Medical expert of the article
New publications
Methods of ultrasound of lymph nodes of the neck
Last reviewed: 04.07.2025
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
The lymph nodes are assessed after their visualization, which is done by rotating the transducer and displaying the lymph node along the longitudinal axis. The maximum longitudinal dimension is divided in two by the perpendicular transverse dimension. The M/P ratio (the ratio of the maximum longitudinal to transverse dimensions) characterizes the shape of the lymph node. If it is less than 2, the node is spherical, which allows us to suspect its metastatic lesion. This criterion does not apply to nodes smaller than 1 cm, because the measurement error is too great. Metastases to lymph nodes smaller than 1 cm or larger than 4 cm are often non-spherical. Lymph nodes larger than 4 cm are suspicious by the length of the maximum dimension itself. Therefore, the M/P ratio is mainly used for lymph nodes with a maximum size of 1-2 cm, since there is an overlap between benign and malignant lymph nodes within this range.
When examining normal lymph nodes and lymph nodes affected by non-specific lymphadenitis, a hypoechoic cortex with a bright central echo in the hilum is determined. In metastatic lesions and in malignant lymphomas, in 50-80% of cases, there is no echo in the hilum. In malignant lymphoma, pronounced hypoechogenicity of the cortex is often determined, which can create the appearance of a pseudocyst. Metastases to the lymph nodes often have a complex echostructure due to regressive changes. Normally, lymph nodes are usually clearly defined, but in the presence of metastases, the boundaries become unclear.
For color duplex evaluation of lymph nodes, visualize intranodal vessels in color Doppler mode. Assess the degree and pattern of vascularization, then place a sample volume into the largest vessels and record the Doppler frequency spectrum. Angle correction is not necessary, since only the IP and SI parameters are of interest. In the case of squamous cell carcinoma metastases in lymph nodes, the resistance index is higher than in benign nodes. With SI greater than 0.8 and SI greater than 1.6, metastases are diagnosed with a sensitivity of about 55% and a specificity of 95%. A higher resistance index of lymph node metastases is a result of obstruction of peripheral vascular channels by tumor cells. Both malignant lymphoma and lymphadenitis are characterized by a low resistance index (SI < 0.8).
[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ], [ 7 ], [ 8 ], [ 9 ], [ 10 ]