Infratentorial Structures Research Articles

Structural volumetric and Periodic Table DTI patterns in Complex Normal Pressure Hydrocephalus-Toward the principles of a translational taxonomy.

We previously proposed a novel taxonomic framework to describe the diffusion tensor imaging (DTI) profiles of white matter tracts by their diffusivity and neural properties. We have shown the relevance of this strategy toward interpreting brain tissue signatures in Classic Normal Pressure Hydrocephalus vs. comparator cohorts of mild traumatic brain injury and Alzheimer's disease. In this iteration of the Periodic Table of DTI Elements, we examined patterns of tissue distortion in Complex NPH (CoNPH) and validated the methodology against an open-access dataset of healthy subjects, to expand its accessibility to a larger community. DTI measures for 12 patients with CoNPH with multiple comorbidities and 45 cognitively normal controls from the ADNI database were derived using the image processing pipeline on the brainlife.io open cloud computing platform. Using the Periodic Table algorithm, DTI profiles for CoNPH vs. controls were mapped according to injury patterns. Structural volumes in most structures tested were significantly lower and the lateral ventricles higher in CoNPH vs. controls. In CoNPH, significantly lower fractional anisotropy (FA) and higher mean, axial, and radial diffusivities (MD, L1, and L2 and 3, respectively) were observed in white matter related to the lateral ventricles. Most diffusivity measures across supratentorial and infratentorial structures were significantly higher in CoNPH, with the largest differences in the cerebellum cortex. In subcortical deep gray matter structures, CoNPH and controls differed most significantly in the hippocampus, with the CoNPH group having a significantly lower FA and higher MD, L1, and L2 and 3. Cerebral and cerebellar white matter demonstrated more potential reversibility of injury compared to cerebral and cerebellar cortices. The findings of widespread and significant reductions in subcortical deep gray matter structures, in comparison to healthy controls, support the hypothesis that Complex NPH cohorts retain imaging features associated with Classic NPH. The use of the algorithm of the Periodic Table allowed for greater consistency in the interpretation of DTI results by focusing on patterns of injury rather than an over-reliance on the interrogation of individual measures by statistical significance alone. Our aim is to provide a prototype that could be refined for an approach toward the concept of a "translational taxonomy."

Applications of hybrid structure light three‐dimensional scanning in neurodegenerative disease autopsy brain banking

AbstractBackgroundPostmortem magnetic resonance imaging (MRI) and three‐dimensional (3D) printing has been demonstrated to be a feasible approach for the creation of tissue matrices to aid in postmortem brain dissection. We aimed to extend this approach using hybrid structure light technology (visible and infrared) 3D scanning to generate brain models as a digital resource and operational tool for human neurodegenerative disease brain banks.MethodA consecutive series of 56 brains accessioned into the Glenn Biggs Institute Brain Bank were imaged using an EinScan H handheld 3D scanner. Five brains were selected for generation of tissue matrices, with infratentorial structures removed using 3D object post‐processing software tools. Matrices were printed using a Raise3D Pro2 printer and 1.75‐mm polylactic acid premium filament.ResultEach scan was approximately an hour to complete, including capture and alignment of a lateral and a medial surface scan for each brain. Raw scan files (DAT and BRAP‐PRJ) averaged 5.47 GB and 3D object files were 12,991 KB for 3MF and 18,067 KB for OBJ file types. For cases with tissue matrices, average print time was 42 hours with an average filament consumption of 338 g. Brain cutting with the tissue matrices was performed in a standardized manner, with superb control for section thickness and planar orientation compared to brains cut without a matrix.Conclusion3D scanning of postmortem autopsied brains is a simple and useful strategy to generate models with utility in guided tissue sectioning and storage (practice), surface area volumetric analysis (research) and virtual reality/augmented reality neuroanatomy training (education) for Alzheimer’s disease and related dementias.

Hydranencephaly: A Case Report

Hydranencephaly is a congenital neurodevelopmental anomaly in which there is an absence of the cerebral hemispheres and intact infratentorial structures. Diagnosis can be made prenatally or postnatally using ultrasound, CT, or MRI. Imaging findings include the presence of primitive brain structures, variable presence of the falx cerebri, and total or near-total absence of the cerebral hemispheres. We reported a case of newborn hydranencephaly in 1 day old neonate with macrocephaly.

