Radiology Flashcards
name radiographs from lowest to highest dose
OPT
full mouth periapicals
CBCT
what are skull radiographs
plain radiographs used primarily for assessing maxillofacial trauma
what are the four main types of skull radiographs
occipitomental
PA mandible
reverse town’s
true lateral skull
what are occipitomental radiographs primarily used for
fractures of the midface
what are PA mandible radiographs primarily used for
fractures of the posterior mandibles - BUT not including condyles
what are reverse Towne’s radiographs primarily used for
fractures of the mandibular condyles
how are occipitomental radiographs usually taken
at two different angles
can be - 0, 10, 30 or 40 degrees
usually pick two numbers not next to one another
what is Water’s view
using two different angles to take an occipitomental radiograph
how is the patient positioned for an occipitomental radiograph
facing receptor
head tipped back so orbitomeatal line is 45 degrees to receptor
x-ray beam positioned at the operator’s chosen degree and centred through the occiput
why are PA mandible radiographs not suitable for viewing facial skeleton
due to superimposition of base of skull and nasal bones
what are indications of PA mandible radiographs
lesions and fractures involving the posterior 1/3 of body of mandible, angles, rami and mandibular hyper or hypoplasia
how is the patient positioned for a PA mandible radiograph
face towards receptor
head tipped forward so orbitomeatal line is perpendicular with receptor (forehead nose position)
x-ray beam perpendicular to receptor and centred through cervical spine at level of rami
why is the x-ray beam projected from posterior side in PA mandible, occipitomental and reverse towne’s radiographs
reduces magnification of the face since the face is closer to the receptor
reduced effective dose needed
what are indications for taking a reverse towne’s radiograph
high fractures of condylar necks
intracapsular fractures of TMJ
condylar hypo or hyperplasia
how is the patient positioned for a reverse towne’s radiograph
face towards receptor
head tipped forward so orbitomeatal line perpendicular with receptor
mouth open so condyle heads move out of glenoid fossa
x-ray beam 30 degrees below perpendicular line to receptor and centred through condyles
what type of radiation does CBCT involve
ionising
how does CBCT machine work
conical/ pyramidal x-ray beam
square digital receptor
rotates around head
no more than 1 full rotation
how is patient positioned for CBCT
machine specific
usually standing but can be sitting
frankfort plane parallel to floor
mid sagittal plane centred
name four benefits of CBCT over plain radiography
no superimposition
ability to view subject from any angle
no magnification or distortion
allows for 3D reconstruction
name four disadvantages of CBCT over plain radiography
increased radiation dose
lower spatial resolution
susceptible to artefacts
equipment more expensive
what are two benefits of CBCT over conventional CT
lower radiation doses
potential for sharper images
what are three benefits of conventional CT over CBCT
able to differentiate soft tissues better
larger field of view
better soft tissue contrast
name four uses of CBCT in dentistry
view proximity of IAN during lower 8 surgery
measuring alveolar bone dimensions for implants
visualising complex root canal morphology
assessing large cystic jaw lesions
name the three orthogonal planes in CBCT
axial
sagittal
coronal
what are three imaging factors/ variables
field of view
voxel size
acquisition time
how are imaging factors/ variables worked out
differs from patient to patient
takes in ALARP principles
what is the FOV
the size of captured volume of data
what is voxel size
the image resolution
voxels are 3D pixels
what does an increase in FOV cause
increase in radiation dose and increase in number of tissues irradiated and increase scatter
what does decrease voxel cause
increases radiation dose
increase scan time
what are the range of options for voxel size
0.4mm cubed to 0.085mm cubed
rate the following x-rays from highest dose to lowest : panoramic, CT, intraoral, CBCT
CT
CBCT
panoramic
intraoral
what are the two main types of artefact
movement artefact
streak artefact
name three contra-indications to CBCT
if plain radiographs are sufficient
high risk of debilitating artefacts
if there is pathology requiring soft tissue visualisation
how should you describe a lesion found on a radiograph
site
size
shape
margins
internal structure
affect on adjacent anatomy
number
how would you describe a lesions general shape
rounded
scalloped
irregular
how can you describe a lesions locularity
unilocular
pseudolocular
multilocular
how can you describe the margins of a lesion
