Tumors of the parotid gland: MR imaging characteristics of various histologic types

Imaging Features of Lymphoepithelial-Like Carcinoma of the Salivary Glands

OBJECTIVE

Lymphoepithelial-like carcinoma of the salivary glands (LELCSG) is a rare tumour of unknown aetiology. No studies have reported the imaging features of primary LELCSG.

METHODS

The clinical information and imaging features of eight patients with LELCSG were reviewed. Computed tomography (n = 4 patients) and magnetic resonance imaging (n = 4 patients) features were analysed by two radiologists to identify the location, number, size, shape, boundary, signal intensity and enhancement of LELCSG.

RESULTS

The study included four women and four men, and the mean size of the tumours was 32.88 ± 3.41 mm (range, 27-38 mm). The tumours affected the parotid gland in six cases and the submandibular gland in two cases. The eight cases were evaluated by radiologists. All tumours were lobulated; three had clear edges and five had blurred edges. There was no necrosis in six tumours, while two tumours exhibited slight necrosis without bleeding. All eight tumours showed multiple nodular changes and extensive fusion. Four tumours with magnetic resonance imaging (MRI) were isointense or slightly hyperintense on T1-weighted imaging (T1WI) and obvious homogeneous enhancement on contrasted enhanced T1WI scan, while slightly hyperintense on T2-weighted imaging (T2WI). The other four lesions were isodense on computed tomography (CT) scan. The degree of enhancement varied among the eight tumours. The necrotic zones of the eight tumours did not exhibit any enhancement.

CONCLUSIONS

LELCSG is a lobulated, multi-nodular tumour, with some fused nodules. LELCSG lesions showed isointensity or slight hyperintensity on T1WI MRI, slight hyperintensity on T2WI MRI and isodense on CT scan. Larger tumours may exhibit some necrosis, but the necrotic cysts were relatively rare. Uniform enhancement was observed in non-necrotic areas on enhanced CT and MRI scan. The multi-nodular feature may be valuable for diagnosis.

Histogram analysis of dynamic contrast-enhanced magnetic resonance imaging in the differential diagnosis of parotid tumors

Objective

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) histograms were used to investigate whether their parameters can distinguish between benign and malignant parotid gland tumors and further differentiate tumor subgroups.

Materials and methods

A total of 117 patients (32 malignant and 85 benign) who had undergone DCE-MRI for pretreatment evaluation were retrospectively included. Histogram parameters including mean, median, entropy, skewness, kurtosis and 10th, 90th percentiles were calculated from time to peak (TTP) (s), wash in rate (WIR) (l/s), wash out rate (WOR) (l/s), and maximum relative enhancement (MRE) (%) mono-exponential models. The Mann–Whitney U test was used to compare the differences between the benign and malignant groups. The diagnostic value of each significant parameter was determined on Receiver operating characteristic (ROC) analysis. Multivariate stepwise logistic regression analysis was used to identify the independent predictors of the different tumor groups.

Results

For both the benign and malignant groups and the comparisons among the subgroups, the parameters of TTP and MRE showed better performance among the various parameters. WOR can be used as an indicator to distinguish Warthin’s tumors from other tumors. Warthin’s tumors showed significantly lower values on 10th MRE and significantly higher values on skewness TTP and 10th WOR, and the combination of 10th MRE, skewness TTP and 10th WOR showed optimal diagnostic performance (AUC, 0.971) and provided 93.12% sensitivity and 96.70% specificity. After Warthin’s tumors were removed from among the benign tumors, malignant parotid tumors showed significantly lower values on the 10th TTP (AUC, 0.847; sensitivity 90.62%; specificity 69.09%; P < 0.05) and higher values on skewness MRE (AUC, 0.777; sensitivity 71.87%; specificity 76.36%; P < 0.05).

Conclusion

DCE-MRI histogram parameters, especially TTP and MRE parameters, show promise as effective indicators for identifying and classifying parotid tumors. Entropy TTP and kurtosis MRE were found to be independent differentiating variables for malignant parotid gland tumors. The 10th WOR can be used as an indicator to distinguish Warthin’s tumors from other tumors.

Prevalence and Clinical Implications of Incidentally Detected Parotid Lesions as Blind Spot on Brain MRI: A Single-Center Experience

Background and objective: This study was conducted to assess the prevalence and clinical implications of parotid lesions detected incidentally during brain magnetic resonance imaging (MRI) examination. Materials and Methods: Between February 2016 and February 2021, we identified 86 lesions in the brain MRI reports of 84 patients that contained the words “parotid gland” or “PG”. Of these, we finally included 49 lesions involving 45 patients following histopathological confirmation. Results: Based on the laboratory, radiological or histopathological findings, the prevalence of incidental parotid lesions was low (1.2%). Among the 45 study patients, 41 (91.1%) had unilateral lesions, and the majority of the lesions were located in the superficial lobe (40/49, 81.6%). The mean size of the parotid lesions was 1.3 cm ± 0.4 cm (range, 0.5 cm–2.8 cm). Of these, 46 parotid lesions (93.9%) were benign, whereas the remaining three lesions were malignant (6.1%). Conclusions: Despite the low prevalence and incidence of malignancy associated with incidental parotid lesions detected on brain MRI, the clinical implications are potentially significant. Therefore, clinical awareness and appropriate imaging work-up of these lesions are important for accurate diagnosis and timely management.

