MR imaging of salivary glands

Morphologic CT and MRI features of primary parotid squamous cell carcinoma and its predictive factors for differential diagnosis with mucoepidermoid carcinoma

Background

Primary parotid squamous cell carcinoma (SCC) is a rare entity with a poor prognosis. Pathologically, the diagnosis of it requires the exclusion of parotid mucoepidermoid carcinoma (MEC). Currently, the imaging features of primary parotid SCC and the predictive indicators for differential diagnosis of the two entities have not been well reported. Our purpose was to identify the imaging characteristics of primary parotid SCC and to determine the predictive factors for its’ differential diagnosis.

Results

Thirty-one participants with primary parotid SCC and 59 with primary parotid MEC were enrolled. Clinical, CT and MRI features were reviewed and compared by univariate analysis. Then, multinomial logistic regression was used to determine the predictors to distinguish parotid SCC from MEC. Most primary parotid SCCs exhibited irregular shape, ill-defined margin, incomplete or no capsule, heterogeneous and marked or moderate enhancement, necrosis, local tumor invasiveness (LTI). Age, maximal dimension, shape, degree of enhancement, gradual enhancement, necrosis, and LTI were different between the primary parotid SCCs and MECs in univariate analysis (p < 0.05). While in multinomial logistic regression analysis, only age and necrosis were the independent predictors for distinguishing parotid SCC from MEC, and this model exhibited an area under curve of 0.914 in ROC curve analysis.

Conclusions

Primary parotid SCC has some distinct imaging features including the large tumor size, irregular shape, ill-defined margin, and particularly the marked central necrosis. Patients with age ≥ 51.5 years and necrosis on the image of the primary tumor in the parotid gland could be more likely to be SCCs than MECs.

Imaging of parotid anomalies in infants and children

A wide spectrum of disorders involves the parotid glands, in infancy and childhood. Acute or chronic inflammatory/infectious diseases are predominant. The first branchial cleft anomalies are congenital lesions that typically manifest during childhood. Tumor lesions are more likely to be benign, with infantile hemangioma the most common in infancy and pleomorphic adenoma the most frequent in childhood. Malignant tumors are uncommon, with mucoepidermoid carcinoma the least rare. Infiltrative parotid diseases are rare and have some pediatric clinical specificities. These common and uncommon disorders of parotid glands during childhood and their imaging characteristics are reviewed.

Surgical Navigation, Augmented Reality, and 3D Printing for Hard Palate Adenoid Cystic Carcinoma En-Bloc Resection: Case Report and Literature Review

Adenoid Cystic Carcinoma is a rare and aggressive tumor representing less than 1% of head and neck cancers. This malignancy often arises from the minor salivary glands, being the palate its most common location. Surgical en-bloc resection with clear margins is the primary treatment. However, this location presents a limited line of sight and a high risk of injuries, making the surgical procedure challenging. In this context, technologies such as intraoperative navigation can become an effective tool, reducing morbidity and improving the safety and accuracy of the procedure. Although their use is extended in fields such as neurosurgery, their application in maxillofacial surgery has not been widely evidenced. One reason is the need to rigidly fixate a navigation reference to the patient, which often entails an invasive setup. In this work, we studied three alternative and less invasive setups using optical tracking, 3D printing and augmented reality. We evaluated their precision in a patient-specific phantom, obtaining errors below 1 mm. The optimum setup was finally applied in a clinical case, where the navigation software was used to guide the tumor resection. Points were collected along the surgical margins after resection and compared with the real ones identified in the postoperative CT. Distances of less than 2 mm were obtained in 90% of the samples. Moreover, the navigation provided confidence to the surgeons, who could then undertake a less invasive and more conservative approach. The postoperative CT scans showed adequate resection margins and confirmed that the patient is free of disease after two years of follow-up.

Actual applications of magnetic resonance imaging in dentomaxillofacial region

Magnetic resonance imaging (MRI) is a versatile imaging modality utilized in various medical fields. Specifically used for evaluation of soft tissues, with non-ionizing radiation and multiplanar sections that has provided great guidance to diagnosis. Nowadays, use of MRI in dental practice is becoming more pervasive, especially for the evaluation of head-and-neck cancer, detection of salivary gland lesions, lymphadenopathy, and temporomandibular joint disorders. Understanding the basic principles, its recent advances, and multiple applications in dentomaxillofacial region helps significantly in the diagnostic decision making. In this article, the principle of MRI and its recent advances are reviewed, with further discussion on the appearance of various maxillofacial pathosis.

