Klein H M, Klosterhalfen B, Kinzel S, Jansen A, Seggewiss C, Weghaus P, Kamp M, Töns C, Günther R W
Department of Diagnostic Radiology, University of Technology, Aachen, Germany.
J Comput Assist Tomogr. 1996 Mar-Apr;20(2):254-61. doi: 10.1097/00004728-199603000-00016.
Our goal was to assess the value of CT and MRI for the detection of bowel wall changes in experimentally induced mesenteric ischemia.
in 18 female pigs, a percutaneous embolization of the superior mesenteric artery was performed with buthyl-2-cyanoacrylate and Lipiodol (1:1) (experimental group). In six animals, only diagnostic imaging and histologic evaluation were performed (control group). CT was carried out 3, 6, and 12 h after occlusion. Incremental CT (1 s scan time, 5 mm slice thickness, 7 mm increment, 120 kV/290 mAs) and spiral CT (slice thickness 5 mm, pitch 1.5, 120 kV/165 mA) were performed pre and post contrast injection (Somatom Plus/Siemens). Serial CT was carried out after intravenous contrast injection (1 ml/kg, 2 ml/s). MRI (Magnetom 1.5 T; Siemens) was performed with T1 (pre and post 0.01 mmol/kg Gd-DTPA; Magnevist; Schering, Germany), T2, and proton density images in axial orientation. Slice thickness was 3 mm and slice gap 1 mm. Additionally, a T1-weighted GE sequence (multislice FLASH 2D) was obtained in dynamic technique (before and 30, 60, and 90 s after contrast agent injection) with a slice thickness of 5 mm. Biometrical monitoring included blood pressure, heart frequency, blood cell count, electrolyte status, blood gas analysis, and determination of serum lactate. Image evaluation included morphological analysis and determination of the enhancement pattern. Histological specimens were obtained and analyzed according to the Chiu classification.
The histologic workup of the specimen 3, 6, and 12 h after vascular occlusion revealed an average Chiu state 3, 4, and 5. On CT, the bowel wall had a thickness of 4.7 mm on average in the ischemic segments. There was a significant difference from the control group (average 3 mm). Free intraperitoneal fluid and intramural gas were seen after 12 h of ischemia in 80%. In ischemic bowel segments, no mural enhancement was seen. Normal segments and the bowel of the control animals showed an enhancement of 34 HU on average (SD = 3.1 HU; p.<0.01). In MRI, S/N and C/N differed significantly between experimental and control groups in T1 and proton density images. In ischemic segments of all phases, the bowel wall did not show contrast enhancement. Healthy segments and bowel of control animals showed a significant enhancement (p<0.01).
Cross-sectional imaging has a high sensitivity for delineation of ischemic bowel wall segments. The enhancement pattern of the bowel wall enables detection of location, extent, and cause of a acute arterial mesenteric ischemia with high accuracy in an early phase.
我们的目标是评估CT和MRI在检测实验性诱导的肠系膜缺血中肠壁变化的价值。
对18只雌性猪，用丁基-2-氰基丙烯酸酯和碘油（1:1）进行肠系膜上动脉的经皮栓塞（实验组）。对6只动物，仅进行诊断性成像和组织学评估（对照组）。闭塞后3、6和12小时进行CT检查。在注射对比剂前后分别进行增量CT（扫描时间1秒，层厚5毫米，层间距7毫米，120 kV/290 mAs）和螺旋CT（层厚5毫米，螺距1.5，120 kV/165 mA）（Somatom Plus/Siemens）。静脉注射对比剂（1毫升/千克，2毫升/秒）后进行系列CT检查。用MRI（Magnetom 1.5 T；Siemens）进行T1（注射0.01毫摩尔/千克钆喷酸葡胺前后；马根维显；德国先灵公司）、T2和轴向质子密度成像。层厚3毫米，层间距1毫米。此外，用动态技术（注射对比剂前及注射后30、60和90秒）获得T1加权GE序列（多层FLASH 2D），层厚5毫米。生物测量监测包括血压、心率、血细胞计数、电解质状态、血气分析和血清乳酸测定。图像评估包括形态学分析和强化模式的确定。获取组织学标本并根据Chiu分类法进行分析。
血管闭塞后3、6和12小时标本的组织学检查显示平均Chiu分级为3、4和5级。在CT上，缺血段肠壁平均厚度为4.7毫米。与对照组（平均3毫米）有显著差异。缺血12小时后，80%可见腹腔内游离液体和肠壁内气体。在缺血肠段未见肠壁强化。正常段和对照组动物的肠平均强化值为34 HU（标准差=3.1 HU；p<0.01）。在MRI中，实验组和对照组在T1和质子密度图像中的信噪比和对比噪声比有显著差异。在所有阶段的缺血段，肠壁均未显示对比剂强化。健康段和对照组动物的肠显示出显著强化（p<0.01）。
横断面成像对描绘缺血肠壁段具有高敏感性。肠壁的强化模式能够在早期高精度地检测急性动脉性肠系膜缺血的部位、范围和病因。
