RESUMEN
INTRODUCTION: The aim of the study was to demonstrate the feasibility of a prototype for accelerometer-based guidance for percutaneous CT-guided punctures and compare it with free-hand punctures. MATERIAL AND METHODS: The prototype enabled alignment with the CT coordinate system and a wireless connectivity. Its feasibility was tested in a swine cadaver model: 20 out-of-plane device-assisted punctures performed without intermittent control scans (one-step punctures) were evaluated regarding deviation to target and difference between planned and obtained angle. Thereafter, 22 device-assisted punctures were compared with 20 free-hand punctures regarding distance to target, deviation from the planned angle, number of control scans and procedure time. Differences were compared with the Mann-Whitney U-test (p < .05). RESULTS: The one-step punctures revealed a deviation to target of 0.26 ± 0.37 cm (axial plane) and 0.21 ± 0.19 cm (sagittal plane) and differences between planned and performed puncture angles of 0.9 ± 1.09° (axial plane) and 1.15 ± 0.91° (sagittal planes). In the comparative study, device-assisted punctures showed a significantly higher accuracy, 0.20 ± 0.17 cm vs. 0.30 ± 0.21 cm (p < .05) and lower number of required control scans, 1.3 ± 1.1 vs. 3.7 ± 0.9 (p < .05) compared with free-hand punctures. CONCLUSION: The accelerometer-based device proved to be feasible and demonstrated significantly higher accuracy and required significantly less control scans compared to free-hand puncture.
Asunto(s)
Punciones , Tomografía Computarizada por Rayos X , Acelerometría , Animales , Agujas , Porcinos , Tomografía Computarizada por Rayos X/métodosRESUMEN
PURPOSE: Assess electromagnetically guided in situ fenestration of juxtarenal aortic stent grafts in an in vivo model. METHODS: Using a newly developed electromagnetic guidance system together with a modified, electromagnetically guidable catheter with steerable tip, an electromagnetically trackable guidewire and a custom in situ fenestrateable stent graft, a series of seven animal experiments was performed. In a swine model, stent grafts were placed juxtarenally, covering the renal arteries. Subsequently, the perfusion of the renal arteries was restored using electromagnetically guided in situ fenestration of the graft at the renal ostia followed by covered stent placement. Intervention times and technical success were assessed. RESULTS: The individual components were successfully combined for the animal experiments. Thirteen of fourteen fenestration experiments in seven animals were successful in restoring perfusion through in situ fenestration. Fenestration (catheter introduction-guidewire placement in renal artery across graft) could be achieved in on average 10.5 ± 9.2 min, and subsequent covered stent placement (guidewire placement-covered stent placement) took on average 32.7 ± 17.5 min. No significant differences between left and right side reperfusion times could be detected. Reperfusion in <30 min was achieved in 3/14 attempts. CONCLUSION: Electromagnetically navigated in situ aortic fenestration for juxtarenal aortic stent grafts was feasible in a healthy animal model. Identified remaining challenges were: shortening the procedure to avoid long warm ischemia times, using an aortic aneurysm animal model, and improving the stability of the stent graft material.
Asunto(s)
Aneurisma de la Aorta Abdominal/cirugía , Implantación de Prótesis Vascular/métodos , Fenómenos Electromagnéticos , Procedimientos Endovasculares/métodos , Arteria Renal/cirugía , Stents , Animales , Implantación de Prótesis Vascular/instrumentación , Catéteres , Modelos Animales de Enfermedad , Procedimientos Endovasculares/instrumentación , Femenino , Humanos , Proyectos Piloto , Diseño de Prótesis , Radiología Intervencionista/métodos , Porcinos , Resultado del TratamientoRESUMEN
OBJECTIVES: To develop an electromagnetic navigation technology for transjugular intrahepatic portosystemic shunt (TIPS) creation and translate it from phantom to an in-vivo large animal setting. MATERIAL AND METHODS: A custom-designed device for TIPS creation consisting of a stylet within a 5 French catheter as well as a software prototype were developed that allow real-time tip tracking of both stylet and catheter using an electromagnetic tracking system. Feasibility of navigated TIPSS creation was tested in a phantom by two interventional radiologists (A/B) followed by in-vivo testing evaluation in eight domestic pigs. Procedure duration and number of attempts needed for puncture of the portal vein were recorded. RESULTS: In the phantom setting, intervention time to gain access to the portal vein (PV) was 144 ± 67 s (A) and 122 ± 51 s (B), respectively. In the in-vivo trials, TIPS could be successfully completed in five out of eight animals. Mean time for the complete TIPS was 245 ± 205 minutes with a notable learning curve towards the last animal. CONCLUSIONS: TIPS creation with the use of electromagnetic tracking technology proved to be feasible in-vitro as well as in-vivo. The system may be useful to facilitate challenging TIPSS procedures.
