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Sample records for calibrain structural mri

  1. Prospective multi-centre Voxel Based Morphometry study employing scanner specific segmentations: Procedure development using CaliBrain structural MRI data

    PubMed Central

    2009-01-01

    Background Structural Magnetic Resonance Imaging (sMRI) of the brain is employed in the assessment of a wide range of neuropsychiatric disorders. In order to improve statistical power in such studies it is desirable to pool scanning resources from multiple centres. The CaliBrain project was designed to provide for an assessment of scanner differences at three centres in Scotland, and to assess the practicality of pooling scans from multiple-centres. Methods We scanned healthy subjects twice on each of the 3 scanners in the CaliBrain project with T1-weighted sequences. The tissue classifier supplied within the Statistical Parametric Mapping (SPM5) application was used to map the grey and white tissue for each scan. We were thus able to assess within scanner variability and between scanner differences. We have sought to correct for between scanner differences by adjusting the probability mappings of tissue occupancy (tissue priors) used in SPM5 for tissue classification. The adjustment procedure resulted in separate sets of tissue priors being developed for each scanner and we refer to these as scanner specific priors. Results Voxel Based Morphometry (VBM) analyses and metric tests indicated that the use of scanner specific priors reduced tissue classification differences between scanners. However, the metric results also demonstrated that the between scanner differences were not reduced to the level of within scanner variability, the ideal for scanner harmonisation. Conclusion Our results indicate the development of scanner specific priors for SPM can assist in pooling of scan resources from different research centres. This can facilitate improvements in the statistical power of quantitative brain imaging studies. PMID:19445668

  2. Bayesian segmentation of brainstem structures in MRI.

    PubMed

    Iglesias, Juan Eugenio; Van Leemput, Koen; Bhatt, Priyanka; Casillas, Christen; Dutt, Shubir; Schuff, Norbert; Truran-Sacrey, Diana; Boxer, Adam; Fischl, Bruce

    2015-06-01

    In this paper we present a method to segment four brainstem structures (midbrain, pons, medulla oblongata and superior cerebellar peduncle) from 3D brain MRI scans. The segmentation method relies on a probabilistic atlas of the brainstem and its neighboring brain structures. To build the atlas, we combined a dataset of 39 scans with already existing manual delineations of the whole brainstem and a dataset of 10 scans in which the brainstem structures were manually labeled with a protocol that was specifically designed for this study. The resulting atlas can be used in a Bayesian framework to segment the brainstem structures in novel scans. Thanks to the generative nature of the scheme, the segmentation method is robust to changes in MRI contrast or acquisition hardware. Using cross validation, we show that the algorithm can segment the structures in previously unseen T1 and FLAIR scans with great accuracy (mean error under 1mm) and robustness (no failures in 383 scans including 168 AD cases). We also indirectly evaluate the algorithm with a experiment in which we study the atrophy of the brainstem in aging. The results show that, when used simultaneously, the volumes of the midbrain, pons and medulla are significantly more predictive of age than the volume of the entire brainstem, estimated as their sum. The results also demonstrate that the method can detect atrophy patterns in the brainstem structures that have been previously described in the literature. Finally, we demonstrate that the proposed algorithm is able to detect differential effects of AD on the brainstem structures. The method will be implemented as part of the popular neuroimaging package FreeSurfer.

  3. Automated Localization of Multiple Pelvic Bone Structures on MRI.

    PubMed

    Onal, Sinan; Lai-Yuen, Susana; Bao, Paul; Weitzenfeld, Alfredo; Hart, Stuart

    2016-01-01

    In this paper, we present a fully automated localization method for multiple pelvic bone structures on magnetic resonance images (MRI). Pelvic bone structures are at present identified manually on MRI to locate reference points for measurement and evaluation of pelvic organ prolapse (POP). Given that this is a time-consuming and subjective procedure, there is a need to localize pelvic bone structures automatically. However, bone structures are not easily differentiable from soft tissue on MRI as their pixel intensities tend to be very similar. In this paper, we present a model that combines support vector machines and nonlinear regression capturing global and local information to automatically identify the bounding boxes of bone structures on MRI. The model identifies the location of the pelvic bone structures by establishing the association between their relative locations and using local information such as texture features. Results show that the proposed method is able to locate the bone structures of interest accurately (dice similarity index >0.75) in 87-91% of the images. This research aims to enable accurate, consistent, and fully automated localization of bone structures on MRI to facilitate and improve the diagnosis of health conditions such as female POP.

  4. Structural brain MRI trait polygenic score prediction of cognitive abilities

    PubMed Central

    Luciano, Michelle; Marioni, Riccardo E; Hernández, Maria Valdés; Maniega, Susana Munoz; Hamilton, Iona F; Royle, Natalie A.; Scotland, Generation; Chauhan, Ganesh; Bis, Joshua C.; Debette, Stephanie; DeCarli, Charles; Fornage, Myriam; Schmidt, Reinhold; Ikram, M. Arfan; Launer, Lenore J.; Seshadri, Sudha; Bastin, Mark E.; Porteous, David J.; Wardlaw, Joanna; Deary, Ian J

    2016-01-01

    Structural brain magnetic resonance imaging (MRI) traits share part of their genetic variance with cognitive traits. Here, we use genetic association results from large meta-analytic studies of genome-wide association for brain infarcts, white matter hyperintensities, intracranial, hippocampal and total brain volumes to estimate polygenic scores for these traits in three Scottish samples: Generation Scotland: Scottish Family Health Study (GS:SFHS), and the Lothian Birth Cohorts of 1936 (LBC1936) and 1921 (LBC1921). These five brain MRI trait polygenic scores were then used to 1) predict corresponding MRI traits in the LBC1936 (numbers ranged 573 to 630 across traits) and 2) predict cognitive traits in all three cohorts (in 8,115 to 8,250 persons). In the LBC1936, all MRI phenotypic traits were correlated with at least one cognitive measure; and polygenic prediction of MRI traits was observed for intracranial volume. Meta-analysis of the correlations between MRI polygenic scores and cognitive traits revealed a significant negative correlation (maximal r=0.08) between the hippocampal volume polygenic score and measures of global cognitive ability collected in childhood and in old age in the Lothian Birth Cohorts. The lack of association to a related general cognitive measure when including the GS:SFHS points to either type 1 error or the importance of using prediction samples that closely match the demographics of the genome-wide association samples from which prediction is based. Ideally, these analyses should be repeated in larger samples with data on both MRI and cognition, and using MRI GWA results from even larger meta-analysis studies. PMID:26427786

  5. Passive ventricular mechanics modelling using MRI of structure and function.

    PubMed

    Wang, V Y; Lam, H I; Ennis, D B; Young, A A; Nash, M P

    2008-01-01

    Patients suffering from dilated cardiomyopathy or myocardial infarction can develop left ventricular (LV) diastolic impairment. The LV remodels its structure and function to adapt to pathophysiological changes in geometry and loading conditions and this remodeling process can alter the passive ventricular mechanics. In order to better understand passive ventricular mechanics, a LV finite element model was developed to incorporate physiological and mechanical information derived from in vivo magnetic resonance imaging (MRI) tissue tagging, in vivo LV cavity pressure recording and ex vivo diffusion tensor MRI (DTMRI) of a canine heart. MRI tissue tagging enables quantitative evaluation of cardiac mechanical function with high spatial and temporal resolution, whilst the direction of maximum water diffusion (the primary eigenvector) in each voxel of a DTMRI directly correlates with the myocardial fibre orientation. This model was customized to the geometry of the canine LV during diastasis by fitting the segmented epicardial and endocardial surface data from tagged MRI using nonlinear finite element fitting techniques. Myofibre orientations, extracted from DTMRI of the same heart, were incorporated into this geometric model using a free form deformation methodology. Pressure recordings, temporally synchronized to the tissue tagging MRI data, were used to simulate the LV deformation during diastole. Simulation of the diastolic LV mechanics allowed us to estimate the stiffness of the passive LV myocardium based on kinematic data obtained from tagged MRI. This integrated physiological model will allow more insight into the regional passive diastolic mechanics of the LV on an individualized basis, thereby improving our understanding of the underlying structural basis of mechanical dysfunction in pathological conditions.

  6. Structural MRI connectome in development: challenges of the changing brain

    PubMed Central

    Hess, C P; Xu, D; Barkovich, A J

    2014-01-01

    MRI connectomics is an emerging approach to study the brain as a network of interconnected brain regions. Understanding and mapping the development of the MRI connectome may offer new insights into the development of brain connectivity and plasticity, ultimately leading to improved understanding of normal development and to more effective diagnosis and treatment of developmental disorders. In this review, we describe the attempts made to date to map the whole-brain structural MRI connectome in the developing brain and pay a special attention to the challenges associated with the rapid changes that the brain is undergoing during maturation. The two main steps in constructing a structural brain network are (i) choosing connectivity measures that will serve as the network “edges” and (ii) finding an appropriate way to divide the brain into regions that will serve as the network “nodes”. We will discuss how these two steps are usually performed in developmental studies and the rationale behind different strategies. Changes in local and global network properties that have been described during maturation in neonates and children will be reviewed, along with differences in network topology between typically and atypically developing subjects, for example, owing to pre-mature birth or hypoxic ischaemic encephalopathy. Finally, future directions of connectomics will be discussed, addressing important steps necessary to advance the study of the structural MRI connectome in development. PMID:24827379

  7. Segmentation of knee MRI using structure enhanced local phase filtering

    NASA Astrophysics Data System (ADS)

    Lim, Mikhiel; Hacihaliloglu, Ilker

    2016-03-01

    The segmentation of bone surfaces from magnetic resonance imaging (MRI) data has applications in the quanti- tative measurement of knee osteoarthritis, surgery planning for patient specific total knee arthroplasty and its subsequent fabrication of artificial implants. However, due to the problems associated with MRI imaging such as low contrast between bone and surrounding tissues, noise, bias fields, and the partial volume effect, segmentation of bone surfaces continues to be a challenging operation. In this paper, a new framework is presented for the enhancement of knee MRI scans prior to segmentation in order to obtain high contrast bone images. During the first stage, a new contrast enhanced relative total variation (RTV) regularization method is used in order to remove textural noise from the bone structures and surrounding soft tissue interface. This salient bone edge information is further enhanced using a sparse gradient counting method based on L0 gradient minimization, which globally controls how many non-zero gradients are resulted in order to approximate prominent bone structures in a structure-sparsity-management manner. The last stage of the framework involves incorporation of local phase bone boundary information in order to provide an intensity invariant enhancement of contrast between the bone and surrounding soft tissue. The enhanced images are segmented using a fast random walker algorithm. Validation against expert segmentation was performed on 10 clinical knee MRI images, and achieved a mean dice similarity coefficient (DSC) of 0.975.

  8. MRI

    MedlinePlus

    MRI does not use ionizing radiation. No side effects from the magnetic fields and radio waves have been reported. The most common type of contrast (dye) used is gadolinium. It is very safe. Allergic reactions rarely ...

  9. Post-processing of structural MRI for individualized diagnostics

    PubMed Central

    Bender, Benjamin; Focke, Niels K.

    2015-01-01

    Currently, a relevant proportion of all histopathologically proven focal cortical dysplasia (FCD) escape visual detection; this shows the need for additional improvements in analyzing MRI data. A positive MRI is still the strongest prognostic factor for postoperative freedom of seizures. Among several post-processing methods voxel-based morphometry (VBM) of T1- and T2-weighted sequences and T2 relaxometry are routinely applied in pre-surgical diagnostics of cryptogenic epilepsy in epilepsy centers. VBM is superior to conventional visual analysis with 9-15% more identified epileptogenic foci, while T2 relaxometry has its main application in (mesial) temporal lobe epilepsy. Further methods such as surface-based morphometry (SBM) or diffusion tensor imaging are promising but there is a lack of current studies comparing their individual diagnostic value. Post-processing methods represent an important addition to conventional visual analysis but need to be interpreted with expertise and experience so that they should be apprehended as a complementary tool within the context of the multi-modal evaluation of epilepsy patients. This review will give an overview of existing post-processing methods of structural MRI and outline their clinical relevance in detection of epileptogenic structural changes. PMID:25853079

  10. Lag structure in resting-state fMRI

    PubMed Central

    Snyder, A. Z.; Hacker, C. D.; Raichle, M. E.

    2014-01-01

    The discovery that spontaneous fluctuations in blood oxygen level-dependent (BOLD) signals contain information about the functional organization of the brain has caused a paradigm shift in neuroimaging. It is now well established that intrinsic brain activity is organized into spatially segregated resting-state networks (RSNs). Less is known regarding how spatially segregated networks are integrated by the propagation of intrinsic activity over time. To explore this question, we examined the latency structure of spontaneous fluctuations in the fMRI BOLD signal. Our data reveal that intrinsic activity propagates through and across networks on a timescale of ∼1 s. Variations in the latency structure of this activity resulting from sensory state manipulation (eyes open vs. closed), antecedent motor task (button press) performance, and time of day (morning vs. evening) suggest that BOLD signal lags reflect neuronal processes rather than hemodynamic delay. Our results emphasize the importance of the temporal structure of the brain's spontaneous activity. PMID:24598530

  11. Differential diagnosis of neurodegenerative diseases using structural MRI data.

    PubMed

    Koikkalainen, Juha; Rhodius-Meester, Hanneke; Tolonen, Antti; Barkhof, Frederik; Tijms, Betty; Lemstra, Afina W; Tong, Tong; Guerrero, Ricardo; Schuh, Andreas; Ledig, Christian; Rueckert, Daniel; Soininen, Hilkka; Remes, Anne M; Waldemar, Gunhild; Hasselbalch, Steen; Mecocci, Patrizia; van der Flier, Wiesje; Lötjönen, Jyrki

    2016-01-01

    Different neurodegenerative diseases can cause memory disorders and other cognitive impairments. The early detection and the stratification of patients according to the underlying disease are essential for an efficient approach to this healthcare challenge. This emphasizes the importance of differential diagnostics. Most studies compare patients and controls, or Alzheimer's disease with one other type of dementia. Such a bilateral comparison does not resemble clinical practice, where a clinician is faced with a number of different possible types of dementia. Here we studied which features in structural magnetic resonance imaging (MRI) scans could best distinguish four types of dementia, Alzheimer's disease, frontotemporal dementia, vascular dementia, and dementia with Lewy bodies, and control subjects. We extracted an extensive set of features quantifying volumetric and morphometric characteristics from T1 images, and vascular characteristics from FLAIR images. Classification was performed using a multi-class classifier based on Disease State Index methodology. The classifier provided continuous probability indices for each disease to support clinical decision making. A dataset of 504 individuals was used for evaluation. The cross-validated classification accuracy was 70.6% and balanced accuracy was 69.1% for the five disease groups using only automatically determined MRI features. Vascular dementia patients could be detected with high sensitivity (96%) using features from FLAIR images. Controls (sensitivity 82%) and Alzheimer's disease patients (sensitivity 74%) could be accurately classified using T1-based features, whereas the most difficult group was the dementia with Lewy bodies (sensitivity 32%). These results were notable better than the classification accuracies obtained with visual MRI ratings (accuracy 44.6%, balanced accuracy 51.6%). Different quantification methods provided complementary information, and consequently, the best results were obtained by

  12. Differential diagnosis of neurodegenerative diseases using structural MRI data

    PubMed Central

    Koikkalainen, Juha; Rhodius-Meester, Hanneke; Tolonen, Antti; Barkhof, Frederik; Tijms, Betty; Lemstra, Afina W.; Tong, Tong; Guerrero, Ricardo; Schuh, Andreas; Ledig, Christian; Rueckert, Daniel; Soininen, Hilkka; Remes, Anne M.; Waldemar, Gunhild; Hasselbalch, Steen; Mecocci, Patrizia; van der Flier, Wiesje; Lötjönen, Jyrki

    2016-01-01

    Different neurodegenerative diseases can cause memory disorders and other cognitive impairments. The early detection and the stratification of patients according to the underlying disease are essential for an efficient approach to this healthcare challenge. This emphasizes the importance of differential diagnostics. Most studies compare patients and controls, or Alzheimer's disease with one other type of dementia. Such a bilateral comparison does not resemble clinical practice, where a clinician is faced with a number of different possible types of dementia. Here we studied which features in structural magnetic resonance imaging (MRI) scans could best distinguish four types of dementia, Alzheimer's disease, frontotemporal dementia, vascular dementia, and dementia with Lewy bodies, and control subjects. We extracted an extensive set of features quantifying volumetric and morphometric characteristics from T1 images, and vascular characteristics from FLAIR images. Classification was performed using a multi-class classifier based on Disease State Index methodology. The classifier provided continuous probability indices for each disease to support clinical decision making. A dataset of 504 individuals was used for evaluation. The cross-validated classification accuracy was 70.6% and balanced accuracy was 69.1% for the five disease groups using only automatically determined MRI features. Vascular dementia patients could be detected with high sensitivity (96%) using features from FLAIR images. Controls (sensitivity 82%) and Alzheimer's disease patients (sensitivity 74%) could be accurately classified using T1-based features, whereas the most difficult group was the dementia with Lewy bodies (sensitivity 32%). These results were notable better than the classification accuracies obtained with visual MRI ratings (accuracy 44.6%, balanced accuracy 51.6%). Different quantification methods provided complementary information, and consequently, the best results were obtained by

  13. Structural and functional correlates of visual field asymmetry in the human brain by diffusion kurtosis MRI and functional MRI.

    PubMed

    O'Connell, Caitlin; Ho, Leon C; Murphy, Matthew C; Conner, Ian P; Wollstein, Gadi; Cham, Rakie; Chan, Kevin C

    2016-11-01

    Human visual performance has been observed to show superiority in localized regions of the visual field across many classes of stimuli. However, the underlying neural mechanisms remain unclear. This study aims to determine whether the visual information processing in the human brain is dependent on the location of stimuli in the visual field and the corresponding neuroarchitecture using blood-oxygenation-level-dependent functional MRI (fMRI) and diffusion kurtosis MRI, respectively, in 15 healthy individuals at 3 T. In fMRI, visual stimulation to the lower hemifield showed stronger brain responses and larger brain activation volumes than the upper hemifield, indicative of the differential sensitivity of the human brain across the visual field. In diffusion kurtosis MRI, the brain regions mapping to the lower visual field showed higher mean kurtosis, but not fractional anisotropy or mean diffusivity compared with the upper visual field. These results suggested the different distributions of microstructural organization across visual field brain representations. There was also a strong positive relationship between diffusion kurtosis and fMRI responses in the lower field brain representations. In summary, this study suggested the structural and functional brain involvements in the asymmetry of visual field responses in humans, and is important to the neurophysiological and psychological understanding of human visual information processing.

  14. Patterns of Structural MRI Abnormalities in Deficit and Nondeficit Schizophrenia

    PubMed Central

    Galderisi, Silvana; Quarantelli, Mario; Volpe, Umberto; Mucci, Armida; Cassano, Giovanni Battista; Invernizzi, Giordano; Rossi, Alessandro; Vita, Antonio; Pini, Stefano; Cassano, Paolo; Daneluzzo, Enrico; De Peri, Luca; Stratta, Paolo; Brunetti, Arturo; Maj, Mario

    2008-01-01

    Negative symptoms of schizophrenia have generally been found in association with ventricular enlargement and prefrontal abnormalities. These relationships, however, have not been observed consistently, most probably because negative symptoms are heterogeneous and result from different pathophysiological mechanisms. The concept of deficit schizophrenia (DS) was introduced by Carpenter et al to identify a clinically homogeneous subgroup of patients characterized by the presence of primary and enduring negative symptoms. Findings of brain structural abnormalities reported by magnetic resonance imaging (MRI) studies focusing on DS have been mixed. The present study included 34 patients with DS, 32 with nondeficit schizophrenia (NDS), and 31 healthy comparison subjects, providing the largest set of MRI findings in DS published so far. The Schedule for the Deficit Syndrome was used to categorize patients as DS or NDS patients. The 2 patient groups were matched on age and gender and did not differ on clinical variables, except for higher scores on the negative dimension and more impaired interpersonal relationships in DS than in NDS subjects. Lateral ventricles were larger in NDS than in control subjects but were not enlarged in patients with DS. The cingulate gyri volume was smaller in NDS but not in DS patients as compared with healthy subjects. Both groups had smaller dorsolateral prefrontal cortex and temporal lobes than healthy subjects, but DS patients had significantly less right temporal lobe volume as compared with NDS patients. These findings do not support the hypothesis that DS is the extreme end of a severity continuum within schizophrenia. PMID:17728266

  15. Structure and function relationship of human heart from DENSE MRI

    NASA Astrophysics Data System (ADS)

    Moghaddam, Abbas N.; Gharib, Morteza

    2007-03-01

    The study here, suggests a macroscopic structure for the Left Ventricle (LV), based on the heart kinematics which is obtained through imaging. The measurement of the heart muscle deformation using the Displacement ENcoding with Stimulated Echoes (DENSE) MRI, which describes the heart kinematics in the Lagrangian frame work, is used to determine the high resolution patterns of true myocardial strain. Subsequently, the tangential Shortening Index (SI) and the thickening of the LV wall are calculated for each data point. Considering the heart as a positive-displacement pump, the contribution of each segment of LV in the heart function, can be determined by the SI and thickening of the wall in the same portion. Hence the SI isosurfaces show the extent and spatial distribution of the heart activity and reveals its macro structure. The structure and function of the heart are, therefore, related which in turn results in a macroscopic model for the LV. In particular, it was observed that the heart functionality is not uniformly distributed in the LV, and the regions with greater effect on the pumping process, form a band which wraps around the heart. These results, which are supported by the established histological evidence, may be considered as a landmark in connecting the structure and function of the heart through imaging. Furthermore, the compatibility of this model with microscopic observations about the fiber direction is investigated. This method may be used for planning as well as post evaluation of the ventriculoplasty.

  16. Complementary aspects of diffusion imaging and fMRI; I: structure and function.

    PubMed

    Mulkern, Robert V; Davis, Peter E; Haker, Steven J; Estepar, Raul San Jose; Panych, Lawrence P; Maier, Stephan E; Rivkin, Michael J

    2006-05-01

    Studying the intersection of brain structure and function is an important aspect of modern neuroscience. The development of magnetic resonance imaging (MRI) over the last 25 years has provided new and powerful tools for the study of brain structure and function. Two tools in particular, diffusion imaging and functional MRI (fMRI), are playing increasingly important roles in elucidating the complementary aspects of brain structure and function. In this work, we review basic technical features of diffusion imaging and fMRI for studying the integrity of white matter structural components and for determining the location and extent of cortical activation in gray matter, respectively. We then review a growing body of literature in which the complementary aspects of diffusion imaging and fMRI, applied as separate examinations but analyzed in tandem, have been exploited to enhance our knowledge of brain structure and function. PMID:16677953

  17. Multiple sclerosis, cannabis, and cognition: A structural MRI study

    PubMed Central

    Romero, Kristoffer; Pavisian, Bennis; Staines, William R.; Feinstein, Anthony

    2015-01-01

    Objective A subset of patients with multiple sclerosis (MS) smoke cannabis to relieve symptoms including spasticity and pain. Recent evidence suggests that smoking cannabis further impairs cognition in people with MS and is linked to impaired functional brain changes. No such association, however, has been reported between cannabis use and structural brain changes, hence the focus of the present study. Methods Twenty patients with MS who smoke cannabis for symptom relief, and 19 matched non-cannabis-smoking MS patients were given the Brief Repeatable Neuropsychological Battery and structural MRI scans. Images were segmented into gray matter and white matter, and subsequently analysed with Partial Least Squares, a data-driven multivariate technique that explores brain–behaviour associations. Results In both groups, the Partial Least Squares analysis yielded significant correlations between cognitive scores and both gray matter (33% variance, p < .0001) and white matter (17% variance, p < .05) volume. Gray matter volume in the thalamus, basal ganglia, medial temporal, and medial prefrontal regions, and white matter volume in the fornix correlated with cognitive deficits. Crucially, the analysis indicated that brain volume reductions were associated with more extensive cognitive impairment in the cannabis versus the non-cannabis MS group. Interpretation These results suggest that cannabis use in MS results in more widespread cognitive deficits, which correlate with tissue volume in subcortical, medial temporal, and prefrontal regions. These are the first findings demonstrating an association between cannabis use, cognitive impairment and structural brain changes in MS patients. PMID:26106538

  18. Incorporating MRI structural information into bioluminescence tomography: system, heterogeneous reconstruction and in vivo quantification

    PubMed Central

    Zhang, Jun; Chen, Duofang; Liang, Jimin; Xue, Huadan; Lei, Jing; Wang, Qin; Chen, Dongmei; Meng, Ming; Jin, Zhengyu; Tian, Jie

    2014-01-01

    Combining two or more imaging modalities to provide complementary information has become commonplace in clinical practice and in preclinical and basic biomedical research. By incorporating the structural information provided by computed tomography (CT) or magnetic resonance imaging (MRI), the ill poseness nature of bioluminescence tomography (BLT) can be reduced significantly, thus improve the accuracies of reconstruction and in vivo quantification. In this paper, we present a small animal imaging system combining multi-view and multi-spectral BLT with MRI. The independent MRI-compatible optical device is placed at the end of the clinical MRI scanner. The small animal is transferred between the light tight chamber of the optical device and the animal coil of MRI via a guide rail during the experiment. After the optical imaging and MRI scanning procedures are finished, the optical images are mapped onto the MRI surface by interactive registration between boundary of optical images and silhouette of MRI. Then, incorporating the MRI structural information, a heterogeneous reconstruction algorithm based on finite element method (FEM) with L 1 normalization is used to reconstruct the position, power and region of the light source. In order to validate the feasibility of the system, we conducted experiments of nude mice model implanted with artificial light source and quantitative analysis of tumor inoculation model with MDA-231-GFP-luc. Preliminary results suggest the feasibility and effectiveness of the prototype system. PMID:24940545

  19. 7-Tesla MRI demonstrates absence of structural lesions in patients with vestibular paroxysmia.

    PubMed

    Rommer, Paulus S; Wiest, Gerald; Kronnerwetter, Claudia; Zach, Heidemarie; Loader, Benjamin; Elwischger, Kirsten; Trattnig, Siegfried

    2015-01-01

    Vestibular parxoysmia (VP) is a rare vestibular disorder. A neurovascular cross-compression (NVCC) between the vestibulochochlear nerve and an artery seems to be responsible for short attacks of vertigo in this entity. An NVCC can be seen in up to every fourth subject. The significance of these findings is not clear, as not all subjects suffer from symptoms. The aim of the present study was to assess possible structural lesions of the vestibulocochlear nerve by means of high field magnetic resonance imaging (MRI), and whether high field MRI may help to differentiate symptomatic from asymptomatic subjects. 7 Tesla MRI was performed in six patients with VP and confirmed NVCC seen on 1.5 and 3.0 MRI. No structural abnormalities were detected in any of the patients in 7 Tesla MRI. These findings imply that high field MRI does not help to differentiate between symptomatic and asymptomatic NVCC and that the symptoms of VP are not caused by structural nerve lesions. This supports the hypothesis that the nystagmus associated with VP has to be conceived pathophysiologically as an excitatory vestibular phenomenon, being not related to vestibular hypofunction. 7 Tesla MRI outperforms conventional MRI in image resolution and may be useful in vestibular disorders.

  20. Predicting aphasia type from brain damage measured with structural MRI.

    PubMed

    Yourganov, Grigori; Smith, Kimberly G; Fridriksson, Julius; Rorden, Chris

    2015-12-01

    Chronic aphasia is a common consequence of a left-hemisphere stroke. Since the early insights by Broca and Wernicke, studying the relationship between the loci of cortical damage and patterns of language impairment has been one of the concerns of aphasiology. We utilized multivariate classification in a cross-validation framework to predict the type of chronic aphasia from the spatial pattern of brain damage. Our sample consisted of 98 patients with five types of aphasia (Broca's, Wernicke's, global, conduction, and anomic), classified based on scores on the Western Aphasia Battery (WAB). Binary lesion maps were obtained from structural MRI scans (obtained at least 6 months poststroke, and within 2 days of behavioural assessment); after spatial normalization, the lesions were parcellated into a disjoint set of brain areas. The proportion of damage to the brain areas was used to classify patients' aphasia type. To create this parcellation, we relied on five brain atlases; our classifier (support vector machine - SVM) could differentiate between different kinds of aphasia using any of the five parcellations. In our sample, the best classification accuracy was obtained when using a novel parcellation that combined two previously published brain atlases, with the first atlas providing the segmentation of grey matter, and the second atlas used to segment the white matter. For each aphasia type, we computed the relative importance of different brain areas for distinguishing it from other aphasia types; our findings were consistent with previously published reports of lesion locations implicated in different types of aphasia. Overall, our results revealed that automated multivariate classification could distinguish between aphasia types based on damage to atlas-defined brain areas. PMID:26465238

  1. MRI Scans

    MedlinePlus

    Magnetic resonance imaging (MRI) uses a large magnet and radio waves to look at organs and structures inside your body. Health care professionals use MRI scans to diagnose a variety of conditions, from torn ...

  2. Functional and structural MRI biomarkers to detect pre-clinical neurodegeneration.

    PubMed

    Abdulkadir, Ahmed; Ronneberger, Olaf; Wolf, Robert Christian; Pfleiderer, Bettina; Saft, Carsten; Klöppel, Stefan

    2013-02-01

    The availability of an accurate genetic test to identify Huntington's Disease (HD) in the pre-symptomatic stage makes HD an important model to develop biomarkers for other neurodegenerative diseases, such as pre-clinical Alzheimer's Disease. We reasoned that functional changes, measured by functional MRI (fMRI), would precede gray matter changes and that performing a task specifically affected by the disease would carry the clearest signature. Separate cohorts of HD gene mutations carriers and controls performed four different fMRI tasks, probing functions either primarly affected by the disease (i.e. motor control), higher cognitive functions (i.e. working memory and irritability), or basic sensory functions (i.e. auditory system). With the aim to compare fMRI and structural MRI biomarkers, all subjects underwent an additional high-resolution T1-weighted MRI. Best classification performance was achived from fMRI-based activations with motor sequence tapping and task-induced irritation. Classification performance based on gray matter probability maps was also significantly above chance and similar to that of fMRI. Both were sufficiently informative to separate gene mutation carriers that were on average 17 years before predicted disease onset from controls with up to 80% accuracy. Further analyses showed that classification accuracy was best in regions of interest with low within-group heterogeneity in relation to disease specific changes. Our study indicates that structural and some functional markers can accurately detect pre-clinical neurodegeneration. However, the lower variability and easier processing of the strucutral MRI data make latter the more useful tool for disease detection in a clinical setting.

  3. Information fusion approach for detection of brain structures in MRI

    NASA Astrophysics Data System (ADS)

    Shademan, Azad; Soltanian-Zadeh, Hamid

    2002-05-01

    This paper presents an information fusion approach for automatic detection of mid-brain nuclei (caudate, putamen, globus pallidus, and thalamus) from MRI. The method is based on fusion of anatomical information, obtained from brain atlases and expert physicians, into MRI numerical information within a fuzzy framework, employed to model intrinsic uncertainty of problem. First step of this method is segmentation of brain tissues (gray matter, white matter, and cerebrospinal fluid). Physical landmarks such as inter-hemispheric plane alongside numerical information from segmentation step are then used to describe the nuclei. Each nucleus is defined according to a unique description according to physical landmarks and anatomical landmarks, most of which are the previously detected nuclei. Also, a detected nucleus in slice n serves as key landmark to detect same nucleus in slice n+1. These steps construct fuzzy decision maps. Overall decision is made after fusing all of decisions according to a fusion operator. This approach has been implemented to detect caudate, putamen, and thalamus from a sequence of axial T1-weighted brain MRI's. Our experience shows that final nuclei detection results are highly dependent upon primary tissue segmentation. The method is validated by comparing resultant nuclei volumes with those obtained using manual segmentation performed by expert physicians.

  4. Congruent MRI and near-infrared spectroscopy for functional and structural imaging of tumors.

    PubMed

    Gulsen, Gultekin; Yu, Hon; Wang, Jun; Nalcioglu, Orhan; Merritt, Sean; Bevilacqua, Frederic; Durkin, Anthony J; Cuccia, David J; Lanning, Ryan; Tromberg, Bruce J

    2002-12-01

    We present a combined near-infrared diffuse optical spectroscopy (DOS) and Magnetic Resonance Imaging (MRI) system for the study of animal model tumors. A combined broadband steady-state and frequency domain optical spectroscopy apparatus was integrated with the MRI. The physiological properties of tissue rendered by MRI, including vascular volume fraction and water, were compared with chromophore concentrations as determined from the parameters obtained by optical measurements. DOS measurements provided oxy-hemoglobin, deoxy-hemoglobin, and water concentration locally in tumors. A method for co-registration of the information obtained by both modalities was developed. Using Monte Carlo simulations, the optically sampled volume was superimposed on the MR images, illustrating which tissue structure was probed optically. Finally, two optical contrast agents, indocyanine green (ICG) and methylene blue (MB), were employed and their kinetics were measured by DOS system from different locations on the tumor and compared with Gd-DTPA enhancement maps obtained from MRI.

  5. 3D structure tensor analysis of light microscopy data for validating diffusion MRI

    PubMed Central

    Khan, Ahmad Raza; Cornea, Anda; Leigland, Lindsey A.; Kohama, Steven G.; Jespersen, Sune Nørhøj; Kroenke, Christopher D.

    2015-01-01

    Diffusion magnetic resonance imaging (d-MRI) is a powerful non-invasive and non-destructive technique for characterizing brain tissue on the microscopic scale. However, the lack of validation of d-MRI by independent experimental means poses an obstacle to accurate interpretation of data acquired using this method. Recently, structure tensor analysis has been applied to light microscopy images, and this technique holds promise to be a powerful validation strategy for d-MRI. Advantages of this approach include its similarity to d-MRI in terms of averaging the effects of a large number of cellular structures, and its simplicity, which enables it to be implemented in a high-throughput manner. However, a drawback of previous implementations of this technique arises from it being restricted to 2D. As a result, structure tensor analyses have been limited to tissue sectioned in a direction orthogonal to the direction of interest. Here we describe the analytical framework for extending structure tensor analysis to 3D, and utilize the results to analyze serial image “stacks” acquired with confocal microscopy of rhesus macaque hippocampal tissue. Implementation of 3D structure tensor procedures requires removal of sources of anisotropy introduced in tissue preparation and confocal imaging. This is accomplished with image processing steps to mitigate the effects of anisotropic tissue shrinkage, and the effects of anisotropy in the point spread function (PSF). In order to address the latter confound, we describe procedures for measuring the dependence of PSF anisotropy on distance from the microscope objective within tissue. Prior to microscopy, ex vivo d-MRI measurements performed on the hippocampal tissue revealed three regions of tissue with mutually orthogonal directions of least restricted diffusion that correspond to CA1, alveus and inferior longitudinal fasciculus. We demonstrate the ability of 3D structure tensor analysis to identify structure tensor orientations

  6. 3D structure tensor analysis of light microscopy data for validating diffusion MRI.

    PubMed

    Khan, Ahmad Raza; Cornea, Anda; Leigland, Lindsey A; Kohama, Steven G; Jespersen, Sune Nørhøj; Kroenke, Christopher D

    2015-05-01

    Diffusion magnetic resonance imaging (d-MRI) is a powerful non-invasive and non-destructive technique for characterizing brain tissue on the microscopic scale. However, the lack of validation of d-MRI by independent experimental means poses an obstacle to accurate interpretation of data acquired using this method. Recently, structure tensor analysis has been applied to light microscopy images, and this technique holds promise to be a powerful validation strategy for d-MRI. Advantages of this approach include its similarity to d-MRI in terms of averaging the effects of a large number of cellular structures, and its simplicity, which enables it to be implemented in a high-throughput manner. However, a drawback of previous implementations of this technique arises from it being restricted to 2D. As a result, structure tensor analyses have been limited to tissue sectioned in a direction orthogonal to the direction of interest. Here we describe the analytical framework for extending structure tensor analysis to 3D, and utilize the results to analyze serial image "stacks" acquired with confocal microscopy of rhesus macaque hippocampal tissue. Implementation of 3D structure tensor procedures requires removal of sources of anisotropy introduced in tissue preparation and confocal imaging. This is accomplished with image processing steps to mitigate the effects of anisotropic tissue shrinkage, and the effects of anisotropy in the point spread function (PSF). In order to address the latter confound, we describe procedures for measuring the dependence of PSF anisotropy on distance from the microscope objective within tissue. Prior to microscopy, ex vivo d-MRI measurements performed on the hippocampal tissue revealed three regions of tissue with mutually orthogonal directions of least restricted diffusion that correspond to CA1, alveus and inferior longitudinal fasciculus. We demonstrate the ability of 3D structure tensor analysis to identify structure tensor orientations that

  7. SEMI-AUTOMATIC SEGMENTATION OF BRAIN SUBCORTICAL STRUCTURES FROM HIGH-FIELD MRI

    PubMed Central

    Kim, Jinyoung; Lenglet, Christophe; Sapiro, Guillermo; Harel, Noam

    2015-01-01

    Volumetric segmentation of subcortical structures such as the basal ganglia and thalamus is necessary for non-invasive diagnosis and neurosurgery planning. This is a challenging problem due in part to limited boundary information between structures, similar intensity profiles across the different structures, and low contrast data. This paper presents a semi-automatic segmentation system exploiting the superior image quality of ultra-high field (7 Tesla) MRI. The proposed approach handles and exploits multiple structural MRI modalities. It uniquely combines T1-weighted (T1W), T2-weighted (T2W), diffusion, and susceptibility-weighted (SWI) MRI and introduces a dedicated new edge indicator function. In addition to this, we employ prior shape and configuration knowledge of the subcortical structures in order to guide the evolution of geometric active surfaces. Neighboring structures are segmented iteratively, constraining over-segmentation at their borders with a non-overlapping penalty. Extensive experiments with data acquired on a 7T MRI scanner demonstrate the feasibility and power of the approach for the segmentation of basal ganglia components critical for neurosurgery applications such as deep brain stimulation. PMID:25192576

  8. The Importance of the Default Mode Network in Creativity--A Structural MRI Study

    ERIC Educational Resources Information Center

    Kühn, Simone; Ritter, Simone M.; Müller, Barbara C. N.; van Baaren, Rick B.; Brass, Marcel; Dijksterhuis, Ap

    2014-01-01

    Anecdotal reports as well as behavioral studies have suggested that creative performance benefits from unconscious processes. So far, however, little is known about how creative ideas arise from the brain. In the current study, we aimed to investigate the neural correlates of creativity by means of structural MRI research. Given that unconscious…

  9. MRI as a tool to study brain structure from mouse models for mental retardation

    NASA Astrophysics Data System (ADS)

    Verhoye, Marleen; Sijbers, Jan; Kooy, R. F.; Reyniers, E.; Fransen, E.; Oostra, B. A.; Willems, Peter; Van der Linden, Anne-Marie

    1998-07-01

    Nowadays, transgenic mice are a common tool to study brain abnormalities in neurological disorders. These studies usually rely on neuropathological examinations, which have a number of drawbacks, including the risk of artefacts introduced by fixation and dehydration procedures. Here we present 3D Fast Spin Echo Magnetic Resonance Imaging (MRI) in combination with 2D and 3D segmentation techniques as a powerful tool to study brain anatomy. We set up MRI of the brain in mouse models for the fragile X syndrome (FMR1 knockout) and Corpus callosum hypoplasia, mental Retardation, Adducted thumbs, Spastic paraplegia and Hydrocephalus (CRASH) syndrome (L1CAM knockout). Our major goal was to determine qualitative and quantitative differences in specific brain structures. MRI of the brain of fragile X and CRASH patients has revealed alterations in the size of specific brain structures, including the cerebellar vermis and the ventricular system. In the present MRI study of the brain from fragile X knockout mice, we have measured the size of the brain, cerebellum and 4th ventricle, which were reported as abnormal in human fragile X patients, but found no evidence for altered brain regions in the mouse model. In CRASH syndrome, the most specific brain abnormalities are vermis hypoplasia and abnormalities of the ventricular system with some degree of hydrocephalus. With the MRI study of L1CAM knockout mice we found vermis hypoplasia, abnormalities of the ventricular system including dilatation of the lateral and the 4th ventricles. These subtle abnormalities were not detected upon standard neuropathological examination. Here we proved that this sensitive MRI technique allows to measure small differences which can not always be detected by means of pathology.

  10. A neurodevelopmental basis for BECTS: Evidence from structural MRI

    PubMed Central

    Pardoe, Heath R.; Berg, Anne T.; Archer, John S.; Fulbright, Robert K.; Jackson, Graeme D.

    2013-01-01

    Summary Purpose BECTS (benign epilepsy with centro-temporal spikes) is one of the most common childhood-onset epilepsy syndromes. We investigated quantitative evidence for brain morphological variation associated with BECTS to provide insights into the neuroanatomical basis of this disorder. Methods Three independent BECTS groups were imaged at different stages: (a) near onset (n = 16, mean age 9.3 ± 1.6 years), (b) ~9 years after onset (n = 9, mean age 15.8 ± 2.3 years), and (c) ~15 years after onset (n = 10, mean age 22.7 ± 2.7 years). Age-matched controls were imaged with each group. Whole brain T1-weighted MRI was acquired. Voxel-based morphometry (groups a–c) and cortical thickness analyses (groups b and c) were undertaken within each group and for the groups combined. The relationship between cortical morphology and age was investigated. Key findings The voxel-based morphometry analysis indicated increased bilateral grey matter volume in the superior frontal gyrus, insula and right inferior frontal gyrus regions in BECTS. The magnitude of the increase lessened with age of the cases. Cortical thickness analysis revealed thicker cortex in BECTS along middle and inferior frontal gyri bilaterally, left insula and bilateral supramarginal gyrus in the 9-year-after-onset group, that normalised with age. The rate of cortical thickness changes with age were greater in BECTS cases than in controls. Significance Increased cortical gray matter associated with BECTS was found. The decreasing magnitude of the effect with increasing age parallels the natural history of the disorder. The areas affected are consistent with neurocognitive dysfunction in BECTS. PMID:23375559

  11. Registration of structurally dissimilar images in MRI-based brachytherapy

    NASA Astrophysics Data System (ADS)

    Berendsen, F. F.; Kotte, A. N. T. J.; de Leeuw, A. A. C.; Jürgenliemk-Schulz, I. M.; Viergever, M. A.; Pluim, J. P. W.

    2014-08-01

    A serious challenge in image registration is the accurate alignment of two images in which a certain structure is present in only one of the two. Such topological changes are problematic for conventional non-rigid registration algorithms. We propose to incorporate in a conventional free-form registration framework a geometrical penalty term that minimizes the volume of the missing structure in one image. We demonstrate our method on cervical MR images for brachytherapy. The intrapatient registration problem involves one image in which a therapy applicator is present and one in which it is not. By including the penalty term, a substantial improvement in the surface distance to the gold standard anatomical position and the residual volume of the applicator void are obtained. Registration of neighboring structures, i.e. the rectum and the bladder is generally improved as well, albeit to a lesser degree.

  12. Structural brain MRI studies in eye diseases: are they clinically relevant? A review of current findings.

    PubMed

    Prins, Doety; Hanekamp, Sandra; Cornelissen, Frans W

    2016-03-01

    Many eye diseases reduce visual acuity or are associated with visual field defects. Because of the well-defined retinotopic organization of the connections of the visual pathways, this may affect specific parts of the visual pathways and cortex, as a result of either deprivation or transsynaptic degeneration. For this reason, over the past several years, numerous structural magnetic resonance imaging (MRI) studies have examined the association of eye diseases with pathway and brain changes. Here, we review structural MRI studies performed in human patients with the eye diseases albinism, amblyopia, hereditary retinal dystrophies, age-related macular degeneration (AMD) and glaucoma. We focus on two main questions. First, what have these studies revealed? Second, what is the potential clinical relevance of their findings? We find that all the aforementioned eye diseases are indeed associated with structural changes in the visual pathways and brain. As such changes have been described in very different eye diseases, in our view the most parsimonious explanation is that these are caused by the loss of visual input and the subsequent deprivation of the visual pathways and brain regions, rather than by transsynaptic degeneration. Moreover, and of clinical relevance, for some of the diseases - in particular glaucoma and AMD - present results are compatible with the view that the eye disease is part of a more general neurological or neurodegenerative disorder that also affects the brain. Finally, establishing structural changes of the visual pathways has been relevant in the context of new therapeutic strategies to restore retinal function: it implies that restoring retinal function may not suffice to also effectively restore vision. Future structural MRI studies can contribute to (i) further establish relationships between ocular and neurological neurodegenerative disorders, (ii) investigate whether brain degeneration in eye diseases is reversible, (iii) evaluate the use

  13. Combination of dynamic (11)C-PIB PET and structural MRI improves diagnosis of Alzheimer's disease.

    PubMed

    Liu, Linwen; Fu, Liping; Zhang, Xi; Zhang, Jinming; Zhang, Xiaojun; Xu, Baixuan; Tian, Jiahe; Fan, Yong

    2015-08-30

    Structural magnetic resonance imaging (sMRI) is an established technique for measuring brain atrophy, and dynamic positron emission tomography with (11)C-Pittsburgh compound B ((11)C-PIB PET) has the potential to provide both perfusion and amyloid deposition information. It remains unclear, however, how to better combine perfusion, amyloid deposition and morphological information extracted from dynamic (11)C-PIB PET and sMRI with the goal of improving the diagnosis of Alzheimer's disease (AD) and mild cognitive impairment (MCI). We adopted a linear sparse support vector machine to build classifiers for distinguishing AD and MCI subjects from cognitively normal (CN) subjects based on different combinations of regional measures extracted from imaging data, including perfusion and amyloid deposition information extracted from early and late frames of (11)C-PIB separately, and gray matter volumetric information extracted from sMRI data. The experimental results demonstrated that the classifier built upon the combination of imaging measures extracted from early and late frames of (11)C-PIB as well as sMRI achieved the highest classification accuracy in both classification studies of AD (100%) and MCI (85%), indicating that multimodality information could aid in the diagnosis of AD and MCI. PMID:26095348

  14. Graph theoretical analysis of structural and functional connectivity MRI in normal and pathological brain networks.

    PubMed

    Guye, Maxime; Bettus, Gaelle; Bartolomei, Fabrice; Cozzone, Patrick J

    2010-12-01

    Graph theoretical analysis of structural and functional connectivity MRI data (ie. diffusion tractography or cortical volume correlation and resting-state or task-related (effective) fMRI, respectively) has provided new measures of human brain organization in vivo. The most striking discovery is that the whole-brain network exhibits "small-world" properties shared with many other complex systems (social, technological, information, biological). This topology allows a high efficiency at different spatial and temporal scale with a very low wiring and energy cost. Its modular organization also allows for a high level of adaptation. In addition, degree distribution of brain networks demonstrates highly connected hubs that are crucial for the whole-network functioning. Many of these hubs have been identified in regions previously defined as belonging to the default-mode network (potentially explaining the high basal metabolism of this network) and the attentional networks. This could explain the crucial role of these hub regions in physiology (task-related fMRI data) as well as in pathophysiology. Indeed, such topological definition provides a reliable framework for predicting behavioral consequences of focal or multifocal lesions such as stroke, tumors or multiple sclerosis. It also brings new insights into a better understanding of pathophysiology of many neurological or psychiatric diseases affecting specific local or global brain networks such as epilepsy, Alzheimer's disease or schizophrenia. Graph theoretical analysis of connectivity MRI data provides an outstanding framework to merge anatomical and functional data in order to better understand brain pathologies. PMID:20349109

  15. Combined MRI-PET dissects dynamic changes in plant structures and functions.

    PubMed

    Jahnke, Siegfried; Menzel, Marion I; van Dusschoten, Dagmar; Roeb, Gerhard W; Bühler, Jonas; Minwuyelet, Senay; Blümler, Peter; Temperton, Vicky M; Hombach, Thomas; Streun, Matthias; Beer, Simone; Khodaverdi, Maryam; Ziemons, Karl; Coenen, Heinz H; Schurr, Ulrich

    2009-08-01

    Unravelling the factors determining the allocation of carbon to various plant organs is one of the great challenges of modern plant biology. Studying allocation under close to natural conditions requires non-invasive methods, which are now becoming available for measuring plants on a par with those developed for humans. By combining magnetic resonance imaging (MRI) and positron emission tomography (PET), we investigated three contrasting root/shoot systems growing in sand or soil, with respect to their structures, transport routes and the translocation dynamics of recently fixed photoassimilates labelled with the short-lived radioactive carbon isotope (11)C. Storage organs of sugar beet (Beta vulgaris) and radish plants (Raphanus sativus) were assessed using MRI, providing images of the internal structures of the organs with high spatial resolution, and while species-specific transport sectoralities, properties of assimilate allocation and unloading characteristics were measured using PET. Growth and carbon allocation within complex root systems were monitored in maize plants (Zea mays), and the results may be used to identify factors affecting root growth in natural substrates or in competition with roots of other plants. MRI-PET co-registration opens the door for non-invasive analysis of plant structures and transport processes that may change in response to genomic, developmental or environmental challenges. It is our aim to make the methods applicable for quantitative analyses of plant traits in phenotyping as well as in understanding the dynamics of key processes that are essential to plant performance.

  16. Verbal Memory Decline following DBS for Parkinson’s Disease: Structural Volumetric MRI Relationships

    PubMed Central

    Geevarghese, Ruben; Lumsden, Daniel E.; Costello, Angela; Hulse, Natasha; Ayis, Salma; Samuel, Michael; Ashkan, Keyoumars

    2016-01-01

    Background Parkinson’s disease is a chronic degenerative movement disorder. The mainstay of treatment is medical. In certain patients Deep Brain Stimulation (DBS) may be offered. However, DBS has been associated with post-operative neuropsychology changes, especially in verbal memory. Objectives Firstly, to determine if pre-surgical thalamic and hippocampal volumes were related to verbal memory changes following DBS. Secondly, to determine if clinical factors such as age, duration of symptoms or motor severity (UPDRS Part III score) were related to verbal memory changes. Methods A consecutive group of 40 patients undergoing bilateral Subthalamic Nucleus (STN)-DBS for PD were selected. Brain MRI data was acquired, pre-processed and structural volumetric data was extracted using FSL. Verbal memory test scores for pre- and post-STN-DBS surgery were recorded. Linear regression was used to investigate the relationship between score change and structural volumetric data. Results A significant relationship was demonstrated between change in List Learning test score and thalamic (left, p = 0.02) and hippocampal (left, p = 0.02 and right p = 0.03) volumes. Duration of symptoms was also associated with List Learning score change (p = 0.02 to 0.03). Conclusion Verbal memory score changes appear to have a relationship to pre-surgical MRI structural volumetric data. The findings of this study provide a basis for further research into the use of pre-surgical MRI to counsel PD patients regarding post-surgical verbal memory changes. PMID:27557088

  17. Synthesis, structural characterization and in vitro testing of dysprosium containing silica particles as potential MRI contrast enhancing agents

    NASA Astrophysics Data System (ADS)

    Chiriac, L. B.; Trandafir, D. L.; Turcu, R. V. F.; Todea, M.; Simon, S.

    2016-11-01

    The work is focused on synthesis and structural characterization of novel dysprosium-doped silica particles which could be considered as MRI contrast agents. Sol-gel derived silica rich particles obtained via freeze-drying and spray-drying processing methods were structurally characterized by XRD, 29Si MAS-NMR and XPS methods. The occurrence of dysprosium on the outermost layer of dysprosium containing silica particles was investigated by XPS analysis. The MRI contrast agent characteristics have been tested using RARE-T1 and RARE-T2 protocols. The contrast of MRI images delivered by the investigated samples was correlated with their local structure. Dysprosium disposal on microparticles with surface structure characterised by decreased connectivity of the silicate network units favours dark T2-weighted MRI contrast properties.

  18. Inferring functional connectivity in MRI using Bayesian network structure learning with a modified PC algorithm.

    PubMed

    Iyer, Swathi P; Shafran, Izhak; Grayson, David; Gates, Kathleen; Nigg, Joel T; Fair, Damien A

    2013-07-15

    Resting state functional connectivity MRI (rs-fcMRI) is a popular technique used to gauge the functional relatedness between regions in the brain for typical and special populations. Most of the work to date determines this relationship by using Pearson's correlation on BOLD fMRI timeseries. However, it has been recognized that there are at least two key limitations to this method. First, it is not possible to resolve the direct and indirect connections/influences. Second, the direction of information flow between the regions cannot be differentiated. In the current paper, we follow-up on recent work by Smith et al. (2011), and apply PC algorithm to both simulated data and empirical data to determine whether these two factors can be discerned with group average, as opposed to single subject, functional connectivity data. When applied on simulated individual subjects, the algorithm performs well determining indirect and direct connection but fails in determining directionality. However, when applied at group level, PC algorithm gives strong results for both indirect and direct connections and the direction of information flow. Applying the algorithm on empirical data, using a diffusion-weighted imaging (DWI) structural connectivity matrix as the baseline, the PC algorithm outperformed the direct correlations. We conclude that, under certain conditions, the PC algorithm leads to an improved estimate of brain network structure compared to the traditional connectivity analysis based on correlations.

  19. Cerebral basis of visual hallucinations in Parkinson's disease: structural and functional MRI studies.

    PubMed

    Ibarretxe-Bilbao, Naroa; Junque, Carme; Marti, Maria J; Tolosa, Eduardo

    2011-11-15

    The presence of visual hallucinations (VH) is a significant predictor of dementia in Parkinson's disease (PD) and it is associated with a more rapid cognitive decline. Non-demented PD patients with VH present greater neuropsychological impairment than those without VH in domains such as verbal and visual memory, language comprehension, and visuospatial and visuoperceptive functions. Frontal dysfunction has also been described in PD with VH, including deficits in verbal fluency, sustained attention, and inhibition. In PD with VH, structural and functional abnormalities within the primary visual system and visual association areas, including ventral and dorsal pathways, have been reported. Structural MRI studies have shown that non-demented PD patients with VH present grey matter reduction in parieto-occipital areas and the hippocampal head. A follow-up study performed at a mean of 30 months revealed that unlike PD patients without VH, PD patients with VH frequently develop dementia associated with progressive atrophy in limbic, paralimbic and neocortical areas. Functional MRI (fMRI) studies have revealed altered activation in occipito-temporal and frontal areas in response to simple and complex visual stimuli in PD patients with VH, suggesting a marked impairment in bottom-up visual processing, as well as an attentional deficit in the pathophysiology of VH in PD.

  20. Visualization and quantification of whole rat heart laminar structure using high-spatial resolution contrast-enhanced MRI.

    PubMed

    Gilbert, Stephen H; Benoist, David; Benson, Alan P; White, Ed; Tanner, Steven F; Holden, Arun V; Dobrzynski, Halina; Bernus, Olivier; Radjenovic, Aleksandra

    2012-01-01

    It has been shown by histology that cardiac myocytes are organized into laminae and this structure is important in function, both influencing the spread of electrical activation and enabling myocardial thickening in systole by laminar sliding. We have carried out high-spatial resolution three-dimensional MRI of the ventricular myolaminae of the entire volume of the isolated rat heart after contrast perfusion [dimeglumine gadopentate (Gd-DTPA)]. Four ex vivo rat hearts were perfused with Gd-DTPA and fixative and high-spatial resolution MRI was performed on a 9.4T MRI system. After MRI, cryosectioning followed by histology was performed. Images from MRI and histology were aligned, described, and quantitatively compared. In the three-dimensional MR images we directly show the presence of laminae and demonstrate that these are highly branching and are absent from much of the subepicardium. We visualized these MRI volumes to demonstrate laminar architecture and quantitatively demonstrated that the structural features observed are similar to those imaged in histology. We showed qualitatively and quantitatively that laminar architecture is similar in the four hearts. MRI can be used to image the laminar architecture of ex vivo hearts in three dimensions, and the images produced are qualitatively and quantitatively comparable with histology. We have demonstrated in the rat that: 1) laminar architecture is consistent between hearts; 2) myolaminae are absent from much of the subepicardium; and 3) although localized orthotropy is present throughout the myocardium, tracked myolaminae are branching structures and do not have a discrete identity.

  1. Discriminative analysis of schizophrenia using support vector machine and recursive feature elimination on structural MRI images.

    PubMed

    Lu, Xiaobing; Yang, Yongzhe; Wu, Fengchun; Gao, Minjian; Xu, Yong; Zhang, Yue; Yao, Yongcheng; Du, Xin; Li, Chengwei; Wu, Lei; Zhong, Xiaomei; Zhou, Yanling; Fan, Ni; Zheng, Yingjun; Xiong, Dongsheng; Peng, Hongjun; Escudero, Javier; Huang, Biao; Li, Xiaobo; Ning, Yuping; Wu, Kai

    2016-07-01

    Structural abnormalities in schizophrenia (SZ) patients have been well documented with structural magnetic resonance imaging (MRI) data using voxel-based morphometry (VBM) and region of interest (ROI) analyses. However, these analyses can only detect group-wise differences and thus, have a poor predictive value for individuals. In the present study, we applied a machine learning method that combined support vector machine (SVM) with recursive feature elimination (RFE) to discriminate SZ patients from normal controls (NCs) using their structural MRI data. We first employed both VBM and ROI analyses to compare gray matter volume (GMV) and white matter volume (WMV) between 41 SZ patients and 42 age- and sex-matched NCs. The method of SVM combined with RFE was used to discriminate SZ patients from NCs using significant between-group differences in both GMV and WMV as input features. We found that SZ patients showed GM and WM abnormalities in several brain structures primarily involved in the emotion, memory, and visual systems. An SVM with a RFE classifier using the significant structural abnormalities identified by the VBM analysis as input features achieved the best performance (an accuracy of 88.4%, a sensitivity of 91.9%, and a specificity of 84.4%) in the discriminative analyses of SZ patients. These results suggested that distinct neuroanatomical profiles associated with SZ patients might provide a potential biomarker for disease diagnosis, and machine-learning methods can reveal neurobiological mechanisms in psychiatric diseases. PMID:27472673

  2. MRI-detectable changes in mouse brain structure induced by voluntary exercise.

    PubMed

    Cahill, Lindsay S; Steadman, Patrick E; Jones, Carly E; Laliberté, Christine L; Dazai, Jun; Lerch, Jason P; Stefanovic, Bojana; Sled, John G

    2015-06-01

    Physical exercise, besides improving cognitive and mental health, is known to cause structural changes in the brain. Understanding the structural changes that occur with exercise as well as the neuroanatomical correlates of a predisposition for exercise is important for understanding human health. This study used high-resolution 3D MR imaging, in combination with deformation-based morphometry, to investigate the macroscopic changes in brain structure that occur in healthy adult mice following four weeks of voluntary exercise. We found that exercise induced changes in multiple brain structures that are involved in motor function and learning and memory including the hippocampus, dentate gyrus, stratum granulosum of the dentate gyrus, cingulate cortex, olivary complex, inferior cerebellar peduncle and regions of the cerebellum. In addition, a number of brain structures, including the hippocampus, striatum and pons, when measured on MRI prior to the start of exercise were highly predictive of subsequent exercise activity. Exercise tended to normalize these pre-existing differences between mice.

  3. Unified structural equation modeling approach for the analysis of multisubject, multivariate functional MRI data.

    PubMed

    Kim, Jieun; Zhu, Wei; Chang, Linda; Bentler, Peter M; Ernst, Thomas

    2007-02-01

    The ultimate goal of brain connectivity studies is to propose, test, modify, and compare certain directional brain pathways. Path analysis or structural equation modeling (SEM) is an ideal statistical method for such studies. In this work, we propose a two-stage unified SEM plus GLM (General Linear Model) approach for the analysis of multisubject, multivariate functional magnetic resonance imaging (fMRI) time series data with subject-level covariates. In Stage 1, we analyze the fMRI multivariate time series for each subject individually via a unified SEM model by combining longitudinal pathways represented by a multivariate autoregressive (MAR) model, and contemporaneous pathways represented by a conventional SEM. In Stage 2, the resulting subject-level path coefficients are merged with subject-level covariates such as gender, age, IQ, etc., to examine the impact of these covariates on effective connectivity via a GLM. Our approach is exemplified via the analysis of an fMRI visual attention experiment. Furthermore, the significant path network from the unified SEM analysis is compared to that from a conventional SEM analysis without incorporating the longitudinal information as well as that from a Dynamic Causal Modeling (DCM) approach.

  4. Manganese-enhanced MRI reveals structural and functional changes in the cortex of Bassoon mutant mice.

    PubMed

    Angenstein, Frank; Niessen, Heiko G; Goldschmidt, Jürgen; Lison, Holger; Altrock, Wilko D; Gundelfinger, Eckart D; Scheich, Henning

    2007-01-01

    Manganese-enhanced magnetic resonance imaging (ME-MRI) was used to analyze the brain architecture in mice lacking the functional presynaptic active zone protein Bassoon. Anatomical characterization revealed a significant increase in the total brain volume in Bassoon mutants as compared with wild-type mice, which is mainly caused by changes in cortex and hippocampus volume. The measured enlargement in cortical volume coincides with an altered Mn2+ distribution within cortical layers as visualized by T1-weighted magnetic resonance imaging. Two days after manganese application, the cortex of Bassoon mutant mice appeared more laminated in ME-MRI, with an enhanced accumulation of manganese in deep, central, and superficial cortical cell layers. Whereas morphologically the cortical lamination is not affected by the absence of a functional Bassoon, an altered basal activation pattern was found in the cortex of the mutant mice both by metabolic labeling with [14C]-2-deoxyglucose and histochemical detection of the potassium analogue thallium uptake. Consequently, the results indicate that the absence of the functional presynaptic protein Bassoon causes disturbance in the formation of normal basal cortical activation patterns and thereby in the functional cortical architecture. Furthermore, this study shows that ME-MRI can become a valuable tool for a structural characterization of genetically modified mice.

  5. Discovering anatomical patterns with pathological meaning by clustering of visual primitives in structural brain MRI

    NASA Astrophysics Data System (ADS)

    Leon, Juan; Pulido, Andrea; Romero, Eduardo

    2015-01-01

    Computational anatomy is a subdiscipline of the anatomy that studies macroscopic details of the human body structure using a set of automatic techniques. Different reference systems have been developed for brain mapping and morphometry in functional and structural studies. Several models integrate particular anatomical regions to highlight pathological patterns in structural brain MRI, a really challenging task due to the complexity, variability, and nonlinearity of the human brain anatomy. In this paper, we present a strategy that aims to find anatomical regions with pathological meaning by using a probabilistic analysis. Our method starts by extracting visual primitives from brain MRI that are partitioned into small patches and which are then softly clustered, forming different regions not necessarily connected. Each of these regions is described by a co- occurrence histogram of visual features, upon which a probabilistic semantic analysis is used to find the underlying structure of the information, i.e., separated regions by their low level similarity. The proposed approach was tested with the OASIS data set which includes 69 Alzheimer's disease (AD) patients and 65 healthy subjects (NC).

  6. Structure-function relationships underlying calculation: a combined diffusion tensor imaging and fMRI study.

    PubMed

    van Eimeren, L; Grabner, R H; Koschutnig, K; Reishofer, G; Ebner, F; Ansari, D

    2010-08-01

    Both neuropsychological and functional neuroimaging studies have identified brain regions that are critical for the neurocognitive processes related to the calculation of arithmetic problems. In particular, the left angular gyrus (lAG) has been repeatedly implicated in arithmetic problem solving and found to be most activated during the retrieval of arithmetic facts. While significant progress has been made in determining the functional role of specific grey matter areas underlying calculation, very little is known about the relationship between these activated regions and their underlying white matter structures. In this study, we collected both diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) data while participants performed a mental arithmetic task. Fractional anisotropy (FA) values were extracted from predefined, hypothesis-driven, white matter regions and correlated with fMRI activation values, which were extracted from anatomically defined grey matter regions. Results indicated structure-function relationships on multiple levels. Specifically, a link between the integrity of the left superior corona radiata (SCR) and neural activity in the lAG during calculation was observed, which was found to be particularly strong for problems that have a high probability of being solved via the retrieval of arithmetic facts (problems with a relatively small problem size). The findings reported provide a link between functional activation and structural integrity of grey and white matter regions in the left temporoparietal cortex, thereby contributing to our understanding of the role of both the function and structure of this brain region in calculation. PMID:20382234

  7. Structural Image Analysis of the Brain in Neuropsychology Using Magnetic Resonance Imaging (MRI) Techniques.

    PubMed

    Bigler, Erin D

    2015-09-01

    Magnetic resonance imaging (MRI) of the brain provides exceptional image quality for visualization and neuroanatomical classification of brain structure. A variety of image analysis techniques provide both qualitative as well as quantitative methods to relate brain structure with neuropsychological outcome and are reviewed herein. Of particular importance are more automated methods that permit analysis of a broad spectrum of anatomical measures including volume, thickness and shape. The challenge for neuropsychology is which metric to use, for which disorder and the timing of when image analysis methods are applied to assess brain structure and pathology. A basic overview is provided as to the anatomical and pathoanatomical relations of different MRI sequences in assessing normal and abnormal findings. Some interpretive guidelines are offered including factors related to similarity and symmetry of typical brain development along with size-normalcy features of brain anatomy related to function. The review concludes with a detailed example of various quantitative techniques applied to analyzing brain structure for neuropsychological outcome studies in traumatic brain injury.

  8. Structural MRI biomarkers of shared pathogenesis in autism spectrum disorder and epilepsy.

    PubMed

    Blackmon, Karen

    2015-06-01

    Etiological factors that contribute to a high comorbidity between autism spectrum disorder (ASD) and epilepsy are the subject of much debate. Does epilepsy cause ASD or are there common underlying brain abnormalities that increase the risk of developing both disorders? This review summarizes evidence from quantitative MRI studies to suggest that abnormalities of brain structure are not necessarily the consequence of ASD and epilepsy but are antecedent to disease expression. Abnormal gray and white matter volumes are present prior to onset of ASD and evident at the time of onset in pediatric epilepsy. Aberrant brain growth trajectories are also common in both disorders, as evidenced by blunted gray matter maturation and white matter maturation. Although the etiological factors that explain these abnormalities are unclear, high heritability estimates for gray matter volume and white matter microstructure demonstrate that genetic factors assert a strong influence on brain structure. In addition, histopathological studies of ASD and epilepsy brain tissue reveal elevated rates of malformations of cortical development (MCDs), such as focal cortical dysplasia and heterotopias, which supports disruption of neuronal migration as a contributing factor. Although MCDs are not always visible on MRI with conventional radiological analysis, quantitative MRI detection methods show high sensitivity to subtle malformations in epilepsy and can be potentially applied to MCD detection in ASD. Such an approach is critical for establishing quantitative neuroanatomic endophenotypes that can be used in genetic research. In the context of emerging drug treatments for seizures and autism symptoms, such as rapamycin and rapalogs, in vivo neuroimaging markers of subtle structural brain abnormalities could improve sample stratification in human clinical trials and potentially extend the range of patients that might benefit from treatment. This article is part of a Special Issue entitled "Autism

  9. Feasibility of Structural and Functional MRI Acquisition with Unpowered Implants in Argus II Retinal Prosthesis Patients: A Case Study

    PubMed Central

    Cunningham, Samantha I.; Shi, Yonggang; Weiland, James D.; Falabella, Paulo; Olmos de Koo, Lisa C.; Zacks, David N.; Tjan, Bosco S.

