRI CONTRAST
• ULTRASOUND CONTRAST
 CONCLUSION.
2

3. INTRODUCTION
Contrast media are used to make specific organs,blood vessels
and/or tissues stand out with more image contrast to better show
the presence of disease or injury.

4. WHY IS A CONTRAST AGENT REQUIRED?
• Using contrast agents, contrast of the medical image is
increased which enhances the visibility and improves
detection.
• Both static and dynamic images can be made during
contrast examination.
• Static image i.e. radiographic film provides
morphological information while continuous monitoring
during contrast administration provides additional
functional information.

5. CLASSIFICATION OF CONTRAST MEDIA
POSITIVE CONTRAST
RADIOOPQUAE
• INSOLUBLE BARIUM SULPHATE
• ORGANIC IODIDE COMPOUNDS
NEGATIVE CONTRAST
NON RADIOOPQUAE
• AIR
• CARBON DIOXIDE
NEUTRAL CONTRAST
• PEGLEC
• MANNITOL
• PLAIN WATER

6. PARAMETERS OF CONTRAST MEDIA
There are major differences between the contrast
media, not only whether they are ionic or non-ionic
relative to blood, but also between non-ionic molecules,
which differ in many other parameters.
Osmolality,
Viscosity,
Chemotoxicity,
Hydrophilicity etc.
OSMOLALITY
Can be expressed as concentration of particles per kg of
solvent. (in medicine milliosmoles per kg of water)
The closer the osmolarity of radiological contrast media is to
that of body fluids the better the general tolerance.
 Osmolality of blood = 285 – 295 mOsm/Kg H2O
 isosmolar CM (visipaque) = 290 mOsm/Kg H2O
 LOCM (optiray 300) =651 mOsm/Kg H2O
 HOCM (conray 400) = 2300 mOsm/Kg H2O
 MAGNEVIST = 1960 mOsm/Kg H2O
VISCOSITY
 Viscosity describes the thickness or resistance to flow
of a contrast agent.
 The thickness of the contrast agent is related to the
concentration,the size of the molecules in a specific
contrast agent and the temperature of the contrast
agent.
 The viscosity affects the rate that the contrast media
can be injected.
CHEMOTOXICITY
 The clinical effects of contrast agents not only result from
high osmolality,but also from their own specific
pharmacology,which mediates chemotoxic effects.
 No. Of properties of CM relate to this term like
hydrophilicity, lipophilicity, protein binding etc.
 Hydrophilicity of CM is its preference for aqueous
solvents.
 Lipophilicity is its preference for fat-like organic solvents.
 Protein binding refers to the % of CM which becomes
bound to plasma proteins in blood stream. Ionic agents have
high degree of protein binding. So, these can’t be rapidly
eliminated by kidneys. These have more chemotoxicity than
non-ionic agents.

7. Modes of administration
Via Intravascular injection:
 Intravascular contrast
helps to highlight blood
vessels & to enhance the
tissue structure of various
organs of the body.
Oral route:
 Oral contrast is used to
enhance CT images of the
abdomen & pelvis or in G I
tract studies or to see any
leak in the GI tract. The
contrast agent used is
gastrograffin.
Rectal route:
 The contrast agent Gastrograffin/Ba is
usually used for rectal study. The rectal
contrast helps outlining not only the large
intestine, but also the bladder, the uterus
in female patients & other organs in the
large gut.
Directly injected into cavities:
 The iodine contrast media is also
used to opacify the cavities by
injecting directly into the cavities of
the body.

8. CONTRAST MEDIA USED IN GIT
 Earlier CM used in GIT was iodised oil. But
due to its oily nature, it didn’t coat the
mucosa.
 Later on, Bismuth Sulphate came into use.
 Nowadays, BaSO4 is a medium of choice.

9. CHARACTERISTICS OF AN IDEAL CONTRAST MEDIA IN GIT
Should fill the entire bowel lumen.
Should be palatable.
Non irritating to the intestinal mucosa.
Should pass rapidly through the GI tract without producing
artifacts or stimulating vigorous peristalsis.
Preferably the contrast media should coat the gut mucosa.
Heat and chemical stability.
Biological inertness.
Reasonable cost.

10. WHY BARIUM
ONLY ?
Barium has high atomic no.(56). So it is highly radio-
opaque.
It is insoluble in water or lipid.
It is non-toxic.
It is inert to tissues.
It is non-absorbable
It is suitable for double contrast studies.

11. PROPERTIES OF BARIUM SULPHATE
B aSO4 PROPERTIES
Form White crystalline powder
Molecular weight 233.39
Specific gravity 4.5
PH 5.3
Atomic number of Ba 56
Particle size 5 - 12µm

12. AVAILABLE FORMS OF BASO4
Commercially prepared Ba formulations in India are
manufactured by M/s. ESKEY fine chemicals Ltd.
Microbar paste :-
 100% high viscosity paste in collapsible tubes.
 This is a high density, high viscosity preparation used for
conventional studies of the pharynx & oesophagus.
Microbar suspension :-
 95% moderate density & viscosity suspension for
oesophagus, stomach & G.I studies.
 Marketed in one liter bottles.

13. CONTD
.
Microbar HD :-
200% high density, low viscosity preparation, supplied in a
powder form in a tumbler pack.
By adding 70 ml of water to this & shaking the tumbler the
desired amount of suspension is formed which is ideal for
double contrast studies for oesophagus , stomach, and
duodenum.
 Sachets of gas producing powder are supplied with the
pack.

