Noninvasive carotid artery imaging with a focus on the vulnerable plaque

Quality of extracranial carotid evaluation with 256-section CT

BACKGROUND AND PURPOSE

To date, no systematic evaluation of image quality has been performed on the 256-section multidetector CT scanner for extracranial carotid evaluations. We evaluated image quality, patient dose, and examination time and compared these parameters with a 64-section multidetector CT.

MATERIALS AND METHODS

We reviewed extracranial CTA scans obtained on a 256-detector CT scanner in 50 consecutive patients. Image quality was analyzed for artifacts and vessel contrast opacification from the aortic arch to the skull base, dose to patient, and scan time. Results were compared with a control group of 50 patients imaged on a 64-section CT scanner. A Fisher exact test was used to analyze both groups with respect to vessel contrast opacification and presence of artifacts, and a Student t test was used to assess differences in patient dose between the 2 groups.

RESULTS

Quantitative and qualitative evaluations revealed >95% acceptable vessel opacification at all levels measured on the 256-section scanner. Scan time was improved (4 seconds on 256-channel). There were fewer artifacts related to metallic streak on the 256-channel CTA study, and DLP was lower on the 256-channel CTA (113.9 versus 159.8 mGy).

CONCLUSIONS

The 256-channel CTA imaging protocol for carotid arteries yielded similar vessel contrast opacification compared with the 64-channel CTA but with fewer metallic artifacts, a modest decrease in scan time, similar image quality, and a statistically significant reduction in radiation dose of 10%.

A modified rabbit model of carotid atherosclerotic plaque suitable for the stroke study and MRI evaluation

In order to induce a modified rabbit model of carotid atherosclerotic plaque suitable for the stroke study and to evaluate the lesion with magnetic resonance imaging (MRI). Eight rabbits of group A were fed with high-fat diet only. Atherosclerosis at the right common carotid artery was induced in rabbits of group B (n = 12) by high-fat diet and balloon catheter injury to the endothelium 4 weeks later. The rabbits were examined in vivo with a 1.5-T MRI. After 4 weeks on the high-fat diet, the serum lipid levels were markedly increased, which became significantly higher than the baseline levels. The lesions on both MRI and histology were remarkable. One week after balloon injury, the signal of injured right common carotid was higher on all the contrast-weighted images than the left side. The extent of abnormal signal was reduced 9 weeks after balloon injury. Hemorrhage was detected on all the contrast-weighted images. In conclusion, the rabbit model established by the authors is such a feasible one to the study of stroke caused by carotid atherosclerosis.