Transcript Middle turbinate

Anatomy and relevant
anatomical variants in nasal
and paranasal sinuses CT scan
CERTIFICATE
OF
MERIT
RSNA 2003
P. Loubeyre1 MD & J.S Lacroix2 MD, PhD
1 Radiology Department,
2 Rhinology-Olfactology Unit
Hôpitaux Universitaires de Genève
CH- 1211 Genève 14
Switzerland
Sinusitis – Imaging technique (3-10)
Anatomy
Paranasal sinuses (dia 11-12)
Ostiomeatal unit (dia 13-16)
Uncinate process (dia 17-19)
Ethmoid bulla (dia 20-22)
Middle turbinate (dia 23,24)
Ethmoid infundibulum (dia 25)
Frontal recess (dia 26-28)
Sphenoethmoidal recess (dia 29,30)
Posterior nasal fontanel (dia 31)
Posterior choana (dia 32)
Nasal septum (dia 33)
Nasolacrymal duct (dia 34)
Anterior skull base (dia 35-38)
Anatomic variants
Septal deviation (dia 40)
Septal spurs (dia 41)
Middle turbinate (dia 42-44)
Superior turbinate (dia 45)
Uncinate process (dia 46)
Frontal bulla cell (dia 47)
Frontal sinus extension (dia 48)
Agger nasi cell (dia 49)
Maxillary sinus recesses (dia 50)
Sphenoid sinus recesses (dia 51-53)
Intersinus sphenoid septation (dia 54)
Surgical risks
Vulnerability of the carotid canal (dia 55-57)
Vulnerability of the optic nerve (dia 58-61)
Vulnerability of the orbit (dia 62-65)
Vulnerability of the nasolacrymal duct (dia 66)
Vulnerability of anterior skull base (dia 67)
Some articles to read
Mafee MF. Endoscopic sinus surgery: role of the radiologist. AJNR1991;157:855-60
Earwaker J. Anatomic variants in sinonasal CT. Radiographics 1993;13:381-415
Rao VM, El-Noueam KI. Sinonasal imaging. Radiologic Clinics of North America 1998;36(5):921-39
Zeifer B. Update on sinonasal imaging. Neuroimaging Clinics of North America 1998;8(3):607-30
Mucociliary clearance
impairment
Mucous accumulation
increases the risk of infection or
chronic inflammation
Mucociliary transport : anatomy of the drainage pathway of
the paranasal sinuses
Ostio-meatal
complex
Obstruction
Normal
mucociliary
clearance
or
Normal mucosal
thickening during
nasal cycle
Contact of two opposing
mucosal surfaces
(ex: anatomic variants)
Mucous accumulation
increases risk of infection
Chronic rhinosinusitis unresponsive to
medical management
The aim of nasal and paranasal sinuses imaging is to provide a
surgical road map delineating the anatomy, defining the obstructive
lesions, and noting the anatomical factors that may predispose
impaired mucociliary clearance and per operative complications
CT High spatial resolution
Minute bony details and adjacent soft tissue
structures
Pre-operative investigation for
patients undergoing
endoscopic sinus surgery
Rhinosinusitis is a medical
diagnosis,
not a radiologic diagnosis
Supine position
Confortable position
console
Coronal, sagittal or oblique reformations
1-mm-thick overlapping
axial slices
Real time image-guided anatomic localization
during endoscopic surgery
Medical treatment should be
performed before CT scan
To reduce transient acute inflammatory or
infectious mucosal changes
Nasal lavages
Topical corticosteroids
Antibiotics
Mucolytic agents
CT scan should be
scheduled after
completion of medical
treatment
Contrast-enhanced CT ?