well defined and corticated/ non-corticated
poorly defined and blending into adjacent anatomy
what does a corticated lesion suggest
benign lesion
what does a moth eaten lesion suggest
malignancy
how can you describe the internal structure of a lesion
entirely radiolucent
radiolucent with some internal radiopacity
radiopaque
name four reasons a lesion could present as radiolucent
resorption of bone
decreased mineralisation of bone
decreased thickness of bone
replacement of bone with abnormal less mineralised tissue
why may a lesion present as radiopaque - give four examples
increased thickness of bone
osteosclerosis of bone
presence of abnormal tissues
mineralisation of normally non-mineralised tissues
how may teeth be affected by a lesion present on a radiograph
displacement/ impaction
resorption
loss of lamina dura
widening of PDL
hypercementosis
name five potential causes of a periapical radiolucency
periapical granuloma
periapical abscess
radicular cyst
perio-endo lesion
ameloblastoma
how can infected cysts present on a radiograph
mimic radiographic features of malignancy
check clinically for features of secondary infection
name 6 types of jaw radiopacities
idiopathic osteosclerosis
sclerosing osteitis
hypercementosis
buried retained roots
unerupted teeth
supernumeraries
what is idiopathic osteosclerosis
localised area of increased bone density of unknown cause
is asymptomatic and often an incidental finding
can be relevant to ortho
how does idiopathic osteosclerosis present radiographically
well defined radiopacity
variable shape
less than 2mm
not associated with teeth but can appear next to them
what is sclerosing osteitis
localised area of increased bone density in response to inflammation
may present with symptoms
no expansion or displacement of adjacent structures
how does sclerosing osteitis present radiographically
well defined or poorly defined radiopacity
variable shape
directly related to source of inflammation
what is hypercementosis
excessive deposition of cementum around the root
asymptomatic
what diseases are hypercementosis associated with
Pagets disease
Acromegaly
what is the clinical relevance of hypecementosis
can make extractions more difficult
how does hypercementosis present radiographically
single or multi tooth involvement
homogenous radiopacity continuous with root surface
PDL space of tooth extends around periphery
what are buried retained roots
remnants of failed extractions or heavily broken down teeth
when would retained roots need to be managed
if infected
if symptomatic
if hampering treatment
name three reasons why salivary glands may be imaged
obstruction
dry mouth
swelling
what is ultrasound
no ionising radiation
uses high frequency sound waves at a frequency that cannot be heard audibly
as the waves hit different densities of the tissues it depends on length of time it gets back to the transmitter - determining the density in the photograph
what is the imaging protocol for salivary obstruction in order
ultrasound
plain film - mandibular true occlusal
sialography
name symptoms of salivary obstructive disease
meal time symptoms
rush of saliva into the mouth
saliva is bad tasting - salty
thick saliva
dry mouth
how does saliva obstruction occur and present on imaging
can be due to sialolith or mucous plug
saliva stones are usually hyperechoic (white) as the sound waves cannot pass through
what is sialography
injection of iodinated radiographic contrast into salivary duct to look for obstruction
can be done with panoramic skull views
name two indications for sialography
looking for obstruction or stricture of salivary duct
planning for access for interventional procedures
name four risks of sialography
discomfort
swelling
infection
allergy to contrast
how is sialography carried out
find duct orifice
serial dialators used to allow cannula to be placed
contrast administered
primary image captured
patient rinses
post contrast phase taken to make sure no contrast left
how does acinar changes present in sialography
snow storm appearance
how are saliva stones treated
incision to FOM to remove stone
gland removal if stone is too posterior to be reached by intra-oral approach
what is the 4 selection criteria for stone removal
stone must be mobile
stone should be located within the lumen on main duct distal to border of mylohyoid
stone should be distal to hilum or anterior border of gland
duct should be patent and wide enough to allow passage of the stone
what tests are done for patients with suspected sjogren’s syndrome
blood tests
schirmer test
labial gland biopsy
sialometry
what is a scintiscan
injection of radioactive technetium to assess how well the glands are working
what imaging is first line to rule out obstruction or neoplasia of salivary glands
