Neurosurgical Navigation System Research Articles

SAMCOR: A robust and precise co-registration algorithm for brain CT and MR imaging

ObjectiveCurrent methods for co-registration of computed tomography (CT) and magnetic resonance (MR) brain imaging employ optimization-based cost functions of advanced statistical metrics to align datasets (e.g. mutual information, MI). Yet the inherent differences between these modalities still lead to occasional failures of registration. To address these limitations, we developed a novel approached termed sequence adaptive multimodal co-registration (SAMCOR), which is robust to intensity, feature, and scanner-based differences. MethodsSAMCOR was validated using 152 CT and MRI datasets from subjects implanted with intracranial electrodes for evaluation of medically-refractory epilepsy. Alignment outcomes were compared against five current open-source co-registration algorithms and a widely used commercial neurosurgical navigation system and classified as aligned/not-aligned relative to manually co-registered datasets. ResultsSAMCOR was the only method to align all 152 datasets (100%), while success rates for existing algorithms ranged from 3% to 82%. Given the time-intensive nature of manual verification, we further developed a metric to automatically quantify co-registration accuracy using Dice Similarity Coefficients (DSC). We applied a binary classification analysis to evaluate this DSC metric performance against traditional mutual information (MI) metrics for predicting alignment outcomes. The DSC metric demonstrated significantly higher positive and negative predictive values (0.93 and 0.97, respectively) than MI (0.79 and 0.87, respectively). The DSC classifier accuracy was 94.7% (vs 83.2% for MI). ConclusionsOur novel approaches for CT-MRI co-registration and quantitative alignment outcome analysis demonstrate significant advancements of the state-of-the-art for intermodal image co-registration with clinical relevance in patients with implanted intracranial devices.

Three-dimensional-printed marker-based augmented reality neuronavigation: a new neuronavigation technique.

The aim of this study was to assess the precision and feasibility of 3D-printed marker-based augmented reality (AR) neurosurgical navigation and its use intraoperatively compared with optical tracking neuronavigation systems (OTNSs). Three-dimensional-printed markers for CT and MRI and intraoperative use were applied with mobile devices using an AR light detection and ranging (LIDAR) camera. The 3D segmentations of intracranial tumors were created with CT and MR images, and preoperative registration of the marker and pathology was performed. A patient-specific, surgeon-facilitated mobile application was developed, and a mobile device camera was used for neuronavigation with high accuracy, ease, and cost-effectiveness. After accuracy values were preliminarily assessed, this technique was used intraoperatively in 8 patients. The mobile device LIDAR camera was found to successfully overlay images of virtual tumor segmentations according to the position of a 3D-printed marker. The targeting error that was measured ranged from 0.5 to 3.5 mm (mean 1.70 ± 1.02 mm, median 1.58 mm). The mean preoperative preparation time was 35.7 ± 5.56 minutes, which is longer than that for routine OTNSs, but the amount of time required for preoperative registration and the placement of the intraoperative marker was very brief compared with other neurosurgical navigation systems (mean 1.02 ± 0.3 minutes). The 3D-printed marker-based AR neuronavigation system was a clinically feasible, highly precise, low-cost, and easy-to-use navigation technique. Three-dimensional segmentation of intracranial tumors was targeted on the brain and was clearly visualized from the skin incision to the end of surgery.

Acquisition of point cloud in CT image space to improve accuracy of surface registration: Application to neurosurgical navigation system

One important technique of surgical navigation is surface registration that matches coordinates in two different spaces. We proposed a novel method to extract an optimal point cloud in image space corresponding to the point cloud in patient space to improve the registration accuracy. In the hemispherical study, our proposed method demonstrated a reduced surface registration error (SRE) and target registration error (TRE) compared to the conventional method in all cases (number of points, distribution, noise). In the phantom study, the SRE and TRE were low and stable in the proposed method, with SRE reduced by 22 % and TRE by 18 % (p < 0.05). The proposed method was not affected by the number of points, distribution, or noise in the point cloud, and it could improve the registration accuracy without the aid of additional equipment.

Reliability of Residual Tumor Estimation Based on Navigation Log.

