Medical Image Processing for Fully Integrated Subject Specific Whole Brain Mesh Generation

To the Editor: Wilkinson et al1 describe the very interesting phenomenon of abnormal leptomeningeal enhancement in the territory of the middle cerebral artery after ipsilateral carotid stent insertion. In our view, Figures 1E⇓ and 1F⇓ of the above-mentioned article not only show leptomeningeal contrast enhancement but also indicate extravasation of contrast medium into the cerebrospinal fluid (CSF) space. The authors do not believe that a reaction of leptomeningeal vessels to the x-ray contrast medium (Optiray, Mallinckrodt Medical Ltd; dosage not mentioned) was a likely cause. The phenomenon of contrast medium extravasation into the CSF space following disrupture the blood-CSF barrier, however, has been observed by using CT2 and MRI.3 During the last 10 years we have found extravasation of contrast medium into the CSF space in 11 patients, who suffered from cardiovascular and cerebrovascular arteriosclerosis often associated with severe hypoxemic brain damage (Figures 1⇓ and 2). We believe that a latent, regional alteration of the blood-brain barrier in patients with severe stenosis of the internal carotid artery might become obvious in terms of enhancement of the leptomeninges and the adjacent subarachnoid space under certain conditions: (1) repeated intra-arterial application of x-ray contrast media; (2) short periods of hypoxemia during angioplasty; and (3) in accordance with Wilkinson et al,1 an obviously temporary reperfusion phenomenon exists, the mechanism of which is not completely understood. Enhancement of the ventricular system (Figure 2⇓) is a result of hypoxemic damage of the “tight junctions” between …

In veterinary medicine, patients undergo magnetic resonance imaging (MRI) under general anesthesia to enable acquisition of artifact-free images. The fraction of inspired oxygen (FiO2) ranges between 30 and 95%. In humans, a high FiO2 is associated with incomplete signal suppression of peripheral cerebrospinal fluid (CSF) spaces on T2-weighted fluid-attenuated inversion recovery (T2w-FLAIR) sequences. The influence of FiO2 on T2w-FLAIR images remains unreported in small animals. The aim of this prospective study was to investigate whether a high FiO2 is associated with hyperintensity in peripheral CSF spaces on T2w-FLAIR images in dogs and cats. Client-owned patients undergoing brain MRI were prospectively enrolled. Animals with brain parenchymal abnormalities and/or meningeal contrast enhancement on MRI images and/or abnormal CSF analysis were excluded. Consequently, twelve patients were enrolled. Anesthesia was maintained by isoflurane 0.5–1 minimal alveolar concentration in 30% oxygen. After acquisition of transverse and dorsal T2w-FLAIR images, the FiO2 was increased to 95%. The T2w-FLAIR sequences were then repeated after 40 min. Arterial blood gas analysis was performed in six patients at the same time as T2w-FLAIR sequence acquisition. Plot profiles of the signal intensity (SI) from CSF spaces of three cerebral sulci and adjacent gray and white matter were generated. SI ratios of CSF space and white matter were compared between the T2w-FLAIR images with 30 and 95% FiO2. An observer blinded to the FiO2, subjectively evaluated the SI of peripheral CSF spaces on T2w-FLAIR images as high or low. There was significant difference in the partial pressure of oxygen between the two arterial samples (P < 0.001). The SI ratios obtained from the T2w-FLAIR images with 95% FiO2 were significantly higher compared with those obtained from the T2w-FLAIR images with 30% FiO2 (P < 0.05). The peripheral CSF spaces were subjectively considered hyperintense in 11 of 12 cases on T2w-FLAIR images with 95% FiO2 (P < 0.005). A clear difference in SI, dependent on the FiO2 was seen in the peripheral CSF spaces on T2w-FLAIR images. In conclusion, the influence of FiO2 must be considered when differentiating pathological and normal CSF spaces on T2w-FLAIR images in dogs and cats.

