Radiology Flashcards
Define, “a pathological cavity having fluid, semi-fluid or gaseous contents & which is not created by the accumulation of pus”
A cyst
Name three developmental odontogenic cysts.
- Dentigerous cyst
- Odontogenic keratocyst
- Lateral periodontal cyst
Name two inflammatory Odontogenic cysts.
- Radicular cyst
- Inflammatory collateral cysts (paradental or buccal bifurcation cyst)
What radiographic imaging allows for more accurate determination of size of a cyst or cyst-like lesion?
CBCT
In terms of shape of a lesion, how can locularity on a radiograph be described?
Either:
1. Unilocular
2. Pseudolocular
3. Multilocular
In terms of shape of a lesion, how can general shape on a radiograph be described?
Either:
1. Rounded
2. Scalloped
3. Irregular
In terms of margins of a lesion on a radiograph, how can this be described?
- Well defined (either corticated or non-corticated)
- Poorly defined (blends into adjacent anatomy or appears ragged/moth-eaten)
What does a corticated margin on a lesion suggest about the nature of the lesion?
That it is benign
What does a moth-eaten margin on a lesion suggest about the nature of the lesion?
Suggest malignancy
What is important to note about an infected cyst/lesion and how this affects its appearance on a radiograph?
Cysts can loose their features (usually well-defined and corticated becomes poorly defined) when infected
Position of a cyst or cyst-like lesion can aid diagnosis. What lesions might be suggested if positioned:
1) around apex/apices
2) at side of root
3) around crown
4) around entire tooth
1) radicular cyst
2) lateral periodontal or radicular cyst
3) dentigerous cyst
4) rare calcifying odontogenic tumour
If there are >2 lesions present at once, what should be suspected?
An associated syndrome
It is difficult to differentiate between radicular cysts and periapical granulomas radiographically. However what is the best way to attempt to do this?
Radicular cysts are typically larger, if radiolucency diameter >15mm then in 2/3rds of cases this will be a radicular cyst
What is a residual cyst?
When a radicular cyst persists after loss of tooth (or after tooth is successfully root canal treated)
What cyst is described?
Cystic change of a dental follicle associated with crown of an unerupted/impacted tooth
Dentigerous cyst
How can you distinguish between a cyst and n enlarged follicle?
Consider a cyst if follicular space > or equal to 5mm (measured from surface of crown to edge of follicle)
What is the measurement of a normal follicular space?
2-3mm
What inflammatory collateral cyst typically occurs at the distal aspect of partially-erupted mandibular third molars?
Paradental cyst
What syndrome presents with multiple Odontogenic keratocysts?
Basal cell naevus syndrome
What structures surround and are involved in the function of the TMJ?
- Bone
- Muscles
- Articular disc
- Ligaments
- Neurovascular structures
What are the 5 imaging modalities that could be utilised for imaging of the TMJ?
- Plain film (e.g. DPT)
- CBCT
- CT
- MRI
- Nuclear medicine
DPT usually isn’t recommended for assessment of the TMJ in most cases, however, what 5 cases would it be indicated?
- Recent trauma
- Change in occlusion
- Mandibular shift
- Sensory/motor alterations
- Change in range of movement (specifically trismus)
Why are DPT’s not indicated for TMJ assessment in majority of cases?
Because most pain associated with the TMJ will be myofascial in origin rather than bony or soft tissue in relation to the articular disc.
Why can fractures of the mandible be difficult to spot on PA view?
Due to superimposition of the cervical spine
What imaging is particularly good to assess bone changes/degeneration of the TMJ?
CBCT
What imaging is best for investigation of potentially neoplastic masses and why?
CT scan, as you can visualise both soft tissue and bone.
What is the gold standard imaging for assessment of the TMJ?
MRI
What is the main advantage of MRI over other imaging modalities?
No radiation dose
What are the clinical features of anterior displacement with reduction?
Reciprocal clicks on opening when the disc is recaptured
Describe the positioning of the articular disc (within TMJ) when there is anterior displacement with reduction?
Articular disc will lie in an anterior position in the closed mouth, and will sit in a normal position upon mouth opening.
