Fluorodeoxyglucose Uptake in Lipomatous Hypertrophy of the Interatrial Septum is Not Likely Related to Brown Adipose Tissue

Abstract

Dear Editor, We read with interest the article by Kamaleshwaran et al.[1] and found that our previous publication[2] was cited twice, that is, (1) as a reference for the prevalence of lipomatous hypertrophy of the interatrial septum (LHIS) on echocardiography and (2) for the concept that inflammation is the cause of increased fluorodeoxyglucose (FDG) uptake in LHIS. First, our paper is not a reference for the prevalence of LHIS on echocardiography. Our paper: “FDG uptake in LHIS is not likely related to brown adipose tissue (BAT)” should have been cited as a report suggesting increased FDG uptake in LHIS is not likely related to BAT, as its title suggests. Dual-time point imaging may be useful to help distinguish FDG uptake associated with benign versus malignant etiologies;[3] However, it should be remembered that no imaging test or criteria are 100% sensitive/specific. Washout of FDG does not necessarily confirm an inflammatory etiology. Indeed, 5 of 18 benign lesions in reference 3 did not show FDG washout on delayed imaging. In particular, 3 of these 5 benign lesions showed an increase in FDG avidity with time that is, 10%, 13% and 27%. We have certainly seen cases where inflammatory lesions showed an increase in FDG uptake on delayed imaging. We hope an amendment to the paper by Kamaleshwaran et al.[1] can be published to prevent a misconception from developing. Specifically, our paper is not a reference for the prevalence of LHIS on echocardiography. Further, we did not prove that inflammation is the cause of increased FDG uptake in LHIS but suggested it only as a “possible” alternative cause. At the same time, Kamaleshwaran et al.'s paper does not disprove it. As we mentioned in our previous paper, we would like to re-emphasize that a larger sample size would be needed to show whether inflammation is indeed the cause of increased FDG uptake associated with LHIS or not. Our paper suggested FDG uptake in LHIS is not likely related to BAT (we were likely the first to suggest this) and our paper is a reference for this. Thank you for your help in this matter. We would sincerely appreciate that the reference to our paper is correct.