37 research outputs found
Accurate localization of brain activity in presurgical fMRI by structure adaptive smoothing
An important problem of the analysis of fMRI experiments is to achieve some noise reduction of the data without blurring the shape of the activation areas. As a novel solution to this problem, the Propagation-Separation approach (PS), a structure adaptive smoothing method, has been proposed recently. PS adapts to different shapes of activation areas by generating a spatial structure corresponding to similarities and differences between time series in adjacent locations. In this paper we demonstrate how this method results in more accurate localization of brain activity. First, it is shown in numerical simulations that PS is superior over Gaussian smoothing with respect to the accurate description of the shape of activation clusters and and results in less false detections. Second, in a study of 37 presurgical planning cases we found that PS and Gaussian smoothing often yield different results, and we present examples showing aspects of the superiority of PS as applied to presurgical planning
Rapid anatomical imaging of the neonatal brain using T -prepared 3D balanced steady-state free precession
PURPOSE: To develop a new approach to 3D gradient echo-based anatomical imaging of the neonatal brain with a substantially shorter scan time than standard 3D fast spin echo (FSE) methods, while maintaining a high SNR. METHODS: T -prepration was employed immediately prior to image acquisition of 3D balanced steady-state free precession (bSSFP) with a single trajectory of center-out k-space view ordering, which requires no magnetization recovery time between imaging segments during the scan. This approach was compared with 3D FSE, 2D single-shot FSE, and product 3D bSSFP imaging in numerical simulations, plus phantom and in vivo experiments. RESULTS: T -prepared 3D bSSFP generated image contrast of gray matter, white matter, and CSF very similar to that of reference T -weighted imaging methods, without major image artifacts. Scan time of T -prepared 3D bSSFP was remarkably shorter compared to 3D FSE, whereas SNR was comparable to that of 3D FSE and higher than that of 2D single-shot FSE. Specific absorption rate of T -prepared 3D bSSFP remained within the safety limit. Determining an optimal imaging flip angle of T -prepared 3D bSSFP was critical to minimizing blurring of images. CONCLUSION: T -prepared 3D bSSFP offers an alternative method for anatomical imaging of the neonatal brain with dramatically reduced scan time compared to standard 3D FSE and higher SNR than 2D single-shot FSE
Diffuse Leptomeningeal Glioneuronal Tumor (DLGNT) With Direct Cystic Infiltration of the Optic Chiasm and Tracts
Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare pediatric neoplasm categorized by the WHO in 2016 (1, 2). It is characterized by communicating hydrocephalus, slow tumor growth, CSF with absence of tumor cells, and MRI showing diffuse leptomeningeal enhancement and cystic changes (3). Here we present, to our knowledge, the first case in which direct cystic tumor infiltration of the optic apparatus was the initial manifestation
Face reconstruction using flesh deformation modes
An important forensic problem is the identification of human skeletal remains. For this purpose the skull is commonly used as a means for building a face model, which may be used for recognition of the subject. This paper describes a method whereby a 3D computer model of the face and head is built using computer 3D graphics techniques. In reconstructing the shape of the face from a skull, it is essential to have data relating the shape of the face to the shape of the underlying skull. In manual reconstruction techniques this information is derived from flesh depth tables. We offer a method in which Computer Tomography (CT) scans are used to get a dense set of measurements of flesh depth. To model the variation of the facial shape, Principal Component Analysis is used as a means of exploring the space of the major facial deformations. After a subject skull and a set of database skulls have been aligned, the average face and principal deformations may be computed. Also provided are interactive tools for substituting facial features (such as nose, eyes, ears) from a catalog of such parts.
Diffusion Weighted/Tensor Imaging, Functional MRI and Perfusion Weighted Imaging in Glioblastoma—Foundations and Future
In this article, we review the basics of diffusion tensor imaging and functional MRI, their current utility in preoperative neurosurgical mapping, and their limitations. We also discuss potential future applications, including implementation of resting state functional MRI. We then discuss perfusion and diffusion-weighted imaging and their application in advanced neuro-oncologic practice. We explain how these modalities can be helpful in guiding surgical biopsies and differentiating recurrent tumor from treatment related changes
A Pilot Study of Quantitative MRI Measurements of Ventricular Volume and Cortical Atrophy for the Differential Diagnosis of Normal Pressure Hydrocephalus
Current radiologic diagnosis of normal pressure hydrocephalus (NPH) requires a subjective judgment of whether lateral ventricular enlargement is disproportionate to cerebral atrophy based on visual inspection of brain images. We investigated whether quantitative measurements of lateral ventricular volume and total cortical thickness (a correlate of cerebral atrophy) could be used to more objectively distinguish NPH from normal controls (NC), Alzheimer's (AD), and Parkinson's disease (PD). Volumetric MRIs were obtained prospectively from patients with NPH (n=5), PD (n=5), and NC (5). Additional NC (n=5) and AD patients (n=10) from the ADNI cohort were examined. Although mean ventricular volume was significantly greater in the NPH group than all others, the range of values overlapped those of the AD group. Individuals with NPH could be better distinguished when ventricular volume and total cortical thickness were considered in combination. This pilot study suggests that volumetric MRI measurements hold promise for improving NPH differential diagnosis
Accurate Localization of Brain Activity in Presurgical fMRI by Structure Adaptive Smoothing
An important problem of the analysis of functional magnetic resonance imaging (fMRI) experiments is to achieve some noise reduction of the data without blurring the shape of the activation areas. As a novel solution to this problem, recently the propagation-separation (PS) approach has been proposed. PS is a structure adaptive smoothing method that adapts to different shapes of activation areas. In this paper, we demonstrate how this method results in a more accurate localization of brain activity. First, it is shown in numerical simulations that PS is superior over Gaussian smoothing with respect to the accurate description of the shape of activation clusters and results in less false detections. Second, in a study of 37 presurgical planning cases we found that PS and Gaussian smoothing often yield different results, and we present examples showing aspects of the superiority of PS as applied to presurgical planning
Central nervous system tuberculoma mimicking a brain tumor: A case report
The central nervous system (CNS) is a rare but serious site of tuberculosis spread that manifests in three forms: meningitis, spinal arachnoiditis, and CNS tuberculoma. CNS tuberculoma, or intracranial tuberculous granuloma, is a caseating or non-caseating granulomatous reaction within the brain parenchyma that may mimic a brain tumor. We present the case of a 10-year-old male patient with a travel history to Western Africa who presented to our institution after his fourth tonic-clonic seizure over 2 months. MRI of the brain revealed a solitary cortical/subcortical enhancing intracranial mass with intralesional hemorrhage and mineralization, pathologically proven to represent a CNS tuberculoma. While rare, this etiology should be considered with the appropriate travel history and for which prompt treatment may improve outcomes in the pediatric population