Value of dynamic contrast enhanced MRI in differential diagnostics of Warthin tumors and parotid malignancies

To define an algorithm for differential diagnostics of parotid malignancies and Warthin tumors (WTs) based on dynamic contrast enhanced MRI (DCE-MRI). 55 patients with parotid tumors treated surgically were analyzed. Of which, 19 had parotid malignancy and 36 had WTs confirmed with postoperative histopathological examination. Accuracy of DCE-MRI parameters (T_peak and WR) was compared with the histopathological diagnosis. ROC analysis was performed to determine sensitivity and specificity of DCE-MRI with various T_peak and WR cut-off values. WT showed significantly lower median T_peak and higher median WR than malignant lesions. The cut-off values for T_peak and WR providing maximum sensitivity (84.2%) and specificity (86.1%) for malignant tumors were T_peak > 60 s and WR ≤ 30%. Different diagnostic algorithm, i.e., lower cut-off value for T_peak (T_peak = 60 s), increases sensitivity of DCE-MRI in differentiating parotid malignancies from WTs. However, WR > 30% seems to be a key diagnostic criterion for benign lesions. Precise and reliable preoperative diagnostics of parotid tumors aids in careful surgical planning, thereby assisting in achieving sufficient surgical resection margins and facial nerve preservation.

TransMed: Transformers Advance Multi-Modal Medical Image Classification

Over the past decade, convolutional neural networks (CNN) have shown very competitive performance in medical image analysis tasks, such as disease classification, tumor segmentation, and lesion detection. CNN has great advantages in extracting local features of images. However, due to the locality of convolution operation, it cannot deal with long-range relationships well. Recently, transformers have been applied to computer vision and achieved remarkable success in large-scale datasets. Compared with natural images, multi-modal medical images have explicit and important long-range dependencies, and effective multi-modal fusion strategies can greatly improve the performance of deep models. This prompts us to study transformer-based structures and apply them to multi-modal medical images. Existing transformer-based network architectures require large-scale datasets to achieve better performance. However, medical imaging datasets are relatively small, which makes it difficult to apply pure transformers to medical image analysis. Therefore, we propose TransMed for multi-modal medical image classification. TransMed combines the advantages of CNN and transformer to efficiently extract low-level features of images and establish long-range dependencies between modalities. We evaluated our model on two datasets, parotid gland tumors classification and knee injury classification. Combining our contributions, we achieve an improvement of 10.1% and 1.9% in average accuracy, respectively, outperforming other state-of-the-art CNN-based models. The results of the proposed method are promising and have tremendous potential to be applied to a large number of medical image analysis tasks. To our best knowledge, this is the first work to apply transformers to multi-modal medical image classification.

TransMed: Transformers Advance Multi-Modal Medical Image Classification

Over the past decade, convolutional neural networks (CNN) have shown very competitive performance in medical image analysis tasks, such as disease classification, tumor segmentation, and lesion detection. CNN has great advantages in extracting local features of images. However, due to the locality of convolution operation, it cannot deal with long-range relationships well. Recently, transformers have been applied to computer vision and achieved remarkable success in large-scale datasets. Compared with natural images, multi-modal medical images have explicit and important long-range dependencies, and effective multi-modal fusion strategies can greatly improve the performance of deep models. This prompts us to study transformer-based structures and apply them to multi-modal medical images. Existing transformer-based network architectures require large-scale datasets to achieve better performance. However, medical imaging datasets are relatively small, which makes it difficult to apply pure transformers to medical image analysis. Therefore, we propose TransMed for multi-modal medical image classification. TransMed combines the advantages of CNN and transformer to efficiently extract low-level features of images and establish long-range dependencies between modalities. We evaluated our model on two datasets, parotid gland tumors classification and knee injury classification. Combining our contributions, we achieve an improvement of 10.1% and 1.9% in average accuracy, respectively, outperforming other state-of-the-art CNN-based models. The results of the proposed method are promising and have tremendous potential to be applied to a large number of medical image analysis tasks. To our best knowledge, this is the first work to apply transformers to multi-modal medical image classification.

Clinicopathological features of incidental parotid lesions

Background

The purpose of this study is to determine the histopathological spectrum and risk of primary malignancy of asymptomatic parotid lesions incidentally discovered on cross-sectional imaging.

Methods

Over a 10-year period, 154 patients underwent 163 ultrasound-guided parotid lesion biopsies at our institution. This retrospective chart review included 89 lesions in 87 patients with asymptomatic parotid lesions discovered on cross-sectional imaging studies performed for unrelated clinical indications. The histopathologic findings of all sampled lesions were reviewed. We evaluated the patient demographics and pathological diagnoses of sampled parotid lesions to determine the histopathological spectrum and risk of malignancy.

Results

The average age was 67.5 years and 92 % were males. 25 % of patients had bilateral lesions. The average size of the parotid lesions was 1.5 cm and 91 % were located in the superficial lobe. 92.1 % of lesions were benign with Warthin tumor being the most common diagnosis followed by pleomorphic adenoma. 2.3 % of lesions were primary parotid malignant neoplasms, while 5.6 % were metastatic lesions in patients with known malignancy.

Conclusions

The incidence of primary parotid malignant neoplasm in asymptomatic incidentally discovered parotid lesions is low. Imaging or clinical follow-up may be considered in patients with incidental parotid lesions who prefer to avoid biopsy.

Magnetic resonance image biomarkers improve differentiation of benign and malignant parotid tumors through diagnostic model analysis

OBJECTIVES

To explore the effectiveness of magnetic resonance image (MRI)-based biomarkers for identifying benign and malignant parotid tumors via diagnostic model analysis.

METHODS

This retrospective study included 109 patients (development cohort and validation cohort) who underwent MRI preoperatively, including T1- and T2-weighted images. Parameters based on 2D or 3D texture analysis were extracted from tumor lesions by MaZda software, fisher discriminant and bootstrap method were used to perform parameter reduction, diagnostic models with the selected biomarkers were established along with clinical data, model performance (discrimination and calibration) was furtherly evaluated by internal and external validation, decision curve analysis was applied to measure the improvement of clinical benefits.

