Application Of Ultrasound In Deep Cervical And Mesenteric Lymph Nodes Of Normal Children

BackgroundLymph node is an important defensive organ of human body. Many diseases such as inflammation, tuberculosis, metastasis and lymphoma may lead to lymphadenopathy. Evaluating the status of the lymph nodes (LNs) has very important value for clinic to diagnose and treat disease. Nowadays, Ultrasound (US) has been used widely to assess superficial and abdominal LNs, because it is convenient to operation, nonradioactive, cheap and accurate to diagnose diseases.It is well accepted that the structure of normal LNs changes with the increasing age, and LNs in different parts of body are also not the same, especially children's LNs which have great variety with physiological growth. The diagnostic criteria for children's lymphadenopathy based on for adult's is not completely accuracy. Although there are ultrasonographic reports about normal adult's LNs, there aren't systematically reports about children's normal deep cervical lymph nodes (DCLNs) and mesenteric lymph nodes(MLNs).DCLNs and MLNs are the frequent regions of children with disease. US has been implemented with increasing frequency for assessment of these LNs as an adjuvant diagnostic tool. The purpose of our study is to explore ultrasonographic features and the changes with the increasing age of normal children's DCLNs and MLNs and to define reference value of enlarged DCLNs and MLNs.Materials and methodsBetween February 2005 and March 2006, health volunteers, outpatients and inpatients whose age range from 1 to 15 years old with normal or enlarged DCLNs and MLNs, which were proved by clinical findings and follow-up. A total of 92 normal children (46 male, 46 female) were included in our superficial DCLNs study (normal group), and all LNs were divided into superior or inferior groups by cricoid cartilage (where the omohyoid muscle crosses the internal jugular vein), whereas the LNs of enlarged group (47 children) were located in superior group. A total of 84 normal children (42 male, 42 female) were included in our deep MLNs study (normal group) and the enlarged group was 30 children. Normal children were classified into three age groups: 1-5 years, 6-10 years and 11-15 years. High-resolution US investigations were performed on all children. For each individual child, the largest lymph node of cervical superior and inferior group and/or the mesenteric lymph nodes (shortest diameter larger than 4mm) utilizing the graded compression US technique, considered as the node with the largest transverse diameter, were documented in the plane that demonstrated the largest(L) and shortest(S). Morphology comprised evaluation of nodal shape by measuring the long to short axis ratio (L/S), margin, numbers, US hilum, interior echo-texture and confluence were assessed. Assessment of intranodal vascularity by color Doppler flow imaging (CDFI) was based on flow signal, which was divided into four degrees from no blood flow signal to abundant signal. Pulse Doppler was performed in the DCLNs to measure resistive index (RI) and pulsative index (PI).ResultsThe largest LNs of cervical superior and inferior group in normal children demonstrated central echogenic hilus, distinct and regular margin. The number of LNs in superior group was more than in inferior group, and diminished gradually from higher to lower cervical region. The LNs of superior group commonly appeared as oval shape and inferior group as flat shape. The L/S ratio of DCLNs in the majority was greater than 2, and the L/S ratio of inferior group was significantly larger than that of superior group (P<0.01). In normal DCLNs group, the short diameter was not statistically significantbetween the right and the left (P>0.05), and P>0.05 between the boys and the girls, but P<0.01 between the superior and the inferior group. The short diameter of the cervical superior and inferior group was not statistically significant between the 1-5 years and 6-10 years group (P>0.05), but P<0.01 between the 11-15 years group and the two younger groups. The normal ceiling reference value (95% confidence interval) of the superior group LNs: 1-10 years children about 9.5mm, 11-15 years children about 9.0mm, and of the inferior group LNs: 1-10 years children about 4.0mm, 11-15 years children about 3.5mm. The color Doppler signal was detected in the majority of normal DCLNs, and the superior group LNs tended to have hypervascularization than did the inferior group (P<0.01).The