Skull I (PNS) Flashcards
What is the four pairs of sinuses
Maxillary
Frotnal
Ethmoidal
And sphenoidal sinuses
Ostiomeatal complex
Common channel that links the frontal, anterior and middle ethmoidal, and the maxillary sinuses to the middle meatus that allows air flow and mucocilliary drainage
The posterior ethmoidal sinus is emptying to:
Superior meatus
Sphenoidal sinus opens to:
Sphenoethmoidal recess
Imaging modalities of sinuses
Plain radiography
CT (Gold standard)
MRI (primary investigation)
Plain radiography in sinus can:
• Evaluate normal sinuses (tranradiant or translucent bc air)
Show mucosal thickening, air fluid level, bone destruction and fracture.
Plain radiography veiws for sinuses:
• Water’s view (occipitomental view) or (nose chin position)
• Lateral view
Water’s view is best for
Maxillary sinuses
And can be taken with open mouth to visualize sphenoid sinus
Lateral view can visualize:
• Anterior and posterior extent of sphenoid, forntal, and maxillary sinuses.
• Ethmoidal sinuses
• sella turcica
Muscoal thickening can be recognized by
Noting the soft tissue interface b/w the air and bony wall
Mucosal thickening can be …. or …. (shape)
Smooth in outline
Or polypoid
Cuases of mucosal thickening
Allergy
Infection
Causes of opaque sinus
Infection
Allergy
Mucocele
Antrochoanal polyp (maxilla…sin)
Truama with hge
Carcinoma of sinus or nasal cavity
Sinusitis can occur in any sinuses but most frequently:
Maxillary > ethmoidal > frontal > sphenoidal sinus.
Types of sinusitis
Infectiuous (acute, sub.., chronic)
Non-inf(allergic)
Dental infection and sinusitis (20 maxill)
Radiographic features of acute sinusitis
Opacified sinus (partial or complete)
Mucosal thickening
Air-fluid levels (diagnostic for acute)
Radiographic features of chronic sinusitis
Mucosal thickening
Hyperostosis of bone
Talk about Role of CT and MRI in acute sinusitis
It is usually diagnosed and treated clinically, but CT is recommended for symptoms persist.
Both CT and MRI can elegantly demonstrate mucosal thickening and fluid levels as well as displaying the bony walls of the sinuses.
Just for mcq knowledge
Radiographic features of fungal sinusitis
Usually with hx of : DM, steroid, and Ab, (immune compromised)
• Bony destruction and rapid extension into adjacent anatomical spaces
• indistinguishable from tumor (req biopsy)
• main role kf CT/MRI is to determine the extent of the disease
• Aspergillosis may appear hyperdense on CT.
Sinus Mucocele becomes symptomatic when :
When it extends into surrounding tissue planes secondary to remodeling of the surrounding bone erosion
useless information
Most common sinus involvement of mucocele
Frontal (67%) > ethmoidal (20%) > maxillary (10%) > sphenoidal (3%)
What is sinus Mucocele
A largely clinically silent mucus-containing expansile lesion of the paranasal sinus with 2ry obstruction of the main ostium of affected sinus.
Lined by cilliated columnar respiratory epithelium.
Radiolographic features of sinus mucocele
Diffuse opacification
Remodeling of the bony walls with cortical erosion
High T1 and T2 (on flair) signal
Abnromal contrast enhancement
What is sino-nasal polyposis
It is the presence of multiple begin polyps in the nasal cavity and paranasal sinuses
Radiographic features of sino-nasal polyposis
• Opacification of PNS
• Thinning of septa
• fluid density lesion
• high T2 signal
• peripheral enhancement on T1+C
• secretion of higher density
•No disruption of adjacent structures
Other signs of chronic sinusitis
Signs of antro-choanal polyp
Unilateral opacification of the maxillary antrum and the frontal and anterior ethmoidal sinuses dt obstruction of their drainage pathways
Most common type of PNS tumor and most common location
Squamous cell carcinoma (90%)
Maxillary (80%)
Both CT and MRI imp in PNS tumor
CT is superior at visualing bone destruction
MRI is preferred for demostrating tumor invasion by showing the extent of any soft tissue mass beyond the sinus cavity.
In all opaque sinus, Particularly the antra, special attention should be paid to the bony margins on CT. Why?
Because if these are destroyed; a dx of carcinoma needs exclusion
Radiographic features of PNS tumor
• Soft tissue mass with patchy (heterogeneous)postcontrast enhancement
• bony eall destruction
• Aggressive regional spread (invasion)
• low T1 signal
• intermediate (isointense) T2
• patchy orHeterogeneous enhancement
Sinus trauma
• Hx of Trauma:
• May comes with fracture of sinus wall + hge (high density) and opacification
• on CT: depressed fracutre may present, mucosal thickening and air-fluid level (blood).
