Soft Tissue Calcifications in the Neck:
Maxillofacial CBCT Presentation and Significance
William C. Scarfe*, B.D.S., F.R.A.C.D.S., M.S., Dipl. ABOMR
Allan G. Farman*, B.D.S., Ph.D., D.Sc., MBA, Dipl. ABOMR
*Professors, University of Louisville School of Dentistry. Louisville, Kentucky,
William C. Scarfe B.D.S., F.R.A.C.D.S., M.S., Dipl. ABOMR
Dept. of Surgical/Hospital Dentistry,
University of Louisville School of Dentistry,
501 South Preston St.,
Louisville Kentucky 40292, USA
Tel: 502-852-1226 Fax: 502-852-7595
From the Spring 2010 AADMRT Newsletter
William C. Scarfe
Allan G. Farman
Calcifications of the soft tissue structures in the head and neck can occur either
as physiological or pathological mineralization. Pathological mineralization is
more likely to occur in articular cartilage, vascular tissues, ligaments and glandular
tissues and is usually associated with chronic inflammation or scarring. The deposition
of mineral salts in dead or degenerating tissues is referred to as dystrophic calcification.
In the craniofacial region, these calcifications can occur in the brain (e.g. calcification
of choroid plexus, pineal gland, or dura mater), the temporomandibular joint synovial
tissue (e.g. synovial chondromatosis), paranasal sinuses (e.g. antrolith), associated
with maxilla and mandible (e.g. sialiliths) or in the neck and adjacent structures.
Among patients presenting for dental treatment, some calcifications may be detected
on panoramic radiography because of the proximity of soft tissue structures to the
focal trough. However, these images are inherently planar and two-dimensional (2D),
so localization and therefore diagnosis is problematic. With the increasing use
of cone beam computed tomography (CBCT) in dentistry, the incidental discovery of
these calcifications is most likely to increase. In addition, CBCT provides images
in the third dimension (3D) which facilitates precise localization.
The purpose of this article is to describe the imaging characteristics of regional
neck calcifications on cone beam computed tomography (CBCT) commonly observed in
dental practice. Proper knowledge and diagnosis of these calcifications assists
the clinician in the appropriate management of the patient.
STRATEGIES FOR CBCT INTERPRETATION
Interpretation of CBCT images for calcifications in the neck involves three considerations:
Calcifications of soft tissue structures are a relatively common occurrence.
Khan et al.1 recently reviewed 308 CBCT scans (mean age;
52 ± 18 yrs.: age range; 7 - 86 yrs: sex; 56.8% women/43.2% men) and found
that 35% had some form of soft tissue calcification with most (90%) in the neck.
The most common soft tissue calcifications found, with an almost equal distribution,
were carotid artery calcifications (CAC), calcifications of the triticeous cartilage
(CTC) or calcifications of the tonsils (CT).
Task specific image display should be used to demonstrate the presence and location
of calcifications. Because the key to differential diagnosis is determining
the anatomic location of the calcification, an appropriate display mode should be
used to provide the optimal viewing. The protocol we recommend uses of medium thickness
slice (20mm - 40mm) maximum intensity projection (MIP) images.2
This technique is faster and less expensive than direct volumetric reconstruction
(Fig. 1) and, when used in all three orthogonal projections, provides adequate three
dimensional information for diagnosis.
Figure 1: Shaded surface 3D reconstruction demonstrating segmented calcified
Knowledge of the imaging characteristics of the calcification assists in developing
a differential diagnosis and facilitates appropriate management. Most
calcifications in the maxillofacial region are relatively benign in nature and are
associated with few negative outcomes, however in the neck it is necessary to specifically
identify carotid artery calcifications (CAC) from others as the presentation of
these could lead to more ominous sequelae. Therefore the clinician should have a
solid foundation in the radiographic presentation of calcifications condition as
it relates to the various structures, particularly on CBCT imaging.
