An ultrasound-based ensemble machine learning model for the preoperative classification of pleomorphic adenoma and Warthin tumor in the parotid gland.

OBJECTIVES: The preoperative classification of pleomorphic adenomas (PMA) and Warthin tumors (WT) in the parotid gland plays an essential role in determining therapeutic strategies. This study aims to develop and validate an ultrasound-based ensemble machine learning (USEML) model, employing nonradiative and noninvasive features to differentiate PMA from WT. METHODS: A total of 203 patients with histologically confirmed PMA or WT who underwent parotidectomy from two centers were enrolled. Clinical factors, ultrasound (US) features, and radiomic features were extracted to develop three types of machine learning model: clinical models, US models, and USEML models. The diagnostic performance of the USEML model, as well as that of physicians based on experience, was evaluated and validated using receiver operating characteristic (ROC) curves in internal and external validation cohorts. DeLong's test was used for comparisons of AUCs. SHAP values were also utilized to explain the classification model. RESULTS: The USEML model achieved the highest AUC of 0.891 (95% CI, 0.774-0.961), surpassing the AUCs of both the US (0.847; 95% CI, 0.720-0.932) and clinical (0.814; 95% CI, 0.682-0.908) models. The USEML model also outperformed physicians in both internal and external validation datasets (both p < 0.05). The sensitivity, specificity, negative predictive value, and positive predictive value of the USEML model and physician experience were 89.3%/75.0%, 87.5%/54.2%, 87.5%/65.6%, and 89.3%/65.0%, respectively. CONCLUSIONS: The USEML model, incorporating clinical factors, ultrasound factors, and radiomic features, demonstrated efficient performance in distinguishing PMA from WT in the parotid gland. CLINICAL RELEVANCE STATEMENT: This study developed a machine learning model for preoperative diagnosis of pleomorphic adenoma and Warthin tumor in the parotid gland based on clinical, ultrasound, and radiomic features. Furthermore, it outperformed physicians in an external validation dataset, indicating its potential for clinical application. KEY POINTS: • Differentiating pleomorphic adenoma (PMA) and Warthin tumor (WT) affects management decisions and is currently done by invasive biopsy. • Integration of US-radiomic, clinical, and ultrasound findings in a machine learning model results in improved diagnostic accuracy. • The ultrasound-based ensemble machine learning (USEML) model consistently outperforms physicians, suggesting its potential applicability in clinical settings.

Ultrasound-guided percutaneous thermal ablation of parotid tumors: experience from two-centers.

Objective: To evaluate the efficacy and feasibility of ultrasound-guided percutaneous thermal ablation (TA) for treating benign parotid tumors.Methods: Patients with benign parotid tumors who underwent ultrasound-guided microwave ablation (MWA) or radiofrequency ablation (RFA) between January 2020 and March 2023 were included in this retrospective study. Change in tumor size (maximum diameter, tumor volume(V), volume reduction rate (VRR)) and cosmetic score (CS) were evaluated during a one-year follow-up period. We also recorded the incidence of any complications associated with TA.Results: A total of 23 patients (13 males and 10 females; median age 65 years, range 5-91 years) were included. The mean VRR at 1, 3, 6, and 12 months after TA was 37.03%±10.23%, 56.52%±8.76%, 82.28%±7.89%, and 89.39%±6.45%, respectively. Mean CS also changed from 3.39 ± 0.66 to 1.75 ± 0.93 (p < 0.001) by the end of follow-up time. Subgroup analysis showed that tumors with smaller initial maximum diameter had a faster CS reduction rate than those with larger initial diameter. The incidence of facial nerve dysfunction was 8.70%.Conclusion: Ultrasound-guided percutaneous TA is an effective and safe treatment option for patients with benign parotid tumors.

Growth rates over time of unoperated parotid benign tumors.