    2015-01-01

    Purpose Magnetic resonance imaging (MRI) can measure the effects of vision loss and recovery on brain function and structure. In this case study, we sought to determine the feasibility of acquiring anatomical and functional MRI data in recipients of the Argus II epiretinal prosthesis system. Methods Following successful implantation with the Argus II device, two retinitis pigmentosa (RP) patients completed MRI scans with their implant unpowered to measure primary visual cortex (V1) functional responses to a tactile task, whole-brain morphometry, V1 cortical thickness, and diffusion properties of the optic tract and optic radiation. Measurements in the subjects with the Argus II implant were compared to measurements obtained previously from RP patients and sighted individuals. Results The presence of the Argus II implant resulted in artifacts that were localized around the patient's implanted eye and did not extend into cortical regions or white matter tracts associated with the visual system. Structural data on V1 cortical thickness and the retinofugal tract obtained from the two Argus II subjects fell within the ranges of sighted and RP groups. When compared to the RP and sighted subjects, Argus II patients' tactile-evoked cross-modal functional MRI (fMRI) blood oxygen level-dependent (BOLD) responses in V1 also fell within the range of either sighted or RP groups, apparently depending on time since implantation. Conclusions This study demonstrates that successful acquisition and quantification of structural and functional MR images are feasible in the presence of the inactive implant and provides preliminary information on functional changes in the brain that may follow sight restoration treatments. Transitional Relevance Successful MRI and fMRI acquisition in Argus II recipients demonstrates feasibility of using MRI to study the effect of retinal prosthesis use on brain structure and function. PMID:26693097

  10. Heart MRI

    MedlinePlus

    Magnetic resonance imaging - cardiac; Magnetic resonance imaging - heart; Nuclear magnetic resonance - cardiac; NMR - cardiac; MRI of the heart; Cardiomyopathy - MRI; Heart failure - MRI; Congenital heart disease - MRI

  11. New tissue priors for improved automated classification of subcortical brain structures on MRI.

    PubMed

    Lorio, S; Fresard, S; Adaszewski, S; Kherif, F; Chowdhury, R; Frackowiak, R S; Ashburner, J; Helms, G; Weiskopf, N; Lutti, A; Draganski, B

    2016-04-15

    Despite the constant improvement of algorithms for automated brain tissue classification, the accurate delineation of subcortical structures using magnetic resonance images (MRI) data remains challenging. The main difficulties arise from the low gray-white matter contrast of iron rich areas in T1-weighted (T1w) MRI data and from the lack of adequate priors for basal ganglia and thalamus. The most recent attempts to obtain such priors were based on cohorts with limited size that included subjects in a narrow age range, failing to account for age-related gray-white matter contrast changes. Aiming to improve the anatomical plausibility of automated brain tissue classification from T1w data, we have created new tissue probability maps for subcortical gray matter regions. Supported by atlas-derived spatial information, raters manually labeled subcortical structures in a cohort of healthy subjects using magnetization transfer saturation and R2* MRI maps, which feature optimal gray-white matter contrast in these areas. After assessment of inter-rater variability, the new tissue priors were tested on T1w data within the framework of voxel-based morphometry. The automated detection of gray matter in subcortical areas with our new probability maps was more anatomically plausible compared to the one derived with currently available priors. We provide evidence that the improved delineation compensates age-related bias in the segmentation of iron rich subcortical regions. The new tissue priors, allowing robust detection of basal ganglia and thalamus, have the potential to enhance the sensitivity of voxel-based morphometry in both healthy and diseased brains. PMID:26854557

  12. Brain without Anatomy: Construction and Comparison of Fully Network-Driven Structural MRI Connectomes

    PubMed Central

    Tymofiyeva, Olga; Ziv, Etay; Barkovich, A. James; Hess, Christopher P.; Xu, Duan

    2014-01-01

    MRI connectomics methods treat the brain as a network and provide new information about its organization, efficiency, and mechanisms of disruption. The most commonly used method of defining network nodes is to register the brain to a standardized anatomical atlas based on the Brodmann areas. This approach is limited by inter-subject variability and can be especially problematic in the context of brain maturation or neuroplasticity (cerebral reorganization after brain damage). In this study, we combined different image processing and network theory methods and created a novel approach that enables atlas-free construction and connection-wise comparison of diffusion MRI-based brain networks. We illustrated the proposed approach in three age groups: neonates, 6-month-old infants, and adults. First, we explored a data-driven method of determining the optimal number of equal-area nodes based on the assumption that all cortical areas of the brain are connected and, thus, no part of the brain is structurally isolated. Second, to enable a connection-wise comparison, alignment to a “reference brain” was performed in the network domain within each group using a matrix alignment algorithm with simulated annealing. The correlation coefficients after pair-wise network alignment ranged from 0.6102 to 0.6673. To test the method’s reproducibility, one subject from the 6-month-old group and one from the adult group were scanned twice, resulting in correlation coefficients of 0.7443 and 0.7037, respectively. While being less than 1 due to parcellation and noise, statistically, these values were significantly higher than inter-subject values. Rotation of the parcellation largely explained the variability. Through the abstraction from anatomy, the developed framework allows for a fully network-driven analysis of structural MRI connectomes and can be applied to subjects at any stage of development and with substantial differences in cortical anatomy. PMID:24789312

  13. Recognition of upper airway and surrounding structures at MRI in pediatric PCOS and OSAS

    NASA Astrophysics Data System (ADS)

    Tong, Yubing; Udupa, J. K.; Odhner, D.; Sin, Sanghun; Arens, Raanan

    2013-03-01

    Obstructive Sleep Apnea Syndrome (OSAS) is common in obese children with risk being 4.5 fold compared to normal control subjects. Polycystic Ovary Syndrome (PCOS) has recently been shown to be associated with OSAS that may further lead to significant cardiovascular and neuro-cognitive deficits. We are investigating image-based biomarkers to understand the architectural and dynamic changes in the upper airway and the surrounding hard and soft tissue structures via MRI in obese teenage children to study OSAS. At the previous SPIE conferences, we presented methods underlying Fuzzy Object Models (FOMs) for Automatic Anatomy Recognition (AAR) based on CT images of the thorax and the abdomen. The purpose of this paper is to demonstrate that the AAR approach is applicable to a different body region and image modality combination, namely in the study of upper airway structures via MRI. FOMs were built hierarchically, the smaller sub-objects forming the offspring of larger parent objects. FOMs encode the uncertainty and variability present in the form and relationships among the objects over a study population. Totally 11 basic objects (17 including composite) were modeled. Automatic recognition for the best pose of FOMs in a given image was implemented by using four methods - a one-shot method that does not require search, another three searching methods that include Fisher Linear Discriminate (FLD), a b-scale energy optimization strategy, and optimum threshold recognition method. In all, 30 multi-fold cross validation experiments based on 15 patient MRI data sets were carried out to assess the accuracy of recognition. The results indicate that the objects can be recognized with an average location error of less than 5 mm or 2-3 voxels. Then the iterative relative fuzzy connectedness (IRFC) algorithm was adopted for delineation of the target organs based on the recognized results. The delineation results showed an overall FP and TP volume fraction of 0.02 and 0.93.

  14. The correlation of 3D DT-MRI fiber disruption with structural and mechanical degeneration in porcine myocardium.

    PubMed

    Zhang, Song; Crow, J Allen; Yang, Xiaoyong; Chen, Joseph; Borazjani, Ali; Mullins, Katie B; Chen, Wei; Cooper, Robert C; McLaughlin, Ronald M; Liao, Jun

    2010-10-01

    Evaluation of structural parameters following a myocardial infarction (MI) is important to assess left ventricular function and remodeling. In this study, we assessed the capability of 3D diffusion tensor magnetic resonance imaging (DT-MRI) to assess tissue degeneration shortly after an MI using a porcine model of infarction. Two days after an induced infarction, hearts were explanted and immediately scanned by a 3T MRI scanner with a diffusion tensor imaging protocol. 3D fiber tracks and clustering models were generated from the diffusion-weighted imaging data. We found in a normal explanted heart that DT-MRI fibers showed a multilayered helical structure, with fiber architecture and fiber density reflecting the integrity of muscle fibers. For infarcted heart explants, we observed either a lack of fibers or disruption of fibers in the infarcted regions. Contours of the disrupted DT-MRI fibers were found to be consistent with the infarcted regions. Both histological and mechanical analysis of the infarcted hearts suggested DT-MRI fiber disruption correlated with altered microstructure and tissue mechanics. The ability of 3D DT-MRI to accurately distinguish viable myocardium from dead myocardium only 2 days post infarct without the use of radioisotopes or ionotropic agents makes it a promising approach to evaluate cardiac damage early post-MI. PMID:20499182

  15. Entorhinal cortex structure and functional MRI response during an associative verbal memory task

    PubMed Central

    Braskie, Meredith N.; Small, Gary W.; Bookheimer, Susan Y.

    2009-01-01

    Entorhinal cortex (ERC) volume in adults with mild cognitive impairment has been shown to predict prodromal Alzheimer's disease (AD). Likewise, neuronal loss in ERC has been associated with AD, but not with normal aging. Because ERC is part of a major pathway modulating input to the hippocampus, structural changes there may result in changes to cognitive performance and functional brain activity during memory tasks. In 32 cognitively intact older adults, we examined the relationship between left ERC thickness and functional magnetic resonance imaging (fMRI) activity during an associative verbal memory task. This task has been shown previously to activate regions that are sensitive to aging and AD risk. ERC was manually defined on native space, high resolution, oblique coronal MRI scans. Subjects having thicker left ERC showed greater activation in anterior cingulate and medial frontal regions during memory retrieval, but not encoding. This result was independent of hippocampal volume. Anterior cingulate cortex is directly connected to ERC, and is, along with medial frontal cortex, implicated in error detection, which is impaired in AD. Our results suggest that in healthy older adults, processes that engage frontal regions during memory retrieval are related to ERC structure. PMID:19507155

  16. Using partial correlation to enhance structural equation modeling of functional MRI data.

    PubMed

    Marrelec, Guillaume; Horwitz, Barry; Kim, Jieun; Pélégrini-Issac, Mélanie; Benali, Habib; Doyon, Julien

    2007-10-01

    In functional magnetic resonance imaging (fMRI) data analysis, effective connectivity investigates the influence that brain regions exert on one another. Structural equation modeling (SEM) has been the main approach to examine effective connectivity. In this paper, we propose a method that, given a set of regions, performs partial correlation analysis. This method provides an approach to effective connectivity that is data driven, in the sense that it does not require any prior information regarding the anatomical or functional connections. To demonstrate the practical relevance of partial correlation analysis for effective connectivity investigation, we reanalyzed data previously published [Bullmore, Horwitz, Honey, Brammer, Williams, Sharma, 2000. How good is good enough in path analysis of fMRI data? NeuroImage 11, 289-301]. Specifically, we show that partial correlation analysis can serve several purposes. In a pre-processing step, it can hint at which effective connections are structuring the interactions and which have little influence on the pattern of connectivity. As a post-processing step, it can be used both as a simple and visual way to check the validity of SEM optimization algorithms and to show which assumptions made by the model are valid, and which ones should be further modified to better fit the data.

  17. Knowledge-based deformable surface model with application to segmentation of brain structures in MRI

    NASA Astrophysics Data System (ADS)

    Ghanei, Amir; Soltanian-Zadeh, Hamid; Elisevich, Kost; Fessler, Jeffrey A.

    2001-07-01

    We have developed a knowledge-based deformable surface for segmentation of medical images. This work has been done in the context of segmentation of hippocampus from brain MRI, due to its challenge and clinical importance. The model has a polyhedral discrete structure and is initialized automatically by analyzing brain MRI sliced by slice, and finding few landmark features at each slice using an expert system. The expert system decides on the presence of the hippocampus and its general location in each slice. The landmarks found are connected together by a triangulation method, to generate a closed initial surface. The surface deforms under defined internal and external force terms thereafter, to generate an accurate and reproducible boundary for the hippocampus. The anterior and posterior (AP) limits of the hippocampus is estimated by automatic analysis of the location of brain stem, and some of the features extracted in the initialization process. These data are combined together with a priori knowledge using Bayes method to estimate a probability density function (pdf) for the length of the structure in sagittal direction. The hippocampus AP limits are found by optimizing this pdf. The model is tested on real clinical data and the results show very good model performance.

  18. Hyperpolarized helium-3 mouse lung MRI: Studies of lung structure and function

    NASA Astrophysics Data System (ADS)

    Dugas, Joseph Paul

    Hyperpolarized 3He magnetic resonance imaging (MRI) of human and animal lungs has displayed promising and useful applications to studies of lung structure and function in both healthy and diseased lungs. Hyperpolarized 3He MRI allows the visualization of gas in the gas-exchange spaces of the lungs (as opposed to tissue) and has proven especially effective in studying diseases that are characterized by ventilation defects, such as emphysema. In particular, in-vivo measurements of the 3He apparent diffusion coefficient (ADC) can quantify lung structure by measuring its restrictive effects on the motion of 3He spins. This allows for detection and longitudinal tracking of changes in micro-architecture that result from disease destruction of alveolar walls. Due, in part, to the difficulties inherent in administering and imaging hyperpolarized 3He within the small (0.5 cc volume) mouse lung, applications of hyperpolarized 3He MRI techniques to laboratory mice are scarce. We have been able to implement and improve the techniques of hyperpolarized 3He mouse lung MRI and subsequently apply them to studies of several mouse models of disease, including elastase-induced emphysema, smoking-induced emphysema, and lung cancer. Here we detail the design, development, and implementation of a versatile, electronically-controlled, small animal ventilator that is capable of delivering tiny volumes of hyperpolarized 3He, mixed with oxygen, to the mouse and is also compatible with both the easily depolarized 3He gas and the highly magnetic environment within and around an imaging magnet. Also described are NM techniques developed to improve the signal-to-noise ratio of our images and effectively utilize the gas hyperpolarization. Applications of these technologies and techniques to small animal models of disease are presented wherein we have measured up to a 35% increase in 3He ADC in mice with elastase-induced emphysema as compared to healthy mice. We also demonstrate the potential

  19. Head MRI

    MedlinePlus

    ... the head; MRI - cranial; NMR - cranial; Cranial MRI; Brain MRI; MRI - brain; MRI - head ... the test, tell your provider if you have: Brain aneurysm clips An artificial heart valves Heart defibrillator ...

  20. Visualization and quantification of whole rat heart laminar structure using high-spatial resolution contrast-enhanced MRI

    PubMed Central

    Benoist, David; Benson, Alan P.; White, Ed; Tanner, Steven F.; Holden, Arun V.; Dobrzynski, Halina; Bernus, Olivier; Radjenovic, Aleksandra

    2012-01-01

    It has been shown by histology that cardiac myocytes are organized into laminae and this structure is important in function, both influencing the spread of electrical activation and enabling myocardial thickening in systole by laminar sliding. We have carried out high-spatial resolution three-dimensional MRI of the ventricular myolaminae of the entire volume of the isolated rat heart after contrast perfusion [dimeglumine gadopentate (Gd-DTPA)]. Four ex vivo rat hearts were perfused with Gd-DTPA and fixative and high-spatial resolution MRI was performed on a 9.4T MRI system. After MRI, cryosectioning followed by histology was performed. Images from MRI and histology were aligned, described, and quantitatively compared. In the three-dimensional MR images we directly show the presence of laminae and demonstrate that these are highly branching and are absent from much of the subepicardium. We visualized these MRI volumes to demonstrate laminar architecture and quantitatively demonstrated that the structural features observed are similar to those imaged in histology. We showed qualitatively and quantitatively that laminar architecture is similar in the four hearts. MRI can be used to image the laminar architecture of ex vivo hearts in three dimensions, and the images produced are qualitatively and quantitatively comparable with histology. We have demonstrated in the rat that: 1) laminar architecture is consistent between hearts; 2) myolaminae are absent from much of the subepicardium; and 3) although localized orthotropy is present throughout the myocardium, tracked myolaminae are branching structures and do not have a discrete identity. PMID:22021329

  1. Susceptibility-weighted MRI of extrapyramidal brain structures in Parkinsonian disorders

    PubMed Central

    Schneider, Eva; Ng, Kia-Min; Yeoh, Chooi-Sum; Rumpel, Helmut; Fook-Chong, Stephanie; Li, Hui-Hua; Tan, Eng-King; Chan, Ling-Ling

    2016-01-01

    Abstract Susceptibility-weighted MRI (SWI) is sensitive to T2∗ effects and mineralization. We investigated differences in the extrapyramidal brain structures on SWI between Parkinson disease (PD) and postural instability gait disorder (PIGD) patients and correlated the SWI values with the degree of gait dysfunction. Forty patients diagnosed with PD and PIGD underwent 3 Tesla magnetic resonance imaging (MRI) brain study. An SWI sequence (TE/TR/FA 20/33/15) was used. Ten regions of interest were placed in the midbrain and basal ganglia by 2 independent raters blinded to subject data and quantitatively evaluated. The inter-rater reliability between the raters was excellent (interclass correlation coefficient >0.8). The SWI intensity values in all regions were on average lower in PIGD than in PD patients, with the lowest results found in globus pallidus. Multivariate analysis showed a lower SWI hypointensity in the putamen and globus pallidus in PIGD compared with PD patients, with a similar trend for the other basal ganglia nuclei. Pearson correlation analysis showed a statistically significant positive correlation between SWI putaminal hypointensity and the Tinetti total score (r = 0.39, P = 0.01) in both PD and PIGD. SWI putaminal hypointensity may be a useful imaging marker in prospective evaluation for clinical progression for Parkinsonian disorders. PMID:27367979

  2. Diagnostic classification of specific phobia subtypes using structural MRI data: a machine-learning approach.

    PubMed

    Lueken, Ulrike; Hilbert, Kevin; Wittchen, Hans-Ulrich; Reif, Andreas; Hahn, Tim

    2015-01-01

    While neuroimaging research has advanced our knowledge about fear circuitry dysfunctions in anxiety disorders, findings based on diagnostic groups do not translate into diagnostic value for the individual patient. Machine-learning generates predictive information that can be used for single subject classification. We applied Gaussian process classifiers to a sample of patients with specific phobia as a model disorder for pathological forms of anxiety to test for classification based on structural MRI data. Gray (GM) and white matter (WM) volumetric data were analyzed in 33 snake phobics (SP; animal subtype), 26 dental phobics (DP; blood-injection-injury subtype) and 37 healthy controls (HC). Results showed good accuracy rates for GM and WM data in predicting phobia subtypes (GM: 62 % phobics vs. HC, 86 % DP vs. HC, 89 % SP vs. HC, 89 % DP vs. SP; WM: 88 % phobics vs. HC, 89 % DP vs. HC, 79 % SP vs. HC, 79 % DP vs. HC). Regarding GM, classification improved when considering the subtype compared to overall phobia status. The discriminatory brain pattern was not solely based on fear circuitry structures but included widespread cortico-subcortical networks. Results demonstrate that multivariate pattern recognition represents a promising approach for the development of neuroimaging-based diagnostic markers that could support clinical decisions. Regarding the increasing number of fMRI studies on anxiety disorders, researchers are encouraged to use functional and structural data not only for studying phenotype characteristics on a group level, but also to evaluate their incremental value for diagnostic or prognostic purposes.

  3. Longitudinal alterations to brain function, structure, and cognitive performance in healthy older adults: A fMRI-DTI study.

    PubMed

    Hakun, Jonathan G; Zhu, Zude; Brown, Christopher A; Johnson, Nathan F; Gold, Brian T

    2015-05-01

    Cross-sectional research has shown that older adults tend to have different frontal cortex activation patterns, poorer brain structure, and lower task performance than younger adults. However, relationships between longitudinal changes in brain function, brain structure, and cognitive performance in older adults are less well understood. Here we present the results of a longitudinal, combined fMRI-DTI study in cognitive normal (CN) older adults. A two time-point study was conducted in which participants completed a task switching paradigm while fMRI data was collected and underwent the identical scanning protocol an average of 3.3 years later (SD=2 months). We observed longitudinal fMRI activation increases in bilateral regions of lateral frontal cortex at time point 2. These fMRI activation increases were associated with longitudinal declines in WM microstructure in a portion of the corpus callosum connecting the increasingly recruited frontal regions. In addition, the fMRI activation increase in the left VLPFC was associated with longitudinal increases in response latencies. Taken together, our results suggest that local frontal activation increases in CN older adults may in part reflect a response to reduced inter-hemispheric signaling mechanisms.

  4. Longitudinal Alterations to Brain Function, Structure, and Cognitive Performance in Healthy Older Adults: a fMRI-DTI study

    PubMed Central

    Hakun, Jonathan G.; Zhu, Zude; Brown, Christopher A.; Johnson, Nathan F.; Gold, Brian T.

    2015-01-01

    Cross-sectional research has shown that older adults tend to have different frontal cortex activation patterns, poorer brain structure, and lower task performance than younger adults. However, relationships between longitudinal changes in brain function, brain structure, and cognitive performance in older adults are less well understood. Here we present the results of a longitudinal, combined fMRI-DTI study in cognitive normal (CN) older adults. A two time-point study was conducted in which participants completed a task switching paradigm while fMRI data was collected and underwent the identical scanning protocol an average of 3.3 years later (SD = 2 months). We observed longitudinal fMRI activation increases in bilateral regions of lateral frontal cortex at time point 2. These fMRI activation increases were associated with longitudinal declines in WM microstructure in a portion of the corpus callosum connecting the increasingly recruited frontal regions. In addition, the fMRI activation increase in the left VLPFC was associated with longitudinal increases in response latencies. Taken together, our results suggest that local frontal activation increases in CN older adults may in part reflect a response to reduced inter-hemispheric signaling mechanisms. PMID:25862416

  5. Structural MRI correlates of cognitive impairment in patients with multiple sclerosis: A Multicenter Study.

    PubMed

    Preziosa, Paolo; Rocca, Maria A; Pagani, Elisabetta; Stromillo, Maria Laura; Enzinger, Christian; Gallo, Antonio; Hulst, Hanneke E; Atzori, Matteo; Pareto, Deborah; Riccitelli, Gianna C; Copetti, Massimiliano; De Stefano, Nicola; Fazekas, Franz; Bisecco, Alvino; Barkhof, Frederik; Yousry, Tarek A; Arévalo, Maria J; Filippi, Massimo

    2016-04-01

    In a multicenter setting, we applied voxel-based methods to different structural MR imaging modalities to define the relative contributions of focal lesions, normal-appearing white matter (NAWM), and gray matter (GM) damage and their regional distribution to cognitive deficits as well as impairment of specific cognitive domains in multiple sclerosis (MS) patients. Approval of the institutional review boards was obtained, together with written informed consent from all participants. Standardized neuropsychological assessment and conventional, diffusion tensor and volumetric brain MRI sequences were collected from 61 relapsing-remitting MS patients and 61 healthy controls (HC) from seven centers. Patients with ≥2 abnormal tests were considered cognitively impaired (CI). The distribution of focal lesions, GM and WM atrophy, and microstructural WM damage were assessed using voxel-wise approaches. A random forest analysis identified the best imaging predictors of global cognitive impairment and deficits of specific cognitive domains. Twenty-three (38%) MS patients were CI. Compared with cognitively preserved (CP), CI MS patients had GM atrophy of the left thalamus, right hippocampus and parietal regions. They also showed atrophy of several WM tracts, mainly located in posterior brain regions and widespread WM diffusivity abnormalities. WM diffusivity abnormalities in cognitive-relevant WM tracts followed by atrophy of cognitive-relevant GM regions explained global cognitive impairment. Variable patterns of NAWM and GM damage were associated with deficits in selected cognitive domains. Structural, multiparametric, voxel-wise MRI approaches are feasible in a multicenter setting. The combination of different imaging modalities is needed to assess and monitor cognitive impairment in MS. PMID:26833969

  6. Structural MRI correlates of cognitive impairment in patients with multiple sclerosis: A Multicenter Study.

    PubMed

    Preziosa, Paolo; Rocca, Maria A; Pagani, Elisabetta; Stromillo, Maria Laura; Enzinger, Christian; Gallo, Antonio; Hulst, Hanneke E; Atzori, Matteo; Pareto, Deborah; Riccitelli, Gianna C; Copetti, Massimiliano; De Stefano, Nicola; Fazekas, Franz; Bisecco, Alvino; Barkhof, Frederik; Yousry, Tarek A; Arévalo, Maria J; Filippi, Massimo

    2016-04-01

    In a multicenter setting, we applied voxel-based methods to different structural MR imaging modalities to define the relative contributions of focal lesions, normal-appearing white matter (NAWM), and gray matter (GM) damage and their regional distribution to cognitive deficits as well as impairment of specific cognitive domains in multiple sclerosis (MS) patients. Approval of the institutional review boards was obtained, together with written informed consent from all participants. Standardized neuropsychological assessment and conventional, diffusion tensor and volumetric brain MRI sequences were collected from 61 relapsing-remitting MS patients and 61 healthy controls (HC) from seven centers. Patients with ≥2 abnormal tests were considered cognitively impaired (CI). The distribution of focal lesions, GM and WM atrophy, and microstructural WM damage were assessed using voxel-wise approaches. A random forest analysis identified the best imaging predictors of global cognitive impairment and deficits of specific cognitive domains. Twenty-three (38%) MS patients were CI. Compared with cognitively preserved (CP), CI MS patients had GM atrophy of the left thalamus, right hippocampus and parietal regions. They also showed atrophy of several WM tracts, mainly located in posterior brain regions and widespread WM diffusivity abnormalities. WM diffusivity abnormalities in cognitive-relevant WM tracts followed by atrophy of cognitive-relevant GM regions explained global cognitive impairment. Variable patterns of NAWM and GM damage were associated with deficits in selected cognitive domains. Structural, multiparametric, voxel-wise MRI approaches are feasible in a multicenter setting. The combination of different imaging modalities is needed to assess and monitor cognitive impairment in MS.

  7. Advances in functional and structural imaging of the human lung using proton MRI.

    PubMed

    Miller, G Wilson; Mugler, John P; Sá, Rui C; Altes, Talissa A; Prisk, G Kim; Hopkins, Susan R

    2014-12-01

    The field of proton lung MRI is advancing on a variety of fronts. In the realm of functional imaging, it is now possible to use arterial spin labeling (ASL) and oxygen-enhanced imaging techniques to quantify regional perfusion and ventilation, respectively, in standard units of measurement. By combining these techniques into a single scan, it is also possible to quantify the local ventilation-perfusion ratio, which is the most important determinant of gas-exchange efficiency in the lung. To demonstrate potential for accurate and meaningful measurements of lung function, this technique was used to study gravitational gradients of ventilation, perfusion, and ventilation-perfusion ratio in healthy subjects, yielding quantitative results consistent with expected regional variations. Such techniques can also be applied in the time domain, providing new tools for studying temporal dynamics of lung function. Temporal ASL measurements showed increased spatial-temporal heterogeneity of pulmonary blood flow in healthy subjects exposed to hypoxia, suggesting sensitivity to active control mechanisms such as hypoxic pulmonary vasoconstriction, and illustrating that to fully examine the factors that govern lung function it is necessary to consider temporal as well as spatial variability. Further development to increase spatial coverage and improve robustness would enhance the clinical applicability of these new functional imaging tools. In the realm of structural imaging, pulse sequence techniques such as ultrashort echo-time radial k-space acquisition, ultrafast steady-state free precession, and imaging-based diaphragm triggering can be combined to overcome the significant challenges associated with proton MRI in the lung, enabling high-quality three-dimensional imaging of the whole lung in a clinically reasonable scan time. Images of healthy and cystic fibrosis subjects using these techniques demonstrate substantial promise for non-contrast pulmonary angiography and detailed

  8. Structural hippocampal network alterations during healthy aging: a multi-modal MRI study

    PubMed Central

    Pelletier, Amandine; Periot, Olivier; Dilharreguy, Bixente; Hiba, Bassem; Bordessoules, Martine; Pérès, Karine; Amieva, Hélène; Dartigues, Jean-François; Allard, Michèle; Catheline, Gwénaëlle

    2013-01-01

    While hippocampal atrophy has been described during healthy aging, few studies have examined its relationship with the integrity of White Matter (WM) connecting tracts of the limbic system. This investigation examined WM structural damage specifically related to hippocampal atrophy in healthy aging subjects (n = 129), using morphological MRI to assess hippocampal volume and Diffusion Tensor Imaging (DTI) to assess WM integrity. Subjects with Mild Cognitive Impairment (MCI) or dementia were excluded from the analysis. In our sample, increasing age was significantly associated with reduced hippocampal volume and reduced Fractional Anisotropy (FA) at the level of the fornix and the cingulum bundle. The findings also demonstrate that hippocampal atrophy was specifically associated with reduced FA of the fornix bundle, but it was not related to alteration of the cingulum bundle. Our results indicate that the relationship between hippocampal atrophy and fornix FA values is not due to an independent effect of age on both structures. A recursive regression procedure was applied to evaluate sequential relationships between the alterations of these two brain structures. When both hippocampal atrophy and fornix FA values were included in the same model to predict age, fornix FA values remained significant whereas hippocampal atrophy was no longer significantly associated with age. According to this latter finding, hippocampal atrophy in healthy aging could be mediated by a loss of fornix connections. Structural alterations of this part of the limbic system, which have been associated with neurodegeneration in Alzheimer's disease, result at least in part from the aging process. PMID:24367331

  9. DT-MRI measurement of myolaminar structure: accuracy and sensitivity to time post-fixation, b-value and number of directions.

    PubMed

    Gilbert, Stephen H; Smaill, Bruce H; Walton, Richard D; Trew, Mark L; Bernus, Olivier

    2013-01-01

    DT-MRI has been widely used to quantify myocardial fiber and laminar orientations. These structural orientations influence both the spread of excitation and the reorganization of the myocardium during contraction and are altered in disease states. Studies have sought to validate DT-MRI but questions remain about the accuracy of the method and its sensitivity to the time post-fixation and imaging parameters, including b-value, number of diffusion directions and image voxel size. The advent of high-spatial resolution ex vivo MRI and structure tensor (ST) analysis provides a means of direct validation of DT-MRI and assessment of sensitivity to the b-value, the number of diffusion directions and the image voxel size. We find that, with the fixation method we used, structure does not change with time (up to 72 hours). We show that DT-MRI and ST/HR-MRI are markedly similar measures of fiber orientation but DT-MRI and ST are much less similar measures of laminar orientation. DT-MRI performance is not sensitive to the number of directions, with similar structural orientations measured with 6 or 12 directions. Likewise, DT-MRI performance is generally insensitive to b-value, but laminar measurement is moderately more accurate at b = 500 than for higher b-values.

  10. Structural changes of the carpal tunnel, median nerve and flexor tendons in MRI before and after endoscopic carpal tunnel release.

    PubMed

    Momose, Toshimitsu; Uchiyama, Shigeharu; Kobayashi, Seneki; Nakagawa, Hiroyuki; Kato, Hiroyuki

    2014-01-01

    The purpose of this study is to investigate the structural changes of the carpal tunnel, median nerve, and flexor tendons in magnetic resonance imaging (MRI) before and after endoscopic carpal tunnel release (ECTR). We studied 36 hands undergoing ECTR. In MRI, the cross-sectional area of the carpal tunnel and the median nerve at the hamate and the pisiform levels were measured. The distance from the volar side of carpal bone to the median nerve or tendons and the volar displacement were measured. In post-operative MRI, the transverse carpal ligament could not be well delineated and the carpal tunnel was significantly enlarged both at the hamate and pisiform levels. The median nerve was enlarged at the hamate level. The median nerve and flexor tendons significantly moved to the volar side. The volar displacement of the median nerve and flexor digitorum superficialis in the long and ring fingers was greater than the other tendons.

  11. Structural and Functional MRI Differences in Master Sommeliers: A Pilot Study on Expertise in the Brain

    PubMed Central

    Banks, Sarah J.; Sreenivasan, Karthik R.; Weintraub, David M.; Baldock, Deanna; Noback, Michael; Pierce, Meghan E.; Frasnelli, Johannes; James, Jay; Beall, Erik; Zhuang, Xiaowei; Cordes, Dietmar; Leger, Gabriel C.

    2016-01-01

    Our experiences, even as adults, shape our brains. Regional differences have been found in experts, with the regions associated with their particular skill-set. Functional differences have also been noted in brain activation patterns in some experts. This study uses multimodal techniques to assess structural and functional patterns that differ between experts and non-experts. Sommeliers are experts in wine and thus in olfaction. We assessed differences in Master Sommeliers’ brains, compared with controls, in structure and also in functional response to olfactory and visual judgment tasks. MRI data were analyzed using voxel-based morphometry as well as automated parcellation to assess structural properties, and group differences between tasks were calculated. Results indicate enhanced volume in the right insula and entorhinal cortex, with the cortical thickness of the entorhinal correlating with experience. There were regional activation differences in a large area involving the right olfactory and memory regions, with heightened activation specifically for sommeliers during an olfactory task. Our results indicate that sommeliers’ brains show specialization in the expected regions of the olfactory and memory networks, and also in regions important in integration of internal sensory stimuli and external cues. Overall, these differences suggest that specialized expertise and training might result in enhancements in the brain well into adulthood. This is particularly important given the regions involved, which are the first to be impacted by many neurodegenerative diseases.

  12. Structural and Functional MRI Differences in Master Sommeliers: A Pilot Study on Expertise in the Brain

    PubMed Central

    Banks, Sarah J.; Sreenivasan, Karthik R.; Weintraub, David M.; Baldock, Deanna; Noback, Michael; Pierce, Meghan E.; Frasnelli, Johannes; James, Jay; Beall, Erik; Zhuang, Xiaowei; Cordes, Dietmar; Leger, Gabriel C.

    2016-01-01

    Our experiences, even as adults, shape our brains. Regional differences have been found in experts, with the regions associated with their particular skill-set. Functional differences have also been noted in brain activation patterns in some experts. This study uses multimodal techniques to assess structural and functional patterns that differ between experts and non-experts. Sommeliers are experts in wine and thus in olfaction. We assessed differences in Master Sommeliers’ brains, compared with controls, in structure and also in functional response to olfactory and visual judgment tasks. MRI data were analyzed using voxel-based morphometry as well as automated parcellation to assess structural properties, and group differences between tasks were calculated. Results indicate enhanced volume in the right insula and entorhinal cortex, with the cortical thickness of the entorhinal correlating with experience. There were regional activation differences in a large area involving the right olfactory and memory regions, with heightened activation specifically for sommeliers during an olfactory task. Our results indicate that sommeliers’ brains show specialization in the expected regions of the olfactory and memory networks, and also in regions important in integration of internal sensory stimuli and external cues. Overall, these differences suggest that specialized expertise and training might result in enhancements in the brain well into adulthood. This is particularly important given the regions involved, which are the first to be impacted by many neurodegenerative diseases. PMID:27597821

  13. Structural and Functional MRI Differences in Master Sommeliers: A Pilot Study on Expertise in the Brain.

    PubMed

    Banks, Sarah J; Sreenivasan, Karthik R; Weintraub, David M; Baldock, Deanna; Noback, Michael; Pierce, Meghan E; Frasnelli, Johannes; James, Jay; Beall, Erik; Zhuang, Xiaowei; Cordes, Dietmar; Leger, Gabriel C

    2016-01-01

    Our experiences, even as adults, shape our brains. Regional differences have been found in experts, with the regions associated with their particular skill-set. Functional differences have also been noted in brain activation patterns in some experts. This study uses multimodal techniques to assess structural and functional patterns that differ between experts and non-experts. Sommeliers are experts in wine and thus in olfaction. We assessed differences in Master Sommeliers' brains, compared with controls, in structure and also in functional response to olfactory and visual judgment tasks. MRI data were analyzed using voxel-based morphometry as well as automated parcellation to assess structural properties, and group differences between tasks were calculated. Results indicate enhanced volume in the right insula and entorhinal cortex, with the cortical thickness of the entorhinal correlating with experience. There were regional activation differences in a large area involving the right olfactory and memory regions, with heightened activation specifically for sommeliers during an olfactory task. Our results indicate that sommeliers' brains show specialization in the expected regions of the olfactory and memory networks, and also in regions important in integration of internal sensory stimuli and external cues. Overall, these differences suggest that specialized expertise and training might result in enhancements in the brain well into adulthood. This is particularly important given the regions involved, which are the first to be impacted by many neurodegenerative diseases. PMID:27597821

  14. Identifying Individuals at High Risk of Psychosis: Predictive Utility of Support Vector Machine using Structural and Functional MRI Data

    PubMed Central

    Valli, Isabel; Marquand, Andre F.; Mechelli, Andrea; Raffin, Marie; Allen, Paul; Seal, Marc L.; McGuire, Philip

    2016-01-01

    The identification of individuals at high risk of developing psychosis is entirely based on clinical assessment, associated with limited predictive potential. There is, therefore, increasing interest in the development of biological markers that could be used in clinical practice for this purpose. We studied 25 individuals with an at-risk mental state for psychosis and 25 healthy controls using structural MRI, and functional MRI in conjunction with a verbal memory task. Data were analyzed using a standard univariate analysis, and with support vector machine (SVM), a multivariate pattern recognition technique that enables statistical inferences to be made at the level of the individual, yielding results with high translational potential. The application of SVM to structural MRI data permitted the identification of individuals at high risk of psychosis with a sensitivity of 68% and a specificity of 76%, resulting in an accuracy of 72% (p < 0.001). Univariate volumetric between-group differences did not reach statistical significance. By contrast, the univariate fMRI analysis identified between-group differences (p < 0.05 corrected), while the application of SVM to the same data did not. Since SVM is well suited at identifying the pattern of abnormality that distinguishes two groups, whereas univariate methods are more likely to identify regions that individually are most different between two groups, our results suggest the presence of focal functional abnormalities in the context of a diffuse pattern of structural abnormalities in individuals at high clinical risk of psychosis. PMID:27092086

  15. Functional and structural abnormalities associated with empathy in patients with schizophrenia: An fMRI and VBM study.

    PubMed

    Singh, Sadhana; Modi, Shilpi; Goyal, Satnam; Kaur, Prabhjot; Singh, Namita; Bhatia, Triptish; Deshpande, Smita N; Khushu, Subash

    2015-06-01

    Empathy deficit is a core feature of schizophrenia which may lead to social dysfunction. The present study was carried out to investigate functional and structural abnormalities associated with empathy in patients with schizophrenia using functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM). A sample of 14 schizophrenia patients and 14 healthy control subjects matched for age, sex and education were examined with structural highresolution T1-weighted MRI; fMRI images were obtained during empathy task in the same session. The analysis was carried out using SPM8 software. On behavioural assessment, schizophrenic patients (83.00+-29.04) showed less scores for sadness compared to healthy controls (128.70+-22.26) (p less than 0.001). fMRI results also showed reduced clusters of activation in the bilateral fusiform gyrus, left lingual gyrus, left middle and inferior occipital gyrus in schizophrenic subjects as compared to controls during empathy task. In the same brain areas, VBM results also showed reduced grey and white matter volumes. The present study provides an evidence for an association between structural alterations and disturbed functional brain activation during empathy task in persons affected with schizophrenia. These findings suggest a biological basis for social cognition deficits in schizophrenics. PMID:25963262

  16. Identifying Individuals at High Risk of Psychosis: Predictive Utility of Support Vector Machine using Structural and Functional MRI Data.

    PubMed

    Valli, Isabel; Marquand, Andre F; Mechelli, Andrea; Raffin, Marie; Allen, Paul; Seal, Marc L; McGuire, Philip

    2016-01-01

    The identification of individuals at high risk of developing psychosis is entirely based on clinical assessment, associated with limited predictive potential. There is, therefore, increasing interest in the development of biological markers that could be used in clinical practice for this purpose. We studied 25 individuals with an at-risk mental state for psychosis and 25 healthy controls using structural MRI, and functional MRI in conjunction with a verbal memory task. Data were analyzed using a standard univariate analysis, and with support vector machine (SVM), a multivariate pattern recognition technique that enables statistical inferences to be made at the level of the individual, yielding results with high translational potential. The application of SVM to structural MRI data permitted the identification of individuals at high risk of psychosis with a sensitivity of 68% and a specificity of 76%, resulting in an accuracy of 72% (p < 0.001). Univariate volumetric between-group differences did not reach statistical significance. By contrast, the univariate fMRI analysis identified between-group differences (p < 0.05 corrected), while the application of SVM to the same data did not. Since SVM is well suited at identifying the pattern of abnormality that distinguishes two groups, whereas univariate methods are more likely to identify regions that individually are most different between two groups, our results suggest the presence of focal functional abnormalities in the context of a diffuse pattern of structural abnormalities in individuals at high clinical risk of psychosis. PMID:27092086

  17. Functional and structural abnormalities associated with empathy in patients with schizophrenia: An fMRI and VBM study

    PubMed Central

    Singh, Sadhana; Modi, Shilpi; Goyal, Satnam; Kaur, Prabhjot; Singh, Namita; Bhatia, Triptish; Deshpande, Smita N; Khushu, Subash

    2016-01-01

    Empathy deficit is a core feature of schizophrenia which may lead to social dysfunction. The present study was carried out to investigate functional and structural abnormalities associated with empathy in patients with schizophrenia using functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM). A sample of 14 schizophrenia patients and 14 healthy control subjects matched for age, sex and education were examined with structural high-resolution T1-weighted MRI; fMRI images were obtained during empathy task in the same session. The analysis was carried out using SPM8 software. On behavioural assessment, schizophrenic patients (83.00±29.04) showed less scores for sadness compared to healthy controls (128.70±22.26) (p<0.001). fMRI results also showed reduced clusters of activation in the bilateral fusiform gyrus, left lingual gyrus, left middle and inferior occipital gyrus in schizophrenic subjects as compared to controls during empathy task. In the same brain areas, VBM results also showed reduced grey and white matter volumes. The present study provides an evidence for an association between structural alterations and disturbed functional brain activation during empathy task in persons affected with schizophrenia. These findings suggest a biological basis for social cognition deficits in schizophrenics. PMID:25963262

  18. Functional and structural abnormalities associated with empathy in patients with schizophrenia: An fMRI and VBM study.

    PubMed

    Singh, Sadhana; Modi, Shilpi; Goyal, Satnam; Kaur, Prabhjot; Singh, Namita; Bhatia, Triptish; Deshpande, Smita N; Khushu, Subash

    2015-06-01

    Empathy deficit is a core feature of schizophrenia which may lead to social dysfunction. The present study was carried out to investigate functional and structural abnormalities associated with empathy in patients with schizophrenia using functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM). A sample of 14 schizophrenia patients and 14 healthy control subjects matched for age, sex and education were examined with structural highresolution T1-weighted MRI; fMRI images were obtained during empathy task in the same session. The analysis was carried out using SPM8 software. On behavioural assessment, schizophrenic patients (83.00+-29.04) showed less scores for sadness compared to healthy controls (128.70+-22.26) (p less than 0.001). fMRI results also showed reduced clusters of activation in the bilateral fusiform gyrus, left lingual gyrus, left middle and inferior occipital gyrus in schizophrenic subjects as compared to controls during empathy task. In the same brain areas, VBM results also showed reduced grey and white matter volumes. The present study provides an evidence for an association between structural alterations and disturbed functional brain activation during empathy task in persons affected with schizophrenia. These findings suggest a biological basis for social cognition deficits in schizophrenics.

  19. Ultrasound vs. MRI in the assessment of rotator cuff structure prior to shoulder arthroplasty

    PubMed Central

    Fischer, Christian Alexander; Weber, Marc-André; Neubecker, Clément; Bruckner, Thomas; Tanner, Michael; Zeifang, Felix

    2015-01-01

    Background/Aims We compared the accuracy of US to 3 T Tesla MRI for the detection of rotator cuff and long biceps tendon pathologies before joint replacement. Methods 45 patients were prospectively included. Results For the supraspinatus tendon, the accuracy of US when using MRI as reference was 91.1%. For the infraspinatus tendon, the accuracy with MRI as reference was 84.4%. The subscapularis tendon was consistently assessed by US and MRI in 35/45 patients (accuracy 77.8%). For the long biceps tendon the accuracy was 86.7%. Conclusion US detection of rotator cuff and biceps tendon integrity is comparable to MRI and should be preferred in revision cases. PMID:25829757

  20. Discriminative Analysis of Migraine without Aura: Using Functional and Structural MRI with a Multi-Feature Classification Approach

    PubMed Central

    Zhang, Junran; He, Ling; Huang, Jiangtao; Zhang, Jiang; Huang, Hua; Gong, Qiyong

    2016-01-01

    Magnetic resonance imaging (MRI) is by nature a multi-modality technique that provides complementary information about different aspects of diseases. So far no attempts have been reported to assess the potential of multi-modal MRI in discriminating individuals with and without migraine, so in this study, we proposed a classification approach to examine whether or not the integration of multiple MRI features could improve the classification performance between migraine patients without aura (MWoA) and healthy controls. Twenty-one MWoA patients and 28 healthy controls participated in this study. Resting-state functional MRI data was acquired to derive three functional measures: the amplitude of low-frequency fluctuations, regional homogeneity and regional functional correlation strength; and structural MRI data was obtained to measure the regional gray matter volume. For each measure, the values of 116 pre-defined regions of interest were extracted as classification features. Features were first selected and combined by a multi-kernel strategy; then a support vector machine classifier was trained to distinguish the subjects at individual level. The performance of the classifier was evaluated using a leave-one-out cross-validation method, and the final classification accuracy obtained was 83.67% (with a sensitivity of 92.86% and a specificity of 71.43%). The anterior cingulate cortex, prefrontal cortex, orbitofrontal cortex and the insula contributed the most discriminative features. In general, our proposed framework shows a promising classification capability for MWoA by integrating information from multiple MRI features. PMID:27690138

  1. Recent applications of UHF-MRI in the study of human brain function and structure: a review.

    PubMed

    van der Zwaag, Wietske; Schäfer, Andreas; Marques, José P; Turner, Robert; Trampel, Robert

    2016-09-01

    The increased availability of ultra-high-field (UHF) MRI has led to its application in a wide range of neuroimaging studies, which are showing promise in transforming fundamental approaches to human neuroscience. This review presents recent work on structural and functional brain imaging, at 7 T and higher field strengths. After a short outline of the effects of high field strength on MR images, the rapidly expanding literature on UHF applications of blood-oxygenation-level-dependent-based functional MRI is reviewed. Structural imaging is then discussed, divided into sections on imaging weighted by relaxation time, including quantitative relaxation time mapping, phase imaging and quantitative susceptibility mapping, angiography, diffusion-weighted imaging, and finally magnetization-transfer imaging. The final section discusses studies using the high spatial resolution available at UHF to identify explicit links between structure and function. Copyright © 2015 John Wiley & Sons, Ltd.

  2. Surface-Based fMRI-Driven Diffusion Tractography in the Presence of Significant Brain Pathology: A Study Linking Structure and Function in Cerebral Palsy

    PubMed Central

    Cunnington, Ross; Boyd, Roslyn N.; Rose, Stephen E.

    2016-01-01

    Diffusion MRI (dMRI) tractography analyses are difficult to perform in the presence of brain pathology. Automated methods that rely on cortical parcellation for structural connectivity studies often fail, while manually defining regions is extremely time consuming and can introduce human error. Both methods also make assumptions about structure-function relationships that may not hold after cortical reorganisation. Seeding tractography with functional-MRI (fMRI) activation is an emerging method that reduces these confounds, but inherent smoothing of fMRI signal may result in the inclusion of irrelevant pathways. This paper describes a novel fMRI-seeded dMRI-analysis pipeline based on surface-meshes that reduces these issues and utilises machine-learning to generate task specific white matter pathways, minimising the requirement for manually-drawn ROIs. We directly compared this new strategy to a standard voxelwise fMRI-dMRI approach, by investigating correlations between clinical scores and dMRI metrics of thalamocortical and corticomotor tracts in 31 children with unilateral cerebral palsy. The surface-based approach successfully processed more participants (87%) than the voxel-based approach (65%), and provided significantly more-coherent tractography. Significant correlations between dMRI metrics and five clinical scores of function were found for the more superior regions of these tracts. These significant correlations were stronger and more frequently found with the surface-based method (15/20 investigated were significant; R2 = 0.43–0.73) than the voxelwise analysis (2 sig. correlations; 0.38 & 0.49). More restricted fMRI signal, better-constrained tractography, and the novel track-classification method all appeared to contribute toward these differences. PMID:27487011

  3. Surface-Based fMRI-Driven Diffusion Tractography in the Presence of Significant Brain Pathology: A Study Linking Structure and Function in Cerebral Palsy.

    PubMed

    Reid, Lee B; Cunnington, Ross; Boyd, Roslyn N; Rose, Stephen E

    2016-01-01

    Diffusion MRI (dMRI) tractography analyses are difficult to perform in the presence of brain pathology. Automated methods that rely on cortical parcellation for structural connectivity studies often fail, while manually defining regions is extremely time consuming and can introduce human error. Both methods also make assumptions about structure-function relationships that may not hold after cortical reorganisation. Seeding tractography with functional-MRI (fMRI) activation is an emerging method that reduces these confounds, but inherent smoothing of fMRI signal may result in the inclusion of irrelevant pathways. This paper describes a novel fMRI-seeded dMRI-analysis pipeline based on surface-meshes that reduces these issues and utilises machine-learning to generate task specific white matter pathways, minimising the requirement for manually-drawn ROIs. We directly compared this new strategy to a standard voxelwise fMRI-dMRI approach, by investigating correlations between clinical scores and dMRI metrics of thalamocortical and corticomotor tracts in 31 children with unilateral cerebral palsy. The surface-based approach successfully processed more participants (87%) than the voxel-based approach (65%), and provided significantly more-coherent tractography. Significant correlations between dMRI metrics and five clinical scores of function were found for the more superior regions of these tracts. These significant correlations were stronger and more frequently found with the surface-based method (15/20 investigated were significant; R2 = 0.43-0.73) than the voxelwise analysis (2 sig. correlations; 0.38 & 0.49). More restricted fMRI signal, better-constrained tractography, and the novel track-classification method all appeared to contribute toward these differences. PMID:27487011

  4. How the brain processes different dimensions of argument structure complexity: Evidence from fMRI

    PubMed Central

    Meltzer-Asscher, Aya; Mack, Jennifer E.; Barbieri, Elena; Thompson, Cynthia K.

    2015-01-01

    Verbs are central to sentence processing, as they encode argument structure (AS) information, i.e., information about the syntax and interpretation of the phrases accompanying them. The behavioral and neural correlates of AS processing have primarily been investigated in sentence-level tasks, requiring both verb processing and verb-argument integration. In the current functional magnetic resonance imaging (fMRI) study, we investigated AS processing using a lexical decision task requiring only verb processing. We examined three aspects of AS complexity: number of thematic roles, number of thematic options, and mapping (non)canonicity (unaccusative vs. unergative and transitive verbs). Increased number of thematic roles elicited greater activation in the left posterior perisylvian regions claimed to support access to stored AS representations. However, the number of thematic options had no neural effects. Further, unaccusative verbs elicited longer response times and increased activation in the left inferior frontal gyrus, reflecting the processing cost of unaccusative verbs and, more generally, supporting the role of the IFG in noncanonical argument mapping. PMID:25658635

  5. Learning Effective Connectivity Network Structure from fMRI Data Based on Artificial Immune Algorithm.

    PubMed

    Ji, Junzhong; Liu, Jinduo; Liang, Peipeng; Zhang, Aidong

    2016-01-01

    Many approaches have been designed to extract brain effective connectivity from functional magnetic resonance imaging (fMRI) data. However, few of them can effectively identify the connectivity network structure due to different defects. In this paper, a new algorithm is developed to infer the effective connectivity between different brain regions by combining artificial immune algorithm (AIA) with the Bayes net method, named as AIAEC. In the proposed algorithm, a brain effective connectivity network is mapped onto an antibody, and four immune operators are employed to perform the optimization process of antibodies, including clonal selection operator, crossover operator, mutation operator and suppression operator, and finally gets an antibody with the highest K2 score as the solution. AIAEC is then tested on Smith's simulated datasets, and the effect of the different factors on AIAEC is evaluated, including the node number, session length, as well as the other potential confounding factors of the blood oxygen level dependent (BOLD) signal. It was revealed that, as contrast to other existing methods, AIAEC got the best performance on the majority of the datasets. It was also found that AIAEC could attain a relative better solution under the influence of many factors, although AIAEC was differently affected by the aforementioned factors. AIAEC is thus demonstrated to be an effective method for detecting the brain effective connectivity. PMID:27045295

  6. Structural alterations in the rat brain and behavioral impairment after status epilepticus: An MRI study.

    PubMed

    Suleymanova, E M; Gulyaev, M V; Abbasova, K R

    2016-02-19

    Temporal lobe epilepsy (TLE) is one of the most common neurologic disorders often associated with behavioral impairments and cognitive deficit. Lithium-pilocarpine model of seizures in rodents reproduces many features of human convulsive status epilepticus (SE) and subsequent TLE. In this study, we have investigated changes in the rat brain after lithium-pilocarpine SE using a high-field MRI system for small animals in early and chronic periods after SE. We have studied the relationship between T2 relaxation time measured in these periods and the development of behavioral exploratory response to novelty and habituation in the open field test. A significant increase in T2 in the hippocampus and associated structures was found 2 days after SE and practically resolved by day seven, while an increase in T2 in the parietal and prefrontal cortex appeared 30 days after SE. High T2 values in the parietal cortex and thalamus on day two after SE were associated with an increased mortality risk. A substantial variability in T2 relaxation time was observed in the hippocampus and amygdala 30 days after SE. Rats survived after SE showed locomotor hyperactivity and disruption of long-term habituation in the open field test carried out 5 weeks after the seizures. Interestingly, T2 in the amygdala 30 days after SE had a strong correlation with hyperactivity in the novel open field. Therefore, the amygdala damage may be an important factor in the development of hyperactivity in the chronic period after SE. PMID:26674057

  7. Learning Effective Connectivity Network Structure from fMRI Data Based on Artificial Immune Algorithm

    PubMed Central

    Ji, Junzhong; Liu, Jinduo; Liang, Peipeng; Zhang, Aidong

    2016-01-01

    Many approaches have been designed to extract brain effective connectivity from functional magnetic resonance imaging (fMRI) data. However, few of them can effectively identify the connectivity network structure due to different defects. In this paper, a new algorithm is developed to infer the effective connectivity between different brain regions by combining artificial immune algorithm (AIA) with the Bayes net method, named as AIAEC. In the proposed algorithm, a brain effective connectivity network is mapped onto an antibody, and four immune operators are employed to perform the optimization process of antibodies, including clonal selection operator, crossover operator, mutation operator and suppression operator, and finally gets an antibody with the highest K2 score as the solution. AIAEC is then tested on Smith’s simulated datasets, and the effect of the different factors on AIAEC is evaluated, including the node number, session length, as well as the other potential confounding factors of the blood oxygen level dependent (BOLD) signal. It was revealed that, as contrast to other existing methods, AIAEC got the best performance on the majority of the datasets. It was also found that AIAEC could attain a relative better solution under the influence of many factors, although AIAEC was differently affected by the aforementioned factors. AIAEC is thus demonstrated to be an effective method for detecting the brain effective connectivity. PMID:27045295

  8. An efficient computational approach to characterize DSC-MRI signals arising from three-dimensional heterogeneous tissue structures.

    PubMed

    Semmineh, Natenael B; Xu, Junzhong; Boxerman, Jerrold L; Delaney, Gary W; Cleary, Paul W; Gore, John C; Quarles, C Chad

    2014-01-01

    The systematic investigation of susceptibility-induced contrast in MRI is important to better interpret the influence of microvascular and microcellular morphology on DSC-MRI derived perfusion data. Recently, a novel computational approach called the Finite Perturber Method (FPM), which enables the study of susceptibility-induced contrast in MRI arising from arbitrary microvascular morphologies in 3D has been developed. However, the FPM has lower efficiency in simulating water diffusion especially for complex tissues. In this work, an improved computational approach that combines the FPM with a matrix-based finite difference method (FDM), which we call the Finite Perturber the Finite Difference Method (FPFDM), has been developed in order to efficiently investigate the influence of vascular and extravascular morphological features on susceptibility-induced transverse relaxation. The current work provides a framework for better interpreting how DSC-MRI data depend on various phenomena, including contrast agent leakage in cancerous tissues and water diffusion rates. In addition, we illustrate using simulated and micro-CT extracted tissue structures the improved FPFDM along with its potential applications and limitations.

  9. Manually segmented template library for 8-year-old pediatric brain MRI data with 16 subcortical structures

    PubMed Central

    Garg, Amanmeet; Wong, Darren; Popuri, Karteek; Poskitt, Kenneth J.; Fitzpatrick, Kevin; Bjornson, Bruce; Grunau, Ruth E.; Beg, Mirza Faisal

    2014-01-01

    Abstract. Manual segmentation of anatomy in brain MRI data taken to be the closest to the “gold standard” in quality is often used in automated registration-based segmentation paradigms for transfer of template labels onto the unlabeled MRI images. This study presents a library of template data with 16 subcortical structures in the central brain area which were manually labeled for MRI data from 22 children (8 male, mean age=8±0.6  years). The lateral ventricle, thalamus, caudate, putamen, hippocampus, cerebellum, third vevntricle, fourth ventricle, brainstem, and corpuscallosum were segmented by two expert raters. Cross-validation experiments with randomized template subset selection were conducted to test for their ability to accurately segment MRI data under an automated segmentation pipeline. A high value of the dice similarity coefficient (0.86±0.06, min=0.74, max=0.96) and small Hausdorff distance (3.33±4.24, min=0.63, max=25.24) of the automated segmentation against the manual labels was obtained on this template library data. Additionally, comparison with segmentation obtained from adult templates showed significant improvement in accuracy with the use of an age-matched library in this cohort. A manually delineated pediatric template library such as the one described here could provide a useful benchmark for testing segmentation algorithms. PMID:26158067

  10. Manually segmented template library for 8-year-old pediatric brain MRI data with 16 subcortical structures.

    PubMed

    Garg, Amanmeet; Wong, Darren; Popuri, Karteek; Poskitt, Kenneth J; Fitzpatrick, Kevin; Bjornson, Bruce; Grunau, Ruth E; Beg, Mirza Faisal

    2014-10-01

    Manual segmentation of anatomy in brain MRI data taken to be the closest to the "gold standard" in quality is often used in automated registration-based segmentation paradigms for transfer of template labels onto the unlabeled MRI images. This study presents a library of template data with 16 subcortical structures in the central brain area which were manually labeled for MRI data from 22 children (8 male, [Formula: see text]). The lateral ventricle, thalamus, caudate, putamen, hippocampus, cerebellum, third vevntricle, fourth ventricle, brainstem, and corpuscallosum were segmented by two expert raters. Cross-validation experiments with randomized template subset selection were conducted to test for their ability to accurately segment MRI data under an automated segmentation pipeline. A high value of the dice similarity coefficient ([Formula: see text], [Formula: see text], [Formula: see text]) and small Hausdorff distance ([Formula: see text], [Formula: see text], [Formula: see text]) of the automated segmentation against the manual labels was obtained on this template library data. Additionally, comparison with segmentation obtained from adult templates showed significant improvement in accuracy with the use of an age-matched library in this cohort. A manually delineated pediatric template library such as the one described here could provide a useful benchmark for testing segmentation algorithms.

  11. Adaptive Modulation of Adult Brain Gray and White Matter to High Altitude: Structural MRI Studies

    PubMed Central

    Zhang, Jiaxing; Zhang, Haiyan; Li, Jinqiang; Chen, Ji; Han, Qiaoqing; Lin, Jianzhong; Yang, Tianhe; Fan, Ming

    2013-01-01

    The aim of this study was to investigate brain structural alterations in adult immigrants who adapted to high altitude (HA). Voxel-based morphometry analysis of gray matter (GM) volumes, surface-based analysis of cortical thickness, and Tract-Based Spatial Statistics analysis of white matter fractional anisotropy (FA) based on MRI images were conducted on 16 adults (20–22 years) who immigrated to the Qinghai-Tibet Plateau (2300–4400 m) for 2 years. They had no chronic mountain sickness. Control group consisted of 16 matched sea level subjects. A battery of neuropsychological tests was also conducted. HA immigrants showed significantly decreased GM volumes in the right postcentral gyrus and right superior frontal gyrus, and increased GM volumes in the right middle frontal gyrus, right parahippocampal gyrus, right inferior and middle temporal gyri, bilateral inferior ventral pons, and right cerebellum crus1. While there was some divergence in the left hemisphere, surface-based patterns of GM changes in the right hemisphere resembled those seen for VBM analysis. FA changes were observed in multiple WM tracts. HA immigrants showed significant impairment in pulmonary function, increase in reaction time, and deficit in mental rotation. Parahippocampal and middle frontal GM volumes correlated with vital capacity. Superior frontal GM volume correlated with mental rotation and postcentral GM correlated with reaction time. Paracentral lobule and frontal FA correlated with mental rotation reaction time. There might be structural modifications occurred in the adult immigrants during adaptation to HA. The changes in GM may be related to impaired respiratory function and psychological deficits. PMID:23874692

  12. Effect of Psychostimulants on Brain Structure and Function in ADHD: A Qualitative Literature Review of MRI-Based Neuroimaging Studies

    PubMed Central

    Spencer, Thomas J.; Brown, Ariel; Seidman, Larry J.; Valera, Eve M.; Makris, Nikos; Lomedico, Alexandra; Faraone, Stephen V.; Biederman, Joseph

    2013-01-01

    Objective To evaluate the impact of therapeutic oral doses of stimulants on the brains of ADHD subjects as measured by MRI-based neuroimaging studies (morphometric, functional, spectroscopy). Data Sources We searched PubMed and ScienceDirect through the end of calendar year 2011 using the keywords: 1) “psychostimulants” or “methylphenidate” or “amphetamine”, and 2) “neuroimaging” or “MRI” or “fMRI”, and 3) “ADHD” or “ADD” or “Attention-Deficit/Hyperactivity Disorder” or “Attention Deficit Hyperactivity Disorder”. Study Selection We included only English language articles with new data that were case or placebo-controlled and examined ADHD subjects on and off psychostimulants (as well as 5 relevant review papers). Data Extraction We combined details of study design and medication effects in each imaging modality. Results We found 29 published studies that met our criteria. These included 6 structural MRI, 20 functional MRI studies and 3 spectroscopy studies. Methods varied widely in terms of design, analytic technique, and regions of the brain investigated. Despite heterogeneity in methods, however, results were consistent. With only a few exceptions, the data on the effect of therapeutic oral doses of stimulant medication suggest attenuation of structural and functional alterations found in unmedicated ADHD subjects relative to findings in Controls. Conclusions Despite the inherent limitations and heterogeneity of the extant MRI literature, our review suggests that therapeutic oral doses of stimulants decrease alterations in brain structure and function in subjects with ADHD relative to unmedicated subjects and Controls. These medication-associated brain effects parallel, and may underlie, the well-established clinical benefits. PMID:24107764

  13. Brain Correlates of Self-Evaluation Deficits in Schizophrenia: A Combined Functional and Structural MRI Study.

    PubMed

    Tan, Shuping; Zhao, Yanli; Fan, Fengmei; Zou, Yizhuang; Jin, Zhen; Zen, Yawei; Zhu, Xiaolin; Yang, Fude; Tan, Yunlong; Zhou, Dongfeng

    2015-01-01

    Self-evaluation plays an important role in adaptive functioning and is a process that is typically impaired in patients with schizophrenia. Underlying neural mechanisms for this dysfunction may be associated with manifested psychosis. However, the brain substrates underlying this deficit are not well known. The present study used brain blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) and gray matter voxel-based morphometry to explore the functional and structural brain correlates of self-evaluation deficits in schizophrenia. Eighteen patients with schizophrenia and 17 healthy controls were recruited and asked to judge whether a set of personality-trait adjectives were appropriate for describing themselves, a familiar other, or whether the adjectives were of positive or negative valence. Patients had slower response times for negative trait attributions than controls did; responses to positive trait attributions were faster than those for negative traits among the patient group, while no differences were observed in the control group. Control subjects showed greater activation within the dorsal medial prefrontal cortex (dMPFC) and the anterior cingulate cortex (ACC) than the patient group during the self-evaluation > semantic positivity-evaluation contrast. Patients showed greater activation mainly within the posterior cingulate gyrus (PCC) as compared to controls for the other-evaluation > semantic positivity-evaluation contrast. Furthermore, gray matter volume was reduced in the MPFC, temporal lobe, cuneus, and the dorsal lateral prefrontal cortex (DLPFC) among the patient group when compared to controls. The present study adds to previous findings regarding self- and other-referential processing in schizophrenia, providing support for neurobiological models of self-reflection impairment. PMID:26406464

  14. Prediction of Conversion from Mild Cognitive Impairment to Alzheimer's Disease Using MRI and Structural Network Features.

    PubMed

    Wei, Rizhen; Li, Chuhan; Fogelson, Noa; Li, Ling

    2016-01-01

    Optimized magnetic resonance imaging (MRI) features and abnormalities of brain network architectures may allow earlier detection and accurate prediction of the progression from mild cognitive impairment (MCI) to Alzheimer's disease (AD). In this study, we proposed a classification framework to distinguish MCI converters (MCIc) from MCI non-converters (MCInc) by using a combination of FreeSurfer-derived MRI features and nodal features derived from the thickness network. At the feature selection step, we first employed sparse linear regression with stability selection, for the selection of discriminative features in the iterative combinations of MRI and network measures. Subsequently the top K features of available combinations were selected as optimal features for classification. To obtain unbiased results, support vector machine (SVM) classifiers with nested cross validation were used for classification. The combination of 10 features including those from MRI and network measures attained accuracies of 66.04, 76.39, 74.66, and 73.91% for mixed conversion time, 6, 12, and 18 months before diagnosis of probable AD, respectively. Analysis of the diagnostic power of different time periods before diagnosis of probable AD showed that short-term prediction (6 and 12 months) achieved more stable and higher AUC scores compared with long-term prediction (18 months), with K-values from 1 to 30. The present results suggest that meaningful predictors composed of MRI and network measures may offer the possibility for early detection of progression from MCI to AD. PMID:27148045

  15. Prediction of Conversion from Mild Cognitive Impairment to Alzheimer's Disease Using MRI and Structural Network Features

    PubMed Central

    Wei, Rizhen; Li, Chuhan; Fogelson, Noa; Li, Ling

    2016-01-01

    Optimized magnetic resonance imaging (MRI) features and abnormalities of brain network architectures may allow earlier detection and accurate prediction of the progression from mild cognitive impairment (MCI) to Alzheimer's disease (AD). In this study, we proposed a classification framework to distinguish MCI converters (MCIc) from MCI non-converters (MCInc) by using a combination of FreeSurfer-derived MRI features and nodal features derived from the thickness network. At the feature selection step, we first employed sparse linear regression with stability selection, for the selection of discriminative features in the iterative combinations of MRI and network measures. Subsequently the top K features of available combinations were selected as optimal features for classification. To obtain unbiased results, support vector machine (SVM) classifiers with nested cross validation were used for classification. The combination of 10 features including those from MRI and network measures attained accuracies of 66.04, 76.39, 74.66, and 73.91% for mixed conversion time, 6, 12, and 18 months before diagnosis of probable AD, respectively. Analysis of the diagnostic power of different time periods before diagnosis of probable AD showed that short-term prediction (6 and 12 months) achieved more stable and higher AUC scores compared with long-term prediction (18 months), with K-values from 1 to 30. The present results suggest that meaningful predictors composed of MRI and network measures may offer the possibility for early detection of progression from MCI to AD. PMID:27148045

  16. A comparison of supervised machine learning algorithms and feature vectors for MS lesion segmentation using multimodal structural MRI.

    PubMed

    Sweeney, Elizabeth M; Vogelstein, Joshua T; Cuzzocreo, Jennifer L; Calabresi, Peter A; Reich, Daniel S; Crainiceanu, Ciprian M; Shinohara, Russell T

    2014-01-01

    Machine learning is a popular method for mining and analyzing large collections of medical data. We focus on a particular problem from medical research, supervised multiple sclerosis (MS) lesion segmentation in structural magnetic resonance imaging (MRI). We examine the extent to which the choice of machine learning or classification algorithm and feature extraction function impacts the performance of lesion segmentation methods. As quantitative measures derived from structural MRI are important clinical tools for research into the pathophysiology and natural history of MS, the development of automated lesion segmentation methods is an active research field. Yet, little is known about what drives performance of these methods. We evaluate the performance of automated MS lesion segmentation methods, which consist of a supervised classification algorithm composed with a feature extraction function. These feature extraction functions act on the observed T1-weighted (T1-w), T2-weighted (T2-w) and fluid-attenuated inversion recovery (FLAIR) MRI voxel intensities. Each MRI study has a manual lesion segmentation that we use to train and validate the supervised classification algorithms. Our main finding is that the differences in predictive performance are due more to differences in the feature vectors, rather than the machine learning or classification algorithms. Features that incorporate information from neighboring voxels in the brain were found to increase performance substantially. For lesion segmentation, we conclude that it is better to use simple, interpretable, and fast algorithms, such as logistic regression, linear discriminant analysis, and quadratic discriminant analysis, and to develop the features to improve performance. PMID:24781953

  17. MRI and low back pain

    MedlinePlus

    Backache - MRI; Low back pain - MRI; Lumbar pain - MRI; Back strain - MRI; Lumbar radiculopathy - MRI; Herniated intervertebral disk - MRI; Prolapsed intervertebral disk - MRI; Slipped disk - MRI; Ruptured ...

  18. Validity of semi-quantitative scale for brain MRI in unilateral cerebral palsy due to periventricular white matter lesions: Relationship with hand sensorimotor function and structural connectivity

    PubMed Central

    Fiori, Simona; Guzzetta, Andrea; Pannek, Kerstin; Ware, Robert S.; Rossi, Giuseppe; Klingels, Katrijn; Feys, Hilde; Coulthard, Alan; Cioni, Giovanni; Rose, Stephen; Boyd, Roslyn N.

    2015-01-01

    Aim To provide first evidence of construct validity of a semi-quantitative scale for brain structural MRI (sqMRI scale) in children with unilateral cerebral palsy (UCP) secondary to periventricular white matter (PWM) lesions, by examining the relationship with hand sensorimotor function and whole brain structural connectivity. Methods Cross-sectional study of 50 children with UCP due to PWM lesions using 3 T (MRI), diffusion MRI and assessment of hand sensorimotor function. We explored the relationship of lobar, hemispheric and global scores on the sqMRI scale, with fractional anisotropy (FA), as a measure of brain white matter microstructure, and with hand sensorimotor measures (Assisting Hand Assessment, AHA; Jebsen–Taylor Test for Hand Function, JTTHF; Melbourne Assessment of Unilateral Upper Limb Function, MUUL; stereognosis; 2-point discrimination). Results Lobar and hemispheric scores on the sqMRI scale contralateral to the clinical side of hemiplegia correlated with sensorimotor paretic hand function measures and FA of a number of brain structural connections, including connections of brain areas involved in motor control (postcentral, precentral and paracentral gyri in the parietal lobe). More severe lesions correlated with lower sensorimotor performance, with the posterior limb of internal capsule score being the strongest contributor to impaired hand function. Conclusion The sqMRI scale demonstrates first evidence of construct validity against impaired motor and sensory function measures and brain structural connectivity in a cohort of children with UCP due to PWM lesions. More severe lesions correlated with poorer paretic hand sensorimotor function and impaired structural connectivity in the hemisphere contralateral to the clinical side of hemiplegia. The quantitative structural MRI scoring may be a useful clinical tool for studying brain structure–function relationships but requires further validation in other populations of CP. PMID:26106533

  19. MRI of the brain (image)

    MedlinePlus

    An MRI (magnetic resonance imaging) of the brain creates a detailed image of the complex structures in the brain. An MRI can give a three-dimensional depiction of the brain, making location of problems such ...

  20. Multimodal visualization of 3D enhanced MRI and CT of acoustic schwannoma and related structures

    NASA Astrophysics Data System (ADS)

    Kucharski, Tomasz; Kujawinska, Malgorzata; Niemczyk, Kazimierz; Marchel, Andrzej

    2005-09-01

    According to the necessity of supporting vestibular schwannoma surgery, there is a demand to develop a convenient method of medical data visualization. The process of making choice of optimal operating access way has been uncomfortable for a surgeon so far, because there has been a necessity of analyzing two independent 3D images series (CT -bone tissues visible, MRI - soft tissues visible) in the region of ponto-cerebellar angle tumors. The authors propose a solution that will improve this process. The system used is equipped with stereoscopic helmet mounted display. It allows merged CT and MRI data representing tissues in the region of of ponto-cerebellar angle to be visualized in stereoscopic way. The process of data preparation for visualization includes: -automated segmentation algorithms, -different types of 3D images (CT, MRI) fusion. The authors focused on the development of novel algorithms for segmentation of vestibular schwannoma. It is important and difficult task due to different types of tumors and their inhomogeneous character dependent on growth models. The authors propose algorithms based on histogram spectrum and multimodal character of MRI imaging (T1 and T2 modes). However due to a variety of objects the library of algorithms with specific modifications matching to selected types of images is proposed. The applicability and functionality of the algorithms and library was proved on the series of data delivered by Warsaw Central Medical University Hospital.

