Paransasal Sinuses Home Edition
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Paransasal Sinuses Home Edition Paransasal Sinuses Home Edition Presentation Transcript

  • What is a sinus?
    • Cavity within a bone
    • Canal or passageway leading to an absess
    • dilated channel for venous blood
    • any cavity having relatively narrow opening
  • 57 different kinds sinuses in human body!
    • Heart
    • Ankle
    • Brain
    • Coccyx
    • Spleen
    • Kidney
    • Uterus
    • Anus
    • Skull- around the nasal cavity known as….
  • Paranasal Sinuses Each sinus is name after the bone it resides in!
  • Lateral Aspects of Sinuses
  • Development
    • Start as small sacs around nasal meatus & recesses
    • Grow – invading bone- forming air sinuses and cells
    • Maxillary seen at birth
    • By age 6 or 7 frontals & sphenoids
    • distinguish themselves
    • Ethmoids around puberty
    • All full developed age 17- 18
    • All sinuses communicate nasal cavity and each other
  • Functions of Paranasal Sinuses?
    • Not definitely known!- but speculated:
    • decrease weight of skull
    • resonating chamber for voice
    • help warm and moisten air
    • act as airbags in trauma
    • possibly control immune system
  • Paranasal sinuses are joined to nasal cavity via small orifices called Ostia (harbour city of ancient Rome)
    • Ostia easily blocked by allergic inflammation or swelling of nasal lining drainage of mucous is disrupted
    • Sinusitis may result!
  • What is Sinusitis?
    • Inflammation of sinuses- caused by bacterial infection of membrane lining- can fill with pus!
    • Usually from common cold (after first attack, recurrence more likely)
    • Can spread from upper tooth infection
    • Jumping in infected water without holding nose
  • Symptoms of Sinusitis
    • Loss of smell
    • Fever
    • Fullness or tension
    • Pain
    • 37 million Americans suffer every year
    • Decongestion opens up ostia to restore drainage
  • Sinusitis Video (Click on icon)
  • Conditions aggravating Sinusitis
    • Scuba diving
    • Chlorinated swimming pools
    • Drinking alcohol
    • Airplane rides (vacuum)
  • What is Ex-u-date? ( Something that exudes!)
    • Heavy, semi-gelationous material that likes to cling to walls of sinuses (Mucous)
    • Allow several minutes for material to layer out if going from erect projection to cross-table projection
    • Clean Image Receptor before and after !!
  • There are 4 sets of Paranasal Sinuses
    • Frontal
    • Maxillary
    • Ethmoid
    • Sphenoid
  • Frontal Sinuses
    • 2nd Largest
    • Usually paired -sometimes one, three or none!
    • Great variation in size and shape-almost never symmetrical (califlower )
  • Frontal Sinuses
  • Maxillary Sinuses
    • Largest (think Maxi mum!)
    • Two, symmetrical but vary in size and shape from person to person
    • Can be seen at birth
    • Apices at bottom of sinus!
  • Ethmoid Sinuses
    • Paired
    • Divided into 3 groups-
    • anterior- 2-8 cells
    • middle- 2-8 cells
    • posterior 2-6 cells
    • 6-22 possible
    • each side
  • Sphenoid Sinuses
    • Paired (sometimes one)
    • Great variation in size and shape
    • Asymetric
    • Directly below Sella turcica
  • Sinuses should always be performed upright with horizontal beam
  • Horizontal Beam Beam angles up 45 degrees
  • Beam projected straight downward
  • If patient can not sit or stand upright, what is an alternative method for getting equally useful views? CrossTable Lateral or Dorsal Decubitus
  • To see an anterior posterior projection-- A Lateral Decubitus!-- As long as beam is horizontal , a fluid level can be demonstrated!
