Deep phenotyping using foetal MRI

Abstract Effectively combining prenatal ultrasound and foetal MRI maximizes the diagnostic possibilities in foetal medicine. Foetal MRI offers excellent soft tissue contrast and detailed assessment of the brain, body, and placenta. It is particularly valuable for evaluating CNS anomalies, complex syndromes, pulmonary hypoplasia, and structural abnormalities of the gastrointestinal and urogenital tracts. MRI phenotyping—performed in expert centres—enables detailed structural characterization, supporting genotype-phenotype correlations and refining risk assessment. Foetal MRI is considered safe from 18 weeks of gestation, with emerging research exploring its use earlier in pregnancy. When combined with genetic testing and expert ultrasound, foetal MRI enables a personalised, deep phenotypic evaluation. This integrated approach is essential for accurate prenatal diagnosis, risk stratification, and counselling in the context of complex congenital disorders. Rather than confirming or refuting sonographic diagnoses, MRI can be used more efficiently. Following the motto ‘the deeper you go, the more you know’, ‘MR phenotyping’ can be regarded as an important concept in future prenatal medicine.