Imagingof paranasal sinuses ,inflammatory , benign and neoplastic lesions anatomical variants

1. IMAGING OF
PARANASAL SINUSES
Dr Roshan Valentine
PG Resident
Dept of Radiodiagnosis
St Johns Hospital , Bangalore

2. EMBRYOLOGY
• At birth, the ratio of the volume of the facial
skeleton to the volume of the cranial vault is
about 1:7.
• Development of the paranasal sinuses leads
to increase in the ratio
• 4 major sinuses : Maxillary , ethmoid ,
sphenoid and frontal sinuses

3. • Maxillary , ethmoid and frontal sinuses
develop from invaginations of the nasal
cavity into bones
• Sphenoid sinus forms by closure of
sphenoethmoidal recess
• Maxillary sinus - forms during 3rd fetal
month
• Primary pneumatisation and secondary
pneumatisation
• Sphenoid and frontal sinus – develop during
Pre natal 4th mnth then undergo sec
pneumatisation
EMBRYOLOGY

4. • Frontal sinus not radiologically visible till
post natal 6 yrs
• Ethmoid sinus during post natal 5th month
• Growth continues till adulthood
EMBRYOLOGY

6. ANATOMY
• Air containing cavity in certain skull bones
• They are lined by mucosa similar to that of
the nasal cavity – pseudo stratified ciliated
columnar epithelium
SIGNIFICANCE
• Lighten the skull & facial bones
• Contributes to vocal resonance
• Collapsible framework that helps the
brain to protect from blunt trauma

7. PHYSIOLOGY
• Side to side cyclic variation in thickness of
nasal mucosa
• Signal intensity of mucosal lining of nasal
cavity & ethmoid sinuses also vary.
• During oedematous phase of nasal cycle,
mucosal signal intensity on T2 is similar to
mucosal inflammation
• No cyclic variation in frontal, maxillary or
sphenoid sinus mucosa

9. Sinuses Status at
Birth
First
Radiologic
al
evidence
Reaches
Adult
size by
Maxillary
sinus
Present at
birth
4-5 months
after birth
15 years
Ethmoid
sinus
Present at
birth
1 year 12 years
Sphenoid
sinus
Not Present 4 years 15 years –
adult age
Frontal Sinus Not Present 6 years Size
increases
until teens

11. MAXILLARY SINUS
• Antrum of highmore
• Pyramidal in shape
• Present at birth as a rudimentary sinus
• First radiological evidence is at 4-5 months
after birth
• Reaches adult size by 15 years
• On average, it has capacity of 14.75 ml

12. MAXILLARY SINUS DRAINAGE
• Seen high up in the medial wall
• Does not open directly into the nasal cavity,
but opens into post. part of ethmoidal
infundibulum, via hiatus semilunaris into
middle meatus.
• The infundibulum is the air passage that
connects the maxillary sinus ostium to the
middle meatus.
• Unfavourable for natural sinus drinage
• Accessory ostium – 30 % cases

14. FRONTAL SINUS
• Situated between the outer & inner table of
frontal bone
• Funnel shaped
• Two sinuses on either side
• Asymmetrical
• Intervening bony septum which may be thin
or deficiency

15. FRONTAL SINUS
• Not present at birth
• First radiological evidence is at 6
years
• Reaches adult size after puberty
• OSTIUM : posteromedial floor of the
sinus (most dependent part).
• Open into frontal recess or naso
frontal duct

17. FRONTAL SINUS
FRONTAL RECESS
• Hour glass like narrowing
• Narrowest anterior air channels – prone for
infection
• obstruction subsequently results in loss of
ventilation and mucociliary clearance of the
frontal sinus

18. SPHENOID SINUS
• Occupies the body of sphenoid
• Right & left, seperated by a thin strip
of bony septum (like frontal sinus)
• Ostium opens into spheno ethmoidal
recess
• Relations of the sinus are very
important, esp during the surgical
approach of pituitary gland

19. SPHENOID SINUS

20. SPHENOID SINUS
RELATIONS
Anterior Part
• Roof – olfactory tract, optic chiasma &
frontal lobe
• Lateral – optic nerve, internal carotid artery
& maxillary nerve
Posterior Part
• Roof – Pituitary gland in sella turcica
• Lateral – Cavernous sinus,ICA & Cranial
nerves III, IV, VI & all divisions of V

