Transcript RAD 473 - Lec 3, 4 - INAYA Medical College

COMPUTED TOMOGRAPHY II
– RAD 473
Prepared By:
Ala’a Ali Tayem Abed
SINUSES CT SCAN
Screening Sinus CT
 CT of the sinuses primarily is used to:
1. Detect the presence of inflammatory diseases.
2. Plan for surgery by defining anatomy or giving further information about tumors of the
nasal cavity and sinuses.
3. Evaluate sinuses that are filled with fluid or thickened sinus membranes.
4. Help diagnose sinusitis.
 Scout image: Patient is placed supine. The alignment of the scan is perpendicular to the
hard palate. The scan is set up to start posterior to the sphenoid sinus and continued anteriorly
through the frontal sinuses and anterior face.
 Contrast: 100cc Omnipaque 300 IV, R/O sinus or nasal cavity tumor
 kVp / Effective mAs / Rotation time (sec) 120 / 130 / 0.75
 FOV : 180 mm.
 Thickness : 3 mm.
 Resolution : high.
 Bone Window: WC : 200, WW : 2000
 Soft Tissue Window: WC : 50, WW : 350
 Submit images in bone and soft tissue algorithm, ALL 3 PLANES at 2mm x 2mm.
Scan Coverage:
Maxillary teeth
through frontal
sinuses
Maxillary Sinus
Ethmoid Sinus
Sphenoid Sinus
Sagittal reconstructions
(through all sinuses)
Coronal reconstructions
(back of sphenoid sinus through
nose)
CT axial view shows a
well-defined expansile
lesion (black arrow)
with sclerotic margin
( red arrow),
scattered amorphous
calcification and teeth
within the lesion
(yellow arrow).
CT coronal view
shows an expansile
lesion in the right
maxilla exhibiting
features of
calcification,
presence of teeth
displaced due to the
lesion (black arrow)
and involving the
floor of the maxillary
sinus.
A computed
tomography
sagittal view of
a front sinus
active ossifying
fibroma.
Axial image with arrow
pointing to air-fluid level
in maxillary sinus in acute
sinusitis. Note the slightly
bubbly appearing fluid.
Axial image demonstrating
additional case of acute
sinusitis with arrows pointing
to air-fluid levels in the
Ethmoid and sphenoid
sinuses
Coronal image with
arrow pointing to
right maxillary
sinus mucus
retention cyst
(MRC).
Coronal image with arrow pointing to
maxillary sinus polyp. Often on imaging a
polyp and mucus retention cyst cannot be
differentiated
TEMPORAL BONE
CT SCAN
Temporal Bone CT
 Temporal bone CTs, also known as mastoid bone CTs are typically ordered to evaluate the
outer ear, bones of the ear and inner ear structures for infection, tumor, injury or congenital or
acquired hearing disorders.
Axial scout image: The patient is placed supine. The alignment of the plane is parallel to the
Orbitomeatal line. This is set up to start at the top of the anterior arch of C1, and scan
superiorly to the roof of the mastoid air cells.
 Coronal scout image: The patient is placed prone with the neck hyperextended. The
alignment of the plane is perpendicular to the Orbitomeatal line. This is set up to start at the
posterior edge of the mastoid air cells and go anteriorly to the mid-portion of the TMJ.
 kVp / Effective mAs / Rotation time (sec): 120 / 160 / 1.0
 FOV : 100 mm.
 Res: Ultra high bone algorithm.
 Thickness : 1 mm.
 Bone Window: WC: 400, WW: 4000
 Soft Tissue Window: WC: 50, WW: 350
 Submit images in bone and soft tissue algorithm.
Scan Coverage: Above Petrous
ridges to tip of mastoids
Mandibular condyle
Ossicles
External
auditory
canals
Mastoid
air cells
Clivus
Temporal Bone Fracture
The eardrum is thickened.
A small amount of soft tissue (arrow) is visible
between the scutum and the ossicular chain but no
erosion is present.
This favors the diagnosis of chronic otitis media.
Cochlear Implantation
Temporal Bone Tumor
Temporal Bone Tumor
CT scan of the head demonstrating a
large hyperdense mass in the right
CP angle, solid arrow,
(Schwannoma).
Right acoustic neuroma
(schwannoma).
