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
What are the different types of facial injuries?
Fractures of the zygomatic region
Fractures of the nasal region
LeForte #
Orbital ‘blowout’ fractures
Define Le Fort Fractures
Severe bilateral horizontal fractures of the maxillae resulting in an unstable detached fragment
LeForte I – horizontal # thru the tooth bearing segment of the maxillae
LeForte II – thru the middle third of the face, inside and below the malars
LeForte III – separation of the whole of the bony face from the skull (from the frontomalar suture, along the floor of the orbit, across the lower orbital margins, along the anterior wall of the antrum and across the lateral antral wall to the pterygoid region. Can also be across the cribriform plate)
What are orbital blowout fractures?
Naso-orbital fracture tends to consist of a comminuted, depressed fx involving nasal bones, ethmoid sinuses, maxillary sinus and medial orbital walls.
Tear drop deformity: Radiographically, fragments may be seen in the maxillary sinus or there may be opacification of the maxillary sinus with blood.
What are the radiographs for facial bones?
PA Caldwell 25 degree
Parietoacanthial (OM)
Modified Parietoacanthial (OM30o) (for anterior floor of anterior orbit)
Lateral
Parietoacanthial (OM)
Position I & P patient sits facing the vertical table/bucky, with head tilted back and nose & chin resting on IR Arms relaxed by side or holding bucky for support MSP central to & at 90o to table Raise chin until RBL 53o from horizontal Centre Point To pass thru the acanthion/nose-lip junction CR HCR Film Size 18x24cm crosswise Respiration Arrested
Superimposed frontal sinuses Maxillary sinus Orbital floor Zygomatic arches Nasal septum
Modified Parietoacanthial (OM30o) (for anterior floor of orbit)
Patient positioned as for Waters (OM)
MSP is 90o to IR plane
OML: chin extended so it makes an angle PA 45o-40o with IR plane
CR is 30o caudad CP is thru the vertex of skull to exit just posterior to acanthion Cassette 18x24cm lengthwise displaced to allow for tube angle Suspend respiration
Demonstration
MAINLY inferior
orbital margins
zygomatic bones and arches
maxilla
nasal bones
Specifically for anterior floor of orbit fracture
SPECIFICALLY FOR ANTERIOR FLOOR OF ORBIT FRACTURE
Lateral facial bone projection
Position as for Lateral sinus
Sphenoid sinus Superimposed frontal sinuses Ethmoid Maxillary sinus Sella turcica Orbital roof
Patient erect, or seated in anterior oblique position/ semi-prone
Head in lateral position
MSP is parallel to IR
IPL is 90 to film plane
IOML is perpendicular to front edge of the IR
CR: is HCR CP: midway between outer cathus & EAM Cassette: 18x24cm lengthwise Suspend respiration
Demonstration facial bones overshadow each other shows gross displacements fluid levels (if erect) line of occlusion of teeth lateral mandible lateral orbital margins floor of maxillary sinus
What supplementary radiograph would you do for a facial bone?
Modified Parietoacanthial (modified Waters) OMBL is 55o angle to IR (shows floor of orbit more clearly an regular OM
What are the clinical indications for orbits?
? Fracture ? Foreign body investigation of sight disorders diplopia (double vision) variations in size enlarged tumor anuerysm narrowing Pagets exopthalmos
What is exopthalmos?
Abnormal protrusion of eyeballs
What is a tripod fracture?
Complex fractures of the zygoma from it’s 3 major bony attachments
- orbital
- temporal
- maxillary
Why would you do a slit 25 degree caldwell xray for an orbit?
A Slit 25o Caldwell (PA) is routinely performed for ?Metallic FB prior to MRI.
