Carotid Plaque Evaluation Using Gemstone Spectral Imaging: Comparison with Magnetic Resonance Angiography.

BACKGROUND: The present study compared the applicability of computed tomography carotid plaque imaging using effective Z maps with gemstone spectral imaging (GSI) to that of magnetic resonance plaque imaging using 3-dimensional time-of-flight magnetic resonance angiography. METHODS: Stenosis was assessed in 18 carotid arteries of 14 patients, and the effective Z values of noncalcified carotid plaques were compared with the signal intensities of magnetic resonance angiography. RESULTS: It was found that the effective Z value of noncalcified carotid plaques was significantly lower for a group with high signal intensity than for a group with low signal intensity on magnetic resonance angiography (P <.001). The area under the receiver operating characteristic curve of effective Z values was .975, and the presumed cutoff effective Z value required to discriminate low and high intensity plaques on magnetic resonance angiography was 7.83. CONCLUSIONS: The effective Z value generated by GSI is a useful parameter to detect vulnerable carotid plaque materials.