Prospective evaluation of Quasistatic Ultrasound Elastography (USE) compared with Baseline US for parotid gland lesions: preliminary results of elasticity contrast index (ECI) evaluation

Efficacy of ultrasound shear wave elastography in the diagnosis of salivary gland tumors

PURPOSE

Diagnostic accuracy of fine-needle aspiration cytology (FNAC) as the ability to discriminate between the target condition and health in the evaluation of salivary gland tumors is not perfected yet and false-negative results are possible. The purpose of the present study was to measure and compare the diagnostic accuracy of FNAC performed with conventional B-mode ultrasound and ultrasound with shear wave elastography (SWE) FNAC navigation.

METHODS

The investigators implemented a single-blind randomized study (sealed envelope method). The study population was composed of all patients presenting for evaluation and management of suspected benign or malignant tumors of the major salivary glands between July 2013 and December 2020. The involvement of SWE navigation was the primary predictor variable affecting FNA targeting. The method involved analysis of redistribution of SWE values within the affected gland expressed in kilopascals (kPa) and the four-point ES1 (soft tissue) to ES4 (stiff) scoring. The primary outcome variable was the success in obtaining diagnostic tissue resulting in a histologically confirmed FNAC diagnosis and coded as yes/no. Age and sex of the patients and topographical locations of lesions were covariates. Descriptive and bivariate statistics were computed and the P value was set at .05.

RESULTS

The sample included 132 subjects (male/female 59/73; mean age 54 ± 11 years; 144 tumors). SWE + Group (n = 66) consisted of patients presurgically diagnosed with salivary tumors SWE-guided FNAC and SWE- Group (n = 66) was diagnosed with tumors by conventional ultrasound-(B-mode)-guided FNAC. The SWE-guided FNAC statistically significantly reduced the incidence of false-negative results (n = 0; P = .001) and nondiagnostic cases (n = 3 SWE FNAC vs n = 7 B-mode US FNAC; P = .04). For SWE + Group, the FNAC diagnosis was confirmed by postsurgical histology in 95.5% with 91.0% sensitivity (confidence interval [CI] 0.62 to 0.97) and 84.4% specificity (CI 0.58 to 0.96). For SWE- Group, 81.8% confirmation was obtained (P = .05) with 82.3% sensitivity (CI 0.54 to 0.90) and 74.0% specificity.

CONCLUSION

SWE can increase success in obtaining diagnostic tissue when used for FNAC navigation purposes. We suggest combining both SWE and standard B-mode US methods when the FNAC procedure is performed.

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.

Rupture of the Pleomorphic Adenoma of the Parotid Gland: What to Know before, during and after Surgery

Background: We assessed the cases of intraoperative spillage of primary pleomorphic adenomas (PPAs) of the parotid gland in the literature, comparing them with our own cases. We aim to explain how the surgeon should manage a spillage during surgery (i.e., how to avoid spreading the contents that are coming out of the tumor). We also aim to investigate whether or not spillage is linked to a higher rate of PPA recurrence. Methods: We collected surgical and pathological reports, taking data on capsular ruptures and the spillage of tumors. Results: Intraoperative tumor spillage and tumor rupture occurred in 34/202 cases. There were three recurrences after a mean of 3.7 years (mean follow-up duration: 10.3 years). One recurrence happened to a patient who had an intraoperative tumor spillage, and two more recurrences happened to patients who did not have spillage. Conclusion: We believe that the real number of the events of spillage is underestimated and underreported by surgeons. Capsular rupture must always be avoided, and secure resection margins must always be pursued, independent of the type of parotidectomy being performed. Features that increase the risk of recurrence are an intraoperative rupture and the presence of satellite nodules (as recorded in the pathologist’s report). In these cases, patients need a longer follow-up period.

