The role of 18F fluorodeoxyglucose positron emission tomography (18F-FDG-PET) in children with rheumatic carditis and chronic rheumatic heart disease.

BACKGROUND We report the use of positron emission tomography (PET) using 18F-FDG for the diagnosis of carditis in children with rheumatic heart disease (RHD). MATERIAL AND METHODS Thirty-six children aged 6-17 years (seventeen males and nineteen females) with isolated rheumatic significant mitral regurgitation (MR) underwent FDG-PET scanning of the heart after fasting for 6 h within a period of 2 years. They were divided into two groups based on Jones criteria - acute rheumatic carditis and chronic RHD. Age- and gender-matched twelve children who underwent whole body ¹⁸F-FDG-PET scan for routine PET scan for oncological evaluation was taken as controls. Nineteen patients had active carditis and 17 were chronic RHD cases. RESULTS All 12 controls and all 17 cases with chronic RHD with MR showed diffuse uptake pattern. Of the 19 active cases, 14 showed ¹⁸F-FDG uptake in the myocardium, 5 did not show any uptake. Thus the finding of no uptake pattern on ¹⁸F-FDG-PET scan had a sensitivity of 26% but positive predictive value of 100% for acute carditis cases. This study describes the ¹⁸F-FDG-PET uptake pattern in children with RHD and in 12 age-matched control subjects in the fasting state. Those with chronic RHD with MR showed diffuse myocardial uptake pattern similar to that of the control group. Patients with active carditis showed mixed results; the majority showed diffuse uptake pattern. CONCLUSION In view of its poor sensitivity, ¹⁸F-FDG-PET is not recommended as a routine imaging modality for the diagnosis of rheumatic carditis.