sinuses Flashcards
Why must patients be erect with a HCR when conducting a sinus view?
To demonstrate all the paranasal sinuses free of overlying bony structures
No single radiograph will demonstrate all sinuses, a number of projections may be taken.
Demonstrates fluid level(s) which may represent retained fluid after sinusitis or blood following trauma
What is the function of the maxillary sinuses? Properties of maxillary sinus.
Site of communication into nasal cavity located at superior medial aspect of the sinus cavity.
Thin cortical bone. Sizes vary but symmetrical. On periapical radiographs you see the sinus floor at the apices of molars and premolars. They extend down towards the crest of the alveolar ridge = edentulous areas.
Properties of the frontal siuses
Located between inner & outer tables of skull, posterior to glabella
Rarely become aerated before age 6.
Properties of the ethmoid sinuses
within lateral masses of labyrinths of ethmoid bone
Grouped into anterior, middle & posterior collections, all intercommunicate
Osteomeatal complex
A channel that links the frontal sinus anterior and middle ethmoid sinuses and maxillary sinus to the middle meatus that allows airflow and mucocilliary drainage.
most important sinus opening.
Any process that causes blockage in this sensitive area can occlude other sinuses that drain into osteomeatal complex. When obstruction occurs, mucus is retained in sinus cavity.
Stagnant secretions thicken & provide medium for bacteria.
What is the septae of the maxillary sinus?
Radiopaque lines traversing the sinus either horizontally or vertically are septae, bony projections from the floor and wall of the antrum.
Septae give the sinus an appearance of being divided into compartments, although this is not the case.
How would you distinguish between the nodules of the maxillary sinus and the root tip of teeth?
a nodule will show trabecular pattern while a root tip will not.
What else is at premolars other than the maxillary sinus floor?
The zygoma appears as a U-shaped radiopaque line with the round portion superimposing area of 1st and 2nd molars.
What do you want to see on a SMV radiograph?
Foramen magnum Mandible Sphenoid and Ethmoid sinus Petrous ridges Base of skull Lateral margins of skull
What are the clinical indications for doing facial bones xray? some cocoa crap picd
Complications of infection
Osteomyelitis
Empyema
Mucocele
Cysts and tumors
Osteomata
Ca Antrum
Sarcoma
Inflammatory
Rhinitis
Coryza
Rhinorrhoea
Allergic changes
Cat fur
Pollens
Dust
Polyps may form as a sequel to infection & allergies
Contraindications for sinus xrays
Pregnancy
Previous sinus xrays
What are the radiographs you take for sinuses?
Lateral position
OM Parietoacanthial (Waters method) or open-mouth waters
PA 25 degrees(Caldwell) -
SUPPLEMENTARY
Submentovertex (SMV)
OM Parietocanthial (open mouth waters)
f
Normal aerated sinuses and orbital shadows should be same density
Which sinuses are demonstrated with lateral, caldwell and OM waters
F, S, E, M
F, E, M
F, S, E, M
What is the center point and respiration for lateral sinuses?
CP: 2.5cm posterior to outer canthus of eye. (can be done on slow inspiration to highlight maxillary sinus)
In a lateral sinus xray what needs to be demonstrated?
facial bones overshadow each other show gross displacements fluid levels (if erect) line of occlusion of teeth lateral mandible lateral orbital margins floor of maxillary sinus
OM - Parietoacanthial Projection/Waters
Position
PA
I & P patient sits facing vertical table/bucky, w/ head tilted back & nose & chin resting on or near IR
Arms relaxed by side or hold IR for support
MSP 900 to IR
Raise chin until IOMBL 37 - 53o from horizontal
OML makes angle PA 45-40 degrees to IR plane
CR is 90 to IR plane (HCR)
CP is thru posterior skull to exit at level (acanthion)
Cassette
18x24cm lengthwise
Suspend respiration
mml 0 degrees
Demonstration orbits zygomatic bone nasal septum maxilla, maxillary sinuses - fluid levels Petrous ridges below floor of maxillary sinuses Oblique Radiographs Frontal sinus Sphenoid sinus thru open mouth
Too much extension, ridges appear considerably below the sinuses and maxillary sinuses are foreshortened
EXPOSURE
Density (mA) & rad contrast (kV) allows visualisation maxillary & sphenoid sinus
Bony trabeculae seen
What happens when patient can’t bring chin up for a OM waters projection?
If patient unable to bring chin up
Do not tilt CR - it obscures fluid levels
Magnification due to OFD
Greater dose to eyes
AP view, tilt head back
OM open mouth projection
Patient is positioned as for an extended Waters projection. Mouth is opened as wide as possible.
CR is directed horizontally
CP is thru posterior of skull to exit thru the open mouth
Sphenoid sinuses projected thru the open mouth.
(An alternative to SMV)
What are the projections for facial bones?
Projections studied Lateral PA - Parietoacanthial PA Caldwell - 25 degrees Modified OM: 30o caudal (PA Parietoacanthial)
What are the 3 sections of the face?
Bones of face can be divided into 3 parts
Upper 1/3 – above the superior orbital ridge belongs to the cranium
Middle 1/3 – between the superior orbital ridges & occlusal line of upper teeth
Lower 1/3 – is the mandible
What are the bones of the middle third of the face?
Maxillae & palatine bones above upper teeth
The nasal, ethmoid & lacrymal bones between the orbits
The zygomatic or cheek bones
The sphenoid & frontal bones of posterior and upper walls PAthe orbits
Paired pterygoid processes of sphenoid bone lying directly posterior to maxillae
What are the clinical indication to conduct a sinus x-ray?
Fractures Foreign body Neoplasms Osteomyelitis Sinusitis Secondary Osteomyelitis TMJ syndrome
When do facial injuries occur and what can you infer from them>
Injuries to middle 1/3 of face are usually inflicted during MVA when passengers are thrown forward against a windscreen or dashboard.
They are often subsidiary to more serious injuries & maybe overlooked – particularly as patient may develop severe facial odema
