The Value Of Baseline ¹⁸F-FDG PET/CT Imaging For The Diagnosis Of Bone Marrow Infiltration And Its Prognosis In DLBCL Patients

Objective:To investigate the accuracy of Positron Emission Tomography/Computed Tomography（PET/CT）in diagnosing bone marrow infiltration in patients with first pathologically confirmed Diffuse Large B cell Lymphoma（DLBCL）and the correlation between the different uptake patterns of bone marrow ¹⁸F-FDG and the prognosis of DLBCL patients.Method:Clinical data of 156 patients with DLBCL diagnosed in Shanxi Cancer Hospital were retrospectively analyzed.All patients underwent bone marrow aspiration biopsy（BMB）,bone marrow smear,Flow Cyto Metry（FCM）and ¹⁸F-Fluorodeoxyglucose(¹⁸F-FDG)PET/CT scan before treatment.Using the normal liver right lobe S6 segment ¹⁸F-FDG uptake value as the standard,patients were classified as having focal increased bone marrow uptake（focal PET,f PET⁺）,diffuse increased bone marrow uptake（diffuse PET,d PET⁺）and normal bone marrow uptake（normal PET,n PET）patterns.Differences in clinicopathological factors between groups were analyzed by t-test,Mann-Whitney U test,χ²test,or Fisher’s exact test,depending on the type of variables.Kappa test was used to determine the consistency of PET/CT and bone marrow examination in diagnosing BMI in DLBCL patients.Subjects’Operating Characteristic（ROC）curves were plotted using the Maximun standardized uptake value（SUVmax）ratio of bone marrow/liver,and the Area Under Curve（AUC）to find the optimal threshold,and the difference was considered statistically significant at P<0.05.The prognostic significance of different uptake patterns of bone marrow was derived by the Kaplan-Meier method,and Cox regression models were used to identify relevant risk factors from clinical,pathological,and imaging variables.Results:There were 45 PET⁺patients,including 17 f PET⁺patients,28 d PET⁺patients and 111n PET patients.There were 21 patients with positive Bone Marrow Infiltration⁺（BMI⁺）and135 patients with BMI^-.In f PET⁺patients,BMI⁺accounted for 41.2%and in d PET⁺patients,BMI⁺accounted for 42.9%.There were 12 patients with d PET⁺in patients with BMI⁺and 16 patients with d PET⁺in patients with BMI^-.The BMI⁺condition assessed by bone marrow examination was present in 2 cases in n PET patients.The sensitivity,specificity,positive predictive value and negative predictive value of f PET⁺were 33.3%,92.6%,41.2%and 89.0%respectively.The sensitivity,specificity,positive predictive value and negative predictive value of d PET⁺were 57.1%,88.1%,42.9%and 93.0%,respectively.ROC working curve of d PET⁺vs n PET patients with bone marrow/liver SUVmax ratio to determine BMI:AUC=92.3%（P<0.001）,with an optimal threshold of bone marrow/liver SUVmax=1.19,sensitivity of 86.7%,and specificity of 91.1%.d PET⁺vs bone marrow SUVmax plotted ROC curve:AUC=94.8%（P<0.001）,with an optimal threshold of bone marrow SUVmax=3.60,sensitivity of 86.7%,and specificity of91.1%.Univariate analysis showed that Ann Arbor stage,B symptoms,National Comprehensive Cancer Network-International Prognostic Index,NCCN-IPI)score,Lactate Dehydrogenase（LDH）,BMI⁺and bone marrow uptake pattern were correlated with Progression-Free Survival（all P<0.05）.Ann Arbor staging,NCCN-IPI score,LDH,BMI⁺and bone marrow uptake pattern were correlated with Overall Survival（OS）（all P<0.05）.Multivariate analysis showed that stage III/IV,LDH and f PET⁺（all P<0.05）was an independent predictor of PFS.There were no independent predictors in the multivariate analysis of OS.Conclusion:1.¹⁸F-FDG PET/CT as a means of diagnosing BMI in DLBCL patients;f PET⁺is a typical manifestation of lymphoma BMI,and d PET⁺indicates suspicious BMI in DLBCL patients.d PET⁺patients,bone marrow/liver SUVmax>1.19,bone marrow;3.60 May serve as a diagnostic critical point for predicting the outcome of bone marrow infiltration;bone marrow SUVmax>3.60 may be diagnostic of BMI critical point;2.The bone marrow uptake pattern in PET/CT imaging was associted with the prognosis of DLBCL patients,and f PET⁺correlated with the PFS of patients.f PET⁺may provide a basis for patient BMI diagnosis,treatment and prognosis aspect.