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Background: The reversible posterior leukoencephalopathy (RPL) syndrome with typical vasogenic edema in the occipital lobe and associated cortical blindness is a rare finding; however, the brainstem variant is even more infrequent. Etiologies discussed include blood pressure dysregulations, renal failure, or immunosuppression., Patient: A 63-year-old man with the characteristic radiographic findings of RPL syndrome presented with reversible cortical blindness and internuclear ophthalmoplegia (INO) after resection of an infratentorial hemangiopericytoma. The patient postoperatively presented with diplopia and mental status alterations followed by visual loss; these symptoms completely recovered within a few days. Fluid-attenuated inversion recovery-, and T2-weighted magnetic resonance imaging (MRI) revealed bilateral hyperintense lesions not only in the white matter of the parieto-occipital region but also in the rostral paramedian mesencephalon and pons., Conclusions: We hypothesize that the patient had an RPL, coincidentally in classic-, and brainstem localization, caused by perioperative fluctuations of blood pressure., (Georg Thieme Verlag KG Stuttgart · New York.)

Objective: Up to now, fiber tractography in the clinical routine is mostly based on diffusion tensor imaging (DTI). However, there are known drawbacks in the resolution of crossing or kissing fibers and in the vicinity of a tumor or edema. These restrictions can be overcome by tractography based on High Angular Resolution Diffusion Imaging (HARDI) which in turn requires larger numbers of gradients resulting in longer acquisition times. Using compressed sensing (CS) techniques, HARDI signals can be obtained by using less non-collinear diffusion gradients, thus enabling the use of HARDI-based fiber tractography in the clinical routine., Methods: Eight patients with gliomas in the temporal lobe, in proximity to the optic radiation (OR), underwent 3T MRI including a diffusion-weighted dataset with 30 gradient directions. Fiber tractography of the OR using a deterministic streamline algorithm based on DTI was compared to tractography based on reconstructed diffusion signals using HARDI+CS., Results: HARDI+CS based tractography displayed the OR more conclusively compared to the DTI-based results in all eight cases. In particular, the potential of HARDI+CS-based tractography was observed for cases of high grade gliomas with significant peritumoral edema, larger tumor size or closer proximity of tumor and reconstructed fiber tract., Conclusions: Overcoming the problem of long acquisition times, HARDI+CS seems to be a promising basis for fiber tractography of the OR in regions of disturbed diffusion, areas of high interest in glioma surgery.

Diffusion Tensor Imaging (DTI) and fiber tractography are established methods to reconstruct major white matter tracts in the human brain in-vivo. Particularly in the context of neurosurgical procedures, reliable information about the course of fiber bundles is important to minimize postoperative deficits while maximizing the tumor resection volume. Since routinely used deterministic streamline tractography approaches often underestimate the spatial extent of white matter tracts, a novel approach to improve fiber segmentation is presented here, considering clinical time constraints. Therefore, fiber tracking visualization is enhanced with statistical information from multiple tracking applications to determine uncertainty in reconstruction based on clinical DTI data. After initial deterministic fiber tracking and centerline calculation, new seed regions are generated along the result's midline. Tracking is applied to all new seed regions afterwards, varying in number and applied offset. The number of fibers passing each voxel is computed to model different levels of fiber bundle membership. Experimental results using an artificial data set of an anatomical software phantom are presented, using the Dice Similarity Coefficient (DSC) as a measure of segmentation quality. Different parameter combinations were classified to be superior to others providing significantly improved results with DSCs of 81.02%±4.12%, 81.32%±4.22% and 80.99%±3.81% for different levels of added noise in comparison to the deterministic fiber tracking procedure using the two-ROI approach with average DSCs of 65.08%±5.31%, 64.73%±6.02% and 65.91%±6.42%. Whole brain tractography based on the seed volume generated by the calculated seeds delivers average DSCs of 67.12%±0.86%, 75.10%±0.28% and 72.91%±0.15%, original whole brain tractography delivers DSCs of 67.16%, 75.03% and 75.54%, using initial ROIs as combined include regions, which is clearly improved by the repeated fiber tractography method.

