Comparative Study of Qualitative and Quantitative Analyses of Contrast-Enhanced Ultrasound and the Diagnostic Value of B-Mode and Color Doppler for Common Benign Tumors in the Parotid Gland

Deep learning-assisted diagnosis of benign and malignant parotid tumors based on ultrasound: a retrospective study

BACKGROUND

To develop a deep learning(DL) model utilizing ultrasound images, and evaluate its efficacy in distinguishing between benign and malignant parotid tumors (PTs), as well as its practicality in assisting clinicians with accurate diagnosis.

METHODS

A total of 2211 ultrasound images of 980 pathologically confirmed PTs (Training set: n = 721; Validation set: n = 82; Internal-test set: n = 89; External-test set: n = 88) from 907 patients were retrospectively included in this study. The optimal model was selected and the diagnostic performance evaluation is conducted by utilizing the area under curve (AUC) of the receiver-operating characteristic(ROC) based on five different DL networks constructed at varying depths. Furthermore, a comparison of different seniority radiologists was made in the presence of the optimal auxiliary diagnosis model. Additionally, the diagnostic confusion matrix of the optimal model was calculated, and an analysis and summary of misjudged cases' characteristics were conducted.

RESULTS

The Resnet18 demonstrated superior diagnostic performance, with an AUC value of 0.947, accuracy of 88.5%, sensitivity of 78.2%, and specificity of 92.7% in internal-test set, and with an AUC value of 0.925, accuracy of 89.8%, sensitivity of 83.3%, and specificity of 90.6% in external-test set. The PTs were subjectively assessed twice by six radiologists, both with and without the assisted of the model. With the assisted of the model, both junior and senior radiologists demonstrated enhanced diagnostic performance. In the internal-test set, there was an increase in AUC values by 0.062 and 0.082 for junior radiologists respectively, while senior radiologists experienced an improvement of 0.066 and 0.106 in their respective AUC values.

CONCLUSIONS

The DL model based on ultrasound images demonstrates exceptional capability in distinguishing between benign and malignant PTs, thereby assisting radiologists of varying expertise levels to achieve heightened diagnostic performance, and serve as a noninvasive imaging adjunct diagnostic method for clinical purposes.

Contrast-Enhanced Ultrasound and Strain Elastography for Differentiating Benign and Malignant Parotid Tumors

OBJECTIVES

Preoperative differentiation between benign parotid tumors (BPT) and malignant parotid tumors (MPT) is crucial for treatment decisions. The purpose of this study was to investigate the benefits of combining contrast-enhanced ultrasound (CEUS) and strain elastography (SE) for preoperative differentiation between BPT and MPT.

METHODS

A total of 115 patients with BPT (n=72) or MPT (n=43) who underwent ultrasound (US), SE, and CEUS were enrolled. US and CEUS features and the elasticity score were evaluated. Receiver operating characteristic curve (ROC) analysis was used to assess the diagnostic performance of SE, CEUS, and SE + CEUS with respect to identifying MPT from BPT.

RESULTS

Solitary presentation, larger diameter, irregular shape, ill-defined margin, heterogeneous echogenicity, and calcification on US and higher elasticity score on SE had a significant association with malignancy. MPT also presented an unclear margin, larger size after enhancement, and "fast-in and fast-out" pattern on CEUS. The combination of SE and CEUS was effective for differentiating MPT from BPT (AUC: 0.88, 0.80-0.95), with a sensitivity of 86.0%, specificity of 88.9%, and accuracy of 87.8%, which were significantly higher than the values for SE (AUC: 0.75, 0.66-0.85) and CEUS (AUC: 0.82, 0.73-0.91) alone.

CONCLUSION

The combination of CEUS and SE is valuable for distinguishing MPT from BPT.

Assessment of Parotid Gland Tumors by Means of Quantitative Multiparametric Ultrasound (mpUS)

OBJECTIVE

The preoperative diagnostical differentiation of parotid gland tumor (PGT) is not always simple due to several different entities. B-mode-ultrasound (US) remains the imaging modality of choice, while histopathology serves as the gold standard for finalizing the diagnosis. We aimed to evaluate the use of multiparametric US (mpUS) in the assessment of PGT.

