| Objective:We investigated the application value of pretreatment 18F-FDG PET/CT PET/CT parameters expressing metabolic parameters and lesion dissemination in prognosis assessment and pathological grading of follicular lymphoma（FL）.Methods:Baseline 18F-FDG PET/CT images of 126 patients with grade 1-3A FL were retrospectively analyzed from February 2013 to December 2020.The total metabolic tumor volume（TMTV）and total lesion glycolysis（TLG）were calculated using the 41%maximum standardized uptake value（SUVmax）thresholding method.The parameter characterizing lesion dissemination was expressed as the distance between the two lesions that were furthest apart（Dmax）.Results:A total of 126 patients with FL were recruited,63 males and 63 females,with a median age of 53 years（range 21-76 years）.The median follow-up time was 41 months,and the 5-year progression-free survival（PFS）and overall survival（OS）were 51.9%and89.1%,respectively.Univariate analysis showed PET/CT parameters（SUVmax>17.60,TMTV>408.72cm3,TLG>1446.98,and Dmax>56.73cm）and elevated serum Lactate dehydrogenase（LDH）,elevatedβ2-microglobulin,and hemoglobin<12g/d L were adverse factors for PFS and OS.In addition,pathologic grade 3A and the longest diameter of the largest involved node>6cm were unfavorable actors affecting OS.Multivariate analysis showed that TLG,Dmax,and LDH were independent predictors of PFS,while TLG was the independent prognostic factor of OS.In this study,TLG,Dmax,and LDH were used to construct a prognostic scoring system for PFS.The predictive performance of this model was good,and its concordance index（C-index）was 0.785,which was significantly higher than that of（Follicular Lymphoma International Prognosis Index,FLIPI）、FLIPI2 and PRIMA-PI（C-index:0.628-0.701,P<0.05）.In addition,the area under the receiver operating characteristic curves of PFS at 3 and 5-year of our scoring system were higher than that of FLIPI,FLIPI2,and PRIMA-PI.The decision curve analysis showed that our scoring system had higher net benefits than the three existing prognostic indices.In addition,we found that SUVmax was significantly higher in the high-grade group（grade3A,36 cases）than in the low-grade group（grade 1-2,90 cases）（median:13.63 vs.11.45,P=0.013）,and SUVmax remained an independent predictor in the multivariate logistic regression analysis（P=0.001）.However,there was extensive overlap in SUVmax between the two groups（range:2.25-39.62 vs.3.17-39.80）,and the sensitivity of SUVmax（threshold 17.38）for predicting pathological grading was relatively low（41.7%）.Conclusions:The results of this study provide evidence to support the prognostic value of baseline PET/CT metabolic and lesion dissemination parameters in FL patients.The total metabolic tumor burden parameter of TLG along with Dmax reflecting lesion dissemination and serum LDH were independent prognostic factors of PFS,while TLG was the only independent predictor of OS.The prognostic scoring system based on TLG,Dmax,and LDH showed superior performance and clinical benefit to FLIPI,FLIPI2,and PRIMA-PI.In addition,our study found that SUVmax was related to the pathological grade,but it was difficult to use an absolute threshold to distinguish high-grade from low-grade FL.PET/CT could be used as an auxiliary tool for pathological grading,but could not replace pathological biopsy.Objective: The application value of interim 18F-FDG PET/CT imaging in the prognostic assessment of follicular lymphoma（FL）is controversial.The purpose of this study was to investigate the role of interim PET/CT images in assessing the prognosis of FL patients during immuno-chemotherapy by visual and semi-quantitative interpreting methods.Methods: Baseline and interim 18F-FDG PET/CT images of 60 patients with grade 1-3A FL were retrospectively analyzed from February 2013 to December 2020.The interim PET/CT images were evaluated by Deauville standard（DS）and semi-quantitative parameters of target lesion-to-liver SUVmax ratio（LLR）and delta maximum standard uptake value（ΔSUVmax）.The optimal thresholds of LLR and ΔSUVmax were determined by the receiver operating characteristic curve.Results: A total of 60 patients with FL were recruited,32 females and 28 males,with an average age of 50.92±12.06 years（range 21-76 years）.The median follow-up time was 38 months,ranging from 11 to 102 months.By the end of follow-up,17 patients had disease progression,and 4 patients died of FL.The 5-year PFS（progression-free survival）was54.9%.Patients were evaluated by Deauville standard,and a DS score of 4-5 was considered as the positive PET/CT imaging（17 cases）,while 1-3 was classified as the negative group（43 cases）.The 3-year PFS of the two subgroups were 37.4% and 87.3%,respectively（HR=4.51,P<0.001）.In this study,LLR≥1.32 was defined as the positive group（9 cases）and LLR<1.32 as the negative group（51 cases）.The 3-year PFS of the two subgroups were 16.7% and 85.1%,respectively（HR=7.51,P<0.001）.In addition,ΔSUVmax≤82.6% was defined as the positive group（42 cases）,and SUVmax>82.6% as the negative group（18 cases）.The 3-year PFS of the two subgroups were 68.0% and 88.5%, respectively,but there was no significant difference in PFS between the two subgroups（HR=3.21,P=0.122）.Compared with visual analysis of DS,the LLR evaluation method had higher accuracy（80.00% vs.73.33%）,positive predictive value（77.78% vs.52.94%）,and specificity（95.35% vs.81.40%）.Subsequently,the interim imaging results of DS score and LLR analysis were incorporated into the baseline model described in Part I for multivariate survival analysis,respectively.The results showed that DS 4-5 and high LLR were independent adverse prognostic factors（P=0.022,P=0.035）.The scoring systems for predicting PFS were built using the baseline parameters（TLG or Dmax）along with interim PET/CT evaluated by DS or LLR,which were able to effectively distinguish between subgroups of FL patients with significantly different outcomes（P<0.001）.Conclusions: Interim PET/CT imaging might be an effective tool for predicting the prognosis of FL patients.In addition to the visual analysis of the Deauville standard,the LLR analysis could be a promising evaluation method to interpret PET/CT results in FL patients receiving immunochemotherapy as first-line treatment.The new prognostic scoring systems,which combine interim PET/CT results with baseline parameters,enable risk stratification in FL patients. |
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