Ultra sonography indications in maxillofacial region /prosthodontic courses

ULTRASONOGRAPHY
TYPES & INDICATIONS IN MAXILLOFACIAL
REGION
INDIAN DENTAL ACADEMY
Leader in continuing Dental
Education
www.indiandentalacademy.com

contents
• Introduction
• Characteristics of sounds
• Display modes
• Recent advances in display modes
• Indications of usg in maxillofacial region
• Advantages
• Disadvantages
• Recent advances

INRODUCTION
• Ultrasound is an imaging modality
that utilizes high-frequency sound
waves to produce cross-sectional
images of the body

SOUND
• Sound is result of mechanical energy transmitted
through the medium as a pressure wave
• In resting state, pressure is uniform through out medium
• Physical displacement of materials cause transmission of
sound
• The sound wave produced has areas of high pressure (or
high density) and low pressure (or low density)

• The high-pressure areas (compression) are where
the sound waves are compressed together
• The low-pressure areas (rarefaction) are where
the sound waves are spaced apart

• The distance between corresponding points on the
time pressure curve is defined as the wavelength (λ),
• Time (T) to complete a single cycle is called the
period.
• The number of complete cycles in a unit of time is
the frequency (f ) of the sound.
• Frequency and period are
inversely related.
• f = 1/T

• The unit of acoustic frequency is the hertz (Hz)
• 1 Hz = 1 cycle /second.
• Audible sound frequency: 15 to 20,000cycles /sec
• US has a frequency greater than 20,000cycles/sec
• High frequencies are expressed in kHz/ MHz
• 1 kHz = 1000 Hz
• 1 MHz = 1,000,000 Hz (or)1 million cycles / second
• Diagnostic US – 2 TO 20 MHz

Display
modes
A
M
B
DOPPLER

A-mode (amplitude)
• Used to measure distance by displaying the
amplitude of the wave versus time (ie, depth)
for the return of that pulse.
• Echoes are displayed as spikes projecting from base
line.

Measured spectrum is a graph of amplitude versus
time. The time for a pulse to come back is
proportional to the distance.

• This mode allows for precise measurements, it was
used in ophthalmology for ocular measurements.
• HELPS IN RECORDING POSITION & STRENGTH OF
REFLECTING SURFACE
• LIMITATION : presents echo data from a single beam.

M-MODE & TM-MODE
• Detects motion of structures- cardiac valves and of
cardiac chambers , vessels.
• Echoes are displayed as
dots of varying intensity.
• It displays echo amplitude &
Shows position of moving
reflectors

M mode
• M-Mode does not have Time factor
• TM-Mode has Time factor
• M – mode US – functional Assesment of striated
muscles

Brightness mode(B mode)
 Echo signals as – Line of dots.
 Intensity of dot gives relative size of echo
 It provides depth of
information and variations
in direction of beam

GRAY SCALE IMAGING
• Displays the variation of Amplitudes of echoes arising
from tissues as varying shades of gray on monitor
Real time imaging
• The images change with each movement of the
transducer or if any part of the body is moving
• The movement is shown on the monitor in real time as
it occurs

Colour doppler imaging

• Doppler effect is a change in the perceived
frequency of sound emitted by a moving source
Us beam with a
frequency hits a
stationary
reflector
Echoes will be of
same frequency
as transmitted
Us beam hits a
moving reflector
( towards
transducer)
increased in
frequency
Decrease in
frequency
hits a moving
reflector
( away from
transducer)

Doppler equation

Types of doppler
• Continuous – rare – only in cardiac scanners
• Pulse/ Spectral ( duplex)
• triplex – colour + spectral
• Power doppler
Intra Oral doppler
• Indirect – intracavitary transducer covered
with gloves filled with water
• Direct oral – small specialised probe

Colour doppler
• Blood vessel is located by B- mode ultrasound imaging
and then the blood flow is measured by colour doppler
• Computer overlays a colour box
• The operator positions a box on the image, and colour is
superimposed wherever the scanner detects a moving
structure, usually blood
• velocities are distinguished by different colours

Spectral doppler

Power doppler :
• Technique that uses amplitude of doppler signal to
detect moving reflectors
• It is independent of velocity , direction of flow &
Angle of insonation
• Highly sensitive for low velocity flow lesions
• Grading stenosis

