[Relative size of the ventricle to the hemisphere in the neonatal MRI]

Using a software program for measuring surface area, we quantified the relative size of four parts of the lateral ventricles, including the body, the trigone, the anterior horn and the occipital horn, compared to the hemispheres in the axial plane of magnetic resonance imaging (MRI) in neonates. In 44 neonates without any neurological disorders from 26 to 41 weeks of gestational age (GA), MRI was performed between 12 and 124 postnatal days. The mean of the relative size of the ventricle compared to the hemisphere (RSVH) among the subjects showed a significant left-right asymmetry that was observed only in the occipital horn. However, in the body, the anterior horn and the occipital horn, the percentage of neonates with a larger left RSVH compared to the right RSVH was significantly higher than the percentage of neonates with a larger right RSVH compared to the left RSVH. The RSVH of the body and the occipital horn increased according to the number of postnatal days and decreased according to GA. Measuring RSVH was useful in assessing the size of the ventricle in the axial plane of neonatal MRI. It clarified the fact that normative asymmetry, GA of subject, and the number of postnatal days should be considered in assessing the size of ventricle.