14. 14
CONT...
ADVANTAGES:
1. Non-absorbable. Therefore
it doesn’t get degraded
throughout the bowel .
2. It coats the mucosa in a
thin layer thus allows the
introduction of negative c/m
without significant
degradation.
DISADVANTAGES-
• Subsequent abdominal CT and U/S
examinations of the pt. can’t be done.
Patients may be asked to wait for up to 2
weeks for satisfactory clearance of
barium.
• High morbidity associated with barium in
the peritoneal cavity.

15. 15
ADDITIVES USED IN BARIUM SULPHATE
Additives are added to influence -
• Rate of settling
• Viscosity
• Mucosal coating
• Flocculation
No. of additives added are-
Suspending agent- used to prevent settling and
increase the viscosity of suspension.
• Eg. gum acacia or carboxymethyle cellulose.
Antifoaming agent- used to prevent formation of air
bubbles.
• Eg. Simethicone or methylpolysilioxone.

16. 16
Cont…
Preservative- used to prevent fungal
growth.
e.g. Earlier methyl paraben, now Sodium
metabisulphate is used.
Flavoring agent- strawberry ,lemon, mint
Anta acid- to neutralize gastric acid and
prevent flocculation.
e.g. Sodium citrate
Aluminum hydroxide
Magnesium sulphate

17. DILUTION
Methods to describe a particular dilution
are as follow:---
a) Weight by weight
b) Weight by volume
c) Volume by volume

18. ADVERSE REACTIONS OF Barium
 Chemical peritonitis due to extravasation of BaSO4.
 Extravasation into bronchial tree, urinary tract and
other body cavities will produce inflammation.
 Barium suspension may cause allergy.
 Intravascular entry of Ba can cause embolism.
 Ba encephalopathy.
 After exam, may solidify difficult to evacuate.

19. NEGATIVE CONTRAST AGENT
 CO2 and room air used with Ba to achieve double
contrast effect.
 For upper GI tract CO2 is administered orally in the form
of gases producing granules/ powder.
THE REQUIREMENTS OF THESE AGENTS ARE-
Production of adequate volume of gas i.e., 200-400ml.
Non interference with the Ba coating
No bubble production.
Rapid dissolution ,leaving no residue
Easily swallowed
 Low cost

20. Other gas producing agents are:
 Sodium bicarbonate
 Tartaric acid
 Citric acid
 ENO
 Coke

21. Differences b/w positive and negative CM
• Negative contrast
• AIR OR CO2
• Radiolucent
• Low atomic #
material
• Black on film
• Positive contrast
• all others
• Radiopaque
• High atomic # material
• White on film

22. • Made from fatty acids
• Insoluble in water
• Iodine are added to ester groups
• Long persistence in body
• Infrequently used except for specific
exams like sialography and HSG
• Slowly absorbed by body tissues
• Examples : myodil, lipidol
OIL
BASED

23. IDEAL CONTRAST AGENT
• Water soluble
• Chemical and heat stability
• Biological inertness
• Low viscosity
• Lower or same osmolality as human serum
• Selective excretion(i.e.kidneys)
• Safety
• Low cost
• Not interfere with physiological
homeostasis
IODINATED CONTRAST MEDIA

24. WHY IODINE?
 Iodine provides excellent radio opacity because
 higher atomic no(53).
 K shell electron binding energy of 34 kev,which is lower than but close to
the mean energy used in diagnostic x rays,thus maximizing the
photoelectric effect.
 Low toxicity
 MORE THE IODINE CONCENTRATION->MORE THE RADIOOPACITY
MORE ADVERSE REACTIONS

25. CLASSIFICATION OF IODINATED CM
HIGH OSMOLAR CM LOW OSMOLAR CM
Ionic monomers
• Iothalamate
• Diatrizoate
Ionic Dimers
• Ioxaglic acid
• Iocarmic acid
Non-Ionic monomers
• Metrizamide
• Iohexol
• Iopamidol
• Ioversol
Non-Ionic dimers
• Iotrol
• Isovist

26. OSMOLALITY-SIGNIFICANCE
 Hyperosmolar contrast –tissue damage,sudden drawing
of water from the cellular and interstitial spaces towards the
plasma->
 -local effects(heat,pain),
 -systemic effects(vasodilatation,alteration of vascular
endothelium permeability,hyperaemia,strong osmotic
diuresis).
 Iso osmolar contrast –advantages in patients with renal
disease.

27. IONICITY
 Characteristic of the molecule to break into positively
charged cation and negatively charged anion->more
molecules per kg of water,increasing osmolality.
IODINE PARTICLE RATIO-
 no of iodine atoms per molecule
 :No of osmotically active particles per molecule of solute in
solution.
 For ionic contrast media-3:2
 For non ionic contrast media-3:1

28. HISTORY OF ICM
In 1923,1st report of opacification of urinary
tract after iv injection of 10% sodium
iodide for treatment of syphilis by Osborne.
Pure iodine-high toxicity,poor radiological
contrast.
Organic compounds were bound to iodine.

29. HISTORY OF ICM
1930s-Monoiodinated pyridines-
Uroselectan A(Iopex)
Diiodinated-Uroselectan B(Neoiopex)

30. NEXT ICM:TRIIODINATED BENZENE RING
AGENTS
1950s
Sodium and meglumine salts of triiodinated
benzoic acid(acetrizoic acid)-UROKON
1956
Sodium and meglumine salts of diatrizoic
acid-HYPAQUE,RENOGRAFFIN
1962
IOTHALAMATE(CONRAY)

31.  In 1969 Almen first postulated that many of the adverse
effects of contrast media were the result of high osmolality
and that by eliminating the cation,which does not contribute
to diagnostic information but is responsible for up to 50% of
the osmotic effect,it would be possible to reduce the toxicity
of contrast media*.
 To combine two tri-iodinated benzene rings to produce an
ionic dimer with six iodine atoms per anion.
 The alternative more successful approach was to produce
compounds that do not ionize in solution(Non-ionic).*

32. STRUCTURE OF ICM
1
2
3
4
 All are derivatives of tri iodo benzene
ring.
 C1: in ionic contrast media-acidic group
with sodium or meglumine is attached.
 :in non ionic-amide group is
attached
 Iodine atoms are attached at 2,4 and 6
carbons.
 C3 and C5 –amide attachments to
increase solubility and reduce protein
binding.

