Ebook Diagnostic imaging head and neck (2nd edition): Part 2

Diagnostic Imaging Head and Neck

Part IV - Sinonasal Cavities and Orbit
Section 1 - Nose and Sinus
Introduction and Overview
Sinonasal Overview
> Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section 1 - Nose and Sinus > Introduction and Overview >
Sinonasal Overview
Sinonasal Overview
Michelle A. Michel, MD
Summary Thoughts: Sinus and Nose
The anatomy of the sinonasal (SN) cavities is as unique as a person's fingerprints. The nasal cavity (NC) is centrally
located and is surrounded by the paranasal sinuses (PS). Because the SN region is comprised of air-filled spaces and
complex bony architecture, CT is often the first-line imaging modality. CT is used for determining the extent of disease
and is also helpful for surgical planning and intraoperative guidance. As in all regions of the H&N, information, such as
patient demographics, presenting symptoms, and clinical exam findings, are critical for interpreting imaging studies of
this area.
It is important to understand the drainage pathways of the PS as one can then predict patterns of disease based upon
the point of an obstructing lesion. Inflammatory disease is by far the most common pathology. However, isolated
inflammatory disease of the sphenoid sinus is unusual and should raise suspicion for other pathologies including
neoplasm or cephaloceles, particularly if there is an associated bone defect. Fortunately, malignancies of the SN
cavities are rare. They tend to present at an advanced stage and are often in close proximity to vital structures (orbit,
cranial nerves, and skull base). These tumors are difficult to completely resect and are associated with high surgical
morbidity. Presurgical tumor mapping in such cases is best accomplished with multiplanar MR.
Imaging Approaches and Indications
CT is the modality of choice for evaluation of inflammatory disease. CT is more sensitive for detecting Ca++ in lesions
(fibro-osseous lesions, inverted papilloma, esthesioneuroblastoma) and for evaluating changes in adjacent bone.
Coronal images best demonstrate the anatomy of the ostiomeatal unit (OMU). MR can be used as a complement to CT
for evaluating complicated inflammatory or neoplastic disease.
MR is generally indicated for evaluation of complex inflammatory disease and neoplasms. It is optimal for assessing
extension beyond the SN cavities, evaluating perineural tumor spread, and differentiating tumor from postobstructed

secretions.
Imaging Protocols
Traditionally, ≤ 3 mm direct coronal images are obtained prone and angled perpendicular to the palate. With
multidetector CT, coronal reformatted images can be generated from a thin slice axial data set acquired in the supine
position. This is advantageous as images are less degraded by motion artifact and dental amalgam can be avoided.
Axial images can often be used in image-guidance systems, obviating additional radiation for “treatment planning” CT
prior to surgery. Sagittal reformatted images are helpful for delineating frontal recess (FR) and the sphenoethmoid
region anatomy.
MR imaging protocols generally include axial and coronal T1, STIR, and T1WI C+ images with fat suppression.
Angiography is rarely needed for diagnostic purposes but may be performed for intervention prior to resection of
vascular neoplasms.
Imaging Anatomy
The sinonasal region is comprised of the NC and the surrounding PS. There are important anatomic relationships with
surrounding compartments of the extracranial head and neck, including the anterior cranial fossa, orbits,
pterygopalatine and infratemporal fossae, and oral cavity.
The SN cavities extend into the maxillary, frontal, sphenoid, and ethmoid bones. Superiorly, the frontal sinuses border
the anterior margin of the anterior cranial fossa. The cribriform plate (CP) and fovea ethmoidalis form the borders
between the superior NC and ethmoid, respectively. The hard palate separates the NC from the oral cavity. The NC
communicates posteriorly with the nasopharynx via the choanae. The orbits are separated from the ethmoid sinuses
by the thin lamina papyracea and are separated from the maxillary sinuses by the orbital floors. Posterior to the
maxillary sinuses are the pterygopalatine fossae, which communicate superiorly with the orbital apices & laterally
with masticator space.
The NC is centrally located and is divided in the midline by the nasal septum. The bony septum is formed from the
perpendicular plate of the ethmoid posterosuperiorly and vomer bone posteroinferiorly. Anteriorly the septum is
comprised of cartilage. Paired superior, middle, and inferior turbinates project into the NC and their corresponding
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Diagnostic Imaging Head and Neck
meati exit inferior to each. The middle turbinate has two attachments: 1) superiorly to the CP via the vertical lamella,

and 2) posterolaterally to the lamina papyracea via the basal (ground) lamella.
The frontal sinuses are often asymmetric in size and are divided in the midline by an intersinus septum.
Inferomedially, the frontal sinus narrows toward its ostium, which drains into its FR. The FR is formed by the walls of
surrounding structures. The drainage of the FR is determined by the insertion of the uncinate process. Most often the
uncinate inserts laterally onto the lamina papyracea and secretions drain into the middle meatus (MM). Less
frequently, the uncinate inserts onto the anterior skull base or middle turbinate; FR secretions drain via the
infundibulum into the MM.
Paired groups of 13-18 air cells form the ethmoid labyrinths. These cells are divided into anterior and posterior groups
by the basal lamella. The anterior air cells drain into the anterior recess of the hiatus semilunaris and middle meatus
via the ethmoid bulla. The posterior air cells drain into the superior meatus and sphenoethmoidal recess (SER).
The maxillary sinuses lie lateral to the NC and inferior to the orbits. Each drains via its maxillary ostium into the
infundibulum, then via the hiatus semilunaris into the MM. The maxillary sinuses have lateral recesses and alveolar
recesses inferiorly.
The sphenoid sinuses are asymmetric air cells in the body of the sphenoid bone. Important surrounding structures
include the maxillary division of CN5 in foramen rotundum laterally, the vidian nerve and artery in the vidian canal
inferiorly, the optic nerves and sella superiorly, and the cavernous sinuses laterally. The sphenoid sinuses drain via
their ostia into the SER.
The OMU is a critical crossroads for drainage of the sinuses most affected by inflammatory disease (anterior ethmoid,
maxillary, and frontal). Important components of the OMU include the ethmoid infundibulum, uncinate process,
hiatus semilunaris, ethmoid bulla, and MM.
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Approaches to Imaging Issues of the Sinus and Nose
Congenital lesions can be classified as those presenting with nasal obstruction vs. nasal mass. Lesions presenting with
nasal obstruction and no mass include pyriform aperture stenosis and choanal atresia. Frontonasal cephaloceles,
dermoids, and extranasal gliomas present as extranasal masses. Frontoethmoidal cephaloceles, intranasal gliomas,
and nasolacrimal duct mucoceles present with an intranasal mass. MR imaging can be very helpful for evaluating if
there is a connection to the intracranial space.
Rhinosinusitis (RS) is the most common pathology of the SN region. Acute RS is usually diagnosed clinically & does not
require imaging. Always look for an odontogenic source of sinusitis if isolated maxillary sinus disease is identified.

