sinuses

Question 1

Why must patients be erect with a HCR when conducting a sinus view?

Answer 1

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

Question 2

What is the function of the maxillary sinuses? Properties of maxillary sinus.

Answer 2

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.

Question 3

Properties of the frontal siuses

Answer 3

Located between inner & outer tables of skull, posterior to glabella
Rarely become aerated before age 6.

Question 4

Properties of the ethmoid sinuses

Answer 4

within lateral masses of labyrinths of ethmoid bone

Grouped into anterior, middle & posterior collections, all intercommunicate

Question 5

Osteomeatal complex

Answer 5

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.

Question 6

What is the septae of the maxillary sinus?

Answer 6

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.

Question 7

How would you distinguish between the nodules of the maxillary sinus and the root tip of teeth?

Answer 7

a nodule will show trabecular pattern while a root tip will not.

Question 8

What else is at premolars other than the maxillary sinus floor?

Answer 8

The zygoma appears as a U-shaped radiopaque line with the round portion superimposing area of 1st and 2nd molars.

Question 9

What do you want to see on a SMV radiograph?

Answer 9

Foramen magnum
Mandible
Sphenoid and Ethmoid sinus
Petrous ridges
Base of skull
Lateral margins of skull

Question 10

What are the clinical indications for doing facial bones xray? some cocoa crap picd

Answer 10

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

Question 11

Contraindications for sinus xrays

Answer 11

Pregnancy

Previous sinus xrays

Question 12

What are the radiographs you take for sinuses?

Answer 12

Lateral position
OM Parietoacanthial (Waters method) or open-mouth waters
PA 25 degrees(Caldwell) -

SUPPLEMENTARY
Submentovertex (SMV)
OM Parietocanthial (open mouth waters)

Question 13

f

Answer 13

Normal aerated sinuses and orbital shadows should be same density

Question 14

Which sinuses are demonstrated with lateral, caldwell and OM waters

Answer 14

F, S, E, M

F, E, M

F, S, E, M

Question 15

What is the center point and respiration for lateral sinuses?

Answer 15

CP: 2.5cm posterior to outer canthus of eye. (can be done on slow inspiration to highlight maxillary sinus)

Question 16

In a lateral sinus xray what needs to be demonstrated?

Answer 16

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

Question 17

OM - Parietoacanthial Projection/Waters

Answer 17

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

Question 18

What happens when patient can’t bring chin up for a OM waters projection?

Answer 18

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

Question 19

OM open mouth projection

Answer 19

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)

Question 20

What are the projections for facial bones?

Answer 20

Projections studied
Lateral
 PA - Parietoacanthial 
PA Caldwell - 25 degrees
Modified OM: 30o   caudal                            
   (PA Parietoacanthial)

Question 21

What are the 3 sections of the face?

Answer 21

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

Question 22

What are the bones of the middle third of the face?

Answer 22

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

Question 23

What are the clinical indication to conduct a sinus x-ray?

Answer 23

Fractures
Foreign body
Neoplasms
Osteomyelitis
Sinusitis
Secondary Osteomyelitis
TMJ syndrome

Question 24

When do facial injuries occur and what can you infer from them>

Answer 24

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

Question 25

What are the different types of facial injuries?

Answer 25

Fractures of the zygomatic region
Fractures of the nasal region
LeForte #
Orbital ‘blowout’ fractures

Question 26

Define Le Fort Fractures

Answer 26

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)

Question 27

What are orbital blowout fractures?

Answer 27

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.

Question 28

What are the radiographs for facial bones?

Answer 28

PA Caldwell 25 degree

Parietoacanthial (OM)

Modified Parietoacanthial (OM30o) (for anterior floor of anterior orbit)

Lateral

Question 29

Parietoacanthial (OM)

Answer 29

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

Question 30

Modified Parietoacanthial (OM30o) (for anterior floor of orbit)

Answer 30

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

Question 31

Lateral facial bone projection

Answer 31

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

Question 32

What supplementary radiograph would you do for a facial bone?

Answer 32

Modified Parietoacanthial                       (modified Waters)
OMBL is 55o angle to IR (shows floor of orbit more clearly an regular OM

Question 33

What are the clinical indications for orbits?

Answer 33

? Fracture
? Foreign body
investigation of sight disorders
diplopia (double vision)
variations in size
enlarged 
tumor
anuerysm
narrowing
Pagets
exopthalmos

Question 34

What is exopthalmos?

Answer 34

Abnormal protrusion of eyeballs

Question 35

What is a tripod fracture?

Answer 35

Complex fractures of the zygoma from it’s 3 major bony attachments

1. orbital
2. temporal
3. maxillary

Question 36

Why would you do a slit 25 degree caldwell xray for an orbit?

Answer 36

A Slit 25o Caldwell (PA) is routinely performed for ?Metallic FB prior to MRI.