As highly invasive and infiltrative tumors, gliomas are hard to delineate from healthy brain parenchyma, even with the microscope enhanced eye of an experienced neurosurgeon. However, the surgical goal remains maximum extent of tumor volume resection with a preservation of neurological function. With functional data integrated and visualized in the navigation system, postoperative morbidity can be reduced. With the so far well established techniques diffusion-tensor-imaging (DTI) based fiber tractography and functional MRI (fMRI), white matter tracts or eloquent cortical areas can be displayed. With magnetic resonance spectroscopy (MRS) and also positron emmission computed tomography (PET), methods displaying brain metabolism are also widely used. However, further technical and computational development of these methods has already shown extended insights in brain networks and pathologies and promises further reduction of postoperative morbidity, while used in navigation systems. In addition to these methods, novel techniques have already been implemented and successfully used in the clinical routine. In this way, this review summarizes recent developments in DTI, fMRI, MRSI and PET, also with their use during neurosurgical operations, but also gives introduction in novel methods like navigated transcranial magnetic stimulation (nTMS) or advanced diffusion models as base for fiber tracking.

Background: The most frequently used method for fiber tractography based on diffusion tensor imaging (DTI) is associated with restrictions in the resolution of crossing or kissing fibers and in the vicinity of tumor or edema. Tractography based on high-angular-resolution diffusion imaging (HARDI) is capable of overcoming this restriction. With compressed sensing (CS) techniques, HARDI acquisitions with a smaller number of directional measurements can be used, thus enabling the use of HARDI-based fiber tractography in clinical practice., Objective: To investigate whether HARDI+CS-based fiber tractography improves the display of neuroanatomically complex pathways and in areas of disturbed diffusion properties., Methods: Six patients with gliomas in the vicinity of language-related areas underwent 3-T magnetic resonance imaging including a diffusion-weighted data set with 30 gradient directions. Additionally, functional magnetic resonance imaging for cortical language sites was obtained. Fiber tractography was performed with deterministic streamline algorithms based on DTI using 3 different software platforms. Additionally, tractography based on reconstructed diffusion signals using HARDI+CS was performed., Results: HARDI+CS-based tractography displayed more compact fiber bundles compared with the DTI-based results in all cases. In 3 cases, neuroanatomically plausible fiber bundles were displayed in the vicinity of tumor and peritumoral edema, which could not be traced on the basis of DTI. The curvature around the sylvian fissure was displayed properly in 6 cases and in only 2 cases with DTI-based tractography., Conclusion: HARDI+CS seems to be a promising approach for fiber tractography in clinical practice for neuroanatomically complex fiber pathways and in areas of disturbed diffusion, overcoming the problem of long acquisition times.

Background: During external ventricular drainage (EVD) weaning, cranial computed tomography (cCT) is necessary to evaluate ventricle width. Because intrahospital transfer of critically ill patients is associated with higher mortality, bedside techniques are necessary to evaluate ventricle width. Transcranial sonography is able to show the ventricles in patients with sufficient temporal acoustic window. Contrast-enhanced ultrasound (CEUS) is able to overcome the limitations of insufficient insonation., Objective: We demonstrate the feasibility of bedside transcranial CEUS ventriculography to measure ventricles and verify the passage of cerebrospinal fluid (CSF) through the foramen of Magendie into the subarachnoid space during EVD weaning in critically ill patients., Methods: Six patients were examined by transcranial and transnuchal CEUS. Harmonic imaging with low mechanical index was used. One milliliter of an ultrasound contrast agent was administered via EVD line. Comparison with the cCT scans at the time of discharge was used to confirm CEUS-ventriculography results., Results: Ventricles were visualized in all patients. CSF transmission via the foramen of Magendie was demonstrated in 5 patients. Mean ventricle width (centimeters) was 0.67 (CEUS) vs 0.73 (cCT) (standard deviation 0.43, 0.45, P = .116) [third ventricle], 0.88 vs 1.02 (0.28, 0.22, P = .055) [fourth ventricle], 1.40 vs 1.37 (0.56, 0.54, P = .620) [left lateral ventricle], 1.37 vs 1.37 (0.55, 0.54, P = .952) [right lateral ventricle], 2.33 vs 2.23 (0.51, 0.58, P = .169) [left anterior horn], and 2.25 vs 2.07 (0.56, 0.64, P = .204) [right anterior horn]. Mean duration for CEUS ventriculography was 3:15 minutes., Conclusion: CEUS ventriculography is an effective bedside procedure in critically ill patients with EVD. CEUS allows measurement of ventricle width, ventricle communication, and CSF transfer to the subarachnoidal space through the cisternal foramina.

