1 / 20

Hyperelastic Elastography for Breast Cancer Assessment

Hyperelastic Elastography for Breast Cancer Assessment. By Ryan Armstrong Under Guidance of Hosein Amooshahi In Dr. Samani’s Lab. Outline. Breast Cancer Overview Breast Anatomy Current Diagnostic Techniques Elastography Concept of Elastography Linear Elastography

spartida
Télécharger la présentation

Hyperelastic Elastography for Breast Cancer Assessment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Hyperelastic Elastography for Breast Cancer Assessment By Ryan Armstrong Under Guidance of Hosein Amooshahi In Dr. Samani’s Lab

  2. Outline Breast Cancer Overview Breast Anatomy Current Diagnostic Techniques Elastography Concept of Elastography Linear Elastography Non-Linear (Hyperelastic) Elastography Biological Stress-Strain Curve Elastography as Inverse Problem Current Lab Work Numerical Phantom Numerical Phantom Algorithm Tissue Mimicking Phantom Summary

  3. Breast Cancer Overview • Second most prevalent cancer worldwide 3 • Fifth most common cause of cancer related death 4 • Early diagnosis is a huge factor in survival

  4. Anatomy of Breast Figure 1: Taken from Mehrabian, 2008. 1

  5. Current Diagnostic Techniques • Self Examination (Manual Palpation) • Mammography • Magnetic Resonance Imaging • Ultrasound • Biopsy

  6. Elastography Overview • Images taken pre and post-compression • Stress-strain relationships in tissues are analyzed • Reconstruction technique used to determine elastic parameters of tissues • Tumours in breast tend to be abnormally stiff compared to surrounding tissue

  7. Linear Elastography • For each tissue type, only a single elastic parameter • Young’s Modulus: E = σ/ε • Only valid for low strains • Significant errors associated with technique

  8. Hyperelastic Elastography • Generally more than one hyperelastic parameter per tissue • Defined by strain energy functions • Valid for large strain values • Calculations more complicated

  9. Biological Stress-Strain Curve Figure 2: Taken from http://www.smpp.northwestern.edu/. . . 2

  10. Elastography as Inverse Problem • Reconstructing hyperelastic parameters from data is an inverse problem • Involves initial estimates and numerous iterations

  11. Numerical Phantom • Computerized proof of concept • Boundary conditions and geometry defined consistent with real breast anatomy • Finite Element calculations performed in ABAQUS to generate displacement data • Iterative inversion algorithm runs to convergence leading to hyperelastic parameter reconstruction

  12. Numerical Phantom (3D) After deformation Before deformation

  13. Hyperelastic Parameters Reconstruction Algorithm Main pre-image Main post-image Latest artificial deformed image Initial HEPs Calculate displacement field using OF Updated HEPs Calculate Stress tensor using ABAQUS Calculate Deformation Gradient No Averaging & updating HE parameters (1 to 3) Converge Yes End Figure 3: Taken from Amooshahi 5

  14. Tissue Mimicking Phantom • Construction of phantom with PVA, Biocide, and heat-cool cycles • Unaxial test for parameter measurement • Pre and Post Compression US images are taken • Hyperelastic parameters reconstructed

  15. Summary • Breast cancer has high prevalence and mortality rate • Early detection is vital for treatment and ultimately survival • Elastography shows great potential as a diagnostic tool with high specificity • Hyperelastic models allow us to reconstruct parameters for high strain

  16. References • H Mehrabian. Soft Tissue Hyperelastic Parameter Reconstruction. Masters thesis submitted to the University of Western Ontario. Supervisor: Abbas Samani. (2008) • Mechanical Properties of Soft Tissue. In Sitting Biomechanics Laboratory. Retrieved May 30th, 2010 from:http://www.smpp.northwestern.edu/Makhsous/Mechanical%20Properties%20of%20Soft%2 0Tissue.shtml • World Health Organization International Agency for Research on Cancer (2008). • "World Cancer Report". Retrieved on May 30th, 2010. • 4. World Health Organization (February 2006). "Fact sheet No. 297: Cancer". Retrieved • on May 30th, 2010. • 5. M Amooshahi. (Nov. 17, 2009) Classification of Breast Tumours Using Hyperelastic Elastography PowerPoint presentation presented at the University of Western Ontario.

  17. Questions?

More Related