Contrast imaging/ dental implant courses

CONTRAST IMAGING
www.indiandentalacademy.com
INDIAN DENTAL ACADEMY
Leader in continuing Dental
Education

Research and development has focussed on
manipulating and altering all three of the basic
requirements for image production
* The patient
* Image generating equipment (to find alternatives
to ionizing radiation)
* Image receptor and manipulating the image itself.
These imaging modalities have considerable over
lap, they are broadly classified according to
whether they have altered or changed,
The patient
- CONTRAST STUDIES
- RADIO ISOTOPE IMAGINGwww.indiandentalacademy.com

The image receptor(with or without image manipulation)
including
-COMPUTER TOMOGRAPHY
-DIGITAL IMAGING
The image generating equipment(to non-ionizing
radiation)& image receptor
-Ultrasound
-MRI

Investigation involving altering the patient-
CONTRAST STUDIES-These investigations use
contrast media,radiopaque substances that have
been devpd to alter artificially the density of
different part of the
Patient,so altering subject contrast-the difference
in the x-ray beam transmitted through different
parts of the patients tissue,thus altering the
patient,certain organs, structures and
tissues,invisible using conventional means, can be
seen.

Contrast studies and the tissues imaged ,include-
Sialography---salivary gland
Arthrography---Joints
Angiography---blood vessels
Lymphography---lymph nodes & vessels
Computed tomography--general enhancement
Magnetic resonance imaging-
Ultrasound

HISTORICAL BACKGROUND
Iodine(at wt-127)-satisfactory for general use as
intravascular radiological contrast medium(RCM).
Since mid 50’s organic carriers of I2 -based on fully
substituted benzoic acid molecule(6 atoms of c in
ring) with 3 atoms of I2 replacing H2 at c2,4,6
positn of benzene ring.
IV organic iodinated RCM- 1st introduced in clinical
practice(1928)by MOSES & SWICK, using-non-ionic
selectan neutral & ionic uroselectan,which
contained chemical -pyridone c contained 1 atom
of I2 per molecule,which had been synthesized at
BERLIN by BINZ & RATH.

On IV injection,the RCM are distributed rapidly by
capillary permeability into extra vascular,extra
cellular space(except in CNS),they do not enter the
interior of blood cells or tissue cells & are rapidly
excreted over 90% by glomerular filtration by
kidneys with in 12 hrs,this is highly desirable,since
they are used as imaging and not as therapeutic
agents.

IDEAL CONTRAST MEDIA-
1]Physiological properties should be similar to that of
saliva
2]Miscibility with saliva
3]Absence of local/systemic toxicity
4]Pharmacological inertness
5]Satisfactory opacification
6]Low surface tension & low viscosity to allow filling of
the fine components of the ductal system
7]Easy elimination,but durable enough to permit time for
satisfactory radiographs.
8]Residual contrast m should be absorbed by the salivary
gland and detoxified by the liver or excreted by kidneywww.indiandentalacademy.com

Types of contrast media
 Barium sulphate suspension- GIT
 Iodine based aqueous solution - IONIC MONOMERS
Iothalmate (eg conray)
Metrizoate (eg Isopaque)
Diatrizoate (eg Urografin)
 NON-IONIC MONOMERS
Iopamidol (eg Niopam)
Iohexol (eg Omnipaque)
Iopromide (eg Ultravist)


IONIC DIMERS
Ioxaglate (eg hexabrix)
 NON-IONIC DIMERS-
Iodine based oil solution-LIPIODOL
(Iodised poppy seed oil)
=>used in lymphography & sialography
MRI contrast agents (eg Gadolinium)

