Early prostate cancer detection and treatment are of major importance to reduce mortality rate. magnetic resonance (MR) imaging provides images of the prostate where an early stage lesion can be visualized. The use of robotic systems for MR-guided interventions in the prostate allows us to improve the clinical outcomes of procedures such as biopsy and brachytherapy. This work presents a novel MR-conditional robot for prostate interventions. The minimally invasive robotics in an magnetic resonance imaging environment (MIRIAM) robot has 9 degrees-of-freedom (DoF) used to steer and fire a biopsy needle. The needle guide is positioned against the perineum by a 5 DoF parallel robot driven by piezoelectric motors. A 4 DoF needle driver inserts, rotates and fires the needle during the procedure. Piezoelectric motors are used to insert and rotate the needle, while pneumatic actuation is used to fire the needle. The MR-conditional design of the robot and the needle insertion controller are presented. MR compatibility tests using T2 imaging protocol are performed showing a SNR reduction of 25% when the robot is operational within the MR scanner. Experiments inserting a biopsy needle toward a physical target resulted in an average targeting error of 1.84[Formula: see text]mm. Our study presents a novel MR-conditional robot and demonstrated the ability to perform MR-guided needle-based interventions in soft-tissue phantoms. Moreover, the image distortion analysis indicates that no visible image deterioration is induced by the robot.
Abstract-Soft miniaturized untethered grippers can be used to manipulate and transport biological material in unstructured and tortuous environments. Previous studies on control of soft miniaturized grippers employed cameras and optical images as a feedback modality. However, the use of cameras might be unsuitable for localizing miniaturized agents that navigate within the human body. In this paper, we demonstrate the wireless magnetic motion control and planning of soft untethered grippers using feedback extracted from B-mode ultrasound images. Results show that our system employing ultrasound images can be used to control the miniaturized grippers with an average tracking error of 0.4±0.13 mm without payload and 0.36±0.05 mm when the agent performs a transportation task with a payload. The proposed ultrasound feedback magnetic control system demonstrates the ability to control miniaturized grippers in situations where visual feedback cannot be provided via cameras.
Orthognathic surgery is a widely performed procedure to correct dentofacial deformities. Virtual treatment planning is an important preparation step. One advantage of the use of virtual treatment planning is the possibility to assess the accuracy of orthognathic surgery. In this study, a tool (OrthoGnathicAnalyser 2.0), which allows for quantification of the accuracy of orthognathic surgery, is presented and validated. In the OrthoGnathicAnalyser 2.0 the accuracy of the osseous chin can now be assessed which was not possible in the earlier version of the OrthoGnathicAnalyser. 30 patients who underwent bimaxillary surgery in combination with a genioplasty were selected from three different centers in the Netherlands. A pre-operative (CB)CT scan, virtual treatment planning and postoperative (CB)CT scan were required for assessing the accuracy of bimaxillary surgery. The preoperative and postoperative (CB)CT scans were aligned using voxel-based matching. Furthermore, voxel-based matching was used to align the pre-operative maxilla, mandible and rami towards their postoperative position whereas surface-based matching was used for aligning the pre-operative chin towards the postoperative position. The alignment resulted in a transformation matrix which contained the achieved translations and rotations. The achieved translations and rotations can be compared to planning values of the virtual treatment plan. To study the reproducibility, two independent observers processed all 30 patients to assess the inter-observer variability. One observer processed the patients twice to assess the intra-observer variability. Both the intra- and inter-observer variability showed high ICC values (> 0.92) and low measurement variations (< 0.673±0.684mm and < 0.654±0.824°). The results of this study show that the OrthoGnathicAnalyser 2.0 has an excellent reproducibility for quantification of skeletal movements between two (CB)CT scans.
Needle-based procedures are commonly performed for cancer diagnosis and treatment. Imaging modalities are used to visualize the needle tip and the target during these needle insertion procedures. Among the available imaging techniques, magnetic resonance (MR) offers the best tissue contrast, where detection of an early stage cancer is possible. MR-guided needle insertions are currently performed with rigid needles, which have limited steerability. Flexible needles have been introduced to increase the steerability during the insertion. In this paper, we present a preliminary evaluation of a steering method for flexible bevel-tipped needles using MR as an imaging modality. The steering algorithm uses a needle deflection model to predict the tip motion and calculate the optimal rotation to reach the target. The best sequence of rotations are defined by an optimization algorithm based on the Nelder-Mead technique. The needle tip and the target are manually tracked through a graphical user interface. The needle is inserted by a device fabricated with MR-compatible material. The MR-guided flexible needle steering is evaluated by a series of insertions in two phantoms with real obstacles and targets. The average targeting error with flexible needles is 4.3mm, which is 28% lower than the values reported in the literature with rigid needles. The results indicate the feasibility of MR-guided flexible needle insertions.
Background Conflicting data exist regarding the effects of deep neuromuscular blockade (NMB) on abdominal dimensions during laparoscopic procedures. We performed a clinical study to establish the influence of moderate and deep neuromuscular blockade (NMB) on the abdominal working space, measured by Magnetic Resonance Imaging (MRI), during laparoscopic donor nephrectomy with standard pressure (12 mmHg) pneumoperitoneum under sevoflurane anaesthesia. Methods Ten patients were intraoperatively scanned three times in the lateral decubitus position, with pneumoperitoneum maintained by a mobile insufflator. The first scan without NMB (T1) was followed by scans with moderate (T2) and deep NMB (T3). The skin-sacral promontory (S-SP) distance was measured, and 3D pneumoperitoneum volumes were reconstructed. Results The mean difference in the S-SP distance was -0.32 cm between T2 and T3 (95% CI -1.06 - 0.42 cm; p = 0.344) and + 2.1 cm between T1 and T2 (95% CI 0.81 - 3.39 cm; p = 0.006). The mean differences in pneumoperitoneum volume were 166 mL between T2 and T3 (95% CI, 5 - 327 mL; p = 0.044) and 108 mL between T1 and T2 (95% CI, -273 - 488 mL; p = 0.525). The pneumoperitoneum volume showed high inter-individual variability and no increase in three patients with a high volume at T1. Conclusions During laparoscopic surgery in the lateral decubitus position with standard pressure under sevoflurane anaesthesia, deep NMB did not increase the S-SP distance compared to moderate NMB. Moderate NMB increased the S-SP distance by a mean of 2.1 cm (15.2%) compared with no NMB. The mean pneumoperitoneum volume increased slightly from moderate to deep NMB, with high inter-individual variability. Trial registration Clinicaltrials.gov ID: NCT03287388.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.