MR Angiography Gives New Image of Arterial Disease

LOS ANGELES, Jan. 30 -- Magnetic resonance angiography (MRA) is highly effective in identifying severely stenotic supra-aortic arteries, according to researchers here.

In a prospective cohort study, the MRA images were comparable to those obtained using multidetector CT scanning or the gold standard, digital subtraction angiography (DSA), according to Kambiz Nael, M.D., of the University of California at Los Angeles.

The new techniques would mean that patients thought to have a severe supra-aortic arterial stenosis would not be exposed to ionizing radiation, as in CT scanning, or to the risk of transient or permanent neurological damage, as in DSA, Dr. Nael and colleagues reported in the February issue of Radiology.

"MR angiography produced results comparable to the gold standard of digital subtraction angiography and multidetector computed tomography angiography," Dr. Nael said in a statement.

From May 2004 through February 2005, the researchers used MRA on 80 consecutive patients suspected of having cerebrovascular atherosclerotic disease.

Of those, 25 underwent subsequent imaging for comparison purposes -- 12 getting a follow-up CT angiogram and 13 patients getting DSA.

The MRA scanning was done in a 3-Tesla whole-body Magnetom Trio, made by Siemens Medical Solutions and equipped to perform highly accelerated parallel image acquisition.

After an injection of a contrast agent, patients were scanned as they held their breath for 20 seconds, Dr. Nael and colleagues reported, and the subsequent images were later evaluated independently by two neuroradiologists.

The combination of parallel image acquisition and the higher magnetic power -- 3-Tesla, rather than 1.5-Tesla -- "produced images with higher resolution over a larger field of view in a shorter amount of time than previous contrast-enhanced MR angiography techniques," Dr. Nael said.

Indeed, the researchers reported, the study found that 97% of the imaged arterial segments were good enough to fall in the diagnostic range and the two readers were in substantial agreement on most of the images.

Specifically, the first reader identified disease in 208 arterial segments, and the second identified disease in 218.

Also, there was a significant correlation between CT and MR angiography and between DSA and MRA (at P<0.001 for both readers and both comparisons).

"In the absence of contraindications to MRI," Dr. Nael said, "I would recommend MRA over DSA and CTA for routine use-avoiding increased risk of mini-stroke and radiation exposure."