INTRODUCTION: The treatment of parotid benign tumor is in principle surgery, but observation may be necessary in some cases. The purpose of this study was to investigate the growth rates over time of unoperated parotid benign tumors. METHODS: We retrospectively reviewed the medical records of 63 patients with unoperated parotid benign tumors diagnosed at our institution between January 2010 and December 2022. RESULTS: Forty-nine of the 63 patients had a Warthin tumor and 13 patients had a pleomorphic adenoma. On average, the unoperated parotid benign tumors grew 0.02 cm in length and 0.4 cm3 in volume per year. Compared to pleomorphic adenomas, Warthin tumors were more predominant in male patients and in those with a smoking history and a longer duration of smoking history; patients with Warthin tumors were also followed up longer (p < 0.05). However, the length and volume growth rates of unoperated Warthin tumors and pleomorphic adenomas did not significantly differ. CONCLUSION: Surgery is the standard treatment for parotid benign tumors. However, small benign parotid tumors identified during preoperative examination can be observed through close follow-up, taking into account the patient's medical and general condition.

Navigating the void: outcomes and adaptations during parotid surgery in the absence of posterior belly of digastric muscle.

It is well known that the digastric posterior belly is one of the essential landmarks for facial nerve identification during parotid surgery. While there were multiple reports about variations of the digastric anterior belly, only a few anatomical variations of the posterior belly of the digastric muscle have been described.In this article, we describe an anatomical variation of the posterior belly of digastric muscle found during superficial parotidectomy of a patient with pleomorphic adenoma. This anatomical variation also led to an anatomical variation in the position of the facial nerve.To our knowledge, this is the first report of an absent posterior belly of digastric muscle found during live parotid surgery. The knowledge of current anatomical variation may help to avoid facial nerve injury during parotid surgery and preserve the function of muscles of facial expression.

Incidentally found parotid gland lesion in 18F-FDG PET/CT for staging evaluation of patients with hepatocellular carcinoma: remote possibility of metastatic tumor or second primary salivary gland malignancy.

OBJECTIVES: We primarily aimed to evaluate whether parotid incidental lesion (PIL) in 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for staging evaluation of patients with hepatocellular carcinoma (HCC) would represent a possibility of extrahepatic metastasis or second primary malignancy (SPM). Additionally, we explored the incidence of PIL in HCC patients and examined any associated risk factors. METHODS: We retrospectively analyzed patients with HCC who underwent 18F-FDG PET/CT at our institution from 2010 to 2022. The pathological findings of PILs in HCC patients were investigated for confirmatory identification of the risk of HCC metastasis or SPM in parotid gland. Healthy controls received 18F-FDG PET/CT for health screening were also enrolled to compare the incidence of PILs with HCC patients. Various parameters associated with patient demographics and characteristics of HCC were analyzed to find the related factors of PILs. RESULTS: A total of 17,674 patients with HCC and 2,090 healthy individuals who had undergone 18F-FDG PET/CT scans were enrolled in the analyses. Among the 54 HCC patients who underwent pathological confirmation for PILs, benign primary parotid tumor was most commonly observed (n = 43 [79.6%]); however, no malignant lesions were detected, including HCC metastasis. The incidence of PILs was higher in patients diagnosed with HCC compared with the control group (485 [2.7%] vs. 23 [1.1%], p = 0.002). Analysis for the risk factors for PILs revealed that patient age, sex, and positive viral markers were significantly associated with the incidence of PILs in patients with HCC (all p < 0.001). CONCLUSIONS: Our study demonstrates that PILs are more frequently identified in patients with HCC on 18F-FDG PET/CT. However, no malignant PIL, including extrahepatic metastasis of HCC, was identified. Therefore, the presence of PIL should not impede or delay the treatment process for patients with HCC. Additionally, we suggested that for future swift and straightforward differential diagnoses of PIL, the development of additional protocols within the PET/CT imaging could be beneficial.

The protective role of postoperative radiation therapy in low and intermediate grade major salivary gland malignancies: A study of the Canadian Head and Neck Collaborative Research Initiative.

