第第 六六 篇篇消化系统消化系统 第第 一一 章章消化系统总论消化系统总论组成消化道（胃肠道：食管、胃、十二指肠、空肠、回肠、结肠和直肠）消化腺（器官：肝脏、胆道系统、胰腺） 第一节第一节 消化道消化道一、常用影像学检查方法（一）、X线检查 1、透视（Fluoroscope）：目前较少应用2、腹部平片（Plain film） ：仰卧前后位、站立位较常用 （二）、钡剂造影（barium contrast examination ）Ø消化道疾病的消化道疾病的首选首选影像学检查方法影像学检查方法Ø造造影影剂剂————医医用用硫硫酸酸钡钡，，疑疑有有胃胃肠肠道道穿穿孔孔时时，，禁禁用用硫硫酸钡，可改用有机碘水溶液对比剂酸钡，可改用有机碘水溶液对比剂Ø造影前病人的准备造影前病人的准备总总原原则则: : 使使所所检检查查部部位位之之消消化化道道呈呈洁洁净净、、空空虚虚状状态态 方法传统法（硫酸钡加水调制成不同浓度混悬液口服或肠道灌注）：少用气钡双重造影（钡液和气体共同在胃腔内形成影像）：常用 （二）、钡剂造影（barium contrast examination ）粘膜相、充盈相、加压相 （二）、钡剂造影（barium contrast examination ）造影范围与充填钡剂方式的选择：Ø食管、胃、小肠主要采用口服钡剂法(“钡餐”)Ø结肠主要采用钡剂灌肠法 （三）、血管造影（ Angiography ）Ø适应症: 腹部肿瘤、血管性病变、胃肠道出血Ø方法：选择性动脉造影、超选择性动脉造影 周围器官结构的继发性改变（腹膜、血管、淋巴结、实质脏器、腹水等）管腔外的异常消化道管壁本身的改变CT扫描可以显示（四）、CT（Computed tomography）在消化道肿瘤的分期、消化道急腹症、肠系膜病变评价方面提供更多信息。
可实现对肿瘤性病变的早期诊断、功能评价、临床分期和预后评估 （四）、CT（Computed tomography） （四）、CT（Computed tomography） （四）、CT（Computed tomography） （四）、CT（Computed tomography） （四）、CT（Computed tomography）ＣＴ仿真内镜检查——用于结直肠病变的早期筛查 Normal appearance of digestive tractObservations:Mucosa: traveling, smoothness, continuity, widthWall: flexibility, thicknessLumen: size, diastolic and contractionTube: location, mobility EsophagusDefinition: The muscular tube between the hypopharynx and the stomach,which is divided into three sections:neck,chest and abdomen.Normal shape: Band-shaped ,smooth outline,2-3 cm in widthMucosal folds: Parallel striped shadow, width <2mm4 physiological stenosis: Esophagus entrance, compression of aortic knuckle, compression of left main bronchus, diaphragmatic hiatus3 compressions：：Compression of aortic knuckle, compression of left main bronchus, compression of left atrium1、 barium contrast examination filling viewmucosal view mucosal view mucosal foldMucosal ditch Normal esophagus, three physiological pressure trace 2、CTEsophagus is round soft tissue in chest CT cross-section, it’s located in front of the thoracic and thoracic aorta, in the rear of trachea, carina, left main bronchus and left atrial. Stomach and duodenum1、barium contrast examination PartitionFundusbodyAntrumCommon nameLesser curvaturegreater curvatureangular incisureCardiaPylorus Normal gastric type: steer horn , fishhook, cascade, asthenic steer horn fishhook asthenic cascade Antrum: parallel folds or sometimes oblique <3mm in widthLesser curvature: parallel with lesser curvatur, 3 ~ 4mm in widthFundus: wider, reticular folds <5mm in width Greater curvature: transverse, oblique folds, width <5mmMucosal folds——black and white streak shadow Mucosal foldsMucosal ditchMucosal folds double contrast view- Fine relief: Gastric folds disappear, gastric area and gastric sulcus displayed. Gastric area is 1~3mm in diameter, appear to fish net. Gastric sulcus is <1mm in width, appear to thin lineGastric areaGastric sulcus