Radiology in Head and Neck
Presenter : Kanato T
Radiology is a continually evolving
Since the discovery of x-rays.
Resulting in the numerous imaging
One should bear in mind that most
imaging techniques utilizing ionizing
radiation, including plain films,
computed tomography (CT) and nuclear
Carry with them a lifetime risk of
Useful To The ENT Surgeon
What Is an X-Ray?
An x-ray is a discrete bundle of
electromagnetic energy called a photon.
similar to other forms of electromagnetic
energy such as light, infrared, ultraviolet,
radio waves, or gamma rays.
Having no electrical charge, x-rays are
more penetrating than other types of
ionizing radiation (such as alpha or beta
particles) and are therefore useful for
imaging the human body.
Four basic densities:
1. Air is black or very dark.
2. fat is generally gray and darker than muscle
3. Bone and calcium appear almost white.
4. Items that contain metal (such as prosthetic
hips) and contrast agents also appear
The contrast agents are barium for
gastrointestinal studies and iodine for most
intravenously administered agents
Depends on kVp, mA, Time
If radiograph is too light
Increase kVp (increase the
penetrating power or energy
of the x-ray photons)
Increase mA (produce more
Or to increase time (produce
more x-ray photons)
If a radiograph is too dark
decrease kVp, mA, or time
Temporal Bone: Law’s View, Schullars view,
Stenver’s View, Transorbital View,
Nose and Paranasal Sinuses: Water’s View,
Caldwell View, Lateral View, Right and Left
Oblique Views, Lateral and Occlusal Views of
Neck: Lateral View and Anteroposterior
Views of Neck, Soft Tissue Lateral View
Nasopharynx, Submandibular Salivary Gland
Law’s View (Lateral view of
In 1913, Dr Frederik Law described lateral
view of mastoid bone.
Sagittal plane of the skull is parallel to the flim
X ray beam is projected 15 degree
mastoid air cells,
lateral sinus plate
1906, Dr Arthur Schuller, an Austrian
neuroradiologist, described an oblique view
of mastoid bone.
X-ray beam is projected 30° cephalocaudal
and prevents superimposition of two sides
of mastoid bones.
Structures seen: EAC superimposed on
IAC, mastoid air cells, tegmen, lateral sinus
plate, condyle of mandible, sinodural angle
and atticoantral region (key areas for
cholesteatoma and its erosion).
Extent of pneumatization, sclerotic
mastoid, destruction of intercellular
location of sinus plate (position of
sigmoid sinus) and
tegmen (roof of middle ear and floor of
middle cranial fossa),
longitudinal fracture of petrous
In 1917, Dr H. W. Stenver described Stenvers
view of temporal bone
Long axis of the petrous bone lies parallel to
Entire petrous pyramid,
internal auditory meatus,
labyrinth with its vestibule,
and mastoid antrum
In 1926, Dr E. B. Town of England described
This is an anteroposterior view of skull with
30° tilt from above and in front.
It shows both petrous pyramids, which can be
Structures seen: Both side temporal
arcuate eminence and superior
semicircular canal, mastoid antrum, IAC,
tympanic cavity, cochlea and EAC
Clinical applications: Acoustic neuroma
and apical petrositis.
This is an anteroposterior view of skull.
Orbitomeatal line is at right angles to the
X-ray beam passes through the orbit.
Structures seen: IAC, cochlea, labyrinth
petrous pyramids projected through the
Clinical applications: Acoustic neuroma
and petrous pyramid.
nose and paranasal Sinuses
Water’s view (occipitomental view):
In 1914, Dr C. A. Waters and C. W. Waldron,
two British radiologists, introduced the Waters
Nose and chin touch the film and X-ray
beam is projected from occipital side.
Open mouth view shows sphenoid sinus.
Petrous bones are projected below the
Fractures of right and left nasal bones and
their lateral displacement can be seen.
frontal process of
Caldwell view (occipitofrontal
Eugene W. Caldwell, In 1903, described a
view of the paranasal sinuses that still bears
his name, “the Caldwell view”
Nose and forehead touch the film and X-ray
beam is projected 15–20° caudally.
