Walsh Caroline J, Nystrom Jered T, Silveira Lori J, Meyers Mariana L
University of Colorado Anschutz Medical Campus, 13001 E 17th Pl, Aurora, 80045, CO, USA.
Department of Radiology, University of Colorado School of Medicine, Aurora, CO, USA.
Pediatr Radiol. 2025 May;55(5):987-998. doi: 10.1007/s00247-025-06192-8. Epub 2025 Feb 20.
MRI is being increasingly used as a supplemental tool to ultrasound for prenatal diagnosis of fetal anomalies. Evidence suggests fetal MRI may aid in diagnosis and management of gastrointestinal abnormalities, though it is not widely used for this indication at this time. There is a lack of well-established nomograms of fetal colonic measurements by gestational age (GA) with MRI.
We aim to establish a nomogram of normal colonic and rectal size throughout the second and third trimesters by fetal MRI, starting at a younger GA than previously documented.
A retrospective study was performed. Fetal MRI databases spanning October 2010 to June 2021 were searched for examinations performed from 19 weeks GA to term. Cases were excluded for poor image quality or if a gastrointestinal abnormality was noted. Coronal and sagittal T1-weighted images were used to measure the ascending, transverse, descending, and sigmoid colon; rectosigmoid colon (at the level of the iliac crest); and rectum (at the distal third in the coronal views and at the base of the bladder and largest dimension in the sagittal views, at the orthogonal plane of the colon). Reproducible measurement areas for fetal bowel were established between two readers, and two-way mixed single-measure intra-class correlation coefficients (ICCs) were developed to assess inter-rater reliability. Growth curves were developed using generalized additive models. The main outcomes were the measurements at each section of the bowel and the predictor was GA. The curves of the fitted models were plotted for the estimated 10th, 25th, 50th, 75th, and 90th percentiles.
A total of 315 patients had at least one measurable bowel segment. If 100 or more measurements were obtained at a bowel segment, a nomogram was created. Due to limited available data prior to 20 weeks and after 36 weeks GA, bowel nomograms were developed for 20-36 weeks GA. The three bowel segments with the most included patients and greatest number of measurements obtained were the rectosigmoid colon at the iliac crest, distal one-third of the rectum, and the sigmoid colon (n = 251, 234, 178, respectively) with excellent reader agreement (ICC = 0.96, 0.90, 0.94, respectively). The range of bowel diameter increased with advancing GA at the 10th percentile through the 90th percentile in a nearly linear distribution at the sigmoid colon, rectum at the base of the bladder, and distal rectum and in a non-linear distribution at the rectum at the level of the iliac crest and descending colon.
Our study provides normative data for fetal colon and rectum measurements from 20 to 36 weeks GA on MRI. Radiologists can reliably measure the normal fetal colon and rectum on fetal MRI. Our nomogram of normal fetal bowel measurements provides radiologists and clinicians with data that can aid in the early recognition of bowel anomalies on fetal MRI.
磁共振成像（MRI）正越来越多地被用作超声的辅助工具，用于胎儿异常的产前诊断。有证据表明，胎儿MRI可能有助于胃肠道异常的诊断和管理，尽管目前它尚未广泛用于此适应症。目前缺乏通过MRI按孕周（GA）建立的完善的胎儿结肠测量列线图。
我们旨在通过胎儿MRI建立整个孕中期和孕晚期正常结肠和直肠大小的列线图，起始孕周比先前记录的更早。
进行了一项回顾性研究。检索了2010年10月至2021年6月的胎儿MRI数据库，查找从孕19周直至足月进行的检查。因图像质量差或发现胃肠道异常而排除病例。使用冠状位和矢状位T1加权图像测量升结肠、横结肠、降结肠和乙状结肠；直肠乙状结肠（在髂嵴水平）；以及直肠（在冠状位视图中的远端三分之一处，在矢状位视图中的膀胱底部且为最大尺寸，在结肠的正交平面处）。在两名阅片者之间确定了胎儿肠道可重复测量区域，并制定了双向混合单测量组内相关系数（ICC）以评估阅片者间的可靠性。使用广义相加模型绘制生长曲线。主要结果是肠道各节段的测量值，预测因素是孕周。绘制拟合模型的曲线，得出估计的第10、25、50、75和90百分位数。
共有315例患者至少有一个可测量的肠段。如果在一个肠段获得100次或更多测量值，则创建列线图。由于孕20周之前和孕36周之后可用数据有限，因此为孕20 - 36周建立了肠道列线图。纳入患者最多且测量次数最多的三个肠段是髂嵴水平的直肠乙状结肠、直肠远端三分之一以及乙状结肠（分别为n = 251、234、178），阅片者间一致性良好（ICC分别为0.96、0.90、0.94）。在乙状结肠、膀胱底部的直肠和直肠远端，肠道直径范围从第10百分位数到第90百分位数随孕周增加呈近似线性分布，而在髂嵴水平的直肠和降结肠呈非线性分布。
我们的研究提供了孕20至36周胎儿结肠和直肠MRI测量的规范数据。放射科医生可以在胎儿MRI上可靠地测量正常胎儿结肠和直肠。我们的正常胎儿肠道测量列线图为放射科医生和临床医生提供了有助于在胎儿MRI上早期识别肠道异常的数据。
