Roles and Limitations of FDG PET in Pediatric Non-Hodgkin Lymphoma

PURPOSEThe usefulness of F fluorodeoxyglucose (FDG) positron emission tomography (PET) in pediatric Hodgkin lymphoma (p-HL) has been well demonstrated; however, pediatric non-Hodgkin lymphoma (p-NHL) has distinct characteristics from p-HL and adult NHL. We assessed roles of FDG PET in p-NHL. MATERIALS AND METHODSNineteen patients with p-NHL underwent 80 scans. Scans for staging (group A, n = 6) and response assessment (group B, n = 42) were compared with conventional imaging modalities (CIMs). Scans within group B for end-chemotherapy assessment (subgroup B+, n = 11) and for post-therapeutic surveillance (group C, n = 32) were analyzed for diagnostic performance. RESULTSIn group A, PET and CIM demonstrated comparable results. In group B, PET diagnoses were concordant with CIM in 21 and discordant in 11 studies. Of the discordant cases, PET suggested remnant lesions in 5 cases, whereas CIM suggested lesions in 6 cases. PET modified therapeutic strategy in 4 cases by detecting new extranodal lesions. In subgroup B+, sensitivity, specificity, and accuracy for predicting relapse were 50%, 71%, and 64%, respectively. In group C, sensitivity, specificity, and accuracy were 100%, 87%, and 88%, respectively, but positive predictive value was 33%. CONCLUSIONSThe role of FDG PET in p-NHL may be limited, unlike with p-HL or adult NHL. Nevertheless, FDG PET may serve complementarily in detecting unexpected lesions that can emerge in p-NHL.