Background: For neuroepithelial tumors, the surgical goal is maximum resection with preservation of neurological function. This is contributed to by intraoperative magnetic resonance imaging (iMRI) combined with multimodal navigation., Objective: We evaluated the contribution of diffusion tensor imaging (DTI)-based fiber tracking of language pathways with 2 different algorithms (tensor deflection, connectivity analysis [CA]) integrated in the navigation on the surgical outcome., Methods: We evaluated 32 patients with neuroepithelial tumors who underwent surgery with DTI-based fiber tracking of language pathways integrated in neuronavigation. The tensor deflection algorithm was routinely used and its results intraoperatively displayed in all cases. The CA algorithm was furthermore evaluated in 23 cases. Volumetric assessment was performed in pre- and intraoperative MR images. To evaluate the benefit of fiber tractography, language deficits were evaluated pre- and postoperatively and compared with the volumetric analysis., Results: Final gross-total resection was performed in 40.6% of patients. Absolute tumor volume was reduced from 55.33 ± 63.77 cm(3) to 20.61 ± 21.67 cm(3) in first iMRI resection control, to finally 11.56 ± 21.92 cm(3) (P < .01). Fiber tracking of the 2 algorithms showed a deviation of the displayed 3D objects by <5 mm. In long-term follow-up only 1 patient (3.1%) had a persistent language deficit., Conclusion: Intraoperative visualization of language-related cortical areas and the connecting pathways with DTI-based fiber tracking can be successfully performed and integrated in the navigation system. In a setting of intraoperative high-field MRI this contributes to maximum tumor resection with low postoperative morbidity.

Navigation systems are commonly used in neurosurgical operating theaters. Generally, they either rely on the use of preoperative or intraoperative image data. Using preoperative image data, the phenomenon of brain shift contributes most to errors, in addition to various other sources of decreased reliability, such as image-related errors or registration inaccuracy. Updating navigation after intraoperative magnetic resonance imaging (iMRI) serves as immediate feedback on the surgical result and furthermore compensates for the effects of brain shift. Together with an integration of functional data in the navigation such as diffusion tensor imaging (DTI)-based fiber tracking or functional MRI, there is evidence that iMRI contributes to maximize extent of resection in glioma surgery with a preservation of neurological function. The following article summarizes the work flow and clinical impact of iMRI and functional navigation, as well as current problems and possible solutions.

