Hunter Reeve Underhill MD, Abstract Co-Author: Nothing to Disclose

Chun Yuan PhD, Presenter: Nothing to Disclose

Vasily L. Yarnykh PhD, Abstract Co-Author: Nothing to Disclose

Jinnan Wang, Abstract Co-Author: Nothing to Disclose

Niranjan Balu, Abstract Co-Author: Nothing to Disclose

Cecil E. Hayes PhD, Abstract Co-Author: Nothing to Disclose

Minako Oikawa, Abstract Co-Author: Nothing to Disclose

Wei Yu MD, Abstract Co-Author: Nothing to Disclose

Baocheng Chu, Abstract Co-Author: Nothing to Disclose

Brad Wyman, Abstract Co-Author: Employee, Pfizer Inc

Thomas S. Hatsukami MD, Abstract Co-Author: Consultant, Pfizer Inc Speaker, Pfizer Inc

et al, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To determine the impact of imaging at 3.0T on the interpretation and quantification of carotid vessel wall morphology and plaque composition.

20 subjects with 16-79% carotid stenosis by duplex ultrasound were imaged on 1.5 and 3.0T scanners with bilateral, four-element, phased-array surface coils. Protocols designed for similar SNR between platforms acquired T1, T2, proton density, time-of-flight, and contrast-enhanced T1 serial axial images with 24.0 mm of longitudinal coverage centered at the bifurcation of the artery with greater disease. Two reviewers, blinded to both field-strength and the corresponding images and results from the other scanner, interpreted each axial location via consensus opinion. Lumen area, wall area, total vessel area and mean wall thickness were recorded. Presence or absence and area of plaque components were also documented. Continuous variables were compared with the intra-class correlation coefficient (ICC) and appropriate parametric or non-parametric tests. Cohen’s κ was used to evaluate compositional dichotomous variables.

Mean(SD) time between scans was 22.4(20.6) days and the mean(SD) matched coverage per artery was 21.8(1.9) mm. There was strong agreement between field-strengths for all morphological variables with ICC values ranging from 0.95 to 0.99. Agreement in the identification of presence or absence of plaque components was very good for calcification (κ=0.72), lipid-rich necrotic core (κ=0.73), and hemorrhage (κ=0.66). However, the prevalence of hemorrhage was significantly greater at 1.5T than 3.0T (14.7% vs. 7.8%, p=0.03). For plaque components present at both matched locations between platforms, calcification was significantly (p=0.001) larger at 3.0T, while there were no size differences in lipid-rich necrotic core or hemorrhage.

At higher field-strengths, the increased susceptibility of calcification and paramagnetic ferric iron in hemorrhage appears to alter quantification and/or detection. Nevertheless, imaging criteria histologically validated at 1.5T for carotid vessel wall interpretation are applicable at 3.0T.

Effects of higher-field strengths on carotid plaque imaging.

Underhill, H, Yuan, C, Yarnykh, V, Wang, J, Balu, N, Hayes, C, Oikawa, M, Yu, W, Chu, B, Wyman, B, Hatsukami, T, et al, , et al, , Carotid Plaque Morphology and Composition: A Comparison between 1.5 and 3.0 Tesla Magnetic Field Strengths.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5001889.html