Prognostic Parameters on Baseline and Interim F-18-FDG-PET/CT in Diffuse Large B-cell Lymphoma Patients

Purpose FDG-PET/CT is a widely used imaging method in the management of diffuse large B-cell lymphomas (DLBCL). Our aim was to investigate the prognostic performance of different PET-biomarkers in a multicentre setting. Methods We investigated baseline volumetric values (MTV and TLG, also normalized for body weight) segmented with three different methods (>SUV4 [glob4]; 41% isocontour [41pc], and a gradiant-based lesion growing algorithm [grad]) and interim parameters (Deauville-score, ΔSUVmax, modified qPET, and rPET) alongside clinical parameters (stage, R-IPI), using 24-month progression-free survival as the clinical endpoint. Receiver operating characteristics analyses were performed to define optimal cut-off points for the continous PET-parameters.Results 107 DLBCL patients were included (54 women; mean age: 53.7 years). MTV and TLG calculations showed good correlation among glob4, 41pc and grad methods, however, optimal cut-off points were markedly different. Significantly different PFS was observed between low- and high-risk groups according to baseline MTV, bwaMTV, TLG, bwaTLG, as well as interim parameters Deauville-score, ΔSUVmax, mqPET, and rPET. Univariate Cox-regression analyses showed hazard ratios lowest for bwaMTVglob4 (HR=2.3) and highest for rPET (HR=9.09). In a multivariate Cox-regression model, rPET was shown to be an independent predictor of PFS (p=0.041; HR=9.15). A combined analysis showed that ΔSUVmax positive patients with high MTV formed a group with distinctly poor PFS (35.3%).Conclusion Baseline MTV and TLG values and optimal cut-off points achieved with different segmentation methods varied markedly and showed limited prognostic impact. Interim PET/CT parameters provided more accurate prognostic information with semiquantitative „Deauville-like” parameters performing best in the present study.