Contrast rad sem / dental implant courses

Seminar on
CONTRAST
RADIOGRAPHY
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
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• Contrast is the difference in image density
appearing on a radiograph
,representing various degrees of beam
attenuation.
(Langland &
Langlias)

• Contrast radiography is exaggerating
the differences in density of tissues or
organs or Intraluminal filling defects,
usually by the introduction of contrast
agents.

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• Contrast agents, also known as contrast media, often
are used during medical imaging examinations to
highlight specific parts of the body and make them
easier to see.
• Contrast agents are administered in different ways:
Some are given Orally, others are injected or delivered
through an Intravenous Line or an Enema.

• After the examination, some contrast agents are
harmlessly absorbed by the body.
• Others are excreted through the urine or bowel
movements.
• Contrast agents are not dyes; they do not permanently
discolour internal organs.
• Instead, they temporarily change the way x-rays or other
imaging tools interact with our body.

CONTRAST MEDIACONTRAST MEDIA::
•Substances that increase contrast between
specific structure and background thus
improve conspicuity of structure and enable
improved evaluation ..

BRIEF HISTORY
• In 1863, Walter Bradford Cannon, a UnitedIn 1863, Walter Bradford Cannon, a United
States physician, found that aStates physician, found that a BismuthBismuth
compound could be used to create images ofcompound could be used to create images of
the digestive tract.the digestive tract.
He developed a method of examining theHe developed a method of examining the
gastrointestinal system usinggastrointestinal system using BariumBarium
compound.compound.

Ideal requirements of Contrast Media:
Safe to use and handle.
Non-toxic.
Should be removed from the body easily.
Should be stable in the body and in storage.
Should not have any side effects.
Should not penetrate the Blood Brain Barrier.

Their transfer to the breast milk and placentral
passage should be limited.
Viscosity should be within acceptable limits to allow
easy and rapid injection.
Should have no adverse reactions.
Should not be very expensive.

Why contrast media are necessary
• Different tissues within the body attenuate
the beam of X-rays to different degrees.
• The degree of attenuation of an X-ray
beam by an element is complex, but one of
the major variables is the number of
electrons in the path of the beam with
which it can interact.

• In a complex mixture of elements, which
is what we are concerned with in the
organs of a patient, the degree of
attenuation is particularly influenced by
the average of the atomic numbers of all
the atoms involved.

• Where there is a considerable difference
between the densities of two organs,
such as between the solid muscle
of the heart and the air in the
lungs, then the outlines of the structures
can be visualised on a radiograph
because of the Natural contrast that
exists.

• Similarly, if there is a difference between the
average atomic numbers of two tissues, such as
between soft tissues, which are composed of
elements of Low Atomic Number and Bone,
which is partly composed of the element
Calcium, with a rather higher atomic number,
then the outlines of the different structures can
be seen by Natural contrast.

• However, if the two organs have similar
densities and similar average atomic numbers,
then it is not possible to distinguish them on a
radiograph, because no natural contrast
exists.
• This situation commonly occurs in diagnostic
radiography, so that, for example, it is not
possible to identify Blood Vessels within an
organ.

• Two of the factors important in organ contrast that can
be artificially altered are the density of an organ, and,
more usefully, the average atomic number of a
structure.
• The density of a hollow organ can be reduced by filling
it with gas or air, providing negative contrast.
Ex: gas is introduced into the stomach or colon during
a double-contrast Barium examination.

• The average atomic number of hollow structure such as
a Blood Vessel can be increased by filling the cavity with
a liquid of much higher average atomic number (such as
iodine containing contrast medium) than that of Blood.
• This is the principle by which contrast media consist of
solutions or suspensions of non-toxic substances that
contain a significant proportion of elements of high
atomic number, usually iodine.

D.H. Charr (1988) classified contrast media
into various types:
1.Depending on the nature of material
a. Iodine based
b. Non-Iodine based Eg. Barium Sulphate
2. Depending on the solvent
a. Conventional Ionic water soluble
b. Oil Soluble
Classification

3. Depending on the ionic nature:
a. Mono acidic monomer
Ex. Diatrizoate, Iothalurate
b. Non-ionic monomer
Ex. Iopamidol, Iohexol, Ioversol
c. Mono acidic dimer
Ex. Hexabrix
d. Non-Ionoic dimer
Ex. Iodixanol, Iotrol.

Whaites E. (1996) classified contrast media as :
1. Barium Sulphate suspension for investigation of
GIT
2. Iodine based aqueous solution used for all other
investigations and divided them into:
a. Ionoic monomers,
Ex. Iothalamate, Metrizoate, Diatrizoate
b. Ionic dimers,
Ex. Ioxaglate
c. Non-ionic monomers
Ex. Iopamidol, Iohexol
3. Iodine based oil solutions.