  1. Using fMRI non-local means denoising to uncover activation in sub-cortical structures at 1.5 T for guided HARDI tractography

    PubMed Central

    Bernier, Michaël; Chamberland, Maxime; Houde, Jean-Christophe; Descoteaux, Maxime; Whittingstall, Kevin

    2014-01-01

    In recent years, there has been ever-increasing interest in combining functional magnetic resonance imaging (fMRI) and diffusion magnetic resonance imaging (dMRI) for better understanding the link between cortical activity and connectivity, respectively. However, it is challenging to detect and validate fMRI activity in key sub-cortical areas such as the thalamus, given that they are prone to susceptibility artifacts due to the partial volume effects (PVE) of surrounding tissues (GM/WM interface). This is especially true on relatively low-field clinical MR systems (e.g., 1.5 T). We propose to overcome this limitation by using a spatial denoising technique used in structural MRI and more recently in diffusion MRI called non-local means (NLM) denoising, which uses a patch-based approach to suppress the noise locally. To test this, we measured fMRI in 20 healthy subjects performing three block-based tasks : eyes-open closed (EOC) and left/right finger tapping (FTL, FTR). Overall, we found that NLM yielded more thalamic activity compared to traditional denoising methods. In order to validate our pipeline, we also investigated known structural connectivity going through the thalamus using HARDI tractography: the optic radiations, related to the EOC task, and the cortico-spinal tract (CST) for FTL and FTR. To do so, we reconstructed the tracts using functionally based thalamic and cortical ROIs to initiates seeds of tractography in a two-level coarse-to-fine fashion. We applied this method at the single subject level, which allowed us to see the structural connections underlying fMRI thalamic activity. In summary, we propose a new fMRI processing pipeline which uses a recent spatial denoising technique (NLM) to successfully detect sub-cortical activity which was validated using an advanced dMRI seeding strategy in single subjects at 1.5 T. PMID:25309391

  2. Combination of NMR and MRI quantitation of moisture and structure changes for convection cooking of fresh chicken meat.

    PubMed

    Shaarani, Sharifudin Md; Nott, Kevin P; Hall, Laurance D

    2006-03-01

    This study demonstrates that a combination of bulk NMR and magnetic resonance imaging measurements of the T(2)-values of water protons can be used to determine the heat-induced changes in the structure and moisture content of fresh chicken meat which had been cooked in a convection oven at 200°C for a range of times. The gravimetric moisture content was also determined for both the raw and cooked meat. Multi-exponential fitting of the bulk NMR T(2) relaxation time data demonstrated three distinct water populations T(21) (39-43ms), T(22) (82-99ms) and T(23) (2-3ms) for raw meat which changed to 18-31ms (T(21)), 61-208ms (T(22)) and 3-7ms (T(23)) after the meat had been cooked. The T(1) and T(2) values obtained by MRI for cooked meat decreased progressively with increased heating time. There are highly significant correlations between the T(2) values from MRI and the T(21) values from bulk NMR measurements of cooked meat (r=0.986; p<0.01), and also between the normalised M(0) values from MRI and the gravimetric moisture content (r=0.953; p<0.01).

  3. Exploratory Structural Equation Modeling of Resting-state fMRI: applicability of group models to individual subjects

    PubMed Central

    James, G. Andrew; Kelley, Mary E.; Craddock, R. Cameron; Holtzheimer, Paul E.; Dunlop, Boadie; Nemeroff, Charles; Mayberg, Helen S.; Hu, Xiaoping P.

    2009-01-01

    The extension of group-level connectivity methods to individual subjects remains a hurdle for statistical analyses of neuroimaging data. Previous group analyses of positron emission tomography data in clinically depressed patients, for example, have shown that resting-state connectivity prior to therapy predicts how patients eventually respond to pharmacological and cognitive-behavioral therapy. Such applications would be considerably more informative for clinical decision making if these connectivity methods could be extended into the individual subject domain. To test such an extension, 46 treatment-naïve depressed patients were enrolled in an fMRI study to model baseline resting-state functional connectivity. Resting-state fMRI scans were acquired and submitted to exploratory structural equation modeling (SEM) to derive the optimal group connectivity model. Jackknife and split sample tests confirm that group model was highly reproducible, and path weights were consistent across the best five group models. When this model was applied to data from individual subjects, 85% of patients fit the group model. Histogram analysis of individual subjects’ paths indicate that some paths are better representative of group membership. These results suggest that exploratory SEM is a viable technique for neuroimaging connectivity analyses of individual subjects’ resting-state fMRI data. PMID:19162206

  4. Combining EEG Microstates with fMRI Structural Features for Modeling Brain Activity.

    PubMed

    Michalopoulos, Kostas; Bourbakis, Nikolaos

    2015-12-01

    Combining information from Electroencephalography (EEG) and Functional Magnetic Resonance Imaging (fMRI) has been a topic of increased interest recently. The main advantage of the EEG is its high temporal resolution, in the scale of milliseconds, while the main advantage of fMRI is the detection of functional activity with good spatial resolution. The advantages of each modality seem to complement each other, providing better insight in the neuronal activity of the brain. The main goal of combining information from both modalities is to increase the spatial and the temporal localization of the underlying neuronal activity captured by each modality. This paper presents a novel technique based on the combination of these two modalities (EEG, fMRI) that allow a better representation and understanding of brain activities in time. EEG is modeled as a sequence of topographies, based on the notion of microstates. Hidden Markov Models (HMMs) were used to model the temporal evolution of the topography of the average Event Related Potential (ERP). For each model the Fisher score of the sequence is calculated by taking the gradient of the trained model parameters. The Fisher score describes how this sequence deviates from the learned HMM. Canonical Partial Least Squares (CPLS) were used to decompose the two datasets and fuse the EEG and fMRI features. In order to test the effectiveness of this method, the results of this methodology were compared with the results of CPLS using the average ERP signal of a single channel. The presented methodology was able to derive components that co-vary between EEG and fMRI and present significant differences between the two tasks.

  5. Combining EEG Microstates with fMRI Structural Features for Modeling Brain Activity.

    PubMed

    Michalopoulos, Kostas; Bourbakis, Nikolaos

    2015-12-01

    Combining information from Electroencephalography (EEG) and Functional Magnetic Resonance Imaging (fMRI) has been a topic of increased interest recently. The main advantage of the EEG is its high temporal resolution, in the scale of milliseconds, while the main advantage of fMRI is the detection of functional activity with good spatial resolution. The advantages of each modality seem to complement each other, providing better insight in the neuronal activity of the brain. The main goal of combining information from both modalities is to increase the spatial and the temporal localization of the underlying neuronal activity captured by each modality. This paper presents a novel technique based on the combination of these two modalities (EEG, fMRI) that allow a better representation and understanding of brain activities in time. EEG is modeled as a sequence of topographies, based on the notion of microstates. Hidden Markov Models (HMMs) were used to model the temporal evolution of the topography of the average Event Related Potential (ERP). For each model the Fisher score of the sequence is calculated by taking the gradient of the trained model parameters. The Fisher score describes how this sequence deviates from the learned HMM. Canonical Partial Least Squares (CPLS) were used to decompose the two datasets and fuse the EEG and fMRI features. In order to test the effectiveness of this method, the results of this methodology were compared with the results of CPLS using the average ERP signal of a single channel. The presented methodology was able to derive components that co-vary between EEG and fMRI and present significant differences between the two tasks. PMID:26584584

  6. Implicit reference-based group-wise image registration and its application to structural and functional MRI.

    PubMed

    Geng, Xiujuan; Christensen, Gary E; Gu, Hong; Ross, Thomas J; Yang, Yihong

    2009-10-01

    In this study, an implicit reference group-wise (IRG) registration with a small deformation, linear elastic model was used to jointly estimate correspondences between a set of MRI images. The performance of pair-wise and group-wise registration algorithms was evaluated for spatial normalization of structural and functional MRI data. Traditional spatial normalization is accomplished by group-to-reference (G2R) registration in which a group of images are registered pair-wise to a reference image. G2R registration is limited due to bias associated with selecting a reference image. In contrast, implicit reference group-wise (IRG) registration estimates correspondences between a group of images by jointly registering the images to an implicit reference corresponding to the group average. The implicit reference is estimated during IRG registration eliminating the bias associated with selecting a specific reference image. Registration performance was evaluated using segmented T1-weighted magnetic resonance images from the Nonrigid Image Registration Evaluation Project (NIREP), DTI and fMRI images. Implicit reference pair-wise (IRP) registration-a special case of IRG registration for two images-is shown to produce better relative overlap than IRG for pair-wise registration using the same small deformation, linear elastic registration model. However, IRP-G2R registration is shown to have significant transitivity error, i.e., significant inconsistencies between correspondences defined by different pair-wise transformations. In contrast, IRG registration produces consistent correspondence between images in a group at the cost of slightly reduced pair-wise RO accuracy compared to IRP-G2R. IRG spatial normalization of the fractional anisotropy (FA) maps of DTI is shown to have smaller FA variance compared with G2R methods using the same elastic registration model. Analyses of fMRI data sets with sensorimotor and visual tasks show that IRG registration, on average, increases the

  7. A survey of current trends in diffusion MRI for structural brain connectivity

    NASA Astrophysics Data System (ADS)

    Ghosh, Aurobrata; Deriche, Rachid

    2016-02-01

    In this paper, we review the state of the art in diffusion magnetic resonance imaging (dMRI) and we present current trends in modelling the brain's tissue microstructure and the human connectome. dMRI is today the only tool that can probe the brain's axonal architecture in vivo and non-invasively, and has grown in leaps and bounds in the last two decades since its conception. A plethora of models with increasing complexity and better accuracy have been proposed to characterise the integrity of the cerebral tissue, to understand its microstructure and to infer its connectivity. Here, we discuss a wide range of the most popular, important and well-established local microstructure models and biomarkers that have been proposed from these models. Finally, we briefly present the state of the art in tractography techniques that allow us to understand the architecture of the brain's connectivity.

  8. Simultaneous EEG and fMRI: towards the characterization of structure and dynamics of brain networks.

    PubMed

    Mulert, Christoph

    2013-09-01

    Progress in the understanding of normal and disturbed brain function is critically dependent on the methodological approach that is applied. Both electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are extremely efficient methods for the assessment of human brain function. The specific appeal of the combination is related to the fact that both methods are complementary in terms of basic aspects: EEG is a direct measurement of neural mass activity and provides high temporal resolution. FMRI is an indirect measurement of neural activity and based on hemodynamic changes, and offers high spatial resolution. Both methods are very sensitive to changes of synaptic activity, suggesting that with simultaneous EEG and fMRI the same neural events can be characterized with both high temporal and spatial resolution. Since neural oscillations that can be assessed with EEG are a key mechanism for multi-site communication in the brain, EEG-fMRI can offer new insights into the connectivity mechanisms of brain networks.

  9. Gray Matter Alterations in Schizophrenia High-Risk Youth and Early-Onset Schizophrenia: A Review of Structural MRI Findings

    PubMed Central

    Brent, Benjamin K.; Thermenos, Heidi W.; Keshavan, Matcheri S.; Seidman, Larry J.

    2013-01-01

    Synopsis The purpose of this article is to provide a review of the literature on structural MRI findings in pediatric and young adult populations at clinical or genetic high-risk for schizophrenia, as well as in early-onset schizophrenia. The authors discuss the implications of this research for understanding the pathophysiology of schizophrenia and for early intervention strategies for prevention of the illness. The evidence linking brain structural changes in pre-psychosis development and early-onset schizophrenia with disruptions of normal neurodevelopmental processes during childhood and/or adolescence are described. In addition, the authors outline future directions for research to address current knowledge gaps regarding the neurobiological basis of brain structural abnormalities in schizophrenia and to help improve the utility of these abnormalities for preventative interventions. PMID:24012081

  10. Emotional voice areas: anatomic location, functional properties, and structural connections revealed by combined fMRI/DTI.

    PubMed

    Ethofer, Thomas; Bretscher, Johannes; Gschwind, Markus; Kreifelts, Benjamin; Wildgruber, Dirk; Vuilleumier, Patrik

    2012-01-01

    We determined the location, functional response profile, and structural fiber connections of auditory areas with voice- and emotion-sensitive activity using functional magnetic resonance imaging (fMRI) and diffusion tensor imaging. Bilateral regions responding to emotional voices were consistently found in the superior temporal gyrus, posterolateral to the primary auditory cortex. Event-related fMRI showed stronger responses in these areas to voices-expressing anger, sadness, joy, and relief, relative to voices with neutral prosody. Their neural responses were primarily driven by prosodic arousal, irrespective of valence. Probabilistic fiber tracking revealed direct structural connections of these "emotional voice areas" (EVA) with ipsilateral medial geniculate body, which is the major input source of early auditory cortex, as well as with the ipsilateral inferior frontal gyrus (IFG) and inferior parietal lobe (IPL). In addition, vocal emotions (compared with neutral prosody) increased the functional coupling of EVA with the ipsilateral IFG but not IPL. These results provide new insights into the neural architecture of the human voice processing system and support a crucial involvement of IFG in the recognition of vocal emotions, whereas IPL may subserve distinct auditory spatial functions, consistent with distinct anatomical substrates for the processing of "how" and "where" information within the auditory pathways. PMID:21625012

  11. The Lumbar Spine as a Dynamic Structure Depicted in Upright MRI

    PubMed Central

    Kubosch, David; Vicari, Marco; Siller, Alexander; Strohm, Peter C.; Kubosch, Eva J.; Knöller, Stefan; Hennig, Jürgen; Südkamp, Norbert P.; Izadpanah, Kaywan

    2015-01-01

    Abstract Spinal canal stenosis is a dynamic phenomenon that becomes apparent during spinal loading. Current diagnostic procedures have considerable short comings in diagnosing the disease to full extend, as they are performed in supine situation. Upright MRI imaging might overcome this diagnostic gap. This study investigated the lumbar neuroforamenal diameter, spinal canal diameter, vertebral body translation, and vertebral body angles in 3 different body positions using upright MRI imaging. Fifteen subjects were enrolled in this study. A dynamic MRI in 3 different body positions (at 0° supine, 80° upright, and 80° upright + hyperlordosis posture) was taken using a 0.25 T open-configuration scanner equipped with a rotatable examination bed allowing a true standing MRI. The mean diameter of the neuroforamen at L5/S1 in 0° position was 8.4 mm on the right and 8.8 mm on the left, in 80° position 7.3 mm on the right and 7.2 mm on the left, and in 80° position with hyperlordosis 6.6 mm (P < 0.05) on the right and 6.1 mm on the left (P < 0.001). The mean area of the neuroforamen at L5/S1 in 0° position was 103.5 mm2 on the right and 105.0 mm2 on the left, in 80° position 92.5 mm2 on the right and 94.8 mm2 on the left, and in 80° position with hyperlordosis 81.9 mm2 on the right and 90.2 mm2 on the left. The mean volume of the spinal canal at the L5/S1 level in 0° position was 9770 mm3, in 80° position 10600 mm3, and in 80° position with hyperlordosis 9414 mm3. The mean intervertebral translation at level L5/S1 was 8.3 mm in 0° position, 9.9 mm in 80° position, and 10.1 mm in the 80° position with hyperlordosis. The lordosis angle at level L5/S1 was 49.4° in 0° position, 55.8° in 80° position, and 64.7 mm in the 80° position with hyperlordosis. Spinal canal stenosis is subject to a dynamic process, that can be displayed in upright MRI imaging. The range of anomalies is clinically relevant and dynamic

  12. Bayesian estimation of optical properties of the human head via 3D structural MRI

    NASA Astrophysics Data System (ADS)

    Barnett, Alexander H.; Culver, Joseph P.; Sorensen, A. Gregory; Dale, Anders M.; Boas, David A.

    2003-10-01

    Knowledge of the baseline optical properties of the tissues of the human head is essential for absolute cerebral oximetry, and for quantitative studies of brain activation. In this work we numerically model the utility of signals from a small 6-optode time-resolved diffuse optical tomographic apparatus for inferring baseline scattering and absorption coefficients of the scalp, skull and brain, when complete geometric information is available from magnetic resonance imaging (MRI). We use an optical model where MRI-segmented tissues are assumed homogeneous. We introduce a noise model capturing both photon shot noise and forward model numerical accuracy, and use Bayesian inference to predict errorbars and correlations on the measurments. We also sample from the full posterior distribution using Markov chain Monte Carlo. We conclude that ~ 106 detected photons are sufficient to measure the brain"s scattering and absorption to a few percent. We present preliminary results using a fast multi-layer slab model, comparing the case when layer thicknesses are known versus unknown.

  13. Body Composition in Premature Adrenarche by Structural MRI, 1H MRS and DXA

    PubMed Central

    Leibel, Natasha; Shen, Wei; Mao, Xiangling; Punyanitya, Mark; Gallagher, Dympna; Horlick, Mary; Shungu, Dikoma C.; Oberfield, Sharon E.

    2010-01-01

    Background Premature adrenarche (PA) is recognized to be a possible precursor of polycystic ovarian syndrome, type 2 diabetes mellitus and cardiovascular disease. Visceral adiposity and increased intramyocellular lipid (IMCL) are associated with insulin resistance and increased risk of cardiovascular disease. Aim To determine whether prepubertal girls with PA have altered visceral adiposity and/or increased muscle lipid content compared to prepubertal girls without PA using proton magnetic resonance imaging (MRI) and spectroscopy (1H MRS). Patients and Methods We performed total body dual energy X-ray absorptiometry (DXA) scans, MRI of the trunk, and MRS of the tibialis anterior muscle in the right calf on six girls with PA and eight prepubertal controls. Results Amount of visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue (SAT), and VAT to SAT ratio did not differ significantly between the PA and control girls. Those with PA, however, had significantly greater IMCL than controls (p = 0.004). Conclusions This study adds further evidence that PA is not a benign condition, and future studies investigating early intervention with dietary and exercise counseling may help diminish potential risk for diabetes mellitus and/or cardiovascular disease. PMID:19554803

  14. Combined diffusion and strain MRI reveals structure and function of human myocardial laminar sheets in vivo.

    PubMed

    Dou, Jiangang; Tseng, Wen-Yih I; Reese, Timothy G; Wedeen, Van J

    2003-07-01

    The mechanism of ventricular thickening in normal humans was investigated using in vivo MRI. The hypothesis that myocardial laminar sheets contribute to ventricular thickening predominantly via sheet shear and sheet extension, as previously found invasively in canine studies at particular ventricular sites, was tested. In normal human subjects, registered images of myocardial sheet architecture and strain at the mid-left ventricle (mid-LV) at mid-systole were acquired with diffusion and strain MRI. Sheet function was analyzed by computing myocardial strain in the local fiber-sheet coordinates. In general, myocardial sheets contribute to ventricular thickening through all three cross-fiber strain components: sheet shear, sheet extension, and sheet-normal thickening (previously undocumented). Each of these components demonstrated substantial spatial heterogeneity, with sheet shear and sheet extension usually predominant in the anterior free wall, and sheet-normal thickening predominant near the right ventricular (RV) insertions. However, considerable intersubject variability was also found. In all cases, the contributions to thickening of fiber strains were small. Sheet function in normal humans was found to be heterogeneous and variable, contrasting with the uniform and symmetric ventricular patterns of fiber shortening and wall thickening. The study demonstrates that noninvasive NMR imaging is a promising tool for investigations of myocardial sheet architecture and function, and is particularly suited to the evident complexity of this field of study.

  15. Synthesis and development of novel fullerene-based structures for photovoltaics, electronic applications and MRI contrast agents

    NASA Astrophysics Data System (ADS)

    Chaur, Manuel N.

    Metallic nitride endohedral metallofullerenes (EMFs) are one of the most interesting types of metallofullerenes due to their high yields and interesting electronic properties. The synthesis of these compounds allows the encapsulation of different metals inside fullerenes making it possible to combine the properties of the metal with those of the fullerene. Their interesting electrochemical and optical features make them potential candidates for several applications such as molecular electronics, biomedical imaging, non-linear optical devices, and magnetic resonance imaging (MRI) agents. This thesis reports the synthesis of novel metallic nitride EMFs based on Gd, Nd, Pr, Ce and La. These families of metallofullerenes were characterized by different techniques such as X-ray diffraction, MALDI-TOF mass spectrometry, HPLC, electrochemistry and UV/Vis-NIR spectroscopy. The reactivity study of the Gd nitride EMF family and the synthesis of a third generation dendrimer that is attached to EMFs in order to obtain water soluble structures that can be used in MRI applications is also covered. Finally, a comprehensive electrochemical study of carbon rich macrocycles is reported.

  16. A structural-functional MRI-based disease atlas: application to computer-aided-diagnosis of prostate cancer

    NASA Astrophysics Data System (ADS)

    Xiao, G.; Bloch, B.; Chappelow, J.; Genega, E.; Rofsky, N.; Lenkinski, R.; Madabhushi, A.

    2010-03-01

    Different imaging modalities or protocols of a single patient may convey different types of information regarding a disease for the same anatomical organ/tissue. On the other hand, multi-modal/multi-protocol medical images from several different patients can also provide spatial statistics of the disease occurrence, which in turn can greatly aid in disease diagnosis and aid in improved, accurate biopsy and targeted treatment. It is therefore important to not only integrate medical images from multiple patients into a common coordinate frame (in the form of a population-based atlas), but also find the correlation between these multi-modal/multi-protocol data features and the disease spatial distribution in order to identify different quantitative structural and functional disease signatures. Most previous work on construction of anatomical atlases has focused on deriving a population-based atlas for the purpose of deriving the spatial statistics. Moreover, these models are typically derived from normal or healthy subjects, either explicitly or implicitly, where it is assumed that the inter-patient pathological variation is not large. These methods are not suitable for constructing a disease atlas, where significant differences between patients on account of disease related variations can be expected. In this paper, we present a novel framework for the construction of a multi-parametric MRI-based data-driven disease atlas consisting of multi-modal and multi-protocol data from across multiple patient studies. Our disease atlas contains 3 Tesla structural (T2) and functional (dynamic contrast enhanced (DCE)) prostate in vivo MRI with corresponding whole mount histology specimens obtained via radical prostatectomy. Our atlas construction framework comprises 3 distinct modules: (a) determination of disease spatial extent on the multi-protocol MR imagery for each patient, (b) construction of a multi-protocol MR imaging spatial atlas which captures the geographical

  17. Convergent Findings of Altered Functional and Structural Brain Connectivity in Individuals with High Functioning Autism: A Multimodal MRI Study.

    PubMed

    Mueller, Sophia; Keeser, Daniel; Samson, Andrea C; Kirsch, Valerie; Blautzik, Janusch; Grothe, Michel; Erat, Okan; Hegenloh, Michael; Coates, Ute; Reiser, Maximilian F; Hennig-Fast, Kristina; Meindl, Thomas

    2013-01-01

    Brain tissue changes in autism spectrum disorders seem to be rather subtle and widespread than anatomically distinct. Therefore a multimodal, whole brain imaging technique appears to be an appropriate approach to investigate whether alterations in white and gray matter integrity relate to consistent changes in functional resting state connectivity in individuals with high functioning autism (HFA). We applied diffusion tensor imaging (DTI), voxel-based morphometry (VBM) and resting state functional connectivity magnetic resonance imaging (fcMRI) to assess differences in brain structure and function between 12 individuals with HFA (mean age 35.5, SD 11.4, 9 male) and 12 healthy controls (mean age 33.3, SD 9.0, 8 male). Psychological measures of empathy and emotionality were obtained and correlated with the most significant DTI, VBM and fcMRI findings. We found three regions of convergent structural and functional differences between HFA participants and controls. The right temporo-parietal junction area and the left frontal lobe showed decreased fractional anisotropy (FA) values along with decreased functional connectivity and a trend towards decreased gray matter volume. The bilateral superior temporal gyrus displayed significantly decreased functional connectivity that was accompanied by the strongest trend of gray matter volume decrease in the temporal lobe of HFA individuals. FA decrease in the right temporo-parietal region was correlated with psychological measurements of decreased emotionality. In conclusion, our results indicate common sites of structural and functional alterations in higher order association cortex areas and may therefore provide multimodal imaging support to the long-standing hypothesis of autism as a disorder of impaired higher-order multisensory integration.

  18. Convergent Findings of Altered Functional and Structural Brain Connectivity in Individuals with High Functioning Autism: A Multimodal MRI Study

    PubMed Central

    Samson, Andrea C.; Kirsch, Valerie; Blautzik, Janusch; Grothe, Michel; Erat, Okan; Hegenloh, Michael; Coates, Ute; Reiser, Maximilian F.; Hennig-Fast, Kristina; Meindl, Thomas

    2013-01-01

    Brain tissue changes in autism spectrum disorders seem to be rather subtle and widespread than anatomically distinct. Therefore a multimodal, whole brain imaging technique appears to be an appropriate approach to investigate whether alterations in white and gray matter integrity relate to consistent changes in functional resting state connectivity in individuals with high functioning autism (HFA). We applied diffusion tensor imaging (DTI), voxel-based morphometry (VBM) and resting state functional connectivity magnetic resonance imaging (fcMRI) to assess differences in brain structure and function between 12 individuals with HFA (mean age 35.5, SD 11.4, 9 male) and 12 healthy controls (mean age 33.3, SD 9.0, 8 male). Psychological measures of empathy and emotionality were obtained and correlated with the most significant DTI, VBM and fcMRI findings. We found three regions of convergent structural and functional differences between HFA participants and controls. The right temporo-parietal junction area and the left frontal lobe showed decreased fractional anisotropy (FA) values along with decreased functional connectivity and a trend towards decreased gray matter volume. The bilateral superior temporal gyrus displayed significantly decreased functional connectivity that was accompanied by the strongest trend of gray matter volume decrease in the temporal lobe of HFA individuals. FA decrease in the right temporo-parietal region was correlated with psychological measurements of decreased emotionality. In conclusion, our results indicate common sites of structural and functional alterations in higher order association cortex areas and may therefore provide multimodal imaging support to the long-standing hypothesis of autism as a disorder of impaired higher-order multisensory integration. PMID:23825652

  19. Direct evidence of intra- and interhemispheric corticomotor network degeneration in amyotrophic lateral sclerosis: an automated MRI structural connectivity study.

    PubMed

    Rose, Stephen; Pannek, Kerstin; Bell, Christopher; Baumann, Fusun; Hutchinson, Nicole; Coulthard, Alan; McCombe, Pamela; Henderson, Robert

    2012-02-01

    Although the pathogenesis of amyotrophic lateral sclerosis (ALS) is uncertain, there is mounting neuroimaging evidence to suggest a mechanism involving the degeneration of multiple white matter (WM) motor and extramotor neural networks. This insight has been achieved, in part, by using MRI Diffusion Tensor Imaging (DTI) and the voxelwise analysis of anisotropy indices, along with DTI tractography to determine which specific motor pathways are involved with ALS pathology. Automated MRI structural connectivity analyses, which probe WM connections linking various functionally discrete cortical regions, have the potential to provide novel information about degenerative processes within multiple white matter (WM) pathways. Our hypothesis is that measures of altered intra- and interhemispheric structural connectivity of the primary motor and somatosensory cortex will provide an improved assessment of corticomotor involvement in ALS. To test this hypothesis, we acquired High Angular Resolution Diffusion Imaging (HARDI) scans along with high resolution structural images (sMRI) on 15 patients with clinical evidence of upper and lower motor neuron involvement, and 20 matched control participants. Whole brain probabilistic tractography was applied to define specific WM pathways connecting discrete corticomotor targets generated from anatomical parcellation of sMRI of the brain. The integrity of these connections was interrogated by comparing the mean fractional anisotropy (FA) derived for each WM pathway. To assist in the interpretation of results, we measured the reproducibility of the FA summary measures over time (6months) in control participants. We also incorporated into our analysis pipeline the evaluation and replacement of outlier voxels due to head motion and physiological noise. When assessing corticomotor connectivity, we found a significant reduction in mean FA within a number of intra- and interhemispheric motor pathways in ALS patients. The abnormal

  20. Structural analysis of fMRI data: a surface-based framework for multi-subject studies.

    PubMed

    Operto, Grégory; Rivière, Denis; Fertil, Bernard; Bulot, Rémy; Mangin, Jean-François; Coulon, Olivier

    2012-07-01

    We present a method for fMRI data group analysis that makes the link between two distinct frameworks: surface-based techniques, which process data in the domain defined by the surface of the cortex, and structural techniques, which use object-based representations of the data as opposed to voxel-based ones. This work is a natural surface-based extension of the volume-based structural approach presented in a previous paper. A multi-scale surface-based representation of individual activation maps is first computed for each subject. Then the inter-subject matching and the activation detection decision are performed jointly by optimization of a Markovian model. Finally, a significance measure is computed in a non-parametric way for the results, in order to assess their relevance and control the risk of type I error. The method is applied on simulated and real data and the results are compared to those produced by standard analyses. The surface-based structural analysis is shown to be particularly robust to inter-subject spatial variability and to produce relevant results with good specificity and sensitivity. We also demonstrate the advantages of the surface-based approach by comparing with the results of a 3D structural analysis. PMID:22465075

  1. Automatic ROI selection in structural brain MRI using SOM 3D projection.

    PubMed

    Ortiz, Andrés; Górriz, Juan M; Ramírez, Javier; Martinez-Murcia, Francisco J

    2014-01-01

    This paper presents a method for selecting Regions of Interest (ROI) in brain Magnetic Resonance Imaging (MRI) for diagnostic purposes, using statistical learning and vector quantization techniques. The proposed method models the distribution of GM and WM tissues grouping the voxels belonging to each tissue in ROIs associated to a specific neurological disorder. Tissue distribution of normal and abnormal images is modelled by a Self-Organizing map (SOM), generating a set of representative prototypes, and the receptive field (RF) of each SOM prototype defines a ROI. Moreover, the proposed method computes the relative importance of each ROI by means of its discriminative power. The devised method has been assessed using 818 images from the Alzheimer's disease Neuroimaging Initiative (ADNI) which were previously segmented through Statistical Parametric Mapping (SPM). The proposed algorithm was used over these images to parcel ROIs associated to the Alzheimer's Disease (AD). Additionally, this method can be used to extract a reduced set of discriminative features for classification, since it compresses discriminative information contained in the brain. Voxels marked by ROIs which were computed using the proposed method, yield classification results up to 90% of accuracy for controls (CN) and Alzheimer's disease (AD) patients, and 84% of accuracy for Mild Cognitive Impairment (MCI) and AD patients.

  2. Gender differences in brain development in Chinese children and adolescents: a structural MRI study

    NASA Astrophysics Data System (ADS)

    Guo, Xiaojuan; Jin, Zhen; Chen, Kewei; Peng, Danling; Yao, Li

    2008-03-01

    Using optimized voxel-based morphometry (VBM), this study systematically investigated gender differences in brain development through magnetic resonance imaging (MRI) data in 158 Chinese normal children and adolescents aged 7.26 to 22.80 years (mean age 15.03+/-4.70 years, 78 boys and 80 girls). Gender groups were matched for measures of age, handedness, education level. The customized brain templates, including T I-weighted image and gray matter (GM)/white matter (WM)/cerebro-spinal fluid (CSF) prior probability maps, were created from all participants. Results showed that the total intracranial volume (TIV), global absolute GM and global WM volume in girls were significantly smaller than those in boys. The hippocampus grew faster in girls than that in boys, but the amygdala grew faster in boys than that in girls. The rate of regional GM decreases with age was steeper in the left superior parietal lobule, bilateral inferior parietal lobule, left precuneus, and bilateral supramarginal gyrus in boys compared to girls, which was possibly related to better spatial processing ability in boys. Regional GM volumes were greater in bilateral superior temporal gyrus, bilateral inferior frontal gyrus and bilateral middle frontal gyrus in girls. Regional WM volumes were greater in the left temporal lobe, right inferior parietal and bilateral middle frontal gyrus in girls. The gender differences in the temporal and frontal lobe maybe be related to better language ability in girls. These findings may aid in understanding the differences in cognitive function between boys and girls.

  3. Creatine Deficiency Syndrome could be Missed Easily: A Case Report of Guanidinoacetate Methyltransferase Deficiency Presented with Neurodevelopmental Delay, Seizures, and Behavioral Changes, but Normal Structural MRI.

    PubMed

    Pacheva, Iliyana; Ivanov, Ivan; Penkov, Marin; Kancheva, Daliya; Jordanova, Albena; Ivanova, Mariya

    2016-09-01

    A case with GAMT deficiency (homozygous c.64dupG mutation) presented with neurodevelopmental delay, rare seizures, behavioral disturbances, and mild hypotonia, posing diagnostic challenges. Metabolic investigations showed low creatinine in plasma and urine (guanidinoacetate couldn't be investigated) and slightly elevated lactate. MRI was normal. Correct diagnosis was possible only after MR spectroscopy was performed at age 5½ years. A homozygous c.64dupG mutation of the GAMT gene was identified in the proband. In conclusion, every case with neurodevelopmental delay or arrest, especially when accompanied by seizures, behavioral impairment, muscle hypotonia or extrapyramidal symptoms should undergo MRI with MR spectroscopy. Normal structural MRI doesn't exclude a creatine deficiency syndrome. Biochemical investigations of guanidinoacetate, creatine, and creatinine in body fluid should be done to diagnose cerebral creatine deficiency syndromes and to specify the deficient enzyme. Thus, a treatable disease will not be missed. PMID:27650626

  4. Standardized evaluation of algorithms for computer-aided diagnosis of dementia based on structural MRI: the CADDementia challenge.

    PubMed

    Bron, Esther E; Smits, Marion; van der Flier, Wiesje M; Vrenken, Hugo; Barkhof, Frederik; Scheltens, Philip; Papma, Janne M; Steketee, Rebecca M E; Méndez Orellana, Carolina; Meijboom, Rozanna; Pinto, Madalena; Meireles, Joana R; Garrett, Carolina; Bastos-Leite, António J; Abdulkadir, Ahmed; Ronneberger, Olaf; Amoroso, Nicola; Bellotti, Roberto; Cárdenas-Peña, David; Álvarez-Meza, Andrés M; Dolph, Chester V; Iftekharuddin, Khan M; Eskildsen, Simon F; Coupé, Pierrick; Fonov, Vladimir S; Franke, Katja; Gaser, Christian; Ledig, Christian; Guerrero, Ricardo; Tong, Tong; Gray, Katherine R; Moradi, Elaheh; Tohka, Jussi; Routier, Alexandre; Durrleman, Stanley; Sarica, Alessia; Di Fatta, Giuseppe; Sensi, Francesco; Chincarini, Andrea; Smith, Garry M; Stoyanov, Zhivko V; Sørensen, Lauge; Nielsen, Mads; Tangaro, Sabina; Inglese, Paolo; Wachinger, Christian; Reuter, Martin; van Swieten, John C; Niessen, Wiro J; Klein, Stefan

    2015-05-01

    Algorithms for computer-aided diagnosis of dementia based on structural MRI have demonstrated high performance in the literature, but are difficult to compare as different data sets and methodology were used for evaluation. In addition, it is unclear how the algorithms would perform on previously unseen data, and thus, how they would perform in clinical practice when there is no real opportunity to adapt the algorithm to the data at hand. To address these comparability, generalizability and clinical applicability issues, we organized a grand challenge that aimed to objectively compare algorithms based on a clinically representative multi-center data set. Using clinical practice as the starting point, the goal was to reproduce the clinical diagnosis. Therefore, we evaluated algorithms for multi-class classification of three diagnostic groups: patients with probable Alzheimer's disease, patients with mild cognitive impairment and healthy controls. The diagnosis based on clinical criteria was used as reference standard, as it was the best available reference despite its known limitations. For evaluation, a previously unseen test set was used consisting of 354 T1-weighted MRI scans with the diagnoses blinded. Fifteen research teams participated with a total of 29 algorithms. The algorithms were trained on a small training set (n=30) and optionally on data from other sources (e.g., the Alzheimer's Disease Neuroimaging Initiative, the Australian Imaging Biomarkers and Lifestyle flagship study of aging). The best performing algorithm yielded an accuracy of 63.0% and an area under the receiver-operating-characteristic curve (AUC) of 78.8%. In general, the best performances were achieved using feature extraction based on voxel-based morphometry or a combination of features that included volume, cortical thickness, shape and intensity. The challenge is open for new submissions via the web-based framework: http://caddementia.grand-challenge.org.

  5. MRI assessment of suppression of structural damage in patients with rheumatoid arthritis receiving rituximab: results from the randomised, placebo-controlled, double-blind RA-SCORE study

    PubMed Central

    Peterfy, Charles; Emery, Paul; Tak, Paul P; Østergaard, Mikkel; DiCarlo, Julie; Otsa, Kati; Navarro Sarabia, Federico; Pavelka, Karel; Bagnard, Marie-Agnes; Gylvin, Lykke Hinsch; Bernasconi, Corrado; Gabriele, Annarita

    2016-01-01

    Objective To evaluate changes in structural damage and joint inflammation assessed by MRI following rituximab treatment in a Phase 3 study of patients with active rheumatoid arthritis (RA) despite methotrexate (MTX) who were naive to biological therapy. Methods Patients were randomised to receive two infusions of placebo (n=63), rituximab 500 mg (n=62), or rituximab 1000 mg (n=60) intravenously on days 1 and 15. MRI scans and radiographs of the most inflamed hand and wrist were acquired at baseline, weeks 12 (MRI only), 24 and 52. The primary end point was the change in MRI erosion score from baseline at week 24. Results Patients treated with rituximab demonstrated significantly less progression in the mean MRI erosion score compared with those treated with placebo at weeks 24 (0.47, 0.18 and 1.60, respectively, p=0.003 and p=0.001 for the two rituximab doses vs placebo) and 52 (−0.30, 0.11 and 3.02, respectively; p<0.001 and p<0.001). Cartilage loss at 52 weeks was significantly reduced in the rituximab group compared with the placebo group. Other secondary end points of synovitis and osteitis improved significantly with rituximab compared with placebo as early as 12 weeks and improved further at weeks 24 and 52. Conclusions This study demonstrated that rituximab significantly reduced erosion and cartilage loss at week 24 and week 52 in MTX-inadequate responder patients with active RA, suggesting that MRI is a valuable tool for assessing inflammatory and structural damage in patients with established RA receiving rituximab. Trial registration number NCT00578305 PMID:25355728

  6. Microstructural parameter estimation in vivo using diffusion MRI and structured prior information

    PubMed Central

    Nagy, Zoltan; Weiskopf, Nikolaus; Alexander, Daniel C.; Clark, Chris A.

    2015-01-01

    Purpose Diffusion MRI has recently been used with detailed models to probe tissue microstructure. Much of this work has been performed ex vivo with powerful scanner hardware, to gain sensitivity to parameters such as axon radius. By contrast, performing microstructure imaging on clinical scanners is extremely challenging. Methods We use an optimized dual spin‐echo diffusion protocol, and a Bayesian fitting approach, to obtain reproducible contrast (histogram overlap of up to 92%) in estimated maps of axon radius index in healthy adults at a modest, widely‐available gradient strength (35 mT m −1). A key innovation is the use of influential priors. Results We demonstrate that our priors can improve precision in axon radius estimates—a 7‐fold reduction in voxelwise coefficient of variation in vivo—without significant bias. Our results may reflect true axon radius differences between white matter regions, but this interpretation should be treated with caution due to the complexity of the tissue relative to our model. Conclusions Some sensitivity to relatively large axons (3–15 μm) may be available at clinical field and gradient strengths. Future applications at higher gradient strength will benefit from the favorable eddy current properties of the dual spin‐echo sequence, and greater precision available with suitable priors. Magn Reson Med, 2015. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Magn Reson Med 75:1787–1796, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance. PMID:25994918

  7. Wavelet based characterization of ex vivo vertebral trabecular bone structure with 3T MRI compared to microCT

    SciTech Connect

    Krug, R; Carballido-Gamio, J; Burghardt, A; Haase, S; Sedat, J W; Moss, W C; Majumdar, S

    2005-04-11

    Trabecular bone structure and bone density contribute to the strength of bone and are important in the study of osteoporosis. Wavelets are a powerful tool to characterize and quantify texture in an image. In this study the thickness of trabecular bone was analyzed in 8 cylindrical cores of the vertebral spine. Images were obtained from 3 Tesla (T) magnetic resonance imaging (MRI) and micro-computed tomography ({micro}CT). Results from the wavelet based analysis of trabecular bone were compared with standard two-dimensional structural parameters (analogous to bone histomorphometry) obtained using mean intercept length (MR images) and direct 3D distance transformation methods ({micro}CT images). Additionally, the bone volume fraction was determined from MR images. We conclude that the wavelet based analyses delivers comparable results to the established MR histomorphometric measurements. The average deviation in trabecular thickness was less than one pixel size between the wavelet and the standard approach for both MR and {micro}CT analysis. Since the wavelet based method is less sensitive to image noise, we see an advantage of wavelet analysis of trabecular bone for MR imaging when going to higher resolution.

  8. Linking contemporary high resolution magnetic resonance imaging to the von Economo legacy: A study on the comparison of MRI cortical thickness and histological measurements of cortical structure.

    PubMed

    Scholtens, Lianne H; de Reus, Marcel A; van den Heuvel, Martijn P

    2015-08-01

    The cerebral cortex is a distinctive part of the mammalian nervous system, displaying a spatial variety in cyto-, chemico-, and myelinoarchitecture. As part of a rich history of histological findings, pioneering anatomists von Economo and Koskinas provided detailed mappings on the cellular structure of the human cortex, reporting on quantitative aspects of cytoarchitecture of cortical areas. Current day investigations into the structure of human cortex have embraced technological advances in Magnetic Resonance Imaging (MRI) to assess macroscale thickness and organization of the cortical mantle in vivo. However, direct comparisons between current day MRI estimates and the quantitative measurements of early anatomists have been limited. Here, we report on a simple, but nevertheless important cross-analysis between the histological reports of von Economo and Koskinas on variation in thickness of the cortical mantle and MRI derived measurements of cortical thickness. We translated the von Economo cortical atlas to a subdivision of the commonly used Desikan-Killiany atlas (as part of the FreeSurfer Software package and a commonly used parcellation atlas in studies examining MRI cortical thickness). Next, values of "width of the cortical mantle" as provided by the measurements of von Economo and Koskinas were correlated to cortical thickness measurements derived from high-resolution anatomical MRI T1 data of 200+ subjects of the Human Connectome Project (HCP). Cross-correlation revealed a significant association between group-averaged MRI measurements of cortical thickness and histological recordings (r = 0.54, P < 0.001). Further validating such a correlation, we manually segmented the von Economo parcellation atlas on the standardized Colin27 brain dataset and applied the obtained three-dimensional von Economo segmentation atlas to the T1 data of each of the HCP subjects. Highly consistent with our findings for the mapping to the Desikan-Killiany regions, cross

  9. Marked effects of intracranial volume correction methods on sex differences in neuroanatomical structures: a HUNT MRI study

    PubMed Central

    Pintzka, Carl W. S.; Hansen, Tor I.; Evensmoen, Hallvard R.; Håberg, Asta K.

    2015-01-01

    To date, there is no consensus whether sexual dimorphism in the size of neuroanatomical structures exists, or if such differences are caused by choice of intracranial volume (ICV) correction method. When investigating volume differences in neuroanatomical structures, corrections for variation in ICV are used. Commonly applied methods are the ICV-proportions, ICV-residuals and ICV as a covariate of no interest, ANCOVA. However, these different methods give contradictory results with regard to presence of sex differences. Our aims were to investigate presence of sexual dimorphism in 18 neuroanatomical volumes unrelated to ICV-differences by using a large ICV-matched subsample of 304 men and women from the HUNT-MRI general population study, and further to demonstrate in the entire sample of 966 healthy subjects, which of the ICV-correction methods gave results similar to the ICV-matched subsample. In addition, sex-specific subsamples were created to investigate whether differences were an effect of head size or sex. Most sex differences were related to volume scaling with ICV, independent of sex. Sex differences were detected in a few structures; amygdala, cerebellar cortex, and 3rd ventricle were larger in men, but the effect sizes were small. The residuals and ANCOVA methods were most effective at removing the effects of ICV. The proportions method suffered from systematic errors due to lack of proportionality between ICV and neuroanatomical volumes, leading to systematic mis-assignment of structures as either larger or smaller than their actual size. Adding additional sexual dimorphic covariates to the ANCOVA gave opposite results of those obtained in the ICV-matched subsample or with the residuals method. The findings in the current study explain some of the considerable variation in the literature on sexual dimorphisms in neuroanatomical volumes. In conclusion, sex plays a minor role for neuroanatomical volume differences; most differences are related to ICV

  10. Cortical Structural Connectivity Alterations in Primary Insomnia: Insights from MRI-Based Morphometric Correlation Analysis.

    PubMed

    Zhao, Lu; Wang, Enfeng; Zhang, Xiaoqi; Karama, Sherif; Khundrakpam, Budhachandra; Zhang, Hongju; Guan, Min; Wang, Meiyun; Cheng, Jingliang; Shi, Dapeng; Evans, Alan C; Li, Yongli

    2015-01-01

    The etiology and maintenance of insomnia are proposed to be associated with increased cognitive and physiological arousal caused by acute stressors and associated cognitive rumination. A core feature of such hyperarousal theory of insomnia involves increased sensory processing that interferes with the onset and maintenance of sleep. In this work, we collected structural magnetic resonance imaging data from 35 patients with primary insomnia and 35 normal sleepers and applied structural covariance analysis to investigate whether insomnia is associated with disruptions in structural brain networks centered at the sensory regions (primary visual, primary auditory, and olfactory cortex). As expected, insomnia patients showed increased structural covariance in cortical thickness between sensory and motor regions. We also observed trends of increased covariance between sensory regions and the default-mode network, and the salience network regions, and trends of decreased covariance between sensory regions and the frontoparietal working memory network regions, in insomnia patients. The observed changes in structural covariance tended to correlated with poor sleep quality. Our findings support previous functional neuroimaging studies and provide novel insights into variations in brain network configuration that may be involved in the pathophysiology of insomnia.

  11. Cortical Structural Connectivity Alterations in Primary Insomnia: Insights from MRI-Based Morphometric Correlation Analysis

    PubMed Central

    Zhao, Lu; Wang, Enfeng; Zhang, Xiaoqi; Karama, Sherif; Khundrakpam, Budhachandra; Zhang, Hongju; Guan, Min; Wang, Meiyun; Cheng, Jingliang; Shi, Dapeng; Evans, Alan C.; Li, Yongli

    2015-01-01

    The etiology and maintenance of insomnia are proposed to be associated with increased cognitive and physiological arousal caused by acute stressors and associated cognitive rumination. A core feature of such hyperarousal theory of insomnia involves increased sensory processing that interferes with the onset and maintenance of sleep. In this work, we collected structural magnetic resonance imaging data from 35 patients with primary insomnia and 35 normal sleepers and applied structural covariance analysis to investigate whether insomnia is associated with disruptions in structural brain networks centered at the sensory regions (primary visual, primary auditory, and olfactory cortex). As expected, insomnia patients showed increased structural covariance in cortical thickness between sensory and motor regions. We also observed trends of increased covariance between sensory regions and the default-mode network, and the salience network regions, and trends of decreased covariance between sensory regions and the frontoparietal working memory network regions, in insomnia patients. The observed changes in structural covariance tended to correlated with poor sleep quality. Our findings support previous functional neuroimaging studies and provide novel insights into variations in brain network configuration that may be involved in the pathophysiology of insomnia. PMID:26539528

  12. Cortical Structural Connectivity Alterations in Primary Insomnia: Insights from MRI-Based Morphometric Correlation Analysis.

    PubMed

    Zhao, Lu; Wang, Enfeng; Zhang, Xiaoqi; Karama, Sherif; Khundrakpam, Budhachandra; Zhang, Hongju; Guan, Min; Wang, Meiyun; Cheng, Jingliang; Shi, Dapeng; Evans, Alan C; Li, Yongli

    2015-01-01

    The etiology and maintenance of insomnia are proposed to be associated with increased cognitive and physiological arousal caused by acute stressors and associated cognitive rumination. A core feature of such hyperarousal theory of insomnia involves increased sensory processing that interferes with the onset and maintenance of sleep. In this work, we collected structural magnetic resonance imaging data from 35 patients with primary insomnia and 35 normal sleepers and applied structural covariance analysis to investigate whether insomnia is associated with disruptions in structural brain networks centered at the sensory regions (primary visual, primary auditory, and olfactory cortex). As expected, insomnia patients showed increased structural covariance in cortical thickness between sensory and motor regions. We also observed trends of increased covariance between sensory regions and the default-mode network, and the salience network regions, and trends of decreased covariance between sensory regions and the frontoparietal working memory network regions, in insomnia patients. The observed changes in structural covariance tended to correlated with poor sleep quality. Our findings support previous functional neuroimaging studies and provide novel insights into variations in brain network configuration that may be involved in the pathophysiology of insomnia. PMID:26539528

  13. Brain development in preterm infants assessed using advanced MRI techniques.

    PubMed

    Tusor, Nora; Arichi, Tomoki; Counsell, Serena J; Edwards, A David

    2014-03-01

    Infants who are born preterm have a high incidence of neurocognitive and neurobehavioral abnormalities, which may be associated with impaired brain development. Advanced magnetic resonance imaging (MRI) approaches, such as diffusion MRI (d-MRI) and functional MRI (fMRI), provide objective and reproducible measures of brain development. Indices derived from d-MRI can be used to provide quantitative measures of preterm brain injury. Although fMRI of the neonatal brain is currently a research tool, future studies combining d-MRI and fMRI have the potential to assess the structural and functional properties of the developing brain and its response to injury.

  14. In vitro flow assessment: from PC-MRI to computational fluid dynamics including fluid-structure interaction

    NASA Astrophysics Data System (ADS)

    Kratzke, Jonas; Rengier, Fabian; Weis, Christian; Beller, Carsten J.; Heuveline, Vincent

    2016-04-01

    Initiation and development of cardiovascular diseases can be highly correlated to specific biomechanical parameters. To examine and assess biomechanical parameters, numerical simulation of cardiovascular dynamics has the potential to complement and enhance medical measurement and imaging techniques. As such, computational fluid dynamics (CFD) have shown to be suitable to evaluate blood velocity and pressure in scenarios, where vessel wall deformation plays a minor role. However, there is a need for further validation studies and the inclusion of vessel wall elasticity for morphologies being subject to large displacement. In this work, we consider a fluid-structure interaction (FSI) model including the full elasticity equation to take the deformability of aortic wall soft tissue into account. We present a numerical framework, in which either a CFD study can be performed for less deformable aortic segments or an FSI simulation for regions of large displacement such as the aortic root and arch. Both of the methods are validated by means of an aortic phantom experiment. The computational results are in good agreement with 2D phase-contrast magnetic resonance imaging (PC-MRI) velocity measurements as well as catheter-based pressure measurements. The FSI simulation shows a characteristic vessel compliance effect on the flow field induced by the elasticity of the vessel wall, which the CFD model is not capable of. The in vitro validated FSI simulation framework can enable the computation of complementary biomechanical parameters such as the stress distribution within the vessel wall.

  15. Control-group feature normalization for multivariate pattern analysis of structural MRI data using the support vector machine.

    PubMed

    Linn, Kristin A; Gaonkar, Bilwaj; Satterthwaite, Theodore D; Doshi, Jimit; Davatzikos, Christos; Shinohara, Russell T

    2016-05-15

    Normalization of feature vector values is a common practice in machine learning. Generally, each feature value is standardized to the unit hypercube or by normalizing to zero mean and unit variance. Classification decisions based on support vector machines (SVMs) or by other methods are sensitive to the specific normalization used on the features. In the context of multivariate pattern analysis using neuroimaging data, standardization effectively up- and down-weights features based on their individual variability. Since the standard approach uses the entire data set to guide the normalization, it utilizes the total variability of these features. This total variation is inevitably dependent on the amount of marginal separation between groups. Thus, such a normalization may attenuate the separability of the data in high dimensional space. In this work we propose an alternate approach that uses an estimate of the control-group standard deviation to normalize features before training. We study our proposed approach in the context of group classification using structural MRI data. We show that control-based normalization leads to better reproducibility of estimated multivariate disease patterns and improves the classifier performance in many cases.

  16. The association of brain structure with gait velocity in older adults: a quantitative volumetric analysis of brain MRI

    PubMed Central

    Katz, Mindy J.; Lipton, Michael L.; Lipton, Richard B.; Verghese, Joe

    2015-01-01

    Introduction While cortical processes play an important role in controlling locomotion, the underlying structural brain changes associated with slowing of gait in aging are not yet fully established. Our study aimed to examine the relationship between cortical gray matter volume (GM), white matter volume (WM), ventricular volume (VV), hippocampal and hippocampal subfield volumes, and gait velocity in older adults free of dementia. Methods Gait and cognitive performance was tested in 112 community-residing adults, age 70 years and over, participating in the Einstein Aging Study. Gait velocity (cm/s) was obtained using an instrumented walkway. Volumetric MRI measures were estimated using a FreeSurfer software. We examined the cross-sectional relationship of GM, WM, VV, and hippocampal total and subfield volumes and gait velocity using linear regression models. In complementary models, the effect of memory performance on the relationship between gait velocity and regional volumes was evaluated. Results Slower gait velocity was associated with smaller cortical GM and total hippocampal volumes. There was no association between gait velocity and WM or VV. Among hippocampal subfields, only smaller presubiculum volume was significantly associated with decrease in gait velocity. Addition of the memory performance to the models attenuated the association between gait velocity and all volumetric measures. Conclusions Our findings indicate that total GM and hippocampal volumes as well as specific hippocampal subfield volumes are inversely associated with locomotor function. These associations are probably affected by cognitive status of study population. PMID:25921321

  17. Gauging MRI

    NASA Astrophysics Data System (ADS)

    Herron, Ison; Goodman, Jeremy

    2009-11-01

    Axisymmetric stability of viscous resistive magnetized Couette flow is re-examined, with emphasis on flows that would be hydrodynamically stable according to Rayleigh's criterion: opposing gradients of angular velocity and specific angular momentum. A uniform axial magnetic field permeates the fluid. In this regime, magnetorotational instability (MRI) may occur. It is proved that MRI is suppressed, in fact no instability at all occurs, with insulating boundary conditions, when the magnetic resistivity is sufficiently large. This shows conclusively that small magnetic dissipation is a feature of this instability for all magnetic Prandtl numbers. A criterion is provided for the onset of MRI.

  18. Musculoskeletal MRI.

    PubMed

    Sage, Jaime E; Gavin, Patrick

    2016-05-01

    MRI has the unique ability to detect abnormal fluid content, and is therefore unparalleled in its role of detection, diagnosis, prognosis, treatment planning and follow-up evaluation of musculoskeletal disease. MRI in companion animals should be considered in the following circumstances: a definitive diagnosis cannot be made on radiographs; a patient is nonresponsive to medical or surgical therapy; prognostic information is desired; assessing surgical margins and traumatic and/or infectious joint and bone disease; ruling out subtle developmental or early aggressive bone lesions. The MRI features of common disorders affecting the shoulder, elbow, stifle, carpal, and tarsal joints are included in this chapter.

  19. Intraoperative MRI and functional mapping.

    PubMed

    Gasser, Thomas; Szelenyi, Andrea; Senft, Christian; Muragaki, Yoshihiro; Sandalcioglu, I Erol; Sure, Ulrich; Nimsky, Christopher; Seifert, Volker

    2011-01-01

    The integration of functional and anatomical data into neuronavigation is an established standard of care in many neurosurgical departments. Yet, this method has limitations as in most cases the data are acquired prior to surgery. Due to brain-shift the accurate presentation of functional as well as anatomical structures declines in the course of surgery. In consequence, the acquisition of information during surgery about the brain's current functional state is of specific interest. The advancement of imaging technologies (e.g. fMRI, MEG, Intraoperative Optical Intrinsic Signal Imaging--IOIS) and neurophysiological techniques and the advent of intraoperative MRI all had a major impact on neurosurgery. The combination of modalities such as neurophysiology and intraoperative MRI (ioMRI), as well as the acquisition of functional MRI during surgery (ifMRI) are in the focus of this work. Especially the technical aspects and safety issues are elucidated.

  20. Structural MRI-Based Predictions in Patients with Treatment-Refractory Depression (TRD)

    PubMed Central

    Johnston, Blair A.; Steele, J. Douglas; Tolomeo, Serenella; Christmas, David; Matthews, Keith

    2015-01-01

    The application of machine learning techniques to psychiatric neuroimaging offers the possibility to identify robust, reliable and objective disease biomarkers both within and between contemporary syndromal diagnoses that could guide routine clinical practice. The use of quantitative methods to identify psychiatric biomarkers is consequently important, particularly with a view to making predictions relevant to individual patients, rather than at a group-level. Here, we describe predictions of treatment-refractory depression (TRD) diagnosis using structural T1-weighted brain scans obtained from twenty adult participants with TRD and 21 never depressed controls. We report 85% accuracy of individual subject diagnostic prediction. Using an automated feature selection method, the major brain regions supporting this significant classification were in the caudate, insula, habenula and periventricular grey matter. It was not, however, possible to predict the degree of ‘treatment resistance’ in individual patients, at least as quantified by the Massachusetts General Hospital (MGH-S) clinical staging method; but the insula was again identified as a region of interest. Structural brain imaging data alone can be used to predict diagnostic status, but not MGH-S staging, with a high degree of accuracy in patients with TRD. PMID:26186455

  1. Multivariate classification of structural MRI data detects chronic low back pain.

    PubMed

    Ung, Hoameng; Brown, Justin E; Johnson, Kevin A; Younger, Jarred; Hush, Julia; Mackey, Sean

    2014-04-01

    Chronic low back pain (cLBP) has a tremendous personal and socioeconomic impact, yet the underlying pathology remains a mystery in the majority of cases. An objective measure of this condition, that augments self-report of pain, could have profound implications for diagnostic characterization and therapeutic development. Contemporary research indicates that cLBP is associated with abnormal brain structure and function. Multivariate analyses have shown potential to detect a number of neurological diseases based on structural neuroimaging. Therefore, we aimed to empirically evaluate such an approach in the detection of cLBP, with a goal to also explore the relevant neuroanatomy. We extracted brain gray matter (GM) density from magnetic resonance imaging scans of 47 patients with cLBP and 47 healthy controls. cLBP was classified with an accuracy of 76% by support vector machine analysis. Primary drivers of the classification included areas of the somatosensory, motor, and prefrontal cortices--all areas implicated in the pain experience. Differences in areas of the temporal lobe, including bordering the amygdala, medial orbital gyrus, cerebellum, and visual cortex, were also useful for the classification. Our findings suggest that cLBP is characterized by a pattern of GM changes that can have discriminative power and reflect relevant pathological brain morphology.

  2. MRI-based surface area estimates in the normal adult human brain: evidence for structural organisation.

    PubMed Central

    Sisodiya, S; Free, S; Fish, D; Shorvon, S

    1996-01-01

    There are a number of quantitative relationships between geometric parameters describing the structure of the normal human cerebral cortex examined in vivo using volumetric magnetic resonance imaging. A voxel-counting method is used to estimate grey-white interface surface area. The effects of bias associated with the method are considered. In 33 normal controls, the cerebral hemispheres were symmetric in terms of total volume, irrespective of handedness, but not in terms of surface areas for right-handers. The surface area of the grey matter-white matter interface was directly proportional to the cortical grey matter volume, suggesting that growth of the neocortex is primarily tangential, with repetition of a basic structural element rather than gross alterations in the thickness of the cortex. The majority of the surface area of the grey-white interface lies within gyral white matter cores. The mean thickness of the cortex of the right cerebral hemisphere in vivo was 3.0 mm and that of the left 3.3 mm. There was a relationship between the cross-sectional area of the corpus callosum and grey-white interface surface area, suggesting that a fixed proportion and cortical neurons extend interhemispheric axons. These findings suggest that there are general architectural principles governing the organisation of the complex, but ordered, human cerebral cortex. Images Fig. 1 Fig. 2 PMID:8621342

  3. Association of social engagement with brain volumes assessed by structural MRI.

    PubMed

    James, Bryan D; Glass, Thomas A; Caffo, Brian; Bobb, Jennifer F; Davatzikos, Christos; Yousem, David; Schwartz, Brian S

    2012-01-01

    We tested the hypothesis that social engagement is associated with larger brain volumes in a cohort study of 348 older male former lead manufacturing workers (n = 305) and population-based controls (n = 43), age 48 to 82. Social engagement was measured using a summary scale derived from confirmatory factor analysis. The volumes of 20 regions of interest (ROIs), including total brain, total gray matter (GM), total white matter (WM), each of the four lobar GM and WM, and 9 smaller structures were derived from T1-weighted structural magnetic resonance images. Linear regression models adjusted for age, education, race/ethnicity, intracranial volume, hypertension, diabetes, and control (versus lead worker) status. Higher social engagement was associated with larger total brain and GM volumes, specifically temporal and occipital GM, but was not associated with WM volumes except for corpus callosum. A voxel-wise analysis supported an association in temporal lobe GM. Using longitudinal data to discern temporal relations, change in ROI volumes over five years showed null associations with current social engagement. Findings are consistent with the hypothesis that social engagement preserves brain tissue, and not consistent with the alternate hypothesis that persons with smaller or shrinking volumes become less socially engaged, though this scenario cannot be ruled out.

  4. Structural MRI-Based Predictions in Patients with Treatment-Refractory Depression (TRD).

    PubMed

    Johnston, Blair A; Steele, J Douglas; Tolomeo, Serenella; Christmas, David; Matthews, Keith

    2015-01-01

    The application of machine learning techniques to psychiatric neuroimaging offers the possibility to identify robust, reliable and objective disease biomarkers both within and between contemporary syndromal diagnoses that could guide routine clinical practice. The use of quantitative methods to identify psychiatric biomarkers is consequently important, particularly with a view to making predictions relevant to individual patients, rather than at a group-level. Here, we describe predictions of treatment-refractory depression (TRD) diagnosis using structural T1-weighted brain scans obtained from twenty adult participants with TRD and 21 never depressed controls. We report 85% accuracy of individual subject diagnostic prediction. Using an automated feature selection method, the major brain regions supporting this significant classification were in the caudate, insula, habenula and periventricular grey matter. It was not, however, possible to predict the degree of 'treatment resistance' in individual patients, at least as quantified by the Massachusetts General Hospital (MGH-S) clinical staging method; but the insula was again identified as a region of interest. Structural brain imaging data alone can be used to predict diagnostic status, but not MGH-S staging, with a high degree of accuracy in patients with TRD.

  5. Ultra-High Field MRI Post Mortem Structural Connectivity of the Human Subthalamic Nucleus, Substantia Nigra, and Globus Pallidus

    PubMed Central

    Plantinga, Birgit R.; Roebroeck, Alard; Kemper, Valentin G.; Uludağ, Kâmil; Melse, Maartje; Mai, Jürgen; Kuijf, Mark L.; Herrler, Andreas; Jahanshahi, Ali; ter Haar Romeny, Bart M.; Temel, Yasin

    2016-01-01

    Introduction: The subthalamic nucleus, substantia nigra, and globus pallidus, three nuclei of the human basal ganglia, play an important role in motor, associative, and limbic processing. The network of the basal ganglia is generally characterized by a direct, indirect, and hyperdirect pathway. This study aims to investigate the mesoscopic nature of these connections between the subthalamic nucleus, substantia nigra, and globus pallidus and their surrounding structures. Methods: A human post mortem brain specimen including the substantia nigra, subthalamic nucleus, and globus pallidus was scanned on a 7 T MRI scanner. High resolution diffusion weighted images were used to reconstruct the fibers intersecting the substantia nigra, subthalamic nucleus, and globus pallidus. The course and density of these tracks was analyzed. Results: Most of the commonly established projections of the subthalamic nucleus, substantia nigra, and globus pallidus were successfully reconstructed. However, some of the reconstructed fiber tracks such as the connections of the substantia nigra pars compacta to the other included nuclei and the connections with the anterior commissure have not been shown previously. In addition, the quantitative tractography approach showed a typical degree of connectivity previously not documented. An example is the relatively larger projections of the subthalamic nucleus to the substantia nigra pars reticulata when compared to the projections to the globus pallidus internus. Discussion: This study shows that ultra-high field post mortem tractography allows for detailed 3D reconstruction of the projections of deep brain structures in humans. Although the results should be interpreted carefully, the newly identified connections contribute to our understanding of the basal ganglia. PMID:27378864

  6. SU-E-J-230: Evaluation of ViewRay 0.35 T MRI Normal Structure Segmentation

    SciTech Connect

    Paliwal, B; Asprey, W; Yan, Y; Saenz, D; Bayouth, J

    2015-06-15

    Purpose: In order to take advantage of the high resolution soft tissue imaging available in MR images, we investigated 3D images obtained with the low field 0.35 T MR in ViewRay to serve as an alternative to CT scans for radiotherapy treatment planning. In these images, normal and target structure delineation can be visualized. Assessment is based upon comparison with the CT images and the ability to produce comparable contours. Methods: Routine radiation oncology CT scans were acquired on five patients. Contours of brain, brainstem, esophagus, heart, lungs, spinal cord, and the external body were drawn. The same five patients were then scanned on the ViewRay TrueFISP-based imaging pulse sequence. The same organs were selected on the MR images and compared to those from the CT scan. Physical volume and the Dice Similarity Coefficient (DSC) were used to assess the contours from the two systems. Image quality stability was quantitatively ensured throughout the study following the recommendations of the ACR MR accreditation procedure. Results: The highest DSC of 0.985, 0.863, and 0.843 were observed for brain, lungs, and heart respectively. On the other hand, the brainstem, spinal cord, and esophagus had the lowest DSC. Volume agreement was most satisfied for the heart (within 5%) and the brain (within 2%). Contour volume for the brainstem and lung (a widely dynamic organ) varied the most (27% and 19%). Conclusion: The DSC and volume measurements suggest that the results obtained from ViewRay images are quantitatively consistent and comparable to those obtained from CT scans for the brain, heart, and lungs. MR images from ViewRay are well-suited for treatment planning and for adaptive MRI-guided radiotherapy. The physical data from 0.35 T MR imaging is consistent with our geometrical understanding of normal structures.

  7. Alzheimer's disease markers from structural MRI and FDG-PET brain images

    NASA Astrophysics Data System (ADS)

    Chincarini, Andrea; Bosco, Paolo; Gemme, Gianluca; Morbelli, Silvia; Arnaldi, Dario; Sensi, Francesco; Solano, Ilaria; Amoroso, Nicola; Tangaro, Sabina; Longo, Renata; Squarcia, Sandro; Nobili, Flavio

    2012-11-01

    Despite the widespread use of neuroimaging tools (morphological and functional) in the routine diagnostic of cerebral diseases, the information available by the end user -the clinician- remains largely limited to qualitative visual analysis. This restriction greatly reduces the diagnostic impact of neuroimaging in routine clinical practice and increases the risk of misdiagnosis. In this context, researches are focussing on the development of sophisticated automatic analyses able to extract clinically relevant information from the captured data. The identification of biological markers at early stages of Alzheimer's disease (AD) contributes to diagnostic accuracy and adds prognostic value. However, in spite of recent developments, results of structural and functional imaging studies on predicting conversion to AD are not uniform. We provide here an overview of analysis methods and approaches, discussing their contribution to clinical assessment.

  8. Quantitative MRI of the spinal cord and brain in adrenomyeloneuropathy: in vivo assessment of structural changes.

    PubMed

    Castellano, Antonella; Papinutto, Nico; Cadioli, Marcello; Brugnara, Gianluca; Iadanza, Antonella; Scigliuolo, Graziana; Pareyson, Davide; Uziel, Graziella; Köhler, Wolfgang; Aubourg, Patrick; Falini, Andrea; Henry, Roland G; Politi, Letterio S; Salsano, Ettore

    2016-06-01

    Adrenomyeloneuropathy is the late-onset form of X-linked adrenoleukodystrophy, and is considered the most frequent metabolic hereditary spastic paraplegia. In adrenomyeloneuropathy the spinal cord is the main site of pathology. Differently from quantitative magnetic resonance imaging of the brain, little is known about the feasibility and utility of advanced neuroimaging in quantifying the spinal cord abnormalities in hereditary diseases. Moreover, little is known about the subtle pathological changes that can characterize the brain of adrenomyeloneuropathy subjects in the early stages of the disease. We performed a cross-sectional study on 13 patients with adrenomyeloneuropathy and 12 age-matched healthy control subjects who underwent quantitative magnetic resonance imaging to assess the structural changes of the upper spinal cord and brain. Total cord areas from C2-3 to T2-3 level were measured, and diffusion tensor imaging metrics, i.e. fractional anisotropy, mean, axial and radial diffusivity values were calculated in both grey and white matter of spinal cord. In the brain, grey matter regions were parcellated with Freesurfer and average volume and thickness, and mean diffusivity and fractional anisotropy from co-registered diffusion maps were calculated in each region. Brain white matter diffusion tensor imaging metrics were assessed using whole-brain tract-based spatial statistics, and tractography-based analysis on corticospinal tracts. Correlations among clinical, structural and diffusion tensor imaging measures were calculated. In patients total cord area was reduced by 26.3% to 40.2% at all tested levels (P < 0.0001). A mean 16% reduction of spinal cord white matter fractional anisotropy (P ≤ 0.0003) with a concomitant 9.7% axial diffusivity reduction (P < 0.009) and 34.5% radial diffusivity increase (P < 0.009) was observed, suggesting co-presence of axonal degeneration and demyelination. Brain tract-based spatial statistics showed a marked reduction

  9. Functional connectivity analysis in resting state fMRI with echo-state networks and non-metric clustering for network structure recovery

    NASA Astrophysics Data System (ADS)

    Wismüller, Axel; DSouza, Adora M.; Abidin, Anas Z.; Wang, Xixi; Hobbs, Susan K.; Nagarajan, Mahesh B.

    2015-03-01

    Echo state networks (ESN) are recurrent neural networks where the hidden layer is replaced with a fixed reservoir of neurons. Unlike feed-forward networks, neuron training in ESN is restricted to the output neurons alone thereby providing a computational advantage. We demonstrate the use of such ESNs in our mutual connectivity analysis (MCA) framework for recovering the primary motor cortex network associated with hand movement from resting state functional MRI (fMRI) data. Such a framework consists of two steps - (1) defining a pair-wise affinity matrix between different pixel time series within the brain to characterize network activity and (2) recovering network components from the affinity matrix with non-metric clustering. Here, ESNs are used to evaluate pair-wise cross-estimation performance between pixel time series to create the affinity matrix, which is subsequently subject to non-metric clustering with the Louvain method. For comparison, the ground truth of the motor cortex network structure is established with a task-based fMRI sequence. Overlap between the primary motor cortex network recovered with our model free MCA approach and the ground truth was measured with the Dice coefficient. Our results show that network recovery with our proposed MCA approach is in close agreement with the ground truth. Such network recovery is achieved without requiring low-pass filtering of the time series ensembles prior to analysis, an fMRI preprocessing step that has courted controversy in recent years. Thus, we conclude our MCA framework can allow recovery and visualization of the underlying functionally connected networks in the brain on resting state fMRI.