33. IONIC MONOMERS
 Also known as high osmolar CM or conventional
CM.
 These are salts consisting of a sodium or
meglumine cation and a triodinated benzoate
anion.
 Ratio of 3 iodine atoms per molecule to 2 particles
in solution i.e. 3:2.
 Examples are diatrizoic acid(urograffin),
Iothalamic acid(conray)

34. DIFFERENCE B/W MEGLUMINE SALTS AND SODIUM SALTS
Meglumine salts Sodium salts
Solubitity Better Same,less in some
acids
Viscosity High Low
Tolerence Better Less,causes nausea
and vomiting
Blood brain barrier No effect Crosses(BBB)
Vascular effect Less Marked
Diuretic effect Strong Less
Opacification Poor Better
Bronchospasm Causes,so
contraindicated in
bronchial asthma
No

35. IONIC DIMERS
 Two benzene rings (each with 3 iodine
atoms) are linked by a bridge to form a
large compound.
 Carries only one carboxylic group. So
known as monoacid dimers.
 Iodine particle ratio is 6:2.
 Example: Ioxaglate(hexabrix)
 Conc. of 59%(320 mg/ml),relatively low
osmolality of 600mosm/kg

36. NON-IONIC MONOMERS
 Carboxyl group of monomeric salts is
replaced by a non-ionizing radical and
CONH2 producing an iodine particle ratio of
3:1.
 Metrizamide was the earliest non-ionic
monomer and proved as an excellent CM
but was very expensive, impossible to
autoclave and unstable in solution.
 Relatively low osmolality(600-800 mosm/kg).
 So 2nd generation of CM is introduced.
 IOHEXOL(OMNIPAQUE)
 IOPAMIDOL(ISOVUE)
 IOVERSOL(OPTIRAY)
 IOMEPROL(IOMERON)
 IOBITRIDOL

37. NON-IONIC DIMERS
 A ratio of 6 iodine atoms for each
molecule in solution with satisfactory
iodine concentration at iso-osmolality. So
known as iso-osmolar CM.
 These agents have very low toxicity
because of iso-osmolarity, non-ionic
character and also these posses a very
large no. of hydroxyl group.
Most ideal contrast media-deliver most iodine with
least effect on osmolality(290 mosm/kg)
At approx. 60% by wt conc,they are iso osmolar with
plasma
Disadv-higher viscosity,greater resistance to
catheter injection.
Examples: Iotrolan(isovist)

38. IONIC VS.NON IONIC ICM
IONIC NON-IONIC
Dissociates into separate
ions when injected
doesn’t dissociate
creates hypertonic
condition
Remains nearly isotonic
increase in blood
osmolality
no significant increase in
osmolality
Less cost more cost
More adverse reactions less adverse reactions

39. GENERAL GUIDELINES FOR ICM ADMINISTRATION
 All ICM stock should be monitored by designated
nursing and CT staff.
 All nurses/technologists/radiologists should personally
inspect contrast containers/vials for integrity,signs of
contamination and also check expiry date.
 The ICM should be stored at less than 37 degree C
for a max period of 1 month.
 All multidose contrast containers/vials should be
properly labelled along with the time when they were
opened.
 All expired contrast containers/vials should be properly
disposed.

40.  The dosage and technique of ICM should be
decided under the guidance of a radiologist.
 Only authorised persons,i.e.technologists and
nurses should inject ICM under supervision of a
radiologist.
GENERAL GUIDELINES FOR ICM ADMINISTRATION

41.  IV route-MC used
 iv canula is inserted and contrast is directly injected
 When power injector is utilised,20G or large needle
or canula 1.25 to 1.5 inches in length is used.
 To ensure adequate catheter placement->check
backflow of blood and flush canula with saline.
 Care should be taken while injecting contrast
through pre existing lines.
 Only power injection rated peripherally inserted
central catheters(PICC) or central lines are
approved for power injection.
GENERAL GUIDELINES FOR ICM ADMINISTRATION

42.  Max.flow rate and psi set for adult-5 ml/sec at <300 psi
pediatric-2ml/sec at <300 psi
 Injection rate will depend on specific catheter type,size
and examination protocol.
 Special care must be taken while injecting the contrast
via central line.
 If not power rated,injection must be hand held.
 Hand injection of contrast is acceptable if the examination
does not require arterial phase.
 RIGHT PATIENT
 RIGHT CONTRAST
 RIGHT DOSE
 RIGHT ROUTE
 RIGHT TIME
GENERAL GUIDELINES FOR ICM ADMINISTRATION

43.  Patient should not eat 4 hours prior to the study.
 He/she should bring all the previous records.
 He/she should bring all the material required for the study.
 Patient preparation as per procedure should be checked.
 Report of the tests as per the study required, must be done
e.g. RFT
 Patient/attendant should be explained the procedure and
consent should be taken.
GENERAL GUIDELINES FOR ICM ADMINISTRATION

