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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4416_Библиотеки_им_академика_М_И_Перельмана
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51Chapter 3 Sinonasal Anatomy: Section-wise
G
I
H
J
K
Figs. 3.2G to L: Consecutive axial sections from cranial to caudal.
L
Section 1 Normal Anatomy and Imaging52
CONSECUTIVE SAGITTAL SECTIONS
Consecutive sagittal sections are depicted from lateral to medial in Figures
3.3A to F. Sagittal sections well depict the drainage pathways of frontal sinus
and sphenoid sinus.
Sagittal Sections (Figs. 3.3A to F)
■ Laterally on these sagittal images, frontal (FS) and maxillary sinuses (MS)
can be seen.
■ On a more medial section through the nasal cavity, the turbinates and
meati are well-visualized.
■ e anterior and posterior ethmoidal cells (PE cells) are seen between
the frontal and sphenoid sinuses (SS).
■ Agger nasi cell is the anterior most anterior ethmoidal cell seen anterior
to the frontal sinus drainage pathway.
■ Bulla ethmoidalis (BE) is the largest anterior ethmoidal cell and lies
behind the frontal sinus drainage pathway.
■ e posterior boundary of the bulla ethmoidalis (BE) is the basal lamella
(BL).
■ Sphenoid ostium (SO) is the opening of the sphenoid sinus into
sphenoethmoidal recess.
■ Onodi cells if present can be seen projecting superior to the sphenoid
sinus.
■ Parts of nasal septum, both cartilaginous and bony (vomer and
perpendicular plate of ethmoid) can be seen in the midline.
■ Hard palate forms the inferior boundary of the nasal cavity.
Key
AN: Agger nasi cells BE : Bullae ethmoidalis
BL: Basal lamella FS: Frontal sinus
FSDP: Frontal sinus drainage pathway HP: Hard palate
IM: Inferior meatus IT: Inferior turbinate
MM: Middle meatus MT: Middle turbinate
NB: Nasal bone NS: Nasal septum
SO: Sphenoid ostium SS: Sphenoid sinus
53Chapter 3 Sinonasal Anatomy: Section-wise
A
C
B
D
E
Figs. 3.3A to F: Consecutive sagittal sections.
F
Section
2
Inammatory Nasal Conditions
4. Imaging in Rhinosinusitis (Inammatory Diseases)
5. Imaging in Polyps and Mucocele
6. Chronic Rhinosinusitis: Clinical Aspects
7. Imaging in Fungal Sinusitis
8. Fungal Diseases of Nose and Paranasal Sinuses: Surgical Aspects
9. Pre- and Post-functional Endoscopic Sinus Surgery Imaging
4
CHAPTER
Imaging in Rhinosinusitis
(Inammatory Diseases)
Ashu Seith Bhalla, Smita Manchanda
• Introduction
• Classication
• Imaging Modalities
• Acute Sinusitis
– Complications
• Chronic Rhinosinusitis
– Imaging Findings
– Staging
– Patterns
– Causes of Obstruction to
Drainage Pathways
– Chronic Complications
▪ Retention Cyst, Polyps,
Mucocoele
▪ Silent Sinus Syndrome
▪ Atrophic Rhinitis
– Miscellaneous Associations
▪ Chronic Inammation and
Cocaine Abuse
▪ Sinonasal Tuberculosis
▪ Dental Infection and Sinusitis
– Differential Diagnosis
INTRODUCTION
■ Refers to inammation of the sinus mucosa, often accompanied by that
of nasal mucosa as well.
■ Incidental mucosal thickening is often detected in asymptomatic patients
undergoing magnetic resonance imaging (MRI) for other indications. It
is reported that up to 20–40% patients who undergo MRI may display
mucosal thickening in the sinonasal (SN) cavity.1 In asymptomatic
patients this mucosal thickening may not have any clinical signicance.
■ Drainage pathways
• Sinus lined by ciliated columnar epithelium → mucous propelled to
sinus ostium by cilia → nasal cavity → pharynx
• Any obstruction in nasociliary pathways for clearance of mucosa leads
to accumulation of secretion in the sinus.
Section 2 Inammatory Nasal Conditions58
CLASSIFICATION
Various bases of classication are:
■ Based on etiology: Infective (viral, bacterial or fungal), non-infective
(reactive or allergic)
■ Based on duration: Acute, subacute or chronic (Chapter 6)
■ Based on extra-sinus or vascular inltration: Invasive or noninvasive
■ Based on extent: Various patterns are described which are detailed
subsequently.
