Keywords sialography - salivary gland diseases - cone beam computed tomography
Introduction
Salivary gland diseases unrelated to tumors are prevalent among adults and encompass
conditions such as chronic inflammation, ductal strictures, salivary stones, and anatomical
abnormalities. Sialolithiasis, accounting for 60 to 70% of obstructive cases, stands
as the primary cause, followed by stenosis at 15 to 25%. Clinically, these pathologies
manifest as a reduction in salivary flow, leading to obstructive symptoms such as
salivary pain and swelling during eating.[1 ] Assessment and management of the majority of symptomatic salivary gland disorders
heavily rely on diagnostic imaging. These radiological techniques help determine the
type, extension, and etiology of these diseases.[2 ] Currently, occlusal intraoral radiographs, conventional sialography, ultrasound
(US), computed tomography (CT) with or without contrast media, magnetic resonance
imaging (MRI) with or without enhancements, MR-sialography, and nuclear salivary scintigraphy
are the methods used to image the major salivary glands. There are indications and
restrictions associated with each technique, which are reliant on primary evaluation
objectives and the availability of various imaging technologies.[3 ]
US is currently the imaging modality of choice for preliminary evaluation of salivary
glands. Assessing lesions located superficially in both parotid and submandibular
glands is made easier by its affordability, patient-friendliness, accessibility, and
safety. Research has indicated that US has a 98% accuracy rate when it comes to differentiating
between glandular and extraglandular lesions. However, US method is limited in its
ability to identify parotid masses that are located in depth, which are hidden by
the mandible, and is dependent on operator competence. Thus, to determine the full
extent of big tumors or to provide a conclusive diagnosis in cases of locally invasive
lesions, clinicians ought to investigate alternative imaging modalities.[4 ]
Sialography, which involves injecting a radiopaque contrasting agent within the gland's
ductal architecture before imaging, is considered the imaging modality that assesses
the functioning of the glands. This imaging modality is considered to be the only
investigative method that shows the complex architecture of the ductal system in strictures
and sialoliths. Sialography is preferred in cases of major salivary gland obstructions.[5 ] The complex anatomy of the glandular ductal systems may not be sufficiently depicted
by the anisotropic voxel resolution of sialography, despite its integration with medical
CT. Combining sialography and fluoroscopy is possible but results in high radiation
dosage to the patients.[6 ]
[7 ]
Conventional sialography is gradually being replaced by MRI. MRI, being nonionizing
in nature and not requiring cannulation in its diagnostic procedure, is useful for
investigating salivary glands as well as detecting lesions that are both parenchymal
and ductal. MR-sialography has limitations in terms of accessibility, cost, and sensitivity
when examining ductal diseases.[8 ]
To provide information on the quantity, dimensions, and exact placement of salivary
stones, millimeter-thin precision axial CT scan slices, multiplanar reconstruction,
and three-dimensional (3D) reconstruction are utilized. In comparison with X-rays
and US, these methods have a higher specificity for sialoliths. Cone beam CT (CBCT)
has been proposed as an alternative to standard CT in accordance with the idea of
obtaining diagnostic accuracy with low radiation exposure.[9 ] Though it seems to have greater sensitivity than plain films in identifying calcifications
of ductal architecture, traditional CT has been used to identify salivary calculi;
nonetheless, it is not commonly used for patients with suspected blockage. In the
case study published by Szolar et al,[6 ] it was found that sialography was less effective than 3D reconstructive images of
CT data of the ductal system architecture in displaying strictures.[10 ] Sialo CBCT, sometimes referred to as CBCT-sialography, is considered a novel method
as an alternative to traditional sialography for observing the salivary glands' ductal
system. The ability of CBCT-sialography to reconstruct in three dimensions, allowing
for visualization from any angle and slice thickness, is a significant benefit over
conventional techniques. It is useful to obtain cross-sectional slices in different
directions to illustrate intricate anatomical regions, like the anterior parotid duct's
trajectory over the anterior border of the masseter, the path of ducts toward the
parotid gland's deep pole, and the course of the submandibular duct over the posterior-free
border of the mylohyoid. Planning interventional procedures like balloon dilatation
of strictures and basket retrieval of sialoliths may also benefit from this strategy.[11 ] For complex situations with salivary duct obstruction, where standard plain film
sialography is regarded as insufficient and has proven unsatisfactory, the use of
CBCT imaging in sialography is indicated.[12 ]
Materials and Methods
The current study was performed in compliance with guidelines established by the Preferred
Reporting Items of Systematic Reviews and Meta-Analysis (PRISMA) declaration.[13 ]
Eligibility Criteria
The following PECO strategy's criteria were met by all included studies:
Participants : Individuals with nontumorous salivary gland pathologies like sialolithiasis, ductal
strictures, space-occupying lesions, and Sjogren's syndrome. Studies utilizing phantom
models replicating the human body as well as thermo-luminescent dosimeters to evaluate
the radiation exposure in the process of Sialo-CBCT and formulating a protocol for
the same.