  10. Age-associated differences on structural brain MRI in nondemented individuals from 71 to 103 years.

    PubMed

    Yang, Zixuan; Wen, Wei; Jiang, Jiyang; Crawford, John D; Reppermund, Simone; Levitan, Charlene; Slavin, Melissa J; Kochan, Nicole A; Richmond, Robyn L; Brodaty, Henry; Trollor, Julian N; Sachdev, Perminder S

    2016-04-01

    Successful brain aging in the oldest old (≥90 years) is underexplored. This study examined cross-sectional brain morphological differences from 8th to 11th decades of life in nondemented individuals by high-resolution magnetic resonance imaging. Two hundred seventy-seven nondemented community-dwelling participants (71-103 years) from Sydney Memory and Ageing Study and Sydney Centenarian Study comprised the sample, including a subsample of 160 cognitively high-functioning elders. Relationships between age and magnetic resonance imaging-derived measurements were studied using general linear models; and structural profiles of the ≥90 years were delineated. In full sample and the subsample, significant linear negative relationship of gray matter with age was found, with the greatest age effects in the medial temporal lobe and parietal and occipital cortices. This pattern was further confirmed by comparing directly the ≥90 years to the 71-89 years groups. Significant quadratic age effects on total white matter and white matter hyperintensities were observed. Our study demonstrated heterogeneous differences across brain regions between the oldest old and young old, with an emphasis on hippocampus, temporoposterior cortex, and white matter hyperintensities. PMID:26973107

  11. Genetic risk factors for longitudinal changes in structural MRI in former organolead workers.

    PubMed

    James, Bryan D; Caffo, Brian; Stewart, Walter F; Yousem, David; Davatzikos, Christos; Schwartz, Brian S

    2011-01-01

    This study examined associations between polymorphisms in three genes, apolipoprotein E (APOE), angiotensin converting enzyme (ACE), and vitamin D receptor (VDR), and longitudinal change in brain volumes and white matter lesions (WML) as well as effect modification by cardiovascular factors and tibia lead concentrations. Two MRIs, an average of 5 years apart, were obtained for 317 former organolead workers and 45 population-based controls. Both regions-of-interest and voxel-wise analyses were conducted. APOE ε3/ε4 and ε4/ε4 genotypes were associated with less decline in white matter volumes. There was some evidence of interaction between genetic polymorphisms and cardiovascular risk factors (ACE and high-density lipoprotein; VDR and diabetes) on brain volume decline. The VDR FokI ff genotype was associated with an increase in WML (no association for APOE or ACE). This study expands our understanding of how genetic precursors of dementia and cardiovascular diseases are related to changes in brain structure.

  12. A combined DTI and structural MRI study in medicated-naïve chronic schizophrenia.

    PubMed

    Liu, Xiaoyi; Lai, Yunyao; Wang, Xijin; Hao, Chuanxi; Chen, Lei; Zhou, Zhenyu; Yu, Xin; Hong, Nan

    2014-01-01

    Disconnection in white matter (WM) pathway and alterations in gray matter (GM) structure have been hypothesized as pathogenesis in schizophrenia. However, the relationship between the abnormal WM integrity and the alteration of GM in anatomically connected areas remains uncertain. Moreover, the potential influence of antipsychotic medication on WM anisotropy and cortical morphology was not excluded in previous studies. In this study, a total number of 34 subjects were enrolled, including 17 medicated-naïve chronic schizophrenia patients and 17 healthy controls. Tract-based spatial statistics (TBSS) were applied to investigate the level of WM integrity. The FreeSurfer surface-based analysis was used to determine GM volume, cortical thickness and the surface area of GM regions which corresponded to abnormal WM fiber tracts. We observed that patients possessed lower fractional anisotropy (FA) values in the left inferior fronto-occipital fasciculus (IFOF) and left inferior longitudinal fasciculus (ILF), along with smaller GM volume and cortical thinning in temporal lobe than the healthy controls, which reflected the underlying WM and GM disruption that contributed to the disease. In the patient population, the lower connectivity of ILF and IFOF was positively associated with cortical thickness in left lateral orbitofrontal cortex, superior temporal gyrus and lingual gyrus in males, and positively correlated with GM volume in left lateral orbitofrontal cortex in females. On the other hand, it was negatively correlated with cortical area of middle temporal gyrus in males and temporal pole in females respectively, but not when genders were combined. These findings suggested that abnormal WM integrity and anatomical correspondence of GM alterations in schizophrenia were interdependent on gender-separated analysis in patients with schizophrenia. Moreover, combining TBSS and FreeSurfer might be a useful method to provide significant insight into interacting processes

  13. Assessment of structural connectivity in the preterm brain at term equivalent age using diffusion MRI and T2 relaxometry: a network-based analysis.

    PubMed

    Pannek, Kerstin; Hatzigeorgiou, Xanthy; Colditz, Paul B; Rose, Stephen

    2013-01-01

    Preterm birth is associated with a high prevalence of adverse neurodevelopmental outcome. Non-invasive techniques which can probe the neural correlates underpinning these deficits are required. This can be achieved by measuring the structural network of connections within the preterm infant's brain using diffusion MRI and tractography. We used diffusion MRI and T2 relaxometry to identify connections with altered white matter properties in preterm infants compared to term infants. Diffusion and T2 data were obtained from 9 term neonates and 18 preterm-born infants (born <32 weeks gestational age) at term equivalent age. Probabilistic tractography incorporating multiple fibre orientations was used in combination with the Johns Hopkins neonatal brain atlas to calculate the structural network of connections. Connections of altered diffusivity or T2, as well as their relationship with gestational age at birth and postmenstrual age at the time of MRI, were identified using the network based statistic framework. A total of 433 connections were assessed. FA was significantly reduced in 17, and T2 significantly increased in 18 connections in preterm infants, following correction for multiple comparisons. Cortical networks associated with affected connections mainly involved left frontal and temporal cortical areas: regions which are associated with working memory, verbal comprehension and higher cognitive function--deficits which are often observed later in children and adults born preterm. Gestational age at birth correlated with T2, but not diffusion in several connections. We found no association between diffusion or T2 and postmenstrual age at the time of MRI in preterm infants. This study demonstrates that alterations in the structural network of connections can be identified in preterm infants at term equivalent age, and that incorporation of non-diffusion measures such as T2 in the connectome framework provides complementary information for the assessment of brain

  14. Assessment of Structural Connectivity in the Preterm Brain at Term Equivalent Age Using Diffusion MRI and T2 Relaxometry: A Network-Based Analysis

    PubMed Central

    Pannek, Kerstin; Hatzigeorgiou, Xanthy; Colditz, Paul B.; Rose, Stephen

    2013-01-01

    Preterm birth is associated with a high prevalence of adverse neurodevelopmental outcome. Non-invasive techniques which can probe the neural correlates underpinning these deficits are required. This can be achieved by measuring the structural network of connections within the preterm infant's brain using diffusion MRI and tractography. We used diffusion MRI and T2 relaxometry to identify connections with altered white matter properties in preterm infants compared to term infants. Diffusion and T2 data were obtained from 9 term neonates and 18 preterm-born infants (born <32 weeks gestational age) at term equivalent age. Probabilistic tractography incorporating multiple fibre orientations was used in combination with the Johns Hopkins neonatal brain atlas to calculate the structural network of connections. Connections of altered diffusivity or T2, as well as their relationship with gestational age at birth and postmenstrual age at the time of MRI, were identified using the network based statistic framework. A total of 433 connections were assessed. FA was significantly reduced in 17, and T2 significantly increased in 18 connections in preterm infants, following correction for multiple comparisons. Cortical networks associated with affected connections mainly involved left frontal and temporal cortical areas: regions which are associated with working memory, verbal comprehension and higher cognitive function – deficits which are often observed later in children and adults born preterm. Gestational age at birth correlated with T2, but not diffusion in several connections. We found no association between diffusion or T2 and postmenstrual age at the time of MRI in preterm infants. This study demonstrates that alterations in the structural network of connections can be identified in preterm infants at term equivalent age, and that incorporation of non-diffusion measures such as T2 in the connectome framework provides complementary information for the assessment of brain

  15. Integrating structural and functional imaging for computer assisted detection of prostate cancer on multi-protocol in vivo 3 Tesla MRI

    NASA Astrophysics Data System (ADS)

    Viswanath, Satish; Bloch, B. Nicolas; Rosen, Mark; Chappelow, Jonathan; Toth, Robert; Rofsky, Neil; Lenkinski, Robert; Genega, Elizabeth; Kalyanpur, Arjun; Madabhushi, Anant

    2009-02-01

    Screening and detection of prostate cancer (CaP) currently lacks an image-based protocol which is reflected in the high false negative rates currently associated with blinded sextant biopsies. Multi-protocol magnetic resonance imaging (MRI) offers high resolution functional and structural data about internal body structures (such as the prostate). In this paper we present a novel comprehensive computer-aided scheme for CaP detection from high resolution in vivo multi-protocol MRI by integrating functional and structural information obtained via dynamic-contrast enhanced (DCE) and T2-weighted (T2-w) MRI, respectively. Our scheme is fully-automated and comprises (a) prostate segmentation, (b) multimodal image registration, and (c) data representation and multi-classifier modules for information fusion. Following prostate boundary segmentation via an improved active shape model, the DCE/T2-w protocols and the T2-w/ex vivo histological prostatectomy specimens are brought into alignment via a deformable, multi-attribute registration scheme. T2-w/histology alignment allows for the mapping of true CaP extent onto the in vivo MRI, which is used for training and evaluation of a multi-protocol MRI CaP classifier. The meta-classifier used is a random forest constructed by bagging multiple decision tree classifiers, each trained individually on T2-w structural, textural and DCE functional attributes. 3-fold classifier cross validation was performed using a set of 18 images derived from 6 patient datasets on a per-pixel basis. Our results show that the results of CaP detection obtained from integration of T2-w structural textural data and DCE functional data (area under the ROC curve of 0.815) significantly outperforms detection based on either of the individual modalities (0.704 (T2-w) and 0.682 (DCE)). It was also found that a meta-classifier trained directly on integrated T2-w and DCE data (data-level integration) significantly outperformed a decision-level meta

  16. Using voxel-based morphometry to map the structural changes associated with rapid conversion in MCI: a longitudinal MRI study.

    PubMed

    Chételat, G; Landeau, B; Eustache, F; Mézenge, F; Viader, F; de la Sayette, V; Desgranges, B; Baron, J-C

    2005-10-01

    Capturing the dynamics of gray matter (GM) atrophy in relation to the conversion from mild cognitive impairment (MCI) to clinically probable Alzheimer's disease (AD) would be of considerable interest. In this prospective study we have used a novel longitudinal voxel-based method to map the progression of GM loss in MCI patients over time and compared converters to non-converters. Eighteen amnestic MCI patients were followed-up for a predefined fixed period of 18 months and conversion was judged according to NINCDS-ADRDA criteria for probable AD. Each patient underwent a high-resolution T1-weighted volume MRI scan both at entry in the study and 18 months later. We used an optimal VBM protocol to compare baseline imaging data of converters to those of non-converters. Moreover, to map GM loss from baseline to follow-up assessment, we used a modified voxel-based morphometry (VBM) procedure specially designed for longitudinal studies. At the end of the follow-up period, seven patients had converted to probable AD. Areas of lower baseline GM value in converters mainly included the hippocampus, parahippocampal cortex, and lingual and fusiform gyri. Regions of significant GM loss over the 18-month follow-up period common to both converters and non-converters included the temporal neocortex, parahippocampal cortex, orbitofrontal and inferior parietal areas, and the left thalamus. However, there was significantly greater GM loss in converters relative to non-converters in the hippocampal area, inferior and middle temporal gyrus, posterior cingulate, and precuneus. This accelerated atrophy may result from both neurofibrillary tangles accumulation and parallel pathological processes such as functional alteration in the posterior cingulate. The ability to longitudinally assess GM changes in MCI offers new perspectives to better understand the pathological processes underlying AD and to monitor the effects of treatment on brain structure.

  17. Multiclass Classification for the Differential Diagnosis on the ADHD Subtypes Using Recursive Feature Elimination and Hierarchical Extreme Learning Machine: Structural MRI Study

    PubMed Central

    Qureshi, Muhammad Naveed Iqbal; Min, Beomjun; Jo, Hang Joon; Lee, Boreom

    2016-01-01

    The classification of neuroimaging data for the diagnosis of certain brain diseases is one of the main research goals of the neuroscience and clinical communities. In this study, we performed multiclass classification using a hierarchical extreme learning machine (H-ELM) classifier. We compared the performance of this classifier with that of a support vector machine (SVM) and basic extreme learning machine (ELM) for cortical MRI data from attention deficit/hyperactivity disorder (ADHD) patients. We used 159 structural MRI images of children from the publicly available ADHD-200 MRI dataset. The data consisted of three types, namely, typically developing (TDC), ADHD-inattentive (ADHD-I), and ADHD-combined (ADHD-C). We carried out feature selection by using standard SVM-based recursive feature elimination (RFE-SVM) that enabled us to achieve good classification accuracy (60.78%). In this study, we found the RFE-SVM feature selection approach in combination with H-ELM to effectively enable the acquisition of high multiclass classification accuracy rates for structural neuroimaging data. In addition, we found that the most important features for classification were the surface area of the superior frontal lobe, and the cortical thickness, volume, and mean surface area of the whole cortex. PMID:27500640

  18. Multiclass Classification for the Differential Diagnosis on the ADHD Subtypes Using Recursive Feature Elimination and Hierarchical Extreme Learning Machine: Structural MRI Study.

    PubMed

    Qureshi, Muhammad Naveed Iqbal; Min, Beomjun; Jo, Hang Joon; Lee, Boreom

    2016-01-01

    The classification of neuroimaging data for the diagnosis of certain brain diseases is one of the main research goals of the neuroscience and clinical communities. In this study, we performed multiclass classification using a hierarchical extreme learning machine (H-ELM) classifier. We compared the performance of this classifier with that of a support vector machine (SVM) and basic extreme learning machine (ELM) for cortical MRI data from attention deficit/hyperactivity disorder (ADHD) patients. We used 159 structural MRI images of children from the publicly available ADHD-200 MRI dataset. The data consisted of three types, namely, typically developing (TDC), ADHD-inattentive (ADHD-I), and ADHD-combined (ADHD-C). We carried out feature selection by using standard SVM-based recursive feature elimination (RFE-SVM) that enabled us to achieve good classification accuracy (60.78%). In this study, we found the RFE-SVM feature selection approach in combination with H-ELM to effectively enable the acquisition of high multiclass classification accuracy rates for structural neuroimaging data. In addition, we found that the most important features for classification were the surface area of the superior frontal lobe, and the cortical thickness, volume, and mean surface area of the whole cortex. PMID:27500640

  19. Portable MRI

    SciTech Connect

    Espy, Michelle A.

    2012-06-29

    This project proposes to: (1) provide the power of MRI to situations where it presently isn't available; (2) perform the engineering required to move from lab to a functional prototype; and (3) leverage significant existing infrastructure and capability in ultra-low field MRI. The reasons for doing this: (1) MRI is the most powerful tool for imaging soft-tissue (e.g. brain); (2) Billions don't have access due to cost or safety issues; (3) metal will heat/move in high magnetic fields; (4) Millions of cases of traumatic brain injury in US alone; (5) even more of non-traumatic brain injury; (6) (e.g. stroke, infection, chemical exposure); (7) Need for early diagnostic; (8) 'Signature' wound of recent conflicts; (9) 22% of injuries; (10) Implications for post-traumatic stress disorder; and (11) chronic traumatic encephalopathy.

  20. Methods for Acquiring Structural MRI Data in Very Young Children with Autism without the Use of Sedation

    ERIC Educational Resources Information Center

    Nordahl, Christine Wu; Simon, Tony J.; Zierhut, Cynthia; Solomon, Marjorie; Rogers, Sally J.; Amaral, David G.

    2008-01-01

    We describe a protocol with which we achieved a 93% success rate in acquiring high quality MRI scans without the use of sedation in 2.5-4.5 year old children with autism, developmental delays, and typical development. Our main strategy was to conduct MRIs during natural nocturnal sleep in the evenings after the child's normal bedtime.…

  1. Corpus Callosum Area and Brain Volume in Autism Spectrum Disorder: Quantitative Analysis of Structural MRI from the ABIDE Database

    ERIC Educational Resources Information Center

    Kucharsky Hiess, R.; Alter, R.; Sojoudi, S.; Ardekani, B. A.; Kuzniecky, R.; Pardoe, H. R.

    2015-01-01

    Reduced corpus callosum area and increased brain volume are two commonly reported findings in autism spectrum disorder (ASD). We investigated these two correlates in ASD and healthy controls using T1-weighted MRI scans from the Autism Brain Imaging Data Exchange (ABIDE). Automated methods were used to segment the corpus callosum and intracranial…

  2. Structural and Perfusion Abnormalities of Brain on MRI and Technetium-99m-ECD SPECT in Children With Cerebral Palsy: A Comparative Study.

    PubMed

    Rana, Kamer Singh; Narwal, Varun; Chauhan, Lokesh; Singh, Giriraj; Sharma, Monica; Chauhan, Suneel

    2016-04-01

    Cerebral palsy has traditionally been associated with hypoxic ischemic brain damage. This study was undertaken to demonstrate structural and perfusion brain abnormalities. Fifty-six children diagnosed clinically as having cerebral palsy were studied between 1 to 14 years of age and were subjected to 3 Tesla magnetic resonance imaging (MRI). Brain and Technetium-99m-ECD brain single-photon emission computed tomography (SPECT) scan. Male to female ratio was 1.8:1 with a mean age of 4.16 ± 2.274 years. Spastic cerebral palsy was the most common type, observed in 91%. Birth asphyxia was the most common etiology (69.6%). White matter changes (73.2%) such as periventricular leukomalacia and corpus callosal thinning were the most common findings on MRI. On SPECT all cases except one revealed perfusion impairments in different regions of brain. MRI is more sensitive in detecting white matter changes, whereas SPECT is better in detecting cortical and subcortical gray matter abnormalities of perfusion.

  3. Structural and Perfusion Abnormalities of Brain on MRI and Technetium-99m-ECD SPECT in Children With Cerebral Palsy: A Comparative Study.

    PubMed

    Rana, Kamer Singh; Narwal, Varun; Chauhan, Lokesh; Singh, Giriraj; Sharma, Monica; Chauhan, Suneel

    2016-04-01

    Cerebral palsy has traditionally been associated with hypoxic ischemic brain damage. This study was undertaken to demonstrate structural and perfusion brain abnormalities. Fifty-six children diagnosed clinically as having cerebral palsy were studied between 1 to 14 years of age and were subjected to 3 Tesla magnetic resonance imaging (MRI). Brain and Technetium-99m-ECD brain single-photon emission computed tomography (SPECT) scan. Male to female ratio was 1.8:1 with a mean age of 4.16 ± 2.274 years. Spastic cerebral palsy was the most common type, observed in 91%. Birth asphyxia was the most common etiology (69.6%). White matter changes (73.2%) such as periventricular leukomalacia and corpus callosal thinning were the most common findings on MRI. On SPECT all cases except one revealed perfusion impairments in different regions of brain. MRI is more sensitive in detecting white matter changes, whereas SPECT is better in detecting cortical and subcortical gray matter abnormalities of perfusion. PMID:26353878

  4. A Randomized Controlled Trial to Assess Pain and Magnetic Resonance Imaging-Based (MRI-Based) Structural Spine Changes in Low Back Pain Patients After Yoga Practice

    PubMed Central

    Telles, Shirley; Bhardwaj, Abhishek K.; Gupta, Ram K.; Sharma, Sachin K.; Monro, Robin; Balkrishna, Acharya

    2016-01-01

    Background The present study aimed at determining whether 12 weeks of yoga practice in patients with chronic LBP and MRI-based degenerative changes would result in differences in: (i) self-reported pain, anxiety, and spinal flexibility; and (ii) the structure of the discs or vertebrae. Material/Methods Sixty-two persons with MRI-proven degenerative intervertebral discs (group mean ±S.D., 36.2±6.4 years; 30 females) were randomly assigned to yoga and control groups. However, testing was conducted on only 40 subjects, so only their data are included in this study. The assessments were: self-reported pain, state anxiety, spinal flexibility, and MRI of the lumbosacral spine, performed using a 1.5 Tesla system with a spinal surface column. The yoga group was taught light exercises, physical postures, breathing techniques, and yoga relaxation techniques for 1 hour daily for 3 months. No intervention was given to the control group except for routine medical care. A repeated-measures analysis of variance (ANOVA) with post hoc analyses (which was Bonferroni-adjusted) was used. The Ethics Committee of Patanjali Research Foundation had approved the study which had been registered in the Clinical Trials Registry of India (CTRI/2012/11/003094). Results The yoga group showed a significant reduction in self-reported pain and state anxiety in a before/after comparison at 12 weeks. A few patients in both groups showed changes in the discs and vertebrae at post-intervention assessment. Conclusions Within 12 weeks, yoga practice reduced pain and state anxiety but did not alter MRI-proven changes in the intervertebral discs and in the vertebrae.

  5. A Randomized Controlled Trial to Assess Pain and Magnetic Resonance Imaging-Based (MRI-Based) Structural Spine Changes in Low Back Pain Patients After Yoga Practice.

    PubMed

    Telles, Shirley; Bhardwaj, Abhishek K; Gupta, Ram K; Sharma, Sachin K; Monro, Robin; Balkrishna, Acharya

    2016-01-01

    BACKGROUND The present study aimed at determining whether 12 weeks of yoga practice in patients with chronic LBP and MRI-based degenerative changes would result in differences in: (i) self-reported pain, anxiety, and spinal flexibility; and (ii) the structure of the discs or vertebrae. MATERIAL AND METHODS Sixty-two persons with MRI-proven degenerative intervertebral discs (group mean ±S.D., 36.2±6.4 years; 30 females) were randomly assigned to yoga and control groups. However, testing was conducted on only 40 subjects, so only their data are included in this study. The assessments were: self-reported pain, state anxiety, spinal flexibility, and MRI of the lumbosacral spine, performed using a 1.5 Tesla system with a spinal surface column. The yoga group was taught light exercises, physical postures, breathing techniques, and yoga relaxation techniques for 1 hour daily for 3 months. No intervention was given to the control group except for routine medical care. A repeated-measures analysis of variance (ANOVA) with post hoc analyses (which was Bonferroni-adjusted) was used. The Ethics Committee of Patanjali Research Foundation had approved the study which had been registered in the Clinical Trials Registry of India (CTRI/2012/11/003094). RESULTS The yoga group showed a significant reduction in self-reported pain and state anxiety in a before/after comparison at 12 weeks. A few patients in both groups showed changes in the discs and vertebrae at post-intervention assessment. CONCLUSIONS Within 12 weeks, yoga practice reduced pain and state anxiety but did not alter MRI-proven changes in the intervertebral discs and in the vertebrae. PMID:27619104

  6. From prosodic structure to acoustic saliency: A fMRI investigation of speech rate, clarity, and emphasis

    NASA Astrophysics Data System (ADS)

    Golfinopoulos, Elisa

    Acoustic variability in fluent speech can arise at many stages in speech production planning and execution. For example, at the phonological encoding stage, the grouping of phonemes into syllables determines which segments are coarticulated and, by consequence, segment-level acoustic variation. Likewise phonetic encoding, which determines the spatiotemporal extent of articulatory gestures, will affect the acoustic detail of segments. Functional magnetic resonance imaging (fMRI) was used to measure brain activity of fluent adult speakers in four speaking conditions: fast, normal, clear, and emphatic (or stressed) speech. These speech manner changes typically result in acoustic variations that do not change the lexical or semantic identity of productions but do affect the acoustic saliency of phonemes, syllables and/or words. Acoustic responses recorded inside the scanner were assessed quantitatively using eight acoustic measures and sentence duration was used as a covariate of non-interest in the neuroimaging analysis. Compared to normal speech, emphatic speech was characterized acoustically by a greater difference between stressed and unstressed vowels in intensity, duration, and fundamental frequency, and neurally by increased activity in right middle premotor cortex and supplementary motor area, and bilateral primary sensorimotor cortex. These findings are consistent with right-lateralized motor planning of prosodic variation in emphatic speech. Clear speech involved an increase in average vowel and sentence durations and average vowel spacing, along with increased activity in left middle premotor cortex and bilateral primary sensorimotor cortex. These findings are consistent with an increased reliance on feedforward control, resulting in hyper-articulation, under clear as compared to normal speech. Fast speech was characterized acoustically by reduced sentence duration and average vowel spacing, and neurally by increased activity in left anterior frontal

  7. Automatic Atlas Based Electron Density and Structure Contouring for MRI-based Prostate Radiation Therapy on the Cloud

    NASA Astrophysics Data System (ADS)

    Dowling, J. A.; Burdett, N.; Greer, P. B.; Sun, J.; Parker, J.; Pichler, P.; Stanwell, P.; Chandra, S.; Rivest-Hénault, D.; Ghose, S.; Salvado, O.; Fripp, J.

    2014-03-01

    Our group have been developing methods for MRI-alone prostate cancer radiation therapy treatment planning. To assist with clinical validation of the workflow we are investigating a cloud platform solution for research purposes. Benefits of cloud computing can include increased scalability, performance and extensibility while reducing total cost of ownership. In this paper we demonstrate the generation of DICOM-RT directories containing an automatic average atlas based electron density image and fast pelvic organ contouring from whole pelvis MR scans.

  8. MRI as a Novel In Vivo Approach for Assessing Structural Changes of Chlamydia Pathology in a Mouse Model.

    PubMed

    Hines, Catherine D G; Wang, Shubing; Meng, Xiangjun; Skinner, Julie M; Heinrichs, Jon H; Smith, Jeffrey G; Boddicker, Melissa A

    2016-01-01

    Chlamydia trachomatis is among the most prevalent of sexually transmitted diseases. While Chlamydia infection is a reportable event and screening has increased over time, enhanced surveillance has not resulted in a reduction in the rate of infections, and Chlamydia infections frequently recur. The development of a preventative vaccine for Chlamydia may be the only effective approach for reducing infection and the frequency of pathological outcomes. Current vaccine research efforts involve time consuming and/or invasive approaches for assessment of disease state, and MRI presents a clinically translatable method for assessing infection and related pathology both quickly and non-invasively. Longitudinal T2-weighted MRI was performed over 63 days on both control or Chlamydia muridarum challenged mice, either with or without elementary body (EB) immunization, and gross necropsy was performed on day 65. A scoring system was developed to assess the number of regions affected by Chlamydia pathology and was used to document pathology over time and at necropsy. The scoring system documented increasing incidence of pathology in the unimmunized and challenged mice (significantly greater compared to the control and EB immunized-challenged groups) by 21 days post-challenge. No differences between the unchallenged and EB immunized-challenged mice were observed. MRI scores at Day 63 were consistently higher than gross necropsy scores at Day 65, although two of the three groups of mice showed no significant differences between the two techniques. In this work we describe the application of MRI in mice for the potential evaluation of disease pathology and sequelae caused by C. muridarum infection and this technique's potential for evaluation of vaccines for Chlamydia. PMID:27467585

  9. MRI as a Novel In Vivo Approach for Assessing Structural Changes of Chlamydia Pathology in a Mouse Model

    PubMed Central

    Wang, Shubing; Meng, Xiangjun; Skinner, Julie M.; Heinrichs, Jon H.; Smith, Jeffrey G.; Boddicker, Melissa A.

    2016-01-01

    Chlamydia trachomatis is among the most prevalent of sexually transmitted diseases. While Chlamydia infection is a reportable event and screening has increased over time, enhanced surveillance has not resulted in a reduction in the rate of infections, and Chlamydia infections frequently recur. The development of a preventative vaccine for Chlamydia may be the only effective approach for reducing infection and the frequency of pathological outcomes. Current vaccine research efforts involve time consuming and/or invasive approaches for assessment of disease state, and MRI presents a clinically translatable method for assessing infection and related pathology both quickly and non-invasively. Longitudinal T2-weighted MRI was performed over 63 days on both control or Chlamydia muridarum challenged mice, either with or without elementary body (EB) immunization, and gross necropsy was performed on day 65. A scoring system was developed to assess the number of regions affected by Chlamydia pathology and was used to document pathology over time and at necropsy. The scoring system documented increasing incidence of pathology in the unimmunized and challenged mice (significantly greater compared to the control and EB immunized-challenged groups) by 21 days post-challenge. No differences between the unchallenged and EB immunized-challenged mice were observed. MRI scores at Day 63 were consistently higher than gross necropsy scores at Day 65, although two of the three groups of mice showed no significant differences between the two techniques. In this work we describe the application of MRI in mice for the potential evaluation of disease pathology and sequelae caused by C. muridarum infection and this technique’s potential for evaluation of vaccines for Chlamydia. PMID:27467585

  10. Battlefield MRI

    SciTech Connect

    Espy, Michelle

    2015-06-01

    Magnetic Resonance Imaging is the best method for non-invasive imaging of soft tissue anatomy, saving countless lives each year. It is regarded as the gold standard for diagnosis of mild to moderate traumatic brain injuries. Furthermore, conventional MRI relies on very high, fixed strength magnetic fields (> 1.5 T) with parts-per-million homogeneity, which requires very large and expensive magnets.

  11. MRI and intraocular tamponade media.

    PubMed

    Manfrè, L; Fabbri, G; Avitabile, T; Biondi, P; Reibaldi, A; Pero, G

    1993-01-01

    Thirteen patients who underwent surgery for retinal detachment and injection of intraocular tamponade media (silicone oil, fluorosilicone oil, or perfluorocarbon liquid) underwent magnetic resonance imaging (MRI), using spin-echo T1- and T2-weighted images. The ophthalmic tamponade media showed different signal intensity, according to their chemical structure. Unlike ophthalmoscopy or ultrasonography, MRI showed no oil-related artefact, making possible recognition of recurrent retinal detachment.

  12. MRI of plants and foods

    NASA Astrophysics Data System (ADS)

    Van As, Henk; van Duynhoven, John

    2013-04-01

    The importance and prospects for MRI as applied to intact plants and to foods are presented in view of one of humanity's most pressing concerns, the sustainable and healthy feeding of a worldwide increasing population. Intact plants and foods have in common that their functionality is determined by complex multiple length scale architectures. Intact plants have an additional level of complexity since they are living systems which critically depend on transport and signalling processes between and within tissues and organs. The combination of recent cutting-edge technical advances and integration of MRI accessible parameters has the perspective to contribute to breakthroughs in understanding complex regulatory plant performance mechanisms. In food science and technology MRI allows for quantitative multi-length scale structural assessment of food systems, non-invasive monitoring of heat and mass transport during shelf-life and processing, and for a unique view on food properties under shear. These MRI applications are powerful enablers of rationally (re)designed food formulations and processes. Limitations and bottlenecks of the present plant and food MRI methods are mainly related to short T2 values and susceptibility artefacts originating from small air spaces in tissues/materials. We envisage cross-fertilisation of solutions to overcome these hurdles in MRI applications in plants and foods. For both application areas we witness a development where MRI is moving from highly specialised equipment to mobile and downscaled versions to be used by a broad user base in the field, greenhouse, food laboratory or factory.

  13. Impossible expectations: fMRI adaptation in the lateral occipital complex (LOC) is modulated by the statistical regularities of 3D structural information.

    PubMed

    Freud, Erez; Ganel, Tzvi; Avidan, Galia

    2015-11-15

    fMRI adaptation (fMRIa), the attenuation of fMRI signal which follows repeated presentation of a stimulus, is a well-documented phenomenon. Yet, the underlying neural mechanisms supporting this effect are not fully understood. Recently, short-term perceptual expectations, induced by specific experimental settings, were shown to play an important modulating role in fMRIa. Here we examined the role of long-term expectations, based on 3D structural statistical regularities, in the modulation of fMRIa. To this end, human participants underwent fMRI scanning while performing a same-different task on pairs of possible (regular, expected) objects and spatially impossible (irregular, unexpected) objects. We hypothesized that given the spatial irregularity of impossible objects in relation to real-world visual experience, the visual system would always generate a prediction which is biased to the possible version of the objects. Consistently, fMRIa effects in the lateral occipital cortex (LOC) were found for possible, but not for impossible objects. Additionally, in alternating trials the order of stimulus presentation modulated LOC activity. That is, reduced activation was observed in trials in which the impossible version of the object served as the prime object (i.e. first object) and was followed by the possible version compared to the reverse order. These results were also supported by the behavioral advantage observed for trials that were primed by possible objects. Together, these findings strongly emphasize the importance of perceptual expectations in object representation and provide novel evidence for the role of real-world statistical regularities in eliciting fMRIa.

  14. Structural and Nutritional Properties of Pasta from Triticum monococcum and Triticum durum Species. A Combined ¹H NMR, MRI, and Digestibility Study.

    PubMed

    Pasini, Gabriella; Greco, Fulvia; Cremonini, Mauro A; Brandolini, Andrea; Consonni, Roberto; Gussoni, Maristella

    2015-05-27

    The aim of the present study was to characterize the structure of two different types of pasta, namely Triticum turgidum ssp. durum (cv. Saragolla) and Triticum monococcum ssp. monococcum (cv. Monlis), under different processing conditions. MRI analysis and NMR spectroscopy (i.e., T1 and T2 NMR relaxation times and diffusion parameters) were conducted on pasta, and (1)H NMR spectroscopic analysis of the chemical compounds released by pasta samples during the cooking process was performed. In addition, starch digestibility (enzimatically determined) was also investigated. The NMR results indicated that Saragolla pasta has a more compact structure, ascribed to pasta network and in particular to different technological gluten properties, that mainly determine the lower ability of Monlis pasta in binding water. These results correlate well with the lower rate of starch hydrolysis measured for Monlis pasta compared to Saragolla when both are dried at high temperature.

  15. Pelvis MRI scan

    MedlinePlus

    MRI - pelvis; MRI - hips; Pelvic MRI with prostate probe; Magnetic resonance imaging - pelvis ... care provider if you are afraid of close spaces (have claustrophobia). You may be given a medicine ...

  16. Breast MRI scan

    MedlinePlus

    MRI - breast; Magnetic resonance imaging - breast; Breast cancer - MRI; Breast cancer screening - MRI ... the same breast or the other breast after breast cancer has been diagnosed Distinguish between scar tissue and ...

  17. MRI of the penis.

    PubMed

    Kirkham, A

    2012-11-01

    MRI of the penis is an expensive test that is not always superior to clinical examination or ultrasound. However, it shows many of the important structures, and in particular the combination of tumescence from intracavernosal alprostadil, and high-resolution T(2) sequences show the glans, corpora and the tunica albuginea well. In this paper we summarise the radiological anatomy and discuss the indications for MRI. For penile cancer, it may be useful in cases where the local stage is not apparent clinically. In priapism, it is an emerging technique for assessing corporal viability, and in fracture it can in most cases make the diagnosis and locate the injury. In some cases of penile fibrosis and Peyronie's disease, it may aid surgical planning, and in complex pelvic fracture may replace or augment conventional urethrography. It is an excellent investigation for the malfunctioning penile prosthesis.

  18. Corpus callosum area and brain volume in autism spectrum disorder: quantitative analysis of structural MRI from the ABIDE database.

    PubMed

    Kucharsky Hiess, R; Alter, R; Sojoudi, S; Ardekani, B A; Kuzniecky, R; Pardoe, H R

    2015-10-01

    Reduced corpus callosum area and increased brain volume are two commonly reported findings in autism spectrum disorder (ASD). We investigated these two correlates in ASD and healthy controls using T1-weighted MRI scans from the Autism Brain Imaging Data Exchange (ABIDE). Automated methods were used to segment the corpus callosum and intracranial region. No difference in the corpus callosum area was found between ASD participants and healthy controls (ASD 598.53 ± 109 mm(2); control 596.82 ± 102 mm(2); p = 0.76). The ASD participants had increased intracranial volume (ASD 1,508,596 ± 170,505 mm(3); control 1,482,732 ± 150,873.5 mm(3); p = 0.042). No evidence was found for overall ASD differences in the corpus callosum subregions.

  19. Superconducting magnets for MRI

    SciTech Connect

    Williams, J.E.

    1984-08-01

    Three types of magnets are currently used to provide the background field required for magnet resonance imaging (MRI). (i) Permanent magnets produce fields of up to 0.3 T in volumes sufficient for imaging the head or up to 0.15 T for whole body imaging. Cost and simplicity of operation are advantages, but relatively low field, weight (up to 100 tonnes) and, to a small extent, instability are limitations. (ii) Water-cooled magnets provide fields of up to 0.25 T in volumes suitable for whole body imaging, but at the expense of power (up to 150 kW for 0.25 T) and water-cooling. Thermal stability of the field requires the maintenance of constant temperature through periods both of use and of quiescence. (iii) Because of the limitations imposed by permanent and resistive magnets, particularly on field strength, the superconducting magnet is now most widely used to provide background fields of up to 2 T for whole body MRI. It requires very low operating power and that only for refrigeration. Because of the constant low temperature, 4.2 K, at which its stressed structure operates, its field is stable. The following review deals principally with superconducting magnets for MRI. However, the sections on field analysis apply to all types of magnet and the description of the source terms of circular coils and of the principals of design of solenoids apply equally to resistive solenoidal magnets.

  20. Non-Cartesian sampled centric scan SPRITE imaging with magnetic field gradient and B0(t) field measurements for MRI in the vicinity of metal structures.

    PubMed

    Han, Hui; Green, Derrick; Ouellette, Matthew; MacGregor, Rodney; Balcom, Bruce J

    2010-09-01

    This paper proposes the possibility of spatially resolved MRI measurements undertaken inside metallic cells. MRI has been rarely usable inside conducting vessels due to the eddy currents in the walls caused by switching magnetic field gradients, which render most advanced MRI pulse sequences impossible. We propose magnetic field gradient waveform monitoring (MFGM) for MRI of samples inside metallic cells. In this work the MFGM method was extended to measure the B(0) field temporal evolution associated with gradient waveforms. MFGM was used to observe and correct eddy current effects associated with a metallic cell. High quality centric scan SPRITE images result from such corrections. MRI of samples held under pressure, most notably rock core samples, traditionally employs cells that are non-magnetic and fabricated from polymeric materials. The natural material for high-pressure MRI is however non-ferromagnetic metal given their high tensile strengths and high thermal conductivity. MRI measurement of macroscopic samples at high pressure would be generally possible if metallic pressure vessels could be employed. This study will form the basis of new MRI compatible metallic pressure vessels, which will permit MRI of macroscopic systems at high pressure. PMID:20650669

  1. A short-term scan-rescan reliability test measuring brain tissue and subcortical hyperintensity volumetrics obtained using the lesion explorer structural MRI processing pipeline.

    PubMed

    Ramirez, Joel; Scott, Christopher J M; Black, Sandra E

    2013-01-01

    Lesion Explorer (LE) is a reliable and comprehensive MRI-derived tissue segmentation and brain region parcellation processing pipeline for obtaining intracranial tissue and subcortical hyperintensity (SH) volumetrics. The processing pipeline segments: gray (GM) and white matter (WM); sulcal (sCSF) and ventricular cerebrospinal fluid (vCSF); periventricular (pvSH) and deep white subcortical hyperintensities (dwSH); and cystic fluid filled lacunar-like infarcts (Lacunar); into 26 regions of interest. A short-term scan-rescan reliability test was performed on 20 healthy volunteers: 10 older (mean = 77.7 years, SD = 11.1) and 10 younger (mean = 29.4 years, SD = 7.1). Each participant was scanned twice with an average interscan interval of 15.4 days (range: 29 min-50 days). Results suggest low technique-related error as indicated by excellent intraclass correlation coefficient (ICC) results, with ICCs above 0.90 (p < 0.05) for GM, WM, and CSF, in all 26 regions of interest (13 per hemisphere). Ventricular and lesion sub-type (pvSH, dwSH, and Lacunar) volumes also showed high scan-rescan reliability (dwSH = 0.9998, pvSH = 0.9998, Lacunar = 0.9859, p < 0.01). As indicated by the results of this short-term scan-rescan study, the LE structural MRI processing pipeline can be applied for longitudinal volumetric analyses with confidence.

  2. Abnormal Subcortical Components of the Corticostriatal System in Young Adults with DLI: A Combined Structural MRI and DTI Study

    PubMed Central

    Lee, Joanna C.; Nopoulos, Peggy C.; Tomblin, J. Bruce

    2013-01-01

    Developmental Language Impairment (DLI) is a neurodevelopmental disorder affecting 12% to 14% of the school-age children in the United States. While substantial studies have shown a wide range of linguistic and non-linguistic difficulty in individuals with DLI, very little is known about the neuroanatomical mechanisms underlying this disorder. In the current study, we examined the subcortical components of the corticostriatal system in young adults with DLI, including the caudate nucleus, the putamen, the nucleus accumbens, the globus pallidus, and the thalamus. Additionally, the four cerebral lobes and the hippocampus were also comprised for an exploratory analysis. We used conventional magnetic resonance imaging (MRI) to measure regional brain volumes, as well as diffusion tensor imaging (DTI) to assess water diffusion anisotropy as quantified by fractional anisotropy (FA). Two groups of participants, one with DLI (n=12) and the other without ( n=12), were recruited from a prior behavioral study, and all were matched on age, gender, and handedness. Volumetric analyses revealed region-specific abnormalities in individuals with DLI, showing pathological enlargement bilaterally in the putamen and the nucleus accumbens, and unilaterally in the right globus pallidus after the intracranial volumes were controlled. Regarding the DTI findings, the DLI group showed decreased FA values in the globus pallidus and the thalamus but these significant differences disappeared after controlling for the whole-brain FA value, indicating that microstructural abnormality is diffuse and affects other regions of the brain. Taken together, these results suggest region-specific corticostriatal abnormalities in DLI at the macrostructural level, but corticostriatal abnormalities at the microstructural level may be a part of a diffuse pattern of brain development. Future work is suggested to investigate the relationship between corticostriatal connectivity and individual differences in

  3. Brain structural connectivity increases concurrent with functional improvement: evidence from diffusion tensor MRI in children with cerebral palsy during therapy.

    PubMed

    Englander, Zoë A; Sun, Jessica; Laura Case; Mikati, Mohamad A; Kurtzberg, Joanne; Song, Allen W

    2015-01-01

    Cerebral Palsy (CP) refers to a heterogeneous group of permanent but non-progressive movement disorders caused by injury to the developing fetal or infant brain (Bax et al., 2005). Because of its serious long-term consequences, effective interventions that can help improve motor function, independence, and quality of life are critically needed. Our ongoing longitudinal clinical trial to treat children with CP is specifically designed to meet this challenge. To maximize the potential for functional improvement, all children in this trial received autologous cord blood transfusions (with order randomized with a placebo administration over 2 years) in conjunction with more standard physical and occupational therapies. As a part of this trial, magnetic resonance imaging (MRI) is used to improve our understanding of how these interventions affect brain development, and to develop biomarkers of treatment efficacy. In this report, diffusion tensor imaging (DTI) and subsequent brain connectome analyses were performed in a subset of children enrolled in the clinical trial (n = 17), who all exhibited positive but varying degrees of functional improvement over the first 2-year period of the study. Strong correlations between increases in white matter (WM) connectivity and functional improvement were demonstrated; however no significant relationships between either of these factors with the age of the child at time of enrollment were identified. Thus, our data indicate that increases in brain connectivity reflect improved functional abilities in children with CP. In future work, this potential biomarker can be used to help differentiate the underlying mechanisms of functional improvement, as well as to identify treatments that can best facilitate functional improvement upon un-blinding of the timing of autologous cord blood transfusions at the completion of this study.

  4. Brain structural connectivity increases concurrent with functional improvement: Evidence from diffusion tensor MRI in children with cerebral palsy during therapy

    PubMed Central

    Englander, Zoë A.; Sun, Jessica; Laura Case; Mikati, Mohamad A.; Kurtzberg, Joanne; Song, Allen W.

    2015-01-01

    Cerebral Palsy (CP) refers to a heterogeneous group of permanent but non-progressive movement disorders caused by injury to the developing fetal or infant brain (Bax et al., 2005). Because of its serious long-term consequences, effective interventions that can help improve motor function, independence, and quality of life are critically needed. Our ongoing longitudinal clinical trial to treat children with CP is specifically designed to meet this challenge. To maximize the potential for functional improvement, all children in this trial received autologous cord blood transfusions (with order randomized with a placebo administration over 2 years) in conjunction with more standard physical and occupational therapies. As a part of this trial, magnetic resonance imaging (MRI) is used to improve our understanding of how these interventions affect brain development, and to develop biomarkers of treatment efficacy. In this report, diffusion tensor imaging (DTI) and subsequent brain connectome analyses were performed in a subset of children enrolled in the clinical trial (n = 17), who all exhibited positive but varying degrees of functional improvement over the first 2-year period of the study. Strong correlations between increases in white matter (WM) connectivity and functional improvement were demonstrated; however no significant relationships between either of these factors with the age of the child at time of enrollment were identified. Thus, our data indicate that increases in brain connectivity reflect improved functional abilities in children with CP. In future work, this potential biomarker can be used to help differentiate the underlying mechanisms of functional improvement, as well as to identify treatments that can best facilitate functional improvement upon un-blinding of the timing of autologous cord blood transfusions at the completion of this study. PMID:25610796

  5. Spontaneous Slow Fluctuation of EEG Alpha Rhythm Reflects Activity in Deep-Brain Structures: A Simultaneous EEG-fMRI Study

    PubMed Central

    Omata, Kei; Hanakawa, Takashi; Morimoto, Masako; Honda, Manabu

    2013-01-01

    The emergence of the occipital alpha rhythm on brain electroencephalogram (EEG) is associated with brain activity in the cerebral neocortex and deep brain structures. To further understand the mechanisms of alpha rhythm power fluctuation, we performed simultaneous EEGs and functional magnetic resonance imaging recordings in human subjects during a resting state and explored the dynamic relationship between alpha power fluctuation and blood oxygenation level-dependent (BOLD) signals of the brain. Based on the frequency characteristics of the alpha power time series (APTS) during 20-minute EEG recordings, we divided the APTS into two components: fast fluctuation (0.04–0.167 Hz) and slow fluctuation (0–0.04 Hz). Analysis of the correlation between the MRI signal and each component revealed that the slow fluctuation component of alpha power was positively correlated with BOLD signal changes in the brain stem and the medial part of the thalamus and anterior cingulate cortex, while the fast fluctuation component was correlated with the lateral part of the thalamus and the anterior cingulate cortex, but not the brain stem. In summary, these data suggest that different subcortical structures contribute to slow and fast modulations of alpha spectra on brain EEG. PMID:23824708

  6. Fetal MRI: A pictorial essay.

    PubMed

    Rathee, Sapna; Joshi, Priscilla; Kelkar, Abhimanyu; Seth, Nagesh

    2016-01-01

    Ultrasonography (USG) is the primary method for antenatal fetal evaluation. However, fetal magnetic resonance imaging (MRI) has now become a valuable adjunct to USG in confirming/excluding suspected abnormalities and in the detection of additional abnormalities, thus changing the outcome of pregnancy and optimizing perinatal management. With the development of ultrafast sequences, fetal MRI has made remarkable progress in recent times. In this pictorial essay, we illustrate a spectrum of structural abnormalities affecting the central nervous system, thorax, genitourinary and gastrointestinal tract, as well as miscellaneous anomalies. Anomalies in twin gestations and placental abnormalities have also been included.

  7. MRI EVALUATION OF KNEE CARTILAGE

    PubMed Central

    Rodrigues, Marcelo Bordalo; Camanho, Gilberto Luís

    2015-01-01

    Through the ability of magnetic resonance imaging (MRI) to characterize soft tissue noninvasively, it has become an excellent method for evaluating cartilage. The development of new and faster methods allowed increased resolution and contrast in evaluating chondral structure, with greater diagnostic accuracy. In addition, physiological techniques for cartilage assessment that can detect early changes before the appearance of cracks and erosion have been developed. In this updating article, the various techniques for chondral assessment using knee MRI will be discussed and demonstrated. PMID:27022562

  8. Fetal MRI: A pictorial essay

    PubMed Central

    Rathee, Sapna; Joshi, Priscilla; Kelkar, Abhimanyu; Seth, Nagesh

    2016-01-01

    Ultrasonography (USG) is the primary method for antenatal fetal evaluation. However, fetal magnetic resonance imaging (MRI) has now become a valuable adjunct to USG in confirming/excluding suspected abnormalities and in the detection of additional abnormalities, thus changing the outcome of pregnancy and optimizing perinatal management. With the development of ultrafast sequences, fetal MRI has made remarkable progress in recent times. In this pictorial essay, we illustrate a spectrum of structural abnormalities affecting the central nervous system, thorax, genitourinary and gastrointestinal tract, as well as miscellaneous anomalies. Anomalies in twin gestations and placental abnormalities have also been included. PMID:27081224

  9. Cardiac MRI

    MedlinePlus

    ... a powerful magnetic field, radio waves and a computer to produce detailed pictures of the structures within ... powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of organs, soft tissues, ...

  10. Knee MRI

    MedlinePlus

    ... a powerful magnetic field, radio waves and a computer to produce detailed pictures of the structures within ... powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of organs, soft tissues, ...

  11. Getting an MRI

    MedlinePlus

    ... Help White House Lunch Recipes Getting an MRI (Video) KidsHealth > For Kids > Getting an MRI (Video) A A A en español Obtención de una resonancia magnética, RM (video) An MRI (magnetic resonance imaging) scan creates detailed ...

  12. The Effects of X Chromosome Loss on Neuroanatomical and Cognitive Phenotypes During Adolescence: a Multi-modal Structural MRI and Diffusion Tensor Imaging Study.

    PubMed

    Xie, Sheng; Zhang, Zhixin; Zhao, Qiuling; Zhang, Jiaying; Zhong, Suyu; Bi, Yanchao; He, Yong; Pan, Hui; Gong, Gaolang

    2015-09-01

    The absence of all or part of one X chromosome in female humans causes Turner's syndrome (TS), providing a unique "knockout model" to investigate the role of the X chromosome in neuroanatomy and cognition. Previous studies have demonstrated TS-associated brain differences; however, it remains largely unknown 1) how the brain structures are affected by the type of X chromosome loss and 2) how X chromosome loss influences the brain-cognition relationship. Here, we addressed these by investigating gray matter morphology and white matter connectivity using a multimodal MRI dataset from 34 adolescent TS patients (13 mosaic and 21 nonmosaic) and 21 controls. Intriguingly, the 2 TS groups exhibited significant differences in surface area in the right angular gyrus and in white matter integrity of the left tapetum of corpus callosum; these data support a link between these brain phenotypes and the type of X chromosome loss in TS. We further showed that the X chromosome modulates specific brain-cognition relationships: thickness and surface area in multiple cortical regions are positively correlated with working-memory performance in controls but negatively in TS. These findings provide novel insights into the X chromosome effect on neuroanatomical and cognitive phenotypes and highlight the role of genetic factors in brain-cognition relationships.

  13. The Effects of X Chromosome Loss on Neuroanatomical and Cognitive Phenotypes During Adolescence: a Multi-modal Structural MRI and Diffusion Tensor Imaging Study.

    PubMed

    Xie, Sheng; Zhang, Zhixin; Zhao, Qiuling; Zhang, Jiaying; Zhong, Suyu; Bi, Yanchao; He, Yong; Pan, Hui; Gong, Gaolang

    2015-09-01

    The absence of all or part of one X chromosome in female humans causes Turner's syndrome (TS), providing a unique "knockout model" to investigate the role of the X chromosome in neuroanatomy and cognition. Previous studies have demonstrated TS-associated brain differences; however, it remains largely unknown 1) how the brain structures are affected by the type of X chromosome loss and 2) how X chromosome loss influences the brain-cognition relationship. Here, we addressed these by investigating gray matter morphology and white matter connectivity using a multimodal MRI dataset from 34 adolescent TS patients (13 mosaic and 21 nonmosaic) and 21 controls. Intriguingly, the 2 TS groups exhibited significant differences in surface area in the right angular gyrus and in white matter integrity of the left tapetum of corpus callosum; these data support a link between these brain phenotypes and the type of X chromosome loss in TS. We further showed that the X chromosome modulates specific brain-cognition relationships: thickness and surface area in multiple cortical regions are positively correlated with working-memory performance in controls but negatively in TS. These findings provide novel insights into the X chromosome effect on neuroanatomical and cognitive phenotypes and highlight the role of genetic factors in brain-cognition relationships. PMID:24770708

  14. Patient-Specific Carotid Plaque Progression Simulation Using 3D Meshless Generalized Finite Difference Models with Fluid-Structure Interactions Based on Serial In Vivo MRI Data.

    PubMed

    Yang, Chun; Tang, Dalin; Atluri, Satya

    2011-01-01

    Previously, we introduced a computational procedure based on three-dimensional meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data to quantify patient-specific carotid atherosclerotic plaque growth functions and simulate plaque progression. Structure-only models were used in our previous report. In this paper, fluid-stricture interaction (FSI) was added to improve on prediction accuracy. One participating patient was scanned three times (T1, T2, and T3, at intervals of about 18 months) to obtain plaque progression data. Blood flow was assumed to laminar, Newtonian, viscous and incompressible. The Navier-Stokes equations with arbitrary Lagrangian-Eulerian (ALE) formulation were used as the governing equations. Plaque material was assumed to be uniform, homogeneous, isotropic, linear, and nearly incompressible. The linear elastic model was used. The 3D FSI plaque model was discretized and solved using a meshless generalized finite difference (GFD) method. Growth functions with a) morphology alone; b) morphology and plaque wall stress (PWS); morphology and flow shear stress (FSS), and d) morphology, PWS and FSS were introduced to predict future plaque growth based on previous time point data. Starting from the T2 plaque geometry, plaque progression was simulated by solving the FSI model and adjusting plaque geometry using plaque growth functions iteratively until T3 is reached. Numerically simulated plaque progression agreed very well with the target T3 plaque geometry with errors ranging from 8.62%, 7.22%, 5.77% and 4.39%, with the growth function including morphology, plaque wall stress and flow shear stress terms giving the best predictions. Adding flow shear stress term to the growth function improved the prediction error from 7.22% to 4.39%, a 40% improvement. We believe this is the first time 3D plaque progression FSI simulation based on multi-year patient-tracking data was reported. Serial MRI-based progression

  15. Decomposing cerebral blood flow MRI into functional and structural components: A non-local approach based on prediction

    PubMed Central

    Kandel, Benjamin M.; Wang, Danny JJ; Detre, John A.; Gee, James C.; Avants, Brian B.

    2014-01-01

    We present RIPMMARC (Rotation Invariant Patch-based Multi-Modality Analysis aRChitecture), a flexible and widely applicable method for extracting information unique to a given modality from a multi-modal data set. We use RIPMMARC to improve interpretation of arterial spin labeling (ASL) perfusion images by removing the component of perfusion that is predicted by the underlying anatomy. Using patch-based, rotation invariant descriptors derived from the anatomical image, we learn a predictive relationship between local neuroanatomical structure and the corresponding perfusion image. This relation allows us to produce an image of perfusion that would be predicted given only the underlying anatomy and a residual image that represents perfusion information that cannot be predicted by anatomical features. Our learned structural features are significantly better at predicting brain perfusion than tissue probability maps, which are the input to standard partial volume correction techniques. Studies in test-retest data show that both the anatomically predicted and residual perfusion signal are highly replicable for a given subject. In a pediatric population, both the raw perfusion and structurally predicted images are tightly linked to age throughout adolescence throughout the brain. Interestingly, the residual perfusion also shows a strong correlation with age in select regions including the hippocampi (corr= 0.38, p-value < 10−6), precuneus (corr= −0.44, p < 10−5), and combined default mode network regions (corr= −0.45, p < 10−8) that is independent of global anatomy-perfusion trends. This finding suggests that there is a regionally heterogeneous pattern of functional specialization that is distinct from that of cortical structural development. PMID:25449745

  16. Age-related alterations in the modular organization of structural cortical network by using cortical thickness from MRI.

    PubMed

    Chen, Zhang J; He, Yong; Rosa-Neto, Pedro; Gong, Gaolang; Evans, Alan C

    2011-05-01

    Normal aging is accompanied by various cognitive functional declines. Recent studies have revealed disruptions in the coordination of large-scale functional brain networks such as the default mode network in advanced aging. However, organizational alterations of the structural brain network at the system level in aging are still poorly understood. Here, using cortical thickness, we investigated the modular organization of the cortical structural networks in 102 young and 97 normal aging adults. Brain networks for both cohorts displayed a modular organization overlapping with functional domains such as executive and auditory/language processing. However, compared with the modular organization of young adults, the aging group demonstrated a significantly reduced modularity that might be indicative of reduced functional segregation in the aging brain. More importantly, the aging brain network exhibited reduced intra-/inter-module connectivity in modules corresponding to the executive function and the default mode network of young adults, which might be associated with the decline of cognitive functions in aging. Finally, we observed age-associated alterations in the regional characterization in terms of their intra/inter-module connectivity. Our results indicate that aging is associated with an altered modular organization in the structural brain networks and provide new evidence for disrupted integrity in the large-scale brain networks that underlie cognition.

  17. Good, bad and ugly word stress--fMRI evidence for foot structure driven processing of prosodic violations.

    PubMed

    Domahs, Ulrike; Klein, Elise; Huber, Walter; Domahs, Frank

    2013-06-01

    Using a stress violation paradigm, we investigated whether metrical feet constrain the way prosodic patterns are processed and evaluated. Processing of correctly versus incorrectly stressed words was associated with activation in left posterior angular and retrosplenial cortex, indicating the recognition of an expected and familiar pattern, whereas the inverse contrast yielded enhanced bilateral activation in the superior temporal gyrus, reflecting higher costs in auditory (re-)analysis. More fine-grained analyses of severe versus mild stress violations revealed activations of the left superior temporal and left anterior angular gyrus whereas the opposite contrast led to frontal activations including Broca's area and its right-hemisphere homologue, suggesting that detection of mild violations lead to increased effort in working memory and deeper phonological processing. Our results provide first evidence that different incorrect stress patterns are processed in a qualitatively different way and that the underlying foot structure seems to determine potential stress positions in German words.

  18. Structural alteration of the dorsal visual network in DLB patients with visual hallucinations: a cortical thickness MRI study.

    PubMed

    Delli Pizzi, Stefano; Franciotti, Raffaella; Tartaro, Armando; Caulo, Massimo; Thomas, Astrid; Onofrj, Marco; Bonanni, Laura

    2014-01-01

    Visual hallucinations (VH) represent one of the core features in discriminating dementia with Lewy bodies (DLB) from Alzheimer's Disease (AD). Previous studies reported that in DLB patients functional alterations of the parieto-occipital regions were correlated with the presence of VH. The aim of our study was to assess whether morphological changes in specific cortical regions of DLB could be related to the presence and severity of VH. We performed a cortical thickness analysis on magnetic resonance imaging data in a cohort including 18 DLB patients, 15 AD patients and 14 healthy control subjects. Relatively to DLB group, correlation analysis between the cortical thickness and the Neuropsychiatric Inventory (NPI) hallucination item scores was also performed. Cortical thickness was reduced bilaterally in DLB compared to controls in the pericalcarine and lingual gyri, cuneus, precuneus, superior parietal gyrus. Cortical thinning was found bilaterally in AD compared to controls in temporal cortex including the superior and middle temporal gyrus, part of inferior temporal cortex, temporal pole and insula. Inferior parietal and supramarginal gyri were also affected bilaterally in AD as compared to controls. The comparison between DLB and AD evidenced cortical thinning in DLB group in the right posterior regions including superior parietal gyrus, precuneus, cuneus, pericalcarine and lingual gyri. Furthermore, the correlation analysis between cortical thickness and NPI hallucination item scores showed that the structural alteration in the dorsal visual regions including superior parietal gyrus and precuneus closely correlated with the occurrence and severity of VH. We suggest that structural changes in key regions of the dorsal visual network may play a crucial role in the physiopathology of VH in DLB patients.

  19. MRI of Blood–Brain Barrier Permeability in Cerebral Ischemia

    PubMed Central

    Ewing, James R.; Chopp, Michael

    2013-01-01

    Quantitative measurement of blood–brain barrier (BBB) permeability using MRI and its application to cerebral ischemia are reviewed. Measurement of BBB permeability using MRI has been employed to evaluate ischemic damage during acute and subacute phases of stroke and to predict hemorrhagic transformation. There is also an emerging interest on the development and use of MRI to monitor vascular structural changes and angiogenesis during stroke recovery. In this review, we describe MRI BBB permeability and susceptibility-weighted MRI measurements and its applications to evaluate ischemic damage during the acute and subacute phases of stroke and vascular remodeling during stroke recovery. PMID:23997835

  20. Permutation and parametric tests for effect sizes in voxel-based morphometry of gray matter volume in brain structural MRI.

    PubMed

    Dickie, David A; Mikhael, Shadia; Job, Dominic E; Wardlaw, Joanna M; Laidlaw, David H; Bastin, Mark E

    2015-12-01

    Permutation testing has been widely implemented in voxel-based morphometry (VBM) tools. However, this type of non-parametric inference has yet to be thoroughly compared with traditional parametric inference in VBM studies of brain structure. Here we compare both types of inference and investigate what influence the number of permutations in permutation testing has on results in an exemplar study of how gray matter proportion changes with age in a group of working age adults. High resolution T1-weighted volume scans were acquired from 80 healthy adults aged 25-64years. Using a validated VBM procedure and voxel-based permutation testing for Pearson product-moment coefficient, the effect sizes of changes in gray matter proportion with age were assessed using traditional parametric and permutation testing inference with 100, 500, 1000, 5000, 10000 and 20000 permutations. The statistical significance was set at P<0.05 and false discovery rate (FDR) was used to correct for multiple comparisons. Clusters of voxels with statistically significant (PFDR<0.05) declines in gray matter proportion with age identified with permutation testing inference (N≈6000) were approximately twice the size of those identified with parametric inference (N=3221voxels). Permutation testing with 10000 (N=6251voxels) and 20000 (N=6233voxels) permutations produced clusters that were generally consistent with each other. However, with 1000 permutations there were approximately 20% more statistically significant voxels (N=7117voxels) than with ≥10000 permutations. Permutation testing inference may provide a more sensitive method than traditional parametric inference for identifying age-related differences in gray matter proportion. Based on the results reported here, at least 10000 permutations should be used in future univariate VBM studies investigating age related changes in gray matter to avoid potential false findings. Additional studies using permutation testing in large imaging databanks

  1. Variance Decomposition of MRI-Based Covariance Maps Using Genetically-Informative Samples and Structural Equation Modeling

    PubMed Central

    Schmitt, J. Eric; Lenroot, Rhoshel; Ordaz, Sarah E.; Wallace, Gregory L.; Lerch, Jason P.; Evans, Alan C.; Prom, Elizabeth C.; Kendler, Kenneth S.; Neale, Michael C.; Giedd, Jay N.

    2010-01-01

    The role of genetics in driving intracortical relationships is an important question that has rarely been studied in humans. In particular, there are no extant high-resolution imaging studies on genetic covariance. In this article, we describe a novel method that combines classical quantitative genetic methodologies for variance decomposition with recently-developed semi-multivariate algorithms for high-resolution measurement of phenotypic covariance. Using these tools, we produced correlational maps of genetic and environmental (i.e. nongenetic) relationships between several regions of interest and the cortical surface in a large pediatric sample of 600 twins, siblings, and singletons. These analyses demonstrated high, fairly uniform, statistically significant genetic correlations between the entire cortex and global mean cortical thickness. In agreement with prior reports on phenotypic covariance using similar methods, we found mean cortical thickness was most strongly correlated with association cortices. However, the present study suggests that genetics plays a large role in global brain patterning of cortical thickness in this manner. Further, using specific gyri with known high heritabilities as seed regions, we found a consistent pattern of high bilateral genetic correlations between structural homologues, with environmental correlations more restricted to the same hemisphere as the seed region, suggesting that interhemispheric covariance is largely genetically mediated. These findings are consistent with the limited existing knowledge on the genetics of cortical variability as well as our prior multivariate studies on cortical gyri. PMID:18672072

  2. A novel series of complexones with bis- or biazole structure as mixed ligands of paramagnetic contrast agents for MRI.

    PubMed

    Mayoral, Elena P; García-Amo, María; López, Pilar; Soriano, Elena; Cerdán, Sebastián; Ballesteros, Paloma

    2003-12-01

    We describe the syntheses, physicochemical properties and biological evaluation of a novel series of complexones containing bis- or biazoles moieties and two iminodiacetic acid units as novel ligands for paramagnetic lanthanides. The complexones were prepared by reaction of the corresponding 1,1'-bishaloethylbi- or bispyrazoles with methyl iminodiacetate and subsequent NaOH hydrolysis. 1,1'-Bisbromoethyl precursors were obtained by direct alkylation with an excess of 1,2-dibromoethane, or by heating the corresponding alcohol in HCl. Sigmoidal binding isotherms and MO calculations supported as most stable structures in solution, those containing two Gd(III) atoms bound per molecule of complexone with half saturation values S(0.5) (M(-1), 22 degrees C, pH 7.2) in the range 6.5 10(-6)

  3. [STRUCTURE OF HUMAN CORPUS CALLOSUM IN AFTER-DEATH STATE COMPARED TO INTRA-VITAM MRI IMAGES].

    PubMed

    Boiagina, O

    2016-05-01

    Our preliminary results suggest that the corpus callosum is composed of a certain number of stringy formations visualized on macroscopic and microscopic level that we proposed to call commissural funiculi. They are treated as subcallous units of the first order. The purpose of this research is to find out the form of the above-mentioned corpus callosum formations as being displayed on its sagittal profile as well as the extent to which they are displayed. The material used was male and female cerebrum of mature age people, who died for reasons not related to the pathology of the central nervous system. Cerebrum extracted from the skull after being washed was exposed to a two week fixation in 10% formalin solution. The sagittal plane slicer was used for brain dissection. Photo fixation of the medial surface of hemispheres was implemented with a digital camera. It was found out that the sagittal cut of the corpus callosum can be represented as a formation having segmental structure principle. Also, according to our observations, the trunk of the corpus callosum has distinct morphological features of bilateral asymmetry.

  4. [STRUCTURE OF HUMAN CORPUS CALLOSUM IN AFTER-DEATH STATE COMPARED TO INTRA-VITAM MRI IMAGES].

    PubMed

    Boiagina, O

    2016-05-01

    Our preliminary results suggest that the corpus callosum is composed of a certain number of stringy formations visualized on macroscopic and microscopic level that we proposed to call commissural funiculi. They are treated as subcallous units of the first order. The purpose of this research is to find out the form of the above-mentioned corpus callosum formations as being displayed on its sagittal profile as well as the extent to which they are displayed. The material used was male and female cerebrum of mature age people, who died for reasons not related to the pathology of the central nervous system. Cerebrum extracted from the skull after being washed was exposed to a two week fixation in 10% formalin solution. The sagittal plane slicer was used for brain dissection. Photo fixation of the medial surface of hemispheres was implemented with a digital camera. It was found out that the sagittal cut of the corpus callosum can be represented as a formation having segmental structure principle. Also, according to our observations, the trunk of the corpus callosum has distinct morphological features of bilateral asymmetry. PMID:27348174

  5. Age-Related Differences in White Matter Integrity in Healthy Human Brain: Evidence from Structural MRI and Diffusion Tensor Imaging

    PubMed Central

    Rathee, Rishu; Rallabandi, V.P. Subramanyam; Roy, Prasun K.

    2016-01-01

    The aim is to investigate the relationship between microstructural white matter (WM) diffusivity indices and macrostructural WM volume (WMV) among healthy individuals (20–85 years). Whole-brain diffusion measures were calculated from diffusion tensor imaging using FMRIB software library while WMV was estimated through voxel-based morphometry, and voxel-based analysis was carried out using tract-based spatial statistics. Our results revealed that mean diffusivity, axial diffusivity, and radial diffusivity had shown good correlation with WMV but not for fractional anisotropy (FA). Voxel-wise tract-based spatial statistics analysis for FA showed a significant decrease in four regions for middle-aged group compared to young-aged group, in 22 regions for old-aged group compared to middle-aged group, and in 26 regions for old-aged group compared to young-aged group (P < 0.05). We found significantly lower WMV, FA, and mean diffusivity values in females than males and inverted-U trend for FA in males. We conclude differential age- and gender-related changes for structural WMV and WM diffusion indices. PMID:27279747

  6. Quantitative MRI Measures in SIV-Infected Macaque Brains.

    PubMed

    Zhang, Xiaodong; Li, Chunxia

    2013-01-01

    Multiple MRI modalities including Diffusion Tensor Imaging (DTI), perfusion MRI, in vivo MR Spectroscopy (MRS), volumetric MRI, contrast-enhanced MRI, and functional MRI have demonstrated abnormalities of the structural and functional integrity as well as neurochemical alterations of the HIV-infected central nervous system (CNS). MRI has been proposed as a robust imaging approach for the characterization of the stage of progression in HIV infection. However, the interpretation of the MRI findings of HIV patients is complicated by the fact that these clinical studies cannot readily be controlled. Simian immunodeficiency virus (SIV) infected macaques exhibit neuropathological symptoms similar to those of HIV patients, and are an important model for studying the course of CNS infection, cognitive impairment, and neuropathology of HIV disease as well as treatment efficacy. MRI of non-human primates (NHPs) is of limited benefit on most clinical scanners operating at or below 1.5 Tesla because this low field strength does not produce high-quality images of the relatively small NHP brain. Contemporary high field MRI (3T or more) for clinical use provides impressive sensitivity for magnetic resonance signal detection and is now accessible in many imaging centers and hospitals, facilitating the use of various MRI techniques in NHP studies. In this article, several high field MRI techniques and applications in macaque models of neuroAIDS are reviewed and the relation between quantitative MRI measures and blood T-cell alterations is discussed. PMID:24244892

  7. Structural and functional MRI abnormalities of cerebellar cortex and nuclei in SCA3, SCA6 and Friedreich's ataxia.

    PubMed

    Stefanescu, Maria R; Dohnalek, Moritz; Maderwald, Stefan; Thürling, Markus; Minnerop, Martina; Beck, Andreas; Schlamann, Marc; Diedrichsen, Joern; Ladd, Mark E; Timmann, Dagmar

    2015-05-01

    type 3. Within the cerebellar nuclei, reductions were significant when comparing spinocerebellar ataxia type 6 and Friedreich's ataxia to matched controls (P < 0.01, bootstrap-corrected cluster-size threshold; two-sample t-tests). Susceptibility weighted imaging allowed depiction of atrophy of the cerebellar nuclei in patients with Friedreich's ataxia and spinocerebellar ataxia type 3. In spinocerebellar ataxia type 6, pathology was not restricted to the cerebellar cortex but also involved the cerebellar nuclei. Functional magnetic resonance imaging data, on the other hand, revealed that pathology in Friedreich's ataxia and spinocerebellar ataxia type 3 is not restricted to the cerebellar nuclei. There was functional involvement of the cerebellar cortex despite no or little structural changes.

