Handbook 2021

IMAGING TECHNIQUE II

Skull and Cranial Bones
Facial Bones
Paranasal Sinus

DR. NUR HAYATI JASMIN

Skull and Cranial Bones
Radiographic Anatomy
Surface Landmarks
Radiographic Positioning
Radiographic Critique
Case Study

Facial Bones
Radiographic Anatomy
Radiographic Positioning
Radiographic Critique
Case Study

Paranasal Sinus
Radiographic Anatomy
Radiographic Positioning
Radiographic Critique
Case Study

References

Radiographic Anatomy

Cranial Bones (8)

Frontal view Lateral view Superior cutaway view

Frontal Bone Calvaria/Skullcap:
Frontal
Parietal and Occipital Bone Right Parietal
Left Parietal
Occipital

Floor:
Right Temporal
Left Temporal
Sphenoid
Ethmoid

Frontal Bone:
Vertical portion
forms the
forehead
Horizontal
portion forms the
superior part of
the orbit

Parietal Bones:
Forms the lateral
walls of the
cranium and part
of the roof.
Roughly square
and have a
concave internal
surface.

Occipital Bone:
Foramen
magnum – Spinal
cord passes
through here.
Lateral condyles –
Articulation
between skull
and cervical
spine.

Radiographic Anatomy Temporal Bones:
House the delicate
Temporal Bones organs of hearing
and balance
Sphenoid Bone (Petrous pyramid).
Squamous portion
Ethmoid Bone – the most
vulnerable portion
of the entire skull.
Petrous ridge –
the upper border
of petrous
pyramid
Corresponds to
the level of TEA

Sphenoid Bones:
Sella turcica
surrounds and
protects the major
gland of the body
(pituitary gland).
Lesions can cause
erosion to the
foramina.
Superior orbital
fissure – passage
for cranial nerves
and blood vessels
to the orbits

Ethmoid Bone:
Located anterior
to the sphenoid
bone
Cribriform plate –
contains many
openings for the
olfactory nerves

Radiographic Anatomy

Joints of the Cranium (Sutures)

Xxxxx:
Xxxx

Landmarks

Body planes and landmarks

Positioning lines:
AML: Acanthiomeatal line
LML: Lips-meatal line
MML: Mentomeatal line
GML: Glabellomeatal line
OML: Orbitomeatal line
IOML: Infraorbital meatal line

Orbit landmarks Positioning lines
Surface landmarks Positioning aid

Angle ruler – IOML to IR

AP axial (Towne method)

Projections - Skull Series:
Basic:

AP axial (Towne method)
Lateral
PA axial 15⁰ (Caldwell
method)/ PA axial 25⁰ to 30⁰
PA 0⁰
Special:
Submentovertex (SMV)
PA axial (Haas method)
Sella Turcica (Lateral)
Sella Turcica (AP axial –
Towne method)

Part Position: Technical Factors:
Depress chin, bringing OML perpendicular to IR. SID: 100 cm
For patients who unable to flex the neck to this extent, IR size: 24 x 30 cm
align IOML perpendicular to IR. (lengthwise)
Align MSP to CR and to the midline of the grid or the Grid
table/imaging device surface. Analog: 70 to 80 kV
Ensure no head rotation and/or tilt. range
Ensure vertex in included. Digital system: 80 to 85
kV range
Central Ray:
Angle CR 30⁰ caudad to OML, or 37⁰ caudad to IOML Structures Shown:
Center at MSP, 6 - 6.5 cm above the glabella to pass Occipital bone,
through the foramen magnum at the level of the base of Petrous pyramids, and
the occiput foramen magnum are
demonstrated with the
Collimation: dorsum sellae and
Superior to include skin margins Posterior clinoids
Inferior to include base of skull visualized in the shadow
Lateral to the skin margins of the foramen
magnum

AP axial (Towne method)

Cranial Bones - AP Axial Towne
A - Dorsum sellae of the sphenoid
B - Posterior clinoid processes
C - Petrous ridge or petrous pyramid
D - Parietal bone
E - Occipital bone
F - Foramen magnum

Indication:
This projection is used to evaluate for medial
and lateral displacements of skull fractures, in
addition to neoplastic changes and Paget
disease.

Practical Points:
If the dorsum sella projects above the foramen magnum it requires an increase in the angle.
If the anterior arch of C1 is laying in the foramen magnum, less angle is required.
The Towne view allows better occipital bone and frontal evaluation of the posterior fossa
region than a standard nonangled frontal skull view.
The lambdoid suture is better evaluated than on nonangled views.
The addition of a Towne view to skull AP and lateral views has been thought to result in better
sensitivity for detecting skull fractures than an AP and lateral view alone.
Better than a conventional AP 0 degree view for evaluating an occipital plagiocephaly involving
the lambdoid suture.

