Tc-99m HMPAO Labeled WBC Scan for the Detection of Myocarditis in Different Phases of Kawasaki Disease

Myocardial imaging with Tc-99m HMPAO WBC was used to detect myocarditis of Kawasaki disease in 103 infants and children (66 boys and 37 girls, mean age 3 years and 4 months). The clinical course of Kawasaki disease may be divided into three phases, from the onset of illness onset until all clinical symptoms and signs have disappeared. Twenty-four hour myocardial imaging was performed in anterior, LAO, and left lateral views. The grading system was as follows: score 0 less than bone uptake; 1 = bone uptake; 2 greater than bone uptake; and 3 greater than or equal to liver uptake. If the score was greater than or equal to 2, significant myocarditis was considered. The appearing ratio of myocarditis was 57% (13/23) in the first phase; 65% (15/23) in the second phase; 54% (31/57) in the third phase. No significant difference was demonstrated among the three groups of patients (P greater than 0.1, by Chi-square test). In conclusion, an occult myocarditis may continue in all three phases of Kawasaki disease, even if the clinical symptoms and signs had improved by the evidence of Tc-99m HMPAO labeled WBC scan to avoid advanced cardiac complication.