What are the clinical features of anterior displacement without reduction?
Limitation of opening for the patient and associated pain, as retro-discal tissues have been stretched
In what case is nuclear medicine (SPECT) most useful?
Condylar hyperplasia
What does SPECT stand for?
Single photon emission CT
Why do we image the salivary glands?
- Obstruction (mucous plugs, salivary stones, neoplasia)
- Dry mouth
- Swelling
What 6 imaging modalities can we use for imaging of the salivary glands in dentistry?
- Plain film
- Ultrasound
- Injection of iodinated contrast (sialography)
- CT
- MRI
- Nuclear medicine
What are the two main first-line imaging modalities for salivary gland obstruction?
- Plain film
- Ultrasound
What 3 main views are undertaken in plain film radiography for imaging of the salivary glands?
- Lower true occlusal
- OPT
- Lateral oblique
What plain film view is particularly useful for looking at submandibular salivary stones?
Lower true occlusal
What is the advantage of a lateral oblique over an OPT for imaging of submandibular gland?
Lateral oblique prevents superimposition of mandible over submandibular gland, like in an OPT.
Define the imaging technique described.
- no ionising radiation
- high frequency sounds waves
Ultrasound
How does an ultrasound work? (Summarise in 3 steps)
- Transducer emits and detects sound waves/echoes
- Transducer creates sound waves which enter the body and reflect back to the transducer
- Tissue depths are calculated and the ultrasound unit creates a 2D image
Define hypoechoic in regards to an ultrasound
Dark
Define hyperechoic in regards to an ultrasound
Bright
What are the three main advantages of ultrasound for imaging salivary glands?
- Glands are superficially positioned
- Can assess parenchymal pattern, vascularity, Ductal dilatation or neoplastic masses
- Can give a sialogogue to aid saliva flow
What are the symptoms of obstructive salivary disease?
- “Meal time symptoms”
- Prandial swelling and pain
- ‘Rush of saliva into the mouth’
- Bad taste
- Thick saliva
- Dry mouth
What is the aetiology of obstructive salivary gland disease?
Sialolith or mucous plug
What is sialography?
Injection of iodinated radiographic contrast into salivary duct to look for obstruction
What are the two main indications for sialography?
- Looking for obstruction or stricture of salivary duct which could be leading meal time symptoms
- Planning for access for interventional procedures (e.g. basket retrieval of stones)
What are the 5 main risk of the procedure for sialography?
- discomfort
- Swelling
- Infection
- If stones mobile could make obstruction worse
- Allergy to contrast (very rare)
What is the purpose of the pre-contrast phase of sialography?
Excludes other pathology which could account for Symtpoms and can be used as a base line
What are the three different contrasts that can be used for sialography?
- Iodine based
- Aqueous rather than oil based
- ISO-osmolar
On a sialograph, what should a normal parotid gland appear like?
“Tree in winter”
On a sialograph, what should a normal submandibular gland appear like?
“Bush in winter”
On a sialograph, if there are acinar changes to a gland, what will this appear like?
“Snow-storm appearance”
If a patient has an iodine allergy, what alternative type of sialography can be used?
MRI Sialography
What is the selection criteria for stone removal? (4 points)
- Stone must be mobile
- Stone should be located within lumen on main duct distal to posterior border of the gland
- Stone should be distal to hilum or at anterior border of the gland
- Duct should be patent and wide to allow passage of the stone
What is the best imaging modality for Sjögren’s disease?
Ultrasound
What is scintigraphy?
Intra-venous injection of radioactive technetium 99m pertechnetate
What is the purpose of scintigraphy?
Assess how well the glands are working (uptake into glands if they are working well)
What are features of a benign lesion?
- Well defined
- Encapsulated
- Peripheral vascularity
- No lymphadenopathy
What are features of a malignant lesion?
- Irregular margins
- Poorly defined
- Increased/tortuous internal vascularity
- Lymphadenopathy
Why is it important to undertake MRI for salivary gland imaging before doing a biopsy?
Inflammatory appearances will appear on the MRI scan which may complicate diagnosis if not done first
What does SUMP stand for?
