Influence of Software Tool and Methodological Aspects of Total Metabolic Tumor Volume Calculation on Baseline [18F]FDG PET to Predict Survival in Hodgkin Lymphoma

Aim

To investigate the respective influence of software tool and total metabolic tumor volume (TMTV0) calculation method on prognostic stratification of baseline 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography ([18F]FDG-PET) in newly diagnosed Hodgkin lymphoma (HL).

Methods

59 patients with newly diagnosed HL were retrospectively included. [18F]FDG-PET was performed before any treatment. Four sets of TMTV0 were calculated with Beth Israel (BI) software: based on an absolute threshold selecting voxel with standardized uptake value (SUV) >2.5 (TMTV0_2.5), applying a per-lesion threshold of 41% of the SUV_max (TMTV0₄₁) and using a per-patient adapted threshold based on SUV_max of the liver (>125% and >140% of SUV_max of the liver background; TMTV0₁₂₅ and TMTV0₁₄₀). TMTV0₄₁ was also determined with commercial software for comparison of software tools. ROC curves were used to determine the optimal threshold for each TMTV0 to predict treatment failure.

Results

Median follow-up was 39 months. There was an excellent correlation between TMTV0₄₁ determined with BI and with the commercial software (r = 0.96, p<0.0001). The median TMTV0 value for TMTV0₄₁, TMTV0_2.5, TMTV0₁₂₅ and TMTV0₁₄₀ were respectively 160 (used as reference), 210 ([28;154] p = 0.005), 183 ([-4;114] p = 0.06) and 143ml ([-58;64] p = 0.9). The respective optimal TMTV0 threshold and area under curve (AUC) for prediction of progression free survival (PFS) were respectively: 313ml and 0.70, 432ml and 0.68, 450ml and 0.68, 330ml and 0.68. There was no significant difference between ROC curves. High TMTV0 value was predictive of poor PFS in all methodologies: 4-years PFS was 83% vs 42% (p = 0.006) for TMTV0_2.5, 83% vs 41% (p = 0.003) for TMTV0_41, 85% vs 40% (p<0.001) for TMTV0₁₂₅ and 83% vs 42% (p = 0.004) for TMTV0₁₄₀.

Conclusion

In newly diagnosed HL, baseline metabolic tumor volume values were significantly influenced by the choice of the method used for determination of volume. However, no significant differences were found in term of prognosis.