21. ETHMOID SINUS
• Thin walled air cavities in the lateral masses
of the ethmoid bone
• Occupy the space between the upper third
of the lateral nasal wall and the medial wall
of orbit
• Clinically divided into anterior ethmoidal air
cells & posterior ethmoidal air cells, by basal
lamella (lateral attachment of middle
turbinate to lamina papyracea)

22. ETHMOID SINUS
DRAINAGE
• Anterior : Recess of hiatus semilunaris and
middle meatus via ethmoid bulla
• Posterior : Sup meatus and SE recess
• Present at birth
• Reaches adult size by 12 yrs
• First radiological evidence seen at 1 year

23. SPHENOID SINUS

24. ETHMOID SINUS RELATIONS
Roof – formed by the anterior cranial fossa
Lateral wall - orbit
Medial wall – nasal cavity
Thin paper like bony part of the ethmoid
separating the air cells from the orbit, Called
LAMINA PAPYRACEA, can be easily destroyed
leading to spread of ethmoidal infections into
the orbit
Optic nerve forms a close relationship with the
posterior ethmoidal cells & is at risk during
ethmoidal surgery

25. OSTEOMEATAL COMPLEX
• Key anatomic area for surgeons
• Blockage prevents mucociliary clearance –
stagnation of secretions – recurrent or
chronic sinusitis

26. OSTEOMEATAL COMPLEX
BOUNDARIES
• Medially :middle turbinate,
• Posteriorly and superiorly : basal
lamella
• Laterally : lamina papyracea.
• Inferiorly and anteriorly the omc is
open.

27. OSTEOMEATAL COMPLEX
STRUCTURES
• Maxillary sinus ostium
• Ethmoidal bulla
• Frontal recess
• Uncinate processus
• Infundibulum
• Hiiatus semilunaris
• Middle meatus

29. NORMAL ANATOMY
NASAL STRUCTURES
Nasal Septum
• Bone and cartilage
• Midline structure
Lateral wall
• Superior , middle and inferior tubrinates
3 air passages
• Superior , middle and inferior meatus

30. NORMAL ANATOMY
INFERIOR TURBINATES
• Lower most projection with extension into
nasopharynx
• Enlarged in DNS and allergic rhinits
NASOLACRIMAL DUCT
• Tubular structure in the lateral wall
• Opens into inferior meatus underneath inf
turbinate

31. NORMAL ANATOMY
MIDDLE TURBINATE
• Attach to the skull base lateral to cribriform
plate
• Basal lamella – part of middle turbinate
attached to ethmoid complex

32. NORMAL ANATOMY
DRAINING PATHWAYS
• Anterior draining pathways
• Posterior draining pathways

33. NORMAL ANATOMY
ANTERIOR DRAINING PATHWAYS
• Osteomeatal complex – air passage between
frontal , ant ethmoid and maxillary sinus
Components: Frontal recess , ethmoid
infundibulum , hiatus semilunaris and middle
meatus

34. NORMAL ANATOMY
MIDDLE MEATUS
• b/w middle turbinate and uncinate process
• Uncinate process: superior extension of the
medial wall of maxillary sinus
• Agger Nasi : Most anterior cells in ant
ethmoidal sinus complex
• Hiatus semilunaris – Crevice between
uncinate process and ethmoidal bulla
• Ethmoidal infundibulum : maxillary ostium
to middle meatus , b/w uncinae process and
lamina papyracea

35. NORMAL ANATOMY
INFERIOR MEATUS
• Opening of the drainage channel of NLD

36. NORMAL ANATOMY
POSTERIOR DRAINAGE PATHWAYS
• Draining pathways of sphenoid and posterior
ethmoidal sinus
• They drain via sphenoethmoidal recess into
superior meatus
• B/w anterior sphenoid sinus wall and
posterior wall of ethmoid sinus air cells

37. ANATOMICAL VARIANTS
CONCHA BULLOSA
• Aerated middle turbinate
• Obstruct the middle meatus and
infundibulum
• Concha Bullosa – Pneumatised bulbous
segment of the middle turbinate
• Lamellar concha – Only the attachment
portion of the middle turbinate
AERATED CRISTA GALLI
AERATED ANTERIOR CLINOID PROCESS

