FDG PET for Evaluation of Bone Marrow Status in T-Cell Lymphoma

Purpose In T-cell lymphoma, the role of FDG PET for bone marrow (BM) evaluation is not established yet. We investigated diagnostic performance and prognostic implication of FDG PET for BM evaluation in peripheral T-cell lymphoma (PTCL) and extranodal NK/T-cell lymphoma (NKTCL). Patients and Methods Patients with PTCL or NKTCL, who underwent initial staging with FDG PET and BM biopsy, were retrospectively enrolled and analyzed. PET BM finding was evaluated using visual analysis and a quantitative index (marrow-to-liver ratio [MLR]). Diagnostic performance of PET for BM involvement was assessed with biopsy as the gold standard. Prognostic value of PET findings was also assessed regarding progression-free survival (PFS) and overall survival (OS). Results A total of 109 (63 PTCL and 46 NKTCL) patients were analyzed. Biopsy revealed BM involvement in 35.8% of cases. Sensitivity and specificity of PET for diagnosing positive BM biopsy were 61.5% and 75.7% by visual analysis and 64.1% and 72.9% by MLR. Diagnostic performance of PET was not different across lymphoma types. Survival analysis revealed that MLR and BM biopsy result is significant for both PFS and OS. In multivariate analysis, MLR was an independent prognostic factor for both PFS and OS. Marrow-to-liver ratio was also a significant prognostic factor in BM biopsy-negative patients. Conclusions Despite fair correlation with BM biopsy result, PET may not replace BM biopsy in PTCL and NKTCL. However, the BM finding on PET is an independent prognostic factor, suggesting additional biological implication of PET findings.