Clinical Types of Movement Disorders in Patients with Multiple Sclerosis

Background Little is known about the true prevalence and clinical characteristics of movement disorders in early multiple sclerosis (MS), associated clinical disability and their effect on QOL. We conducted a cross sectional study to fill this knowledge gap. Objectives to study the prevalence of movement disorders in early stages of multiple sclerosis, presence of other clinical disability and their effect on QOL. Patients and method This is a cross sectional observational study. The patients group included 250 patients with RRMS whom were recruited consecutively from the MS clinic of Ain Shams and Nasr institute hospitals. Each eligible patient was interviewed and examined for presence of movement disorders, Patients were divided into 2 groups, group A without movement disorders and group B showing movement disorders. General and neurological examination including Expanded Disability Status Scale (EDSS) score at time of interview for both groups. Magnetic resonance imaging (MRI) of brain and cervical spinal cord (with contrast whenever available) obtained at the time of interview with documentation of MS plaques involvement for both groups. RRMS patients with movement disorders (group B) are subjected to different assessment for depression by Beck Depression Inventory (BDI), cognitive assessment by Montreal Cognitive Assessment (MOCA) scale, disability and quality of life (QOL) by the Short Form 36 Health Survey Questionnaire. Results This study included 250 RRMS. onset of their movement disorders was 2.69 ± 2.34 years from MS diagnosis with mean EDSS 3.515 ± 1.04. Cerebellar signs are present in 97% of total number of movement disorders and 26% of total sample, regarding tremors, 36 patients in this study showed tremors representing 53.7% of movement disorders patients, 14.4% of total sample of RRMS patients. This study showed presence of 5 cases of restless leg syndrome 7.5% of total number of MD. 4 cases of dystonia are present in this study representing 6% of MD patients. Patients with MD showed presence of depressive symptoms and cognitive affection with negative impact on QOL. Tremors severity is not correlated with either cognition or depression scores where ataxia is correlated with depression score only. MRI assessment of patients with MD showed higher lesion load and involvement of infratentorial structures especially cerebellum and its connections and cerebellum. Conclusion Movement disorders are common to occur than previously known especially ataxia and tremors early in the course of the disease. Presence of MD is related to high lesion load and strategic location of these lesions. special assessment of movement disorders as independent cause of disability with concomitant depression and cognitive impairment especially early in the disease course should be taken in consideration due to their negative impact on QOL.

Evaluation of the frequency of tentorial hypoplasia and accompanying gyral herniation using MRI.

Purpose The cerebellar tentorium, the second-largest dural reflection in the brain, separates supratentorial and infratentorial structures. This study aimed to determine the frequency of tentorial hypoplasia (TH) and gyral herniation and their relationship with clinical findings. Methods The standard brain MRIs were examined retrospectively. The presence of TH and laterality were investigated. If hypoplasia was accompanied by a gyrus extending inferior to the line where the tentorium should be located, this was recorded as tentorial hypoplasia-herniated gyrus (TH-HG), while the cases with hypoplasia alone were noted as isolated TH. It was also determined which gyrus or gyri were herniated. The clinical findings of the patients were obtained, and the correlation between HG was explored. Results Standard brain MRIs of the 2051 patients were evaluated. Two hundred ten patients were excluded from the study due to different intracranial disorders, and 1841 patients, 739 (40.1%) males, and 1102 (59.9%) females, were included. Isolated TH or TH-HG was present in 56 patients, resulting in a prevalence of 3.04%. Of the patients with TH or TH-HG, 15 were men, and 41 were women. TH and TH-HG were significantly more common in women (p=0.038). TH-HG was unilateral in 22 (39.2%) patients and bilateral in 21 (37.5%). Left TH was found in 11 (19.6%) patients, left TH-HG in 29 (51.7%), right TH in eight (14.2%), and left TH-HG in 35 (62.5%). Conclusion Hypoplasia of the tentorium is a rare and unknown anomaly that can be easily diagnosed using MRI, and different gyral herniations may accompany TH.

