MRI-compatible Force/Toque Sensor with Fiber Bragg Gratings

C12338: MRI-Compatible Force and Torque Sensor

Novelty:

A MRI-compatible tool to remotely measure axial force and torque interactions between a device, such as a surgical needle, and a substrate, such as patient tissue and, then, relay this information to the user.

Value Proposition:

Prostate needle insertion is a technique used in medical procedures, such as brachytherapy seed implantation, biopsies, and treatment injections; during prostate needle insertion, the gland rotates and displaces and the surrounding soft tissues deform, resulting in needle placement inaccuracy. Needle placement error can result in procedure failure or increased side effects. Existing MRI-compatible sensing systems are often bulky and have limited sensing degrees of freedom (DOF). This invention allows for teleoperated needle steering under real-time MRI-guidance using a novel force measurement system. Additional advantages of this tool include:

Technical Details:

Johns Hopkins researchers have developed a system using Fiber Bragg Grating (FBG) sensor technology to sensitively measure strain of surgical needle insertion up to 10,000 m/m in a MRI environment. FBG sensors are constructed of optical fibers that reflect a particular wavelength of light and transmit all other wavelengths; the reflected wavelength directly varies with external force/torque or temperature change, allowing for measurement of mechanical and thermal strain. The optic fibers, which make up the FBG sensor, do not interfere with the MRI systems magnetic field. The system components to generate the light and to compute and analyze the wavelength shift of the reflected signal are placed outside of the MRI room, so these components also do not have an impact on the MRI image. The measured wavelength shift is compared to calibration matrices and translated to force data using a specialized analysis software module, which can be loaded on a laptop or PC. Force measurements are, then, input to a controller software module, which sends commands to the bedside surgical robots as optical data. This procedure ensures no interference of the force sensing with MRI since it requires no electrical signal transmission.

Looking for Partners:

To develop and commercialize the technology as a force sensing tool for use in noisy and high magnetic field environments, such as with MRI systems.

Stage of Development:

Prototype designed, fabricated, and successfully calibrated

Data Availability:

Prototype

Publications/Associated Cases:

Proc. SPIE 8671, Medical Imaging 2013