RESULTS

S(5,5) Entrop, S(0,1) ASM, WavEnHH (s-4), S(1,1,0) Entropy and Perc.10% were significantly associated with the pathological diagnosis of parotid tumor (benign versus malignancy), when adding these biomarkers to the regression analysis, model performance significantly improved in the development cohort (likelihood-ratio-test; p < 0.05, with an increase of AUC from 0.72 (reference model) to 0.85), and these results were maintained in a small external validation cohort. Decision curve analysis indicated that clinical benefit was greater with the application of MRI-based biomarkers.

CONCLUSIONS

MRI-based texture analysis is proven to be an effective tool in differentiating benign and malignant parotid tumors, preoperative diagnosis was improved with the selected biomarkers compared to the reference model.

Platysma Infiltration on CT or MRI in Parotid Pathology

목적

CT나 MRI에서 이하선의 양성종양, 악성종양 및 염증 질환에서 나타나는 활경근 침윤의 빈도와 어떤 상황에서 잘 일어나는지 그 조건을 알아보고자 하였다.

대상과 방법

이하선에서 발생한 양성종양 314명, 악성종양 52명 그리고 염증 22명을 대상으로 하였다. CT나 MRI에서 활경근 침윤의 빈도 및 병변의 위치, 피막침범 유무, 국소성에 따른 활경근 침윤 유무를 후향적으로 알아보았다.

결과

활경근 침윤의 빈도는 양성종양에서 0%, 악성종양에서 19.2% (10/52), 염증 환자에서 50% (11/22)였다. 피막을 침범한 염증 환자 13명 중 10명에서 활경근 침윤을 보였다. 활경근 침윤을 보인 염증 환자 11명 중 10명이 미만성을, 1명은 국소성을 보였다. 활경근 침윤을 보인 악성종양 총 10명 모두에서 피막을 침범하였으며, 그중 미만성 병변이 7명, 국소성이 3명이었다.

결론

이하선 질환에서 활경근 침윤은 악성종양보다 염증 질환에서 더 흔하게 일어났다. 염증 질환에서의 활경근 침윤은 이하선 피막을 침범하거나 미만성 병변일 경우 더 잘 나타났다.

Ultra-small superparamagnetic iron oxide (USPIO) magnetic resonance imaging in benign mixed tumor of the parotid gland

Historically USPIO has been used to help with nodal staging but not in primary tumors. The ability to concentrate USPIO may help to differentiate BMT from other types of parotid tumors.

Multiparametric magnetic resonance imaging of parotid tumors: A systematic review

PURPOSE

The purpose of this systematic review was to provide an overview of the contribution of multiparametric magnetic resonance imaging (MRI) in the diagnosis of parotid tumors (PT) and recommendations based on current evidences.

MATERIAL AND METHODS

We performed a retrospective systematic search of PubMed, EMBASE, and Cochrane Library databases from inception to January 2020, using the keywords "magnetic resonance imaging" and "salivary gland neoplasms".

RESULTS

The initial search returned 2345 references and 90 were deemed relevant for this study. A total of 54 studies (60%) reported the use of diffusion-weighted imaging (DWI) and 28 studies (31%) the use of dynamic contrast-enhanced (DCE) imaging. Specific morphologic signs of frequent benign PT and suggestive signs of malignancy on conventional sequences were reported in 37 studies (41%). DWI showed significant differences in apparent diffusion coefficient (ADC) values between benign and malignant PT, and especially between pleomorphic adenomas and malignant PT, with cut-off ADC values between 1.267×10^-3mm²/s and 1.60×10^-3mm²/s. Perfusion curves obtained with DCE imaging allowed differentiating among pleomorphic adenomas, Warthin's tumors, malignant PT and cystic lesions. The combination of morphological MRI sequences, DCE imaging and DWI helped increase the diagnostic accuracy of MRI.

CONCLUSION

Multiparametric MRI, including morphological MRI sequences, DWI and DCE imaging, is the imaging modality of choice for the characterization of focal PT and provides features that are highly suggestive of a specific diagnosis.

Clinical and demographic data improve diagnostic accuracy of dynamic contrast-enhanced and diffusion-weighted MRI in differential diagnostics of parotid gland tumors

PURPOSE

To verify if differential diagnostic algorithms based on selected parameters of dynamic and diffusion-weighted MRI, clinical and demographic variables are accurate enough to differentiate between parotid malignancies, pleomorphic adenomas and Warthin tumors.

MATERIALS AND METHODS

The study included 84 patients, among them 19 (23%) with postoperative diagnosis of a parotid malignancy, 37 (44%) with Warthin tumors and 28 (33%) with pleomorphic adenomas. Accuracy of dynamic and diffusion-weighted MRI parameters (T_peak, T_max, WR and ADC), clinical parameters of the tumor (location in the superficial or deep parotid lobe, single vs. multiple lesion, concomitant lymphadenopathy) and demographic characteristics of the patient (age, sex) was determined on ROC analysis.

RESULTS

Compared to Warthin tumors, parotid malignancies showed higher T_peak, T_max and ADC, lower WR, were more often located in the deep lobe of the parotid and presented as single lesions with concomitant lymphadenopathy. Consideration of all these variables provided 100% sensitivity and 89.2% specificity of the differential diagnostic algorithm. Compared to pleomorphic adenomas, parotid malignancies presented with lower ADC and T_peak, higher T_max, were more often located in the deep lobe of the parotid, associated with concomitant lymphadenopathy, diagnosed in men and individuals older than 66 years. Consideration of all these variables provided 100% sensitivity and 96.4% specificity of the differential diagnostic algorithm.

CONCLUSION

Combined analysis of clinical data and results of dynamic and diffusion-weighted MRI may provide nearly ideal accuracy in differential diagnostics of parotid malignancies and the two most common histological types of benign tumors.