BACKGROUND: The objective of this study was to examine the utility of postoperative radiation for low and intermediate grade cancers of the parotid and submandibular glands. METHODS: The authors conducted a retrospective, Canadian-led, international, multi-institutional analysis of a patient cohort with low or intermediate grade salivary gland cancer of the parotid or submandibular gland who were treated from 2010 until 2020 with or without postoperative radiation therapy. A multivariable, marginal Cox proportional hazards regression analysis was performed to quantify the association between locoregional recurrence (LRR) and receipt of postoperative radiation therapy while accounting for patient-level factors and the clustering of patients by institution. RESULTS: In total, 621 patients across 14 tertiary care centers were included in the study; of these, 309 patients (49.8%) received postoperative radiation therapy. Tumor histologies included 182 (29.3%) acinic cell carcinomas, 312 (50.2%) mucoepidermoid carcinomas, and 137 (20.5%) other low or intermediate grade primary salivary gland carcinomas. Kaplan-Meier LRR-free survival at 10 years was 89.0% (95% confidence interval [CI], 84.9%-93.3%). In multivariable Cox regression analysis, postoperative radiation therapy was independently associated with a lower hazard of LRR (adjusted hazard ratio, 0.53; 95% CI, 0.29-0.97). The multivariable model estimated that the marginal probability of LRR within 10 years was 15.4% without radiation and 8.8% with radiation. The number needed to treat was 16 patients (95% CI, 14-18 patients). Radiation therapy had no benefit in patients who had early stage, low-grade salivary gland cancer without evidence of nodal disease and negative margins. CONCLUSIONS: Postoperative radiation therapy may reduce LLR in some low and intermediate grade salivary gland cancers with adverse features, but it had no benefit in patients who had early stage, low-grade salivary gland cancer with negative margins.

Value of T2-weighted-based radiomics model in distinguishing Warthin tumor from pleomorphic adenoma of the parotid.

OBJECTIVES: The differentiation of Warthin tumor and pleomorphic adenoma before treatment is crucial for clinical strategies. The aim of this study was to develop and test a T2-weighted-based radiomics model for differentiating pleomorphic adenoma from Warthin tumor of the parotid gland. METHODS: A total of 117 patients, including 61 cases of Warthin tumor and 56 cases of pleomorphic adenoma, were retrospectively enrolled from two centers between January 2010 and June 2022. The training set included 82 cases, and the validation set included 35 cases. From T2-weighted images, 971 radiomics features were extracted. Seven radiomics features remained after a two-step selection process. We used the seven radiomics features and clinical factors through multivariable logistic regression to build radiomics and clinical models, respectively. A radiomics-clinical model was also built that combined the independent clinical predictors with the radiomics features. Through ROC curves, the three models were evaluated and compared. RESULTS: In the radiomics model, AUCs were 0.826 and 0.796 in training and validation sets, respectively. In the clinical model, the AUCs were 0.923 and 0.926 in the training and validation sets, respectively. Decision curve analysis revealed that the radiomics-clinical model had the best diagnostic performance for distinguishing Warthin tumor from pleomorphic adenoma of the parotid gland (AUC = 0.962 and 0.934 for the training and validation sets, respectively). CONCLUSION: The radiomics-clinical model performed well in differentiating pleomorphic adenoma from Warthin tumor of the parotid gland. KEY POINTS: • The clinical model outperformed the radiomics model in distinguishing pleomorphic adenoma from Warthin tumor of the parotid gland. • The radiomics features extracted from T2-weighted images could help differentiate pleomorphic adenoma from Warthin tumor of the parotid gland. • The radiomics-clinical model was superior to the radiomics and the clinical models for differentiating pleomorphic adenoma from Warthin tumor of the parotid gland.

Deep learning-assisted diagnosis of benign and malignant parotid tumors based on contrast-enhanced CT: a multicenter study.

OBJECTIVES: To develop deep learning-assisted diagnosis models based on CT images to facilitate radiologists in differentiating benign and malignant parotid tumors. METHODS: Data from 573 patients with histopathologically confirmed parotid tumors from center 1 (training set: n = 269; internal-testing set: n = 116) and center 2 (external-testing set: n = 188) were retrospectively collected. Six deep learning models (MobileNet V3, ShuffleNet V2, Inception V3, DenseNet 121, ResNet 50, and VGG 19) based on arterial-phase CT images, and a baseline support vector machine (SVM) model integrating clinical-radiological features with handcrafted radiomics signatures were constructed. The performance of senior and junior radiologists with and without optimal model assistance was compared. The net reclassification index (NRI) and integrated discrimination improvement (IDI) were calculated to evaluate the clinical benefit of using the optimal model. RESULTS: MobileNet V3 had the best predictive performance, with sensitivity increases of 0.111 and 0.207 (p < 0.05) in the internal- and external-testing sets, respectively, relative to the SVM model. Clinical benefit and overall efficiency of junior radiologist were significantly improved with model assistance; for the internal- and external-testing sets, respectively, the AUCs improved by 0.128 and 0.102 (p < 0.05), the sensitivity improved by 0.194 and 0.120 (p < 0.05), the NRIs were 0.257 and 0.205 (p < 0.001), and the IDIs were 0.316 and 0.252 (p < 0.001). CONCLUSIONS: The developed deep learning models can assist radiologists in achieving higher diagnostic performance and hopefully provide more valuable information for clinical decision-making in patients with parotid tumors. KEY POINTS: • The developed deep learning models outperformed the traditional SVM model in predicting benign and malignant parotid tumors. • Junior radiologist can obtain greater clinical benefits with assistance from the optimal deep learning model. • The clinical decision-making process can be accelerated in patients with parotid tumors using the established deep learning model.

