Three-dimensional reconstruction of defects in congenital diaphragmatic hernia: a fetal MRI study

Abstract

Objective: To assess the clinical feasibility and validity of fetal magnetic resonance imaging (MRI)-based three-dimensional (3D) reconstruction to locate, classify and quantify diaphragmatic defects in congenital diaphragmatic hernia (CDH).

Methods: This retrospective study included 46 cases of CDH which underwent a total of 69 fetal MRI scans (65 in-vivo and four postmortem) at the Medical University of Vienna during the period 1 January 2002 to 1 January 2017. Scans were performed between 16 and 38 gestational weeks using steady-state free precession, T2-weighted and T1-weighted sequences. MRI data were retrieved from the hospital database and manual segmentation of the diaphragm was performed with the open-source software, ITK-SNAP. The resulting 3D models of the fetal diaphragm and its defect(s) were validated by postmortem MRI segmentation and/or comparison of 3D model-based classification of the defect with a reference classification based on autopsy and/or surgery reports. Surface areas of the intact diaphragm and of the defect were measured and used to calculate defect-diaphragmatic ratios (DDR). The need for prosthetic patch repair and, in cases with repeated in-vivo fetal MRI scans, diaphragm growth dynamics, were analyzed based on DDR.

Results: Fetal MRI-based manual segmentation of the diaphragm in CDH was feasible for all 65 (100%) of the in-vivo fetal MRI scans. Based on the 3D diaphragmatic models, one bilateral and 45 unilateral defects (n = 47) were further classified as posterolateral (23/47, 48.9%), lateral (7/47, 14.9%) or hemidiaphragmatic (17/47, 36.2%) defects, and none (0%) was classified as anterolateral. This classification of defect location was correct in all 37 (100%) of the cases in which this information could be verified. Nineteen cases had a follow-up fetal MRI scan; in five (26.3%) of these, the initial CDH classification was altered by the results of the second scan. Thirty-three fetuses underwent postnatal diaphragmatic surgical repair; 20 fetuses (all of those with DDR ≥ 54 and 88% of those with DDR > 30) received a diaphragmatic patch, while the other 13 underwent primary surgical repair. Individual DDRs at initial and at follow-up in-vivo fetal MRI correlated significantly (P < 0.001).

Conclusions: MRI-based 3D reconstruction of the fetal diaphragm in CDH has been validated to visualize, locate, classify and quantify the defect. Planning of postnatal surgery may be optimized by MRI-based prediction of the necessity for patch placement and the ability to personalize patch design based on 3D-printable templates. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Keywords: CDH; CDH classification; CDH typology; MRI; MRI-based segmentation; congenital diaphragmatic hernia; fetal MRI; fetal diaphragm.

Figure 1

Flowchart summarizing cases reviewed, inclusion and exclusion criteria and characterization of study population of fetuses with congenital diaphragmatic hernia (CDH) undergoing magnetic resonance imaging (MRI).

Figure 2

ITK‐SNAP user interface (version 3.6.0)14: software used for manual in‐vivo MRI‐based segmentation in fetuses with congenital diaphragmatic hernia. Segmentation of diaphragm (red) and diaphragmatic defect (yellow), defined as axial plane at level of xiphoid, was performed in three orthogonal planes (coronal, axial and sagittal), enabling 3D reconstruction (bottom left). A, anterior; L, left; P, posterior; R, right.

Figure 3

1.5‐T steady‐state free precession sagittal MRI of two fetuses with congenital diaphragmatic hernia at 31 + 2 (a,b) and 31 + 0 (c,d) gestational weeks, with (b,d) and without (a,c) superimposed segmentation. (a) Diaphragm can be delineated as continuous black line between hyperintense lung and less hyperintense liver and heart. (b) Diaphragm is shown with superimposed segmentation (red). (c) Anterior aspect of diaphragm is intact and is demarcated by hyperintense herniated stomach and less hyperintense liver, but posterior part cannot be delineated. Hyperintense tubular structures in thoracic cavity represent small‐bowel herniation. (d) Superimposed segmentations of intact anterior portion of diaphragm (red) and posterior diaphragmatic defect (yellow) are shown.

Figure 4

In‐vivo fetal MRI‐based 3D segmentation model of diaphragm (red) and diaphragmatic defect (yellow) in fetus with congenital diaphragmatic hernia with left posterolateral defect at 37 + 5 gestational weeks, shown cranially (a), caudally (b), left cranially (c) and left caudally (d). a, anterior; l, left; p, posterior; r, right.

Figure 5

Schematic illustration of fetal MRI‐based classification system for congenital diaphragmatic hernia. (a) Normal diaphragm (red) and surrounding bony structures (gray) seen from cranially. (b–f) If diaphragmatic defect (blue) is present, it is first classified as left‐ or right‐sided, then categorized according to location as posterolateral (b), lateral (c), anterolateral (d) or hemidiaphragmatic (e). If more than one defect is present (f), each defect is classified individually; in this case, classification yields one left‐sided lateral and one right‐sided posterolateral defect.

Figure 6

In‐vivo fetal MRI‐based segmentation models (diaphragm red, defect yellow) of four different cases of congenital diaphragmatic hernia at gestational ages of 32 + 5 (a), 31 + 0 (b), 27 + 1 (c) and 26 + 4 (d) weeks, classified as follows: left lateral (a); left posterolateral (b); left hemidiaphragmatic (c); and bilateral (d), further classified as one left‐sided and one right‐sided lateral defect.

Figure 7

Postmortem fetal MRI provides excellent contrast and allows precise characterization of fetal thoracic anatomy, particularly fetal diaphragm. (a,b) T2‐weighted 1.5‐T in‐vivo (a) and 3.0‐T postmortem (b) coronal MR images in fetus with congenital diaphragmatic hernia at 22 + 3 (a) and 23 + 5 (b) gestational weeks. (c,d) Corresponding 3D segmentation models based on in‐vivo (c) and postmortem (d) fetal MRI.

Figure 8

Fetal MRI segmentation‐based 3D printed model of diaphragm (yellow), diaphragmatic defect (magenta), liver (gray, translucent) and inferior vena cava and hepatic veins (blue) from 37 + 5‐week fetus with congenital diaphragmatic hernia with left posterolateral defect: ventral (a), dorsal (b), left lateral (c) and cranial (d) views.

Figure 9

Box‐and‐whiskers plot showing defect–diaphragmatic ratios (DDR) of fetuses with congenital diaphragmatic hernia which underwent diaphragmatic patch repair (n = 20) and those which underwent primary surgical repair (n = 13). Boxes and internal lines are median and interquartile range, and whiskers are range.