The salivary ducts of Wharton and Stenson: Analysis of normal variant sialographic morphometry and a historical review

MR sialographic assessment of the masseter muscle and the ductal kinking in patients with recurrent parotitis

Dysfunction of the masseter muscle may cause pathological kinking of the parotid duct leading to parotitis; MR sialography is a non-invasive radiological examination that allows to evaluate dynamically the ductal system of the parotid glands. In the present study we aimed to assess the relationships between Stensen's duct and masseter muscle and their implications in the aetiopathogenesis of recurrent parotitis secondary to masseter muscle dysfunction. Forty-one patients with recurrent unilateral parotitis and nine with bilateral recurrent parotitis, all with a clinical suspicious of masseter muscle hypertrophy due to bruxism were enrolled. They underwent ultrasonography as a first line examination and then MR sialography and sialendoscopy. Different anatomical features were studied. Involved parotid glands had a wider duct compared to contralateral unaffected parotid glands of patients with recurrent parotitis (p = 0.00134); male subjects with parotitis had a longer duct compared to the salivary glands of healthy patients (p = 0.00943 for affected glands and p = 0.00629 for the contralateral). A concordance between the evidence of an acute duct angle during sialendoscopy and a wider duct in patients with parotitis was observed although not statistically significant. These initial findings suggest that the masticatory muscle dysfunction related to bruxism seems to condition alteration of parotid duct course and anatomy thus favouring the occurrence of recurrent parotitis. A specific diagnostic iter based on clinical evaluation, dynamic ultrasonography and MR sialography, is therefore, mandatory to confirm the relationship between masseter muscle anatomy and parotid duct anomalies; this is the premise for an adequate therapeutic approach to underlying masticatory muscle disorder.

Optimizing effective dose and image quality in cone beam CT sialography

OBJECTIVES

The purpose of this study was to develop protocols that optimize patient radiation dose and image quality for cone beam computed tomographic (CBCT) sialography for the major salivary glands.

STUDY DESIGN

Radiation absorbed dose measurements were repeated in triplicate using 25 sites in the head and neck of a Radiation ANalog DOsimetry system (RANDO) phantom, and effective doses were calculated across a range of peak kilovoltage (kVp) and milliamperage (mA) settings using an 8 cm (diameter) by 5 cm (height) field of view (FOV) for submandibular imaging and an 8 cm (diameter) by 8 cm (height) FOV for parotid imaging. Image signal difference-to-noise ratio (SDNR) was determined, and the figure-of-merit (FOM), a measure of image quality, was calculated.

RESULTS

For submandibular sialography, 85 kVp and 6 mA were chosen as the optimal exposure parameters, resulting in a mean effective dose of 82.47 µSv and a mean SDNR of 13.86, with a mean FOM of 2.33 µSv^-1. For parotid sialography, 70 kVp and 6 mA were chosen, and these settings resulted in a mean effective dose of 39.99 µSv, a mean SDNR of 17.43, and a mean FOM of 7.60 µSv^-1.

CONCLUSIONS

Low-dose 3-dimensional sialography with high image quality and minimal effective dose can be delivered using CBCT with localized, small FOVs.

Retrograde Migration of an Au-198 Grain to the Submandibular Gland Post Brachytherapy Treatment of Floor of Mouth Cancer

At our institution, radiation oncologists routinely treat early-stage oral cancer with low-dose-rate brachytherapy (LDR-BRT) using Au-198 grains. In this report, we show a unique case of a patient with a gold grain located within the submandibular gland, found incidentally during follow-up after LDR-BRT for floor of mouth cancer. One month after the implant, he showed sialadenitis-like symptoms, but the pain resolved two months later. All the grains were detected around the anterior sublingual area by computed tomography (CT) four months after the implant. Unexpectedly, 11 months after the implant, CT revealed that a grain was located in an intraglandular site of the submandibular gland. This finding clearly demonstrates that the grain entered Wharton's duct and retrogradely migrated to the submandibular gland through the duct. As a mechanism of the calculus formation within Wharton's duct, retrograde migration of foreign bodies to the inside of the duct has been proposed. Our incidental finding after LDR-BRT highlights the need for monitoring post-LDR-BRT using Au-198 grains for the treatment of floor of mouth cancer and sheds additional light on retrograde theory within Wharton's duct.