Avg physiological turnover of iodine is 0.0001g.The total iodine
content in the body (mainly in thyroid) is 0.01g.
IMPORTANT POINTS TO REMEMBER:-
Osmolality- dependent on the number (not the size)of the particles of
solute in solution.
Radio-opacity-dependent on iodine concentration of the solution
inturn depends on no of iodine atoms per molecule and of the
molecules in solution I.e iodine :particle ratio is imp criteria.
Non ionicity - a molecule that does not dissociate in solution is
required and also reduces minor-severe adv reactions.
Low osmolality- reduces the pain on intra arterial injection.
CHOICE OF CONTRAST MEDIA;
High VS Low Osmolar CM:- Non ionic LOCM are more popular than
HOCM b,coz it causes less nausea,v(on iv inj),less pain on peripheral
arterial injections ,less incidence of mild,moderate,severe adv
reactions.
Only dis adv is LOCM is very expensive than HOCM(10-20TIMES)www.indiandentalacademy.com

Types of contrast media
1] Water soluble
2]Oil based
water soluble eg- hypaque , hypaque M, renografin-60,
sinografin,isopque,trisol,dionosil
Hypaque and Renografin- WSM of choice
Fat soluble media- 2 types- Iodized oil
water insoluble organic iodine compounds
eg, -ethiodol (ethiodized poppy seed oil){ Fsm of choice}
-lipiodol(iodised poppy seed oil), iodiochloral(chloridized
peanut oil), pantopaque(mixture of isomers of ethyl
iodophenylundecylate) www.indiandentalacademy.com

COMPLICATIONS OF CONTRAST MEDIA
Mild- eg head ache, nausea,warmth(pain,flushing)sneezing and
constipation.
Moderate-eg vomiting, bronchospasm,urticaria,hypotension.
Severe-eg cardaic arrgythmias,cardiac
arrest,convulsions,anaphylactic shock and pulmonary oedema)
Fatal-
Patients at risk-elderly,very young children.
DELAYED ADVERSE REACTION:- serious adv reactn begin
during/within 15min of iv inj of RCM.some pt experience late reactions,onset
may be delayed for a few days,it is uncomfortable but not dangerous.MC in
females,delayed arm pain
(7%),delayed rash(5%),flu-like symptoms(headache,skin lesions,salivary
gland swelling- “iodide mumps”(9%) [due to iodism]
this reaction is idiosyncratic and not dose dependent.www.indiandentalacademy.com

Patients at risk-elderly,very young children.
-H/o allergy to contrast media
-Diabetics
-H/o cardiac failue,severe pulmonary disorders--ashtma,
renal failure
causes of complications-
due to allergy
chemotoxicity ,osmolality,anxiety
Prophylactic measures to minimise complications
use of low osmolality contrast agents
prophylactic steroids and antihistamines
Reassurance to reduce levels of anxiety
Ask about previous h/o iodine allergywww.indiandentalacademy.com

Contra-Indications
1]Patient with known sensitivity to iodine compounds.
2]If acute inflammation is present.
3]The administration & retention of the iodinated contrast
media may interfere with subsequent thyroid function
tests,hence TFT should be done prior to any test.

MAIN CONTRAST STUDIES USED IN THE
HEAD AND NECK REGION
Sialography
Arthrography
Computed tomography(to provide general enhancement)
Angiography
MRI
US

Sialography-It is retrograde injection of an iodinated
contrast agents into the ductal system of a salivary gland.
For many years,it was considered as “gold standard” for
evaluating the salivary component of auto-immune diseases
such as sjogren’s syndrome.
Historical background- 1st sialogram - Carpy in 1904,on
parotid gland using mercury as the contrast agent.
Arcelin(1913)-1 st sialogram,using bismuth,demonstrated a
stone in wharton’s duct.
After 1926, Carlsten et al popularised sialography by
demonstrating its efficiency.With advent modern imaging
modalities like CT,MRI,US,they have replaced sialography
in evaluation of parenchymal masses,but it is still ideal to
demonstrate status of ductal system.www.indiandentalacademy.com

ARMAMENTARIUM-
a] Rabinov sialography catheters
b]Lacrimal probes
c]Iodinated contrast agents
d]Dental cotton rolls
.

