Purpose or Case Report: To evaluate the utility of quantitative CT in children with neuroendocrine cell hyperplasia of infancy (NEHI)
Methods & Materials: All children with a confirmed NEHI (from 2005 to 2019) and typical CT imaging findings, agreed upon by two pediatric radiologists, were included. Typical CT appearance was defined as ground glass density in the middle lobe/lingula and centrally, with lucency of the lower lobes. Age-, sex-, and height-matched control CTs included those interpreted as normal in patients without acute or chronic respiratory conditions. Lung parenchyma was segmented into individual lungs and lobes using a semi-automated technique with open-source software. Mean lung density (MLD), ventilation heterogeneity (VH), lung mass, and volume were calculated. Descriptive data are presented as mean ± standard deviation. Nonparametric tests were used to evaluate group differences.
Results: 11 children with NEHI (7 boys, 20.3 ± 18.1 months) and 11 controls (7 boys, 19.5 ± 18.5 months) were included. Those with NEHI had lower MLD (-615 HU vs -549 HU, p = 0.02) with higher mass (232 gr vs 151 gr, p = 0.04) and volume (0.59 L vs 0.34 L, p = 0.008) compared to controls.

In the right middle lobe, the only significant difference was a higher mass in the NEHI cases compared to controls (32,9 g vs 19.6 g, respectively, p = 0.02); while in all other lobes, NEHI cases had lower MLD with higher VH, mass and volume. Significant differences by lobe were as follows:

Right upper lobe: NEHI had lower MLD (-628 HU vs -572 HU, p = 0.02) and higher VH (0.20 vs 0.16, p = 0.02); Right lower lobe: NEHI patients had lower MLD (-616 HU vs -511 HU, p = 0.005) and higher VH (0.22 vs 0.17, p = 0.01), mass (58.2 gr vs 37.2 gr, p = 0.04) and volume (0.15 L vs 0.07 L, p = 0.007).

Left upper lobe: NEHI patients had higher VH (0.21 vs 0.17, p = 0.02) and volume (0.14 L vs 0.08 L, p = 0.01); while in the left lower lobe, NEHI patients had a lower MLD (-599 HU vs -499 HU vs, p = 0.008), higher VH (0.23 vs 0.17, p = 0.01), and higher volume (0.13 L vs 0.07 L, p = 0.01)
Conclusions: Quantitative analysis of the typical NEHI CT pattern demonstrates significantly higher lung mass of the RML and higher VH and lower MLD (surrogates of air trapping) in the remaining lobes. Hence, quantitative CT in NEHI, shows that the typical CT findings represent a combination of the traditionally described ground glass opacities plus air trapping in the rest of the lobes (previously perceived as normal).