Descriptive data

Of the 59 patients, 25 were female and 34 male. 49 (83.05%) had left-sided hernias and 10 (16.95%) right-sided hernias. Mean o/e FLV was 27.4 ± 11.79%. Prenatally, 10.16% underwent FETO; postnatally, 58.18% required ECMO therapy. Patch repair was performed in 88.14%. Recurrence was diagnosed in 23.73%. For detailed information, see Table 1. Mean age at MRI was 24.75 ± 4.7 months (E1) and 124.60 ± 5.23 months (E2).

Prenatal lung volume

Higher o/e FLV correlated with higher postnatal PBF ipsilaterally (correlation coefficient r = 0.5073, p = 0.0082) and contralaterally (r = 0.3959, p = 0.0452) at E1, and ipsilaterally at E2 (ipsilateral: r = 0.342, p = 0.0342; contralateral: r = 0.1631, p = 0.5045), Fig. 1.

Fig. 1

Correlation between prenatal lung volume and PBF (ipsilateral and contralateral) at the E1 and E2. PBF, Pulmonary blood flow

Postnatal lung volume

Correlation analysis demonstrated an inverse relationship between postnatal lung volume and PBF at both time points (Fig. 2).

Fig. 2

Correlation between lung volume and PBF (ipsilateral and contralateral) at the E1 and E2. PBF, Pulmonary blood flow

At E1, a moderate statistically significant negative correlation was found contralaterally (r = −0.5047, p = 0.0003), whereas the ipsilateral correlation was weak and non-significant (r = −0.0843, p = 0.5687). Accordingly, higher lung volumes were associated with lower PBF, particularly on the contralateral side at E1.

At E2, the pattern shifted, a significant negative correlation was observed ipsilaterally (r = −0.4123; p = 0.0112), while the contralateral correlation was weaker and statistically non-significant (r = −0.2203; p = 0.1902). These findings suggest that negative correlations are present at both time points, with the side showing statistical significance differing between E1 and E2. Clinical factors, including ECMO (p = 0.5813) and FETO (p = 0.5548), showed no significant association.

Patch repair and hernia recurrence showed a non-significant trend towards reduced ipsilateral lung volume (patch repair p = 0.2954; presence of a hernia recurrence p = 0.3129). Additionally, contralateral lung volume was not associated with clinical outcome (recurrence p = 0.2277).

Patch repair showed no significant trend toward reduced ipsilateral lung volume (p = 0.0897) at E2. The influence on contralateral volume remained minor (p = 0.4198). The effects of ECMO therapy remained largely unchanged from E1 (ipsilateral p = 0.5707; contralateral p = 0.6198).

Pulmonary perfusion parameters at the E1

At E1, PBF was significantly lower on the ipsilateral side compared to the contralateral side (6.53 ± 27.77 mL/100 mL/min vs 88.32 ± 41.06 mL/100 mL/min, p < 0.0001), Fig. 3. Similarly, PBV was significantly reduced on the ipsilateral side (6.53 ± 2.47 mL/100 mL) compared to the contralateral side (8.78 ± 2.73 mL/100 mL, p < 0.0001), Fig. 3.

Fig. 3

Comparison of PBF and PBV (ipsilateral vs contralateral) at the E1 and E2. The boxplots illustrate the PBF and PBV for the ipsilateral and contralateral lungs at the E1 (left) and E2 (right). The whiskers represent the 95% confidence interval. PBF, Pulmonary blood flow; PBV, Pulmonary blood volume

In children with postnatal ECMO therapy, mean ipsilateral PBF was tendentially lower (58.31 ± 26.99 mL/100 mL/min) compared to children without ECMO therapy (71.89 ± 27.16 mL/100 mL/min), though not statistically significant (p = 0.0611).

Prenatal FETO therapy showed no significant PBF difference between ipsilateral and contralateral lungs (61.36 ± 14.34 mL/100 mL/min ipsilateral, p = 0.7485 vs 96.36 ± 35.98 mL/100 mL/min contralateral, p = 0.3988), nor compared to patients without FETO (63.68 ± 29.04 mL/100 mL/min ipsilateral, p = 0.7485 vs 87.39 ± 41.89 mL/100 mL/min contralateral, p = 0.3988).

In patients with patch repair, the mean ipsilateral PBF was tendentially lower (61.18 ± 27.49 mL/100 mL/min) than with primary suture repair (82.86 ± 24.59 mL/100 mL/min), without statistical significance (p = 0.0544). Contralaterally, no PBF difference was observed between patch and primary suture repair (61.18 ± 27.49 mL/100 mL/min vs 82.86 ± 24.59 mL/100 mL/min).

