 Brain MRI:No evidence for intracranial hemorrhage or acute cerebral, brainstem or cerebellar infarction. There is right PCA territorial encephalomalacia indicating prior ischemic infarction and appears similar to the recent prior CT but increased compared to the MRI from 2009 at which time infarct was acute. Evidence of Wallerian degeneration along the right corticospinal tract. Additional periventricular and subcortical T2/Flair hyperintensities are nonspecific but compatible with small vessel ischemic changes.There is ex-vacuo dilatation of the temporal horn of the right lateral ventricle. No hydrocephalus. The cerebellar tonsils are in normal position. There are no masses, mass effect or midline shift. The pituitary gland is normal in size. There are no extraaxial fluid collections or subdural hematomas. The paranasal sinuses and mastoid air cells are clear. A right lens prosthesis is noted.Brain MRA: The V3 segment of the right vertebral artery is moderately narrow with opacification more distally intracranially and better seen on the postgadolinium sequence. There is a left dominant vertebral artery. The right PICA is not clearly seen. The AICA arteries are patent. There is some irregularity involving the right superior cerebellar artery.At least moderate stenosis suspected in the right PCA involving right P2 and distally. The PCA appears diminutive within the right ambient cistern and is not visualized beyond the quadrigeminal cistern. The posterior communicating arteries are not visualized bilaterally.Mild atherosclerotic narrowing is noted of the left paraclinoid ICA. The remaining anterior circulation is patent without significant steno-occlusive disease.Neck MRA:There is conventional takeoff of the great vessels from the aortic arch. There are is irregularity and narrowing involving the right V1 segment at the origin and just beyond the origin. There is a 5 mm enhancing structure at the right carotid bifurcation and is unclear if this represents a small aneurysm or an extravascular mass. No stenoses of the bilateral common, internal or external carotid arteries or of the bilateral carotid bifurcations. There is no evidence for vasculitis, fibromuscular dysplasia or dissection of the carotid or vertebral arterial systems within the neck.
1.No evidence of acute infarct. Chronic right PCA territory infarct.2.High grade right PCA stenosis similar to 2/22/2009 CTA. 3.The V3 segment of the right vertebral artery is moderately narrow with opacification more distally intracranially and better seen on the postgadolinium sequence. Irregularity and narrowing involving the right V1 segment at the origin and just beyond the origin.4.7 mm enhancing structure at the right carotid bifurcation. Prior CTA neck demonstrates a 3 mm enhancing lesion in this location. Finding likely represents a normal carotid body and less likely carotid body paraganglioma (6 mm considered 2 standard deviations above normal by CTA, Nguyen RP et al. AJNR 2011 32: 1096-1099). 