no
.Anatomy is adequately assessed without the use
of IV injected iodinated contrast material
.Iodine injection does not allow for discriminating
an inflammatory disease from a tumoral process
yes
Initial images or clinical symptoms suggest
intracranial complications of a chronic
MRI
inflammatory sinus disease
CT imaging
1. Obstruction of the drainage pathways or anatomic
variants that may compromise already narrow drainage
pathways
2. Identification of critical anatomic areas where anatomic
variants pose special risks during sinus surgery
3. Local extension of disease
4. Complications
1+2 : Preoperative CT scan as a
road map for endoscopic sinus
surgery
Coronal CT
Maxillary sinuses
Ethmoid sinus
Nasal cavity
Sagittal CT
Frontal sinuses
Ethmoid sinus
Sphenoid sinus
Nasal cavity
Ostio-meatal unit
Coronal CT
Sagittal CT
Middle nasal meatus
(air channel medial to uncinate process
and lateral to the middle turbinate)
Ostio-méatal unit
Drainage from frontal, maxillary
and anterior ethmoid sinuses
Obstruction
Frontal sinusitis
Maxillary sinusitis
Anterior ethmoid sinusitis
Sagittal view
Ostio-meatal unit
Coronal CT
Ethmoid
bulla (EB)
Orbit
EB
Middle
turbinate
Middle
meatus
Uncinate
process
Axial CT
Ostio-meatal unit
Maxillary ostium
Ethmoid infundibulum (posterior)
Hiatus semilunaris
Middle meatus
Coronal CT
Uncinate process
Thin-curved bony lamina of variable height from the lateral side of the
ethmoid labyrinth, that forms a portion of the lateral nasal wall.
Coronal CT
Lamina
papyracea
EB
Inferior attachment to the
neck of the inferior turbinate
Supero-anterior
attachment to lamina
papyracea in 50%
Uncinate process
Coronal CT
Sagittal CT
Postero-lateral attachment to the roof of the maxillary sinus
Uncinate process
Sagittal CT
Anterior-most ethmoid cell:
agger nasi cell
EB
Lacrymal bone
Anterior attachment
of the uncinate process
Coronal CT
Ethmoid bulla (EB)
Most posterior of all anterior ethmoid air cells, roof of the
hiatus semilunaris and posterior ethmoid infundibulum
Sagittal CT
Coronal CT
EB
Anterior ethmoid drainage
Middle meatus
Anterior ethmoid cells can drain into the middle meatus via the ethmoid bulla
Ethmoid bulla
Orbit
EB
Uncinate
process
Normal-sized bullae
Large bullae
Hypoplasic bullae
Acording to John Earwaker. Anatomic variants in sinonasal CT.Radiographics 1993;13:381-415
Coronal CT
Different
ethmoid
bullae
Middle turbinate
Coronal CT
Coronal CT
Posterior
ethmoid
cell
EB
Bulb
It attaches superiorly to the
cribriform plate:
It attaches posteriorly and
laterally to the lamina papyracea:
Medial lamella
Basal (ground) lamella
Coronal CT
Middle turbinate
Sagittal CT
Anterior
ethmoid
EB
Posterior
ethmoid
Anterior
ethmoid
air cells
Posterior
ethmoid
air cells
Basal lamella
Ethmoid infundibulum
Anterior ethmoid cells drainage
Frontal sinus drainage (25%)
Anterior ethmoid cells can directly drain into middle meatus
Coronal CT
Frontal recess
Communication between frontal sinus and nasal cavity.
It is not strictly a duct but a channel located between
anterior ethmoid cells. Variety of configurations.
Sagittal CT
Frontal
sinus
Coronal CT
Frontal ostium
Agger nasi cell
Anterior middle meatus
Coronal CT
50%
Frontal sinus drainage pathways
according to supero-anterior attachment
of the uncinate plate
Attachment to the lamina papyracea
Frontal drainage in the medial meatus
25%
Attachment to the skull base
Frontal drainage into the ethmoid infundibulum
25%
Attachment to the neck of the middle turbinate
Frontal drainage into the ethmoid infundibulum
or into an anterior ethmoid cell
Frontal sinus outflow obstruction
Frontal sinusitis
Sagittal view
Sphenoethmoidal recess
Posterior ethmoid and sphenoid sinus drainages
Axial CT
Sagittal CT
Sphenoid
sinus
Sphenoid sinus
ostium
Superior nasal meatus
Sphenoethmoidal recess obstruction
Posterior ethmoid sinusitis
Sphenoid sinus sinusitis
Posterior nasal fontanel
Coronal CT
coronal
Axial CT
Area of the lateral wall of the nose immediately behind the posterior
attachment of the uncinate plate. Consists of mucous membrane only,
without bony support.