Exposition : Sialography combined with CBCT to other imaging modalities like US, plain film radiography,
MR-sialography, CT-sialography.
Control : Individuals with salivary gland pathologies identified by imaging modalities other
than sialography, combined with CBCT.
Outcome : To evaluate the relative merits of sialography plus CBCT, or Sialo-CBCT, in comparison
to other imaging modalities like US, MR-sialography, CT-sialography, and plain film
radiography in assessing the pathology present within the involved salivary gland
contributing toward the sign and symptom presented by the individuals.
Cross-sectional, prospective, case reports, case series, and pilot studies were incorporated
utilizing the PECO strategy. Criteria used for inclusion encompassed studies involving
subjects with nontumorous salivary gland pathologies such as sialolithiasis, ductal
strictures, space-occupying lesions, and Sjogren's syndrome. These studies utilized
the combination of sialography with CBCT, in conjunction with other radiographic investigative
modalities such as sialography, MR-sialography, CT-sialography, US, and plain film
radiography for analysis.
Exclusion criteria were review studies, animal studies, studies performed on tumors,
and salivary gland pathologies.
Information Sources and Search Strategy
A thorough assessment of the literature encompassed studies examining the diagnostic
capability of sialography combined with CBCT (Sialo-CBCT) published up until December
2023. The search strategy employed the PubMed and Web of Science databases. The search
tactics included terms pertaining to sialography, CBCT, Sialo-CBCT, and salivary gland
diseases, and these descriptors were researched in MeSH terms. The protocol was filed
in PROSPERO [CRD42024503038], and the search was performed in accordance with PRISMA
criteria.
Data Extraction
S.S.K. and H.S. independently conducted the data extraction process. The collected
information was organized in a tabular format, categorizing details based on the year
of publication, study type, inclusion and exclusion criteria, assessment of results,
and conclusions drawn from each study. Cross-checking of the data was performed by
the reviewers, and any discrepancies were resolved through discussion. The specific
details can be found in [Tables 1 ] to [3 ].