Negative contrast media
Air: Procedures which used air as C.M include -
Arthrography
Ventriculography
Bronchography etc.
• Advantage over gases (Co2 & O2 ) –
slowly absorbed from the injection site giving more time
for imaging.
Complications : Air embolism
• Also used in double contrast studies of the GIT(such as
barium enema).

Mode of action
• Gas displaces, rather than mixing with the Blood & they
act as a negative C.M.
• It rapidly dissolves in the blood and is excreted as it
passes through the lungs.

Advantages of CO2 over iodinated
contrast media :
• Absence of both nephrotoxicity & allergic reactions.
• Can be used in pt with previous reaction to ICM & in
asthmatics & Pts with impaired renal function
• Unlimited volume of CO2 can be delivered in multiple low
volume injections.

Adverse Reactions
According to Ansell(1970):
Minor reactions:
• Nausea, mild vomitting,feeling of heat, limited
urticaria, pain, sneezing, mild pallor, sweating.
Intermediate reactions:
• Giddiness, severe vomitting, extensive
urticaria, Edema of face/glottis, Bronchospasm,
dyspnoea, chest/head/abdominal pain,
thrombophlebitis, thrombosis.

Major reactions:
• Loss of consciousness.
• Cardiac arrest / Arryhythmias,
• Pulmonary edema,
• Pulmonary embolus.

MANAGEMENT OF
ANAPHYLACTIC
REACTION

Grade 1
• Reassurance
• Close watch till the symptoms subside

Grade 2 and grade3
reactions
• Skin reactions-if severe pruritis-
Diphenhydramine(50mg).
• Severe diffuse Erythema or Angioedema-
antihistamines.
• If still no response-Adrenaline,0.1-0.3ml
S.C.(1in1000)

Respiratory reactions-
• Laryngeal edema-O2, adrenaline,intubation
• Bronchospasm-
Mild- O2 10lit/min
Salbutamol(inhaler)
Moderate-
Adrenaline: 0.1-0.3ml s.c.
and repeated after 10-15 min
Severe- adrenaline I.v

Pulmonary edema:
• O2 10 lit/min
• Furosemide 40mg i.v.slowly
• Morphine 1-3mg i.v.
• Hydrocortisone 100mg i.v.slowly
• Shift to ICU.

Hypotension with Bradycardia-
• Mild-
O2 10lit/min
Isotonic I.v.fluids
• Severe -
Atropine0.6mg-1mg
I.v.slowly(repeat 3-5 times; Max dose-3mg)
Hypotention with Tachycardia-
Severe -adrenaline 1-3 ml(1-10000),i.v.upto
10ml or dopamine.

Seizures or convulsions :
• Mild –turn the patient to one side to
prevent aspiration.
Clean the airway.
O2 10 ml/min.
• Severe-diazepam 5mg i.v. slowly

IODINATED
RADIOLOGICAL
CONTRAST MEDIA

IODINE, the preferred element in the radiological
contrast media because-
• High atomic number=53,produces high contrast
density
• Low toxicity
• Relatively safe.

Classification of ICM
There are 4 chemical varieties of iodinated RCM in clinical
use
1. Ionic monomer:
Ex: Diatrizoate, Iothalamate
2. Nonionoic monomer:
Ex: Iohexol, Iopromide
3. Ionoic dimer:
Ex: Ioxaglate
4. Nonionoic dimer
Ex: Iodixanol

• Total iodine content in the body is 50mg.
• Very large amounts of iodine are necessary because of
the low sensitivity in conventional photographic film-
screen radiography.
• Alternative non-photographic X-ray detection recording
systems like CT are much more sensitive to minor
differences in iodine concentration contrast.
DOSAGE OF IODINE

•The average daily physiological turn over of iodine is
0.0001g.
• The total iodine content in the body (mainly in the
thyroid) is 0.01g.
• The requirement for a 2-, 3-, or 4-vessel angiogram (with
conventional film-screen recording) may be 70 g iodine
into the arterial supply trees of very sensitive organs, for
example the brain or heart.
• This is 700000 times the daily body turnover of iodine .

•This huge quantity of iodine can be accepted by
the body with very rare evidence of severe toxicity.
• As the iodine content of the contrast medium
molecule is about 50% by weight, approximately
140g of contrast agent may be required in a
multivessel angiographic study.
• Probably the largest quantity of any drug used
intravascularly in the whole of clinical medicine.

