The Role of Real-Time Elastography in the Differential Diagnosis of Salivary Gland Tumors

Evaluation of submandibular and parotid salivary glands by ultrasonography in patients with diabetes

BACKGROUND

Microvascular complications of diabetes mellitus (DM) include oral manifestations and complications, including xerostomia, reduced salivary flow, susceptibility to infection, periodontal disease and salivary gland enlargement.

OBJECTIVE

The present study aims to evaluate B-mode ultrasonography (USG) parameters such as size, volume and echogenicity of the submandibular and parotid salivary glands on both sides, shear-wave elastography (SWE) value and colour Doppler properties in patients with DM and healthy control groups.

METHODS

In total, 160 right and left submandibular glands and 160 right and left parotid glands of 80 patients, 40 patients (20 type 1 DM, 20 type 2 DM) and 40 healthy control group, between the ages of 18-70 were examined by USG. Echogenicity, parenchyma internal structure, margin and dimensional measurements (antero-posterior length, supero-inferior length, medio-lateral length and volume) and colour Doppler with 'ML 6-15-D Matrix Array (4-15 MHz)' probe, shear-wave elastography '9L-D (2-8 MHz)' probe was investigated.

RESULT

Statistically significant difference was observed in echogenicity in the right submandibular gland, echogenicity in the right parotid gland, margin characteristics, parenchymal homogeneity and colour Doppler characteristics between the type 1 DM, type 2 DM and control groups (p < .05). It was observed that the size, volume and SWE values of both submandibular and parotid glands were higher in the DM patient group than in the control group. Higher values were observed in type 2 DM compared to type 1 DM in the patient group.

CONCLUSION

USG is an effective imaging technique in investigating the effects of diabetes on the submandibular and parotid salivary glands.

Differentiation of salivary gland tumours using diffusion-weighted image-based virtual MR elastography: a pilot study

OBJECTIVES

Differentiation among benign salivary gland tumours, Warthin tumours (WTs), and malignant salivary gland tumours is crucial to treatment planning and predicting patient prognosis. However, differentiation of those tumours using imaging findings remains difficult. This study evaluated the usefulness of elasticity determined from diffusion-weighted image (DWI)-based virtual MR elastography (MRE) compared with conventional magnetic resonance imaging (MRI) findings in differentiating the tumours.

METHODS

This study included 17 benign salivary gland tumours, 6 WTs, and 11 malignant salivary gland tumours scanned on neck MRI. The long and short diameters, T1 and T2 signal intensities, tumour margins, apparent diffusion coefficient (ADC) values, and elasticity from DWI-based virtual MRE of the tumours were evaluated. The interobserver agreement in measuring tumour elasticity and the receiver operating characteristic (ROC) curves were also assessed.

RESULTS

The long and short diameters and the T1 and T2 signal intensities showed no significant difference among the 3 tumour groups. Tumour margins and the mean ADC values showed significant differences among some tumour groups. The elasticity from virtual MRE showed significant differences among all 3 tumour groups and the interobserver agreement was excellent. The area under the ROC curves of the elasticity were higher than those of tumour margins and mean ADC values.

CONCLUSION

Elasticity values based on DWI-based virtual MRE of benign salivary gland tumours, WTs, and malignant salivary gland tumours were significantly different. The elasticity of WTs was the highest and that of benign tumours was the lowest. The elasticity from DWI-based virtual MRE may aid in the differential diagnosis of salivary gland tumours.

Comparisons among the Ultrasonography Prediction Model, Real-Time and Shear Wave Elastography in the Evaluation of Major Salivary Gland Tumors

We aimed to validate the diagnostic accuracy of a novel sonographic scoring model and compare it with other methods in the evaluation of malignant major salivary gland tumors. We enrolled 138 patients who received neck ultrasound (US) with fine needle aspiration (FNA) and further operations or core needle biopsies for major salivary gland tumors from June 2015 to October 2021. The sonographic scoring model was presented as 2.08 × (vague boundary) + 1.75 × (regional lymphadenopathy) + 1.18 × (irregular or speculated shape) + 1.45 × (absence of posterior acoustic enhancement) + 2.4 × (calcification). We compared the diagnostic accuracy of the sonographic scoring model with shear wave elastography (SWE), real-time elastography (RTE), and US-FNA cytology for differentiating between benign and malignant lesions. The sensitivity, specificity, and accuracy were 58%, 89%, and 85% for the sonographic scoring model, 74%, 62%, and 64% for the SD of SWE with optimal cutoff value of 31.5 kPa, 69%, 70%, and 70% for the 4-point scoring system of RTE, and 74%, 93%, and 91% for US-FNA cytology, respectively. The sonographic scoring model is feasible as assistance in the evaluation of major salivary gland tumors. US-FNA cytology remains the tool of choice in diagnosing malignant salivary gland tumors.

