FLEX February 2024

Imaging of Pediatric Head and Neck Masses

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absent perfusion. 1,2,9 Any or all of these characteristics warrant consideration of fine needle aspiration (FNA) or biopsy ( Fig. 2 ). Necrosing lymph nodes tend to become increasingly hypoechoic and may initially show increased flow, but central flow may become decreased as the lymph node becomes more necrotic. As the lymph node degenerates to an abscess, the node becomes more anechoic centrally and can develop a hyperechoic rind that typically demonstrates increased flow. As the necrotic lymph node becomes more liquid in composition, there may be posterior acoustic enhancement/increased through trans mission, as is seen in cysts. Although an excellent screening tool, there are several limitations of ultrasound imaging. Deep structures of the neck, particularly the retropharyngeal soft tissues, are not well-visualized with ultrasound. The short length of the neck in infants and toddlers can present technical challenges for the sonographer, and patient motion can also make the acquisition of diagnostic-quality images challenging. As image Fig. 1. Normal lymph node on ultrasound. The image on the left demonstrates a normal reniform lymph node, with a central area of hyperechogenicity representing the fatty hilum. Color Doppler interrogation is shown in the image on the right, demonstrating vascular flow in the region of the hilum.

Fig. 2. Lymph node metastasis from papillary thyroid carcinoma on ultrasound.

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