RC 108 - Head and neck imaging: don't sell your ultrasound yet!
1. To understand the limitations of clinical examination.
2. To learn about the diagnostic approach to salivary glands.
3. To appreciate how to differentiate salivary gland pathology.
Ultrasound examination is often the first-line modality for imaging patients suspected of having salivary gland disease. Indications for this procedure include swelling with suspected sialadenitis or obstructing calculus, autoimmune diseases, palpable solitary or multiple masses suggestive of a benign or malignant neoplasm or floor of the mouth lesion. A thorough knowledge of the anatomy is crucial for reliable diagnosis of the pathology in this area. Although having considerable limitations (e.g. limited visualization of the deep lobe of the parotid gland) ultrasound can be very useful in selecting patients who require CT or MR imaging, provide biopsy guidance and, in some cases, gives the final diagnosis.
1. To become familiar with cervical ultrasound anatomy.
2. To learn about benign neck masses.
The neck constitutes a broad anatomic region, which has many aero-digestive, salivary glands, lymphatic, endocrine, neural and vascular structures. A good number of pathological conditions affecting these organs system are very well evaluated on high-resolution ultrasound. It is also very useful for ultrasound-guided needle aspiration for cytology, culture and hormone assay, ultrasound-guided core biopsy and molecular markers. The excellent tissue details and anatomical landmarks in the neck such as thyroid cartilage, trachea, strep muscles and neck vessels have made assessment of the neck masses a practical proposition. The neck masses are divided into two major groups: 1. thyroid neck masses; 2. non-thyroid neck masses. The non-thyroid neck masses include congenital masses, cervical masses, lymph node mass, salivary gland masses, nerve tumours, vascular masses, inflammatory masses, parasitic infestations, foreign body, benign and malignant neck tumours. High-resolution ultrasound is a multi-planner, non-invasive, cost-effective imaging modality which is having advantage of CT scan and MRI as the spatial resolution of ultrasound is much better than CT and MRI. The biggest advantage is that it is a dynamic modality which does not require any sedation or special preparation for evaluation of neck masses. The excellent tissue characterization of various structures in the neck on ultrasound clearly differentiate different pathology. The 3D ultrasound with multi-planner, panoramic and colour flow imaging increases the diagnostic accuracy.
1. To get acquainted with normal and abnormal findings.
2. To understand the patterns of nodal involvement.
3. To learn about technique of fine-needle aspiration.
There are several clinical scenarios where imaging is required to investigate the neck lymph nodes. 1. Imaging is indicated to integrate the clinical examination in the evaluation of unknown neck masses. In this clinical setting, the first task of imaging is to differentiate between non-nodal lesions and adenopathies. If the clinical examination cannot detect a primary neoplasm in the head and neck area, fine-needle aspiration (FNAC) is indicated. Ultrasound (US) is the technique of choice for the initial evaluation and for FNAC. 2. In case of acute/subacute neck infection with enlarged adenopathies, imaging is required to assess nodal changes (abscess), spread outside the lymph node capsule, potential extent into deep neck spaces, with great risk of mediastinal involvement. While US can be accurate in assessing superficial cervical node changes, CT with contrast agent is indicated to survey the deep spread of infections. 3. If a malignant neoplasm arising from the mucosa of the upper aerodigestive tract (UADT) is identified at clinical examination, imaging techniques are required to detect nodal metastases in the ipsilateral (if the primary tumour arises far from midline) and the contralateral neck. Besides detecting the abnormal node, extra-nodal spread and key vessels invasion (carotid, jugular vein) are key information to be acquired by imaging. US, MDCT and MR can be used: their greatest limitation is the low sensitivity for non-enlarged metastatic nodes. A different setting is the assessment of thyroid papillary carcinoma where microcalcifications inside even very small metastatic nodes can be detected by US.