Background: Contrast-enhanced magnetic resonance angiography (CE-MRA) seems better than time-of-flight magnetic resonance angiography (TOF-MRA) in the evaluation of extracranial arteries but to have some limitations in the evaluation of intracranial arteries. We found it showed a tendency to overestimate the stenosis.
Objectives: With digital subtraction angiography (DSA) as a gold standard, we tried to find out if CE-MRA overestimates the degrees of stenosis of middle cerebral artery (MCA) and basilar artery (BA).
Methods: From April 2003 to August 2006, 93 patients, who underwent TOF-MRA, CE-MRA, and DSA within a month, were enrolled. Fourteen MCA and 3 BA images were missing on DSA, so we could analyze 172 MCAs and 90 BAs. The quality of TOF-MRA, CEMRA, and DSA were classified as adequate or inadequate for analysis. The degree of stenosis was measured by comparing the diameter of the vessel at the site of stenosis with the normal diameter of the vessel just distal to the stenosis and stratified as minimal (1-29%), mild (30-49%), moderate (50-69%) and severe (70-99%) stenosis.
Results: Among 172 MCAs, 13 MCAs were excluded because the quality of 11 CE-MRA and 2 TOF-MRA images were inadequate for analysis (6.4% vs. 1.2%, p<0.05). We calculated the agreement (κ) in DSA vs. CE-MRA (κ=0.49, p<0.01) and in DSA vs. TOF-MRA (κ=0.65, p<0.01) in measuring the stenosis of MCA. Among 90 BAs, 7 BAs were excluded because the quality of 6 CE-MRA and 1 TOF-MRA images were inadequate (6.7% vs. 1.1%, p<0.05). We calculated the agreement (κ) in DSA vs. CE-MRA (κ=0.24, p<0.01) and in DSA vs. TOF-MRA (κ=0.45, p<0.01).
Conclusion In comparison to TOF-MRA, CE-MRA tends to overestimate the degree of intracranial artery stenosis and it often shows suboptimal quality. (Korean Journal of Stroke 2006;8:197-203)
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