CATHETERS-many available-market,no-16 & 32 are the
most versatile & easiest to use.N0 16 is a non-tapered,end
hole catheter,measuring 0.016 inch in diameter(spc in
catheterising small stenotic ducts.No 32 catheter measures
0.032 inch in diameter & has a side hole,helps in large ducts)
Lacrimal probes-useful in identifying ductal orifices & in
probing distal ductal segments

Contrast agents used are either fat/water soluble
agents,containing appx 37% of iodine.
Most common fat soluble agent used is ethiodol.
Most common water soluble agent used is sinografin.

Preliminary films(SCOUT films)-plain film views of glands &
surrounding str are taken to assess for presence of radiodensities ,to
provide a radiographic background against which the sialogram will be
evaluated, to see any bony destruction should be looked for in cases of
neoplasm.
for eg parotid-AP VIEW,AP Puffed cheek view,
a lateral view, a lateral oblique view.
For submandibular gland views include AP view, A lateral oblique view,
SMV view.

Cannulation- Identification of the ductal orifice & placement of the metal
cannula in the distal duct.

Injection techniques- Sialography should be performed under direct
fluoroscopic observation b,coz
it permits the examiner to witness the different phases of study
to position the patient optimally for appropriate spot films
 it helps to terminate procedure, if any complication(extravasation )
occurs.
HYDROSTATIC INJECTION
DISTENTION TECHNIQUES
HAND INJECTIONS
PHASES OF SIALOGRAPHY
DUCTAL
ACINAR
EVACUATION

INDICATIONS FOR SIALOGRAPHY
1] to evaluate patients presenting with acute/chronic glandular
enlargement from the following- acute obstructive/chronic reccurent
sialdenitis,auto immune sialadenitis,sialosis.
2]to detect presence of calculus/foreign bodies(either RL/RO)
3]to determine the extent of destruction of the gland,secondary to
obstructing calculi/foreign bodies.This will aid in deciding whether a
total excision of the gland or a simple lithotomy should be performed.
4]to detect any fistulae,stricture/diverticulae present
5]to detect & diagnose any recurrent swellings & inflammatory
process present.
6]to demonstrate location of a tumor,its size,origin & whether the
radiograph suggest a benign/malignant lesion.
7]to detect any residual stone or tumor/retention cyst following
lithotomy/surgical procedures.
8]to evaluate ductal system following trauma to the gland/periglandular
region.
9]to evaluate mandibular lesion thought to be of salivary origin.
10]to evaluate submandibular masses/masses with in dense parotid
gland,especially in conjunction with the CT.

CONTRA-INDICATIONS FOR SIALOGRAPHY
1]Patient with known sensitivity to iodine compounds.
2]If acute inflammation of salivary system is present.
3]The administration & retention of the iodinated
contrast media may interfere with subsequent thyroid
function tests,hence TFT should be done prior to
sialography.

SYSTEMIC APPROACH FOR INTERPRETATION OF SIALOGRAPHS
General overview of the entire film-
1] Note the shadows -by overlying normal anatomical str-
spine,hyd bone ,mandible.
2] Assess the exposure factors
The Salivary Gland-
3] Assess the degree of filling of the duct str.
4] Assess the main duct-diameter of duct,course & direction
of the duct ,presence & position of any filling defects.
5]Assess the duct str within the gland-branching & gradual
tapering of the minor ducts towards the periphery of the
gland,overall pattern & shape of the ducts,degree of over all
glandular filling ,presence and position of any filling defects.
6] Assess the degree of emptying.www.indiandentalacademy.com

NORMAL SIALOGRAPHIC APPEARANCE
PAROTID GLAND- Main duct -even diameter(1-2mm wide) & should be
completely filled with uniformity.Duct str within the gland branches
regularly & tapers gradually towards the periphery of the gland- TREE
IN WINTER
SUBMANDIBULAR GLAND-Main duct -even diameter(3-4mm wide) &
shd be filled completely & uniformly.
Branching of duct is similar to parotid, but called as BUSH IN WINTER.

