全身弥散加权成像与PET-CT及颅脑MRI在肺癌分期诊断中的对照研究谈炎欢,李俊晨 南京中医药大学附属常熟医院 放射科,江苏 常熟 215500 [摘 要]目的确定全身磁共振弥散加权成像(Whole Body Diffusion Weighted Imaging, WB-DWI)肺癌分期的诊断性能是否优于PET-CT联合颅脑MRI。方法用于肺癌分期与术前PET-CT联合颅脑MRI和WB-DWI检查的肺癌患者30例。其中鳞癌22例,腺癌6例,小细胞癌2例。对肺癌分期的准确性采用McNemar检验和卡方检验进行统计分析。结果PET-CT正确识别病理N分期23例(76.67%),2例被高估(6.67%)和5例被低估(16.67%),分期准确性为0.767。WB-DWI正确识别病理N分期26例(86.67%),1例被高估(3.33%)和3例被低估(10%),分期准确性为0.867,准确性差异无统计学差异。PETCT联合颅脑MRI正确分期20例(66.67%),3例被高估(10%)和7例被低估(23.33%),分期准确性为0.667。WB-DWI正确分期21例(70%),2例被高估(6.67%)和7例被低估(23.33%),分期准确性为0.7,准确性差异无统计学差异。结论WB-DWI对肺癌的分期诊断性能优于PET-CT联合颅脑MRI。 [关键词]磁共振成像;正电子发射断层扫描成像;全身弥散加权成像;肺癌;分期 引言男性肺癌发病率和死亡率均占所有恶性肿瘤的第一位,转移是恶性肿瘤发生和演变过程中最危险的阶段[1]。故肺癌准确地术前分期至关重要,不同的分期治疗方法也不尽相同。目前肺癌的术前分期主要依靠PET-CT和颅脑MRI。虽然PET-CT可作为金标准,但程序复杂,基层医院装备少。而作为类PET的全身磁共振弥散加权成像(Whole Body Diffusion Weighted Imaging, WB-DWI)简便易操作,且无辐射,较PET-CT便宜,已应用于肺癌的临床分期[2-3]。本研究通过WB-DWI与PET-CT及颅脑MRI的比较,评估WB-DWI在肺癌术前分期中的价值。 1 资料与方法1.1 一般资料收集本院2015年3月~2017年3月肺癌手术患者30例,30例患者均于两周内分别行颅脑MRI与WB-DWI检查,且均有上级医院PET-CT检查资料。30例患者通过告知检查事项并签署知情同意书。男23例,女7例,平均年龄62.27±2.29岁(38~82岁),其中鳞癌22例,腺癌6例,小细胞癌2例。25例患者行肺叶切除和周围淋巴结清扫,5例行肺楔形切除或肺段切除。TNM分期根据2009年第7版UICC标准[4]。 1.2 MRI扫描参数磁共振成像采用1.5 T扫描仪(Magnetom Avanto,Siemens)。WB-MRI采用短T1反转恢复平面回波(Short T1 Inversion Recovery Echo Planner Imaging,STIR-EPI) 序列;患者空腹取仰平卧位,头先进,平静呼吸,扫描范围自头颅至股骨上段,包括双侧腹股沟区,分8个部位进行扫描,激光标志线定位于下颌骨颏突水平,扫描完成后对8段原始图像进行无缝重组,然后利用3D-MIP重建及黑白反转技术进行三维重建。WB-DWI参数:TR=13800 ms,TE=76 ms,b值 为 50和 1000 s/mm2,FOV=450 mm,层厚5.0 mm,Matrix为340×340,扫描时间为808 s。 颅脑MRI扫描:仰卧位,头颅线圈放置,定位眶耳线,进行轴位平扫及增强扫描,造影剂为钆喷酸葡 胺(0.2 mmol/kg)。T2WI:TR=5000 ms,TE=96 ms,FOV=230 mm, 层 厚 5.0 mm,Matrix为 60×40;T1WI:TR=550 ms,TE=8.7 ms,FOV=230 mm, 层 厚 5.0 mm,Matrix为60×40,扫描时间为20 min。 1.3 图像分析WB-DWI图像的分期诊断由两位磁共振5年和3年诊断经验的影像科医生独立完成。两位医师再对患者的PETCT联合颅脑MRI资料进行分期诊断。如有分歧则协商后完成。两位医师除知晓肺癌的临床诊断外,对其它信息均未知。诊断标准为2009年第7版UICC的TNM分期标准,将WB-DWI和PET-CT联合颅脑MRI的分期结果分别与术后病理结果对照。 1.4 统计学分析统计分析使用STATA 13.1软件MP版。数据以平均值±标准差表示。全身DWI与PET-CT及颅脑MRI对肺癌分期的准确性采用McNemar检验和卡方检验,分别对敏感性、特异性、阳性预测值(Positive Predictive Value,PPV)和阴性预测值(Negative Predictive Value,NPV)进行比较。P<0.05表示有统计学意义。 2 结果PET-CT+颅脑MRI和WB-DWI的肺癌诊断图像,见图1。由PET-CT或WB-DWI检查获得的临床N分期(cN)及病理结果分析N分期(pN)之间的关系,见表1。PET-CT正确识别病理N分期有23例(76.67%),有2例被高估和5例被低估,分别占比为6.67%和16.67%,具有0.767的分期准确性。WB-DWI正确识别病理N分期有26例(86.67%),有1例被高估和3例被低估,分别占比为3.33%和10%,具有0.867的分期准确性。两者之间的准确性差异无统计学意义(P=0.125)。同样,WB-DWI检查与PET-CT之间在敏感性、特异性、阳性预测值、阴性预测值上没有显著性差异(表2)。 由PET-CT联合颅脑MRI或WB-DWI检查获得的肺癌临床分期(cS)及病理结果分析的肺癌临床分期(pS)之间的关系,见表3。PET-CT+颅脑MRI能正确地确定病理分期的有20例(66.67%),有3例被高估和7例被低估,分别占比为10%和23.33%,分期准确性为0.667。