Multiparametric Magnetic Resonance Imaging for the Diagnosis and Differential Diagnosis of Parotid Gland Tumors

The majority of salivary gland tumors occur in the parotid glands. Characterization (ie, benign or malignant, and histological type), location (deep or superficial), and invasion into the neighboring tissues of parotid tumors determine preoperative treatment planning. MRI gives more information than other imaging methods about the internal structure, localization, and relationship with other tissues of parotid tumors. Functional MRI methods (diffusion-weighted imaging, dynamic contrast-enhanced MRI, perfusion-weighted MRI, MR spectroscopy, etc.) have been increasingly used recently to increase the power of radiologists to characterize the tumors. Although they increase the workload of radiologists, the combined use of functional MRI methods improves accuracy in the differentiation of the tumors. There are a wide range of studies in the literature dealing with the combined use of different functional imaging methods in combination with conventional sequences. The aim of the present review is to evaluate conventional and functional/advanced MR methods, as well as multiparametric MRI applications combining them in the diagnosis of parotid gland tumors. Evidence Level: 5 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020;52:11-32.

Multifocal Warthin's Tumor: An Uncommon Presentation of Bilateral Cervical Lymphadenopathy

Warthin's tumor is the second most common benign lesion of the parotid gland. It is most commonly encountered in male smokers in the fifth to seventh decades of life. Uniquely, among benign lesions of the parotid gland, it can be seen bilaterally in 7–10% of cases. Very rarely, Warthin's tumor can also mimic malignant or metastatic disease by presenting within cervical lymph nodes. We present a rare case of a 71-year old male smoker with bilateral parotid lesions in addition to progressively enlarging cervical and mediastinal lymphadenopathy. Excisional biopsy of a cervical lymph node ultimately revealed Warthin's tumor.

Diagnostic accuracy of magnetic resonance imaging techniques for parotid tumors, a systematic review and meta-analysis

OBJECTIVE

To assess the added benefit of combining different MRI techniques for preoperative diagnosis of parotid tumors when compared to conventional MRI and advanced MRI techniques alone with meta-analysis.

METHODS

A comprehensive PubMed electronic database search was performed for original diagnostic studies up to July 2017. The methodologic quality of each study was evaluated by two independent reviewers who used the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Statistical analysis included pooling of sensitivity and specificity with 95% confidence intervals (CI). All analyses were conducted using STATA (version 12.0), RevMan (version 5.2), and Meta-Disc 1.4 software programs.

RESULTS

Pooled sensitivity and specificity of conventional MRI, diffusion weighted imaging (DWI), dynamic contrast enhanced (DCE) and the above combination were 76% (95%CI)/91% (95%CI)/80% (95%CI)/86% (95%CI) and 83% (95%CI)/56% (95%CI)/90% (95%CI)/90% (95%CI).

CONCLUSION

Conventional MRI combined with DWI and DCE showed higher diagnostic accuracy than conventional or advanced MRI alone, supporting their use in parotid tumors diagnosis.

Cross-sectional Imaging of Parotid Gland Nodules: A Brief Practical Guide

Clinical evaluation and ultrasound examination are the first steps in the evaluation of a patient with a swelling of the parotid region. After the detection of a nodular lesion, cytological or histological confirmation is usually performed to achieve the diagnosis, while the choice of cross-sectional imaging (computed tomography scan and magnetic resonance imaging) may significantly vary from one physician to another, on the basis of the degree of confidence that both radiologist and surgeon have with this kind of imaging. This work focuses on some essential “reporting points” in cross-sectional imaging evaluation of parotid nodules, chiefly helpful to the radiologist when the ultrasonography assessment is considered incomplete and requires a further evaluation.

Assessment of salivary gland tumors using MRI and CT: impact of experience on diagnostic accuracy

RATIONALE AND OBJECTIVES

To analyze the accuracy of radiological diagnosis in MRI and CT studies of salivary gland tumors depending on the radiologist's experience.

MATERIALS AND METHODS

Three radiologists with differing experience (R1 > 20, R2 > 11, and R3 > 7 years, respectively) retrospectively reviewed 128 cases (116 MRI, 12 CT studies) with suspected salivary gland tumors regarding dignity and classification using histopathology as a reference standard. Sensitivity, specificity, positive/negative predictive value and inter-observer agreement (using Cohen's κ) were calculated to compare diagnostic performance.

RESULTS

Lesions were benign in 87 and in 23 cases malignant. Neoplasia was absent in 18 cases (15 cases without neoplasia and 3 cases without disease). The highest inter-observer agreement for determining dignity using CT was found between R1 and R2 (κ = 0.74, p < 0.001), and the lowest between R2 and R3 (κ = 0.28, p < 0.001). MRI sensitivity/specificity for classifying pleomorphic adenomas was as follows: R1 (100%/100%), R2 (76.92%/87.01%), R3 (43.53%/67.53%), and for CT: R1 (100%/100%), R2 (100%/88.89%), R3 (66.67%/88.89%; for Warthin's tumor using MRI: R1 (100%/97.44%), R2 (68.42%/83.33%), R3 (50.00%/67.95%), and using CT: R1 (100%/100%), R2 (50.00%/100%), R3 (100%/100%; for squamous cell carcinomas using MRI: R1 (100%/100%), R2 (75.00%/97.12%), R3 (75.00%/99.04%), and using CT: R1 (100%/100%), R2 (66.67%/88.89%), R3 (66.67%/66.67%). The highest agreement was found between R1 and R2 for MRI (κ = 0.62, p < 0.001), and the lowest between R1 and R3 at MRI (κ = 0.28, p < 0.001).

CONCLUSION

Diagnostic accuracy in the assessment of salivary gland tumors strongly depends on the observer's expertise and increases with higher experience.

The value of combining conventional, diffusion-weighted and dynamic contrast-enhanced MR imaging for the diagnosis of parotid gland tumours

OBJECTIVES

The aim of this study was to determine the value of combining conventional MRI, diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE)-MRI in diagnosing solid neoplasms in the parotid gland.