Analysis and hierarchical clustering of infratentorial morphological MRI identifies SCAs phenogroups.

Clinical decision-making in spinocerebellar ataxia spectrum diseases (SCAs) has mainly been based on genetic tests, not considering the SCAs' imaging and clinical heterogenicity. To identify SCAs phenogroups by analysis and hierarchical clustering of infratentorial morphological MRI for unveiling pathophysiological differences among common SCA subtypes. We prospectively enrolled 119 (62 women; mean age 37years) genetically diagnosed SCAs (SCA1 n = 21, SCA2 n = 10, symptomatic SCA3 n = 59, presymptomatic SCA3 n = 22, SCA6 n = 7) and 35 healthy controls (HCs). All patients underwent MRI and detailed neurological and neuropsychology examinations. The width of each cerebellar peduncle (CP) and anteroposterior diameter of the spinal cord and pontine were measured. Twenty-five SCAs patients (15 women; mean age 35years) were followed for at least a year (17 (15, 24) months), whose MRI and the Scale for the Assessment and Rating of Ataxia (SARA) were collected. Infratentorial morphological MRI measurements could significantly discriminate SCAs from HCs, even among SCA subtypes. Two mutually exclusive and clinically distinct phenogroups were identified. Despite similar (CAG)n, phenogroup 1 (n = 66, 55.5%) presented more atrophied infratentorial brain structures and more severe clinical symptoms with older age and earlier age of onset when compared with phenogroup 2. More importantly, all SCA2, most of SCA1 (76%), and symptomatic SCA3 (68%) were classified into phenogroup 1, whereas all SCA6 and all presymptomatic SCA3 were in phenogroup 2. The right middle CP had the highest diagnostic value in predicting phenogroup 2 (AUC = 0.99; P < 0.01) with high specificity (95%). Consistent with the significantly increased SARA (7.5 vs 10, P = 0.021), the bilateral inferior CP, spinal cord, and pontine tegmentum were more atrophy during the follow-up (P < 0.05). SCAs were with significant infratentorial brain atrophy than HCs. We identified two different SCAs phenogroups associated with substantial differences in infratentorial brain atrophy, clinical presentation, and may reflect the underlying molecular profiles to some extent, paving the way for a more personalized diagnostic and treatment approach.

A case study of left visual neglect after right pontine lesion: pathophysiological evidence for the infratentorial involvement in human visual attention.

Hemispatial neglect, the inability to attend to the contralesional side of space, is the most common disturbance of visuospatial attention. Both hemispatial neglect and visuospatial attention are typically associated with extended cortical networks. Nevertheless, recent accounts challenge this so-called corticocentric view and postulate the participation of structures well beyond the telencephalic cortex, in particular advocating the role of the brainstem. However, to the best of our knowledge, hemispatial neglect after a brainstem lesion has not yet been described. We describe, for the first time in a human, the occurrence and remission of contralesional visual hemispatial neglect after a focal lesion in the right pons. Hemispatial neglect was assessed by means of video-oculography during free visual exploration, a very sensitive and established method, and its remission was followed up until 3 wk after stroke. Moreover, by means of a lesion-deficit approach complemented by imaging, we identify a pathophysiological mechanism involving the disconnection of cortico-ponto-cerebellar and/or tecto-cerebellar-tectal pathways passing through the pons. Our findings offer, for the first time in a human, causal, lesion-based support for recent seminal accounts postulating the role of infratentorial structures participating in the activity of cerebral cortical attentional networks mediating attentional processes.NEW & NOTEWORTHY Visuospatial attention and its most common disturbance, hemispatial neglect, are typically associated with extended cortical networks. However, recent accounts challenge this corticocentric view and advocate the role of infratentorial structures. We describe, for the first time in a human, the occurrence of contralesional visual hemispatial neglect after a focal lesion in the right pons. We provide causal, lesion-based evidence for a pathophysiological mechanism involving the disconnection of cortico-ponto-cerebellar and/or tecto-cerebellar-tectal pathways passing through the pons.