Frontal and ethmoidal sinuses are seen well
in this view.
Frontal, ethmoid and
Frontal process of
process of frontal
superior margins of
Lateral side of the skull lies against
the flim and X ray beam is projected
perpendicular from other side.
Structures seen :
Anterior and posterior extents of
sphenoid, frontal and maxillary
sinuses, sella turcica,
Ethmoid sinuses, alveolar process,
condyle and neck of mandible.
Common radiologic abnormalities
Air-fluid levels suggest an acute
Opacification = secretions, polyps, etc.
Thickened mucosa : Suggests chronic
Lateral views of nasal bones:
To see fracture line, depression or elevation of
the fractures segment.
Lower part of nasal bones, which is thin,
fracture more frequently.
Groove for ethmoidal nerve and vessels may
look like fracture line
Occlusal view of nasal bone:
Film is held between
the teeth and X-ray
beam is projected
perpendicular to the
It shows fracture line
displacement of the
nasal pyramid clearly.
Neck, Larynx and Pharynx
Lateral view of neck
Structure seen: Outline of
base of tongue, vallecula,
hyoid bone, epiglottis and
false and true cords with
ventricle in between
thyroid and cricoid
and trachea, prevertebral
soft tissues, cervical
and pretracheal soft
tissues and thyroid.
Radio-opaque foreign bodies of larynx, pharynx and
Position of tracheostomy tube and laryngeal stent
Fractures of larynx and hyoid bone and their
Compression of trachea by thyroid or
Caries of cervical spine associated with
Osteophytes in cervical vertebrae and injuries of
Chronic Retropharyngeal abscess
Secondary to TB
Erosion of cervical
FB Cricopharynx with Acute
Anteroposterior view of neck:
It helps in differentiating between a
foreign body of larynx and esophagus
(lateral view is also needed).
It shows compression or displacement
of trachea by lateral neck masses
such as thyroid swellings.
esophagus is an
Submandibular salivary gland:
Radio-opaque calculus can be seen.
procedure used to examine upper
gastrointestinal tract,which include the
pharynx, esophagus, cardia of stomach.
The contrast used is barium sulfate.
TYPES OF CONTRAST STUDY
(i) SINGLE CONTRAST STUDY
(ii) DOUBLE CONTRAST STUDY
Suspected esophageal perforation.
If strong clincal suspicion of aspiration
or TEF,then omnipaque swallow
SOFT TISSUE NECK,CHEST – AP &
The stenotic segment is long giving a “rat-
Barium swallow shows mild dilatation of the
esophagus with irregular stenotic lesion in
the lower end of the esophagus “moth
Radiologic examination of the salivary
The submandibular and parotid glands
are investigated by this method
The sublingual gland is usually not
evaluated this way because of
difficulty in cannulation
Obtain preliminary radiographs
Any condition that is visibe w/o contrast
Optimum technique obtained
2-3 min before procedure give lemon
Contrast media (iohexol) injected into
After procedure suck on lemon to clear
10 min after procedure take radiograph
(tomography of the mandible)
A pantomograph is a
visualization of entire
alveolar arches and
on a single extraoral
Ultrasound is sound within a frequency above
the upper limit of normal hearing.
Ultrasound images are formed from reflected
Sound waves are generated in short bursts by
the transducer (or probe)
and the sound energy that is reflected back is
collected at the point of origin (the transducer)
Piezoelectric material is used to
produce sound wave
Usually lead zirconate titanate
The higher the frequency of the probe
the lesser the depth of penetration but
gives better spatial resolution.
In neck most of the structures of interest
are superficial and required a higher
frequency probe of greater than 7.5
no known harmful effects and no
High-resolution ultrasound is quick and
Further, it is relatively inexpensive
compared to CT or MRI.
In addition to using echoes to generate
images, we can analyze the returning
echo frequencies. This Doppler analysis
allows identification of moving blood as
well as its direction and magnitude
Ultrasound appearance of
Normal lymphnode may be visualized by usg
in healthy subject, they are often not seen
due to their small size and similar echo-
texture with surrounding structure.
