CT analysis of retropharyngeal abnormality in Kawasaki disease

Abstract

Objective: To retrospectively compare the imaging characteristics of retropharyngeal density and associated findings for Kawasaki disease with those for non-Kawasaki disease, and identify the distinguishing features which aid the CT diagnosis of Kawasaki disease with retropharyngeal low density.

Materials and methods: Among the enhanced neck CT performed in children less than 8-years old with clinical presentation of fever and cervical lymphadenopathy over a 6-year period, only cases with retropharyngeal low density (RLD) were included in this study. The 56 cases of RLD were divided into two groups; group A included cases diagnosed as Kawasaki disease (n = 34) and group B included cases diagnosed as non-Kawasaki disease (n = 22). We evaluated the CT features including the thickness of RLD and its extent into the deep neck spaces, as well as soft tissue change in the adjacent structure. We also scored the extent of RLD into the deep neck spaces and the soft tissue changes in the adjacent structure.

Results: The thickness of RLD was greater in group A than in group B (group A, 6.0 ± 2.1; group B, 4.6 ± 1.5, p = 0.01). The score of the RLD extent into the deep neck spaces was significantly greater in group A than in group B (group A, 2.3 ± 1.3; group B, 0.8 ± 1.0, p < 0.01). Also, the score of the adjacent soft tissue changes was greater in group A than in group B (group A, 2.0 ± 1.1; group B, 1.0 ± 1.0, p < 0.01).

Conclusion: If children present with fever and cervical lymphadenopathy that display retropharyngeal low density with extension into more deep neck spaces as well as changes in more adjacent soft tissue, the possibility of Kawasaki disease should be considered.

Keywords: CT; Kawasaki disease; Retropharyngeal edema.

Fig. 1

Kawasaki disease in 6-year-old boy. CT images (A-C) show retropharyngeal low density without rim enhancement (arrows), which extends to right parapharyngeal, carotid, posterior and anterior cervical, as well as submandibular and perivertebral spaces (score: 6). In addition, there are multiple enlarged cervical lymph nodes and swelling of right sternocleidomastoid, as well as platysma muscles and subcutaneous tissue (score: 3). Retropharyngeal low density and associated soft tissue lesions are dramatically improved on follow-up CT after immunoglobulin therapy (D).

Fig. 2

Kawasaki disease in 5-year-old boy. A, B. CT demonstrates diffuse swelling of left sternocleidomastoid muscle (arrows), platysma muscles (long arrows), and infiltration of adjacent subcutaneous tissue layer (arrowheads) of left posterolateral neck (score: 3), in addition to retropharyngeal low density with extension to left deep cervical spaces (score: 3) and cervical lymphadenopathy.

Fig. 3

Infectious mononucleosis in 1-year-old boy. A, B. CT images show enlarged cervical lymph nodes in both neck and retropharyngeal low density without enhancing rim, which is not extended to deep neck space (score: 0). Adjacent soft tissue is not involved (score: 0). C. Retropharyngeal low density is improved on follow-up CT after antibiotic therapy.

Fig. 4

Lymphadenitis of undetermined etiology in 4-year-old boy. A, B. CT shows retropharyngeal low density extending to left parapharyngeal and carotid spaces (score: 2) and swollen left sternocleidomastoid muscle (score: 1), in addition to multiple enlarged cervical and retropharyngeal nodes, and palatine tonsil. C. Retropharyngeal low density is improved on follow-up CT after antibiotic therapy.