ADVANTAGES
• Color Doppler depicts - anatomic view and identifies the
presence, quantity, & type of vascularization
• Mean velocity and direction of blood flow in ROI
• To identify feeding and draining vessels
• spectral curve analysis of a blood vessel determines the
arterial or venous nature of the flow, as well as its
velocity (cm/s)
• Help in the Dd of vascular & nonvascular nodular lesions
in the oral cavity

Recent Advances
• DYNAMIC MUSCLE US :
• US tech with improved spatial resolution, frame rate (
15/sec)
• Helps to detect smaller movements of muscle
• Fasiculations - short jerky movements
• Fibrillations – small, irregular oscillatory movements

Panoramic imaging / extended field
of view
• Static image was produced by moving a 1-D probe
across the examination area.
• Extended view is created by sweeping the probe in
the lateral direction over a region of interest in
freehand.

• 3D : reconstructed from multiple
2D/1D images
• 4D : If a 3-D volume is recorded over time and if the
frame rate is high enough to cover a single cardiac
cycle, this technique is called 4-D ultrasound.
• Results in live action images

• US ELASTOGRAPHY:
• Gives info about consistency of structures ( soft
/firm)
Red – increased stifness, purple – decreased
stifness

Applications of
USG & doppler
in maxillofacial
region

• sonographic images are identified in terms of echoes
• A mass is hypoechoic- intensity lower than that of the
adjacent tissue
• Hyperechoic - masses of higher intensity ( bright)
• Isoechoic - masses with intensity similar to the
adjacent tissue.
• Anechoic – no internal echoes, appears darker
• A calcified mass - hyperechoic
• clear fluid or blood – anechoic

• Homogeneous - even echo pattern or reflections that
are relative and uniform in composition
• Heterogeneous - to an uneven echo pattern or
reflections of varying echo densitities.
• If a mass lesion contains hyperechoic and hypoechoic
areas, it is described as a heterogeneous mass

• Peri apical lesions – abscess, cyst, granuloma
• Soft tissue lesions – fibroma, pyogenic granuloma, space
infections, Peritonsillar abscess
• Osmf
• Salivary : Mucocele , ranula, sialadenitis, sialoliths, tumors
• Maxillofacial AV anomalies
• IO jaw lesions
• Assesing nature of lymphnodes
• Muscles of mastication & other facial muscles
• TMJ ?

• Prognostic denture failure
• Viability of mucocutaneous flap
• Guiding FNAC

• Ultrasonography has been used by a few researchers
( Shawker 1984; Vinka – puhakka (1989) to examine
soft tissues surrounding oral cavity
• Wilson IR ( An intro to USG in oral surgery. Oral surg
oral med oral pathol.1985;59: 236 – 241) HR USG to
examine facial tissues before & after surgical removal
of impacted 3rd molar
• Info concerning site & dimensions of post surgical
edema & hematoma can be obtained

Periapical abscess , space infection : poorly defined,
hypoechoic
Periapical granuloma:
• Poorly defined lesion
• Internal echoes – hyper/ hypoechoic
• Rich vascularity

• Simple cyst : anechoic to hypoechoic
( as it is a fluid filled cavity)
• Smooth walled with acoustic enhancement
• No vascularity in colour doppler

• Gundappa M “Comparison of ultrasound, digital and
conventional radiography in differentiating periapical lesions”.
Dentomaxillofacial Radiology (2006) 35, 326–333
• US imaging is possible through thinned or perforated
cortical bone.
• It underestimates the dimensions of the lesions, but can
provide accurate information on the pathological nature
of periapical disease
• They confirmed US as a reliable tech for differentiating
peri apical cysts & granulomas

• US provides accurate info on pathological nature of
lesions, inflammatory process, capsular thickness of
lesion.
• It also differentiates b/n simple & complex cyst
• Nature of content differentiation into solid/ semisolid
cyst

• Tikku AP et.al evaluated “Use of US & CD imaging
and radiography to monitor periapical healing after
endodontic surgery”Journal of Oral Science.2010;
52:411-416)
• USG in combo CD yields considerable info on nature
of bone healing & vascularity.
• Detecting changes in the healing of hard tissue at
the surgical site by this tech was stat. sig when
compared to conventional imagimg. (P < 0.004).

OSMF
• Normal mucosa - the connective tissue was loosely
woven - only low echogenicity was induced
• Fibrotic bands – increase no.of echoes – brighter
• Manjunath K “(Evaluation of oral submucous fibrosis using
ultrasonographic technique: A new diagnostic tool. Indian
Journal of Dental Research. 2011)”
• USG – delineates normal mucosa with uniform fine
mottled appearance with interspersed hypoechoic
areas.