DIFFERENCES B/W OIL BASED
CM AND WATER SOLUBLE CM

CONTRAST STUDIES:
• These investigations use contrast media,
radiopaque substances that have been developed
to alter artificially the density of different parts of
the patient, so altering subject contrast — the
difference in the X-ray beam transmitted through
different parts of the patient's tissues.

Thus, by altering the patient, certain organs, structures and
tissues, invisible using conventional means, can be
seen.
Contrast studies, and the tissues imaged, include:
• Sialography — salivary glands
• Arthrography — joints
• Angiography — blood vessels
• Lymphography — lymph nodes and vessels.
• Urography — kidneys
• Barium swallow, meal and enema — GI tract.

Main contrast studies used in the head and neck:
These include:
• Sialography
• Arthrography
• Angiography — this involves the introduction of aqueous
iodine-based contrast media into selected blood vessels.
(In the head and neck region, this involves usually the carotids
(common, internal or external) or the vertebral arteries.

• Sialography can be defined as the radiographic
demonstration of the major salivary glands by
introducing a radiopaque contrast medium into their
ductal system.
• It is also very effective for the diagnosis of obstruction
whether caused by stones or strictures.
• It is widely used and is probably still the most common
specialized salivary gland investigation.
Sialography

An ideal sialographic contrast media should have the
following characteristics:
i.Physiological properties similar to that of saliva,
ii. Miscibility with saliva.
iii. Absence of local or systemic toxicity.
iv. Pharmacological inertness
v. Satisfactory opacification.
vi. Low surface tension and low viscosity to allow filling
of fine components of the ductal system.

vii. Easy elimination, but should be durable for sufficient time
so as to permit time for satisfactory radiographs
viii. Residual contrast media should be absorbed by the
salivary gland and detoxified by the liver or excreted by the
kidney

• The procedure is divided into three
phases.
1.The Preoperative phase
2.The Filling phase
3.The Emptying phase

Prophylactic measures to minimize
complications
• Use of low osmolality contrast agents
• Skin pre-testing.
• Prophylactic steroids
• Prophylactic Antihistamines
• Reassurance to reduce levels of anxiety
• Ask specifically about previous history of
iodine allergy.

Preoperative phase :
This involves taking preoperative (scout) radiographs, if
not already taken, before the introduction of the contrast
medium, for the following reasons:
• To note the position and/or presence of any
radiopaque obstruction
• To assess the position of shadows cast by
normal anatomical structures that may overlie
the gland, such as the hyoid bone
• To assess the exposure factors.

Filling phase:
• The relevant duct orifice needs to be found clinically,
probed and dilated, and then cannulated.
• The contrast medium can then be introduced.
• Three main techniques are available for introducing the
contrast medium, as described later.
• When this is complete, the filling phase radiographs are
taken.

Emptying phase:
• The cannula is removed and the patient allowed to rinse
out.
• The use of lemon juice at this stage to aid excretion of
the contrast medium is often advocated.
• After five minutes, the emptying phase radiographs are
taken, usually lateral oblique . These films can be used
as a crude assessment of function.

Contrast media used:
The types of contrast media suitable for sialography are all
iodine-based, and include:
Ionic aqueous solutions:
• Diatrizoate (Urografin®)
• Metrizoate (Triosil®)
Non-ionic aqueous solutions :
Iohexol (Omnipaque®)
• Iodized oil, e.g. Lipiodol® (iodized poppy
seed oil)
• Water-insoluble organic iodine compounds,
E.g. Pantopaque®.

Main indications
The main clinical indications for sialography
include:
• To determine the presence and/or position of calculi or
other blockages.
• To assess the extent of ductal and glandular destruction
secondary to an obstruction .
• To determine the extent of glandular break-down and as
a crude assessment of function in cases of dry mouth.

Contraindications:
The main contraindications include.
• Allergy to compounds containing Iodine although
Gadolinium may be used as an alternative.
• Periods of Acute infection/inflammation.
• when there is discharge of pus from the duct opening
• When clinical examination or routine radiographs have
shown a calculus close to the duct opening, as injection
of the contrast medium may push the calculus back
down the main duct where it may be inaccessible.

SIALOGRAPHIC TECHNIQUES:
• The control of infection measures .
• Wearing of eye protection glasses and a mask by
operators is recommended.
• The three main techniques available for introducing the
contrast medium into the ductal system, having
cannulated the relevant duct orifice, include:
• Simple injection .
• Hydrostatic
• Continuous infusion pressure-monitored.

