ABSTRACT
Objective To study the localization of the foramen of Monro on magnetic resonance image (MRI) and its clinical significance.Methods Cranial MRI was observed for 30 normal healthy subjects to study their location,shape and size of the foramen of Monro,as compared to those in 22 patients with hydrocephalus and 14 cases with tumor around their foramen.Results The the foramen of Monro is located between the fornix and the anterior part of thalamus in the normal healthy subjects,with a transverse diameter of 2.8 mm and a vertical diameter of 2.1 mm in average on MRI.Y-shaped structure is formed between their bilateral the foramen of Monro and the 3rd cerebral ventricle.Very obvious changes in shape and size of the foramen of Monro can be observed in patients with hydrocephalus,which sometimes can integrated with the 3rd cerebral ventricle and lateral ventricle,forming a"rabbit-head sign".Meanwhile, imaging of the foramen of Monro varied in patients with tumor around the foramen,depending on its location and size.Conclusions The foramen of Monro has a relative constant position in the brain.Changes in its position,size and shape are important signs suggesting intracranial lesions.An individualized operation plan for a patient should be determined based on those changes.