The mass of residual tumors has previously been estimated using time-series records of the position of surgical instruments acquired from neurosurgical navigation systems (navigation log). This method has been shown to be useful for rapid evaluation of residual tumors during resection. However, quantitative analysis of the method’s reliability has not been sufficiently reported. The effect of poor log coverage is dominant in previous studies, in that it did not highlight other disturbance factors, such as intraoperative brain shift. We analyzed 25 patients with a high log-acquisition rate that was calculated by dividing the log-available time by the instrument-use time. We estimated the region of resection using the trajectory of surgical instrument that was extracted from the navigation log. We then calculated the residual tumor region and measured its volume as log-estimation residual tumor volume (RTV). We evaluated the correlation between the log-estimation RTV and the RTV in the post-resection magnetic resonance (MR) image. We also evaluated the accuracy of detecting the residual tumor mass using the estimated residual tumor region. The log-estimation RTV and the RTV in the post-resection MR image were significantly correlated (correlation coefficient = 0.960; P <0.001). The presence of patient-wise residual tumor mass was detected with a sensitivity of 81.8% and a specificity of 92.9%. The individual residual tumor mass was detected with a positive predictive value of 72%. Estimation of residual tumor with adequate log coverage appears to be a suitable method with a high reliability. This method can support rapid decision-making during resection.

The scalp localization system of neurosurgery based on augmented reality theory

Neurosurgery navigation system, which is expensive and complicated to operate, has a low penetration rate, and is only found in some large medical institutions. In order to meet the needs of other small and medium-sized medical institutions for neurosurgical navigation systems, the scalp localization system of neurosurgery based on augmented reality (AR) theory was developed. AR technology is used to fuse virtual world images with real images. The system integrates computed tomography (CT) or magnetic resonance imaging (MRI) with the patient's head in real life to achieve the scalp positioning. This article focuses on the key points of Digital Imaging and Communications in Medicine (DICOM) standard, three-dimensional (3D) reconstruction, and AR image layer fusion in medical image visualization. This research shows that the system is suitable for a variety of mobile phones, can achieve two-dimensional (2D) image display, 3D rendering and clinical scalp positioning application, which has a certain significance for the auxiliary neurosurgical head surface positioning.

Localization of Intracranial Lesions Using Superficial Stereotaxic Cranial Lesion Locator Based on Magnetic Resonance Images.

Detection of a deep-seated lesion located in the brain parenchyma and major neuroanatomical sites is a critical issue in neurosurgery. Some neurosurgical cranial navigation systems have been developed that are available; however, some preparation is necessary, including the installation of complex computer software programs and obtaining specific neuroradiological images. The purpose of this experimental study was to design and evaluate a superficial stereotaxic frameless lesion locator in order to localize mass lesions within the brain. A superficial stereotaxic frameless lesion locator system was designed using cardboard and the Cartesian coordinate system as a reference framework. This material was used in a model creating printed magnetic resonance images in the superficially marking of the lesion. This material easily located the lesion placement and superficially projected the lesion location. The results of this study revealed that the superficial stereotaxic frameless lesion location procedure using a coordinate cardboard locator is a safe, fast, and simple procedure. This procedure provides an accurate means of locating the target lesion seated within the brain parenchyma. When compared with other models, we found that this device is reliable and has a high rate of superficial lesion detection. A superficial lesion locator may be used in clinical practice. This experimental study demonstrated the usability and reliability of the procedure. Additional detailed investigations are necessary to improve the procedure.

Technical feasibility of integrating 7T anatomical MRI in image-guided radiotherapy of glioblastoma: a preparatory study.

The use of 7 Tesla (T) magnetic resonance imaging (MRI) has recently shown great potential for high-resolution soft-tissue neuroimaging and visualization of microvascularization in glioblastoma (GBM). We have designed a clinical trial to explore the value of 7T MRI in radiation treatment of GBM. For this aim we performed a preparatory study to investigate the technical feasibility of incorporating 7T MR images into the neurosurgical navigation and radiotherapy treatment planning (RTP) systems via qualitative and quantitative assessment of the image quality. The MR images were acquired with a Siemens Magnetom 7T whole-body scanner and a Nova Medical 32-channel head coil. The 7T MRI pulse sequences included magnetization-prepared two rapid acquisition gradient echoes (MP2RAGE), T2-SPACE, SPACE-FLAIR and gradient echo sequences (GRE). A pilot study with three healthy volunteers and an anthropomorphic 3D phantom was used to assess image quality and geometrical image accuracy. The MRI scans were well tolerated by the volunteers. Susceptibility artefacts were observed in both the cortex and subcortical white matter at close proximity to air-tissue interfaces. Regional loss of signal and contrast could be minimized by the use of dielectric pads. Image transfer and processing did not degrade image quality. The system-related spatial uncertainty of geometrical distortion-corrected MP2RAGE pulse sequences was≤2mm. Integration of high-quality and geometrically-reliable 7T MR images into neurosurgical navigation and RTP software is technically feasible and safe.