  • All sinuses views are performed-
    • With a 40 “ SID
    • Collimated to area of sinuses
    • Erect (or crosstable)
    • 8X10 cassette
  • 4 Basics Projections of Sinus Series
    • PA Axial (Caldwell)
    • Parietoacanthial (Waters)
    • Lateral
    • SMV (basilar)
  • PA axial (Caldwell method) Incorrect! Beam should not be angled- must be horizontal! X
  • For proper PA axial of sinuses, either tilt IR 15 degrees forward Or keep IR vertical, but extend pt.’s head back 15 degrees
  • PA axial (Caldwell)
    • beam exits at nasion
    • interpupillary line horizontal
    • midsagital plane perpendicular to IR
    • 8X10 cassette
    • Collimated to sinuses
    Best projection for Frontal sinuses!
  • How to Judge if you have a good Caldwell projection?
    • No rotation (equal distance between lateral border of skull and lateral border of orbit )
    • Petrous ridges in lower 1/3 or orbit
    • Close beam colimation
  • Parietoacanthial Projection Waters Method
  • Parietoacanthial projection (Waters)
    • Horizontal beam exits at acanthion
    • chin touches IR, nose extends back 1/2” from IR
    • Angle of orbito-meatal line is 37 degrees
    • (mento-meatal line is perpendicular to IR)
    Best projection for Maxillary sinuses!
  • Proper Waters Position OML is 37 degrees to IR (cassette) Not OML 37 deg. to CR !
  • Improper Parietoacanthial Position
    • Nose is touching-thus OML is not 37 degrees to IR
    • This is actually a “ Modified” Waters for imaging orbits, nasal bones
  • An Under - extended Waters projection
    • Petrous ridges do not sit directly below apices of Maxillary sinuses!
    • Head needs to be extended back further
    • Does patient have sinusitis?
  • Open-mouthed Waters for Sphenoid Sinus (Board Question)
  • Lateral Projection Shows all 4 sets of sinuses at once!
    • Shows all 4 sinus groups, - mainly for sphenoid
    • Similar to lateral skull, but collimate to anterior half of skull
    • CR ½” – 1” posterior to outer canthus furthest from film
    • CR parallel to floor
    Lateral Sinus projection
  • Evaluation Criteria - Lateral Sinus
    • No rotation of sella turcica
    • Superimposed orbital roofs
    • Close beam restriction
  • SMV (basal) projection Demonstrates Ethmoid & Sphenoid sinuses best!
  • SMV - Sinuses
    • Similar to skull, but collimated to anterior 2/3 of skull
    • CR horizontal, perpendicular to I OML
    • CR enters 3/4 anterior to level of EAM
  • If patient can’t extend head back enough--
  • Alternate SMV Position?
    • Often times, better to omit SMV, depending on patient’s condition & age
    • Beam not horizontal!
  • Evaluation Criteria - SMV Sinuses
    • Equal distance from lateral border of skull to mandibular condyles on both sides
    • Mental protuberance superimposes Frontal bone
    • Condyles anterior to petrous pyramids
  • Is this an acceptable Waters projection ?
    • No!
    • Apices of Max. sinus must be immediately above petrous pyramids
    • The head is underextended!
  • How about this Waters?
    • No!
    • Head over extended!
    • Frontal and maxillary sinuses are foreshortened
    • Apices too high above petrous ridges
  • Technical Factors very important with sinuses!
    • More critical & misleading than any other part of body
    • Under penetration-miss pathology or simulate false conditions
    • Over penetration- burn out pathology
    • Need to see both bony structure and soft tissue
  • Overpenetrated Waters
    • Where is the frontal sinus?
    • A bit overextended as well
    • Remove dentures!
  • Underpenetrated Is there fluid in apices or not?
  • Should you shield?
    • Federal government has reported placing a lead shield over a pt.’s pelvis does NOT significantly reduce gonadal exposure during skull imaging
    • Do it anyway!
  • Best way to reduce Pt. expose to Radiation?
    • Proper collimation!
    • Also, infants and children should receive shielding of thymus (lymph gland in chest-later disapears) and thyroid glands, as well as Gonads
    • Double shield pregnant women