title: Carotid plaque regression following 6-month statin therapy assessed by 3T cardiovascular magnetic resonance: comparison with ultrasound intima media thickness.
abstract: BACKGROUND
  Cardiovascular magnetic resonance (CMR) allows volumetric carotid plaque measurement that has advantage over 2-dimensional ultrasound (US) intima-media thickness (IMT) in evaluating treatment response. We tested the hypothesis that 6-month statin treatment in patients with carotid plaque will lead to plaque regression when measured by 3 Tesla CMR but not by IMT.
  
  
  METHODS
  Twenty-six subjects (67 ± 2 years, 7 females) with known carotid plaque (> 1.1 mm) and coronary or cerebrovascular atherosclerotic disease underwent 3T CMR (T1, T2, proton density and time of flight sequences) and US at baseline and following 6 months of statin therapy (6 had initiation, 7 had increase and 13 had maintenance of statin dosing). CMR plaque volume (PV) was measured in the region 12 mm below and up to 12 mm above carotid flow divider using software. Mean posterior IMT in the same region was measured. Baseline and 6-month CMR PV and US IMT were compared. Change in lipid rich/necrotic core (LR/NC) and calcification plaque components from CMR were related to change in PV.
  
  
  RESULTS
  Low-density lipoprotein cholesterol decreased (86 ± 6 to 74 ± 4 mg/dL, p = 0.046). CMR PV decreased 5.8 ± 2% (1036 ± 59 to 976 ± 65 mm3, p = 0.018). Mean IMT was unchanged (1.12 ± 0.06 vs. 1.14 ± 0.06 mm, p = NS). Patients with initiation or increase of statins had -8.8 ± 2.8% PV change (p = 0.001) while patients with maintenance of statin dosing had -2.7 ± 3% change in PV (p = NS). There was circumferential heterogeneity in CMR plaque thickness with greatest thickness in the posterior carotid artery, in the region opposite the flow divider. Similarly there was circumferential regional difference in change of plaque thickness with significant plaque regression in the anterior carotid region in region of the flow divider. Change in LR/NC (R = 0.62, p = 0.006) and calcification (R = 0.45, p = 0.03) correlated with PV change.
  
  
  CONCLUSIONS
  Six month statin therapy in patients with carotid plaque led to reduced plaque volume by 3T CMR, but ultrasound posterior IMT did not show any change. The heterogeneous spatial distribution of plaque and regional differences in magnitude of plaque regression may explain the difference in findings and support volumetric measurement of plaque. 3T CMR has potential advantage over ultrasound IMT to assess treatment response in individuals and may allow reduced sample size, duration and cost of clinical trials of plaque regression.
authors.affiliation: Department of Medicine, Marquette University, 1120 W, Wisconsin Avenue, Wilwaukee, WI 53233, USA. raymond.migrino@gmail.com
authors.forename: Raymond Q
authors.initials: RQ
authors.lastname: Migrino
authors.forename: Mark
authors.initials: M
authors.lastname: Bowers
authors.forename: Leanne
authors.initials: L
authors.lastname: Harmann
authors.forename: Robert
authors.initials: R
authors.lastname: Prost
authors.forename: John F
authors.initials: JF
authors.lastname: LaDisa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002340:Carotid Artery Diseases / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000473:pathology; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D007090:Image Interpretation, Computer-Assisted; D008055:Lipids / Q000097:blood; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D058226:Plaque, Atherosclerotic / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D017539:Tunica Intima / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000473:pathology; D017540:Tunica Media / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000473:pathology; D014463:Ultrasonography; D061205:Vascular Calcification / Q000175:diagnosis / Q000188:drug therapy; D014922:Wisconsin
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D008055:Lipids