38. ANATOMICAL VARIANTS
DEVIATED NASAL SEPTUM
• Can compress middle turbinate laterally
• Narrow the middle meatus
• Bony spurs : can obstruct OMC

39. ANATOMICAL VARIANTS
PARADOXICAL MIDDLE TURBINATE
• Middle turbinate project laterally narrowing
middle meatus

40. ANATOMICAL VARIANTS
UNCINATE PROCESS
Superior edge can
• Deviate medially – obstruct middle meatus
• Deviate laterally to compromise the
infundibulum
• Fusion with the medial orbital wall –
endanger orbital contents while
uncinectomy is done

41. ANATOMICAL VARIANTS
UNCINATE PROCESS
• Type I – Insertion of UP into LP directly/
indirectly (via an anterior ethmoidal cell)
• Type II –Insertion of UP into the skull base
(SB)
• Type III – Insertion of UP into middle
turbinate
• Type IV – UP lying free in the middle meatus
(Free type).

42. ANATOMICAL VARIANTS
UNCINATE PROCESS PNEUMATISATION

43. ANATOMICAL VARIANTS
HALLER CELLS
• Infraethmoid air cells extending along the
roof of maxillary sinus and lateral to the
uncinate process
• Narrows the infundibulum

44. ANATOMICAL VARIANTS
ONODI CELL
• Lateral and posterior extensions of the
posterior ethmoid air cells , superolateral to
the sphenoid sinus
• Lie in close relation to the optic nerve

46. ANATOMICAL VARIANTS
PROMINENT ETHMOID BULLA
• Largest of the ethmoid air cells
• Obstruct the middle meatus and
infundibulum

47. ANATOMICAL VARIANTS
MEDIAL DEVIATION OR DEHISCENCE OF THE
LAMINA PAPYRACEA
• May be either congenital or the result of
prior facial trauma.
• It occur most often at the site of the
insertion of the basal lamella into the lamina
papyracea, thus rendering this portion of the
lamina papyracea most delicate
• Orbit at risk

48. ANATOMICAL VARIANTS
ETHMOIDAL ROOF VARIATIONS
• Keros 3 types
• Length of the lateral lamella of cribriform
plate – thinnest part of entire skull base
• Danger of penetration of of the lateral
lamella
Type 1: 1-3mm deep
Type II : 4-7mm
Type III : 8-16mm

49. ANATOMICAL VARIANTS
AERATED CRISTA GALLI
• When aeration of the normally bony crista galli
occurs the aerated cells may communicate
with the frontal recess, and obstruction of this
ostium.
• To avoid unnecessary surgical extension into
the anterior cranial vault, it is important to
recognize an aerated crista galli and
differentiate it from an ethmoid air cell.

50. IMAGING MODALITIES

51. IMAGING MODALITIES
CONVENTIONAL RADIOGRAPHY
• Lateral view
• Caldwell View
• Waters View
• Submento vertical view
CT
Gold standard. Coronal & axial sections
MRI
• MRI is predominantly used for pre and post
operative management of naso sinus
malignancy
• The chief disadvantage of MRI is its inability to
show the bony details of the sinuses, as both
air and bone give no signal

52. WATERS VIEW • The patient’s nose and chin are placed in
contact with the midline of the cassette
holder.
• The head is then adjusted to bring the orbito-
meatal baseline to a 45-degree angle to the
cassette holder.
• Maxillary sinus ,frontal sinus , anterior
ethmoidal air cells , inferior orbital rims , and
orbital floors

53. CALDWELL VIEW
• The head is positioned so that the orbito-
meatal baseline is raised 15 degrees to the
horizontal
• Frontal sinus and posterior ethmoidal air
cells

54. LATERAL VIEW • Mediansagittal plane parallel to
casette
• Inter-orbital line is perpendicular
to the Bucky
• Frontal, maxillary and sphenoid
sinus

