Paranasal sinus

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Slide 1 :

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

Slide 2 :

57 different kinds sinuses in human body! Heart Ankle Brain Coccyx Spleen Kidney Uterus Anus Skull- around the nasal cavity known as….

Slide 3 :

Paranasal Sinuses Each sinus is name after the bone it resides in!

Slide 4 :

Lateral Aspects of Sinuses

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Development Start as small sacs around nasal meatus & recesses Grow – invading bone- forming air sinuses and cells Maxillary seen at birth

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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

Slide 7 :

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

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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!

Slide 9 :

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

Slide 10 :

Symptoms of Sinusitis Loss of smell Fever Fullness or tension Pain 37 million Americans suffer every year Decongestion opens up ostia to restore drainage

Slide 11 :

Sinusitis Video (Click on icon)

Slide 12 :

Conditions aggravating Sinusitis Scuba diving Chlorinated swimming pools Drinking alcohol Airplane rides (vacuum)

Slide 13 :

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!!

Slide 14 :

There are 4 sets of Paranasal Sinuses Frontal Maxillary Ethmoid Sphenoid

Slide 15 :

Frontal Sinuses 2nd Largest Usually paired-sometimes one, three or none! Great variation in size and shape-almost never symmetrical (califlower)

Slide 16 :

Frontal Sinuses

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Maxillary Sinuses Largest (think Maximum!) Two, symmetrical but vary in size and shape from person to person Can be seen at birth Apices at bottom of sinus!

Slide 18 :

Ethmoid Sinuses Paired Divided into 3 groups- anterior- 2-8 cells middle- 2-8 cells posterior 2-6 cells 6-22 possible each side

Slide 19 :

Sphenoid Sinuses Paired (sometimes one) Great variation in size and shape Asymetric Directly below Sella turcica

Slide 20 :

Sinuses should always be performed upright with horizontal beam

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Horizontal Beam Beam angles up 45 degrees

Slide 22 :

Beam projected straight downward

Slide 23 :

If patient cannot sit or stand upright, what is an alternative method for getting equally useful views? CrossTable Lateral or Dorsal Decubitus

Slide 24 :

To see an anterior posterior projection-- A Lateral Decubitus!--As long as beam is horizontal, a fluid level can be demonstrated!

Slide 25 :

All sinuses views are performed- With a 40 “ SID Collimated to area of sinuses Erect (or crosstable) 8X10 cassette

Slide 26 :

4 Basics Projections of Sinus Series PA Axial (Caldwell) Parietoacanthial (Waters) Lateral SMV (basilar)

Slide 27 :

PA axial (Caldwell method) Incorrect! Beam should not be angled- must be horizontal! X

Slide 28 :

For proper PA axial of sinuses, either tilt IR 15 degrees forward Or keep IR vertical, but extend pt.’s head back 15 degrees

Slide 29 :

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!

Slide 30 :

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

Slide 31 :

Parietoacanthial Projection Waters Method

Slide 32 :

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!

Slide 33 :

Proper Waters Position OML is 37 degrees to IR (cassette) Not OML 37 deg. to CR!

Slide 34 :

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

Slide 35 :

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?

Slide 36 :

Open-mouthed Waters for Sphenoid Sinus (Board Question)

Slide 37 :

Lateral Projection Shows all 4 sets of sinuses at once!

Slide 38 :

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

Slide 39 :

Evaluation Criteria - Lateral Sinus No rotation of sella turcica Superimposed orbital roofs Close beam restriction

Slide 40 :

SMV (basal) projection Demonstrates Ethmoid & Sphenoid sinuses best!

Slide 41 :

SMV - Sinuses Similar to skull, but collimated to anterior 2/3 of skull CR horizontal, perpendicular to IOML CR enters 3/4 anterior to level of EAM

Slide 42 :

If patient can’t extend head back enough--

Slide 43 :

Alternate SMV Position? Often times, better to omit SMV, depending on patient’s condition & age Beam not horizontal!

Slide 44 :

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

Slide 45 :

Is this an acceptable Waters projection? No! Apices of Max. sinus must be immediately above petrous pyramids The head is underextended!

Slide 46 :

How about this Waters? No! Head overextended! Frontal and maxillary sinuses are foreshortened Apices too high above petrous ridges

Slide 47 :

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

Slide 48 :

Overpenetrated Waters Where is the frontal sinus? A bit overextended as well Remove dentures!

Slide 49 :

Underpenetrated Is there fluid in apices or not?

Slide 50 :

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!

Slide 51 :

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

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