Images of Blood Vessels
Angiography is an imaging procedure that takes images of blood vessels in various parts of the body, including the brain, heart and kidneys. This imaging helps doctors determine whether the vessels are diseased, narrowed, enlarged or fully blocked.
Types of Angiography
There are three major forms of angiography: catheter angiography, computed tomography angiography (CTA) and magnetic resonance angiography (MRA).
Catheter angiography is a process in which a catheter is inserted into an artery in the groin and advanced to the area of the body being examined. Imaging is performed using X-rays. Contrast material is sent through the catheter to highlight the vessels while the X-rays are being taken. It is widely used as a preoperative procedure for patients who will be undergoing surgery. It is also used as a guide to perform angioplasty or stent placement. These are procedures performed by a radiologist, cardiologist or surgeon in order to treat abnormal or blocked vessels.
Catheter angiography also may be used to intentionally embolize or block vessels that are supplying areas of bleeding or tumors. An example of this is uterine artery embolization, where vessels linked to uterine fibroids are blocked in order to shrink these benign tumors.
A specific kind of catheter angiography is performed to diagnose abnormalities of the vessels supplying the brain. Physicians at GW Hospital use the Integris Biplane Neurovascular imaging system, manufactured by Philips Medical Systems, to visualize vessels and conduct complex neuro-interventional procedures dealing with aneurysms, head and neck tumors, and strokes. Since this machine uses biplane technology, it will allow studies to be completed with lower contrast doses, fewer potential complications and significantly reduced procedure time.
Computed Tomography Angiography (CTA)
CTA uses a CT scanner to noninvasively take pictures of vessels. Iodine is a contrast material that may be injected into a vein using a small intravenous needle, creating no need for invasive catheter placement. This type of exam has been used to screen numerous patients for arterial diseases such as aortic dissection, carotid stenosis, aneurysms and vascular disease of the kidney. Most patients can receive this exam without being admitted into the hospital. This method of detection displays the anatomical detail of blood vessels more precisely than an ultrasound, and while comparable to magnetic resonance imaging (MRI), is faster and can be performed on patients with pacemakers and other metal implants.
Magnetic Resonance Angiography (MRA)
MRA is another noninvasive angiography procedure that uses MRI to visualize vessels as two-dimensional and three-dimensional images that can be viewed on a computer monitor. The indications are similar to that of CTA. This noninvasive procedure requires no X-rays, invasive catheter placement or iodinated contrast material, but does involve an intravenous injection of Gadolinium. MRA is a painless, shorter exam than a catheter angiography. The results of MRA may be used to determine whether surgery or treatment such as angioplasty is needed, and to plan that treatment.