Magnetic resonance imaging (MRI) allows for excellent depiction of the vascular anatomy through routine planar imaging, contrast-enhanced MR angiography (MRA) and non-contrast-enhanced MRA. Conventional angiography should be relegated to cases where depiction of small vessels is necessary such as in the evaluation of vasculitis and to therapeutic interventions. Figure 4.1a shows a volume rendered image of the aorta showing the most common vascular distribution: leftsided aortic arch, right brachiocephalic artery, left common carotid, and left subclavian artery, arising from the aorta and both vertebral arteries arising from the subclavian arteries. Figure 4.1b and c shows the most common variations including bovine arch (Figure 4.1b),

where both common carotid arteries arise from a common trunk (which is actually a misnomer as the bovine anatomy is different) and an aberrant right subclavian artery in the setting of a left aortic arch (Figure 4.1c), potentially creating a vascular compression on the esophagus, which can be seen on uoroscopy. This artery is also called lusoria artery. In these patients, the right subclavian artery can have a dilated origin from the aortic arch named the diverticulum of Kommerell. Important anomalies to keep in mind in the evaluation of the aortic arch include right aortic arch with mirror image branching, which is associated with cyanotic congenital heart disease, and right aortic arch with aberrant left subclavian artery, which, although not as strongly related with congenital heart disease, causes a vascular ring and its associated symptoms from compression of the trachea and esophagus, such as inspiratory stridor,

CONTENTS

4.1 Vascular Anatomy .......................................................................................................................................................... 55 4.1.1 Vessel Wall Histology ......................................................................................................................................... 57 4.1.2 Vascular Imaging ................................................................................................................................................ 58

4.1.2.1 Time-of-Flight MRA ............................................................................................................................ 58 4.1.2.2 Contrast-Enhanced MRA .................................................................................................................... 59 4.1.2.3 Phase Contrast MRA ........................................................................................................................... 59

4.1.3 Black-Blood Imaging .......................................................................................................................................... 59 4.2 Supra-Aortic Arteriopathies .......................................................................................................................................... 59

4.2.1 Atherosclerosis .................................................................................................................................................... 61 4.2.1.1 Carotid Bulb Atherosclerosis ............................................................................................................. 61 4.2.1.2 Intracranial Atherosclerosis ............................................................................................................... 66

4.2.2 Noninammatory ............................................................................................................................................... 70 4.2.2.1 Fibromuscular Dysplasia .................................................................................................................... 70 4.2.2.2 Arterial Dissection ............................................................................................................................... 72 4.2.2.3 Reversible Vasoconstriction Syndrome............................................................................................. 72 4.2.2.4 CADASIL Syndrome ............................................................................................................................ 74

4.2.3 Inammatory ....................................................................................................................................................... 74 4.2.3.1 CNS Vasculitis ...................................................................................................................................... 74 4.2.3.2 Giant Cell Arteritis ............................................................................................................................... 76 4.2.3.3 Takayasu Arteritis ................................................................................................................................ 76 4.2.3.4 Carotidynia ........................................................................................................................................... 77

4.2.4 Unknown ............................................................................................................................................................. 78 4.2.4.1 Moyamoya Disease and Moyamoya Syndrome .............................................................................. 78

4.3 Conclusion ....................................................................................................................................................................... 82 References .................................................................................................................................................................................. 85

wheezing, dyspnea, cough, dysphagia, and recurrent respiratory tract infections [1].