Studying the metabolic activity of red bone marrow by means of FDG-PET: the need for a standardization.

摘要

We read with interest the paper by Fan et al. , and we agree that a deeper understanding of the pathophysiology of red marrow could lead to a better knowledge of its involvement in neoplastic processes and therefore help in the clinical management and prognosis assessment. Because of its easiness, the measurement of red marrow activity by means of fluoro-D-deoxyglucose (FDG) positron emission tomography (PET) could be of help to this purpose, and the standardized uptake value (SUV) represents a widespread easily reproducible parameter for glucose uptake. The work by Fan et al. indeed describes the role of FDG-PET in the definition of changes in the metabolic activity of red marrow with aging. The authors gave a valid contribution to the search for a standardization of bone marrow uptake by demonstrating the higher stability of axial red bone marrow with advancing age compared with the peripheral bone marrow. These findings confirm the validity of the choice made by other groups [2, 3]. However, some aspects of their findings probably need a further explanation to allow a more reproducible conclusion.First of all, the method of calculating the SUV should be as homogeneous as possible; on this subject, methods used by the authors seem not to be so clearly defined.The way of drawing regions of interest (ROIs) on the considered transverse slices are not clearly specified; the use of noncomputed tomography-fused images for manual drawing of ROIs "could be misleading because of the possibility of including structures other than the bone marrow. Moreover, the authors give no information on the use of anthropometric factors in SUV correction.In this study, the authors calculated SUV values on three consecutive transverse slices on the 12th thoracic and the fifth lumbar vertebra; then the maximal values were averaged.