Simple injection technique
• Oil-based or aqueous contrast medium is introduced
using gentle hand pressure until the patient experiences
tightness or discomfort in the gland, (about 1.0 ml for the
parotid gland, 0.8 ml for the submandibular gland).
Advantages:
• Simple Inexpensive.
Disadvantages:
• The arbitrary pressure which is applied may cause
damage to the gland .
• Relying on patient's responses may lead to
underfilling or overfilling of the gland.

Hydrostatic technique:
• Aqueous contrast media is allowed to flow freely
into the gland under the force of gravity until the patient
experiences fulness or discomfort.
Advantages:
• The controlled introduction of contrast medium is less
likely to cause damage or give an artefactual picture.
• Simple
• Inexpensive.

Disadvantages:
• Reliant on the patient's responses - Patients have to lie
down during the procedure, so they need to be
positioned in advance for the filling-phase radiographs.
Continuous infusion pressure-monitored technique:
Using aqueous contrast medium, a constant flow
rate is adopted and the ductal pressure monitored
throughout the procedure.

• Each of these techniques has its advantages, and with
experience, each produces satisfactory results.
• The technique employed is therefore dependent on the
Operator and the Facilities available.
• In addition, Sialography may also be performed using
advanced imaging modalities,
Ex: CT Sialography and MR Sialography .

Sialographic interpretation:
Essential requirements include:
• A systematic approach
• A detailed knowledge of the radiographic appearances of normal
salivary glands.
• A detailed knowledge of the pathological conditions affecting the
salivary glands.

Systematic approach:
A suggested systematic approach for viewing sialographs
General overview of entire film
1 Note the shadows cast by overlying normal anatomical
structures, particularly:
• The spine
• The hyoid bone
• The mandible
2 Assess the exposure factors
The salivary gland
3 Assess the degree of filling of the duct structure
4 Assess the main duct, noting particularly: The diameter of the duct ,the
course and direction of the duct .The presence and position of any defects or
strictures.
5 Assess the duct structure within the gland, noting particularly: The
branching and gradual tapering of the minor ducts towards the periphery of the
gland The overall pattern and shape of the ducts The degree of overall glandular
filling The presence and positioning of any filling defects
6 Assess the degree of emptying

Algorithm for diagnostic imaging of salivary
glands:
 Plain film radiography,
 Conventional sialography,
 Computed Tomography (CT),
 Magnetic Resonance Imaging (MRI),
 Scintigraphy
 Ultrasonography

Normal sialographic appearances of the parotid gland:
• The main duct is of even diameter (1-2 mm wide) and
should be filled completely and uniformly.
• The duct structure within the gland branches regularly
and tapers gradually towards the periphery of the gland,
the so-called tree in winter appearance

Pathological appearances:
Based on the suggested systematic approach to
sialographic assessment, the main pathological changes
can be divided into:
Ductal changes associated with:
• Calculi
• Sialodochitis (Salivary ductal inflammation)
Glandular changes associated with:
• Sialadenitis (Glandular Inflammation/
Infection)
• Sjogren's syndrome
• Intrinsic tumours.

• Sialographic appearances of sialodochitis
include:
Segmented Sacculation or dilatation and stricture of
the main duct, the so called sausage link appearance.
Associated calculi or ductal stenosis.

• Sialographic appearances of sialadenitis
include:
Dots or blobs of contrast medium within the gland, an
appearance known as sialectasis caused by the
inflammation of the glandular tissue producing saccular
dilatation of the acini .
• The main duct is usually normal

Sialographic appearances in Sjogren's syndrome:
• Widespread dots or blobs of contrast medium within the
gland, an appearance known as punctate sialedasis or
snowstorm .
• This is caused by a weakening of the epithelium lining
the intercalated ducts, allowing the escape of the
contrast medium out of the ducts.
• Considerable retention of the contrast medium during the
emptying phase
• The main duct is usually normal

The different stages of sialectasia in SS, as present on Lateral parotid sialograms
(A) Punctate sialectasia,
less than 1 mm in size;
(B) Globular Sialectasia, uniform of
shape and 1 to 2 mm in size;
(C) Cavitary sialectasia, irregular of
shape and more than 2 mm in size;

Intrinsic tumors

Diagrams showing an intercalated Ductule and Acinus.
A In a normal gland.
B In Sjogren's syndrome, the epithelium lining the
intercalated ductule becomes weakened allowing escape of
the contrast medium out of the duct so producing the dots
or blobs.
C In sialadenitis, the acinus becomes dilated allowing the
collection of contrast into a dot or blob.