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.

Renal Cell Carcinoma: Delayed Metachronous Metastases to Parotid and Cerebellum

PURPOSE

The purpose of this report is to describe a rare case of delayed metachronous isolated metastases of renal cell carcinoma (RCC) to the parotid gland and the cerebellum. The metastases occurred more than a decade after treatment of the primary tumor without any other systemic involvement. In addition, the potential differential diagnosis of the parotid mass based on presentation and imaging is discussed.

MATERIALS AND METHODS

An 83-year-old man presented for evaluation and treatment of a rapidly growing mass at the right parotid region. He had a history of RCC resection 10 years before this presentation and had no evidence of persistent disease at the primary site. The diagnosis of metastatic RCC was made after fine-needle aspiration biopsy examination of the mass. The patient underwent superficial parotidectomy for resection of the tumor. Approximately 1.5 years later, he complained of loss of balance. Further investigation disclosed a cerebellar mass that at biopsy examination was found to represent RCC. He underwent stereotactic ablation of the mass. He currently remains free of disease at the primary site and the parotid and without further known brain metastases.

RESULTS

This report presents the 29th case of a solitary parotid mass consistent with metastatic RCC 10 years after successful treatment of the primary RCC. Approximately 1.5 years later, the patient presented with new-onset loss of balance. Further investigation disclosed a mass to the cerebellum consistent with metastatic RCC. This case is unique because the brain involvement occurred extremely late, 11.5 years after successful treatment of primary RCC and 1.5 years after resection of a metastatic RCC to the parotid, and without any evidence of other metastases.

CONCLUSIONS

Late distant metastases of RCC are not uncommon and patients require life surveillance follow-up, but such late presentation of metachronous metastases without systemic disease progression is unique. The patterns of metastases of RCC are not clearly defined and this diagnosis should be considered, especially in patients with relevant history.

Follow-up strategies in head and neck cancer other than upper aerodigestive tract squamous cell carcinoma

Post-therapy follow-up for patients with head and neck cancer other than upper aerodigestive tract squamous cell carcinoma should meet several objectives: to detect both local, regional or distant recurrences, to evaluate acute and long-term treatment-related side effects, to guide the rehabilitation process, and to provide psychosocial support when needed. To our knowledge, there are no published reports in the literature dedicated to the follow-up of patients with these tumours. A comprehensive literature search for post-treatment follow-up strategies spanning from 1980 to 2012 was performed on several databases. This review focuses on malignant salivary gland tumors, soft tissue sarcomas, cutaneous squamous cell carcinomas, and sinonasal adenocarcinomas. Given the varying biological behavior and treatment-related factors and based on the literature, different recommendations are made on the follow-up of patients with the above-mentioned tumors.

Mucocele in lower lip as a result of improper use of feeding bottle: a case report

A rare case of mucocele associated with improper feeding habit has been presented. An eight-month old male child presented with swelling in lower lip which was noticed by his mother a week earlier. A thorough clinical examination and history taking gave a diagnosis of mucocele resulting from improper use of feeding bottle. This case highlights and discusses the history, the clinical along with histologic features, and the clinical management of this lesion. Awareness of such an entity and the functional problems associated with the lesion will help the pediatric dentist to prevent any further complications.

Ultrasound GLCM texture analysis of radiation-induced parotid-gland injury in head-and-neck cancer radiotherapy: an in vivo study of late toxicity

PURPOSE

Xerostomia (dry mouth), secondary to irradiation of the parotid glands, is one of the most common side effects of head-and-neck cancer radiotherapy. Diagnostic tools able to accurately and efficiently measure parotid gland injury have yet to be introduced into the clinic. This study's purpose is to investigate sonographic textural features as potential imaging signatures for quantitative assessment of parotid-gland injury after head-and-neck radiotherapy.