Autostereoscopic 3D visualization and image processing system for neurosurgery

A demonstrator system for planning neurosurgical procedures was developed based on commercial hardware and software. The system combines an easy-to-use environment for surgical planning with high-end visualization and the opportunity to analyze data sets for research purposes. The demonstrator system is based on the software AMIRA. Specific algorithms for segmentation, elastic registration, and visualization have been implemented and adapted to the clinical workflow. Modules from AMIRA and the image processing library Insight Segmentation and Registration Toolkit (ITK) can be combined to solve various image processing tasks. Customized modules tailored to specific clinical problems can easily be implemented using the AMIRA application programming interface and a self-developed framework for ITK filters. Visualization is done via autostereoscopic displays, which provide a 3D impression without viewing aids. A Spaceball device allows a comfortable, intuitive way of navigation in the data sets. Via an interface to a neurosurgical navigation system, the demonstrator system can be used intraoperatively. The precision, applicability, and benefit of the demonstrator system for planning of neurosurgical interventions and for neurosurgical research were successfully evaluated by neurosurgeons using phantom and patient data sets.

Brain Tumor Surgery With 3-Dimensional Surface Navigation

Precise lesion localization is necessary for neurosurgical procedures not only during the operative approach, but also during the preoperative planning phase. To evaluate the advantages of 3-dimensional (3-D) brain surface visualization over conventional 2-dimensional (2-D) magnetic resonance images for surgical planning and intraoperative guidance in brain tumor surgery. Preoperative 3-D brain surface visualization was performed with neurosurgical planning software in 77 cases (58 gliomas, 7 cavernomas, 6 meningiomas, and 6 metastasis). Direct intraoperative navigation on the 3-D brain surface was additionally performed in the last 20 cases with a neurosurgical navigation system. For brain surface reconstruction, patient-specific anatomy was obtained from MR imaging and brain volume was extracted with skull stripping or watershed algorithms, respectively. Three-dimensional visualization was performed by direct volume rendering in both systems. To assess the value of 3-D brain surface visualization for topographic lesion localization, a multiple-choice test was developed. To assess accuracy and reliability of 3-D brain surface visualization for intraoperative orientation, we topographically correlated superficial vessels and gyral anatomy on 3-D brain models with intraoperative images. The rate of correct lesion localization with 3-D was significantly higher (P = .001, χ), while being significantly less time consuming (P < .001, χ) compared with 2-D images. Intraoperatively, visual correlation was found between the 3-D images, superficial vessels, and gyral anatomy. The proposed method of 3-D brain surface visualization is fast, clinically reliable for preoperative anatomic lesion localization and patient-specific planning, and, together with navigation, improves intraoperative orientation in brain tumor surgery and is relatively independent of brain shift.

Comparison of F-18 FET-PET with F-18 FDG-PET for biopsy planning of non-contrast-enhancing gliomas

The management of non-contrast-enhancing brain tumours largely depends on biopsy, which allows a differentiation of low-grade gliomas (LGG) from high-grade gliomas (HGG). The aim of this study was to compare positron emission tomography using 2-[(18)F]-fluoro-2-deoxy-D: -glucose (FDG-PET) and O-(2-[(18)F]-fluoroethyl)-L: -tyrosine (FET-PET) in terms of providing target regions for biopsies. Fifteen consecutive patients with newly diagnosed brain tumours (n = 11) or suspected recurrence of a known LGG (n = 4), in whom MRI demonstrated no contrast enhancement, were studied by both FET-PET and FDG-PET. FET-PET, FDG-PET and MRI data were fused, and then transferred to the neurosurgical navigation system, prior to neurosurgical interventions. Histology showed HGG (WHO grade III) in 6/15 and LGG (WHO grade II) in 9/15 patients. FET-PET revealed an increased intratumoural tracer uptake in 8/9 LGG and in 5/6 HGG. FDG-PET depicted hypermetabolic spots in 2/9 LGG and in 4/6 HGG. In 6 patients we observed an increased intratumoural uptake of both tracers. In 4 of them, the area of highest FET accumulation in the tumour corresponded to the focus of increased FDG uptake. FET-PET appears to be superior to FDG-PET for biopsy planning in non-contrast-enhancing brain tumours. FDG-PET does not provide any additional information in this issue.