Table 1
Compilation of research articles studying the diagnostic potential of Sialo-CBCT in
obstructive salivary gland pathologies like Sialolithiasis and Strictures
Author
Aims
Sample
Methods
Main findings
Bertin et al[1 ]
In nontumorous salivary diseases, to assess the diagnostic efficacy of (MR) sialography
against 3D-CBCT sialographic procedures
46 individuals with inflammatory or obstructive conditions
MR and CBCT with contrast
Visualizing sialolithiasis and ductal dilatation was better achieved with MR sialography
than with 3D CBCT-sialography [Sialo-CBCT]
Cetinkaya et al[21 ]
To assess the overall performance of US and Sialo-CBCT in the diagnosis of salivary
gland diseases
236 patients
The outcomes of the US examination were correlated with 3D CBCT-sialography
Sialolithiasis and other major salivary gland diseases were better visualized using
3D CBCT-sialography than with US
Bertin et al[22 ]
To assess 3D CBCT-sialography's diagnostic efficacy in identifying conditions of the
salivary glands other than the tumor ones
27 individuals with persistent discomfort, edema, or recurring infections as their
primary salivary gland symptoms
After injecting 0.5 mL of highly concentrated water-soluble iodinated contrast media
into the salivary ostium, CBCT images were acquired
In addition to detecting mucus plugs, strictures, and dilatations, 3D CBCT-sialography
allowed for the accurate location and quantification of sialoliths, even those with
dimensions less than 2 mm
Elenjickal et al[19 ]
Analyzing 3D CBCT-sialography's diagnostic potential for identifying obstructive salivary
gland disorders
A 60-year-old female patient presenting with a history of persistent discomfort in
the left parotid area
Orthopantomograph was taken, followed by US examination. Sialography was performed
of the left parotid region, followed by acquisition of CBCT scans
CBCT-sialography outperforms conventional sialography in identifying sialoliths and
strictures as well as displaying the gland's ductal system in obstructive conditions
of salivary glands
Abdel-Wahed et al[23 ]
To evaluate the potential of Sialo-CBCT in the identification of various alterations
linked to salivary gland lesions
8 patients who displayed features indicative of salivary gland lesions
For every participant, CBCT-sialography and conventional sialography utilizing digital
panoramic and lateral oblique radiographs were conducted
Compared with traditional sialography, CBCT-sialography revealed more sialoliths,
particularly in second- and third-order branches, and revealed regions with strictures
and gland punctuation
Table 2
Compilation of research articles studying the diagnostic potential of Sialo-CBCT analyzing
the ductal architecture
Author
Aims
Sample
Methods
Main findings
Thomas et al[20 ]
To highlight the efficacy of 3D CBCT-sialography as a diagnostic tool for primary
Sjögren's syndrome
44-, 65-, and 75-year-old female patients who presented with dryness of the mouth,
recurrent swelling of the parotid region, and burning mouth sensation
The right and left parotid ductal orifices were injected with 4 mL of iodinated contrast
media, and then 3D CBCT-sialography was performed
The investigation of salivary gland diseases was made possible by 3D CBCT-sialography,
which also allowed for the picturization of the intraglandular ductal anatomy and
the detection of the appearance associated with Sjogren's syndrome—cherry blossom
Kroll et al[24 ]
To track the application of CBCT-sialography in cases where ultrasonography proved
unsatisfactory for the identification of diseases within the intralobular ductal system
14 patients suffering from recurrent pain and swelling of the major salivary glands
Diagnostic US examination was performed initially. The enlarged gland's efferent duct
dilated to a gauge of 22, after which a contrast agent was injected and CBCT images
were obtained
The ductal system of the gland was visualized till the sixth branch with the help
of 3D CBCT-sialography and allowed diagnosis of undetected intraglandular pathologies
Jadu and Lam[5 ]
To evaluate the diagnostic efficacy of the newest modality, 3D CBCT method versus
2D sialography
47 individuals suspected of blockage of major salivary glands
Sialography was performed, followed by acquisition of a lateral skull plain image
and CBCT images
To observe the intricate structures of the salivary glands, sialoliths, ductal strictures,
and distinguish between normal architecture and architecture resulting from inflammatory
