On an axial MRI of the brain at the level of the basal ganglia, the structure that appears as a hypointense (dark) rim on T2-weighted imaging due to iron deposition is the:

• A Caudate nucleus head
• B Putamen
• C Anterior limb of internal capsule
• D Globus pallidus ✓

Explanation

The globus pallidus normally accumulates the highest concentration of iron in the brain, appearing hypointense (dark) on T2-weighted MRI and GRE sequences due to iron's paramagnetic effect causing T2* shortening. This is a normal finding that increases with age. The putamen also accumulates iron but to a lesser degree. The caudate and internal capsule do not show significant physiological iron deposition. Abnormal T2-hypointensity of both globus pallidus and putamen ('eye of the tiger' sign) suggests neurodegeneration with brain iron accumulation (NBIA/PKAN).

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.