MRA | MRV
MR Angiography (MRA) is an MRI study of the blood vessels. It utilizes MRI technology to detect, diagnose and aid the treatment of heart disorders, stroke, and blood vessel diseases. MRA provides detailed images of blood vessels without using any contrast material, although a special form of contrast material is often given to make the MRI images even clearer. The procedure is painless, and the magnetic field is not known to cause tissue damage of any kind.
What are some of the common uses of this procedure?
Many patients with arterial disease now have it treated in the radiology department rather than undergoing surgery in an operating room. MRA is a very useful way of finding problems with blood vessels and determining how to best to treat those problems.
The carotid arteries in the neck that conduct blood to the brain are a common site of atherosclerosis, which may severely narrow or block off an artery, reducing blood flow to the brain and even causing a stroke. If an ultrasound study shows that such disease is present, many surgeons will perform the necessary operation after confirmation with MRA, dispensing with the need for catheter angiography.
MRA has found wide use in checking patients for diseased intracranial (in the head) arteries, so that only those with positive findings will need to undergo a more invasive catheter study.
MRA is also used to detect disease in the aorta and in blood vessels supplying the kidneys, lungs and legs.
Patients with a family history of arterial aneurysm, a ballooning out of a segment of the vessel wall, can be screened with MRA to see if they have a similar disorder that has not produced symptoms. If an aneurysm is found, it may be eliminated surgically, possibly avoiding serious or fatal bleeding.
MR Angiography helps your physician diagnose the following conditions:
• Bulges in your aorta, called aneurysms
• Tears in your aorta, called dissections
• Problems with your heart that you may be born with, called congenital heart disorders
• Narrowing of the arteries in and around your kidneys, called renal artery stenosis
• Inflammation in your blood vessels, called vasculitis
• Hardening of the arteries (called atherosclerosis) involving the legs or arms
• Blockages in the major arteries that supply blood to your brain, called carotid artery disease
MRV – Magnetic Resonance Venography
Magnetic Resonance venography (MRV) is an accurate, non-invasive imaging technique used to detect deep vein thrombosis. This type of MRI provides images of blood flow in diseased and normal veins. MRV is specifically useful for visualizing vascular abnormalities, thrombosis, and other pathology. MRV can be accomplished with contrast or without. Special imaging sequences allow the visualization of moving blood within the veins. Two common techniques to obtain the images of flowing blood are:
• TOF – Time of flight: Incoming blood makes the vessels appear bright, and surrounding tissue is suppressed.
• SSFP – Steady state free precession is generally used for assessment of veins in the chest, abdomen, and pelvis.
Although the initial evaluation of the iliac and lower extremity veins is usually accomplished with Ultrasound. MRV is more efficient in detecting venous thrombosis in the pelvic and calf veins.