Prenatal diagnosis of fetal respiratory function: evaluation of fetal lung maturity using lung-to-liver signal intensity ratio at magnetic resonance imaging.
Bottom Line: Lung-to-liver signal intensity ratio correlated significantly with advancing gestational age (R = 0.35, p < 0.001).The non-SRD group had higher LLSIR compared with the SRD group (2.15 ± 0.30 vs. 1.53 ± 0.40, p < 0.001).The fetal LLSIR on T2-weighted images is an accurate marker to diagnose the fetal lung maturity.
Affiliation: Department of Obstetrics and Gynecology, Kanazawa Medical University, Uchinada, Japan.Show MeSH
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Mentions: Magnetic resonance imaging examinations of the 110 cases (118 examinations) were carried out during the 22nd to 40th week of gestation (32.6 ± 3.6 weeks, mean ± SD). In 18 of 118 examinations, LLSIR was calculated by two examiners to confirm the reproducibility. For examiner 1 (Y. O.), the LLSIR range was 0.860–3.36 (median, 2.04; mean, 1.98). For examiner 2 (M. R.), the LLSIR range was 0.851–3.44 (median, 2.03; mean, 2.00). The concordance was confirmed by Wilcoxon signed-rank test (p < 0.001). Figure 2 shows the different images of lung and liver on T2-weighted MRI between non-SRD case and SRD case, respectively. The relationship between LLSIR and gestational age for non-SRD subjects is shown in Figure 3. The best fit for LLSIR of normal lung was represented by the regression line Y = 0.040X + 0.88 (r = 0.35; p < 0.001), in which Y is LLSIR and X is gestational age in weeks (Figure 3). In the eight cases in which MRI was carried out twice, the LLSIR increased with the advancing gestational age (Table 3). The mean gestational age at MRI of non-SRD cases, which intervals from MRI to delivery were within 14 days, was 34.1 ± 3.2 weeks (median 34.8 weeks, range 24–37 weeks). The mean LLSIR was 2.2 ± 0.3 (Figure 4). In non-SRD group, LLSIR varied from 1.5 at the 28th week of gestation to 2.8 at the 37th week of gestation. The mean gestational age at MRI of the SRD cases in which interval from MRI to delivery was within 14 days was 33.7 ± 5.5 weeks (median 35.0 weeks, range 25–40 weeks). In this group, the mean LLSIR was 1.5 ± 0.4, which is significantly lower than the normal group (p < 0.001) (Figure 4). The LLSIR of SRD cases varied from 0.9 at the 34th week of gestation to 2.0 at the 36th week of gestation. In fetuses of similar gestational age, the LLSIR of SRD cases was usually less than the LLSIR of non-SRD cases.
Affiliation: Department of Obstetrics and Gynecology, Kanazawa Medical University, Uchinada, Japan.