Automatic detection and quantification of brain midline shift using anatomical marker model.

Brain midline shift (MLS) is a significant factor in brain CT diagnosis. In this paper, we present a new method of automatically detecting and quantifying brain midline shift in traumatic injury brain CT images. The proposed method automatically picks out the CT slice on which midline shift can be observed most clearly and uses automatically detected anatomical markers to delineate the deformed midline and quantify the shift. For each anatomical marker, the detector generates five candidate points. Then the best candidate for each marker is selected based on the statistical distribution of features characterizing the spatial relationships among the markers. Experiments show that the proposed method outperforms previous methods, especially in the cases of large intra-cerebral hemorrhage and missing ventricles. A brain CT retrieval system is also developed based on the brain midline shift quantification results.

Unsupervised medical image classification by combining case-based classifiers.

We introduce an automated pathology classification system for medical volumetric brain image slices. Existing work often relies on handcrafted features extracted from automatic image segmentation. This is not only a challenging and time-consuming process, but it may also limit the adaptability and robustness of the system. We propose a novel approach to combine sparse Gabor-feature based classifiers in an ensemble classification framework. The unsupervised nature of this non-parametric technique can significantly reduce the time and effort for system calibration. In particular, classification of medical images in this framework does not rely on segmentation, nor semantic-based or annotation-based feature selection. Our experiments show very promising results in classifying computer tomography image slices into pathological classes for traumatic brain injury patients.

DuraSeal-hematoma: concealed hematoma causing spinal cord compression.

STUDY DESIGN: Case description. OBJECTIVE: To present a case report which highlights a complication following the use of Duraseal in posterior cervical surgery. SUMMARY OF BACKGROUND DATA: Duraseal is increasingly used to repair cranial and spinal dural defects to prevent cerebrospinal fluid leakage. Although it is well established that the hydrogel expands after implantation and may result in compressive effects, the phenomenon of Duraseal-entrapped hematoma has not previously been reported. METHODS: The authors report a 80-year-old woman who presented with cervical myelopathy secondary to canal stenosis. The patient underwent decompressive cervical laminectomies. The surgery was complicated by an unintended durotomy. A thin layer of Duraseal was applied over the dural surface and a suction drain placed before wound closure. The patient awoke from surgery without any new neurologic deficits but experienced delayed functional deterioration. Urgent magnetic resonance imaging demonstrated an extradural hematoma with severe cord compression. RESULTS: The patient underwent urgent surgery. Intraoperatively, the Duraseal was found to have formed a restrictive layer, completely entrapping the extradural hematoma with resultant spinal cord compression. Minimal blood clot was found external to the hydrogel layer. CONCLUSION: Although Duraseal can provide an effective and water-tight dural repair, it also has the potential to "entrap" extradural bleeding which otherwise may have been evacuated by a wound drain placed under suction. Our experience has shown that Duraseal should be used judiciously with recognition of this potential complication.

Augmented reality neurosurgical planning and navigation for surgical excision of parasagittal, falcine and convexity meningiomas.

OBJECTIVE: To assess the utility of pre-operative 3-dimension (3D) visualisation and surgical planning with the Dextroscope in combination with the use of DEX-Ray-a novel augmented reality surgical navigation platform for resection of meningiomas in the falcine, convexity and parasagittal regions. METHODS AND RESULTS: Magnetic resonance imaging (MRI) and magnetic resonance venogram (MRV) images of the patients were reconstructed in 3D using the Dextroscope workstation. Using a variety of available tools, we were able to view the tumour in various surgical angles and appreciate the intricate relationship of the tumour with respect to the surrounding structures and venous anatomy. Critical draining veins both superficial and deep to the tumour were well visualised. By varying the transparency of the overlying scalp and bone we were able to preoperatively determine the ideal size of our scalp flap and bone window for surgical approach. The Dextroscope enabled us to simulate surgical opening and various trajectories of approach while the DexRay virtual reality navigation system enabled the transfer of the Dextroscope 3D planning data into the operating by displaying it in real-time video-augmented mode which further enhanced the appreciation of the tumour's location in 3D space. Four patients underwent total excision of their meningioma while one patient had near total excision with a small residual remnant left behind at the medial third of the superior sagittal sinus. All 5 patients had good neurological recovery post-operatively. CONCLUSION: The use of the Dextroscope for pre-operative surgical planning allows for appreciation of complex anatomical relationships in 3D. This appreciation is further translated for use during surgical navigation utilizing the DEX-Ray platform that provided us with the superior advantage of allowing fast and accurate surgical resection confidently.

Surgical planning for microsurgical excision of cerebral arterio-venous malformations using virtual reality technology.

