Hertzberg B S, Kliewer M A, Bowie J D
Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
Radiology. 1997 Dec;205(3):813-6. doi: 10.1148/radiology.205.3.9393540.
To investigate the implications of mistaking the medial surface of the cerebral hemisphere for the medial wall of the lateral ventricle at antenatal ultrasonography (US) and to identify US clues that might help avoid this interpretive error.
In 50 second- and third-trimester fetuses, a directed attempt was made to demonstrate the medial surface of the cerebral hemisphere and the medial wall of the lateral ventricle on images that depicted the lateral wall of the ventricle. In each fetus, measurements of the diameter of the false ventricular atrium were compared with the true diameter of the lateral ventricle to assess the potential magnitude of error.
The average diameter measured with the medial surface of the cerebral hemisphere was 10.7 mm, compared with the true mean ventricular diameter of 6.2 mm. This value was greater than or equal to 10 mm (the generally accepted upper limit of normal for the ventricular diameter) in all 15 third-trimester fetuses and in 16 (46%) of 35 second-trimester fetuses. The parietal occipital fissure was demonstrated along the medial surface of the cerebral hemisphere in 36 (72%) of 50 fetuses, and the medial surface of the cerebral hemisphere could be traced posteriorly around the occipital lobe in 45 (90%).
When ventriculomegaly is suspected, the examiner should make a direct attempt to find the medial wall of the ventricle and distinguish it from the medial boundary of the cerebral hemisphere. Correct identification of the anatomic interfaces is facilitated by demonstrating that the cerebral interface contains the parietal occipital fissure and can be traced posteriorly around the occipital lobe.
探讨产前超声检查（US）时将大脑半球内侧面误认作侧脑室内壁的影响，并识别可能有助于避免这种解释错误的超声线索。
在50例孕中期和孕晚期胎儿中，在描绘脑室侧壁的图像上，有针对性地尝试显示大脑半球内侧面和侧脑室内壁。对每个胎儿，将假性脑室房的直径测量值与侧脑室的真实直径进行比较，以评估误差的潜在大小。
大脑半球内侧面测量的平均直径为10.7mm，而侧脑室的真实平均直径为6.2mm。在所有15例孕晚期胎儿以及35例孕中期胎儿中的16例（46%）中，该值大于或等于10mm（脑室直径通常公认的正常上限）。50例胎儿中有36例（72%）在大脑半球内侧面显示出顶枕裂，45例（90%）大脑半球内侧面可沿枕叶向后追踪。
当怀疑脑室扩大时，检查者应直接尝试寻找脑室的内壁，并将其与大脑半球的内侧边界区分开来。通过显示大脑界面包含顶枕裂且可沿枕叶向后追踪，有助于正确识别解剖界面。
