Winter T C, Reichman J A, Luna J A, Cheng E Y, Doll A M, Komarniski C A, Nghiem H V, Schmiedl U P, Shields L E, Uhrich S B
Department of Radiology, University of Washington Medical Center, Seattle, WA 98195-7115, USA.
Radiology. 1998 Apr;207(1):215-22. doi: 10.1148/radiology.207.1.9530318.
To determine whether the frontal lobe is disproportionately smaller than normal in second-trimester fetuses with Down syndrome by using prenatal ultrasonographic (US) measurements of the frontothalamic distance (FTD).
The FTD, measured from the inner table of the frontal bone to the posterior margin of the thalamus, was measured in 43 fetuses (mean gestational age, 17.2 weeks +/- 1.3 [standard deviation]; range, 15.0-20.4 weeks) with chromosomally proved trisomy 21 and in 160 chromosomally normal fetuses (mean gestational age, 17.1 weeks +/- 1.5; range, 14.5-22.5 weeks). Other cranial biometric ratios also were calculated.
The FTD was best predicted from the estimated gestational age (EGA) in the euploid population with the quadratic equation FTD = -0.0120 x EGA2 + 0.6917 x EGA - 5.2349 (R2 = .731) or from the biparietal diameter (BPD) with the linear equation FTD = 0.6837 x BPD + 0.5525 (R2 = .731). If an observed-to-expected ratio of 0.84 is used as a cutoff sign to screen for trisomy 21, a sensitivity of 16%, specificity of 97%, odds ratio of 6.03 (95% confidence interval, 1.81, 20.1), and relative risk of 5.98 are achieved.
The frontal lobe is statistically significantly smaller in fetuses with trisomy 21. US measurement of the FTD may prove to be a useful adjunctive screening tool if used with other markers for Down syndrome.
通过产前超声测量额丘距离（FTD），确定孕中期唐氏综合征胎儿的额叶是否比正常胎儿明显更小。
测量了43例经染色体检查证实为21 -三体的胎儿（平均孕周17.2周±1.3[标准差]；范围15.0 - 20.4周）以及160例染色体正常胎儿（平均孕周17.1周±1.5；范围14.5 - 22.5周）从额骨内板到丘脑后缘的FTD。还计算了其他颅骨生物测量比率。
在整倍体人群中，根据估计孕周（EGA）用二次方程FTD = -0.0120×EGA² + 0.6917×EGA - 5.2349（R² = 0.731）或根据双顶径（BPD）用线性方程FTD = 0.6837×BPD + 0.5525（R² = 0.731）能最好地预测FTD。如果将观察值与预期值的比率0.84作为筛查21 -三体的临界值，灵敏度为16%，特异性为97%，优势比为6.03（95%置信区间，1.81, 20.1），相对风险为5.98。
21 -三体胎儿的额叶在统计学上明显更小。如果与其他唐氏综合征标志物一起使用，超声测量FTD可能是一种有用的辅助筛查工具。
