Preoperative Imaging Data Research Articles

Initial Experience with Intraoperative Ultrasound in Navigated Soft Tissue Operations of the Neck and Below the Base of the Skull

Ultrasound (US) is a cost effective and time saving examination method for diseases of the neck,and can be used without any known side effects or limitations. US tied into modern navigation devices may significantly improve intraoperative orientation in regions with soft tissue characteristics. 22 patients with soft tissue tumours of the head and neck underwent surgical procedures assisted by CAS system LandmarX (Medtronic) in combination with the US system DynaVievP II (Aloka). Clinical feasibility of using intraoperative US in navigated surgical procedures has been investigated by paying particular attention to the surgical approach, possible interferences from surgical instruments and time consumption. In the case of soft tissue shift, US can provide a sequence of a section of the operative field and, without delay, an instant comparison with the preoperative imaging data set. The feasibility of using this method is severely limited by the additional preparation required, the unfamiliar handling during surgery, and design-related matters. Integrating US into a navigation device could provide additional useful information for a more controlled resection of soft tissue disease of the neck and below the base of the skull.

Real-time tracking of vertebral body movement with implantable reference microsensors

Objective: In the spine, navigation techniques serve mainly to control and accurately target insertion of implants. The main source of error is that the spine is not a rigid organ, but rather a chain of semiflexible movement segments. Any intraoperative manipulation of the patient alters the geometry and volumetry as compared to the 3D volume model created from the image data. Thus, the objective of the study was to implement the theoretical principle of microsensor referencing in a model experiment and to clarify which anatomical structures are suitable for intermittent implantation of positional sensors, as illustrated with cervical vertebral bodies.Materials and Methods: Laboratory tests were conducted using 70 models of human cervical vertebral bodies. The first experiment investigated whether arbitrary movements of vertebral bodies can be tracked with the positional information from the implanted microsensors. The accuracy of this movement monitoring was determined quantitatively on the basis of positional error measurement. In the second experiment, different ventral and dorsal surgical operations were simulated on five models of the cervical spine. Quantifiable measurement values such as the spatial extension of the intervertebral space and the relative positions of the planes of the upper plates were determined.Results: With respect to the differing anatomy of the individual vertebral bodies of the cervical spine, the sensors could be placed securely with a 5 × 2 mm drill. The registration error (RE) was determined as a root mean square error. The mean value was 0.9425 mm (range: 0.57–1.2 mm; median: 0.9400 mm; SD: 0.1903 mm). The precision of the movement monitoring of the vertebral body was investigated along its three main axes. The error tolerance between post-interventional 3D reconstruction and direct measurement on the model did not exceed 1.3 mm in the distance measurements or 2.5° in the angular measurements. The tomograms on the system monitor could be updated in close to real time on the basis of the positional information from the reference sensor.Conclusions: Motion sensors implanted into the vertebral bodies communicated any change in position to the navigation system in close to real time, thus enabling the preoperative image data set to be updated. The experiments described could ultimately show that continuous real-time visualization of individual vertebral body movements along the movement axes (flexion-extension, tilting and rotation) is possible with high accuracy using implantable microsensors. A future application of such microsensors might be the integration of robot systems into spinal microsurgery.

Processing of radical prostatectomy specimens for correlation of data from histopathological, molecular biological, and radiological studies: a new whole organ technique

Aims: To develop a method of processing non-formalin fixed prostate specimens removed at radical prostatectomy to obtain fresh tissue for research and for correlating diagnostic and molecular results with preoperative...

