Neuroradiologic findings in pontine and extrapontine myelinolysis

Contrast enhancement on MRI in the early phase of central pontine myelinolysis
Three days after symptom onset, T2-weighted MRI showed a hyperintense lesion of the pons (A) and of the basal ganglia (B). Coronal postgadolinium T1-weighted MRI showed a nonhomogeneous enhancement of the pontine lesion 3 days after symptom onset (C), which diminished 15 days later (D).

Sequential MRI of the pituitary in Sheehan syndrome

Coronal and sagittal postcontrast T1-weighted spin-echo images show an enlarged pituitary with rim enhancement and no internal enhancement (arrows). Findings are suggestive of nonhemorrhagic pituitary infarct, i.e., Sheehan syndrome.  
Temporal evolution of the pituitary gland in Sheehan syndrome
Coronal and sagittal postcontrast T1-weighted spin-echo images show atrophy of the anterior pituitary gland (arrows) on follow-up MRI 1 year later.

Lipoma of trigeminal nerve in a patient with severe trigeminal neuralgia

T1 coronal images show homogenous hyperintense lesion involving the right trigeminal nerve root (white arrows) in A and B and Meckel's cave (white arrow) in C as compared to normal left trigeminal nerve (black arrows) and Meckel's cave (yellow arrow). Axial T1 image also demonstrates the involvement of mandibular division in foramen ovale (white arrow) as compared to normal on left side (orange arrow) in D.

A case of partial oculomotor palsy

Examination of conjugate extraocular movements showing right adduction palsy and right partial ptosis

(A) Brain MRI shows hyperintense signal in the dorsal midbrain on the right side on axial T2-weighted image and (B) schematic representation of the oculomotor nerve fascicles in the midbrain with the arrangement of various fibers in the oculomotor nerve fascicle: IO = inferior oblique; IR = inferior rectus; LPS = levator palpebrae superioris; MR = medial rectus; PF = pupillary fibers; SR = superior rectus. (C, D) Diffusion-weighted imaging (coronal) with reduced apparent diffusion coefficient on the corresponding site.

A slowly growing benign brain mass

(A–H) T2-weighted images (repetition time msec/echo time msec, 2,150/30; 3-mm-thick sections; matrix, 256 × 256; field of view 250 mm2) show a neuroglial cyst in the right hemisphere measuring 16 cm3 initially and increasing to 175 cm3 with considerable mass effect after 7 years.