MRI-Based radiomics nomogram for differentiation of benign and malignant lesions of the parotid gland

OBJECTIVES

Preoperative differentiation between benign parotid gland tumors (BPGT) and malignant parotid gland tumors (MPGT) is important for treatment decisions. The purpose of this study was to develop and validate an MRI-based radiomics nomogram for the preoperative differentiation of BPGT from MPGT.

METHODS

A total of 115 patients (80 in training set and 35 in external validation set) with BPGT (n = 60) or MPGT (n = 55) were enrolled. Radiomics features were extracted from T1-weighted and fat-saturated T2-weighted images. A radiomics signature model and a radiomics score (Rad-score) were constructed and calculated. A clinical-factors model was built based on demographics and MRI findings. A radiomics nomogram model combining the Rad-score and independent clinical factors was constructed using multivariate logistic regression analysis. The diagnostic performance of the three models was evaluated and validated using ROC curves on the training and validation datasets.

RESULTS

Seventeen features from MR images were used to build the radiomics signature. The radiomics nomogram incorporating the clinical factors and radiomics signature had an AUC value of 0.952 in the training set and 0.938 in the validation set. Decision curve analysis showed that the nomogram outperformed the clinical-factors model in terms of clinical usefulness.

CONCLUSIONS

The above-described radiomics nomogram performed well for differentiating BPGT from MPGT, and may help in the clinical decision-making process.

KEY POINTS

• Differential diagnosis between BPGT and MPGT is rather difficult by conventional imaging modalities. • A radiomics nomogram integrated with the radiomics signature, clinical data, and MRI features facilitates differentiation of BPGT from MPGT with improved diagnostic efficacy.

A CT-based radiomics nomogram for differentiation of lympho-associated benign and malignant lesions of the parotid gland

OBJECTIVES

Preoperative differentiation between benign lymphoepithelial lesion (BLEL) and mucosa-associated lymphoid tissue lymphoma (MALToma) in the parotid gland is important for treatment decisions. The purpose of this study was to develop and validate a CT-based radiomics nomogram combining radiomics signature and clinical factors for the preoperative differentiation of BLEL from MALToma in the parotid gland.

METHODS

A total of 101 patients with BLEL (n = 46) or MALToma (n = 55) were divided into a training set (n = 70) and validation set (n = 31). Radiomics features were extracted from non-contrast CT images, a radiomics signature was constructed, and a radiomics score (Rad-score) was calculated. Demographics and CT findings were assessed to build a clinical factor model. A radiomics nomogram combining the Rad-score and independent clinical factors was constructed using multivariate logistic regression analysis. The performance levels of the nomogram, radiomics signature, and clinical model were evaluated and validated on the training and validation datasets, and then compared among the three models.

RESULTS

Seven features were used to build the radiomics signature. The radiomics nomogram incorporating the clinical factors and radiomics signature showed favorable predictive value for differentiating parotid BLEL from MALToma, with AUCs of 0.983 and 0.950 for the training set and validation set, respectively. Decision curve analysis showed that the nomogram outperformed the clinical factor model in terms of clinical usefulness.

CONCLUSIONS

The CT-based radiomics nomogram incorporating the Rad-score and clinical factors showed favorable predictive efficacy for differentiating BLEL from MALToma in the parotid gland, and may help in the clinical decision-making process.

KEY POINTS

• Differential diagnosis between BLEL and MALToma in parotid gland is rather difficult by conventional imaging modalities. • A radiomics nomogram integrated with the radiomics signature, demographics, and CT findings facilitates differentiation of BLEL from MALToma with improved diagnostic efficacy.

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.

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.

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

OBJECTIVES

The aim of the study was to scrutinize the value of qualitative elastography in the diagnosis of salivary gland masses.

METHODS

Sixty patients were enrolled in this prospective study. Patients aged between 1 and 91 years (mean age, 48.8 ± 20.48) with a salivary gland mass were studied with real-time elastography. All patients were examined by 1 examiner, blinded to all relevant data. On elastography, masses were scored into 4 types according to their stiffness compared to normal tissue. Scores of 3 and 4 were accepted as signs of malignancy. Sensitivity, specificity, and positive and negative predictive value were calculated for elastography in verifying malignancy.

