Contrast Agents in Dentistry

8/13/2019 Contrast Agents in Dentistry

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INTRODUCTION:

Image formed on radiograph is as result of differentialattenuation of the x-ray beam by structures through

which X-ray pass,

Structures that lack sufficient density to attenuates thebeam do not appear on the radiograph.

If the densityof a structure of interest is too low to bevisualized on an X-ray image or if the subject contrast

is too low to meet the specific diagnostic needs ,the

contrast & the density can be improved artificially


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The use of artificially induced contrast has beenhelpful in allowing the evaluation of the structures

that would otherwise be radiographically invisible.

Use of radiopaque agent is termed as positive contrast

agent

whereas use of gas like air, o2, co2 is termed as

negative contrast agent.When both are used concomitantly, it is known as

double contrast.


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WHY CONTRAST MEDIA ARE NECESSARY ?

1. Different tissues within the body attenuate the X-ray beam todifferent degrees-the degree of attenuation is depends upon

electrons in the path of the beam with which it interacts.

2. the no. of electrons in the path of the beam dependds upon

three factors:a) Thickness of the object

b) Density : difference between two organs ,such as between ms

of heart & the air in the lungs,

c) Atomic no: difference between atomic no. between two tissuessoft tissues composed of elements with low atomic no. and

bone which is composed of high atomic no.


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WHY CONTRAST MEDIA ARE NECESSARY ?

The density of hollow organs is reduced by filling it with gas orair providing negative contrast

The average atomic no. of the hollow structure such as blood

vessel can be increased by filling the lumen with liquid such as

high atomic no.than the blood such as IODINE


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DEFINATION of contrast :

It is defined as radiopaque substances that havebeen developed to alter artificially, the density of

different parts of the patient so altering the subject

contrast.


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1. SIALOGRAPHY: It Is The Study Involving Salivary Glands

2. ATHROGRAPHY: It Is The Study Involving Joints Of The Body

3. ANGIOGRAPHY: To Study The Blood Vessels

4. LYMPHOGRAPHY: This Study Involves Lymph Nodes

5. UROGRAPHY: This Is The Study Carried Out For Kidney

6. BARIUM SWOLLOW MEAL: This Is The Study Of GIT

7. COMPUTED TOMOGRAPHY: It Is Used For General Enhancement

STUDIES INVOLVING CONTRAST AGENTS:


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REQUIREMENT:

RADIOPAQUE : it should be adequatelyradiopque to show good contrast.

MINIMUM SIDE EFFECTS : it should have

no harmful effects at all i.e should be

biologically stable.

LESS VISCOCITY: it should not be so

viscous that it requires considerable pressure

to be introduced.LOW SURFACE TENSION: it should have

low surface tension.


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Classification

According to CHARR DH in 19881) Depending upon the nature of material

a) Iodine based

b) Noniodine based

2) Depending upon the solvent

a) Conventional ionic water soluble

b) Oil soluble

3)Depending on the ionic naturea) Monoacidic monomer

b) Nonacidic monomer

c) Monoacidic dimer

d) Non ionic dimer


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Classification :

According to WHAIRES E IN 1996Barium sulphate suspensions for investigating the gastrointestinal tract

Iodine-based aqueous solutions used for all other investigations and divided into:

Ionic monomers, including:

* iothalmate (e.g. Conray)

* metrizoate (e.g. Isopaque)

* diatrizoate (e.g. Urografin)

Ionic dimers, including:

* ioxaglate (e.g. Hexabrix)

Non-ionic monomers, including:

* iopamidol (e.g. Niopam)

* iohexol (e.g. Omnipaque)

* iopromide (e.g. Ultravist)

Iodine-based oil solutions such as Lipiodol (iodized poppy seed oil) used for lymphography and sialography

MR contrast agents (e.g. gadolinium)


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Chemistry of barium sulphate and iodine

BARIUM SULPHATE:1) it is a crystalline salt insoluble in water

2) the mineral barite is composed largely of barium sulphate and

is common are of barium

3) although barium is a heavy metal and it is water soluble

compound are often highly toxic

4) extreamly low solubility of barium sulphate protects the

patients from absorbing harmful amounts of metal

Specific gravity4.5

Melting point

1580 degree centigradeDensity4.5 gm/cm3


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IODINE:-Atomic wt127

It is the only element which is proved satisfactory for general use

as an intrvascular contrast media

Iodine provides the radiopacity

The other elements of radio contrast media molecule provide no

radiopoacity but acts as carrier of the iodine and which markdly

reducing toxicity of molecule

Over 90% being eliminated by glomerular filtrate by kidneys

withinn12 hrs


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General properties of contrast media

1) VISCOSITYViscocity of contrast medium is important because it helps to

determine the force required to inject it through a needle or

catheter into a patient which turn limits the rate at which it can be

injected

2) OSMOLALITY:the sensation of heat and discomfort or even pain experienced by

the patient are directly related to the osmolarity of the contrast

media

3)CHEMOTOXICITY:

Refers to mechanism responsible for causing the toxic effects ofthe contrast media which can not be explained by other means