PATHOLOGICAL SIALOGRAPHIC APPEARANCE
Ductal changes -Calculi,sialodochitis(ductal inflammation/infection)
Glandular changes -Sialadenitis(glandular inflammation/infection),
sjogren’s syndrome,intrinsic tumors.
SIALOGRAPHIC APPEARANCE OF CALCULI -Filling defect(s) in the
main duct,ductal dilatation proximal to the calculus,the emptying film -
shows contrast m retained behind the stone.

SIALOGRAPHIC APPEARANCE OF
SIALODOCHITIS-
Segmented sacculation or dilatation & stricture of the
main duct-sausage link appearance.
Associated calculi or ductal stenosis.

SIALOGRAPHIC APPEARANCE OF SIALADENITIS-
Dots/blobs of contrast medium within the gland- Sialectasis- caused by inflammation
ot the glandular tissue producing saccular dilatation of the acini.main duct normal.
.

SIALOGRAPHIC APPEARANCE OF SJOGRENS SYNDROME-
Widespread dots or blobs of contrast medium within the gland-PUNCTATE
SIALECTASIS/ SNOWSTORM.

SIALOGRAPHIC APPEARANCE OF INTRINSIC TUMOURS
An area of underfilling within the gland,due to ductal compression by
the tumor.
Ductal displacement- ducts adjacent to the tumour -stretched around it-
BALL IN HAND appearance.Retention of contrast m in the displaced
ducts during the emptying phase.

INTERVENTIONAL SIALOGRAPHY
minimally invasive interventional procedures-BALOON CATHETERS- inflated
once positioned within a duct to produce dilatation of ductal stricutes.
DORMIA BASKET- Used to retrieve mobile ductal salivary stones.successful.no
need of surgery.
CT SIALOGRAPHY
sialography is performed in conjunction with CT-CT SIALOGRAM.
Earlier used to enhance the visualization of salivary masses on early CT
scanners.With advances in CT Scanners, this is reserved for dense parotid
glands is strongly suspected clinicaly but cannot be demonstrated on routine
non contrast enhanced CT studies.

TREATMENT OF CHRONIC SIALADENITS BY INTRADUCTAL PENCILLIN
OR SALINE (Jr OMF Surgery,2004,vol 62,pg 443-34)
it is simple,successful technq (1st given by QUINN & GRAHAM(1973)
-the orifice of the duct was dilated w a lacrimal probe & cannulated w
no.19 polyethlyene tubing for the submandibular gl & no 21 for
parotid.the solution consisted of 1 million IU of pencillinG IN 5Ml of
normal saline or plain NS & was instilled until the pt was aware of
discomfort or enlargemt of the gand was observed.Reflux of the solution
was prevented by pressure of the fingers of the free hand on the orifice
of the duct during the instillation & subsequently for 5-10 min depending
on the tolerance of the pt. vol of the soltn varied from 0.5--1.5mL for SM
gland,1.5--2mL for parotid.
-44 pt of chr sialadentis were treated w instilation of pencilin -
-2-19 instiltn (avg 7.1 ist)over periods of 1-36 wks(avg 6.8 wks)
18 pt of chr parotitis treated w instltn of pen --2-28 inst (avg 8.4 inst) over
periods of 1wk-2yr (avg 15.6wk). This improvd functional response to
sialography after the course of ductal instltn is due to loss of obstruction
caused by inflamtory oedema,esply in chr sialadentis.

ARTHROGRAPHY-It utilizes the injection of radioopaque contrast
material into one or both(u/l) joint compartments , to enhance the
contrast between the disc & these spaces. The shape & position of the
disc -inferred from the shapes of radioopacities above & below it.
Conventional arthrography & Double contrast arthrography
Used to evaluate soft tissue components of TMJ.
ADV- accuracy,visualization,dynamic funtional
assessment,morphologic evaluation of disc,simplicity,less expensive.
DIS ADV- Invasive, Substantial radiaiton dose is needed, less precise,
skill required, slight discomfort.
INDICATIONS-Long standing TMJ pain dysfunction,repeated jaw
locking,limited opening of unknown etiology,meniscal pathology such
as tears & perforations, to evaluate splint therapy.
CONTRAINDICATIONS- Allergy to local anaesthetics, iodine
containing products, bleeding disorders, acute infections.