Radiographic Criteria:
No rotation: Petrous ridge should be symmetrical
Correct CR and proper neck flexion/extension: Dorsum sellae visualized in the foramen
magnum
Underangulation: Dorsum sellae above the foramen magnum
Over angulation: Anterior arch of C1 projected into the foramen magnum rather than the
dorsum sellae.
Tilt: Shifting of the anterior or posterior clinoids within the foramen magnum.
Exposure Criteria:
Density and contrast - Sufficient to visualize occipital bone and sellar structures within the
foramen magnum.
Sharp bony margins indicate no rotation.

Are there any positioning errors in these images?

AP axial (Towne method)

Reference:

Notes:

AP axial (Towne method)

Cranial Bones - AP Axial Towne
A - Dorsum sellae of the sphenoid
B - Posterior clinoid processes
C - Petrous ridge or petrous pyramid
D - Parietal bone
E - Occipital bone
F - Foramen magnum

Indication:
This projection is used to evaluate for medial
and lateral displacements of skull fractures, in
addition to neoplastic changes and Paget
disease.

Example case study:

Case Study 1: Towne view
Patient Presentation
Conscious, ambulant, and cooperative 22-year-old patient who was involved in a motor vehicle
accident (MVA) is referred to Radiology Department for an x-ray of the skull. The patient
complains of (C/o) pain in the head. Lateral skull projection revealed fracture (#) of the skull.
You are requested to perform an additional view of the AP axial Towne view of the skull.
Physical Examination
Scalp wounds/swelling on the left side
Facial abrasion
Indication: TRO lateral displacements of skull fracture
Projection: AP Axial Towne

Case Study 2: Towne view
Patient Presentation
An unconscious, ambulant, and uncooperative 25-year-old patient who was involved in a
motor vehicle accident (MVA) is referred to Radiology Department for an x-ray of the skull. The
patient complains of pain at the backside of the head.
Physical Examination
Scalp wounds/swelling
Indication: TRO fracture of Occipital bone
Projection: AP Axial Towne

Case Study 3: Towne view (Paediatric - Infant)
Patient/Clinical Presentation
The right side of the head appears flattened when it is viewed from above. A bump is seen
behind the ear on the ipsilateral side or the ipsilateral ear might be pulled backwards.
However, if the ear is forward on the flat side (with respect to the opposite ear), and there is
no reduction in skull height on the affected (right) side, then a skull deformation should be
suspected instead of a fused suture. It is critically important to determine whether or not a
child truly has a fused suture because skull deformations almost never need to be surgically
treated.
Indication: TRO Occipital plagiocephaly
Occipital plagiocephaly is used to describe the shape of the skull which is a result of an early
fusion of the lambdoid suture. The premature fusion may occur either on one side or both
sides of the suture.
Projection: AP Axial Towne

Lateral

Projections - Skull Series:
Basic:

AP axial (Towne method)
Lateral
PA axial 15⁰ (Caldwell
method)/ PA axial 25⁰ to 30⁰
PA 0⁰
Special:
Submentovertex (SMV)
PA axial (Haas method)
Sella Turcica (Lateral)
Sella Turcica (AP axial –
Towne method)

Part Position: Technical Factors:
Place the head in a true lateral position, with the side of SID: 100 cm
interest closest to IR and the patient’s body in a semi- IR size: 24 x 30 cm
prone position (crosswise)
Align MSP parallel to IR, ensuring no rotation or tilt. Grid
Align IPL perpendicular to IR, ensuring no tilt of head Analog: 70 to 80 kV
Adjust neck flexion to align IOML perpendicular to range
front edge of IR Digital system: 80 to 85
kV range
Central Ray:
Center to a point 5 cm superior to EAM or halfway Structures Shown:
between the glabella and the inion Superimposed cranial
halves with superior
Collimation: details of the lateral
Superiorly to include skin margins cranium closest to the
Inferiorly to include base of skull IR.
Anteriorly to include frontal bone The entire sella turcica,
Posteriorly to the skin margins including anterior and
posterior clinoids and
dorsum sellae, is shown.
The sella turcica and
clivus are demonstrated
in profile.

Lateral

Cranial Bones - AP Axial Towne
A - Dorsum sellae of the sphenoid
B - Posterior clinoid processes
C - Petrous ridge or petrous pyramid
D - Parietal bone
E - Occipital bone
F - Foramen magnum

Indication:
Skull fractures, in addition to neoplastic changes and Paget disease. A common
general routine includes both left and right laterals.
This view provides an overview of the entire skull rather than attempting to highlight
any one region.
Myleodysplastic syndrome. Skeletal survey.

Practical Points:
Trauma routine - A horizontal beam is required to obtain a lateral view for trauma patients.
These may demonstrate air-fluid levels in the sphenoid sinus - a sign of basal skull fracture if
intracranial bleeding occurs.

Radiographic Criteria:
Rotation: is evident by anterior and posterior separation of EAMs, mandibular rami, mastoid
process, etc.
Tilt: is evident by superior and inferior separation of symmetric horizontal structures such as the
orbital roofs, and mandibular bodies.
Exposure Criteria:
Density and contrast - Sufficient to visualize bony detail of sellar structures and surrounding
skull.
Sharp bony margins indicate no rotation.

Are there any positioning errors in these images?