A neurosurgical navigation system based on intraoperative tumour remnant estimation.

This paper proposes a method to intra-operatively visualize the process of tumour resection until complete resection is accomplished. A fuzzy connectedness method that is robust against image noises was used to identify the tumour position and volume. Based on the tumour segmentation results, the removed area and the residual tumour tissues were examined with reference to the electrocautery trace log. Unique processes that are specific to glioma resection were introduced in the method to improve the accuracy of estimation. Invalid data in the trace log were excluded, and the tumour region surrounded by valid log points was included in the removed area. The proposed system also produces an alarm to indicate whether the electrocautery is being accurately performed within the tumour area. Thus, this surgical navigation system can assist surgeons in intuitively monitoring the tumour resection process and properly removing tumour remnants. Preliminary experiments and a clinical pilot study showed the feasible application of this method.

Po-Thur Eve General-16: Development and Application of a Visualization and Navigation System for Stereotactic Deep-Brain Neurosurgeries

This work presents the development and application of a neurosurgical visualization and navigation system. Integrated with a digitized and segmented brain atlas, an electrophysiological database, and collections of final surgical targets of previous patients, this system provides valuable assistance in pre‐operative planning and intra‐operative guidance of stereotactic deep‐brain neurosurgical procedures for the treatment of Parkinson's disease, chronic pain, and essential tremor. The fusion of standardized functional and anatomical information, once registered to individual patient images, facilitates the delineation of surgical targets, surrounding structures, as well as functional borders. Three retrospective studies and one prospective study were conducted to assess the surgical target localization efficiency of this system, which is capable of non‐rigid registration, interactive manipulation and processing of clinical image data. The surgical target locations identified by an experienced stereotactic neurosurgeon using multiple electrophysiological exploratory trajectories were compared with those located by a non‐expert using this system on 36 thalamotomy, pallidotomy, thalamic deep brain stimulation (DBS), and subthalamic nucleus (STN) DBS procedures. The average displacement between the surgical target locations in both groups was 1.85±0.96mm, 1.87±0.82mm, 1.84±0.85mm, and 1.65±0.71mm for each category of surgeries respectively, indicating promising utilization of our system in stereotactic deep‐brain neurosurgical procedures, and demonstrating its capability of accurate surgical target initiation.

Efficacy of a Navigation System in Neuroendoscopic Surgery

Neuro-endoscopy is playing a greater role in the diagnosis and treatment of several types of lesions, especially in the ventricular system. However, surgical planning and intraoperative orientation during endoscopic surgery are sometimes difficult. The efficacy of a neurosurgical navigation system using three-dimensional computer graphics of magnetic resonance (MR) images in neuro-endoscopic surgery was evaluated in this study. We have developed a navigational endoscopic system designed to monitor the tip and direction of the endoscope, with the mirror marker of the navigation connected to a rigid endoscope. Eight patients, 3 cases of aqueductal stenting for isolated fourth ventricle, 3 cases of cystostomy for ependymal cyst, 1 case of septostomy for isolated lateral ventricle, and 1 case of ventricular tap in narrow ventricles, underwent endoscopic surgery using the present system. All patients underwent successful procedures with good outcomes. The present system was very useful in the cases of an accurate ventricular tap in narrow ventricles, identification of anatomic structures, and determining the appropriate route to the target point. This navigational endoscopic system improved the safety and accuracy of neuro-endoscopic surgery.

Magnetic resonance angiography image guidance for the microsurgical clipping of intracranial aneurysms: a report of two cases

To describe the integration of magnetic resonance angiography (MRA) in neuronavigation procedures for microsurgery of intracranial aneurysms. MRA was combined with standard magnetic resonance image (MRI) acquisition in the image-guided planning for the microsurgical clipping of a saccular aneurysm in two patients (one 3-mm large middle cerebral artery and one 8-mm large pericallosal artery aneurysm, diagnosed by catheter angiography in both patients) using two different neurosurgical navigation systems. Conventional 3-D T1-weighted MRI with gadolinium and MRA pulse sequences were acquired in frameless stereotactic conditions the day before surgery and thereafter registered, allowing the definition a minimally invasive straight trajectory to the aneurysm neck. MRA-guided neurosurgery allowed a direct approach to the aneurysms at their proper location, reducing the invasiveness of the approach by tailoring the bone opening and reducing the duration and extension of brain retraction. The technique also avoided unnecessary dissection and exposure of the main trunks and collateral vessels. The aneurysms were successfully eradicated without complication. Integration of MRA in the planning and neuronavigation procedure for intracranial aneurysms may minimize the morbidity related to the surgical approach. This technique may be applicable more routinely using standard neuronavigation equipment.