Salivary gland neoplasm of unknown malignant potential
What is the management for an odontoma?
Excision
Define a localised area of increased bone density of unknown cause.
Idiopathic osteosclerosis
What are two features to remember about idiopathic osteosclerosis?
- adjacent teeth are not displaced
- there is no affect on the PDL space of teeth
Define a localised area if increased bone density in response to inflammation.
Sclerosing osteitis
Define an excessive deposition of cementum around root
Hypercementosis
What diseases is Hypercementosis more common in?
- Paget’s disease of bone
- Acromegaly
What is the clinical relevance of hypercementosis?
Makes extractions more difficult
What is the key distinctive feature of Hypercementosis?
Homogenous radiopacity continuous with root surface (PDL space extends around periphery of lesion)
Define the benign odontogenic tumour of cementum.
Cementoblastoma
What are the clinical features of cementoblastoma?
- Occurs around root of vital tooth
- Often painful
- Can displace adjacent teeth and cortical bone
What are the key radiographic feature of cementoblastoma?
Thin radiolucent margin continuous with PDL space of root
What is the clinical relevance of Tori?
- Can hamper denture wear
- Potentially traumatised during eating
Define, a benign tumour of bone.
Osteoma
What might multiple osteoma indicate?
Gardener syndrome
What is gardner syndrome?
A rare variant of familial adenomatous polyposis
What train of clinical manifestations is gardener syndrome characterised by?
- Colorectal polyposis
- Osteomas
- Soft tissue tumours (e.g. epidermoid cysts of skin)
What are 7 dental features of cleidocranial dysplasia?
- generally delayed eruption
- multiple supernumerary teeth
- impaction of other teeth
- retained primary teeth
- hypoplastic maxilla with high arched palate
- increased prevalence of cleft palate
- coarse trabecular pattern
Define, inflammation of bone and bone marrow due to bacterial infection.
Osteomyelitis
Define, bone death resulting from irradiation.
Osteoradionecrosis
Define, breakdown of bone.
Osteolysis
Define, increased density of bone.
Osteosclerosis
Define, a reactive lesion with benign tumour-like behaviour.
Central giant cell granuloma
Define, a group of rare benign, non-inheritable conditions where normal bone is replaced by connective tissue and abnormal bone.
Fibro-osseous lesions
What are the three main types of fibro-osseous lesions?
- Cemento-osseous dysplasia
- Fibrous dysplasia
- Ossifying fibroma
Which type of fibro-osseous lesion only affects the jaws?
Cemento-osseous dysplasia
What are the three forms of cemento-osseous dysplasia?
- Focal COD
- Periapical COD
- Florid COD
Describe focal COD.
Single or few localised lesions
Describe periapical COD.
Lesions associated with apices of anterior mandibular teeth
Describe florid COD.
Extensive lesion or many lesions
What is the incidence of cemento-osseous dysplasia?
Presents at age 30-50 years, more common in black females.
What is the management of cemento-osseous dysplasia?
Usually no management required, removal only recommended if exposed by extraction, trauma etc.
Why is biopsy best avoided in the case of cemento-osseous dysplasia?
As there is a risk of secondary infection following interventions
What are the three forms of fibrous dysplasia?
- Monostotic
- Polyostotic
- Craniofacial
What are the clinical features of fibrous dysplasia in the jaw?
- facial swelling
- May displace teeth
- painless
What is the management of fibrous dysplasia?
No managment required if not causing functional or aesthetic issues
Define, a fibro-osseous neoplasm occurring most often in tooth-bearing areas.
Ossifying fibroma
What is the management of ossifying fibroma?
Removal indicated due to progressive growth (by surgical enucleation or resection)
Define, a chronic condition causing disordered remodelling of bone.
Paget’s disease of bone
What are clinical/radiographic features of Paget’s disease of the bone?
- enlargement of bones
- cotton-wool appearance of bone on x-ray
- malocclusion
- nerve impingement (cranial nerve deficits)
- brittle bones
Define, decreased bone mass.
Osteoporosis
What are radiographic features of osteoperosis of the jaw?
- thinned cortices
- sparse trabecular bone pattern
- thinned lamina dura around teeth
