Assessing bone marrow involvement in paediatric Non-Hodgkin lymphoma: A comparative analysis of imaging ([¹⁸F]FDG PET-CT and WB-DW-MRI) and bone marrow aspiration – a retrospective study

Background: Bone marrow aspiration (BMA) is performed to determine bone marrow involvement (BMI) in paediatric non-Hodgkin lymphoma (NHL). In adult patients, non-invasive imaging with positron emission tomography ([¹⁸F]FDG PET-CT) is used instead of BMA. This is not the case in paediatric NHL. The study's primary objective is to compare the agreement of imaging ([¹⁸F]FDG PET-CT and WB-DW-MRI) versus BMA in paediatric NHL for BMI assessment, while also exploring the impact on tumour staging and subtype-specific differences. Procedure: This single-center retrospective review included children diagnosed with NHL between 2018 and 2022, 0–18 years, received a BMA, an [¹⁸F]FDG PET-CT and/or WB-DW-MRI before treatment. Data analysis included calculating sensitivity (SN), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and accuracy. BMA was considered the gold standard. Results: In 79 patients (mean age 10 years, 76% male), combined [¹⁸F]FDG PET-CT and WB-DW-MRI was concordant with BMA in 52 patients (66%). Combined imaging techniques demonstrated high SN, SP, NPV, and accuracy (respectively 80%, 73%, 97%, and 74%) for BMI. Imaging-based approach led to stage IV reclassification in 17 patients. Accuracy in assessing BMI varied across lymphoma subtypes. Conclusions: Compared to BMA, [¹⁸F]FDG PET-CT, and WB-DW-MRI were highly accurate in determining BMI in paediatric NHL with notable high NPVs. These imaging techniques offer viable alternatives for BMA in the evaluation of BMI.