ultrasound
what is a benign salivary gland tumour
pleomorphic adenoma
how does a pleomorphic adenoma present
well defined
encapsulated peripheral vascularity
no lymphadenopathy
what is a malignant salivary gland tumour
adenoid cystic carcinoma
acinic cell carcinoma
how do adenoic cystic carcinoma/ acinic cell carcinoma present on images
irregular margins
poorly defined
increased internal vascularity
lymphadenopathy
what is MRI
useful for pre-surgical assessment
can see deep margins of lesions that are not seen on ultrasound
when should MRI be taken with regards to biopsy
before a biopsy
if after - inflammatory appearances present on scan which can complicate diagnosis
what is SUMP
salivary gland neoplasm of unknown malignant potential
when would minor salivary glands need imaged
if enlarged or pathological
what is a lipoma
benign fatty mass that appears as hypoechoic with hyperehoic (white) striations
typically avascular
if a lipoma has related vascular structures what should be investigated for
liposarcoma
what is the best imaging to asses quality and quantity of bone
CBCT or CT
MRI for changes in bone marrow that may not be picked up from the above
name four oral bony lesions that may be viewed with CBCT after plain radiographic view
Osteonecrosis
MRONJ
Osteomyelitis
Odontogenic lesions (cysts)
how does osteonecrosis / MRONJ appear on CBCT
moth eaten radiolucency with not-well defined cortical margins
can see central radiopaques which is bony sequestra
how does osteomyelitis present on CBCT
moth eaten radiolucency with widening of PDL
patient is not on drugs associated with MRONJ and has not had radiotherapy
what can CBCT be used for to screen odontogenic lesions
proximity of important structures
buccal-lingual expansion can be seen
if a suspected cyst presents with not much buccal-lingual expansion what is it likely to be and what supplemental test should be done
keratocyst
biopsy for histopathological investigation
is imaging required for myofascial pain in TMD
no
what requires imaging in TMD
internal derangement
degenerative disease (osteoarthritis)
what is used to assess internal derangement of TMJ
MRI
determines if it is with or without reduction
determines which direction the disc moves in relation to the condyle
what views are required when assessing internal derangement with MRI
para coronal
para sagittal
in a normal closed position where should the articular disc be sitting
between 12 and 9 o’clock in the fossa
where does the articular disc sit in normal opening
between the condylar head and articular eminence with the narrowest point directly between the two structures
why may CBCT be used in orthodontics
to assess marked facial asymmetry
what is SPECT
imaging modality used to assess activity of joint
what imaging can be used for head and neck oncology
CT
MRI
Ultrasound
PET
what are the contraindications for MRI scans
pacemakers
cochlear implants
claustrophobia
what three things is MRI better for assessing
perineural spread
bone invasion via bone marrow changes
soft tissue characteristics of lesion
what is the gold standard imaging for neck lumps
ultrasound
what is a PET scan
positron electron tomography
used if patient presents with neck lump but no primary tumour
how does PET scan work
inject fluorine labelled glucose
goes to metabolically active tissues
ascertains the primary tumour
however normal movements of muscles can cause false positives
name causes of generalised malformed roots
systemic illness as a child
tetracyclines during pregnancy
idiopathic
what is the definition of a cyst
pathological cavity having fluid, semi-fluid or gaseous contents which is NOT created by the accumulation of pus
when is the only time a cyst can be filled with pus
if the cyst is infected
name five clinical signs of cystic presence
pain in the bone
mobility of surrounding teeth
swelling around the area
numbness
egg shell crackling noise when pressed
what are the imaging modalities for cyst investigations
initial - PA, occlusal, panoramic
supplemental - CBCT, PA mandible, occipitomental
what radiographic features of cysts should be described
location
shape
margins
locularity
multiplicity
effect on surrounding anatomy
include unerupted teeth
what are the classifications of odontogenic cysts
developmental vs inflammatory
what are the classifications of non-odontogenic cysts
development vs other
what are odontogenic cysts
occur in teeth bearing areas
all lined with epithelium
arising from hertwig’s epithelial root sheath
what is the Rests of Serres
remnants of dental lamina
what are the types of developmental odontogenic cysts
dentigerous
odontogenic keratocyst
lateral periodontal cyst
what are the types of inflammatory odontogenic cysts
