Résumé
Diffuse bone marrow uptake of F-18-FDG-PET in cancer patients raises the problem of differential diagnosis between marrow involvement and stimulated marrow. In this study, we prospectively included, during a 1-year period, all cancer patients referred for initial staging showing an unexplained diffuse bone marrow uptake and explored consecutively by MRI. The abnormalities described on PET and the conclusion reached about disease status of bone marrow ("benign" or "malignant") were compared with corresponding MRI results, as well as clinical and biological findings pertinent when bone marrow activity is studied, marrow status considered by referring clinicians, and follow-up data. During 1 year, 60 patients had diffuse bone marrow uptake on F-18-FDG-PET, 26 underwent MRI examination and were finally included in the study. Results of PET and MRI were concordant in 24 cases (six "malignant" and 18 "benign") and two cases were discordant, judged "malignant" by MRI and "benign"by PET. The outcome after confrontation of MRI and PET, was "malignant" for one patient and "benign" for the other one. The final results, was "malignant" for seven patients and "benign" for 19 patients and this final diagnosis was retained by referring clinicians. Among the 19 patients with diffuse bone marrow uptake considered as benign, seven patients had a pejorative evolution and four of them developed osteomedullary metastases. In cancer patients, F-18-FDG-PET identify bone marrow diffuse uptake which seems to correspond well to abnormalities assessed on MRI studies. Notably, heterogenous F-18-FDG uptake and/or foci of increased uptake seems significative of marrow involvement. The limited population size and discordant published findings about bone marrow evaluation by F-18-FDG-PET compared with MRI can not pen-nit to ensure that these imaging modalities or one of these are sufficient to assess bone marrow status without performing bone marrow biopsy. Some patients with unexplained diffuse bone marrow uptake develop disease progression, such observations could be interestingly assessed by further studies. (C) 2009 Elsevier Masson SAS. All rights reserved.