Efficacy of navigation in skull base surgery using composite computer graphics of magnetic resonance and computed tomography images.

The efficacy of a neurosurgical navigation system using three-dimensional composite computer graphics (CGs) of magnetic resonance (MR) and computed tomography (CT) images was evaluated in skull base surgery. Three-point transformation was used for integration of MR and CT images. MR and CT image data were obtained with three skin markers placed on the patient's scalp. Volume-rendering manipulations of the data produced three-dimensional CGs of the scalp, brain, and lesions from the MR images, and the scalp and skull from the CT. Composite CGs of the scalp, skull, brain, and lesion were created by registering the three markers on the three-dimensional rendered scalp images obtained from MR imaging and CT in the system. This system was used for 14 patients with skull base lesions. Three-point transformation using three-dimensional CGs was easily performed for multimodal registration. Simulation of surgical procedures on composite CGs aided in comprehension of the skull base anatomy and selection of the optimal approaches. Intraoperative navigation aided in determination of actual spatial position in the skull base and the optimal trajectory to the tumor during surgical procedures.

Cranionavigator combining a high-speed drill and a navigation system for skull base surgery--technical note.

Drilling of the skull base bone without damaging the important inside structures and with the correct orientation is very difficult even with the help of the anatomical landmarks. Monitoring of the location and direction of the drill tip and indications of the removed part of the bone during the drilling procedure enhances safety and achieves less invasive neurosurgery. We have developed a novel cranionavigator by combining a high-speed drill with a neurosurgical navigation system. To reduce the positional error to less than 1.5 mm, the position sensor (magnetic field sensor) must be attached 5 cm from the metallic fan portion of the drill and the sensor kept at least 10 cm away from the operating microscope. Simulation studies with the cranionavigator using two dried skulls and three cadaver heads were performed before clinical application. Clinically, this surgical instrument was used in four patients with the skull base tumor. The cranionavigator helped to safely drill the skull base bone in a shorter time by dynamic and real-time display of the precise operating site and extent of bone drilling on the preoperative computed tomography scans or magnetic resonance images. The cranionavigator is a very helpful instrument for skull base surgery in the hands of neurosurgeons with extensive expertise and anatomical knowledge.

脳外科手術支援ナビゲーションシステムの使用経験

脳腫瘍摘出術におけるナビゲーションシステムの有用性と問題点について, 磁場変換式3次元位置測定装置システムを用いて検討した.対象は脳腫瘍19例, 眼窩内腫瘍2例, および難治性てんかん4例である.腫瘍, てんかん焦点の切除範囲の同定に有用で, 特に, 術中脳表に露出していない境界不明瞭の病変に有用であった.基本的な脳外科手術手技を変えることなく, 手術支援が行われた.問題点としては金属による影響に留意しなければならない点であった.正中深部にある腫瘍, 難治性てんかんに対する脳梁離断などでは術中脳の偏位が少ないものの, 半球腫瘍では偏位が避けられないため髄液排出前に脳表の目標点を定め, 術中に経時的に観察する必要がある.

Neurosurgical navigation using a noninvasive stereoadapter

A neurosurgical navigation system incorporating a multiarticulated arm and an isocentric stereotaxic mechanism has been developed. The usefulness of the navigation system has been increased by using it in combination with Laitinen's noninvasive, accurately reproducible stereoadapter. Stereotaxic microsurgery and surgical navigation was performed successfully in 30 cases with these systems.

An articulated neurosurgical navigation system using MRI and CT images.

Neurosurgical operations sometimes involve difficulties in finding out the real positions of small-size neoplasms shown on tomographical images. The articulated navigation system, with the aid of a computer, gives ongoing positional correspondence between the position in the patient's brain and the one in the tomographic images to assist neurosurgery.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>