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Declaration of Conflict of Interest or Relationship

Declaration of Conflict of Interest or Relationship. Speaker Name: Yong-Lae Park I have no conflicts of interest to disclose with regard to the subject matter of this presentation.

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Declaration of Conflict of Interest or Relationship

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  1. Declaration of Conflict of Interest or Relationship Speaker Name: Yong-Lae Park I have no conflicts of interest to disclose with regard to the subject matter of this presentation.

  2. MRI-Compatible Haptics: Feasibility of Using Optical Fiber Bragg Grating Sensors to Detect Deflection of Needles in an MRI environment Yong-Lae Park, Santhi Elayaperumal, Elena Kaye, Kim B. Pauly, Richard J. Black, and Mark R. Cutkosky Stanford University Stanford University

  3. Outline • Background • Fiber Bragg Grating (FBG) Sensors • Prototype Development • Experimental Results • Conclusions and Future Work

  4. MRI-Guided Needle Procedures • MR guided biopsy • Lesion Localization • Tumor Ablation • Therapeutic Injection • Problem: Needle Deflection

  5. Goal: Detection of Needle Deflection • Existing Technologies • MR Tracking • Rapid MRI • Gradient-based Tracking • Objective: MR-Haptics • Detection of needle deflection • Strain sensing approach

  6. Fiber Bragg Grating (FBG) Sensors • Immune to electromagnetic Interference • High resolution (0.1 με) • Multiple sensors in one fiber • Small (80 μm thick) and flexible Optical Fibers Input Transmission FBG Reflection Optical Fiber 5 mm FBG Transmission Input Reflection Needle

  7. εx d2y d dx2 dy dx Deflection Estimation using Beam Theory εx: strain measured by FBG sensor ρ: radius of curvature d: distance from neutral axis Sensor 2 Sensor 1 x1 x2 Curvature (1/ρ) x 1 Curvature = = ρ f(x) = ax2+bx+c Slope Slope = ∫f(x) dx x Deflection = ∫∫f(x) dx Deflection x y

  8. Model Construction • EZEM MRI-compatible biopsy needle • 22 ga x 15 cm • Material: Inconel 625 alloy L = 15cm 2 / L F2 F1 Sensor 2 Sensor 1 Tip Deflection x1 x2

  9. Determination of Sensor Locations Sensitivity of Deflection Error Deflection Error Plot For x1 Minimum Error Region x2 x2 x1=25 mm x2=82 mm x1 For x2 x1 x2 Sensor 2 Sensor 1 x1 x2 x1

  10. Prototype Development • Two FBGs on a biopsy needle • Measure strains when deflected • No artifact from the optical fiber (MR-image of the bent needle) • No sensor noise • Remote sensor interrogation Sensor 2 Sensor 1 25 mm 82 mm deflection original needle shape bent needle

  11. One Point Bending • EZEM MRI-compatible biopsy needle • 22 ga x 15 cm • Material: Inconel 625 alloy Sensor 2 Sensor 1 X1 = 25 X2 = 82 Deflection = - 5 mm, Error = 0.13 mm (2.6 %)

  12. Two Point Bending (S-curve) • EZEM MRI-compatible biopsy needle • 22 ga x 15 cm • Material: Inconel 625 alloy Sensor 2 Sensor 1 X1 = 25 X2 = 82 Deflection = - 10 mm, Error = 0.27 mm (2.7 %)

  13. Conclusions • Less than 3% estimation error • in 5 mm deflection for one point bending • In 10 mm deflection for two point bending • No artifacts on MR images • No degradation of sensor accuracy in MRI environments

  14. Future Work • Fabrication method • Three dimensional sensing • Force and position sensing in MR-compatible robotics • Instrumented base socket Biopsy Needle Polymer Base Socket Optical Fibers Embedded FBGs

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