RESULTS

Forty-two percent of the masses were located in the parotid, and the rest in submandibular gland. The diameter of the lesions varied between 12 and 60 mm (mean, 24.36 ± 11.98 mm). Forty-four masses were benign (73%), and among them the majority were inflammatory lesions (31 of 60; 51.7%). There were 16 malignant lesions (27%). On elastography, not only all malignant lesions but 15 benign lesions were scored as 3 to 4. All masses scored as 1 to 2 were benign. Sensitivity was 100%; specificity, 66%; positive predictive value, 52%; and negative predictive value, 100%. When only Score 4 lesions were accepted as malignant, these values became 75%, 77%, 55%, and 90%, respectively.

CONCLUSIONS

Elastography alone cannot be used to discriminate malignant from benign in the evaluation of salivary gland lesions. However, with its high negative predictive value, it may be used as an adjunct tool to increase the diagnostic value of ultrasonography.

Sonoelastography for differential diagnosis between malignant and benign parotid lesions: a meta-analysis

Objectives

To assess the performance of sonoelastography for differential diagnosis between malignant and benign parotid lesions using a meta-analysis.

Methods

An independent literature search of English medical databases, such as PubMed, Embase and Medline (Embase.com), Web of Science, Cochrane Library and Ovid was performed. The diagnostic accuracy of sonoelastography was compared with that of histopathology and/or cytology, which was used as reference standard. The pooled sensitivity, specificity, diagnostic odds ratio (DOR) and area under the curve (AUC) were calculated to evaluate the accuracy of sonoelastography. A meta-regression analysis evaluating imaging mechanisms, shear wave elastography techniques, assessment methods and QUADAS scores was performed.

Results

Ten eligible studies that included a total sample of 711 patients with 725 parotid lesions were included. Sonoelastography showed a pooled sensitivity of 0.67 (95% CI 0.59–0.74), specificity of 0.64 (95% CI 0.60–0.68), DOR of 8.00 (95% CI 2.96–21.63) and an AUC of 0.77. The results of the meta-regression analysis revealed that no heterogeneity was due to the imaging mechanism (p = 0.119), shear wave elastography technique (p = 0.473) or QUADAS score (p = 0.462). However, the assessment method was a significant factor that affected the study heterogeneity (p = 0.035). According to the subgroup analysis, quantitative and semiquantitative methods performed better than qualitative ones.

Conclusion

Overall, sonoelastography has a limited value for differential diagnosis between malignant and benign parotid lesions. Quantitative and semiquantitative methods perform better than qualitative ones.

Key Points

• Overall, sonoelastography has a limited value for differential diagnosis between malignant and benign parotid lesions.

• Quantitative and semiquantitative assessment methods perform better than qualitative ones.

• Semiquantitative and quantitative methods are automatically calculated by an ultrasound machine and are thus less operator-dependent.

Quality assurance of ultrasound systems: current status and review of literature

Diagnostic ultrasound (US) images can be obtained from a quality device, in optimal working conditions, combined with the capable actions of the operator in tweaking the equipment's characteristics. The quality assurance (QA) is the topic of this review article, and it is addressed in an US practice through proper selection of the equipment when purchasing, and through care and preventive maintenance of the machine for ensuring accurate performance. For optimal US system functioning, QA steps carried out on the basis of a scheduled program are needed in any US practice or department. It is critical to confirm in a semiannual or annual basis that the image quality is maintained according to standards and any subtle change in equipment's functioning is detected and amended at an early stage. The use of test objects (also called US testing phantoms) is required above the basic level of QA testing. The scope of this review article is to inform the US user about necessary QA knowledge and at the same time, present the state of the art of the most suitable test methods for US QA. We referred to relevant publications, selected after performing a systematic literature search of the MEDLINE, EMBASE and COCHRANE databases, and also to the standards established by authoritative international societies.