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LEGEND: + - border
of maxillary sinus, * - maxillary sinus ostium, U -
uncinate process, E - ethmoid sinuses, IT- inferior
turbinate, MT- middle turbinate, S - septum, C -
concha bullosa.
Note that the CT
scan is a computerized X-Ray taken in the same way
as the first diagram is drawn, as if you were able
to look head on into the sinuses.
On the CT scan,
bone appears white, air appears black, and soft
tissue, fluid, or muscle is varying shades of gray.
Of note in the bottom portion of the scan is a ray
pattern emanating from the teeth. This is as a
result of poor penetration of the x-rays through
the metal in the teeth.
When evaluating the
sinuses for sinusitis, notice the thickening of the
lining of the sinus. Note on the patient's left
side (your right) at the + sign, there is a very
sharp distinct border between the black air in the
maxillary sinus and the white bone. As you will see
later, sinusitis is manifested by grayish
thickening of the lining of the sinus.
The asterisk (*) is
at the point where drainage occurs from the
maxillary sinus into the nose through part of the
ostiomeatal unit. The maxillary sinus ostia is
bounded below by the uncinate process (U) and above
by the lower bony portion of the ethmoid sinuses
(E). A narrowing in this area obviously can be very
critical. The ethmoid sinuses, as can be seen, are
much smaller than the maxillary sinuses.
On the right side
(your left), one can see the middle turbinate (MT)
as well as inferior turbinate (IT). There is a
slight deviation of the septum (S) to the right
side (your left), but in this case it is unlikely
that it is causing any obstruction. Of note is that
there is air contained in the middle turbinate on
the left (C-short for concha bullosa). This
represents a normal anatomical variant in which the
ethmoid sinuses have pushed down into the middle
turbinate. In this case, it does not appear to have
caused a problem, but often it will cause a
significant enlargement of the middle turbinate and
consequently an obstruction on one side of the
nose.
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