Contrast enhanced ultrasound in atherosclerotic carotid artery disease.

AIM

The traditional morphological parameters for the description of a carotid atherosclerotic plaque (degree of stenosis, echogenicity, systolic peak velocity etc.) are insufficient for the prediction of the risk of embolization. Contrast enhanced ultrasound (CEUS), based on the theory of inflammation and neoangiogenesis, seems to have a great potential for the detection of unstable plaques. The purpose of our work was to compare echogenicity of the plaque (evaluated with the Grey Scale Median; GSM), the degree of stenosis and CEUS with the histopathological findings.

METHODS

Patients with indication for internal carotid endarterectomy (CEA) underwent a preoperative imaging study with B-mode echo Doppler Ultrasound and with CEUS. The contrast enhancement of the plaque was described with two parameters: the maximum and mean signal intensity (SImax, SImean). After the surgical operation the removed plaque is sent to the pathology laboratory for the measurement of the neoangiogenesis (vessel density, VD).

RESULTS

Fifty-one consecutive patients were enrolled (12 symptomatic, 39 asymptomatic). Analysis pointed out significant differences between symptomatic and asymptomatic patients for: GSM median 14 (I quartile 11.5; III quartile 23) versus 32.5 (27-42.25) (P=0.012); SI (%) SImax 30 (29-35.5) versus 24 (19.7-27) (P<0.001) and SImean 23 (20.5-27) versus 15 (8-18.25) (P<0.001); VD (vessels/mm2) 41.5 (30-70) versus 12.6 (7-18.6) (P<0.001), respectively. Moreover, a cut-off value was determined between the two groups for each parameter: GSM:25, SImax:28%, SImean:20%, and VD: 25/mm2. Combined analysis showed that plaques with greater contrast enhancement had more newly formed capillaries and that plaques with lower GSM values correlated with greater vascularization.

CONCLUSION

The study confirms that in vitro neoangiogenesis, contrast enhancement and stability of the plaque are strongly connected and CEUS appears to be one of the most promising tools for the stratification of the carotid plaque vulnerability.