TECHNIQUE-
Non ionic aqueous contrast medium(eg, iopamidol-Niopam,370) is
injected carefully into the lower joint space,using fluoroscopy to aid the
accurate positioning of needle.The primary record is obtained ideally
using video-recorded fluorography or cinefluorography which allows
imaging of the joint components as they move.
Diagnostic information- Dynamic information on the position of the joint
components & disc as they move in relation to one another,static
images of the joint components with the mouth closed and with the
mouth open.Any anterior or anteromedial displacement of the disc can
be observed.The integrity of the disc,I.e. the presence of any
perforations.

DOUBLE CONTRAST ARTHROGRAPHY
it utilizes iodine contrast media and gas contrast m. 1st given by
Bircher , for TMJ - Arnaudow first described .
Principle- coat the articulating surfaces with the iodinate contrast-
radioopaque, expand the joint compartments w gas contrst m-
radiolucent, mc used is room air.
EQUIPMENT& TECHNIQUE- A C- arm, with an x-ray tube and image
intensifier -used for cannulation of the joint spaces. Injection of
contrast m is done w patient in supine positn,C- arm is tilted abt 10-150
caudally-to project the TMJ free of base of the skull, then an oblique
lateral transcranial projection of tmj is obtained.

ANGIOGRAPHY-
It involves the introduction of aqueous iodine-based contrast media into
selected bld vessels.In h/n region- mc Carotid(common,internal or external)or
the vertebral arteries.
Procedure- introduce a catheter into a femoral artery followed by selective
cathetirization of the carotid/vertebral arteries,using fluoroscopic control.once
the catheter is sited correctly,the contrast medium is injected & radiographs of
the appropriate area taken.
INDICATION IN HEAD & NECK -
To show the vascular anatomy & feeder vessels associated w haemangiomas .
To show the vascular anatomy of arteriovenous malformations.
Investigation of suspected subarachnoid hemorrhage resulting from an
aneurysm in the circle of willis.
Investigation of transient ischaemic attacks possibly caused by emboli from
atheromatous plaques in the carotid arteries.

LYMPHANGIOGRAPHY- to visualize lymphatic system of the body.
Eg,in diseases like testicular tumors,filiariasis,congenital
lymphhoedema
PRINCIPLE-since lymph v are not visible on gross exmtn,methylene
blue dye is injected subcutaneously in dorsum of foot to make the
lymphatics prominent.Thereafter 3-5 ml of ultra fluid lipoidal(contrast
media) is injected in the lymph vessel.skiagrams of the desired region
are then obtained & lymphatics vessels are studied.

CONTRAST AGENTS IN COMPUTER TOMOGRAPHYCONTRAST AGENTS IN COMPUTER TOMOGRAPHY
GODFREY HOUNSEFIELD-1972,PRINCIPLES OF CTGODFREY HOUNSEFIELD-1972,PRINCIPLES OF CT
with advent of new scanners- intravascular contrast agent --contrastwith advent of new scanners- intravascular contrast agent --contrast
enhancements.enhancements.
-- IONIC/NON-IONICIONIC/NON-IONIC
-MONOMERIC/DIMERIC,-MONOMERIC/DIMERIC,

REASONS FOR ARTIFICIAL CONTRAST ENHANCEMENTREASONS FOR ARTIFICIAL CONTRAST ENHANCEMENT
1)To label blood vessels with an agent & to help differentiate these1)To label blood vessels with an agent & to help differentiate these
vessels from other soft tissues.vessels from other soft tissues.
2)They may be used as tracers in physiological & functional2)They may be used as tracers in physiological & functional
measurementsmeasurements
3)To characterize lesions by tissue enhancement - may indicate the3)To characterize lesions by tissue enhancement - may indicate the
pathology type.pathology type.
4)The commonest & most imp reason-to improve lesion conspicuity &4)The commonest & most imp reason-to improve lesion conspicuity &
thereby increase diagnostic yield.thereby increase diagnostic yield.