Background: The beneficial role of the extent of resection (EOR) in glioma surgery in correlation to increased survival remains controversial. However, common literature favors maximum EOR with preservation of neurological function, which is shown to be associated with a significantly improved outcome., Objective: In order to obtain a maximum EOR, it was examined whether high-field intraoperative magnetic resonance imaging (iMRI) combined with multimodal navigation contributes to a significantly improved EOR in glioma surgery., Methods: Two hundred ninety-three glioma patients underwent craniotomy and tumor resection with the aid of intraoperative 1.5 T MRI and integrated multimodal navigation. In cases of remnant tumor, an update of navigation was performed with intraoperative images. Tumor volume was quantified pre- and intraoperatively by segmentation of T2 abnormality in low-grade and contrast enhancement in high-grade gliomas., Results: In 25.9% of all cases examined, additional tumor mass was removed as a result of iMRI. This led to complete tumor resection in 20 cases, increasing the rate of gross-total removal from 31.7% to 38.6%. In 56 patients, additional but incomplete resection was performed because of the close location to eloquent brain areas. Volumetric analysis showed a significantly (P < .01) reduced mean percentage of tumor volume following additional further resection after iMRI from 33.5% ± 25.1% to 14.7% ± 23.3% (World Health Organization [WHO] grade I, 32.8% ± 21.9% to 6.1% ± 18.8%; WHO grade II, 24.4% ± 25.1% to 10.8% ± 11.0%; WHO grade III, 35.1% ± 27.3% to 24.8% ± 26.3%; WHO grade IV, 34.2% ± 23.7% to 1.2% ± 16.2%)., Conclusion: MRI in conjunction with multimodal navigation and an intraoperative updating procedure enlarges tumor-volume reduction in glioma surgery significantly without higher postoperative morbidity.

In the present study, we investigated the sonothrombolytic effect of new nanoscaled lipid formulations in human blood clots, using diagnostic ultrasound. Human blood clots of 1 ml were incubated with 1 μl of the different lipid dispersions DPPC/CH, DPPC/PEG40S, DSPC/PEG40S and the commercially available ultrasound contrast agent SonoVue®. Clots were stored for 3 days at 5 °C to obtain maximal clot retraction and lytic resistance. Each clot weight was determined before and after continuous insonation for 1h of insonation at 1.4 MHz. The pressure in the insonation chamber was 80 mm Hg to mimic middle arterial blood pressure. There were no significant differences in thrombus weight before insonation. All nanoscaled formulations and SonoVue® were able to reduce thrombus weight compared to the weight loss of clots that were not insonated but kept under pressure for one hour (p < 0.001). We found a highly significant weight reduction with DSPC/PEG40S compared to SonoVue® (p = 0.007). Nanoscaled DSPC/PEG40S dispersion could be a promising formulation in ultrasound enhanced thrombolysis even without thrombolytic drugs. Stable cavitation is a crucial parameter in fragmentation of thrombus architecture. Further studies of physicochemical properties of DSPC/PEG40S are necessary to corroborate our hypothesis., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Purpose: Diffusion tensor imaging (DTI) is a non-invasive imaging technique that allows estimating the location of white matter tracts based on the measurement of water diffusion properties. Using DTI data, the fiber bundle boundary can be determined to gain information about eloquent structures, which is of major interest for neurosurgical interventions. In this paper, a novel approach for boundary estimation is presented., Methods: DTI in combination with diverse segmentation algorithms allows estimating the position and course of fiber tracts in the human brain. For additional information about the expansion of the fiber bundle, the introduced iterative approach uses the centerline of a tracked fiber bundle between two regions of interest (ROI). After sampling along this centerline, rays are sent out radially, discrete 2D contours are calculated, and the fiber bundle boundary is estimated in a stepwise manner. For this purpose, each ray is analyzed using several criteria, including anisotropy parameters and angle parameters, to find the boundary point., Results: The novel method for automatically calculating the boundaries has been applied to several artificially generated DTI datasets. Multiple parameters were varied: number of rays per plane, sampling rate and sampled points along the rays. For the DTI data used in the experiments, the method yielded a dice similarity coefficient (DSC) between 74.7 and 91.5%., Conclusions: In this paper, a novel approach to retrieve significant information about the fiber bundle boundary from DTI data is presented. The method is a contribution to gather important knowledge about high-risk structures in neurosurgical interventions.

