Abstract 1899: Morphology-Enhanced Probabilistic Plaque Segmentation Identifies Regression of the Lipid-Rich Portion of Carotid Plaques after 2 Years of Rosuvastatin Therapy
Purpose: Morphology-enhanced probabilistic plaque segmentation (MEPPS) has been validated with histology to accurately segment and identify carotid plaque composition as depicted by magnetic resonance imaging (MRI). Using MEPPS, we sought to determine the effects of rosuvastatin (RSV) on carotid atherosclerotic plaque.
Methods: Forty-three subjects (70% men; mean age 65 yrs) with fasting low-density lipoprotein cholesterol (LDL-C) ≥100 and <250 mg/dL and either 16%–79% carotid stenosis by ultrasound or plaque with a lipid-rich necrotic core (LRNC) by MRI were randomized to low- (5 mg) or high-dose (40/80 mg) RSV therapy for 2 yrs. Multi-sequence carotid MRI was done at 1.5T, with phased-array carotid coils at baseline and 2 yrs. Two reviewers, blinded to dosage and time point, used semi-automated image analysis tools to identify the boundary of lumen and outer wall in each image. Plaque components were then automatically segmented and identified with MEPPS. For each axial image, area measurements of lumen (LA), wall (WA), calcification (CA) and LRNC were determined. An ordinary bootstrap technique was applied to assess for mean (95% CI) change in the identified measurements.
Results: Thirty-three subjects (nlow=13; nhigh=20) had matched baseline and 2-yr scans. Low- and high-dose RSV reduced LDL-C levels by 39% and 58%, respectively (p<0.001). Overall, there was no significant mean change in WA (0.54 mm2, −0.70 to 1.54), LA (−0.03 mm2, −1.31 to 1.39) or CA (0.09 mm2, −0.02 to 0.27). The proportion of vessel wall comprised by the LRNC (mean %LRNC) did not change significantly in the low-dose group (mean −1.10%, −3.16 to 0.01) but was reduced by 32.7% in the high-dose group (absolute mean change in %LRNC −2.00%, −5.18 to −0.48).
Conclusion: These results confirm that MEPPS is an effective tool for evaluating plaque compositional changes in response to pharmacologic therapy. In addition to evidence suggesting arrested progression, MEPPS analysis demonstrates that 2 yrs of therapy with high-dose RSV is associated with a significant reduction in the lipid-rich portion of carotid plaques in subjects with moderate hypercholesterolemia. These findings provide compelling evidence that intensive statin therapy may have a beneficial effect on plaque composition.