title: Seven-tesla magnetic resonance imaging of atherosclerotic plaque in the significantly stenosed carotid artery: a feasibility study.
abstract: OBJECTIVE
  The objective of this study was to assess the feasibility of carotid vessel wall imaging at 7.0 for T magnetic resonance imaging (MRI) in a series of patients with a symptomatic greater than 70% stenosis of the internal carotid artery.
  
  
  METHODS
  First, a series of 6 healthy volunteers were scanned at 3.0 T and 7.0 T MRI to perform a signal-to-noise ratio comparison between these 2 field strengths. Second, in patients with a greater than 70% stenosed carotid artery, a 7.0 T MRI protocol, consisting of a dual-echo turbo spin echo sequence (echo times of 45 and 150 milliseconds) and a T1-weighted turbo spin echo sequence, was obtained. Lumen and vessel wall were delineated for interobserver and intraobserver reproducibility, and signal intensity distribution in the most severely stenosed part of the internal carotid artery was correlated with different plaque components on histopathologic findings.
  
  
  RESULTS
  The mean (SD) signal-to-noise ratio in the vessel wall was 42 (12) at 7.0 T and 24 (4) at 3.0 T. Nineteen patients were included, but technical issues yielded carotid MRI data of 14 patients available for the final analysis. Of these patients, 4 were diagnosed with stroke, 7 were diagnosed with a transient ischemic attack, and 3 were diagnosed with amaurosis fugax. Intraclass correlation coefficient of the agreements of lumen and vessel wall determination between 2 observers and between the repeated measures of 1 observer were above 0.80 in both 3.0 T and 7.0 T data sets of the healthy volunteers and also in the 7.0 T data set of the patients. Signal hyperintensity in the 7.0 T magnetic resonance images was inversely proportional to calcification. Other correlations between plaque components and signal intensity could not be confirmed.
  
  
  CONCLUSIONS
  This first series of patients with carotid atherosclerotic plaque who were scanned at 7.0 T MRI shows that 7.0 T MRI enables to adequately determine lumen and vessel wall areas. Signal hyperintensity in these 7.0 T magnetic resonance images was inversely proportional to calcification. However, at this stage, no other correlations between histologic findings and vessel wall contrast were found. Implementation of in vivo high-resolution 7.0 T MRI of plaque components for risk stratification remains challenging. Future development of hardware and software is still needed to attain a more robust setup and to enable complete plaque characterization, similar to what is currently possible with multiple MRI sequences at 1.5 T and 3.0 T MRI.
authors.affiliation: From the *Department of Radiology, University Medical Center Utrecht, Utrecht; Departments of †Radiology, and ‡Clinical Neurophysiology, §Cardiovascular Research Institute Maastricht, University Medical Center Maastricht, Maastricht; ∥Department of Vascular Surgery, University Medical Center Utrecht, Utrecht, the Netherlands; ¶Department of Bioengineering, Imperial College London, London, United Kingdom; Departments of #Pathology, and **Experimental Cardiology, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: Alexandra A J
authors.initials: AA
authors.lastname: de Rotte
authors.forename: Wouter
authors.initials: W
authors.lastname: Koning
authors.forename: Martine T B
authors.initials: MT
authors.lastname: Truijman
authors.forename: Anne G
authors.initials: AG
authors.lastname: den Hartog
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Bovens
authors.forename: Aryan
authors.initials: A
authors.lastname: Vink
authors.forename: Shahrzad
authors.initials: S
authors.lastname: Sepehrkhouy
authors.forename: Jaco J M
authors.initials: JJ
authors.lastname: Zwanenburg
authors.forename: Dennis W J
authors.initials: DW
authors.lastname: Klomp
authors.forename: Gerard
authors.initials: G
authors.lastname: Pasterkamp
authors.forename: Frans L
authors.initials: FL
authors.lastname: Moll
authors.forename: Peter R
authors.initials: PR
authors.lastname: Luijten
authors.forename: Jeroen
authors.initials: J
authors.lastname: Hendrikse
authors.forename: Gert Jan
authors.initials: GJ
authors.lastname: de Borst
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002343:Carotid Artery, Internal / Q000473:pathology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D002546:Ischemic Attack, Transient / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D058226:Plaque, Atherosclerotic / Q000175:diagnosis*; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D020521:Stroke / Q000175:diagnosis*