Because of the anatomy of the PS drainage pathways, predictable patterns of inflammatory disease exist based upon
the point of obstruction. For example, obstruction of the MM would lead to disease in the ipsilateral frontal, anterior
ethmoid, & maxillary sinuses. SER obstruction might lead to ipsilateral posterior ethmoid & sphenoid disease.
Although uncommon, there are several forms of SN fungal disease. Mycetoma and allergic fungal sinusitis occur in
immunocompetent patients and invasive fungal sinusitis (IFS) occurs in the immunocompromised or poorly controlled
diabetics. It is important to note that IFS may appear mass-like at imaging. Granulomatous disease has a predilection
for involving the nasal septum and turbinates.
There are a wide variety of neoplasms of the SN cavities. Imaging features that favor a benignity include bone
remodeling and well-defined margins vs. bone destruction and infiltrative margins. The site of origin may also be
suggestive of histology. For instance, osteomas most often arise in the frontal and ethmoid sinuses, juvenile
angiofibromas (JAF) arise in the posterior NC at the sphenopalatine foramen, inverted papillomas often arise along the
lateral nasal wall, and esthesioneuroblastoma (ENB) typically arises near the CP. Squamous cell carcinoma is by far the
most common SN malignancy and most often arises in the maxillary antrum. The imaging features of
adenocarcinomas can be nonspecific, but they have a predilection for the ethmoid region. Three malignant neoplasms
with a predilection for the NC include ENB, lymphoma, and melanoma.
Clinical Implications
The anatomy of the SN cavities is complex and highly variable. Technical advances, such as image guidance systems,
have helped surgeons, particularly in the frontal & sphenoid sinuses. It is important to note that studies have shown a
poor correlation between symptoms of RS and CT findings. The diagnosis of RS is a clinical one!
Disease of the SN cavities often presents with nonspecific symptoms, such as nasal obstruction & discharge.
Additional symptoms, such as epistaxis, may be indicative of a vascular lesion (JAF or ENB). Pain may also be caused by
mucoceles or neoplasms, while paresthesias can be linked to malignancies such as adenoid cystic carcinoma. Clinically,
lesions located within the NC can be evaluated with endoscopy. Lesions involving the sinuses are difficult to evaluate
with scopes, so imaging is essential for characterization & determination of disease extent.
Selected References
1. Beale TJ et al: Imaging of the paranasal sinuses and nasal cavity: normal anatomy and clinically relevant anatomical
variants. Semin Ultrasound CT MR. 30(1):2-16, 2009
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2. Raghavan P et al: Magnetic resonance imaging of sinonasal malignancies. Top Magn Reson Imaging. 18(4):259-67,
2007
3. Aygun N et al: Imaging for functional endoscopic sinus surgery. Otolaryngol Clin North Am. 39(3):403-16, vii, 2006
Tables

Differential Diagnosis of Sinonasal Lesion
Congenital
Benign tumors & tumor-like
lesions
Nasolacrimal duct mucocele Fibrous dysplasia
Choanal atresia
Osteoma
Nasal glioma
Ossifying fibroma
Nasal dermal sinus
Juvenile angiofibroma
Frontoethmoidal
Inverted papilloma
cephalocele
Pyriform aperture stenosis Hemangioma
Infectious & inflammatory Nerve sheath tumor
Acute rhinosinusitis
Benign mixed tumor
Chronic rhinosinusitis
Malignant tumors
Complications of
Squamous cell carcinoma
rhinosinusitis
Allergic fungal sinusitis

Esthesioneuroblastoma
Mycetoma
Invasive fungal sinusitis
Sinonasal polyposis
Solitary sinonasal polyp
Mucocele
Silent sinus syndrome
Wegener granulomatosis
Sarcoidosis
Nasal cocaine necrosis

Anatomic variations
Sinus hypo- or
hyperpneumatization
Nasal septal deviation & spurs
Frontal cells (types I-IV)
Ethmoid region
Agger nasi cell
Infraorbital (Haller) cell
Supraorbital ethmoid cell
Large ethmoid bulla
Sphenoethmoidal (Onodi) cell
Asymmetric fovea ethmoidalis

Medial or dehiscent lamina
papyracea
Adenocarcinoma
Middle turbinate
Melanoma
Concha bullosa

Non-Hodgkin lymphoma
Paradoxical curvature
Sinonasal undifferentiated sarcoma Hypoplasia
Adenoid cystic carcinoma
Uncinate process
Chondrosarcoma
Pneumatized
Osteosarcoma
Deviated
Rhabdomyosarcoma
Fusion to middle turbinate or skull
base
Metastasis
Atelectatic (approximates orbital
floor)

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Image Gallery

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(Top) Sagittal graphic demonstrates the osseous anatomy of the lateral nasal wall. The superior turbinate & portions
of the middle & inferior turbinates have been resected. The superior, middle, & inferior meati drain inferior to their
respective turbinates. The ipsilateral frontal, anterior ethmoid, & maxillary sinuses ultimately drain into the middle
meatus. The nasolacrimal duct drains into the inferior meatus. The sphenoid ostium is located along the anterior
sphenoid sinus wall & drains into the SER. (Bottom) Coronal graphic of magnified right sinonasal region shows the

important structures around the ostiomeatal unit. The vertically oriented uncinate process is bounded laterally by the
ethmoid infundibulum, superiorly by the hiatus semilunaris, & medially by the middle meatus. The ethmoid bulla is
the dominant anterior ethmoid cell located superior to the uncinate. The middle meatus drains beneath the middle
turbinate.
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(Top) Sagittal graphic shows the frontal sinus drainage pathway. The frontal sinus narrows inferiorly to its ostium.
Secretions drain through the ostium into the frontal recess (FR). The FR is not a true duct in that its walls are
comprised of adjacent anatomy. In the graphic, the FR is bounded anteriorly by an agger nasi cell & posteriorly by the
ethmoid bulla. Note that FR drainage may vary based upon the point of insertion of the uncinate process. (Bottom)
Coronal graphic shows the important anatomy surrounding the sphenoid sinuses. The cavernous portions of the
internal carotid arteries lie lateral & posterior to the sinuses. At the orbital apex, the optic nerve can be seen
traversing the optic canal. Multiple cranial nerves pass through the superior orbital fissure into the orbit including CNs
3, 4, & 6 as well as the ophthalmic division on CN5. The maxillary division of CN5 in foramen rotundum & the vidian
nerve are positioned lateral & inferior to the sinus, respectively.
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Image Gallery