radicular cysts
paradental cysts
buccal bifurcation cysts
what is a radicular cyst
inflammatory odontogenic
always associated with non-vital tooth
initiates from chronic inflammation from non-vital tooth at apex
what is the difference between a radicular cyst and a periapical granuloma
radicular cysts tend to be larger
if radiolucency is more than 15mm it tends to be a radicular cyst
name four radiographic features of radicular cyst
well corticated round radiolucency
cortical margin continuous with lamina dura of non-vital tooth
larger lesions may displace adjacent structures
long-standing lesions may cause external root resorption
what are the histological features of radicular cysts
epithelial lined
connective tissue capsule
name five reasons a patient may experience a numb lower lip
compression of nerve by cysts
trigeminal neuralgia
tumours
damage to nerve from IDB
infection
what are the variants of radicular cysts
residual cysts
lateral radicular cysts
what is a residual cyst
type of radicular cyst that persists after the non-vital tooth has been extracted
what is a lateral radicular cyst
cyst associated with an accessory canal
located at the side of the tooth
what are inflammatory collateral cysts and give two examples of types
cyst associated with vital tooth
paradental cyst - occurs at distal aspect of partially erupted mandibular 8
buccal bifurcation cyst - occurs at buccal aspect of mandibular 6
what is a dentigerous cyst
developmental odontogenic cyst
happens during failed eruption
the reduced enamel epithelium has not completely resorbed
the cyst will surround the crown of an unerupted tooth
what is the histological features of a dentigerous cyst
thin non-keratinised stratified squamous epithelium
arises from reduced enamel epithelium
what is the difference between a dentigerous cyst and enlarged follicle
follicle enlargement is less than 5mm
what can increase in size of a dentigerous cyst lead to
damage to bone
fracture of bone
numbness of lip
pathology
what is an eruption cyst
variation of dentigerous cyst but contained within soft tissue rather than bone
associated with erupting tooth
associated with rests of serres
what is an odontogenic keratocyst
developmental odontogenic cyst
has no specific relationship to teeth
has scalloped margins
can cause displacement of adjacent teeth and root resorption
what is the characteristic expansion of an odontogenic keratocyst
enlarges markedly in medullary bone before displacing cortical bone
so there is more mesio-distal expansion compared to buccal-lingual
what are pre-operative diagnostic tests for OKC and what will the histology show
cyst aspirate
will contain squames and low soluble protein content
name four histological features of an OKC
keratin in lining
parakeratosis
nuclei all at same level
when inflamed - keratin is lost
what is the biggest problem of OKC
recurrence
what is a syndrome associated with multiple odontogenic keratocysts
Basal Cell Naevus Syndrome
can cause multiple basal carcinomas of the skin
also known as Gorlin-Goltz syndrome
what is a naso-palatine duct cyst
non-odontogenic developmental cyst
arising from remnants of nasopalatine duct epithelium
occurs in anterior maxilla at the midline
how does naso-palatine duct cyst present
often asymptomatic
patient may have salty taste in mouth
larger cysts may displace teeth
ALWAYS involves midline
what radiographic images are best for viewing nasopalatine duct cyst
periapical or standard maxillary occlusal
how does nasopalatine duct cyst present radiographically
corticated radiolucency between roots of incisors
unilocular
may appear heart shaped
what type of imaging can be used if greater visualisation of a cyst is required for surgical planning
CBCT
what is a solitary bone cyst
non-odontogenic cyst without epithelial lining
most common in young people
what is the radiographical presentation of solitary bone cyst
mostly occurs premolar/ molar region of mandible
variable definition and cortication
may have scalloped margins - pesudolocular
what is a stafne cavity
no a cyst - is a depression in the bone
only occurs in mandible
contains salivary or fatty tissue
how does Stafne cavity present radiographically
often in angle or body of mandible
asymptomatic
well define corticated radiolucency
rarely displaces adjacent structure
what is the general rule for odontogenic vs non-odontogenic cysts
if below level of IAN canal = non-odontogenic
how are odontogenic tumours classified
divided based on origin
epithelial
mesenchymal
mixed
why do only mixed tumours have dentine and enamel formation
due to the concept of induction - ameloblasts only form enamel once dentine starts being deposited
dentine originates from mesencyme
