Normal size of retropharyngeal lymph nodes in children on three dimensional magnetic resonance imaging.

Background: Age-specific normal measurements or specific size criteria for retropharyngeal lymph nodes in children have not been defined.

Objective: We aimed to determine the normal measurements and distribution of retropharyngeal lymph nodes on three-dimensional magnetic resonance imaging (3-D MRI) in children.

Materials and methods: In this retrospective study, we included 440 patients (213 girls) aged 0-17 years who were admitted to our center with seizures and headaches and underwent brain and neck MRI with T2-sampling perfection with application-optimized contrasts using different flip angle evolution sequences. We evaluated the number, laterality, and level distribution of lateral and medial group lymph nodes according to the skull base-cervical vertebrae. For both groups, we measured the short and long diameters of the largest lymph node in the axial plane and the craniocaudal diameter in the sagittal plane. The short/long diameter ratios and volumes were determined.

Results: In 433 cases (98%), 1,554 lateral group lymph nodes were detected. Medial group lymph nodes were less common (7%). The lateral group was mostly bilateral, while the medial group was unilateral. Lateral group lymph nodes extended from the skull base-first cervical (C1) vertebral level to the C4, while the medial group extended from the C2 vertebral level to the C4. The mean axial short axis, axial long axis, and sagittal long axis diameters were 5.8 mm, 10.1 mm, and 15.5 mm for the lateral group and 3.8 mm, 7.6 mm, and 10.8 mm for the medial group, respectively.

Conclusion: The findings of the study show that normally retropharyngeal lymph nodes are frequently seen in children and provide valuable information for lateral and medial lymph nodes depending on age.