FACIAL BONE CT SCAN
Facial Bones CT (also use for mandible protocol)
 A CT of the Facial Bones is an exam that takes very thin slice (2-3.5mm) images of the
facial bone structure, including the jaw, nose, eye sockets and cheek bones. These images are
helpful in the diagnosis of facial trauma and malformations.
Axial scout image: Patient is placed supine. The scan is set up to start below the mandible
and continue superiorly through the frontal sinuses. The alignment is with the plane of a line
from the center of the orbit though the external auditory canal, called the Orbitomeatal line.
 Coronal scout image: Patient is placed prone, with the neck hyperextended. The scan is
set up to start posterior to the sphenoid sinus and continued anteriorly through the frontal
sinuses and anterior face.
 FOV : 180 mm.
 Thickness : 3 mm.
 Resolution : high.
 Bone Window: WC : 200, WW : 2000
 Soft Tissue Window: WC : 50, WW : 350
 Submit images in bone and soft tissue algorithm.
Scan Coverage:
Maxillary teeth through
frontal sinuses; If
mandibular trauma,
begin below mandible
Sagittal reconstructions
through Zygomatic arches
Coronal reconstructions
external auditory canals
through nasal bones
Nasal Bone Fracture
three-dimensional (3-D) model made
from a CT scan showing a broken
(fractured) cheekbone that extends
into the gum of the mouth.
3-dimensional reconstruction
of the fracture under the eyesocket on the left side of the
image.
ORBIT CT SCAN
Orbit CT
 A CT of the Orbits is an exam that takes very thin slice images of the eyes and orbital
socket at three different angles. This allows for the diagnosis of a range of conditions such as
injury, disease and congenital defects.
Axial scout image: Patient is placed supine. The scan is set up to start at the hard palate
and continue superiorly through the orbits. The alignment is with the plane of a line from the
center of the orbit though the external auditory canal, called the Orbitomeatal line.
 Coronal scout image: Patient is placed prone, with the neck hyperextended. The scan is
set up to start posterior to the sphenoid sinus and continued anteriorly through the frontal
sinuses and anterior face.
If a contrasted study is required, Common Histories: Cannot have MR;R/O
infection/abscess; assess orbital tumor; R/O lacrimal gland pathology; optic atrophy…. 60 cc
of contrast is given prior to the coronal scans, and the other 60 cc is given prior to the axial
scan.
 kVp / Effective mAs / Rotation time (sec) 120 / 170 / 0.75
 FOV : 180 mm.
 Thickness : 3mm.
 Resolution : high.
 Bone Window: WC : 200, WW : 2000
 Soft Tissue Window: WC : 50, WW : 350
 Submit images in bone and soft tissue algorithm.
Scan Coverage: Mid
maxillary sinus to frontal
sinuses.
Coronal reconstructions
Sagittal reconstructions
Orbit CT – Soft Tissue Window (Axial Plane)
Orbit CT – Bone Window (Axial and
Coronal Plane)
Orbit CT – Soft Tissue
Window (Coronal Plane)
Orbit CT – Soft Tissue
Window (Sagittal Plane)
Orbit CT – Bone Window
(Sagittal Plane)
ORBIT CT
(with contrast)
Axial CT scan of a patient with
thyroid eye disease. Several of the
elements of this disease are evident
on this image: 1) exophthalmos or
protrusion of the eye ball from the
orbit, and 2) enlargement of the
extraocular muscles, including the
medial rectus (mr). Also seen are
some less common variations of sinus
anatomy. Specifically, a posterior
Ethmoid cell (EC) has extended into
the sphenoid bone to pneumatize the
area around the optic nerve.
Right orbital blow-out fracture
on CT-scan; coronal reformat
The axial CT scan (right) shows air in
the orbit and a mild proptosis.
Orbital swelling and proptosis from
vigorous sneezing. Air escaped into
the orbit through a "reverse" medial
blow-out fracture of the lamina
papyracea, resulting in orbital
emphysema.
Unilateral subconjunctival fat prolapse.
Precontrast axial CT scan shows the
herniated fat at the superotemporal aspect
of the right epibulbar area (arrow). The
prolapsed fat is continuous with the
intraconal fat and lies between the lateral
wall of the eyeball medially and the
lateral rectus muscle and the lacrimal
gland laterally.
Thank You
BEST WISHES
FOR ALL