胎儿磁共振成像-胎儿头颅MRI检查

Comparison of antenatal and postnatal MR findings in 39 of 42 live born infants
Complete agreement 23 (59%)
Disagreement
Excluded fetal MRI Revealed additional abnormalities
Craniocaudal diameter
Craniocaudal diameter (perpendicular to fastigial point-declive line)
28-week fetus
The craniocaudal diameter of vermis measures 10.9mm (equivalent of 22 weeks). The expected measurement is 14.8mm.
胎儿磁共振成像
MR Imaging of the Fetus
• 超声－Ultrasound --母体肥胖
--羊水过少 --妊娠中晚期胎头增大 --胎儿颅骨骨化
• MRI－Ultrafast MRI
--单次激发快速序列 --大来自百度文库OV --安全性？
MRI仅适用于当产前超声不足以解决临床问题时
MRI检查技术
36-week fetus
枕大池蛛网膜囊肿
29-week fetus
5-month
孕32周，外院超声提示左脑室扩张、枕大池积水
孕31周，超声提示：可疑侧脑室增宽
育不良，大枕大池，蛛网膜囊肿
小脑蚓部的发育
• • • • 11－12W，小脑及原始蚓部从第四脑室嘴侧发生 13－14W，原始顶点可见（第四脑室顶部裂缝） 14－16W，小脑蚓部原裂出现 16W，小脑蚓部向尾侧发育，于顶点处“折叠” 覆盖四脑室顶，第四脑室“闭合” • 16－17W，锥前裂、顶前裂等可见 • 18－19W，蚓部颅尾方向长度与小脑半球相等
Tengmento-vermian angle
Normal
Abnormal
22－week fetus
A. axial sonography showed a large cystic posterior fossa with small cerebellar hemispheres. B. the tegmento-vermian angle is increased with the fourth ventricle uncovered . The vermis is very small; there is no primary fissure or fastigial point. C. Diagrammatic representation of DWC. D. the cerebellar hemispheres are small.The ventricular system is dilated, resulting in large temporal horns
11－12W
13－14W
16W
18W
17.5w
21w
22w
24w
27w
Assessment of Vermian Maturity
• • • • 小脑原裂 primary fissure 顶点 fastigial point 顶－蚓角tengmento-vermian angle，TVA 颅尾径 craniocaudal diameter，CCD
• 1.5T及以下MR机 • 体部相共振线圈 • 序列：单次激发FSE(0.5NEX） FIASTA序列 • 常规轴、冠、矢扫描
胎儿头颅MRI检查
• 胎儿头颅MR检查主要观察
--脑室扩大 --可疑后颅窝异常 --胼胝体发育不良
Total fetuses 90
MRI abnormal 60 (67%)
22－week fetus
Sonography and MRI findings are similar to the previous case except that the cerebellar hemispheres seems larger and vermian tisse can be seen in the midline.
The transcerebellar diameter is also small.
孕28＋3周，B超提示胎儿脑室扩张
12.3mm 9.8mm
14.9mm
上下蚓比
• 小脑蚓部胚胎期呈线性协调发育 • 以顶点为分界上下蚓比例为47％和53％，不随 生长发育变化
23-week fetus
大枕大池
16 (41%)
6 (15%) 10 (26%)
Limperopoulos C, et al. AJR Am J Roentgenol 2008; 190:1637–1643.
• 枕大池(cisterna magna)正常值2－11mm • 侧脑室体部<10mm • 异常表现：Dandy-Walker 畸形，小脑蚓部发