The cerebrospinal fluid (CSF) space is convoluted. CSF flow oscillates with a net flow from the ventricles towards the cerebral and spinal subarachnoid space. This flow is influenced by heartbeats, breath, head or body movements as well as the activity of the ciliated epithelium of the plexus and ventricular ependyma. The shape of the CSF space and the CSF flow preclude rapid equilibration of cells, proteins and smaller compounds between the different parts of the compartment. In this review including reinterpretation of previously published data we illustrate, how anatomical and (patho)physiological conditions can influence routine CSF analysis. Equilibration of the components of the CSF depends on the size of the molecule or particle, e.g., lactate is distributed in the CSF more homogeneously than proteins or cells. The concentrations of blood-derived compounds usually increase from the ventricles to the lumbar CSF space, whereas the concentrations of brain-derived compounds usually decrease. Under special conditions, in particular when distribution is impaired, the rostro-caudal gradient of blood-derived compounds can be reversed. In the last century, several researchers attempted to define typical CSF findings for the diagnosis of several inflammatory diseases based on routine parameters. Because of the high spatial and temporal variations, findings considered typical of certain CNS diseases often are absent in parts of or even in the entire CSF compartment. In CNS infections, identification of the pathogen by culture, antigen detection or molecular methods is essential for diagnosis.

A non-ionic water soluble contrast medium, 3-Deoxy-3-Iodo-D-Glucose (DIG), was experimentally evaluated for use in the cerebrospinal fluid (CSF) space, and compared with other contrast media. Two ml (180 mgI/ml) of DIG were injected either intraventricularly or intracisternally in 15 adult mongrel dogs (average weight: 6.4 kg), and X-ray photographic, CSF, EEG, and histological studies were then performed. Additional tests were made on four beagle dogs (average weight: 9.8 kg), focussing particularly on changes in cell count and protein in the CSF following alternate intracisternal injections of 2 ml (170 mgI/ml) of DIG and metrizamide (Amipaque), and on epileptogenicity following intracisternal injection of 3 ml (300 mgI/ml) of DIG. That DIG provides adequate definition was demonstrated both by the ventriculograms and cisternograms, and by comparison with metrizamide. Neither epileptic discharges in the EEG nor epileptic symptoms were seen in any of the dogs used in the studies. In the CSF drawn 24 hours after the injection, protein tended to increase moderately with DIG, but pleocytosis was mild with both media. Histological studies of the central nervous system structures around the cisterna magna revealed no definite abnormal findings. Neither fibrosis nor arachnoid adhesions were seen in scanning electron microscopic observations of the basal subarachnoid spaces.

Bacterial meningitis is still an important infectious disease with a high morbidity and mortality rate. Bacterial infection of the cerebrospinal fluid (CSF) space causes a powerful inflammatory reaction that is largely responsibly for meningitis-induced tissue damage and adverse outcome of the disease. In a landmark series of experiments in the mid-1980s, cell wall components including lipooligosaccharides and lipoteichoic acid were indicated to be the key bacterial elements that can trigger the host inflammatory response in the CSF. Ten years ago, the discovery of Toll-like receptor proteins (TLRs) that allow the detection of microbial components and initiate the host immune response opened up new horizons in research on the pathophysiology of meningitis. Cell culture approaches provided the first evidence for a crucial role of TLRs in sensing meningeal pathogens including Streptococcus pneumoniae, Neisseria meningitidis, Streptococcus agalactiae, and Listeria monocytogenes. Subsequently, studies in mice with single or combined deficiencies in TLRs demonstrated that TLR activation is a key event in meningeal inflammation and, even more interestingly, a pivotal factor for meningitis-associated tissue damage. A detailed understanding of the mechanisms of host-pathogen interactions in the CSF space may generate new opportunities for specific treatment strategies for bacterial meningitis.

Cerebral CT findings in male opioid-dependent patients: Stereological, planimetric and linear measurements

Imaging in cutis laxa syndrome caused by a dominant negative ALDH18A1 mutation, with hypotheses for intracranial vascular tortuosity andwide perivascular spaces.

Changes in body position cause pressure changes in the fluid spaces of the body. The postural pressure changes in the cerebrospinal fluid (CSF) space have been the subject of numerous clinical investigations from the beginning of this century. An important early finding was that in any position of the body, the level of CSF in manometers connected to lumbar, cisternal, and ventricular needles was the same (for references, see Masserman25). This means that when there is no block in the course of the CSF pathways, the craniospinal system acts as a continuous fluid medium (Fig. 1). This is also the case in patients with medium-pressure CSF shunts,23 so apparently the drainage of CSF in such patients does not cause collapse and block of any part of the CSF space. Thus, in the craniospinal system, the pressure is equal at all points in a horizontal plane, and the difference in pressure between two different horizontal planes equals the weight of the corresponding vertical column of CSF. If the pressure is measured at one level in the system, the pressure at all other horizontal planes can be calculated. In other words, Pascal’s laws are valid for the craniospinal system.