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(Left) Coronal bone CT shows the paired frontal sinuses

separated by the intersinus septum
. The most
anterior ethmoid-type cells, the agger nasi, can be seen
. Notice the air-filled lacrimal sac on the left
. (Right)
Coronal bone CT shows the medial
& lateral
lamellae of the cribriform plate forming the roof of the nasal
cavity. The fovea ethmoidalis
forms the ethmoid sinus roof. Note the patent frontal recesses
leading to the
middle meati.

(Left) Sagittal CT reconstruction shows the frontal sinus drainage pathway. The sinus
drains inferiorly into the
frontal recess
. A frontal cell
is anterior to the recess & the ethmoid bulla is posterior
. Note the middle
& inferior
turbinates. (Right) Axial T1WI MR shows the paired maxillary sinuses
lateral to the nasal cavity.
Note the inferior turbinates
, midline nasal septum
, & air-filled nasolacrimal ducts
above the inferior
meati.

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Diagnostic Imaging Head and Neck

(Left) Sagittal CT reconstruction shows the nasolacrimal duct
draining into the inferior meatus
. Note the
pterygopalatine fossa posterior to the maxillary sinus
. (Right) Coronal bone CT at the level of the ostiomeatal
units shows the uncinate processes
, ethmoid bullae
, & middle turbinates
. They are pneumatized as is
the right inferior turbinate. The middle meatus lies between the uncinate & middle turbinate. A retention cyst blocks
the left maxillary ostium.
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(Left) Sagittal CT reconstruction shows anterior
& posterior
ethmoid cells and the sphenoid sinus
. The
lateral attachment of the middle turbinate (basal lamella) is seen
. Note the hiatus semilunaris
. The palate is
noted inferiorly
. (Right) Axial bone CT shows the thin lamina papyracea
separating the ethmoid air cells from
the orbits. The sphenoid sinuses
are separated by an intersinus septum. Note internal carotid arteries
adjacent to the sinuses.

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Diagnostic Imaging Head and Neck

(Left) Sagittal CT reconstruction shows the sphenoethmoidal recess
bounded anteriorly by the most posterior
ethmoid air cell
& posteriorly by the sphenoid sinus
. A retention cyst is seen in the sphenoid sinus
.
(Right) Coronal bone CT shows the sphenopalatine foramen
connecting the nasal cavity to the pterygopalatine
fossa (PPF)
. The inferior orbital fissure
extends from the PPF to the orbital apex. Note the planum
sphenoidale above the sphenoid sinuses
.

(Left) Sagittal CT reconstruction shows the sphenoid sinus ostium
along the anterior wall of the sphenoid sinus.
An agger nasi cell
& the basal lamella
are also seen. (Right) Coronal bone CT shows the important structures
around the sphenoid sinuses. The vidian canals
are noted along the sinus floors & the foramen rotundum
is
located laterally. The optic nerves lie medial to the anterior clinoids
& the cavernous sinuses lie laterally
.

Congenital Lesions
Nasolacrimal Duct Mucocele
> Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section 1 - Nose and Sinus > Congenital Lesions >
Nasolacrimal Duct Mucocele
Nasolacrimal Duct Mucocele
Michelle A. Michel, MD
Key Facts
Terminology
Synonym: Congenital dacryocystocele
Imaging
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Diagnostic Imaging Head and Neck
Well-defined, cystic, unilateral or bilateral medial canthal mass in contiguity with enlarged bony NLD in newborn
Absent or minimal wall enhancement (unless infected)
Coronal/sagittal reformatted images show contiguity of cyst at lacrimal sac with NLD and inferior meatus
Top Differential Diagnoses
Orbital dermoid and epidermoid
Dacryocystocele, acquired
Pathology
Tears & mucus accumulate in nasolacrimal duct with imperforate Hasner membrane (distal duct obstruction)
Clinical Issues
Proximal lesion: Small, round, bluish, medial canthal mass identified at birth or shortly thereafter
Distal lesion: Nasal airway obstruction with respiratory distress if bilateral
Most common abnormality of infant lacrimal apparatus
Diagnostic Checklist
Cross-sectional imaging evaluates extent of lesion along lacrimal apparatus & excludes other sinonasal causes of
respiratory distress in newborn

(Left) Axial bone CT in an infant shows well-circumscribed, low-density masses at the levels of the inferior meatus
bilaterally
consistent with nasolacrimal duct mucoceles. Note the position of the lesions relative to the inferior
turbinates
. (Right) Coronal T2WI MR in the same patient shows hyperintense signal in the mucoceles, not only at
the inferior nasolacrimal ducts
, but also at the level of the lacrimal sacs
.

