正常胸腺及胸腺病变的ct表现 吕晓飞.ppt

正常胸腺及胸腺病变—CT表现 The Normal and Abnormal Thymus —— CT imaging finding
南方医院影像中心
2009级博士研究生
吕晓飞
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
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
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14~16周,胸腺进一步分化形成皮质及髓质成分。
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、。
正常胸腺解剖
A
B
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
Figure 1. Normal thymus with a ponent in a 12-year-old boy. (a) Sagittal ultrasonographic (US) image shows the mediastinal and ponents 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 2. ponent of the thymus in a 3-year-old boy with a strong maternal family history of papillary thyroid carcinoma. The ponent was misinterpreted as an “exophytic tumor of the thyroid gland.” Contrast-enhanced CT scans show a normal mediastinal thymus (arrows in A) and its ponent (arrows in B). Follow-up studies 2 years later showed no change, and the patient remained asymptomatic.
A
B