55. SUBMENTO VERTEX VIEW
• Mainly for the sphenoid sinus
• Infraorbito-meatal (Frankfort line) parallel to
the casette

56. COMPUTED TOMOGRAPHY
• Modality of choice
• Protocol : Thin slices and MPR
• Axial plane : parallel to the inferior
orbitomeatal plane
• Extent : superior wall of frontal sinus to hard
palate
• Bone and soft tissue window
• Patency of Osteometal complex and other
pathways : Lung Window
• Contrast : neoplasm and its intra acranial
extension , acute infections,

57. COMPUTED
TOMOGRPAHY
PRE REQUISITES
• Course of medical therapy to eliminate
reversible mucosal inflammation
• Reduce nasal congestion 15 mins prior to the
study
• Thus improve the display of the fine bony
architecture and any irreversible mucosal
disease

58. COMPUTED
TOMOGRPAHY
• Coronal View: Primary image orientation for
evaluation of the sinonasal tract in all
patients with inflammatory sinus disease
who are endoscopic surgical candidates

59. COMPUTED
TOMOGRPAHY

60. COMPUTED
TOMOGRPAHY
AXIAL IMAGE
• Complements coronal image
• For anterior and posterior sinus walls
• Visualising fronto ethmoid junction and
sphenoethmoid recess

62. MR IMAGING
• Spread of pathology into brain and orbit
• Superior soft tissue extension
• Contrast : tissue characterization
• Skull base and posterior fossa

63. INFLAMMATORY SINUS
DISEASE
ACUTE SINUSITIS
• Superinfection of obstructed sinus
• Secretions favour growth for bacteria
• The hallmark of acute sinusitis is air fluid
level on plain x-ray and CT

64. CHRONIC SINUSITIS
• Hypertrophic mucosa
• Polypoid changes with atrophy and fibrosis
• Sinus secretions in acute state: 10-25HU
• Chronic sinusitis : 30-60HU (mucoid
secretions)
• Facial bones undergo thickening and
sclerosis adjacent to the inflamed mucosa
Hyperdense Secretions
• Inspissated secretions
• Fungal sinusitis
• Hemorrhage
CHRONIC SINUSITIS

65. CHRONIC SINUSITIS

66. Sonkens Et al patterns of chronic sinusitis
• Infundibular pattern
• Ostiomeatal unit pattern
• Sphenoethmoidal recess pattern
• Sinonasal polyposis pattern
• Sporadic/unclassified pattern
Helps the surgeon in planning FESS as the
rational is to restore the flow of sinus secretion
via their natural pathways
CHRONIC SINUSITIS

67. INFUNDIBULAR PATTERN
• Maxillary sinus , infundibulum
• Occur due to mucosal thickening, polyp in that
location , Haller cells
OSTIOMEATAL UNIT PATTERN
• Middle meatus obstruction
• Changes in frontal, anterior ethmoid and
maxillary sinus
• Cause : Mucosal thickening , polyps , concha
bullosa , DNS
SPHENOETHMOIDAL RECESS PATTERN
• SE recess is blocked
• Changes in I/L sphenoid and post ethmoidal air
cells
CHRONIC SINUSITIS

68. SINONASAL POLYPOSIS PATTERN
• Both nasal cavities and sinuses are filled
• Mix of all three patterns
SPORADIC/UNCLASSIFIED PATTERN
• No specific kind of obstruction
• Mucocele , retention cysts or post operative
changes are there
CHRONIC SINUSITIS

70. SINONASAL POLYPOSIS
• Nonneoplastic, inflammatory swelling of
sinonasal mucosa
• Involves nasal cavity and PNS
• Predominantly along lateral nasal wall and
roof of nasal cavity
• Dx clue : Polypoid masses involving nasal
cavity & paranasal sinuses mixed with
chronic inflammatory secretions

71. SINONASAL POLYPOSIS
IMAGING FINDINGS
• NECT : Polypoid soft tissue density with
bone remodeling/erosions
Hyperdense with inc protein content and dec
water content
• CECT : Peripheral enhancement

72. SINONASAL POLYPOSIS
MRI
T1WI
• Fresh mucus (high water content) is
hypointense
• Heterogenous SI : polyps mixed with various
ages of mucus
T2WI
• Fresh mucus is hyperintense
• Chronic, inspissated mucus can appear low
signal (mimics air)
T1WI C+
• Thin mucosal enhancement between
polypoid soft tissue lesions without central
enhancement