  8. MRI morphometry in Alzheimer's disease.

    PubMed

    Matsuda, Hiroshi

    2016-09-01

    MRI based evaluation of brain atrophy is regarded as a valid method to stage the disease and to assess progression in Alzheimer's disease (AD). Volumetric software programs have made it possible to quantify gray matter in the human brain in an automated fashion. At present, voxel based morphometry (VBM) is easily applicable to the routine clinical procedure with a short execution time. The importance of the VBM approach is that it is not biased to one particular structure and is able to assess anatomical differences throughout the brain. Stand-alone VBM software running on Windows, Voxel-based Specific Regional analysis system for AD (VSRAD), has been widely used in the clinical diagnosis of AD in Japan. On the other hand, recent application of graph theory to MRI has made it possible to analyze changes in structural connectivity in AD.

  9. MRI brain imaging.

    PubMed

    Skinner, Sarah

    2013-11-01

    General practitioners (GPs) are expected to be allowed to request MRI scans for adults for selected clinically appropriate indications from November 2013 as part of the expansion of Medicare-funded MRI services announced by the Federal Government in 2011. This article aims to give a brief overview of MRI brain imaging relevant to GPs, which will facilitate explanation of scan findings and management planning with their patients. Basic imaging techniques, common findings and terminology are presented using some illustrative case examples.

  10. Low-Cost High-Performance MRI.

    PubMed

    Sarracanie, Mathieu; LaPierre, Cristen D; Salameh, Najat; Waddington, David E J; Witzel, Thomas; Rosen, Matthew S

    2015-01-01

    Magnetic Resonance Imaging (MRI) is unparalleled in its ability to visualize anatomical structure and function non-invasively with high spatial and temporal resolution. Yet to overcome the low sensitivity inherent in inductive detection of weakly polarized nuclear spins, the vast majority of clinical MRI scanners employ superconducting magnets producing very high magnetic fields. Commonly found at 1.5-3 tesla (T), these powerful magnets are massive and have very strict infrastructure demands that preclude operation in many environments. MRI scanners are costly to purchase, site, and maintain, with the purchase price approaching $1 M per tesla (T) of magnetic field. We present here a remarkably simple, non-cryogenic approach to high-performance human MRI at ultra-low magnetic field, whereby modern under-sampling strategies are combined with fully-refocused dynamic spin control using steady-state free precession techniques. At 6.5 mT (more than 450 times lower than clinical MRI scanners) we demonstrate (2.5 × 3.5 × 8.5) mm(3) imaging resolution in the living human brain using a simple, open-geometry electromagnet, with 3D image acquisition over the entire brain in 6 minutes. We contend that these practical ultra-low magnetic field implementations of MRI (<10 mT) will complement traditional MRI, providing clinically relevant images and setting new standards for affordable (<$50,000) and robust portable devices. PMID:26469756

  11. Low-Cost High-Performance MRI

    NASA Astrophysics Data System (ADS)

    Sarracanie, Mathieu; Lapierre, Cristen D.; Salameh, Najat; Waddington, David E. J.; Witzel, Thomas; Rosen, Matthew S.

    2015-10-01

    Magnetic Resonance Imaging (MRI) is unparalleled in its ability to visualize anatomical structure and function non-invasively with high spatial and temporal resolution. Yet to overcome the low sensitivity inherent in inductive detection of weakly polarized nuclear spins, the vast majority of clinical MRI scanners employ superconducting magnets producing very high magnetic fields. Commonly found at 1.5-3 tesla (T), these powerful magnets are massive and have very strict infrastructure demands that preclude operation in many environments. MRI scanners are costly to purchase, site, and maintain, with the purchase price approaching $1 M per tesla (T) of magnetic field. We present here a remarkably simple, non-cryogenic approach to high-performance human MRI at ultra-low magnetic field, whereby modern under-sampling strategies are combined with fully-refocused dynamic spin control using steady-state free precession techniques. At 6.5 mT (more than 450 times lower than clinical MRI scanners) we demonstrate (2.5 × 3.5 × 8.5) mm3 imaging resolution in the living human brain using a simple, open-geometry electromagnet, with 3D image acquisition over the entire brain in 6 minutes. We contend that these practical ultra-low magnetic field implementations of MRI (<10 mT) will complement traditional MRI, providing clinically relevant images and setting new standards for affordable (<$50,000) and robust portable devices.

  12. Structure-property relationships in manganese oxide--mesoporous silica nanoparticles used for T1-weighted MRI and simultaneous anti-cancer drug delivery.

    PubMed

    Chen, Yu; Chen, Hangrong; Zhang, Shengjian; Chen, Feng; Sun, Shikuan; He, Qianjun; Ma, Ming; Wang, Xia; Wu, Huixia; Zhang, Lingxia; Zhang, Linlin; Shi, Jianlin

    2012-03-01

    The extremely low longitudinal relaxivity (r(1)) of manganese oxide has severely impeded their substitution for cytotoxic gadolinium-based contrast agents for safe clinical magnetic resonance imaging (MRI). Here, we report on a synthetic strategy of chemical oxidation/reduction reaction in-situ in mesopores, followed by hydrogen reduction, for the fabrication of non-toxic manganese oxide/MSNs-based MRI-T(1) contrast agents with highly comparable imaging performance to commercial Gd-based agents. This strategy involves a "soft-templating" process to prepare mesoporous silica nanoparticles, in-situ reduction of MnO(4)(-) by the "soft templates" in mesopores and heat treatment under reducing atmosphere, to disperse manganese oxide nanoparticles within mesopores. This special nanostructure combines the merits of nanopores for maximum manganese paramagnetic center accessibility for water molecules for enhanced MRI performance and encapsulation/sustained release/intracellular delivery of drugs. The synthesized manganese oxide/MSNs were successfully assessed as a high performance contrast agent for MRI-T(1) both in intro and in vivo, and meanwhile, was also demonstrated as an effective anti-cancer drug delivery (doxorubicin) vehicle, therefore, a family of manganese-based theranostics was successfully demonstrated based on the manganese oxide/MSNs composite.

  13. CEST MRI reporter genes.

    PubMed

    Liu, Guanshu; Bulte, Jeff W M; Gilad, Assaf A

    2011-01-01

    In recent years, several reporter genes have been developed that can serve as a beacon for non-invasive magnetic resonance imaging (MRI). Here, we provide a brief summary of recent advances in MRI reporter gene technology, as well as detailed "hands-on" protocols for cloning, expression, and imaging of reporter genes based on chemical exchange saturation transfer (CEST).

  14. Diffusion MRI and its role in neuropsychology

    PubMed Central

    Mueller, Bryon A; Lim, Kelvin O; Hemmy, Laura; Camchong, Jazmin

    2015-01-01

    Diffusion Magnetic Resonance Imaging (dMRI) is a popular method used by neuroscientists to uncover unique information about the structural connections within the brain. dMRI is a non-invasive imaging methodology in which image contrast is based on the diffusion of water molecules in tissue. While applicable to many tissues in the body, this review focuses exclusively on the use of dMRI to examine white matter in the brain. In this review, we begin with a definition of diffusion and how diffusion is measured with MRI. Next we introduce the diffusion tensor model, the predominant model used in dMRI. We then describe acquisition issues related to acquisition parameters and scanner hardware and software. Sources of artifacts are then discussed, followed by a brief review of analysis approaches. We provide an overview of the limitations of the traditional diffusion tensor model, and highlight several more sophisticated non-tensor models that better describe the complex architecture of the brain’s white matter. We then touch on reliability and validity issues of diffusion measurements. Finally, we describe examples of ways in which dMRI has been applied to studies of brain disorders and how identified alterations relate to symptomatology and cognition. PMID:26255305

  15. Diffusion MRI and its Role in Neuropsychology.

    PubMed

    Mueller, Bryon A; Lim, Kelvin O; Hemmy, Laura; Camchong, Jazmin

    2015-09-01

    Diffusion Magnetic Resonance Imaging (dMRI) is a popular method used by neuroscientists to uncover unique information about the structural connections within the brain. dMRI is a non-invasive imaging methodology in which image contrast is based on the diffusion of water molecules in tissue. While applicable to many tissues in the body, this review focuses exclusively on the use of dMRI to examine white matter in the brain. In this review, we begin with a definition of diffusion and how diffusion is measured with MRI. Next we introduce the diffusion tensor model, the predominant model used in dMRI. We then describe acquisition issues related to acquisition parameters and scanner hardware and software. Sources of artifacts are then discussed, followed by a brief review of analysis approaches. We provide an overview of the limitations of the traditional diffusion tensor model, and highlight several more sophisticated non-tensor models that better describe the complex architecture of the brain's white matter. We then touch on reliability and validity issues of diffusion measurements. Finally, we describe examples of ways in which dMRI has been applied to studies of brain disorders and how identified alterations relate to symptomatology and cognition.

  16. MRI-Safe Robot for Endorectal Prostate Biopsy

    PubMed Central

    Stoianovici, Dan; Kim, Chunwoo; Srimathveeravalli, Govindarajan; Sebrecht, Peter; Petrisor, Doru; Coleman, Jonathan; Solomon, Stephen B.; Hricak, Hedvig

    2014-01-01

    This paper reports the development of an MRI-Safe robot for direct (interventional) MRI-guided endorectal prostate biopsy. The robot is constructed of nonmagnetic and electrically nonconductive materials, and is electricity free, using pneumatic actuation and optical sensors. Targeting biopsy lesions of MRI abnormality presents substantial clinical potential for the management of prostate cancer. The paper describes MRI-Safe requirements, presents the kinematic architecture, design and construction of the robot, and a comprehensive set of preclinical tests for MRI compatibility and needle targeting accuracy. The robot has a compact and simple 3 degree-of-freedom (DoF) structure, two for orienting a needle-guide and one to preset the depth of needle insertion. The actual insertion is performed manually through the guide and up to the preset depth. To reduce the complexity and size of the robot next to the patient, the depth setting DoF is remote. Experimental results show that the robot is safe to use in any MRI environment (MRI-Safe). Comprehensive MRI tests show that the presence and motion of the robot in the MRI scanner cause virtually no image deterioration or signal to noise ratio (SNR) change. Robot’s accuracy in bench test, CT-guided in-vitro, MRI-guided in-vitro and animal tests are 0.37mm, 1.10mm, 2.09mm, and 2.58mm respectively. These values are acceptable for clinical use. PMID:25378897

  17. MRI characteristics of midbrain tumours.

    PubMed

    Sun, B; Wang, C C; Wang, J

    1999-03-01

    We diagnosed 60 cases of midbrain tumours by MRI between 1993 to 1997. There were 39 males and 21 females, aged 2-64 years, mean 25.6 years. We found 38 patients with true intramedullary mid-brain tumours, 11 predominantly in the tectum, 20 in the tegmentum and 7 with a downward extension to the pons; there were 7 within the cerebral aqueduct. There were 22 patients with infiltrating midbrain tumours extending from adjacent structures, 11 cases each from the thalamus and pineal region. All patients received surgical treatment. Gross total resection was achieved in 42 cases, subtotal (> 75 %) resection in 18. Pathological diagnoses included 16 low-grade and 15 high-grade astrocytomas; 5 oligodendroastrocytomas; 2 ependymomas; 11 glioblastomas; and 11 pineal parenchymal or germ-cell tumours. Midbrain tumours are a heterogeneous group of neoplasms, with wide variation in clinical and MRI features, related to the site and type of tumour. MRI not only allows precise analysis of their growth pattern, but also can lead to a correct preoperative diagnosis in the majority of cases.

  18. An MRI-based attenuation correction method for combined PET/MRI applications

    NASA Astrophysics Data System (ADS)

    Fei, Baowei; Yang, Xiaofeng; Wang, Hesheng

    2009-02-01

    We are developing MRI-based attenuation correction methods for PET images. PET has high sensitivity but relatively low resolution and little anatomic details. MRI can provide excellent anatomical structures with high resolution and high soft tissue contrast. MRI can be used to delineate tumor boundaries and to provide an anatomic reference for PET, thereby improving quantitation of PET data. Combined PET/MRI can offer metabolic, functional and anatomic information and thus can provide a powerful tool to study the mechanism of a variety of diseases. Accurate attenuation correction represents an essential component for the reconstruction of artifact-free, quantitative PET images. Unfortunately, the present design of hybrid PET/MRI does not offer measured attenuation correction using a transmission scan. This problem may be solved by deriving attenuation maps from corresponding anatomic MR images. Our approach combines image registration, classification, and attenuation correction in a single scheme. MR images and the preliminary reconstruction of PET data are first registered using our automatic registration method. MRI images are then classified into different tissue types using our multiscale fuzzy C-mean classification method. The voxels of classified tissue types are assigned theoretical tissue-dependent attenuation coefficients to generate attenuation correction factors. Corrected PET emission data are then reconstructed using a threedimensional filtered back projection method and an order subset expectation maximization method. Results from simulated images and phantom data demonstrated that our attenuation correction method can improve PET data quantitation and it can be particularly useful for combined PET/MRI applications.

  19. Leg MRI scan

    MedlinePlus

    ... resonance imaging) scan of the leg uses strong magnets to create pictures of the leg. This may ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed into the room ...

  20. Shoulder MRI scan

    MedlinePlus

    ... an imaging test that uses energy from powerful magnets and to create pictures of the shoulder area. ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed in the room ...

  1. MRI (Magnetic Resonance Imaging)

    MedlinePlus

    ... some MRI exams, intravenous (IV) drugs, such as gadolinium-based contrast agents (GBCAs) are used to change the contrast of the MR image. Gadolinium-based contrast agents are rare earth metals that ...

  2. MRI of the Breast

    MedlinePlus

    ... as a supplemental tool to breast screening with mammography or ultrasound. It may be used to screen ... following diagnosis, or further evaluate abnormalities seen on mammography. Breast MRI does not use ionizing radiation, and ...

  3. Abdominal MRI scan

    MedlinePlus

    Nuclear magnetic resonance - abdomen; NMR - abdomen; Magnetic resonance imaging - abdomen; MRI of the abdomen ... used to look at: Blood flow in the abdomen Blood vessels in the abdomen The cause of ...

  4. MRI of the Chest

    MedlinePlus

    ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ... tell the technologist if you have medical or electronic devices in your body. These objects may interfere ...

  5. Lumbar MRI scan

    MedlinePlus

    ... may need a lumbar MRI if you have: Low back pain that does not get better after treatment Leg ... spine Injury or trauma to the lower spine Low back pain and a history or signs of cancer Multiple ...

  6. Knee MRI scan

    MedlinePlus

    ... have been no reported side effects from the magnetic fields and radio waves. The most common type of ... health care provider before the test. The strong magnetic fields created during an MRI can cause heart pacemakers ...

  7. Cervical MRI scan

    MedlinePlus

    ... have been no reported side effects from the magnetic fields and radio waves. The most common type of ... tell your provider before the test. The strong magnetic fields created during an MRI can cause heart pacemakers ...

  8. Arm MRI scan

    MedlinePlus

    ... have been no reported side effects from the magnetic fields and radio waves. The most common type of ... tell your provider before the test The strong magnetic fields created during an MRI can cause heart pacemakers ...

  9. Molecular fMRI

    PubMed Central

    Bartelle, Benjamin B.; Barandov, Ali

    2016-01-01

    Comprehensive analysis of brain function depends on understanding the dynamics of diverse neural signaling processes over large tissue volumes in intact animals and humans. Most existing approaches to measuring brain signaling suffer from limited tissue penetration, poor resolution, or lack of specificity for well-defined neural events. Here we discuss a new brain activity mapping method that overcomes some of these problems by combining MRI with contrast agents sensitive to neural signaling. The goal of this “molecular fMRI” approach is to permit noninvasive whole-brain neuroimaging with specificity and resolution approaching current optical neuroimaging methods. In this article, we describe the context and need for molecular fMRI as well as the state of the technology today. We explain how major types of MRI probes work and how they can be sensitized to neurobiological processes, such as neurotransmitter release, calcium signaling, and gene expression changes. We comment both on past work in the field and on challenges and promising avenues for future development. SIGNIFICANCE STATEMENT Brain researchers currently have a choice between measuring neural activity using cellular-level recording techniques, such as electrophysiology and optical imaging, or whole-brain imaging methods, such as fMRI. Cellular level methods are precise but only address a small portion of mammalian brains; on the other hand, whole-brain neuroimaging techniques provide very little specificity for neural pathways or signaling components of interest. The molecular fMRI techniques we discuss have particular potential to combine the specificity of cellular-level measurements with the noninvasive whole-brain coverage of fMRI. On the other hand, molecular fMRI is only just getting off the ground. This article aims to offer a snapshot of the status and future prospects for development of molecular fMRI techniques. PMID:27076413

  10. High-resolution MRI: in vivo histology?

    PubMed Central

    Bridge, Holly; Clare, Stuart

    2005-01-01

    For centuries scientists have been fascinated with the question of how the brain works. Investigators have looked at both where different functions are localized and how the anatomical microstructure varies across the brain surface. Here we discuss how advances in magnetic resonance imaging (MRI) have allowed in vivo visualization of the fine structure of the brain that was previously only visible in post-mortem brains. We present data showing the correspondence between definitions of the primary visual cortex defined anatomically using very high-resolution MRI and functionally using functional MRI. We consider how this technology can be applied to allow the investigation of brains that differ from normal, and what this ever-evolving technology may be able to reveal about in vivo brain structure in the next few years. PMID:16553313

  11. Optogenetic Functional MRI

    PubMed Central

    Lin, Peter; Fang, Zhongnan; Liu, Jia; Lee, Jin Hyung

    2016-01-01

    The investigation of the functional connectivity of precise neural circuits across the entire intact brain can be achieved through optogenetic functional magnetic resonance imaging (ofMRI), which is a novel technique that combines the relatively high spatial resolution of high-field fMRI with the precision of optogenetic stimulation. Fiber optics that enable delivery of specific wavelengths of light deep into the brain in vivo are implanted into regions of interest in order to specifically stimulate targeted cell types that have been genetically induced to express light-sensitive trans-membrane conductance channels, called opsins. fMRI is used to provide a non-invasive method of determining the brain's global dynamic response to optogenetic stimulation of specific neural circuits through measurement of the blood-oxygen-level-dependent (BOLD) signal, which provides an indirect measurement of neuronal activity. This protocol describes the construction of fiber optic implants, the implantation surgeries, the imaging with photostimulation and the data analysis required to successfully perform ofMRI. In summary, the precise stimulation and whole-brain monitoring ability of ofMRI are crucial factors in making ofMRI a powerful tool for the study of the connectomics of the brain in both healthy and diseased states. PMID:27167840

  12. Performance of the MRI-Based Virtual Bone Biopsy in the Distal Radius: Serial Reproducibility and Reliability of Structural and Mechanical Parameters in Women Representative of Osteoporosis Study Populations

    PubMed Central

    Lam, Shing Chun Benny; Wald, Michael J.; Rajapakse, Chamith S.; Liu, Yinxiao; Saha, Punam K.; Wehrli, Felix W.

    2011-01-01

    Serial reproducibility and reliability critically determine sensitivity to detect changes in response to intervention and provide a basis for sample size estimates. Here, we evaluated the performance of the MRI-based Virtual Bone Biopsy in terms of 26 structural and mechanical parameters in the distal radius of 20 women in the age range of 50 to 75 years (mean = 62.0 years, S.D. = 8.1 years), representative of typical study populations in drug intervention trials and fracture studies. Subjects were examined three times at average intervals of 20.2 days (S.D. = 14.5 days) by MRI at 1.5 T field strength at a voxel size of 137×137×410 μm3. Methods involved prospective and retrospective 3D image registration and auto-focus motion correction. Analyses were performed from a central 5×5×5 mm3 cuboid subvolume and trabecular volume consisting of a 13 mm axial slab encompassing the entire medullary cavity. Whole-volume axial stiffness and sub-regional Young’s and shear moduli were computed by finite-element analysis. Whole-volume-derived aggregate mean coefficient of variation of all structural parameters was 4.4% (range 1.8% to 7.7%) and 4.0% for axial stiffness; corresponding data in the subvolume were 6.5% (range 1.6% to 13.0%) for structural, and 5.5% (range 4.6% to 6.5%) for mechanical parameters. Aggregate ICC was 0.976 (range 0.947 to 0.986) and 0.992 for whole-volume-derived structural parameters and axial stiffness, and 0.946 (range 0.752 to 0.991) and 0.974 (range 0.965 to 0.978) for subvolume-derived structural and mechanical parameters, respectively. The strongest predictors of whole-volume axial stiffness were BV/TV, junction density, skeleton density and Tb.N (R2 0.79 – 0.87). The same parameters were also highly predictive of sub-regional axial modulus (R2 0.88 – 0.91). The data suggest that the method is suited for longitudinal assessment of the response to therapy. The underlying technology is portable and should be compatible with all general

  13. Incorporation of gallium-68 into the crystal structure of Prussian blue to form K(68)GaxFe1-x[Fe(CN)6] nanoparticles: toward a novel bimodal PET/MRI imaging agent.

    PubMed

    Kandanapitiye, Murthi S; Gott, Matthew D; Sharits, Andrew; Jurisson, Silvia S; Woodward, Patrick M; Huang, Songping D

    2016-05-31

    Similarity between the Ga(+) ion and the Fe(3+) ion allows for partial replacement of Fe(3+) ions with Ga(3+) ions in the Fe(iii) crystallographic positions in Prussian blue (PB) to form various solid solutions KGaxFe1-x[Fe(CN)6] (0 < x < 1). Such solid solutions possess very high thermodynamic stability as expected from the parent PB structure. Consequently, a simple one-step (68)Ga-labeling method was developed for preparing a single-phase nanoparticulate bimodal PET/MRI imaging agent based on the PB structural platform. Unlike the typical (68)Ga-labelling reaction based on metal complexation, this novel chelator-free (68)Ga-labeling reaction was shown to be kinetically fast under the acidic conditions. The Ga(3+) ion does not hydrolyze, and affords the (68)Ga-labelled PB nanoparticles, which are easy to purify and have extremely high stability against radionuclidic leaching in aqueous solution. PMID:27169624

  14. Incorporation of gallium-68 into the crystal structure of Prussian blue to form K(68)GaxFe1-x[Fe(CN)6] nanoparticles: toward a novel bimodal PET/MRI imaging agent.

    PubMed

    Kandanapitiye, Murthi S; Gott, Matthew D; Sharits, Andrew; Jurisson, Silvia S; Woodward, Patrick M; Huang, Songping D

    2016-05-31

    Similarity between the Ga(+) ion and the Fe(3+) ion allows for partial replacement of Fe(3+) ions with Ga(3+) ions in the Fe(iii) crystallographic positions in Prussian blue (PB) to form various solid solutions KGaxFe1-x[Fe(CN)6] (0 < x < 1). Such solid solutions possess very high thermodynamic stability as expected from the parent PB structure. Consequently, a simple one-step (68)Ga-labeling method was developed for preparing a single-phase nanoparticulate bimodal PET/MRI imaging agent based on the PB structural platform. Unlike the typical (68)Ga-labelling reaction based on metal complexation, this novel chelator-free (68)Ga-labeling reaction was shown to be kinetically fast under the acidic conditions. The Ga(3+) ion does not hydrolyze, and affords the (68)Ga-labelled PB nanoparticles, which are easy to purify and have extremely high stability against radionuclidic leaching in aqueous solution.

  15. [MRI compatibility of deep brain stimulator].

    PubMed

    Zhang, Yujing

    2013-07-01

    Deep brain stimulation (DBS) therapy develops rapidly in clinical application. The structures of deep brain stimulator and magnetic resonance imaging (MRI) equipment are introduced, the interactions are analyzed, and the two compatible problems of radio frequency (RF) heating and imaging artifact are summarized in this paper.

  16. MRI in congenital duplication of urethra

    PubMed Central

    Bhadury, S; Parashari, Umesh C; Singh, Ragini; Kohli, Neera

    2009-01-01

    Congenital urethral duplication is a rare anomaly, with less than 200 cases described in the literature. The investigations that are usually performed are micturating cystourethrography (MCU) and retrograde urethrography (RGU), which can diagnose the presence of duplication but cannot diagnose the precise relationship of the duplicated urethra with other pelvic structures. MRI, because of the excellent tissue contrast that it provides and its multiplanar ability, can demonstrate with precision, the size, shape and position of the two urethras. We describe below a case where MRI was able to show this exquisitely. PMID:19881093

  17. Polarized noble gas MRI

    SciTech Connect

    Brookeman, James R.; Mugler, John P. III; Lange, Eduard E. de; Knight-Scott, Jack; Maier, Therese; Bogorad, Paul; Driehuys, Bastiaan; Cates, Gordon; Happer, William; Daniel, Thomas M.; Truwit, Jonathon D.

    1998-01-20

    The development of convenient methods to polarize liter quantities of the noble gases helium-3 and xenon-129 has provided the opportunity for a new MRI method to visualize the internal air spaces of the human lung. These spaces are usually poorly seen with hydrogen-based MRI, because of the limited water content of the lung and the low thermal polarization of the water protons achieved in conventional magnets. In addition, xenon, which has a relatively high solubility and a sufficiently persistent polarization level in blood and biological tissue, offers the prospect of providing perfusion images of the lung, brain and other organs.

  18. MRI in decompression illness.

    PubMed

    Hierholzer, J; Tempka, A; Stroszczynski, C; Amodio, F; Hosten, N; Haas, J; Felix, R

    2000-05-01

    We report a case of decompression illness in which the patient developed paraparesis during scuba diving after rapid ascent. MRI of the spine revealed a focal intramedullary lesion consistent with the symptoms. The pathophysiological and radiological aspects of spinal decompression illness are discussed.

  19. Multi-modal image registration: matching MRI with histology

    NASA Astrophysics Data System (ADS)

    Alic, Lejla; Haeck, Joost C.; Klein, Stefan; Bol, Karin; van Tiel, Sandra T.; Wielopolski, Piotr A.; Bijster, Magda; Niessen, Wiro J.; Bernsen, Monique; Veenland, Jifke F.; de Jong, Marion

    2010-03-01

    Spatial correspondence between histology and multi sequence MRI can provide information about the capabilities of non-invasive imaging to characterize cancerous tissue. However, shrinkage and deformation occurring during the excision of the tumor and the histological processing complicate the co registration of MR images with histological sections. This work proposes a methodology to establish a detailed 3D relation between histology sections and in vivo MRI tumor data. The key features of the methodology are a very dense histological sampling (up to 100 histology slices per tumor), mutual information based non-rigid B-spline registration, the utilization of the whole 3D data sets, and the exploitation of an intermediate ex vivo MRI. In this proof of concept paper, the methodology was applied to one tumor. We found that, after registration, the visual alignment of tumor borders and internal structures was fairly accurate. Utilizing the intermediate ex vivo MRI, it was possible to account for changes caused by the excision of the tumor: we observed a tumor expansion of 20%. Also the effects of fixation, dehydration and histological sectioning could be determined: 26% shrinkage of the tumor was found. The annotation of viable tissue, performed in histology and transformed to the in vivo MRI, matched clearly with high intensity regions in MRI. With this methodology, histological annotation can be directly related to the corresponding in vivo MRI. This is a vital step for the evaluation of the feasibility of multi-spectral MRI to depict histological groundtruth.

  20. Free-Breathing 3D Imaging of Right Ventricular Structure and Function Using Respiratory and Cardiac Self-Gated Cine MRI

    PubMed Central

    Zhu, Yanchun; Liu, Jing; Weinsaft, Jonathan; Spincemaille, Pascal; Nguyen, Thanh D.; Prince, Martin R.; Bao, Shanglian; Xie, Yaoqin; Wang, Yi

    2015-01-01

    Providing a movie of the beating heart in a single prescribed plane, cine MRI has been widely used in clinical cardiac diagnosis, especially in the left ventricle (LV). Right ventricular (RV) morphology and function are also important for the diagnosis of cardiopulmonary diseases and serve as predictors for the long term outcome. The purpose of this study is to develop a self-gated free-breathing 3D imaging method for RV quantification and to evaluate its performance by comparing it with breath-hold 2D cine imaging in 7 healthy volunteers. Compared with 2D, the 3D RV functional measurements show a reduction of RV end-diastole volume (RVEDV) by 10%, increase of RV end-systole volume (RVESV) by 1.8%, reduction of RV systole volume (RVSV) by 21%, and reduction of RV ejection fraction (RVEF) by 12%. High correlations between the two techniques were found (RVEDV: 0.94; RVESV: 0.85; RVSV: 0.95; and RVEF: 0.89). Compared with 2D, the 3D image quality measurements show a small reduction in blood SNR, myocardium-blood CNR, myocardium contrast, and image sharpness. In conclusion, the proposed self-gated free-breathing 3D cardiac cine imaging technique provides comparable image quality and correlated functional measurements to those acquired with the multiple breath-hold 2D technique in RV. PMID:26185764

  1. Brain Morphometry using MRI in Schizophrenia Patients

    NASA Astrophysics Data System (ADS)

    Abanshina, I.; Pirogov, Yu.; Kupriyanov, D.; Orlova, V.

    2010-01-01

    Schizophrenia has been the focus of intense neuroimaging research. Although its fundamental pathobiology remains elusive, neuroimaging studies provide evidence of abnormalities of cerebral structure and function in patients with schizophrenia. We used morphometry as a quantitative method for estimation of volume of brain structures. Seventy eight right-handed subjects aged 18-45 years were exposed to MRI-examination. Patients were divided into 3 groups: patients with schizophrenia, their relatives and healthy controls. The volumes of interested structures (caudate nucleus, putamen, ventricles, frontal and temporal lobe) were measured using T2-weighted MR-images. Correlations between structural differences and functional deficit were evaluated.

  2. Alterations of Gray and White Matter Networks in Patients with Obsessive-Compulsive Disorder: A Multimodal Fusion Analysis of Structural MRI and DTI Using mCCA+jICA.

    PubMed

    Kim, Seung-Goo; Jung, Wi Hoon; Kim, Sung Nyun; Jang, Joon Hwan; Kwon, Jun Soo

    2015-01-01

    Many of previous neuroimaging studies on neuronal structures in patients with obsessive-compulsive disorder (OCD) used univariate statistical tests on unimodal imaging measurements. Although the univariate methods revealed important aberrance of local morphometry in OCD patients, the covariance structure of the anatomical alterations remains unclear. Motivated by recent developments of multivariate techniques in the neuroimaging field, we applied a fusion method called "mCCA+jICA" on multimodal structural data of T1-weighted magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) of 30 unmedicated patients with OCD and 34 healthy controls. Amongst six highly correlated multimodal networks (p < 0.0001), we found significant alterations of the interrelated gray and white matter networks over occipital and parietal cortices, frontal interhemispheric connections and cerebella (False Discovery Rate q ≤ 0.05). In addition, we found white matter networks around basal ganglia that correlated with a subdimension of OC symptoms, namely 'harm/checking' (q ≤ 0.05). The present study not only agrees with the previous unimodal findings of OCD, but also quantifies the association of the altered networks across imaging modalities. PMID:26038825

  3. Alterations of Gray and White Matter Networks in Patients with Obsessive-Compulsive Disorder: A Multimodal Fusion Analysis of Structural MRI and DTI Using mCCA+jICA

    PubMed Central

    Kim, Seung-Goo; Jung, Wi Hoon; Kim, Sung Nyun; Jang, Joon Hwan; Kwon, Jun Soo

    2015-01-01

    Many of previous neuroimaging studies on neuronal structures in patients with obsessive-compulsive disorder (OCD) used univariate statistical tests on unimodal imaging measurements. Although the univariate methods revealed important aberrance of local morphometry in OCD patients, the covariance structure of the anatomical alterations remains unclear. Motivated by recent developments of multivariate techniques in the neuroimaging field, we applied a fusion method called “mCCA+jICA” on multimodal structural data of T1-weighted magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) of 30 unmedicated patients with OCD and 34 healthy controls. Amongst six highly correlated multimodal networks (p < 0.0001), we found significant alterations of the interrelated gray and white matter networks over occipital and parietal cortices, frontal interhemispheric connections and cerebella (False Discovery Rate q ≤ 0.05). In addition, we found white matter networks around basal ganglia that correlated with a subdimension of OC symptoms, namely ‘harm/checking’ (q ≤ 0.05). The present study not only agrees with the previous unimodal findings of OCD, but also quantifies the association of the altered networks across imaging modalities. PMID:26038825

  4. Structural and resting-state MRI detects regional brain differences in young and mid-age healthy APOE-e4 carriers compared with non-APOE-e4 carriers.

    PubMed

    Dowell, Nicholas G; Evans, Simon L; Tofts, Paul S; King, Sarah L; Tabet, Naji; Rusted, Jennifer M

    2016-05-01

    The presence of the e4 allele of the apolipoprotein E (APOE) gene is the best-known genetic risk factor for Alzheimer's disease. In this study, we investigated the link between functional and behavioural differences and regional brain volume and cortical thickness differences in those who carry the e4 allele (e4+) and those who only carry the e3 allele (e3/e3). We studied these genotype populations in two age groups: a young group (average age, 21 years) and a mid-age group (average age, 50 years). High-resolution T1 -weighted MRI scans were analysed with Freesurfer to measure regional white matter brain volume and cortical thickness differences between genotype groups at each age. These data were correlated with behavioural findings in the same cohort. Resting-state MRI was also conducted to identify differences in underlying brain functional connectivity. We found that there was a positive correlation between the thickness of the parahippocampal cortex in young e4+ individuals and performance on an episodic memory task. Young e4+ individuals also showed a positive correlation between white matter volume in the left anterior cingulate and performance on a covert attention task. At mid-age, e4+ individuals had structural differences relative to e3/e3 individuals in these areas: the parahippocampal cortex was thicker and white matter volume in the left anterior cingulate was greater than in e3/e3 individuals. We discuss the possibility that an over-engagement with these regions by e4+ individuals in youth may have a neurogenic effect that is observable later in life. The cuneus appears to be an important region for APOE-driven differences in the brain, with greater functional connectivity among young e3/e3 individuals and greater white matter volume in young e4+ individuals.

  5. Analysis of the Metabolic and Structural Brain Changes in Patients With Torture-Related Post-Traumatic Stress Disorder (TR-PTSD) Using ¹⁸F-FDG PET and MRI.

    PubMed

    Zandieh, Shahin; Bernt, Reinhard; Knoll, Peter; Wenzel, Thomas; Hittmair, Karl; Haller, Joerg; Hergan, Klaus; Mirzaei, Siroos

    2016-04-01

    Many people exposed to torture later suffer from torture-related post-traumatic stress disorder (TR-PTSD). The aim of this study was to analyze the morphologic and functional brain changes in patients with TR-PTSD using magnetic resonance imaging (MRI) and positron emission tomography (PET). This study evaluated 19 subjects. Thirteen subcortical brain structures were evaluated using FSL software. On the T1-weighted images, normalized brain volumes were measured using SIENAX software. The study compared the volume of the brain and 13 subcortical structures in 9 patients suffering from TR-PTSD after torture and 10 healthy volunteers (HV). Diffusion-weighted imaging (DWI) was performed in the transverse plane. In addition, the 18F-FDG PET data were evaluated to identify the activity of the elected regions. The mean left hippocampal volume for the TR-PTSD group was significantly lower than in the HV group (post hoc test (Bonferroni) P < 0.001). There was a significant difference between the gray matter volume of the patients with TR-PTSD and the HV group (post hoc test (Bonferroni) P < 0.001). The TR-PTSD group showed low significant expansion of the ventricles in contrast to the HV group (post hoc test (Bonferroni) P < 0.001). Diffusion-weighted imaging revealed significant differences in the right frontal lobe and the left occipital lobe between the TR-PTSD and HV group (post hoc test (Bonferroni) P < 0.001). Moderate hypometabolism was noted in the occipital lobe in 6 of the 9 patients with TR-PTSD, in the temporal lobe in 1 of the 9 patients, and in the caudate nucleus in 5 of the 9 patients. In 2 cases, additional hypometabolism was observed in the posterior cingulate cortex and in the parietal and frontal lobes. The findings from this study show that TR-PTSD might have a deleterious influence on a set of specific brain structures. This study also demonstrated that PET combined with MRI is sensitive in detecting possible metabolic and structural

  6. Analysis of the Metabolic and Structural Brain Changes in Patients With Torture-Related Post-Traumatic Stress Disorder (TR-PTSD) Using 18F-FDG PET and MRI

    PubMed Central

    Zandieh, Shahin; Bernt, Reinhard; Knoll, Peter; Wenzel, Thomas; Hittmair, Karl; Haller, Joerg; Hergan, Klaus; Mirzaei, Siroos

    2016-01-01

    Abstract Many people exposed to torture later suffer from torture-related post-traumatic stress disorder (TR-PTSD). The aim of this study was to analyze the morphologic and functional brain changes in patients with TR-PTSD using magnetic resonance imaging (MRI) and positron emission tomography (PET). This study evaluated 19 subjects. Thirteen subcortical brain structures were evaluated using FSL software. On the T1-weighted images, normalized brain volumes were measured using SIENAX software. The study compared the volume of the brain and 13 subcortical structures in 9 patients suffering from TR-PTSD after torture and 10 healthy volunteers (HV). Diffusion-weighted imaging (DWI) was performed in the transverse plane. In addition, the 18F-FDG PET data were evaluated to identify the activity of the elected regions. The mean left hippocampal volume for the TR-PTSD group was significantly lower than in the HV group (post hoc test (Bonferroni) P < 0.001). There was a significant difference between the gray matter volume of the patients with TR-PTSD and the HV group (post hoc test (Bonferroni) P < 0.001). The TR-PTSD group showed low significant expansion of the ventricles in contrast to the HV group (post hoc test (Bonferroni) P < 0.001). Diffusion-weighted imaging revealed significant differences in the right frontal lobe and the left occipital lobe between the TR-PTSD and HV group (post hoc test (Bonferroni) P < 0.001). Moderate hypometabolism was noted in the occipital lobe in 6 of the 9 patients with TR-PTSD, in the temporal lobe in 1 of the 9 patients, and in the caudate nucleus in 5 of the 9 patients. In 2 cases, additional hypometabolism was observed in the posterior cingulate cortex and in the parietal and frontal lobes. The findings from this study show that TR-PTSD might have a deleterious influence on a set of specific brain structures. This study also demonstrated that PET combined with MRI is sensitive in detecting possible metabolic and

  7. Analysis of the Metabolic and Structural Brain Changes in Patients With Torture-Related Post-Traumatic Stress Disorder (TR-PTSD) Using ¹⁸F-FDG PET and MRI.

    PubMed

    Zandieh, Shahin; Bernt, Reinhard; Knoll, Peter; Wenzel, Thomas; Hittmair, Karl; Haller, Joerg; Hergan, Klaus; Mirzaei, Siroos

    2016-04-01

    Many people exposed to torture later suffer from torture-related post-traumatic stress disorder (TR-PTSD). The aim of this study was to analyze the morphologic and functional brain changes in patients with TR-PTSD using magnetic resonance imaging (MRI) and positron emission tomography (PET). This study evaluated 19 subjects. Thirteen subcortical brain structures were evaluated using FSL software. On the T1-weighted images, normalized brain volumes were measured using SIENAX software. The study compared the volume of the brain and 13 subcortical structures in 9 patients suffering from TR-PTSD after torture and 10 healthy volunteers (HV). Diffusion-weighted imaging (DWI) was performed in the transverse plane. In addition, the 18F-FDG PET data were evaluated to identify the activity of the elected regions. The mean left hippocampal volume for the TR-PTSD group was significantly lower than in the HV group (post hoc test (Bonferroni) P < 0.001). There was a significant difference between the gray matter volume of the patients with TR-PTSD and the HV group (post hoc test (Bonferroni) P < 0.001). The TR-PTSD group showed low significant expansion of the ventricles in contrast to the HV group (post hoc test (Bonferroni) P < 0.001). Diffusion-weighted imaging revealed significant differences in the right frontal lobe and the left occipital lobe between the TR-PTSD and HV group (post hoc test (Bonferroni) P < 0.001). Moderate hypometabolism was noted in the occipital lobe in 6 of the 9 patients with TR-PTSD, in the temporal lobe in 1 of the 9 patients, and in the caudate nucleus in 5 of the 9 patients. In 2 cases, additional hypometabolism was observed in the posterior cingulate cortex and in the parietal and frontal lobes. The findings from this study show that TR-PTSD might have a deleterious influence on a set of specific brain structures. This study also demonstrated that PET combined with MRI is sensitive in detecting possible metabolic and structural

  8. Nonaxisymmetric modes of MRI in dissipative Keplerian disks

    NASA Astrophysics Data System (ADS)

    Kitchatinov, L. L.; Rüdiger, G.

    2010-04-01

    Aims: Deviations from the axial symmetry are necessary to maintain self-sustained MRI-turbulence by a dynamo mechanism. We define the parameter region where the nonaxisymmetric MRI modes are excited and study their geometries and growth rates. Methods: The linear eigenvalue problem for global nonaxisymmetric modes of standard-MRI in Keplerian disks is solved numerically with allowance for finite diffusion. Results: For small magnetic Prandtl numbers the microscopic viscosity completely drops out of the analysis so that the stability maps and the growth rates expressed in terms of the magnetic Reynolds number Rm and the Lundquist number S do not depend on the magnetic Prandtl number Pm. The minimum magnetic field for the onset of nonaxisymmetric MRI grows with the rotation rate. For a given S all nonaxisymmetric modes disappear for a sufficiently large Rm. This is a consequence of the radial fine-structure of the nonaxisymmetric modes resulting from the winding effect of differential rotation. It is this fine-structure which also provides serious resolution problems for the numerical simulation of MRI at large Rm. Conclusions: For weak magnetic fields slightly above the critical value for the onset of MRI only axisymmetric modes are unstable. Nonaxisymmetric modes need stronger fields and not too large Rm. If Pm is small its real value does not play any role in MRI.

  9. Disconnection Mechanism and Regional Cortical Atrophy Contribute to Impaired Processing of Facial Expressions and Theory of Mind in Multiple Sclerosis: A Structural MRI Study

    PubMed Central

    Mike, Andrea; Strammer, Erzsebet; Aradi, Mihaly; Orsi, Gergely; Perlaki, Gabor; Hajnal, Andras; Sandor, Janos; Banati, Miklos; Illes, Eniko; Zaitsev, Alexander; Herold, Robert; Guttmann, Charles R. G.; Illes, Zsolt

    2013-01-01

    Successful socialization requires the ability of understanding of others’ mental states. This ability called as mentalization (Theory of Mind) may become deficient and contribute to everyday life difficulties in multiple sclerosis. We aimed to explore the impact of brain pathology on mentalization performance in multiple sclerosis. Mentalization performance of 49 patients with multiple sclerosis was compared to 24 age- and gender matched healthy controls. T1- and T2-weighted three-dimensional brain MRI images were acquired at 3Tesla from patients with multiple sclerosis and 18 gender- and age matched healthy controls. We assessed overall brain cortical thickness in patients with multiple sclerosis and the scanned healthy controls, and measured the total and regional T1 and T2 white matter lesion volumes in patients with multiple sclerosis. Performances in tests of recognition of mental states and emotions from facial expressions and eye gazes correlated with both total T1-lesion load and regional T1-lesion load of association fiber tracts interconnecting cortical regions related to visual and emotion processing (genu and splenium of corpus callosum, right inferior longitudinal fasciculus, right inferior fronto-occipital fasciculus, uncinate fasciculus). Both of these tests showed correlations with specific cortical areas involved in emotion recognition from facial expressions (right and left fusiform face area, frontal eye filed), processing of emotions (right entorhinal cortex) and socially relevant information (left temporal pole). Thus, both disconnection mechanism due to white matter lesions and cortical thinning of specific brain areas may result in cognitive deficit in multiple sclerosis affecting emotion and mental state processing from facial expressions and contributing to everyday and social life difficulties of these patients. PMID:24349280

  10. Mapping Primary Gyrogenesis During Fetal Development in Primate Brains: High-Resolution in Utero Structural MRI of Fetal Brain Development in Pregnant Baboons

    PubMed Central

    Kochunov, Peter; Castro, Carlos; Davis, Duff; Dudley, Donald; Brewer, Jordan; Zhang, Yi; Kroenke, Christopher D.; Purdy, David; Fox, Peter T.; Simerly, Calvin; Schatten, Gerald

    2010-01-01

    The global and regional changes in the fetal cerebral cortex in primates were mapped during primary gyrification (PG; weeks 17–25 of 26 weeks total gestation). Studying pregnant baboons using high-resolution MRI in utero, measurements included cerebral volume, cortical surface area, gyrification index and length and depth of 10 primary cortical sulci. Seven normally developing fetuses were imaged in two animals longitudinally and sequentially. We compared these results to those on PG that from the ferret studies and analyzed them in the context of our recent studies of phylogenetics of cerebral gyrification. We observed that in both primates and non-primates, the cerebrum undergoes a very rapid transformation into the gyrencephalic state, subsequently accompanied by an accelerated growth in brain volume and cortical surface area. However, PG trends in baboons exhibited some critical differences from those observed in ferrets. For example, in baboons, the growth along the long (length) axis of cortical sulci was unrelated to the growth along the short (depth) axis and far outpaced it. Additionally, the correlation between the rate of growth along the short sulcal axis and heritability of sulcal depth was negative and approached significance (r = −0.60; p < 0.10), while the same trend for long axis was positive and not significant (p = 0.3; p = 0.40). These findings, in an animal that shares a highly orchestrated pattern of PG with humans, suggest that ontogenic processes that influence changes in sulcal length and depth are diverse and possibly driven by different factors in primates than in non-primates. PMID:20631812

  11. Disconnection mechanism and regional cortical atrophy contribute to impaired processing of facial expressions and theory of mind in multiple sclerosis: a structural MRI study.

    PubMed

    Mike, Andrea; Strammer, Erzsebet; Aradi, Mihaly; Orsi, Gergely; Perlaki, Gabor; Hajnal, Andras; Sandor, Janos; Banati, Miklos; Illes, Eniko; Zaitsev, Alexander; Herold, Robert; Guttmann, Charles R G; Illes, Zsolt

    2013-01-01

    Successful socialization requires the ability of understanding of others' mental states. This ability called as mentalization (Theory of Mind) may become deficient and contribute to everyday life difficulties in multiple sclerosis. We aimed to explore the impact of brain pathology on mentalization performance in multiple sclerosis. Mentalization performance of 49 patients with multiple sclerosis was compared to 24 age- and gender matched healthy controls. T1- and T2-weighted three-dimensional brain MRI images were acquired at 3Tesla from patients with multiple sclerosis and 18 gender- and age matched healthy controls. We assessed overall brain cortical thickness in patients with multiple sclerosis and the scanned healthy controls, and measured the total and regional T1 and T2 white matter lesion volumes in patients with multiple sclerosis. Performances in tests of recognition of mental states and emotions from facial expressions and eye gazes correlated with both total T1-lesion load and regional T1-lesion load of association fiber tracts interconnecting cortical regions related to visual and emotion processing (genu and splenium of corpus callosum, right inferior longitudinal fasciculus, right inferior fronto-occipital fasciculus, uncinate fasciculus). Both of these tests showed correlations with specific cortical areas involved in emotion recognition from facial expressions (right and left fusiform face area, frontal eye filed), processing of emotions (right entorhinal cortex) and socially relevant information (left temporal pole). Thus, both disconnection mechanism due to white matter lesions and cortical thinning of specific brain areas may result in cognitive deficit in multiple sclerosis affecting emotion and mental state processing from facial expressions and contributing to everyday and social life difficulties of these patients.

  12. Eosinophilic granuloma: MRI manifestations.

    PubMed

    Beltran, J; Aparisi, F; Bonmati, L M; Rosenberg, Z S; Present, D; Steiner, G C

    1993-01-01

    The appearance on magnetic resonance imaging (MRI) of 16 cases of pathologically proven eosinophilic granuloma were reviewed retrospectively and correlated with the radiographic appearance of the lesion. The most common MR appearance (ten cases) was a focal lesion, surrounded by an extensive, ill-defined bone marrow and soft tissue reaction with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, considered to represent bone marrow and soft tissue edema (the flare phenomenon). The MRI manifestations of eosinophilic granuloma, especially during the early stages, are nonspecific, and may stimulate an aggressive lesion such as osteomyelitis or Ewings sarcoma, or other benign bone tumors such as osteoid osteoma or chondroblastoma. PMID:8480200

  13. Functional connectomics from resting-state fMRI

    PubMed Central

    Smith, Stephen M; Vidaurre, Diego; Beckmann, Christian F; Glasser, Matthew F; Jenkinson, Mark; Miller, Karla L; Nichols, Thomas E; Robinson, Emma; Salimi-Khorshidi, Gholamreza; Woolrich, Mark W; Barch, Deanna M; Uğurbil, Kamil; Van Essen, David C

    2014-01-01

    Spontaneous fluctuations in activity in different parts of the brain can be used to study functional brain networks. We review the use of resting-state functional MRI for the purpose of mapping the macroscopic functional connectome. After describing MRI acquisition and image processing methods commonly used to generate data in a form amenable to connectomics network analysis, we discuss different approaches for estimating network structure from that data. Finally, we describe new possibilities resulting from the high-quality rfMRI data being generated by the Human Connectome Project, and highlight some upcoming challenges in functional connectomics. PMID:24238796

  14. MRI studies in late-life mood disorders.

    PubMed

    Andreescu, Carmen; Aizenstein, Howard

    2012-01-01

    There are well-established patterns of structural brain changes associated with aging. The change in brain volume with age and with the diseases of aging presents a particular challenge for MRI studies in the elderly. Structural MRI is important for studies in normal aging, late-life depression, dementia, Alzheimer disease and other cognitive disorders to examine how age-associated changes in neuroanatomy are associated with specific age-related changes in brain function. Functional MRI has been a major advance for the fields of cognitive and affective neuroscience by allowing investigators to test theories of the underlying neural pathways controlling cognitive and emotional processes. In this chapter, we will review the contribution of MRI studies to late-life mood and anxiety disorders: major depression, bipolar disorder and anxiety disorders in late-life. PMID:22167336

  15. MRI Studies in Late-Life Mood Disorders

    PubMed Central

    Andreescu, Carmen

    2013-01-01

    There are well-established patterns of structural brain changes associated with aging. The change in brain volume with age and with the diseases of aging presents a particular challenge for MRI studies in the elderly. Structural MRI is important for studies in normal aging, late-life depression, dementia, Alzheimer disease and other cognitive disorders to examine how age-associated changes in neuroanatomy are associated with specific age-related changes in brain function. Functional MRI has been a major advance for the fields of cognitive and affective neuroscience by allowing investigators to test theories of the underlying neural pathways controlling cognitive and emotional processes. In this chapter, we will review the contribution of MRI studies to late-life mood and anxiety disorders: major depression, bipolar disorder and anxiety disorders in late-life. PMID:22167336

  16. Stability of MRI Turbulent Accretion Disks

    NASA Astrophysics Data System (ADS)

    Takahashi, H. R.; Masada, Y.

    2010-12-01

    We study the stability of geometrically thin accretion disks with non-standard α parameter, which characterizes the efficiency of the angular momentum transport. Following recent results of numerical simulations of the Magnetorotational instability (MRI) driven turbulence, we assume that α increases with the magnetic Prandtl number. By adopting Spitzer's microscopic diffusivities, we obtain local structures of geometrically thin accretion disks consistently including effects of MRI-driven turbulence. Since the magnetic Prandtl number increases with the temperature, the efficiency of the angular momentum transport and thus viscous heating rate are smaller for a larger radius when δ > 0. We find that such disks can be unstable to gravitational, thermal, and secular instabilities. It is most remarkable feature that the thermal and secular instabilities can grow in the middle part of accretion disks even when the radiation pressure is negligible, while the standard Shakura & Sunyaev's accretion disk (constant α) is stable to these instabilities. We conclude that it would be difficult to maintain the steady mass accretion state unless the Pm-dependence of the MRI-driven turbulence is weak. Consideration of Pm dependence of α due to the MRI-driven turbulence may make the phase transition of accretion disks less mysterious.

  17. Diffusion-MRI in neurodegenerative disorders.

    PubMed

    Goveas, Joseph; O'Dwyer, Laurence; Mascalchi, Mario; Cosottini, Mirco; Diciotti, Stefano; De Santis, Silvia; Passamonti, Luca; Tessa, Carlo; Toschi, Nicola; Giannelli, Marco

    2015-09-01

    The ability to image the whole brain through ever more subtle and specific methods/contrasts has come to play a key role in understanding the basis of brain abnormalities in several diseases. In magnetic resonance imaging (MRI), "diffusion" (i.e. the random, thermally-induced displacements of water molecules over time) represents an extraordinarily sensitive contrast mechanism, and the exquisite structural detail it affords has proven useful in a vast number of clinical as well as research applications. Since diffusion-MRI is a truly quantitative imaging technique, the indices it provides can serve as potential imaging biomarkers which could allow early detection of pathological alterations as well as tracking and possibly predicting subtle changes in follow-up examinations and clinical trials. Accordingly, diffusion-MRI has proven useful in obtaining information to better understand the microstructural changes and neurophysiological mechanisms underlying various neurodegenerative disorders. In this review article, we summarize and explore the main applications, findings, perspectives as well as challenges and future research of diffusion-MRI in various neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease and degenerative ataxias. PMID:25917917

  18. A Combined fMRI and DTI Examination of Functional Language Lateralization and Arcuate Fasciculus Structure: Effects of Degree versus Direction of Hand Preference

    ERIC Educational Resources Information Center

    Propper, Ruthe E.; O'Donnell, Lauren J.; Whalen, Stephen; Tie, Yanmei; Norton, Isaiah H.; Suarez, Ralph O.; Zollei, Lilla; Radmanesh, Alireza; Golby, Alexandra J.

    2010-01-01

    The present study examined the relationship between hand preference degree and direction, functional language lateralization in Broca's and Wernicke's areas, and structural measures of the arcuate fasciculus. Results revealed an effect of degree of hand preference on arcuate fasciculus structure, such that consistently-handed individuals,…

  19. SU-E-J-239: IMRT Planning of Prostate Cancer for a MRI-Linac Based On MRI Only

    SciTech Connect

    Chen, X; Prior, P; Paulson, E; Lawton, C; Li, X

    2014-06-01

    Purpose: : To investigate dosimetric differences between MRI- and CT-based IMRT planning for prostate cancer, the impact of a magnetic field in a MRI-Linac, and to explore the feasibility of IMRT planning based on MRI alone. Methods: IMRT plans were generated based on CT and MRI images acquired on two representative prostate-cancer patients using clinical dose volume constraints. A research planning system (Monaco, Elekta), which employs a Monte Carlo dose engine and includes a perpendicular magnetic field of 1.5T from an MRI-Linac, was used. Bulk electron density assignments based on organ-specific values from ICRU 46 were used to convert MRI (T2) to pseudo CT. With the same beam configuration as in the original CT plan, 5 additional plans were generated based on CT or MRI, with or without optimization (i.e., just recalculation) and with or without the magnetic field. The plan quality in terms of commonly used dose volume (DV) parameters for all plans was compared. The statistical uncertainty on dose was < 1%. Results: For plans with the same contour set but without re-optimization, the DV parameters were different from those for the original CT plan, mostly less than 5% with a few exceptions. These differences were reduced to mostly less than 3% when the plans were re-optimized. For plans with contours from MRI, the differences in the DV parameters varied depending on the difference in the contours as compared to CT. For the optimized plans with contours from MR, the differences for PTV were less than 3%. Conclusion: The prostate IMRT plans based on MRI-only for a MR-Linac were practically similar as compared to the CT plan under the same beam and optimization configuration if the difference on the structure delineation is excluded, indicating the feasibility of using MRI-only for prostate IMRT.

  20. Sodium MRI: Methods and applications

    PubMed Central

    Madelin, Guillaume; Lee, Jae-Seung; Regatte, Ravinder R.; Jerschow, Alexej

    2014-01-01

    Sodium NMR spectroscopy and MRI have become popular in recent years through the increased availability of high-field MRI scanners, advanced scanner hardware and improved methodology. Sodium MRI is being evaluated for stroke and tumor detection, for breast cancer studies, and for the assessment of osteoarthritis and muscle and kidney functions, to name just a few. In this article, we aim to present an up-to-date review of the theoretical background, the methodology, the challenges and limitations, and current and potential new applications of sodium MRI. PMID:24815363

  1. Fusion of PET and MRI for Hybrid Imaging

    NASA Astrophysics Data System (ADS)

    Cho, Zang-Hee; Son, Young-Don; Kim, Young-Bo; Yoo, Seung-Schik

    Recently, the development of the fusion PET-MRI system has been actively studied to meet the increasing demand for integrated molecular and anatomical imaging. MRI can provide detailed anatomical information on the brain, such as the locations of gray and white matter, blood vessels, axonal tracts with high resolution, while PET can measure molecular and genetic information, such as glucose metabolism, neurotransmitter-neuroreceptor binding and affinity, protein-protein interactions, and gene trafficking among biological tissues. State-of-the-art MRI systems, such as the 7.0 T whole-body MRI, now can visualize super-fine structures including neuronal bundles in the pons, fine blood vessels (such as lenticulostriate arteries) without invasive contrast agents, in vivo hippocampal substructures, and substantia nigra with excellent image contrast. High-resolution PET, known as High-Resolution Research Tomograph (HRRT), is a brain-dedicated system capable of imaging minute changes of chemicals, such as neurotransmitters and -receptors, with high spatial resolution and sensitivity. The synergistic power of the two, i.e., ultra high-resolution anatomical information offered by a 7.0 T MRI system combined with the high-sensitivity molecular information offered by HRRT-PET, will significantly elevate the level of our current understanding of the human brain, one of the most delicate, complex, and mysterious biological organs. This chapter introduces MRI, PET, and PET-MRI fusion system, and its algorithms are discussed in detail.

  2. Gradient echo MRI

    PubMed Central

    Copenhaver, B R.; Shin, J; Warach, S; Butman, J A.; Saver, J L.; Kidwell, C S.

    2009-01-01

    Background: Recent studies have demonstrated that gradient echo (GRE) MRI sequences are as accurate as CT for the detection of intracerebral hemorrhage (ICH) in the context of acute stroke. However, many physicians who currently read acute stroke imaging studies may be unfamiliar with interpretation of GRE images. Methods: An NIH Web-based training program was developed including a pretest, tutorial, and posttest. Physicians involved in the care of acute stroke patients were encouraged to participate. The tutorial covered acute, chronic, and mimic hemorrhages as they appear on CT, diffusion-weighted imaging, and GRE sequences. Ability of users to identify ICH presence, type, and age on GRE was compared from the pretest to posttest timepoint. Results: A total of 104 users completed the tutorial. Specialties represented included general radiology (42%), general neurology (16%), neuroradiology (15%), stroke neurology (14%), emergency medicine (1%), and other (12%). Median overall score improved pretest to posttest from 66.7% to 83.3%, p < 0.001. Improvement by category was as follows: acute ICH, 66.7%–100%, p < 0.001; chronic ICH, 33.3%–66.7%, p < 0.001; ICH negatives/mimics, 100%–100%, p = 0.787. Sensitivity for identification of acute hemorrhage improved from 68.2% to 96.4%. Conclusions: Physicians involved in acute stroke care achieved significant improvement in gradient echo (GRE) hemorrhage interpretation after completing the NIH GRE MRI tutorial. This indicates that a Web-based tutorial may be a viable option for the widespread education of physicians to achieve an acceptable level of diagnostic accuracy at reading GRE MRI, thus enabling confident acute stroke treatment decisions. GLOSSARY AHA/ASA = American Heart Association/American Stroke Association; CME = continuing medical education; DWI = diffusion-weighted imaging; GRE = gradient echo; ICH = intracerebral hemorrhage; tPA = tissue plasminogen activator. PMID:19414724

  3. Occupational exposure in MRI

    PubMed Central

    Mcrobbie, D W

    2012-01-01

    This article reviews occupational exposure in clinical MRI; it specifically considers units of exposure, basic physical interactions, health effects, guideline limits, dosimetry, results of exposure surveys, calculation of induced fields and the status of the European Physical Agents Directive. Electromagnetic field exposure in MRI from the static field B0, imaging gradients and radiofrequency transmission fields induces electric fields and currents in tissue, which are responsible for various acute sensory effects. The underlying theory and its application to the formulation of incident and induced field limits are presented. The recent International Commission on Non-Ionizing Radiation Protection (ICNIRP) Bundesministerium für Arbeit und Soziales and Institute of Electrical and Electronics Engineers limits for incident field exposure are interpreted in a manner applicable to MRI. Field measurements show that exposure from movement within the B0 fringe field can exceed ICNIRP reference levels within 0.5 m of the bore entrance. Rate of change of field dB/dt from the imaging gradients is unlikely to exceed the new limits, although incident field limits can be exceeded for radiofrequency (RF) exposure within 0.2–0.5 m of the bore entrance. Dosimetric surveys of routine clinical practice show that staff are exposed to peak values of 42±24% of B0, with time-averaged exposures of 5.2±2.8 mT for magnets in the range 0.6–4 T. Exposure to time-varying fields arising from movement within the B0 fringe resulted in peak dB/dt of approximately 2 T s−1. Modelling of induced electric fields from the imaging gradients shows that ICNIRP-induced field limits are unlikely to be exceeded in most situations; however, movement through the static field may still present a problem. The likely application of the limits is discussed with respect to the reformulation of the European Union (EU) directive and its possible implications for MRI. PMID:22457400

  4. Nanoformulations for molecular MRI

    PubMed Central

    Tu, Chuqiao; Louie, Angelique Y.

    2012-01-01

    Nanoscale contrast agents have shown the ability to increase the detection sensitivity of MRI by several orders of magnitude, endowing this traditionally macroscopic modality with the ability to observe unique molecular signatures. Herein, we describe three types of nanoparticulate contrast agents: iron oxide nanoparticles, gadolinium-based nanoparticles, and bio-essential manganese, cobalt, nickel, and copper ion-containing nanoformulations. Some of these agents have been approved for clinical use, but more are still under development for medical imaging. The advantages and disadvantages of each nanoformulation, in terms of intrinsic magnetism, ease of synthesis, and biodistribution, etc. are discussed. PMID:22488901

  5. Ex vivo diffusion tensor MRI reflects microscopic structural remodeling associated with aging and disease progression in normal and cardiomyopathic Syrian hamsters

    PubMed Central

    Li, Wen; Lu, Ming; Banerjee, Suhanti; Zhong, Jia; Ye, Allen; Molter, Joseph; Yu, Xin

    2010-01-01

    Dilated cardiomyopathy (DCM) is a major cause of mortality and morbidity in cardiac patients. Aging is often an ignored etiology of pathological conditions. Quantification of DCM and aging associated cardiac structural remodeling is important in guiding and evaluating therapeutic interventions. Diffusion tensor magnetic resonance imaging (DTMRI) has recently been used for nondestructive characterization of three-dimensional myofiber structure. In this study, we explored the potential of DTMRI in delineating microscopic structural remodeling in aging and DCM hearts. Six month (n = 10) and nine month old (n = 11) DCM (TO-2) hamsters and their age-matched controls (F1β) were characterized. Both aging and DCM hearts showed increased diffusivity and decreased diffusion anisotropy. DTMRI images of DCM hearts also revealed a subgroup of imaging pixels characterized by decreased radial diffusivity and increased FA. The location of these pixels showed qualitative agreement with regions of calcium deposition determined by X-ray CT imaging. Histological analysis confirmed expanded extracellular space in aging and DCM hearts as well as substantial calcium deposition in DCM hearts. These results suggest that DTMRI may provide a noninvasive technique to delineate structural remodeling associated with aging and DCM progression at the tissue and cellular level without the use of an exogenous contrast agent. PMID:19434665

  6. Hyperoxia and Functional MRI.

    PubMed

    Bulte, Daniel

    2016-01-01

    Oxygen plays a fundamental role in functional magnetic resonance imaging (FMRI). Blood oxygenation level-dependent (BOLD) imaging is the foundation stone of all FMRI and is still the essential workhorse of the vast majority of FMRI procedures. Hemoglobin may provide the magnetic properties that allow the technique to work, but it is oxygen that allows the contrast to effectively be switched on or off, and it is oxygen that we are interested in tracking in order to observe the oxygen metabolism changes. In general the changes in venous oxygen saturation are observed in order to infer changes in the correlated mechanisms, which can include changes in cerebral blood flow, metabolism, and the fraction of inspired oxygen. By independently manipulating the fraction of inspired oxygen it is possible to alter the amount of dissolved oxygen in the plasma, the venous saturation, or even the blood flow. The effects that these changes have on the observed MRI signal can be either a help or a hindrance depending on how well the changes induced are understood. The administration of supplemental inspired oxygen is in a unique position to provide a flexible, noninvasive, inexpensive, patient-friendly addition to the MRI toolkit to enable investigations to look beyond statistics and regions of interest, and actually produce calibrated, targeted measurements of blood flow, metabolism or pathology. PMID:27343097

  7. MRI of the glenoid labrum with gross anatomic correlation

    SciTech Connect

    Longo, C.; Trudell, D.; Resnick, D.

    1996-05-01

    The objective of this pictorial essay is to illustrate the magnetic resonance image (MRI) appearance of the glenoid labrum and the perilabral structures with and without instillation of intraarticular contrast material. Ten cadaveric shoulder specimens underwent axial MRI using various MR pulse sequences. The shoulders then were transversely sectioned, and tile gross morphology of the labrum and perilabral structures was evaluated and correlated with the MR images. The contrast-enhanced sequences allowed for improved anatomic visualization of the structures evaluated. 23 refs., 13 figs.

  8. DT-MRI segmentation using graph cuts

    NASA Astrophysics Data System (ADS)

    Weldeselassie, Yonas T.; Hamarneh, Ghassan

    2007-03-01

    An important problem in medical image analysis is the segmentation of anatomical regions of interest. Once regions of interest are segmented, one can extract shape, appearance, and structural features that can be analyzed for disease diagnosis or treatment evaluation. Diffusion tensor magnetic resonance imaging (DT-MRI) is a relatively new medical imaging modality that captures unique water diffusion properties and fiber orientation information of the imaged tissues. In this paper, we extend the interactive multidimensional graph cuts segmentation technique to operate on DT-MRI data by utilizing latest advances in tensor calculus and diffusion tensor dissimilarity metrics. The user interactively selects certain tensors as object ("obj") or background ("bkg") to provide hard constraints for the segmentation. Additional soft constraints incorporate information about both regional tissue diffusion as well as boundaries between tissues of different diffusion properties. Graph cuts are used to find globally optimal segmentation of the underlying 3D DT-MR image among all segmentations satisfying the constraints. We develop a graph structure from the underlying DT-MR image with the tensor voxels corresponding to the graph vertices and with graph edge weights computed using either Log-Euclidean or the J-divergence tensor dissimilarity metric. The topology of our segmentation is unrestricted and both obj and bkg segments may consist of several isolated parts. We test our method on synthetic DT data and apply it to real 2D and 3D MRI, providing segmentations of the corpus callosum in the brain and the ventricles of the heart.

  9. Structural brain changes associated with antipsychotic treatment in schizophrenia as revealed by voxel-based morphometric MRI: an activation likelihood estimation meta-analysis

    PubMed Central

    2013-01-01

    Background The results of multiple studies on the association between antipsychotic use and structural brain changes in schizophrenia have been assessed only in qualitative literature reviews to date. We aimed to perform a meta-analysis of voxel-based morphometry (VBM) studies on this association to quantitatively synthesize the findings of these studies. Methods A systematic computerized literature search was carried out through MEDLINE/PubMed, EMBASE, ISI Web of Science, SCOPUS and PsycINFO databases aiming to identify all VBM studies addressing this question and meeting predetermined inclusion criteria. All studies reporting coordinates representing foci of structural brain changes associated with antipsychotic use were meta-analyzed by using the activation likelihood estimation technique, currently the most sophisticated and best-validated tool for voxel-wise meta-analysis of neuroimaging studies. Results Ten studies (five cross-sectional and five longitudinal) met the inclusion criteria and comprised a total of 548 individuals (298 patients on antipsychotic drugs and 250 controls). Depending on the methodologies of the selected studies, the control groups included healthy subjects, drug-free patients, or the same patients evaluated repeatedly in longitudinal comparisons (i.e., serving as their own controls). A total of 102 foci associated with structural alterations were retrieved. The meta-analysis revealed seven clusters of areas with consistent structural brain changes in patients on antipsychotics compared to controls. The seven clusters included four areas of relative volumetric decrease in the left lateral temporal cortex [Brodmann area (BA) 20], left inferior frontal gyrus (BA 44), superior frontal gyrus extending to the left middle frontal gyrus (BA 6), and right rectal gyrus (BA 11), and three areas of relative volumetric increase in the left dorsal anterior cingulate cortex (BA 24), left ventral anterior cingulate cortex (BA 24) and right putamen

  10. Anatomo-clinical overlapping maps (AnaCOM): a new method to create anatomo-functional maps from neuropsychological tests and structural MRI scan of subjects with brain lesions

    NASA Astrophysics Data System (ADS)

    Kinkingnehun, Serge R. J.; du Boisgueheneuc, Foucaud; Golmard, Jean-Louis; Zhang, Sandy X.; Levy, Richard; Dubois, Bruno

    2004-04-01

    We have developed a new technique to analyze correlations between brain anatomy and its neurological functions. The technique is based on the anatomic MRI of patients with brain lesions who are administered neuropsychological tests. Brain lesions of the MRI scans are first manually segmented. The MRI volumes are then normalized to a reference map, using the segmented area as a mask. After normalization, the brain lesions of the MRI are segmented again in order to redefine the border of the lesions in the context of the normalized brain. Once the MRI is segmented, the patient's score on the neuropsychological test is assigned to each voxel in the lesioned area, while the rest of the voxels of the image are set to 0. Subsequently, the individual patient's MRI images are superimposed, and each voxel is reassigned the average score of the patients who have a lesion at that voxel. A threshold is applied to remove regions having less than three overlaps. This process leads to an anatomo-functional map that links brain areas to functional loss. Other maps can be created to aid in analyzing the functional maps, such as one that indicates the 95% confidence interval of the averaged scores for each area. This anatomo-clinical overlapping map (AnaCOM) method was used to obtain functional maps from patients with lesions in the superior frontal gyrus. By finding particular subregions more responsible for a particular deficit, this method can generate new hypotheses to be tested by conventional group methods.

  11. Fabrication of hollow and porous structured GdVO4:Dy3+ nanospheres as anticancer drug carrier and MRI contrast agent.