Assessment of the observation management of sialocele after partial superficial parotidectomy.

PURPOSE: This study aimed to investigate the usefulness of management of sialocele formation and to evaluate the quality of life of patients under elective management post-parotidectomy. MATERIALS AND METHODS: A prospective study was performed including patients who underwent postoperative management with either compression therapy or observation. The self-filled questionnaire method was used to assess the quality of life of participants who changed from compression therapy to observation. Demographic and operative data, variables regarding wound complications and scores for quality of life were documented and analysed. RESULTS: A total of 86 patients met the eligibility criteria. The respective rates of sialocele formation within 1 month were 5.3% in the compression therapy group (2/38) and 16.0% in the observation group (4/25), but no significant difference was observed (p = 0.204). Meanwhile, both groups displayed comparable times of needle aspiration and time for sialocele resolution (p > 0.05). Based on 23 valid paired questionnaires, scores for physical and social-emotional function before changing from compression therapy to observation were significantly lower than scores after the change (p < 0.001). CONCLUSION: The application of observation after partial superficial parotidectomy appears to have acceptable clinical outcomes and considerable improvements in quality of life.

Comparative analysis of benign and malignant parotid gland tumors: A retrospective study of 992 patients.

OBJECTIVE: We analyzed and compared the clinical characteristics of benign and malignant parotid gland tumors. PATIENTS AND METHODS: A total of 992 patients who underwent surgical treatment for parotid gland tumors from January 2010 to December 2020 were included in this study. This study population was subdivided into benign (n = 812, 81.9 %) and malignant parotid gland tumors (n = 180, 18.1 %). RESULTS: Pleomorphic adenoma is the most common benign tumor and mucoepidermoid carcinoma is the most common malignant tumor. The patients with malignant parotid gland tumors were older than the patients with benign lesions. The duration of symptoms was longer in patients with benign parotid gland tumors compared to those with malignant lesions. The size of the malignant tumors was larger than that of the benign lesions. Preoperative fine-needle aspiration cytology had a diagnostic sensitivity of 50.3 %, diagnostic specificity of 98.7 %, a positive predictive value of 89.5 %, a negative predictive value of 89.9 %, and accuracy of 89.9 % for diagnosing malignant parotid gland tumors. For benign parotid gland tumors, superficial parotidectomy was most frequently performed, and for malignant parotid gland tumors, total parotidectomy was most frequently performed. Facial palsy was observed in 19.4 % of the patients with malignant parotid gland tumors compared to 5.4 % of those with benign tumors. CONCLUSION: The clinical features of benign and malignant parotid gland tumors showed differences in age, symptoms, duration of symptoms, size and site of the parotid tumors, surgical procedures, and postoperative facial nerve palsy.

[Indications for fine-needle aspiration and core needle biopsy for diagnosis of salivary gland tumors]. / Indikation der Feinnadelpunktion und Grobnadelbiospie zur Diagnostik von Speicheldrüsentumoren.