73. SINONASAL SOLITARY
POLYP

74. • Secondary to obstructed mucus drainage
• Expanded and remodeled sinuses –
obstructed and contain secretions
• Frontal > ethmoid sinus > maxillary sinus
• Infected mucocele – Mucopyocele
• CT: expanded sinus with intact walls
containing mucoid and soft tissue densities
• Remodelling of sinus can occur
• MR : Depends on the nature of the secretion
Peripheral enhancement
MUCOCELE

75. NLD MUCOCELE

76. INFLAMMATORY SINUS
DISEAS
3 TYPES
• Allergic fungal rhinosinusitis
• Invasive fungal sinusitis
• Non invasive chronic fungal sinusitis
FUNGAL SINUSITIS

77. INFLAMMAORY SINUS
DISEASE
ALLERGIC FUNGAL SINUSITIS
• Allergic response to fungal elements in
atopic pts
• CT : Diffuse mucosal thickening involving
multiple sinuses with central hyperdense
content and peripheral hypodensity
• MRI :Central content is hypo on T1 and T2
• Wall destruction not seen
• Central or punctate calcification
FUNGAL SINUSITIS

78. INFLAMMAORY SINUS
DISEASE
ALLERGIC FUNGAL SINUSITIS
• Allergic response to fungal elements in
atopic pts
• CT : Diffuse mucosal thickening involving
multiple sinuses wit central hyperdense
content and peripheral hypodensity
• MRI :Central content is hypo on T1 and T2
• Wall destruction not seen
• Central or punctate calcification
FUNGAL SINUSITIS

79. INFLAMMAORY SINUS
DISEASE

80. INFLAMMATOY SINUS
DISEASE
INVASIVE FUNGAL SINUSITIS
• Immunosuppressed individuals
• Mucor, aspergillus or fusarium
• CT: Opacification of sinuses by secretions
and mucosal hypertrophy
• Destruction of the boney wall
• Spread of infection into orbits , cavernous
sinus or brain
FUNGAL SINUSITIS

81. INFLAMMATORY SINUS
DISEASE
NON INVASIVE CHRONIC FUNGAL SINUSITIS
• Chronic, noninvasive form of fungal sinus
infection in which material within sinonasal
cavity is colonized by fungus
• Ball of fungus
• MC – Maxillary sinus
FUNGAL SINUSITIS

82. NON INVASIVE CHRONIC FUNGAL SINUSITIS
CT FINDINGS
CECT
• Thickened, inflamed mucosa at periphery of sinus may enhance
• Opacification or focal mass within sinus lumen
• Central areas of high density ± calcification
• Thick, sclerotic bony sinus walls from chronic inflammation
MR FINDINGS
T1WI
• Variable signal material in affected sinus
• Usually ↓ T1 signal due to absence of free water in thick, solid,
mycetomatous mass
T2WI
• Hypointense mass from macromolecular protein binding may be
mistaken for air
• T1WI C+
• Inflamed peripheral mucosa may enhance
FUNGAL SINUSITIS

83. GRANULOMATOUS
DISEASE
• Actinomycosis, tuberculosis, syphilis, leprosy,
rhinoscleroma, rhinosporidiosis, sarcoidosis,
Wegener’s granulomatosis, midline
granuloma, leishmaniasis and yaws
• Non specific findings -Soft tissue masses
and focal erosions
• Leprosy,WG, Cocaine : septal thickening or
erosions

84. BENIGN TUMOR AND
TUMOR LIKE LESIONS
• Sinonasal osteoma
• Sinonasal fibrous dysplasia
• Sino nasal ossifying fibroma
• Juvenile Angiofibroma
• Sinonasal papilloma

85. SINONASAL OSTEOMA
• MC benign tumor
• benign, well-defined, slow-growing,
bone-forming tumor from wall of
paranasal sinus & protrudes into sinus
lumen
• Frontal & ethmoid > > > maxillary &
sphenoid
• Larger osteomas can cause sinus
opacification by ostia obstruction
• Orbital mass effect by extraconal
extension

