paranasal sinuses imaging
TRANSCRIPT
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Paranasal Sinuses Imaging
Prof. J. Stelmark
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PARANASAL SINUSES
The large, air-filled a!ities of the "aranasal sinuses are sometimes alled the
aessor# nasal sinuses $eause the# are lined %ith muous mem$rane, %hihis ontinuous %ith the nasal a!it#. These sinuses are di!ided into four grou"s,
aording to the $ones that ontain them&
'.(a)illar# *+ (a)illar# *faial $ones
+. rontal *usuall# + rontal *ranial $ones
. Ethmoid *man# Ethmoid *ranial $ones
/. S"henoid *ranial $one
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0nl# the ma)illar# sinuses are "art of the faial $one struture. The frontal,
ethmoid, and s"henoid sinuses are ontained %ithin their res"eti!e ranial
$ones.
The "aranasal sinuses $egin to de!elo" in the fetus, $ut onl# the ma)illar#
sinuses e)hi$it a definite a!it# at $irth. The frontal and s"henoid sinuses
$egin to $e !isi$le on radiogra"hs at age 1 or 2. The ethmoid sinuses de!elo"
last. All the "aranasal sinuses generall# are full# de!elo"ed $# the late
teenage #ears.
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(a)illar# Sinuses
The large ma)illar# sinuses are "aired strutures, one of %hih is loated %ithin
the $od# of eah ma)illar# $one. An older term for ma)illar# sinus is antrum, an
a$$re!iation for Antrum of 3ighmore.
Eah ma)illar# sinus is sha"ed some%hat like a "#ramid on a frontal !ie%.
Laterall#, the# a""ear more u$i. The a!erage total !ertial dimension is
$et%een and / m, and the other dimensions are $et%een +.4 and m.
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rontal Sinuses
The frontal sinuses are loated $et%een the inner and outer ta$les of the skull,
"osterior to the gla$ella5 the# rarel# $eome aerated $efore age 1. The ma)illar#
sinuses are al%a#s "aired and are usuall# fairl# s#mmetri in si6e and sha"e5 the
frontal sinuses are rarel# s#mmetri. The frontal sinuses usuall# are se"arated $# ase"tum, %hih de!iates from one side to the other or ma# $e a$sent entirel#,
resulting in a single a!it#.
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Ethmoid Sinuses
The ethmoid sinuses are ontained %ithin the lateral masses or la$#rinths of the
ethmoid $one. These air ells are grou"ed into anterior, middle, and "osterior
olletions, $ut the# all interommuniate.
7hen !ie%ed from the side, the anterior ethmoid sinuses a""ear to fill the or$its.
This ours $eause "ortions of the ethmoid sinuses are ontained in the lateral
masses of the ethmoid $one, %hih hel"s to form the medial %all of eah or$it.
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S"henoid Sinuses
The s"henoid sinuses lie in the $od# of the s"henoid $one diretl# $elo% the sella
turia. The $od# of the s"henoid that ontains these sinuses is u$i and
fre8uentl# is di!ided $# a thin se"tum to form t%o a!ities. This se"tum ma# $e
inom"lete or a$sent entirel#, ho%e!er, resulting in onl# one a!it#.
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PARANASAL SINUSES
Tehnial ators
A medium k9 range of 2: to ;: is ommonl# used to "ro!ide suffiient ontrast ofthe air-filled "aranasal sinuses. 0"timum densit# as ontrolled $# the mAs is
es"eiall# im"ortant for sinus radiogra"h# to !isuali6e "atholog# %ithin the sinus
a!ities. A small foal s"ot should $e used for ma)imum detail.
As %ith ranial and faial $one imaging, gonadal shielding is not useful in reduing
gonadal e)"osure, $ut shields o!er the "el!i area ma# $e used for "atientreassurane. <lose ollimation and elimination of unneessar# re"eats are the $est
measures for reduing radiation dose in sinus and tem"oral $one radiogra"h#.
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LATERAL P0SITI0N=RI>3T 0R LET LATERAL& SINUSES
Pathology Demonstrated
Inflammator# onditions and sinus "ol#"s or #sts.
(o!ing or stationar# grid
? 14 to 24 k9 range
? Small foal s"ot
Tehnial ators
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Part Position
? Plae lateral as"et of head against ta$le@u"right uk# surfae, %ith side of
interest losest to IR.
? AdBust head into a true lateral "osition, mo!ing $od# in an o$li8ue diretion as
needed for "atientCs omfort *midsagittal "lane "arallel to IR.
? Align IPL "er"endiular to IR *ensures no tilt.
