Hyperpolarized 13 C Pyruvate MRI / MRS for Characterizing Splenic Metabolism in Advanced Diffuse Large B‐Cell Lymphoma: A Pilot Study

ABSTRACT Background Splenic lymphoma involvement can be difficult to assess because splenomegaly is nonspecific and focal lesions may be absent. Hyperpolarized [1‐ 13 C]pyruvate MRI/MRS may provide metabolic information beyond morphologic assessment. Purpose To assess hyperpolarized [1‐ 13 C]pyruvate MRI/MRS's feasibility for evaluating splenic metabolism in advanced‐stage diffuse large B‐cell lymphoma (DLBCL), and explore associations with 18 F‐FDG PET/CT metrics. Study Type Prospective pilot study. Population 5 treatment‐naïve patients (4 male, 1 female) with Lugano Stage III–IV DLBCL and splenic involvement/splenomegaly and four female reference participants from a published cervical cancer study without visually apparent splenic abnormality on imaging. Field Strength/Sequence 3.0 T hyperpolarized [1‐ 13 C]pyruvate MRI/MRS using a multi‐echo gradient‐echo spiral chemical shift imaging sequence with IDEAL‐based reconstruction. Assessment Parameters included the apparent pyruvate‐to‐lactate exchange rate constant ( k PL ) and area‐under‐the‐curve ratios of lactate, alanine, and bicarbonate normalized to total carbon. PET/CT metrics included splenic maximum standardized uptake value (SUVmax) and spleen‐to‐liver ratio (SLR). Statistical Tests Mann–Whitney U tests compared groups. Spearman coefficients assessed associations between hyperpolarized 13 C and PET/CT metrics. p value < 0.05 indicated significance. Results All five patients completed hyperpolarized 13 C MRI/MRS acquisition without adverse events; four had dynamic datasets for kinetic analysis. Median spleen volume was 2.7‐fold higher in DLBCL than in the reference cohort. Median k PL and lactate/total carbon ratio were 2.4‐fold and 5.3‐fold higher, respectively, but not significant ( p = 0.081 and p = 0.114). Exploratory correlations were observed between k PL and each PET metric (SUVmax and SLR; ρ = 1.00; p = 0.083 for both), and between lactate/total carbon ratio and each PET metric ( ρ = 0.80; p = 0.333 for both); none reached significance. Data Conclusion Hyperpolarized [1‐ 13 C]pyruvate MRI/MRS was completed in all five patients, with kinetic analysis feasible in four. Findings showed numerically higher splenic pyruvate‐to‐lactate metabolism and nonsignificant positive correlations with FDG‐PET activity, warranting larger studies. Evidence Level 4. Technical Efficacy Stage 1.