CALCIFICATIONS IN THE NECK
Calcified Stylohyoid Chain (CSC). The styloid process (SP) is a slender projection
of bone that arises from the inferior surface of the temporal bone just beneath
the external auditory meatus. Within the neck, the SP extends infero-medially towards
the pharyngeal wall lateral to the tonsillar fossa. The normal length in an adult
is considered to between 20mm3 to 30mm4,5
with 40mm considered to be elongated. There are several ligaments (stylohyoid and
stylomandibular) and muscles (styloglossus, stylohyoid and stylopharyngeus) that
originate from the SP which together act to stabilize the hyoid bone during normal
oropharyngeal functions. In particular, the stylohyoid ligament (SHL) arises from
the tip of the SP and attaches to the lesser cornu of the hyoid bone. This anatomic
arrangement is collectively referred to as the stylohyoid chain. Excessive or abnormal
calcification of stylohyoid chain (CSC) components includes elongation of the SP6,7
and calcification of the stylohyoid ligament.8-10 Depending
on the population sample, between approximately 1.4%11
to 30%6 of individuals have radiographic evidence of CSC,
most of which (75%) are bilateral.7 Most patients with
CSC are asymptomatic however approximately 1%9 to 10%6
may have clinical symptoms due to the compression of the rigid stylohyoid compressing
or irritating nearby structures,12 such as the carotid artery - known as "Eagle's"
or "Elongated Styloid Process" Syndrome.
On panoramic radiology, the CSC appears as an elongated slender bony projection
that continues from the SP and extends towards, and occasionally appearing continuous
with, the lesser cornu of the hyoid bone. Calcification may present in one of 12
patterns13 with variations in degree of ossification,
segmentation, pseudo-articulation, thickness and angulation. On axial CBCT images
CSC appears as a discrete circular corticated opacification and, because of the
caudal, medial and anterior progression presents more anteriorly and medially on
progressively more inferior sections (Fig. 2). Our protocol clearly demonstrates
the anatomic relationships (Fig. 3).
Figure 2: Location of CSC on axial images. At the level of the sigmoid notch
(a), discrete circular opacities are present posterior and lateral to the pharyngeal
airspace, anterior to the petrous temporal bone and posterior and medial to the
distal border of the ramus. At the level of the mid ramus/ C1 (b) and mid mandible/C2
(c) the location of the opacity changes along a medial anterior path (arrow in (a))
such that at the level of the lower border of the mandible (d) the opacities are
anterior to the airway.
Figure 3: Definitive characterization of the CSC is provided by bilateral
oblique linear medium thickness (40mm) MIP images (a/c) developed on axial MIP image
at the level of the mandible (b – yellow line). Panoramic MPR images (d) (orange
line on b) are also useful.
Calcified Triticeous Cartilage (CTC). The triticeous cartilages (TC) are
small bilateral ovoid structures located below the hyoid bone in the lateral thyrohyoid
ligament at approximately the level of C3-C4. Benign dystrophic calcification of
this structure is common, ranging from 5-29%.14 The TC
may help reinforce the lateral thyrohyoid ligament.15
When calcified, the TC may be seen on a panoramic radiograph as a single faint opacification
immediately inferior to the tip of the greater cornu of the hyoid bone (GCHB) in
the same regional area as other dystrophic calcifications of soft tissue including
the CAC (Fig 4). On axial CBCT imaging, CTC appears as a single "rice grain"
like ovoid homogeneous dense opacification always located medio-posterior to the
most distal extent of the GCHB and in the superficial soft tissue in the lateral
pre-vertebral space (Fig. 5a). On coronal images CTC are immediately inferior to
the GCHB (Fig. 5b) whereas on sagittal images, CTC are immediately inferior and
slightly anterior to the GCHB (Fig. 5c).
Figure 4: Cropped panoramic image of the lower left mandibular angle (MA)
demonstrating relationship of the calcified triticeous cartilage (CTC) to the greater
cornu of the hyoid bone (GCHB) and second cervical vertebrae (C2).
Figure 5: Axial (a), coronal (b) and sagittal (c) MIP projections showing
appearance and location of the CTC immediately inferior to the maximal extension
of the greater cornu of the hyoid bone (GCHB).
Calcified Superior Cornu of the Thyroid Cartilage (CSCT). The thyroid is
the largest and most superior of the cartilages of the larynx and is suspended immediately
below the hyoid bone by the thyrohyoid membrane, median and lateral throhyoid ligaments.
