Effect of whole-body 18F-FDG PET on detection and clinical staging of non-Hodgkin's lymphoma

Purpose: Accurate staging and re-staging in primary and post therapy non-Hodgkin's lymphoma (NHL) is important for treatment management. In this study, the utility of whole-body PET with [18F]-fluorodeoxyglucose was performed as an imaging modality for initial staging and re-staging and evaluating bone marrow infiltration non-Hodgkin's lymphoma. Methods: FDG PET studies were performed on 56 patients. The patients were divided into 2 groups: group 1, suspected or diagnostic non-Hodgkin's lymphoma (n=39), and group 2, post-treatment non-Hodgkin's lymphoma (n=17). Lymphoma-suspicious patients were followed up with histology, cytology. Whole-body images were acquired 1 h after intravenous injection of 370-555 MBq FDG using a PET scanner with an axial field of view of 15.5 cm. Results: In groups 1, thirty patients had positive scans, which were proven to be true-positive in 26 patients, whereas 3 patients had false-positive findings. Ten patients had negative scans, which were proven to be true-negative. The sensitivity and specificity of FDG PET for untreated lymphoma were 100%(26 of 26) and 77%(10 of 13). The accuracy of FDG PET was 92%(36 of 39). In the 26 true-positive patients, PET led to a change in the clinical staging in 42.3% of patients: 30.8% were upstaged and 11.5% were downstaged. In evaluation of bone marrow infiltration, The PET scan and marrow histology agreed in 21 patients(80.8%,21 of 26), being concordant positive in 9 and concordant negative in 12. In three patients the PET scan showed increasing FDG uptake but bone marrow biopsy was negative; in 2 of these 3 patients was proven by MRI, another was proven by bone marrow biopsy after 1 month. 2 patients bone marrow biopsy was positive but PET found that bone marrow only had mild uptake of Fag. In group 2, other imaging modalities only proved 6 patients in complete remission, FDG PET found out another 5 patients in complete remission. In another 8 patients, new treatment have planed. Conclusion: Noninvasive FDG-PET is very accurate in the staging and re-staging and bone marrow infiltration of non-Hodgkin's lymphoma. Compared with standard staging modalities (CT and BMB), PET was significantly superior or equal to CT and BMB, and led to changes in the therapy regimen for 42.3% of untreated patients