Diagnostic performance of elastosonography in the differential diagnosis of benign and malignant salivary gland tumors: A meta-analysis

Purpose

The clinical practice of elastosonography for the detection of salivary gland tumors is still a controversial issue. The objective of this meta-analysis was to evaluate the effect of elastosonography for the diagnosis of salivary gland tumors and to compare the diagnostic value of elastosonography and conventional ultrasound in the diagnosis of salivary gland tumors.

Methods

A comprehensive literature search through PubMed, EMBASE, and Cochrane Library was carried out from inception to November 2021. Two researchers independently extracted the data from the enrolled papers using a standard data extraction form. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under the curve (AUC) were calculated to evaluate the diagnostic performance of elastosonography. The Quality Assessment of Diagnostic Accuracy Studies—2 (QUADAS-2) tool was utilized to evaluate the quality of each included study. Meta-DiSc version 1.4, Review Manager 5.3, and StataSE 15 were used.

Results

Sixteen studies with a total of 1105 patients with 1146 lesions were included in this meta-analysis. The pooled sensitivity, specificity, PLR, NLR, and DOR of elastosonography for the differentiation between benign and malignant salivary gland tumors were 0.73 (95%CI, 0.66–0.78), 0.64 (95%CI, 0.61–0.67), 2.83 (95%CI, 1.97–4.07), 0.45 (95%CI, 0.32–0.62), and 9.86 (95%CI, 4.49–21.62), respectively, with an AUC of 0.82. Four studies provided data regarding the conventional ultrasound for the differentiation between benign and malignant salivary gland tumors. The pooled sensitivity, specificity, and DOR were 0.62 (95%CI, 0.50–0.73), 0.93 (95%CI, 0.90–0.96), and 25.07 (95%CI, 4.28–146.65), respectively. The meta-regression and subgroup analyses found that assessment methods were associated with significant heterogeneity, and quantitative or semiquantitative elastosonography performed better than the qualitative one.

Conclusions

Elastosonography showed a limited value for diagnosing malignant salivary gland tumors; it could be considered as a supplementary diagnostic technology to conventional ultrasound, and quantitative or semiquantitative elastosonography was superior to the qualitative one.

Diffusion-weighted imaging with histogram analysis of the apparent diffusion coefficient maps in the diagnosis of parotid tumours

The aim of this study was to investigate the role of diffusion-weighted imaging (DWI) with histogram analysis of apparent diffusion coefficient (ADC) maps in the characterization of parotid tumours. This prospective study included 39 patients with parotid tumours. All patients underwent magnetic resonance imaging with DWI, and ADC maps were generated. The whole lesion was selected to obtain histogram-related parameters, including the mean (ADC_mean), minimum (ADC_min), maximum (ADC_max), skewness, and kurtosis of the ADC. The final diagnosis included pleomorphic adenoma (PA; n=18), Warthin tumour (WT; n=12), and salivary gland malignancy (SGM; n=9). ADC_mean (×10^-3mm²/s) was 1.93±0.34 for PA, 1.01±0.11 for WT, and 1.26±0.54 for SGM. There was a significant difference in whole lesion ADC_mean among the three study groups. Skewness had the best diagnostic performance in differentiating PA from WT (P=0.001; best detected cut-off 0.41, area under the curve (AUC) 0.990) and in discriminating WT from SGM (P=0.03; best detected cut-off 0.74, AUC 0.806). The whole lesion ADC_mean value had best diagnostic performance in differentiating PA from SGM (P=0.007; best detected cut-off 1.16×10^-3mm²/s, AUC 0.948). In conclusion, histogram analysis of ADC maps may offer added value in the differentiation of parotid tumours.

The current value of quantitative shear wave sonoelastography in parotid gland tumors

Background

The preoperative differentiation between salivary gland tumor entities using computed tomography, magnetic resonance imaging (MRI) and ultrasound (US) is still limited. Biopsies are often regarded as indispensable for properly characterizing these various lesions. The aim of this study was to analyze the value of acoustic radiation force impulse (ARFI) sonoelastography as an US differentiation tool when examining parotid gland (PG) lesions.

Methods

We included 104 patients with PG masses in this study, employing two different US devices using quantitative ARFI-sonoelastography (Siemens Acuson-S3000, n=59; Siemens Acuson-Sequoia, n=45). The ability of sonoelastographic measurements to differentiate between different neoplasms was compared and analyzed for both US machines.

Results

Quantitative shear wave sonoelastography is limited in its ability to reliably differentiate between tumor entities of the PG as a stand-alone parameter. Measurement results were unsystematically distributed and not transferable between the two US devices. A significant differentiation of benign and malignant lesions was not possible with either US machine (S3000: P=0.770, Sequoia: P=0.382). A differentiation between pleomorphic adenomas (PA) and Warthin tumors was only possible with the Acuson S3000 system (P=0.001, Spearman-Rho =0.492, sensitivity 73.9%, specificity 65.0%).