The latter extends from the terminal portion of the GCHB inferior to a lateral prominence
called the superior cornu of the thyroid cartilage. In the thyroid cartilage, calcification
is a progressive condition16 that normally starts at the
posterior border, the lower margin, and the inferior horn of the thyroid cartilage
and is completed around the age of 70 years.17 CSCT on
panoramic imaging18 only occurs in older individuals and
presents in the same regional location as the CTC and more importantly the CAC.15
On CBCT most often appears as a discontinuous anteroinferiorly perpendicular extension
of the terminal end of the greater cornu of the hyoid. On axial sections the CSCT
appears as a single distinct circular opacification immediately posterior to the
GCHB (Fig. 6a) rather than medial as with the CTC. On coronal sections the CSCT
appears as a linear cylindrical opacification extending inferior from the greater
cornu of the hyoid (Fig. 6b) and on sagittal images (Fig. 6c) a single peripherally
corticated opacification is usually located along a line projected inferiorly and
slightly anterior to the most posterior extent of the GCHB.
Figure 6: Axial (a), coronal (b) and sagittal (c) MIP projections showing
appearance and location of the CSCT immediately inferior to the maximal extension
of the greater cornu of the hyoid bone (GCHB). CTC can be differentiated from the
CSCT on axial images image as being medial to the GCHB (a).
Calcified Tonsils (CT). The tonsils are paired bilateral lymphoid tissue
located in the lateral wall of the oropharynx adjacent lateral to the terminal sulcus
of the tongue. Tonsilloliths are small areas of calcareous matter that form in the
tonsillar crypts which may grow or coalesce to a large size.19
Patients may be asymptomatic or complain of persistent throat irritation, foul taste
and odor or otalgia. Tonsilloliths are a common incidental imaging finding on up
to 16% of patients.20 On panoramic images they appear
as multiple small opaque masses superimposed on the anterior border of the oropharyngeal
airway space and may extend over the mandible. On CBCT imaging CT appear as multiple
clustered "rice grain" like ovoid homogeneous dense opacifications immediately
superficial to the lateral oro-pharyngeal airway space which differentiates them
from CAC or CTC (Fig. 7).
Figure 7: Orthogonal sections showing CT on axial (a), coronal (b) and sagittal
(c) MIP projections as multiple small opacifications superficial and antero-lateral
to the oro-pharyngeal airway space. On coronal section (b), clusters are often superimposed
over the anterior tubercle of the cervical spine and span supero-inferiorly linearly
in line with the pterygoid plates whereas on sagittal sections (c), they are superimposed
over the shadow of the oro-pharyngeal airway space or anterior to it.
Carotid Artery Calcifications (CAC). The carotid artery provides the main
blood supply to the brain. Atherosclerosis is a pathological condition of the vasculature
where vascular plaques form reducing the luminal diameter. This occurs most often
at areas of greatest shear force such as the bifurcation of the internal and external
carotid artery, located lateral and inferior to the hyoid bone. Atherosclerotic
conditions of a carotid artery can lead to neural ischemia (inadequate oxygen to
the brain) thus resulting in a cerebrovascular accident (CVA), or stroke. Atheroma-related
formations of thrombi and emboli in the carotid artery is the most frequent cause
of stroke.21 Calcification is a complication in the evolution
of atheromatous plaque enabling potential detection by maxillofacial imaging. Since
198122 calcified atherosclerotic lesions at the carotid
bifurcation have been reported on panoramic radiographs as curvilinear irregular
parallel radiopacities about 1.5 to 2.5 cm inferiorposterior to the angle of the
mandible adjacent to the cervical spine at or below the third and fourth cervical
vertebra and inferior and lateral to the hyoid bone.
The prevalence of CAC on panoramic images in the general dental population over
50 years varies from 0.1% to 3.2% increasing with age and is substantially higher
(22% to 37%) in populations exhibiting atherosclerotic (hypertension, cardiovascular
disease, past stroke/CVA, transient ischaemic attacks or diabetes) or other (hypercholesterolemia,
obesity and physical inactivity, cigarette smoking, sleep apnea, head and neck radiation
therapy, and male gender) risk factors.
