Prognostic Value of Multiple Manual Segmentation Methods for Diffuse Large B-Cell Lymphoma with ¹⁸F-FDG PET/CT

Area of Science:

• Nuclear Medicine
• Oncology
• Radiomics

Background:

• Quantitative 18F-FDG PET/CT metrics are crucial for assessing patient outcomes in diffuse large B-cell lymphoma (DLBCL).
• Standardization is hindered by the lack of consensus on optimal segmentation thresholds for metabolic tumor volume (MTV).

Purpose of the Study:

• To evaluate the prognostic value of different MTV segmentation approaches in DLBCL patients.
• To compare the predictive accuracy of MTV metrics against the International Prognostic Index (IPI).

Main Methods:

• Assessed 140 stage II-IV DLBCL patients treated with standard immunochemotherapy.
• Derived MTV using fixed SUV (≥2.5, ≥4.0), relative (>41% SUVmax), and adaptive thresholds.
• Performed univariate, multivariate, and ROC analyses to assess prognostic significance and predictive accuracy.

Main Results:

• Baseline MTV metrics correlated significantly with 3-year overall survival (OS3) in univariate analysis, with MTV41 showing the strongest association.
• MTV25 and MTV41 remained significant predictors in stage 4 patients.
• In multivariate analysis, IPI was the dominant predictor of OS3, outperforming all MTV metrics.
• IPI demonstrated superior AUC (0.76) compared to PET-based metrics (0.64-0.69).

Conclusions:

• While PET-derived MTV metrics offer prognostic value in univariate analysis for DLBCL, threshold selection has minimal impact.
• The added prognostic value of MTV metrics is limited when combined with IPI.
• IPI remains the most reliable survival predictor in DLBCL, reinforcing its established role.