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Ideal properties of CONTRAST AGENTS

1) Safe2) Non Toxic

3) Should not cross blood brain barrier or placental barrier

4) Should have similar properties when compared to blood ,body

fluids,saliva

5) Should be pharmacologically inert

6) Opacificaton

7) Low surfacetention

8) Easy to inject

9) Elimination should be easy but the eliminaton time should besufficient

10) Residual contrast media

11) Should Be Cost Effective


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CONTRAST agents in sialography:

Salivary gland are soft tissue structures , so they can not be visualisedradiographically

they are visualised by the technique of sialography which involves the technique

of retrograde filling of luminal system of gland with radiopaque contrast media

August fredrick 1972merqury as contrast agent

Carpy 1909 performed 1 st sialography

Contrast sialography can be performed using either lipid soluble or water

soluble agents

A major disadvantage of the lipid soluble agent is that they are not diluted in

saliva or absorbed by glandular mucosa resulting in optimum opacification ofboth ductal and acinar elements

used commonly when to see small peripheral masses


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Water soluble angiographic dyes containing about 28-38% iodineused in contrast sialography

A major disadvantage with this dyes is that they are easily diluted

in saliva and get rapidly absorbed across glandular elements

CLASSIFICATION OF CONTRAST AGENTSUSED IN SIALOGRAPHY:

1) Lipid soluble or fat soluble contrast media

2) Water soluble contrast media


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Lipid soluble contrast media:

1) Iodised oils:

a) Ethiodolb) Lipidol

c) Lipidol uf

d) Todochioral

Advantage :1) Opacification : satisfactory

2) visualization : sharper ,with good resolution of the most

peripheral ducts

Disadvantage:1) Produces greater degree of Discomfort

2) Inflammatory reactions --grannuloma formation,subsequent fibrosis

3) Gland clouding due to greater amount of contrast medium within the

lining of fine duct and capillaries


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2) Water insoluble organic iodine compundse.g-pantoapaque

myodil


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Water soluble contrast media:

e.g_ hypaque 50, urograffin,hypaque 75, renograffin 60

&73,amipaque ,isopaque ,conray 80&420Properties

1) Miscibiltythey are miscible with body fluids and saliva

2) Iodine content-28-30 w/w

3) Viscosity 2-10 centipores

4) Hyper tonic compare to saliva and body fluids

Advantage :

1) Filling of finer duct system

2) Discomfortless pain &less discomfort to patient

3) Excretion- they are rapidly removed from the tissues

Disadvantages:

1) Less contrast

2) Less time retention in body


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Contrast Media In Arthrography:

Inability of plain radiography to demostrate either the articularcartilage or bounderies of synovial space needs contrast media

introduced in to joint space followed by x-ray examination

When employed in temperomandibularbjoint it is known as

temperomandibular joint arhtrography

Pass in 1939 acomplished the 1st

use of arthrography inevaluating TMJ

Single contrast arthrography:

Usually performed by introducing the contrast medium into the

lower joint space

The single contrast technique yield mre information about jointdynamics


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Double contrast arthrography:Performed when the iodinated contrast medium and air

are introduced in both upper and lower joint space

Double contrast tech gives more informatics regarding

joint morphologyWater soluble contrast agents are preffered.


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Contrast media in lymphangiography

The demostration of internal architecture of normal sized or

enlarged lymph nodes requires the ingestion of radiopaque

contrast media into efferent lymphatics,

Lipoidol and patient blue violet also called as

sulphan blue or /acidblue are /commonly usedin lymphangiography


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Contrast media in computed tomography:

Need for using contrast media is to obtain the differential change

in the attenuation values of normal and pathological tissues

Contrast agents can be administrated prior to C SCAN to allow

organs and structures to be seen more easily

Most widely used material is 30 mg of iodine for an avg built

which can be scaned. 5-15 min later.Agents can be administrated through a vein (iv),by injection or

taken orally.


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Contrast Agents Available In Indian Market

An angiograffin: it contains 0.65 gm meglumindiatrizoate in aq. Sol ( iodine conc.306mg /ml)

inj.20ml amp and 50 ml vial

barium sulphate x-ray_ba2so4 400gm

Magnevist- 469mg gadpenetate acid dimoglumine saltin aq sol 10 ml & 20ml vial

Radiopaque (iohexol): 10-20-50 ml

Sunray 280

Sunray 420Ultravxist 300

urograffin


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Anaphylactoid (idiosyncratic)

unpredictabledose independent

prevalence 1-2% (0.04 - 0.22% severe)

fatal 1 in 75,000


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Risk Factors

Previous contrast reaction either moderate

or severeasthma

allergy history requiring medical treatment

pretesting poor predictor of reaction

Repeat Reactions, ionicbronchospasm 40% to facial edema 70%

decrease to 6 - 9% with pretreatment

decrease to 0.6% with pretreatment and switchto nonionic


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Late Reactions

1 hr to 1 week following contrastinjection

Headache, myalgias, fever, skin

reactions

Risk Factors

Previous contrast reaction

Interleukin-2 treatment

usually self-limited, treat severereactions with steroids


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Severity of Reactions - Minor

