Diagnostic Efficacy of Cone Beam Computed Tomography Sialography (Sialo-CBCT) in Salivary Gland Pathologies: A Systematic Review

Abstract

Objective

This article aims to investigate the clinical usefulness of sialography with cone beam computed tomography (CBCT), also known as Sialo-CBCT, for the diagnosis of salivary gland diseases.

Materials and Methods

Literature search was performed in PubMed and Web of Science databases with search terminologies “sialography, cone beam computed tomography sialography, salivary gland diseases.” Thirteen articles that examined the diagnostic potential of Sialo-CBCT were included in the present review. The search complied with PRISMA criteria, and the protocol was registered in the PROSPERO [CRD42024503038].

Results

Out of thirteen publications included in the review, three were studies that optimized the effective dosage and image quality in Sialo-CBCT and ten remaining included imaging performed in patients with salivary gland diseases.

Conclusion

The findings suggest that 3D CBCT combined with sialography has good diagnostic potential in visualizing the ductal subdivisions and anatomy of the salivary glands as well as the identification of salivary gland pathologies. Characteristic features of imaging modalities such as plain radiography, ultrasonography, CT-sialography, MR-sialography, and CBCT-sialography were outlined in the review.

 

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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]

 

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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.

 

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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.

 

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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

 

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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].

 

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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.

 

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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.

 

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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.

 

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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.

 

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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]

 

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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]

 

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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]

 

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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.

 

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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]

 

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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]

 

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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.

 

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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]

 

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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]

 

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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]

 

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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]

 

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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]

 

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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

 

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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.

 

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Conflict of Interest

None declared.

Acknowledgments

The authors would like to thank the Department of Radiodiagnosis, K.S. Hegde Charitable Hospital, NITTE (Deemed to be University), for the sialographic images.

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Publication History

Article published online:
22 August 2025