CT and MR imaging findings of non-neoplastic cystic lesions of the parotid gland

Cystic lesions in the salivary gland. Pitfalls to be avoided on cytology

Cystic lesions of the salivary glands are very uncommon entities. However, on occasion, some neoplasms of the salivary glands show a cystic component, which may be predominant or only partially cystic. Basal cell adenoma, canalicular adenoma, oncocytoma, sebaceous adenoma, intraductal papilloma, epithelial-myoepithelial carcinoma, intraductal carcinoma, and secretory carcinoma are such cystic entities. Cystic degeneration and necrosis, which can develop within solid tumours, represent another possibility. The ability to recognise this type of lesion is a challenge in diagnostic cytology because hypocellular fluid is frequently recovered. Furthermore, evaluating all of the differential diagnoses for cystic lesions of the salivary glands is helpful in obtaining the correct diagnosis. Herein, we evaluate the various types of cystic lesions within the salivary glands.

Congenital Cystic Neck Masses

Congenital cystic masses are commonly encountered when imaging a patient presenting with a neck mass. Congenital cysts are present at birth; however, these cysts may not present until later in life with some growing slowly and others rapidly increasing in size due to hemorrhage of infection. A neonatal presentation is rare but when present may allow a narrower differential diagnosis. Imaging plays a significant role in defining a lesion as cystic, assessing location, and directing the next step in evaluation and or intervention.

Three Signs to Help Detect Sjögren's Syndrome: Incidental Findings on Magnetic Resonance Imaging and Computed Tomography

This study aimed to retrospectively investigate the prevalence of Sjögren's syndrome (SS) among patients with ranulas, parotid cysts, or parotid calcifications; identify the characteristic magnetic resonance imaging (MRI) or computed tomography (CT) findings of the lesions associated with SS; and compare the SS disease stages among SS patients with the three lesion types. A total of 228 patients with the lesions were classified into SS, possible SS, and non-SS groups. The prevalence of SS among patients with ranulas, parotid cysts, or parotid calcifications was 16%, 24%, and 40%, and the rates of either SS or possible SS were 25%, 41%, and 64%, respectively. SS was associated with (i) ranulas: ≤17 mm; (ii) parotid cysts: bilateral and multiple; and (iii) parotid calcifications: in females, bilateral, multiple, parenchymal, and no coexisting calcifications in other tissues. SS patients with ranulas were significantly younger and had lower submandibular gland stage scores on MRI/CT than those with other lesions. Additionally, in 58% and 15% of SS patients with ranulas and parotid calcifications, respectively, detection of the lesions led to the diagnosis of primary SS. Therefore, recognizing the prevalence of SS among patients with these lesions and the findings associated with SS can help detect undiagnosed SS.

MRI findings of sporadic/simple lymphoepithelial cyst of the parotid gland

PURPOSE

This study aimed to determine the MRI features of sporadic/simple lymphoepithelial cyst (SLEC) of the parotid gland.

METHODS

Ten patients (seven men, three women; mean age, 60 years; age range, 38-77 years) with histopathologically and clinically proven SLEC of the parotid gland who underwent MRI before surgical resection were enrolled in this study. No enrolled patient had HIV infection or Sjögren syndrome. MRI findings of SLEC were retrospectively assessed.

RESULTS

We confirmed 10 SLECs larger than 10 mm with a mean maximum diameter of 26.6 mm (range, 12-42 mm). Nine patients (90%) had a single cyst, and one (10%) had a large cyst accompanied by small cysts (<10 mm) within the ipsilateral parotid gland. Eight SLECs (80%) were unilocular, and two (20%) were bilocular, with complete septa. Among seven SLECs (70%) with internal septa, five unilocular SLECs (50%) had incomplete septa. Six SLECs (60%) had eccentric cyst wall thickening, and five (50%) were surrounded by small solid nodules that were isointense relative to lymph node. On T1-weighted images, all cyst contents were homogeneously hyperintense relative to cerebrospinal fluid.

CONCLUSION

SLECs of the parotid gland are usually single unilocular lesions. Internal septa, eccentric cyst wall thickening, and small solid nodules surrounding the lesion were often observed. Cyst contents are always homogeneously hyperintense on T1-weighted images.

Newly Discovered Parotid Lesion: What Next?

When a parotid lesion is discovered incidentally, it can be challenging for the radiologist to provide specific recommendations for the next steps. This article describes how the radiologist can play an active role in managing incidentally discovered parotid lesions. First, we explore the significance of parotid lesions. Next, the pertinent anatomy of the parotid space is presented to develop an appropriate differential diagnosis. Lastly, we discuss critical clinical and imaging characteristics the radiologist can use to provide specific recommendations.

