Elastographic Study of Injection Ali Baghani, Robert Rohling Robotics and Control Lab, University of British Columbia

Outline Problem background Proposed method Experimental setup Results Conclusion and future work

Problem Background (1) Many medical procedures involve needle placement inside tissue:  Therapeutic procedures: Gene transfer Ethanol injection into parathyroid glands  Anesthetic procedures Peripheral nerve blocks Epidural procedure Many of these procedures are carried out under the guidance of ultrasound.

Problem Background (2) Main goal of ultrasound guided procedures:  Accurate placement of needle in anatomy Main goal of procedures involving injection:  Accurate delivery of the injectate to the correct anatomical site

Proposed Method Using elastography to monitor injection The benefits:  Tracking the needle tip  Tracking the injectate deposition  Inferring tissue properties at the needle tip Result:  Accurate delivery of the injectate to the correct anatomical site

Experimental Setup (1)

Experimental Setup (2)

Results (1) Axial strain rate measurements during injection using oscillatory injection

Results (2) Video of axial strain rate measurements during injection using an oscillatory injection

Results (3) Video of axial strain measurements during injection using a ramp input

Conclusion We have demonstrated the conceptual feasibility of injection studies using elastograms. The depot can be distinguished from the surrounding tissue using correlation data. Strains caused by the injection in surrounding tissue can be observed and measured using the elastogram.

Future Works The current approach can be applied for:  Needle tip tracking  Strain monitoring for avoiding pain and tissue damage during  Characterizing mechanical properties of the tissue surrounding needle tip

Acknowledgement This project was supported by grants from NSERC and CHIR.

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