Diagnostic and Prognostic Evaluation Value of 18f-FDG PET-CT for Bone Marrow Infiltration in Primary Treated Follicular Lymphoma
Authors: Zhao Yu , Shen Jianzhen , Liu Tingbo , Li Xiaofan 
Published: December 2023

Objective ：The purpose of this paper is to evaluate the value of 18F-FDG PET-CT in the diagnosis of bone marrow infiltration in patients with primary treated follicular lymphoma and whether it provides valuable information for staging and prognosis.

Methods ：This is a retrospective analysis of 199 hospitalized patients with primary 1-3a follicular lymphoma diagnosed by pathological examination from January 01, 2014 to September 31, 2022 in Fujian Medical University's Union Hospital. The recorded clinical characteristics, bone marrow examination, the result of 18F-FDG PET-CT for bone marrow involvement, treatment regimen, efficacy, and survival status were analyzed. univariate analysis and multivariate analysis were performed for clinical features, laboratory results.

Results ：

1.Among the 199 patients with FL , the median age was 54.1 years old, including 88 males and 111 females Stage III-IV patients accounted for 82.9%.The Number in high-risk groups was 70（35.2%）according to FLIPI score and was 33（16.6%）according to FLIPI-2 score. The median OS in all cases was not reached. The cumulative OS rates at 1, 3, and 5 years were 93.5%90.0% and 88.8%,respectively The median PFS in all cases was not reached. The cumulative PFS rates at 1, 3, and 5 years were 87.3%72.0% and 67.8%,respectively. PET-CT images showed increased bone marrow uptake FDG in a total of 42 patients (21.1%), of which 17 patients (8.54%) had focal increased bone marrow uptake FDG (6 unifocal; 3 bifocal; 8 multifocal), 6 patients (3.02%) had focal with diffuse increased bone marrow uptake FDG, and 19 patients (9.55%) had diffuse bone marrow FDG uptake was elevated in 19 patients (9.55%).Bone marrow infiltration was detected by PET-CT alone in 16 patients (8.04%),and by BMB alone in 19 patients (9.54%), and by both PET-CT and BMB in 26 patients (13.63%), Bone marrow infiltration was detected by PET-CT and BMB in a total of 26 patients (13.61%). 45 patients (22.6%) had bone marrow infiltration detected by BMB and 42 patients (21.1%) had bone marrow infiltration detected by PET-CT. Using BMB results as the gold standard for bone marrow infiltration, the paired chi-square design corrected chi-square test yielded c 2=0.11， P=0.735, so it can be considered that the results of the two methods for testing bone marrow infiltration were consistent, and the difference was not statistically significant, and the agreement between PET-CT and BMB diagnostic results was general (Kappa=0.485, P&lt;0.05), using BMB as the gold standard , the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET-CT for detecting bone marrow infiltration were 57.78%, 89.61%, 82.41%, 61.90%, and 87.90%, respectively.The initial staging of 199 patients with FL was based on PET-CT findings of lesions outside of the bone marrow, and 22 patients with initial stage III were up-staged to stage IV by restaging with PET-CT findings of bone marrow lesions; similarly, 1 patient with initial stage II was up-staged to stage IV by restaging with BMB findings of bone marrow lesions, and 23 patients with initial stage III were up-staged to stage IV by BMB. Eight patients with stage III were upstaged to stage IV by PET-CT alone, one patient with stage II and nine patients with stage III were upstaged to stage IV by BMB alone, and 14 patients were upstaged to stage IV by BMB and PET-CT together, making a total of 32 patients upstaged to stage IV by BMB or PET-CT. 5 patients were upstaged to stage IV by BMB and PET-CT. Five patients changed their treatment plan due to up-staging of BMB bone marrow infiltration, and five patients had up-staging of BMB bone marrow infiltration but were unable to change their standard treatment due to symptoms or high tumor load.The result of univariate analysis showed that BMB positivity, PET-CT detection of bone marrow infiltration, Ann Arbor staging based on PET-CT, PET-CT combined with Ann Arbor staging of BMB,were factors associated with OS ( P &lt; 0.05)Multifactorial results showed thatPET-CT detection of bone marrow infiltration were risk factors for OS (P&lt;0.05)

Conclusion ： Combined PET-CT and marrow biopsy has higher accuracy than bone marrow biopsy alone. PET-CT detection of bone marrow infiltration were risk factors for OS and was associated with poor prognosis.

Keywords: bone marrow biopsy, positron emission tomography/computed tomography，follicular lymphoma, prognostic factor