44. Any History of reaction from any medicine : _YES_ NO
Any History of Contrast Reaction _YES_ NO
History of Asthma and no pretreatment for current study _YES_ NO
Significant cardiac dysfunction _YES_ NO
Severe renal dysfunction (Creatinine> 2.5 mg/dl) _YES_ NO
Diabetes and on Glucophage:
Glucophage must beheld for 48 hrs foll. The CT exam
_YES_ NO
LMP of the female patient _YES_ NO
Have you eaten or drunk in the last 4 hours? _YES_ NO
Have you had a barium study in the last week? _YES_ NO
Patient risk assessment: risk
factors

45.  Essential to know S.creatinine levels and GFR before
injecting contrast.
 Recent S.creatinine levels(done within 6 wks)
AVOID CONTRAST IF:
 S.CREATININE >1.5 MG/DL IN A DIABETIC PATIENT
 >2 MG/DL IN A NON DIABETIC PATIENT
 GFR<30 ML/MIN
 PATIENTS WITH END STAGE RENAL DISEASE ON
CHRONIC PERITONEAL DIALYSIS
GUIDELINES FOR ICM ADMINISTRATION

46. DOSE OF ICM
 Potential risk factor for contrast reactions and
nephropathy
 Concern if undergoing catheter angiography and
CT on same day.
 Lowest dose necessary for optimal contrast,AND
NOT max. recommended dose.
 Discuss risks and benefits with patient and treating
clinician.
 Standard dose- 1-2 ml/kg at conc. of 300 mg/ml.
 Max.dose is 200 ml of agent with conc.of 320
mg/ml iodine(total of 64 g of iodine)-but depends
on patient factors,such as level of hydration.

47. FACTORS AFFECTING CONTRAST ENHANCEMENT
Use of lower CT tube voltages (in peak kilovolts) yields
stronger contrast enhancement for a given injection of contrast
medium.
The most important patient related factor affecting the
magnitude of vascular and parenchymal contrast enhancement is
BODY WEIGHT.
Injection duration is the most important injection-related factor
affecting CT scan timing

48. FACTORS AFFECTING CONTRAST ENHANCEMENT

49. FACTORS AFFECTING CONTRAST ENHANCEMENT

50. ADVERSE REACTIONS TO ICM
CONTRAST REACTIONS
IDIOSYNCRATIC
REACTIONS
NON IDIOSYNCRATIC
REACTIONS
CHEMOTAXIS RELATED
UNRELATED TO
CONTRAST MEDIA
OSMOLARITY

51. IDIOSYNCRATIC ANAPHYLACTIC REACTIONS
 Unpredictable reactions which occur within 1 hr of
contrast media administration,and are unrelated to the
amount of contrast media above a certain level.
 Most dreaded and are most severe as they occur
WITHOUT WARNING, cannot be reliably predicted and
are not preventable.
 85% of cases begin immediately after injecting contrast.

52. Mild Moderate Severe
Nausea, vomiting,
cough, sneezing,
warmth, headache,
dizziness, shaking,
altered taste, itching,
pallor, flushing,
chills, sweats, rash,
hives, nasal
stuffiness, anxiety,
sneezing, swelling –
eyes, face
Tachycardia/Bradyc
ardia, hypertension /
hypotension,
pronounced
cutaneous reaction,
Dyspnea,
Bronchospasm /
wheezing.
Laryngeal edema,
convulsions,
profound
hypotension,
clinically manifest
arrhythmias,
unresponsiveness,
Cardiopulmonary
arrest.
TYPES OF IDIOSYNCRATIC ANAPHYLACTIC REACTIONS

53. MECHANISMS OF IDIOSYNCRATIC ANAPHYLACTIC REACTIONS
 Inhibition of enzymes
 Release of vasoactive substances
 Activation of physiological cascades
 Immunological disturbances
 Anxiety,apprehension and fear

54. RISK FACTORS FOR IDIOSYNCRATIC ANAPHYLACTIC REACTIONS
 Type of contrast agent-more with HOCM than
LOCM/IOCM
 Previous adverse reaction to same contrast medium-most
impt.
 Asthmatics
 Allergic and atopic patients
 Patients on drugs like beta adrenergic blockers
 Patients with impaired cardiovascular and renal systems
 Diabetics.
 Patients with metabolic and hematological disorders.
 Thyrotoxic:goitrous patients
 Feeble infants and aged patients.
 Severe general debility.
 Very nervous,anxious patients

55. PREVENTION OF ACUTE IDIOSYNCRATIC REACTIONS
 Consider alternative tests
 Chioce of contrast agent-most impt(4-5 times lower
risk with non ionic LOCM)
 Premedication-
 Elective-50 mg hydrocortisone by mouth at 13,7,1 hr
before,and
 Diphenhydramine-50 mg i m/iv/oral 1 hr before
contrast
 Emergency-hydrocortisone 200 mg iv 4 hrly ,and
diphenhydramine 50 mg iv 1 hr before contrast
injection.

56. NON-ANAPHYLACTOID REACTIONS
 Other reactions relating to osmotic, chemotoxic,
direct organ toxicity, or vasomotor effects are more
predictable and better understood.
 These reactions do not have the characteristics of
an anaphylactoid reaction and are therefore
referred to as nonanaphylactoid.

57. Chemotoxic Reactions:
 Chemotoxic side effects include neurotoxicity, cardiac
depression, arrhythmia, electrocardiogram changes,
and renal tubular or vascular injury.
 Some chemotoxic side effects appear to relate to the
ionic nature and content of contrast media that
dissolved in solution.
 Nonionic contrast media are associated with fewer
chemotoxic side effects.

