Differentiation of Kawasaki disease from other causes of fever and cervical lymphadenopathy : a diagnostic scoring system using contrast-enhanced CT

概要

Kawasaki disease (KD) is an acute systemic vasculitis that occurs in childhood and can affect the coronary arteries. Prompt initiation of therapy with IV immunoglobulin has led to the reduced frequency of coronary artery aneurysms, from 25% to 4% [1]. Among principal clinical features, cervical lymphadenopathy is the least common, occurring in 42–75% of cases [2]. However, in 9– 23% of patients with KD, fever and cervical lymphadenopathy may be the most notable initial clinical findings at admission, leading to clinical diagnosis of bacterial cervical lymphadenitis and treatment with antibiotics [3]. Although sonography is useful for the routine assessment of cervical lymphadenopathy, it may be challenging to differentiate KD from other causes of fever and cervical lymphadenopathy on the basis of sonography findings alone [4]. Therefore, in some cases, contrast- enhanced CT (CECT) of the neck is necessary to investigate the cause of resistance to antibiotic therapy [5]. This study aimed to determine characteristic CECT findings of the neck in patients with KD and to develop a diagnostic scoring system that facilitates the diagnosis of KD versus other causes of fever and cervical lymphadenopathy.

Two radiologists evaluated CECT images of 37 patients with KD and 92 patients without KD who had febrile cervical lymphadenopathy, first independently and then in consensus. Significant findings in CECT images were evaluated through cervical edema and lymph node scores. CT attenuation of the nodal low-attenuation area and its ratio to the CT attenuation of the trapezius muscle were measured. On the basis of these indexes, a diagnostic scoring system was developed to differentiate between patients with and without KD. Its diagnostic performance was determined using ROC curve analysis. Retropharyngeal edema, lateral cervical edema, nasopharyngeal wall edema, level IIA lymphadenopathy, and retropharyngeal lymphadenopathy were more common in patients with KD than in patients without KD (p < 0.001, < 0.001, < 0.001, 0.003, and 0.028, respectively). Level VB lymphadenopathy was more common in patients without KD (p = 0.013), and the presence of nodal low-attenuation areas with lower attenuation indexes (attenuation of nodal low-attenuation area ≤ 50 HU, or ratio of attenuation of nodal low-attenuation area to trapezius muscle attenuation ≤ 0.7) was specific to patients without KD. In cases of higher attenuation indexes and cervical edema and lymph node scores of 4 or higher, sensitivity, specificity, and accuracy of the diagnostic scoring system were 86% (32/37), 86% (79/92), and 86% (111/129), respectively, for diagnosing KD.

The proposed diagnostic scoring system was useful in differentiating between patients with and without KD.

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