Two skull projections
- a lateral view with a horizontal beam
second view depends on area of injury:
- occipital injury: TOWNES
- any other injuries: AP
do not require an AP and a townes
what is the most common accessory suture remaining in adults?
the metopic suture: joining anterior aspect of frontal bones/fontanell to the naison
Vascual appearances on skull
- (colour and why?)
- (branch size?)
- (sclerotic?)
- vascualr markings appear grey on image rather than black. only the inner aspect of the skull is thinned, not the whole way through. # would most commonly appear black
- branches gradually decrease in size; # are uniform in size
- vascualr markings have well defined sclerotic margins; # does not
Steps to assess a SXR
Step 1: scrutinise the area corresponding to the site of the injury
Step 2: look for abnormalities:
- lucent linear #?
- depressed #? - a dense white area or parallel white lines due to overlapping bone
- fluid level in the sphenoid sinus? - indicates haemorrhage, or CSF in sinus and suggests a base of skull #
step 3: VERY RARE: intracranial air (can see cerebral sulci) indicates a # of a frontal sinus or sphenoid sinus
Fluid in the sphenoid sinus
- appears different depending on the patient position
- indicates that there is a basal skull #
Normal Paediatric Sutures
- sagittal
- coronal
- lambdoid
- squamous
- innominate is visible in children but not adults
accessory sutures:
- metopic
- accessory parietal
- mendosal
Paediatrics
suture or #?
principle 1:
- wide sutures are normal in neonates (baby)
principle 2:
- accessory sutures can be present at varying ages
Assessing a paediatric SXR
Step 1: scrutinise the area corresponding to the site of the injury
Step 2: look for abnormalities:
- lucent linear #?
- depressed #? - a dense white area or parallel white lines due to overlapping bone
Assess the frontal projection
- trace the lambdosal suture (common to have wormian bones present in this suture)
- the lambdoid suture meets the sagittal suture in the midline. the frontal projection makes the sagittal suture appear foreshortened
- trace the sagittal suture. it should stop when it reaches the coronal suture, if not the patient may have a metopic suture (an accessory suture)
Examine the parietal bone
- may be present on the frontal projection
- tend to travel superiorly from the lambdoid suture
A SQUOMOUS SUTURE ON A TOWNES PROJECTION CAN APPEAR LUCENT LIKE A # AS IT IS PROJECTED TANGENTIALLY
Assess the lateral paediatic SXR
- (what sutures can you see and which ones can you not see ?)
- (what is spheno-occipital synchondrosis?)
- sagittal suture is not seen on lateral
- if patient is rotated, coronal and lambdoid sutures may appear as parrallel lines
- squamousal suture comes anteriorly off of the lambdoid suture
- the mendosal suture extends posteriorly from the lamdoid suture
- the inominate suture extends inferiorly from the mabdoid suture
- accessory parietal sutures can be seen on the lateral coming posteriorly of of the coronal suture, or anteriorly off of the lambdoid suture. Can also be seen to come inferiorly from where the sagittal suture is located
-spheno-occipital synchondrosis is a lucent line at the base of skull, posterior to the pituitary fossa - PRESENT IN ALL INFANTS
Lateral Skull Positioning
- detector is on left side of patients head, MSP is parallel to the detector
- no rotatino, temporomandibular joints are superimposed
- centre 4cm superior of EAM
- collimate to include superior skin surface, frontal bone, inferiorly to get base of skull, posterior skin margins
- 60-70kVp 10-20mAs
Townes Positioning
- (what is a townes projection good for showing?)
- good for showing the occipital bone `
