[MRI and in utero ventriculomegaly]

Ventriculomegaly constitutes the major indication of fetal brain MRI. MRI is therefore of utmost importance to look for a cause through the depiction of criteria of malformations and through the definition of criteria of destructive lesions. Malformations and destructive lesions are the most common causes of ventricular dilatation. Some challenging points are worth mentioning in term of mechanism with the challenge of hydrocephalus (in term of increased in intracranial pressure) and of isolated ventriculomegaly. The image itself is also challenging since a similar image may be of different origin. In term of natural history of fetal brain injury an irregular, nodular aspect of the ventricular wall and/or the germinal matrix is often the only pathologic MRI finding that is known to be of clastic origin. In term of prognosis the challenge is represented by the isolated mild ventriculomegaly, the literature being quite confusing. The purpose of this review paper is to highlight the underlying mechanisms and pathophysiology of ventricular dilatation based on results from the literature as well as from personal experience.