WB-DWI能正确地确定病理分期的有21例(70%),有2例被高估和7例被低估,分别占比为6.67%和23.33%,分期准确性为0.7。WB-DWI分期准确性为0.7,PET-CT联合颅脑MRI的分期准确性为0.667,两者之间的差异无统计学意义(P=0.157)。 图1 PET-CT+颅脑MRI和WB-DWI的肺癌诊断图像 注:患者为72岁男性右侧肺腺癌患者。通过WB-DWI临床诊断为cT2aN2M0(临床分期为IIIA),与PET-CT+颅脑MRI诊断相同;病理诊断有5组淋巴结转移,病理分期为pT2aN2M0(病理分期为IIIA);a、b、e图:b值=50 s/mm2;c、d、f图:b值=1000 s/mm2;g图:f图的黑白反转图;a图和c图箭头所指为不同b值下的腺癌;b图和d图箭头所指为不同b值转移淋巴结;e、f、g图右侧箭头所指为不同b值下的腺癌;e、f、g图左侧箭头所指为不同b值下的转移淋巴结。 表1 经由PET-CT或WB-DWI的临床诊断淋巴结分期与淋巴结病理分期的关系(例) 表2 肺癌的肺门及纵隔淋巴结在PET-CT或WB-DWI的诊断准确性评估(%) 注:*代表McNemar检验;#代表卡方检验。 表3 经由PET-CT或WB-DWI诊断的临床分期与病理分期的关系(例) 3 讨论本研究不仅使用了横断面轴位DWI扫描,且通过WB-DWI在冠状面重建中获得整体效果图,可显示除肿瘤病灶外的诸如血管瘤、肾囊肿、骨梗死等等良性病变。目前已有一些研究比较PET-CT扫描与WB-DWI诊断效能的优劣,指出WB-DWI在诊断脑转移和肝转移方面较PETCT要好[5],这是由于一些器官的高组织学FDG摄取掩盖了病灶的真实面目[6]。另一方面,WB-DWI在腹部和盆腔的影像诊断中,敏感性不如PET-CT[7]。因此,WB-DWI和PET-CT联合使用可以互补来提高诊断的性能。有研究指出,WB-DWI与PET-CT联合颅脑MRI能更加准确地论证肿瘤的临床分期[8],准确率接近98%。 研究发现WB-DWI对肺癌分期的诊断准确性高于PET-CT联合颅脑MRI(0.7>0.667),但两种检查方法没有统计学差异,因而可以认为两者的诊断性能相当。但由于PET-CT昂贵的价格,辐射损伤的影响,其普及率也不如MRI广泛,加上PET-CT对于脑转移的显示较差,必须用颅脑MRI作为辅助,因而可以认为WB-DWI具有更加便捷、直观且整体的统一性,检查方式优于PET-CT。同样我们在表1和表3中发现对于有淋巴结转移的患者,WB-DWI在诊断淋巴结转移方面高于PET-CT (表1中的WB-DWI 2例,PET-CT 0例),而对于有远处脑转移的患者差别不大(表3中两者均为3例),因而WB-DWI是一种有用的肺癌分期检查工具。 WB-DWI在显示远处转移性病变、恶性嗜铬细胞瘤和副神经节瘤等方面具有优势[9]。与PET-CT相比,WBDWI在卵巢癌患者中显示特征性的原发肿瘤灶,潜在病灶及远处病灶精度较高[10]。而本研究显示WB-DWI却与PET-CT诊断性能相当,这是由于远处转移的病例数较少,故无法引证上述研究。但却能显示在淋巴结转移诊断中的优越性。这与其他研究中,WB-DWI在淋巴瘤和消化道肿瘤的诊断性能与PET-CT相当[11],结果是一致的。但也有一些研究显示,WB-DWI在淋巴瘤和乳腺癌的诊断性能不如PET-CT[12]。因而,目前来说还没有统一的结论,需要进一步扩大样本量进行细致分组研究。 虽然PET-CT是作为肿瘤分期的首选影像学检查方法,但由于尘肺、矽肺、肺结核、结节病等病变,会对肺门和纵隔淋巴结的诊断产生假阳性结果,故对多个肺门和纵隔淋巴结FDG积聚的肺癌患者进行WB-DWI评价,可区分淋巴结的良恶性[13]。PET-CT同样可造成假阴性结果,比如在高分化肺腺癌的分期诊断中,PET-CT在淋巴结炎时可能显示假阳性,而在假阴性结果中的淋巴结可能含有少量的癌细胞[14]。这一结果和本研究中淋巴结分期诊断的结果是一致的(WB-DWI诊断准确率为86.67%>PET-CT的76.67%,同样特异性、阳性预测值和阴性预测值均高于PET-CT,见表2)。这也能为临床运用WB-DWI评价肺癌的淋巴结转移提供依据。 近年来,DWI可在动物模型的恶性转移淋巴结中区分炎症组织[15-16]。这使WB-DWI在评估肺结节和肿块方面比PET-CT更具有优势。WB-DWI中ADC值和信号强度可以区分良性和恶性纵隔淋巴结肿大,较PET-CT检查更具有数据说服力。因此,WB-DWI可成为肺癌分期评估的更有用的检查工具,其诊断性能优于PET-CT。 [参考文献] [1] Cossetti RJ,Bezerra RO,Gumz B,et al.Whole body diffusion for metastatic disease assessment in neuroendocrine carcinomas:comparison with OctreoScan® in two cases[J].World J Surg Oncol,2012,10:82. [2] Ohno Y,Koyama H,Onishi Y,et al.Non-small cell lung cancer:whole-body MR examination for M-stage assessment utility for whole-body diffusion-weighted imaging compared with integrated FDG PET/CT[J].Radiology,2008,248(2):643-654. [3] Heusch P,Köhler J,Wittsack HJ,et al.Hybrid [18F]-FDG PET/MRI including non-Gaussian diffusion-weighted