Background The distinction between normal and pathological extra-axial cerebrospinal fluid (CSF) spaces is unclear, with the use of the term benign external hydrocephalus (BEH) not being well defined in clinical practice. This study aimed to establish a distribution of metrics of the subarachnoid space in a population of children diagnosed as normal, and investigate the clinical use of the term BEH. Methods A retrospective case-control study on magnetic resonance image scans was performed on 150 children diagnosed as normal and 10 children diagnosed with BEH. Measurements were taken in the axial plane for CSF width (CSFW), and interhemispheric width (IHW). Results Normal controls had a mean age of 11.1 ± 7.6 months (78 male, 72 female) and the BEH sample had a mean age of 10.6 ± 7.8 months (six male, four female). Mean CSFW was 7.96 ± 4.79 mm in the BEH sample compared to 4.58 ± 2.25 mm in the normal sample ( p < 0.05). Mean IHW was 6.30 ± 2.79 mm in the BEH sample compared to 3.89 ± 1.83 mm in the normal sample ( p < 0.05). However, a substantial overlap between the two distributions of CSFW was found, with 50% of BEH patients lying within a single standard deviation of the mean of normal individuals. Conclusion The absence of diagnostic criteria for BEH means reporting is variable. Patients being diagnosed with BEH who have no other clinical defects may represent the extreme of the normal population rather than a distinct clinical entity.

Purpose To study the glaucomatous optic nerve head in Chinese eyes. Methods The histomorphometric investigation included a Normal group (non‐highly myopic eyes) of 40 human globes enucleated due to a malignant choroidal melanoma, a Glaucomatous group (non‐highly myopic eyes) of 55 eyes enucleated due to painful secondary angle‐closure glaucoma, and a Highly Myopic Glaucomatous group of 26 glaucomatous globes with an axial length &gt;26.5 mm. Anterior‐posterior histological sections through the pupil and the optic disc were morphometrically evaluated and compared. Results The lamina cribrosa was significantly (P&lt;0.001) thicker in the Normal group than in the Glaucomatous group, in which it was significantly (P&lt;0.001) thicker than in the Highly Myopic Glaucomatous group. The lamina cribrosa thickness decreased significantly (P&lt;0.001) with increasing axial length and presence of glaucoma (p&lt;0.001). The peripapillary scleral thickness close to the optic nerve scleral canal and just outside of the optic nerve meninges decreased significantly with increasing axial length (P=0.04 and P=0.02, respectively). The peripapillary scleral thickness did not vary significantly between the Glaucomatous group and the Normal Group. The distance between the intraocular space and cerebrospinal fluid space was (p&lt;0.001) shorter in the two glaucomatous groups than in the Normal group. Conclusion Lamina cribrosa thickness and peripapillary sclera thickness decreased significantly with axial length, in addition to a glaucoma‐related thinning of the lamina cribrosa. Within non‐highly myopic eyes, the peripapillary sclera thickness did not vary significantly between glaucomatous eyes and normal eyes.

The human lungs are divided into five distinct anatomic compartments called lobes. The physical boundaries between the lobes are called the lobar fissures. Detection of lobar fissure positions in pulmonary X-ray CT images is of increasing interest for the diagnosis of lung disease. We have developed an automatic method for segmentation of all five lung lobes simultaneously using a 3D watershed transform on the distance transform of a previously generated vessel mask, linearly combined with the original data. Due to the anatomically separate airway sub-trees for individual lobes, we can accurately and automatically place seed points for the watershed segmentation based on the airway tree anatomical description, due to the fact that lower generation airway and vascular tree segments are located near each other. This, along with seed point placement using information on the spatial location of the lobes, can give a close approximation to the actual lobar fissures. The accuracy of the lobar borders is assessed by comparing the automatic segmentation to manually traced lobar boundaries. Averaged over all volumes, the RMS distance errors for the left oblique fissure, right oblique fissure and right horizontal fissure are 3.720 mm, 0.713 mm and 1.109 mm respectively.