METHODS

A total of 148 subjects (101 subjects with benign and 47 subjects with malignant tumours) were evaluated with conventional MRI, DWI and DCE-MRI prior to surgery and pathologic verification. The items observed with conventional MRI included the shape, capsule and signal intensity of parotid masses. The apparent diffusion coefficient (ADC) was calculated from DWI that was obtained with a b-factor of 0 and 1000 s mm^-2. A time-intensity curve (TIC) was obtained from DCE-MRI.

RESULTS

There were significant differences (p < 0.01) in the shape, capsule, ADC and TIC between benign and malignant parotid tumours. Irregular neoplasms without a capsule, ADC <1.12 × 10^-3 mm² s^-1 and a plateau enhancement pattern were valuable parameters for predicting malignant neoplasms. A combination of all of these parameters yielded sensitivity, specificity, accuracy, positive-predictive value and negative-predictive value of 85.1%, 94.1%, 91.2%, 87.0% and 93.1%, respectively.

CONCLUSIONS

A combined analysis using conventional MRI, DWI and DCE-MRI is helpful in distinguishing benign from malignant tumours in the parotid gland.

Parotid malignancies are not homogenous in terms of their presentation on dynamic MRI - a preliminary report

CONCLUSION

At least two groups of parotid malignancies exist, including one whose parameters of dynamic MRI closely resemble those of pleomorphic adenomas. Also tumors with long time to peak enhancement after administration of a contrast agent (T_peak) and low washout rate (WR) should be considered malignant, especially single masses with concomitant lymphadenopathy located within the deep parotid lobe.

OBJECTIVE

To verify if malignant tumors of the parotid are homogeneous in terms of parameters of preoperative dynamic MRI: T_peak and WR.

METHODS

The retrospective analysis included 221 surgical patients with parotid tumors. Aside from fine needle biopsy, pre-operative examination included dynamic and diffusion-weighted MRI. Final diagnosis was based on histopathological examination of the surgical specimen.

RESULTS

Twenty-four of 221 (10.8%) malignant lesions were identified. Using k-means clustering based on T_peak and WR values, two distinct clusters of parotid malignancies were identified. The cut-off value for T_peak optimally differentiating between the clusters was 140 s; the cut-off value for WR could not be identified. The two clusters did not differ in terms of dynamic and diffusion-weighted MRI parameters, patient age, sex and prevalence of lymphadenopathy. Significant inter-cluster differences were found in the prevalence of deep parotid lobe involvement and presence of a single mass.

The added value of pretreatment DW MRI in characterization of salivary glands pathologies

OBJECTIVE

To evaluate the added value of diffusion weighted magnetic resonance imaging (DW-MRI) in characterization of salivary gland lesions.

STUDY DESIGN

A prospective study was carried out between January 2013, and March 2015.

METHODS

The study included 46 patients. The consultant radiologist, who reviewed the scans to comment on the apparent diffusion coefficient (ADC) value and ADC histogram was blind to the suspected pathology. Radiological findings were then compared to clinical and histological findings.

RESULTS

The diagnostic performance of DW-MRI for identification of malignant lesions showed that the sensitivity, specificity, and positive and negative prediction value were 100%, 92%, 91.3%, and 100%, respectively.

CONCLUSION

The specific ability of DW-MRI to probe tissue microstructures is an interesting complement to the currently used imaging procedures in the characterization, and even grading of malignancies. ADC mapping is an easy, cost effective promising tool that has neither radiation exposure, nor amalgam artifacts and can be used in helping characterization of salivary glands lesions.

LEVEL OF EVIDENCE

1B.

The efficacy of magnetic resonance imaging and color Doppler ultrasonography in diagnosis of salivary gland tumors

Background and aims. Although salivary gland tumors are not very common, early diagnosis and treatment is crucial because of their proximity to vital organs, and therefore, determining the efficacy of new imaging procedures becomes important. This study aimed to evaluate the efficacy of magnetic resonance imaging (MRI) and color doppler ultrasonography parameters in the diagnosis and differentiation of benign and malignant salivary gland tumors.

Materials and methods. In this cross-sectional study, color doppler ultrasonography and MRI were performed for 22 patients with salivary gland tumor. Demographic data as well as MRI, color doppler ultrasonography, and surgical parameters including tumor site, signal in MRI images, ultrasound echo, tumor border, lymphadenopathy, invasion, perfusion, vascular resistance index (RI), vascular pulse index (PI) were analyzed using Chi-square test, Fisher's exact test, and independent t-test.

Results. The mean age of patients was 46.59±13.97 years (8 males and 14females). Patients with malignant tumors were older (P < 0.01). The most common tumors were pleomorphic adenoma (36.4%), metastasis (36.4%), and mucoepidermoid carcinoma (9%). Nine tumors (40.9%) were benign and 13 (59.1%) were malignant. The overall accuracy of MRI and color doppler ultrasonography in determining tumor site was 100% and 95%, respectively. No significant difference observed between RI and PI and the diagnosis of tumor.

Conclusion. Both MRI and ultrasonography have high accuracy in the localization of tumors. Well-identified border was a sign of benign tumors. Also, invasion to adjacent structures was a predictive factor for malignancy.

MRI criteria for the diagnosis of pleomorphic adenoma: a validation study

OBJECTIVES

To validate an MRI algorithm characteristic of pleomorphic adenoma (PA).

STUDY DESIGN

Cross-sectional analysis.

SETTING

Academic tertiary-care medical center.

METHODS

A radiologic algorithm for the MRI diagnosis of PA was developed on the basis of five "high probability" criteria that all must be fulfilled for the MRI to qualify as a positive test result: bright T2-signal, sharp margins, heterogeneous nodular enhancement, lobulated contours, T2-dark rim. We then identified MRI images from our institutional database to test the diagnostic accuracy of the proposed algorithm.

