多层螺旋CT扫描技术在胰腺癌诊断中的应用价值

【摘要】 目的 研究螺旋CT多期扫描技术在胰腺癌诊断中的临床应用价值。方法 88例胰腺癌患者行螺旋CT多期扫描，扫描时间为注射造影剂后18～25 s、40～45 s和60 s左右，比较正常胰腺组织和肿瘤在平扫和动脉期、胰腺期、门静脉期的增强变化。依照 CT征象诊断胰腺癌并行术前评估，并与手术结果比较。结果 正常胰腺组织在胰腺期的增强值明显高于其他两期 (F=12.22,P0.01);胰腺—病灶增强差值胰腺期高于其他两期 (F=14.91,P0.01)，肿块在胰腺期能够清晰显示。胰周血管在胰腺期显示满意，诸动脉在动脉期、胰腺期与门静脉期相比，差异有显著性(P0.01);诸静脉在胰腺期、门静脉期与动脉期相比差异有显著性(P0.01)。55例不可切除的肿瘤中，血管受侵者32例(58.18%),其中胰周小静脉扩张者19例(34.54%)。40例术前认为可切除的肿瘤，术中仍有7例不可切除。结论 多层螺旋CT双期扫描诊断胰腺癌，胰腺期和门静脉期应作为首选方案，具有非常重要的临床意义。

【关键词】 胰腺癌;X线计算机;体层摄影术;术前评估。

Abstract： Objective To investigate the clinical value of multislice spiral CT (MSCT) scanning in the diagnosis of pancreatic adenocarcinoma. Methods 88 patients with pancreatic adenocarcinoma underwent triple—phase spiral CT scanning 18—25 seconds, 40—45 seconds and 60 seconds after the injection of contrast medium for angiography. Normal pancreatic tissues and the tumor were compared by normal scanning and triple—phase spiral CT scanning so as to explore the variations in enhanced scanning. The diagnosis of pancreatic tumor was based on the MSCT findings, which were assessed preoperatively and later compared with the surgical results. Results Density difference of normal pancreas was greatest on images obtained in the pancreatic phase (F=12.22,P0.01); mean tumor—gland attenuation difference was the greatest on those obtained in the pancreatic phase (F=14.91,P0.01). Tumor and peripancreatic vasculature were well visualized in the pancreatic phase. For vessels detection, sensitivity of arteries obtained in the arterial and pancreatic phases was superior to that of those obtained in portal vein phase (P0.01); sensitivity of veins obtained in pancreatic and hepatic phases was better than that of those obtained in arterial phase (P0.01). Vascular invasion of 32 cases were detected among 55 unresectable cases (58.18%), of which 19 cases with expansion of small veins were detected (34.54%). Of 40 cases which had been preoperatively diagnosed as resectable, 7 cases were not resectable during operation. Conclusion In the diagnosis of pancreatic adenocarcinoma by dual—phase spiral CT, pancreatic and portal vein phases should be selected as the first scheme, which has very important value in clinical application.

Key words： pancreatic adenocarcinoma; X—ray computer; tomograghy; preoperative assessment。

随着多层螺旋 CT扫描技术的飞速发展以及在临床上的广泛应用，图像分辨率明显改善，对胰腺癌诊断的准确率和术前的准确评估水平已得到很大提高。但胰腺癌的早期诊断和分期迄今仍是难题，无论采用何种检查手段，高质量的图像显示胰腺、病灶及周围结构是提高诊断率的关键。目前，动态螺旋CT对胰腺癌的诊断准确率大于90%[1]。我们利用螺旋 CT扫描速度快、可选择扫描时相的特点，对胰腺进行多期扫描研究，目的在于探索一种简单易行的扫描方案，旨在提高胰腺癌的诊断准确率和术前的准确评估水平。

1 资料和方法。

1.1 一般资料 本组88例，男 50例，女 38例，年龄32～88岁，平均 53.7岁。肿瘤位于胰头或胰颈部 59例，胰体部 17例，胰尾部12例。 59例经手术病理证实，其中33例为可切除性肿瘤。29例经CT及临床诊断后仅行姑息性治疗。

1.2 设备及扫描技术 使用Siemens Sensition16螺旋CT扫描仪。扫描参数为：130 kV,120 mAs，螺距1.15，扫描层厚3～5 mm，使用Wared工作站进行图像处理。检查前空腹4～6 h、检查前30 min口服1.5%泛影葡胺400 ml，扫描前再口服相同浓度造影剂300 ml,先平扫确定胰腺位置及病灶范围。增强扫描用Ommipaque 100 ml对比剂，经上肢静脉由高压注射器4 ml/s注入。分别于注射增强剂后18～25 s、40～45 s、60 s左右行动脉期、胰腺期及门静脉期扫描。

1.3 图像分析 正常胰腺组织有丰富的动脉血供和密集毛细血管网，动脉期和胰腺期实质显著强化;而胰腺癌由于结缔组织增生和相对血供不足，必然产生一定的增强密度差异[2—3]。我们分别测定平扫、动脉期、胰腺期及门静脉期正常胰腺组织与肿瘤的CT值。兴趣区(ROI)大小为5 mm×5 mm，肿瘤CT值测定为肿块实性部分，坏死或囊性部分除外。各期所测定层面应尽量保持一致，以便于比较。在动脉期、胰腺期及门静脉期观察胰周血管的显影情况(包括腹主动脉、腹腔干、肝总动脉、肠系膜上动脉、脾动脉、门静脉、脾静脉、肠系膜上静脉及胰周小静脉)，观察其形态、位置、边缘改变等。胰腺及肿瘤在动脉期、胰腺期及门静脉期的 CT值分别减去平扫CT值，即为正常胰腺和肿瘤在动脉期、胰腺期、门静脉期的CT增强值。动脉期、胰腺期和门静脉期肿瘤与周围正常胰腺CT值的差值，即为胰腺—病灶增强差值。依据Diehl等[4]制定的标准，所有图像由3位经验丰富的CT室医师诊断、分析并行可切除性判断，并与手术结果比较(图1～4)。

1.4 统计学处理 采用方差分析( F检验)及q检验，对胰腺各期的CT增强值、胰腺—病灶增强差值进行统计学分析。P0.05认为差异有显著性。