58. Vasovagal Reactions:
 Vagal reactions occur as a result of increased vagal tone
on the heart and blood vessels.
 The result is bradycardia and decreased blood pressure
and may be accompanied by apprehension, confusion,
sweating, unresponsiveness, and loss of bowel or bladder
control signals.
 Some vagal reactions may not be caused by the contrast
media but instead may be the result of coincident events
related to the examination (e.g., needle puncture, or
abdominal compression).

59. Idiopathic Reactions:
 Other reactions, without having a
chemotoxic or vasovagal basis, can
occur.
 When these reactions are
encountered, the underlying
pathophysiology cannot be defined.

60. TREATMENT OF REACTIONS

61. URTICARIA
• Discontinue injection if not completed.
• No treatment needed in most cases.
• Give H1 receptor blocker: diphenhydramine(benadryl)
PO/IM/IV 25-50mg.
• If severe or widely disseminated: give alpha-
agonist(arterial and venous constriction) epinephrine
SC(1:1000) 0.1-0.3mg (if no cardiac contraindications).

62. FACIAL OR LARYNGEAL EDEMA
• Give O2 6-10 litres per min via mask
• Give epinephrine SC or IM(1:10,000) 0.1-0.3ml or
especially if hypotension evident give it 3ml slowly IV
• If not responsive to therapy or if there is obvious acute
laryngeal edema, seek proper assistance.

63. HYPOTENSION WITH TACHYCARDIA
 Legs elevated 60degree or more
 Monitor elecrocardiogram, pulse oxymeter, B.P.
 Give o2 6-10 litres/min via mask
 Rapid IV administration of large volumes of NS
 If poorly responsive: epinephrine slowly IV 0.1
ml(=0.1mg). Repeat as needed upto a maximum of
1mg.

64. HYPOTENSION WITH BRADYCARDIA
 Secure airway: give O2 6-10 litres/min
 Monitor vital signs
 Elevate legs
 Secure IV access: rapid administration of NS
 Give atropine 0.6-1mg if patient doesn’t respond quickly to the
above steps.
 Repeat atropine up to a total dose of 0.4mg/kg in adults
 Ensure complete resolution of hypotension and bradycardia
prior to discharge

65. HYPERTENSION SEVERE
 Give O2 6-10 litres per min.
 Monitor electrocardiogram, pulse rate, BP.
 Give nitroglycerine 0.4mg tablet sublingual or topical 2%
ointment, apply 1inch strip.
 If no response, consider labetalol 20mg IV, then 20-80mg IV
every 10 minutes upto 300mg.
 Transfer to ICU or emg.

66. SEIZURES AND CONVULSIONS
 Give O2 6-10litres /min
 Consider diazepam 5mg iv(or more as appropriate) or
midazolam 0.5-1 mg IV
 If longer effect needed, obtain consultation; consider phenytoin
infusion– 15-18mg/kg at 50mg/min
 Careful monitoring of vital signs required, particularly of po2
because of risk to respiratory depression with benzodiazepine
administration.

67. EXTRAVASATION OF CONTRAST
 Extravasation of contrast material from the vessel into
which it is introduced into the surrounding tissue or body
cavity.
0.1 -0.9%
RISK FACTORS
 Atherosclerotic Peripheral vascular disease
 Diabetic vascular disease
 Raynud’s sisease
 Venous thrombosis
 Prior radiation Therapy
 Extensive Surgery
 Severely ill/Debilitated Patients
 Injection through indwelling peripheral venous
Lines(>24 hrs)
 Multiple punctures into the same vein.

68. EXTRAVASATION OF CONTRAST
 Can occur during hand or power injection.
 Frequency is not related to injection flow rate.
 May involve large volumes of contrast media.
 More common with injections on dorsum of
hand,foot or ankle.
 d/t hyperosmolarity of extravasated fluid->incites
local inflammatory response.
 LOCM rarely cause severe adverse effect.
 Most extravasations are limited to immediately soft
tissues.
 NO PERMANENT INJURY

69. EXTRAVASATION OF CONTRAST-CLINICAL FEATURES
MILD SEVERE
• TISSUE EDEMA
• ERYTHEMA
• STINGING
• TENDERNESS
• COMPARTMENT SYNDROME-MC
• SKIN ULCERATION
• TISSUE NECROSIS

70. EXTRAVASATION OF CONTRAST-CLINICAL FEATURES
 Initial symptoms may be relatively mild.
 SEVERITY AND PROGNOSIS DIFFICULT TO DETERMINE ON
INITIAL EVALUATION OF AFFECTED SITE-CLOSE FOLLOW UP
FOR SEVERAL HOURS IS ESSENTIAL.
 NO EFFECTIVE TREATMENT
 Elevation of affected extremity above the level of heart to decrease
capillary hydrostatic pressure and promote absorption of fluid.
 No clear evidence regarding use of warm or cold compresses,
aspiration of extravasated fluid or injection of hyaluronidase or
corticosteroids.

71. EXTRAVASATION OF CONTRAST-TREATMENT
 OPD patient should be released from radiology department
only after the radiologist is satisfied that the signs and
symptoms have improved or new symptoms have not
developed.
 Clear instructions for additional medical care in case of
worsening of symptoms,skin ulceration,development of any
neurologic deficit or circulatory symptoms
 Surgical consultation for severe extravasation injury.
 Proper documentation

72. COMBINED REACTIONS
 In some patients, Anaphylactoid reactions and
nonanaphylactoid reactions can occur or appear to occur
simultaneously. The end result may be a complex, life-
threatening situation with a patient in shock.
 In others, such as patients who develop sudden
cardiopulmonary arrest, the reaction cannot be
specifically classified.
 Careful attention to the specific signs and symptoms of
a reaction should help in identifying the exact causes of
the reaction.
 A careful history of any medication ingested prior to the
exam can aid in identifying possible contributory effects
of the medications.

