title: Comparison of three dimensional strain volume reconstructions using SOUPR and wobbler based acquisitions: A phantom study.
abstract: OBJECTIVE
  Ultrasound strain imaging is a relatively low cost and portable modality for monitoring percutaneous thermal ablation of liver neoplasms. However, a 3D strain volume reconstruction from existing 2D strain images is necessary to fully delineate the thermal dose distribution. Tissue mimicking (TM) phantom experiments were performed to validate a novel volume reconstruction algorithm referred to as sheaf of ultrasound planes reconstruction (SOUPR), based on a series of 2D rotational imaging planes.
  
  
  METHODS
  Reconstruction using SOUPR was formulated as an optimization problem with constraints on data consistency with 2D strain images and data smoothness of the volume data. Reconstructed ablation inclusion dimensions, volume, and elastographic signal to noise ratio (SNRe) and contrast to noise ratio (CNRe) were compared with conventional 3D ultrasound strain imaging based on interpolating a series of quasiparallel 2D strain images with a wobbler transducer.
  
  
  RESULTS
  Volume estimates of the phantom inclusion were in a similar range for both acquisition approaches. SNRe and CNRe obtained with SOUPR were significantly higher on the order of 250% and 166%, respectively. The mean error of the inclusion dimension reconstructed with a wobbler transducer was on the order of 10.4%, 3.5%, and 19.0% along the X, Y, and Z axes, respectively, while the error with SOUPR was on the order of 2.6%, 2.8%, and 9.6%. A qualitative comparison of SOUPR and wobbler reconstruction was also performed using a thermally ablated region created in ex vivo bovine liver tissue.
  
  
  CONCLUSIONS
  The authors have demonstrated using experimental evaluations with a TM phantom that the reconstruction results obtained with SOUPR were superior when compared with a conventional wobbler transducer in terms of inclusion shape preservation and detectability.
authors.affiliation: Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Yang
authors.affiliation: Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706.
authors.forename: Atul
authors.initials: A
authors.lastname: Ingle
authors.affiliation: Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53705 and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706.
authors.forename: Tomy
authors.initials: T
authors.lastname: Varghese
mesh_terms: D000465:Algorithms; D000818:Animals; D002417:Cattle; D054459:Elasticity Imaging Techniques / Q000295:instrumentation*; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D008099:Liver / Q000000981:diagnostic imaging; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio; D013314:Stress, Mechanical; D014159:Transducers