CT Imaging of Head and Neck Flashcards
BRAIN IMAGING
Examples of clinical indications
- Without contrast:
intracranial hemorrhage, early infarction, dementia, hydrocephalus, cerebral trauma
BRAIN IMAGING
Examples of clinical indications
- Without and with contrast:
Mass, lesion, arteriovenous malformation, metastasis, aneurysm, for symptoms of headache, seizure
BRAIN IMAGING Scout
AP and lateral
BRAIN IMAGING Scan type
Axial
BRAIN IMAGING Scan plane
Transverse
BRAIN IMAGING Start location
Just below skull base
BRAIN IMAGING End location
Just above vertex
BRAIN IMAGING IV contrast
100 mL at 1.0 mL/s
Scan delay = 5 minutes
BRAIN IMAGING Oral Contrast
None
BRAIN IMAGING Reference Angle
Angle gantry parallel to supraorbital meatal line (avoid lens of eyes)
BRAIN IMAGING SFOV
Head
BRAIN IMAGING Algorithm
Standard
BRAIN IMAGING Window settings
140 ww/40 wl
BRAIN IMAGING Gantry rotation time
2.0 s or 1.0 s depending on the CT scan
BRAIN IMAGING Reconstruction (slice thickness/interval)
5.0 mm/5 mm (2 images per rotation)
BRAIN IMAGING kVp/mA (posterior fossa)
140/150
BRAIN IMAGING kVp/mA (vertex)
120/150
BRAIN IMAGING Reconstruction 2:
Algorithm: Bone
Window setting: 4000 ww/400 wl
DFOV: ∼23
Slice thickness/interval 2.5 mm/2.5 mm
- Lens shaped (dura tightly adhered to skull
- Can cross midline
- Frequently assoc. with fracture
Epidural Hematoma
Follows the contour of the brain & doesn’t cross the midline
Subdural Hematoma
TEMPORAL BONE IMAGING Examples of clinical indications
- Without contrast:
cholesteatoma, inflammatory disease, fractures, evaluate implants
TEMPORAL BONE IMAGING Examples of clinical indications
- With contrast:
IAC tumor, hearing loss, acoustic neuroma, Schwannoma
TEMPORAL BONE IMAGING Scout
AP and lateral
TEMPORAL BONE IMAGING Scan type:
Axial
TEMPORAL BONE IMAGING Scan plane:
Transverse
TEMPORAL BONE IMAGING Start location
Just below the mastoid process
TEMPORAL BONE IMAGING End location
Just above petrous ridge (include entire mastoid, internal auditory canal, and external auditory canal)
TEMPORAL BONE IMAGING IV contrast
(if contrast is ordered) 100 mL at 1.0 mL/s. Scan delay = when all contrast is administered
TEMPORAL BONE IMAGING Oral Contrast
None
TEMPORAL BONE IMAGING Reference Angle
Angle gantry parallel to infraorbital meatal line (be sure patient’s head is straight and not rotated in the head holder)
TEMPORAL BONE IMAGING DFOV
~ 9.6cm
TEMPORAL BONE IMAGING SFOV
Head
TEMPORAL BONE IMAGING Algorithm
Bone
TEMPORAL BONE IMAGING Window settings
4000ww/400wl
TEMPORAL BONE IMAGING kVp/mA
140/170
TEMPORAL BONE IMAGING Gantry rotation time
1.0s
TEMPORAL BONE IMAGING Reconstruction (slice thickness/interval):
0.625 mm/0.625 mm
TEMPORAL BONE IMAGING Reconstruction 2:
Algorithm: Bone
Window setting: 4000 ww/400 wl
DFOV: ∼9.6 cm
Slice thickness and interval: 0.625 mm/0.625 mm
is intended as an inexpensive, accurate, and low radiation dose method for confirming the presence of inflammatory sinonasal disease
Sinus screening
PARANASAL SINUSES(SCREENING) CT scans typically obtained for visualizing the paranasal sinus should include
coronal and axial (3-mm) cross sections
In Paranasal Sinuses Screening, _____ facilitate evaluation of disease processes and the bony architecture.
Soft tissue and bony windows
In Paranasal Sinuses Screening, the use of ____ just prior to scanning can help define soft tissue lesions and delineate vascularized structures, such as vascular tumors.
Intravenous constrast material
Contrast-enhanced CT is particularly useful in evaluating
neoplastic, chronic, and inflammatory processes.