Movement: *peristalsis------fundus, body *moving as a whole ------ antrumEmptying :2~4hour Duodenum is C-shaped and divided into cap, descending, horizontal and ascending segment，with pancreatic head in it DuodenumCap/bulb1st segment2nd segment3rd segment Cap .triangular shape with apex right pointing posteriorly and superiorly .parallel mucosal folds .moving as a whole1st – 3rd segment .c- shaped .feathery mucosal fold .peristalsis*duodenal papilla 2、CT and MRIGastric wall thickness can be observed, and its enhancement Jejunum and ileum 1、 barium contrast examination Distribution : upper jejunum--- left upper abdomen lower jejunum--- left middle abdomen upper ileum------ right middle abdomen middle ileum------right middle and lower abdomen lower ileum-------pelvic regionMucosal folds: jejunum : feathery appearance ileum: smooth tubular appearance (folds decrease in number from jejunum to ileum)Peristalsis: jejunum : Active and, mostly mucosal view ileum: Slow and weak, mostly filling viewEmptying: 7~9 hour mucosal viewfilling view CT ColonMorphology : haustra, semilunar folddecreases in number from ascending colon to descending colonMucosal folds: longitudinal , transverse, oblique foldMovement: moving as a wholeEmptying: generally 24 to 48 hours1、 barium contrast examination filling viewmucosal viewdouble contrast view double contrast view CT Abnormal patterns on x-ray filmbarium contrast examination1 1. calibre change Narrowing: persistent/constant, not transitory (Inflammatory, cancer, external pressure, spasms )Distention: persistent/constant, not transitory 2.changes of outline(1). Filling defectArea can not be filled by barium sulfate owe to lesion arising from wall of digestive tract occupies the space of lumen. .en face --- radiolucent area .in profile – area without barium sulfate Filling defect Filling defect Filling defect concave lesion in the wall of digestive tract en face --- area collected with barium sulfate in profile --- area projecting outwards with barium sulfate(2). niche en facein profile niche in lesser curvature (3). diverticulum：outwards saccular projection with barium sulfate due to localized weakness or outside pulling of digestive tract wall Øoutwards saccular projection with barium sulfate from lumenØ peristalsisØnormal mucosal fold in itØshape can change diverticulum 3.changes of mucosa(1).