The value of 18 F-FDG-PET/CT for evaluation of bone marrow involvement in pediatric Non-Hodgkin Lymphoma Conferences uri icon

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abstract

  • Introduction: Bone marrow evaluation is an integral component of staging workup in children with a new diagnosis non-Hodgkin lymphoma (NHL) that is obtained through unilateral or bilateral BM biopsy (BMB). 18 F- FDG -PET/CT is increasingly used as a reliable method for the staging of NHL. PET/CT for BM evaluation is now accepted practice in staging of adult patients, and increasingly in pediatric patients, with HL. The purpose of this study was to evaluate the diagnostic accuracy of PET/CT in detecting BMI compared to bone marrow biopsy (BMB) in pediatric patients with NHL. The secondary aim of the study was to evaluate the prognostic value of BMI detected by PET/CT. Methods: 69 paediatric patients diagnosed with NHL, who underwent staging PET/CT and BMB, were included. BMI on PET/CT was analyzed visually according to a proposed five-point scale (scores 1-5) where scores 1, 2 and 3 were considered negative and score 4 and 5 were considered positive. Ideally, to consider PET/CT result as positive for BMI, histopathological confirmation of the PET-positive lesion is needed. BMB of PET-positive lesion in addition to the standard BMB wasn’t feasible for ethical purpose. Subsequently, BMB wasn’t the sole reference standard to calculate the diagnostic accuracy in this study given the potential for sampling error with focal and multifocal BMI. PET/CT was considered as true positive in cases where any one of the following criteria was present: 1) positive BMB if the focal FDG uptake on PET/CT and BMB site were the same; 2) no evidence of underlying bone changes to suggest alternative pathology; 3) disappearance of lesions on follow-up PET/CT after chemotherapy, in parallel with other lymphoma lesions. The rest of the cases positive for BMI on PET/CT were considered as false positives. PET/CT was considered as false negative if BMB was positive and PET/CT was negative for BMI. A negative PET/CT was considered as true negative, if BMB was negative for BM. The prognostic significance of BMI detected by PET/CT was determined by overall survival (OS) and 3-year progression free survival (PFS). Results: PET/CT was more sensitive than BMB for the detection of BMI with a sensitivity of 94 % vs. 25% and as specific as BMB with a specificity of 100% for both methods. PET/CT demonstrated a higher negative predictive value compared to BMB of 98% vs 80% respectively as well as higher accuracy of 99% using PET/CT vs. 81% using BMB. In addition, BMI by PET/CT showed a strong correlation with PFS of 96.8% vs 86.5% in cases with negative and positive BMI on PET/CT respectively (p = 0.003); and OS of 100% vs 82.5% (p value=0. 004) in cases with negative and positive BMI on PET/CT, respectively. Conclusions: PET-CT showed better diagnostic capability for the detection of BMI and prediction of outcome in this cohort of patients. We underscored the utility of PET-CT as a supportive diagnostic tool to BMB.