• osmf pts USG – no, length, thickness of fibrotic
bands
• CD, Spectral doppler – decreased vascularity & PSV
in lesional areas.
• (normal pts venous flow – continued pattern with
avg. PSV – 1-2 cm/sec, arterial flow – pulsatile
pattern . PSV – 3- 9 cm/sec)

• Thapasum AF (Gray-scale ultrasonographic imaging of
the buccal mucosa in various stages of osmf. Oral
radiol. 2014)
• Correlated these findings with clinical, hp
• The results – stage progresses – statistically significant
increase in echogenecity ( corresponding to fibrotic
component)

Salivary gland
Indications :
• Acute infl. Conditions – to diff obstructive & non obstructive
sialadenitis
• Abscess, I& D – US guidance
• Cystic lesions , Mucocele, ranula
• Salivary gland tumors – benign & malignant
• Sialoliths – intraductal/ glandular
• Ductal dilatation/ inflammatory changes
• Multi locular lesions – sarcoidosis, lymphoma, metastasis,
cystlymphadenoma
• Pseudotumorous lesions – MMH, TB, sarcoidosis, lymphoepithelial
lesions www.indiandentalacademy.com

Sonographic anatomy :
• All salivary glands are homogeneous echogenic
glandular organs.
Parotid : homogeneous & echogenicity is comparable to
that of the thyroid gland.
• Deep part of parotid – not seen ( ramus)
• retro mandibular vein can be visualised
• Intra glandular ducts are rarely visualised
• Stensons duct visualised ( when it is dilated)

Parotid : superficial
lobe, deeplobe, duct,
masseter, ramus

• Sub mandibular gland : oblique section – triangular
• On a typical oblique section of gland , tonsils are
visualized as hypoechogenic areas cranio-posterior to
the submandibular glands.
• The main duct originates from the deep portion of
the gland and runs in an ascending way in fom
• The main duct can be differentiated from the lingual
vessels by color Doppler.

• Inflammatory diseases :
• Acute sialadenitis :
• Sonographically, the glands are enlarged with a more
rounded shape, with a convex lateral surface and a
hypoechoic structure
• ColorDoppler – hyperemia
• 50% cases , sialolith leads to sialadenitis, sonography
helps in excluding obstruction)
• Helps in identifying liquefaction
• In case of abscess – puncturing US guidancewww.indiandentalacademy.com

• Chronic sialadenitis :
• Sonographic changes are less prominent than acute
disease
• Ductal ectasia can be seen
• Sialography is superior to sonography in visualization
of ductal chronic inflammatory obstructions
• Post Radiation : gland is inhomogeneous, hypoechogenic
• chronic fibrotic form
• Diminished Vascularizationof the gland is diminished

• In children chronic recurrent cystic sialadenitis is a
typical form of chronic inflammation
• Multiple hypoechoic, cystoid areas in the parotid
glands are visualized
• These are caused by peripheral ductal ectasias and
chronic lymphatic infiltrations

• Sjogrens syndrome : all major salivary glands are
involved
• Acute stage : glands are in homogenous due to
inflammation . Hypervascularisation seen
• Enlarged, hypoechoic transformations are seen
• Long standing : glands are usually small, hypoechoic
• Glands are difficult to delineate.
• Fibrotic changes, diminished vascularity
(If hypoechogenic lesions > 2cms – biopsy)

Sjogrens syndrome
Multiple rounded, hypoechoic areas with
relatively normal parenchyme

Sialoliths :
• Calculi have a typical appearance - bright curvilinear
echo complexes with posterior shadowing
Calculi in distal part of
left sub mandibular
gland (8mm)
Accuracy of US in detecting
calculi – 90%
Helps in differentiating calculi
from calcified nodes,
phleboliths in veins

Salivary gland tumors :
Pleomorphic adenoma: tumor is well circumscribed
usually shows a homogeneous hypoechogenicity
A sharp, lobulated margin is regarded as typical

• Warthins tumor/ cystadenolymphoma :
• Warthin’s tumors are sharply bordered masses.
• On sonograms the lesion is usually more inhomogeneous
than the pleomorphic adenoma
• Hypoechoic with Multiple cystic lesions