453 Neuromodulation of the Centromedian Nucleus of the Thalamus for the Treatment of Generalized Drug-Resistant Epilepsy: Novel Insights Into the Targeting and the Anti-Seizure Mechanism From a Tractographic Study

INTRODUCTION: Neuromodulation of the centromedian nucleus (CM) has been investigated with promising results for the treatment of generalized drug-resistant epilepsy (gDRE). Recent evidence suggests a more clinically beneficial “sweet-spot” corresponding to the thalamic area between the antero-lateral CM and the posterior subdivision of the ventrolateral nucleus. However, it is unclear if this region can be considered a new target or still a subcomponent of CM. METHODS: We analyzed diffusion and structural MRI scans from 9 DRE patients, who underwent CM-stimulation surgery. CM masks from the THOMAS atlas and 2 spherical ROIs from the MNI coordinates of the sweet-spot and the cold-spot in Warren et al. 2022 were used as seed regions for probabilistic tractography (FSL software). 42 cortical and subcortical areas were selected as target regions and divided in 5 groups: sensorimotor, associative, basal ganglia, infratentorial and limbic structures. Mean structural connectivity was calculated using descriptive statistics and statistical significance was tested with a standard t-test. Statistical comparison among the 3 seed regions was conducted using ANOVA. RESULTS: For each seed, statistically significant (p &lt; 0.05) connections were found for all the 5 groups. When comparing the 3 seeds, the CM and the cold-spot had stronger connections with the postcentral and the superior temporal cortices, the brainstem, the caudate and the amygdala; the sweet-spot with the precentral and the superior frontal cortices, the cerebellum, the putamen and the nucleus accumbens. However, no statistically significant differences resulted among the 3 seeds. CONCLUSIONS: CM has widespread connections with both cortical and subcortical structures. The sweet-spot seems to correspond to the parvocellular part of CM on the border with the ventrolateral nucleus. CM connections with frontal and prefrontal areas and the cerebellum may underlie the beneficial effect against generalized seizures.

Differences in Olivo-Cerebellar Circuit and Cerebellar Network Connectivity in Essential Tremor: a Resting State fMRI Study

The olivo-cerebellar circuit is thought to play a crucial role in the pathophysiology of essential tremor (ET). Whether olivo-cerebellar circuit dysfunction is also present at rest, in the absence of clinical tremor and linked voluntary movement, remains unclear. Assessing this network in detail with fMRI is challenging, considering the brainstem is close to major arteries and pulsatile cerebrospinal fluid–filled spaces obscuring signals of interest. Here, we used methods tailored to the analysis of infratentorial structures. We hypothesize that the olivo-cerebellar circuit shows altered intra-network connectivity at rest and decreased functional coupling with other parts of the motor network in ET. In 17 ET patients and 19 healthy controls, we investigated using resting state fMRI intracerebellar functional and effective connectivity on a dedicated cerebellar atlas. With independent component analysis, we investigated data-driven cerebellar motor network activations during rest. Finally, whole-brain connectivity of cerebellar motor structures was investigated using identified components. In ET, olivo-cerebellar pathways show decreased functional connectivity compared with healthy controls. Effective connectivity analysis showed an increased inhibitory influence of the dentate nucleus towards the inferior olive. Cerebellar independent component analyses showed motor resting state networks are less strongly connected to the cerebral cortex compared to controls. Our results indicate the olivo-cerebellar circuit to be affected at rest. Also, the cerebellum is “disconnected” from the rest of the motor network. Aberrant activity, generated within the olivo-cerebellar circuit could, during action, spread towards other parts of the motor circuit and potentially underlie the characteristic tremor of this patient group.

