Y.Y.P. Lee

Imaging of salivary gland tumours

Salivary gland neoplasms account for <3% of all tumors. Most of them are benign and parotid gland is the commonest site. As a general rule, the smaller the involved salivary gland, the higher is the possibility of the tumor being malignant. The role of imaging in assessment of salivary gland tumour is to define intra-glandular vs. extra-glandular location, detect malignant features, assess local extension and invasion, detect nodal metastases and systemic involvement. Image guided fine needle aspiration cytology provides a safe means to obtain cytological confirmation. For lesions in the superficial parotid and submandibular gland, ultrasound is an ideal tool for initial assessment. These are superficial structures accessible by high resolution ultrasound and FNAC which provides excellent resolution and tissue characterization without a radiation hazard. Nodal involvement can also be assessed. If deep tissue extension is suspected or malignancy confirmed on cytology, an MRI or CT is mandatory to evaluate tumour extent, local invasion and perineural spread. For all tumours in the sublingual gland, MRI should be performed as the risk of malignancy is high. For lesions of the deep lobe of parotid gland and the minor salivary glands, MRI and CT are the modalities of choice. Ultrasound has limited visualization of the deep lobe of parotid gland which is obscured by the mandible. Minor salivary gland lesions in the mucosa of oral cavity, pharynx and tracheo-bronchial tree, are also not accessible by conventional ultrasound. Recent study suggests that MR spectroscopy may differentiate malignant and benign salivary gland tumours as well as distinguishing Warthins tumor from pleomorphic adenoma. However, its role in clinical practice is not well established. Similarly, the role of nuclear medicine and PET scan, in imaging of parotid masses is limited. Sialography is used to delineate the salivary ductal system and has limited role in assessment of tumour extent.

Shear wave elastography of focal salivary gland lesions: preliminary experience in a routine head and neck US clinic

Book synopsis: New Materialisms rethinks the relevance of materialist philosophy in the midst of a world shaped by forces such as digital and biotechnologies, global warming, global capital, and population flows. Moving away from modes of inquiry that have prioritized the study of consciousness and subjectivity over matter, the essays in this collection show that any account of experience, agency, and political action demands renewed attention to the urgent issues of our own material existence and our environment. The editors propose “new materialisms” as a way to take matter seriously without falling into the conceptual dualism that posits an opposition between matter and thought, materialism and idealism, and body and mind. They locate new materialisms within post-humanist discourses, explaining that new materialist philosophies do not privilege human bodies, but rather view human bodies as one of many bodies, or agential materialities, in the world. By revealing how emerging accounts of matter, materiality, and corporeality are combining with developments in science and technology to demand radically new conceptions of nature, agency, and social and political relationships, New Materialisms makes a significant contribution to the recent resurgence of interest in phenomenology and materialist philosophy in the humanities.

Ultrasound of malignant cervical lymph nodes

Abstract Malignant lymph nodes in the neck include metastases and lymphoma. Cervical nodal metastases are common in patients with head and neck cancers, and their assessment is important as it affects treatment planning and prognosis. Neck nodes are also a common site of lymphomatous involvement and an accurate diagnosis is essential as its treatment differs from other causes of neck lymphadenopathy. On ultrasound, grey scale sonography helps to evaluate nodal morphology, whilst power Doppler sonography is used to assess the vascular pattern. Grey scale sonographic features that help to identify metastatic and lymphomatous lymph nodes include size, shape and internal architecture (loss of hilar architecture, presence of intranodal necrosis and calcification). Soft tissue oedema and nodal matting are additional grey scale features seen in tuberculous nodes or in nodes that have been previously irradiated. Power Doppler sonography evaluates the vascular pattern of nodes and helps to identify the malignant nodes. In addition, serial monitoring of nodal size and vascularity are useful features in the assessment of treatment response.

Imaging of cystic or cyst-like neck masses.

Cystic or cyst-like neck masses form a unique category within head and neck radiology with unique differential diagnoses. The precise anatomical location and imaging appearances are important for accurate diagnosis and formulating the differential diagnoses of cystic lesions in the neck. In vast majority of cases ultrasound, sometimes supplemented by fine-needle aspiration cytology (FNAC), is adequate for pre-treatment assessment. For large, deep-seated lesions assessment using magnetic resonance imaging (MRI) or computed tomography (CT) often provides useful supplementary information. Radiologists should be aware of imaging findings of common cystic neck masses to help in their appropriate management.

