Assessment of Carotid Diffusion-Weighted Imaging for Detection of Lipid-Rich Necrotic Core in Symptomatic Carotid Atheroma

Abstract

Purpose To evaluate the diagnostic usefulness of diffusion-weighted MR imaging (DWI) compared with contrast-enhanced MR imaging for the detection of the lipid-rich necrotic core (LRNC) of symptomatic carotid atherosclerotic plaques. Materials and Methods Twenty-five patients (median age: 66 years; range: 45–78 years) with moderate-to-severe symptomatic carotid stenosis confirmed with contrast-enhanced carotid MR angiography who underwent carotid plaque MR imaging were retrospectively reviewed. An echo-planner DWI with b0, b200, b400, b800, and b1000 was performed along with carotid plaque MR imaging. Plaque visualization on DWI was analyzed by 2 reviewers on consensus. The contrast-to-noise ratio between the lumen and plaque was analyzed between variable b-values. Results Carotid atherosclerotic plaques were identified on carotid DWI in 8 patients. Confirmed carotid atherosclerotic plaques were not identified on carotid DWI in 16 patients. The DWI-identified group had plaques with significantly greater maximal wall thickness and longitudinal length, as compared with the non-identified group. DWI with b200 had a higher contrast-to-noise ratio between the lumen and LRNC (p < 0.001). The mean apparent diffusion coefficient value from DWI with b200 for the LRNC was 0.51 ± 1.55 × 10-3 mm2/s. Conclusion There was less frequent identification of carotid atherosclerotic plaques with carotid DWI, as compared with contrast-enhanced MR imaging. This study suggested that carotid DWI cannot replace contrast-enhanced MR imaging for the detection of carotid plaques, including LRNC.

Keywords

• carotid artery disease
• carotid stenosis
• plaque
• atherosclerotic
• magnetic resonance angiography
• diffusion weighted mri