73.  In evaluating a patient for a potential contrast reaction, five
important immediate assessments should be made:---
 patient look
 patient’s voice sound
 patient’s breathing
Patient’s pulse strength and rate
Patient’s blood pressure
 These findings allow for proper diagnosis of the reaction including
urticaria, bronchospasm, facial or laryngeal edema etc.

74. CONTRAST MEDIA IN MRI
 Tissue contrast in MRI – difference in relaxation
times.
 Previously thought that MRI, due to excellent soft
tissue contrast will obviate the need for a external
agent, making it non invasive.
 But in many pathological conditions, no enough
difference in relaxation times to get a tissue
contrast.

75. WHY DO WE USE A CONTRAST AGENT?
 To differentiate structures similar in appearance.
 To provide additional specificity in description of
a abnormal signal.
 To specify/ highlight spaces.
 To depict tissue vascularity and perfusion.

76. BASIC PRINCIPLES
 Contrast enhancement in MRI – based on NMR with
proton spin relaxation:
- i.e MR contrast agents alter the T1 and T2
relaxation times – measured as ‘relaxivity’ of an agent
 Relaxivity of a contrast agent is directly proportional
to
 Magnitude of the magnetic moment
 Tumbling frequency in solution
 Spin relaxation time (T1 and T2 contrast agents)

77.  When molecules with one or more unpaired electrons
are placed in a magnetic field- their magnetic
moment aligns with the field.
 Such molecules are called as paramagnetic,
superparamagnetic and ferromagnetic ions.
 MC used – exogenous paramagnetic compounds of
gadolinium, manganese or iron

78. CLASSIFICATION OF MR CONTRAST AGENTS
Based on
 Magnetic property of the agent:
• Paramagnetic
• Superparamagnetic
 Dominant effect of the agent on signal
intensity (image enhancement):
• Positive
• Negative
 Biodistribution of the agent:
• Extracellular fluid agents
• Intravascular agents
• Tissue specific agents

79. BASED ON THE MAGNETIC PROPERTY
Paramagnetic agents:
 Have their own magnetic field
 This magnetic field reduces the T1 and T2
relaxation times of the surrounding protons *
 MC used is Gadolinium (Gd-3+) – has 7
unpaired electrons with a long electron spin
relaxation time* (relaxation enhancing agent)
 Other metals – Mn
 Always chelated to a appropriate ligand * to
reduce toxicity

80. Superparamagnetic agents:
 Similar mechanism as that of paramagnetic agents.
 These are small/ ultrasmall particles of
superparamagnetic iron oxide.
 If the iron ions in these agents are magnetically ordered
within the crystal, a large net magnetic moment is
produced (ie., supermagnetisation)*
 Dominant effect on T2 relaxation time (due to large
magnetic moment)
BASED ON THE MAGNETIC PROPERTY

81. BASED ON IMAGE ENHANCEMENT
 Positive contrast agents:
 Increase in T1 enhancement *
 eg: Gadolinium
 Negative contrast agents:
 Increase T2 enhancement (signal reduction)
 All MR contrast agents affect both T1 and T2
relaxation times – differences are based upon the
dose given
 Gadolinium – positive enhancement on T1
weighted images, weak T2 negative enhancing
effect, whereas iron oxide – predominant T2/ T2 *
shortening effect

82. BASED ON BIODISTRIBUTION
 Extracellular fluid agents:
 Small molecular weight paramagnetic
substances
 Diffuse into the interstitium but not taken up
by the cells
 Excreted by kidneys (so T1/2 is based on
GFR)
 Eg: Gadolinium
 Intravascular agents:
 Large molecules
 Eg: iron oxide nanoparticles, macropolymer
bound Gadolinium
 Bind with plasma proteins, so stay
intravascular.

83.  Tissue specific contrast agents:
Accumulate in a given organ or tissue type.
Eg: 1) iron oxide compounds – specifically taken up by the
Kupffer cells causing dominant T2/T2* shortening. So these
compounds are both intravascular and tissue specific.
2) liver specific agents : Mangafodipir trisodium and few
chelates of gadolinium – hepatocyte specific.
3) atherosclerotic plaque specific.
4) tumor antibody specific.
BASED ON BIODISTRIBUTION

84. GADOLINIUM BASED CONTRAST AGENTS (GBCAS)
 Usually used in the form of Gd-DTPA chelate
 High tolerability
 Good relaxation property
 Chemically inert
 Low doses : reduction in T1 relaxation time-
increased signal intensity in T1 weighted images.
 Free Gd not used – competes for calcium binding
sites
 Currently 9 compounds in use

85. GBCAS
• NON SPECIFIC
EXTRACELLULAR GBCAS *
• HIGH RELAXIVITY AGENTS
 Gadopenetate(Magnevist)
 Gadoterate (Dotarem)
 Gadodiamide (Omniscan)
 Gadoteridol (Prohance)
 Gadobutrol (Gadovist)
 Gadoversatamide(Optimark)
 Gadobenate (Multihance)
 Gadoxetate*(Eovist)
 Gadofosveset (Vasovist)

86. NON SPECIFIC ECF AGENTS
 Three phases of contrast enhancement:
 Arterial phase: (first 20 sec)
 Early arterial- for depicting vessels
 Late arterial – to depict hypervascular
lesions
 Blood pool phase (PV phase) – max. liver
enhancement
 ECF phase
 Routine PC images – at 2 mins when contrast has
reached ECF – Fat Sat. images give best contrast
 If IR sequences used, they not only supress fat but
also the enhancing tissue – so STIR not used

