Aim: To define the role of 18F-flourodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in the detection of bone marrow (BM) involvement in patients with diffuse large B cell lymphoma (DLBCL).
Materials and methods: Fifty-four (mean age: 55.5 ± 18.3 years, 20 female and 34 male) DLBCL patients who underwent pretreatment 18F-FDG PET/CT were included to the study. Focal or diffuse BM 18F-FDG uptake that is higher than mediastinal blood pool uptake was accepted as positive. After staging of disease by CT and 18F-FDG PET/CT, all the patients received R-CHOP treatment after diagnostic blinded bone marrow biopsy (BMB). Presence of positive BM uptake in 18F-FDG PET/CT and histopathological examination results of BMBs were analyzed by Chi-square test. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of 18F-FDG PET/CT in the detection of BM involvement were calculated. Prognostic importance of the presence of BM 18F-FDG uptake was analyzed by Kaplan-Meier analysis.
Results: BM 18F-FDG uptake was detected in 8 patients. Histopathological examination of BMB revealed BM involvement in 6 out of 8 patients. BMB was negative in all patients who have no 18F-FDG uptake in the evaluation of PET/CT images. Sensitivity, specificity, accuracy, PPV, and NPV of 18F-FDG PET/CT in the detection of BM involvement were calculated as 100%, 96%, 96%, 75%, and 100%, respectively. In the Kaplan-Meier analysis, we found that presence of pretreatment 18F-FDG uptake in BM has a prognostic importance. Whereas mean time to progression (TTP) in patients with BM uptake was 32.25 ± 10.9 months and mean TTP in those without was 51.69 ± 3.6 months (p = 0.013).
Conclusions: BM uptake in pretreatment 18F-FDG PET/CT is an important prognostic factor in DLBCL patients. Moreover, in consideration of high NPV, 18F-FDG PET/CT could eliminate unnecessary BMB in FDG-negative patients.
Keywords: 18F-FDG positron emission tomography/computed tomography; bone marrow involvement; diffuse large B cell lymphoma.