Neue Möglichkeiten in der computergestützten Orbitachirurgie

Surgical planning and tumor margins from preoperative image data sets can be transferred to the surgical site by use of computer-assisted navigation systems. Usually registration markers are placed prior to image data acquisition in order to correlate the patient's preoperative image data set with his/her position in the operating room. Pointers are commonly used for navigation, and the position of the pointer within the surgical site is compared to its position within the image data set. With a new navigation system, patient registration can be performed without registration markers. Tumor margins and osteotomy lines can be projected onto the surgical site. With the new navigation system, which has been developed by the Sonderforschungsbereich 414 of the Deutsche Forschungsgemeinschaft, markerless patient registration is performed using the contours of the patient's face. A scanner is mounted above the operating table, which detects the surface of the surgical site intraoperatively. Osteotomy lines and tumor margins are projected onto this surface using an intense beamer. The procedure is illustrated for a patient with a meningeal tumor of the orbit. Patients can be registered with an accuracy of 1 mm. Pointers are not required to transfer the data on the surgical site. Furthermore, monitors are no longer required, since the information is projected directly on the patient's surface. Surgical planning and tumor margins can exactly be visualized within the surgical site. Ergonomics are especially improved for navigated orbitotomies via a coronal approach.

Reconstruction Options for Complex Middle Cerebral Artery Aneurysms

To describe techniques of reconstruction for unclippable and uncoilable middle cerebral artery aneurysms. A retrospective review was performed of seven patients who underwent eight operations during a 9-year period to treat complex middle cerebral artery bifurcation aneurysms not amenable to direct clipping or endovascular coiling. All preoperative and postoperative clinical and imaging data were reviewed. Follow-up was obtained for all patients via clinic visit and/or telephone. The operative techniques used included saphenous vein graft bypass (n = 1), radial artery graft interposition (n = 2), radial artery patch (n = 1), superficial temporal artery interposition graft (n = 1), superior thyroid artery interposition graft (n = 1), direct reimplantation of branch (n = 1), and reconstruction of trifurcation (n = 1). There was no mortality. Six patients had excellent outcomes with Glasgow Outcome Scale scores of 5, and one patient had a good outcome with a Glasgow Outcome Scale score of 4. Techniques for middle cerebral artery reconstruction may remain important and useful in the age of endovascular aneurysm treatment.

Causes for pedicle screw misplacement in the thoracolumbar spine and countermeasures

目的 探讨胸腰椎椎弓根螺钉误置的原因及对策.方法1996～2002年对293例脊柱疾病患者施行椎弓根螺钉内固定术发生的螺钉误置情况进行回顾性总结、分析.结果293例共置入椎弓根螺钉1256枚,螺钉植入节段错误7例,占2.38%;上胸椎(T2-7)置钉113枚,有11枚螺钉穿破椎弓根皮质,占9.74%;下胸椎(T8-12)置钉261枚,有9枚螺钉穿破椎弓根皮质,占3.45%;腰骶椎置钉882枚,有16枚穿破椎弓根皮质,占1.81%,共计36枚螺钉,占2.87%;螺钉角异常65枚,占5.81%.结论椎弓根螺钉误置与操作技术、解剖学变异及脊柱病损因素密切相关;良好的手术技巧、术前影像资料的认真观测及术中必要的影像监控是准确置钉的关键。

A novel technique using customised templates for the application of fractionated interstitial HDR brachytherapy to the tumour bed in soft-tissue sarcomas located in the extremities

Postoperative interstitial brachytherapy of limbs is challenging, because it is difficult to deliver a conformal dose to the tumour bed. We developed and assessed a new surgical fixation system for positioning guiding tubes in interstitial brachytherapy in order to achieve favourable geometry. A 28-year-old patient was treated with postoperative interstitial brachytherapy boost followed by external radiotherapy after the 11th recurrence of a desmoid tumour in the forearm. On the basis of preoperative imaging data, customised resorbable templates made of polydioxanone (PDS) were cut to fit in the space left by the resected tumour. These were strategically positioned in the tumour bed during surgery. In order to hold the brachytherapy-guiding tubes parallel for the duration of treatment, they were passed through a series of holes bored into the templates. Fixing the guiding tubes with PDS templates resulted in a fixed geometry, and thus in an optimal dose distribution with only little additional dose optimisation needed by the brachytherapy treatment planning system. An optimised dose to the tumour bed, and a reduction of dose to critical normal tissues, is achievable with this template system for sarcomas located between osseous structures. The PDS templates offer a more rigid fixation of the guiding tubes in relation to the surrounding anatomy even after the operation cavity has been closed. A tailored dose distribution can be achieved, thus reducing possible side-effects. Additionally, because of the self-resorbable nature of the material, a re-operation for template removal is not necessary. The potential advantages of this method are being further investigated.

