Within the motion degraded MRA (not shown), no vascular abnormalities were seen, in particular, no evidence of a mycotic aneurysm. This patient went to further formal DSA angiography, which also came as normal. 

The imaging appearances of multiple infarcts in almost all the major vascular territories, including the posterior fossa, are those of shower emboli from a central source. Given the known aortic root abscess, this was considered the most likely source, and, although no other imaging features to suggest an abscess or a mycotic aneurysm, septic emboli was strongly considered. 

Generally, causes that could explain cardiac embolism to the brain are ¹: 

• blood stasis and thrombus formation in an enlarged left cardiac chamber: e.g. a ventricular aneurysm, atrial fibrillation, etc.
• valvular surface releasing abnormal materials: e.g. mitral calcific degeneration, nonbacterial thrombotic endocarditis, infective endocarditis, etc.
• paradoxical embolism (abnormal communication in between the venous to the arterial circulation): e.g. patent foramen ovale, pulmonary AVMs, etc.

Atrial fibrillation, which is the commonest sustained cardiac arrhythmia. is considered the major source for cardioembolic stroke ¹.