Potential Theranostic Role of Bone Marrow Glucose Metabolism on Baseline 18F-FDG PET/CT in Metastatic Melanoma

TOTHEEDITOR:Wewere interested to read the recent article by Foster et al. (1) describing early experience of avb6 PET/CT imaging of the lungs after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Wewould like to point out that the suggestion that theavb6 uptake in lung regions affected by SARS-CoV-2 is 3 times that which we reported previously for fibrotic lung (2) may be misleading. Foster et al. report an SUVmax of approximately 3.0 in SARS-CoV-2 and compare this with our reported value of 1.03 in subjects with idiopathic pulmonary fibrosis. However, our value is the SUVmean averaged over the whole lung volume, which will be systematically lower than SUVmax. Although we did not perform an equivalent analysis, and the color scale in our example images (Lukey et al. (2), Fig. 1) was chosen to enable comparison with the healthy participants rather than visualization of the maximal value, we can confirm qualitatively that localized SUVs of 3.0 or more were observed widely in the fibrotic lung regions in our study. Clearly, more data and appropriate analyses (3) would be needed to make a valid quantitative comparison, particularly given the potential influence of tissue fraction (4) and the known (micro)-vascular component of the SARS-CoV-2 disease mechanism (5), which might influence the blood signal. We look forward to seeing more results from this important work in due course.