Myoepithelial Carcinoma Arising in a Salivary Duct Cyst of the Parotid Gland: Case Presentation

Cystic lesions observed in parotid glands are relatively rare and comprise 2-5% of all parotid primaries. A salivary duct cyst (SDC) is a true cyst representing 10% of all salivary gland cysts. The risk of malignant transformation of SDC's epithelium is extremely rare. In the literature, only three cases of carcinoma ex SDC of the parotid gland are described. This report presents the first in the literature case of myoepithelial carcinoma (MECA) arising from a parotid SDC. A 75-year-old male patient was referred to the Department of Cranio-Maxillofacial Surgery of the Jagiellonian University in Cracow, Poland due to a cystic tumor arising from the right parotid gland. Superficial parotidectomy with facial nerve preservation was performed. Histological examination confirmed a rare case of MECA emerging from the SDC. The immunohistochemical profile of MECA ex SDC was presented. During 6 months of the follow-up, local recurrence or distant metastasis was not observed.

Magnetic resonance imaging of parotid gland tumors: a pictorial essay

Imaging of parotid gland tumors is challenging due to the wide variety of differential diagnoses. Malignant parotid tumors can have very similar features to benign ones, such as slow growth and displacement instead of infiltration of neighboring structures. Malignant and benign tumors may therefore not be clinically distinguishable. Correct characterization of parotid tumors (i.e., benign or malignant) determines preoperative treatment planning and is important in optimizing the individualized surgical plan. Magnetic resonance imaging (MRI) is the imaging modality of choice for evaluation of suspected parotid gland lesions and differentiation between benign and malignant lesions. Certain conventional MRI features can suggest whether a mass is more likely to be a benign or low-grade malignancy or a high-grade malignancy and adding diffusion-weighted imaging or advanced MRI techniques like perfusion can aid in this distinction. Morphological features seen on MRI, such as low signal on T2-w, infiltrative changes or ill-defined margins, change over time and diffusion restriction can point to the malignant nature of the lesion. MRI is useful for detection and localization of the lesion(s), and associated findings like perineural spread of tumor, lymph node involvement and infiltrative changes of the surrounding tissues. In this pictorial essay, we present selected images of a variety of benign and malignant parotid tumors and emphasize the MRI features that may be useful in their characterization.

Deep Learning-Based Image Segmentation of Cone-Beam Computed Tomography Images for Oral Lesion Detection

This paper aimed to study the adoption of deep learning (DL) algorithm of oral lesions for segmentation of cone-beam computed tomography (CBCT) images. 90 patients with oral lesions were taken as research subjects, and they were grouped into blank, control, and experimental groups, whose images were treated by the manual segmentation method, threshold segmentation algorithm, and full convolutional neural network (FCNN) DL algorithm, respectively. Then, effects of different methods on oral lesion CBCT image recognition and segmentation were analyzed. The results showed that there was no substantial difference in the number of patients with different types of oral lesions among three groups (P > 0.05). The accuracy of lesion segmentation in the experimental group was as high as 98.3%, while those of the blank group and control group were 78.4% and 62.1%, respectively. The accuracy of segmentation of CBCT images in the blank group and control group was considerably inferior to the experimental group (P < 0.05). The segmentation effect on the lesion and the lesion model in the experimental group and control group was evidently superior to the blank group (P < 0.05). In short, the image segmentation accuracy of the FCNN DL method was better than the traditional manual segmentation and threshold segmentation algorithms. Applying the DL segmentation algorithm to CBCT images of oral lesions can accurately identify and segment the lesions.

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

Background

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

Methods

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

Results

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

Conclusions

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

Orthodontic appliances and MR image artefacts: An exploratory in vitro and in vivo study using 1.5-T and 3-T scanners

Purpose

The aim of this study was to assess the artefacts of 12 fixed orthodontic appliances in magnetic resonance images obtained using 1.5-T and 3-T scanners, and to evaluate different imaging sequences designed to suppress metal artefacts.

Materials and Methods

In vitro, study casts of 1 adult with normal occlusion were used. Twelve orthodontic appliances were attached to the study casts and scanned. Turbo spin echo (TSE), TSE with high readout bandwidth, and TSE with view angle tilting and slice encoding for metal artefact correction were used to suppress metal artefacts. Artefacts were measured. In vivo, 6 appliances were scanned: 1) conventional stainless-steel brackets; 2) nickel-free brackets; 3) titanium brackets; 4) a Herbst appliance; 5) a fixed retainer; and 6) a rapid maxillary expander. The maxilla, mandible, nasopharynx, tongue, temporomandibular joints, and cranial base/eye globes were assessed. Scores of 0, 1, 2, and 3 indicated no artefacts and minor, moderate, and major artefacts, respectively.

Results

In vitro, titanium brackets and the fixed retainer created minor artefacts. In vivo, titanium brackets caused minor artefacts. Conventional stainless-steel and nickel free brackets, the fixed retainer, and the rapid maxillary expander caused major artefacts in the maxilla and mandible. Conventional stainless-steel and nickel-free brackets caused major artefacts in the eye globe (3-T). TSE with high readout bandwidth reduced image artefacts in both scanners.

Conclusion

Titanium brackets, the Herbst appliance, and the fixed retainer caused minor artefacts in images of neurocranial structures (1.5-T and 3-T) when using TSE with high readout bandwidth.