RT Journal Article
SR Electronic
T1 Interim PET in Diffuse Large B-Cell Lymphoma
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1068
OP 1074
DO 10.2967/jnumed.120.255034
VO 62
IS 8
A1 Lars Kurch
A1 Andreas Hüttmann
A1 Thomas W. Georgi
A1 Jan Rekowski
A1 Osama Sabri
A1 Christine Schmitz
A1 Regine Kluge
A1 Ulrich Dührsen
A1 Dirk Hasenclever
YR 2021
UL http://jnm.snmjournals.org/content/62/8/1068.abstract
AB In diffuse large B-cell lymphoma, early assessment of treatment response by 18F-FDG PET may trigger treatment modification. Reliable identification of good and poor responders is important. We compared 3 competing methods of interim PET evaluation. Methods: Images from 449 patients participating in the “PET-Guided Therapy of Aggressive Non-Hodgkin Lymphomas” trial were reanalyzed by applying the visual Deauville score and the SUV-based qPET (q = quantitative) and ΔSUVmax scales to interim PET scans performed after 2 cycles of chemotherapy. qPET relates residual lymphoma 18F-FDG uptake to physiologic liver uptake, converting the ordinal Deauville scale into a continuous scale and permitting a direct comparison with the continuous ΔSUVmax scale, which is based on SUVmax changes between baseline and interim scans. Positive and negative predictive values were calculated for progression-free survival. Results: When established thresholds were used to distinguish between good and poor responders (visual Deauville score 1–3 vs. 4–5; ΔSUVmax > 66% vs. ≤ 66%), the positive predictive value was significantly lower with Deauville than ΔSUVmax (38.4% vs. 56.6%; P = 0.03). qPET and ΔSUVmax were strongly correlated on the log scale (Pearson r = 0.75). When plotted along corresponding percentiles, the positive predictive value curves for qPET and ΔSUVmax were superimposable, with low values up to the 85th percentile and a steep rise thereafter. The recommended threshold of 66% SUVmax reduction for the identification of poor responders was equivalent to qPET = 2.26, corresponding to score 5 on the visual Deauville scale. The negative predictive value curves were also superimposable but remained flat between 80% and 70%. Conclusion: Continuous scales are better suited for interim PET–based outcome prediction than the ordinal Deauville scale. qPET and ΔSUVmax essentially carry the same information. The proportion of poor-risk patients identified is less than 15%.