Image-guided FUS rhizotomy using dual-mode ultrasound array systems - description: facet joint inflammation or degeneration is implicated in 20 - 40% of lumbar and cervical back pain cases

The National Institute of Neurological Disorders and Stroke awarded Nusonex LLC $323,645 on September 1, 2026, under the Drug Use and Addiction Research Programs (CFDA 93.279) to develop a prototype image-guided focused ultrasound device for rhizotomy treatment of facet joint–related back pain.

Nusonex LLC will develop a specialized dual-mode ultrasound array prototype with real-time image guidance, monitoring, and image-based closed-loop control capable of precise thermal, mechanical, or thermomechanical lesion formation. The device is intended to eliminate the need for fluoroscopy guidance and reduce or eliminate the need for diagnostic nerve blocks by providing stimulating sub-threshold exposures to identify target nerves before ablation. The technology is based on dual-mode ultrasound array patents optioned from the University of Minnesota intellectual property portfolio and invented by the principal investigator.

Performance takes place in Minneapolis, Minnesota, with a period of performance from September 1, 2026, through August 31, 2027. This is a Phase I Small Business Innovation Research award (R41 mechanism).

A considerable number of patients do not respond to more conservative treatments, and resort to more aggressive treatments such as rhizotomy and endoscopic denervation. A recent meta-analysis suggests that radiofrequency (RF) rhizotomy has good efficacy at 12 months in reducing back pain due to FJ inflammation. While RF rhizotomy can be considered safe, efficacious, and minimally invasive, IT requires fluoroscopy for guidance and may require general anesthesia. These requirements add to the complexity and cost of this procedure, which could be a barrier to even higher levels of adoption by providers and acceptance by patients. Nusonex LLC is developing a novel device for delivering localized, noninvasive form of rhizotomy using image-guided focused ultrasound (igfus). The FUS rhizotomy device is based on the dual-mode ultrasound array (dmua) technology invented by the PI and developed at the university of minnesota. Nusonex LLC has optioned key patents from the UMN IP portfolio related to dmua technology that provides the basis for the development of the proposed device. The proposed device will have image guidance, targeting, and legion control features that will eliminate the need for fluoroscopy. Furthermore, the dmua- based FUS rhizotomy treatment has the potential to identify the target nerve by providing precise stimulating sub-threshold exposures before ablation. This feature should lead to a more streamlined treatment procedure and may even eliminate or reduce the need for the nerve block diagnostic step. To realize the potential of the proposed FUS rhizotomy, we propose to develop a specialized dmua prototype with real-time image- guidance, monitoring, and image-based closed-loop control (CLC) capable of forming precise thermally-, mechanically, or thermomechanically induced millimeter-size lesions in the vicinity of facet joints without damage to the bone. In phase i, nusonex LLC will be developing a new fpga-based dmua system for imaging and real-time CLC. The design and development effort will be performed in parallel with a UMN study of the characteristics of image-guided lesion formation in 4 human cadaver specimens (2 male and 2 female) using the hifu synthesizer®, a dmua system that was developed under license from the university of minnesota, for the treatment of peripheral vascular disease. We will develop multi-parametric dmua imaging capabilities for characterization of the FJ target region in cadaveric human specimens (SA1, UMN). We will also develop a tabletop, fpga-based prototype system for targeting and characterizing the soft tissues in the vicinity of the facet joint (SA2, nusonex). Successful completion of the proposed research will open the way for first-in-human studies in phase II using a tabletop version of the dmua system, which will be fabricated by a prospective industrial partner. The proposed system will reduce the cost and complexity of rhizotomy to the provider, and the patient. More importantly, IT will offer an attractive alternative to providers and patients who have preference for the least invasive procedure.