Department of Radiology, Division of Neuroradiology and Musculoskeletal Radiology, Medical University Vienna, Vienna, Austria.
Ultrasound Obstet Gynecol. 2011 Dec;38(6):695-700. doi: 10.1002/uog.8973. Epub 2011 Feb 28.
To characterize the normal development of the female external genitalia on fetal magnetic resonance imaging (MRI).
This retrospective study included MRI examinations of 191 female fetuses (20-36 gestational weeks) with normal anatomy or minor abnormalities, following suspicion of anomalies on prenatal ultrasound examination. Using a 1.5-Tesla unit, the bilabial diameter was measured on T2-weighted sequences. Statistical description, as well as correlation and regression analyses, was used to evaluate bilabial diameter in relation to gestational age. MRI measurements were compared with published ultrasound data. The morphological appearance and signal intensities of the external genitalia were also assessed.
Mean bilabial diameters, with 95% CIs and percentiles, were defined. The bilabial diameter as a function of gestational age was expressed by the regression equation: bilabial diameter = - 11.336 + 0.836 × (gestational age in weeks). The correlation coefficient, r = 0.782, was statistically significant (P < 0.001). Bilabial diameter on MRI was not significantly different from that on ultrasound (P < 0.001). In addition, on MRI we observed changes in morphology of the external genitalia and in signal intensities with increasing gestational age.
We have provided a reference range of fetal bilabial diameter on MRI, which, in addition to ultrasound findings, may be helpful in the identification of genital anomalies.
描述女性胎儿外生殖器在磁共振成像（MRI）上的正常发育过程。
本回顾性研究纳入了 191 例经产前超声检查怀疑存在异常的解剖结构正常或存在轻微异常的女性胎儿（20-36 孕周）的 MRI 检查结果。在 1.5T 磁共振仪上，于 T2 加权序列上测量阴唇直径。采用统计描述、相关性和回归分析等方法，评估阴唇直径与胎龄的关系。将 MRI 测量值与已发表的超声数据进行比较。还评估了外生殖器的形态外观和信号强度。
定义了阴唇直径的平均值、95%置信区间和百分位数。阴唇直径与胎龄的关系可由回归方程表示：阴唇直径=-11.336+0.836×（孕周）。相关系数 r=0.782，具有统计学意义（P＜0.001）。MRI 上的阴唇直径与超声上的无显著差异（P＜0.001）。此外，我们在 MRI 上观察到随着胎龄的增加，外生殖器的形态和信号强度发生了变化。
我们提供了胎儿阴唇直径在 MRI 上的参考范围，该范围除了超声检查结果外，可能有助于识别生殖器异常。
