On a T2-weighted MRI of the brain, cerebrospinal fluid appears bright (hyperintense). Which of the following structures, if enlarged, would appear as a hyperintense midline structure between the thalami on axial section?
- A Aqueduct of Sylvius
- B Third ventricle ✓
- C Cavum septum pellucidum
- D Foramen of Monro
Correct answer: B. Third ventricle
Explanation
The third ventricle is a midline CSF space lying between the two thalami. On axial T2-MRI, if dilated (e.g., in obstructive hydrocephalus), it appears as a prominent hyperintense midline structure flanked by the thalami. The cavum septum pellucidum is anterior, between the frontal horns. The aqueduct and foramen of Monro are small and narrow; enlargement implies obstruction at a different level.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.