(Left) Axial CECT in an infant demonstrates a cystic mass
with an enhancing rim in the medial right orbit consistent
with a mucocele. There is associated enlarged lacrimal sac fossa
. Note the normal left lacrimal sac fossa
.
(Right) Axial CECT in the same patient shows extension of the mucocele inferiorly to the level of the inferior meatus
. The lesion obstructs the right nasal cavity at that level.
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TERMINOLOGY
Abbreviations
Nasolacrimal duct (NLD) mucocele
Synonyms
Congenital dacryocystocele
Definitions
Cystic dilatation of nasolacrimal apparatus secondary to proximal ± distal obstruction of NLD

IMAGING
General Features
Best diagnostic clue
Well-defined, cystic, unilateral or bilateral medial canthal mass in contiguity with enlarged bony NLD in
newborn
Location
Anywhere from lacrimal sac to inferior aspect of NLD at inferior meatus
Size
Variable; 5-10 mm intranasal or medial orbital component
CT Findings
NECT
Hypodense, thin-walled cyst medial canthus ± inferior meatus
Cyst(s) communicate with enlarged NLD
CECT
Minimal wall enhancement (unless infected)
MR Findings
T1WI
Hypointense, well-circumscribed mass at medial canthus ± inferior meatus
T2WI
Typically hyperintense due to fluid content
T1WI C+
No or minimal wall enhancement around cyst
Imaging Recommendations
Best imaging tool
Thin section axial bone CT
Fast & ↓ need for sedation
Rules out choanal atresia as cause of airway obstruction
Protocol advice
Coronal/sagittal reformats show contiguity of lacrimal sac cyst with large NLD in nasolacrimal canal &
extension into inferior meatus

DIFFERENTIAL DIAGNOSIS
Orbital Dermoid and Epidermoid
Lateral > medial canthus
50% fat density/intensity with thin rim enhancement ± calcification
Dacryocystocele
Acquired lacrimal sac cyst
PATHOLOGY
General Features
Etiology
Tears & mucus accumulate in nasolacrimal duct with imperforate Hasner membrane (distal duct
obstruction)
Nasolacrimal sac distension vs. anatomic variation compresses proximal valve
CLINICAL ISSUES
Presentation
Most common signs/symptoms
Principal presentation (proximal lesion)
Small, round, bluish, medial canthal mass identified at birth or shortly thereafter
Principal presentation (distal lesion)
Nasal airway obstruction with respiratory distress if bilateral
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Diagnostic Imaging Head and Neck
Submucosal nasal cavity mass at inferior meatus
Other signs/symptoms
Tearing, crusting at medial canthus
Preseptal cellulitis
Clinical profile
Infant with medial canthal mass ± nasal cavity mass
Demographics

Age
Infancy; 4 days to 10 weeks typically
Gender
M < F = 1:3
Epidemiology
Most common abnormality of infant lacrimal apparatus
3rd most common etiology in neonatal nasal obstruction
1st = mucosal edema, 2nd = choanal atresia
Unilateral > bilateral
Natural History & Prognosis
90% simple distal obstructions (congenital dacryostenosis) resolve spontaneously by age 1
Intervention recommended before infection occurs to prevent nasal airway obstruction, dacryocystitis, &
permanent sequelae
DIAGNOSTIC CHECKLIST
Consider
Cross-sectional imaging evaluates extent of lesion along lacrimal apparatus & excludes other sinonasal causes of
respiratory distress in newborn
SELECTED REFERENCES
1. Cavazza S et al: Congenital dacryocystocele: diagnosis and treatment. Acta Otorhinolaryngol Ital. 28(6):298-301,
2008
2. Wong RK et al: Presentation and management of congenital dacryocystocele. Pediatrics. 122(5):e1108-12, 2008
3. Rand PK et al: Congenital nasolacrimal mucoceles: CT evaluation. Radiology. 173(3):691-4, 1989

Choanal Atresia
> Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section 1 - Nose and Sinus > Congenital Lesions > Choanal
Atresia
Choanal Atresia
Michelle A. Michel, MD
Key Facts
Terminology

Congenital obstruction of posterior nasal apertures
Imaging
Unilateral or bilateral narrowing of posterior nasal cavity with membranous or osseous obstruction of choana
Thickening of vomer
Medial bowing of posterior maxilla
Top Differential Diagnoses
Choanal stenosis
Pyriform aperture stenosis
Nasolacrimal duct mucocele
Nasal foreign body
Pathology
Unilateral CAt 1.6-2x as common as bilateral
Bony-osseous (85-90%)
Membranous (10-15%)
Clinical Issues
Bilateral CAt: Respiratory distress in newborn
Unilateral CAt or stenosis: Chronic, purulent unilateral rhinorrhea with mild breathing obstruction
Most common congenital abnormality of nasal cavity
Isolated finding (25%)
Associated with other anomalies (75%)
Diagnostic Checklist
Respiratory distress & nasal obstruction in newborn should be evaluated with thin section bone CT
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Diagnostic Imaging Head and Neck

(Left) Axial bone CT in a newborn with unilateral choanal atresia on the left. There is a membranous atresia
and
fluid layers

in the left nasal cavity. Note the associated thickening of the vomer
posteriorly. (Right) Axial bone
CT in an infant in respiratory distress with bilateral membranous choanal atresia. Note the soft tissue and fluid in the
nasal cavities
and the medialization of the maxillae (lateral nasal walls) posteriorly
.

(Left) Axial NECT shows typical findings of unilateral choanal atresia. There is soft tissue within the left nasal cavity
with apparent narrowing of the left choana
. The contralateral nasal cavity is unremarkable. (Right) Axial bone
CT in the same patient shows the bony stenosis
of the left choanal opening to better advantage. The narrow
opening is occluded by a membranous plug of tissue.
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TERMINOLOGY
Abbreviations
Choanal atresia (CAt)
Definitions
Congenital obstruction of posterior nasal apertures
IMAGING
General Features
Best diagnostic clue
Unilateral or bilateral narrowing of posterior nasal cavity with membranous or osseous obstruction of
choana
Location
Choanal openings: Posterior nasal cavity & nasopharyngeal junction
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Size
Choanal opening in newborn < 0.34 cm; vomer > 0.23 cm
Morphology
Medial bowing of posterior maxilla (lateral nasal walls)
Thickened vomer
Bone ± soft tissue membrane/plug obstructs choana
CT Findings
Bone CT
Bony plate or soft tissue occludes choanal opening(s)
Soft tissue in membranous atresia may be thin/strand-like or thick/plug-like
Thickening of vomer, which may be fused to maxilla
Medial bowing of posterior maxilla
Nasal cavity filled with air, soft tissue, fluid, hypertrophied inferior turbinates
Imaging Recommendations
Best imaging tool
High-resolution unenhanced bone CT
Protocol advice
Suction secretions from nasal cavity prior to scanning
Perform supine with gantry angled 5° cephalad to palate
High-resolution, edge enhancement bone filters helpful in delineating bone margins in partially ossified
skull base
Multiplanar reformations as needed
Sagittal usually best plane for this
3D reconstructions may be helpful for clinical decision making & surgical planning
DIFFERENTIAL DIAGNOSIS
Choanal Stenosis
More common than true CAt
Part of spectrum of “choanal dysplasia” from stenosis to atresia
Axial bone CT appearance