Giant Size Pilocytic Astrocytoma in Pediatric Patient : A Case Report

Introduction: Pilocytic astrocytomas are the most common primary tumor in children and adolescents, accounting for approximately 15.6% of all brain tumors and 5.4% of all gliomas. The incidence of tumors substantially decreases with age and diagnosis in patients older than 50 years is less common. According to the Central Brain Tumor Registry of the United States (CBTRUS), its development is more common in the first two decades of life and there are few reports in the age group over 18 years.&#x0D; Case Report: An 8-year-old girl was brought by her parents with complaints of loss of consciousness. This happened 2 days before admission to the hospital. The patient was prepared for craniotomy tumor removal. During the operation, the tumor specimen was sent to Anatomical Pathology for histopathological examination. The examination revealed calcified Rosenthal Fibers and eosinophilic granular bodies.&#x0D; Discussion : Astrocytic tumors originate from neuroepithelial tissue and are grade I because of their well-defined and slow-growing nature. They are mostly found in infratentorial structures such as the cerebellum and in the midline of brain structures such as the optic nerve, hypothalamus, and brainstem. However, it can be found anywhere on the neuroaxis. Considered relatively rare in adults, there are few publications on the most efficient treatment methods and subsequent patient outcomes.&#x0D; Conclusion: Pilocytic astrocytoma (PA) treated with complete or near complete tumor resection tends to have a better prognosis, recent studies recommend aggressive tumor resection without neurologic deficits.

The “White Cerebellum Sign” after cardiac arrest

The white cerebellum sign, or reversal sign, is a rare radiological image in computed tomography of the head characterized by a hypodense image of the cerebral hemispheres with loss of white and gray matter differentiation and a relatively hyperdense image of infratentorial structures. It occurs in patients with severe, often irreversible, cerebral hypoxia. In the presented case of an 82-year-old patient with numerous comorbidities, the sign appeared about a week after successful cardiac arrest resuscitation. Despite intensive therapeutic management, the patient’s condition could not be improved, and palliative care was initiated.

Change your Angle of View

BackgroundArtifacts from surrounding bony structures, especially from the petrous bones, regularly impair soft tissue computed tomography (CT) imaging of the middle and posterior fossa. This affects flat-panel CT in particular. Sinusoidal movement of the C‑arm during acquisition (i.e. craniocaudal tilting along with semicircular rotation) is supposed to reduce artifacts, thus enhancing soft tissue imaging quality.MethodsIn the work-up of ischemic stroke or subarachnoid hemorrhage 40 patients underwent multi-slice CT (MS-CT) and either plain circular (cFP-CT; n = 20) or sinusoidal (sFP-CT; n = 20) flat-panel CT within a short interval. Two independent readers analyzed MS-CT and FP-CT datasets for recognizability of eight different brain structures and three typical types of artifacts according to a predetermined score.ResultsInterrater reliability was moderate for cFP-CT (κ = 0.575) and good to very good for ratings of MS-CT and sFP-CT (κ = 0.651 to κ = 1). MS-CT was rated to be significantly better than cFP-CT and sFP-CT (p < 0.0001) in the overall score. Yet, sFP-CT was rated to be significantly superior to cFP-CT (overall p < 0.0001) regarding most anatomical regions and petrous bone artifacts.ConclusionCompared to a standard circular protocol, sinusoidal C‑arm movement in cranial FP-CT can significantly reduce artifacts in the posterior fossa and, moreover, can improve visualization of most supratentorial and infratentorial anatomical structures.

Evaluation of Sine Spin flat detector CT imaging compared with multidetector CT

BackgroundFlat detector computed tomography (FDCT) is widely used for periprocedural imaging in the angiography suite. Sine Spin FDCT (SFDCT) is the latest generation of cone beam CT using a double...

Brainstem and cerebellar volumes at magnetic resonance imaging are smaller in fetuses with congenital heart disease