imaging(DWI): preliminary results in non-small cell lung cancer(NSCLC)[J].Eur J Radiol,2013,82(11):2055-2060. [4] Asamura H,Chansky K,Crowley J,et al.The international Association for the Study of Lung Cancer Lung Cancer Staging Project: proposals for the revision of the N descriptors in the forthcoming 8thedition of the TNM classification for lung cancer[J].J Thorac Oncol,2015,10(12):1675-1684. [5] Kim HS,Lee KS,Ohno Y,et al.PET/CT versus MRI for diagnosis, staging, and follow-up of lung cancer[J].J Magn Reson Imaging,2015,42(2):247-260. [6] Schmidt GP,Kramer H,Reiser MF,et al.Whole-body MRI and FDG-PET/CT imaging diagnostics in oncology[J].Radiologe,2010,50(4):329-338. [7] Stecco A,Romano G,Negru M,et al.Whole-body diffusion weighted magnetic resonance imaging in the staging of oncological patients: comparison with positron emission tomography computed tomography (PET-CT) in a pilot study[J].Radiol Med,2009,114(1):1-17. [8] Plathow C,Aschoff P,Lichy MP,et al.Positron emission tomography/computed tomography and whole-body magnetic resonance imaging in staging of advanced nonsmall cell lung cancer-initial results[J].Invest Radiol,2008,43(5):290-297. [9] Laurent V,Trausch G,Bruot O,et al.Comparative study of two whole-body imaging techniques in the case of melanoma metastases: advantages of multi-contrast MRI examination including a diffusion-weighted sequence in comparison with PET-CT[J].Eur J Radiol,2010,75(3):376-383. [10] Michielsen K,Vergote I,Beeck K,et al.Whole-body MRI with diffusion-weighted sequence for staging of patients with suspected ovarian cancer: a clinical feasibility study in comparison to CT and FDG-PET/CT[J].Eur Radiol,2014,24(4):889-901. [11] Li B,Li Q,Nie W,et al.Diagnostic value of whole-body diffusion-weighted magnetic resonance imaging for detection of primary and metastatic malignancies: a meta analysis[J].Eur J Radiol,2014,83(2):338-344. [12] Heusner TA,Kuemmel S,Koeninger A,et al.Diagnostic value of diffusion-weighted magnetic resonance imaging (DWI)compared to FDG PET/CT for whole-body breast cancer staging[J].Eur J Nucl Med Mol Imaging,2010,37(6):1077-1086.[13] Maturu VN,Agarwal R,Aggarwal AN,et al.Dual-time point whole-body18F-fluorodeoxyglucose PET/CT imaging in undiagnosed mediastinal lymphadenopathy: a prospective study of 117 patients with sarcoidosis and TB[J].Chest,2014,146(6):216-220. [14] Usuda K,Zhao XT,Sagawa M,et al.Diffusion-weighted imaging is superior to PET in the detection and nodal assessment of lung