METHODS

The authors have investigated a series of sonographic features obtained from the gray level co-occurrence matrix (GLCM) - a second order statistical method of texture analysis. These GLCM textural features were selected based on empirical observations that the normal parotid gland exhibits homogeneous echotexture, whereas the postradiotherapy parotid gland often exhibits heterogeneous echotexture. We employed eight sonographic features: (1) angular second moment (ASM), (2) inverse differential moment (IDM), (3) contrast, (4) variance, (5) correlation, (6) entropy, (7) cluster shade, and (8) cluster prominence. Altogether, sonographic properties of the parotid glands were quantified by their degrees of homogeneity (ASM and IDM), heterogeneity (contrast and variance), smoothness (correlation), randomness (entropy), and symmetry (cluster shade and prominence). The sonographic features were tested in a pilot study of 12 postradiotherapy patients and 7 healthy volunteers. The mean follow-up time for the postradiotherapy patients was 17.2 months (range: 12.1-23.9 months) and the mean radiation dose to the parotid glands was 32.3 Gy (range: 11.0-63.4 Gy). Each participant underwent one ultrasound study in which longitudinal (vertical) ultrasound scans were performed on the bilateral parotids - a total of 24 postirradiation and 14 normal parotid glands were examined. The 14 normal parotid glands served as the control group. A radiologist contoured the parotid glands on the B-mode images and the sonographic features were computed from the contoured region-of-interest.

RESULTS

The authors observed significant differences (p < 0.05) in all sonographic features between the normal and postradiotherapy parotid glands. The sonographic findings were consistent with the clinical observations of the ultrasound images: normal parotid glands exhibited homogeneous texture, while the postradiotherapy parotid glands exhibited heterogeneous echotexture (e.g., hyperechoic lines and spots), which likely represents fibrosis.

CONCLUSIONS

The authors have demonstrated the feasibility of ultrasonic texture evaluation of parotid glands; and the sonographic features may serve as imaging signatures to assess radiation-induced parotid injury.

Recurrent salivary gland cancer

OPINION STATEMENT

Salivary gland cancer is the most diverse cancer in the body consisting of up to 24 different pathologic subtypes. Although these cancers arise within a common group of glands in the head and neck region, these diverse cancers differ substantially in clinical behavior. As a result, salivary cancers are often categorized as low, intermediate, or high-risk for recurrence and metastasis based on histopathologic subtype and tumor stage. Appropriate risk classification of a given salivary tumor provides a useful guide to the physicians who determine the appropriate treatment regimen. Low-risk tumors can be treated successfully with surgery alone, whereas intermediate and high-risk tumors often require multimodality therapy. Recurrent salivary cancer should be considered high-risk by definition, especially if previously treated with appropriate therapy, and therefore requires aggressive multimodality therapy in order to achieve adequate local control and disease-free survival.

Assessment of post-radiotherapy salivary glands

Salivary glands are usually irradiated during radiotherapy for head and neck cancers, which can lead to radiation-induced damage. Radiation-induced xerostomia (oral dryness) is the most common post-radiotherapy complication for head and neck cancer patients and can reduce the patient's quality of life. Accurate and efficient salivary gland assessment methods provide a better understanding of the cause and degree of xerostomia, and may help in patient management. At present, there are different methods for the assessment of salivary gland hypofunction; however, none of them are considered to be standard procedure. This article reviews the value of common methods in the assessment of post-radiotherapy salivary glands.

Sonographic appearance of parotid glands in patients treated with intensity-modulated radiotherapy or conventional radiotherapy for nasopharyngeal carcinoma

This study aimed to investigate and compare the sonographic appearances of parotid glands in nasopharyngeal carcinoma patients treated with conventional radiotherapy (RT) or intensity-modulated radiotherapy (IMRT), and to compare them with healthy subjects. Totally 43 patients treated with conventional RT, 38 patients treated with IMRT and 58 healthy subjects were recruited and underwent parotid ultrasonography. Parotid glands were assessed for their size, echogenicity and internal architectures. The mean transverse dimension of parotid glands in patients treated with conventional RT and those treated with IMRT were significantly smaller than that in healthy subjects (p < 0.05). Parotid glands of the IMRT group tended to be hyperechoic (93%), homogenous (62%), without hypoechoic areas (64%) and with marginally-seen intra-parotid ducts (89%), which are similar to those in healthy subjects. Parotid glands in the conventional RT group tended to be hypoechoic (51%), heterogeneous (98%), with hypoechoic areas (94%) and had obviously-seen intra-parotid ducts (64%). For accurate diagnosis, post-RT changes of parotid glands should be noted in ultrasound examination of patients with previous radiotherapy.

