Longitudinal in Utero Analysis of Engrailed-1 Knockout Mouse Embryonic Phenotypes Using High-Frequency Ultrasound

• Published in: Ultrasound in medicine & biology Vol. 49; no. 1; pp. 356 - 367
• Main Authors: Aristizábal, Orlando, Qiu, Ziming, Gallego, Estefania, Aristizábal, Matias, Mamou, Jonathan, Wang, Yao, Ketterling, Jeffrey A., Turnbull, Daniel H.
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 01.01.2023
• Subjects: Animals; Brain; Embryo, Mammalian - diagnostic imaging; Imaging, Three-Dimensional - methods; In utero imaging; Longitudinal 3-D ultrasound; Mice; Mice, Knockout; Mouse embryo; Mutant phenotype analysis; Phenotype; Ultrasonography; In utero imaging; Mutant phenotype analysis; Mouse embryo; Longitudinal 3-D ultrasound
• ISSN: 0301-5629; 1879-291X
• DOI: 10.1016/j.ultrasmedbio.2022.09.008

Large-scale international efforts to generate and analyze loss-of-function mutations in each of the approximately 20,000 protein-encoding gene mutations are ongoing using the “knockout” mouse as a model organism. Because one-third of gene knockouts are expected to result in embryonic lethality, it is important to develop non-invasive in utero imaging methods to detect and monitor mutant phenotypes in mouse embryos. We describe the utility of 3-D high-frequency (40-MHz) ultrasound (HFU) for longitudinal in utero imaging of mouse embryos between embryonic days (E) 11.5 and E14.5, which represent critical stages of brain and organ development. Engrailed-1 knockout (En1-ko) mouse embryos and their normal control littermates were imaged with HFU in 3-D, enabling visualization of morphological phenotypes in the developing brains, limbs and heads of the En1-ko embryos. Recently developed deep learning approaches were used to automatically segment the embryonic brain ventricles and bodies from the 3-D HFU images, allowing quantitative volumetric analyses of the En1-ko brain phenotypes. Taken together, these results show great promise for the application of longitudinal 3-D HFU to analyze knockout mouse embryos in utero.