Accessory maxillary ostium is frequently found through the
posterior nasal fontanel (15-40%)
Posterior choana
Sagittal CT
Nasopharynx
Coronal CT
Nasal septum
Coronal CT
Sagittal view
post
Perpendicular plate
of the ethmoid
vomer
ant
Septal
cartilage
Chondrovomeral
junction
Nasolacrymal duct
Axial CT
3
1
2
4
Coronal
CT
Inferior
meatus
Anterior skull base
Coronal CT
Axial CT
Crista galli
Cribriform plates (floor of the olfactive fossa)
Ethmoid roof (fovea ethmoidalis)
Ethmoid roof
Axial CT
Sagittal CT
Lateral lamella
(point of structural weakness in
the anterior skull base)
Coronal CT
Point of structural
weakness during
turbinectomy
Ethmoid roof
Cribriform plate
Medial
lamella
Middle
turbinate
1-16 mm length
Dehiscent in 15% of specimens
Anterior ethmoidal artery
Anterior ethmoidal artery
Coronal CT
Coronal CT
Olfactory
fossa
Lateral lamella
Medial lamella of
Middle turbinate
The anterior ethmoidal artery - branch of the ophtalmic artery - exits the
orbit through the anterior ethmoidal foramen and enters the olfactory
fossa at the point of attachment of the middle turbinate to the cribriform
plate
Anatomic variants
Very frequently noted
The presence of anatomic variants, singly or in
combination, does not represent a disease state per se
Equal prevalence of patients with and without sinus
disease in the presence of the same anatomic variant
Septal deviation
Coronal CT
Coronal CT
Hypoplasic Large
middle
middle
turbinate turbinate
Middle meatus
Inferior meatus
Septal spurs
Axial CT
Coronal CT
Coronal CT
Bridging spur
Frequently encountered at the junction of the perpendicular
plate of the ethmoid and the vomer
May impige on and invaginate the middle or inferior turbinates. When the
turbinate mucosa swells with the normal nasal cycle or inflammation, it is
impaled on the spur, setting up a cycle of facial pain or headache. A septal
spur occasionally produces a complete bridge.
Size variations of middle turbinate
Coronal CT
Coronal CT
Ostio-méatal complex compromise?
Turbinate septal contact when the turbinate mucosa
swells with the normal nasal cycle or inflammation
Pneumatized middle turbinate
Axial CT
Coronal CT
Air cell in the vertical lamella:
concha neck air cell
Air cell in the bulbous segment:
concha bullosa cell
Paradoxical middle turbinate
Coronal CT
Usually
Paradoxical turbinate
Convex configuration medially
Concave configuration medially
Concave configuration laterally
Convexe configuration laterally
Pneumatized superior turbinate
Coronal CT
A cause of migraine headache?
Enlargement of the superior turbinate due to pneumatization,
with accompanying mucosal contact, acts as a mechanical
stimulus initiating an axon reflex with resultant referred pain?
Uncinate process
Height : 1-4 mm
Length : 14-22 mm
Coronal CT
Coronal CT
Medially rotated uncinate
Pneumatized
Frontal bulla cell (suprabullar cell)
Anterior ethmoid air cell extending upwards (intramural ethmoid
air cell)
sagittal
axial
coronal
Frontal recess
May be small and impiges only on the floor of the frontal sinus.
May elevate and narrows the frontal recess
May be prominent and bulges into the frontal sinus
Frontal sinus extension
Pneumatization of the orbital plate of the frontal bone
ant
post
Coronal CT
Frontal sinus
No frontal sinus drainage compromise
Agger nasi (AN) cell
Coronal CT
Sagittal CT
Lacrymal
fossa
AN
Frontal recess
The most anterior of the ethmoid cells. Forms the floor of the frontal
recess. It reaches the lacrimal fossa inferiolaterally, and is
anterolaterally arched by the nasal bone. A large agger nasi can impige on
and distort the frontal recess.