On CBCT imaging, the salient features depend on orthogonal section. On axial projections,
most CAC presented as single or multiple "rice grains", linear, or curvilinear
homogeneous opacifications (Fig. 8). They are most commonly located in the soft
tissue approximately 0-10mm antero-laterally to the anterior tubercle of the transverse
process, lateral or more often latero-posterior to the GCHB. They are always postero-lateral
to the pharyngeal airway space. In coronal sections, CAC are lateral to the anterior
tubercle of the cervical vertebrae (Fig. 9). On sagittal sections, CAC are medial
and inferior to the angle of the mandible, lateral and mostly anterior to the cervical
tubercle with vertical position varying from C3 to C5 (Fig. 10).
Figure 8: Axial projections demonstrating CAC as single rice grain (a), multiple
"rice grains" (b - right), linear (b - left; c - right), or curvilinear
(c - left; d - left) homogeneous opacifications. As the size of the CAC increases,
the number of ipsilateral opacifications also tends to increased (d - left) forming
larger coalescing masses (d - right). The proximity to the calcified stylohyoid
chain (CSC) is clearly evident.
Figure 9: Coronal MIP projections demonstrating CAC lateral to the cervical
vertebrae and presentation as linear globular (a) or globular calcifications (b).
Relationship to the calcified stylohyoid chain (CSC) is evident.
Figure 10: Sagittal MIP projections demonstrating location of CAC in relation
to the hyoid bone at the level of the greater cornu of the hyoid bone (GCHB). An
isolated calcified stylohyoid chain (CSC) is shown.
Because of the significant morbidity and mortality of the presence of a CAC, when
suspected, the patient should be referred to an appropriate medical physician (Fig.
11) who will confirm the presence and degree of stenosis of the lumen of the artery
(usually by duplex ultrasonography) which which is directly related to the risk
of a stroke.
Figure 11: Example of suggested referral letter to a physician with suspected
CAC identified on either a panoramic or CBCT image.
Other Neck Calcifications. Three other calcifications with substantially
reduced prevalence may occur in the neck. A sialolith (a.k.a. salivary stone or
salivary gland calculus) is an aggregation of calcified material found within the
ducts or glandular tissue of salivary glands. The overall on panoramic radiographs
in the general population is 0.1%.23 The submandibular
gland is the most commonly affected (approx. 80%). Stones in this gland are located
near the hilum of the gland or in the proximal portion of Wharton's duct (Fig. 12).
Depending on the position of the hyoid bone at the time of the CBCT, a sialolith
may appear to be present within the superior neck. They may appear as single linear
or globular homogeneous opacities medial to the angle of the mandible.
Figure 12: Axial (a) and coronal (b) 0.4mm orthogonal sections demonstrating
large isolated onion shaped calcification adjacent the lingual cortical plate in
the right submandibular region consistent with a sialolith. The patient was asymptomatic
and unaware of the condition, however once made aware of the calcification, reported
the removal of a similar "stone" on the left time approximately 10 years
Lymph nodes are present in the neck in the submandibular, submental preauricular,
and cervical areas. Calcification is asymptomatic and usually present in patients
who have a history of chronic inflammation in the area (e.g. sinusitis, tonsillitis)
however can be the result of tuberculosis, metastases of thyroid cancer or associated
with a patients who have been treated for lymphoma. Radiographically these calcifications
usually appear as distinct, irregularly shaped opacities characteristically described
as "cauliflower-like." As cervical lymph nodes are grouped both superficially
and deep to the neck, imaging differentiation is most often based on appearance.
A phlebolith is a calcified vascular thrombus that is most frequently associated
with a vein, venule, or hemangioma not contained within bone. Their formation is
thought to be as a result of vascular anomaly, which induces thrombus formation.
The end result is calcium deposit with eventual stone formation. They are usually
multiple, laminated spherical radiopacities with an "onion-like" appearance.
The presence of a phlebolith is highly suggestive of either a hard of soft tissue
Calcifications within the cervical neck at the peri-hyoid region are common findings
on CBCT images of this region. An appreciation of the CBCT imaging features of the
most frequently (e.g. carotid artery calcifications, calcifications of the triticeous
cartilage or calcifications of the tonsils) as well as less commonly occurring conditions
is necessary to identify and appropriately refer those with carotid artery calcification
for more comprehensive diagnostic medical assessment.
This article was originally submitted to the Australian Dental Journal.
Dr. William C. Scarfe and Dr. Allan Farman hold exclusive rights to this article.
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