Asunto(s)
Fenómenos Electromagnéticos , Procedimientos Quirúrgicos Mínimamente Invasivos/instrumentación , Derivación Portosistémica Intrahepática Transyugular/instrumentación , Ultrasonografía Intervencional/métodos , Animales , Diseño de Equipo , PorcinosRESUMEN
BACKGROUND: Electromagnetic tracking is a relatively new technique that allows real time navigation in the absence of radiation. The aim of this study was to prove the feasibility of this technique for the treatment of posterior pelvic ring fractures and to compare the results with established image guided procedures. METHODS: Tests were performed in pelvic specimens (Sawbones®) with standardized sacral fractures (Type Denis I or II). A gel matrix simulated the operative approach and a cover was used to disable visual control. The electromagnetic setup was performed by using a custom made carbon reference plate and a prototype stainless steel K-wire with an integrated sensor coil. Four different test series were performed: Group OCT: Optical navigation using preoperative CT-scans; group O3D: Optical navigation using intraoperative 3-D-fluoroscopy; group Fluoro: Conventional 2-D-fluoroscopy; group EMT: Electromagnetic navigation combined with a preoperative Dyna-CT. Accuracy of screw placement was analyzed by standardized postoperative CT-scan for each specimen. Operation time and intraoperative radiation exposure for the surgeon was documented. All data was analyzed using SPSS (Version 20, 76 Chicago, IL, USA). Statistical significance was defined as p< 0.05. RESULTS: 160 iliosacral screws were placed (40 per group). EMT resulted in a significantly higher incidence of optimal screw placement (EMT: 36/40) compared to the groups Fluoro (30/40; p< 0.05) and OCT (31/40; p< 0.05). Results between EMT and O3D were comparable (O3D: 37/40; n.s.). Also, the operation time was comparable between groups EMT and O3D (EMT 7.62 min vs. O3D 7.98 min; n.s.), while the surgical time was significantly shorter compared to the Fluoro group (10.69 min; p< 0.001) and the OCT group (13.3 min; p< 0.001). CONCLUSION: Electromagnetic guided iliosacral screw placement is a feasible procedure. In our experimental setup, this method was associated with improved accuracy of screw placement and shorter operation time when compared with the conventional fluoroscopy guided technique and compared to the optical navigation using preoperative CT-scans. Further studies are necessary to rule out drawbacks of this technique regarding ferromagnetic objects.
Asunto(s)
Fijación Interna de Fracturas/métodos , Fracturas Óseas/cirugía , Ilion/cirugía , Modelos Anatómicos , Sacro/cirugía , Cirugía Asistida por Computador/métodos , Materiales Biomiméticos/química , Tornillos Óseos , Radiación Electromagnética , Fijación Interna de Fracturas/instrumentación , Fracturas Óseas/diagnóstico por imagen , Fracturas Óseas/patología , Humanos , Ilion/diagnóstico por imagen , Ilion/patología , Imagenología Tridimensional/instrumentación , Imagenología Tridimensional/métodos , Sacro/diagnóstico por imagen , Sacro/patología , Cirugía Asistida por Computador/instrumentación , Factores de Tiempo , Tomografía Computarizada por Rayos X/instrumentación , Tomografía Computarizada por Rayos X/métodosRESUMEN
PURPOSE: Percutaneous punctures are often performed under computed tomography (CT) guidance using a freehand method. Especially in challenging cases, initial accuracy of the needle placement is highly dependent on the radiologist's experience. Thus, a miniature lightweight guidance device was developed which is capable of assisting a radiologist during the needle placement process. METHODS: The device utilizes an accelerometer to measure the needle's tilt by calculating a set of orientation angles. This set can be matched with the coordinate system of the CT imaging software during a simple alignment process. After that, the needle's orientation can be expressed in terms of projected angles in the axial and sagittal planes. The accuracy of the device was evaluated in a phantom study, and initial clinical trials were carried out performing facet joint punctures in a swine cadaver. RESULTS: The sensor was embedded in a cube with dimensions of [Formula: see text] and a total weight of about 11 g which can be attached to the puncture needle at its rear end or handgrip. A graphical user interface (GUÌ) has been created offering visual real-time orientation guidance. Results of the phantom experiments showed differences between planned target and performed puncture angles of [Formula: see text] for in-plane and [Formula: see text] for out-of-plane punctures. CONCLUSION: The results of the phantom and ex vivo study suggest that the device is useful to assist a radiologist in CT-guided percutaneous punctures and helps navigating the needle with high precision.
Asunto(s)
Acelerometría , Punciones/métodos , Tomografía Computarizada por Rayos X/métodos , Articulación Cigapofisaria/diagnóstico por imagen , Animales , Humanos , Reproducibilidad de los Resultados , Programas Informáticos , PorcinosRESUMEN
This work presents concepts for complex endovascular procedures using electromagnetic navigation technology (EMT). Navigation software interfacing a standard commercially available navigation system was developed, featuring registration, electromagnetic field distortion correction, breathing motion detection and gating, and state-of-the-art 3D imaging post processing. Protocols for endovascularly placed, in-situ fenestrated abdominal aortic stent grafts and an EMT guided transjugular intrahepatic portosystemic shunt (TIPSS) creation have been designed. A dedicated set of interventional devices was developed for each of the procedures: For aortic in-situ fenestration a combination of high-porosity stentgrafts, steerable catheters and electromagnetically navigated guidewires was used, for TIPSS a dual-navigated (sheath and stylet) TIPSS-device was designed and manufactured. The developed devices underwent phantom testing, in preparation for animal experiments to prove the feasibility of the approach. Once established, these systems could aid in performing these challenging interventional radiology procedures, exploiting the unique characteristics of electromagnetic navigation and solving multiple of the problems associated with these interventions being performed under X-ray fluoroscopy, such as lacking real-time 3D information or extensive exposure to ionizing radiation.