GENERAL PRINICIPLEGENERAL PRINICIPLE
CT scanner use x-ray to produce sectional or slice images,but film isCT scanner use x-ray to produce sectional or slice images,but film is
replaced by sensitve crystal of gas detectors.these detectors measure thereplaced by sensitve crystal of gas detectors.these detectors measure the
intensity of the x-ray beam emerging form the patient and convert this tointensity of the x-ray beam emerging form the patient and convert this to
digital data which are stored and can be manipulated by a computer.thisdigital data which are stored and can be manipulated by a computer.this
numerical information is converted into a grey scale representingnumerical information is converted into a grey scale representing
different tissue densities=>visual imagedifferent tissue densities=>visual image
MODE OF ACTION OF C AMODE OF ACTION OF C A
They increase x-ray absorption in the location in which they are found toThey increase x-ray absorption in the location in which they are found to
an extent that is proportional to the concentration of Iodine.The efficiencyan extent that is proportional to the concentration of Iodine.The efficiency
of phenomenon might be optimised by modification of x-ray tube voltageof phenomenon might be optimised by modification of x-ray tube voltage
& filtration & that elements other than iodine could certainly form the& filtration & that elements other than iodine could certainly form the
basis of effective contrast agents in CT, if designated for the right energybasis of effective contrast agents in CT, if designated for the right energy
spectrum.spectrum.

MRI :-MRI :-
PRINCIPLEPRINCIPLE
A Method of obtaining images of body in thin slices,it measures theA Method of obtaining images of body in thin slices,it measures the
characteristics of hydrogen nuclei of water and nuclei with similarcharacteristics of hydrogen nuclei of water and nuclei with similar
chemical shifts, modified by chemical environment across the slice. MRIchemical shifts, modified by chemical environment across the slice. MRI
give spatial distribution of the intensity of water proton signal in thegive spatial distribution of the intensity of water proton signal in the
volume of the body, this signal intensity depends on the amt of water involume of the body, this signal intensity depends on the amt of water in
the given place and on the magnetic relaxation times T1 & T2 which inthe given place and on the magnetic relaxation times T1 & T2 which in
turn are influenced by a range of factors.turn are influenced by a range of factors.

CONTRAST AGENTS IN MRICONTRAST AGENTS IN MRI
1)increases relaxation rates in regions it is present, & causes1)increases relaxation rates in regions it is present, & causes
enhancement.enhancement.
Eg.Gadolinium-DTPAEg.Gadolinium-DTPA
(diethylenetriaminepente acetic acid)(diethylenetriaminepente acetic acid)
2)increases field inhomogeneity .eg,superparamagnetic particle agents.2)increases field inhomogeneity .eg,superparamagnetic particle agents.
Clinical applications-c e with Gd-chelates are significant in cases of smallClinical applications-c e with Gd-chelates are significant in cases of small
neuromas, mengiomas,when diagnosis is not certain in pre-enhancementneuromas, mengiomas,when diagnosis is not certain in pre-enhancement
images.They are also helpful in tumour recurrence,where anatomy isimages.They are also helpful in tumour recurrence,where anatomy is
distorted by prev surgery.distorted by prev surgery.
General agreement MRI is more sensitive than CTGeneral agreement MRI is more sensitive than CT
To distinguish between “active” & “inactive”lesions in multiple sclerosisTo distinguish between “active” & “inactive”lesions in multiple sclerosis