Anatomical Features of the Parotid Duct in Sialography as an Aid to Endoscopy—A Retrospective Study

Sialography is used for diagnosis of obstructive salivary gland diseases and prior to sialendoscopy. Three-dimensional cone beam computerized tomography (CBCT) sialography allows imaging and measurement of salivary duct structures. Salivary gland endoscopy has a long learning curve. The aim of this retrospective study is to create an anatomical quantitative guide of different distances and angles significant for endoscopy. Twenty-six CBCT sialographies of healthy parotid ducts were included. Outcome parameters included diameters, distances, angles and number of minor tributaries. Results show the average distance from the papilla to the curvature of the gland was 41.5 mm (Q1 36.97 mm–Q3 45.32 mm), with an angle of 126.9° (Q1 107.58°–Q3 135.6°) of the curvature and a distance of 35.25 mm (±7.81 mm) between the curvature and the hilus. The mean width of the duct was 0.8 mm (Q1 0.7 mm–Q3 1.15 mm) at its narrowest and 2 mm (Q1 1.4 mm–Q3 2.2 mm) at its widest. This is the first anatomical quantitative study of the parotid duct in relation to sialendoscopy.

Establishing correlations between normal pancreatic and submandibular gland ducts

Background

The objectives of this study were to evaluate the relationship between ductal morphometry and ramification patterns in the submandibular gland and pancreas in order to validate their common fractal dimension.

Methods

X-ray ductography with software-aided morphometry were obtained by injecting barium sulphate in the ducts of post-mortem submandibular gland and pancreas specimens harvested from 42 adult individuals.

Results

Three cases were excluded from the study because of underlying pathology. There was a significant correlation between the length of the main pancreatic duct (MPD) and the intraglandular portion of the right submandibular duct (SMD) (r = 0.3616; p = 0.028), and left SMD (r = 0.595; p < 0.01), respectively, but their maximal diameters did not correlate (r = 0.139—0.311; p > 0.05). Both dimensions of the SMD showed a significant right-left correlation (p < 0.05). The number of MPD side branches (mean = 37) correlated with the number of side branches of left SMD, but not with the right one (mean = 9). Tortuosity was observed in 54% of the MPD, 32% of the right SMD, and 24% of the left SMD, with mutual association only between the two salivary glands.

Conclusions

Although the length of intraglandular SMD and MPD correlate, other morphometric ductal features do not, thus suggesting a more complex relationship between the two digestive glands.

Effectiveness of sialendoscopy on the symptoms of chronic obstructive sialadenitis and patient satisfaction degree

OBJECTIVES

The purpose of this study was to assess the effectiveness of sialendoscopy (SE) on the symptom severity of chronic obstructive sialadenitis (COS) and patient satisfaction by using the Chronic Obstructive Sialadenitis Symptoms (COSS) questionnaire and the Patient Satisfaction Scores (PSS).

PATIENT AND METHODS

COSS questionnaire was employed to 51 Turkish patients with COS before and three months after SE. Patients' satisfaction with SE was evaluated by analyzing the PSS.

RESULTS

Gland preservation rate of the SE operation was 96.2%. The sialolith extraction rate was 74.2%. A significant decrease in the COSS scores of all of the patients in the study sub-groups was observed (p < 0.05). The effectiveness of SE was more pronounced for patients with sialolithiasis and submandibular gland (SG) involvement (p < 0.001, p = 0.03, respectively). Totally extracted stone and symptom duration were the only independent factors that significantly affected the COSS score gain values in patients with and without sialolithiasis, respectively (p < 0.001). There was a statistically significant correlation between COSS score gain values and PSS values. (r = 0.786) CONCLUSION: The benefit of SE was more pronounced in patients with sialolithiasis and SG involvement. Successful stone extraction and symptom duration were two independent factors that influenced both clinical improvement and patient satisfaction for patients with and without sialolithiasis, respectively. COSS questionnaire results correlated with the PSS values; thus, this questionnaire can also be used to evaluate the patients' satisfaction with SE.