When apparent, lymph nodes are reactive,
inflammatory or neoplastic.
Retropharyngeal lymph nodes cannot be
seen with ultrasound.
Reactive lymph node.
(a) An oval-shaped,
node with an
(b) Florid colour
Doppler flow to the
consistent with a
An enlarged low
reflective mass with
an irregular border
carotid artery (short
For ultrasound imaging thyroid disorder may be
considered into two groups
Major role of usg in the assessment of disease
1. Detection of focal masses
2. Differentiation of multinodular goiter/hyperplasia
from other nodular disease
3. To document the extent of a known thyroid
4. Follow up to look for residual, recurrent or
5. Guidance for FNAC or fine needle aspiration for
Salivary gland disease
Both the parotid and submandibular glands
are superficial and well sited for ultrasound
Ultrasound accurately differentiates salivary
gland tumors from other lesions outside gland
Calculi larger than 2mm are detected by usg
And useful in defining location of calculi in
relation to the gland parenchyma
It detects the presence and extends of any
Doppler ultrasound measures blood
flow of vessels.
In Color Doppler flowing blood
appears either red or blue,
which depends upon the blood
direction, towards or away from the
„Power Doppler: It can demonstrate
Applications of Ultrasound
Differentiating cystic from solid masses
„Metastatic lymph nodes
„Tumor invasion of carotid vessels and internal jugular
„Tumors of parotid and submandibular salivary glands
„Salivary duct stones even less than 2 mm
„Detection and drainage of salivary gland abscess
under US guidance
„Masses of thyroid and parathyroid glands and US
guided fine needle biopsy
In 1972 Godfrey Hounsfield of Great
Britain invent CT.
Computed tomography (CT) is
accomplished by passing a rotating fan
beam of x-rays through the patient and
measuring the transmission at thousands
The data are handled by a computer that
calculates exactly what the x-ray
absorption was at any given spot in the
Compared with plain x-rays, CT uses
about 10 to 100 times more radiation
Computed tomography imaging
Imaging can be obtained in several
In most cases the axial (transaxial)
plane, usually parallel to the
orbitomeatal or infraorbitomeatal plane,
is used with the patient lying Supine
In addition, direct coronal imaging and
even direct sagittal imaging can be
In fact images can be reformatted in any
plane or any angle
Different views of CT pns
Conventional CT scanners have traditionally
operated in a step-and-shoot mode, defined
by data acquisition and patient positioning
Helical CT is characterized by continuous
patient transport through the gantry while a
series of x-ray tube rotations simultaneously
acquires volumetric data.
The evolution of multidetector CT scanners
(MDCTs) has resulted from the combination of
helical scanning with multislice data
In general, the basic four densities on
CT images are the same as those in
air is black,
fat is dark gray,
soft tissue is light gray,
bone or calcium and contrast agents
CT image display
Hounsfield unit: value of CT number
Defined by the relationship between the
linear attenuation value of the material
being scanned and that of water.
Gas = -1000 HU
Water = 0 (zero) HU
Bone = +1000 HU
Fat = - 80 to -100 HU
CT image display
The window level is simply the midpoint of the
densities chosen for display
For imaging of the soft tissues of the head and
neck, a window level of approximately 40 to 70
HU is usually chosen, at a midpoint
approximately equal to the density of muscle
For imaging bony structures such as paranasal
sinuses and temporal bone, window levels from
0 to +400 HU and a very wide window width of
2000 to 4000 HU may be chosen
The terminology commonly used to describe
the above mentioned windows includes soft
tissue windows (window width of 250 to 400
HU) and bone windows (2000 to 4000 HU).
Soft tissue window CT
Bone window CT
Helical or spiral CT scans a volume of
provides better quality images than
the conventional CT.
It covers more than 300 cm tissue
during a single breathhold of 30
multidetector CT scanners
MDCT can reduce scan time, permit
imaging with thinner collimation, or
Multidetector CT offers the additional
advantages of decreased contrast
load, reduced respiratory and cardiac
motion artifacts, and enhanced
multiplanar reconstruction capabilities.
