Unmet Need
Effective radiation treatment of tumors combines maximal radiation dose delivery to planned locations while mitigating radiation impacts on surrounding normal tissues. A delivery of radiation absorption materials (biocompatible gels) to create pockets of radiation dissipation has proven to be an effective method to mask unwanted effects. Most injection procedures are performed under passive ultrasound, or x-ray guidance as MRI guided injections are material limiting and inefficient in procedural timing. If a needle were to exist that was MRI-compatible, comparable in mechanical properties to non-MRI compatible needles, and allowed for active tracking of needlepoint to the target area, accuracy in dose delivery could be improved. Other areas to benefit from this technology could be cryoblation techniques, chemotherapy agent deployments, and embolization practices.
Technology Overview
The reported invention is an MR-tracked injection needle formed by concentric titanium tubes with a bevel-shaped cutting tip. The area between the tubes is where MR-tracking coils are located, along with signal-transmitting micro axial cables. This allows for distal end location and orientation tracking. The proximal end contains electrical circuits to optimize the tracking signal and is connected to a syringe (for radiation gel injection) and to a quick-disconnect electrical connection that allows for the transfer of the MR Tracking signals to receivers of the MRI scanners. "Longer" injection needles may require MBalun overlays at prescribed distances along the shaft to prevent radio-frequency induced heating of the titanium shaft. This device aims to provide efficient and precise gel delivery with quantifiable topology and volume results.
This approach's immediate design targets center on trans-perineal gel injections used during HDR or LDR Brachytherapy (BT) for the treatment of cervical and prostate cancers. Similar designs may be used for injection of various agents into vascular and soft-tissue spaces. A slight variation could be utilized for suction practices (biopsy purposes). Examples: cryoblation, chemotherapy agent deployment, embolization.
Stage of Development
Inventors have tested 30 cm long prototypes in female swine models, demonstrating the ability to rapidly bring the needle tip under MR-tracked guidance to soft tissue pockets between the cervix/endometrium and the rectum, and to dynamically visualize the volume and shape of the pockets with real-time MR Imaging during injection of MR-visible contrasts into these pockets, allowing the shaping of pockets that can significantly reduce rectum irradiation. Thermal testing of these prototypes in 1.5 Tesla scanners was also completed, meeting ASTM 2182-19 heating limits for MRI-conditional devices. This product utilizes two prior inventions outlined below.
• MR-Tracking pulse sequence used with metallic devices. This invention utilized flexible printed-circuit MRI micro-coils in a lobe pattern for improved metallic device location. Phase-dithering gradient lobes accompanied this to reduce localization artifacts resulting from metallic surfaces. Localization resolution is 0.6x0.6x0.6mm^3, performed at a speed of 15 fps. Patent- "An Active Tracking System and Method for MRI", assigned to BWH.
• MBalun overlay for metal surfaces to reduce induced currents on metallic devices by MRI. Long metallic devices limited to heating below FDA/IEC limits during specific absorption rate sequences. Patent- "MRI Radio-Frequency Heating Amelioration for Metallic Electrophysiology Catheters and Guidewires with Miniature Tether Radio-Frequency Traps".