Self-adaptive weighted level set evolution based on local intensity difference for parotid ducts segmentation

BACKGROUND

Parotid ducts (PDs) play an important role in the diagnosis and treatment of parotid lesions. Segmentation of PDs from Cone beam computed tomography (CBCT) images has a significant impact to the pathological analysis of the parotid gland. Although level set methods (LSMs) have achieved considerable success in medical imaging segmentation, it is still a challenging task for existing LSMs to precisely and self-adaptively segment PDs from parotid duct (PD) images with both noise, intensity inhomogeneity, and vague boundary. In this paper, we propose a novel Self-adaptive Weighted level set method via Local intensity Difference (SWLD) to comprehensively solve the above issues.

METHOD

Firstly, a new adaptive weighted operator based on local intensity variance difference has been proposed to overcome the limitations of previous LSMs that are sensitive to parameters, which achieves the aim of automatic segmentation. Secondly, we introduce local intensity mean difference into the energy function to improve the curve evolution efficiency. Thirdly, we eliminate the effects of intensity inhomogeneity, noise, and boundary blur in the parotid image through a local similarity factor with two different neighborhood sizes.

RESULTS

Using the same dataset, segmentation of PDs is performed using the proposed SWLD algorithm and existing LSM algorithms. The mean Dice score for the proposed algorithm is 91.3%, and the corresponding mean Hausdorff distance (HD) is 1.746.

CONCLUSION

Experimental results demonstrate that the proposed algorithm is superior to many existing level set segmentation algorithms, and it can accurately and automatically segment the PDs even in complex gradient boundaries.

Unusual Conditions Impairing Saliva Secretion: Developmental Anomalies of Salivary Glands

Salivary glands (SG) arise from ectodermal tissue between 6 and 12th weeks of intrauterine life through finely regulated epithelial-mesenchymal interactions. For this reason, different types of structural congenital anomalies, ranging from asymptomatic anatomical variants to alterations associated with syndromic conditions, have been described. Notable glandular parenchyma anomalies are the SG aplasia and the ectopic SG tissue. Major SG aplasia is a developmental anomaly, leading to variable degrees of xerostomia, and oral dryness. Ectopic SG tissue can occur as accessory gland tissue, salivary tissue associated with branchial cleft anomalies, or true heterotopic SG tissue. Among salivary ducts anomalies, congenital atresia is a rare developmental anomaly due to duct canalization failure in oral cavity, lead to salivary retention posterior to the imperforate orifice. Accessory ducts originate from the invagination of the developing duct in two places or from the premature ventral branching of the main duct. Heterotopic ducts may arise from glandular bud positioned in an anomalous site lateral to the stomodeum or from the failure of the intraoral groove development, hindering their proximal canalization. These anomalies require multidisciplinary approach to diagnosis and treatment. While ectopic or accessory SG tissue/ducts often do not require any treatment, patients with SG aplasia could benefit from strategies for restoring SG function. This article attempts to review the literature on SG parenchyma and ducts anomalies in head and neck region providing clinicians with a comprehensive range of clinical phenotypes and possible future applications of bioengineered therapies for next-generation of regenerative medicine.

Feasibility of Parotid Duct Transposition for the Treatment of Dry Eye: A Cadaveric Study

Total dry eye is encountered less frequently, but it may lead to blindness. Transposition of parotid duct to the conjunctival cul-de-sac is a method of treatment for advanced cases of xerophthalmia to prevent blindness. Tears and parotid secretions have similar composition; therefore saliva provides an excellent replacement for tears. Limitation of this procedure is that the length of the parotid duct may not be adequate to reach the conjunctival cul-de-sac. This study was conducted in 30 fresh cadavers to assess the length of parotid duct and technical feasibility of parotid duct transposition for the treatment of dry eye. The parotid duct was dissected and resting length of parotid duct was measured on both sides without stretching. The distance between ear lobule to lateral canthus was also measured on both sides in each cadaver. The length of parotid duct ranges from 4.5 to 7 cm with average length was 5.8 cm. The majority of the cadavers had parotid duct length of 6 cm. Length of the right and left parotid duct was found to be equal in all cadavers. Parotid duct reached comfortably in 24 cadavers (80%) while it was short in 6 cadavers (20%) by 1-1.50 cm in length. Parotid duct can be transposed easily to the lower conjunctival cul-de-sac in majority of the cases. If the parotid duct is falling short than a cuff of the buccal mucosa can be taken in order to gain length.