Conclusions

A reliable identification and differentiation of PG tumors as well as clinical treatment decisions cannot be made with the sole use of ARFI-sonoelastography. The results emphasize the device-dependence and high error-proneness of this US technique when examining lesions of the PG.

Clinical Utility of Qualitative Elastography Using Acoustic Radiation Force Impulse for Differentiating Benign from Malignant Salivary Gland Tumors

The goal of the work described here was to evaluate the utility of acoustic radiation force impulse (ARFI) imaging, a novel elastography technique, for differentiating benign from malignant salivary gland tumors. With the use of conventional strain elastography (SE) and ARFI imaging with a four-pattern scoring system, 185 tumors were examined (163 benign/22 malignant). When a score of ≥3 was used to define malignancy, the sensitivity, specificity and accuracy were higher for ARFI imaging (77.3%, 63.8% and 65.4%, respectively) than for conventional SE (54.5%, 56.4% and 56.2%, respectively). ARFI imaging findings revealed that most (92%) Warthin tumors, but only 24% of pleomorphic adenomas, were benign (score: 1 or 2). Attenuation of acoustic push pulses made it difficult to determine the stiffness of malignant tumors in the deep parotid lobes. Thus, ARFI imaging is a useful tool for screening Warthin tumors and exhibits high sensitivity for malignant tumors of salivary glands, other than deep parotid lobe tumors.

Narrative review of multiparametric ultrasound in parotid gland evaluation

Disorders affecting parotid gland represent a heterogeneous group comprising congenital, inflammatory and neoplastic diseases which show a focal or diffuse pattern of appearance. The differentiation of neoplastic from non-neoplastic conditions of parotid glands is pivotal for the diagnostic imaging. Frequently there is evidence of overlapping between the clinical and the imaging appearance of the various pathologies. The parotid gland is also often object of study with the combination of different techniques [ultrasound-computed tomography-magnetic resonance imaging (US-CT-MRI), ex.]. Compared to other dominant methods of medical imaging, US has several advantages providing images in real-time at lower cost, and without harmful use of ionizing radiation and of contrast enhancement. B-mode US, and the microvascular pattern color Doppler are usually used as first step evaluation of parotid lesions. Elastography and contrast-enhanced US (CEUS) has opened further possible perspectives to improve the differentiation between benign and malignant parotid lesions. The characterization of the parotid tumors plays a crucial role for their treatment planning and for the prediction of possible surgical complications. We present, here an updated review of the most recurrent pathologies of parotid gland focusing on the diagnostic power of multiparametric US including CEUS and ultrasound elastography (USE); limitations, advantages and the main key-points will be presented.

Sonoelastic response of median nerve to rehabilitation in carpal tunnel syndrome

Aim of the study

To evaluate the sonoelastic response of the median nerve in patients with carpal tunnel syndrome following conservative rehabilitation with splint plus exercise regimens.

Materials and methods

A total of thirty-five patients diagnosed with mild carpal tunnel syndrome and treated with splint plus exercise therapy; hand resting splint all day for 3 weeks and then only at nights along with nerve gliding exercises in 10 repetitions 3 times a day. The median nerve was evaluated clinically prior to the treatment and at week 6 of therapy using physical examination, electrodiagnostic neurophysiology tests and radiological imaging; Boston Scores, electromyogram, ultrasonography and sonoelastography.

Results

Following the 6-week treatment protocol on 35 subjects with mild carpal tunnel syndrome, sonoelastography showed significantly softer median nerve, while the traditional parameters based on Boston Scores and cross-sectional area based on ultrasonography remained nearly unresponsive. Such early indication of biomechanical changes in the nerve may be of clinical importance if it can offer a prognostic value of the applied treatment, while tissue softening suggests the alleviation of nerve compression.

Conclusions

Sonoelasticity of the median nerve can serve as a reliable marker for assessing therapeutic changes in median nerve stiffness and potentially the outcome early on in mild carpal tunnel syndrome.

Multiparametric ultrasound evaluation of parotid gland tumors: B-mode and color Doppler in comparison and in combination with contrast-enhanced ultrasound and elastography. A case report of a misleading diagnosis

Preoperative characterization of parotid gland tumors using imaging or cytological examination (fine-needle aspiration cytology) has a strong clinical and therapeutic impact, but it is often difficult due to the tumors' histological heterogeneity. The recent introduction of contrast-enhanced ultrasound (CEUS) and elastography, in the context of multiparametric ultrasound evaluation, contributed to improving the preoperative diagnosis of many diseases affecting the liver, breast, and thyroid, as well as other organs. However, limited evidence is available on the use and the diagnostic power of these techniques in parotid gland neoplasms. In this paper, we present a case of a parotid lesion that highlights the importance of a complete workup using multiparametric ultrasound evaluation, including CEUS and elastography, to identify malignant tumors of the parotid gland.