IMAGING MODALITIES
■ Imaging is seldom indicated for acute sinusitis, but is performed if
recurrent episodes of acute sinusitis occur, or in chronic sinusitis. Imaging
is also indicated when complicated acute sinusitis is suspected.
1,2
Plain Radiographs
■ May be used in acute sinusitis or as a screening modality in those with a
low clinical suspicion.
■ Should be performed in sitting/standing position.
■ No patient preparation is required.
■ Frequently used views are Water’s view (Fig. 4.1) and Caldwell’s view,
occasionally lateral view may be required.
■ May be used for follow-up imaging.
Fig. 4.1: Chronic sinusitis (Water’s view). Mucosal thickening bilateral maxillary (arrows)
and right frontal sinuses (asterisk).
Computed Tomography (CT) Scan
■ Non-contrast computed tomography (NCCT) is the imaging modality of
choice for imaging of chronic or recurrent disease.
■ Low dose CT may be used, especially for follow-up imaging.
■ If there is suspicion of complicated acute sinusitis clinically, then contrast
administration will be required.
■ NCCT should be performed only after adequate dose of antibiotics and
resolution of symptoms of acute sinusitis.
■ Also, it is advocated that after nasal blowing, nasal decongestants may
be instilled 15 minutes prior to the scan. is is, however, not universally
advocated.
Magnetic Resonance Imaging (MRI)
■ Contrast enhanced MRI is the preferred modality when complications of
acute sinusitis are suspected.
■ However, not a preferred modality for chronic sinusitis as it can lead to
underestimation of the disease. Also, calcication, air and long standing
desiccated secretions all appear similar (signal voids).
ACUTE SINUSITIS
■ Allergic or infective in etiology.
■ Imaging is seldom indicated unless complications suspected.
■ Plain radiographs: Sinus opacication/air uid levels are seen.
■ CT/MRI: Mucosal thickening with submucosal edema and/or secretions
within the sinuses. Acute secretions being mucoid in nature have an
attenuation similar to water (up to 25 HU). Interspersed lucencies due to
air bubbles/an air uid level (Fig. 4.2) may be seen, which is considered
characteristic of acute sinusitis.
■ On MRI, acute secretions appear hypointense on T1WI and hyperintense
on T2 weighted images.
■ While an air-uid level may be seen in acute sinusitis, its presence does
not necessarily imply acute sinusitis. ere can be several causes for it
(Table 4.1).
59Chapter 4 Imaging in Rhinosinusitis (Inammatory Diseases)
Complicated Acute Sinusitis (Figs. 4.3 and 4.4)
■ Besides immunocompromised hosts, complications are more frequent
in children.
■ Complications of acute sinusitis (Table 4.2)2 primarily result from extrasinus spread of the inammation.
■ Complications are more severe and more frequent in immunocompromised hosts.
■ Contrast enhanced MRI is required to detail the extent, when orbital or
intracranial spread is suspected.
Section 2 Inammatory Nasal Conditions60
Fig. 4.2: Acute on chronic sinusitis. Air uid level right maxillary sinus (arrow). Hypodense
secretions left maxillary sinus (arrowhead) with hyperdense secretions in left posterior nasal
cavity (asterisk).
Table 4.1: Causes for air-uid level.
1. Acute sinusitis
2. Recent trauma
3. Recent surgery
4. Antral lavage or oroantral stula
5. Hemorrhage in coagulopathies
6. Barotrauma
7. Sinonasal polyposis
8. Children who have been crying
■ Fat-suppressed T1 weighted images best delineate extent.
■ Orbital complications
• More frequent in children than in adults.
• Inammatory edema results in swelling of eyelid. As the inammation
progresses, it may result in orbital cellulitis, subperiosteal and orbital
abscesses.
61Chapter 4 Imaging in Rhinosinusitis (Inammatory Diseases)
A
Figs. 4.3A and B: Complications of sinusitis—cellulitis and periostitis. Right maxillary
mucosal disease (white arrow) with erosion of posterior wall (arrowhead). Ill-dened soft
tissue in inferior orbital ssure (asterisk) and retroantral fat (black arrow).
A
Figs. 4.4A and B: Intracranial complications of sinusitis—meningitis and cerebral
abscesses. Left ethmoid and sphenoid mucosal enhancement with secretions (white
arrows). Erosion of zygomatic bone with subperiosteal abscess (arrowhead). Abnormal
meningeal enhancement along left temporal lobe (asterisk). Multiple small ring enhancing
lesions s/o intra-axial abscesses left temporal lobe (black arrow).
B
B
■ Intracranial complications
• In case of frontal sinus involvement, there can be spread of infection
to orbit and also intracranially through its posterior plate (when
periostitis/osteomyelitis develops).
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