Methods of image enhancementMethods of image enhancement
CT &MRI-based on image generation by computer=>choice ofCT &MRI-based on image generation by computer=>choice of
computational method become imp for obtaining quality images.signalcomputational method become imp for obtaining quality images.signal
intensity in mri depends not only on the amt of water in a given place,butintensity in mri depends not only on the amt of water in a given place,but
also on the magnetic relaxation times T1 &T2=>more oppurtunity toalso on the magnetic relaxation times T1 &T2=>more oppurtunity to
change the picture.change the picture.
overall quality of image =>depends on hardware design,esply onoverall quality of image =>depends on hardware design,esply on
transmitting and receiving coil design,pulse sequence employed to taketransmitting and receiving coil design,pulse sequence employed to take
particular picture.for ex-blood- appears black,gray,white-depending onparticular picture.for ex-blood- appears black,gray,white-depending on
pulse sequence,velocity of flow & orientation of flow of the imagingpulse sequence,velocity of flow & orientation of flow of the imaging
plane.plane.
Since it is difficult to influence the proton density in tissue,changes ofSince it is difficult to influence the proton density in tissue,changes of
image of diffnt tissue is done by changing the M relaxation times T1 & T2image of diffnt tissue is done by changing the M relaxation times T1 & T2
of the protons in tissue-contained water.of the protons in tissue-contained water.

Contrast agents in MRIContrast agents in MRI
1]paramagnetic contrast agents- gen considerations-T1 & T2 may be1]paramagnetic contrast agents- gen considerations-T1 & T2 may be
shortened ,results in increase in signal intensity(T1),& broader lines withshortened ,results in increase in signal intensity(T1),& broader lines with
decreased intensity(T2).net result is at low conctn, an increase in contrastdecreased intensity(T2).net result is at low conctn, an increase in contrast
agent provides an increase in signal intensity due to effect on T1 until optagent provides an increase in signal intensity due to effect on T1 until opt
conctn is reached. Hence in clinical practice, a less than opt contrastconctn is reached. Hence in clinical practice, a less than opt contrast
effect is produced & also negative contrast effect.effect is produced & also negative contrast effect.
PM Species-unpaired electrons---simple sub(molecular oxygen),stablePM Species-unpaired electrons---simple sub(molecular oxygen),stable
radical(nitroxide radical) or metal ion(many transition metal ions).radical(nitroxide radical) or metal ion(many transition metal ions).
Dis adv-in their native form- toxicity. Hence research is on stable PMDis adv-in their native form- toxicity. Hence research is on stable PM
complexes,latest is called superparamagnetic iron oxide(SPIO)basedcomplexes,latest is called superparamagnetic iron oxide(SPIO)based
colloids(microcrystalline magnetic cores coated with dextranes orcolloids(microcrystalline magnetic cores coated with dextranes or
siloxanes)siloxanes)

2]Gadolinium complexes-high no of unpaired electrons-seven. Free Gd3+2]Gadolinium complexes-high no of unpaired electrons-seven. Free Gd3+
are toxic,but complexes are stable-less toxic.Only FDA approved is Gd-are toxic,but complexes are stable-less toxic.Only FDA approved is Gd-
DTPA(diethylenetriaminepentaacetic acid){marketed as magnevist} .DTPA(diethylenetriaminepentaacetic acid){marketed as magnevist} .
3]Metalloporphyrins of Mn & Fe have favorable properties as MRI3]Metalloporphyrins of Mn & Fe have favorable properties as MRI
Contrast agent for tumor detection.Contrast agent for tumor detection.
4]Native proteins acting as contrast agents4]Native proteins acting as contrast agents
Heme containing proteins may act as “natural” contrast agentsHeme containing proteins may act as “natural” contrast agents..
ex haematomas are easily identified by MRI.ex haematomas are easily identified by MRI.