• Muco epidermoid carcinoma: low grade :< 2 cm
diameter - homogeneous structure with smooth
borders
• Incorrectly regarded as benign lesions by imaging
• High grade : larger lesions, irregular borders and a
typical heterogeneous echo pattern. Frequently
irregular necrosis is found.
• Infiltrations to base of skull, parapharyngeal.s,
mandible – not detected

• In malignant tumors , color Doppler usually present
a higher degree of vascularization compared with
the normal parenchyma or with benign tumors
• High systolic values & abnormal pattern of tumors
vessels are suspicious for malignancy even when
gray-scale imaging suggests a benign lesion

Limitations of sonography in salivary gland
tumors
• Deeply situated tumors
• Some tumors cannot be delineate completely by
sonography
• extremely sensitive , but specificity – low
• Difficult to differentiate tumors from inflammatory
lesions.
“Gritzmann G. sonography of salivary glands. Eur radiol. 2003.”

Maxillo Facial Vascular Anomalies
Hemangiomas
• usually poorly defined solid masses
• show different echogenicity & vascularization – acc
to stage
• Pulse Doppler indicates peak systolic flow of up to 90
cm/s.
• The diastolic flow is pronounced with spectral
broadening and a low resistive index (RI: 0.4–0.7)

Low flow
VENOUS VM:
• hypoechoic, heterogeneous appearance
• with multiple anechoic sinusoidal spaces
• Usually characterized by compressible ducts by the US probe
• Venous flow on spectral analysis.
• Phleboliths may be present within the lesions.
• hyperechoic foci with posterior acoustic shadowing

VENOUS
MALFORMATION

• Lymphatic malformations :
• Macrocystic - large, anechoic cavity separated by
septa at US
• Microcystic - consists of multiple microscopic
cavities
• appear hyperechoic.
• Usually both are avascular, except for the septa,
• A mixed type of vascular flow both venous and
arterial sometimes may be depicted

High flow
Arterial / AV malformations :
• A mass composed entirely of vascular spaces with
aberrant arterial and venous vessels within the
mass.

CAROTID DOPPLER
• Carotid arteries can become narrowed due to
atherosclerosis (furring up) or other causes, and this
can lead to transient ischemic attack (mini-stroke) or
stroke.
• The carotid doppler test can help to determine stroke
risk and the need for preventive measures

Muscles of mastication
• Wilson IR (1985) HR USG - examine masseter muscle
• Normal masseter – relatively smooth internal texture of
moderate echogenicity
• Muscle is clearly demarcated from more superficial
tissues & is seen to abut directly against mandibular
ramus.
• US is capable of providing information regarding muscle
pathologies by depicting structural alterations

• Healthy masseter muscles have a heterogeneous
speckled appearance in cross-section on US scan
because of the irregular connective tissue bundles that
randomly permeate their structure (Kiliaridis et al.
1995).
• Hyperechoic bands - internal fascia, are referred to as
septa (Bakke et al. 1992).
• These bands diminish or disappear with inflammation;
hence, this is an important structural index of
masseteric infection

• Temporal muscle :
• Thin hypoechogenic band lying adjacent to the
medial relations of the temporal fossa
• The bony landmark is identified as a hyperdense line

• MP , LP – not superficial muscles
• Other muscles of the head and neck :
• Digastrics
• Sternocleidomastoid
• Trapezius
• lip muscle
• “Serra MD. The use of ultrasound in the investigation of
the muscles of mastication. Ultrasound in Medicine and
Biology. 2008;34:1875-1885”

• Accurate and reliable imaging technique for
measuring the thickness and cross sectional area of
the masticatory muscles , facial & neck muscles in
vivo
• Precision analysis of muscle shape
• CD USG - demonstrating the arteries in and around
the muscle
• Evaluate pathological changes in the muscles and
arteries

TMJ
• DISK DISPLACEMENTS
• OSTEOARTHROSIS
• JOINT EFFUSION

Lymphnodes
• Normal lymphnodes are difficult to detect because of
their high echogenicity, which is similar to that of the
surrounding fatty tissue.
• In acute, nonspecific lymphadenitis the lymphnodes
are painful and markedly enlarged.
• display a hypoechoic area.
• The hilus of the lymphnode is not always apparent.

 Cervical lymphnode metastases in H&N - SCC (80%)
 US findings: enlargement with a round to spherical
shape, hypoechogenic, in homogenously echogenic,
with loss of hilar definition.
 Common findings of metastases from SCC are
extranodal spread and central necrosis together with
liquid areas in the lymphnode.
 INCREASED VASCULARITY

 The round to spherical shape of the nodes is the
most important criteria in the diagnosis of metastatic
lymphnode disease.

