Role of diffusion-weighted imaging in carotid plaque vulnerability assessment

Abstract

Background MR plaque imaging is a valuable tool in characterizing carotid atherosclerotic plaque and identifying high-risk features. There are limited data on the role of the widely available single-shot diffusion-weighted imaging (DWI) in plaque characterization along with histological correlation. This study aimed to correlate the plaque characteristics identified by MR imaging in vivo at the level of maximum stenosis with histological plaque characteristics in the postoperative specimen. Methods Patients who underwent carotid endarterectomy in a tertiary care center during one and half years were prospectively recruited for non-contrast MR carotid plaque imaging (including single-shot EPI-DWI sequence) in a 3 Tesla MRI using a dedicated carotid coil. An experienced radiologist correlated DWI sequence findings with histopathology of postsurgical sections to confirm the high-risk features. Results Twenty-three patients (mean age 66.1 years ± SD 6.25) were evaluated, of which 65% were males and 96% were symptomatic. Apparent diffusion coefficient (ADC) values in location of plaques could differentiate histopathological unstable from stable plaques (0.83 × 10–3 mm2/s vs 1.7 × 10–3 mm2/s; p 0.001), with a sensitivity and specificity of 75% and 79%, respectively, at an ADC cutoff of 1.24 × 10–3 mm2/s. Plaques with and without lipid-rich necrotic core (0.86 × 10–3 mm2/s vs 1.44 × 10–3 mm2/s; p = 0.042) as well as intraplaque hemorrhage could be differentiated (0.751 × 10–3 mm2/s vs 1.352 × 10–3 mm2/s; p 0.037) using the apparent diffusion coefficients. Conclusion The widely available single-shot EPI-DWI in assessing plaque characteristics in carotid stenosis is promising and correlated with histopathological features. Diffusion-weighted imaging will be a helpful adjunct in patients when contrast administration is intolerable.

Microstructural and mechanical insight into atherosclerotic plaques: an ex vivo DTI study to better assess plaque vulnerability

“…However, this work provides the fundamental insights into DTI-derived metrics and the mechanical insight they can yield for future translational studies. Additionally, a number of in vivo studies have used diffusion weighted imaging to investigate plaque components (Alex et al 2022 ; Kim et al 2011 ; Kim et al 2021 ; Millon et al 2013 ; Xie et al 2014 ; Lopez Gonzalez, et al 2016 ; Young et al 2010 ; Zhang et al 2017 ), already establishing the usefulness of measuring water diffusion within these tissues. Extending these acquisitions to incorporate directionality, while not trivial, has the potential to better ascertain plaque vulnerability due to the direct link to mechanical integrity.…”

“…There is a growing body of evidence suggesting that the percent stenosis, a diagnostic criterion for atherosclerotic plaque vulnerability established in the 1980s and 1990s (Warlow et al 1998 ; Warlow 1991 ), is not an adequate indicator for measuring the likelihood of a plaque to rupture. While studies have investigated geometric features and remodeling of plaques and their usefulness in determining vulnerability (Ghasemi et al 2020 ; Jiang 2020 ; Wang et al 2022 ; Creane et al 2012 ), there is a recent acknowledgement that plaque composition and microstructure could better capitulate rupture risk (Naylor et al 2018 ; Saba et al 2019 ; Kolodgie et al 2017 ; Alex et al 2022 ). More specifically, the percent stenosis falls short both in low grade stenosed plaques (Wasserman et al 2005 ; Holm Nielsen, et al 2020 ) and asymptomatic patients (Elhfnawy et al.…”