18F FDG Uptake to Assess Eosinophilic Inflammation in Asthma: Would SUV at Late Imaging Be Relevant?
TO THE EDITOR: We read with great interest the article by Harris et al. (1) demonstrating that 18F FDG uptake rate (Ki, min21) precisely predicts the degree of eosinophilic inflammatory response in the lungs of asthmatic patients undergoing an allergen challenge. Any result in this field is of tremendous interest because it may provide complementary quantitative insight into the severity of the inflammatory response in asthma and thus may be used for testing innovative therapies. The study of Harris et al. used the gold standard graphical method of Patlak et al. involving dynamic acquisition until about 60 min after injection and venous blood sampling (2,3) allowing determination of the ratio of Ki in allergen challenged and diluent control lobe, which was compared with that of eosinophil counts obtained with bronchoalveolar lavage. Because we have proposed an adapted estimation of 18F FDG metabolism that can be used for lung examination in clinical practice (4) we suggest that the standardized uptake value (SUV) assessed at late imaging may be used to estimate eosinophilic inflammation in asthma. Let us consider SUV at a late imaging time of t 60 min:
The Journal of Nuclear Medicine