PURPOSE: Point-of-care ultrasound image-guided therapies (POCUS IGT) transcend geographic and socioeconomic boundaries and help bringing modern therapies to underserved communities and countries. Unfortunately, current commercial systems are not feasible to deploy in Mauritania due to prohibitive costs of purchase, support, and operation. We present the development of a versatile POCUS IGT system, optimized for financial and operating conditions in Mauritania. We aimed to create a system that is functionally similar to the popular CIVCO product, but costs only a small fraction of the price due to the support of inexpensive ultrasound scanners and its use of open-source software. METHODS: A 3D-printed plastic needle guide with multiple guide channels was designed to securely fit around the ultrasound probe, placed in a sterile cover, and fitted with a sterile guide sleeve. Open source targeting software was developed to overlay selectable needle trajectories on the live ultrasound image. RESULTS: The assembly and workflow were found to be similar to CIVCO’s. The operator was able to accurately reach targets in the entire workspace. Excluding the price of the ultrasound scanner, the use of system costs around $1.00 per patient. CONCLUSION: A POCUS IGT system was developed using free open-source guidance software that supports low-cost ultrasound scanners, offering similar performance to the leading commercial system for 5% of price.
PURPOSE: Endoscopic vessel harvesting is the preferred minimally invasive approach to obtain grafts for coronary bypass surgeries, however it requires extensive practice to minimize vessel damage. We propose to create a surgical training simulation with visual and haptic feedback. In this study, we focus on analyzing the force and torque peaks on the surgical retractor during the procedure. METHODS: The original retractor handle was 3D scanned and modified to attach an ATI Mini40 force-torque transducer. The forces and torques in two radial artery and two saphenous vein procedures in human cadavers were recorded. The measurements, endoscopic video and surgical surface video were collected. The median and interquartile range of the force and torque peaks were calculated for the artery and vein harvesting procedures. RESULTS: The median and interquartile range for saphenous vein harvests was larger than radial artery harvests. The largest median force and torque generated in the vein was 11.654 N [posterior] and 0.661 Nm [- frontal], whereas in the artery was 6.163 N [anterior] and 0.381 Nm [+ frontal], respectively. CONCLUSION: The distribution of force and torque peaks in the retractor was found for endoscopic vessel harvests. This data can be used to design a haptic user interface, and to establish expert benchmarks for learning curve evaluation.
PURPOSE: In the operating theatre surgeons are accustomed to using spatially navigated tools in conjunction with standard clinical imaging during a procedure. This gives them a good idea where they are in the patients’ anatomy but doesn’t provide information about the type of tissue they are dissecting. In this paper we demonstrate an integrated system consisting of a spatially navigated surgical electrocautery combined with real-time molecular analysis of the dissected tissue using mass spectrometry. METHODS: Using the 3D Slicer software package, we have integrated a commercially available neurosurgical navigation system with an intra-operative mass spectrometer (colloquially referred to as the intelligent knife, or iKnife) that analyzes the charged ions in the smoke created during cauterization. We demonstrate this system using a simulated patient comprised of an MRI scan from a brain cancer patient deformably registered to a plastic skull model. On the skull model we placed porcine and bovine tissues to simulate cancerous and healthy tissue, respectively. We built a PCA/LDA model to distinguish between these tissue types. The tissue classifications were displayed in a spatially localized manner in the pre-operative imaging, in both 2D and 3D views. RESULTS: We have demonstrated the feasibility of performing spatially navigated intra-operative analysis of tissues by mass spectrometry. We show that machine learning can classify our sample tissues, with an average computed confidence of 99.37 % for porcine tissue and 99.36% for bovine tissue. CONCLUSION: In this paper we demonstrate a proof of concept system for navigated intra-operative molecular analysis. This system may enable intra-operative awareness of spatially localized tissue classification during dissection, information that is especially useful in tumor surgeries where margins may not be visible to the unassisted eye.
PURPOSE: MR-guided injections are safer for the patient and the physician than CT-guided interventions but require a significant amount of hand-eye coordination and mental registration by the physician. We propose a low-cost, adjustable, handheld guide to assist the operator in aligning the needle in the correct orientation for the injection. METHODS: The operator adjusts the guide to the desired insertion angle as determined by an MRI image. Next, the operator aligns the guide in the image plane using the horizontal laser and level gradient. The needle is inserted into the sleeve of the guide and inserted into the patient. To evaluate the method, two operators inserted 5 needles in two facet joints of a lumbar spine phantom. Insertion points, final points and trajectory angles were compared to the projected needle trajectory using an electromagnetic tracking system. RESULTS: On their first attempt, operators were able to insert the needle into the facet joint 85% of the time. On average, operators had an insertion point error of 2.92 ± 1.57 mm, a target point error of 3.39 ± 2.28 mm, and a trajectory error of 3.98 ± 2.09 degrees. CONCLUSION: A low-cost, adjustable, handheld guide was developed to assist in correctly positioning a needle in MR guided needle interventions. The guide is as accurate as other needle placement assistance mechanisms, including the biplane laser guides and image overlay devices when used in lumbar facet joint injections in phantoms.
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