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.

788 Investigation of Gravity-induced Brain Shift Based on a Three-dimensional Finite-element Model of the Human Brain

INTRODUCTION: Brain shift, defined as the deformation of the brain during surgery, can invalidate preoperative image data. Although an intraoperative magnetic resonance imaging system can be used to ascertain the amount of brain shift, such a system is very expensive and not useful when conducting presurgical planning. As a result, numerical models capable of predicting brain shift is a good supplemental tool for computer-assisted surgery systems. The aim of this study was to predict gravity-induced brain shift using a three-dimensional (3-D) finite-element (FE) model of the human brain. METHODS: A 3-D FE model of the human brain developed at Wayne State University was used. The model includes a detailed description of the dura, pia, falx, tentorium, ventricles, cerebrum (gray and white matter), cerebellum, and brainstem. A commercially available implicit FE code LS-NIKE3D and a postprocessing program LS-POST (version 970, LSTC, Livermore, CA) were used for analysis. RESULTS: Two head positions, a supine and 60 axial rotation positions were simulated, and a completely void cerebral spinal fluid space between the dura and pia mater were assumed before the application of gravitational force. The maximum brain shift predicted by the model for a supine and 60 axial rotation positions was 8.64 and 6.95 mm located at the anterior and right anterior region of the frontal lobe. The model predicted the largest brain shift at the highest point in the direction of gravity. Maximum model-predicted brain shifts were in the same range as experimental results reported in the literature. CONCLUSION: A 3-D FE model of the human brain has been developed to predict the brain deformation caused by gravity after dura opening. We believe that this study represents the first attempt to simulate complex features of the human brain without the need for surface deformation data to calculate the extent of brain shift.

Functional neuronavigation—risk grading for surgery in close proximity to eloquent motor cortex

BACKGROUNDTumor removal, brain swelling, the use of brain retractors, and cerebrospinal-fluid drainage all result in an intraoperative brain deformation that is known as brain shift. Thus, neuronavigation systems relying on preoperative image data have a decreasing accuracy during the surgical procedure. Intraoperative image data represent the correct anatomic situation, so their use may compensate for the effects of brain shift.METHODSIn a series of 16 brain tumor patients, we used intraoperative magnetic resonance (MR) imaging to obtain 3-D data, which were then transferred to the microscope-based neuronavigation system. With the help of bone fiducial markers these images were registered intraoperatively, updating the neuronavigation system.RESULTSIn all patients the updating of the neuronavigation system with the intraoperative MR data was successful. It led to reliable neuronavigation with high accuracy; the mean registration error of the update procedure in all patients was 1.1 mm. The updating procedure added about 15 minutes to the operation time. In all patients the area suggestive of remaining tumor was reached and the additional tumor could be resected, resulting in a complete tumor removal in 14 patients. In the remaining patients extension of the tumor into eloquent brain areas prevented a complete excision.CONCLUSIONSThe update of a neuronavigation system with intraoperative MR images reliably compensates for the effects of brain shift. This method allows completion of tumor removal in some difficult brain tumors.

Registration of preoperative and intraoperative high-field MR image data allows automatic updating of neuronavigation

Updating of neuronavigation systems with intraoperative image data is possible without repeated patient registration. Tumor remnants depicted by intraoperative imaging can be localized reliably, as well as brain shift can be compensated for.

