Reproducibility of fetal lung‐to‐head ratio in left diaphragmatic hernia across the North American Fetal Therapy Network (NAFTNet)

Abstract

Objective To determine the antenatal sonographic lung area measurement method in left congenital diaphragmatic hernia (CDH) with the highest interrater agreement among North American Fetal Therapy Network (NAFTNet) centers within and outside the fetoscopic tracheal occlusion (FETO) consortium and in comparison with a European “expert” reviewer (ER). Methods Nineteen members from nine FETO consortium centers and 29 reviewers from 17 non‐FETO centers reviewed ultrasound clips of the chest from 13 fetuses with isolated left CDH and were asked to select a static plane for lung area measurement using anteroposterior (AP), longest, and trace methods. Interrater agreement in lung area measurements was determined using intraclass correlation coefficient (ICC). Bland‐Altman analysis was used to evaluate mean difference (bias) between NAFTNet reviewers and ER. Results Among FETO centers, agreement was highest using trace (ICC 0.94; 95% CI, 0.83‐0.98), followed by longest (ICC 0.89; 95% CI, 0.75‐0.97) and lowest for A‐P (ICC 0.83; 95% CI, 0.67‐0.94). Similar trends were noted in non‐FETO centers. When compared with ER, bias was lowest for trace: 14 ± 38 mm2 and 19 ± 36 mm2 for FETO and non‐FETO centers, respectively. Conclusion The trace method demonstrated the highest interrater agreement and lowest bias for lung area estimation in left CDH across NAFTNet.

Variability in antenatal prognostication of fetal diaphragmatic hernia across the North American Fetal Therapy Network (NAFTNet)

“…The critical landmarks of a true axial plane and 4‐chamber view of the heart should be described. A single lung area measurement method should be used, specifically the trace method, as it was demonstrated to have the highest inter‐rater agreement , and caution must be taken to avoid inclusion of extra‐pulmonary tissue while tracing fetal lung area. The optimal fetal position for the trace method should be specified with the fetal spine at 3 or 9 o'clock depending on fetal presentation, with the contralateral lung closest to the transducer.…”

“…However, other contributing factors may include the use of LHR, rather than o/e LHR, the use of different sonographic lung area measurement methods, and the variable implementation of US protocols for prognostication of prenatally diagnosed CDH. When the current group of authors evaluated inter‐rater agreement in lung area estimation among physicians within the North American Fetal Therapy Network (NAFTNet), poor inter‐rater agreement was demonstrated among participants for image quality rating of sonographic clips in isolated left CDH . This lack of agreement among fetal medicine specialists highlights a potential gap in implementation of universal image selection criteria across NAFTNet.…”

“…When the current group of authors evaluated interrater agreement in lung area estimation among physicians within the North American Fetal Therapy Network (NAFTNet), poor inter-rater agreement was demonstrated among participants for image quality rating of sonographic clips in isolated left CDH. 12 This lack of agreement among fetal medicine specialists highlights a potential gap in implementation of universal image selection criteria across NAFTNet. The absence of a standardized approach to antenatal CDH prognostication may directly impact patient care, as demonstrated in a recent study by Britto et al, 13 which found that the use of a standardized protocol for o/e LHR improved the accuracy in predicting neonatal mortality.…”

Prenatal treatment of severe congenital diaphragmatic hernia: there is still medical equipoise

“…One of the criticisms often raised is that the current assessment and counseling algorithms were never, or are no longer, appropriate. Indeed, the ultrasound criteria for severe hypoplasia have been criticized widely, for the outdated nature of the data, the unstandardized neonatal management 18,27,34 , the poor reproducibility and variability in measurement methods and timing 35,36 , the restriction of lung-size measurement to the contralateral lung in a two-dimensional, rather than three-dimensional, plane 37 and/or the failure to take into account other biomarkers 38 . We believe, however, that all recent observational studies in Western countries, using standardized lung measurement and management methods, have continued to confirm the relationship between o/e LHR and survival ( Figure 1) 18,[39][40][41][42] .…”

Prenatal assessment of congenital diaphragmatic hernia at north american fetal therapy network centers: A continued plea for standardization

“…In practice, several methods for lung area measurement exist, including the trace, longest axis (LA), and antero‐posterior (AP) methods 17,18 . The trace method has demonstrated the best reproducibility and its adoption has been urged by the North American Fetal Therapy Network (NAFTNet, https://www.naftnet.org/) and beyond 17,19‐21 . Similar variability in practice surrounds fetal MRI practice: percent predicted lung volume (PPLV) and o/e TFLV have been reported from different institutions with a variety of methods to calculate the results 11‐13,22 .…”