BACKGROUND: Salivary gland malignancies are rare neoplasms of the head and neck area. Preoperative clinical and imaging assessment of salivary gland masses is challenging. However, preoperative identification of malignancy is crucial for further treatment and for the course of the disease. OBJECTIVE: This article presents the advantages and disadvantages of fine-needle aspiration cytology (FNAC) and core needle biopsy (CNB). Additionally, the sensitivity and specificity of both methods for predicting malignancy were analyzed. Furthermore, it is discussed which procedure is suitable for the diagnostic work-up of salivary gland tumors. MATERIALS AND METHODS: This current article summarizes important and recent studies in the field of the diagnostic work-up for salivary gland lesions, with discussion of original articles, metanalyses, and systematic reviews concerning FNAC and CNB. RESULTS: The sensitivity and specificity of the predictive ability of FNAC for malignancy is described at between 70.0-80.0% and 87.5-97.9%. The pooled sensitivity and specificity for CNB were 92.0-98.0% and 95.0-100.0%, respectively. Tumor cell seeding or facial nerve palsy are very rare complications of both procedures. CONCLUSION: If malignancy is suspected based on clinical examination or imaging, FNAC or CNB should be performed. FNAC is easy to perform; however, an onsite cytologist is necessary. CNB has a higher sensitivity for routine diagnosis of malignancy; tumor typing and grading is facilitated by preserving the histological architecture. In conclusion, CNB is the procedure of choice in the diagnostic work-up for suspected malignant salivary gland tumors.

[Surgery for parotid gland cancer-controversial and proven aspects]. / Chirurgie der primären Karzinome der Gl. parotidea ­ Kontroverses und Bewährtes.

BACKGROUND: Due to the rarity of primary parotid malignancies, there are currently only limited clinical study data on the optimal surgical therapy. Parotid malignancies encompass a broad spectrum of more than 20 different histological subtypes with varying biology, which thus represents a challenge for even experienced pathologists and head and neck surgeons with proven expertise in salivary gland surgery. OBJECTIVE: The aim of this review article is to provide an overview of the current literature on surgical therapy of the primary tumor and the cN0 neck as well as treatment of the facial nerve, and to shed light on the various controversial aspects of this topic. RESULTS: In salivary gland oncology there is a trend towards safe (R0) but more conservative surgery. Currently, less-invasive surgical approaches could potentially be applied in a small subgroup with carefully selected caudally located and R0-resected "low-grade tumors" in stages T1-T2 and cN0 in relatively young patients with high compliance and more in the context of structured clinical studies. Elective neck dissection in the case of cN0 status should be carried out if risk factors for occult cervical lymph node metastasis (T3-T4a, "high-grade subtypes," advanced age, lymphangitic carcinomatosis) are present. In cases of small "low-grade parotid carcinomas," narrow resection margins or even microscopic tumor residues on the facial nerve can potentially be adequately compensated with adjuvant radiation therapy. However, due to the lack of solid data, the significance of the actual effect of the radiation in this situation should be viewed with great caution.

[Preservation, reconstruction, and rehabilitation of the facial nerve]. / Erhalt, Rekonstruktion und Rehabilitation des N. facialis.

Handling of the facial nerve during surgery for parotid cancer is relevant for the patient's long-term quality of life. In about two thirds of cases, the facial nerve is not affected by the tumor. In these cases, in addition to complete tumor resection, identification and preservation of the facial nerve are important components of a successful operation. If the nerve is infiltrated by the tumor, the affected part must be resected during radical parotidectomy. When possible, primary nerve reconstruction leads to the best long-term cosmetic and functional outcomes. Individual selection of the optimal treatment concept is based on clinical examination of facial muscle mobility, preoperative imaging to understand the positional relationship between tumor and nerve, and on the basis of an electrophysiological examination of nerve function. Intraoperatively, standardized dissection helps to identify and preserve the facial nerve. If radical parotidectomy is indicated, in addition to one-step reconstruction, preoperative diagnostic tests can help to plan postoperative adjuvant therapy. The aim of rehabilitation is restoration of facial tone, facial symmetry, and movement of the paralyzed face. Restoration of eye closure is of high importance. The surgical treatment of facial paralysis has seen many improvements in recent years. The present work provides an overview of the most recent advances in diagnostics, surgical techniques, and further possibilities for preventing damage to the normal facial nerve during parotid cancer treatment. Furthermore, the options for rehabilitation of the tumor-infiltrated facial nerve in the context of treatment of salivary gland malignancies are described.

CT-based radiomics analysis of different machine learning models for differentiating benign and malignant parotid tumors.

