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Do Something or Do Nothing? Anatomical Variants and Incidental Findings on Cone Beam CT. Part 2: Beyond the Dento-alveolar Complex and Neighbouring Structures
Do Something or Do Nothing? Anatomical Variants and Incidental Findings on Cone Beam CT. Part 2: Beyond the Dento-alveolar Complex and Neighbouring Structures Jimmy Makdissi Amanda Loughlin Ashok Adams Mohammed M Dungarwalla Dental Update 2024 49:3, 707-709.
Authors
JimmyMakdissi
DDS, MMedSc, FDS RCS(Eng), DDRRCR, FHEA
Clinical Senior Lecturer and Honorary Consultant, Dental and Maxillofacial Radiology, Institute of Dentistry, Queen Mary University of London and Barts and The London School of Medicine and Dentistry, The Royal London Dental Hospital; Clinical Director, JM Radiology CBCT Training
Specialist in Oral Surgery, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London; Department of Oral and Maxillofacial Surgery, The Royal London Hospital
Cone beam computed tomography (CBCT) is a popular and often indispensable imaging modality used for the dento-alveolar tissues and immediate surrounding structures. It can be used across several dental disciplines including endodontics, implant planning, oral surgery and orthodontics. Furthermore, it is commonly used in the medical specialties of oral and maxillofacial surgery (OMFS) and ear, nose and throat (ENT) surgery. In part 1 of this series, we described some of the common incidental findings found in the dento-alveolar complex and immediate neighbouring structures. Part 2 looks further afield and depicts some common and important incidental findings and anatomical variants that can be found on larger fields of view.
CPD/Clinical Relevance: Many incidental findings are innocuous, yet their recognition and documentation are essential because some will warrant medical or surgical intervention.
Article
In Part 1 of this series,1 the authors illustrated some of the more common incidental findings and anatomical variants found on smaller cone beam computed tomography (CBCT) volumes. Part 2 of this series focuses on the structures beyond the dento-alveolar tissues and the immediate surrounding structures. It also includes some of the less common incidental findings and variants that deserve mention due to their proposed management.
Importantly, some of the findings presented may be beyond the scope for interpretation of the dental practitioner, and onward referral of images for a specialist opinion may be required. Structures potentially included in the imaging field of view include the temporomandibular joints, major salivary glands, cervical spine, skull base, neck ligaments and vasculature. As in Part 1, the entities are presented alphabetically.
Symptoms: may be asymptomatic or non-specific nasal stuffiness, excess mucous production, throat-clearing and epistaxis.
Appearance: there should be a smooth outline of the nasopharyngeal mucosa and symmetrical appearance of the torus tubarius and pharyngeal recesses.
Management: urgent referral to ENT, particularly in the setting of soft tissue asymmetry and radiological evidence of eustachian tube dysfunction with a middle ear and mastoid effusion.
Figure 2.
(a) Calcinosis cutis lateral to the mental protuberance seen on axial slices. This condition is also commonly seen on small volume CBCT (as demonstrated above). (b) 3D reformatting demonstrating the position of the calcifications in relation to the facial skeleton.
Category: incidental finding.
Frequency: common.
Symptoms: Usually few, but can be associated with a wide range of causes including acne, trauma and connective tissue disorders such as systemic sclerosis.
Appearance: scarring from acne, small regions of calcification within the dermal soft tissues. The lips, cheeks and chin are common sites.
Figure 3.
(a) (top left) Sagittal (b) (bottom left) axial and (c) (right) coronal slices demonstrating calcifications in the left external carotid artery (arrowed).
Category: incidental finding.
Frequency: common. In one study with 608 patients, over 17% demonstrated carotid artery calcification.2
Symptoms: none.
Appearance: circular/semi-circular ring of radiopacity in the region of the carotid artery bifurcation.
Management: associated with higher incidence of cardiovascular disease, and attention should be paid to risk factors (smoking, body mass index, exercise and diet).3 GP referral is advised if there is uncontrolled hypertension. All patients who smoke should be offered smoking cessation advice.
Figure 4.
(a) Sagittal slice demonstrating sclerosis, osteophyte formation and narrowing of the joint space between C1 and C2 consistent with degenerative change (arrowed). (b) Sagittal slice demonstrating a well circumscribed radiolucent lesion in C4 likely to represent a simple bone cyst (arrowed).
Category: incidental finding.
Frequency: ranges from uncommon to common.
Symptoms: dependent on pathology, but ranges from none to severe.
Management: neurosurgical/orthopaedic opinion is advised if there are relevant symptoms and signs as degenerative changes are often encountered in asymptomatic patients.
Figure 6. Deviation of the nasal septum towards the left has narrowed the air passage (arrowed) on this side.
Category: incidental finding/anatomical variant.
Frequency: very common.
Signs and symptoms: usually none.
However, can be noticeable particularly after trauma. Patients may mouth-breathe and complain of a dry mouth when awaking or complain of nasal obstruction. Can cause obstruction of ostio-meatal unit leading to unilateral sinusitis.