METHODS

We included 97 PGTs from 96 patients. A standardized mpUS protocol using B-mode-US, shear-wave elastography (SWE), and standardized contrast-enhanced ultrasound (CEUS) was performed prior to surgical intervention. SWE was assessed by real-time measurement conducting a minimum of five measurements, while quantitative CEUS parameters were assessed with a post-processing perfusion software.

RESULTS

SWE allowed differentiation between benign PGT (Warthin's Tumor (WT) paired with lymph nodes (LN) and pleomorphic adenoma (PA)), and WT and LN were softer compared to PA. WT showed lower velocities than squamous cell carcinoma (SCC): the most common malignant PGT. CEUS parameters showed significant group differences between WT and PA, WT and malignant lesions, WT and SCC, WT paired with LN versus PA, and WT paired with LN versus SCC.

CONCLUSION

MpUS seems to be beneficial in the assessment of PGT characterization, with benign PGT appearing to be softer in SWE than tumors with malignant tendencies. The quantitative CEUS parameter shows higher perfusion in WT than in PA, and malignant PGTs are less vascularized than WTs.

Contrast-Enhanced Ultrasound in the Differentiation between the Most Common Benign Parotid Gland Tumors: A Systematic Review and Meta-Analysis

Recently, contrast-enhanced ultrasound (CEUS) has become a promising tool in distinguishing benign from malignant parotid gland tumors. However, its usefulness in differentiating various benign parotid tumors has not been determined so far. This study aimed to systematically review the literature to determine the utility of CEUS in the preoperative differentiation between pleomorphic adenomas (PAs) and Warthin's tumors (WTs) of the parotid gland. PubMed, Embase, and Cochrane were searched for English-language articles published until 21 July 2022. Fifteen studies were included. On CEUS examination, a significantly greater percentage of PAs displayed heterogeneous enhancement texture compared to WTs. Contrarily, the enhanced lesion size, the enhancement margin, and the presence of the enhancement rim did not differ significantly between the entities. Significantly longer normalized mean transit time (nMTT) and time to peak (TTP) were observed in PAs. Contrarily, the mean values of area under the curve (AUC) and time from peak to one half (TPH) were significantly higher for WTs. Due to the considerable overlap among the qualitative CEUS characteristics of PAs and WTs, the reproducible, investigator-independent quantitative CEUS measurements have a greater potential to distinguish PAs from WTs, which might influence the selection of an appropriate management strategy.

Clinical Diagnostic Application of Contrast-Enhanced Ultrasound in Focal Lesions of the Salivary Glands

OBJECTIVES

To evaluate the clinical diagnostic value of contrast-enhanced ultrasound (CEUS) for focal benign and malignant lesions of the salivary glands, as well as for common benign lesions.

METHODS

A total of 91 patients with focal lesions of the salivary glands were included in this study. In this study, CEUS was used to study the differential diagnosis of focal benign and malignant lesions of the salivary gland and the most common benign tumors, that is, pleomorphic adenoma (PA) and adenolymphoma.

RESULTS

The differences between focal benign and malignant lesions in the salivary glands were statistically significant (P < .05) in terms of qualitative CEUS indicators, enhancement pattern, enhancement homogeneity, enhancement margin, and enhanced lesion size, whereas the differences were not statistically significant (P > .05) in terms of wash-in and wash-out pattern, enhancement degree. Blurred margins and increased size of the lesion after enhancement are two CEUS features independently associated with focal malignant lesions of the salivary gland. The differences between salivary gland PA and adenolymphoma were statistically significant (P < .05) in terms of wash-in pattern, enhancement degree, enhancement homogeneity, and enhancement pattern, but not in terms of wash-out pattern, enhancement margin, and enhanced lesion size (P > .05).

CONCLUSIONS

As an economical, convenient, and safe imaging method, CEUS has important clinical value in distinguishing benign and malignant salivary glands.