Patients with and without hernia recurrence, as well as those with and without reoperation for recurrence, showed no significant differences in PBF, Table 2.

Table 2 Pulmonary perfusion parameters and clinical endpoints at E1 and E2Pulmonary perfusion parameters at the E2

At E2, mean ipsilateral PBF was significantly lower than contralateral (62.04 ± 23.55 mL/100 mL/min vs 90.44 ± 33.41 mL/100 mL/min, p < 0.0001). PBV also remained significantly reduced on the ipsilateral side compared to the contralateral side (5.54 ± 2.29 mL/100 mL vs 7.66 ± 2.32 mL/100 mL, p < 0.0001), Fig. 3.

In children with postnatal ECMO, ipsilateral PBF was significantly lower than without ECMO (55.31 ± 20.6 mL/100 mL/min vs 72.77 ± 26.44 mL/100 mL/min, p = 0.0365), Fig. 4. Contralateral PBF tended to be lower after ECMO than without ECMO (84.7 ± 34.73 mL/100 mL/min vs 98.73 ± 33.76 mL/100 mL/min, p = 0.1198).

Fig. 4

PBF ipsilateral and ECMO at the E2. The boxplots display PBF under the influence of ECMO at the E2 examination. The whiskers represent the 95% confidence interval. ECMO, Extracorporeal membrane oxygenation; PBF, Pulmonary blood flow

No significant perfusion differences were found between children with and without prenatal FETO (Table 2).

In patch repair, ipsilateral PBF tended to be lower than with other repair types (58.67 ± 88.79 mL/100 mL/min vs 100.31 ± 39.13 mL/100 mL/min, p = 0.0623). Patients with hernia recurrence showed no significant differences in PBF, either ipsilateral or contralateral, nor did those require reoperation (Table 2). Hernia side (left vs right) had no relevant impact on lung perfusion (Table 2).

Intraindividual development of pulmonary perfusion parameters from E1 to E2 and the association of clinical parameters with the change in pulmonary perfusion parameters

Longitudinal analysis of pulmonary perfusion parameters from E1 to E2 revealed stable PBF ipsilateral (E1: 63.44 ± 27.77 mL/100 mL/min; E2: 62.04 ± 23.55 mL/100 mL/min, p = 0.8001) and contralateral (E1: 88.32 ± 41.06 mL/100 mL/min; E2: 90.44 ± 33.41 mL/100 mL/min, p = 0.7071).

PBV decreased significantly ipsilaterally (E1: 6.53 ± 2.47 mL/100 mL; E2: 5.54 ± 2.29 mL/100 mL, p = 0.0213), while contralateral values showed a nonsignificant decrease (E1: 8.78 ± 2.73 mL/100 mL; E2: 7.66 ± 2.32 mL/100 mL, p = 0.2263).

Hernia localization had no significant impact on PBF development (ipsilateral: p = 0.5123, contralateral: p = 0.1332). After prenatal FETO therapy, contralateral lung perfusion tended to decline compared to children without FETO (–24.92 ± 37.72 mL/100 mL/min vs 7.763 ± 48.99 mL/100 mL/min, p = 0.079, Table 3). A similar but nonsignificant trend was observed on the ipsilateral side (p = 0.0921).

Following ECMO, contralateral PBF decreased significantly (ECMO yes: −6.177 ± 55.1 mL/100 mL/min, ECMO no: 17.14 ± 34.8 mL/100 mL/min, p = 0.0435), while ipsilateral PBF remained unchanged (ECMO yes: −1.684 ± 27.28 mL/100 mL/min, ECMO no: 0.08947 ± 22.87 mL/100 mL/min, p = 0.7588), Table 3.

Other postnatal factors, such as hernia recurrence and reoperation, were associated with trends toward reduced lung perfusion without statistical significance (Table 3). For example, children with hernia recurrence showed ipsilateral decline of PBF (−6.84 ± 15.73 mL/100 mL/min; p = 0.1101) and a slight contralateral decrease (recurrence yes: −1.196 ± 27.53 mL/100 mL/min, recurrence no: 6.423 ± 54.67 mL/100 mL/min; p = 0.3579). Similar non-significant findings were seen in reoperated patients (reoperation yes: 2.82 ± 25.21 mL/100 mL/min, reoperation no: 4.77 ± 53.40 mL/100 mL/min; p = 0.6617).

Table 3 Pulmonary perfusion development from E1 to E2