• Size, Shape
• Cortical thickness, CAPSULAR THICKNESS
• Loss of Hilar echogenicity,
• Hilar displacement
• Echogenicity of node
• Necrosis
• Extracapsular spread
• Color flow
• Number
• Calcification

• SIZE: short axis > 1cm
• size alone should not be considered
• Shape : Benign nodes are elongated
and fusiform in shape
• Malignant nodes have more transverse diameter
(more rounded in shape
• Cortical thickness – uniform in
benign node
• Increased in malignancy

hilum
• A normal benign lymphnode is an elliptical structure
with an outer hypoechoic cortex and a central
echogenic hilus - a sign of benignity.
Hilar
compression /
displacement is
a sign of
malignancy

hilum
• Diffuse hypoechogenicity of the nodes – characteristic
feature of lymphomas
• If a node has fluid like appearance i.e uniformly hypo-
echoic with acoustic enhancement (pseudo cystic
appearance)

 Presence of necrosis in
a node is strong sign of
malignancy

 Extracpsular spread
can be seen clearly in
the ultrasound.

Malignant nodes shows
features like
1. Displacement of vessels
2. Aberrant vessels
3. Focal absence of
perfusion
4. Subscapular vessels
5. More peripheral than
central vascularity

 Presence of cluster of
nodes in a draining
region from a primary
tumor is regarded as a
sign of malignancy

 Presence of punctate
areas of calcifications in
a node has a possibility
of metastases from
papillary carcinoma of
thyroid
 Bright echogenic flecks
can be seen in
metastatic nodes

Dental scanning
• Dental scanning. Most solids, including enamel and
dentin, can be penetrated by ultrasound, and it is
possible to detect caries and cracks
• Due to the irregular tooth anatomy, some errors
were evident in the US images , as US hits sharp or
undulated surfaces, it is usually distorted upon
reflection and transmission leading to errors

INTERVENTIONAL USG
US GUIDED FNAC
• Used for abscess, salivary gland lesions, lymphnodes
• The usually used outer diameter of the needle is 1.2
mm.
• Can be performed statically / real time
• Advantage : With US guidance it is possible to monitor
the pass of the needle in real time.
• Avoid puncturing of necrotic areas
• laceration of the great cervical vessels

ADVANTAGES
• For soft-tissue imaging, ultrasound is superior to
conventional radiographs
• Best modality for near field imaging
• US provides information about size, localization,
echogenicity, margins and tendency of the lesion to
invade the surrounding structure
• It can also provide a clearer definition and spatial
resolution of the cutaneous, muscular, and mucosal
layers, using its HR sonographic equipment

• Relatively inexpensive
• Non invasive, non ionising radiation is used
• Easily reproducible
• Short scan time ( compared to MRI)
• Equipment can be easily handled & transported
• Children & mentally challenged

BIO EFFECTS
• There are no confirmed biological effects on
patients or instrument operators caused by
exposures from present diagnostic ultrasound
“American Institute of ultrasound in Medicine medical
ultrasound safety”. American Institute of Ultrasound in
Medicine; 2009.

DISADVANTAGES
• Deeper structures visualised with less accuracy
• Operator dependent
• Sound beam beams cannot penetrate thick bone
• Sound beams are scattered by gas

CONCLUSION
• Ultrasound imaging in dentistry has been
increasingly developed and studied in recent
years and it seems that this technology will
gain even more space in dental practices.

References
• Shriki. Ultrasound physics. Crit Care Clin .2014; 30.1–24
• Rumack . Diagnostic ultrasound. Volume 1. 4th edition.
Mosby: elsevier. 2011. chapter 1: physics of ultrasound
• Goel S et.al. Ultrasonography with color Doppler and power
Doppler in the diagnosis of periapical lesions. Indian J Radiol
Imaging. 2011;21:279-83.
• Gaimari G et.al. Color-Doppler Ultrasound in the Diagnosis of
Oral Vascular Anomalies. North American Journal of Medical
Sciences | January 2014

References
• Marotti j . Recent advances of ultrasound imaging
in dentistry - a review of the literature. Oral Surg
Oral Med Oral Pathol Oral Radiol 2013

Thank you !!!www.indiandentalacademy.com

Ultra sonography indications in maxillofacial region /prosthodontic courses

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