Imaging: For verification of CAD diagnosis, all study participants will undergo a standardized routine MRI scan of brain and neck before study entry. 14 +/- 7 days after treatment onset a second MRI of brain and neck will be performed. The following MRI sequences will be performed on a 3 Tesla scanner (1) spin echo (SE) T1w, turbo spin-echo (TSE) T2w, FLAIR to detect chronic ischemic brain lesions. (2) Diffusion weighted imaging (DWI) including apparent diffusion coefficient (ADC) maps to detect acute ischemic brain lesions. (3) susceptibility-weighted imaging (SWI) sequences or T2*w gradient echo (GRE) to detect hemorrhagic brain lesions (4) contrast-enhanced magnetic resonance angiography (CE-MRA) to improve delineation of the wall hematoma against the perfused vessel lumen, and to assess the degree of obstruction of the affected artery. MRI scans will be centrally analysed at the University Hospital Basel, and independently assessed by two observers who are blinded to the type of treatment and clinical outcome.