正常胸腺和胸腺病变的CT表现培训课件

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,本文档所提供的信息仅供参考之用，不能作为科学依据，请勿模仿；如有不当之处，请联系网站或本人删除。,Content,胸腺病变的,CT,表现,3,正常胸腺的,CT,表现,2,概述,1,Content胸腺病变的CT表现3正常胸腺的CT表现2概述1,胸腺是一种复杂的淋巴上皮器官，具有调节细胞免疫的功能，在人类正常免疫中是不可缺少的。,CT,及,MR,在胸腺异常的诊断中有重要作用，有利于评价是否正常及胸腺病变的范围。,概述,1,胸腺是一种复杂的淋巴上皮器官，具有调节细胞免疫的功能，在人类,正常,CT,表现（形态、大小、密度）,胚胎发育,正常胸腺解剖位置及异位胸腺,正常胸腺的,CT,表现,2,正常CT表现（形态、大小、密度）胚胎发育正常胸腺解剖位置及异,胎儿第,6,周，胸腺起源于第三及第四咽囊；,第,7,周，胸腺始基延长并呈圆柱状形态，形成胸腺咽管，逐渐移行至前纵隔；,第,8,周，胸腺始基于下极融合；,第,10,周，肝脏组织及骨髓内的小淋巴样细胞移行至胸腺始基；,第,1416,周，胸腺进一步分化形成皮质及髓质成分。,胚胎发育,胎儿第6周，胸腺起源于第三及第四咽囊；胚胎发育,正常胸腺解剖位置,位于前上纵隔，上达胸廓入口（甚至突入颈部接近甲状腺下缘），下至心包前面上部，两侧临近纵隔胸膜，后面贴附心包及左头臂静脉及主动脉弓。,胸腺的位置上界不超过胸骨柄上缘，下缘不超过左心室上缘或主动脉根部层面，外缘不超过上腔静脉、主动弥弓外缘其前缘位置正常可随周围结构改变而向左或向右移位。,正常胸腺解剖位置 位于前上纵隔，上达胸廓入口（甚至,正常胸腺解剖,A,B,正常胸腺解剖AB,异位胸腺,Ectopic and accessory thymic tissue may occur anywhere along the path of descent(thymopharyngeal duct)as the result of failure of descent,sequestration,or failure to involute.Ectopic or accessory thymic tissue may be found in,the vicinity of the superior vena cava,brachiocephalic vessels,and,aorta,.Rarely,it may be found in the,posterior mediastinum,or even in the,dermis,.,异位胸腺Ectopic and accessory thym,异位胸腺,Figure 1.,Normal thymus with a cervical component in a 12-year-old boy.,(a),Sagittal ultrasonographic(US)image shows the mediastinal and cervical components of the thymus(black arrows)attached to the lower pole of the thyroid(white arrow)via the thyrothymic ligament(arrowhead).Note the“starry sky”appearance of the thymus;this is created by hyperechoic fat against the background of the remaining hypoechoic lymphoid tissue.,(b),Corresponding anatomic drawing shows the mediastinal(arrowheads)and cervical(arrows)components of the thymus.,A,B,异位胸腺Figure 1.Normal thymus wi,异位胸腺,Figure 2.,Cervical component of the thymus in a 3-year-old boy with a strong maternal family history of papillary thyroid carcinoma.The cervical component was misinterpreted as an“exophytic tumor of the thyroid gland.”Contrast-enhanced CT scans show a normal mediastinal thymus(arrows in,A,)and its cervical component(arrows in,B,).Follow-up studies 2 years later showed no change,and the patient remained asymptomatic.,A,B,异位胸腺Figure 2.Cervical compone,异位胸腺,Figure 3.,Ectopic parapharyngeal thymus in a 7-week-old boy with a“mass”in the right mandib-ular angle.Coronal contrast materialenhanced T1-weighted magnetic resonance(MR)image shows an enhancing parapharyngeal mass(arrow),which is isointense relative to the mediastinal thymus(arrowhead).At needle biopsy,the mass was proved to be ectopic thymic tissue.,异位胸腺Figure 3.Ectopic paraphar,正常,CT,表现（形态）,9,岁以下多呈方形或梯形，,10,岁以后随年龄变化较大,。