A real-time data fusion system updating 3D organ shapes using color information from multi-directional cameras

We have been developing a data fusion system, which allows surgeons to visualize the inner structures of organs during liver surgery. The liver alters its shape dynamically during an operation. In this system, we used stereo cameras to track intraoperative liver deformation. Color markers were attached on to the liver surface and tracked by the stereo cameras. Multi-directional camera views compensated for the lack of surface data during surgical procedures, even if the surface data could not be acquired from one directional camera view. A three-dimensional (3D) organ model that represented inner structures was reconstructed from preoperative image data sets and deformed by the intraoperative data. The model was updated on the video images of the surgical field. We examined the feasibility of this data fusion system in a liver phantom examination and in an in-vivo experiment with a pig liver.

Three-dimensional ultrasound-based navigation combined with preoperative CT during abdominal interventions: a feasibility study.

Three-dimensional (3D) intraoperative ultrasound may be easier to interpret when used in combination with less noisy preoperative image data such as CT. The purpose of this study was to evaluate the use of preoperative image data in a 3D ultrasound-based navigation system specially designed for minimally invasive abdominal surgery. A prototype system has been tested in patients with aortic aneurysms undergoing clinical assessment before and after abdominal aortic stent-graft implantation. All patients were first imaged by spiral CT followed by 3D ultrasound scanning. The CT volume was registered to the patient using fiducial markers. This enabled us to compare corresponding slices from 3D ultrasound and CT volumes. The accuracy of the patient registration was evaluated both using the external fiducial markers (artificial landmarks glued on the patient's skin) and using intraoperative 3D ultrasound as a measure of the true positioning of anatomic landmarks inside the body. The mean registration accuracy on the surface was found to be 7.1 mm, but increased to 13.0 mm for specific landmarks inside the body. CT and ultrasound gave supplementary information of surrounding structures and position of the patient's anatomy. Fine-tuning the initial patient registration of the CT data with a multimodal CT to intraoperative 3D ultrasound registration (e.g., mutual information), as well as ensuring no movements between this registration and image guidance, may improve the registration accuracy. Preoperative CT in combination with 3D ultrasound might be helpful for guiding minimal invasive abdominal interventions.

Integration of MR spectroscopy into neuronavigation for stereotactic definition of tumor infiltration zone

BACKGROUNDTumor removal, brain swelling, the use of brain retractors, and cerebrospinal-fluid drainage all result in an intraoperative brain deformation that is known as brain shift. Thus, neuronavigation systems relying on preoperative image data have a decreasing accuracy during the surgical procedure. Intraoperative image data represent the correct anatomic situation, so their use may compensate for the effects of brain shift.METHODSIn a series of 16 brain tumor patients, we used intraoperative magnetic resonance (MR) imaging to obtain 3-D data, which were then transferred to the microscope-based neuronavigation system. With the help of bone fiducial markers these images were registered intraoperatively, updating the neuronavigation system.RESULTSIn all patients the updating of the neuronavigation system with the intraoperative MR data was successful. It led to reliable neuronavigation with high accuracy; the mean registration error of the update procedure in all patients was 1.1 mm. The updating procedure added about 15 minutes to the operation time. In all patients the area suggestive of remaining tumor was reached and the additional tumor could be resected, resulting in a complete tumor removal in 14 patients. In the remaining patients extension of the tumor into eloquent brain areas prevented a complete excision.CONCLUSIONSThe update of a neuronavigation system with intraoperative MR images reliably compensates for the effects of brain shift. This method allows completion of tumor removal in some difficult brain tumors.