OBJECTIVES: This study aimed to explore and validate the value of different radiomics models for differentiating benign and malignant parotid tumors preoperatively. METHODS: This study enrolled 388 patients with pathologically confirmed parotid tumors (training cohort: n = 272; test cohort: n = 116). Radiomics features were extracted from CT images of the non-enhanced, arterial, and venous phases. After dimensionality reduction and selection, radiomics models were constructed by logistic regression (LR), support vector machine (SVM), and random forest (RF). The best radiomic model was selected by using ROC curve analysis. Univariate and multivariable logistic regression was applied to analyze clinical-radiological characteristics and identify variables for developing a clinical model. A combined model was constructed by incorporating radiomics and clinical features. Model performances were assessed by ROC curve analysis, and decision curve analysis (DCA) was used to estimate the models' clinical values. RESULTS: In total, 2874 radiomic features were extracted from CT images. Ten radiomics features were deemed valuable by dimensionality reduction and selection. Among radiomics models, the SVM model showed greater predictive efficiency and robustness, with AUCs of 0.844 in the training cohort; and 0.840 in the test cohort. Ultimate clinical features constructed a clinical model. The discriminatory capability of the combined model was the best (AUC, training cohort: 0.904; test cohort: 0.854). Combined model DCA revealed optimal clinical efficacy. CONCLUSIONS: The combined model incorporating radiomics and clinical features exhibited excellent ability to distinguish benign and malignant parotid tumors, which may provide a noninvasive and efficient method for clinical decision making. KEY POINTS: The current study is the first to compare the value of different radiomics models (LR, SVM, and RF) for preoperative differentiation of benign and malignant parotid tumors. A CT-based combined model, integrating clinical-radiological and radiomics features, is conducive to distinguishing benign and malignant parotid tumors, thereby improving diagnostic performance and aiding treatment.

Influence of post-label delay time on the performance of 3D pseudo-continuous arterial spin labeling magnetic resonance imaging in the characterization of parotid gland tumors.

OBJECTIVE: To evaluate the influence of post-label delay times (PLDs) on the performance of 3D pseudo-continuous arterial spin labeling (pCASL) magnetic resonance imaging for characterizing parotid gland tumors and to explore the optimal PLDs for the differential diagnosis. MATERIALS AND METHOD: Fifty-eight consecutive patients with parotid gland tumors were enrolled, including 33 patients with pleomorphic adenomas (PAs), 16 patients with Warthin's tumors (WTs), and 9 patients with malignant tumors (MTs). 3D pCASL was scanned for each patient five times, with PLDs of 1025 ms, 1525 ms, 2025 ms, 2525 ms, and 3025 ms. Tumor blood flow (TBF) was calculated, and compared among different PLDs and tumor groups. Performance of TBF at different PLDs was evaluated using receiver operating characteristic analysis. RESULTS: With an increasing PLD, TBF tended to gradually increase in PAs (p < 0.001), while TBF tended to slightly increase and then gradually decrease in WTs (p = 0.001), and PAs showed significantly lower TBF than WTs at all 5 PLDs (p < 0.05). PAs showed significantly lower TBF than MTs at 4 PLDs (p < 0.05), except at 3025 ms (p = 0.062). WTs showed higher TBF than MTs at all 5 PLDs; however, differences did not reach significance (p > 0.05). Setting a TBF of 64.350 mL/100g/min at a PLD of 1525 ms, or a TBF of 23.700 mL/100g/min at a PLD of 1025 ms as the cutoff values, optimal performance could be obtained for differentiating PAs from WTs (AUC = 0.905) or from MTs (AUC = 0.872). CONCLUSIONS: Short PLDs (1025 ms or 1525 ms) are suggested to be used in 3D pCASL for characterizing parotid gland tumors in clinical practice. KEY POINTS: • With 5 different PLDs, 3D pCASL can reflect the variation of blood flow in parotid gland tumors. • 3D pCASL is useful for characterizing PAs from WTs or MTs. • Short PLDs (1025 ms or 1525 ms) are suggested to be used in 3D pCASL for characterizing parotid gland tumors in clinical practice.

Diffusion kurtosis imaging and dynamic contrast-enhanced MRI for the differentiation of parotid gland tumors.

