The role of salivary duct morphology in the aetiology of sialadenitis: statistical analysis of sialographic features

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.

Does three-dimensional intraglandular location predict malignancy in parotid tumors?

Tumors arising within the parotid encompass a heterogeneous mix of benign and malignant neoplasms and other tissue growths. The purpose of this study was to determine the association between the location of intraparotid masses and the risk of malignancy. A retrospective cohort study was performed of patients diagnosed with parotid tumors following open tumor excision. The primary predictor variable was the location of the epicenter of the tumor in three-dimensional space, as determined from preoperative imaging. Other variables were patient demographics and clinical parameters. The primary outcome variable was the final histopathologic diagnosis of a benign or malignant process. A χ² analysis was performed to test for any significant associations between demographic, clinical, and radiographic factors in relation to the outcome, and backwards stepwise logistic regression analysis was used to control for variables. Both increasing age (P = 0.002) and the presence of local pain (P = 0.020) were associated with malignancy. Tumors located anterior to the posterior border of the retromandibular vein had 2.18 times higher odds of malignancy (95% confidence interval 1.13-4.21; P = 0.020). Multivariate regression analysis suggested that patient age, the presence of pain, and tumor location anterosuperiorly and superoinferiorly could all assist in determining the odds of malignancy.

Concurrent giant sialoliths within the submandibular gland parenchyma and distal segment of Wharton's duct: Novel case report

OBJECTIVE

This article discusses the clinical significance of an unusual case of the simultaneous occurrence of 2 giant sialoliths within the ipsilateral submandibular gland and distal aspect of Wharton's duct in a 63-year-old patient.

BACKGROUND

The majority of submandibular gland sialoliths are found in Wharton's duct, with fewer within the gland parenchyma. Giant sialoliths (exceeding 15 mm in size) are rare.

MATERIALS AND METHODS

An asymptomatic, otherwise healthy older patient sought dental care and underwent a comprehensive oral and radiographic examination.

RESULTS

A panoramic radiograph revealed 2 incidental radiopaque structures, representing giant sialoliths within the submandibular gland and along the distal segment of Wharton's duct. This synchronous finding apparently represents the first case reported in the geriatric literature.

CONCLUSIONS

The detection of 1 salivary stone should heighten the scrutiny for additional stones. Practitioners should carefully weigh the risk of sialolith removal versus deferment of treatment in older medically compromised patients.

Description and relationships of the parotid gland levels proposed by the European Salivary Gland Society staging system: an anatomical study

OBJECTIVES

To perform an anatomical study to analyze the size, weight, and the relationships of the parotid levels proposed by the European Salivary Gland Society (ESGS).

MATERIALS AND METHODS

Anatomical dissections of the parotid region in 19 human specimens were performed. All dissections were systematically carried out to study the dimensions and weight of each level. We also studied the facial nerve distribution between the different levels and the relative position of the facial nerve main trunk and parotid duct in regard to the Frankfort line plane.

RESULTS

The facial nerve trunk and the parotid duct were identified in all the 19 specimens, which made it feasible to define the 4 principal levels of the parotid gland body (levels I-IV). Level V was identified in 9 out of 19 dissections (47.5%). For the whole gland, the mean for the height and width dimensions were 66.37 mm and 46.84 mm, respectively, and it weighted 18.13 g. In terms of relative weight regarding the whole gland, level II was always the heaviest, representing from 41 to 47% of the gland's weight, depending on the presence of level V. Levels I and III represent almost the same amount of relative weight as they range from 20 to 22% for each one. Level IV was the lightest body level representing 8-10% of the whole, and when present, level V represented less than 5% of the whole parotid weight. The temporal and zygomatic terminal branches were always found between the cranial levels, whereas the cervical and marginal nerves lie in all cases between the caudal levels. The buccal branches had multiple ramifications that lie between both cranial and caudal levels in 47% of the cases, being found exclusively between cranial levels in 21% and between the caudal levels in the remaining 32%.

CONCLUSION

As traditionally reported, the caudal superficial portion of the gland represents the most voluminous portion of the gland, being labeled in our classification as level II. Levels I and III represent similar amounts of gland, though presenting a significantly different morphological disposition. Level IV is the smallest portion of the body gland and level V, when present represents a scarce 5% of the whole body gland weight. The ESGS levels have a clear anatomical basis and the basic references needed to define them are always present.

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.

Study of morphological structure in human fetus Wharton's duct opening area

OBJECTIVES

Not many morphological studies have been reported regarding the human salivary main duct, especially those based on observations of the fetal salivary main duct at various developmental stages. The relationships between fetal structural development and its function, functional disorders and diseases certainly have clinical significance.

METHODS

In this study, we conducted a morphological observation of seven 5-9 month old human fetal sublingual caruncula, the common opening between the submandibular (Wharton's) duct and the sublingual (Bartholin's) duct. After seven specimens were removed and paraffin sections were prepared, HE and EVG staining were used for histological study of structural differences in the various developmental stages. Furthermore, anti-α-SMA staining was used to observe the distribution of the smooth muscle inside of the Wharton's duct wall.

RESULTS

An abundance of elastic fibers were observed in the duct walls of both five and nine month old specimens with EVG staining. The smooth muscle fibers of five month old fetus were immature and were starting to distribute throughout the duct wall, whereas nine month old fetus' smooth muscle fibers were further developed and composed in layers.

CONCLUSION

In this study, we confirmed that the Wharton's duct wall structure of nine month old fetuses was close to its adult structural formation, while the inner structure consisted of an ample distribution of elastic fibers and smooth muscle fibers. Based on the distribution pattern of the smooth muscle, we speculate that the Wharton's duct's opening area does not possess a sphincter-like function in the regulation of salivary flow.

[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.

Role of the Accessory Parotid Gland in the Etiology of Parotitis: Statistical Analysis of Sialographic Features

This retrospective study aimed to identify if the existence of the accessory parotid gland correlated with the etiology of parotitis. This may aid the development of better treatment strategies in the future. Sialographic features of cases with parotitis and healthy subjects were reviewed. The chi-square test was used to compare the incidence of accessory parotid gland between the groups. The Student's t test was used to compare the length of Stensen's duct, the length from the orifice to the confluence of the accessory duct, and the angle between the accessory duct and Stensen's duct between the groups. The incidence of accessory parotid gland in patients with parotitis was 71.8% (28/39), which was significantly higher than that in healthy subjects (P = 0.005). Patients with parotitis had a longer Stensen's duct than healthy subjects (P = 0.003). There was no significant difference in the length from the orifice to the confluence of the accessory duct or the angle between the accessory duct and Stensen's duct (P = 0.136 and 0.511, respectively) between the groups. The accessory parotid gland might play a role in the pathogenesis of parotitis. The existence of an accessory parotid gland is likely to interfere with salivary flow. Computational fluid dynamics analysis of salivary flow in the ductal system would be useful in future etiologic studies on parotitis.