Congenital heart disease is associated with an increased risk of smaller brain volumes and structural brain damage, and impaired growth of supratentorial brain structures in utero has been linked to poor neurodevelopmental outcomes. However, little is known on brainstem and cerebellar volumes in fetuses with congenital heart disease. Moreover, it is not clear whether impaired infratentorial growth, if present, is associated with only certain types of fetal cardiac defects or with supratentorial brain growth, and whether altered biometry is already present before the third trimester. This study aimed to investigate brainstem and cerebellar volumes in fetuses with congenital heart disease and to compare them to infratentorial brain volumes in fetuses with normal hearts. Secondarily, the study aimed to identify associations between infratentorial brain biometry and the type of cardiac defects, supratentorial brain volumes, and gestational age. In this retrospective case-control study, 141 magnetic resonance imaging studies of 135 fetuses with congenital heart disease and 141 magnetic resonance imaging studies of 125 controls with normal hearts at 20 to 37 gestational weeks (median, 25 weeks) were evaluated. All cases and controls had normal birthweight and no evidence of structural brain disease or genetic syndrome. Six types of congenital heart disease were included: tetralogy of Fallot (n=32); double-outlet right ventricle (n=22); transposition of the great arteries (n=27); aortic obstruction (n=24); hypoplastic left heart syndrome (n=22); and hypoplastic right heart syndrome (n=14). First, brainstem and cerebellar volumes of each fetus were segmented and compared between cases and controls. In addition, transverse cerebellar diameters, vermian areas, and supratentorial brain and cerebrospinal fluid volumes were quantified and differences assessed between cases and controls. Volumetric differences were further analyzed according to types of cardiac defects and supratentorial brain volumes. Finally, volume ratios were created for each brain structure ([volume in fetus with congenital heart disease/respective volume in control fetus]× 100) and correlated to gestational age. Brainstem (cases, 2.1 cm3 vs controls, 2.4 cm3; P<.001) and cerebellar (cases, 3.2 cm3 vs controls, 3.4 cm3; P<.001) volumes were smaller in fetuses with congenital heart disease than in controls, whereas transverse cerebellar diameters (P=.681) and vermian areas (P=.947) did not differ between groups. Brainstem and cerebellar volumes differed between types of cardiac defects. Overall, the volume ratio of cases to controls was 80.8% for the brainstem, 90.5% for the cerebellum, and 90.1% for the supratentorial brain. Fetuses with tetralogy of Fallot and transposition of the great arteries were most severely affected by total brain volume reduction. Gestational age had no effect on volume ratios. The volume of the infratentorial brain, which contains structures considered crucial to brain function, is significantly smaller in fetuses with congenital heart disease than in controls from midgestation onward. These findings suggest that impaired growth of both supra- and infratentorial brain structures in fetuses with congenital heart disease occurs in the second trimester. Further research is needed to elucidate associations between fetal brain volumes and neurodevelopmental outcomes in congenital heart disease.

Creating Computational Models for Planning TTFields Treatment for Tumors in the Infratentorial Brain

Tumor Treating Fields (TTFields) is an FDA-approved treatment for glioblastoma multiforme (GBM) and malignant pleural mesothelioma (MPM), and is currently being investigated in a phase III trial for the treatment of brain metastases from non-small cell lung cancer (NSCLC). Increased TTFields dose density at the tumor is associated with longer patient survival. Therefore, estimating dose at the tumor utilizing computational simulations with patient-specific computational models are integral for treatment planning. NSCLC brain metastases are often observed in infratentorial brain regions. In these cases, TTFields arrays may be placed on the head, neck, and upper back. Manual segmentation of this large area is impractical and time consuming. Therefore, we developed a computational method for semi-automatic segmentation of infratentorial tissues relevant to TTFields treatment planning.We incorporated a dataset of 20 head T1w Gad MRIs of patients treated with TTFields with segmentation of the infratentorial area, and 20 CT images that incorporate head, neck and upper torso from a public database for segmentation of extracranial structures. For the segmentation of the infratentorial zone we developed an atlas-based method that deforms a predefined statistical atlas to best fit the patient's MRI. Our method then revises the initial fitting to ensure the segmented structures adhere to known anatomical relations. For supratentorial brain areas, we incorporate a custom atlas-based method. Extra-cranial zones (head, neck and upper torso) were segmented with threshold-based methods for the skin, muscle, fat, bones, and bronchi. User-defined landmarks were used to segment the esophagus and the artery. The spine and CSF were segmented automatically by identifying the relevant area and defining a constant ratio between their diameters. To evaluate the segmentation of the infratentorial regions, a trained annotator manually segmented the infratentorial area of the 20 head MRIs. We compared manual and automatic segmentations and measured the Dice overlap score.The average Dice coefficient between the human annotator and the algorithms' segmentation was 0.84 (SD = 0.05) for cerebellum and 0.67 (SD = 0.05) for brainstem. These results are comparable to those observed in supratentorial regions with a method that was verified previously. The radiation oncologist confirmed that the semi-automatic segmentation of the infratentorial, and extracranial head, neck and upper torso provides a quality result for TTFields treatment planning in a reasonable amount of time for all cases. The infratentorial segmentation is fully automatic and typically lasts a few minutes. Segmentation of extracranial structures is semi-automatic and typically lasts less than an hour.We have developed a fast method for the segmentation of infratentorial structures for TTFields planning.

