A different perspective on PET/CT before treatment in patients with Hodgkin lymphoma: importance of volumetric and dissemination parameters.

The aim of this study is to investigate the role of the combination of volumetric and dissemination parameters obtained from pretreatment 18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in predicting the interim response and progression status in patients with Hodgkin lymphoma (HL). Pretreatment PET/CT images of HL patients were analyzed with LIFEx software, and volumes of interest (VOIs) were drawn with a fixed SUV 4.0 threshold. MTV, SUVmax, and TLG values were obtained from each VOI. Total MTV (tMTV) was calculated by summing the MTV values in all VOIs, and similarly, total TLG (tTLG) was obtained by summing the TLG values. The distance between the centers of the lesions was noted as Dmax, and the distance between the outermost voxels of the lesions as DmaxVox. tMTV/DmaxVox was calculated by dividing the tMTV value by the DmaxVox value, and tTLG/DmaxVox was calculated by dividing the tTLG value by the DmaxVox value. The correlation of pretreatment PET parameters with response groups (complete/poor) and relapse/progression status (stable/progressive) was statistically evaluated. A total of 52 patients were included in the study. Bulky disease, tMTV, tTLG, and tMTV/DmaxVox values were found to be significantly higher in the poor response group. tMTV > 190.60 ml was found to be the only prognostic factor predicting interim PET response. The tMTV/DmaxVox and tTLG/DmaxVox showed statistically significant differences between the groups with and without progression. tMTV/DmaxVox > 7.70 was found to be the only prognostic factor in predicting relapse/progression. The evaluation of tumor burden and dissemination together in 18F-FDG PET/CT before treatment in patients with HL can help us to predict the results of the patients.