18F-FDG coincidence SPECT imaging for early evaluation of response to chemotherapy and prognosis in non-Hodgkin's lymphoma

Objective: Evaluation of therapeutic response in lymphoma is of great clinical significance. The current study employed 18F-fluorodeoxyglucose(FDG) coincidence SPECT imaging to evaluate response and to predict prognosis of patients with non-Hodgkin's lymphoma (NHL) at early stage of chemotherapy. Methods: 18F-FDG coincidence SPECT imaging was performed in 48 patients with pathologically con- firmed NHL. The patients were divided into two groups based on the FDG scanning results at the early stage after chemotherapy. The follow-up lasted for 8-43 months and the progression free survival (PFS) analysis was undertaken. Twenty-three cases with positive 18F-FDG scans consisted of group 1 and 25 with negative scans in group 2. Results: The clinical outcome of those patients varied as their PET results differed. In group 1, 7 cases were in clinical remission and 11 in progression. In group 2, there were 24 cases with clinical remission and 1 progression, 18F-FDG imaging led to changes on therapeutic strategy in 21% (10/48) of the patients. The estimated 2 year PFS rate was 12.8% in group 1, and 78.0% in group 2. Kaplan- Meier survival analyses showed a strong correlation between FDG results and PFS (P<0.0001). Cox regression analyses indicated that early 18F-FDG scan after chemotherapy was an independent prognostic factors (P<0.001). The accuracy (85.4%) and positive predictive value (91.3%) with 18F-FDG coincidence SPECT imaging were higher than that with conventional imaging (66.7% and 68.0%, respectively). Conclusion: Early 18F-FDG scan after chemotherapy may be valuable in early assessment of response to chemotherapy and the prognosis in NHL. (authors)