Primary central nervous system lymphoma in neurosurgery

Primary central nervous system lymphoma (PCNSL) most commonly (&gt;95%) constitutes a specific kind of diffuse large B-cell lymphoma, which shows expression of CD20, CD19 and CD79a antigens on its surface and belongs to non-germinal center B-cell-like type (non-GCB). This results from both its limited localization as well as immunophenotypic and molecular features. It frequently has an aggressive clinical course and its prognosis remains highly uncertain. PCNSL’s development in areas normally free from lymphoid tissue has not been adequately explained thus far. PCNSL is usually a solitary lesion (60–70%), with the majority (c.60%) occurring in supratentorial areas, and less frequently in telencephalic nuclei and periventricular areas, corpus callosum, infratentorial structures, spinal cord or orbital cavities. Lymphoid cells can occasionally create diffuse infiltration with no mass effect — a PCNSL variant known as lymphomatosis cerebri. Reported clinical symptoms depend on the localization of the tumor in central nervous system. The most common include: cognitive impairment, behavioral changes, focal neurological deficit and symptoms of increased intracranial pressure. A final diagnosis of PCNSL requires histopathological evaluation of tissue samples obtained usually during a stereotactic biopsy. Identifying lymphoid cells in cerebrospinal fluid may also be sufficient. Chemotherapy combined with radiotherapy is the standard treatment of PCNSL. For many years, surgical treatment has been controversial. This provides constant encouragement to explore effective treatment methods, with neurosurgical involvement waiting to be further defined.

Abstract 3071: A method for infratentorial structures segmentation for tumor treating fields treatment planning

Abstract Introduction: Tumor treating fields (TTFields) is an FDA approved treatment for the management of glioblastoma multiform (GBM) and mesothelioma (MPM) and is associated with a significant extension to patients' survival. We have developed software to optimize the location of the TTFields transducer arrays (TAs) on GBM patients' head to maximize the field in the tumor region. To that end, we first segment the patients' head MRIs into five normal and three abnormal tissues. However, the current method for head segmentation was found to be less accurate at the infratentorial regions, mark some sinuses with cerebrospinal fluid (CSF), and does not identify the cerebellum and brain-stem. Therefore, it is assuming the infratentorial structures have the same electrical properties as in the cerebrum. Methods: We have developed a new method for segmentation of the head MRI that overcomes these limitations. As in the previous method, we have incorporated an atlas that is composed of an MRI image and tissue probability maps (TPM). The TPM assign each voxel in the atlas MRI with a value in the range of 0-1. This value reflects the probability that the specific tissue resides in that voxel. We have generated new customized TPMs for the cerebellum, brain stem and sinuses. Moreover, we have carefully revised the other TPMs to ensure best results. Last, we have incorporated these TPMs in a new atlas-based segmentation method. We have validated the method on 10 GBM patients T1w +gad head MRIs. Results: The average Dice coefficient between gold-standard and algorithms' segmentation was 68.4% (SD=11.2%) that is similar to the value observed with the current method implemented in the treatment-planning software (67.8%; SD=10.6%). However, the new method presented here extends the current method with the cerebellum (average Dice = 84%) and brainstem (average Dice = 67%). Moreover, the sinuses are marked with air, and erroneous CSF segments in the sinuses were removed. Conclusions: We have presented a novel method for the segmentation of the head that facilitates accurate infratentorial and supratentorial structures' segmentation. Moreover, the method eliminates erroneous CSF segmentation in the sinuses. These improvements pave the way for TTFields planning for infratentorial tumors. Citation Format: Yana Glozman, Reuben R. Shamir, Zeev Bomzon. A method for infratentorial structures segmentation for tumor treating fields treatment planning [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3071.