alterations, CBCT-sialography may be superior to conventional film sialography
Drage and Brown[11 ]
To assess the 3D CBCT-sialography's diagnostic capacity to investigate occlusion of
the salivary glands
59- and 54-year-old patients with recurrent swelling of the right submandibular and
right parotid gland, respectively
Sialogram was performed initially, and later CBCT images were acquired following injection
of contrast medium into the involved salivary gland
The CBCT scan revealed calculi that could otherwise be hidden by contrast, and major
and primary intraglandular ducts and their blockage
Table 3
Compilation of research articles conducted for dose optimization protocols in Sialo-CBCT
Author
Aims
Sample
Methods
Main findings
Douglas et al[18 ]
To create strategies for CBCT-sialography that minimize the radiation dose to patients
and enhance the quality of the images obtained for the main salivary glands
25
Dosimeters were placed corresponding to the anatomical position of major salivary
glands and imaging was performed using 70, 85, 100 kVp and 3, 6, and 9 mA
Since the beam of X-ray has to pass through the jaw and soft tissues to reach the
submandibular and parotid glands, respectively, the signal difference to noise ratio
was lower for the submandibular gland protocol than for the parotid gland
Jadu et al[17 ]
To refine the technique by optimizing the image signal difference-to-noise ratio (SDNR)
and data acquired will be compared with the previously published data of dosimetry
for CBCT-sialography
Dry mandible along with four imaging iodine phantoms were used, each with a concentration
of 180, 160, 140, as well as 120 mg/mL
CBCT scans of the iodine phantoms along with the mandible are obtained at 80 kVp and
10 mA. After deducting the mean pixel value (MPV) recorded in a neighboring ROI with
only background water (ROIW ) recorded in an iodine phantom (ROII ), the signal difference (SD) was computed. Pixel SDNR was determined
Keeping mA constant resulted in a positive correlation between an increase in mA and
SDNR, with the computed SDNR rising in proportion to kVp
Jadu et al[16 ]
Employing CBCT and plain radiography for comparison of the effective doses of radiation
from the traditional sialography of the major salivary glands
This investigation used a head and neck RANDO. The amount absorbed at each of the
25 places was recorded using TLD-100 chips
Orienting the phantom in the unit, the imaging field was centered on the left major
salivary glands, 15 and 10 mA, along with kVp of 120,100, and 80, and 30 cm, 23 cm,
and 15 cm FOV were used for images
According to variations noticed in the parameters like FOV, kVp, and mA for CBCT,
the effective dosage changed. Significantly, the computed E was reduced by around
40% when the FOV was decreased from the bigger size to the next available lower size
Study Risk of Bias Assessment
The checklist developed by Hawker et al[14 ] and numerically adjusted by McEvoy et al[15 ] was used to assess each study's risk of bias. The scale was calibrated using the
subsequent values 4, 3, 2, 1 corresponding to the descriptions of good, fair, poor,
and very poor, respectively, and summarized in [Table 4 ].
Table 4
Methodological quality of selected articles determined according to the studies of
Hawker et al and McEvoy et al
Checklist
Bertin et al[1 ]
Bonnet et al [2023]
Douglas et al[18 ]
Thomas et al[20 ]
Bertin et al[22 ]
Kroll et al[24 ]
Tatu Joy et al [2015]
Shoaleh and Shahrm [2014]
Jadu and Lam[5 ]
Abdel-Wahed et al[23 ]
Jadu et al[16 ]
Jadu et al[16 ]
Drage and Brown[11 ]
1. Abstract and title: Clear study description?
4
4
4
4
4
4
4
4
4
4
4
4
4
2. Introduction and aims: Background and research aim mentioned?
4
4
4
4
4
4
4
4
3
3
4
3
3
3. Method and data: Appropriate method was used and description written?
4
4
3
4
4
3
3
3
3
4
4
4
4
4. Sampling: Sampling strategy used in the study could address the aims?
3
3
3
3
3
3
3
3
3
3
3
3
3
5. Data analysis: Was the data analysis sufficiently rigorous?
3
4
3
3
3
3
3
4
3
3
4
4
4
6. Ethics and bias: Have ethical issues been addressed, ethical approval obtained?
4
4
4
4
4
4
4
4
4
4
4
4
4
7. Results: findings of the study clearly written?
4
3
4
3
4
4
4
4
4
4
4
4
4
8. Transferability or generalizability: Are the study findings generalizable to a
wider population?
4
4
4
4
4
4
4
4
3
3
3
3
3
9. Implications and usefulness: How important are findings of study to policy and
practice?