flow resistance was not statistically significant between the superior and inferior group LNs (P>0.05).MLNs were detected in 67% of the normal group, the majority of them were iso- or hypoechoic, and about 43% of the MLNs showed central echogenic areas. The margin of all MLNs was distinct, and the majority was oval-shaped. The L/S ratio of 78% MLNs was greater than 2. The number of MLNs in normal children was not statistically significant between boys and girls (P>0.05). The detection rate of different age group MLNs: P>0.05 between the 1-5 years group and the 6-10 years group, P<0.05 between the 11-15 years group and the two younger groups. The MLNs in normal children were mainly located in right lateral and/or anterior to the inferior vena cava and ileocecal region, which distributed around mesenteric vessel. The average number of MLN in the normal group was 1.7, and the short diameter ≤8 was in 96% LNs. About 57% MLNs of the normal group appeared avascular on CDFI, the majority of the rest normal children's MLNs appeared a single artery penetrating to the capsule, and the minority appeared several arteries penetrating to the capsule.All largest enlarged DCLNs were located in superior group. High-resolution US findings: The blurring of outer margin was detected in the partial LNs, irregular margins in 36% of nodes, indistinct hilum and inhomogenous echo-texture in 29% of nodes, including internal anechoic area with necrosis in 8% of nodes. The long and short diameter of enlarged DCLNs was significantly larger than that of normal nodes (P<0.01), and present with L/S≤2 (in 59% of nodes) in higher frequency than in normal groupLNs (P<0.01). The enlarged group of DCLNs tended to have hypervascularization than did the normal group (P<0.01), and irregular vascular territory was shown in some enlarged LNs. The flow resistance (RI and PI) of DCLNs was statistically lower in the enlarged group than in the normal group (P<0.05 and P<0.01). Using a threshold of short diameter >10mm to diagnose enlarged DCLNs of superior group, the sensitivity, specificity and accuracy was 96.4%, 96.2%, and 96.3%. It was the most important ultrasonic parameter than others.The number of iso- and hypoechoic MLNs was more in enlarged group than in normal group, but there was not statistically significant. The L/S ratio ≤2 was in 53% MLNs. The number of MLNs(average 4.5) in enlarged group was apparently greater than normal group (P<0.01). In partial patients, several MLNs in the left to inferior vena cava and below the umbilicus where there were rarely MLN in normal children were detected. The color Doppler flow signal of MLNs in enlarged group was significantly hypervasculized than that in normal group (P<0.01). Using a threshold of short diameter >8mm to diagnose children's enlarged MLNs, the sensitivity, specificity and accuracy was 26.7%, 94.0%, and 76.3%. Using the diagnostic criteria of partial enlarged MLNs in children-three or more MLNs >4mm-would yield a sensitivity of 96.2%, specificity of 75.0% and accuracy of 80.0%.Conclusions1. Our study first time demonstrates that it can be define as reference value to diagnose enlarged LNs that superior DCLNs >9.5mm, inferior DCLNs >4.0mm and MLNs >8.0mm. The sizes of DCLNs and MLNs gradually diminish with the increasing age in normal children.2. Initial study shows it is the most valuable diagnostic criteria by measuring short diameter >10mm of the largest DCLN to distinguish the normal LN from enlarged LNs of superior group, and the sensitivity and specificity are all high. Using a threshold of short diameter >8mm to diagnose children's enlarged MLNs, the specificity is very high, but the sensitivity is low. Using the diagnostic criteria of partial enlarged MLNs in children-three or more MLNs >4mm-would yield a highersensitivity. In addition, we should also consider the location of the MLNs. 3. The number and size of DCLNs both diminish gradually from superior to inferior cervical region in each normal child, and the largest LNs of cervical superior and inferior group commonly demonstrate central echogenic hilus, distinct and regular margin. The MLNs usually have a iso- or hypoechoic appearance in normal children, but partly MLNs demonstrate echogenic medulla of the node. The L/S ratio of DCLNs and MLNs in normal children is frequently greater than 2. The vascularization of superior DCLNs is more hypervascularized compared with inferior DCLNs in normal children, but RI and PI have not significant difference between them.