Posterior nasal airway narrowed but not completely occluded
Pyriform Aperture Stenosis
Narrowed anterior nasal passage
Axial bone CT appearance
Narrowing of anterior & inferior nasal passage
Thickened anteromedial maxilla
Anterior nasal septum may be thinned
Single central megaincisor may be present
Brain evaluation for holoprosencephaly important
Nasolacrimal Duct Mucocele
Bilobed cystic masses in both nasolacrimal fossae & inferior meati
Nasal Foreign Body
Older patient with choanal stenosis or unilateral CAt
PATHOLOGY
General Features
Etiology
Pathogenesis remains elusive and unproven
Failure of perforation of oronasal membrane (normally perforates by 7th week of gestation)
Bony CAt: Incomplete canalization of choanae
Membranous CAt: Incomplete resorption of epithelial plugs
Molecular mechanisms in retinoic acid receptor development recently described in CAt
pathogenesis
Genetics
Chromosomal abnormalities, single gene defects, deformations, and teratogens implicated
Associated with chromosome 18, 12, 22, XO abnormalities
Familial form exists
Associated abnormalities
Syndromic associations
CHARGE syndrome

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Diagnostic Imaging Head and Neck
Coloboma, Heart defect, Choanal atresia, Retarded growth and development,
Genitourinary abnormalities, Ear defects
Choanal atresia in 100% of patients with CHARGE
Acrocephalosyndactyly
Amniotic band syndrome
Apert syndrome
Craniosynostosis
Gut malrotations
Crouzon disease
Cornelia de Lange syndrome
Fetal alcohol syndrome
DiGeorge syndrome
Treacher-Collins syndrome
Unilateral CAt 1.6-2x as common as bilateral
Staging, Grading, & Classification
Choanal atresia types
Bony-osseous (85-90%)
Membranous (10-15%)
Gross Pathologic & Surgical Features
Membranous soft tissue or bony plate occludes choanal opening
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CLINICAL ISSUES
Presentation
Most common signs/symptoms
Bilateral choanal atresia: Respiratory distress in newborn

Infants are obligate nasal breathers up to 6 months of age
Aggravated by feeding
Relieved by crying
Unilateral choanal atresia or stenosis: Chronic, purulent unilateral rhinorrhea with mild breathing
obstruction
Other signs/symptoms
Inability to pass nasogastric tube through nasal cavity beyond 3-4 cm despite aerated lungs on plain film
Nasal stuffiness
Grunting, snorting, low-pitched stridor
Clinical profile
Bilateral: Infant with respiratory distress
Unilateral: Child/young adult with unilateral purulent rhinorrhea
Demographics
Age
Bilateral atresia presents at birth
Unilateral choanal atresia/stenosis may present in child/young adult
Gender
Incidence in males and females statistically equal
Epidemiology
CAt or choanal stenosis: Most common congenital abnormality of nasal cavity
1:5,000 to 8,000 live births
CAt in isolation (25%)
Unilateral cases more likely to be isolated
CAt associated with other anomalies (75%)
Bilateral cases more likely associated with specific disorders or multiple anomalies
Natural History & Prognosis
Bilateral CAt
Diagnosed and treated in newborn period
Unilateral CAt
Not life-threatening

May present later in childhood
Prognosis excellent after surgical therapy
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Some patients prone to re-stenosis
Treatment
Establish oral airway immediately to ensure proper breathing
Membranous atresias may be perforated upon passage of NG tube
Surgical treatment believed to be effective for alleviating respiratory symptoms
Best surgical approach, use of endoscopic/laser-assisted techniques, adjuvant use of stents
Use of antiproliferative agents debated
Endoscopic approaches frequently used for simple membranous & bony atresias
Minimizes traumatic injury leading to scarring & restenosis
Bilateral bony atresias require transpalatal resection of vomer with choanal reconstruction
Postoperative scar & incomplete resection of atresia plate best evaluated with bone CT
DIAGNOSTIC CHECKLIST
Consider
Once airway is established, respiratory distress & nasal obstruction in newborn should be evaluated with thin
section bone CT
Image Interpretation Pearls
Determine whether CAt unilateral or bilateral
Look for associated anomalies in head & neck
Reporting Tips
Describe CAt as membranous or bony; unilateral or bilateral
Comment on thickness of bony atresia plate
SELECTED REFERENCES
1. Aslan S et al: Comparison of nasal region dimensions in bilateral choanal atresia patients and normal controls: a
computed tomographic analysis with clinical implications. Int J Pediatr Otorhinolaryngol. 73(2):329-35, 2009

2. Burrow TA et al: Characterization of congenital anomalies in individuals with choanal atresia. Arch Otolaryngol Head
Neck Surg. 135(6):543-7, 2009
3. Corrales CE et al: Choanal atresia: current concepts and controversies. Curr Opin Otolaryngol Head Neck Surg. Epub
ahead of print, 2009
4. Hengerer AS et al: Choanal atresia: embryologic analysis and evolution of treatment, a 30-year experience.
Laryngoscope. 118(5):862-6, 2008
5. Petkovska L et al: CT evaluation of congenital choanal atresia: our experience and review of the literature. Australas
Radiol. 51(3):236-9, 2007
6. Uslu H et al: Bilateral choanal atresia; evaluation with scintigraphy: case report. Int J Pediatr Otorhinolaryngol.
70(1):171-3, 2006
7. Samadi DS et al: Choanal atresia: a twenty-year review of medical comorbidities and surgical outcomes.
Laryngoscope. 113(2):254-8, 2003
8. Shah RK et al: Paranasal sinus development: a radiographic study. Laryngoscope. 113(2):205-9, 2003
9. Triglia JM et al: [Choanal atresia: therapeutic management and results in a series of 58 children] Rev Laryngol Otol
Rhinol (Bord). 124(3):139-43, 2003
10. Holzmann D et al: Unilateral choanal atresia: surgical technique and long-term results. J Laryngol Otol. 116(8):6014, 2002
11. Faust RA et al: Assessment of congenital bony nasal obstruction by 3-dimensional CT volume rendering. Int J
Pediatr Otorhinolaryngol. 61(1):71-5, 2001
12. Vanzieleghem BD et al: Imaging studies in the diagnostic workup of neonatal nasal obstruction. J Comput Assist
Tomogr. 25(4):540-9, 2001
13. Behar PM et al: Paranasal sinus development and choanal atresia. Arch Otolaryngol Head Neck Surg. 126(2):155-7,
2000
14. Lowe LH et al: Midface anomalies in children. Radiographics. 20(4):907-22; quiz 1106-7, 1112, 2000
15. Hsu CY et al: Congenital choanal atresia: computed tomographic and clinical findings. Acta Paediatr Taiwan.
40(1):13-7, 1999
16. Black CM et al: Potential pitfalls in the work-up and diagnosis of choanal atresia. AJNR Am J Neuroradiol.
19(2):326-9, 1998
P.IV(1):13

