Cross-Sectional Imaging Techniques and Normal Anatomy of the Salivary Glands

[Salivary gland ultrasound or biopsy? : Comparison of methods based on case examples]

BACKGROUND

Ultrasound examination of the salivary glands (SG) is a quick and noninvasive method to detect and semiquantitatively estimate typical changes in the large SG in Sjögren's syndrome (SS). The differential diagnosis of SS is difficult because several diseases and adverse effects of treatment have a similar clinical picture as SS with sicca syndrome and can even induce alterations in the SG (mimic diseases). Hence, for a long time an SG biopsy was regarded as the diagnostic procedure of choice, especially in SS‑A negative patients, whereas the significance of SD sonography is still controversially discussed.

OBJECTIVE

Comparison of typical and atypical changes for SS in the salivary glands in ultrasound and associated histological sections.

MATERIAL AND METHODS

This article describes six patient cases with antibody positive or negative SS with and without typical SS ultrasound patterns, SS-associated lymphoma, sarcoidosis and IgG4-associated disease. The findings of the sonographic examination of the parotid glands and the associated histology of the SD are explained and put into context.

RESULTS

The SSA antibody positive patients with SS show a typical sonographic pattern with hypoechoic foci, especially if the disease has been present for a long time. This pattern can help support the diagnosis of SS. The ultrasound patterns of the mimic diseases sometimes differ significantly from the typical patterns of pSS. The histological examination of the SG helps to corroborate the diagnosis but low histological focus scores, in particular, require a critical synopsis of the clinical, serological and imaging findings.

CONCLUSION

Both salivary gland ultrasound and the histological examination of SG biopsies are justified in the diagnostics and differential diagnosis of SS and sicca syndrome.

Imaging of Major Salivary Gland Lesions and Disease

Infectious and inflammatory disorders are the commonest pathologies to affect the major salivary glands however frequently overlap in clinical presentation. Imaging plays an important role in diagnosis, usually initially performed by CT or ultrasound. MRI, with its superior soft-tissue characterization compared with CT, provides a better evaluation of tumors and tumor-like conditions. Imaging features may suggest that a mass is more likely to be benign versus malignant, however, biopsy is often needed to establish a definitive histopathologic diagnosis. Imaging plays a key role in the staging of neoplastic disease.

Newly Discovered Parotid Lesion: What Next?

When a parotid lesion is discovered incidentally, it can be challenging for the radiologist to provide specific recommendations for the next steps. This article describes how the radiologist can play an active role in managing incidentally discovered parotid lesions. First, we explore the significance of parotid lesions. Next, the pertinent anatomy of the parotid space is presented to develop an appropriate differential diagnosis. Lastly, we discuss critical clinical and imaging characteristics the radiologist can use to provide specific recommendations.

Progress in salivary glands: Endocrine glands with immune functions

The production and secretion of saliva is an essential function of the salivary glands. Saliva is a complicated liquid with different functions, including moistening, digestion, mineralization, lubrication, and mucosal protection. This review focuses on the mechanism and neural regulation of salivary secretion, and saliva is secreted in response to various stimuli, including odor, taste, vision, and mastication. The chemical and physical properties of saliva change dynamically during physiological and pathophysiological processes. Moreover, the central nervous system modulates salivary secretion and function via various neurotransmitters and neuroreceptors. Smell, vision, and taste have been investigated for the connection between salivation and brain function. The immune and endocrine functions of the salivary glands have been explored recently. Salivary glands play an essential role in innate and adaptive immunity and protection. Various immune cells such as B cells, T cells, macrophages, and dendritic cells, as well as immunoglobins like IgA and IgG have been found in salivary glands. Evidence supports the synthesis of corticosterone, testosterone, and melatonin in salivary glands. Saliva contains many potential biomarkers derived from epithelial cells, gingival crevicular fluid, and serum. High level of matrix metalloproteinases and cytokines are potential markers for oral carcinoma, infectious disease in the oral cavity, and systemic disease. Further research is required to monitor and predict potential salivary biomarkers for health and disease in clinical practice and precision medicine.

Radiomic Analysis of Multi-parametric MR Images (MRI) for Classification of Parotid Tumors

Background

Characterization of parotid tumors before surgery using multi-parametric magnetic resonance imaging (MRI) scans can support clinical decision making about the best-suited therapeutic strategy for each patient.

Objective

This study aims to differentiate benign from malignant parotid tumors through radiomics analysis of multi-parametric MR images, incorporating T2-w images with ADC-map and parametric maps generated from Dynamic Contrast Enhanced MRI (DCE-MRI).

Material and Methods

MRI scans of 31 patients with histopathologically-confirmed parotid gland tumors (23 benign, 8 malignant) were included in this retrospective study. For DCE-MRI, semi-quantitative analysis, Tofts pharmacokinetic (PK) modeling, and five-parameter sigmoid modeling were performed and parametric maps were generated. For each patient, borders of the tumors were delineated on whole tumor slices of T2-w image, ADC-map, and the late-enhancement dynamic series of DCE-MRI, creating regions-of-interest (ROIs). Radiomic analysis was performed for the specified ROIs.

Results

Among the DCE-MRI-derived parametric maps, wash-in rate (WIR) and PK-derived K^trans parameters surpassed the accuracy of other parameters based on support vector machine (SVM) classifier. Radiomics analysis of ADC-map outperformed the T2-w and DCE-MRI techniques using the simpler classifier, suggestive of its inherently high sensitivity and specificity. Radiomics analysis of the combination of T2-w image, ADC-map, and DCE-MRI parametric maps resulted in accuracy of 100% with both classifiers with fewer numbers of selected texture features than individual images.

