MRangiografia

MR angiography (MRA) is a group of magnetic resonance imaging techniques used to visualize blood vessels and assess blood flow without using ionizing radiation. It can be performed with or without intravenous contrast and provides noninvasive evaluation of arteries and veins across the body, aiding in the diagnosis of vascular disease and preoperative planning.

Techniques include non-contrast methods such as time-of-flight (TOF) and phase-contrast MRA, which exploit flow-related signals or velocity encoding to depict vessels. Contrast-enhanced MRA (CE-MRA) uses gadolinium-based agents injected intravenously to improve visualization, particularly of small or slow-flow vessels. Some protocols acquire time-resolved data to show dynamic contrast passage (4D MRA).

Applications span the cerebral circulation (intracranial aneurysms, stenosis), carotid and vertebral arteries, the aorta and its branches, renal and mesenteric arteries, and peripheral vasculature for evaluation of occlusive disease or aneurysms.

Advantages include avoidance of ionizing radiation and, in many cases, reduced invasiveness compared with catheter angiography. Limitations involve susceptibility to motion and flow-related artifacts, and, for CE-MRA, dependence on kidney function and concerns about gadolinium exposure, though newer agents have improved safety. TOF-MRA may be limited by slow flow and saturation effects.

Safety and considerations include MRI compatibility, contraindications for gadolinium in impaired kidney function, and the choice of technique based on clinical question, anatomy, and patient factors. In some situations CT angiography or conventional angiography may be preferred.