Its posterior-medial wall usually gives rise to the anterior uncinate process
Maxillary sinus recesses
Coronal CT
Palatine recess
Axial CT
Infraorbital recess of
The maxillary sinus
Coronal CT
Sagittal CT
Alveolar recesses
(roots of the premolar
and molar teeth)
Axial CT
Zygomatic recess
Sphenoid sinus recesses
Sagittal view
Coronal anterior view
ant
post
Sphenoid sinus
Temporal
bone
Orbital
wall
Maxillary
bone
Rostrum
Septum, vomer
Sup or inf clivus
Lesser wing
Greater wing
Pterygoid process
Sphenoid
sinus
Sphenoid sinus recesses
Sagittal CT
Septal recess
Sagittal CT
Inferior clival recess
Sphenoid sinus recesses
Coronal CT
Lesser wing
Greater wing
Ptérygoid process
Anterior clinoid process
Foramen rotundum
(maxillairy nerve)
Optic nerve
Coronal CT
Intersinus septation of sphenoid
Axial CT
Coronal CT
Presellar segment of the internal carotid artery
Vulnerability of the carotid canal
Internal carotid artery bulges into sphenoid sinus
Axial CT
Axial CT
Sphenoid
sinus
surgery
septum
Vulnerability of the carotid canal
Dehiscent carotid canal
Axial CT
Axial CT
Sphenoid
sinus
surgery
Vulnerability of the carotid canal
Normal
sphenoid
sinus
Axial CT
Hypoplasia or aplasia
of the sphenoid sinus
Carotid canal impiges on or bulges into
posterior ethmoid
Posterior
ethmoid
surgery
Ethmoid
Normal
sphenoid
sinus
ETHMOIDE
POST
Vulnerability of the optic nerve
1 Onodi cell (bulging of the optic canal into the posterior ethmoid)
2 Pneumatization of the lesser wing of the sphenoid bone
3 Pneumatization of the anterior clinoid process of the sphenoid bone
Coronal CT
Sagittal CT
2
Coronal CT
1
Posterior
ethmoid
surgery
Optic nerves
Sphenoid
sinus
surgery
Sphenoid
sinus
surgery
Encasement of the optic nerve
Within the sphenoid sinus
3
Vulnerability of the optic nerve
Onodi cell
Sagittal CT
Axial CT
Sinus
sphénoide
Posterior
ethmoid
surgery
Coronal CT
Posterior ethmoid cell, with prominent superior or lateral
pneumatization to the sphenoid sinus, and a bulge of the optic
canal into it.
Vulnerability of the optic nerve
Axial CT
Sphenoid
sinus
surgery
1
2
Coronal CT
1. Bulging of the optic nerve
into the sphenoid sinus
2. Dehiscent optic canal
Sphenoid
sinus
surgery
2
Vulnerability of the optic nerve
Hypoplasia or aplasia of the sphenoid sinus
(Optic nerves impinge on or bulge into the posterior ethmoid)
Posterior
ethmoid
surgery
Post
ethmoid
Normal-sized
sphenoid sinus
mt
mt
Sagittal view
mt: middle turbinate
Optic nerve
mt
Vulnerability of the orbit
Haller cells
Coronal CT
Anterior
ethmoid
endoscopy
Anterior ethmoid air cells that extend along
the medial floor of the orbit
Vulnerability of the orbit
Coronal CT
Axial CT
orbite
orbit
Uncinectomy
Uncinate process is very close to infero-medial orbit wall.
They can be merged.
Vulnerability of the orbit
Lamina papyracea localized medial to
the maxillary sinus ostium
Coronal CT
Coronal CT
orbit
Fusion of the uncinate process to the
medial orbital wall
(Ex :maxillary sinus hypoplasia;reduced
ethmoid transverse diameter;children)
(usually associated with ipsilateral hypoplastic
maxillary sinus)
Vulnerability of the orbit
Coronal CT
Axial CT
Axial CT
Anterior
ethmoid
endoscopy
coronal
Dehiscent lamina
papyracea
Thin medial orbital wall
(lamina papyracea)
Dehiscent lamina
papyracea
Vulnerability of the nasolacrymal duct
Agger nasi cell can invade the lacrymal bone
and impinge on or encircle the nasolacrymal duct
Coronal CT
Anterior
ethmoid
endoscopy
Axial CT
Vulnerability of the anterior skull base
Low cribriform plate: below the upper third of the vertical
orbital plate
Coronal CT
orbit
Usually associated with
hypoplastic middle
turbinate(s)
Risk of penetration into the
anterior cranial fossa during
ethmoid endoscopic surgery