الفهرس 
Gross AnatomyOnly 14 pages are availabe for public view
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Abstract
The radiological examination ofthe sinonasal cavity is difficult
because of the complicated surrounding bony structures .
Conventional radiographic techniques are important in the evaluation
of sinus disease, as a general survey of the bony and soft tissue
changes.
However, the details of soft tissue involvement and the fine
details of the bony changes are poorly seen on plain radiographs .
Conventional radiography has been largely replaced by CT .
Computed tomographic sections are clear of overlying structures and
can demonstrate the bony framework and the normal soft tissue
structures .
CT is useful in a wide spectrum of sinonasal lesions :
Congenital anomalies, trauma, inflammations and neoplasms . In case
of congenital anomalies, coronal CT reveals in detail the sinus
configuration . In addition, it also shows the associated changes in the
orbit, skull and the brain as for example, in encephalo-menigoc des.
CT is the primary diagnostic imaging modality used in the
evaluation of complex facial trauma after routine screening films are
obtained, due to its superior contrast resolution which also allows
direct visualization of soft tissue .
Different sinonasal lesions often simulate each other both in
their clinical and radiographic presentation. The early symptoms of
chronic rhinosinusitis (nasal obstruction or discharge) are identical to
those caused by neoplasms or infections confined to the sinonasal
cavity . CT scan should be performed ~hen a patient with known
rhinosinusitis develops ominous new symptoms such as epistaxis,
facial swelling, persistent facial pain, facial numbness, ocular
dysfunction or proptosis .
CT is preferably perfonned after the acute excerbations of
recurrent sinusitis have been optimally treated medically in order to
better demonstrate the underlying cause of recurrent or persistant
inflammation.
CT is also valuable, in visualization of tumonr extension to
important areas such as the infratemporalfossa, orbit, pterygopalatine
fossa, nasopharynx and intracranialcavity .
Coronal CT cuts demonstrate the anatomical details in an
orientation more or less similar to and very helpful in endoscopic
assessment and management. Accordingly,coronal CT has a greater
importance for the preoperative assessment of patients for endonasal
endoscopic surgery and follow up of surgicalnasal diseases .
CT is of particular value in the assessment of patients with
persistant complaints after sinus surgery . The most common cause of
failure in therapy directed at the major sinuses has been persistant
etlnnoid diseases . In these cases, CTis mandatory because
inflannnatory changes in the middle meatus are poorly seen on plain
radiographs .
CT is also indicated when a conventionalsinus series show
sinonasal opacification with bone destruction . The information
obtained in these cases prove essential in surgical planning by
demonstrating early involvement of adjacent structures such as the
orbits or cranial cavity . With CT, it is possible to identify osseous
involvement of the orbital wall and extension of the tumour into the extraocular muscles.