Image Gallery

855


Diagnostic Imaging Head and Neck

(Left) Axial NECT shows the typical features of unilateral choanal atresia. Fluid layers in the posterior nasal cavity on
the left
are due to a bony atresia
. There is thickening of the vomer
. (Right) Axial 3D reformatted image
in the same patient shows the bony choanal atresia on the left
with a widely patent choanal opening on the right
. Three dimensional images can be very helpful to the referring clinicians for surgical planning.

(Left) Axial bone CT in a newborn with complex nasal anomalies shows bilateral CAt
with aplasia of the right nasal
cavity. There are fluid layers in the left nasal cavity
& thickening of the vomer posteriorly
. (Right) More
inferior axial bone CT in the same patient shows fluid layering in the left nasal cavity
anterior to the absent
choanal opening. Note the absent right nasal cavity with the septum
apposed to the lateral nasal wall
.
Incidental persistent craniopharyngeal canal
is noted.

856

Diagnostic Imaging Head and Neck

(Left) Sagittal reformatted bone CT in the same patient shows the nonpatent left choanal opening
and the
layering fluid in the left nasal cavity
. Incidental craniopharyngeal canal
is shown. (Right) Axial bone CT shows
a membranous, unilateral choanal atresia on the right side
with layering fluid in the right nasal cavity. There are
typical associated features, including thickening of the vomer
and medialization of the posterior maxilla
.

Nasal Glioma
> Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section 1 - Nose and Sinus > Congenital Lesions > Nasal
Glioma
Nasal Glioma
Michelle A. Michel, MD
Key Facts
Terminology
Developmental mass of dysplastic neurogenic tissue sequestered & isolated from subarachnoid space
“Glioma” is a misnomer as this is nonneoplastic tissue
Extranasal glioma (ENG), intranasal glioma (ING)
Imaging
Well-circumscribed, soft tissue mass at superior nasal dorsum (ENG) or within nasal cavity (ING) with no
connection to brain
Multiplanar MR
May show pedicle of fibrous tissue (not brain parenchyma) between ING & intracranial cavity
Better than CT for differentiating NG from cephalocele or dermoid

Gyral structure of gray matter rarely visible
Commonly shows hyperintensity related to gliosis
Top Differential Diagnoses
Frontoethmoidal cephalocele
Nasal dermal sinus
Sinonasal solitary polyp
Pathology
Similar spectrum of congenital anomalies as frontoethmoidal cephaloceles
Does not contain CSF contiguous with subarachnoid or intraventricular spaces
Rarely associated with other brain or systemic anomalies
Clinical Issues
Usually identified at birth
ENG: 60%, ING: 30%, other sites: 10%
Treatment of choice is complete surgical resection

857


Diagnostic Imaging Head and Neck

(Left) Sagittal graphic of a nasal glioma shows a mass of dysplastic glial tissue
along the nasal dorsum. Notice the
absence of a connection to the intracranial contents. (Right) Sagittal T1WI MR of a newborn demonstrates a large
intranasal glioma
filling the right nasal cavity. No connection to the intracranial cavity by CSF-filled meninges or
brain parenchyma is appreciated, helping to distinguish this lesion from an cephalocele.

(Left) Coronal NECT shows a well-defined, somewhat polypoid soft tissue mass
, consistent with an intranasal
glioma, within the left nasal cavity. The nasal septum is slightly deviated toward the right. No definite connection to

the frontal lobe parenchyma is appreciated. (Right) Axial CECT shows a left-sided intranasal glioma
widening the
anterior nasal vault.
P.IV(1):15

TERMINOLOGY
Abbreviations
Nasal glioma (NG)
Extranasal glioma (ENG), intranasal glioma (ING)
Synonyms
Nasal cerebral heterotopia, glial heterotopia
Definitions
Developmental mass of dysplastic neurogenic tissue sequestered & isolated from subarachnoid space
“Glioma” is misnomer as this is nonneoplastic tissue
Best thought of as cephalocele without intracranial connection to brain
IMAGING
858


Diagnostic Imaging Head and Neck
General Features
Best diagnostic clue
Well-circumscribed, soft tissue mass at superior nasal dorsum (ENG) or within nasal cavity (ING) with no
connection to brain
Location
Most occur at bridge of nose or in & around nasal cavity
Usually off midline; right > left side
ENG: Mass along nasal dorsum
Glabella most frequent location
ENG may also be found at medial canthus

May be found in nasopharynx, mouth, pterygopalatine fossa (very rare)
ING: Nasal cavity mass
May be attached to concha of middle turbinate, nasal septum, or lateral nasal wall
Other sites: Ethmoid sinus, palate, middle ear, tonsil, & pharynx
Size
1-3 cm in diameter
Morphology
Well-circumscribed round, ovoid, or polypoid mass
CT Findings
NECT
ENG: Well-circumscribed soft tissue attenuation mass (isodense to brain) located at glabella
Superficial to point of fusion of frontal and nasal bones (fonticulus frontalis)
Nasal bones may be thinned
ING: Soft tissue attenuation mass within nasal cavity
Typically high in nasal vault
Fibrous pedicle may extend toward skull base but not intracranially
Defect in cribriform plate (10-30%)
Calcification rare
CECT
Typically no significant enhancement
If intrathecal contrast used
Fails to document connection of lesion to subarachnoid space
MR Findings
T1WI
Predominantly mixed to low signal intensity mass
Gyral structure of gray matter rarely visible
T2WI
Commonly shows hyperintensity related to gliosis
No CSF around lesion connecting to subarachnoid space
T1WI C+

