Magnetic resonance imaging (MRI) lumbar plexus fat suppressed T2-weighted axial image, showing thickening of the left obturator nerve (red arrow) from the level of S1 as it courses medially along the psoas major muscle and between the pectineus (PE) and adductor brevis (AB), consistent with left obturator neuropathy. Post-radiation injury to the nerve appears hyperintense, diffuse, with uniform swelling on a T2-weighted image (7). Edema and mild enhancement of the left adductor compartment and obturator externus (OE) is present, consistent with post-radiation changes and denervation secondary to left obturator neuropathy.