Abstract
Background: In pediatric Hodgkin’s lymphoma (pHL) early response-to-therapy prediction is metabolically assessed by (18)F-FDG PET carrying an excellent negative predictive value (NPV) but an impaired positive predictive value (PPV). Aim of this study was to improve the PPV while keeping the optimal NPV. A comparison of different PET data analyses was performed applying individualized standardized uptake values (SUV), PET-derived metabolic tumor volume (MTV) and the product of both parameters, termed total lesion glycolysis (TLG); Methods: One-hundred-eight PET datasets (PET1, n = 54; PET2, n = 54) of 54 children were analysed by visual and semi-quantitative means. SUVmax, SUVmean, MTV and TLG were obtained the results of both PETs and the relative change from PET1 to PET2 (Δ in %) were compared for their capability of identifying responders and non-responders using receiver operating characteristics (ROC)-curves. In consideration of individual variations in noise and contrasts levels all parameters were additionally obtained after threshold correction to lean body mass and background; Results: All semi-quantitative SUV estimates obtained at PET2 were significantly superior to the visual PET2 analysis. However, ΔSUVmax revealed the best results (area under the curve, 0.92; p < 0.001; sensitivity 100%; specificity 85.4%; PPV 46.2%; NPV 100%; accuracy, 87.0%) but was not significantly superior to SUVmax-estimation at PET2 and ΔTLGmax. Likewise, the lean body mass and background individualization of the datasets did not impove the results of the ROC analyses; Conclusions: Sophisticated semi-quantitative PET measures in early response assessment of pHL patients do not perform significantly better than the previously proposed ΔSUVmax. All analytical strategies failed to improve the impaired PPV to a clinically acceptable level while preserving the excellent NPV.
Highlights
In oncology, volumetric assessment of response to therapy is based on CT as it forms a reproducible, easy-to-acquire rational for treatment evaluation
Qualitative response assessment by visual ratings of PET2 revealed a sensitivity of 66.7% and a specificity of 70.8% (AUC, 0.69; p-value, 0.044; positive predictive value (PPV), 22.2%; negative predictive value (NPV), 94.4%; accuracy, 70.4%) (Table 2)
Both SUVmax2 and SUVmean2 performed significantly better than the qualitative response assessment (SUVmax2 vs. visual: p = 0.034; SUVmean2 vs. visual: p = 0.04)
Summary
Volumetric assessment of response to therapy is based on CT as it forms a reproducible, easy-to-acquire rational for treatment evaluation. In this respect, we were able to demonstrate in a subset (n = 33/54) of the patients investigated in the present study, that the most accurate response-to-therapy assessment in pediatric Hodgkin lymphoma (pHL) was the percentaged decrease comparing the maximal. With the requirement to warrant a negative predictive value (NPV) of 100% in response assessment, the data collected there indicated that early response assessment by PET using the ΔSUVmax achieved a positive predictive value (PPV) superior to visual PET assessment [6,7]. In pediatric Hodgkin’s lymphoma (pHL) early response-to-therapy prediction is metabolically assessed by (18)F-FDG PET carrying an excellent negative predictive value (NPV) but an impaired positive predictive value (PPV).
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