(1). Mucosa destruction： Disappearance of normal mucosa replaced by irregular barium spots or dotsMucosa destructionNormal mucosa Mucosa destruction (2).Flattened mucosa: Mucosal folds lighter or disappear completely inflammation or edema in mucosal or submucosal layer(3).Tortuous and widened mucosa: Mucosal fold thickening, often accompanied by tortuosity (varices and chronic gastritis )Tortuous and widened mucosa (4). mucosa convergence / gathering: mucosa folds radiate to the lesionBenign convergence: regular, radial, tapering to the tip, can reach lesionsMalignant convergence: uneven distribution, tip was clubbed, suddenly interrupted 5.Changes of functionTension change: increased, reducingChanges of peristalsis: increase, decrease and disappearPower：accelerate, slow down, do not emptyingSecretion change: hyperthyroidism, retention CT and MRI1.Wall thickening and Tumor2.2.Wall density or signal3.3.Mesenteric vascular changes and abnormal lymph nodes 第二节第二节 肝肝 胆胆 胰胰 脾脾一、常用影像学检查方法 CT、MRI 二、正常解剖影像学表现第二肝门平面第二肝门平面CTCT图像与相应解剖示意图图像与相应解剖示意图 肝门平面肝门平面CTCT图像与相应解剖示意图图像与相应解剖示意图 胆囊平面胆囊平面CTCT图像与相应解剖示意图图像与相应解剖示意图 肾门平面肾门平面CTCT图像与相应解剖示意图图像与相应解剖示意图 （一）、肝脏1、外形及肝叶、肝段划分肝脏以三条肝V、肝内门V左、右支和肝裂为解剖标志划分为8个肝段 2、肝脏血管（（1 1）肝动脉造影表现）肝动脉造影表现 动脉期: 显示肝A及各级分支由粗渐细,走行自然、规则、边缘光整 实质期: 肝脏密度呈普遍均匀性增高 静脉期: 肝内静脉→肝右、肝中、肝左静脉→第二肝门→下腔静脉肝动脉造影：动脉期、毛细血管期、实质期 （（2 2）肝内门静脉系统）肝内门静脉系统3、肝实质（（1 1））CTCT表现表现1）平扫：呈均匀软组织密度，CT值为40-65Hu，略高于脾、胰、肾，肝内门静脉和肝静脉血管密度低于肝实质，显示为管道状或圆形影 2）增强扫描：Ø动脉期：肝A明显强化，肝实质无强化Ø门静脉期：门V、肝V强化明显, 实质开始强化Ø门脉晚期/肝实质期：肝实质达强化峰值动脉期门静脉期肝实质期 （（2 2））MRIMRI表现表现平平扫扫：：SE序列T1W相肝实质呈均匀中等信号；T2W呈低信号；脂肪呈高信号；血管为黑色“流空”信号；液体在T1低，T2高（长T1、长T2）Gd-Gd-增增强强扫扫描描：：肝实质呈均匀强化，肝血管也强化明显，而胆管无强化 T1WIT2WIMRIMRI平扫平扫 MRIMRI增强增强动脉期门静脉期肝实质期 （二）、胆道系统（（1 1））CTCT表现表现1、胆囊 （（2 2））MRIMRI表现表现T1WIT2WI CTCT表现表现2、胆管树 MRIMRI表现表现T1WIT2WI （三）、胰腺CTCT平扫表现平扫表现Ø呈突向腹侧的带状影，自胰头至胰尾逐渐变细小Ø胰腺呈软组织密度，老年萎缩呈羽毛状Ø胰管不显示或小于1~3mm，胆总管小于1cm CTCT增强表现增强表现Ø胰腺均匀强化，实质血供丰富Ø A期胰周动脉和胰腺实质明显强化Ø V期门V、脾V、肠系膜上V强化,胰腺实质密度降低 （四）、脾CTCT表现表现Ø平扫时，脾脏密度均匀，稍低于肝脏Ø增强扫描，动脉期迅速强化，呈花斑脾，门脉及延迟期强化均匀MRIMRI表现表现ØT1WI呈均匀稍低信号，略低于肝脏，T2WI呈稍高信号Ø增强扫描强化特点类似于CT 三、基本病变的影像学表现（一）、肝脏1、肝脏大小与形态异常（1）肝脏增大：弥漫性肝病和肝内较大的占位性病变（2）肝萎缩：全肝体积缩小，常有变形（3）肝脏变形：表现为一个肝叶增大，而另一肝叶萎缩 肝脏增大 肝萎缩 2、肝实质异常（1）局灶性肝实质异常： 1）病灶形态：圆形、类圆形，良性边界光滑，恶性边界不清 2）病灶大小：差异很大 3）病灶数目：转移瘤、囊肿、血管瘤常多发 4）病灶质地：囊肿CT呈水样密度，MRI呈T1低T2高信号；脓肿可出现气液平和呈分隔状；肿瘤CT常呈稍低密度，MRI常呈T1稍低，T2稍高信号 5）病灶强化特点：囊肿不强化；脓肿环状强化；HCC动脉期明显强化，呈“快进快出”；肝海绵状血管瘤动脉期边缘强化，呈“快进慢出” 6）周围管道结构异常：肝癌造成门静脉、肝静脉癌栓；良性病变推移压迫其周围血管； 肝囊肿 肝囊肿 肝海绵状血管瘤 肝海绵状血管瘤 HCC 肝转移瘤 （2）弥漫性肝实质改变： 1）病因：肝硬化、脂肪肝等 2）表现：体积增大或萎缩、实质不均匀、增强CT表现为门脉周围环状低密度 肝硬化 肝硬化 脂肪肝 脂肪肝 3、肝血管异常（1）解剖变异（2）病理性异常：继发于肝脏肿瘤对血管的直接侵蚀而出现的一系列改变，如肿块造成血管受压移位；肿瘤对血管的浸润，血管狭窄闭塞；肿瘤血管；肿瘤供血动脉的增粗迂曲；充盈缺损；静脉早显，多见于动静脉瘘 门静脉明显增粗 门静脉早显 门静脉受压推移 门静脉充盈缺损 肿瘤供血动脉的增粗迂曲 （二）、胆道系统的异常影像学征象1、管腔大小改变：发育异常造成先天性扩张，其他原因造成管腔狭窄、阻塞或完全中断2、管壁改变：均匀增厚或不均匀、结节状增厚，增强可见强化3、管腔内容物异常：胆汁成分发生变化或腔内出现其他病理性组织。
胆管扩张 胆管扩张 胆囊壁增厚 （三）、胰腺的异常影像学征象1、形态异常：各部比例失调，多见于胰腺肿瘤；胰腺肿大丰满，多见于急性胰腺炎；胰腺萎缩，常见于慢性胰腺炎；胰腺边缘毛糙模糊，常见于急性胰腺炎2、实质异常：囊性病灶（囊肿、坏死、囊性肿瘤等），CT呈水样密度，MRI呈T1低信号、T2高信号；胰管结石、CT呈高密度；胰腺实性占位，CT呈稍低密度，MRI呈T1稍低、T2稍高信号3、胰管异常：胰腺肿留、慢性胰腺炎可造成胰管扩张 胰腺肿瘤，胰管扩张 胰腺炎 胰管扩张，胰管结石 （四）、脾脏的异常影像学征象1、脾脏增大：2、数目与位置改变：主要有多脾、副脾、无脾和脾脏异位3、脾实质异常：（1）低密度：囊肿、脾梗死等（2）稍低或等密度：各类实性肿瘤（3）稍高或高密度：出血、错构瘤或钙化（4）病灶强化：海绵状血管瘤“快进慢出”；转移瘤环状强化；梗死、囊肿无强化 脾脏增大 副脾 。