[A fast adaptive active contour model based on local gray difference for parotid duct]

OBJECTIVE

To establish a fast adaptive active contour model based on local gray difference for parotid duct image segmentation.

METHODS

On the basis of the LBF model, we added the mean difference of the local gray scale inside and outside the contour as the energy term of the driving evolution curve, and the local gray-scale variance difference was used to replaceλ₁ and λ₂ as the control term of the energy parameter value. Two local similarity factors of different neighborhood sizes were introduced to correct the effects of image gray unevenness and boundary blur to improve the segmentation efficiency.

RESULTS

During image segmentation, this algorithm allowed for adaptive adjustment of the evolution direction, velocity and the energy weight of the internal and external regions according to the difference of gray mean and variance between the internal and external regions. This algorithm was also capable of detecting the actual boundary in a complex gradient boundary region, thus enabling the evolution curve to approach the target boundary quickly and accurately.

CONCLUSIONS

The proposed algorithm is superior to the existing segmentation algorithms and allows fast and accurate segmentation of the parotid duct with well-preserved image details.

Role of Salivary Duct Morphology in the Etiology of Chronic Obstructive Parotitis: Statistical Analysis of Sialographic Features and Computational Fluid Dynamics Analysis of Salivary Flow

PURPOSE

The causes of some cases of chronic obstructive parotitis (COP) without obstructive factors are still unclear. The authors hypothesized that some morphologic features of salivary ducts might contribute to the development of COP. This study investigated the role of salivary duct morphology in the etiology of COP.

MATERIALS AND METHODS

The authors designed and implemented a case-and-control study. Cases were defined as patients with COP, diagnosed from September 2014 to May 2017 at the Affiliated Hospital of Stomatology of the Sun Yat-sen University (Guangzhou, China), and controls were healthy participants. The primary predictor variables were the occurrence of an accessory duct (AD), the number of branches uniting to form the Stensen duct (SD), the angle between the AD and the SD, and the angle between branches identified on sialographic computed tomograms. Data from the 2 groups were compared to investigate the association between these variables and COP. The χ² test, Student t test, and logistic regression were computed, with significance set at a P value less than .05. Fluid dynamics analysis was used to analyze salivary flow field in models of salivary ducts with different morphologic features reconstructed from sialographic computed tomograms.

RESULTS

The sample was composed of 39 patients with COP and 18 controls without COP. The 2 groups were not similar for incidences of an AD (71.8 vs 38.9%) and the angle between branches (96.5 ± 26.0° vs 71.5 ± 21.2°). There was no relevant difference between groups in the number of branches and the angle between the AD and the SD. The area of low velocity was larger in the model with the wider angle between branches.

CONCLUSIONS

The results suggest that the presence of an AD and a wider angle between duct branches are associated with COP.

Radiocontrast Dye Extravasation During Sialography

Objective:

Evaluate the pathophysiology of contrast extravasation.

Methods:

Two hundred fifty-five sialograms at the University of Iowa from 2008 to 2016 were reviewed.

Results:

Twelve sialograms (4.7% of total) were identified with main ductal extravasation. In each case, ductal stenosis as a diagnosis was supported by clinical history and the finding of difficulty in advancing the cannula into the duct during sialography. In all but 1 case, extravasation occurred at the distal duct with no further imaging of the ductal system. Each of the 5 cases treated with sialendoscopy with or without gland resection confirmed stenosis. Ultrasound evaluation of 5 of the cases detected ductal dilation in 4 (80%). Six of 11 computed tomography scans done before the sialogram were interpreted as normal with indirect evidence for ductal stenosis (duct dilation) reported in only 1. All extravasations were associated with either stricture alone or stricture with stone (1 case).

Conclusion:

Radiocontrast extravasation from the main duct during sialography is highly associated with the presence of ductal stricture. In our experience, the inability to fill the ductal system with radiocontrast is a useful sialographic finding that correlated closely with anatomic abnormality rather than technical error. The frequent finding of extravasation of radiocontrast supports the use of water soluble contrast.