Centro di Medicina Fetale, Dipartimento Assistenziale Integrato Materno-Infantile, Azienda Ospedaliero-Universitaria Careggi, Firenze, Italia.
Ultrasound Obstet Gynecol. 2010 Oct;36(4):423-6. doi: 10.1002/uog.7615.
To evaluate the effect of tissue harmonic imaging (THI) on the measurement of fetal nuchal translucency thickness (NT).
One-hundred and three pregnant women underwent first-trimester NT measurement according to The Fetal Medicine Foundation criteria. NT was evaluated using conventional ultrasonography (CUS) and THI without modifying any other ultrasound parameter (e.g. gain). For each patient three images with CUS and three images with THI were stored and then measured independently on the ultrasound system by two different operators. The maximum measurements using CUS and THI were compared. Differences between the values of CUS and THI NT measurements were tested using the Wilcoxon signed-rank test. Bland-Altman plots were constructed, and intraobserver and interobserver variabilities were assessed by calculation of the intraclass correlation coefficient. Probability values of < 0.05 were considered significant.
Mean maternal age was 32.8 (range, 20-42) years, mean gestational age at examination was 12 + 1 (11 + 0 to 13 + 6) weeks and mean crown-rump length (CRL) was 55.8 (SD, 7.2) mm. Median fetal NT was 1.4 (0.8-3.5) mm using CUS and 1.2 (0.6-3.3) mm using THI (P < 0.001) for the first operator. A second operator remeasured the first 51 cases: median fetal NT was 1.4 (0.8-3.8) mm using CUS and 1.1 (0.6-3.1) mm using THI (P < 0.001). Fetal NT measurements were above the expected median value according to CRL in 49 cases (47.6%) using CUS and in only 24 cases (23.3%) using THI.
THI leads to a small, but significant, reduction of the NT measurement and this could reduce the sensitivity of screening for Down syndrome.
评估组织谐波成像（THI）对胎儿颈项透明层（NT）测量的影响。
103 名孕妇根据胎儿医学基金会标准进行了早孕期 NT 测量。使用常规超声（CUS）和不改变任何其他超声参数（如增益）的 THI 评估 NT。每位患者的 CUS 和 THI 各存储 3 个图像，然后由两名不同的操作员在超声系统上独立测量。比较 CUS 和 THI 的最大测量值。使用 Wilcoxon 符号秩检验检验 CUS 和 THI NT 测量值之间的差异。绘制 Bland-Altman 图，并通过计算组内相关系数评估观察者内和观察者间的可变性。概率值 < 0.05 被认为具有统计学意义。
平均产妇年龄为 32.8（范围 20-42）岁，检查时的平均孕周为 12+1（11+0 至 13+6）周，平均头臀长（CRL）为 55.8（标准差 7.2）mm。使用 CUS 测量的中位数胎儿 NT 为 1.4（0.8-3.5）mm，使用 THI 测量的中位数胎儿 NT 为 1.2（0.6-3.3）mm（P < 0.001），对于第一位操作员。第二位操作员重新测量了前 51 例：使用 CUS 测量的中位数胎儿 NT 为 1.4（0.8-3.8）mm，使用 THI 测量的中位数胎儿 NT 为 1.1（0.6-3.1）mm（P < 0.001）。在 49 例（47.6%）中，根据 CRL 测量，胎儿 NT 值高于预期中位数，而在仅 24 例（23.3%）中，使用 THI 测量。
THI 导致 NT 测量值略有下降，但有统计学意义，这可能会降低唐氏综合征筛查的敏感性。