87.  Interstitial agents- concentrate predominantly in the
neoplastic and inflammed tissue and fibrous tissues
(due to large interstitial space), despite being
hypovascular.
 Brain and testes – not permeable, wheras injured brain
parenchyma enhance more due to increased
interstitium
 Filtered by the glomerulus and is concentrated in the
tubules – cause enhancement of the kidneys and
urinary tract

88. HIGH RELAXIVITY GBCAS
 Higher T1 relaxivity as compared to the ECF agents.
 These agents bind to proteins and have a higher T1
relaxivity
 Immediately taken by liver – on early images can help
characterise the lesion like other agents. On delayed
imaging, normal hepatocytes enhance more - liver specific
agents on delayed phase - Best used for metastasis.
 Gadoxetate disodium has the maximum biliary excretion
(almost equal biliary and renal excretion) and has a
convenient delayed imaging time of 10 to 20 minutes - can
be mapped on T1 sequences.
 It also results in a much more intense liver parenchymal
enhancement than gadobenate.

89. BASED ON BIOCHEMICAL STRUCTURE
GBCAs can be classified as:
 Linear, ionic—Gadopentetate,(Magnevist)
Gadobenate, (Multihance)
Gadoxetate (Eovist)
Gadofosveset. (Vasovist)
 Linear, nonionic—Gadodiamide (Omniscan)
Gadoversetamide(Optimark).
 Macrocyclic, ionic—Gadoterate.(Dotarem)
 Macrocyclic nonionic—Gadoteridol (Prohance)
Gadobutrol (Gadovist)

90.  The nonionic agents tend to have lower
osmolarity and are less viscous.
 Nonionic low osmolar GBCAs also have
fewer negative isotropic effects, which is an
important consideration for cardiac patients.
 Low viscosity GBCAs require less pressure
to inject and can be administered using
smaller gauge needles or catheters

91. INTERACTIONS
 GBCAs (free Gd) significantly interact
with blood levels of
 Calcium
 Iron
 Magnesium
 TIBC
 Should be tested only after 24 hours of
contrast injection.
 Osmotic load of GBCAs – low as
compared to iodinated contrast media.

92. CURRENT INDICATIONS OF GBCAS
 Clinical indications for the brain, spine and body for
gadolinium include (but are not limited to):
 tumors pre - and post - operation
 pre- and post- radiotherapy
 infection
 infarction
 inflammation
 post- traumatic lesions
 post- operation lumbar disc.
 contrast- enhanced MRA.

93. GADOLINIUMADMINISTRATION/ DOSE
 The recommended dosage of gadolinium is
0.1 millimoles per kilogram (mmol/kg) of body
weight, (0.2 ml/kg)
 Single dose
 Double dose
 Triple dose

94. Adverse effects of GBCAs
 Less common with extracellular contrast agents.
 Usually mild in the form of nausea, vomiting and urticaria.
 Uncommon- dizziness, headache, taste disturbances,
parasthesias – if known asthma/ allergy/ fast injection.
 Nephropathy and NSF.
 Anaphylactoid/ fatal reactions- extremely rare.
 Gadolinium deposition diseases.

95. CONTRAST INDUCED NEPHROPATHY
• Extracellular agents are more nephrotoxic than the
iodinated contrast media (ICM).
• But the dose used is very less as compared to ICM,
so nephropathy is less common even in kidney
disease.
• CIN at normal doses occurs when there is
markedly reduced renal function due to diabetes.

96. • Gadolinium attenuates x rays, so can be used
instead of iodinated contrast media in allergy.
• Extravasation:
• Can occur at local site or distant site
• Causes edema, inflammation and necrosis
• Less tolerable in children, old age and patients
with pre-existing vascular compromise.

97. NEPHROGENIC SYSTEMIC FIBROSIS
• 1997 – nephrogenic fibrosing dermopathy
(resembling sclerosing oedema).
• Presents as scleroderma like skin changes, fibrotic
changes in the viscera (heart, lung, liver, kidney and
testis).
• Occurs within days to months
• Mechanism unknown. Proposed hypothesis – Gd
forms other cations by transmetallation. Free Gd
binds with anions, precipitates subcutaneously and
causes fibrotic reaction.

98. RISK FACTORS FOR DEVELOPMENT OF NSF
• Acute kidney disease / CKD
• Co factors:
• Acidosis
• Increased iron
• Immunosuppresion
• Vasculopathy
• EPO therapy
• Reported for all GBCAS, MC with gadodiamide.
• Based on the prevalence of NSF, GBCAS are classified
(ACR) into three groups

99. ACR GUIDELINES ON GBCA USAGE
• Prior to an MRI using a GBCA, physicians should
identify renal dysfunction by history and evaluation
of the eGFR within 6 weeks of the procedure in
patients with:
• Renal disease (including patients with a solitary
kidney, renal transplant, or renal neoplasm)
• Over the age of 60 years and
• With hypertension, diabetes mellitus, or a history
of severe liver disease
• If a risk factor is identified, avoid using GBCA’s or
use least possible dose

100. • If the patient has ESRD and is on dialysis:
• Prefer CT with iodinated contrast over a CEMRI
• If to be used group 1 agents are strictly contraindicated
• If the patient has stage IV/V CKD:
• CECT has risk of worsening of renal status.
• If to be used, use as less dose as possible (avoid group-1)
• If the patient has stage III CKD:
• NSF occurrence rare
• If eGFR <40 ml/min- follow precautions as that of stage IV/V.
• If eGFR 40-59 ml/min – no special precautions needed.
ACR GUIDELINES ON GBCA USAGE