Small salivary gland size in patients with xerostomia of unknown etiology

OBJECTIVE

We have recently reported that flow rates of whole saliva in young healthy humans correlate positively with salivary gland sizes. The low rate of salivary secretion in xerostomia patients may be related to the small size of the salivary glands. To investigate this possibility, relationships between salivary secretions and salivary gland sizes were investigated in unknown-etiology xerostomia patients and healthy controls.

DESIGN

The sizes of the three major salivary glands in seven xerostomia patients and seven age- and gender-matched healthy controls who have no previous disease history and prescription medication related to xerostomia, were measured by use of a magnetic resonance imaging technique. The salivary glands of all subjects failed to show any pathological aspects in magnetic resonance images. The flow rates of unstimulated and chewing-stimulated whole saliva were also measured.

RESULTS

Flow rates of unstimulated and chewing-stimulated whole saliva and the sizes of the parotid and submandibular glands were significantly lower and smaller in xerostomia patients of unknown etiology when compared with healthy controls. In addition, salivary flow rates per size of the combined three major salivary glands were also significantly lower in the xerostomia patients of unknown etiology.

CONCLUSIONS

The smaller salivary gland size in xerostomia patients of unknown etiology may be one of the causes of the reduced salivary secretion. The secretion rates as a function of gland sizes were also lower, and so it is likely that functional impairments of the salivary gland are also present in patients with xerostomia of unknown etiology.

Salivary gland malignancies: the role for chemotherapy and molecular targeted agents

Salivary gland tumors are a rare and clinically diverse group of neoplasms that represent less than 1% of all malignancies. In locoregional recurrent or metastatic disease, systemic therapy is the standard approach. Numerous phase II studies with small sample sizes have assessed the activity of different cytotoxic agents, either alone or in combination. For these agents, the objective response rates are generally modest, ranging from 15% to 50%. Duration of response is typically cited in the range of 6 to 9 months. Further evaluation of novel therapies is mandated in this disease. With the emergence of molecular targeted therapy, these tumors become optimal candidates for trials of investigational drugs and established drugs for new indications. Often, salivary gland carcinomas are indolent. As such, one should wish only to treat patients with progressive disease. Study designs must incorporate stringent inclusion criteria to enable accurate reporting of disease response and stabilization, especially in the evaluation of new drugs and novel combinations. Salivary gland-focused cooperative groups are necessary in order to accrue patients to these clinical trials and establish new treatment guidelines for these patients.

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.

Epithelial-myoepithelial carcinoma of the parotid gland, unusual malignancy radiologically simulating a benign lesion: case report

Background

Ultrasound (US), Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are widely used in the clinical diagnosis of parotid gland tumors and their efficacy in identifying benign lesions is well documented. However, problems arise when facing some malignant lesions. Only few cases of salivary gland low grade malignant tumors have been previously reported in the literature complete with the radiological features.

Case presentation

We here describe a case of epithelial-myoepithelial carcinoma (EMC) of the parotid gland, a low grade malignant tumor, with spread to an intraparotid lymph node and with CT and MRI findings mimicking a benign lesion.

Conclusion

All the images revealed sharply outlined profiles and a homogeneous enhancement of the nodule, suggesting a benign tumor and demonstrating that a radiological evaluation of the lesion alone may be unsatisfactory and misleading in the diagnosis of salivary gland tumours, especially in the case of low grade malignant tumors, such as EMC.

Neither MRI, CT nor US is superior to diagnose tumors in the salivary glands--an extended case study

OBJECTIVES

Ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI) are the most common radiological procedures for the diagnosis of tumor-like lesions of the salivary glands. The aim of the present study was to determine whether MRI or CT provide additional information besides that delivered by US.

STUDY DESIGN/METHODS

109 patients with a tumor-like lesion of the salivary glands underwent surgery. MRI and CT were arranged in 73 and in 40 patients respectively, whereas all 109 patients were prospectively diagnosed by US. The results of CT, MRI and US were compared with the histological outcome. Furthermore, the recent rise in the number of CT and MRI studies was investigated.

RESULTS

On CT and MRI, there was no rise in the percentage of malignant tumors or advanced surgical procedures. In respect of the radiological assessment of the lesion (benign/malignant) and the correct diagnosis, CT, MRI and US were comparable in terms of sensitivity, specificity and accuracy. No significant difference was found in the Chi-square test (p > 0.05).

