3D- versus 2D-Power-Doppler Ultrasound for Evaluation of Internal Carotid Arteries: Implications for Whole Plaque Analysis with Gray-Scale Median

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Aim:

Whole plaque analysis of carotid artery stenosis with Gray-Scale Median (GSM) allows quantification of plaque echogenicity, correlates with histology and was shown to be associated with symptoms and embolic cerebral findings. The aim of the study is to find out whether 3-dimensional Power-Doppler ultrasound (3D-PDUS) datasets comprising whole plaque stenoses provide different GSM than single sections acquired by 2D-PDUS as commonly used for this purpose.

Patients and Methods:

27 patients were scanned with a 3D-ultrasound (US) probe at 10 Mhz. GSM analysis was performed offline with a specially designed software in 2D longitudinal scans adjusted to the vessel center line, as well as 3 parasagital- longitudinal sections of the plaque, that were aquired off-line from the 3D-datasets by multiplanar rendering. For comparison of the GSM, the median differences between 3Dand the 2D-images as well as standard deviations (SD) were calculated. Mixed model regression analysis was used for further descriptive statistics.

Results:

The proportion of the SD in between the GSM of the 3D sections compared to single 2D-reference sections were calculated 63% for the parasagital 3D-views, which is higher than the methodological error.

The GSM of the two central longitudinal 3D-sections located closest to the 2D-section correlate to the GSM of the 2D-reference section. However, significant over- versus underestimations were noted for high versus low GSM values in the 3D parasagital views.

Summary/Conclusions: Variations of the echogenity in between the 3D-sections are largely due to deviations in between the GSM-values of the 3D-views. The GSM of a single 2D-section may be representative for the central part the whole 3D plaque structure.