Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma among adults, with an annual incidence of 7-8 cases per 100,000 people per year. A key factor in deciding DLBCL patient management plans is determining the extent of bone marrow involvement, which is generally carried out by bone marrow biopsy. A recent study from a group of researchers in Dijon, France have now determined that, compared to biopsy, 18F-FDG PET CT imaging is more sensitive, showed a higher negative predictive value and was more accurate. The lead author of the study, Dr L Berthet, said that “although bone marrow biopsy is considered as the gold standard to evaluate bone marrow involvement by high-grade lymphomas, 18F-FDG PET/ CT is in fact the best method to evaluate extension of the disease, as well as to avoid invasive procedures”. 
The retrospective study carried out by the Dijon team included 133 patients diagnosed with DLBCL. All patients received both a whole-body 18F-FDG PET/CT scan, as well as a bone marrow biopsy to determine bone marrow involvement. A final diagnosis of bone marrow involvement was made if the biopsy was positive, or if the positive PET/CT scan was confirmed by a guided biopsy, by targeted magnetic resonance imaging (MRI) or, after chemotherapy, by the concomitant disappearance of focal bone marrow uptake and uptake in other lymphoma lesions on 18F-FDG PET/CT reassessment. Progression- free survival and overall survival were then analyzed. Of the patients studied, 33 were considered to have bone marrow involvement. Of these, eight were positive according to the biopsy and 32 were positive according to the PET/CT scan. 18FDG PET/CT was more sensitive (94 percent vs. 24 percent), showed a higher negative predictive value (98 percent vs. 80 percent) and was more accurate (98 percent vs. 81 percent) than bone marrow biopsy. Among the 26 patients with positive 18F-FDG PET/CT results and negative biopsy results, 11 were upstaged to stage IV by PET/CT, which changed their treatment plans. 18F-FDG PET/CT was also determined to be an independent predictor of progression-free survival. “Molecular imaging is the best method to adapt targeted therapies to each patient. The emergence of PET/MRI and novel radiotracers predicts an exciting new future for our field” Berthet said. http://tinyurl.com/Berthet-paper