Views;Waters,caldwell,lateral,submental vertexFeaturesOpacification of nasal cavity and sinuses
SSCT IS THE MODALITY OF CHOICE CT is of value for determining anatomical landmarks and variants,to identify erosive changes,e xcellent to determin intraorbital extension of sinonasal disease upto the ventral 2/3rd of the orbit. when disease approaches apex…MRI is next step to assess spread to the cavernous sinus and intracranial extension. Non enhanced CT is performed…value of NECT is the following;if u see an opacified sinus with hyperdense content it is usually a benign disease.hyperdensities are due to,blood,fungus,inspissated secretions. FEATURES1. Hypodense polypoidal,rounded masses in the nasal cavity and paranasal sinuses enlarging sinus ostium .
2.Expansion of the sinuse,thining of sinus walls,nasal and ethmoid septa.3.Bulging of the lamina papyracea leading to displacement of the eyeballs and hypertelorism4.Widening of the infundibulum.5.On post contrast images show peripheral or occasionally solid heterogenous enhancement.6. Erosive changes at anterior skull base.
Reserved for difficult cases especially where is doubt about the pathology on SSCT. MRI is also useful to assess any intracranial or orbital involvement.
Benign antral polyp which widens the sinus ostium and extends into nasal cavity;5% of all nasal polyps. Age Teenagers and young adults Features1. Antral clouding2. Ipsilateral nasal mass3. Smooth mass enlarging the sinus ostium4. No sinus expansion
. A sphenochoanal polyp is a solitary mass of low attenuation on computed tomographic (CT) scans that arises from the sphenoid sinus and extends through the sphenoid ostium, across the sphenoethmoid recess, and into the choana (the boundary between the nasal cavity and nasopharynx). Contiguous axial or coronal magnetic resonance and CT images help clearly differentiate the rare sphenochoanal polyp from the more common antrochoanal polyp. The sinus of origin is important to identify, as the surgical approach depends on the target sinus.
Sinusitis(air fluid levels,total opacification,enhancement pattern,hyperintense secretion on T1WI,rim enhancement on post gad) Cancer(solid central enhancement). Fungal disease(focal or diffuse areas of increased attenuation on ct,signal voids on mri,rim enhancement on mri). Juvenile angiofibroma(involvement of pterygopalatine fossa).
Mucocele is end stage of a chronically obstructed sinus…………an obstructed,airless,mucoid filled expanded sinus.Location;Frontal(60%),ethmoid(30%).maxillary(10%),sphen oid (rare)CAUSES. The most common causes of mucoceles are chronic infection, allergic sinonasal disease, trauma and previous surgery.
Soft tissue density mass….having mucoid attenuation. Sinus cavity expansion Bone demineralisation+remodelingat late stage but No bone destruction(DDx from neoplasm) Surrounding zone of bone sclerosis/calcification of edges of mucocele(ch sinusitis).
Macroscopic calcification in 5%(superimposed fungal infection) Uniform thin rim enhancement. Protrusion into orbit displacing medial rectus muscle laterally. Expansion into subarachnoid space…. resulting in CSF leaking.
X-ray ;will show an expansion of the sinus cavity with loss of the scalloped margin of the normal sinus. Sinus is opaque than normal due to secretions but may on occasions appear more radiolucent if bone destruction is marked. CT;will show the full extent of expansion and is usually enough to make the diagnosis. MRI;may be used to assess the intracranial extent.
Clinically more obvious as palpable mass at medial canthus of eye,proptosis,epiphora..expansion on lacrimal sac. Majority are found in the anterior ethmoid cells,expansion of the posterior ethmoid cells are less common and are associated with sphenoid mucoceles.
Rare Involvement of optic nerve,cavernous sinus and 3rd nerve is common due to proximity to these structures. Imaging plays a key role in diagnosis and its important that condition be recognized by the radiologist at an early stage and dealt surgically before vision is compromised. CT and MRI show rounded or partially rounded expansion of the sphenoid sinus as opposed to the destruction of bone in situ caused by malignancy.
Signal intensity varies with state of hydration,protein content,hemorrhage,air content,calcification,fibrosis. Hypointense on T1W1+signal void on T2W1 due to inspissated debris+fungus. Hydrated secretions are hypo on T1W1 and hyperintense on T2W1. Peripheral enhancement pattern(DDx neoplasm).
Fungal disease of the paranasal sinuses is usually diagnosed when an apparent routine infection fails to respond to normal antibiotic treatment. Acute invasive fungal sinusitis;is the most aggressive form of fungal sinusitis.it is seen in immunocompromised patients and source of morbidity and mortality. Clinical features;are rapid development of fever,facial pain,nasal congestion and epistaxis.
Extension into orbit,cavernous sinus and intracranial compartment results in decreased vision.proptosis and neurological deficits. Pathology ;originates in the nasal cavity mostly in the middle turbinate with subsequent spread into the paranasal sinuses.a number of fungal agents are implicated..1. Aspergillus2. Rhizopus3. Mucor4. Absidia
Ethmoids,maxillary antra are commonly involved,sphenoid sinus may be occasionally involved,frontal sinuses are rarely affected. Mucosal thickening:hypoattenuating Bone destruction:extensive/subtle Fat stranding outside of sinus..intraorbital,pterygopalatine fossa,masticator space. Punctate calcifications….diffuse,nodular or linear
MRI is the modality of choice to asses soft tissue extension. The findings within the sinus itself are variable, and range from mucosal thickening, to complete opacification of the sinus. T1 : intermediate low signal T2 fungal mass is of intermediate to low signal often associated with fluid / blood elsewhere in the paranasal sinuses T1 C+ (GAD) : peripheral enhancement only Hypointense on all sequences due to paramagnetic effect of heavy metals …… high fungal mycelial iron,magnesium,manganese content from amino acid metabolism…DDx from inspissated secretions/polypoid disease. Low signal on T1 and T2 when there is fibrosis.