title: Principal Strain Vascular Elastography: Simulation and Preliminary Clinical Evaluation.
abstract: It is difficult to produce reliable polar strain elastograms (radial and circumferential) because the center of the carotid artery is typically unknown. Principal strain imaging can overcome this limitation, but suboptimal lateral displacement estimates make this an impractical approach for visualizing mechanical properties within the carotid artery. We hypothesized that compounded plane wave imaging can minimize this problem. To test this hypothesis, we performed (i) simulations with vessels of varying morphology and mechanical behavior (i.e., isotropic and transversely isotropic), and (ii) a pilot study with 10 healthy volunteers. The accuracy of principal and polar strain (computed using knowledge of the precise vessel center) elastograms varied between 7% and 17%. In both types of elastograms, strain concentrated at the junction between the fibrous cap and the vessel wall, and the strain magnitude decreased with increasing fibrous cap thickness. Elastograms of healthy volunteers were consistent with those of transversely isotropic homogeneous vessels; they were spatially asymmetric, a trend that was common to both principal and polar strains. No significant differences were observed in the mean strain recovered from principal and polar strains (p > 0.05). This investigation indicates that principal strain elastograms measured with compounding plane wave imaging overcome the problems incurred when polar strain elastograms are computed with imprecise estimates of the vessel center.
authors.affiliation: Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York, USA.
authors.forename: Rohit
authors.initials: R
authors.lastname: Nayak
authors.affiliation: Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Huntzicker
authors.affiliation: Laboratory TIMC-IMAG/DyCTiM, University Joseph-Fourier, CNRS UMR 5525, Grenoble, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Ohayon
authors.affiliation: Department of Imaging Sciences, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York, USA.
authors.forename: Nancy
authors.initials: N
authors.lastname: Carson
authors.affiliation: Department of Imaging Sciences, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York, USA.
authors.forename: Vikram
authors.initials: V
authors.lastname: Dogra
authors.affiliation: Department of Neurology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York, USA.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Schifitto
authors.affiliation: Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York, USA; Department of Biomedical Engineering, University of Rochester, Rochester, New York, USA. Electronic address: m.doyley@rochester.edu.
authors.forename: Marvin M
authors.initials: MM
authors.lastname: Doyley
mesh_terms: D000368:Aged; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000502:physiology*; D003198:Computer Simulation; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012016:Reference Values; D015203:Reproducibility of Results
keywords: Anisotropy; Atherosclerosis; Plane wave imaging; Principal strain; Vascular elastography