RESULTS

A total of 103 parotidectomy cases with adequate MRI studies were identified (pleomorphic adenoma n=41, mucoepidermoid carcinoma n=11, Warthin's tumor n=8, adenoid cystic carcinoma n=6, oncocytoma n=6, acinic cell carcinoma n=5, salivary duct carcinoma n=5, and other n=21). Eighteen of 21 cases that met all five "high probability" MRI criteria were consistent with PA on final histopathology; 3 were consistent with carcinoma. MRI had a specificity of 95.1% [95% confidence interval: 85.6-98.7%] and sensitivity of 43.9% [95% C.I.: 28.8-60.1%] for PA. The positive predictive value was 85.7% [95% C.I.: 70.4-100%] and the negative predictive value was 71.9% [95% C. I.: 62.0-81.9%]. The overall diagnostic accuracy was 74.8% [95% C.I.: 66.2-83.3%].

CONCLUSION

A "high probability" MRI is about 95% specific for pleomorphic adenoma. A subset of patients with MRI imaging that is highly suggestive of PA may reliably avoid further workup. The value of MRI in this setting is especially useful if preoperative fine needle aspiration is not readily available. A significant proportion of PAs, however, have indeterminate imaging features that overlap considerably with other benign and malignant lesions.

[Salivary gland tumors, clinico-epidemiological study and radioanatomy correlation: retrospective study of 148 cases]

Les tumeurs des glandes salivaires sont rares, elles représentent moins de 3% de l'ensemble des tumeurs. Les tumeurs bénignes sont les plus fréquentes dominées par l'adénome pléomorphe, la glande parotide reste la localisation la plus commune. L'objectif de ce travail est d’évaluer la contribution des 3 méthodes d'imagerie: échographie, TDM et IRM dans la différentiation entre tumeur maligne et lésion bénigne. C'est une étude rétrospective à propos de 148 cas de tumeurs des glandes salivaires collectés sur 5 ans. Les paramètres étudiés étaient l’âge, le sexe du patient, le motif de consultation, les données de l'examen clinique, les données de l'imagerie. Chacun des critères radiologiques utilisés pour déterminer la nature de la tumeur a été analysée et corrélé avec les données de l'histologie. L'analyse s'est basée sur le test du X2 et le calcul du p. Nous avons calculé la sensibilité, la spécificité et l'efficacité diagnostique pour chaque modalité. La localisation parotidienne était prédominante (80%), les tumeurs bénignes ont représenté 76%, dominés par l'adénome pléomorphe. L’échographie a révélé que seulement la présence de quelques critères prédisent le caractère malin de la masse: les limites floues, irrégulières, et la présence d'adénopathies (p < 0,05). A la TDM, seules les limites floues de la masse et l'extension aux tissus adjacents étaient des indicateurs de malignité. A l'IRM, l'irrégularité des contours, l'hyposignal et le signal intermédiaire en séquences T1 et T2, et l'extension aux tissus avoisinants étaient en faveur de la malignité. La corrélation entre résultats de l'imagerie et diagnostic histologique a révélé la supériorité de l'IRM par rapport au scanner et à l’échographie, en termes de sensibilité, spécificité et efficacité diagnostique. L’évaluation préopératoire des tumeurs des glandes salivaires est devenue un challenge pour les ORL et les radiologues, pour prédire la nature de la lésion. L'IRM représente l'examen de choix, notamment avec l'apparition des nouvelles techniques dynamiques.

High-frequency ultrasound in parotid gland disease

Parotid gland is involved in many inflammatory and neoplastic conditions. Many a times, it is difficult to ascertain the type of swelling by clinical examination. The anatomy and various abnormalities of the glands are very easily visualized by high-frequency ultrasound. Ultrasound can confirm the presence of the mass with sensitivity up to 100%. It can demonstrate whether a lesion is located in the parotid gland or outside. It can help in differentiating benign from malignant neoplasms and local staging of the mass in malignant lesions. In addition, ultrasound can identify those entities that may not need surgical intervention. The glands appear enlarged and show altered echopattern in acute inflammation and may be normal or reduce in size in chronic inflammation. Other pathologies that involve salivary glands are sialolithiasis and various benign and malignant neoplasms. Ultrasound many times suggests final diagnosis or supplies important differential diagnosis. In this article, the use of high-frequency ultrasound in parotid disease is discussed, and sonographic features of different parotid pathologies are reviewed with examples illustrated. High-frequency ultrasound is the first and many a times the only imaging investigation done for evaluation of parotid glands.

Salivary gland tumors of the parotid gland: CT and MR imaging findings with emphasis on intratumoral cystic components

INTRODUCTION

The purpose of this study was to assess computed tomography (CT) and magnetic resonance (MR) imaging findings of salivary gland tumors of the parotid gland with emphasis on intratumoral cystic components.

METHODS

Seventy-two histopathologically confirmed salivary gland tumors of the parotid gland (44 benign and 28 malignant), which underwent both CT and MR imaging including contrast-enhanced study, were included in this study. We retrospectively reviewed images for the presence, number, occupying rate, margin characteristics, distribution, and predominant MR signal intensity of intratumoral cystic components.

RESULTS

The prevalence of cystic components was greater in malignant than benign tumors (79 vs. 50%, p < 0.05). The number and occupying rate were similar between benign and malignant tumors. The irregular margins were more frequent in malignant than benign tumors (73 vs. 27%, p < 0.01). The frequency of eccentric location was greater in benign than malignant tumors (91 vs. 55%, p < 0.01), whereas the frequency of centric location was greater in malignant than benign tumors (32 vs. 0%, p < 0.01). On T1-weighted images, the frequency of hyperintensity was greater in benign than malignant tumors (50 vs. 9%, p < 0.01), whereas that of isointensity was greater in malignant than benign tumors (50 vs. 0%, p < 0.01). Multiple logistic regression analysis showed that the absence of irregular margins of cystic components only was significantly correlated with the presence of benign salivary gland tumors (p < 0.01).

