S2569
Radiobiology – Normal tissue radiobiology
ESTRO 2026
Ambrosio 4 , Crescenzo D'Alterio 4 , Stefania Scala 4 , Roberto Pacelli 5 , Laura Cella 1 1 Institute of Biostructures and Bioimaging, National Research Council, Napoli, Italy. 2 UOSD Fisica Sanitaria e Radioprotezione, University Hospital Federico II, Napoli, Italy. 3 Department of Veterinary Medicine and Animal Production, Federico II School of Medicine, Napoli, Italy. 4 Microenvironment Molecular Targets, Istituto Nazionale Tumori- IRCCS- Fondazione G. Pascale, Napoli, Italy. 5 Department of Advanced Biomedical Sciences, , Federico II School of Medicine, Napoli, Italy Purpose/Objective: Chicken embryos are a well-established alternative animal model for developmental and toxicological research, including radiation studies. Historical data show that whole-body X-irradiation (2–3 Gy) induces morphological abnormalities such as growth retardation and limb deformities [1]. High-resolution magnetic resonance imaging (hMRI) provides a non- invasive, non-destructive method for monitoring in ovo development and complements classical histopathology [2]. This proof-of-concept study aimed to evaluate the utility of hMRI in detecting and characterizing radiation-induced developmental alterations in chicken embryos and to compare imaging findings with histopathological results. Material/Methods: Twenty-four Isa Brown eggs were incubated at 37 °C, 46% humidity, and rotated every 12 hours. On embryonic development day (EDD) 5, twelve eggs were irradiated at 4 Gy using a 6 MV Varian TrueBeam LINAC (600 MU/min). Twelve controls underwent identical handling without irradiation. Six irradiated and six control embryos were scanned in vivo by hMRI at EDD 9, 12, and 15 using a MR Solutions DRYMAG 7.0T system with two whole-egg T2-weighted fast spin echo sequence (TR/TE = 3789/25 ms; voxel size = 0.01x0.01x0.5 mm3) in orthogonal planes. Brain biparietal diameter (BPD), heart, and liver volumes were extracted to evaluate organs development. ANOVA tested the effects of treatment, time, and their interaction.At EDD 15, all embryos were sacrificed. Eleven controls (6 hMRI-scanned, 5 non-scanned) and nine treated embryos (6 hMRI-scanned, 3 non- scanned) were formalin-fixed and paraffin-embedded, sectioned at 4 µm, and stained with hematoxylin and eosin. Histological slides were examined and digitized for quantitative analysis. Results: All embryos survived until EDD 15. From EDD 12 onward, target organs were clearly visualized and quantifiable in hMRI (Figure 1a-1e and Table 1). All measurements increased significantly over time (p < 0.001) confirming development growth. A significant treatment effect was observed for BPD (p = 0.002).
Group x time interaction effect tended towards significance (p = 0.078) for liver volume, while it was significant for heart volume (p = 0.011), indicating altered cardiac growth dynamics. Liver histopathology (Figure 1f) revealed hepatic vein and sinusoid dilatation, vascular congestion, and multifocal perivascular leukocyte infiltration in all irradiated embryos, consistent with an acute or subacute toxic response to radiation. No significant brain or heart lesions were detected.
Conclusion: hMRI proved to be a valuable non-invasive modality for monitoring radiation-induced effects in chicken embryos. This approach supports future in ovo radiobiological studies with expanded sample sizes, dose ranges, and developmental stages, with additional hMRI sequence focused on target organs. References: [1] Phillips LJ, Coggle JE. The radiosensitivity of embryos of domestic chickens and black-headed gulls. Int J Radiat Biol Relat Stud Phys Chem Med. 1988;53(2):309-317. doi:10.1080/09553008814550661[2] Sarnella A, Ferrara Y, Terlizzi C, et al. The Chicken Embryo: An Old but Promising Model for In Vivo Preclinical Research. Biomedicines. 2024;12(12):2835. Published 2024 Dec 13. doi:10.3390/biomedicines12122835 Keywords: radiation-induced effects, MRI, chicken embryo
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