ISUOG Practice Guidelines (updated): sonographic examination of the fetal central nervous system. Part 2: performance of targeted neurosonography.

ISUOG Practice Guidelines (updated): sonographic examination of the fetal central nervous system. Part 2: performance of targeted neurosonography.

Microbleed patterns in critical illness and COVID-19

BackgroundCerebral microbleeds are increasingly reported in critical ill patients with respiratory failure in need of mechanical ventilation and/or extracorporeal membrane oxygenation (ECMO). Typically, these critical illness-associated microbleeds involve the juxtacortical white matter and corpus callosum. Recently, this pattern was reported in patients with respiratory failure, suffering from COVID-19. Materials and methodsIn this retrospective single-center study, we listed patients from March 11, 2020 to September 2, 2020, with laboratory-confirmed COVID-19, critical illness and cerebral microbleeds. Literature research was conducted through a methodical search on Pubmed databases on critical illness-associated microbleeds and cerebral microbleeds described in patients with COVID-19. Results and discussionOn 279 COVID-19 admissions, two cases of cerebral microbleeds were detected in critical ill patients with respiratory failure due to COVID-19. Based on review of existing literature critical illness-associated microbleeds tend to predominate in subcortical white matter and corpus callosum. Cerebral microbleeds in patients with COVID-19 tend to follow similar patterns as reported in critical illness-associated microbleeds. Hence, one patient with typical critical illness-associated microbleeds and COVID-19 is reported. However, a new pattern of widespread cortico-juxtacortical microbleeds, predominantly in the anterior vascular territory with relative sparing of deep gray matter, corpus callosum and infratentorial structures is documented in a second case. The possible etiologies of these microbleeds include hypoxia, hemorrhagic diathesis, brain endothelial erythrophagocytosis and/or cytokinopathies. An association with COVID-19 remains to be determined. ConclusionFurther systematic investigation of microbleed patterns in patients with neurological impairment and COVID-19 is necessary.

Neuroanatomical MRI study: reference values for the measurements of brainstem, cerebellar vermis, and peduncles.

To set age-specific normal reference values for brainstem, cerebellar vermis, and peduncles measurements and characterize values' variations according to gender, age, and age by gender interaction. 565 normal brain magnetic resonance examinations with normal anatomy and signal intensity of the supra- and infratentorial structures were categorized into six age groups (infant, child, adolescent, young adult, middle-age adult, and old aged adults). Patients with congenital malformations, gross pathology of the supra- or infratentorial brain, brain volume loss, developmental delay, metabolic disorders, and neuropsychological disorders (n = 2.839) were excluded. On midsagittal T1 weighted and axial T2 weighted images specific linear diameters and ratios of the brainstem, cerebellar vermis, and peduncles were attained. Two observers assessed a random sample of 100 subjects to evaluate the inter- and intraobserver reproducibility. Intraclass correlation coefficients, means ± standard deviation, one and two-way analysis of variance tests were used in the statistical analysis. Good to excellent inter- and intraobserver measurements' reproducibility were observed, except for the transverse diameter of the midbrain, the anteroposterior diameter of the medulla oblongata at the pontomedullary and cervicomedullary junctions, cerebellar vermis anteroposterior diameter, and thickness of the superior cerebellar peduncle. Age-specific mean values of the investigated measurements were established. A significant gender-related variation was recorded in the anteroposterior diameter of the basis pontis (p = 0.044), the anteroposterior diameter of the medulla oblongata at the cervicomedullary junction (p = 0.044), and cerebellar vermis height (p = 0.018). A significant age-related change was detected in all measurements except the tectal ratio. Age by gender interaction had a statistically significant effect on the tectal ratio, inferior, and middle cerebellar peduncles' thickness (p = 0.001, 0.022, and 0.028, respectively). This study provides age-specific normal mean values for various linear dimensions and ratios of the posterior fossa structures with documentation of measurements' variability according to gender, age, and their interaction. It provides a valuable reference in the clinical practice for easier differentiation between physiological and pathological conditions of the posterior fossa structures especially various neurodegenerative diseases and congenital anomalies.