CONCLUSION

Imaging features of intratumoral cystic components may help to differentiate benign from malignant tumors of the parotid salivary gland.

Carcinoma ex pleomorphic adenoma of the parotid gland

BACKGROUND

Carcinoma ex pleomorphic adenoma (CXPA) is a rare aggressive epithelial malignancy arising from a primary or recurrent benign mixed tumor. Only a few case reports describing the radiologic features of CXPA have been published.

PURPOSE

To describe and characterize the magnetic resonance (MR) imaging findings of CXPA in the parotid gland and correlate them with pathologic findings.

MATERIAL AND METHODS

The MR images of surgically proven CXPA in the parotid gland of five men and five women ranging in age from 28 to 75 years (mean 52 years) were retrospectively reviewed. All MR images were evaluated with emphasis on the size, margin characteristics, extraparotid infiltration, the presence of an encapsulated component, and signal intensity on T2-weighted or short-inversion-time inversion recovery (STIR) images.

RESULTS

The average maximal diameter was 4.3 cm. All 10 tumors had ill-defined boundaries, and seven tumors showed extraparotid infiltration, reflecting invasive growth of the malignant component identified on histological examination. Eight tumors had a round encapsulated component and seven of those signal intensities were a mixture of hypo- and hyperintensity on T2-weighted or STIR images. Histological correlation of these components revealed fibrously encapsulated tumors containing hyalinization and myxoid tissue, suggesting degenerated pleomorphic adenoma. Invasive malignant components had non-specific and various signal intensities.

CONCLUSION

An invasive parotid mass co-existing with a round encapsulated component is suggestive of carcinoma ex pleomorphic adenoma.

Salivary duct carcinomas: clinical and CT and MR imaging features in 20 patients

INTRODUCTION

Salivary duct carcinoma (SDC) is an uncommon high grade adenocarcinoma of the salivary gland with a grave prognosis. The aim of this study was to investigate the clinical and CT and MR imaging features of SDC.

METHODS

We retrospectively evaluated the clinical and CT and MR imaging findings in 20 patients (14 men and six women; mean age, 59 years) with histologically proved SDC. We also tried to correlate clinicoradiological tumor staging with pathologic tumor staging in 17 patients who underwent surgery.

RESULTS

The tumor originated in the parotid gland (n = 11; 55%), the submandibular gland (n = 7; 35%) and the buccal space along the distal Stensen's duct (n = 2; 10%). Locoregional recurrence occurred in 41% and distant metastasis in 47%. Fifty-eight percent died of the disease with a mean survival period of 32 months after diagnosis. On CT and MR images, SDC was mostly seen as an ill-defined (85%) and infiltrative (60%) mass with frequent calcification (50%) and necrosis (80%). Although various signal intensities were seen on MR images, six of nine tumors contained the areas of marked hypointensity on T2-weighted images. Clinicoradiological tumor staging correlated well with pathologic tumor staging in 82% of the patients.

CONCLUSION

Ill-defined, infiltrative mass with calcification on CT scans and the areas of marked hypointensity on T2-weighted MR images may be useful radiologic features to suggest the diagnosis of SDC. CT and MR imaging are useful for staging of SDC.

Oncocytoma: the vanishing parotid mass

Parotid gland oncocytoma is an uncommon, benign salivary neoplasm composed of mitochondria-rich oncocytes. The purpose of this study was to correlate MR imaging and histopathology of parotid gland oncocytomas and to define the features that may distinguish these neoplasms from other benign and malignant parotid gland tumors. The MR imaging features in 9 patients with a pathologic diagnosis of oncocytoma were retrospectively reviewed. The imaging features were strikingly similar for 8 of the 9 patients. All lesions appeared T1 hypointense but isointense to the native parotid gland on fat-saturated T2 and postcontrast T1 imaging. On MR imaging, parotid gland oncocytomas share specific imaging characteristics that have not been described for benign or malignant parotid gland tumors. Oncocytomas are isointense to native parotid gland on fat-saturated T2 and T1 postcontrast MR images. Preoperative identification of correct histology may help surgical planning.

MR imaging of parotid tumors: typical lesion characteristics in MR imaging improve discrimination between benign and malignant disease

BACKGROUND AND PURPOSE

The surgical approach to parotid tumors is different for benign and malignant neoplasms, but the clinical symptoms do not correlate well with histology. Difficulties in tumor classification also arise in imaging modalities, in which sonography has the lowest and MR imaging, the highest accuracy. The purpose of this study was to review our experience using conventional MR imaging of the neck in the evaluation of parotid tumors and to evaluate which MR imaging findings are best able to predict malignant histology.

MATERIALS AND METHODS

Eighty-four consecutive patients (43 males, 41 females; median age, 56 years; range, 9-85 years) with parotid gland tumors who underwent MR imaging before surgery were prospectively included in the present study and retrospectively analyzed. Histology was available for all tumors. We analyzed the following MR imaging parameters: signal intensity, contrast enhancement, lesion margins (well-defined versus ill-defined), lesion location (deep/superficial lobe), growth pattern (focal, multifocal, or diffuse), and extension into neighboring structures, perineural spread, and lymphadenopathy.

RESULTS

The 57 (68%) benign and 27 (32%) malignant tumors consisted of 29 pleomorphic adenomas, 17 Warthin tumors, 11 various benign tumors, 5 mucoepidermoid carcinomas, 3 adenoid cystic carcinomas, 1 acinic cell carcinoma, 1 carcinoma ex pleomorphic adenoma, 9 metastases, and 8 various malignant neoplasms. Specific signs predictive of malignancy were the following: T2 hypointensity of the parotid tumor (P = .048), ill-defined margins (P = .001), diffuse growth (P = .012), infiltration of subcutaneous tissue (P = .0034), and lymphadenopathy (P = .012).

