FLEX February 2024

Stern et al

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quality is highly dependent on sonographic technique, ultrasound is best performed by sonographers with experience scanning children, and may require the interpreting physician to be present during at least part of the examination. Ultrasound is also limited in its ability to accurately diagnosis the specific histology of masses in children by imaging characteristics alone. There is overlap in the imaging features of many congenital and acquired lesions. For example, complex, previously infected thyroglossal duct cysts may demonstrate heterogenous or intermediate echogenicity mimicking other midline lesions such as dermoid cysts (most commonly), epidermal inclusion cysts, vellus hair cysts, lymph nodes, or scar tissue ( Fig. 3 ). 10 Although calcifications may be readily identified on ultrasound by characteristic posterior acoustic shadowing, ultrasound does not visualize bony structures well. Also, as a result of posterior acoustic shadowing, which occurs because sound waves cannot penetrate calcifications, evaluation of structures deep to large calcifications is limited. Computed Tomography MDCT should be performed helically with acquisition of images in the axial plane in soft tissue and bone algorithms, and reconstructions in coronal and sagittal planes. The technique should be optimized to provide the lowest radiation dose possible while acquiring diagnostic quality images, according to the ALARA (as low as reasonably achievable) principle, utilizing age-stratified pediatric protocols. Intravenous contrast

Fig. 3. Transverse ultrasound images of midline neck masses in 4 different children, all of whom had a normal thyroid gland. All 4 of these lesions were surgically removed. ( A – C ) Pathology-proven thyroglossal duct cysts. ( D ) Dermoid cyst.

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