Registering CT images of the chest is a crucial step for several tasks such as disease progression tracking or surgical planning. It is also a challenging step because of the heterogeneous content of the human abdomen which implies complex deformations. In this work, we focus on accurately registering a subset of organs of interest. We register organ surface point clouds, as may typically be extracted from an automatic segmentation pipeline, by expanding the Bayesian Coherent Point Drift algorithm (BCPD). We introduce MO-BCPD, a multi-organ version of the BCPD algorithm which explicitly models three important aspects of this task: organ individual elastic properties, inter-organ motion coherence and segmentation inaccuracy. This model also provides an interpolation framework to estimate the deformation of the entire volume. We demonstrate the efficiency of our method by registering different patients from the LITS challenge dataset. The target registration error on anatomical landmarks is almost twice as small for MO-BCPD compared to standard BCPD while imposing the same constraints on individual organs deformation.

Nonglial Tumors of the Brainstem

This study conducted a functional assessment of the results of magnetic resonance imaging in comparison with electroencephalography of 348 young pilots of the Higher Military Pilot School named after the Hero of the Soviet Union A.K. Serov who were deemed “healthy” during the medical flight commission. Magnetic resonance imaging revealed expansion of the cerebrospinal fluid spaces of varying degrees and localization in 41(11.8%) pilots after the medical flight commission, which is a contraindication for flight service. However, many congenital structural features of the brain detected by magnetic resonance imaging are normal anatomical variants. When deciphering all electroencephalograms, deviations from the norm were noted in 41(11.5%) cases, including α- and β-rhythms. In 1 (0.3%) patient, changes were also detected by magnetic resonance imaging and electroencephalography. Deviations in electroencephalograms were not associated with the changes detected by magnetic resonance imaging. Thus, the detected changes in the electroencephalograms of 1 (0.3%) pilot had not clear effects, and magnetic resonance imaging detected cerebrospinal fluid space expansion up to 10 mm in the retrocerebellar region. The study emphasized the need to clarify the techniques in medical flight commission in relation to flight personnel with such “findings” to objectively predict the real risk in relation to further service. Therefore, additional studies in young pilots with identified characteristics are necessary by comparing magnetic resonance imaging and electroencephalogram findings with respect to exercise testing, mental function, and learning potential.

We performed scalp-avoidance whole-brain irradiation with volumetric-modulated arc therapy (SAWB-VMAT) as a component of craniospinal irradiation. In SAWB-VMAT with two coplanar arcs, radiation oncologists and medical physicists sometimes experience difficulty in reducing the dose to the scalp to below the cut-off equivalent dose in 2Gy per fraction (assuming α/β=2) to 50% (EQD50%scalp ). To investigate the advantage of adding coplanar or non-coplanar arcs in reducing the dose to the scalp in SAWB-VMAT, we conducted a planning study to compare the EQD50%scalp , the dose to other organs at risk (OARs), and target coverage in VMAT with two coplanar arcs (Co2arcVMAT), VMAT with three coplanar arcs (Co3arcVMAT), and VMAT with two coplanar and two non-coplanar arcs (NcVMAT). Co2arcVMAT, Co3arcVMAT, and NcVMAT plans were created for 10 pediatric patients with medulloblastoma. The planned target volume (PTV) included the regions of the whole brain, cervical spinal cord, cerebrospinal fluid space, and intervertebral foramen. The EQD50%scalp was evaluated separately for four areas (top, back, left, and right) in each case. The prescribed dose for the PTV was 35.2Gy in 22 fractions. The median EQD50%scalp of the top area was 21.9, 22.1, and 18.3Gy for Co2arcVMAT, Co3arcVMAT, and NcVMAT, respectively. The EQD50%scalp of the top area was significantly reduced in NcVMAT compared to those in Co2arcVMAT and Co3arcVMAT (p<0.05). The median EQD50%scalp of the top area for NcVMAT was<19.9Gy, which is the cut-off dose for severe permanent alopecia. There were no significant differences in EQD50%scalp in the three other areas, the dose to other OARs, or the dose coverage of PTV among the three techniques. NcVMAT could reduce the EQD50%scalp of the top area below the cut-off dose of 19.9Gy. NcVMAT appears to be a promising treatment technique for SAWB-VMAT.