PROJECT SUMMARY/ABSTRACT Over 450,000 diagnostic lumbar punctures (LPs) are performed annually in the US, but up to 15 – 35% end in procedural failure, primarily due to inability to access the intrathecal space. Bedside LP failure rates are particularly high in the growing obese population, with recent studies reporting failure rates greater than 50% in subjects over BMI 35 kg/m2. Given its technical difficulty, there is a reluctance to perform bedside LPs, even when medically indicated. Consequently, 30 – 50% of LPs are now performed under fluoroscopic guidance, but securing neuroradiology services delays diagnosis, adds cost, and is not possible in emergency or critical care situations. The total direct and indirect costs of failed LPs to patients and the healthcare system exceed $500M/yr. Thus, there is a clear need for bedside LPs to reach success rates similar to those performed using fluoroscopy, and it is likely that a technological advancement that reduces the difficulty of administering LPs is required to meet this need. During this project, a 3D ultrasound-based bedside LP guidance system will be developed under a quality management system (QMS) certified to ISO 13485:2016 and 21 CFR Part 820. The key technological innovations underpinning the development of this product include the following: 3D bone reconstruction technologies enabling ‘fluoroscopy-like’ renderings of the lumbar spine, spine landmark recognition algorithms that automatically detect the location of the intrathecal space, and needle guidance methods to aid visualization of the needle trajectory. The primary technical tasks during the early phases of the project period include the execution of end-user clinical usability studies to guide technical specification development, electro- mechanical sub-system design, integration, and validation, and design and implementation of core ultrasound imaging processing and visualization algorithms. Successful completion of these technical aims will result in fabrication of pre-production systems for pre-clinical validation studies later in the project period. Pre-clinical product validation activities will include cadaver and human-imaging studies performed in collaboration with clinical experts who will validate that the system meets the requirements for the clinical application. The primary endpoint for the pre-clinical cadaveric studies is a direct comparison of needle placement accuracy between the current standard of care (blind needle placement) and the 3D-ultrasound needle guidance product. An additional pre-clinical study will characterize overall system usability and the learning curve required to reach competency with the system by studying the product’s use in 150 simulated imaging procedures, performed by at least 10 individual neurologists. Completion of this research project will result in the development and fabrication of a human clinical-trial- ready 3D-imaging based lumbar puncture guidance system.