With intravenous bolus administration
of iodinated contrast material.
permitted successful imaging of entire
CT angiography has become an
important tool for assessment of the
abdominal and iliac arteries and their
branches, the thoracic aorta, the
pulmonary arteries, and the extra- and
intracranial carotid circulation.
Processing of volumetric data:
The volumetric data can be processed
Multiplanar images: Sagittal and
Three-dimensional (3D) images
Virtual endoscopy: Such as
laryngoscopy, bronchoscopy and
3-D image reformatting
To evaluate bony
3-D reconstruction of
set obtained after
Gives better result
Optimal slice thickness
3 mm or 5mm = Neck structure
2 mm = facial bone, sinunasal cavities
and orbit, laryngohypopharyngeal
0.8 – 1 mm = Temporal bone
Applications of CT,
Extension of mucosal tumors of suprahyoid neck and metastatic
neck lymph nodes (ring enhancement)
„Salivary gland tumors and metastatic neck lymph nodes
„Computed tomography sialography
„Trauma, inflammation and cancer of larynx and laryngopharynx
with metastatic neck nodes
„Large or fixed thyroid tumors invading and compressing larynx,
laryngopharynx, trachea and mediastinum
„Paranasal sinuses prior to endoscopic sinus surgery, severe
nasal polyposis, tumors
„Temporal bone and skull base tumors, semicircular canal fistulas,
Magnetic resonance imaging
The protons in the nuclei of hydrogen behave
like small spinning bar magnets and align with
a strong external magnetic field.
A radio frequency pulse knocks protons out of
alignment, which release small amount of
energy while gradually returning to their original
This energy is detected by sensitive coils,
which are placed around patient.
Hydrogen atoms are abundantly present in
body water and MRI can differentiate the water
content of various tissues
The rate of energy loss is designated as the
longitudinal (T1) and transverse (T2)
T1 represents the restoration of the
longitudinal magnetization along the axis of
the main magnetic field
T2 represents the decay time of the
magnetization in the transverse plane.
Substances (e.g.,fluid) that have a long T1
will appear dark on T1-weighted images,
whereas those with short T1 (fat) will
display high signal intensity.
On T2-weighted images, a long T2
substance (fluid) will appear bright.
The commonly used pulse sequences
are T1-weighted (T1W), T2-weighted
(T2W), gadolinium-enhanced T1W, spin
(proton) density, fat-suppressed and
gradient echo imaging.
T1W: Because of high soft tissue
discrimination, T1W images show
exquisite anatomical details.
„T2W: The pathological lesions increase
T2 de-phase times, which produce
higher signal than surrounding normal
tissue in T2W images.
The combination of T1W and T2W
images is good for characterizing fluid
containing structures, solid components
MRI head sagittal section T1-
MRI head axial section T2-
Intravenous gadolinium (used in T1W)
reduces T1 relaxation time and
enhances lesions, which appear as
high signal intensity areas
Improved delineation of tumor margins
relative to the lower signal of muscle,
bone, vessel and globe.
Gadolinium enhancement is optimally
used with specific fat suppression
Short-tau inversion recovery:
The STIR sequence suppresses high
signal intensity from fat (that turn fat
black) and fluid containing structures
remain high signal intensity.
In STIR, decreased signal-to-noise ratio
degrades the image.
Magnetic resonance angiography:
It uses specific sequences
and demonstrates flowing blood.
(To quickly identify a
T1WI: fat is white,
CSF and vitreous are
black, and nasal
mucosa is low signal.)
(To quickly identify a
T2WI: CSF, vitreous,
and nasal mucosa are
white. Fat is low to
intermediate in signal.)
To quickly identify a
T1WI: nasal mucosa is
white, fat is white, and
CSF and vitreous are
To quickly identify a
suppresion): fat is
black; CSF, vitreous,
and mucosa are white
Superior soft tissue contrast resolution
No radiation exposure
Less image quality gets hampered by
the presence of dental fillings
Long image acquisition time
More chance of motion artifacts
Difficult to stage both primary tumour and
neck nodal disease
Higher cost and less availability
Absolute contraindications to MRI include
patients with cardiac pacemakers,
cochlear implants, and ferromagnetic
intracranial aneurysm clips.