4
3
4
4
4
3
3
3
4
4
4
3
3
Total
34
33
33
33
34
32
32
33
34
32
34
32
32
Note: The numerical values are assigned to each evaluated items: good = 4, fair = 3,
poor = 2, very poor = 1 [lower scores = poor quality].
Results
Selection of Studies
Initially, 20 articles were identified. Screening of titles and abstracts was done
and seven articles were not included in the final review due to duplicates, other
than English language literature, and unavailability of full text. A total of 13 studies
were included and underwent data extraction. The study identification flowchart, aligned
with PRISMA guidelines, is depicted in [Fig. 1 ], outlining the reasons for article exclusion.
Fig. 1 PRISMA flow chart.
Study Characteristics
This review incorporated a total of 13 studies, with 3 studies[16 ]
[17 ]
[18 ] focusing on phantom models to optimize the effective dose and image quality achievable
through Sialo-CBCT. Additionally, four studies[2 ]
[11 ]
[19 ]
[20 ] presented case reports, while the remaining six[1 ]
[5 ]
[21 ]
[22 ]
[23 ]
[24 ] involved comparative evaluations with alternative imaging modalities such as US,
plain film radiography, MR-sialography, and CT-sialography. The research encompassed
the implementation of Sialo graphic procedures, which involve introducing the contrasting
media in the gland's ductal architecture, in conjunction with 3D CBCT (Sialo-CBCT).
This approach aimed to visualize ductal anatomy, alongside various imaging modalities
such as US, MR-sialography, plain film radiography, and CT-sialography. The objective
was to assess the superiority of Sialo-CBCT over other imaging modalities in detecting
nontumorous salivary gland conditions.
Results of Data Synthesis
Studies Performed on Phantom Models
CBCT-sialography happens to be infrequently performed, with only a limited number
of cases documented in the literature. Studies were performed on phantom models[16 ]
[17 ]
[18 ] that included a human skull and a dry mandible wrapped in isocyanate rubber and
exhibiting radiation attenuation properties in line with those of soft tissues of
the human body to analyze as well as determine the effective dosage associated with
Sialo-CBCT. The use of optically stimulated and calibrated luminescent dosimeters
revealed that modifying the field of view (FOV), tube voltage (kVp), as well as tube
current (mA) could alter the effective dose. These studies demonstrated that the estimated
effective doses attained from CBCT scans of the major salivary glands were in line
with those obtained from the plain radiograph sialography. This similarity was achieved
by opting for a smaller FOV in conjunction with lower tube voltage (kVp) and tube
current (mA) settings. The radiation dose was significantly reduced by consistently
modifying the technical parameters, highlighting the significance of taking these
changes into account to guarantee that patient radiation doses stay as low as practically
possible.
Comparison of Sialo-CBCT with Other Imaging Modalities
Sialo-CBCT with MR-Sialography
In the comparison between CBCT combined with sialography and MR-sialography,[1 ] it was observed that CBCT lacked the capability to detect radiolucent calculus,
constituting 10 to 20% of all sialolithiasis cases. MR-sialography demonstrated superior
performance in visualizing sialolithiasis compared with Sialo-CBCT. Additionally,
Sialo-CBCT faced limitations in detecting large sialoceles, although it allowed visualization
up to the last branch of the division of ductal anatomy.
Sialo-CBCT with Standard Sialography
Intricate features inside the paired major salivary glands seem to be easily visualized
with CBCT-sialography than with standard film sialography. It is excellent in differentiating
between normal salivary glands and those that are displaying secondary inflammatory
alterations, as well as in recognizing sialoliths and mild ductal strictures.[5 ] Comparing CBCT-sialography to conventional sialography, it was found to be more
effective in diagnosing sialolithiasis, especially in the second- and third-order
branches. It was also excellent at displaying strictured areas and the glands' punctuated
appearance.[23 ]
Sialo-CBCT with Ultrasonography
The sensitivity and negative predictive value reported in the study conducted to compare
the diagnostic capabilities of Sialo-CBCT and US suggested that Sialo-CBCT excelled
in visualizing sialolithiasis and detecting major salivary gland pathologies compared
with US. It is noteworthy that CBCT induces artificial ductal expansion, while US
identifies spontaneous dilatation of salivary ducts.[21 ]
Sialo-CBCT with CT-Sialography
Sialo-CBCT, like CT-sialography, can detect the quantity and exact position of salivary
stones, even those with a diameter of less than 2 mm. However, it is important to
note that Sialo-CBCT does not provide insights into the functionality of the gland.
