Role of diffusion-weighted imaging in carotid plaque vulnerability assessment

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 mm 2 /s vs 1.7 × 10 –3 mm 2 /s; p 0.001), with a sensitivity and specificity of 75% and 79%, respectively, at an ADC cutoff of 1.24 × 10 –3 mm 2 /s. Plaques with and without lipid-rich necrotic core (0.86 × 10 –3 mm 2 /s vs 1.44 × 10 –3 mm 2 /s; p = 0.042) as well as intraplaque hemorrhage could be differentiated (0.751 × 10 –3 mm 2 /s vs 1.352 × 10 –3 mm 2 /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.