Those patients at risk for metallic orbital
foreign bodies should be screened with
plain films or CT before MRI.
Applications of MRI
Tumors of nasopharynx, oropharynx, oral cavity
„Extracapsular spread of tumor from nodes
„Perineural spread and extension beyond gland
of salivary gland tumors
„Tumors of nose and paranasal sinuses:
Distinguish between tumor and obstructed sinus
secretions (hydrated fluid,viscous, desiccated);
Perineural spread to anterior cranial fossa, orbit,
parapharyngeal space and pterygopalatine
fossa and cribriform plate extension
„Lesions of IAC, facial nerve canal, and jugular
foramen; acoustic schwannoma
„Skull base tumors
such as technetium-99m (99mTc)-
pertechnetate concentrate selectively in
certain tissues and emit gamma
radiation detected by a gamma camera.
It provides two-dimensional display of
physiological and functional changes in
In salivary gland imaging 99mTc pertechnetate
imaging may be useful for assessing salivary
gland function in autoimmune and
inflammatory disease of the salivary glands.
If obstructed, the degree of obstruction as well
as the follow-up of obstruction after treatment
can be assessed.
In evaluating neoplasms of the salivary glands
the findings of the 99mTcpertechnetate scan
are almost pathognomonic of Warthin's tumor
Most nuclear medicine imaging uses
various isotopes of iodine (131I and
123I), Technitium-99m pertechnetate
to determine thyroid function, identify
hot or cold nodules, or access extent
of thyroid masses and tumors.
1- 4 % of hot nodules – malignant
Upto 25 % of cold nodule – malignant
Positron emission tomography
The positron emission tomography provide a
means of identifying pathology based on
altered tissue metabolism.
Imagining technique relies on a radioactive
molecule(radiotracer) that decay with positron
The radiotracer is given intravenously to the
patient and is taken into cells.
Malignant cell trap more radiotracer compare
to non malignant cells.
The local radiotracer concentration can be
PET image lack anatomical details, which
can be overcome by combining with CT/MR
using software technique
Depending on the radiotracer used different
aspects of tissue metabolism can be
An analogue of glucose, 2-[18F] fluoro-2-
deoxy-D-glucose (FDG) which reflects
glucose metabolism is commonly use.
Positron Emission Tomography
Used for staging and evaluation of
recurrence for primary head and neck
tumors, detecting distant lymph node,
soft-tissue and skeletal metastases
More accurate than CT or MRI in
detecting residual or recurrent nodes
Highly reliable after 3 – 4 months of
end of treatment.
Indications of FDG with integrated PET/CT
SCC patients with
equivocal nodal disease following
-suspicion of recurrent/residual disease.
Patients with occult primary tumors.
Post-treatment papillary and follicular
thyroid cancer patients with elevated
thyroglobulin and negative 131-I scan.
Patients with clinical suspicion of more
disease than conventional assessment
Patients where resectability is in doubt.
Effect of radiation
The effects of radiation are usually classified
into two categories, depending on the intensity
of the radiation and the time period of
These electrons may damage DNA molecules
directly or produce free radicals that can
chemically damage genetic material; either
effect may result in cell death or mutation
These categories are referred to as
1. stochastic effects
2. deterministic effects
The severity of stochastic effects is
independent of the absorbed dose.
Under certain exposure conditions, the
effects may or may not occur.
There is no threshold and the probability of
having the effects is proportional to the dose
Example: radiation induced cancer, genetic
severity of certain effects on human beings
will increase with increasing doses.
There exists a certain level, the "threshold",
below which the effect will be absent.
This kind of effects is called "deterministic
Example: cataract, erythema, infertility etc.
Adam Grainger & Allison's Diagnostic
Radiology 5th ed
Basic Radiology LANGE clinical science.
Scott-Brown’s Otorhinolaryngology, Head
and Neck Surgery 7th edition.
Surgery of ear Glasscock Shambaugh 6th
Mohan Bansal Disease of Ear, Nose and
Head and Neck Imaging, Peter M. Som