When it comes to detecting stones, mucus plugs, strictures, and dilatations, Sialo-CBCT
showcases superior performance compared with CT-sialography.[22 ]
In Vivo Studies Performed on Patients with Salivary Gland Pathologies
Studies in Patients with Obstructive Pathologies of Salivary Glands
In their research, Drage and Brown described two cases of female patients in their
sixth decades of life displaying the usual signs and symptoms of salivary blockage.[11 ] According to their results, CBCT-sialography was able to easily identify the obstruction,
secondary duct, and primary duct in each patient. They also concluded that the radiation
dose associated with CBCT-sialography is higher than that of plain image sialography,
but it is still equivalent to that of fluoroscopic sialography.[11 ] 3D sialography outperformed 2D sialography in the findings of Jadu and Lam[5 ] for both recognizing sialoliths (p = 0.02) and observing the parenchymal substance of the gland (p < 0.001). Its remarkable sensitivity in identifying aberrant glands displaying inflammatory
alterations was observed by them. Similarly, Kroll et al[24 ] in their study concluded that 3D CBCT-sialography permitted the imaging of the gland's
ductal system architecture in three dimensions, all the way to the sixth branch, as
well as the peripheral ducts. They thought it to be a potentially useful additional
diagnostic tool for identifying the reasons for recurrent salivary gland enlargement
and conditions pertaining to the intraglandular ductal system. This improved diagnostic
precision was ascribed to the isotropic voxel resolution that CBCT provides, which
sets it apart from other radiographic diagnostic modalities.
Studies Performed in Patients with Sjögren's Syndrome
A study on patients with primary Sjogren's syndrome showed that the intraglandular
ductal system could be seen, and salivary gland diseases in peripheral ducts could
be analyzed using 3D CBCT-sialography.[20 ]
Studies Performed in Patients with Nontumor Chronic Inflammation of Salivary Glands
Using 3D CBCT-sialography, Bertin et al examined 27 individuals exhibiting symptoms
associated with the paired major salivary glands. They put forward the proposal of
utilizing 3D CBCT-sialography in cases of nontumorous chronic inflammatory salivary
gland diseases, thereby facilitating the accurate assessment of the ductal system.
The main lesions found were mucous plugs and lithiasis, which were found in ∼29.6%
of patients due to an abnormality associated with the filling of the duct. Furthermore,
a noticeable “dead tree appearance” was observed in 25.9% of subjects due to persistent
salivary injury.[22 ]
Discussion
Along with other minor salivary glands located inside the oral mucosa, the paired
submandibular, parotid, and sublingual glands are responsible for the production and
release of saliva into the oral cavity. The normal functioning of these glands can
be disrupted by a variety of disorders and conditions, but the most common disruptions
are obstructive and arise from the mucoid impaction or as a result of calcifications
within the intraductal architecture, the pathological condition being termed “sialolithiasis.”[25 ] To diagnose nontumoral salivary gland conditions, traditional sialography was considered
to be the gold standard because it directly opacifies the salivary ducts. By virtue
of its capacity to do a detailed analysis of the ductal system and provide images
of late evacuation, this method makes it easier to assess salivary gland function
and identify obstructive disorders.[26 ]
[Fig. 2 ] represents the normal sialographic appearance of the right parotid gland obtained
by injecting 3 to 4 mL of nonionic contrast media Omnipaque 350 mgI/mL via 24G cannula
into the right Stenson's duct orifice under fluoroscopic guidance.
