探讨三维超声扩展剖面容积成像（OVIX）在胎儿脊髓圆锥末端定位中的作用。

2014年10月至2015年5月在广西壮族自治区妇幼保健院行产前系统超声检查的胎儿127例，其中正常胎儿122例，脊柱裂胎儿5例，孕周范围20~30周，应用三维超声采集胎儿脊髓圆锥末端容积数据，利用扩展剖面容积成像重建圆锥末端对应椎体至其至少5个以上椎体段脊柱冠状面并定位圆锥末端位置；对正常胎儿于新生儿期第28天随访其神经系统发育情况，对脊柱裂胎儿引产后行病理检查，以扩展剖面容积成像定位的脊髓圆锥末端位置为标准，对比正常胎儿脊髓圆锥末端位置与脊柱裂胎儿脊髓圆锥末端位置的差异。

127例胎儿中120例（94.5%，120/127）脊髓圆锥末端被定位，7例（3例因孕妇肥胖、4例因胎儿体位原因，均为正常胎儿）未能定位脊髓圆锥末端位置，115例正常胎儿脊髓圆锥末端位于L₃及L₃以上，5例脊柱裂胎儿脊髓圆锥末端位置均在L₄以下，其中2例位于L₅，2例位于S₁，1例位于S₃；扩展剖面容积成像对脊柱裂胎儿脊髓圆锥末端定位结果与引产后病理诊断结果一致。

扩展剖面容积成像能同时显示骨性标志第12肋、T₁₂及脊髓圆锥末端，利用T₁₂顺推脊髓圆锥末端位置，可准确定位胎儿脊髓圆锥末端位置，为产前评估脊柱裂病变提供有价值的影像学信息。

To explore the role of Oblique View eXtended (OVIX) method in three-dimensional (3D) ultrasound in positioning the fetal conus medullaris terminal.

In this study, 122 normal fetuses and 5 fetuses with spinal bifida at 20^th to 30^th gestation week from October 2014 to May 2015 in our consultation were included after a system ultrasound examination. The conus medullaris terminal of 3D volume data was collected. OVIX was used to form the coronal section of spine which contained conus medullaris terminal and at least above 5 vertebral bodies and position conus medullaris terminal. The development of nervous system of the normal fetuses was followed up till postnatal 28 days. According to the pathological diagnosis of spinal bifida cases after induced labor, the position of conus medullaris terminal in normal cases and spinal bifida cases was compared.

The fetal conus medullaris terminal could be located in 120 cases (94.5%, 120/127), while the conus medullaris terminals of 7 normal cases were failed to be located, including due to pregnant obesity in 3 cases and due to fetus position in 4 cases. The conus medullaris terminal was positioned in L₃ or above L₃ in 115 normal fetuses, below L₄ in 5 abnormal fetuses including in L₅ in 2 cases, in S₁ 2 in cases, and in S₃ 1 in case. OVIX results were consistent with the pathological diagnosis in the 5 abnormal cases.

OVIX could simultaneously display the osseous marks including 12^th rib, T₁₂ and the conus medullaris terminal. The fetal conus medullaris terminal can be exactly positioned by OVIX method, which may provide valuable imaging information for prenatal evaluation of spinal bifida.