ULTRASOUNDULTRASOUND
A high frequency(3.5-10Mhz) pulsed US beam is directed intoA high frequency(3.5-10Mhz) pulsed US beam is directed into
body from a transducer placed in contact w the skin.usbody from a transducer placed in contact w the skin.us
travels tho the body,some are reflected back by tissuetravels tho the body,some are reflected back by tissue
interfaces --ECHOES,c are picked up by the same transducerinterfaces --ECHOES,c are picked up by the same transducer
& converted into electrical signal & then into a black,white && converted into electrical signal & then into a black,white &
grey visual echo picture image c is displayed on a TV screen.grey visual echo picture image c is displayed on a TV screen.
INDICATIONS IN HEAD & NECK;INDICATIONS IN HEAD & NECK;
11] evaluation of swelling of neck-throid,cerv lymp node,maj] evaluation of swelling of neck-throid,cerv lymp node,maj
sal glandsal gland
(investigation of choice for detecting solid & cystic soft t(investigation of choice for detecting solid & cystic soft t
masses)masses)
2]detection of sal gland & ductal calculi2]detection of sal gland & ductal calculi
3]therapeutically,in conjunction w newly devp3]therapeutically,in conjunction w newly devp
sialolithotripter,to break up sal calculi into appx 2mmsialolithotripter,to break up sal calculi into appx 2mm
fragments c will pass out of ductal sy(avoids surgeryfragments c will pass out of ductal sy(avoids surgery))
4]us guided FNA biopsy.4]us guided FNA biopsy.www.indiandentalacademy.com

US CONTRAST AGENTSUS CONTRAST AGENTS::1ST introduced by1ST introduced by GRAMIAK &GRAMIAK &
SHAH(1968)-SHAH(1968)-to image chambers of heart & its bld vessto image chambers of heart & its bld vess
-They should be safe,stable in the vascular sy,to survive-They should be safe,stable in the vascular sy,to survive
pulmonary capillary circulation & be capable of modifying thepulmonary capillary circulation & be capable of modifying the
acoustic pr of the tissues of interest.acoustic pr of the tissues of interest.
-CA used are-CA used are microbubbles(microbubbles(2-8 meu in diamtr),it contains air2-8 meu in diamtr),it contains air
or perfluorocarbon gas c has prolonged longevity due to itsor perfluorocarbon gas c has prolonged longevity due to its
lower solubility.lower solubility.
-Stability to microbubble is provide in the form of shell,made-Stability to microbubble is provide in the form of shell,made
up of denatured albumin,lipid or surfactant layers or polyup of denatured albumin,lipid or surfactant layers or poly
butyl cynoacrylate.butyl cynoacrylate.
-CA improve the quality of sonography either-CA improve the quality of sonography either
1) by decreasing the reflectivity of the undesired1) by decreasing the reflectivity of the undesired
interfaces(orally)interfaces(orally)
2) by increasing the back scatter echoes from the desired2) by increasing the back scatter echoes from the desired
region.(intra vascularly). eg microbubblesregion.(intra vascularly). eg microbubbles

REFERENCES:-REFERENCES:-
1.TEXT BOOK OF MAXILLOFACIAL REGION- DELBALSO1.TEXT BOOK OF MAXILLOFACIAL REGION- DELBALSO
2.ORAL MEDICINE,DIAGNOSIS,TREATMENT-BURKITT2.ORAL MEDICINE,DIAGNOSIS,TREATMENT-BURKITT
3.FUNDAMENTALS OF ORAL MEDICINE-NAGESH &3.FUNDAMENTALS OF ORAL MEDICINE-NAGESH &
BAILOORBAILOOR
4.ESSENTIALS OF DENTAL RADIOGRAPH & RADIOLOGY-4.ESSENTIALS OF DENTAL RADIOGRAPH & RADIOLOGY-
ERIC WHAITESERIC WHAITES
5.TEXT BOOK OF CONTRAST MEDIA- PETER CAWSON5.TEXT BOOK OF CONTRAST MEDIA- PETER CAWSON
6.IMAGES- E NET6.IMAGES- E NET
7.JOURNAL OF ORAL MAXILLOFACIAL SURGERY,2004,PG7.JOURNAL OF ORAL MAXILLOFACIAL SURGERY,2004,PG
431-34,VOL-62431-34,VOL-62

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