Ba swallow test
One of the most commonly used contrast agents is Barium
sulfate.
Barium blocks the passage of x-rays, so barium-filled
organs stand out better on x-ray exams.
For an examination of the esophagus or stomach, patients
are asked to drink a mixture of barium sulfate and water,
sometimes with vanilla or fruit flavoring added.
This mixture usually is Thick and White.

Nasolabial cyst

A 42-year-old woman with a chief complaint of an
asymptomatic swelling of the right nasolabial region present
for 10 years.
On the occlusal radiographic examination a distortion of the
anterior lateral wall of nasal cavity was observed.

Aspiration of 3 ml of cystic fluid was performed with
a needle of 0.5 mm and a brown liquid was obtained.
Three millilitres of radiographic contrast medium (50%
sodium diatrizoat) was injected .
Occlusal and cephalometric radiographs were taken and a
3 cm radiopaque spherical image was observed in these
images

Contrast media in Arthrography:
• Arthrography is a technique in which an indirect
image of the disk is obtained by injecting a
radiopaque contrast agent into one or both
spaces under Fluoroscopic guidance.
• In the Head and neck region this technique is
employed in TMJ is known as “TMJ
Arthrography”.
• Pass in 1939 accomplished the first use of
arthrography in evaulating the TMJ

Indications:
• When information about disk position, function,
morphology, and the integrity of discal attachments
is required for treatment planning.
Contraindications:
• Allergy to contrast agent.
Disadvantages :
Invasiveness of the Technique.
Postoperative discomfort.

• Injection of contrast
medium into the
lower joint space.
• Information about
joint dynamics.
• Recommended for
patients with primary
functional
disturbance such as
clicking and
intermittent locking.
Single contrast technique Double contrast techniques
• Injection of Contrast
medium and Air into both
upper and lower joint
spaces.
• Information about the joint
morphological features.
• Recommended to know
the morphological
Alterations of the joint.

• Water-soluble contrast agents are preferred in
Arthrography because they provide enough
contrast to define Interior structures
• They also have advantage of being dissipated
quickly.
• Upper and lower joint compartments could be
passively filled with 1-2ml and 0.9ml respectively.

Contrast media in
angiography
• Angiography includes Arteriography and Phlebography.
• For Arteriography, ideally require a medium that gives
good contrast, possess low viscosity (for rapidity of
injection) and is Nontoxic.
Most commonly used CM are:
• Sodium and Methylglucamine diatrizoate
• Metrizoate & Iohexol.

• Gadodiamide and Super Paramagnetic iron oxide(SPIO)
can also be used.
• The normal external carotid carotid artery can be
opacified by 3-10ml of contrast medium.
• Low osmolarity and non-ionic contrast media are used
in phlebography or venography where it can be injected
by either direct puncture of the vein or indirectly by
injecting the medium into the arterial system and
imaging the venous return.

CAROTID ANGIOGRAM

Contrast Media in Computed Tomography(CT):
• CT images are analysed in terms of Normal versus
disturbed Anatomy.
• In CT the rationale for using contrast media is to obtain
a differential change in the attenuation values of normal
and pathological tissues, so that recognition of the
abnormality is facilitated.
• Lesions not obvious on simple scan can be revealed
and many others are enhanced by contrast medium
which depends on the pharmacokinetics of the contrsat
media

• Most widely used material is 30mg of Iodine for an
average built and scanned after 5-15 min later.
• CT of the salivary glands was introduced as a new
technique in 1978.
• On CT scan, Normal Parotid Gland appears more radio
dense than adjacent fat but less dense than surrounding
muscles because of its high fat content and high
concentration of saliva.
• Submandibular gland contains less fat so its density is
similar to the adjacent muscles.

Contrast agents for Magnetic Resonance
Imaging(MRI):
• MR contrast agents provide an alternative solution to
overcome some of the limitations of plain MR Imaging.
• Contrast agents alter the Tissue relaxation times and
can therefore be used to manipulate their Single
intensity.
• They are used to enhance soft tissue structures,
characterize the tissues non-invasively, portray
physiological process in vivo and reduce imaging time
easily.

ORAL CONTRAST AGENTS:
Positive contrast: T1 hypersignal
• Gadolinium chelates: Magnevist enteral®, Gadolite®
• Manganese chelates: Lumenhance®
• Ferric amonium citrate: Ferriseltz®
Negative contrast: T2 hyposignal
• SPIO: Lumirem®, Gastromark®
• Barium sulfate
• Blueberry

Contrast agents used in MRI are:
• Gadolinium based contrast agents:
a. Gadolinium-DPTA
b. Gadomer-17 SH L 643A
• Superparamagnetic iron oxide SH U 555C
• Ultrasmall Superparamagnetic iron oxide (USPIO).

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