ameloblasts come from epithelium
what are the three odontogenic sources of epithelium
rests of malassez
rests of serres
reduced enamel epithelium
what are rests of malassez
remnants from hertwigs epithelial root sheath which forms the outline of hard tissue of roots
once the formation ceases HERS breaks down but some remnants remain active in PDL
what are rests of Serres
remnants of dental lamina which is responsible for formation of tooth germ
remnants remain in jaw
what is reduced enamel epithelium remnants
remnants that cover the crown of unerupted tooth
can be source of odontogenic tumour
name the three types of epithelial odontogenic tumours
ameloblastoma
adenomatoid odontogenic tumour
calcifying epithelial odontogenic tumour
name the mesenchymal odontogenic tumour
odontogenic myxoma
name the mixed odontogenic tumour
odontoma (odontome)
name features of ameloblastoma
locally destructive but slow growing
painless
occurs in posterior mandible
what is the typical radiographic appearance of ameloblastoma on adjacent structures
knife edged external root resorption of adjacent teeth
what are the two types of ameloblastoma
follicular type
plexiform type
how does the follicular type of ameloblastoma present histologically
islands present with fibrous tissue background
stellate reticulum like tissue
no connective tissue capsule
name histological features of plexiform type of ameloblastoma
cells arranged in strands rather than islands
stellate reticulum like tissue present
no connective tissue capsule
how is ameloblastoma managed
surgical resection with margin of 1mm of normal bone
recurrence common
small risk of malignancy
how does adenomatoid odontogenic tumour present
unilocular radiolucency with internal calcifications around the crown of unerupted maxillary canine
well defined margins
impedes eruption
how is adenomatoid odontogenic tumour differentiated from dentigerous cyst
adenomatoid odontogenic tumour usually attaches apically to CEJ
what are the histological features of adenomatoid odontogenic tumour
epithelial cells arranged in duct like structures
rosette appearance
degree of calcification
fibrous tissue capsule
how does calcifying epithelial odontogenic tumour present
slow growing but can grow to large
radiolucency that has internal radiopacities
variable appearance
how does an odontogenic myxoma present
well defined radiolucency and thin corticated margin
slow growth causing notable buccal-lingual expansion
scallops between teeth
what is the management for odontogenic myxoma
curettage or resection
follow up as recurrence common
how do odontomas present
compound - ordered dental structures that appear as mini teeth
complex - disordered mass of dental tissues
what type of odontoma is more common
compound 2 x more common than complex
what special tests are done for bone abnormalities
blood calcium
osteoblast activity - serum alkaline phosphatase
osteoclast activity - collagen in urine
parathyroid hormone
vitamin D assays
what are tori
developmental abnormality of bone
2 types - torus palatinus and torus mandibularis
what is osteogenesis imperfecta
developmental abnormality of bone
causes weak bones and multiple fractures
what is achondroplasia
dwarfism
what is osteoporosis
lack of osteoclast activity
failure of resorption
marrow obliteration
what is fibrous dysplasia
gene defect causing slow growing asymptomatic lesion
what are the two types of fibrous dysplasia
monostotic
polyostotic
what is monostotic fibrous dysplasia
single bone involvement
what is polyostotic fibrous dysplasia
multiple bones involved
same side of body
what syndrome can fibrous dysplasia be associated with
Albrights syndrome
early puberty
increased pigmentation of the skin
what are the radiographic features of fibrous dysplasia
cotton wool appearance
margins blend into adjacent bone
what is rarefying osteitis
localised loss of bone in response to inflammation
always occurs secondary to another form of pathology
what is sclerosing osteitis
localised increase in bone density in response to low grade inflammation
always around tooth with necrotic pulp
what is idiopathic osteitis
localised increase in bone density of unknown cause
what is alveolar osteitis
dry socket
complication of extraction
very painful - loss of blood clot
what is osteomyelitis
infection of the bone
what is the condition that occurs in children that is a subsection of osteomyelitis
Garre’s sclerosing osteomyelitis
what is bone necrosis
occurs if there has been severe infection (osteomyelitis) that has cut off blood supply
what are the two types of bone necrosis
avascular - age related ischaemia
irradiation - ORN
what are osteoclast inhibitor drugs used for (anti-resorbtive)
osteoporosis
Paget’s disease
bone metastases
