The role of ¹⁸F-FDG PET/CT metabolic parameters in pediatric lymphoblastic lymphoma

This retrospective study aimed to evaluate the role of metabolic parameters of ¹⁸F-FDG PET/CT in pediatric lymphoblastic lymphoma (LBL).

Thirty patients with LBL underwent 42 scans. Metabolic parameters including maximum standardized uptake value (SUV_max), total metabolic tumor volume (TMTV), and total lesion glycolysis (TLG) were measured at baseline PET/CT. Univariate and multivariate analysis for survival were performed to assess their prognostic value. Twelve patients underwent PET/CT after reinduction regime, and the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT for predicting relapse were calculated.

Patients with stage Ⅳ had a higher TMTV than those with stage III (p = 0.031). Besides, patients with T-LBL or mediastinal involvement had a high TMTV and TLG (p < 0.05). There was no significant difference in PET/CT metabolic parameters between patients with different outcomes (p > 0.05). Children with a low TMTV (<242.91 cm³) had a better 3-year EFS compared with those with a high TMTV (88.9% vs. 56.3%; p = 0.036). SUV_max and TLG were not predictive of EFS (p = 0.874; p = 0.152). However, none of the metabolic parameters of baseline PET/CT were independent prognostic factors for outcomes of pediatric LBL. PET/CT underwent after reinduction regime present with higher sensitivity (50% vs. 0%) and NPV (90% vs. 83.3%) for predicting relapse than CT alone.

Metabolic parameters of baseline PET/CT were not predictive of outcomes in children with LBL. PET/CT done after the reinduction regime had better sensitivity and NPV than CT alone, and a negative scan could be a reliable indicator for sustained remission.