101. • If patient has stage I/II CKD:
• Can be safely used
• In AKI:
• To be used with caution
• Differentiate AKI vs acute on CKD
• Avoid group I agents
• No e/o hemodialysis in preventing or treating NSF in
patients not already undergoing hemodialysis, but it may
be useful to remove GBCAs in patients already on
hemodialysis.
ACR GUIDELINES ON GBCA USAGE

102. In children:
• Accurate calculation of eGFR according to body surface
area essential, especially in preterm infants
• Follow same guidelines as adults
In pregnancy:
• GBCAs cross placenta.It is then excreted by fetal kidney
and can re-circulate through amniotic fluid several times
However no studies on teratogenesis has been done. To
consider risk-benefit ratio.
• In lactation:
• Minute proportion secreted in breast milk, however is safe.
ACR GUIDELINES ON GBCA USAGE

103. GADOLINIUM DEPOSITION DISEASES
• In repeated injections of ionic linear agents (gadopenetate).
• E/o gadolinium in patient’s system after 30 days of injection in
a patient with normal renal function.
• Dose dependant relationship.
• Due to gadolinium deposition in the capillary endothelium and
neural interstitium.
• Deposited in globus pallidus, thalamus, dentate nucleus and
pons.
• Presents as generalised body pains, headache, bone pain,
skin thickening in legs and arms.

104. COMMONLY AVAILABLE GBCAS
• DOTAREM / ATRIREM (GADOTERATE – DOTA)
• MAGNEVIST (GADOPENETATE- DTPA)
• OMNISCAN (GADODIAMIDE- DTPA-BMA)
• OPTIMARK (GADOVERSETAMIDE-DTPA-BMEA)
• PROHANCE (GADOTERIDOL-HP-DO3A)
• GADAVIST (GADOBUTROL-BT-DO3A)
• EOVIST/PRIMOVIST (GADOXETATE-EOB-DTPA)
• ABLAVAR (GADOFOSVESET-DTPA-DCHP)

105. MANGANESE BASED CONTRAST AGENTS
Mangofodipir –
• Resembles vit B6 structurally.
• Taken up by hepatocytes - increases signal
intensity of normal hepatic parenchyma – so
there is increased liver – lesion contrast
• Also accumulates in pancreas – so can be used
in HBP pathologies
• Unlike GBCAs, MBCAs readily dissociate to free
Mn – potential toxicity in the form of PD like
symptoms and hepatic dysfunction.

106. IRON OXIDE BASED CONTRAST AGENTS
• Potential liver specific contrast agents.
• Contain a core of soluble iron oxide (MC – magnetite) coated
with dextran/ BD polysaccharide.
• Each crystal – several paramagnetic iron ions.
• With a external b, strong magnetisation is produced – shortens
t2 relaxation time – decreased signal intensity on t2
• Purely intravascular.
• Eliminated by the RES.

107. CONTRAST MEDIA IN ULTRASOUND
• A contrast agent may be applied during USG
exams, although their usage has not been
worldwide spread.
• USG contrast agents boost echogenicity of blood
which can heighten the tissue contrast and better
delineate body cavities.

108. IDEAL QUALITIES OF USG CONTRAST AGENTS
High echogenicity
Low attenuation
Low blood solubility
Lack of biological effects with repeat doses
Low diffusivity
Ability to pass through capillary bed

109. USG CONTRAST AGENTS
• These are composed of a solution of gas-filled
microbubbles.
• Smaller than rbcs, less than 8 microns in size.
• The ingredients are not intrinsically toxic.
• Due to different impedances of gas and liquid, these
create backscattering effect which increases
echogenicity of blood.

110. CLASSIFICATION OF MICROBUBBLES
1stGen:unstabilisedbubbles, used
only for cardiac and large vein
studiese.g.Agitated saline,Levovist
2ndGen:longer lasting bubbles
coated with shells of protein, lipids
or synthetic polymers e.g.Sonovist
3rdGen:encapsulated emulsions or
bubbles, offer high reflectivity
e.g.Sonovue(BRI)Bracco

112. DIFFERENT TYPES OF CONTRAST MEDIA IN USG
Tissue specific C/M:- important in examining liver, kidney,
pancreas, prostate & ovary by improving acoustic difference
between normal & abnormal portion of the organs. E.G.
Sonovist, levovist & sonozoid.
Vascular c/m:- use air encapsulated by albumin & have
diameter < 5-10 um, used in evaluating cardiac, liver, kidney
disease & malignant tumour in these organs.
C/m for targeted imaging:- used in detection of thrombus,
carcinoma, inflammation. These have high sensitivity and
specificity.

113. REFERENCES
A guide to radiological procedures:
Chapman and Nakielny
Radiological procedures A guide by Dr
Bhushan N Lakhkar
www.xray2000.uk
www.radiology.com
www.google.com

114. CONCLUSION
• The universal use of non ionic monomers/dimers as an IV
contrast agents has a favorable safety profile. But the use of
non ionic contrast media (monomers & dimers) depends upon
the type of studies.
• At present gadolinium chelates are the most widely used
contrast agents in MR imaging and the only MR contrast
agents available in india
• They are easily available, have good tolerability and provide
excellent lesion detection and characterization.
• The main concern with GBCAs is NSF, which is seen to occur
only in patients with severe renal disease.
• Tissue specific and pathology specific contrast agents are the
future trend.

115. THANK YOU