Fig. 2 (A ) Right lateral view showing the normal sialographic study of the right parotid gland.
(B ) Anteroposterior view showing the normal sialographic appearance of the right parotid
gland.
Indications for Various Salivary Gland Imaging Modalities
Sialography
Owing to its great spatial resolution and capacity to investigate the ductal tree,
traditional sialography is considered to be the gold standard for diagnosing nontumoral
salivary gland pathologies. The acquisition of evacuation images in the later phase
of the procedure enhanced the understanding of gland function.[22 ] By passing a contrast substance into the duct opening, sialography, which was first
performed in 1902, can investigate the salivary glands' ductal architecture. This
process usually entails taking plain radiographic images and injecting contrasting
material that is water-soluble within the internal ductal system of the glands to
identify strictures, sialoliths, and the ductal structure.[4 ]
[Fig. 3 ] displays a case of chronic sialadenitis of the left submandibular gland with sialography
performed via injecting 370 mg/mL via 24G cannula into the left Wharton's duct under
aseptic conditions.
Fig. 3 Left submandibular gland calculus with few small peripheral cystic dilatations of
tertiary ducts and contrast collection within the gland, suggestive of sialolithiasis
with chronic sialadenitis.
Computed Tomography
For the detection of bony erosions caused by malignant lesions, tiny calculi inside
the salivary gland or duct, and inflammatory conditions like abscesses, calculi, significant
dilatation of the duct, and inflammation in the acute stage, CT is the recommended
imaging modality. Furthermore, CT is helpful for individuals for whom MRI is contraindicated.
Coronal and sagittal reconstructions help determine the extent of perineural dissemination,
and enhanced CT can be used to stage malignant conditions affecting the salivary glands.[27 ]
Ultrasonography
Since it may be performed by the attending physician, exposes the patient to no radiation,
and provides enough imaging accuracy to diagnose a large number of cases, US is currently
the preferred imaging modality for examining salivary glands. But the salivary ductal
system must be full for the US to picture it well enough. Salivary ducts may already
be filled as a result of obstructive diseases such as salivary stones or duct stenosis,
or they can be purposefully filled by giving ascorbic acid orally to stimulate salivary
flow. Contrast agent administration performed retrogradely, as in sialography, can
improve ductal system visibility in US. One drawback of the US is that it can be difficult
to distinguish conditions other than sialolith-induced blockage when attempting to
determine the reason for recurrent salivary gland enlargement.[28 ]
Sialoendoscopy
As an additional method for treating and diagnosing disorders of the salivary glands,
sialoendoscopy has gained popularity. Using this technique in conjunction with a combined
strategy, Koch et al showed a preservation rate of more than 97% for salivary glands
impacted by stenoses in the Wharton or Stenson ducts. It is crucial to remember that
this method only works for conditions outside the glandular duct anatomy or those
that are in close proximity to the hilum.[29 ]
Sialo-CBCT
CBCT provides fast 3D image volume capture, which has enabled modern practice to overcome
the constraints of spiral CT and MRI radiography. Due to its intrinsic benefits, which
include brief scanning periods, a high degree of resolution, and reduced patient exposure
to radiation, CBCT has become widely accepted in the most recent years and hence revolutionized
the field of radiology pertaining to the oral and maxillofacial region.[2 ]
Clinical Applications of Sialo-CBCT
In 2009, Drage and Brown introduced CBCT-sialography in a case study featuring two
females experiencing blockage of salivary glands. The right submandibular gland featured
a sialolith in the first individual, and interventional radiography was used to treat
a stricture and sialolith in the parotid gland of the right side in the latter. Using
CBCT-sialography, the authors were able to successfully visualize the main duct, branches
of the duct, and blockages in the two scenarios. They advocated for the application
of CBCT-sialography when conventional sialography was deemed insufficient for complicated
cases of blockage in the salivary ducts. They approximated the radiation doses administered