Lateral

Cranial Bones - AP Axial Towne
A - Dorsum sellae of the sphenoid
B - Posterior clinoid processes
C - Petrous ridge or petrous pyramid
D - Parietal bone
E - Occipital bone
F - Foramen magnum

Indication:
Skull fractures, in addition to neoplastic changes and Paget disease. A common
general routine include both left and right laterals.

Example case study:

Case Study 1: Lateral Skull
Patient Presentation
An 18-year-old male was brought to the emergency department after he was found
unconscious on the ski slope. His friends told the ski patrol that while they were "boarding" on
a difficult run he lost control and collided with a tree. He has regained his consciousness and
is ambulant upon arrival at the radiology department.
Physical Examination
Facial abrasions
Swelling above the right ear
Indication: TRO lateral skull fracture
Projection: Lateral
Finding:
Radiography upon admission to the emergency department confirmed a small, lateral skull
fracture

Case Study 2: Lateral Skull
Patient Presentation
A 20-year-old woman was brought to the emergency department. She is conscious and
ambulant. The patient complains (C/o) of having an increasing headache and dizziness.
Suspected of base skull fracture with intracranial bleeding.
Physical Examination
Facial abrasions
Unequal pupil size.
Slurred speech.
Indication: TRO base skull fracture (Erect)
Projection: Lateral
Finding:
Intracranial bleeding - air-fluid levels is seen in the sphenoid sinus.

Caldwell Method

Projections - Skull Series:
Basic:

AP axial (Towne method)
Lateral
PA axial 15⁰ (Caldwell
method)/ PA axial 25⁰ to 30⁰
PA 0⁰
Special:
Submentovertex (SMV)
PA axial (Haas method)
Sella Turcica (Lateral)
Sella Turcica (AP axial – Towne
method)

Part Position: Technical Factors:
Rest patient’s nose and forehead against table/imaging device SID: 100 cm
surface. IR size: 24 x 30 cm
Flex neck as needed to align OML perpendicular to IR. (lentghwise)
Align MSP perpendicular to the midline of the grid or Grid
table/imaging surface to prevent head rotation or tilt. Analog: 70 to 80 kV
range
Central Ray: Digital system: 80 to 85
CR - PA axial with 15°caudad kV range
Angle CR 15°caudad, and center to exit at nasion.
CR - PA axial with 25°to 30°caudad
Alternative with CR 25°to 30°caudad, and center to exit at
nasion.

Collimation:
Outer margins of skull.

PA 15°caudad PA 30°caudad

Caldwell Method

PA 15°caudad PA 30°caudad

Structures Shown:
PA axial with 15°caudad
Petrous pyramids are projected into the lower one third of the orbits
Supraorbital margin is visualized without superimposition
PA axial with 25°to 30°caudad
Petrous pyramids are projected at or just below the IOM to allow visualization of
the entire orbital margin
Better visualization of superior orbital fissures, the foramen rotundrum, and the
inferior orbital rim region.

Caldwell Method

Cranial Bones - AP Axial Towne
A - Dorsum sellae of the sphenoid
B - Posterior clinoid processes
C - Petrous ridge or petrous pyramid
D - Parietal bone
E - Occipital bone
F - Foramen magnum

Indication:
This view aids in visualizing the paranasal sinuses, especially the frontal sinus. It can help to
assess 4 inflammatory conditions such as sinusitis and secondary osteomyelitis, and sinus
polyps or cysts.
Additionally, any fractures to the orbit may also be determined through this view

Practical Points:
Alternative - For patients who are unable to be positioned for a PA projection, an AP axial
projection may be obtained with the use of 15 degree angle cephalic, with OML positioned
perpendicular to the IR.

Radiographic Criteria:
Rotation: is evident by
Tilt: is evident by
Exposure Criteria:



Are there any positioning errors in these images?

Caldwell Method

Cranial Bones - AP Axial Towne
A - Dorsum sellae of the sphenoid
B - Posterior clinoid processes
C - Petrous ridge or petrous pyramid
D - Parietal bone
E - Occipital bone
F - Foramen magnum

Indication:
This view aids in visualizing the paranasal sinuses, especially the frontal sinus. It can
help to assess 4 inflammatory conditions such as sinusitis and secondary
osteomyelitis, and sinus polyps or cysts.
Additionally, any fractures to the orbit may also be determined through this view

Example case study:

Case Study 1: Caldwell view
Patient Presentation
Age: 42
Gender: Female
Indication: Left orbital injury. Fracture?
Projection: PA 25 degree (Caldwell Method)
Finding:
The black eyebrow sign indicates orbital emphysema, typically from a orbital fracture, with air
having entered from the adjacent sinuses.

Case Study 2: Caldwell view
Patient Presentation
Age: 55
Gender: Female
C/o: constant, dull bone pain in the head, severe headache.
Indication: Paget's disease
Projection: PA 15 degree (Caldwell Method)
Finding:
Thickened sclerotic bone, especially at the skull base and large areas of radiolucencies with
deformity of the skull vault on the right.