Dysplastic tissue typically does not enhance
“Perceived” enhancement at periphery of intranasal lesions may actually represent adjacent
nasal mucosa
Imaging Recommendations
Best imaging tool
Multiplanar MR
May show pedicle of fibrous tissue (not brain parenchyma) between ING & intracranial cavity
MR better than CT for differentiating NG from cephalocele or dermoid
Avoids radiation to radiosensitive eye lenses in young patients
Protocol advice
Thin section sagittal T1 and T2 MR are important sequences
Preoperative thin section axial bone CT with coronal reformatted images may also help in surgical
planning
Bone only without enhancement
DIFFERENTIAL DIAGNOSIS
Frontoethmoidal Cephalocele
Frontonasal (FN) & nasoethmoidal (NE) cephaloceles
Clinical: Congenital mass on or around bridge of nose (FN) or within nasal cavity (NE)
Imaging: MR imaging shows connection to intracranial brain parenchyma
859


Diagnostic Imaging Head and Neck
Nasal Dermal Sinus
Clinical: Pit on tip or bridge of nose
Imaging
Associated dermoid or epidermoid along course from tip of nose to foramen cecum, anterior to crista
galli
Single or multiple
Possible intracranial connection via sinus tract

Sinonasal Solitary Polyps
Clinical: Polyp is less firm, more translucent that ING
Unusual < 5 years
Imaging
Typically inferolateral to middle turbinate (ING medial)
Homogeneous ↑ T2 MR signal with thin enhancement of peripheral mucosa
Orbital Dermoid and Epidermoid
Clinical: Focal mass in medial orbit near nasolacrimal suture
Imaging
Dermoid: Fluid or fat density/signal intensity
Epidermoid: Fluid density/signal
P.IV(1):16

PATHOLOGY
General Features
Etiology
Dysplastic, heterotopic neuroglial & fibrous tissue separated from brain during development of anterior
skull or anterior skull base
Similar spectrum of congenital anomalies as frontoethmoidal cephaloceles but does not contain CSF and
is not contiguous with subarachnoid or intraventricular spaces
ENG: Fonticulus frontalis (potential space prior to fusion of frontal & nasal bones) fuses prior to
regression of dural diverticulum
Dysplastic parenchyma sequestered over nasal bones/nasofrontal suture
ING: Prenasal space (potential space prior to fusion of nasal bones with cartilaginous nasal
capsule) fuses prior to regression of dural diverticulum
Dysplastic parenchyma sequestered in nasal cavity
Associated abnormalities
Rarely associated with other brain or systemic anomalies
Gross Pathologic & Surgical Features
Firm, smooth mass

Rarely recognized as brain tissue at surgery
10-30% attached to brain by a stalk of fibrous tissue through defect in or near cribriform plate
Mixed extra-intranasal lesions connect through defect in nasal bone
Microscopic Features
Fibrous or gemistocytic astrocytes & neuroglial fibers
Fibrous, vascularized connective tissue & sparse neurons
Glial fibrillary acidic protein (GFAP) & S100 protein positive
No mitotic features or bizarre nuclear forms
CLINICAL ISSUES
Presentation
Most common signs/symptoms
Extranasal glioma
Congenital subcutaneous blue or red mass along nasal dorsum (glabella)
Usually nonprogressive midfacial swelling
Intranasal glioma
Firm, polypoid submucosal nasal cavity mass
Nasal obstruction & septal deviation may be present
May be confused clinically with nasal polyp
Other signs/symptoms
No change in size with crying, Valsalva, or pressure on jugular vein (vs. frontoethmoidal cephalocele)
ENG: Capillary telangiectasia may cover
860


Diagnostic Imaging Head and Neck
ING: Respiratory distress; epiphora; may protrude through nostril
Clinical profile
Firm mass at glabella (ENG) or within nasal cavity (ING) in a newborn
Demographics
Age

Identified at birth or within 1st few years of life
Epidemiology
Very rare lesion
ENG: 60%, ING: 30%, other sites: 10%
Natural History & Prognosis
Grows slowly in proportion to adjacent tissue or brain if attached by pedicle
May deform nasal skeleton, maxilla, or orbit
May become infected, resulting in meningitis
Complete resection is curative
10% recurrence rate with incomplete resection
Treatment
Treatment of choice is complete surgical resection
ENG without intracranial connection removed via external incision with stalk dissection
ING without intracranial connection may be removed endoscopically
Less postoperative deformity than with craniotomy
Rare mixed gliomas (extranasal & intranasal components) best treated with combined intranasal and
extracranial approach
DIAGNOSTIC CHECKLIST
Consider
Most important to differentiate NG from cephalocele
Document lack of connecting brain tissue &/or contiguous CSF space
Image Interpretation Pearls
Must evaluate images for connection to intracranial cavity through skull base defect (cephalocele)
Combined use of thin section MR & bone CT accomplishes this task
Focus imaging to fronto-ethmoid area
SELECTED REFERENCES
1. Husein OF et al: Neuroglial heterotopia causing neonatal airway obstruction: presentation, management, and
literature review. Eur J Pediatr. 167(12):1351-5, 2008
2. Riffaud L et al: Glial heterotopia of the face. J Pediatr Surg. 43(12):e1-3, 2008
3. De Biasio P et al: Prenatal diagnosis of a nasal glioma in the mid trimester. Ultrasound Obstet Gynecol. 27(5):571-3,

2006
4. Hedlund G: Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr
Radiol. 36(7):647-62; quiz 726-7, 2006
5. Khanna G et al: Causes of facial swelling in pediatric patients: correlation of clinical and radiologic findings.
Radiographics. 26(1):157-71, 2006
6. Huisman TA et al: Developmental nasal midline masses in children: neuroradiological evaluation. Eur Radiol.
14(2):243-9, 2004
7. Belden CJ et al: The developing anterior skull base: CT appearance from birth to 2 years of age. AJNR Am J
Neuroradiol. 18(5):811-8, 1997
8. Barkovich AJ et al: Congenital nasal masses: CT and MR imaging features in 16 cases. AJNR Am J Neuroradiol.
12(1):105-16, 1991
P.IV(1):17

Image Gallery

861


Diagnostic Imaging Head and Neck

(Left) Sagittal CECT demonstrates a mildly enhancing soft tissue lesion in the nasal cavity consistent with intranasal
glioma
. No connection is identified with what appears to be normal foramen cecum
in a child of this age.
(Right) Sagittal T1WI C+ MR in the same patient shows diffuse, slightly heterogeneous enhancement throughout the
glioma
.

