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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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Treatment Contrast Reactions
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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Treatment Contrast Reactions
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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Treatment Contrast Reactions
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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Treatment Contrast Reactions
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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Pretreatment Protocols
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
Pretreatment Protocols
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Pretreatment Protocols
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