Navigation System VectorVision Research Articles

Imaging-Based Surgical Navigated 125i Interstitial Brachytherapy for Locally Advanced Salivery Gland Carcinoma

The precise placement of the needles and seeds is mandatory in interstitial brachytherapy. This study is to explore the practice of accurate positioning of imaging-based surgical navigated 125i interstitial brachytherapy for treatment of locally advanced salivery gland carcinoma. Seventeen patients with locally advanced salivery gland carcinoma were included in this retrospective study. Before 125I implants, the implantation plan was made through the brachytherapy treatment planning system software based on patient’s CT. The template was designed by using Mimics and Geomagic software based on the implantation plan and made through rapid prototyping technique. The template data in STL format and CT were imported into the iPlan CMF software, merged into one object according to the 3-D appearance of the skin and became the navigation plan, which was transferred to the VectorVision navigation system before implantation. During the implantation, the template was placed to the planned position by the guidance of the navigation plan. The needles were implanted using the template and navigation plan guidance, to ensure that all needles were in the expected position and depth. After implants, treatment quality evaluation was made by TPS based on the post-implantation CT. The implantations of all patients were performed sucessfully under navigation plan guidance. The seeds and dosages distribution (D90,V100,V150) were well meet the treatment requirement. The navigation system will be a very useful clinical tool for interstitial brachytherapy applications. Clinical practice confirms that this approach can facilitate easier and more accurate implantation.

Best Matching

Computer navigation systems are increasingly becoming an integral part of the surgical routine in orthopedic and trauma surgery due to improvements in intraoperative visualization procedures. The matching, i.e. data alignment between virtual and therapeutic objects, is however still a persisting problem. In recent years various matching procedures have been developed to attempt to solve the problem. In this study we compared three matching procedures using the VectorVision navigation system. For each matching procedure three artificial models of the lumbar spine (TH10-Os sacrum, Synbone, Malans CH) were used with the VectorVision system as navigation system (BrainLAB, Feldkirchen/Siemens, Erlangen, Germany). The experimental setup was standardized for the different navigational methods. First a CT scan of the models was acquired and based on this data set a master planning for all pedicle drillings was performed. A total of 48 drillings with pairpoint, region or CT fluoromatching were accomplished and evaluated. The time periods needed for the matching procedures were documented and compared with each other. The precision of the drillings was evaluated within the postinterventional CT. Altogether 144 drillings for pedicle screws were performed on artificial models based on an identical planning for all test series. Within the experimental study of 144 drillings, only 2 perforations (1.3%) of the lateral cortical wall were detected. The time needed for the matching procedure was the shortest for region matching, followed by the pairpoint matching. The CT fluoromatching was the longest procedure. Variations in the distance of the individual drilling to the cortical wall were comparably large in all test series (on average 1.3 mm). Significant differences concerning the precision of the different matching procedures could only be shown for pairpoint matching. In our study pairpoint matching was the only procedure without misplacement and on average had the largest safety margin for drillings. Thus this method was the most precise procedure. The region matching procedure offers the advantage of the fastest matching with comparable precision.

Navigated versus conventional drilling of the knee in a model of obesity

Abstract Core decompression by exact drilling into ischemic lesions of the femoral condyle stays a challenging procedure, particularly in obese patients. The precision of fluoroscopically-based drilling compared to conventional drilling was evaluated in an in-vitro model for obesity. 40 sawbones were prepared mimicking osteonecrosis in obese patients. 20 sawbones were drilled by guidance of an intraoperative navigation system VectorVision® (BrainLAB, Munich, Germany); the other 20 sawbones were conventionally drilled by fluoroscopic control only. Regarding the distance to the desired mid-point of the lesion, a statistically significant difference with 0.55 mm in the navigated group and 1.19 mm in the control group could be stated (p<0.001). Significant differences were further found for the number of drilling corrections (p<0.001) and radiation time needed (p<0.001). Even in difficult circumstances as in obese patients, the drilling guided by the VectorVision®-navigation system shows high precision with simultaneous enormous reduction of radiation time.

Precision of computer-assisted core decompression drilling of the femoral head

Osteonecrosis of the femoral head is a local destructive disease with progression into devastating stages. Left untreated it mostly leads to severe secondary osteoarthrosis and early endoprosthetic joint replacement. Core decompression by exact drilling into the ischemic areas can be performed in early stages according to Ficat or ARCO. Computer-aided surgery might enhance the precision of the drilling and lower the radiation exposure time of both staff and patients. The aim of this study was to evaluate the precision of the fluoroscopically based VectorVision navigation system in an in vitro model. Thirty sawbones were prepared with a defect filled up with a radiopaque gypsum sphere mimicking the osteonecrosis. Twenty sawbones were drilled by guidance of an intraoperative navigation system VectorVision (BrainLAB, Munich, Germany) and 10 sawbones by fluoroscopic control only. No gypsum sphere was missed. There was a statistically significant difference regarding the three-dimensional deviation (Euclidian norm) as well as maximum deviation in x-, y- or z-direction (maximum norm) to the desired mid-point of the lesion, with a mean of 0.51 and 0.4 mm in the navigated group and 1.1 and 0.88 mm in the control group, respectively. Furthermore, significant difference was found in the number of drilling corrections as well as the radiation time needed: no second drilling or correction of drilling direction was necessary in the navigated group compared to 1.4 in the control group. The radiation time needed was less than 1 s compared to 3.1 s, respectively. The fluoroscopy-based VectorVision navigation system shows a high feasibility of computer-guided drilling with a clear reduction of radiation exposure time and can therefore be integrated into clinical routine. The additional time needed is acceptable regarding the simultaneous reduction of radiation time.