Appearance: unequal separation of the nasal cavity in an axial dimension due to deviated septum.
Management: None. If symptomatic, ENT referral is advised.
Fungal infection of the paranasal sinuses (Figure 7)
Figure 7. Fungal infection of maxillary sinus. The radiopaque densities in the area give a hint to the correct diagnosis.
Category: incidental finding.
Frequency: uncommon, potential association with zinc oxide-based root-filling material that has extruded into the maxillary sinus.4 Other predisposing causes include asthma, corticosteroid use and immunocompromise.
Appearance: internal opacification of the sinus that potentially has increased central density similar to that of tooth substance (mycetoma/fungal ball). Linear foci of increased density associated with sinonasal polyposis probably reflects allergic fungal sinusitis. Invasive fungal sinusitis is observed in the setting of immunocompromise and may demonstrate aggressive features in terms of bony destruction, but the soft tissue findings and infiltration of fat planes will be relatively occult on CBCT imaging.
Symptoms: Symptoms of nasal stuffiness and obstruction.
Management: ENT referral. If associated with ZOE paste, appropriate management of endodontically treated tooth (ie removal of the extruded root-filling material).
Figure 8. Lymph node calcification seen in level II of the right neck.
Category: incidental finding.
Frequency: common.
Symptoms: usually none, but indicative of previous granulomatous disease, usually tuberculosis or aspergillosis, and also can indicate active or treated malignancy. Also, a potential sequalae of head and neck irradiation.
Appearance: irregular, coral- or cauliflower-shaped radiopacity at the region of the cervical lymph nodes.
Management: none, but history of infection (particularly tuberculosis) or malignancy should be confirmed with the patient.
Appearance: calcification of the soft tissue in the region of the pineal gland.
Management: none.
Pituitary abnormality (enlargement of the sella turcica) (Figure 10)
Figure 10. Enlarged antero-posterior dimensions of the sella turcica seen in the sagittal plane.
Category: incidental finding.
Frequency: uncommon.
Signs and symptoms: wide-ranging depending on type of pathology. Most likely to be a pituitary adenoma that can either be functioning or non-functioning. The relevant symptoms and signs are dependent on the biochemical disturbance, while local mass effect of the tumour may compromise the anterior visual pathways and optic chiasm that may result in a visual field defect.6
Appearance: the maximum normal dimensions of the sella turcica are 5–16 mm in an antero-posterior dimension and 4–12 mm in a superior–inferior dimension. A ballooned or enlarged appearance warrants further investigation.
Management: if undiagnosed, urgent endocrinology and neurosurgical opinion is advised.
Figure 11. A rhinolith seen in the left inferior nasal cavity (arrowed). There was no preceding nasal trauma or known history of a foreign body inserted into the nose. Note the mucosal thickening of the sinuses bilaterally.
Category: incidental finding.
Frequency: uncommon.
Signs and symptoms: usually none, associated with insertion of foreign object during childhood. Occasionally presents with nasal stuffiness, epistaxis, nasal obstruction.7,8
Appearance: irregular radiopaque mass in nasal cavity.
Management: referral to ENT advised as uncommon finding.
Figure 13. Sclerosis and opacification of the left maxillary sinus. Note the mucosal thickening of the right maxillary sinus. There is evidence of periodontal bone loss, and peri-apical changes associated with the upper right first molar.
Category: incidental finding.
Frequency: uncommon.
Appearance: opacification of the sinus and thickening/sclerosis of the sinus walls in longstanding/recurrent disease.
Figure 15. Coronal slice demonstrating a bifid right condyle (arrowed).Figure 16.
(a) Sagittal slice demonstrating flattening of the condylar head and osteophyte formation. (b) Osteophyte formation more clearly seen on the axial view.
Category: incidental finding.
Frequency: extremely common.
Symptoms: often none. Occasionally there is painful crepitus in degenerative change.
Appearance: typical features include flattening of the condylar head and glenoid fossa, osteophyte formation and beaking. Loose bodies may also be seen within the joint space.
Management: Referral to oral and maxillofacial surgery is warranted if there are symptoms of pain, or functional deficits.
Frequency: common, particularly in older age. In one study, they were seen in over 8% of 400 CBCT scans.10
Symptoms: none, may be seen clinically.
Appearance: irregular radiopaque areas a few millimetres in diameter medial to the mandibular ramus.
Management: none
Conclusion
This two-part series has outlined some of the incidental findings and anatomical variants that can be found on CBCT imaging. As the popularity and accessibility of CBCT imaging increases (especially among primary care practitioners), it is likely that clinicians will be faced with presentations on imaging with which they are not necessarily familiar. It is important to note that most, if not all the findings presented in this series can be found in individuals who have no signs or symptoms of disease whatsoever.
The authors recommend that use of CBCT imaging is supported through accredited training and access to a network of professionals who can offer specialist reporting facilities.
