Objective: We report use of F-18 Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) scan in children with rheumatic heart disease (RHD), to see if it helps in diagnosis of carditis, since FDG, a glucose analogue is taken up by the inflammatory cells.

Methods: 36 children (age 6-17 years, mean 10.2 years) with significant rheumatic mitral regurgitation (MR) underwent FDG-PET scanning of the heart after fasting for 6 hours. They were divided into two groups based on Jones criteria – active carditis (AC) and non active. 12 age and sex matched children with normal hearts, undergoing FDG-PET scan for other reasons, served as controls. The primary end point was to compare the pattern of FDG-PET scanning in AC, chronic RHD and in controls.

Results: AC was present in 19/36 cases, 17 were not active. Diffuse FDG uptake was seen in 14/19 cases with AC, all 17 non active cases and 12/12 controls. 5 cases with AC did not show any uptake. Therefore, no uptake pattern on FDG PET scan had a sensitivity of 26% and positive predictive value of 100% for diagnosing AC.

Conclusion: FDG PET scan in children shows diffuse myocardial uptake in cases with RHD, similar to that seen in controls. In 1/4th of AC cases, no myocardial uptake is seen. This finding may be related to the inability of myocytes to shift from fatty acids to glucose substrate for their metabolism. F -18 FDG PET may help to diagnose AC in equivocal situations, since its positive predictive value is high.