    PubMed

    Kang, Xiaojiao; Yang, Dongmei; Ma, Ping'an; Dai, Yunlu; Shang, Mengmeng; Geng, Dongling; Cheng, Ziyong; Lin, Jun

    2013-01-29

    Hollow and porous structured GdVO(4):Dy(3+) spheres were fabricated via a facile self-sacrificing templated method. The large cavity allows them to be used as potential hosts for therapeutic drugs, and the porous feature of the shell allows guest molecules to easily pass through the void space and surrounding environment. The samples show strong yellow-green emission of Dy(3+) (485 nm, (4)F(9/2) → (6)H(15/2); 575 nm, (4)F(9/2) → (6)H(13/2)) under UV excitation. The emission intensity of GdVO(4):Dy(3+) was weakened after encapsulation of anticancer drug (doxorubicin hydrochloride, DOX) and gradually restored with the cumulative released time of DOX. These hollow spheres were nontoxic to HeLa cells, while DOX-loaded samples led to apparent cytotoxicity as a result of the sustained release of DOX. ICP measurement indicates that free toxic Gd ions can hardly dissolate from the matrix. The endocytosis process of DOX-loaded hollow spheres is observed using confocal laser scanning microscopy (CLSM). Furthermore, GdVO(4):Dy(3+) hollow spheres can be used for T(1)-weighted magnetic resonance (MR) imaging. These results implicate that the luminescent GdVO(4):Dy(3+) spheres with hollow and porous structure are promising platforms for drug storage/release and MR imaging.

  12. Magnetostimulation in MRI.

    PubMed

    Irnich, W; Schmitt, F

    1995-05-01

    In national and international bodies, there is active discussion of appropriate safety regulations of levels of magnetic field strength in MRI. Present limits are usually expressed in terms of the switching rate dB/dt, but the validity of this is open to debate. Application of the fundamental law of electrostimulation is well-established, both on theoretical and experimental grounds. Application of this law, in combination with Maxwell's law, yields a very simple equation that we call the fundamental law of magnetostimulation. This law has the hyperbolic form of a strength-duration curve and allows an estimation of the lowest possible value of the magnetic flux density capable of stimulating nerves and muscles. Calculations prove that the threshold for heart excitation is much higher than those for nerve and muscle stimulations. Experimental results from us and other authors confirm the correctness of the derived laws for magnetostimulation. In light of these findings, proposed safety limits should be reconsidered. PMID:7596265

  13. fMRI adaptation revisited.

    PubMed

    Larsson, Jonas; Solomon, Samuel G; Kohn, Adam

    2016-07-01

    Adaptation has been widely used in functional magnetic imaging (fMRI) studies to infer neuronal response properties in human cortex. fMRI adaptation has been criticized because of the complex relationship between fMRI adaptation effects and the multiple neuronal effects that could underlie them. Many of the longstanding concerns about fMRI adaptation have received empirical support from neurophysiological studies over the last decade. We review these studies here, and also consider neuroimaging studies that have investigated how fMRI adaptation effects are influenced by high-level perceptual processes. The results of these studies further emphasize the need to interpret fMRI adaptation results with caution, but they also provide helpful guidance for more accurate interpretation and better experimental design. In addition, we argue that rather than being used as a proxy for measurements of neuronal stimulus selectivity, fMRI adaptation may be most useful for studying population-level adaptation effects across cortical processing hierarchies.

  14. MRI segmentation of the human brain: challenges, methods, and applications.

    PubMed

    Despotović, Ivana; Goossens, Bart; Philips, Wilfried

    2015-01-01

    Image segmentation is one of the most important tasks in medical image analysis and is often the first and the most critical step in many clinical applications. In brain MRI analysis, image segmentation is commonly used for measuring and visualizing the brain's anatomical structures, for analyzing brain changes, for delineating pathological regions, and for surgical planning and image-guided interventions. In the last few decades, various segmentation techniques of different accuracy and degree of complexity have been developed and reported in the literature. In this paper we review the most popular methods commonly used for brain MRI segmentation. We highlight differences between them and discuss their capabilities, advantages, and limitations. To address the complexity and challenges of the brain MRI segmentation problem, we first introduce the basic concepts of image segmentation. Then, we explain different MRI preprocessing steps including image registration, bias field correction, and removal of nonbrain tissue. Finally, after reviewing different brain MRI segmentation methods, we discuss the validation problem in brain MRI segmentation.

  15. The effects of perturbed cerebral blood flow and cerebrovascular reactivity on structural MRI and behavioral readouts in mild traumatic brain injury

    PubMed Central

    Long, Justin A; Watts, Lora T; Li, Wei; Shen, Qiang; Muir, Eric R; Huang, Shiliang; Boggs, Robert C; Suri, Abhinav; Duong, Timothy Q

    2015-01-01

    This study investigated the effects of perturbed cerebral blood flow (CBF) and cerebrovascular reactivity (CR) on relaxation time constant (T2), apparent diffusion coefficient (ADC), fractional anisotropy (FA), and behavioral scores at 1 and 3 hours, 2, 7, and 14 days after traumatic brain injury (TBI) in rats. Open-skull TBI was induced over the left primary forelimb somatosensory cortex (N=8 and 3 sham). We found the abnormal areas of CBF and CR on days 0 and 2 were larger than those of the T2, ADC, and FA abnormalities. In the impact core, CBF was reduced on day 0, increased to 2.5 times of normal on day 2, and returned toward normal by day 14, whereas in the tissue surrounding the impact, hypoperfusion was observed on days 0 and 2. CR in the impact core was negative, most severe on day 2 but gradually returned toward normal. T2, ADC, and FA abnormalities in the impact core were detected on day 0, peaked on day 2, and pseudonormalized by day 14. Lesion volumes peaked on day 2 and were temporally correlated with forelimb asymmetry and foot-fault scores. This study quantified the effects of perturbed CBF and CR on structural magnetic resonance imaging and behavioral readouts. PMID:26104285

  16. Improving tumour heterogeneity MRI assessment with histograms

    PubMed Central

    Just, N

    2014-01-01

    By definition, tumours are heterogeneous. They are defined by marked differences in cells, microenvironmental factors (oxygenation levels, pH, VEGF, VPF and TGF-α) metabolism, vasculature, structure and function that in turn translate into heterogeneous drug delivery and therapeutic outcome. Ways to estimate quantitatively tumour heterogeneity can improve drug discovery, treatment planning and therapeutic responses. It is therefore of paramount importance to have reliable and reproducible biomarkers of cancerous lesions' heterogeneity. During the past decade, the number of studies using histogram approaches increased drastically with various magnetic resonance imaging (MRI) techniques (DCE-MRI, DWI, SWI etc.) although information on tumour heterogeneity remains poorly exploited. This fact can be attributed to a poor knowledge of the available metrics and of their specific meaning as well as to the lack of literature references to standardised histogram methods with which surrogate markers of heterogeneity can be compared. This review highlights the current knowledge and critical advances needed to investigate and quantify tumour heterogeneity. The key role of imaging techniques and in particular the key role of MRI for an accurate investigation of tumour heterogeneity is reviewed with a particular emphasis on histogram approaches and derived methods. PMID:25268373

  17. Gradient-Modulated PETRA MRI

    PubMed Central

    Kobayashi, Naoharu; Goerke, Ute; Wang, Luning; Ellermann, Jutta; Metzger, Gregory J.; Garwood, Michael

    2015-01-01

    Image blurring due to off-resonance and fast T2* signal decay is a common issue in radial ultrashort echo time MRI sequences. One solution is to use a higher readout bandwidth, but this may be impractical for some techniques like pointwise encoding time reduction with radial acquisition (PETRA), which is a hybrid method of zero echo time and single point imaging techniques. Specifically, PETRA has severe specific absorption rate (SAR) and radiofrequency (RF) pulse peak power limitations when using higher bandwidths in human measurements. In this study, we introduce gradient modulation (GM) to PETRA to reduce image blurring artifacts while keeping SAR and RF peak power low. Tolerance of GM-PETRA to image blurring was evaluated in simulations and experiments by comparing with the conventional PETRA technique. We performed inner ear imaging of a healthy subject at 7T. GM-PETRA showed significantly less image blurring due to off-resonance and fast T2* signal decay compared to PETRA. In in vivo imaging, GM-PETRA nicely captured complex structures of the inner ear such as the cochlea and semicircular canals. Gradient modulation can improve the PETRA image quality and mitigate SAR and RF peak power limitations without special hardware modification in clinical scanners. PMID:26771005

  18. [Study on cine view of relative enhancement ratio map in O2-enhanced MRI].

    PubMed

    Fujii, Keita; Watanabe, Yasushi; Hanaoka, Shouhei; Motoyoshi, Kouichi; Goto, Masami; Amemiya, Shiori; Ino, Kenji; Akahane, Masaaki; Yano, Keiichi; Ohtomo, Kuni

    2014-11-01

    Magnetic resonance imaging (MRI) enables the evaluation of organ structure and function. Oxygen-enhanced MRI (O2-enhanced MRI) is a method for evaluating the pulmonary ventilation function using oxygen as a contrast agent. We created the Cine View of Relative Enhancement Ratio Map (Cine RER map) in O2-enhanced MRI to easily observe the contrast effect for clinical use. Relative enhancement ratio (RER) was determined as the pixel values of the Cine RER map. Moreover, six healthy volunteers underwent O2-enhanced MRI to determine the appropriate scale width of the Cine RER map. We calculated each RER and set 0 to 1.27 as the scale width of the Cine RER map based on the results. The Cine RER map made it possible to observe the contrast effect over time and thus is a convenient tool for evaluating the pulmonary ventilation function in O2-enhanced MRI.

  19. Quantitative Histological Validation of Diffusion MRI Fiber Orientation Distributions in the Rat Brain

    PubMed Central

    de Crespigny, Alex; Bolstad, Ingeborg; D'Arceuil, Helen; Bjaalie, Jan G.; Dale, Anders M.

    2010-01-01

    Diffusion MRI (dMRI) is widely used to measure microstructural features of brain white matter, but commonly used dMRI measures have limited capacity to resolve the orientation structure of complex fiber architectures. While several promising new approaches have been proposed, direct quantitative validation of these methods against relevant histological architectures remains missing. In this study, we quantitatively compare neuronal fiber orientation distributions (FODs) derived from ex vivo dMRI data against histological measurements of rat brain myeloarchitecture using manual recordings of individual myelin stained fiber orientations. We show that accurate FOD estimates can be obtained from dMRI data, even in regions with complex architectures of crossing fibers with an intrinsic orientation error of approximately 5–6 degrees in these regions. The reported findings have implications for both clinical and research studies based on dMRI FOD measures, and provide an important biological benchmark for improved FOD reconstruction and fiber tracking methods. PMID:20062822

  20. [Wilm's tumor. Diagnostic capacities of magnetic resonance imaging. MRI-pathomorphological comparison].

    PubMed

    Dombrovskii, V

    2001-01-01

    The accuracy of magnetic resonance imaging (MRI) in the diagnosis of Wilms' tumor (WT) and in the evaluation of preoperative chemotherapy (PCH) efficiency was investigated and compared with histopathological data of 56 children and infants with proven retroperitoneum neoplasma (WT--49, neuroblastoma--6, congenital mesoblastic nephroma--1). The author described the WT MRI-semiotics in general and in particular for its changes during the preoperative chemotherapy. The formula for calculation of tumor reduction index is suggested. The MRI sensitivity (100%), specificity (77.8%) and accuracy (91.1%) are detected. The high positive correlation level between the MRI and pathologic findings, concerning WT dimensions, pseudocapsule presence and safety, tumor structure secondary alterations and tumor spreading was found. At the same time, the specific MRI criteria for the different histological types of WT were not found. MRI is confirmed to be an accurate tool for diagnostic monitoring of patients with WT and other retroperitoneum neoplasms.

  1. Three-dimensional MRI-linac intra-fraction guidance using multiple orthogonal cine-MRI planes

    NASA Astrophysics Data System (ADS)

    Bjerre, Troels; Crijns, Sjoerd; Rosenschöld, Per Munck af; Aznar, Marianne; Specht, Lena; Larsen, Rasmus; Keall, Paul

    2013-07-01

    The introduction of integrated MRI-radiation therapy systems will offer live intra-fraction imaging. We propose a feasible low-latency multi-plane MRI-linac guidance strategy. In this work we demonstrate how interleaved acquired, orthogonal cine-MRI planes can be used for low-latency tracking of the 3D trajectory of a soft-tissue target structure. The proposed strategy relies on acquiring a pre-treatment 3D breath-hold scan, extracting a 3D target template and performing template matching between this 3D template and pairs of orthogonal 2D cine-MRI planes intersecting the target motion path. For a 60 s free-breathing series of orthogonal cine-MRI planes, we demonstrate that the method was capable of accurately tracking the respiration related 3D motion of the left kidney. Quantitative evaluation of the method using a dataset designed for this purpose revealed a translational error of 1.15 mm for a translation of 39.9 mm. We have demonstrated how interleaved acquired, orthogonal cine-MRI planes can be used for online tracking of soft-tissue target volumes.

  2. Three-dimensional MRI-linac intra-fraction guidance using multiple orthogonal cine-MRI planes.

    PubMed

    Bjerre, Troels; Crijns, Sjoerd; af Rosenschöld, Per Munck; Aznar, Marianne; Specht, Lena; Larsen, Rasmus; Keall, Paul

    2013-07-21

    The introduction of integrated MRI-radiation therapy systems will offer live intra-fraction imaging. We propose a feasible low-latency multi-plane MRI-linac guidance strategy. In this work we demonstrate how interleaved acquired, orthogonal cine-MRI planes can be used for low-latency tracking of the 3D trajectory of a soft-tissue target structure. The proposed strategy relies on acquiring a pre-treatment 3D breath-hold scan, extracting a 3D target template and performing template matching between this 3D template and pairs of orthogonal 2D cine-MRI planes intersecting the target motion path. For a 60 s free-breathing series of orthogonal cine-MRI planes, we demonstrate that the method was capable of accurately tracking the respiration related 3D motion of the left kidney. Quantitative evaluation of the method using a dataset designed for this purpose revealed a translational error of 1.15 mm for a translation of 39.9 mm. We have demonstrated how interleaved acquired, orthogonal cine-MRI planes can be used for online tracking of soft-tissue target volumes. PMID:23807514

  3. SU-E-J-193: Feasibility of MRI-Only Based IMRT Planning for Pancreatic Cancer

    SciTech Connect

    Prior, P; Botros, M; Chen, X; Paulson, E; Erickson, B; Li, X

    2014-06-01

    Purpose: With the increasing use of MRI simulation and the advent of MRI-guided delivery, it is desirable to use MRI only for treatment planning. In this study, we assess the dosimetric difference between MRI- and CTbased IMRT planning for pancreatic cancer. Methods: Planning CTs and MRIs acquired for a representative pancreatic cancer patient were used. MRI-based planning utilized forced relative electron density (rED) assignment of organ specific values from IRCU report 46, where rED = 1.029 for PTV and a rED = 1.036 for non-specified tissue (NST). Six IMRT plans were generated with clinical dose-volume (DV) constraints using a research Monaco planning system employing Monte Carlo dose calculation with optional perpendicular magnetic field (MF) of 1.5T. The following five plans were generated and compared with the planning CT: 1.) CT plan with MF and dose recalculation without optimization; 2.) MRI (T2) plan with target and OARs redrawn based on MRI, forced rED, no MF, and recalculation without optimization; 3.) Similar as in 2 but with MF; 4.) MRI plan with MF but without optimization; and 5.) Similar as in 4 but with optimization. Results: Generally, noticeable differences in PTV point doses and DV parameters (DVPs) between the CT-and MRI-based plans with and without the MF were observed. These differences between the optimized plans were generally small, mostly within 2%. Larger differences were observed in point doses and mean doses for certain OARs between the CT and MRI plan, mostly due to differences between image acquisition times. Conclusion: MRI only based IMRT planning for pancreatic cancer is feasible. The differences observed between the optimized CT and MRI plans with or without the MF were practically negligible if excluding the differences between MRI and CT defined structures.

  4. Metalloprotein-based MRI probes

    PubMed Central

    Matsumoto, Yuri; Jasanoff, Alan

    2013-01-01

    Metalloproteins have long been recognized as key determinants of endogenous contrast in magnetic resonance imaging (MRI) of biological subjects. More recently, both natural and engineered metalloproteins have been harnessed as biotechnological tools to probe gene expression, enzyme activity, and analyte concentrations by MRI. Metalloprotein MRI probes are paramagnetic and function by analogous mechanisms to conventional gadolinium or iron oxide-based MRI contrast agents. Compared with synthetic agents, metalloproteins typically offer worse sensitivity, but the possibilities of using protein engineering and targeted gene expression approaches in conjunction with metalloprotein contrast agents are powerful and sometimes definitive strengths. This review summarizes theoretical and practical aspects of metalloprotein-based contrast agents, and discusses progress in the exploitation of these proteins for molecular imaging applications. PMID:23376346

  5. Metalloprotein-based MRI probes.

    PubMed

    Matsumoto, Yuri; Jasanoff, Alan

    2013-04-17

    Metalloproteins have long been recognized as key determinants of endogenous contrast in magnetic resonance imaging (MRI) of biological subjects. More recently, both natural and engineered metalloproteins have been harnessed as biotechnological tools to probe gene expression, enzyme activity, and analyte concentrations by MRI. Metalloprotein MRI probes are paramagnetic and function by analogous mechanisms to conventional gadolinium or iron oxide-based MRI contrast agents. Compared with synthetic agents, metalloproteins typically offer worse sensitivity, but the possibilities of using protein engineering and targeted gene expression approaches in conjunction with metalloprotein contrast agents are powerful and sometimes definitive strengths. This review summarizes theoretical and practical aspects of metalloprotein-based contrast agents, and discusses progress in the exploitation of these proteins for molecular imaging applications.

  6. Development and Assessment of a New 3D Neuroanatomy Teaching Tool for MRI Training

    ERIC Educational Resources Information Center

    Drapkin, Zachary A.; Lindgren, Kristen A.; Lopez, Michael J.; Stabio, Maureen E.

    2015-01-01

    A computerized three-dimensional (3D) neuroanatomy teaching tool was developed for training medical students to identify subcortical structures on a magnetic resonance imaging (MRI) series of the human brain. This program allows the user to transition rapidly between two-dimensional (2D) MRI slices, 3D object composites, and a combined model in…

  7. SU-E-J-192: Verification of 4D-MRI Internal Target Volume Using Cine MRI

    SciTech Connect

    Lafata, K; Czito, B; Palta, M; Bashir, M; Yin, F; Cai, J

    2014-06-01

    Purpose: To investigate the accuracy of 4D-MRI in determining the Internal Target Volume (ITV) used in radiation oncology treatment planning of liver cancers. Cine MRI is used as the standard baseline in establishing the feasibility and accuracy of 4D-MRI tumor motion within the liver. Methods: IRB approval was obtained for this retrospective study. Analysis was performed on MR images from four patients receiving external beam radiation therapy for liver cancer at our institution. Eligible patients received both Cine and 4D-MRI scans before treatment. Cine images were acquired sagittally in real time at a slice bisecting the tumor, while 4D images were acquired volumetrically. Cine MR DICOM headers were manipulated such that each respiratory frame was assigned a unique slice location. This approach permitted the treatment planning system (Eclipse, Varian Medical Systems) to recognize a complete respiratory cycle as a “volume”, where the gross tumor was contoured temporally. Software was developed to calculate the union of all frame contours in the structure set, resulting in the corresponding plane of the ITV projecting through the middle of the tumor, defined as the Internal Target Area (ITA). This was repeated for 4D-MRI, at the corresponding slice location, allowing a direct comparison of ITAs obtained from each modality. Results: Four patients have been analyzed. ITAs contoured from 4D-MRI correlate with contours from Cine MRI. The mean error of 4D values relative to Cine values is 7.67 +/− 2.55 %. No single ITA contoured from 4D-MRI demonstrated more than 10.5 % error compared to its Cine MRI counterpart. Conclusion: Motion management is a significant aspect of treatment planning within dynamic environments such as the liver, where diaphragmatic and cardiac activity influence plan accuracy. This small pilot study suggests that 4D-MRI based ITA measurements agree with Cine MRI based measurements, an important step towards clinical implementation. NIH 1R21

  8. Hybrid-SPRITE MRI.

    PubMed

    Xiao, Dan; Balcom, Bruce J

    2013-10-01

    In a FID based frequency encoding MRI experiment the central part of k-space is not generally accessible due to the probe dead time. This portion of k-space is however crucial for image reconstruction. SPRITE (Single Point Ramped Imaging with T1 Enhancement), SPI with a linearly ramped phase encode gradient, has been employed to image short relaxation time systems for many years with great success. It is a robust imaging method in significant measure because it provides acquisition of high quality k-space origin data. We propose a new sampling scheme, termed hybrid-SPRITE, combining phase and frequency encoding to ensure high quality images with reduced acquisition times, reduced gradient duty cycle and increased sensitivity. In hybrid-SPRITE, numerous time domain points are collected to assist image reconstruction. An Inverse Non-uniform Discrete Fourier Transform (INDFT) is employed in 1D applications. A pseudo-polar grid is exploited in 2D hybrid-SPRITE for rapid and accurate image reconstruction. PMID:23916990

  9. An in vivo MRI Template Set for Morphometry, Tissue Segmentation, and fMRI Localization in Rats

    PubMed Central

    Valdés-Hernández, Pedro Antonio; Sumiyoshi, Akira; Nonaka, Hiroi; Haga, Risa; Aubert-Vásquez, Eduardo; Ogawa, Takeshi; Iturria-Medina, Yasser; Riera, Jorge J.; Kawashima, Ryuta

    2011-01-01

    Over the last decade, several papers have focused on the construction of highly detailed mouse high field magnetic resonance image (MRI) templates via non-linear registration to unbiased reference spaces, allowing for a variety of neuroimaging applications such as robust morphometric analyses. However, work in rats has only provided medium field MRI averages based on linear registration to biased spaces with the sole purpose of approximate functional MRI (fMRI) localization. This precludes any morphometric analysis in spite of the need of exploring in detail the neuroanatomical substrates of diseases in a recent advent of rat models. In this paper we present a new in vivo rat T2 MRI template set, comprising average images of both intensity and shape, obtained via non-linear registration. Also, unlike previous rat template sets, we include white and gray matter probabilistic segmentations, expanding its use to those applications demanding prior-based tissue segmentation, e.g., statistical parametric mapping (SPM) voxel-based morphometry. We also provide a preliminary digitalization of latest Paxinos and Watson atlas for anatomical and functional interpretations within the cerebral cortex. We confirmed that, like with previous templates, forepaw and hindpaw fMRI activations can be correctly localized in the expected atlas structure. To exemplify the use of our new MRI template set, were reported the volumes of brain tissues and cortical structures and probed their relationships with ontogenetic development. Other in vivo applications in the near future can be tensor-, deformation-, or voxel-based morphometry, morphological connectivity, and diffusion tensor-based anatomical connectivity. Our template set, freely available through the SPM extension website, could be an important tool for future longitudinal and/or functional extensive preclinical studies. PMID:22275894

  10. Experience with 7.0 T MRI in Patients with Supratentorial Meningiomas

    PubMed Central

    Song, Sang Woo; Son, Young Don; Cho, Zang-Hee

    2016-01-01

    Meningiomas are typically diagnosed by their characteristic appearance on conventional magnetic resonance imaging (MRI). However, detailed image findings regarding peri- and intra-tumoral anatomical structures, tumor consistency and vascularity are very important in pre-surgical planning and surgical outcomes. At the 7.0 T MRI achieving ultra-high resolution, it could be possible to obtain more useful information in surgical strategy. Four patients who were radiologically diagnosed with intracranial meningioma in 1.5 T MRI underwent a 7.0 T MRI. Three of them underwent surgery afterwards, and one received gamma knife radiosurgery. In our study, the advantages of 7.0 T MRI over 1.5 T MRI were a more detailed depiction of the peri- and intra-tumoral vasculature and a clear delineation of tumor-brain interface. In the safety issues, all patients received 7.0 T MRI without any adverse event. One disadvantage of 7.0 T MRI was the reduced image quality of skull base lesions. 7.0 T MRI in patients with meningiomas could provide useful information in surgical strategy, such as the peri-tumoral vasculature and the tumor-brain interface. PMID:27446524

  11. Pushing spatial and temporal resolution for functional and diffusion MRI in the Human Connectome Project

    PubMed Central

    Uğurbil, Kamil; Xu, Junqian; Auerbach, Edward J.; Moeller, Steen; Vu, An; Duarte-Carvajalino, Julio M.; Lenglet, Christophe; Wu, Xiaoping; Schmitter, Sebastian; Van de Moortele, Pierre Francois; Strupp, John; Sapiro, Guillermo; De Martino, Federico; Wang, Dingxin; Harel, Noam; Garwood, Michael; Chen, Liyong; Feinberg, David A.; Smith, Stephen M.; Miller, Karla L.; Sotiropoulos, Stamatios N; Jbabdi, Saad; Andersson, Jesper L; Behrens, Timothy EJ; Glasser, Matthew F.; Van Essen, David; Yacoub, Essa

    2013-01-01

    The human connectome project (HCP) relies primarily on three complementary magnetic resonance (MR) methods. These are: 1) resting state functional MR imaging (rfMRI) which uses correlations in the temporal fluctuations in an fMRI time series to deduce ‘functional connectivity’; 2) diffusion imaging (dMRI), which provides the input for tractography algorithms used for the reconstruction of the complex axonal fiber architecture; and 3) task based fMRI (tfMRI), which is employed to identify functional parcellation in the human brain in order to assist analyses of data obtained with the first two methods. We describe technical improvements and optimization of these methods as well as instrumental choices that impact speed of acquisition of fMRI and dMRI images at 3 Tesla, leading to whole brain coverage with 2 mm isotropic resolution in 0.7 second for fMRI, and 1.25 mm isotropic resolution dMRI data for tractography analysis with three-fold reduction in total data acquisition time. Ongoing technical developments and optimization for acquisition of similar data at 7 Tesla magnetic field are also presented, targeting higher resolution, specificity of functional imaging signals, mitigation of the inhomogeneous radio frequency (RF) fields and power deposition. Results demonstrate that overall, these approaches represent a significant advance in MR imaging of the human brain to investigate brain function and structure. PMID:23702417

  12. MRI with and without a high-density EEG cap--what makes the difference?

    PubMed

    Klein, Carina; Hänggi, Jürgen; Luechinger, Roger; Jäncke, Lutz

    2015-02-01

    Besides the benefit of combining electroencephalography (EEG) and magnetic resonance imaging (MRI), much effort has been spent to develop algorithms aimed at successfully cleaning the EEG data from MRI-related gradient and ballistocardiological artifacts. However, there are also studies showing a negative influence of the EEG on MRI data quality. Therefore, in the present study, we focused for the first time on the influence of the EEG on morphometric measurements of T1-weighted MRI data (voxel- and surfaced-based morphometry). Here, we demonstrate a strong influence of the EEG on cortical thickness, surface area, and volume as well as subcortical volumes due to local EEG-related inhomogeneities of the static magnetic (B0) and the gradient field (B1). In a second step, we analyzed the signal-to-noise ratios for both the anatomical and the functional data when recorded simultaneously with EEG and MRI and compared them to the ratios of the MRI data without simultaneous EEG measurements. These analyses revealed consistently lower signal-to-noise ratios for anatomical as well as functional MRI data during simultaneous EEG registration. In contrast, further analyses of T2*-weighted images provided reliable results independent of whether including the individuals' T1-weighted image with or without the EEG cap in the fMRI preprocessing stream. Based on our findings, we strongly recommend against using the structural images obtained during simultaneous EEG-MRI recordings for further anatomical data analysis. PMID:25482268

  13. MRI with and without a high-density EEG cap--what makes the difference?

    PubMed

    Klein, Carina; Hänggi, Jürgen; Luechinger, Roger; Jäncke, Lutz

    2015-02-01

    Besides the benefit of combining electroencephalography (EEG) and magnetic resonance imaging (MRI), much effort has been spent to develop algorithms aimed at successfully cleaning the EEG data from MRI-related gradient and ballistocardiological artifacts. However, there are also studies showing a negative influence of the EEG on MRI data quality. Therefore, in the present study, we focused for the first time on the influence of the EEG on morphometric measurements of T1-weighted MRI data (voxel- and surfaced-based morphometry). Here, we demonstrate a strong influence of the EEG on cortical thickness, surface area, and volume as well as subcortical volumes due to local EEG-related inhomogeneities of the static magnetic (B0) and the gradient field (B1). In a second step, we analyzed the signal-to-noise ratios for both the anatomical and the functional data when recorded simultaneously with EEG and MRI and compared them to the ratios of the MRI data without simultaneous EEG measurements. These analyses revealed consistently lower signal-to-noise ratios for anatomical as well as functional MRI data during simultaneous EEG registration. In contrast, further analyses of T2*-weighted images provided reliable results independent of whether including the individuals' T1-weighted image with or without the EEG cap in the fMRI preprocessing stream. Based on our findings, we strongly recommend against using the structural images obtained during simultaneous EEG-MRI recordings for further anatomical data analysis.

  14. Estimating Motion From MRI Data

    PubMed Central

    OZTURK, CENGIZHAN; DERBYSHIRE, J. ANDREW; MCVEIGH, ELLIOT R.

    2007-01-01

    Invited Paper Magnetic resonance imaging (MRI) is an ideal imaging modality to measure blood flow and tissue motion. It provides excellent contrast between soft tissues, and images can be acquired at positions and orientations freely defined by the user. From a temporal sequence of MR images, boundaries and edges of tissues can be tracked by image processing techniques. Additionally, MRI permits the source of the image signal to be manipulated. For example, temporary magnetic tags displaying a pattern of variable brightness may be placed in the object using MR saturation techniques, giving the user a known pattern to detect for motion tracking. The MRI signal is a modulated complex quantity, being derived from a rotating magnetic field in the form of an induced current. Well-defined patterns can also be introduced into the phase of the magnetization, and could be thought of as generalized tags. If the phase of each pixel is preserved during image reconstruction, relative phase shifts can be used to directly encode displacement, velocity and acceleration. New methods for modeling motion fields from MRI have now found application in cardiovascular and other soft tissue imaging. In this review, we shall describe the methods used for encoding, imaging, and modeling motion fields with MRI. PMID:18958181

  15. A Case of Ovarian Pregnancy Diagnosed by MRI.

    PubMed

    Io, Shingo; Hasegawa, Masaaki; Koyama, Takashi

    2015-01-01

    Ovarian pregnancy is a rare form of ectopic pregnancy, causing a great diagnostic challenge. We report a case of ovarian pregnancy in a 42-year-old woman, in whom MRI successfully demonstrated the implantation in the ovary. Transvaginal ultrasonography showed an echogenic mass in the right ovary but failed to demonstrate tubal pregnancy. T2-weighted MR images disclosed a gestational sac structure in the right ovary, which exhibited heterogeneous high intensity intermingled with punctate foci of distinct low intensity. MRI may be a useful tool for diagnosing ovarian pregnancy, by demonstrating a gestational sac in the ovary.

  16. The feasibility of atlas-based automatic segmentation of MRI for H&N radiotherapy planning.

    PubMed

    Wardman, Kieran; Prestwich, Robin J D; Gooding, Mark J; Speight, Richard J

    2016-01-01

    Atlas-based autosegmentation is an established tool for segmenting structures for CT-planned head and neck radiotherapy. MRI is being increasingly integrated into the planning process. The aim of this study is to assess the feasibility of MRI-based, atlas-based autosegmentation for organs at risk (OAR) and lymph node levels, and to compare the segmentation accuracy with CT-based autosegmentation. Fourteen patients with locally advanced head and neck cancer in a prospective imaging study underwent a T1-weighted MRI and a PET-CT (with dedicated contrast-enhanced CT) in an immobilization mask. Organs at risk (orbits, parotids, brainstem, and spinal cord) and the left level II lymph node region were manually delineated on the CT and MRI separately. A 'leave one out' approach was used to automatically segment structures onto the remaining images separately for CT and MRI. Contour comparison was performed using multiple positional metrics: Dice index, mean distance to conformity (MDC), sensitivity index (Se Idx), and inclusion index (Incl Idx). Automatic segmentation using MRI of orbits, parotids, brainstem, and lymph node level was acceptable with a DICE coefficient of 0.73-0.91, MDC 2.0-5.1mm, Se Idx 0.64-0.93, Incl Idx 0.76-0.93. Segmentation of the spinal cord was poor (Dice coefficient 0.37). The process of automatic segmentation was significantly better on MRI compared to CT for orbits, parotid glands, brainstem, and left lymph node level II by multiple positional metrics; spinal cord segmentation based on MRI was inferior compared with CT. Accurate atlas-based automatic segmentation of OAR and lymph node levels is feasible using T1-MRI; segmentation of the spinal cord was found to be poor. Comparison with CT-based automatic segmentation suggests that the process is equally as, or more accurate, using MRI. These results support further translation of MRI-based segmentation methodology into clinicalpractice. PMID:27455480

  17. Challenges in Identifying the Foot Motor Region in Patients with Brain Tumor on Routine MRI: Advantages of fMRI

    PubMed Central

    Fisicaro, R.A.; Jiao, R.X.; Stathopoulos, C.; Brennan, N.M. Petrovich; Peck, K.K.; Holodny, A.I.

    2016-01-01

    BACKGROUND AND PURPOSE Accurate localization of the foot/leg motor homunculus is essential because iatrogenic damage can render a patient wheelchair- or bed-bound. We hypothesized the following: 1) Readers would identify the foot motor homunculus <100% of the time on routine MR imaging, 2) neuroradiologists would perform better than nonradiologists, and 3) those with fMRI experience would perform better than those without it. MATERIALSANDMETHODS Thirty-five attending-level raters (24 neuroradiologists, 11 nonradiologists) evaluated 14 brain tumors involving the frontoparietal convexity. Raters were asked to identify the location of the foot motor homunculus and determine whether the tumor involved the foot motor area and/or motor cortex by using anatomic MR imaging. Results were compared on the basis of prior fMRI experience and medical specialty by using Mann-Whitney U test statistics. RESULTS No rater was 100% correct. Raters correctly identified whether the tumor was in the foot motor cortex 77% of the time. Raters with fMRI experience were significantly better than raters without experience at foot motor fMRI centroid predictions (13 ± 6 mm versus 20 ± 13 mm from the foot motor cortex center, P = 2 × 10−6) and arrow placement in the motor gyrus (67% versus 47%, P = 7 × 10−5). Neuroradiologists were significantly better than nonradiologists at foot motor fMRI centroid predictions (15 ± 8 mm versus 20 ± 14 mm, P = .005) and arrow placement in the motor gyrus (61% versus 46%, P = .008). CONCLUSIONS The inability of experienced readers to consistently identify the location of the foot motor homunculus on routine MR imaging argues for using fMRI in the preoperative setting. Experience with fMRI leads to improved accuracy in identifying anatomic structures, even on routine MR imaging. PMID:25882288

  18. Real time dynamic MRI by exploiting spatial and temporal sparsity.

    PubMed

    Chen, Chen; Li, Yeqing; Axel, Leon; Huang, Junzhou

    2016-05-01

    Online imaging requires that the reconstruction of current frame only depends on the previous frames, and real time imaging is the desired case. In this work, we propose a novel scheme for real time dynamic magnetic resonance imaging (dMRI) reconstruction. Different from previous methods, the reconstructions of the second frame to the last frame are independent in our scheme, which only require the first frame as the reference image. Therefore, this scheme can be naturally implemented in parallel. After the first frame is reconstructed, all the later frames can be processed as soon as the k-space data are acquired. As an extension of the conventional spatial total variation, a new online model called dynamic total variation is used to exploit the sparsity on both spatial and temporal domains in dMRI. In real time dMRI, each frame is required to be reconstructed very fast. We then design a novel reweighted least squares algorithm to solve the challenging problem. Motivated by the special structure of partial Fourier transform in sparse MRI, this algorithm is accelerated by the preconditioned conjugate gradient descent method. The proposed method is compared with 4 state-of-the-art online and offline methods on two in-vivo cardiac dMRI datasets. The experimental results show that our method significantly outperforms previous online methods, and is comparable to the offline methods in terms of reconstruction accuracy. PMID:26578303

  19. Human brain functional MRI and DTI visualization with virtual reality.

    PubMed

    Chen, Bin; Moreland, John; Zhang, Jingyu

    2011-12-01

    Magnetic resonance diffusion tensor imaging (DTI) and functional MRI (fMRI) are two active research areas in neuroimaging. DTI is sensitive to the anisotropic diffusion of water exerted by its macromolecular environment and has been shown useful in characterizing structures of ordered tissues such as the brain white matter, myocardium, and cartilage. The diffusion tensor provides two new types of information of water diffusion: the magnitude and the spatial orientation of water diffusivity inside the tissue. This information has been used for white matter fiber tracking to review physical neuronal pathways inside the brain. Functional MRI measures brain activations using the hemodynamic response. The statistically derived activation map corresponds to human brain functional activities caused by neuronal activities. The combination of these two methods provides a new way to understand human brain from the anatomical neuronal fiber connectivity to functional activities between different brain regions. In this study, virtual reality (VR) based MR DTI and fMRI visualization with high resolution anatomical image segmentation and registration, ROI definition and neuronal white matter fiber tractography visualization and fMRI activation map integration is proposed. Rationale and methods for producing and distributing stereoscopic videos are also discussed. PMID:23256049

  20. Simultaneous EEG-Correlated Ictal fMRI.

    PubMed

    Salek-Haddadi, Afraim; Merschhemke, Martin; Lemieux, Louis; Fish, David R

    2002-05-01

    The ability to continuously acquire simultaneous EEG and fMRI data during seizures presents a formidable challenge both clinically and technically. Published ictal fMRI reports have so far been unable to benefit from simultaneous electrographic recordings and remain largely assumptive. Unique findings from a Continuous EEG-correlated fMRI experiment are presented in which a focal subclinical seizure was captured in its entirety. For the first time dynamic and biphasic Blood Oxygen Level Dependent (BOLD) signal changes are shown using statistical parametric mapping time-locked to the ictal EEG activity localizing seizure generation and propagation sites, with millimeter resolution, to electroclinically concordant gray matter structures. Though presently of limited clinical applicability, a new avenue is opened for further research.

  1. Imaging of the aortic valve with MRI and CT angiography.

    PubMed

    Harvey, J J; Hoey, E T D; Ganeshan, A

    2013-12-01

    The aortic valve may be affected by a wide range of congenital and acquired diseases. Echocardiography is the main non-invasive imaging technique for assessing patho-anatomical alterations of the aortic valve and adjacent structures and in many cases is sufficient to establish a diagnosis and/or guide treatment decisions. Recent technological advances in magnetic resonance imaging (MRI) and multidetector computed tomography (MDCT) have enabled these techniques to play a complimentary role in certain clinical scenarios and as such can be useful problem-solving tools. Radiologists should be familiar with the indications, advantages, and limitations of MRI and MDCT in order to advise and direct an appropriate imaging strategy depending upon the clinical scenario. This article reviews the role of MRI and MDCT angiography for assessment of the aortic valve including relevant anatomy, scan acquisition protocols, and post-processing methods. An approach to interpretation and the key imaging features of commonly encountered aortic valvular diseases are discussed.

  2. K-Bayes reconstruction for perfusion MRI. I: concepts and application.

    PubMed

    Kornak, John; Young, Karl; Schuff, Norbert; Du, Antao; Maudsley, Andrew A; Weiner, Michael W

    2010-06-01

    Despite the continued spread of magnetic resonance imaging (MRI) methods in scientific studies and clinical diagnosis, MRI applications are mostly restricted to high-resolution modalities, such as structural MRI. While perfusion MRI gives complementary information on blood flow in the brain, its reduced resolution limits its power for detecting specific disease effects on perfusion patterns. This reduced resolution is compounded by artifacts such as partial volume effects, Gibbs ringing, and aliasing, which are caused by necessarily limited k-space sampling and the subsequent use of discrete Fourier transform (DFT) reconstruction. In this study, a Bayesian modeling procedure (K-Bayes) is developed for the reconstruction of perfusion MRI. The K-Bayes approach (described in detail in Part II: Modeling and Technical Development) combines a process model for the MRI signal in k-space with a Markov random field prior distribution that incorporates high-resolution segmented structural MRI information. A simulation study was performed to determine qualitative and quantitative improvements in K-Bayes reconstructed images compared with those obtained via DFT. The improvements were validated using in vivo perfusion MRI data of the human brain. The K-Bayes reconstructed images were demonstrated to provide reduced bias, increased precision, greater effect sizes, and higher resolution than those obtained using DFT.

  3. MRI artefacts after Bonebridge implantation.

    PubMed

    Steinmetz, C; Mader, I; Arndt, S; Aschendorff, A; Laszig, R; Hassepass, F

    2014-07-01

    The new transcutaneous bone conduction implant (BCI) Bonebridge (BB, MED-EL) allows the skin to remain intact and therefore overcomes some issues related to percutaneous systems, such as skin reaction around the external screw and cosmetic complaints. According to manufacturer, BB is MRI conditional up to 1,5 Tesla (T). The artefact of the neurocranium after BB implantation is extensive as shown in the present report. This has to be taken into account when patients suffering conductive, mixed or single-sided hearing loss with candidacy for a BCI are counselled. In patients with comorbid intracranial tumour or other diseases of the brain that require imaging control scans with MRI percutaneous, BCI should be the implant of choice considering the very small artefact of the percutaneous screw in MRI.

  4. The Raven MRI teaching file

    SciTech Connect

    Lufkin, R.B.; Bradley, W.G. Jr.; Brant-Zawadzki, M.

    1990-01-01

    This book presents individually bound guides for each section of the body, the 1,000 concise and clearly illustrated case files cover neoplastic, non-neoplastic, degenerative, inflammatory, congenital, and acquired disease of the brain, head and neck, spine, musculoskeletal system, cardiovascular system, chest, abdomen, and male and female pelvis. It focuses on specific body regions; one is devoted to pediatric MRI; and one reviews the principles of MRI and identifies frequently encountered artifacts. It contains 100 completed case studies, with high-resolution MR images.

  5. Paramagnetic lanthanide chelates for multicontrast MRI.

    PubMed

    Cakić, Nevenka; Savić, Tanja; Stricker-Shaver, Janice; Truffault, Vincent; Platas-Iglesias, Carlos; Mirkes, Christian; Pohmann, Rolf; Scheffler, Klaus; Angelovski, Goran

    2016-07-28

    The preparation of a paramagnetic chelator that serves as a platform for multicontrast MRI, and can be utilized either as a T1-weighted, paraCEST or (19)F MRI contrast agent is reported. Its europium(iii) complex exhibits an extremely slow water exchange rate which is optimal for the use in CEST MRI. The potential of this platform was demonstrated through a series of MRI studies on tube phantoms and animals. PMID:27291157

  6. Cervical Spine MRI in Abused Infants.

    ERIC Educational Resources Information Center

    Feldman, Kenneth W.; And Others

    1997-01-01

    This study attempted to use cervical spine magnetic resonance imaging (MRI) to detect cord injury in 12 dead children with head injury from child abuse. Eighty percent of children autopsied had small cervical spine hemorrhages; MRI did not identify them and did not identify cord injury in any child studied, indicating that MRI scans are probably…

  7. [Magnetic resonance imaging in the diagnosis of benign renal parenchymal epithelial tumors: MRI -- pathomorphological comparison].

    PubMed

    Dombrovskiĭ, V I

    2001-01-01

    The study evaluates the MRI diagnostic value in the discovery and characterization of the benign epithelial renal parenchyma's neoplasms. Among more than 700 patients with renal tumors, which underwent MRI, 27 histopathologicaly verified cases of adenoma (10), malignant adenoma (11) and oncocytoma (6) were selected and the retrospective analysis of these 3 groups was performed. The 30 patients with small renal cell carcinoma were accepted as a control group. The benign tumor's MRI semiotics is described in general and in the particular for each nosological form. The author considers that MRI data reliably reflect the true morphological structure of the neoplasm's growth, concerning the secondary tumor's tissue alterations (r = 0.89), the presence (r = 0.92) and safety (r = 0.81) of pseudocapsula. At the same time, the specific MRI criteria for the different types of benign and small malignant tumors were not found.

  8. [Magnetic resonance imaging in the diagnosis of renal neoplasms : MRI - histopathological comparison].

    PubMed

    Dombrovskií, V I

    2000-01-01

    The study evaluates the diagnostic of the MRI in the discovery and characterizing renal neoplasms. The principle of the comparative study of MRI, other diagnostic modalities and histopathological data was applied by the author, using a large pool statistically significant clinical material (419 cases). Renal cell carcinoma--the most wide-spread renal parenchyma's tumor, was selected as a morphological model (302 cases). As a result of this investigation, the MRI semiotics of renal cell carcinoma was more precisely defined and detailed and this method's high level of sensitivity (98.4%) was detected, concerning the detection of such a type of pathology. The MRI data reliably reflect (r > 0.8; P < 0.05) the true morphological structure of the tumor's growth, the secondary tumor's tissue alterations and its interaction with surrounding anatomical formations. Thus, MRI is appreciated as a method of choice for oncological urology.

  9. MRI Biosensors: A Short Primer

    PubMed Central

    Louie, Angelique

    2013-01-01

    Interest in Magnetic Resonance Imaging (MRI) contrast agents for molecular imaging of biological function experienced a surge of excitement approximately 20 years ago with the development of the first activatable contrast agents that could act as biosensors and turn “on” in response to a specific biological activity. This brief tutorial, based on a short course lecture from the 2011 ISMRM meeting, provides an overview of underlying principles governing the design of biosensing contrast agents. We describe mechanisms by which a magnetic resonance imaging (MRI) contrast agent can be made into a sensor for both T1 and T2 types contrast agents. Examples of biological activities that can interact with a contrast agent are discussed using specific examples from the recent literature to illustrate the primary mechanisms of action that have been utilized to achieve activation. MRI sensors for pH, ion binding, enzyme cleavage, and oxidation-reduction are presented. This article is not meant to be an exhaustive review, but an illustrative primer to explain how activation can be achieved for an MRI contrast agent. Chemical exchange saturation transfer (CEST) is not covered as these agents were covered in a separate lecture. PMID:23996662

  10. MRI of Little Leaguer's shoulder.

    PubMed

    Hatem, Stephen F; Recht, Michael P; Profitt, Brad

    2006-02-01

    The MRI appearance of 'Little Leaguer's shoulder' has not been previously reported in the radiology literature. Purported etiologies include proximal humeral epiphyseolysis, osteochondrosis of the proximal humeral epiphysis, stress fracture of the proximal humeral epiphyseal plate, and rotational stress fracture of the proximal humeral epiphyseal plate. We describe magnetic resonance imaging findings in four patients and review the literature.

  11. MRI findings in cobalamin deficiency.

    PubMed

    Krishna, Kavita K; Arafat, Abou-Sharbin Maher; Ichaporia, Nasli Rustom; Jain, M M

    2003-01-01

    A 55 year old male presented 2 years after a jejuno-iliectomy with weakness of all limbs, paraesthesiae, and difficulty in walking. Clinical examination revealed loss of posterior column sensations. Investigations were suggestive of a deficiency of vitamin B12 and folate. MRI showed a band of hyperintensity on T2 image, in the dorsal portion of the spinal cord.

  12. Can Dynamic Contrast-Enhanced MRI (DCE-MRI) and Diffusion-Weighted MRI (DW-MRI) Evaluate Inflammation Disease

    PubMed Central

    Zhu, Jianguo; Zhang, Faming; Luan, Yun; Cao, Peng; Liu, Fei; He, Wenwen; Wang, Dehang

    2016-01-01

    Abstract The aim of the study was to investigate diagnosis efficacy of dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted MRI (DW-MRI) in Crohn's disease (CD). To find out the correlations between functional MRI parameters including Ktrans, Kep, Ve, Vp, and apparent diffusion coefficient (ADC) with a serologic biomarker. The relationships between pharmacokinetic parameters and ADC were also studied. Thirty-two patients with CD (22 men, 10 women; mean age: 30.5 years) and 18 healthy volunteers without any inflammatory disease (10 men, 8 women; mean age, 34.11 years) were enrolled into this approved prospective study. Pearson analysis was used to evaluate the correlation between Ktrans, Kep, Ve, Vp, and C-reactive protein (CRP), ADC, and CRP respectively. The diagnostic efficacy of the functional MRI parameters in terms of sensitivity and specificity were analyzed by receiver operating characteristic (ROC) curve analyses. Optimal cut-off values of each functional MRI parameters for differentiation of inflammatory from normal bowel were determined according to the Youden criterion. Mean value of Ktrans in the CD group was significantly higher than that of normal control group. Similar results were observed for Kep and Ve. On the contrary, the ADC value was lower in the CD group than that in the control group. Ktrans and Ve were shown to be correlated with CRP (r = 0.725, P < 0.001; r = 0.533, P = 0.002), meanwhile ADC showed negative correlation with CRP (r = −0.630, P < 0.001). There were negative correlations between the pharmacokinetic parameters and ADC, such as Ktrans to ADC (r = −0.856, P < 0.001), and Ve to ADC (r = −0.451, P = 0.01). The area under the curve (AUC) was 0.994 for Ktrans (P < 0.001), 0.905 for ADC (P < 0.001), 0.806 for Ve (P < 0.001), and 0.764 for Kep (P = 0.002). The cut-off point of the Ktrans was found to be 0.931 min–1. This value provided the best trade-off between

  13. Simulation of arthroscopic surgery using MRI data

    NASA Technical Reports Server (NTRS)

    Heller, Geoffrey; Genetti, Jon

    1994-01-01

    With the availability of Magnetic Resonance Imaging (MRI) technology in the medical field and the development of powerful graphics engines in the computer world the possibility now exists for the simulation of surgery using data obtained from an actual patient. This paper describes a surgical simulation system which will allow a physician or a medical student to practice surgery on a patient without ever entering an operating room. This could substantially lower the cost of medial training by providing an alternative to the use of cadavers. This project involves the use of volume data acquired by MRI which are converted to polygonal form using a corrected marching cubes algorithm. The data are then colored and a simulation of surface response based on springy structures is performed in real time. Control for the system is obtained through the use of an attached analog-to-digital unit. A remote electronic device is described which simulates an imaginary tool having features in common with both arthroscope and laparoscope.

  14. MRI guidance for focused ultrasound surgery

    NASA Astrophysics Data System (ADS)

    McDannold, Nathan; Hynynen, Kullervo

    2005-09-01

    Magnetic resonance imaging (MRI) based monitoring has been shown in recent years to enhance the effectiveness of minimally or noninvasive thermal therapy techniques, such as focused ultrasound surgery. MR imaging's unique soft tissue contrast and ability to image in three dimensions and in any orientation make it extremely useful for treatment planning and for imaging the tissue response to the therapy. The temperature sensitivity of several intrinsic parameters enables MRI to visualize and quantify the progress an ongoing thermal treatment. The most useful temperature-sensitive parameter appears to be the proton resonant frequency, which allows for precise and accurate temperature measurements in water-based tissues. By acquiring a time series of quantitative temperature images, it is possible to monitor the accumulated thermal dose delivered to the target tissue and accurately predict the areas that are thermally ablated, while at the same time ensuring nearby critical structures are not heated. The method is currently used in an FDA approved focused ultrasound device for the treatment of uterine fibroids. Our research and clinical experience with these techniques will be reviewed.

  15. Tri-Axial MRI Compatible Fiber-optic Force Sensor

    PubMed Central

    Tan, U-Xuan; Yang, Bo; Gullapalli, Rao; Desai, Jaydev P.

    2011-01-01

    Magnetic resonance imaging (MRI) has been gaining popularity over standard imaging modalities like ultrasound and CT because of its ability to provide excellent soft-tissue contrast. However, due to the working principle of MRI, a number of conventional force sensors are not compatible. One popular solution is to develop a fiber-optic force sensor. However, the measurements along the principal axes of a number of these force sensors are highly cross-coupled. One of the objectives of this paper is to minimize this coupling effect. In addition, this paper describes the design of elastic frame structures that are obtained systematically using topology optimization techniques for maximizing sensor resolution and sensor bandwidth. Through the topology optimization approach, we ensure that the frames are linked from the input to output. The elastic frame structures are then fabricated using polymers materials, such as ABS and Delrin®, as they are ideal materials for use in MRI environment. However, the hysteresis effect seen in the displacement-load graph of plastic materials is known to affect the accuracy. Hence, this paper also proposes modeling and addressing this hysteretic effect using Prandtl-Ishlinskii play operators. Finally, experiments are conducted to evaluate the sensor’s performance, as well as its compatibility in MRI under continuous imaging. PMID:21666783

  16. MRI Predictors of Treatment Response in Late-Life Depression

    PubMed Central

    Aizenstein, Howard J.; Khalef, Alexander; Walker, Sarah E.; Andreescu, Carmen

    2014-01-01

    In older adults, depression not only results in more years lived with disability than any other disease, but it also carries additional risk for suicide, medical comorbidities, and family care-giving burden. Because it can take many months to identify an effective treatment regimen, it is of upmost importance to shorten the window of time and identify early on what medication(s) and dosages will work effectively for individuals suffering from depression. Late-life depression (LLD) has been associated with greater burden of age-related changes, including atrophy, white matter ischemic changes, and alterations in functional connectivity (FC). Depression in midlife has been shown to alter affective reactivity and regulation, and functional magnetic resonance imaging (fMRI) studies in LLD have replicated the same abnormalities. Effective treatment can normalize these alterations. This article provides a review of the current literature using structural and functional neuroimaging to identify magnetic resonance imaging (MRI) predictors of treatment response in LLD. The majority of the literature on structural MRI has focused on the vascular depression hypothesis, and studies support the view that loss of brain volume and white matter integrity is associated with poorer treatment outcomes. Studies using fMRI have reported that lower task-based activity in the prefrontal cortex (PFC) and limbic regions is associated with poorer outcome. These imaging markers may be integrated into clinical decision-making to better treatment outcomes in the future. PMID:24381231

  17. Anatomical features of cephalothoracopagus variations: CT and MRI.

    PubMed

    Esposito, V; Gatta, G; Di Grezia, G; Iacomino, A; Fiumarella, A; Russo, A; Feragalli, B; Ferragalli, B; Grassi, R

    2013-01-01

    Conjoined twins have fascinated human mankind for a long time. Until recently, their description was limited to the dissection of non-viable cases, the description of external features and of bones by x-ray imaging. The introduction of ultrasonographic techniques gave the first in uterus images of conjoined twins, though the spatial resolution did not allow detailed descriptions. Subsequently, CT and MRI techniques allowed more precise definition of organs without any dissection, thus the need of formal interpretation of similar new images. As a matter of fact, few monstrosities have been studied by CT and MRI techniques. To this day very few cases still lack any CT/MRI documentation. Here we present a very rare type of cephalothoracopagus twins (joined at the head and the thorax). They have been accurately examined by CT and MRI imaging to study visceral structures. Pathophysiology and genetic aspects are also reviewed. These data offer precious details for accurate comprehension of imaging studies, and for theoretical studies concerning the information of several anatomical structures. PMID:23830409

  18. In-vivo human brain molecular imaging with a brain-dedicated PET/MRI system.

    PubMed

    Cho, Zang Hee; Son, Young Don; Choi, Eun Jung; Kim, Hang Keun; Kim, Jeong Hee; Lee, Sang Yoon; Ogawa, Seiji; Kim, Young Bo

    2013-02-01

    Advances in the new-generation of ultra-high-resolution, brain-dedicated positron emission tomography-magnetic resonance imaging (PET/MRI) systems have begun to provide many interesting insights into the molecular dynamics of the brain. First, the finely delineated structural information from ultra-high-field MRI can help us to identify accurate landmark structures, thereby making it easier to locate PET activation sites that are anatomically well-correlated with metabolic or ligand-specific organs in the neural structures in the brain. This synergistic potential of PET/MRI imaging is discussed in terms of neuroscience and neurological research from both translational and basic research perspectives. Experimental results from the hippocampus, thalamus, and brainstem obtained with (18)F-fluorodeoxyglucose and (11)C-3-amino-4-(2-dimethylaminomethylphenylsulfanyl)benzonitrile are used to demonstrate the potential of this new brain PET/MRI system.

  19. MRI-based morphometric characterizations of sexual dimorphism of the cerebrum of ferrets (Mustela putorius).

    PubMed

    Sawada, Kazuhiko; Horiuchi-Hirose, Miwa; Saito, Shigeyoshi; Aoki, Ichio

    2013-12-01

    The present study aimed to characterize cerebral morphology in young adult ferrets and its sexual dimorphism using high-field MRI and MRI-based morphometry. Ex vivo short TR/TE (typical T1-weighted parameter setting for conventional MRI) and T2W (long TR/TE) MRI with high spatial resolution at 7-tesla could visualize major subcortical and archicortical structures, i.e., the caudate nucleus, lentiform nucleus, amygdala and hippocampus. In particular, laminar organization of the olfactory bulb was identifiable by short TR/TE-MRI. The primary and secondary sulci observable in the adult ferret were distinguishable on either short TR/TE- or T2W-MRI, and the cortical surface morphology was reproduced well by 3D-rendered images obtained by short TR/TE-MRI. The cerebrum had a significantly lower volume in females than in males, which was attributed to region-specific volume reduction in the cerebral cortex and subcortical white matter in females. A sexual difference was also detected, manifested by an overall reduction in normalized signal ratios of short TR/TE-MRI in all cerebral structures examined in females than in males. On the other hand, an alternating array of higher and lower short TR/TE-MRI intensity transverse zones throughout the cortex, which was reminiscent of the functional cortical areas, was revealed by maximum intensity projection (MIP) in 3D. The normalized signal ratio of short TR/TE-MRI, but not T2W-MRI in the cortex, was negatively correlated with the density of myelin-basic protein immunoreactive fibers (males, r=-0.440; females, r=-0.481). The present results suggest that sexual differences in the adult ferret cerebrum are characterized by reduced volumes of the cerebral cortex and subcortical white matter in females, and by overall reductions in physiochemical characteristics, as obtained by short TR/TE-MRI, in females. It should be noted that short TR/TE-MRI-based MIP delineated functional cortical areas related to myeloarchitecture in 3D. Such an

  20. Advances in Clinical PET/MRI Instrumentation.

    PubMed

    Herzog, Hans; Lerche, Christoph

    2016-04-01

    In 2010, the first whole-body PET/MRI scanners installed for clinical use were the sequential Philips PET/MRI with PMT-based, TOF-capable technology and the integrated simultaneous Siemens PET/MRI. Avalanche photodiodes as non-magneto-sensitive readout electronics allowed PET integrated within the MRI. The experiences with these scanners showed that improvements of software aspects, such as attenuation correction, were necessary and that efficient protocols combining optimally PET and MRI must be still developed. In 2014, General Electric issued an integrated PET/MRI with SiPM-based PET detectors, allowing TOF-PET. Looking at the MRI components of current PET/MR imaging systems, primary improvements come from sequences and new coils.

  1. Intraoperative, real-time, functional MRI.

    PubMed

    Gering, D T; Weber, D M

    1998-01-01

    Functional MRI (fMRI) methods have been demonstrated to noninvasively identify motor-sensory, visual, and other areas of eloquent cortex for guiding surgical intervention. Typically, fMRI data are acquired preoperatively during a conventional surgical planning MRI examination. Unlike direct cortical stimulation at the time of surgery, however, preoperative fMRI methods do not account for the potential movement of tissues (relative to the time of functional imaging) that may occur in the surgical suite as a direct result of the intervention. Recently, an MRI device has been demonstrated for use in the surgical suite that has the potential to reduce the extent of cortical exposure required for the intervention. However, the invasive requirements of cortical mapping may supersede the invasive requirements of the surgical intervention itself. Consequently, we demonstrate here a modification to the intraoperative MRI device that facilitates a noninvasive, real-time, functional MR examination in the surgical suite.

  2. The anterolateral ligament of the knee: MRI appearance, association with the Segond fracture, and historical perspective.

    PubMed

    Porrino, Jack; Maloney, Ezekiel; Richardson, Michael; Mulcahy, Hyojeong; Ha, Alice; Chew, Felix S

    2015-02-01

    OBJECTIVE. A recent publication has drawn attention to the anterolateral ligament, a structure of the knee with which most radiologists are unfamiliar. We evaluate this structure on MRI; clarify its origin, insertion, meniscal relationship, and morphologic appearance; and identify its relationship with the Segond fracture. MATERIALS AND METHODS. A total of 53 routine knee MRI studies interpreted as normal were reviewed to characterize the anterolateral ligament. A further 20 knee MRI studies with a Segond fracture were assessed to determine a relationship between the fracture and the anterolateral ligament. RESULTS. In all 53 cases, a structure was present along the lateral knee connecting the distal femur to the proximal tibia, with meniscofemoral and meniscotibial components. This structure was somewhat ill defined and sheetlike, inseparable from the adjacent fibular collateral ligament proximally and iliotibial band distally. Aside from one case limited by anatomic distortion, all cases with a Segond fracture exhibited attachment of this structure to the fracture fragment (19/20 cases). CONCLUSION. An ill-defined sheetlike structure along the lateral knee exists attaching the distal femur, body of lateral meniscus, and proximal tibia. This structure has been referenced in the literature dating back to Paul Segond's original description of the Segond fracture in 1879. The structure is identifiable on MRI and appears to be attached to the Segond fracture fragment. For the radiologist, it may be best to forgo an attempt to separate this structure into discrete divisions, such as the anterolateral ligament, because these individual components are inseparable on routine MRI. PMID:25615760

  3. Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging

    PubMed Central

    Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

    2014-01-01

    Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools—and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids’ apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas. PMID:24969421

  4. Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging.

    PubMed

    Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

    2014-07-15

    Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools--and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids' apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas. PMID:24969421

  5. Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging.

    PubMed

    Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

    2014-07-15

    Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools--and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids' apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas.

  6. Integration of DCE-MRI and DW-MRI Quantitative Parameters for Breast Lesion Classification

    PubMed Central

    Fusco, Roberta; Sansone, Mario; Filice, Salvatore; Granata, Vincenza; Catalano, Orlando; Amato, Daniela Maria; Di Bonito, Maurizio; D'Aiuto, Massimiliano; Capasso, Immacolata; Rinaldo, Massimo; Petrillo, Antonella

    2015-01-01

    Objective. The purpose of our study was to evaluate the diagnostic value of an imaging protocol combining dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted MRI (DW-MRI) in patients with suspicious breast lesions. Materials and Methods. A total of 31 breast lesions (15 malignant and 16 benign proved by histological examination) in 26 female patients were included in this study. For both DCE-MRI and DW-MRI model free and model based parameters were computed pixel by pixel on manually segmented ROIs. Statistical procedures included conventional linear analysis and more advanced techniques for classification of lesions in benign and malignant. Results. Our findings indicated no strong correlation between DCE-MRI and DW-MRI parameters. Results of classification analysis show that combining of DCE parameters or DW-MRI parameter, in comparison of single feature, does not yield a dramatic improvement of sensitivity and specificity of the two techniques alone. The best performance was obtained considering a full combination of all features. Moreover, the classification results combining all features are dominated by DCE-MRI features alone. Conclusion. The combination of DWI and DCE-MRI does not show a potential to dramatically increase the sensitivity and specificity of breast MRI. DCE-MRI alone gave the same performance as in combination with DW-MRI. PMID:26339597

  7. PCA-based groupwise image registration for quantitative MRI.

    PubMed

    Huizinga, W; Poot, D H J; Guyader, J-M; Klaassen, R; Coolen, B F; van Kranenburg, M; van Geuns, R J M; Uitterdijk, A; Polfliet, M; Vandemeulebroucke, J; Leemans, A; Niessen, W J; Klein, S

    2016-04-01

    Quantitative magnetic resonance imaging (qMRI) is a technique for estimating quantitative tissue properties, such as the T1 and T2 relaxation times, apparent diffusion coefficient (ADC), and various perfusion measures. This estimation is achieved by acquiring multiple images with different acquisition parameters (or at multiple time points after injection of a contrast agent) and by fitting a qMRI signal model to the image intensities. Image registration is often necessary to compensate for misalignments due to subject motion and/or geometric distortions caused by the acquisition. However, large differences in image appearance make accurate image registration challenging. In this work, we propose a groupwise image registration method for compensating misalignment in qMRI. The groupwise formulation of the method eliminates the requirement of choosing a reference image, thus avoiding a registration bias. The method minimizes a cost function that is based on principal component analysis (PCA), exploiting the fact that intensity changes in qMRI can be described by a low-dimensional signal model, but not requiring knowledge on the specific acquisition model. The method was evaluated on 4D CT data of the lungs, and both real and synthetic images of five different qMRI applications: T1 mapping in a porcine heart, combined T1 and T2 mapping in carotid arteries, ADC mapping in the abdomen, diffusion tensor mapping in the brain, and dynamic contrast-enhanced mapping in the abdomen. Each application is based on a different acquisition model. The method is compared to a mutual information-based pairwise registration method and four other state-of-the-art groupwise registration methods. Registration accuracy is evaluated in terms of the precision of the estimated qMRI parameters, overlap of segmented structures, distance between corresponding landmarks, and smoothness of the deformation. In all qMRI applications the proposed method performed better than or equally well as

  8. PCA-based groupwise image registration for quantitative MRI.

    PubMed

    Huizinga, W; Poot, D H J; Guyader, J-M; Klaassen, R; Coolen, B F; van Kranenburg, M; van Geuns, R J M; Uitterdijk, A; Polfliet, M; Vandemeulebroucke, J; Leemans, A; Niessen, W J; Klein, S

    2016-04-01

    Quantitative magnetic resonance imaging (qMRI) is a technique for estimating quantitative tissue properties, such as the T1 and T2 relaxation times, apparent diffusion coefficient (ADC), and various perfusion measures. This estimation is achieved by acquiring multiple images with different acquisition parameters (or at multiple time points after injection of a contrast agent) and by fitting a qMRI signal model to the image intensities. Image registration is often necessary to compensate for misalignments due to subject motion and/or geometric distortions caused by the acquisition. However, large differences in image appearance make accurate image registration challenging. In this work, we propose a groupwise image registration method for compensating misalignment in qMRI. The groupwise formulation of the method eliminates the requirement of choosing a reference image, thus avoiding a registration bias. The method minimizes a cost function that is based on principal component analysis (PCA), exploiting the fact that intensity changes in qMRI can be described by a low-dimensional signal model, but not requiring knowledge on the specific acquisition model. The method was evaluated on 4D CT data of the lungs, and both real and synthetic images of five different qMRI applications: T1 mapping in a porcine heart, combined T1 and T2 mapping in carotid arteries, ADC mapping in the abdomen, diffusion tensor mapping in the brain, and dynamic contrast-enhanced mapping in the abdomen. Each application is based on a different acquisition model. The method is compared to a mutual information-based pairwise registration method and four other state-of-the-art groupwise registration methods. Registration accuracy is evaluated in terms of the precision of the estimated qMRI parameters, overlap of segmented structures, distance between corresponding landmarks, and smoothness of the deformation. In all qMRI applications the proposed method performed better than or equally well as

  9. MRI and ultrasonography for diagnosis and monitoring of psoriatic arthritis.

    PubMed

    Coates, Laura C; Hodgson, Richard; Conaghan, Philip G; Freeston, Jane E

    2012-12-01

    Imaging techniques such as magnetic resonance imaging (MRI) and ultrasound (US) have been increasingly used in psoriatic arthritis (PsA) providing additional clues to the pathogenesis of this peripheral, axial and dermatologic disease. This has improved our understanding of the disease and can be used to aid diagnosis and then to follow outcomes of treatment. Both imaging modalities have highlighted the differing involvement of PsA when compared with rheumatoid arthritis (RA) with a significant burden of entheseal disease, flexor tenosynovitis (occurring alone or as part of dactylitis) and other extra-capsular inflammatory changes. MRI scanning has also highlighted the link between the nail and the distal interphalangeal (DIP) joint confirming previous clinical observations. Imaging studies in psoriasis patients have discovered a high level of subclinical inflammatory change but the clinical importance of such findings has not yet been defined. The potential use of MRI and US to monitor treatment outcomes has encouraged research in this field. In MRI, the PsA MRI Score (PsAMRIS) has been developed with promising initial validation. In US, work is ongoing with the OMERACT group to define key pathologies and to develop scoring systems. A few scoring systems are available for enthesitis scoring using US which are further being developed and refined. Further improvements in technologies in both of these fields offer exciting possibilities for future research. New MRI techniques offer the chance to image previously 'dark' structures such as tendons which is key in spondyloarthritides (SpA). Sonoelastography may also improve our understanding of tendon involvement in SpA. Whole-body multi-joint MRI allows a 'snapshot' of inflammation in PsA including joints, entheses and spinal involvement. Three-dimensional US should improve reliability and comparability of US scoring reducing inter-operator variability. The latest machines offer real-time fusion imaging employing US

  10. Cine MRI of swallowing in patients with advanced oral or oropharyngeal carcinoma: a feasibility study.

    PubMed

    Kreeft, Anne Marijn; Rasch, Coen R N; Muller, Sara H; Pameijer, Frank A; Hallo, Eeke; Balm, Alfons J M

    2012-06-01

    Treatment of oral and oropharyngeal cancer may cause dysphagia. Purpose is to examine whether cine magnetic resonance imaging (MRI) yields additional information compared to standard examination in the evaluation of posttreatment dysphagia and mobility of oral and oropharyngeal structures. Thirty-four cine MRIs were made in 23 patients with advanced oral and oropharyngeal cancer, consisting of an MR image every 800 ms during swallowing which is compared to videofluoroscopy and quality of life questionnaires. A scoring system was applied to assess mobility on cine MR and videofluoroscopy leading to a score ranging from 9 to 17. Cine MRI of the swallowing in a midsagittal plane visualized the tumor (if located in the same plane), important anatomic structures and surgical reconstructions. Posttreatment mobility on cine MRI and videofluoroscopy was significantly diminished compared to pretreatment, mean pretreatment cine MRI score was 10.8 and posttreatment 12.4 (p = 0.017). Impaired mobility on cine MRI was significantly correlated to more swallowing problems (Spearman's correlation coefficient 0.73, p = 0.04), on videofluoroscopy not. Cine MRI is a promising new technique as an adjunct to standard examinations for evaluation of swallowing in patients with oral and oropharyngeal cancer. Cine MRI directly visualizes the dynamics of swallowing and allows evaluation of pre- and posttreatment differences. Abnormal findings are significantly correlated with subjective swallowing complaints of patients.

  11. Severe bone marrow edema on sacroiliac joint MRI increases the risk of low BMD in patients with axial spondyloarthritis.