? AdBust hin to align I0(L "er"endiular to front edge of IR.
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<entral Ra#
? Align a hori6ontal <R "er"endiular to the IR.
? <enter <R to a "oint mid%a# $et%een outer anthus and EA(.
? <enter IR to <R.
? (inimum SID is /: inhes *':: m.
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Res"iration
Sus"end res"iration during e)"osure.
Notes& To !isuali6e air-fluid le!els, an eret "osition %ith a hori6ontal $eam is
re8uired. luid %ithin the "aranasal sinus a!ities is thik and gelatin-like, ausing it
to ling to the a!it# %alls. To !isuali6e this fluid, allo% a short time *at least 4
minutes for the fluid to settle after a "atientCs "osition has $een hanged *i.e., from
reum$ent to eret.
If "atient is una$le to $e "laed in the u"right "osition, the image ma# $e o$tained
%ith the use of a hori6ontal $eam.
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Strutures Sho%n& ? All four "aranasal sinus grou"s
are sho%n.
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PA PR0JE<TI0N& SINUSES <ald%ell (ethod
Patholog# Demonstrated
Inflammator# onditions and sinus "ol#"s@#sts are sho%n.
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Part Position
? Plae "atientCs nose and forehead against u"right uk# or ta$le %ith nek
e)tended to ele!ate the 0(L '4 from hori6ontal. A radioluent su""ort $et%een
forehead and u"right uk# or ta$le ma# $e used to maintain this "osition. <Rremains hori6ontal. *alternate method if uk# an $e tilted '4.
? Align (SP "er"endiular to midline of grid or u"right uk# surfae.
? <enter IR to <R and to nasion, ensuring no rotation.
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<entral Ra#
? Align <R hori6ontal, "arallel %ith the floor.
? <enter <R to e)it at nasion.
? (inimum SID is /: inhes *':: m.
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Strutures Sho%n& ? rontal sinuses "roBeted a$o!e the
frontonasal suture. ? Anterior ethmoid air ells !isuali6ed lateral to
eah nasal $one, diretl# $elo% the frontal sinuses.
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PARIET0A<ANT3IAL PR0JE<TI0N& SINUSES 7aters (ethod
Pathology Demonstrated
Inflammator# onditions and sinus "ol#"s are sho%n.
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Part Position
? E)tend nek, "laing hin and nose against ta$le@u"right uk# surfae.
? AdBust head until ((L is "er"endiular to IR5 0(L %ill form a 2 angle %ith the"lane of the IR.
? Position the (SP "er"endiular to the midline of grid or ta$le@u"right uk#
surfae.
? Ensure that no rotation or tilt e)ists.
? <enter IR to <R and to aanthion.
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<entral Ra#
? Align a hori6ontal <R "er"endiular to the IR entered to e)it at the aanthion.
? (inimum SID is /: inhes *':: m.
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Strutures Sho%n& ? (a)illar# sinuses %ith the inferior as"et !isuali6ed free
from su"erim"osing al!eolar "roesses and "etrous ridges, the inferior or$ital
rim, and an o$li8ue !ie% of the frontal sinuses
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SU(ENT09ERTEF *S(9 PR0JE<TI0N& SINUSES
Pathology Demonstrated
Inflammator# onditions *sinusitis, seondar# osteom#elitis and sinus "ol#"s are
sho%n.
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Part Position
? Raise hin, h#"ere)tend nek if "ossi$le until I0(L is "arallel to ta$le@u"right
uk# surfae.
? 3ead rests on !erte) of skull.
? Align (SP "er"endiular to midline of the grid or ta$le@u"right uk# surfae5
ensure no rotation or tilt.
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<entral Ra#
? <R direted "er"endiular to I0(L
? <R entered mid%a# $et%een angles of mandi$le, at a le!el 'G to + inhes*/ to 4 m inferior to mandi$ular s#m"h#sis
? <R entered to IR
? (inimum SID of /: inhes *':: m
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Strutures Sho%n& ? S"henoid sinuses, ethmoid sinuses,
nasal fossae, and ma)illar# sinuses.
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PARIET0A<ANT3IAL TRANS0RAL PR0JE<TI0N& SINUSES
0"en (outh 7aters (ethod
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Strutures Sho%n& ? (a)illar# sinuses %ith the inferior as"et !isuali6ed, free from
su"erim"osing al!eolar "roesses and "etrous ridges, the inferior or$ital rim, an
o$li8ue !ie% of the frontal sinuses, and the s"henoid sinuses !isuali6ed through
the o"en mouth.