86. SINONASAL OSTEOMA

87. SINONASAL
FIBROOSSEOUS LESIONS
• Spectrum of disorder a purely fibrotic lesion
at one end and a dysplastic bony lesion at
the other
• Fibrous tissue replacing normal medullary
bone
• Diagnostic Clue
FD : Ill-defined expansion of diploic space with
“Ground-glass” density
Ossifying Fibroma : Well-demarcated,
expansile mass with soft tissue density
(fibrous) central area surrounded by ossified
rim

88. FD

89. OF

90. SINONASAL INVERTED
PAPILLOMA
• Benign epithelial tumor of nasal mucosa
with histology showing epithelium
proliferating into underlying stroma
• Dx Clue : Mass along lateral nasal wall
centered at middle meatus ± extension into
antrum with local bone remodeling &
obstructive sinus disease
• MC : Lateral nasal wall with extension into
adjacent sinus

93. Modified Krause staging
A. Inverted papilloma (IP) confined to the nasal
cavity, ethmoid sinus, or medial maxillary wall.
B. Inverted papilloma (IP) with involvement of
any maxillary wall (other than the medial wall)
or frontal sinus or sphenoid sinus
C. Inverted papilloma with extension beyond
the paranasal sinuses
A- endoscopic resection
B – Radical approach
PAPILOMMA

94. JUVENILE ANGIOFIBROMA
• Benign, vascular, nonencapsulated,
locally invasive nasal cavity mass
• Centered in posterior nasal
• Extends into nasopharynx,
pterygopalatine fossa (PPF),
infratemporal fossacavity near SPF
• Can spread across skull base and a
combination of CT (to assess bone
destruction;) and contrast-enhanced
MRI (to assess soft tissue extent;) may
be required
• Dx clue : Intensely enhancing mass
originating at sphenopalatine foramen
(SPF) in adolescent male

95. JAF

96. MALIGNANT TUMOR OF
PNS
• Malignant epithelial tumor from sinus
surface epithelium with squamous cell or
epidermoid differentiation
• MC : Maxillary antrum
• Dx clue : Aggressive antral soft tissue mass
with invasion & destruction of sinus walls
• Role of radiologist : presurgical tumor map
of spread

97. MALIGNANT TUMOR OF
PNS
• Imaging findings
CT : Solid, moderately enhancing mass with
aggressive bone destruction +/- necrosis
MRI :
• T1 : Intermiediate , intratumoral H’age
shows inc signal
• T2: ↓ T2 signal due to ↑ cellularity & ↑
nuclear:cytoplasmic ratio
• CE: Enhancement typically mild to moderate;
diffuse, but heterogeneous
• PET : Avid uptake of F18 FDG

98. MALIGNANT TUMOR OF
PNS

99. MALIGNANT TUMOR OF
PNS

100. MALIGNANT TUMOR OF
PNS
• OHNGREN’S LINE : Connecting the
medial canthus of the eye to the
angle of the mandible
• Divide the maxillary sinus into
• Anteroinferior portion infrastructure)- good
prognosis
• Superoposterior portion(suprastructure) -
poor prognosis – early extension to skull
base , orbits , infratemporal fossa

101. STAGING OF CANCER
(AJCC 7TH ED)

102. STAGING OF CANCER
(AJCC 7TH ED)

103. STAGING OF CANCER
(AJCC 7TH ED)

104. OLFACTORY
NEUROBLASTOMAS
• Olfactory neuroepithelioma ,
Esthesioneuroblastoma
• Polypoid tumor with profuse bleeding
• Age : 11-22yrs and 50-60 years of age
• CECT : homogenous mass with moderate
enhancement
• Cysts at intracranial tumor-brain margin
• Dx clue : Dumbbell-shaped mass with upper
portion in anterior cranial fossa, lower
portion in upper nasal cavity, & “waist” at
level of cribriform plate
• Peripheral tumor cysts at intracranial tumor-
brain margin is highly suggestive of diagnosis
of ENB

106. Multiplanar Sinus CT: A Systematic Approach to Imaging Before Functional Endoscopic Sinus Surgery, AJR 2010;
194:W527–W536
• Sinus drainage pathways – OMC ,
sphenoidalostia , sphenoethmoidal recess,
frontal recess
• Anatomic variants : Nasal septum , OMC
variants
• Critical variants : Cribriform plate dehiscence
of lamina papyracea , focal bony dehiscence
of sphenoidal sinus .
• Soft tissues : orbital , cranial extension