140 consecutive cases of minimally invasive, radio-guided parathyroidectomy

The advent of highly accurate parathyroid imaging and the ever-increasing trend towards minimally invasive procedures have changed considerably the surgical approach to the patient with primary hyperparathyroidism (PHPT) caused by a single parathyroid adenoma. This study analyzes the short- and longer-term results of 140 patients who underwent minimally invasive, radio-guided parathyroidectomy. Demographic, clinical, and pre-operative imaging data, operative findings, and short- and long-term results of 140 consecutive patients operated within a 20 months period (8/1999-4/2002), were prospectively entered into a database. Immediate pre-operative sestamibi scintigraphy with skin marking of focal adenoma uptake were followed by intraoperative hand-held gamma probe for the removal of the parathyroid adenoma by unilateral minimal access surgery. Preoperative and surgical data were analyzed and correlated to outcomes, measured by success or failure to cure PHPT, associated morbidity and mortality, predictive value of localizing studies, and postoperative laboratory results in the immediate as well as long-term period. 140 patients, mean age: 55.1 +/- 14.1 years (range 19-88 years), female to male ratio 94:46 with PHPT proven by concomitantly elevated serum calcium and parathormone (PTH) levels, with a single adenoma identified by sestamibi single photon emission tomography (SPECT) scintigraphy and high-resolution sonography, underwent minimally invasive, radio-guided parathyroidectomy. Mean serum levels of preoperative calcium, phosphorus, and PTH were 11.6 +/- 0.8 mg/dL (range 9.1-14), 3.0 +/- 0.3 mg/dL, and 147.1 +/- 94.3 pg/mL (range 68-784), respectively. Overall, in 3 out of 140 patients (2.1%), focused, minimally invasive surgery failed to identify and remove the adenoma. Positive predictive value when both localizing modalities concurred was 99.2%. Positive predictive value of SPECT scan alone was 97.2%. Overall success rate was 97.8% (137/140). 24 hours postoperative mean serum calcium was 9.2 +/- 0.8 mg/dL and at 6 months mean serum calcium, phosphorus, and PTH were 9.4 +/- 1.06 mg/dL, 3.2 +/- 0.8 mg/dL, and 32.1 +/- 11.9 pg/mL, respectively (p = 0.0001). There was no mortality. In 2 patients (1.4%) there was transient vocal cord paresis and there were 8 instances of clinically significant hypocalcemia. In 3 cases (2.1%), a second adenoma manifested itself 9-14 months following surgery and was removed by minimal access procedure. Minimally invasive, radio-guided focused parathyroidectomy for a single adenoma is safe and effective in curing hyperparathyroidism with a 97% success rate. A second adenoma occurring in less than 3% may be successfully treated with a second minimal access operation. The combined positive predictive value of concurring sestamibi SPECT scintigraphy and sonography of 99.2% may increase success rate, and thus implementing this technique in patients with concurring sonography and scintigraphy may be advocated.

Coregistered intraoperative ultrasonography in resection of malignant glioma

The authors present their experience with coregistration of preoperative imaging data to intraoperative ultrasonography in the resection of high-grade gliomas, focusing on methodology and clinical observation. Images were obtained preoperatively and coregistered to intraoperative hand-held ultrasound images by merging the respective imaging coordinate systems. After patient registration and imaging calibration, the authors computed the location on the magnetic resonance (MR) space of each pixel on an ultrasound image acquired in the operating room. The data were retrospectively reviewed in 11 patients with high-grade gliomas who underwent ultrasonography-assisted resection at our institution between June 2000 and December 2002. Satisfactory coregistration of intraoperative ultrasound and preoperative MR images was accomplished in all cases. Ultrasound and MR image data were closely congruent. Preoperative setup and intraoperative use of the system were unencumbering. Based on these preliminary results, intraoperative ultrasonography is an attractive neuronavigational alternative, by which a less expensive and constraining imaging technique is used to acquire updated information. Optimal intraoperative guidance can be provided by the integration of this with other imaging studies.

Awake craniotomy in glioma surgery.