CONCLUSION

The evaluation of the preoperative results of CT, MRI and US revealed no advantage for CT or MRI; these procedures are only required in specific cases. An update or revision of the current preoperative diagnostic management is deemed necessary.

Imaging in head and neck cancer

The goals of imaging in head and neck cancer are to establish tumor extent and size, to assess nodal disease, to evaluate for perineural tumor spread, and to distinguish recurrent tumor from post-treatment changes. MRI is the preferred modality for assessment of nasopharyngeal, sinonasal, and parotid tumors, because of better contrast resolution, high frequency of perineural spread, and less prominent motion artifacts. MRI is the best modality to delineate the extent of intraorbital and intracranial extension of malignant tumors. Tumors of the oropharynx, larynx, and hypopharynx are frequently primarily imaged with CT, which is less affected by breathing and swallowing artifacts. MRI is also the initial study of choice for tumors confined to the oral tongue, and possibly also for other oral cavity locations because MRI is superior in detection of tumor spread into the bone marrow. There is no clear advantage of CT or MRI for evaluation of nodal disease. Positron emission tomography (PET) is very sensitive for metastatic lymph nodes that are at least 8 mm in size and is the technique of choice in dubious cases. Imaging-guided biopsies are performed whenever needed. For imaging of treated head and neck cancer, PET scans have been found to generally offer higher sensitivity than MRI or CT. Combined PET/CT may be the modality of choice because it almost completely eliminates the false-positive and false-negative PET findings. Patients with head and neck cancer who are referred to tertiary care centers commonly arrive with cross-sectional images obtained at other institutions. Reinterpretation of these studies by dedicated radiologists frequently leads to changes in findings, which alter treatment and affect prognosis.

CT and MR imaging of the buccal space: normal anatomy and abnormalities

The buccal space is an anatomical compartment lying anterior to the masticator space and lateral to the buccinator muscle. Since the major purpose of imaging is to define the likely anatomic origin and also the extent of a given lesion, thorough knowledge of the normal anatomy of the buccal space is essential, and this knowledge can aid the physician in narrowing down the list of possible maladies on the differential diagnosis. We illustrate here in this paper the important anatomic landmarks and typical pathologic conditions of the buccal space such as the developmental lesions and the neoplastic lesions. Knowledge of the expected pathologic conditions is useful for the radiologist when interpreting facial CT and MR images.

Diagnostic value of FDG PET and salivary gland scintigraphy for parotid tumors

PURPOSE

The purpose of this study was to examine the diagnostic value of the combination of F-18 fluorodeoxyglucose (FDG) PET and Tc-99m pertechnetate salivary gland scintigraphy in parotid tumors.

MATERIALS AND METHODS

Seventy-two patients with benign parotid gland tumors (n = 52), malignant parotid tumors (n = 12), and inflammation (n = 8) underwent both FDG PET and salivary gland scintigraphy within 1 week, and 66 of the patients also underwent gallium scintigraphy. All patients were negative on their first fine-needle aspiration (FNA).

RESULTS

Malignant parotid tumors showed significantly higher FDG uptake (standard uptake values [SUVs]) than both benign tumors and inflammation, except in Warthin's tumor (5.82 +/- 3.95 vs. 2.07 +/- 1.33; P <0.01). Although the SUV values of Warthin's tumor and malignant parotid tumors overlapped somewhat, Warthin's tumor did demonstrate increased radiotracer uptake, and it was reliably distinguished from other parotid gland tumors by the use of salivary gland scintigraphy. Considering a SUV value >3 as being positive for malignancy and excluding Warthin's tumor on the basis of salivary gland scintigraphy, sensitivity and specificity of FDG PET were 75% and 80%, respectively. These results were superior to those of gallium scintigraphy (58% and 72%, respectively).

CONCLUSIONS

Although the diagnostic value of FDG PET in the differentiation of malignant from benign parotid gland tumors was limited because of the high FDG uptake in some benign tumors, and particularly pleomorphic adenomas, combining salivary gland scintigraphy with FDG PET may help to negate this drawback, and this combination may be a more promising approach for differentiation of various parotid gland tumors in patients compared with nondiagnostic needle aspiration.