摘要目的 评价18F-FDG PET/CT双时相显像在胰腺癌与胰腺炎性病变鉴别诊断中的作用.方法 前瞻性地对因临床怀疑胰腺病变而行18F-FDG PET/CT检查以及18F-FDG PET/CT常规扫描发现胰腺病变的患者行18F-FDG PET/CT双时相显像,选取其中实性局限性病变(经病理或临床影像学随访证实为胰腺癌和胰腺炎性病变)的患者入组.并根据胰腺病变最大径分为3组:≤2.0 cm组(A组),>2.0 cm且≤4.0 cm组(B组),>4.0 cm组(C组).注射FDG后(60±10)min行早期显像,(120±15)min后行延迟显像,分别测定双时相图像上胰腺病灶的SUVmax,并计算其滞留指数(RI).胰腺癌与胰腺炎性病变的SUVmax早期、SUVmax延迟、RI间差异行Mann-Whitney u检验.通过ROC曲线获得上述3个参数诊断胰腺癌的最佳界值及诊断效能,比较AUC(MedCalc软件中方法).结果 最终入组的胰腺实性局限性病变患者196例(胰腺癌152例,炎性病变44例).196例患者中,SUVmax延迟的AUC大于SUVmax早期的AUC(0.83和0.79),差异有统计学意义(z=3.64,P<0.01).A组45例,B组96例,C组55例,各组中胰腺癌与炎性病变的最大径差异均无统计学意义(z值:-0.39,-1.52,-1.41,均P>0.05).A组和B组中胰腺癌的3个参数均高于炎性病变(z值:-4.59~-3.00,均P<0.01).以SUVmax早期>3.6或RI>0联合诊断较SUVmax早期单独诊断胰腺癌可提高诊断的灵敏度[96.4%(27/28)与75.0%(21/28)]和准确性[95.6%(43/45)与82.2%(37/45)].B组中,SUVmax延迟的AUC大于SUVmax早期的AUC(0.81和0.77,z=2.06,P<0.05);SUVmax延迟诊断胰腺癌的最佳界值为5.3,相应的灵敏度、特异性、阳性预测值、阴性预测值和准确性分别为84.4%(65/77)、13/19、91.5%(65/71)、52.0%(13/25)和81.2%(78/96).C组中,胰腺癌的RI高于炎性病变:25.0%(15.8%~35.7%)和14.4%(4.6%~18.7%);z=-2.39,P<0.05,最佳诊断界值为19.0%,相应的灵敏度、特异性、阳性预测值、阴性预测值和准确性分别为68.1%(32/47)、7/8、97.0%(32/33)、31.8%(7/22)和70.9%(39/55).结论 18F-FDG PET/CT双时相显像的SUVmax延迟及RI可能有助于提高胰腺癌的诊断效能,胰腺病变最大径≤2.0 cm时可用SUVmax早期>3.6或RI>0联合诊断胰腺癌,以提高灵敏度和准确性;>2.0 cm且≤4.0 cm时用SUVmax延迟诊断胰腺癌效能可能更高;>4.0 cm时可用RI诊断.

abstractsObjective To investigate the value of dual-phase 18F-FDG PET/CT for differentiating pancreatic cancer from pancreatitis.Methods Dual-phase 18F-FDG PET/CT scanning was prospectively performed on patients with suspicious pancreatic lesions.Patients with solid focal pancreatic lesions proved by histopathology or clinical follow-up were enrolled and divided into 3 groups according to the maximum diameter of the focus: ≤2.0 cm (group A), >2.0 cm and ≤ 4.0 cm (group B), >4.0 cm (group C).SUVmax at (60±10) min and (120±15) min after FDG injection was defined as early and delayed SUVmax (SUVearly and SUVdelayed), respectively, and retention index (RI) was calculated.The differences of SUVearly, SUVdelayed and RI between pancreatic cancer and pancreatitis were analyzed with Mann-Whitney u test.ROC curve was used to determine the optimal cutoff values of the above three parameters and corresponding diagnostic efficiencies were obtained.The AUC was compared with MedCalc software.Results A total of 196 patients (152 pancreatic cancers and 44 pancreatic inflammatory lesions) with solid focal pancreatic lesions were enrolled.The AUC of SUVdelayed was significantly larger than that of SUVearly (0.83 vs 0.79, z=3.64, P<0.01).Numbers of patients in group A, B and C were 45, 96 and 55 respectively.There was no significant difference of the maximum diameter between pancreatic cancers and pancreatitis lesions in all three groups (z values:-0.39,-1.52,-1.41, all P>0.05).The SUVearly, SUVdelayed and RI of pancreatic cancers were all higher than those of pancreatitis in group A and B (z values: from-4.59 to-3.00, all P<0.01).The diagnostic sensitivity and accuracy of SUVearly > 3.6 combined with RI > 0 for diagnosing pancreatic cancer were higher than those of SUVearly > 3.6: 96.4%(27/28) vs 75.0%(21/28), 95.6%(43/45) vs 82.2%(37/45).The AUC of SUVdelayed was significantly larger than that of SUVearly in group B (0.81 vs 0.77, z=2.06, P<0.05).The optimal cutoff value of SUVdelayed in group B was 5.3, with the corresponding sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 84.4%(65/77), 13/19, 91.5%(65/71), 52.0%(13/25) and 81.2%(78/96), respectively.RI of pancreatic cancers was significantly higher than that of pancreatitis (25.0%(15.8%-35.7%) vs 14.4%(4.6%-18.7%), z=-2.39, P<0.05) in group C.The optimal cutoff value of RI in group C was 19.0%, with the corresponding sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 68.1%(32/47), 7/8, 97.0%(32/33), 31.8%(7/22) and 70.9%(39/55).Conclusions The SUVdelayed and RI of dual-phase 18F-FDG PET/CT might be useful for diagnosis of pancreatic tumors.SUVearly > 3.6 combined with RI >0 could be helpful to improve the diagnostic sensitivity and accuracy in patients with the maximum diameter of lesions ≤2.0 cm.The diagnostic value of SUVdelayed might be better than that of SUVearly in patients with the maximum tumor diameter of >2.0 cm and ≤4.0 cm.Only RI could be used for diagnosing pancreatic tumors in patients with the maximum tumor diameter > 4.0 cm.