,正常CT表现（形态）9岁以下多呈方形或梯形，10岁以后随年龄,正常,CT,表现（大小）,胸腺的形态随年龄而异，年轻人（特别是,25,岁以下者）的正常胸腺的大小和,重量有较大的差异。,国内研究学者认为胸腺的厚度随年龄变化，变化最大是在,20-49,岁之间，总体来说是从大到小再到大，大于,60,岁有增大趋势；,60,岁，可超过,30mm,。宽度则随年龄增大而增大。,正常CT表现（大小）胸腺的形态随年龄而异，年轻人（特别是25,正常,CT,表现（密度）,在,6-19,岁,人群中胸腺的,CT,密度与肌肉相同或稍高，,CT,值,约为,30Hu,。,由于随年龄增加腺体遂渐消失而代之以脂肪，故,从青,春期至,25,岁期间,，以前外凸的外缘变得扁平或内陷，,CT,值比肌肉低。,25,岁后,胸腺进一步萎缩，不再能见到明确的软组织密度,的胸腺结构，但可见在较丰富的脂肪背景上软组织密度,岛，萎缩的速度和程度因人而异。在,83%,的小于,50,岁的,人群中还可见正常胸腺。,此后,前纵隔完全脂肪化，但大部分人还可见到密度稍高于,脂肪的残存的纤维性胸腺框架。,正常CT表现（密度）在6-19岁人群中胸腺的CT密度与肌肉相,NORMAL or ABNORMAL?,On the basis of this review,we have drawn the following conclusions regarding the appearance of the thymus gland and the detection of thymic abnormalities:,The thymus gland is largest at puberty,and its overall size does not change significantly with age.It occupies essentially all of the mediastinal compartment anterior to the aortic arch,superior vena cava,and great vessels throughout life.,2.After puberty,parenchymal atrophy within the gland occurs,with the greatest percentage of parenchymal replacement by fat occurring between the ages of 31 and 40.,3.After age 40,the presence of a spherical or oval focal soft-tissue mass within the thymus gland usually represent a neoplasm.,4.Before age 40,differentiation of a small thymoma from normal residual thymic parenchymal tissue may be impossible on the basis of size alone.,5.At all ages,a thymoma usually produces a focal bulge in the normally smooth adjacent visceral-pleural surface.,Moore,A.V.,et al.,Age-related changes in the thymus gland:CT-pathologic correlation.AJR Am J Roentgenol,1983.141(2):p.241-6.,NORMAL or ABNORMAL?On the bas,（二）肿瘤病变,（一）非肿瘤病变,1.,胸腺增生,2.,胸腺淋巴样（滤泡性）增生,3.,胸腺囊肿,1.,胸腺上皮细胞肿瘤：胸腺瘤,2.,胸腺非上皮性肿瘤,（,1,）胸腺淋巴瘤,（,2,）胸腺类癌,（,3,）胸腺脂肪瘤,（,4,）纵隔生殖细胞瘤,胸腺病变的,CT,表现,3,（二）肿瘤病变（一）非肿瘤病变1.胸腺增生1.胸腺上皮细胞肿,1.,胸腺增生,胸腺真性增生,的定义是胸腺变大，但是组织结构维持正常的，只是大小超过同一年龄段正常的上限，,不涉及任何病理性质的胸腺改变,。胸腺真性增生常常见于机体遇到各种应激事件，免疫处于较大的挑战时期，比如肿瘤的化疗、放疗，皮质醇激素治疗，烧伤等应激事件，以后部分患者可恢复到正常大小。,常合并内分泌异常，如特发性甲状腺肿、格雷病（甲状腺中毒）和肢端肥大症。,胸腺弥漫性增大，但仍维持正常形态，两缘对称，呈光滑的不分叶的外形，,CT,值与正常者相似。,（一）非肿瘤病变,1.胸腺增生 胸腺真性增生的定义是胸腺变大，但是组织结,Case 2,胸腺真性增生，,14,岁，男。原发性,T,细胞淋巴瘤化疗后。,Case 1,胸腺真性增生，,29,岁，女性患者，合并,Graves,病。,A.,胸腺体积轻度增大，边缘略膨隆。,B,。经治疗,3,年后，胸腺体积缩小如正常。,Case 2 胸腺真性增生，14岁，男。原发性T细胞淋巴瘤,2.,胸腺淋巴样（滤泡性）增生,好发于青壮年，多为,15-35,岁女性。常见于重症肌无力（M,G,）患者，,65%,左右,重症肌无力,病人显示有淋巴滤泡性胸腺增生。它也被称为,自家免疫性“胸腺炎”,，较真性胸腺增生多见，此时，,胸腺的大小和质量正常，但髓质扩张，而皮质受损,。,胸腺可正常或增大，常是在,M,G,病人行胸腺切除中发现并诊断的。据报道，在患,M,G,并经