(Left) Coronal FLAIR MR shows mixed signal intensity within an intranasal glioma
. There is no connection to the

left frontal lobe to suggest that a cephalocele is present. (Right) Axial T2WI MR shows a well-circumscribed intranasal
glioma
. It is slightly heterogeneous but similar in signal intensity to the brain parenchyma. No surrounding CSF
can be seen around this glioma, a finding that is more indicative of an cephalocele.

862


Diagnostic Imaging Head and Neck

(Left) Axial T1WI C+ MR shows central enhancement
within a large extranasal glioma. The lesion is located slightly
off the midline. Enhancement is uncommon in these lesions. (Right) Axial T1WI C+ MR shows a well-defined extranasal
glioma
along the dorsum of the nose in the midline, with diffuse enhancement throughout the lesion. This degree
of enhancement is a rare feature of nasal gliomas.

Nasal Dermal Sinus
> Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section 1 - Nose and Sinus > Congenital Lesions > Nasal
Dermal Sinus
Nasal Dermal Sinus
Michelle A. Michel, MD
Key Facts
Terminology
Defective embryogenesis of anterior neuropore resulting in any mixture of dermoid cyst, epidermoid cyst, &/or
sinus tract in frontonasal region
Imaging
Midline location anywhere from nasal tip to anterior skull base at foramen cecum
CT
Bifid crista galli with large foramen cecum

Fluid attenuation tract (sinus)/cyst or fat containing mass (dermoid) from nasal dorsum to skull base
within nasal septum
MR
Fluid signal tract in septum from nasal dorsum to skull base (sinus)
Focal low signal (epidermoid) or high signal (dermoid) mass found between tip of nose & apex of crista
galli
Top Differential Diagnoses
Fatty marrow in crista galli
Nonossified foramen cecum
Frontoethmoidal cephalocele
Nasal glioma
Pathology
Intracranial extension of nasal dermal sinus in 20%
Associated craniofacial anomalies in 15%
Clinical Issues
Nasoglabellar mass (30%)
Pit on skin of nasal bridge at osteocartilaginous nasal junction ± protruding hair

863


Diagnostic Imaging Head and Neck

(Left) Lateral graphic depicts a nasal dermal sinus with 2 dermoids. An extracranial dermoid is present just below a
cutaneous nasal pit
. An intracranial dermoid
splits a bifid crista galli
. (Right) Coronal bone CT demonstrates
a nasal dermoid/epidermoid at the skull base. The low attenuation midline mass
causes remodeling of the

adjacent bone
at the margins of the foramen cecum.

(Left) Sagittal T2WI MR in a 3-year-old boy with a bump on the tip of the nose shows a hyperintense sinus tract
extending from the anterior skull base into the nasal septum. The features are characteristic of a dermal sinus.
(Right) Axial NECT demonstrates a low-attenuation dermoid
centered in the cartilaginous portion of the nasal
septum. The mass is slightly higher in attenuation than adjacent fat.
P.IV(1):19

TERMINOLOGY
Abbreviations
Nasal dermal sinus (NDS)
Synonyms
Nasal dermoid, nasal dermal cyst, anterior neuropore anomaly
Definitions
Defective embryogenesis of anterior neuropore resulting in any mixture of dermoid cyst, epidermoid cyst, &/or
sinus tract in frontonasal region
IMAGING
General Features
Best diagnostic clue
CT
864


Diagnostic Imaging Head and Neck
Bifid crista galli with large foramen cecum
Fluid attenuation tract (sinus)/cyst or fat-containing mass (dermoid) from nasal dorsum to skull
base within nasal septum
MR

Fluid signal tract in septum from nasal dorsum to skull base (sinus)
Focal low signal (epidermoid) or high signal (dermoid) mass found between tip of nose & apex
of crista galli
Location
Midline lesion anywhere from nasal tip to anterior skull base at foramen cecum
Size
5 mm to 2 cm dermoid/epidermoid
Morphology
Ovoid mass ± tubular sinus tract
CT Findings
Bone CT
Focal tract (sinus) or mass (dermoid or epidermoid) anywhere from nasal bridge to crista galli
Fluid-density tract = sinus
Fluid-density mass = epidermoid
Fat-density mass = dermoid
Signs of intracranial extension
Large foramen cecum with bifid or deformed crista galli or cribriform plate
MR Findings
T1WI
↓ signal tract = sinus
↑ signal mass = dermoid
↓ signal mass = epidermoid
T2WI
↑ signal in sinus, epidermoid, or dermoid
Coronal plane shows septal lesions to best advantage
DWI
↑ signal = epidermoid
Susceptibility artifacts at skull base may obscure signal from epidermoid
Imaging Recommendations
Best imaging tool

MR more sensitive for delineating sinus tract & characterizing epidermoid/dermoid lesions and
intracranial extension
Bone CT optimal for identifying skull base defect & crista galli deformity
Protocol advice
Imaging “sweet spot” is small & anterior
Focus imaging from tip of nose to back of crista galli
Inferior end of axial imaging is hard palate
Contrast does not help with diagnosis
CT
Thin section (1-2 mm) bone & soft tissue axial & coronal CT
MR
Sagittal plane displays course of sinus tract from nasal dorsum to skull base
Fat-suppressed images confirm fat presence in dermoids
DWI imaging important additional sequence
DIFFERENTIAL DIAGNOSIS
Fatty Marrow in Crista Galli
No nasoglabellar mass or pit on nose
CT & MR otherwise normal
Nonossified Foramen Cecum
Closes postnatally in 1st 5 years of life
Crista galli not deformed or bifid
Frontoethmoidal Cephalocele
Bone dehiscence is larger, involving a broader area of midline cribriform plate or frontal bone
Direct extension of meninges, subarachnoid space ± brain can be seen projecting into cephalocele on sagittal MR
Nasal Glioma
865