Review of ultrasonography of malignant neck nodes: greyscale, Doppler, contrast enhancement and elastography

Abstract Assessment of neck lymph nodes is essential in patients with head and neck cancers for predicting the patient’s prognosis and selecting the appropriate treatment. Ultrasonography is a useful imaging tool in the assessment of neck lymph nodes. Greyscale ultrasonography assesses the size, distribution, and internal architecture of lymph nodes. Doppler ultrasonography evaluates the intranodal vascular pattern and resistance of lymph nodes. Contrast-enhanced ultrasonography provides information on lymph node parenchymal perfusion. Elastography allows qualitative and quantitative assessment of lymph node stiffness. This article reviews the value of greyscale, Doppler and contrast-enhanced ultrasonography as well as elastography in the assessment of malignant nodes in the neck.

Ultrasound elastography in the head and neck. Part II. Accuracy for malignancy

Abstract Ultrasound elastography (USE) describes a variety of ultrasound-based imaging techniques that measure tissue stiffness properties, and is currently under intense investigation for tissue characterization in several anatomic sites. This article summarizes the evidence regarding the accuracy of USE for malignancy in the head and neck. Currently, most published data pertains to small pilot studies with varied methodologies. Encouragingly, most studies have documented promising results for USE in terms of high accuracy for malignancy in thyroid nodules and cervical lymph nodes, which have surpassed conventional sonographic criteria. However, a minority of studies have documented opposite findings. USE seems to be suboptimal for salivary malignancies, and some evidence suggests that USE does not provide useful diagnostic information compared with conventional ultrasonography for miscellaneous neck masses. Further larger studies are required to validate these findings although, in view of the predominance of highly optimistic results for thyroid nodules and cervical lymph nodes, USE may become a useful ancillary technique in the routine diagnostic work-up of lesions in these tissues in the near future.

Tuberculosis in the head and neck: a forgotten differential diagnosis

The aim of the present review is to illustrate the pathogenesis and imaging findings of tuberculosis in specific head and neck regions to avoid pitfalls in diagnosis. It is imperative to be aware of, and provide an early diagnosis for, extra-pulmonary tubercular lesions in the head and neck. A high index of suspicion combined with an appropriate clinical setting serves as an important background to diagnose tubercular lesions in the head and neck region and differentiate them from malignancy and other disease entities. Early diagnosis and treatment can prevent irreversible and debilitating complications and mortality from disseminated tuberculosis.

Ultrasound elastography in the head and neck. Part I. Basic principles and practical aspects

Abstract Ultrasound elastography (USE) is a rapidly developing field of imaging that measures and displays tissue elasticity or stiffness properties using ultrasound. In recent years, real-time USE modes have appeared on commercially available clinical ultrasound machines, stimulating an explosion of research into potential oncologic and non-oncologic clinical applications of USE. Preliminary evidence suggests that USE can differentiate benign and malignant conditions accurately in several different tissues. This article presents an overview of the basic principles of different USE technologies that are currently under investigation in the head and neck region. In addition, more practical aspects pertaining to the optimal performance of USE at this site are discussed.

A pilot study evaluating real-time shear wave ultrasound elastography of miscellaneous non-nodal neck masses in a routine head and neck ultrasound clinic.

A pilot study was performed to evaluate shear wave ultrasound elastography (SWE) for miscellaneous non-nodal/salivary/thyroid neck lesions. Forty-six lesions undergoing conventional sonography also underwent SWE. Elastic moduli from the stiffest areas in lesions were correlated with diagnosis. Forty lesions were benign (9 lipomas, 8 lymphatic/venous vascular malformations, 7 thyroglossal duct cysts, 4 branchial cleft cysts, 4 abscesses/phlegmons, 3 neurogenic tumors and 1 each of paraganglioma, sebaceous cyst, pseudotumor, hypertrophic scar, ranula) and 6 were malignant (1 malignant fibrous histiocytoma, 2 primary squamous cell carcinomas and 3 intramuscular metastases [2 squamous cell carcinomas, 1 malignant melanoma]).Median stiffness of malignant lesions (226.4 kPa, range 55.6 to 300.0) was higher than benign lesions (28.3 kPa, range 4.0 to 300.0) (p < 0.001). SWE cut-off with highest accuracy (174.4 kPa) achieved 83.3% sensitivity and 97.5% specificity, and the cut-off with 100% sensitivity (55.6 kPa) achieved 75% specificity. All malignant lesions were suspected on conventional sonography. The preliminary data indicate that SWE is feasible for miscellaneous neck lesions. SWE would not have altered management in terms of detecting undisclosed malignancies, although as a quantitative technique, it may increase the diagnostic confidence of less experienced operators performing head and neck ultrasound.

Current role of radionuclide imaging in differentiated thyroid cancer.

Abstract Nuclear medicine plays an integral role in the management of differentiated thyroid cancer. This editorial aims to provide a summary of the current role of radionuclide imaging, including whole body iodine scan and fluorodeoxyglucose (FDG)-positron emission tomography (PET), in the diagnostic work-up and follow-up of patients with thyroid cancer.