OBJECTIVE: To assess the usefulness of combined diffusion kurtosis imaging (DKI) and dynamic contrast-enhanced MRI (DCE-MRI) in the differentiation of parotid gland tumors. METHODS: Seventy patients with 80 parotid gland tumors who underwent DKI and DCE-MRI were retrospectively enrolled and divided into four groups: pleomorphic adenomas (PAs), Warthin tumors (WTs), other benign tumors (OBTs), and malignant tumors (MTs). DCE-MRI and DKI quantitative parameters were measured. The Kruskal-Wallis H test and post hoc test with Bonferroni correction and ROC curve were used for statistical analysis. RESULTS: WTs demonstrated the highest Kep value (median 1.89, interquartile range [1.46-2.31] min-1) but lowest Ve value (0.20, [0.15-0.25]) compared with PAs (Kep, 0.34 [0.21-0.55] min-1; Ve, 0.36 [0.24-0.43]), OBTs (Kep, 1.22 [0.27-1.67] min-1; Ve, 0.28 [0.25-0.41]), and MTs (Kep, 0.71 [0.50-1.23] min-1; Ve, 0.35 [0.26-0.45]) (all p < .05). MTs had the lower D value (1.10, [0.88-1.29] × 10-3 mm2/s) compared with PAs (1.81, [1.60-2.20] × 10-3 mm2/s) and OBTs (1.57, [1.32-1.89] × 10-3 mm2/s) (both p < .05). PAs had the lower Ktrans value (0.12, [0.07-0.18] min-1) compared with OBTs (0.28, [0.11-0.50] min-1) (p < .05). The cutoff values of combined Kep and Ve, D, and Ktrans to distinguish WTs, MTs, and PAs sequentially were 1.06 min-1, 0.28, 1.46 × 10-3 mm2/s, and 0.21 min-1, respectively (accuracy, 89% [71/80], 91% [73/80], 78% [62/80], respectively). CONCLUSION: The combined use of DKI and DCE-MRI may help differentiate parotid gland tumors. KEY POINTS: • The combined use of DKI and DCE-MRI could facilitate the understanding of the pathophysiological characteristics of parotid gland tumors. • A stepwise diagnostic diagram based on the combined use of DCE-MRI parameters and the diffusion coefficient is helpful for accurate preoperative diagnosis in parotid gland tumors and may further facilitate the clinical management of patients.

Carcinoma ex pleomorphic adenoma of the parotid gland.

INTRODUCTION: Carcinoma ex pleomorphic adenoma (CXPA) is a rare malignant tumor of the parotid gland. We analyzed the clinical characteristics and treatment outcomes of CXPA of the parotid gland in patients managed for 11 years at this hospital. METHODS: The study included 17 cases of CXPA of the parotid gland from January 2010 to December 2020. RESULTS: Over 11 years, CXPA was the fourth most common parotid carcinoma, accounting for 9.4% of the 180 cases finally diagnosed as parotid carcinoma. Of the 17 cases of CXPA of the parotid gland, 12 lesions were removed by superficial parotidectomy, four lesions by total parotidectomy, and one lesion by radical parotidectomy. Four patients underwent neck dissection. The most common histopathology type was salivary duct carcinoma (n = 13, 76.5%). Postoperative radiation therapy (RT) was performed in 15 patients. Two patients (11.8%) experienced CXPA recurrence 14 and 19 months after surgery. CONCLUSION: CXPA of the parotid gland was treated without recurrence in about 90% of the patients through surgery and postoperative RT. In the case of frankly invasive or adverse factors in the histopathological examination, more attention is required because CXPA recurrence may occur more frequently.

[Perfusion analysis in parotid gland tumors using contrast-enhanced ultrasound (CEUS)]. / Perfusionsanalyse von Parotistumoren mittels kontrastverstärkter Sonographie (CEUS).