CONCLUSIONS

Low signal intensity on T2-weighted images and postcontrast ill-defined margins of a parotid tumor are highly suggestive of malignancy.

Diffusion-weighted imaging in head and neck cancers

This article reviews the utility of diffusion-weighted imaging (DWI) in the diagnosis, prognosis and monitoring of treatment response in tumors arising in the head and neck region. The apparent diffusion coefficient (ADC) value, determined from DWI, can help in cancer staging and detection of subcentimeter nodal metastasis. The ADC value also discriminates carcinomas from lymphomas, benign lesions from malignant tumors and tumor necrosis from abscesses. Low pretreatment ADC values typically predict a favorable response to chemoradiation therapy. These promising reports indicate the potential of DWI as a potential biomarker for diagnosis and monitoring of treatment response in head and neck cancers. In view of the overlapping ADC values between different salivary gland tumors, care should be taken when interpreting these results and other imaging parameters should be considered for a better diagnosis. Susceptibility and motion-induced artifacts may sometimes degrade DWI image quality; however, novel techniques are being developed to overcome these drawbacks.

Salivary duct carcinoma of the parotid gland: clinical and MR features in six patients

This study reports the clinical and MR features of salivary duct carcinoma (SDC) of the parotid gland, which is a rare and highly malignant tumour. We assessed retrospectively the clinical and MR features of six patients with histologically proven SDC of the parotid gland. The five men and one woman, ranging in age from 65-71 years (mean, 67 years), had undergone MRI before surgery. All patients presented with parotid masses and four patients had facial paralysis. Two had been aware of the parotid mass for more than 10 years. On MRI, all of the tumours had an ill-defined margin along either the entire circumference or part of the circumference. Four tumours showed infiltration into the subcutaneous or parapharyngeal space. Two tumours showed a wholly solid internal content, and four tumours had varying proportions of cystic content. The signal intensity of the solid portion was low to intermediate on both T(1) weighted and T(2) weighted images. Three patients showed multiple cervical lymph node swellings. Although SDC can show non-specific MRI findings, the combined findings (e.g. low-to-intermediate signal intensities on T(2) weighted images, ill-defined boundaries, infiltration into the surrounding fat space, facial nerve paralysis and associated cervical lymphoadenopathy, seem to suggest a high-grade malignancy.

[Parotid gland masses: diagnostic value of MR imaging with histopathologic correlations]

BACKGROUND AND PURPOSE

The purpose of our study has been to describe the pre-operatively MR Imaging appearance of masses in the parotid gland which may be sources of clinical and radiological confusion.

METHODS

Sixty-eight adults patients with a parotid mass (39 female, 29 male) has been prospectively investigated. T1-weighted, T2-weighted, diffusion-weighted and contrast-enhanced dynamic MR images were performed by using a 1.5 or 1 T MR Imaging unit (Philips Gyroscan Intera 1.5 T. Siemens Expert 1 T). All patients underwent a parotidectomy with histopathologic analysis.

RESULTS-CONCLUSIONS

In case of pleomorphic adenoma (N=30) MR imaging sensibility, specificity and accuracy were respectively 87.5, 80.5 and 83%. In case of Warthin tumors (N=13) the same values were respectively 45.5, 93 and 85%. In case of malignant tumors (N=13) theses values were respectively 71, 89 and 87%. Our routine MR Imaging study appears excellent not only for assessing the type and extent of benign salivary gland tumors and the relationship to adjacent structures, but also for determining whether the tumor is benign or malignant.

Carcinoma ex pleomorphic adenoma of the parotid gland: radiologic-pathologic correlation with MR imaging including diffusion-weighted imaging

We present 4 cases of carcinoma ex pleomorphic adenoma of the parotid gland. In 3 of the 4 cases, diffusion-weighted and apparent diffusion coefficient (ADC) mapping images clearly revealed carcinoma as a hypercellular area with low ADC values and pleomorphic adenoma as a hypocellular area with high ADC values. Diffusion-weighted images demonstrated well complex tissue components in carcinoma ex pleomorphic adenoma, which may be useful for the diagnosis of this disease.

CT and MR images of pleomorphic adenoma in major and minor salivary glands

PURPOSE

To investigate the CT and MR imaging features of pleomorphic adenoma in the head and neck area.

MATERIALS AND METHODS

Our materials of this study consisted of 50 pleomorphic adenomas from 50 patients which were all histopathologically diagnosed. The CT and MR images were retrospectively evaluated. The following features were evaluated: the detectability of the lesion, the tumor margin, the border of the lesion, the aspect of the lesion, the contrast between the lesion and surrounding tissue, the signal intensity of the lesion, the enhancement of contrast medium, the aspect of the lesion after the injection of contrast medium, the detectability of the capsule, and the detectability of bone resorption of the lesion.

RESULTS

The tumor detectabilities were 77% on axial plain CT images and 90% on axial CE CT images, respectively. On CT images, pleomorphic adenoma tended to show a well-defined margin, a smooth border, an inhomogeneous aspect, a low or high contrast, and intermediate or high signal intensity. After contrast medium administration, pleomorphic adenoma tended to show a slightly high enhancement and either an inhomogeneous or a periphery enhancement on the CE CT images. The capsule could be hardly detected on CT images. The tumor detectabilities were 86% on axial T1-weighted MR images, 88% on axial T2-weighted MR images, and 85% on axial CE T1-weighted MR images, respectively. On MR images, pleomorphic adenomas tended to show well-defined margin, a lobulate border, an inhomogeneous aspect, a high contrast, and intermediate or high signal intensity. After contrast medium administration, pleomorphic adenoma tended to show a high enhancement and either an inhomogeneous or a periphery enhancement on MR images. The capsule could be detected in many cases on MR images.

CONCLUSIONS

It was possible to detect the capsule in pleomorphic adenoma using MR images. The pleomorphic adenomas in head and neck area should be evaluated with MR images.