MR angiography proves accurate for internal carotid artery disease

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Time-of-flight (TOF) and contrast-enhanced (CE) MR angiography accurately detects high-grade internal carotid artery (ICA) stenoses and occlusions, suggesting that the procedure could replace the gold-standard, intra-arterial angiography.

Accurate diagnosis of the degree of ICA stenosis is needed for decisions regarding optimal stroke prevention, according to background information in a study published in the August issue of Stroke.

Alison E. Baird, PhD, director of the division of cerebrovascular disease and stroke at SUNY Downstate Medical Center in Brooklyn, N.Y., and colleagues, performed a systematic review and diagnostic meta-analysis to determine the sensitivity and specificity of TOF MRA and CE MRA for the detection of high-grade (greater than or equal to 70 to 99 percent) ICA stenoses; ICA occlusions; moderately severe (50 to 69 percent) ICA stenoses; and compare the overall accuracy of the two MRA techniques.

The medical literature on MRA and the diagnosis of ICA steno-occlusive disease was reviewed through the PubMed, EMBASE and SCOPUS databases. All publication years were included through November 2006. Studies were eligible for inclusion if they compared the accuracy of TOF or CE MRA for the detection of ICA disease against intra-arterial angiography and reported sufficient data, according to the researchers.

The results showed that the overall sensitivity of TOF MRA for the detection of high-grade ICA stenoses was 91.2 percent with a specificity of 88.3 percent, whereas the sensitivity of CE MRA was 94.6 percent with a specificity of 91.9 percent, according to the investigators.

For the detection of ICA occlusions, the researchers found that the sensitivity of TOF MRA was 94.5 percent and the specificity was 99.3 percent, whereas the sensitivity and specificity values for CE MRA were 99.4 percent and 99.6 percent, respectively.

For moderately severe stenoses, TOF MRA had a sensitivity of only 37.9 percent and specificity of 92.1 percent; for CE MRA, the pooled sensitivity value was somewhat better at 65.9 percent, whereas the specificity was 93.5 percent, the authors wrote.

Baird and colleagues concluded that TOF MRA and CE MRA showed high accuracy for the detection of high-grade ICA stenoses and occlusions with CE MRA having the edge over TOF MRA, but had only poor (TOF MRA) to fair (CE MRA) sensitivity for the detection of moderately severe stenoses.