Awake craniotomy is the cheapest and most reliable method to ensure neurological integrity in cerebral gliomas that infiltrate or come close to the eloquent areas of the brain, allowing (a) the localization of eloquent cortical areas by electrical stimulation and epileptic foci by cortical recording, and (b) the monitoring of the functional integrity of awake patients while aiming at subtotal removal of the gliomatous tissue. In addition, awake craniotomy opens a brief but unique window to the living brain for (a) basic neuroscience, including verification of preoperative functional imaging data and recording of electrophysiological correlates of mental processes, and for (b) applied research, including development of innovative instrumentation for brain recording and monitoring as well as screening for potential areas to be modulated in movement disorders and chronic pain.

Hydatid Cyst Of The Diaphragm: A Case Report And Review Of The Literature

Hydatid cysts of the diaphragm (also known as extrapulmonary intrathoracic cysts) are found occasionally, with less than 100 cases reported in the literature. We report such a case and update the diagnostic and therapeutic aspects of the condition. An 18-year-old male patient was diagnosed with a right lower intra-thoracic mass. CT revealed this to be hydatid cysts. At thoracotomy, a conglomerate of three hydatid cysts originating from the diaphragm was found. The cysts were managed by endocystectomy and unroofing of the fibrous capsules. A retrospective analysis of fifty published reports of diaphragmatic hydatidosis (1960-2001) was performed together with a complimentary review of the Bulgarian literature. A total of 66 cases constitute the basis of this review estimating an incidence of 0.5-1.6%. The cysts were primary in 69.8%, the right hemidiaphragm was the most common site (72.5%), and associated hydatidosis (38.7%, predominantly hepatic and/or pulmonary) was frequently encountered. The preoperative diagnosis of diaphragmatic hydatid cysts demands a high index of suspicion and utilization of imaging methods. Treatment is only surgical and proceeds through transthoracic (83.8%) or transabdominal (16.2%) approaches. Radical surgery includes total cystectomy or pericystectomy, used in 53.7%; deroofing of the fibrous capsulae is the preferred, less traumatic procedure. Hydatid cysts should be considered in the patients with preoperative imaging data indicating cystic lesions adjacent to the diaphragm. Surgery provides the only chance of cure.

State‐of‐the‐art in orthopaedic surgical navigation with a focus on medical image modalities

AbstractThis paper presents a review of surgical navigation systems in orthopaedics and categorizes these systems according to the image modalities that are used for the visualization of surgical action. Medical images used to be an essential part of surgical education and documentation as well as diagnosis and operation planning over many years. With the recent introduction of navigation techniques in orthopaedic surgery, a new field of application has been opened. Today surgical navigation systems — also known as image‐guided surgery systems — are available for various applications in orthopaedic surgery. They visualize the position and orientation of surgical instruments as graphical overlays onto a medical image of the operated anatomy on a computer monitor. Preoperative image data such as computed tomography scans or intraoperatively generated images (for example, ultrasonic, endoscopic or fluoroscopic images) are suitable for this purpose. A new category of medical images termed ‘surgeon‐defined anatomy’ has been developed that exclusively relies upon the usage of navigation technology. Points on the anatomy are digitized interactively by the surgeon and are used to build up an abstract geometrical model of the bony structures to be operated on. This technique may be used when no other image data is available or appropriate for a given application. Copyright © 2002 John Wiley & Sons, Ltd.

Zur Berechnung von Hirnarealverschiebungen bei Hirntumoren

A precise knowledge of the localization of an intracerebral mass is a basic requirement for the planning of neurosurgical operations. Stereotactic atlases offer the possibility to adapt pre-operative imaging data onto normal anatomical conditions in the CNS. These atlases, however, reflect the standard variants of the CNS and do not allow to draw conclusions on local and secondary changes of the anatomy caused by the presence of pathological processes. The physical model proposed in this paper provides an estimate of the displacement of brain areas by an intracerebral mass. The modeling of brain parenchyma deformation is based on the mechanics of deformed media. The implementation of the model is successful in the group of primary brain tumors and meningiomas, and uses empirically-obtained data of a prospectively-selected patient population. The aim of the proposed model is, as further step, the integration and adaptation in apposite software solutions for the stereotactic orientation in the CNS.