    PubMed

    Kim, Ha Neul; Jung, Joon-Yong; Hong, Yeon Sik; Park, Sung-Hwan; Kang, Kwi Young

    2016-01-01

    To determine the association between inflammatory and structural lesions on sacroiliac joint (SIJ) MRI and BMD and to identify risk factors for low BMD in patients with axial spondyloarthritis (axSpA). Seventy-six patients who fulfilled the ASAS axSpA criteria were enrolled. All underwent SIJ MRI and BMD measurement at the lumbar spine, femoral neck, and total hip. Inflammatory and structural lesions on SIJ MRI were scored. Laboratory tests and assessment of radiographic and disease activity were performed at the time of MRI. The association between SIJ MRI findings and BMD was evaluated. Among the 76 patients, 14 (18%) had low BMD. Patients with low BMD showed significantly higher bone marrow edema (BME) and deep BME scores on MRI than those with normal BMD (p < 0.047 and 0.007, respectively). Inflammatory lesions on SIJ MRI correlated with BMD at the femoral neck and total hip. Multivariate analysis identified the presence of deep BME on SIJ MRI, increased CRP, and sacroiliitis on X-ray as risk factors for low BMD (OR = 5.6, 14.6, and 2.5, respectively). The presence of deep BME on SIJ MRI, increased CRP levels, and severity of sacroiliitis on X-ray were independent risk factors for low BMD. PMID:26931505

  12. Liver isolation in abdominal MRI.

    PubMed

    Rajasvaran, Logeswaran; Haw, Tan Wooi; Sarker, Shakowat Zaman

    2008-08-01

    This work presents a method for liver isolation in magnetic resonance imaging (MRI) abdomen images. It is based on a priori statistical information about the shape of the liver obtained from a training set using the segmentation approach. Morphological watershed algorithm is used as a key technique as it is a simple and intuitive method, producing a complete division of the image in separated regions even if the contrast is poor, and it is fast, with possibility for parallel implementation. To overcome the over-segmentation problem of the watershed process, image preprocessing and postprocessing are applied. Morphological smoothing, Gaussian smoothing, intensity thresholding, gradient computation and gradient thresholding are proposed for preprocessing with morphological and graph based region adjacent list constructed for region merging. A new integrated region similarity function is also defined for region merging control. The proposed method produces good isolation of liver in axial MRI images of the abdomen, as is shown in this paper.

  13. Polycatechol Nanoparticle MRI Contrast Agents.

    PubMed

    Li, Yiwen; Huang, Yuran; Wang, Zhao; Carniato, Fabio; Xie, Yijun; Patterson, Joseph P; Thompson, Matthew P; Andolina, Christopher M; Ditri, Treffly B; Millstone, Jill E; Figueroa, Joshua S; Rinehart, Jeffrey D; Scadeng, Miriam; Botta, Mauro; Gianneschi, Nathan C

    2016-02-01

    Amphiphilic triblock copolymers containing Fe(III) -catecholate complexes formulated as spherical- or cylindrical-shaped micellar nanoparticles (SMN and CMN, respectively) are described as new T1-weighted agents with high relaxivity, low cytotoxicity, and long-term stability in biological fluids. Relaxivities of both SMN and CMN exceed those of established gadolinium chelates across a wide range of magnetic field strengths. Interestingly, shape-dependent behavior is observed in terms of the particles' interactions with HeLa cells, with CMN exhibiting enhanced uptake and contrast via magnetic resonance imaging (MRI) compared with SMN. These results suggest that control over soft nanoparticle shape will provide an avenue for optimization of particle-based contrast agents as biodiagnostics. The polycatechol nanoparticles are proposed as suitable for preclinical investigations into their viability as gadolinium-free, safe, and effective imaging agents for MRI contrast enhancement. PMID:26681255

  14. 3D interactive tractography-informed resting-state fMRI connectivity

    PubMed Central

    Chamberland, Maxime; Bernier, Michaël; Fortin, David; Whittingstall, Kevin; Descoteaux, Maxime

    2015-01-01

    In the past decade, the fusion between diffusion magnetic resonance imaging (dMRI) and functional magnetic resonance imaging (fMRI) has opened the way for exploring structure-function relationships in vivo. As it stands, the common approach usually consists of analysing fMRI and dMRI datasets separately or using one to inform the other, such as using fMRI activation sites to reconstruct dMRI streamlines that interconnect them. Moreover, given the large inter-individual variability of the healthy human brain, it is possible that valuable information is lost when a fixed set of dMRI/fMRI analysis parameters such as threshold values are assumed constant across subjects. By allowing one to modify such parameters while viewing the results in real-time, one can begin to fully explore the sensitivity of structure-function relations and how they differ across brain areas and individuals. This is especially important when interpreting how structure-function relationships are altered in patients with neurological disorders, such as the presence of a tumor. In this study, we present and validate a novel approach to achieve this: First, we present an interactive method to generate and visualize tractography-driven resting-state functional connectivity, which reduces the bias introduced by seed size, shape and position. Next, we demonstrate that structural and functional reconstruction parameters explain a significant portion of intra- and inter-subject variability. Finally, we demonstrate how our proposed approach can be used in a neurosurgical planning context. We believe this approach will promote the exploration of structure-function relationships in a subject-specific aspect and will open new opportunities for connectomics. PMID:26321901

  15. Data on the verification and validation of segmentation and registration methods for diffusion MRI.

    PubMed

    Esteban, Oscar; Zosso, Dominique; Daducci, Alessandro; Bach-Cuadra, Meritxell; Ledesma-Carbayo, María J; Thiran, Jean-Philippe; Santos, Andres

    2016-09-01

    The verification and validation of segmentation and registration methods is a necessary assessment in the development of new processing methods. However, verification and validation of diffusion MRI (dMRI) processing methods is challenging for the lack of gold-standard data. The data described here are related to the research article entitled "Surface-driven registration method for the structure-informed segmentation of diffusion MR images" [1], in which publicly available data are used to derive golden-standard reference-data to validate and evaluate segmentation and registration methods in dMRI. PMID:27508235

  16. Data on the verification and validation of segmentation and registration methods for diffusion MRI.

    PubMed

    Esteban, Oscar; Zosso, Dominique; Daducci, Alessandro; Bach-Cuadra, Meritxell; Ledesma-Carbayo, María J; Thiran, Jean-Philippe; Santos, Andres

    2016-09-01

    The verification and validation of segmentation and registration methods is a necessary assessment in the development of new processing methods. However, verification and validation of diffusion MRI (dMRI) processing methods is challenging for the lack of gold-standard data. The data described here are related to the research article entitled "Surface-driven registration method for the structure-informed segmentation of diffusion MR images" [1], in which publicly available data are used to derive golden-standard reference-data to validate and evaluate segmentation and registration methods in dMRI.

  17. MRI in knee osteoarthritis. Application in diet intervention.

    PubMed

    Gudbergsen, Henrik

    2013-03-01

    This thesis examines two main hypotheses: 1. Obese knee osteoarthritis (KOA) patients can achieve symptomatic improvements following diet intervention regardless of their level of structural damage and overall joint malfunctioning: 2. Rapid weight-loss in obese patients with KOA will lead to improvements in KOA related pathology that can be assessed and evaluated by MRI. Data for the studies were obtained from obese KOA patients who were recruited for a 16 week diet intervention trial, the CAROT-trial (ClinicalTrials.gov identification no.: NCT00655941). Inclusion criteria were age ≥ 50 years, BMI ≥ 30 kg/square metro plus symptomatic and verified KOA. Patients underwent a 16 weeks dietary programme with formula products and counselling. Baseline and week 16 assessments included clinical examinations, MRI and CR of the most symptomatic knee, muscle strength tests, gait analyses, blood samples and collection of patient-reported outcomes with a variety of generic and specific health status questionnaires. MRI scans were graded by the BLOKS and CR was analysed by measuring the mJSW and grading the knee as described by KL. 388 possible subjects were pre-screened, 192 were enrolled. Following the 16 weeks diet intervention 175 patients remained in the study. 187 (97%) MRI scans were completed at baseline, 172 (98 %) MRI scans obtained at week 16 and this left the study with 169 (97%) patients with complete MRI datasets at week 16. No statistical significant differences were detected between baseline characteristics of all the initially included patients (n = 192) and the 169 patients included in the per protocol analyses performed in study III (p < 0.05). In order to apply BLOKS, an extensive MRI scoring system, in study II and III we examined the inter- and intra-observer reliability of the various BLOKS items in study I. Results showed that our assessment team performed as described in the original study defining BLOKS and that the patients in the CAROT-trial were

  18. Fetal MRI: An approach to practice: A review.

    PubMed

    Saleem, Sahar N

    2014-09-01

    MRI has been increasingly used for detailed visualization of the fetus in utero as well as pregnancy structures. Yet, the familiarity of radiologists and clinicians with fetal MRI is still limited. This article provides a practical approach to fetal MR imaging. Fetal MRI is an interactive scanning of the moving fetus owed to the use of fast sequences. Single-shot fast spin-echo (SSFSE) T2-weighted imaging is a standard sequence. T1-weighted sequences are primarily used to demonstrate fat, calcification and hemorrhage. Balanced steady-state free-precession (SSFP), are beneficial in demonstrating fetal structures as the heart and vessels. Diffusion weighted imaging (DWI), MR spectroscopy (MRS), and diffusion tensor imaging (DTI) have potential applications in fetal imaging. Knowing the developing fetal MR anatomy is essential to detect abnormalities. MR evaluation of the developing fetal brain should include recognition of the multilayered-appearance of the cerebral parenchyma, knowledge of the timing of sulci appearance, myelination and changes in ventricular size. With advanced gestation, fetal organs as lungs and kidneys show significant changes in volume and T2-signal. Through a systematic approach, the normal anatomy of the developing fetus is shown to contrast with a wide spectrum of fetal disorders. The abnormalities displayed are graded in severity from simple common lesions to more complex rare cases. Complete fetal MRI is fulfilled by careful evaluation of the placenta, umbilical cord and amniotic cavity. Accurate interpretation of fetal MRI can provide valuable information that helps prenatal counseling, facilitate management decisions, guide therapy, and support research studies. PMID:25685519

  19. Parallel MRI at microtesla fields.

    PubMed

    Zotev, Vadim S; Volegov, Petr L; Matlashov, Andrei N; Espy, Michelle A; Mosher, John C; Kraus, Robert H

    2008-06-01

    Parallel imaging techniques have been widely used in high-field magnetic resonance imaging (MRI). Multiple receiver coils have been shown to improve image quality and allow accelerated image acquisition. Magnetic resonance imaging at ultra-low fields (ULF MRI) is a new imaging approach that uses SQUID (superconducting quantum interference device) sensors to measure the spatially encoded precession of pre-polarized nuclear spin populations at microtesla-range measurement fields. In this work, parallel imaging at microtesla fields is systematically studied for the first time. A seven-channel SQUID system, designed for both ULF MRI and magnetoencephalography (MEG), is used to acquire 3D images of a human hand, as well as 2D images of a large water phantom. The imaging is performed at 46 mu T measurement field with pre-polarization at 40 mT. It is shown how the use of seven channels increases imaging field of view and improves signal-to-noise ratio for the hand images. A simple procedure for approximate correction of concomitant gradient artifacts is described. Noise propagation is analyzed experimentally, and the main source of correlated noise is identified. Accelerated imaging based on one-dimensional undersampling and 1D SENSE (sensitivity encoding) image reconstruction is studied in the case of the 2D phantom. Actual threefold imaging acceleration in comparison to single-average fully encoded Fourier imaging is demonstrated. These results show that parallel imaging methods are efficient in ULF MRI, and that imaging performance of SQUID-based instruments improves substantially as the number of channels is increased.

  20. Parallel MRI at microtesla fields

    NASA Astrophysics Data System (ADS)

    Zotev, Vadim S.; Volegov, Petr L.; Matlashov, Andrei N.; Espy, Michelle A.; Mosher, John C.; Kraus, Robert H.

    2008-06-01

    Parallel imaging techniques have been widely used in high-field magnetic resonance imaging (MRI). Multiple receiver coils have been shown to improve image quality and allow accelerated image acquisition. Magnetic resonance imaging at ultra-low fields (ULF MRI) is a new imaging approach that uses SQUID (superconducting quantum interference device) sensors to measure the spatially encoded precession of pre-polarized nuclear spin populations at microtesla-range measurement fields. In this work, parallel imaging at microtesla fields is systematically studied for the first time. A seven-channel SQUID system, designed for both ULF MRI and magnetoencephalography (MEG), is used to acquire 3D images of a human hand, as well as 2D images of a large water phantom. The imaging is performed at 46 μT measurement field with pre-polarization at 40 mT. It is shown how the use of seven channels increases imaging field of view and improves signal-to-noise ratio for the hand images. A simple procedure for approximate correction of concomitant gradient artifacts is described. Noise propagation is analyzed experimentally, and the main source of correlated noise is identified. Accelerated imaging based on one-dimensional undersampling and 1D SENSE (sensitivity encoding) image reconstruction is studied in the case of the 2D phantom. Actual threefold imaging acceleration in comparison to single-average fully encoded Fourier imaging is demonstrated. These results show that parallel imaging methods are efficient in ULF MRI, and that imaging performance of SQUID-based instruments improves substantially as the number of channels is increased.

  1. Retroperitoneal bronchogenic cyst: MRI findings.

    PubMed

    Castro, R; Oliveira, M I; Fernandes, T; Madureira, A J

    2013-01-01

    The authors describe a case of a retroperitoneal bronchogenic cyst in a 36-year-old female. She presented with abdominal pain, nausea, and vomiting. An MRI scan revealed an 8 cm cystic lesion in the left upper retroperitoneum, with intermediate signal on T2-weighted images, high signal on T1 weighted images, and lack of internal enhancement after gadolinium. After laparoscopic excision, the histology findings were compatible with a bronchogenic cyst, which is extremely uncommon in the retroperitoneum.

  2. Quantitative MRI Assessment of Leukoencephalopathy

    PubMed Central

    Reddick, Wilburn E.; Glass, John O.; Langston, James W.; Helton, Kathleen J.

    2008-01-01

    Quantitative MRI assessment of leukoencephalopathy is difficult because the MRI properties of leukoencephalopathy significantly overlap those of normal tissue. This report describes the use of an automated procedure for longitudinal measurement of tissue volume and relaxation times to quantify leukoencephalopathy. Images derived by using this procedure in patients undergoing therapy for acute lymphoblastic leukemia (ALL) are presented. Five examinations from each of five volunteers (25 examinations) were used to test the reproducibility of quantitated baseline and subsequent, normal-appearing images; the coefficients of variation were less than 2% for gray and white matter. Regions of leukoencephalopathy in patients were assessed by comparison with manual segmentation. Two radiologists manually segmented images from 15 randomly chosen MRI examinations that exhibited leukoencephalopathy. Kappa analyses showed that the two radiologists’ interpretations were concordant (κ = 0.70) and that each radiologist’s interpretations agreed with the results of the automated procedure (κ = 0.57 and 0.55).The clinical application of this method was illustrated by analysis of images from sequential MR examinations of two patients who developed leukoencephalopathy during treatment for ALL. The ultimate goal is to use these quantitative MR imaging measures to better understand therapy-induced neurotoxicity, which can be limited or even reversed with some combination of therapy adjustments and pharmacological and neurobehavioral interventions. PMID:11979570

  3. Automatic MRI 2D brain segmentation using graph searching technique.

    PubMed

    Pedoia, Valentina; Binaghi, Elisabetta

    2013-09-01

    Accurate and efficient segmentation of the whole brain in magnetic resonance (MR) images is a key task in many neuroscience and medical studies either because the whole brain is the final anatomical structure of interest or because the automatic extraction facilitates further analysis. The problem of segmenting brain MRI images has been extensively addressed by many researchers. Despite the relevant achievements obtained, automated segmentation of brain MRI imagery is still a challenging problem whose solution has to cope with critical aspects such as anatomical variability and pathological deformation. In the present paper, we describe and experimentally evaluate a method for segmenting brain from MRI images basing on two-dimensional graph searching principles for border detection. The segmentation of the whole brain over the entire volume is accomplished slice by slice, automatically detecting frames including eyes. The method is fully automatic and easily reproducible by computing the internal main parameters directly from the image data. The segmentation procedure is conceived as a tool of general applicability, although design requirements are especially commensurate with the accuracy required in clinical tasks such as surgical planning and post-surgical assessment. Several experiments were performed to assess the performance of the algorithm on a varied set of MRI images obtaining good results in terms of accuracy and stability. PMID:23757180

  4. The MRI of extraadrenal pheochromocytoma in the abdominal cavity.

    PubMed

    Qiao, Huang Sui; Feng, Xu Lin; Yong, Li; Yong, Zhang; Lian, Zhong Jing; Ling, Liang Bi

    2007-06-01

    The purpose of this study was to summarize the MR appearances of extraadrenal pheochromocytoma in the abdominal cavity and evaluate the capabilities of MRI in diagnosis of the tumor. Eleven consecutive patients with an extraadrenal pheochromocytoma in abdominal cavity who underwent preoperative 0.5 T (n=5) or 1.5 T (n=6) superconductor MRI and had a surgical resection were enrolled in the study. The MR scanning protocol included axial T(2)-weighted imaging with or without fat-suppressed sequences, axial and coronal uncontrast and contrast T(1)-weighted sequences with or without fat suppression. The extraadrenal pheochromocytomas were found in retroperitoneum (n=5), the urinary bladder (n=1), the pelvis (n=1), the right prerenal area (n=1), the renal hilus (n=1), the left paramusculus psoas major (n=1) and liver (n=1). The mean maximal diameter of tumors was 55.9 mm (range 17.8-162.2 mm). The high signal intensity was seen on T(2)-weighted imaging in all tumors compared to muscle or liver, especially with fat suppression. The intratumoral septa and capsules were shown in 63.6% and 72.7% of cases, respectively, which had low signal intensity on T(2)-weighted imaging. These relative characteristics may be helpful for qualitative diagnosis of extraadrenal pheochromocytomas with MRI. Other usefulness of MRI was to locate the position, to decide the range of tumors and to show well the relationship between the tumor and near structures.

  5. The circuitry of abulia: Insights from functional connectivity MRI

    PubMed Central

    Siegel, J.S.; Snyder, A.Z.; Metcalf, N.V.; Fucetola, R.P.; Hacker, C.D.; Shimony, J.S.; Shulman, G.L.; Corbetta, M.

    2014-01-01

    Background Functional imaging and lesion studies have associated willed behavior with the anterior cingulate cortex (ACC). Abulia is a syndrome characterized by apathy and deficiency of motivated behavior. Abulia is most frequently associated with ACC damage, but also occurs following damage to subcortical nuclei (striatum, globus pallidus, thalamic nuclei). We present resting state functional connectivity MRI (fcMRI) data from an individual who suffered a stroke leading to abulia. We hypothesized that, although structural imaging revealed no damage to the patient's ACC, fcMRI would uncover aberrant function in this region and in the relevant cortical networks. Methods Resting state correlations in the patient's gray matter were compared to those of age-matched controls. Using a novel method to identify abnormal patterns of functional connectivity in single subjects, we identified areas and networks with aberrant connectivity. Results Networks associated with memory (default mode network) and executive function (cingulo-opercular network) were abnormal. The patient's anterior cingulate was among the areas showing aberrant functional connectivity. In a rescan 3 years later, deficits remained stable and fcMRI findings were replicated. Conclusions These findings suggest that the aberrant functional connectivity mapping approach described may be useful for linking stroke symptoms to disrupted network connectivity. PMID:25379445

  6. Bridging the Gap between MRI and Postmortem Research in Autism

    PubMed Central

    Schumann, Cynthia Mills; Nordahl, Christine Wu

    2010-01-01

    Autism is clearly a disorder of neural development, but when, where, and how brain pathology occurs remains elusive. Typical brain development is comprised of several stages, including the proliferation and migration of neurons, creation of dendritic arbors and synaptic connections, and eventually dendritic pruning and programmed cell death. Any deviation at one or more of these stages could produce catastrophic downstream effects. MRI studies of autism have provided important clues, describing an aberrant trajectory of growth during early childhood that is both present in total brain and marked in specific structures such as the amygdala. However, given the coarse resolution of MRI, the field must also look towards postmortem human brain research to help elucidate the neurobiological underpinnings of MRI volumetric findings. Likewise, studies of postmortem tissue may benefit by looking to findings from MRI studies to narrow hypotheses and target specific brain regions. In this review, we discuss the strengths, limitations, and major contributions of each approach to autism research. We then describe how they relate and what they can learn from each other. Only by integrating these approaches will we be able to fully explain the neuropathology of autism. PMID:20869352

  7. MRI-Guided Target Motion Assessment using Dynamic Automatic Segmentation

    NASA Astrophysics Data System (ADS)

    Saenz, Daniel L.

    Motion significantly impacts the radiotherapy process and represents one of the persisting problems in treatment delivery. In order to improve motion management techniques and implement future image guided radiotherapy tools such as MRI-guidance, automatic segmentation algorithms hold great promise. Such algorithms are attractive due to their direct measurement accuracy, speed, and ability to assess motion trajectories for daily treatment plan modifications. We developed and optimized an automatic segmentation technique to enable target tracking using MR cines, 4D-MRI, and 4D-CT. This algorithm overcomes weaknesses in automatic contouring such as lack of image contrast, subjectivity, slow speed, and lack of differentiating feature vectors by the use of morphological processing. The software is enhanced with predictive parameter capabilities and dynamic processing. The 4D-MRI images are acquired by applying a retrospective phase binning approach to radially-acquired MR image projections. The quantification of motion is validated with a motor phantom undergoing a known trajectory in 4D-CT, 4D-MRI, and in MR cines from the ViewRay MR-Guided RT system. In addition, a clinical case study demonstrates wide-reaching implications of the software to segment lesions in the brain and lung as well as critical structures such as the liver. Auto-segmentation results from MR cines of canines correlate well with manually drawn contours, both in terms of Dice similarity coefficient and agreement of extracted motion trajectories.

  8. A review of MRI findings in schizophrenia

    PubMed Central

    Shenton, Martha E.; Dickey, Chandlee C.; Frumin, Melissa; McCarley, Robert W.

    2009-01-01

    neuropathology of schizophrenia is largely due to advances in in vivo MRI techniques. These advances have now led to the identification of a number of brain abnormalities in schizophrenia. Some of these abnormalities confirm earlier post-mortem findings, and most are small and subtle, rather than large, thus necessitating more advanced and accurate measurement tools. These findings include ventricular enlargement (80% of studies reviewed) and third ventricle enlargement (73% of studies reviewed). There is also preferential involvement of medial temporal lobe structures (74% of studies reviewed), which include the amygdala, hippocampus, and parahippocampal gyrus, and neocortical temporal lobe regions (superior temporal gyrus) (100% of studies reviewed). When gray and white matter of superior temporal gyrus was combined, 67% of studies reported abnormalities. There was also moderate evidence for frontal lobe abnormalities (59% of studies reviewed), particularly prefrontal gray matter and orbitofrontal regions. Similarly, there was moderate evidence for parietal lobe abnormalities (60% of studies reviewed), particularly of the inferior parietal lobule which includes both supramarginal and angular gyri. Additionally, there was strong to moderate evidence for subcortical abnormalities (i.e. cavum septi pellucidi—92% of studies reviewed, basal ganglia—68% of studies reviewed, corpus callosum—63% of studies reviewed, and thalamus—42% of studies reviewed), but more equivocal evidence for cerebellar abnormalities (31% of studies reviewed). The timing of such abnormalities has not yet been determined, although many are evident when a patient first becomes symptomatic. There is, however, also evidence that a subset of brain abnormalities may change over the course of the illness. The most parsimonious explanation is that some brain abnormalities are neurodevelopmental in origin but unfold later in development, thus setting the stage for the development of the symptoms of

  9. Decision forests for learning prostate cancer probability maps from multiparametric MRI

    NASA Astrophysics Data System (ADS)

    Ehrenberg, Henry R.; Cornfeld, Daniel; Nawaf, Cayce B.; Sprenkle, Preston C.; Duncan, James S.

    2016-03-01

    Objectives: Advances in multiparametric magnetic resonance imaging (mpMRI) and ultrasound/MRI fusion imaging offer a powerful alternative to the typical undirected approach to diagnosing prostate cancer. However, these methods require the time and expertise needed to interpret mpMRI image scenes. In this paper, a machine learning framework for automatically detecting and localizing cancerous lesions within the prostate is developed and evaluated. Methods: Two studies were performed to gather MRI and pathology data. The 12 patients in the first study underwent an MRI session to obtain structural, diffusion-weighted, and dynamic contrast enhanced image vol- umes of the prostate, and regions suspected of being cancerous from the MRI data were manually contoured by radiologists. Whole-mount slices of the prostate were obtained for the patients in the second study, in addition to structural and diffusion-weighted MRI data, for pathology verification. A 3-D feature set for voxel-wise appear- ance description combining intensity data, textural operators, and zonal approximations was generated. Voxels in a test set were classified as normal or cancer using a decision forest-based model initialized using Gaussian discriminant analysis. A leave-one-patient-out cross-validation scheme was used to assess the predictions against the expert manual segmentations confirmed as cancer by biopsy. Results: We achieved an area under the average receiver-operator characteristic curve of 0.923 for the first study, and visual assessment of the probability maps showed 21 out of 22 tumors were identified while a high level of specificity was maintained. In addition to evaluating the model against related approaches, the effects of the individual MRI parameter types were explored, and pathological verification using whole-mount slices from the second study was performed. Conclusions: The results of this paper show that the

  10. Joint brain connectivity estimation from diffusion and functional MRI data

    NASA Astrophysics Data System (ADS)

    Chu, Shu-Hsien; Lenglet, Christophe; Parhi, Keshab K.

    2015-03-01

    Estimating brain wiring patterns is critical to better understand the brain organization and function. Anatomical brain connectivity models axonal pathways, while the functional brain connectivity characterizes the statistical dependencies and correlation between the activities of various brain regions. The synchronization of brain activity can be inferred through the variation of blood-oxygen-level dependent (BOLD) signal from functional MRI (fMRI) and the neural connections can be estimated using tractography from diffusion MRI (dMRI). Functional connections between brain regions are supported by anatomical connections, and the synchronization of brain activities arises through sharing of information in the form of electro-chemical signals on axon pathways. Jointly modeling fMRI and dMRI data may improve the accuracy in constructing anatomical connectivity as well as functional connectivity. Such an approach may lead to novel multimodal biomarkers potentially able to better capture functional and anatomical connectivity variations. We present a novel brain network model which jointly models the dMRI and fMRI data to improve the anatomical connectivity estimation and extract the anatomical subnetworks associated with specific functional modes by constraining the anatomical connections as structural supports to the functional connections. The key idea is similar to a multi-commodity flow optimization problem that minimizes the cost or maximizes the efficiency for flow configuration and simultaneously fulfills the supply-demand constraint for each commodity. In the proposed network, the nodes represent the grey matter (GM) regions providing brain functionality, and the links represent white matter (WM) fiber bundles connecting those regions and delivering information. The commodities can be thought of as the information corresponding to brain activity patterns as obtained for instance by independent component analysis (ICA) of fMRI data. The concept of information

  11. Joint brain connectivity estimation from diffusion and functional MRI data

    NASA Astrophysics Data System (ADS)

    Chu, Shu-Hsien; Lenglet, Christophe; Parhi, Keshab K.

    2015-03-01

    Estimating brain wiring patterns is critical to better understand the brain organization and function. Anatomical brain connectivity models axonal pathways, while the functional brain connectivity characterizes the statistical dependencies and correlation between the activities of various brain regions. The synchronization of brain activity can be inferred through the variation of blood-oxygen-level dependent (BOLD) signal from functional MRI (fMRI) and the neural connections can be estimated using tractography from diffusion MRI (dMRI). Functional connections between brain regions are supported by anatomical connections, and the synchronization of brain activities arises through sharing of information in the form of electro-chemical signals on axon pathways. Jointly modeling fMRI and dMRI data may improve the accuracy in constructing anatomical connectivity as well as functional connectivity. Such an approach may lead to novel multimodal biomarkers potentially able to better capture functional and anatomical connectivity variations. We present a novel brain network model which jointly models the dMRI and fMRI data to improve the anatomical connectivity estimation and extract the anatomical subnetworks associated with specific functional modes by constraining the anatomical connections as structural supports to the functional connections. The key idea is similar to a multi-commodity flow optimization problem that minimizes the cost or maximizes the efficiency for flow configuration and simultaneously fulfills the supply-demand constraint for each commodity. In the proposed network, the nodes represent the grey matter (GM) regions providing brain functionality, and the links represent white matter (WM) fiber bundles connecting those regions and delivering information. The commodities can be thought of as the information corresponding to brain activity patterns as obtained for instance by independent component analysis (ICA) of fMRI data. The concept of information

  12. Maleimidyl magnetic nanoplatform for facile molecular MRI

    NASA Astrophysics Data System (ADS)

    Heo, Dan; Lee, Eugene; Ku, Minhee; Hwang, Seungyeon; Kim, Bongjune; Park, Yeonji; Lee, Young Han; Huh, Yong-Min; Haam, Seungjoo; Cheong, Jae-Ho; Yang, Jaemoon; Suh, Jin-Suck

    2014-07-01

    In this study, we developed the maleimidyl magnetic nanoplatform, which enables functional targeting of a biomarker-specific moiety for molecular imaging via MRI. The maleimide group of the maleimidyl magnetic nanoplatform is conjugated with a thiol group without additional crosslinkers and side products. A physicochemical analysis was conducted to verify the effectiveness of the maleimidyl magnetic nanoplatform, and the existence of the maleimidyl group was investigated using the platform. To prepare biomarker-specific MRI probes, a thiolated aptamer and peptide were immobilized onto the maleimidyl group of the maleimidyl magnetic nanoplatform. The fabricated MRI probes were applied to four cancer cell lines: HT1080, MCF7, MKN45, and HEK293T. To investigate the potential of the molecular MRI probe, the target-biomarker specificity was confirmed without serious cytotoxicity, and in vivo MRI analysis using a xenograft mouse model was demonstrated. We believe these results will be useful for fabricating molecular MRI probes for the diagnosis of cancer.

  13. Functional MRI of the placenta--From rodents to humans.

    PubMed

    Avni, R; Neeman, M; Garbow, J R

    2015-06-01

    The placenta performs a wide range of physiological functions; insufficiencies in these functions may result in a variety of severe prenatal and postnatal syndromes with long-term negative impacts on human adult health. Recent advances in magnetic resonance imaging (MRI) studies of placental function, in both animal models and humans, have contributed significantly to our understanding of placental structure, blood flow, oxygenation status, and metabolic profile, and have provided important insights into pregnancy complications.

  14. Negative childhood experiences alter a prefrontal-insular-motor cortical network in healthy adults: A preliminary multimodal rsfMRI-fMRI-MRS-dMRI study

    PubMed Central

    Duncan, Niall W.; Hayes, Dave J.; Wiebking, Christine; Tiret, Brice; Pietruska, Karin; Chen, David Q.; Rainville, Pierre; Marjańska, Malgorzata; Mohammid, Omar; Doyon, Julien; Hodaie, Mojgan; Northoff, Georg

    2016-01-01

    Research in humans and animals has shown that negative childhood experiences (NCE) can have long-term effects on the structure and function of the brain. Alterations have been noted in grey and white matter, in the brain’s resting state, on the glutamatergic system, and on neural and behavioural responses to aversive stimuli. These effects can be linked to psychiatric disorder such as depression and anxiety disorders that are influenced by excessive exposure to early life stressors. The aim of the current study was to investigate the effect of NCEs on these systems. Resting state functional MRI (rsfMRI), aversion task fMRI, glutamate magnetic resonance spectroscopy (MRS), and diffusion magnetic resonance imaging (dMRI) were combined with the Childhood Trauma Questionnaire (CTQ) in healthy subjects to examine the impact of NCEs on the brain. Low CTQ scores, a measure of NCEs, were related to higher resting state glutamate levels and higher resting state entropy in the medial prefrontal cortex (mPFC). CTQ scores, mPFC glutamate and entropy, correlated with neural BOLD responses to the anticipation of aversive stimuli in regions throughout the aversion-related network, with strong correlations between all measures in the motor cortex and left insula. Structural connectivity strength, measured using mean fractional anisotropy, between the mPFC and left insula correlated to aversion-related signal changes in the motor cortex. These findings highlight the impact of NCEs on multiple inter-related brain systems. In particular, they highlight the role of a prefrontal-insular-motor cortical network in the processing and responsivity to aversive stimuli and its potential adaptability by NCEs. PMID:26287448

  15. MRI-based anatomical model of the human head for specific absorption rate mapping

    PubMed Central

    Makris, Nikos; Angelone, Leonardo; Tulloch, Seann; Sorg, Scott; Kaiser, Jonathan; Kennedy, David

    2009-01-01

    In this study, we present a magnetic resonance imaging (MRI)-based, high-resolution, numerical model of the head of a healthy human subject. In order to formulate the model, we performed quantitative volumetric segmentation on the human head, using T1-weighted MRI. The high spatial resolution used (1 × 1 × 1 mm3), allowed for the precise computation and visualization of a higher number of anatomical structures than provided by previous models. Furthermore, the high spatial resolution allowed us to study individual thin anatomical structures of clinical relevance not visible by the standard model currently adopted in computational bioelectromagnetics. When we computed the electromagnetic field and specific absorption rate (SAR) at 7 Tesla MRI using this high-resolution model, we were able to obtain a detailed visualization of such fine anatomical structures as the epidermis/dermis, bone structures, bone-marrow, white matter and nasal and eye structures. PMID:18985401

  16. Competitive advantage of PET/MRI.

    PubMed

    Jadvar, Hossein; Colletti, Patrick M

    2014-01-01

    Multimodality imaging has made great strides in the imaging evaluation of patients with a variety of diseases. Positron emission tomography/computed tomography (PET/CT) is now established as the imaging modality of choice in many clinical conditions, particularly in oncology. While the initial development of combined PET/magnetic resonance imaging (PET/MRI) was in the preclinical arena, hybrid PET/MR scanners are now available for clinical use. PET/MRI combines the unique features of MRI including excellent soft tissue contrast, diffusion-weighted imaging, dynamic contrast-enhanced imaging, fMRI and other specialized sequences as well as MR spectroscopy with the quantitative physiologic information that is provided by PET. Most evidence for the potential clinical utility of PET/MRI is based on studies performed with side-by-side comparison or software-fused MRI and PET images. Data on distinctive utility of hybrid PET/MRI are rapidly emerging. There are potential competitive advantages of PET/MRI over PET/CT. In general, PET/MRI may be preferred over PET/CT where the unique features of MRI provide more robust imaging evaluation in certain clinical settings. The exact role and potential utility of simultaneous data acquisition in specific research and clinical settings will need to be defined. It may be that simultaneous PET/MRI will be best suited for clinical situations that are disease-specific, organ-specific, related to diseases of the children or in those patients undergoing repeated imaging for whom cumulative radiation dose must be kept as low as reasonably achievable. PET/MRI also offers interesting opportunities for use of dual modality probes. Upon clear definition of clinical utility, other important and practical issues related to business operational model, clinical workflow and reimbursement will also be resolved.

  17. MRI Scans - Multiple Languages: MedlinePlus

    MedlinePlus

    ... Resonance Imaging) (Arabic) العربية Bilingual PDF Health Information Translations Chinese - Simplified (简体中文) MRI (Magnetic Resonance Imaging) 核磁共振成像(MRI) - 简体中文 (Chinese - Simplified) Bilingual PDF Health Information Translations Chinese - Traditional (繁體中文) MRI (Magnetic Resonance Imaging) 核磁共振成像( ...

  18. Hepatobiliary MRI: current concepts and controversies.

    PubMed

    Glockner, James F

    2007-04-01

    Evaluation of the liver and biliary system is a frequent indication for abdominal MRI. Hepatobiliary MRI comprises a set of noninvasive techniques that are usually very effective in answering most clinical questions. There are significant limitations, however, as well as considerable variation and disagreement regarding the optimal protocols for standard hepatic MRI and magnetic resonance cholangiopancreaticography (MRCP). This review discusses pulse sequences most often used in hepatic MRI and MRCP, examines a few sources of controversy in the current literature, and summarizes some recent and future developments in the field.

  19. Functional MRI and Outcome in Traumatic Coma

    PubMed Central

    Giacino, Joseph T.; Wu, Ona

    2013-01-01

    Advances in task-based functional MRI (fMRI), resting-state fMRI (rs-fMRI), and arterial-spin labeled (ASL) perfusion MRI have occurred at a rapid pace in recent years. These techniques for measuring brain function have great potential to improve the accuracy of prognostication for civilian and military patients with traumatic coma. In addition, fMRI, rs-fMRI, and ASL have provided novel insights into the pathophysiology of traumatic disorders of consciousness, as well as mechanisms of recovery from coma. However, functional neuroimaging techniques have yet to achieve widespread clinical use as prognostic tests for patients with traumatic coma. Rather, a broad spectrum of methodological hurdles currently limits the feasibility of clinical implementation. In this review, we discuss the basic principles of fMRI, rs-fMRI and ASL and their potential applications as prognostic tools for patients with traumatic coma. We also discuss future strategies for overcoming the current barriers to clinical implementation. PMID:23881623

  20. Distribution of Hyperpolarized Xenon in the Brain Following Sensory Stimulation: Preliminary MRI Findings

    PubMed Central

    Mazzanti, Mary L.; Walvick, Ronn P.; Zhou, Xin; Sun, Yanping; Shah, Niral; Mansour, Joey; Gereige, Jessica; Albert, Mitchell S.

    2011-01-01

    In hyperpolarized xenon magnetic resonance imaging (HP 129Xe MRI), the inhaled spin-1/2 isotope of xenon gas is used to generate the MR signal. Because hyperpolarized xenon is an MR signal source with properties very different from those generated from water-protons, HP 129Xe MRI may yield structural and functional information not detectable by conventional proton-based MRI methods. Here we demonstrate the differential distribution of HP 129Xe in the cerebral cortex of the rat following a pain stimulus evoked in the animal's forepaw. Areas of higher HP 129Xe signal corresponded to those areas previously demonstrated by conventional functional MRI (fMRI) methods as being activated by a forepaw pain stimulus. The percent increase in HP 129Xe signal over baseline was 13–28%, and was detectable with a single set of pre and post stimulus images. Recent innovations in the production of highly polarized 129Xe should make feasible the emergence of HP 129Xe MRI as a viable adjunct method to conventional MRI for the study of brain function and disease. PMID:21789173

  1. Simultaneous measurement of human joint force, surface electromyograms, and functional MRI-measured brain activation.

    PubMed

    Liu, J Z; Dai, T H; Elster, T H; Sahgal, V; Brown, R W; Yue, G H

    2000-08-15

    Functional magnetic resonance imaging (fMRI) has been increasingly used in studying human brain function given its non-invasive feature and good spatial resolution. However, difficulties in acquiring data from peripheral (e.g. information from muscle) during fMRI studies of motor function hinder interpretation of fMRI data and designing more sophisticated investigations. Here we describe a system that was designed to concurrently measure handgrip force, surface electromyograms (EMG) of finger flexor and extensor muscles, and fMRI of human brain. The system included a pressure transducer built in a hydraulic environment, a heavily shielded EMG recording element, and a visual feedback structure for online monitoring of force and/or EMG signal, by the subject positioned in the scanner during an fMRI experiment. System evaluation and subsequent fMRI motor function studies have indicated that by using this system, high quality force and EMG signals can be recorded without sacrificing the quality of the fMRI data. PMID:10967361

  2. Internal Fiducial Markers and Susceptibility Effects in MRI-Simulation and Measurement of Spatial Accuracy

    SciTech Connect

    Jonsson, Joakim H.; Garpebring, Anders; Karlsson, Magnus G.; Nyholm, Tufve

    2012-04-01

    Background: It is well-known that magnetic resonance imaging (MRI) is preferable to computed tomography (CT) in radiotherapy target delineation. To benefit from this, there are two options available: transferring the MRI delineated target volume to the planning CT or performing the treatment planning directly on the MRI study. A precondition for excluding the CT study is the possibility to define internal structures visible on both the planning MRI and on the images used to position the patient at treatment. In prostate cancer radiotherapy, internal gold markers are commonly used, and they are visible on CT, MRI, x-ray, and portal images. The depiction of the markers in MRI are, however, dependent on their shape and orientation relative the main magnetic field because of susceptibility effects. In the present work, these effects are investigated and quantified using both simulations and phantom measurements. Methods and Materials: Software that simulated the magnetic field distortions around user defined geometries of variable susceptibilities was constructed. These magnetic field perturbation maps were then reconstructed to images that were evaluated. The simulation software was validated through phantom measurements of four commercially available gold markers of different shapes and one in-house gold marker. Results: Both simulations and phantom measurements revealed small position deviations of the imaged marker positions relative the actual marker positions (<1 mm). Conclusion: Cylindrical gold markers can be used as internal fiducial markers in MRI.

  3. Day of Injury CT and Late MRI Findings: Cognitive Outcome in a Pediatric Sample with Complicated Mild Traumatic Brain Injury

    PubMed Central

    Jantz, Paul B; Farrer, Thomas J.; Abildskov, Tracy J.; Dennis, Maureen; Gerhardt, Cynthia A.; Rubin, Kenneth H.; Stancin, Terry; Taylor, H. Gerry; Vannatta, Kathryn; Yeates, Keith Owen

    2016-01-01

    Objectives Complicated mild traumatic brain injury (mTBI) or cmTBI is based on the presence of visibly identifiable brain pathology on the day-of-injury computed tomography (CT) scan. In a pediatric sample the relation of DOI CT to late MRI findings and neuropsychological outcome was examined. Methods MRI (> 12 months) was obtained in pediatric cmTBI patients and a sample of orthopedically injured (OI) children. Those children with positive imaging findings (MRI+) were quantitatively compared to those without (MRI-) or with the OI sample. Groups were also compared in neurocognitive outcome from WASI subtests and the WISC-IV Processing Speed Index (PSI), along with the Test of Everyday Attention for Children (TEA-Ch) and a parent-rated behavioral functioning measure (ABAS-II). Results Despite the MRI+ group having significantly more DOI CT findings than the MRI-group, no quantitative differences were found. WASI Vocabulary and Matrix Reasoning scores were significantly lower, but not PSI, TEA-Ch or ABAS-II scores. MRI+ and MRI-groups did not differ on these measures. Conclusions Heterogeneity in the occurrence of MRI-identified focal pathology was not associated with uniform changes in quantitative analyses of brain structure in cmTBI. Increased number of DOI CT abnormalities was associated with lowered neuropsychological performance. PMID:26186038

  4. MRI geometric distortion: Impact on tangential whole-breast IMRT.

    PubMed

    Walker, Amy; Metcalfe, Peter; Liney, Gary; Batumalai, Vikneswary; Dundas, Kylie; Glide-Hurst, Carri; Delaney, Geoff P; Boxer, Miriam; Yap, Mei Ling; Dowling, Jason; Rivest-Henault, David; Pogson, Elise; Holloway, Lois

    2016-01-01

    The purpose of this study was to determine the impact of magnetic resonance imaging (MRI) geometric distortions when using MRI for target delineation and planning for whole-breast, intensity-modulated radiotherapy (IMRT). Residual system distortions and combined systematic and patient-induced distortions are considered. This retrospective study investigated 18 patients who underwent whole-breast external beam radiotherapy, where both CT and MRIs were acquired for treatment planning. Distortion phantoms were imaged on two MRI systems, dedicated to radiotherapy planning (a wide, closed-bore 3T and an open-bore 1T). Patient scans were acquired on the 3T system. To simulate MRI-based planning, distortion maps representing residual system distortions were generated via deform-able registration between phantom CT and MRIs. Patient CT images and structures were altered to match the residual system distortion measured by the phantoms on each scanner. The patient CTs were also registered to the corresponding patient MRI scans, to assess patient and residual system effects. Tangential IMRT plans were generated and optimized on each resulting CT dataset, then propagated to the original patient CT space. The resulting dose distributions were then evalu-ated with respect to the standard clinically acceptable DVH and visual assessment criteria. Maximum residual systematic distortion was measured to be 7.9 mm (95% < 4.7 mm) and 11.9 mm (95% < 4.6 mm) for the 3T and 1T scanners, respectively, which did not result in clinically unacceptable plans. Eight of the plans accounting for patient and systematic distortions were deemed clinically unacceptable when assessed on the original CT. For these plans, the mean difference in PTV V95 (vol-ume receiving 95% prescription dose) was 0.13 ± 2.51% and -0.73 ± 1.93% for right- and left-sided patients, respectively. Residual system distortions alone had minimal impact on the dosimetry for the two scanners investigated. The combina-tion of

  5. MRI of nasopharyngeal adenoid hypertrophy.

    PubMed

    Surov, Alexey; Ryl, Ina; Bartel-Friedrich, Sylvia; Wienke, Andreas; Kösling, Sabrina

    2016-10-01

    Nasopharyngeal adenoid hypertrophy (NAH) is a typical benign lesion. Due to involution, nasopharyngeal lymphatic tissue usually is not found in adults beyond the 30th to 40th year of life. However, occasionally NAH has been recognized after the 50th or 60th year. The aim of this study is to identify the frequency of NAH and to analyze its MRI findings in different age groups. From 2007 to 2011, 6693 MR investigations of the head were performed at our institution. MRI was obtained with a 1.5 T MRI device. NAH was identified in 18.0% of the patients. The frequency of NAH varied from 60.3% to 1.0% in the different age groups. The mean size of NAH was 23.2 ± 4.5 mm in cranio-caudal, 31.1 ± 5.2 mm in left-right, and 14.2 ± 4.1 mm in the anterior-posterior direction. The left-right and cranio-caudal sizes of NAH were largest in the 0-9 age group and decreased with age. On T1-w images most lesions (95.4%) were hypointense in comparison to the adjacent musculature. On T2-w fat-saturated images 82.4% of the lesions were hyperintense. After intravenous administration of contrast medium most lesions showed a slight enhancement (58.6%). Moderate enhancement was seen in 32.4% and a marked enhancement was identified in 9.0%. In the 0-9 age group most lesions showed a slight enhancement. Cysts within NAH were identified in 433 cases (35.9%). The frequency of cysts increased continuously with age, namely from 10.9% to 65.2%.

  6. Functional Imaging: CT and MRI

    PubMed Central

    van Beek, Edwin JR; Hoffman, Eric A

    2008-01-01

    Synopsis Numerous imaging techniques permit evaluation of regional pulmonary function. Contrast-enhanced CT methods now allow assessment of vasculature and lung perfusion. Techniques using spirometric controlled MDCT allow for quantification of presence and distribution of parenchymal and airway pathology, Xenon gas can be employed to assess regional ventilation of the lungs and rapid bolus injections of iodinated contrast agent can provide quantitative measure of regional parenchymal perfusion. Advances in magnetic resonance imaging (MRI) of the lung include gadolinium-enhanced perfusion imaging and hyperpolarized helium imaging, which can allow imaging of pulmonary ventilation and .measurement of the size of emphysematous spaces. PMID:18267192

  7. 4D flow imaging with MRI

    PubMed Central

    Stankovic, Zoran; Allen, Bradley D.; Garcia, Julio; Jarvis, Kelly B.

    2014-01-01

    Magnetic resonance imaging (MRI) has become an important tool for the clinical evaluation of patients with cardiovascular disease. Since its introduction in the late 1980s, 2-dimensional phase contrast MRI (2D PC-MRI) has become a routine part of standard-of-care cardiac MRI for the assessment of regional blood flow in the heart and great vessels. More recently, time-resolved PC-MRI with velocity encoding along all three flow directions and three-dimensional (3D) anatomic coverage (also termed ‘4D flow MRI’) has been developed and applied for the evaluation of cardiovascular hemodynamics in multiple regions of the human body. 4D flow MRI allows for the comprehensive evaluation of complex blood flow patterns by 3D blood flow visualization and flexible retrospective quantification of flow parameters. Recent technical developments, including the utilization of advanced parallel imaging techniques such as k-t GRAPPA, have resulted in reasonable overall scan times, e.g., 8-12 minutes for 4D flow MRI of the aorta and 10-20 minutes for whole heart coverage. As a result, the application of 4D flow MRI in a clinical setting has become more feasible, as documented by an increased number of recent reports on the utility of the technique for the assessment of cardiac and vascular hemodynamics in patient studies. A number of studies have demonstrated the potential of 4D flow MRI to provide an improved assessment of hemodynamics which might aid in the diagnosis and therapeutic management of cardiovascular diseases. The purpose of this review is to describe the methods used for 4D flow MRI acquisition, post-processing and data analysis. In addition, the article provides an overview of the clinical applications of 4D flow MRI and includes a review of applications in the heart, thoracic aorta and hepatic system. PMID:24834414

  8. Multiple-exchange-time xenon polarization transfer contrast (MXTC) MRI: initial results in animals and healthy volunteers.

    PubMed

    Dregely, Isabel; Ruset, Iulian C; Mata, Jaime F; Ketel, Jeffrey; Ketel, Steve; Distelbrink, Jan; Altes, Talissa A; Mugler, John P; Wilson Miller, G; William Hersman, F; Ruppert, Kai

    2012-04-01

    Hyperpolarized xenon-129 is a noninvasive contrast agent for lung MRI, which upon inhalation dissolves in parenchymal structures, thus mirroring the gas-exchange process for oxygen in the lung. Multiple-exchange-time xenon polarization transfer contrast (MXTC) MRI is an implementation of the XTC MRI technique in four dimensions (three spatial dimensions plus exchange time). The aim of this study was to evaluate the sensitivity of MXTC MRI for the detection of microstructural deformations of the healthy lung in response to gravity-induced tissue compression and the degree of lung inflation. MXTC MRI was performed in four rabbits and in three healthy human volunteers. Two lung function parameters, one related to tissue- to alveolar-volume ratio and the other to average septal-wall thickness, were determined regionally. A significant gradient in MXTC MRI parameters, consistent with gravity-induced lung tissue deformation in the supine imaging position, was found at low lung volumes. At high lung volumes, parameters were generally lower and the gradient in parameter values was less pronounced. Results show that MXTC MRI permits the quantification of subtle changes in healthy lung microstructure. Further, only structures participating in gas exchange are represented in MXTC MRI data, which potentially makes the technique especially sensitive to pathological changes in lung microstructure affecting gas exchange.

  9. A diffusion tensor MRI atlas of the postmortem rhesus macaque brain.

    PubMed

    Calabrese, Evan; Badea, Alexandra; Coe, Christopher L; Lubach, Gabriele R; Shi, Yundi; Styner, Martin A; Johnson, G Allan

    2015-08-15

    The rhesus macaque (Macaca mulatta) is the most widely used nonhuman primate for modeling the structure and function of the brain. Brain atlases, and particularly those based on magnetic resonance imaging (MRI), have become important tools for understanding normal brain structure, and for identifying structural abnormalities resulting from disease states, exposures, and/or aging. Diffusion tensor imaging (DTI)-based MRI brain atlases are widely used in both human and macaque brain imaging studies because of the unique contrasts, quantitative diffusion metrics, and diffusion tractography that they can provide. Previous MRI and DTI atlases of the rhesus brain have been limited by low contrast and/or low spatial resolution imaging. Here we present a microscopic resolution MRI/DTI atlas of the rhesus brain based on 10 postmortem brain specimens. The atlas includes both structural MRI and DTI image data, a detailed three-dimensional segmentation of 241 anatomic structures, diffusion tractography, cortical thickness estimates, and maps of anatomic variability among atlas specimens. This atlas incorporates many useful features from previous work, including anatomic label nomenclature and ontology, data orientation, and stereotaxic reference frame, and further extends prior analyses with the inclusion of high-resolution multi-contrast image data.

  10. Novel Imaging of Prostate Cancer with MRI, MRI/US, and PET.

    PubMed

    Koo, Phillip J; Kwak, Jennifer J; Pokharel, Sajal; Choyke, Peter L

    2015-12-01

    Imaging of prostate cancer presents many challenges to the imaging community. There has been much progress in this space in large part due to MRI and PET radiopharmaceuticals. Though MRI has been focused on the evaluation of local disease and PET on the detection of metastatic disease, these two areas do converge and will be complementary especially with the growth of new PET/MRI technologies. In this review article, we review novel MRI, MRI/US, and PET radiopharmaceuticals which will offer insight into the future direction of imaging in prostate cancer.

  11. Novel Imaging of Prostate Cancer with MRI, MRI/US, and PET.

    PubMed

    Koo, Phillip J; Kwak, Jennifer J; Pokharel, Sajal; Choyke, Peter L

    2015-12-01

    Imaging of prostate cancer presents many challenges to the imaging community. There has been much progress in this space in large part due to MRI and PET radiopharmaceuticals. Though MRI has been focused on the evaluation of local disease and PET on the detection of metastatic disease, these two areas do converge and will be complementary especially with the growth of new PET/MRI technologies. In this review article, we review novel MRI, MRI/US, and PET radiopharmaceuticals which will offer insight into the future direction of imaging in prostate cancer. PMID:26462919

  12. Multiwall carbon nanotubes as MRI contrast agents for tracking stem cells

    NASA Astrophysics Data System (ADS)

    Vittorio, Orazio; Duce, Suzanne L.; Pietrabissa, Andrea; Cuschieri, Alfred

    2011-03-01

    In this study we investigate the potential of multiwall carbon nanotubes (MWCNTs) with low metal impurities (2.57% iron) as magnetic resonance imaging (MRI) contrast agents. Taking into account probable aggregation at high MWCNTs concentration analysis shows that the r2 relaxivity of MWCNTs in 1% agarose gels at 19 °C is 564 ± 41 s - 1 mM - 1; this is attributed to both the presence of iron oxide impurities and also to the carbon MWCNT structure itself. Stem cells were labelled with MWCNTs to demonstrate the effectiveness of MWCNTs as MRI contrast agents for cellular MRI. The MWCNTs did not impair cell viability or proliferation. These results suggest that the MRI contrast agent properties of the MWCNTs could be used in vivo for stem cell tracking/imaging and during MWCNT-mediated targeted electro-chemotherapy of tumours.

  13. Physics of MRI: a primer.

    PubMed

    Plewes, Donald B; Kucharczyk, Walter

    2012-05-01

    This article is based on an introductory lecture given for the past many years during the "MR Physics and Techniques for Clinicians" course at the Annual Meeting of the ISMRM. This introduction is not intended to be a comprehensive overview of the field, as the subject of magnetic resonance imaging (MRI) physics is large and complex. Rather, it is intended to lay a conceptual foundation by which magnetic resonance image formation can be understood from an intuitive perspective. The presentation is nonmathematical, relying on simple models that take the reader progressively from the basic spin physics of nuclei, through descriptions of how the magnetic resonance signal is generated and detected in an MRI scanner, the foundations of nuclear magnetic resonance (NMR) relaxation, and a discussion of the Fourier transform and its relation to MR image formation. The article continues with a discussion of how magnetic field gradients are used to facilitate spatial encoding and concludes with a development of basic pulse sequences and the factors defining image contrast.

  14. MRI-conditional pacemakers: current perspectives

    PubMed Central

    Ferreira, António M; Costa, Francisco; Tralhão, António; Marques, Hugo; Cardim, Nuno; Adragão, Pedro

    2014-01-01

    Use of both magnetic resonance imaging (MRI) and pacing devices has undergone remarkable growth in recent years, and it is estimated that the majority of patients with pacemakers will need an MRI during their lifetime. These investigations will generally be denied due to the potentially dangerous interactions between cardiac devices and the magnetic fields and radio frequency energy used in MRI. Despite the increasing reports of uneventful scanning in selected patients with conventional pacemakers under close surveillance, MRI is still contraindicated in those circumstances and cannot be considered a routine procedure. These limitations prompted a series of modifications in generator and lead engineering, designed to minimize interactions that could compromise device function and patient safety. The resulting MRI-conditional pacemakers were first introduced in 2008 and the clinical experience gathered so far supports their safety in the MRI environment if certain conditions are fulfilled. With this technology, new questions and controversies arise regarding patient selection, clinical impact, and cost-effectiveness. In this review, we discuss the potential risks of MRI in patients with electronic cardiac devices and present updated information regarding the features of MRI-conditional pacemakers and the clinical experience with currently available models. Finally, we provide some guidance on how to scan patients who have these devices and discuss future directions in the field. PMID:24851058

  15. MRI endoscopy using intrinsically localized probes

    PubMed Central

    Sathyanarayana, Shashank; Bottomley, Paul A.

    2009-01-01

    Magnetic resonance imaging (MRI) is traditionally performed with fixed externally applied gradient magnetic fields and is hence intrinsically locked to the laboratory frame of reference (FoR). Here a method for high-resolution MRI that employs active, catheter-based, tiny internal probes that utilize the spatial properties of the probe itself for localization is proposed and demonstrated at 3 T. Because these properties are intrinsic to the probe, they move with it, transforming MRI from the laboratory FoR to the FoR of the device itself, analogous to an endoscope. The “MRI endoscope” can utilize loop coils and loopless antennas with modified sensitivity, in combination with adiabatic excitation by the device itself, to restrict the MRI sensitivity to a disk-shaped plane a few mm thick. Excitation with the MRI endoscope limits the eddy currents induced in the sample to an excited volume whose size is orders of magnitude below that excited by a conventional body MRI coil. Heat testing shows maximum local temperature increases of <1 °C during MRI, within regulatory guidelines. The method is demonstrated in a kiwifruit, in intact porcine and rabbit aortas, and in an atherosclerotic human iliac artery specimen, with in-plane resolution as small as 80 μm and 1.5–5 mm slice thickness. PMID:19378751

  16. High-performance computing MRI simulations.

    PubMed

    Stöcker, Tony; Vahedipour, Kaveh; Pflugfelder, Daniel; Shah, N Jon

    2010-07-01

    A new open-source software project is presented, JEMRIS, the Jülich Extensible MRI Simulator, which provides an MRI sequence development and simulation environment for the MRI community. The development was driven by the desire to achieve generality of simulated three-dimensional MRI experiments reflecting modern MRI systems hardware. The accompanying computational burden is overcome by means of parallel computing. Many aspects are covered that have not hitherto been simultaneously investigated in general MRI simulations such as parallel transmit and receive, important off-resonance effects, nonlinear gradients, and arbitrary spatiotemporal parameter variations at different levels. The latter can be used to simulate various types of motion, for instance. The JEMRIS user interface is very simple to use, but nevertheless it presents few limitations. MRI sequences with arbitrary waveforms and complex interdependent modules are modeled in a graphical user interface-based environment requiring no further programming. This manuscript describes the concepts, methods, and performance of the software. Examples of novel simulation results in active fields of MRI research are given.

  17. Pantopaque simulating thrombosed intracranial aneurysms on MRI

    SciTech Connect

    Lidov, M.W.; Silvers, A.R.; Mosesson, R.E.; Stollman, A.L.; Som, P.M.

    1996-03-01

    A patient is presented in whom iophendylate (Pantopaque) within the basal cisterns closely resembled the appearance on MRI of thrombosed aneurysms of the middle cerebral arteries. The sometimes subtle differences between the appearances on MRI of Pantopaque and aneurysmal clot are discussed to permit accurate diagnosis without resorting to more invasive diagnostic tests, such as cerebral angiography. 5 refs., 4 figs.

  18. Cranial computed tomography and MRI. Second edition

    SciTech Connect

    Lee, S.H.; Rao, K.C.V.G.

    1987-01-01

    This book contains 17 chapters. Some of the chapter titles are: Physics and Instrumentation: CT and MRI; Normal Cranial CT and MRI Anatomy; The Orbit; The ventricles and Subarachnoid Spaces in Children; Primary Tumors in Children; Trauma: Craniocerebral and Craniofacial; Infectious Disease; and Stroke.

  19. Functional MRI in investigating cognitive impairment in multiple sclerosis.

    PubMed

    Rocca, M A; De Meo, E; Filippi, M

    2016-09-01

    There is increasing evidence that the severity of the clinical manifestations of multiple sclerosis (MS) does not simply result from the extent of tissue destruction, but it rather represents a complex balance between tissue damage, tissue repair, and cortical reorganization. Functional magnetic resonance imaging (fMRI) provides information about the plasticity of the human brain. Therefore, it has the potential to provide important pieces of information about brain reorganization following MS-related structural damage. When investigating cognitive systems, fMRI changes have been described in virtually all patients with MS and different clinical phenotypes. These functional changes have been related to the extent of brain damage within and outside T2-visible lesions as well as to the involvement of specific central nervous system structures. It has also been suggested that a maladaptive recruitment of specific brain regions might be associated with the appearance of clinical symptoms in MS, such as fatigue and cognitive impairment. fMRI studies from clinically (and cognitively) impaired MS patients may be influenced by different task performances between patients and controls. As a consequence, new strategies have been introduced to assess the role, if any, of brain reorganization in severely impaired patients, including the analysis of resting-state networks. The enhancement of any beneficial effects of this brain adaptive plasticity should be considered as a potential target of therapy for MS. PMID:27580905

  20. MRI parcellation of ex vivo medial temporal lobe.

    PubMed

    Augustinack, Jean C; Magnain, Caroline; Reuter, Martin; van der Kouwe, André J W; Boas, David; Fischl, Bruce

    2014-06-01

    Recent advancements in radio frequency coils, field strength and sophisticated pulse sequences have propelled modern brain mapping and have made validation to biological standards - histology and pathology - possible. The medial temporal lobe has long been established as a pivotal brain region for connectivity, function and unique structure in the human brain, and reveals disconnection in mild Alzheimer's disease. Specific brain mapping of mesocortical areas affected with neurofibrillary tangle pathology early in disease progression provides not only an accurate description for location of these areas but also supplies spherical coordinates that allow comparison between other ex vivo cases and larger in vivo datasets. We have identified several cytoarchitectonic features in the medial temporal lobe with high resolution ex vivo MRI, including gray matter structures such as the entorhinal layer II 'islands', perirhinal layer II-III columns, presubicular 'clouds', granule cell layer of the dentate gyrus as well as lamina of the hippocampus. Localization of Brodmann areas 28 and 35 (entorhinal and perirhinal, respectively) demonstrates MRI based area boundaries validated with multiple methods and histological stains. Based on our findings, both myelin and Nissl staining relate to contrast in ex vivo MRI. Precise brain mapping serves to create modern atlases for cortical areas, allowing accurate localization with important applications to detecting early disease processes.

  1. MRI parcellation of ex vivo medial temporal lobe.

    PubMed

    Augustinack, Jean C; Magnain, Caroline; Reuter, Martin; van der Kouwe, André J W; Boas, David; Fischl, Bruce

    2014-06-01

    Recent advancements in radio frequency coils, field strength and sophisticated pulse sequences have propelled modern brain mapping and have made validation to biological standards - histology and pathology - possible. The medial temporal lobe has long been established as a pivotal brain region for connectivity, function and unique structure in the human brain, and reveals disconnection in mild Alzheimer's disease. Specific brain mapping of mesocortical areas affected with neurofibrillary tangle pathology early in disease progression provides not only an accurate description for location of these areas but also supplies spherical coordinates that allow comparison between other ex vivo cases and larger in vivo datasets. We have identified several cytoarchitectonic features in the medial temporal lobe with high resolution ex vivo MRI, including gray matter structures such as the entorhinal layer II 'islands', perirhinal layer II-III columns, presubicular 'clouds', granule cell layer of the dentate gyrus as well as lamina of the hippocampus. Localization of Brodmann areas 28 and 35 (entorhinal and perirhinal, respectively) demonstrates MRI based area boundaries validated with multiple methods and histological stains. Based on our findings, both myelin and Nissl staining relate to contrast in ex vivo MRI. Precise brain mapping serves to create modern atlases for cortical areas, allowing accurate localization with important applications to detecting early disease processes. PMID:23702414

  2. Statistical shape model-based segmentation of brain MRI images.

    PubMed

    Bailleul, Jonathan; Ruan, Su; Constans, Jean-Marc

    2007-01-01

    We propose a segmentation method that automatically delineates structures contours from 3D brain MRI images using a statistical shape model. We automatically build this 3D Point Distribution Model (PDM) in applying a Minimum Description Length (MDL) annotation to a training set of shapes, obtained by registration of a 3D anatomical atlas over a set of patients brain MRIs. Delineation of any structure from a new MRI image is first initialized by such registration. Then, delineation is achieved in iterating two consecutive steps until the 3D contour reaches idempotence. The first step consists in applying an intensity model to the latest shape position so as to formulate a closer guess: our model requires far less priors than standard model in aiming at direct interpretation rather than compliance to learned contexts. The second step consists in enforcing shape constraints onto previous guess so as to remove all bias induced by artifacts or low contrast on current MRI. For this, we infer the closest shape instance from the PDM shape space using a new estimation method which accuracy is significantly improved by a huge increase in the model resolution and by a depth-search in the parameter space. The delineation results we obtained are very encouraging and show the interest of the proposed framework. PMID:18003193

  3. Anisotropic Smoothing Improves DT-MRI-Based Muscle Fiber Tractography

    PubMed Central

    Buck, Amanda K. W.; Ding, Zhaohua; Elder, Christopher P.; Towse, Theodore F.; Damon, Bruce M.

    2015-01-01

    Purpose To assess the effect of anisotropic smoothing on fiber tracking measures, including pennation angle, fiber tract length, and fiber tract number in the medial gastrocnemius (MG) muscle in healthy subjects using diffusion-weighted magnetic resonance imaging (DW-MRI). Materials and Methods 3T DW-MRI data were used for muscle fiber tractography in the MG of healthy subjects. Anisotropic smoothing was applied at three levels (5%, 10%, 15%), and pennation angle, tract length, fiber tract number, fractional anisotropy, and principal eigenvector orientation were quantified for each smoothing level. Results Fiber tract length increased with pre-fiber tracking smoothing, and local heterogeneities in fiber direction were reduced. However, pennation angle was not affected by smoothing. Conclusion Modest anisotropic smoothing (10%) improved fiber-tracking results, while preserving structural features. PMID:26010830

  4. [MRI and CT in the evaluation of congenital heart diseases].

    PubMed

    Secchi, F; Giardino, A; Nardella, V G; Sardanelli, F

    2010-01-01

    Magnetic resonance imaging (MRI) allows a static and cinetic study of congenital heart diseases avoiding patient exposure to ionizing radiation. It allows for evaluating cardiac morphology, heart function with accurate ventricular volume estimation, flow quantification with gradient and regurgitant fraction estimation, and vascular anatomy (aortic, pulmonary and proximal coronary vessels). Computed tomography (CT), with greater spatial resolution, allows for evaluating proximal and distal coronary arteries, vascular and pericardial calcifications, metal structures such as stents and prosthetic valves. The use of MRI or CT in young and adult patients with congenital heart diseases should be assessed case by case through a close collaboration between cardiologists and radiologists, aiming at an optimal tradeoff between expected diagnostic gain and biological cost in terms of ionizing radiation exposure and contrast material administration.

  5. Non-local MRI denoising using random sampling.

    PubMed

    Hu, Jinrong; Zhou, Jiliu; Wu, Xi

    2016-09-01

    In this paper, we propose a random sampling non-local mean (SNLM) algorithm to eliminate noise in 3D MRI datasets. Non-local means (NLM) algorithms have been implemented efficiently for MRI denoising, but are always limited by high computational complexity. Compared to conventional methods, which raster through the entire search window when computing similarity weights, the proposed SNLM algorithm randomly selects a small subset of voxels which dramatically decreases the computational burden, together with competitive denoising result. Moreover, structure tensor which encapsulates high-order information was introduced as an optimal sampling pattern for further improvement. Numerical experiments demonstrated that the proposed SNLM method can get a good balance between denoising quality and computation efficiency. At a relative sampling ratio (i.e. ξ=0.05), SNLM can remove noise as effectively as full NLM, meanwhile the running time can be reduced to 1/20 of NLM's. PMID:27114338

  6. MRI of Perianal Fistulas: Bridging the radiologic-surgical divide

    PubMed Central

    Gage, Kenneth L.; Deshmukh, Swati; Macura, Katarzyna J.; Kamel, Ihab R.; Zaheer, Atif

    2013-01-01

    Perianal fistula is a clinical entity with multiple surgical treatment options. Recently, magnetic resonance imaging (MRI) has emerged as an important imaging modality in the management of perianal fistulas. It provides accurate description of the fistula within the anal canal in relation to the sphincter complex and other pelvic floor structures as well as the associated complications such as abscess. By understanding the surgical viewpoint, the appearance of perianal fistulas, associated complications, and post-treatment findings of commonly used surgical interventions can more accurately be interpreted to aid clinicians. The objective of the article is to review MRI indications and findings, radiological versus surgical classification schemes, and surgical treatment options for perianal fistulas. PMID:23242265

  7. MRI of anal cancer: assessing response to definitive chemoradiotherapy.

    PubMed

    Gourtsoyianni, S; Goh, V

    2014-02-01

    Anal cancer is an uncommon malignancy of the gastrointestinal tract but has a relatively good prognosis with an 80% 5-year overall survival. In this article, we review the role of MRI for assessing treatment response in anal cancer after completion of definitive chemoradiotherapy. New generation MRI scanners with optimal-phased array body coils, resulting in better signal to noise and improved contrast and spatial resolution, have contributed to high-resolution imaging in clinical practice enabling visualization of relevant anatomy including the sphincter complex, adjacent structures, mesorectal and pelvic lymph nodes with a diameter down to 2 mm. Multiplanar, high-resolution T2-weighted and diffusion-weighted sequences have a role in initial locoregional staging of anal SCC, assisting radiotherapy planning, as well as in assessing response to treatment and treatment-related complications. PMID:24072381

  8. Perspectives on Porous Media MR in Clinical MRI

    NASA Astrophysics Data System (ADS)

    Sigmund, E. E.

    2011-03-01

    Many goals and challenges of research in natural or synthetic porous media are mirrored in quantitative medical MRI. This review will describe examples where MR techniques used in porous media (particularly diffusion-weighted imaging (DWI)) are applied to physiological pathologies. Tissue microstructure is one area with great overlap with porous media science. Diffusion-weighting (esp. in neurological tissue) has motivated models with explicit physical dimensions, statistical parameters, empirical descriptors, or hybrids thereof. Another clinically relevant microscopic process is active flow. Renal (kidney) tissue possesses significant active vascular / tubular transport that manifests as "pseudodiffusion." Cancerous lesions involve anomalies in both structure and flow. The tools of magnetic resonance and their interpretation in porous media has had great impact on clinical MRI, and continued cross-fertilization of ideas can only enhance the progress of both fields.