Nausea & vomitingUrticaria

Pruritis

Diaphoresis

S f


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Severity of Reactions - Moderate

FaintnessFacial edema

Laryngeal edema

Bronchospasm

S it f R ti S


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Severity of Reactions - Severe

Pulmonary edemaRespiratory arrest

Cardiac arrest

Seizures


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Renal Toxicity(increased serum creatinine by more than 25% or > 0.5mg%)

2-7%

Risk Factors5 - 10 fold increase with pre-existing renalinsufficiency (increased creatinine)

Dehydration

CHF

Age > 70

Taking nephrotoxic drugs (nonsteroidalinflammatory agents, gentomycin etc.)


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Renal Toxicity(increased serum creatinine by more than 25% or > 0.5

mg%)direct relationship between serumcreatinine and likelihood

nephrotoxicity

Hydrate 100 ml/hr Normal saline 4 hrsprior to procedure, continue for 24

hours

Those on hemodialysis do not needextra sessions or dialysis

immediately following contrast

administration

M tf i (Gl h )


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Metformin (Glucophage)

oral diabetic agentpatients with renal insufficiency may

develop lactic acidosis

withhold drug for 48 hrs after

contrast administration in all patients

taking this drug

T t t C t t R ti


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Treatment Contrast Reactions

Nausea & Vomitingusually self-limited

protracted: Prochlorperazine (Compazine) 5-10

mg IM

UrticariaDiphenhydramine (Benadryl) 25 - 50 mg IM,

caution: drowsiness

add Cimetidine (Tagamet) 300 mg in 20 ml, IV

slowly

T t t C t t R ti


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HypotensionBradycardia (Vasovagal)elevate legs (infuses 700 ml)

IV fluid (normal saline)

O2 3 L/min

atropine 0.6 mg IV push, repeat up to 3 mg total

Tachycardiaelevate legs

IV fluid (normal saline) may require > 1 Liter

O2 3 L/min

T t t C t t R ti


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Bronchospasm or laryngeal edemaO2 3 L/min

Epinephrine 1:1000 (0.1 - 0.2 ml subq) or

1:10,000 1 ml IV over 3 min

Beta 2 agonist 2 -3 puffs

albuterol (Proventyl)

metaproterenol (Alupent)

terbutaline (Brethaine)

T t t C t t R ti


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Anaphylactoid

O2 3 L/min

IV normal saline

Epinephrine

Benadryl 25 - 50 mg IVTagamet 300 mg in 20 ml IV slowly

Solu-medrol 1 gm IVNote: if patient taking beta blocker

glucagon 1 - 5 mg IV bolus followed by infusion5-15 ug/min or

isoproternol 1:5000 (0.2 mg/ml)IV 0.5 - 1.0 ml diluted in 10 ml

1 mg increments

T t t C t t R ti


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Seizuresprotect airway

Diazepam (valium) 5 mg IV slowly

Suspected pheochromocytoma

phentolamine (Regitine) 5.0 ml (5 mg) IV bolus

Pregnancy

Discard breast milk for 24 hours following

contrast administration

E t ti


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Extravasation

Elevate extremityIce pack 3x day

Observe for 2-4 hours if volume > 5ml

E tra asation


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Extravasation

Plastic Surgery Consultation

ionic > 30 ml

nonionic > 100 ml

skin blistering/significant tissue damage

altered tissue perfusion

increasing pain after 2-4 hours

change in sensation distal to site of

extravasation

Pretreatment Protocols


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Reduces minor reactions

Benadryl 50 mg IM or PO 1 hr before

procedure

Prednisone 50 mg PO 13, 7, 1 hr beforeprocedure

Observe patient at least 30 minutes following

injection



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Reduction of Nephrotoxicity

Creatinine level > 2 mg/dl

Hydrate patient - Oral fluids if unable to drink use

IV salineMild Renal Insufficiency Patients add N-acetyl-

cysteine (Mucomyst) : 600 or 1,200 mg PO BID the

day before and day of the procedure or 150 mg/kg

IV over .5 hr or 50 mg/kg IV over 4 hr

Reference:


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Reference:

1) White and pharoh 5th&6thedition

2) Ultrasound Contrast Media in the Study of Salivary Gland Tumors

ADOLFO GALLIPOLI1 , IOVANNI MANGANELLA 2 , ELISABETTA DE

LUTIO DI CASTELGUIDONE ANGELO MASTRO

3) Alternative and specialized imaging modalities

4) CONTRAST AGENTS FOR RADIOLOGY PROCEDURES

5) Contrast Agents for Radiology Procedures: Reimbursement Policy

(Effective 11/01/2012)1996-2012, Oxford Health Plans, LLC

6)CONTRAST MEDIA TUTORIALJessica B. Robbins, MD Myron A.

Pozniak, MD

7) ACR Manual on Contrast Media Version 8 2012 ACR Committee on Drugs

and Contrast Media

Documents

Contrast Agents in Dentistry