to patients during CBCT-sialography. They concluded that the exposure of 96 to 134
mSv was similar in line with the traditional fluoroscopic techniques (34–113 mSv).[11 ]
A new method of acquiring the radiographic images of the paired major salivary glands
using a combination of CBCT and sialography was initially put forward by Jadu et al
through a series of experiments.[16 ] In their 2013 study, they found that CBCT pictures were better at displaying the
complex branches of the ducts and parenchymal substance of the gland than plain film
sialography. According to Jadu et al, the effective dose of radiation from the 3D
CBCT-sialography procedure may vary from 76 microSv (parotid gland) to 170 microSv
(submandibular gland). Their calculations showed that these effective doses of radiation
(parotid: 65 microSv and submandibular: 156 microSv) were similar to those linked
to traditional sialography.[5 ]
A paraclinical investigation of the etiology of nonlithiasis salivary gland blockages
was conducted and reported by Varoquaux et al in 2011. In this work, the viability
and efficacy of utilizing a flat panel Cone beam with Flat Panel (CPCT) for CBCT in
conjunction with sialography were investigated. The use of 3D CPCT-sialography, as
they concluded, made it possible to identify gland ducts that extended to their fifth
or sixth branch. Moreover, they noted enhancements in the signal-to-noise ratio and
signal strength.[30 ]
[31 ]
Advantages
Compilation of data obtained culminated in the finding that CBCT-sialography seems
more effective than traditional sialographic procedures in interpreting images and
recognizing small structures of the major salivary glands. This involves distinguishing
between salivary glands that are normally functioning and those that are displaying
inflammation-related alterations, as well as spotting sialoliths and single ductal
strictures.[19 ]
The capacity to visualize images from several planes, the removal of superposed structures,
and the 3D character of the radiographic scans are some of the advantages the researchers
attributed to CBCT images' superiority over 2D plain radiography.[23 ]
In comparison to conventional sialography and MRI-sialography, Sialo-CBCT exhibits
enhanced resolution rate with scan times and reconstruction of 3D images enabled at
a faster pace.[32 ]
In comparison to CT-sialography, Sialo-CBCT has reduced radiation exposure with visualization
of sialoliths better than MRI-sialography.[17 ]
Disadvantages
The 3D images acquired from CBCT-sialography were incapable of exposing lesions that
occupied space. Comparatively speaking, 3D scans are typically more effective in identifying
doctitis, sialectasia, and filling abnormalities.[8 ]
No adequate literature evidence on the usefulness of Sialo-CBCT as a diagnostic method
for space-occupying lesions.[24 ]
As the modality has lessened soft tissue contrast compared with other imaging modalities,
Sialo-CBCT is not appropriate for inflammatory or functional gland disorders.[33 ]
The comparison between the imaging modalities is summarized in [Table 5 ].
Table 5
Comparison between various salivary gland imaging modalities
Parameter
CBCT-sialography
Conventional sialography
MRI-sialography
CT-sialography
Sensitivity in pathology detection
High for sialoliths and ductal pathology
High for sialoliths and strictures
High for inflammatory and functional pathologies
High for sialoliths and ductal pathology
Specificity in pathology detection
High
High
High for glandular diseases
High
Radiation dose
Lower than CT; higher than MRI
Moderate
No radiation
High
Soft tissue visualization
Poor
Poor
Excellent
Moderate
Visualization of the ductal system
Excellent
Excellent
Moderate to good
Excellent
Patient comfort
Better than conventional sialography
Discomfort due to catheterization
Noninvasive
Moderate
Availability and cost
Moderate
Moderate
Expensive
Expensive
Conclusion
For diseases of the salivary glands, including sialolithiasis, strictures, and ductal
anomalies, CBCT-sialography is an invaluable imaging technique. Though it lacks the
ability to assess soft tissues like MRI-sialography does, it has the best spatial
resolution and less radiation than CT-sialography. Potential noncontrast CBCT uses,
dose optimization, and standardized techniques should all be investigated. Future
research is needed to ascertain its significance in functional salivary gland problems
and long-term cost-effectiveness.
