Central hyperechogenicity of the hilum is reassuring of a benign lymph node, but a thin, hypoechoic hilum is suspicious of a pathologic lymph node that is infiltrated, inflamed, or malignant. Note the homogeneous appearance, well-defined borders, oval shape, size less than 8 mm, and central hyperechogenicity (arrow) relative to the cortex.Ībnormal lymph nodes are markedly hypoechoic with heterogeneous echotexture and change shape from oval to round ( Figures 33.5 and 33.6 ). Normal appearance of a cervical lymph node. Sequentially evaluate the upper, middle, and lower cervical nodes by sliding the transducer along the path of the internal jugular vein and common carotid artery, from the angle of the mandible to the junction of the internal jugular and subclavian veins. To scan cervical lymph nodes, start at the angle of the mandible with the transducer in a transverse orientation. Obtain images of parotid lymph nodes in transverse and longitudinal planes. Sweep laterally toward the angle of the mandible. Next, slide the transducer toward the submandibular area and orient the transducer parallel to the lower edge of the mandible with the ultrasound beam aimed superiorly toward the head. Start by scanning the neck in a transverse plane in the submental area. The head should be rotated to the contralateral side with the neck extended. A linear transducer maximizes resolution of soft tissue structures while giving an adequate depth of 6–10 cm to visualize lymph nodes, vessels, and pleura.įor optimal imaging of neck lymph nodes, position the patient supine with a pillow between the scapulae. This classification is distinct and does not replace the AJCC classification of cervical lymph nodes for cancer staging.Ī high-frequency, linear array ultrasound transducer (5–10 MHz) should be used to examine lymph nodes. A classification system of lymph nodes has been established to simplify ultrasound evaluation of the neck into eight regions ( Figure 33.3 ). Lymph nodes in the upper neck, specifically submandibular and upper cervical nodes, tend to be larger. Normal size of cervical nodes varies from 0.3 to 0.8 cm.
In general, normal lymph nodes are not larger than 0.7–1 cm, but the normal size of lymph nodes varies greatly from 0.5 to 2.0 cm depending on the location in the body. In the cervical chains, at least six nodes can be routinely identified. Normal distribution of lymph nodes of the head and neck is illustrated in Figure 33.2. The afferent lymphatic vessels bring lymph to the node through the cortex, while the efferent lymphatic vessel carries lymph away from the node exiting at the hilum. The hilum is where blood vessels enter and exit the lymph node. A lymph node is divided into an outer cortex and inner medulla and is surrounded by a fibrous capsule. Normal cross-sectional anatomy of a lymph node.
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