title: Elastic image registration to quantify 3-D regional myocardial deformation from volumetric ultrasound: experimental validation in an animal model.
abstract: Although real-time 3-D echocardiography has the potential to allow more accurate assessment of global and regional ventricular dynamics compared with more traditional 2-D ultrasound examinations, it still requires rigorous testing and validation should it break through as a standard examination in routine clinical practice. However, only a limited number of studies have validated 3-D strain algorithms in an in vivo experimental setting. The aim of the present study, therefore, was to validate a registration-based strain estimation methodology in an animal model. Volumetric images were acquired in 14 open-chest sheep instrumented with ultrasonic microcrystals. Radial strain (ɛRR), longitudinal strain (ɛLL) and circumferential strain (ɛCC) were estimated during different stages: at rest, during reduced and increased cardiac inotropy induced by esmolol and dobutamine infusion, respectively, and during acute ischemia. Agreement between image-based and microcrystal-based strain estimates was evaluated by their linear correlation, indicating that all strain components could be estimated with acceptable accuracy (r = 0.69 for ɛRR, r = 0.64 for ɛLL and r = 0.62 for ɛCC). These findings are comparable to the performance of the current state-of-the-art commercial 3-D speckle tracking methods. Furthermore, shape of the strain curves, timing of peak values and location of dysfunctional regions were identified well. Whether 3-D elastic registration performs better than 3-D block matching-based methodologies still remains to be proven.
authors.affiliation: Laboratory on Cardiovascular Imaging and Dynamics, KU Leuven, Leuven, Belgium. brecht.heyde@med.kuleuven.be
authors.forename: Brecht
authors.initials: B
authors.lastname: Heyde
authors.forename: Stefaan
authors.initials: S
authors.lastname: Bouchez
authors.forename: Sabine
authors.initials: S
authors.lastname: Thieren
authors.forename: Michael
authors.initials: M
authors.lastname: Vandenheuvel
authors.forename: Ruta
authors.initials: R
authors.lastname: Jasaityte
authors.forename: Daniel
authors.initials: D
authors.lastname: Barbosa
authors.forename: Piet
authors.initials: P
authors.lastname: Claus
authors.forename: Frederik
authors.initials: F
authors.lastname: Maes
authors.forename: Patrick
authors.initials: P
authors.lastname: Wouters
authors.forename: Jan
authors.initials: J
authors.lastname: D'Hooge
mesh_terms: D000465:Algorithms; D000818:Animals; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012756:Sheep; D013382:Subtraction Technique; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: Echocardiography; Elastic registration; In vivo; Sonomicrometry; Strain; Validation