Intraoperative high-field MRI in combination and close integration with microscope-based navigation serving as a common interface for the presentation of multimodal data in the surgical field seems to be one of the most promising surgical setups allowing avoiding unwanted tumor remnants while preserving neurological function. Multimodal navigation integrates standard anatomical, structural, functional, and metabolic data. Navigation achieves visualizing the initial extent of a lesion with the concomitant identification of neighboring eloquent brain structures, as well as, providing a tool for a direct correlation of histology and multimodal data. With the help of intraoperative imaging navigation data can be updated, so that brain shift can be compensated for and initially missed tumor remnants can be localized reliably.

Background: Vital sign monitors and ventilator/anesthesia workstations are equipped with multiple alarms to improve patient safety. A high number of false alarms can lead to a "crying wolf" phenomenon with consecutively ignored critical situations. Systematic data on alarm patterns and density in the perioperative phase are missing. Our objective of this study was to characterize the patterns of alarming of a commercially available patient monitor and a ventilator/anesthesia workstation during elective cardiac surgery., Methods: We performed a prospective, observational study in 25 consecutive elective cardiac surgery patients. In all patients, identically fixed alarm settings were used. All incoming patient data and all alarms from the patient monitor and the anesthetic workstation were digitally recorded. Additionally, the anesthesia workplace was videotaped from 2 different angles to allow retrospective annotation and correlation of alarms with the clinical situation and assessment of the anesthesiologists' reaction to the alarms., Results: Of the 8975 alarms, 7556 were hemodynamic alarms and 1419 were ventilatory alarms. For each procedure, 359 ± 158 alarms were recorded, representing a mean density of alarms of 1.2/minute., Conclusion: Approximately 80% of the total 8975 alarms had no therapeutic consequences. Implementation of procedure-specific settings and optimization in artifact and technical alarm detection could improve patient surveillance and safety.

Cerebrospinal fluid (CSF) is routinely used for diagnosing and monitoring neurological diseases. The CSF proteins used so far for diagnostic purposes (except for those associated with whole cells) are soluble. Here, we show that human CSF contains specific membrane particles that carry prominin-1/CD133, a neural stem cell marker implicated in brain tumors, notably glioblastoma. Differential and equilibrium centrifugation and detergent solubility analyses showed that these membrane particles were similar in physical properties and microdomain organization to small membrane vesicles previously shown to be released from neural stem cells in the mouse embryo. The levels of membrane particle-associated prominin-1/CD133 declined during childhood and remained constant thereafter, with a remarkably narrow range in healthy adults. Glioblastoma patients showed elevated levels of membrane particle-associated prominin-1/CD133, which decreased dramatically in the final stage of the disease. Hence, analysis of CSF for membrane particles carrying the somatic stem cell marker prominin-1/CD133 offers a novel approach for studying human central nervous system disease.

During cast surgery the model-positioning appliance allows a controlled three-dimensional positioning of the maxillary incisors and of the entire maxilla in one- or two-jaw surgery. The model-positioning appliance is fastened, in place of the incisal pin or the incisal table, to the anterior end of the upper part of a semiadjustable articulator. Three reference points are marked with a pencil directly on three maxillary teeth. The reference plane during cast surgery is the hinge axis-infraorbital plane, which is represented by a parallel to the upper part of the articulator. All measurements during cast surgery are parallel or at a right angle to this reference plane. Three-dimensional adjustment of the maxillary cast is possible without measurements with a ruler and without the marking of reference points and drawing osteotomy lines on the base of the cast. Sawing cuts on the base of the cast corresponding to marked osteotomy lines is avoided. In this way errors are reduced and precision is increased. The advantage of model-positioning appliance is that the three reference points on the maxillary teeth can be adjusted simultaneously and that the relation of the whole maxillary dental arch to the mandibular dental arch can be controlled at the same time.

N-[4-[2-(2-Amino-3,4-dihydro-4-oxo-7H-pyrrolo[2,3-d]pyrimidin-5- yl)ethyl]benzoyl]-L-glutamic acid (15), prepared in five steps from 2-pivaloyl-7-deazaguanine, has been found to be an antitumor agent with its primary site of action at thymidylate synthase rather than purine synthesis. This compound appears to be a promising candidate for clinical evaluation.