Conclusion

In conclusion, radiomics analysis is a reliable quantitative approach for discrimination of parotid tumors and can be employed as a computer-aided approach for pre-operative diagnosis and treatment planning of the patients.

Development of a new ultrasound scoring system to evaluate glandular inflammation in Sjögren's syndrome: an OMERACT reliability exercise

OBJECTIVE

The aim of this exercise from the OMERACT ultrasound subgroup on Sjögren's syndrome (pSS) was to develop and assess the reliability of a consensus-based semiquantitative colour Doppler (CD) ultrasound scoring system for pathologic salivary gland vascularization in patients with pSS.

METHODS

Using the Delphi method a CD semiquantitative scoring system for vascularization of bilateral parotid and submandibular glands was developed and tested in static images and on patients (9 pSS patients and 9 sonographers). Intra-reader and inter-reader reliability of grading the salivary glands were computed by weighted Cohen and Light's kappa (κ) analysis, respectively.

RESULTS

The consensus-based semiquantitative score was: Grade 0, no visible vascular signals; Grade 1, focal, dispersed vascular signals; Grade 2, diffuse vascular signals detected in < 50% of the gland; Grade 3, diffuse vascular signals in > 50% of the gland. In static images, the intra- and inter-reader reliability showed excellent κ values (95% confidence interval) = 0.90 (0.87-0.93) and 0.80 (0.74-0.84), respectively) for all four salivary glands together. In patients, the intra- and inter-reader reliability for all four salivary glands together was κ  = 0.84 (0.73-0.92) and 0.70 (0.64-0.76), respectively.

CONCLUSION

The consensus-based CD ultrasound scoring for the evaluation of salivary gland vascularization in pSS showed a good inter-reader reliability and excellent intra-reader reliability in static images and in patients. The clinical application of the developed scoring system should be tested in clinical settings.

Radiographic Interpretation in Oral Medicine and Hospital Dental Practice

Oral medicine practice includes the diagnosis and nonsurgical treatment of oral and orofacial diseases and oral manifestations of systemic conditions. Oral medicine specialists in medical and dental settings often require imaging in assessment and treatment of these conditions. This article reviews imaging that may be used in practice, particularly as relevant for facial pain, bone conditions, and salivary gland disease. It reviews imaging that may be considered in a hospital setting for assessment of admitted patients, patient evaluation before surgical procedures, and provision of dentistry in a hospital setting for patients who cannot submit to treatment in an outpatient setting.

Strain and shear wave ultrasound elastography in evaluation of chronic inflammatory disorders of major salivary glands

OBJECTIVE

The aim of this study was to assess chronic inflammatory conditions of major salivary glands by ultrasound elastography.

METHODS

21 patients with chronic inflammatory conditions of major salivary glands and 21 healthy adult volunteers were included in this study. All participants underwent B-mode sonography and ultrasound elastography. The diagnostic performance of strain ratio and shear wave velocity was evaluated by sensitivity and specificity at the optimum cutoff point and the area under the receiver operating characteristic curve.

RESULTS

Cases showed statistically significant higher median strain ratio of parotid and submandibular gland than control group (p-value = 0.001). Total cases showed statistically significant higher median scores than control group (p-value < 0.001). At cut-off value of (1.13); diagnostic accuracy, sensitivity and specificity were 97.6, 95.2 and 100% respectively with AUROC 0.954 and confidence interval: 0.840-0.995. Cases showed statistically significant higher median shear wave velocity of parotid gland than control group (p-value = 0.022), with no statistically significant difference in submandibular gland in the two groups (p-value = 0.216). Total cases showed statistically significant higher median scores than control group (p-value < 0.001). At cut-off value of (23.5), diagnostic accuracy was 78.6% with a sensitivity of 81% and specificity of 76.2% with 0.819 AUROC and onfidence interval :0.669-0.920.

CONCLUSION

Our initial experience suggests that elastography may be potentially useful for diagnosis of chronic inflammatory conditions of the major salivary glands. This conclusion needs to be further validated large sample studies.

Computed tomographic features of adenoid cystic carcinoma in the palate

Background

To evaluate the computed tomographic features and create a prediction model for clinical diagnosis of adenoid cystic carcinoma (ACC) in the palate with intact mucosa.

Methods

From March 2016 to May 2018, 102 patients with palatal tumors and intact mucosa, including 28 patients with a pathological diagnosis of ACC after surgery, were enrolled in this study. The patients’ clinical symptoms, computed tomographic features and pathological diagnoses were recorded and analyzed. Independent predictors of ACC were determined by using univariate analysis and multivariate logistic regression, and the discrimination and calibration of the prediction model was evaluated, and internal validation was performed.

Results

Univariate analysis of patients showed that ACC patients were more likely than non-ACC patients to be older (P = 0.019); to have palatine bone destruction (P<0.001) and greater palatine foramen (GPF) enlargement (P<0.001); to have involvement of the pterygopalatine fossa (P<0.001), foramen rotundum (P<0.001), nasal cavity (P<0.001) and maxillary bone (P<0.001); and to have numbness (P = 0.007) and pain (P<0.001). Multivariate logistic analysis showed that age and GPF enlargement were independent predictors of ACC in palatal tumors. The diagnostic prediction model showed good discrimination and calibration, as evaluated by the area under the receiver operating characteristic curve (0.98) and the Hosmer-Lemeshow goodness-of-fit test (P = 0.927).

Conclusions

The palate ACC prediction model based on age and GPF enlargement shows excellent discrimination with no evidence of poor calibration. Older patients with palatal tumors and intact mucosa should be considered for ACC when they have GPF enlargement.

Electronic supplementary material

The online version of this article (10.1186/s40644-019-0190-z) contains supplementary material, which is available to authorized users.