cancers[J].Ann Thorac Surg,2011,91(6):1689-1695. [15] Xue HD,Li S,Sun HY,et al.Experimental study of in fl ammatory and metastatic lymph nodes with diffusion weighted imaging on animal model: comparison with conventional methods[J].Chin Med Sci J,2008,23(3):166-171. [16] Usuda K,Maeda S,Motono N,et al.Diagnostic performance of diffusion-weighted imaging for multiple hilar and mediastinal lymph nodes with FDG accumulation[J].Asian Pac J Cancer Prev,2015,16(15):6401-6406. Comparative Study of Whole Body Diffusion Weighted Imaging with PET-CT and Craniocerebral MRI in the Clinical Diagnosis of Lung Cancer Staging TAN Yanhuan, LI Junchen Abstract:ObjectiveTo determine whether the diagnostic performance of lung cancer staging by WB-DWI is superior to that of PETCT in combination with craniocerebral MRI.MethodsPET-CT in combination with craniocerebral MRI as well as WB-DWI were used for lung cancer patients before surgery. Among them, 22 were squamous cell carcinomas, 6 were adenocarcinomas and 2 were small cell lung cancer. The accuracy of lung cancer staging was analyzed by McNemar test and chi-square test.ResultsA total of 23 patients (76.67%) with pathological stage of N were correctly identified by PET-CT, with an estimated accuracy of 0.767. However, 2(6.67%) were over staged and 5 (16.67%) were under staged. 26 patients (86.67%) with pathological stage of N were correctly identified by WB-DWI, with an estimated accuracy of 0.867. However, 1 (3.33%) was over staged, and 3 (10%) were under staged. There was no statistical difference between the two detection rates. There were 20 (66.67%) cases who could correctly determine the pathological stage with PET-CT and brain MRI, and there were 3 (10%) over staging cases and 7 (23.33%) under staging cases, and the accuracy of staging was 0.667. There were 21 patients (70%) who could correctly be identified the pathological stage with WB-DWI, and there were 2 (6.67%) over staging cases and 7 (23.33%) cases were underestimated, the staging accuracy was 0.7. There was no statistical difference between the two detection rates.ConclusionWB-DWI is superior in staging diagnosis of lung cancer than PET-CT and brain MRI. Key words:magnetic resonance imaging; positron emission tomography; diffusion weighted imaging; lung cancer; staging [中图分类号]R445.2;R814.42 [文献标识码]B doi:10.3969/j.issn.1674-1633.2017.12.020 [文章编号]1674-1633(2017)012-0083-04 收稿日期:2017-07-01 通讯作者:李俊晨,副主任医师,主要研究方向为放射性脑损伤。 通讯作者邮箱:931903221@qq.com 本文编辑 王静 |