Image-Guided Endonasal Transsphenoidal Microsurgical Treatment of Recurrent Microadenomas of the Pituitary Gland

Neuronavigation is a commonly used technology that provides continuous, three-dimensional information for the precise localization of and surgical trajectory to brain lesions. This study was performed to evaluate the role that navigation can play in assisting microsurgical transsphenoidal surgery for precise localization and removal of recurrent pituitary tumours while simultaneously preserving pituitary gland function. During a 6-month period -- July 2004 until December 2004 -- 9 patients with recurrent pituitary tumours (5 female and 4-male) were treated with navigation-guided transsphenoidal microsurgical resection. Surgery was performed via a paraseptal or endonasal transsphenoidal approach. The navigation system Vector Vision (Brain Lab, Heimstetten, Germany) allowed precise localization of the tumours (7 hormonal active and 2 inactive microadenomas) in respect to the pituitary gland, the carotid arteries and the cavernous sinus. Postoperative MRI investigations of the 9 patients treated with image-guided transsphenoidal microsurgery, showed total tumour removal in 7 (77 %) patients and subtotal removal in 2 patients (23 %). One patient (11 %) developed a cerebral spinal fluid (CSF) leak and was treated conservatively. One patient (11 %) had preoperative insufficiency of the corticotrope axis which remained unchanged postoperatively. Of the remaining 8 patients who did not have preoperative endocrinological disturbance, only one (12 %) developed postoperative insufficiency of the corticotrope axis. Out of the 7 patients with hormone active tumours, 5 (72 %) patients showed no more postoperative hormonal activity. Microneurosurgical transsphenoidal techniques combined with image-guided systems can precisely define the localization and removal of lesions in the sella region with respect to the margins of important anatomical structures in the neighbourhood and the endocrinological functionality of the pituitary gland.

Indications and limitations of intraoperative navigation in maxillofacial surgery

Purpose Although primarily developed for neurosurgical application, intraoperative navigation has gained acceptance even in maxillofacial surgery with an increasing field of indications. We want to demonstrate our clinical experiences, focusing on the indications and limitations of intraoperative navigation. Materials and methods In our department, the navigation system VectorVision 2 (BrainLAB, Heimstetten, Germany) is used. The accuracy of this referencing method, consisting of a cortical fixed reference system and surface scanning, was checked by anatomic landmarks. Surgical treatment of 20 patients was performed with the help of the navigation system. Results The VectorVision system proved to be a useful supplement during the surgical exploration of complex anatomic regions. However, resolution of imaging data sets, errors of image fusion, and discrepancies during referencing increased the inaccuracy before surgery. The main problem was the topographic changes caused by surgery, resulting in discrepancies between the preoperative image data and the surgical site. In one case suffering from a meningioma extending to the neck, topography was changed by surgery making navigation inaccurate. Conclusion Generally, a promising field for intraoperative navigation systems were small surgical approaches allowing only limited exposure. From our point of view, additional promising indications include vast tumors or recurrent tumors because of altered anatomy with lost landmarks during surgery. The same was the case of patients suffering from plexiform neurofibroma caused by neurofibromatosis type I. Further, intraoperative navigation was helpful to determine the position of foreign bodies during imaging, making the intraoperative location easier.

Radiological results of image-based and non-image-based computer-assisted total knee arthroplasty.

Restoration of the mechanical limb axis and accurate component orientation are two major factors affecting the long-term results after total knee replacement (TKR). Different navigation systems are available to improve the outcome. Image-based systems require pre-operative CT scans, while non-image-based systems gain all necessary information intra-operatively during a registration process. We studied 130 patients who received a TKR either using the CT-based (Knee 1.1) or the CT-free module (CT-free Knee 1.0) of the BrainLAB Vector-Vision Navigation System. Post-operative leg alignment and component orientation was determined on long-leg coronal and lateral X-rays. Sixty of 65 patients in the CT-based group and 63/65 patients in the CT-free group had a post-operative leg axis between 3 degrees varus/valgus. No significant differences were found for varus/valgus orientation of the femoral and tibial components.

Early experiences with image-guided transoral surgery for the pathologies of the upper cervical spine.

Technical note. Three years of convincing experience with cranial neuronavigation suggested the application of the cranial software and registration method for the transoral access to the C1-C2 vertebrae. The C1-C2 vertebrae are located in close vicinity to the cranial base. If the intersegmental movements of the C0-C1/C1-C2 segments are prevented with HALO fixation, the upper cervical spine can be considered as a caudal part of the skull base and included in the extended navigation space of the skull. Three patients were selected for navigation-assisted transoral odontoidectomy. Before surgery the patients were fixed and scanned in a HALO device. The fiducials were attached supraorbitally and to both mastoids, determining a wide registration area and allowing the caudal extension of the navigation space. The BrainLAB VectorVision navigation system was used in cranial mode during the operations. Neuronavigation and fluoroscopy-controlled transoral surgery were performed with success in all three cases. The registration accuracy was 1.5, 2.7, and 3.1 mm. Image guidance during transoral exposure of the upper cervical spine offered excellent three-dimensional guidance on the ventral surface of the craniocervical junction, allowing a safer, more controlled surgery. As the targets of the transoral spinal surgery are fixed bony and ligamentous structures, no shifting occurs and continuous high navigation accuracy can be achieved. The use of the navigation can reduce the significance of the intraoperative fluoroscopy, diminishing the radiograph load of the patient and the operating room team.