OBJECTIVE: The diagnosis of parotid gland tumors is challenging due to their rarity and heterogenity. Neither conventional ultrasound nor magnetic resonance imaging (MRI) nor computed tomography (CT) allow a reliable pretherapeutic diagnosis. In addition to conventional ultrasound, contrast-enhanced ultrasound (CEUS) enables a more detailed assessment of perfusion in parotid gland tumors, thereby improving evaluation of this tumor entity. Extensive studies with analysis of perfusion characteristics in different regions of interest (ROI) in parotid gland tumors are currently lacking. This study analysed and compared perfusion parameters in different intratumoral areas of malignant and benign parotid gland tumors using CEUS. MATERIALS AND METHODS: A total of 100 patients with tumors in the parotid gland were examined using B­mode sonography, colour Doppler sonography and CEUS. The parameters magnitude, echogenicity, demarcation, vascularisation and in particular perfusion characteristics were measured and analysed. Analysis of quantitative CEUS parameters was performed using a specific method for perfusion analysis with certain ROI, which were allocated in a standardized manner in the entire parotid gland tumors. The perfusion parameters were compared between intratumoral ROI in the tumors and between particular tumor entities. Qualitative CEUS analysis with an estimation of perfusion patterns was additionally performed. RESULTS: Histologically benign tumors were found in 92 cases, and malignant tumors in eight cases. CEUS analysis of perfusion patterns revealed a centripetal perfusion pattern in malignant tumors significantly more frequently than in benign tumors. In the perfusion analysis of quantitative CEUS parameters, all tumors showed higher perfusion intensities in the peripheral ROI. In benign tumors, more differences in perfusion intensity between the intratumoral ROIs were detected compared to malignant tumors. CONCLUSION: The perfusion parameters (centripetal perfusion pattern; area under the curve) evaluated in this study have the potential to improve pretherapeutic diagnostics of parotid gland tumors in terms of differentiation of tumor entity. Further studies with larger patient cohorts are required for subsequent investigation and validation of the diagnostic accuracy of particular parameters to detect perfusion patterns potentially specific to particular tumor entities.

[Clinicopathologic analysis of micro and mini parotid gland tumors].

OBJECTIVE: To investigate the clinicopathological characteristics of micro and mini parotid gland tumors and to provide reference for their clinical diagnosis and treatment. METHODS: Patients with parotid gland tumors treated in the Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology from December 2012 to April 2020 were selected. Relevant clinical data of the patients with tumor diameter ≤20 mm detected by preoperative CT were collected to analyze the clinicopathological characteristics and prognosis of micro and mini parotid gland tumors. And the collected data were divided into two groups with diameter 11-20 mm and diameter ≤10 mm according to tumor diameter measured by preoperative CT. The clinicopathological differences between the two groups were statistically analyzed. RESULTS: A total of 2 067 patients with primary epithelial parotid gland tumors were collected, and 685 patients with tumor diameter ≤20 mm were examined by CT, accounting for 33.1%. The ratio of male to female patients with micro and mini parotid gland tumors was 1 ∶1.93, the average age was (45.3±13.8) years (12-83 years), and the median course of disease was 12 months (1 week to 30 years). Among them, 635 cases (92.7%) were benign tumors, 50 cases (7.3%) were malignant tumors, and the ratio of benign to malignant was 12.7 ∶1. The most common benign tumor was pleomorphic adenoma, and the most common malignant tumor was mucoepidermoid carcinoma. The micro and mini parotid gland tumors were divided into 11-20 mm group (n=611) and ≤10 mm group (n=74), the clinical characteristics comparison of the two groups of gender ratio, average age, course of di-sease had no statistical difference (P>0.05). In the 11-20 mm diameter group, the percentage of benign and malignant tumor was 92.8% (567/611) and 7.2% (44/611) respectively, and the ratio of benign to malignant tumors was 12.9 ∶1. In the ≤10 mm diameter group, the percentage of benign and malignant tumor was 91.9% (68/74) and 8.1% (6/74) respectively, and the ratio of benign to malignant tumors was 11.3 ∶1. There was no significant difference between the two groups (P>0.05). Fifty patients with malignant tumor were followed up for the median follow-up period of 39.5 months (1-91 months). Local recurrence occurred in 2 patients with one death. The overall 2-year survival rate was 93.7% and the 5-year survival rate was 89.3%. CONCLUSION: The majority of micro and mini parotid gland tumors was benign lesion. There was a good prognosis for micro and mini parotid gland carcinoma. Early surgical treatment was recommended for micro and mini parotid gland tumors.

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.