BACKGROUND: To evaluate the feasibility of surgical planning using a virtual reality platform workstation in the treatment of cerebral arterio-venous malformations (AVMs) METHODS: Patient-specific data of multiple imaging modalities were co-registered, fused and displayed as a 3D stereoscopic object on the Dextroscope, a virtual reality surgical planning platform. This system allows for manipulation of 3D data and for the user to evaluate and appreciate the angio-architecture of the nidus with regards to position and spatial relationships of critical feeders and draining veins. We evaluated the ability of the Dextroscope to influence surgical planning by providing a better understanding of the angio-architecture as well as its impact on the surgeon's pre- and intra-operative confidence and ability to tackle these lesions. FINDINGS: Twenty four patients were studied. The mean age was 29.65 years. Following pre-surgical planning on the Dextroscope, 23 patients underwent microsurgical resection after pre-surgical virtual reality planning, during which all had documented complete resection of the AVM. Planning on the virtual reality platform allowed for identification of critical feeders and draining vessels in all patients. The appreciation of the complex patient specific angio-architecture to establish a surgical plan was found to be invaluable in the conduct of the procedure and was found to enhance the surgeon's confidence significantly. CONCLUSION: Surgical planning of resection of an AVM with a virtual reality system allowed detailed and comprehensive analysis of 3D multi-modality imaging data and, in our experience, proved very helpful in establishing a good surgical strategy, enhancing intra-operative spatial orientation and increasing surgeon's confidence.

Optimization of ventricular catheter placement via posterior approaches: a virtual reality simulation study.

BACKGROUND: This study aimed to evaluate 2 commonly used posterior approach entry points for ventricular cannulation and the ideal trajectories using 3-dimensional virtual reality technology. METHODS: Magnetic resonance imaging data of 10 patients without gross ventricular dilatation or distortion were retrieved and reconstructed. A stereoscopic 3-dimensional preoperative planning system was used to designate the entry points. Various trajectories were simulated. The ideal trajectory was determined as the one that provided direct entry into the atrium or body of the lateral ventricle en route to the ipsilateral frontal horn. RESULTS: Magnetic resonance imaging data sets from 10 patients were used. For the entry point 6 cm above and 4 cm lateral to the inion (Frazier's point), ideal cannulation was achieved for all 10 patients when the selected target was 4 cm above the contralateral medial canthus. When the contralateral medial canthus was targeted, 5 patients had successful outcomes. There were only 3 satisfactory outcomes each when the ipsilateral medial canthus and glabella were targeted. The target 2 cm above the glabella yielded 2 satisfactory outcomes. The entry point 3 cm above and 2 cm lateral to the inion (Dandy's point) had 10 satisfactory outcomes when the target point was 2 cm above the glabella. All the other target points, namely, ipsilateral medial canthus, contralateral medial canthus, 4 cm above the contralateral medial canthus and glabella yielded poor results. CONCLUSIONS: For satisfactory placement when entering via Frazier's point, the best trajectory target would be 4 cm above the contralateral medial canthus. When entering via Dandy's point, the best target would be 2 cm above the glabella.

The role of surgery in high-grade glioma--is surgical resection justified? A review of the current knowledge.

INTRODUCTION: The aims of this article were to review the role of surgical resection in the management of high-grade gliomas and to determine whether there is any survival benefit from surgical resection. METHODS: A literature review of the influence of surgical resection on outcome was carried out. Relevant original and review papers were obtained through a PubMed search using the following keywords: glioma, resection, prognosis and outcome. RESULTS: Presently, there is a lack of evidence to support a survival benefit with aggressive glioma resection, but this should not detract patients from undergoing surgery as there are many other clinical benefits of glioma excision. In addition, limiting surgical morbidity through the use of adjuvant techniques such as intraoperative magnetic resonance imaging (MRI), functional MRI and awake craniotomy is becoming increasingly important. CONCLUSIONS: Ideally, a randomised controlled trial would be the best way to resolve the issue of whether (and to what extent) surgical resection leads to improvements in patient outcome and survival, but this would not be ethical. The second best option would be well-controlled retrospective studies with a multivariate analysis of all potential confounding factors.

Tension pneumoventricle.

We report a case of tension pneumoventricle in a patient who underwent excision of a midbrain tectal plate tumour via a supracerebellar infratentorial approach while in the sitting position. Tension pneumoventricle was diagnosed when the patient's clinical condition deteriorated rapidly early in the postoperative period. An urgent computed tomography scan of the head revealed the presence of air in the frontal and temporal horns of the lateral ventricles and blood in the third and fourth ventricles. An emergency external ventricular drain insertion was performed, resulting in prompt recovery. We believe the contributing factors resulting in such rapid development of tension pneumoventricle were the patient's sitting position, pre-existing hydrocephalus, breach of the third ventricle during surgery and the presence of blood in the third and fourth ventricles.