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MR angiography is an effective means of diagnosing substantial stenotic and occlusive internal carotid artery disease, according to the results of a meta-analysis.

Magnetic resonance angiography (MRA) using either time-of-flight or contrast-enhanced approaches is an effective means of diagnosing substantial stenotic and occlusive internal carotid artery disease, according to the results of a meta-analysis.

"We found that the current change to the use of MRA to detect high-grade internal carotid artery stenoses and occlusions appears justified," senior investigator Dr. Alison E. Baird told Reuters Health. Contrast-enhanced MRA, she added, has the edge over time-of-flight MRA.

Dr. Baird of SUNY Downstate Medical Center, Brooklyn, New York and colleagues examined data from 58 studies, five of which compared time-of-flight and contrast-enhanced in the same patients.

The team determined that the overall sensitivity of time-of-flight MRA was 91.2 per cent and the specificity was 88.3 per cent. Corresponding values of contrast-enhanced MRA were 94.6 per cent and 91.9 per cent, researchers report in the August issue of Stroke.

For the detection of internal carotid artery occlusions, time-of-flight had a sensitivity of 94.5 per cent and a specificity of 99.3 per cent. For contrast-enhanced, these values were 99.4 per cent and 99.6 per cent.

However, for moderately severe stenoses ranging from 50 per cent to 69 per cent, time-of-flight had a sensitivity of only 37.9 per cent and a specificity of 92.1 per cent. With contrast-enhanced, sensitivity was 65.9 per cent and specificity was 93.5 per cent.

"The accuracy of MRA has yet to be proven for the detection of moderate-grade stenoses," continued Dr. Baird. "It is recommended that a second noninvasive study be obtained to confirm the grade of internal carotid artery disease at this time before treatment decisions are made."

"A complimentary diagnostic tool such as ultrasound or computed tomography angiography or digital subtraction angiography," she stressed, "is necessary in these cases for decision-making regarding potential carotid endarterectomy or stenting."

Stroke 2008;39:2237-2248