Abstract
Conclusions: Retropharyngeal abscess-like lesions are occasionally seen in computed tomography (CT) imaging of patients with
Kawasaki disease (KD) and these patients often undergo unnecessary surgery. We could distinguish the lesions from true
abscesses by measuring their Hounsfield unit values (HUs). Objective: To distinguish the retropharyngeal abscess-like lesions
from true abscesses without any surgical procedure. Methods: We investigated six cases of KD showing such lesions on CTs,
both with and without contrast enhancement (CE). We measured the HUs of those lesions and compared them with those of
10 true abscesses as controls. Results: Abscess-like lesions of KD were well enhanced by CE, whereas abscesses showed virtually
no enhancement. The mean HU in the six KD cases was 20.0 ± 4.65 (mean ± SD) on plain CTs and 35.6 ± 4.49 on contrast
CTs. In abscesses, it was 30.3 ± 4.42 on plain CTs and 30.3 ± 3.57 on contrast CTs. The difference in HU values [(HU on
contrast CT) – (HU on plain CT)] was defined as DHU. The mean DHU was 15.6 ± 5.36 in the six KD lesions and 0.0 ± 2.93 in
abscesses, with statistical significance of p < 0.0001 by Student’s t test. Thus, DHU value may potentially be a useful parameter
for their distinction.