PARANASAL SINUSES SCREENING
Examples of clinical indications:
Recurrent or chronic sinusitis
PARANASAL SINUSES SCREENING
Scout
Lateral
PARANASAL SINUSES SCREENING
Scan type
Axial
PARANASAL SINUSES SCREENING
Scan plane
Coronal
PARANASAL SINUSES SCREENING
Start location
Mid sella
PARANASAL SINUSES SCREENING
End location
Through frontal sinus
PARANASAL SINUSES SCREENING
IV contrast
none
PARANASAL SINUSES SCREENING
Oral contrast
none
PARANASAL SINUSES SCREENING
Reference angle
Angle gantry perpendicular to the orbital meatal line
PARANASAL SINUSES SCREENING
DFOV
16 cm
PARANASAL SINUSES SCREENING
SFOV
Head
PARANASAL SINUSES SCREENING
Algorithm
Standard
PARANASAL SINUSES SCREENING
Window settings
350ww/50wl
PARANASAL SINUSES SCREENING
Reconstruction (slice thickness/interval):
2.5mm/2.5mm
PARANASAL SINUSES SCREENING
kVp/mA
120/150
PARANASAL SINUSES SCREENING
Reconstruction 2:
Algorithm: Bone
Window setting: 4000 ww/400 wl
DFOV: ∼23
Slice thickness/interval 2.5 mm/2.5 mm
FACIAL BONES
Examples of clinical indications:
Characterization of facial fractures and soft tissue injury
FACIAL BONES Scouts
AP and lateral
FACIAL BONES Scan type
Helical
FACIAL BONES Scan plane
Transverse
FACIAL BONES Start location
Just below mandible
FACIAL BONES End location
Just above frontal sinus
FACIAL BONES IV contrast
none
FACIAL BONES Oral contrast
none
FACIAL BONES Reference angle
Angle gantry parallel to infraorbital meatal line
FACIAL BONES DFOV
18 cm
FACIAL BONES SFOV
Head
FACIAL BONES Algorithm
Standard
FACIAL BONES Window settings
350ww/50wl
FACIAL BONES Gantry rotation time
0.8s
FACIAL BONES Reconstruction (slice thickness/interval)
1.24 mm/0.625 mm
FACIAL BONES Pitch
0.562
FACIAL BONES kVp/mA
120/250
FACIAL BONES Reconstruction 2
Algorithm: Bone
Window setting: 4000 ww/400 wl
DFOV: 18
Slice thickness/interval: 1.25 mm/0.625 mm
Tripod Fracture
Zygomatic-frontal suture
Zygomatic arch
Maxillary sinus wall
Routine scanning of the neck is typically performed with the patient in
supine and the neck slightly extended
Neck scanning is most often performed in the
Helical mode
To reduce artifacts that degrade images in the lower neck, the patient should be instructed to
lower the shoulders as much as possible
The goals in CT scanning of the neck are
to allow sufficient time after contrast administration for mucosa, lymph nodes, and pathologic tissue to enhance, yet acquire images while the vasculature remains opacified
NECK IMAGING
Examples of clinical indications:
Neck mass, vascular abnormality
If patient has metal dental work, split scan into two groups and angle to reduce artifact
NECK IMAGING Scouts
AP and lateral
NECK IMAGING Scan type
Helical
NECK IMAGING Scan plane
Transverse
NECK IMAGING Start location
Mid orbit
NECK IMAGING End location
Clavicular heads
NECK IMAGING IV contrast
125 mL at 1.5 mL/s.
Split bolus—1st injection 50 mL, 2-minute delay; 2nd injection 75 mL, scans initiated 25 seconds after the start of the second injection.
NECK IMAGING Oral contrast
none
NECK IMAGING Reference angle
Angle gantry parallel to hard palate
NECK IMAGING DFOV
18 cm
NECK IMAGING SFOV
Large body
NECK IMAGING Algorithm
Standard
NECK IMAGING Window settings
350ww/50wl
NECK IMAGING (Cervical Spine) Examples of clinical indications
Fracture, dislocation
NECK IMAGING (Cervical Spine) Scouts
AP and lateral
NECK IMAGING (Cervical Spine) Scan type
Helical
NECK IMAGING (Cervical Spine) Scan plane
Transverse
NECK IMAGING (Cervical Spine) Start location
Just above skull base
NECK IMAGING (Cervical Spine) End location
Mid T1 (include all cervical spine vertebrae, unless a level is specified)
NECK IMAGING (Cervical Spine) IV contrast
(only when requested by radiologist) 100 mL at 1.5 mL/s.
Scan delay = when injection is complete
NECK IMAGING (Cervical Spine) Oral contrast
none
NECK IMAGING (Cervical Spine) Reference angle
No gantry tilt
NECK IMAGING (Cervical Spine) DFOV
~ 13cm
NECK IMAGING (Cervical Spine) SFOV
Large body
NECK IMAGING (Cervical Spine) Algorithm
Standard
NECK IMAGING (Cervical Spine) Window settings
350ww/50wl
NECK IMAGING (Cervical Spine) Gantry rotation time
0.8s
NECK IMAGING (Cervical Spine) Reconstruction (slice thickness/interval)
2.50mm/1.25mm
NECK IMAGING (Cervical Spine) Pitch
0.562
NECK IMAGING (Cervical Spine) kVp/auto mA
140/125-325
NECK IMAGING (Cervical Spine) Reconstruction 2
Algorithm: Bone
Window setting: 4000 ww/400 wl
DFOV: ∼13 cm
Slice thickness/interval: 2.5 mm/1.25 mm
NECK IMAGING (Cervical Spine) Reformations
Coronal and Sagittal
NECK IMAGING (Cervical Spine) Algorithm
Bone
NECK IMAGING (Cervical Spine) Window setting
4000ww/400wl
NECK IMAGING (Cervical Spine) DFOV
Full
NECK IMAGING (Cervical Spine) Slice thickness/spacing
2.0mm/2.0mm
CT angiography advantages:
- The time-saving nature of CTA over traditional angiography is particularly important in the case of patients suspected of suffering an acute stroke in which treatment decisions must be made quickly.
noninvasive and widely available
The goals of CTA for cervicocranial vascular evaluation:
1) to accurately measure stenosis of the carotid and vertebral arteries and their branches,
2) to evaluate the circle of Willis for completeness using three-dimensional reformations of cerebral vasculature in relation to other structures,
3) to detect other vascular lesions, such as dissections or occlusions.
used for the depiction of venous anatomy
CT venography (CTV)
Scan parameters for CT venography are quite similar to CTA, except images are acquired while contrast is in
the venous enhancement phase.