  9. Interactive MRI Segmentation with Controlled Active Vision

    PubMed Central

    Karasev, Peter; Kolesov, Ivan; Chudy, Karol; Muller, Grant; Xerogeanes, John; Tannenbaum, Allen

    2013-01-01

    Partitioning Magnetic-Resonance-Imaging (MRI) data into salient anatomic structures is a problem in medical imaging that has continued to elude fully automated solutions. Implicit functions are a common way to model the boundaries between structures and are amenable to control-theoretic methods. In this paper, the goal of enabling a human to obtain accurate segmentations in a short amount of time and with little effort is transformed into a control synthesis problem. Perturbing the state and dynamics of an implicit function’s driving partial differential equation via the accumulated user inputs and an observer-like system leads to desirable closed-loop behavior. Using a Lyapunov control design, a balance is established between the influence of a data-driven gradient flow and the human’s input over time. Automatic segmentation is thus smoothly coupled with interactivity. An application of the mathematical methods to orthopedic segmentation is shown, demonstrating the expected transient and steady state behavior of the implicit segmentation function and auxiliary observer. PMID:24584213

  10. Dosimetric evaluation of MRI-based treatment planning for prostate cancer

    NASA Astrophysics Data System (ADS)

    Chen, L.; Price, R. A., Jr.; Nguyen, T.-B.; Wang, L.; Li, J. S.; Qin, L.; Ding, M.; Palacio, E.; Ma, C.-M.; Pollack, A.

    2004-11-01

    The purpose of this study is to evaluate the dosimetric accuracy of MRI-based treatment planning for prostate cancer using a commercial radiotherapy treatment planning system. Three-dimensional conformal plans for 15 prostate patients were generated using the AcQPlan system. For each patient, dose distributions were calculated using patient CT data with and without heterogeneity correction, and using patient MRI data without heterogeneity correction. MR images were post-processed using the gradient distortion correction (GDC) software. The distortion corrected MR images were fused to the corresponding CT for each patient for target and structure delineation. The femoral heads were delineated based on CT. Other anatomic structures relevant to the treatment (i.e., prostate, seminal vesicles, lymph notes, rectum and bladder) were delineated based on MRI. The external contours were drawn separately on CT and MRI. The same internal contours were used in the dose calculation using CT- and MRI-based geometries by directly transferring them between MRI and CT as needed. Treatment plans were evaluated based on maximum dose, isodose distributions and dose-volume histograms. The results confirm previous investigations that there is no clinically significant dose difference between CT-based prostate plans with and without heterogeneity correction. The difference in the target dose between CT- and MRI-based plans using homogeneous geometry was within 2.5%. Our results suggest that MRI-based treatment planning is suitable for radiotherapy of prostate cancer. The materials in this paper have been presented in part at the San Diego 2003 AAPM.

  11. Integrating histology and MRI in the first digital brain of common squirrel monkey, Saimiri sciureus

    PubMed Central

    Sun, Peizhen; Parvathaneni, Prasanna; Schilling, Kurt G.; Gao, Yurui; Janve, Vaibhav; Anderson, Adam; Landman, Bennett A.

    2015-01-01

    This effort is a continuation of development of a digital brain atlas of the common squirrel monkey, Saimiri sciureus, a New World monkey with functional and microstructural organization of central nervous system similar to that of humans. Here, we present the integration of histology with multi-modal magnetic resonance imaging (MRI) atlas constructed from the brain of an adult female squirrel monkey. The central concept of this work is to use block face photography to establish an intermediate common space in coordinate system which preserves the high resolution in-plane resolution of histology while enabling 3-D correspondence with MRI. In vivo MRI acquisitions include high resolution T2 structural imaging (300 µm isotropic) and low resolution diffusion tensor imaging (600 um isotropic). Ex vivo MRI acquisitions include high resolution T2 structural imaging and high resolution diffusion tensor imaging (both 300 µm isotropic). Cortical regions were manually annotated on the co-registered volumes based on published histological sections in-plane. We describe mapping of histology and MRI based data of the common squirrel monkey and construction of a viewing tool that enable online viewing of these datasets. The previously descried atlas MRI is used for its deformation to provide accurate conformation to the MRI, thus adding information at the histological level to the MRI volume. This paper presents the mapping of single 2D image slice in block face as a proof of concept and this can be extended to map the atlas space in 3D coordinate system as part of the future work and can be loaded to an XNAT system for further use. PMID:25914510

  12. Integrating histology and MRI in the first digital brain of common squirrel monkey, Saimiri sciureus

    NASA Astrophysics Data System (ADS)

    Sun, Peizhen; Parvathaneni, Prasanna; Schilling, Kurt G.; Gao, Yurui; Janve, Vaibhav; Anderson, Adam; Landman, Bennett A.

    2015-03-01

    This effort is a continuation of development of a digital brain atlas of the common squirrel monkey, Saimiri sciureus, a New World monkey with functional and microstructural organization of central nervous system similar to that of humans. Here, we present the integration of histology with multi-modal magnetic resonance imaging (MRI) atlas constructed from the brain of an adult female squirrel monkey. The central concept of this work is to use block face photography to establish an intermediate common space in coordinate system which preserves the high resolution in-plane resolution of histology while enabling 3-D correspondence with MRI. In vivo MRI acquisitions include high resolution T2 structural imaging (300 μm isotropic) and low resolution diffusion tensor imaging (600 um isotropic). Ex vivo MRI acquisitions include high resolution T2 structural imaging and high resolution diffusion tensor imaging (both 300 μm isotropic). Cortical regions were manually annotated on the co-registered volumes based on published histological sections in-plane. We describe mapping of histology and MRI based data of the common squirrel monkey and construction of a viewing tool that enable online viewing of these datasets. The previously descried atlas MRI is used for its deformation to provide accurate conformation to the MRI, thus adding information at the histological level to the MRI volume. This paper presents the mapping of single 2D image slice in block face as a proof of concept and this can be extended to map the atlas space in 3D coordinate system as part of the future work and can be loaded to an XNAT system for further use.

  13. NMR, MRI, and spectroscopic MRI in inhomogeneous fields

    DOEpatents

    Demas, Vasiliki; Pines, Alexander; Martin, Rachel W; Franck, John; Reimer, Jeffrey A

    2013-12-24

    A method for locally creating effectively homogeneous or "clean" magnetic field gradients (of high uniformity) for imaging (with NMR, MRI, or spectroscopic MRI) both in in-situ and ex-situ systems with high degrees of inhomogeneous field strength. THe method of imaging comprises: a) providing a functional approximation of an inhomogeneous static magnetic field strength B.sub.0({right arrow over (r)}) at a spatial position {right arrow over (r)}; b) providing a temporal functional approximation of {right arrow over (G)}.sub.shim(t) with i basis functions and j variables for each basis function, resulting in v.sub.ij variables; c) providing a measured value .OMEGA., which is an temporally accumulated dephasing due to the inhomogeneities of B.sub.0({right arrow over(r)}); and d) minimizing a difference in the local dephasing angle .phi.({right arrow over (r)},t)=.gamma..intg..sub.0.sup.t{square root over (|{right arrow over (B)}.sub.1({right arrow over (r)},t')|.sup.2+({right arrow over (r)}{right arrow over (G)}.sub.shimG.sub.shim(t')+.parallel.{right arrow over (B)}.sub.0({right arrow over (r)}).parallel..DELTA..omega.({right arrow over (r)},t'/.gamma/).sup.2)}dt'-.OMEGA. by varying the v.sub.ij variables to form a set of minimized v.sub.ij variables. The method requires calibration of the static fields prior to minimization, but may thereafter be implemented without such calibration, may be used in open or closed systems, and potentially portable systems.

  14. Multimodal MRI and (31)P-MRS investigations of the ACTA1(Asp286Gly) mouse model of nemaline myopathy provide evidence of impaired in vivo muscle function, altered muscle structure and disturbed energy metabolism.

    PubMed

    Gineste, Charlotte; Duhamel, Guillaume; Le Fur, Yann; Vilmen, Christophe; Cozzone, Patrick J; Nowak, Kristen J; Bendahan, David; Gondin, Julien

    2013-01-01

    Nemaline myopathy (NM), the most common non-dystrophic congenital disease of skeletal muscle, can be caused by mutations in the skeletal muscle α-actin gene (ACTA1) (~25% of all NM cases and up to 50% of severe forms of NM). Muscle function of the recently generated transgenic mouse model carrying the human Asp286Gly mutation in the ACTA1 gene (Tg(ACTA1)(Asp286Gly)) has been mainly investigated in vitro. Therefore, we aimed at providing a comprehensive picture of the in vivo hindlimb muscle function of Tg(ACTA1)(Asp286Gly) mice by combining strictly noninvasive investigations. Skeletal muscle anatomy (hindlimb muscles, intramuscular fat volumes) and microstructure were studied using multimodal magnetic resonance imaging (Dixon, T2, Diffusion Tensor Imaging [DTI]). Energy metabolism was studied using 31-phosphorus Magnetic Resonance Spectroscopy ((31)P-MRS). Skeletal muscle contractile performance was investigated while applying a force-frequency protocol (1-150 Hz) and a fatigue protocol (6 min-1.7 Hz). Tg(ACTA1)(Asp286Gly) mice showed a mild muscle weakness as illustrated by the reduction of both absolute (30%) and specific (15%) maximal force production. Dixon MRI did not show discernable fatty infiltration in Tg(ACTA1)(Asp286Gly) mice indicating that this mouse model does not reproduce human MRI findings. Increased T2 values were observed in Tg(ACTA1)(Asp286Gly) mice and might reflect the occurrence of muscle degeneration/regeneration process. Interestingly, T2 values were linearly related to muscle weakness. DTI experiments indicated lower λ2 and λ3 values in Tg(ACTA1)(Asp286Gly) mice, which might be associated to muscle atrophy and/or the presence of histological anomalies. Finally (31)P-MRS investigations illustrated an increased anaerobic energy cost of contraction in Tg(ACTA1)(Asp286Gly) mice, which might be ascribed to contractile and non-contractile processes. Overall, we provide a unique set of information about the anatomic, metabolic and functional

  15. Three-dimensional liver motion tracking using real-time two-dimensional MRI

    SciTech Connect

    Brix, Lau; Ringgaard, Steffen; Sørensen, Thomas Sangild; Poulsen, Per Rugaard

    2014-04-15

    Purpose: Combined magnetic resonance imaging (MRI) systems and linear accelerators for radiotherapy (MR-Linacs) are currently under development. MRI is noninvasive and nonionizing and can produce images with high soft tissue contrast. However, new tracking methods are required to obtain fast real-time spatial target localization. This study develops and evaluates a method for tracking three-dimensional (3D) respiratory liver motion in two-dimensional (2D) real-time MRI image series with high temporal and spatial resolution. Methods: The proposed method for 3D tracking in 2D real-time MRI series has three steps: (1) Recording of a 3D MRI scan and selection of a blood vessel (or tumor) structure to be tracked in subsequent 2D MRI series. (2) Generation of a library of 2D image templates oriented parallel to the 2D MRI image series by reslicing and resampling the 3D MRI scan. (3) 3D tracking of the selected structure in each real-time 2D image by finding the template and template position that yield the highest normalized cross correlation coefficient with the image. Since the tracked structure has a known 3D position relative to each template, the selection and 2D localization of a specific template translates into quantification of both the through-plane and in-plane position of the structure. As a proof of principle, 3D tracking of liver blood vessel structures was performed in five healthy volunteers in two 5.4 Hz axial, sagittal, and coronal real-time 2D MRI series of 30 s duration. In each 2D MRI series, the 3D localization was carried out twice, using nonoverlapping template libraries, which resulted in a total of 12 estimated 3D trajectories per volunteer. Validation tests carried out to support the tracking algorithm included quantification of the breathing induced 3D liver motion and liver motion directionality for the volunteers, and comparison of 2D MRI estimated positions of a structure in a watermelon with the actual positions. Results: Axial, sagittal

  16. Hippocampal Volumetry and Memory fMRI in Temporal Lobe Epilepsy

    PubMed Central

    Mechanic-Hamilton, Dawn; Korczykowski, Marc; Yushkevich, Paul A.; Lawler, Kathy; Pluta, John; Glynn, Simon; Tracy, Joseph I.; Wolf, Ronald L.; Sperling, Michael R.; French, Jacqueline A.; Detre, John A.

    2009-01-01

    This study examined the utility of structural and functional MRI at 1.5 and 3 Tesla (T) in the pre-surgical evaluation and prediction of post-surgical cognitive outcome in temporal lobe epilepsy (TLE). Forty-nine patients undergoing presurgical evaluation for temporal lobe (TL) resection and twenty-five control subjects were studied. Patients completed standard pre-surgical evaluations including, intracarotid amobarbital test (IAT) and neuropsychological testing. During functional imaging, subjects performed a complex visual scene-encoding task. High-resolution structural MRI scans were used to quantify hippocampal volumes. Both structural and functional imaging successfully lateralized the seizure focus and correlated with IAT memory lateralization, with improvement for functional imaging at 3T as compared to 1.5T. Ipsilateral structural and functional MRI data was related to cognitive outcome and greater functional asymmetry was related to earlier age of onset. These findings support continued investigation of the utility of MRI and fMRI in the presurgical evaluation of TLE. PMID:19674939

  17. Midbrain volume predicts fMRI and ERP measures of reward reactivity.

    PubMed

    Carlson, Joshua M; Foti, Dan; Harmon-Jones, Eddie; Proudfit, Greg H

    2015-01-01

    Ventral striatal activation measured with functional magnetic resonance imaging (fMRI) and feedback negativity amplitude measured with event-related potentials (ERPs) are each enhanced during reward processing. Recent research has found that these two neural measures of reward processing are also related to one another, such that increases in ventral striatal activity are accompanied by increases in the amplitude of the feedback negativity. Although there is a long history of research implicating the midbrain dopamine system in reward processing, there has been little research into the possibility that structural variability in the midbrain may be linked to functional variability in reward reactivity. Here, we used structural MRI to measure midbrain volumes in addition to fMRI and ERP measures of functional neural reactivity to rewards in a simple gambling task. The results suggest that as midbrain volumes increase, fMRI reward reactivity in the ventral striatum and medial prefrontal cortex also increases. A similar relationship exists between midbrain structure and the amplitude of the feedback negativity; further, this relationship is mediated specifically by activity in the ventral striatum. These data demonstrate convergence between neuroanatomical, hemodynamic, and electrophysiological measures. Thus, structural variability in the midbrain relates to variability in fMRI and ERP measures of functional reward reactivity, which may play a critical role in reward-related psychopathologies and the treatment of these disorders.

  18. Portable MRI developed at Los Alamos

    SciTech Connect

    Espy, Michelle

    2015-04-22

    Scientists at Los Alamos National Laboratory are developing an ultra-low-field Magnetic Resonance Imaging (MRI) system that could be low-power and lightweight enough for forward deployment on the battlefield and to field hospitals in the World's poorest regions. "MRI technology is a powerful medical diagnostic tool," said Michelle Espy, the Battlefield MRI (bMRI) project leader, "ideally suited for imaging soft-tissue injury, particularly to the brain." But hospital-based MRI devices are big and expensive, and require considerable infrastructure, such as large quantities of cryogens like liquid nitrogen and helium, and they typically use a large amount of energy. "Standard MRI machines just can't go everywhere," said Espy. "Soldiers wounded in battle usually have to be flown to a large hospital and people in emerging nations just don't have access to MRI at all. We've been in contact with doctors who routinely work in the Third World and report that MRI would be extremely valuable in treating pediatric encephalopathy, and other serious diseases in children." So the Los Alamos team started thinking about a way to make an MRI device that could be relatively easy to transport, set up, and use in an unconventional setting. Conventional MRI machines use very large magnetic fields that align the protons in water molecules to then create magnetic resonance signals, which are detected by the machine and turned into images. The large magnetic fields create exceptionally detailed images, but they are difficult and expensive to make. Espy and her team wanted to see if images of sufficient quality could be made with ultra-low-magnetic fields, similar in strength to the Earth's magnetic field. To achieve images at such low fields they use exquisitely sensitive detectors called Superconducting Quantum Interference Devices, or SQUIDs. SQUIDs are among the most sensitive magnetic field detectors available, so interference with the signal is the primary stumbling block. "SQUIDs are

  19. Massively Parallel MRI Detector Arrays

    PubMed Central

    Keil, Boris; Wald, Lawrence L

    2013-01-01

    Originally proposed as a method to increase sensitivity by extending the locally high-sensitivity of small surface coil elements to larger areas, the term parallel imaging now includes the use of array coils to perform image encoding. This methodology has impacted clinical imaging to the point where many examinations are performed with an array comprising multiple smaller surface coil elements as the detector of the MR signal. This article reviews the theoretical and experimental basis for the trend towards higher channel counts relying on insights gained from modeling and experimental studies as well as the theoretical analysis of the so-called “ultimate” SNR and g-factor. We also review the methods for optimally combining array data and changes in RF methodology needed to construct massively parallel MRI detector arrays and show some examples of state-of-the-art for highly accelerated imaging with the resulting highly parallel arrays. PMID:23453758

  20. Combined PET/MRI scanner

    DOEpatents

    Schlyer, David; Woody, Craig L.; Rooney, William; Vaska, Paul; Stoll, Sean; Pratte, Jean-Francois; O'Connor, Paul

    2007-10-23

    A combined PET/MRI scanner generally includes a magnet for producing a magnetic field suitable for magnetic resonance imaging, a radiofrequency (RF) coil disposed within the magnetic field produced by the magnet and a ring tomograph disposed within the magnetic field produced by the magnet. The ring tomograph includes a scintillator layer for outputting at least one photon in response to an annihilation event, a detection array coupled to the scintillator layer for detecting the at least one photon outputted by the scintillator layer and for outputting a detection signal in response to the detected photon and a front-end electronic array coupled to the detection array for receiving the detection signal, wherein the front-end array has a preamplifier and a shaper network for conditioning the detection signal.

  1. Intra voxel analysis in MRI

    NASA Astrophysics Data System (ADS)

    Ambrosanio, Michele; Baselice, Fabio; Ferraioli, Giampaolo; Pascazio, Vito

    2014-03-01

    A new application of Compressive Sensing (CS) in Magnetic Resonance Imaging (MRI) field is presented. In particular, first results of the Intra Voxel Analysis (IVA) technique are reported. The idea is to exploit CS peculiarities in order to distinguish different contributions inside the same resolution cell, instead of reconstructing images from not fully sampled k-space acquisition. Applied to MRI field, this means the possibility of estimating the presence of different tissues inside the same voxel, i.e. in one pixel of the obtained image. In other words, the method is the first attempt, as far as we know, of achieving Spectroscopy-like results starting from each pixel of MR images. In particular, tissues are distinguished each others by evaluating their spin-spin relaxation times. Within this manuscript, first results on clinical dataset, in particular a phantom made by aqueous solution and oil and an occipital brain lesion corresponding to a metastatic breast cancer nodule, are reported. Considering the phantom dataset, in particular focusing on the slice where the separation between water and oil occurs, the methodology is able to distinguish the two components with different spin-spin relaxation times. With respect to clinical dataset,focusing on a voxel of the lesion area, the approach is able to detect the presence of two tissues, namely the healthy and the cancer related ones, while in other location outside the lesion only the healthy tissue is detected. Of course, these are the first results of the proposed methodology, further studies on different types of clinical datasets are required in order to widely validate the approach. Although few datasets have been considered, results seem both interesting and promising.

  2. The role of magnetic resonance imaging (MRI) in focal therapy for prostate cancer: recommendations from a consensus panel

    PubMed Central

    Muller, Berrend G.; Fütterer, Jurgen J.; Gupta, Rajan T.; Katz, Aaron; Kirkham, Alexander; Kurhanewicz, John; Moul, Judd W.; Pinto, Peter A.; Rastinehad, Ardeshir R.; Robertson, Cary; de la Rosette, Jean; Sanchez-Salas, Rafael; Jones, J. Stephen; Ukimura, Osamu; Verma, Sadhna; Wijkstra, Hessel; Marberger, Michael

    2014-01-01

    Objective To establish a consensus on the utility of multiparametric magnetic resonance imaging (mpMRI) to identify patients for focal therapy. Methods Urological surgeons, radiologists, and basic researchers, from Europe and North America participated in a consensus meeting about the use of mpMRI in focal therapy of prostate cancer.The consensus process was face-to-face and specific clinical issues were raised and discussed with agreement sought when possible. All participants are listed among the authors.Topics specifically did not include staging of prostate cancer, but rather identifying the optimal requirements for performing MRI, and the current status of optimally performed mpMRI to (i) determine focality of prostate cancer (e.g. localising small target lesions of ≥0.5 mL), (ii) to monitor and assess the outcome of focal ablation therapies, and (iii) to identify the diagnostic advantages of new MRI methods.In addition, the need for transperineal template saturation biopsies in selecting patients for focal therapy was discussed, if a high quality mpMRI is available. In other words, can mpMRI replace the role of transperineal saturation biopsies in patient selection for focal therapy? Results Consensus was reached on most key aspects of the meeting; however, on definition of the optimal requirements for mpMRI, there was one dissenting voice.mpMRI is the optimum approach to achieve the objectives needed for focal therapy, if made on a high quality machine (3T with/without endorectal coil or 1.5T with endorectal coil) and judged by an experienced radiologist.Structured and standardised reporting of prostate MRI is paramount.State of the art mpMRI is capable of localising small tumours for focal therapy.State of the art mpMRI is the technique of choice for follow-up of focal ablation. Conclusions The present evidence for MRI in focal therapy is limited.mpMRI is not accurate enough to consistently grade tumour aggressiveness.Template-guided saturation biopsies

  3. ICA-AROMA: A robust ICA-based strategy for removing motion artifacts from fMRI data.

    PubMed

    Pruim, Raimon H R; Mennes, Maarten; van Rooij, Daan; Llera, Alberto; Buitelaar, Jan K; Beckmann, Christian F

    2015-05-15

    Head motion during functional MRI (fMRI) scanning can induce spurious findings and/or harm detection of true effects. Solutions have been proposed, including deleting ('scrubbing') or regressing out ('spike regression') motion volumes from fMRI time-series. These strategies remove motion-induced signal variations at the cost of destroying the autocorrelation structure of the fMRI time-series and reducing temporal degrees of freedom. ICA-based fMRI denoising strategies overcome these drawbacks but typically require re-training of a classifier, needing manual labeling of derived components (e.g. ICA-FIX; Salimi-Khorshidi et al. (2014)). Here, we propose an ICA-based strategy for Automatic Removal of Motion Artifacts (ICA-AROMA) that uses a small (n=4), but robust set of theoretically motivated temporal and spatial features. Our strategy does not require classifier re-training, retains the data's autocorrelation structure and largely preserves temporal degrees of freedom. We describe ICA-AROMA, its implementation, and initial validation. ICA-AROMA identified motion components with high accuracy and robustness as illustrated by leave-N-out cross-validation. We additionally validated ICA-AROMA in resting-state (100 participants) and task-based fMRI data (118 participants). Our approach removed (motion-related) spurious noise from both rfMRI and task-based fMRI data to larger extent than regression using 24 motion parameters or spike regression. Furthermore, ICA-AROMA increased sensitivity to group-level activation. Our results show that ICA-AROMA effectively reduces motion-induced signal variations in fMRI data, is applicable across datasets without requiring classifier re-training, and preserves the temporal characteristics of the fMRI data.

  4. MRI visualisation by digitally reconstructed radiographs

    NASA Astrophysics Data System (ADS)

    Serrurier, Antoine; Bönsch, Andrea; Lau, Robert; Deserno, Thomas M.

    2015-03-01

    Visualising volumetric medical images such as computed tomography and magnetic resonance imaging (MRI) on picture archiving and communication systems (PACS) clients is often achieved by image browsing in sagittal, coronal or axial views or three-dimensional (3D) rendering. This latter technique requires fine thresholding for MRI. On the other hand, computing virtual radiograph images, also referred to as digitally reconstructed radiographs (DRR), provides in a single two-dimensional (2D) image a complete overview of the 3D data. It appears therefore as a powerful alternative for MRI visualisation and preview in PACS. This study describes a method to compute DRR from T1-weighted MRI. After segmentation of the background, a histogram distribution analysis is performed and each foreground MRI voxel is labeled as one of three tissues: cortical bone, also known as principal absorber of the X-rays, muscle and fat. An intensity level is attributed to each voxel according to the Hounsfield scale, linearly related to the X-ray attenuation coefficient. Each DRR pixel is computed as the accumulation of the new intensities of the MRI dataset along the corresponding X-ray. The method has been tested on 16 T1-weighted MRI sets. Anterior-posterior and lateral DRR have been computed with reasonable qualities and avoiding any manual tissue segmentations. This proof-of-concept holds for research application for use in clinical PACS.

  5. Recommendations for Real-Time Speech MRI

    PubMed Central

    Lingala, Sajan Goud; Sutton, Brad P.; Miquel, Marc E.; Nayak, Krishna S.

    2016-01-01

    Real-time magnetic resonance imaging (RT-MRI) is being increasingly used for speech and vocal production research studies. Several imaging protocols have emerged based on advances in RT-MRI acquisition, reconstruction, and audio-processing methods. This review summarizes the state-of-the-art, discusses technical considerations, and provides specific guidance for new groups entering this field. We provide recommendations for performing RT-MRI of the upper airway. This is a consensus statement stemming from the ISMRM-endorsed Speech MRI summit held in Los Angeles, February 2014. A major unmet need identified at the summit was the need for consensus on protocols that can be easily adapted by researchers equipped with conventional MRI systems. To this end, we provide a discussion of tradeoffs in RT-MRI in terms of acquisition requirements, a priori assumptions, artifacts, computational load, and performance for different speech tasks. We provide four recommended protocols and identify appropriate acquisition and reconstruction tools. We list pointers to open-source software that facilitate implementation. We conclude by discussing current open challenges in the methodological aspects of RT-MRI of speech. PMID:26174802

  6. The effect of alcohol consumption on the adolescent brain: A systematic review of MRI and fMRI studies of alcohol-using youth

    PubMed Central

    Feldstein Ewing, Sarah W.; Sakhardande, Ashok; Blakemore, Sarah-Jayne

    2014-01-01

    Background A large proportion of adolescents drink alcohol, with many engaging in high-risk patterns of consumption, including binge drinking. Here, we systematically review and synthesize the existing empirical literature on how consuming alcohol affects the developing human brain in alcohol-using (AU) youth. Methods For this systematic review, we began by conducting a literature search using the PubMED database to identify all available peer-reviewed magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI) studies of AU adolescents (aged 19 and under). All studies were screened against a strict set of criteria designed to constrain the impact of confounding factors, such as co-occurring psychiatric conditions. Results Twenty-one studies (10 MRI and 11 fMRI) met the criteria for inclusion. A synthesis of the MRI studies suggested that overall, AU youth showed regional differences in brain structure as compared with non-AU youth, with smaller grey matter volumes and lower white matter integrity in relevant brain areas. In terms of fMRI outcomes, despite equivalent task performance between AU and non-AU youth, AU youth showed a broad pattern of lower task-relevant activation, and greater task-irrelevant activation. In addition, a pattern of gender differences was observed for brain structure and function, with particularly striking effects among AU females. Conclusions Alcohol consumption during adolescence was associated with significant differences in structure and function in the developing human brain. However, this is a nascent field, with several limiting factors (including small sample sizes, cross-sectional designs, presence of confounding factors) within many of the reviewed studies, meaning that results should be interpreted in light of the preliminary state of the field. Future longitudinal and large-scale studies are critical to replicate the existing findings, and to provide a more comprehensive and conclusive picture of the

  7. Influence of dental materials on dental MRI

    PubMed Central

    Tymofiyeva, O; Vaegler, S; Rottner, K; Boldt, J; Hopfgartner, AJ; Proff, PC; Richter, E-J; Jakob, PM

    2013-01-01

    Objectives: To investigate the potential influence of standard dental materials on dental MRI (dMRI) by estimating the magnetic susceptibility with the help of the MRI-based geometric distortion method and to classify the materials from the standpoint of dMRI. Methods: A series of standard dental materials was studied on a 1.5 T MRI system using spin echo and gradient echo pulse sequences and their magnetic susceptibility was estimated using the geometric method. Measurements on samples of dental materials were supported by in vivo examples obtained in dedicated dMRI procedures. Results: The tested materials showed a range of distortion degrees. The following materials were classified as fully compatible materials that can be present even in the tooth of interest: the resin-based sealer AH Plus® (Dentsply, Maillefer, Germany), glass ionomer cement, gutta-percha, zirconium dioxide and composites from one of the tested manufacturers. Interestingly, composites provided by the other manufacturer caused relatively strong distortions and were therefore classified as compatible I, along with amalgam, gold alloy, gold–ceramic crowns, titanium alloy and NiTi orthodontic wires. Materials, the magnetic susceptibility of which differed from that of water by more than 200 ppm, were classified as non-compatible materials that should not be present in the patient’s mouth for any dMRI applications. They included stainless steel orthodontic appliances and CoCr. Conclusions: A classification of the materials that complies with the standard grouping of materials according to their magnetic susceptibility was proposed and adopted for the purposes of dMRI. The proposed classification can serve as a guideline in future dMRI research. PMID:23610088

  8. Wavelet-based regularity analysis reveals Recurrent Spatiotemporal Behavior in Resting-state fMRI

    PubMed Central

    Smith, Robert X.; Jann, Kay; Ances, Beau; Wang, Danny J.J.

    2015-01-01

    One of the major findings from multi-modal neuroimaging studies in the past decade is that the human brain is anatomically and functionally organized into large-scale networks. In resting state fMRI (rs-fMRI), spatial patterns emerge when temporal correlations between various brain regions are tallied, evidencing networks of ongoing intercortical cooperation. However, the dynamic structure governing the brain’s spontaneous activity is far less understood due to the short and noisy nature of the rs-fMRI signal. Here we develop a wavelet-based regularity analysis based on noise estimation capabilities of the wavelet transform to measure recurrent temporal pattern stability within the rs-fMRI signal across multiple temporal scales. The method consists of performing a stationary wavelet transform (SWT) to preserve signal structure, followed by construction of “lagged” subsequences to adjust for correlated features, and finally the calculation of sample entropy across wavelet scales based on an “objective” estimate of noise level at each scale. We found that the brain’s default mode network (DMN) areas manifest a higher level of irregularity in rs-fMRI time series than rest of the brain. In 25 aged subjects with mild cognitive impairment and 25 matched healthy controls, wavelet based regularity analysis showed improved sensitivity in detecting changes in the regularity of rs-fMRI signals between the two groups within the DMN and executive control networks, compared to standard multiscale entropy analysis. Wavelet based regularity analysis based on noise estimation capabilities of the wavelet transform is a promising technique to characterize the dynamic structure of rs-fMRI as well as other biological signals. PMID:26096080

  9. Wavelet-based regularity analysis reveals recurrent spatiotemporal behavior in resting-state fMRI.

    PubMed

    Smith, Robert X; Jann, Kay; Ances, Beau; Wang, Danny J J

    2015-09-01

    One of the major findings from multimodal neuroimaging studies in the past decade is that the human brain is anatomically and functionally organized into large-scale networks. In resting state fMRI (rs-fMRI), spatial patterns emerge when temporal correlations between various brain regions are tallied, evidencing networks of ongoing intercortical cooperation. However, the dynamic structure governing the brain's spontaneous activity is far less understood due to the short and noisy nature of the rs-fMRI signal. Here, we develop a wavelet-based regularity analysis based on noise estimation capabilities of the wavelet transform to measure recurrent temporal pattern stability within the rs-fMRI signal across multiple temporal scales. The method consists of performing a stationary wavelet transform to preserve signal structure, followed by construction of "lagged" subsequences to adjust for correlated features, and finally the calculation of sample entropy across wavelet scales based on an "objective" estimate of noise level at each scale. We found that the brain's default mode network (DMN) areas manifest a higher level of irregularity in rs-fMRI time series than rest of the brain. In 25 aged subjects with mild cognitive impairment and 25 matched healthy controls, wavelet-based regularity analysis showed improved sensitivity in detecting changes in the regularity of rs-fMRI signals between the two groups within the DMN and executive control networks, compared with standard multiscale entropy analysis. Wavelet-based regularity analysis based on noise estimation capabilities of the wavelet transform is a promising technique to characterize the dynamic structure of rs-fMRI as well as other biological signals.

  10. Imaging of the myocardium using (18)F-FDG-PET/MRI.

    PubMed

    Ferda, Jiří; Hromádka, Milan; Baxa, Jan

    2016-10-01

    The introduction of the integrated hybrid PET/MRI equipment creates the possibility to perform PET and MRI simultaneously. Depending on the clinical question, the metabolic conversion to glycolytic activity or beta-oxidation is performed before the application of FDG. Since FDG aids to evaluate the energetic metabolism of the myocytes and myocardial MRI reaches the imaging capabilities of perfusion and tissue characterization in the daily routine, FDG-PET/MRI looks to be a promising method of PET/MRI exploitation in cardiac imaging. When myocardial FDG uptake should be evaluated in association with the perfusion distribution, the cross-evaluation of FDG accumulation distribution and perfusion distribution pattern is necessary. The different scenarios may be used in the assessment of myocardium, the conversion to glycolytic activity is used in the imaging of the viable myocardium, but the glycolytic activity suppression might be used in the indications of the identification of injured myocardium by ischemia or inflammation. FDG-PET/MRI might aid to answer the clinical tasks according to the structure, current function and possibilities to improve the function in ischemic heart disease or to display the extent or activity of myocardial inflammation in sarcoidosis. The tight coupling between metabolism, perfusion and contractile function offers an opportunity for the simultaneous assessment of cardiac performance using one imaging modality. PMID:27470994

  11. PET/MRI: THE NEXT GENERATION OF MULTI-MODALITY IMAGING?

    PubMed Central

    Pichler, Bernd; Wehrl, Hans F; Kolb, Armin; Judenhofer, Martin S

    2009-01-01

    Multi-modal imaging is now well-established in routine clinical practice. Especially in the field of Nuclear Medicine, new PET installations are comprised almost exclusively of combined PET/CT scanners rather than PET-only systems. However, PET/CT has certain notable shortcomings, including the inability to perform simultaneous data acquisition and the significant radiation dose to the patient contributed by CT. MRI offers, compared to CT, better contrast among soft tissues as well as functional-imaging capabilities. Therefore, the combination of PET with MRI provides many advantages which go far beyond simply combining functional PET information with structural MRI information. Many technical challenges, including possible interference between these modalities, have to be solved when combining PET and MRI and various approaches have been adapted to resolving these issues. Here we present an overview of current working prototypes of combined PET/MRI scanners from different groups. In addition, besides PET/MR images of mice, the first such images of a rat PET/MR, acquired with the first commercial clinical PET/MRI scanner, are presented. The combination of PET and MR is a promising tool in pre-clinical research and will certainly progress to clinical application. PMID:18396179

  12. Real diffusion-weighted MRI enabling true signal averaging and increased diffusion contrast.

    PubMed

    Eichner, Cornelius; Cauley, Stephen F; Cohen-Adad, Julien; Möller, Harald E; Turner, Robert; Setsompop, Kawin; Wald, Lawrence L

    2015-11-15

    This project aims to characterize the impact of underlying noise distributions on diffusion-weighted imaging. The noise floor is a well-known problem for traditional magnitude-based diffusion-weighted MRI (dMRI) data, leading to biased diffusion model fits and inaccurate signal averaging. Here, we introduce a total-variation-based algorithm to eliminate shot-to-shot phase variations of complex-valued diffusion data with the intention to extract real-valued dMRI datasets. The obtained real-valued diffusion data are no longer superimposed by a noise floor but instead by a zero-mean Gaussian noise distribution, yielding dMRI data without signal bias. We acquired high-resolution dMRI data with strong diffusion weighting and, thus, low signal-to-noise ratio. Both the extracted real-valued and traditional magnitude data were compared regarding signal averaging, diffusion model fitting and accuracy in resolving crossing fibers. Our results clearly indicate that real-valued diffusion data enables idealized conditions for signal averaging. Furthermore, the proposed method enables unbiased use of widely employed linear least squares estimators for model fitting and demonstrates an increased sensitivity to detect secondary fiber directions with reduced angular error. The use of phase-corrected, real-valued data for dMRI will therefore help to clear the way for more detailed and accurate studies of white matter microstructure and structural connectivity on a fine scale.

  13. Imaging of the myocardium using (18)F-FDG-PET/MRI.

    PubMed

    Ferda, Jiří; Hromádka, Milan; Baxa, Jan

    2016-10-01

    The introduction of the integrated hybrid PET/MRI equipment creates the possibility to perform PET and MRI simultaneously. Depending on the clinical question, the metabolic conversion to glycolytic activity or beta-oxidation is performed before the application of FDG. Since FDG aids to evaluate the energetic metabolism of the myocytes and myocardial MRI reaches the imaging capabilities of perfusion and tissue characterization in the daily routine, FDG-PET/MRI looks to be a promising method of PET/MRI exploitation in cardiac imaging. When myocardial FDG uptake should be evaluated in association with the perfusion distribution, the cross-evaluation of FDG accumulation distribution and perfusion distribution pattern is necessary. The different scenarios may be used in the assessment of myocardium, the conversion to glycolytic activity is used in the imaging of the viable myocardium, but the glycolytic activity suppression might be used in the indications of the identification of injured myocardium by ischemia or inflammation. FDG-PET/MRI might aid to answer the clinical tasks according to the structure, current function and possibilities to improve the function in ischemic heart disease or to display the extent or activity of myocardial inflammation in sarcoidosis. The tight coupling between metabolism, perfusion and contractile function offers an opportunity for the simultaneous assessment of cardiac performance using one imaging modality.

  14. Scale-Free Properties of the fMRI Signal during Rest and Task

    PubMed Central

    He, Biyu J.

    2011-01-01

    It has recently been shown that a significant portion of brain electrical field potentials consists of scale-free dynamics. These scale-free brain dynamics contain complex spatiotemporal structures and are modulated by task performance. Here we show that the fMRI signal recorded from the human brain is also scale-free; its power-law exponent differentiates between brain networks, and correlates with fMRI signal variance and brain glucose metabolism. Importantly, in parallel to brain electrical field potentials, the variance and power-law exponent of the fMRI signal decrease during task activation, suggesting that the signal contains more long-range memory during rest and conversely is more efficient at online information processing during task. Remarkably, similar changes also occurred in task-deactivated brain regions, revealing the presence of an optimal dynamic range in the fMRI signal. The scale-free properties of the fMRI signal and brain electrical field potentials bespeak their respective stationarity and nonstationarity. This suggests that neurovascular coupling mechanism is likely to contain a transformation from nonstationarity to stationarity. In summary, our results demonstrate the functional relevance of scale-free properties of the fMRI signal and impose constraints on future models of neurovascular coupling. PMID:21957241

  15. Real diffusion-weighted MRI enabling true signal averaging and increased diffusion contrast.

    PubMed

    Eichner, Cornelius; Cauley, Stephen F; Cohen-Adad, Julien; Möller, Harald E; Turner, Robert; Setsompop, Kawin; Wald, Lawrence L

    2015-11-15

    This project aims to characterize the impact of underlying noise distributions on diffusion-weighted imaging. The noise floor is a well-known problem for traditional magnitude-based diffusion-weighted MRI (dMRI) data, leading to biased diffusion model fits and inaccurate signal averaging. Here, we introduce a total-variation-based algorithm to eliminate shot-to-shot phase variations of complex-valued diffusion data with the intention to extract real-valued dMRI datasets. The obtained real-valued diffusion data are no longer superimposed by a noise floor but instead by a zero-mean Gaussian noise distribution, yielding dMRI data without signal bias. We acquired high-resolution dMRI data with strong diffusion weighting and, thus, low signal-to-noise ratio. Both the extracted real-valued and traditional magnitude data were compared regarding signal averaging, diffusion model fitting and accuracy in resolving crossing fibers. Our results clearly indicate that real-valued diffusion data enables idealized conditions for signal averaging. Furthermore, the proposed method enables unbiased use of widely employed linear least squares estimators for model fitting and demonstrates an increased sensitivity to detect secondary fiber directions with reduced angular error. The use of phase-corrected, real-valued data for dMRI will therefore help to clear the way for more detailed and accurate studies of white matter microstructure and structural connectivity on a fine scale. PMID:26241680

  16. MRI-guided focused ultrasound treatments.

    PubMed

    Hynynen, Kullervo

    2010-02-01

    Focused ultrasound (FUS) allows noninvasive focal delivery of energy deep into soft tissues. The focused energy can be used to modify and eliminate tissue for therapeutic purposes while the energy delivery is targeted and monitored using magnetic resonance imaging (MRI). MRI compatible methods to deliver these exposures have undergone rapid development over the past 10 years such that clinical treatments are now routinely performed. This paper will review the current technical and clinical status of MRI-guided focused ultrasound therapy and discuss future research and development opportunities.

  17. Developments in boron magnetic resonance imaging (MRI)

    SciTech Connect

    Schweizer, M.

    1995-11-01

    This report summarizes progress during the past year on maturing Boron-11 magnetic resonance imaging (MRI) methodology for noninvasive determination of BNCT agents (BSH) spatially in time. Three major areas are excerpted: (1) Boron-11 MRI of BSH distributions in a canine intracranial tumor model and the first human glioblastoma patient, (2) whole body Boron-11 MRI of BSH pharmacokinetics in a rat flank tumor model, and (3) penetration of gadolinium salts through the BBB as a function of tumor growth in the canine brain.

  18. MRI findings in Little Leaguer's shoulder.

    PubMed

    Song, James C; Lazarus, Martin L; Song, Alexandra Pae

    2006-02-01

    Little leaguer's shoulder, a stress injury of the proximal humeral physis, should be considered in the differential diagnosis for an adolescent baseball player with shoulder pain, especially if the player is pitching regularly in a competitive environment. While roentgenographs may or may not be helpful, depending on the duration and severity of the injury, we report the MRI appearance of a case of little leaguer's shoulder. We found MRI helpful in diagnosing injury to the growth plate that was radiographically occult; furthermore, we were able to document the patient's progress with a follow-up MRI examination, which showed improvement with treatment.

  19. MRI findings in pediatric patients with scurvy.

    PubMed

    Gulko, Edwin; Collins, Lee K; Murphy, Robyn C; Thornhill, Beverly A; Taragin, Benjamin H

    2015-02-01

    In modern times scurvy is a rarely encountered disease caused by ascorbic acid (vitamin C) deficiency. However, sporadic cases of scurvy persist, particularly within the pediatric population. Recent individual case reports highlight an increased incidence of scurvy among patients with autism or developmental delay, with isolated case reports detailing the magnetic resonance imaging (MRI) findings of scurvy in these pediatric populations. We present the MRI findings of scurvy in four patients with autism or developmental delay, and review the literature on MRI findings in pediatric patients with scurvy. Despite its rarity, the radiologist must consider scurvy in a pediatric patient with a restricted diet presenting with arthralgia or myalgia. PMID:25109378

  20. MRI findings in pediatric patients with scurvy.

    PubMed

    Gulko, Edwin; Collins, Lee K; Murphy, Robyn C; Thornhill, Beverly A; Taragin, Benjamin H

    2015-02-01

    In modern times scurvy is a rarely encountered disease caused by ascorbic acid (vitamin C) deficiency. However, sporadic cases of scurvy persist, particularly within the pediatric population. Recent individual case reports highlight an increased incidence of scurvy among patients with autism or developmental delay, with isolated case reports detailing the magnetic resonance imaging (MRI) findings of scurvy in these pediatric populations. We present the MRI findings of scurvy in four patients with autism or developmental delay, and review the literature on MRI findings in pediatric patients with scurvy. Despite its rarity, the radiologist must consider scurvy in a pediatric patient with a restricted diet presenting with arthralgia or myalgia.

  1. [Brain development of infant and MRI by diffusion tensor imaging].

    PubMed

    Dubois, J; Dehaene-Lambertz, G; Mangin, J-F; Le Bihan, D; Hüppi, P S; Hertz-Pannier, L

    2012-01-01

    Studying how the brain develops and becomes functional is important to understand how the man has been able to develop specific cognitive abilities, and to comprehend the complexity of some developmental pathologies. Thanks to magnetic resonance imaging (MRI), it is now possible to image the baby's immature brain and to consider subtle correlations between the brain anatomical development and the early acquisition of cognitive functions. Dedicated methodologies for image acquisition and post-treatment must then be used because the size of cerebral structures and the image contrast are very different in comparison with the adult brain, and because the examination length is a major constraint. Two recent studies have evaluated the developing brain under an original perspective. The first one has focused on cortical folding in preterm newborns, from 6 to 8 months of gestational age, assessed with T2-weighted conventional MRI. The second study has mapped the organization and maturation of white matter fiber bundles in 1- to 4-month-old healthy infants with diffusion tensor imaging (DTI). Both studies have enabled to highlight spatio-temporal differences in the brain regions' maturation, as well as early anatomical asymmetries between cerebral hemispheres. These studies emphasize the potential of MRI to evaluate brain development compared with the infant's psychomotor acquisitions after birth.

  2. Diffusion MRI/NMR magnetization equations with relaxation times

    NASA Astrophysics Data System (ADS)

    de, Dilip; Daniel, Simon

    2012-10-01

    Bloch-Torrey diffusion magnetization equation ignores relaxation effects of magnetization. Relaxation times are important in any diffusion magnetization studies of perfusion in tissues(Brain and heart specially). Bloch-Torrey equation cannot therefore describe diffusion magnetization in a real-life situation where relaxation effects play a key role, characteristics of tissues under examination. This paper describes derivations of two equations for each of the y and z component diffusion NMR/MRI magnetization (separately) in a rotating frame of reference, where rf B1 field is applied along x direction and bias magnetic field(Bo) is along z direction. The two equations are expected to further advance the science & technology of Diffusion MRI(DMRI) and diffusion functional MRI(DFMRI). These two techniques are becoming increasingly important in the study and treatment of neurological disorders, especially for the management of patients with acute stroke. It is rapidly becoming a standard for white matter disorders, as diffusion tensor imaging (DTI) can reveal abnormalities in white matter fibre structure and provide models of brain connectivity.

  3. Redox- and hypoxia-responsive MRI contrast agents.

    PubMed

    Do, Quyen N; Ratnakar, James S; Kovács, Zoltán; Sherry, A Dean

    2014-06-01

    The development of responsive or "smart" magnetic resonance imaging (MRI) contrast agents that can report specific biomarker or biological events has been the focus of MRI contrast agent research over the past 20 years. Among various biological hallmarks of interest, tissue redox and hypoxia are particularly important owing to their roles in disease states and metabolic consequences. Herein we review the development of redox-/hypoxia-sensitive T1 shortening and paramagnetic chemical exchange saturation transfer (PARACEST) MRI contrast agents. Traditionally, the relaxivity of redox-sensitive Gd(3+) -based complexes is modulated through changes in the ligand structure or molecular rotation, while PARACEST sensors exploit the sensitivity of the metal-bound water exchange rate to electronic effects of the ligand-pendant arms and alterations in the coordination geometry. Newer designs involve complexes of redox-active metal ions in which the oxidation states have different magnetic properties. The challenges of translating redox- and hypoxia-sensitive agents in vivo are also addressed. PMID:24825674

  4. Breast imaging with ultrasound tomography: a comparative study with MRI

    NASA Astrophysics Data System (ADS)

    Ranger, Bryan; Littrup, Peter; Duric, Neb; Li, Cuiping; Schmidt, Steven; Lupinacci, Jessica; Myc, Lukasz; Szczepanski, Amy; Rama, Olsi; Bey-Knight, Lisa

    2010-03-01

    The purpose of this study was to investigate the performance of an ultrasound tomography (UST) prototype relative to magnetic resonance (MR) for imaging overall breast anatomy and accentuating tumors relative to background tissue. The study was HIPAA compliant, approved by the Institutional Review Board, and performed after obtaining the requisite informed consent. Twenty-three patients were imaged with MR and the UST prototype. T1 weighted images with fat saturation, with and without gadolinium enhancement, were used to examine anatomical structures and tumors, while T2 weighted images were used to identify cysts. The UST scans generated sound speed, attenuation, and reflection images. A qualitative visual comparison of the MRI and UST images was then used to identify anatomical similarities. A more focused approach that involved a comparison of reported masses, lesion volumes, and breast density was used to quantify the findings from the visual assessment. Our acoustic tomography prototype imaged distributions of fibrous stroma, parenchyma, fatty tissues, and lesions in patterns similar to those seen in the MR images. The range of thresholds required to establish tumor volume equivalency between MRI and UST suggested that a universal threshold for isolating masses relative to background tissue is feasible with UST. UST has demonstrated the ability to visualize and characterize breast tissues in a manner comparable to MRI. Thresholding techniques accentuate masses relative to background anatomy, which may prove clinically useful for early cancer detection.

  5. Redox- and hypoxia-responsive MRI contrast agents.

    PubMed

    Do, Quyen N; Ratnakar, James S; Kovács, Zoltán; Sherry, A Dean

    2014-06-01

    The development of responsive or "smart" magnetic resonance imaging (MRI) contrast agents that can report specific biomarker or biological events has been the focus of MRI contrast agent research over the past 20 years. Among various biological hallmarks of interest, tissue redox and hypoxia are particularly important owing to their roles in disease states and metabolic consequences. Herein we review the development of redox-/hypoxia-sensitive T1 shortening and paramagnetic chemical exchange saturation transfer (PARACEST) MRI contrast agents. Traditionally, the relaxivity of redox-sensitive Gd(3+) -based complexes is modulated through changes in the ligand structure or molecular rotation, while PARACEST sensors exploit the sensitivity of the metal-bound water exchange rate to electronic effects of the ligand-pendant arms and alterations in the coordination geometry. Newer designs involve complexes of redox-active metal ions in which the oxidation states have different magnetic properties. The challenges of translating redox- and hypoxia-sensitive agents in vivo are also addressed.

  6. Redox- and Hypoxia-Responsive MRI Contrast Agents

    PubMed Central

    Do, Quyen N.; Ratnakar, James S.; Kovács, Zoltán

    2014-01-01

    The development of responsive or “smart” magnetic resonance imaging (MRI) contrast agents that can report specific biomarker or biological events has been the focus of MRI contrast agent research over the past 20 years. Among various biological hallmarks of interest, tissue redox and hypoxia are particularly important owing to their roles in disease states and metabolic consequences. Herein we review the development of redox-/hypoxia-sensitive T1 shortening and paramagnetic chemical exchange saturation transfer (PARACEST) MRI contrast agents. Traditionally, the relaxivity of redox-sensitive Gd3+-based complexes is modulated through changes in the ligand structure or molecular rotation, while PARACEST sensors exploit the sensitivity of the metal-bound water exchange rate to electronic effects of the ligand-pendant arms and alterations in the coordination geometry. Newer designs involve complexes of redox-active metal ions in which the oxidation states have different magnetic properties. The challenges of translating redox- and hypoxia-sensitive agents in vivo are also addressed. PMID:24825674

  7. Decomposition of fMRI data into multiple components

    NASA Astrophysics Data System (ADS)

    Meyer, Francois G.

    2000-12-01

    The goal of this work is to provide a new representation of functional magnetic resonance imaging (fMRI) time series. Functional neuroimaging aims at quantifying and localizing neuronal activity using imaging techniques. Functional MRI can detect and quantify hemodynamic changes induced by brain activation and neuronal activity. The time course of the fMRI signal at a given voxel inside the brain is represented with a structural model where each component of the model belongs to a subspace spanned by a small number of basis functions. The basis functions in different subspaces have very distinct time-frequency characteristics. The large scale trend of the signal is represented with a combination of large scale wavelets. The response to the stimulus is expanded on a small set of basis functions. Because it is critical to adapt the basis functions to the type of stimulus, the evoked response to a random presentation is expanded into small scale wavelets or wavelet packets, while the response to a periodic stimulus is represented with cosine or sine functions. We illustrate the estimation of the components of the model with several experiments.

  8. Simulation of spin dynamics: a tool in MRI system development

    NASA Astrophysics Data System (ADS)

    Stöcker, Tony; Vahedipour, Kaveh; Shah, N. Jon

    2011-05-01

    Magnetic Resonance Imaging (MRI) is a routine diagnostic tool in the clinics and the method of choice in soft-tissue contrast medical imaging. It is an important tool in neuroscience to investigate structure and function of the living brain on a systemic level. The latter is one of the driving forces to further develop MRI technology, as neuroscience especially demands higher spatiotemporal resolution which is to be achieved through increasing the static main magnetic field, B0. Although standard MRI is a mature technology, ultra high field (UHF) systems, at B0 >= 7 T, offer space for new technical inventions as the physical conditions dramatically change. This work shows that the development strongly benefits from computer simulations of the measurement process on the basis of a semi-classical, nuclear spin-1/2 treatment given by the Bloch equations. Possible applications of such simulations are outlined, suggesting new solutions to the UHF-specific inhomogeneity problems of the static main field as well as the high-frequency transmit field.

  9. Detecting breast microcalcifications with high-field MRI.

    PubMed

    de Leeuw, Hendrik; Stehouwer, Bertine L; Bakker, Chris J G; Klomp, Dennis W J; van Diest, Paul J; Luijten, Peter R; Seevinck, Peter R; van den Bosch, Maurice A A J; Viergever, Max A; Veldhuis, Wouter B

    2014-05-01

    The aim of this study was to detect microcalcifications in human whole breast specimens using high-field MRI. Four mastectomy specimens, obtained with approval of the institutional review board, were subjected to gradient-echo MRI acquisitions on a high-field MR scanner. The phase derivative was used to detect microcalcifications. The echo time and imaging resolution were varied to study the sensitivity of the proposed method. Computed tomography images of the mastectomy specimens and prior acquired mammography images were used to validate the results. A template matching algorithm was designed to detect microcalcifications automatically. The three spatial derivatives of the signal phase surrounding a field-perturbing object allowed three-dimensional localization, as well as the discrimination of diamagnetic field-perturbing objects, such as calcifications, and paramagnetic field-perturbing structures, e.g. blood. A longer echo time enabled smaller disturbances to be detected, but also resulted in shading as a result of other field-disturbing materials. A higher imaging resolution increased the detection sensitivity. Microcalcifications in a linear branching configuration that spanned over 8 mm in length were detected. After manual correction, the automatic detection tool identified up to 18 microcalcifications within the samples, which was in close agreement with the number of microcalcifications found on previously acquired in vivo mammography images. Microcalcifications can be detected by MRI in human whole breast specimens by the application of phase derivative imaging. PMID:24535752

  10. Independent component analysis-based classification of Alzheimer's MRI data

    PubMed Central

    Yang, Wenlu; Lui, Ronald L.M.; Gao, Jia-Hong; Chan, Tony F.; Yau, Shing-Tung; Sperling, Reisa A.; Huang, Xudong

    2013-01-01

    There is an unmet medical need to identify neuroimaging biomarkers that is able to accurately diagnose and monitor Alzheimer's disease (AD) at very early stages and assess the response to AD-modifying therapies. To a certain extent, volumetric and functional magnetic resonance imaging (fMRI) studies can detect changes in structure, cerebral blood flow and blood oxygenation that are able to distinguish AD and mild cognitive impairment (MCI) subjects from normal controls. However, it has been challenging to use fully automated MRI analytic methods to identify potential AD neuroimaging biomarkers. We have thus proposed a method based on independent component analysis (ICA), for studying potential AD-related MR image features, coupled with the use of support vector machine (SVM) for classifying scans into categories of AD, MCI, and normal control (NC) subjects. The MRI data were selected from Open Access Series of Imaging Studies (OASIS) and the Alzheimer's Disease Neuroimaging Initiative (ADNI) databases. The experimental results showed that our ICA-based method can differentiate AD and MCI subjects from normal controls, although further methodological improvement in the analytic method and inclusion of additional variables may be required for optimal classification. PMID:21321398

  11. Implementation of compressive sensing for preclinical cine-MRI

    NASA Astrophysics Data System (ADS)

    Tan, Elliot; Yang, Ming; Ma, Lixin; Zheng, Yahong Rosa

    2014-03-01

    This paper presents a practical implementation of Compressive Sensing (CS) for a preclinical MRI machine to acquire randomly undersampled k-space data in cardiac function imaging applications. First, random undersampling masks were generated based on Gaussian, Cauchy, wrapped Cauchy and von Mises probability distribution functions by the inverse transform method. The best masks for undersampling ratios of 0.3, 0.4 and 0.5 were chosen for animal experimentation, and were programmed into a Bruker Avance III BioSpec 7.0T MRI system through method programming in ParaVision. Three undersampled mouse heart datasets were obtained using a fast low angle shot (FLASH) sequence, along with a control undersampled phantom dataset. ECG and respiratory gating was used to obtain high quality images. After CS reconstructions were applied to all acquired data, resulting images were quantitatively analyzed using the performance metrics of reconstruction error and Structural Similarity Index (SSIM). The comparative analysis indicated that CS reconstructed images from MRI machine undersampled data were indeed comparable to CS reconstructed images from retrospective undersampled data, and that CS techniques are practical in a preclinical setting. The implementation achieved 2 to 4 times acceleration for image acquisition and satisfactory quality of image reconstruction.

  12. Volumetric and fiber-tracing MRI methods for gray and white matter.

    PubMed

    Larvie, Mykol; Fischl, Bruce

    2016-01-01

    Magnetic resonance imaging (MRI) is capable of generating high-resolution brain images with fine anatomic detail and unique tissue contrasts that reveal structures that are not visible to the eye. Sharply defined gray- and white-matter interfaces allow for quantitative anatomic analysis that can be accurately performed with largely automated segmentation methods. In an analogous fashion, diffusion MRI in the brain provides structural information based on contrasts derived from the diffusivity of water in brain tissue, which can highlight the orientation of neuronal axons. Also using largely automated methods, diffusion MRI can be used to generate models of white-matter tracts throughout the brain, a method known as tractography, as well as characterize the microstructural integrity of neuronal axons. Tractographic analysis has helped to define connectivity in the brain that powerfully informs understanding of brain function, and, together with other diffusion metrics, is useful in evaluation of the normal and diseased brain. The quantitative methods of brain segmentation, tractography, and diffusion MRI extend MRI into a realm beyond visual inspection and provide otherwise unachievable sensitivity and specificity in the analysis of brain structure and function.

  13. Volumetric and fiber-tracing MRI methods for gray and white matter.

    PubMed

    Larvie, Mykol; Fischl, Bruce

    2016-01-01

    Magnetic resonance imaging (MRI) is capable of generating high-resolution brain images with fine anatomic detail and unique tissue contrasts that reveal structures that are not visible to the eye. Sharply defined gray- and white-matter interfaces allow for quantitative anatomic analysis that can be accurately performed with largely automated segmentation methods. In an analogous fashion, diffusion MRI in the brain provides structural information based on contrasts derived from the diffusivity of water in brain tissue, which can highlight the orientation of neuronal axons. Also using largely automated methods, diffusion MRI can be used to generate models of white-matter tracts throughout the brain, a method known as tractography, as well as characterize the microstructural integrity of neuronal axons. Tractographic analysis has helped to define connectivity in the brain that powerfully informs understanding of brain function, and, together with other diffusion metrics, is useful in evaluation of the normal and diseased brain. The quantitative methods of brain segmentation, tractography, and diffusion MRI extend MRI into a realm beyond visual inspection and provide otherwise unachievable sensitivity and specificity in the analysis of brain structure and function. PMID:27432659

  14. Imaging of adult flatfoot: correlation of radiographic measurements with MRI.

    PubMed

    Lin, Yu-Ching; Mhuircheartaigh, Jennifer Ni; Lamb, Joshua; Kung, Justin W; Yablon, Corrie M; Wu, Jim S

    2015-02-01

    OBJECTIVE. The purpose of this study is to determine whether radiographic foot measurements can predict injury of the posterior tibial tendon (PTT) and the supporting structures of the medial longitudinal arch as diagnosed on MRI. MATERIALS AND METHODS. After institutional review board approval, 100 consecutive patients with radiographic and MRI examinations performed within a 2-month period were enrolled. Thirty-one patients had PTT dysfunction clinically, and 69 patients had other causes of ankle pain. Talonavicular uncoverage angle, incongruency angle, calcaneal pitch angle, Meary angle, cuneiform-to-fifth metatarsal height, and talar tilt were calculated on standing foot or ankle radiographs. MRI was used to assess for abnormalities of the PTT (tenosynovitis, tendinosis, and tear) and supporting structures of the medial longitudinal arch (spring ligament, deltoid ligament, and sinus tarsi). Statistical analysis was performed using the chi-square and Fisher exact tests for categoric variables; the Student t test was used for continuous variables. RESULTS. There was a statistically significant association of PTT tear with abnormal talonavicular uncoverage angle, calcaneal pitch angle, Meary angle, and cuneiform-to-fifth metatarsal height. PTT tendinosis and isolated tenosynovitis had a poor association with most radiologic measurements. If both calcaneal pitch and Meary angles were normal, no PTT tear was present. An abnormal calcaneal pitch angle had the best association with injury to the supporting medial longitudinal arch structures. CONCLUSION. Radiographic measurements, especially calcaneal pitch and Meary angles, can be useful in detecting PTT tears. Calcaneal pitch angle provides the best assessment of injury to the supporting structures of the medial longitudinal arch.

  15. Dual-Purpose Magnetic Micelles for MRI and Gene Delivery

    PubMed Central

    Wang, Chunyan; Ravi, Sowndharya; Martinez, Gary.V.; Chinnasamy, Vignesh; Raulji, Payal; Howell, Mark; Davis, Yvonne; Seehra, Mohindar S.; Mohapatra, Subhra

    2013-01-01

    Gene therapy is a promising therapeutic approach for treating disease, but the efficient delivery of genes to desired locations with minimal side effects remains a challenge. In addition to gene therapy, it is also highly desirable to provide sensitive imaging information in patients for disease diagnosis, screening and post-therapy monitoring. Here, we report on the development of dual-purpose chitosan and polyethyleneimine (PEI) coated magnetic micelles (CP-mag-micelles) that can deliver nucleic acid-based therapeutic agents and also provide magnetic resonance imaging (MRI). These ‘theranostic’ CP-mag-micelles are composed of monodisperse hydrophobic superparamagnetic iron oxide nanoparticles (SPIONs) loaded into the cores of micelles that are self-assembled from a block copolymer of poly (D, L-lactide) (PLA) and monomethoxy polyethylene glycol (mPEG). For efficient loading and protection of the nucleic acids the micelles were coated with cationic polymers, such as chitosan and PEI. The morphology and size distribution of the CP-mag-micelles were characterized and their potential for use as an MRI-probe was tested using an MRI scanner. The T2 relaxivity of micelles was similar to CP-mag-micelles confirming that coating with cationic polymers did not alter magnetism. Nanoparticles coated with chitosan:PEI at a weight ratio of 5:5 showed higher transfection efficiency in HEK293, 3T3 and PC3 cells than with weight ratios of 3:7 or 7:3. CP-mag-micelles are biocompatible, can be delivered to various organs and are safe. A single injection of CP-mag-micelles carrying reporter plasmids in vivo expressed genes for at least one week. Collectively, our results demonstrate that a structural reinforcement of SPIONs loaded in the core of an mPEG-PLA micelle coated with cationic polymers provides efficient DNA delivery and enhanced MRI potential, and affords a promising candidate for theranostics in the future. PMID:22561339

  16. The Suppression of Selected Acoustic Noise Frequencies in MRI

    NASA Astrophysics Data System (ADS)

    Shou, Xingxian

    Problems due to Magnetic Resonance Imaging (MRI) acoustic noise have long been an important concern, both in research and clinical applications. A study is made of certain dominant frequencies in the acoustic noise spectrum of the MRI system. Motivated by both spring and string ideas, we investigate whether the contributions to the sound from certain frequencies can be cancelled by the appropriate the gradient pulse sequence design. Ideas for cancelling these frequencies are investigated by carrying out theoretical string calculations. The MRI gradient assembly is modeled as a string and the gradient pulse sequences as a driving force for that string. Analytical results are obtained with different input gradient pulses including boxcars, trapezoids, and multiple trapezoids, along with special "quadratic" pulses. Pulse trains composed of repetitions of these pulse structures are studied. For comparison and to test these ideas, both simulations and experiments are carried out to verify our analytical results for the cancellations of selected frequency peaks. The idea that vibrations resulting from an impulsive force associated with a ramping up of a gradient pulse are shown to be cancelled immediately upon the application of another impulsive force coming from the subsequent appropriately timed ramping down of that pulse is verified both by simulations and experiments. A general approach to suppression of multiple-frequency contributions involving a series of gradient pulses with variable timings is given for the cancellations between pairs of impulse forces. The various examples investigated with string analytics and simulations and the associated MRI experiments are a physical embodiments of general time-invariant linear response theory. The present study also provides a foundation to explain results in previous papers on this subject. The method suggests that a variety of pulse profiles and timing combinations can be used to attenuate important contributions to

  17. Evidential value of postmortem MRI in forensic pathology

    NASA Astrophysics Data System (ADS)

    Schweitzer, Wolf; Schaepman, Michael E.; Ith, Michael; Bruegger, Karin; Thali, Michael J.; Doernhofer, Tanya; Tiefenthaler, Kathrin; Scheurer, Eva; Vock, Peter; Boesch, Chris; Dirnhofer, Richard

    2001-05-01

    We currently evaluate MRI as add-on to dissection. Cases can only build on high evidential values of morphological findings as estimated using Bayesian likelihood-ratios. These values may vary among different cases depending on the quality of the morphology and the discrete hypotheses to be discerned. After scanning 20 bodies using MRI admitted to our institute for autopsy, we reconstructed selected imaging findings from a couple of illustrative cases according to a geometrical model ('Pink Box') designed as an object oriented bridging protocol to enable comparison of autopsy and MRI data. Although it appears obvious that 'three-dimensional imaging yields relevant diagnoses,' comparison of selected findings suggests, that the real evidential value of a postmortem scan depends on basic geometrical features of tissue structures examined. (1) Tissue surfaces are difficult to examine in MRI, including surface features of contact wounds in firearm injuries, lacerations of the pleura, or skin needle marks. (2) Specificity and sensitivity of solid tissue block data depend on contrast and resolution. (3) Tunnels or tubes, such as coronary arteries, linear wound tracks or the aorta offer more degrees of freedom for reconstruction, including spatial reconstruction or cross sectioning in different directions. (4) Three-dimensional rendering of complex objects results in spectacular images. Their evidential value is dependent on the way thresholding of 2D slices is validated. We present illustrative examples which suggest that a possible integration of non-invasive imaging methods into Forensic Pathology in fact need to take basic geometry into consideration when discussing evidential value.

  18. MRI of brain tissue oxygen tension under hyperbaric conditions.

    PubMed

    Muir, Eric R; Cardenas, Damon P; Duong, Timothy Q

    2016-06-01

    The brain depends on a continuous supply of oxygen to maintain its structural and functional integrity. This study measured T1 from MRI under normobaric air, normobaric oxygen, hyperbaric air, and hyperbaric oxygen (HBO) conditions as a marker of tissue pO2 since dissolved molecular oxygen acts as an endogenous contrast agent. Brain tissue T1 decreased corresponding to increased pO2 with increasing inhaled oxygen concentrations, and tissue oxygenation was estimated from the T1 changes between different inhaled oxygen levels. Tissue pO2 difference maps between different oxygen conditions showed heterogeneous pO2 changes in the brain. MRI-derived tissue pO2 was markedly lower than the arterial pO2 but was slightly higher than venous pO2. Additionally, for comparison with published extracellular tissue pO2 data obtained using oxygen electrodes and other invasive techniques, a model was used to estimate extracellular and intracellular pO2 from the MRI-derived mean tissue pO2. This required multiple assumptions, and so the effects of the assumptions and parameters used in modeling brain pO2 were evaluated. MRI-derived pO2 values were strongly dependent on assumptions about the extra- and intracellular compartments but were relatively less sensitive to variations in the relaxivity constant of oxygen and contribution from oxygen in the cerebral blood compartment. This approach may prove useful in evaluating tissue oxygenation in disease states such as stroke.

  19. A low cost MRI permanent magnet prototype

    NASA Astrophysics Data System (ADS)

    Esparza-Coss, Emilio; Cole, David M.

    1998-08-01

    Here we present the proceedings in designing and constructing a low cost, friendly use, Magnetic Resonance Imaging (MRI) prototype magnet; 55 cm×45 cm×30 cm in size scaleable to full body; with a C-shaped assembly to provide open access to the 10 cm C-gap; operational at 0.22 Tesla where the low field increments the tissue contrast; structured with methodically selected and strategically positioned permanent magnets to reach the required field homogeneity as well as to be practically free of maintenance; and having iron flux return to leave an extremely low fringe field. The magnetic flux is funneled through the iron and focused by carefully designed and finely machined iron pole faces of 8.9 cm radius to create a homogeneity of less than 20 parts per million (PPM), without shimming, in a roughly 1.3 cm by 2 cm main axes oval region. An image of an okra plant was taken to test its performance.

  20. A low cost MRI permanent magnet prototype

    SciTech Connect

    Esparza-Coss, Emilio; Cole, David M.

    1998-08-28

    Here we present the proceedings in designing and constructing a low cost, friendly use, Magnetic Resonance Imaging (MRI) prototype magnet; 55 cmx45 cmx30 cm in size scaleable to full body; with a C-shaped assembly to provide open access to the 10 cm C-gap; operational at 0.22 Tesla where the low field increments the tissue contrast; structured with methodically selected and strategically positioned permanent magnets to reach the required field homogeneity as well as to be practically free of maintenance; and having iron flux return to leave an extremely low fringe field. The magnetic flux is funneled through the iron and focused by carefully designed and finely machined iron pole faces of 8.9 cm radius to create a homogeneity of less than 20 parts per million (PPM), without shimming, in a roughly 1.3 cm by 2 cm main axes oval region. An image of an okra plant was taken to test its performance.

  1. Quest for an open MRI scanner.

    PubMed

    Bertora, Franco; Borceto, Alice; Viale, Andrea; Sandini, Giulio

    2014-01-01

    A study of the motor cortex during the programming, execution and mental representation of voluntary movement is of great relevance; its evaluation in conditions close to reality is necessary, given the close integration of the visuomotor, sensory feedback and proprioceptive systems, as of yet, a functional Magnetic Resonance Imaging (fMRI) scanner allowing a human subject to maintain erect stance, observe the surroundings and conserve limb freedom is still a dream. The need for high field suggests a solenoid magnet geometry that forces an unnatural posture that affects the results, particularly when the motor cortex is investigated. In contrast in a motor functional study, the scanner should allow the subject to sit or stand, with unobstructed sight and unimpeded movement. Two approaches are presented here to solve this problem. In the first approach, an increased field intensity in an open magnet is obtained lining the "back wall" of the cavity with a sheet of current: this boosts the field intensity at the cost of the introduction of a gradient, which has to be canceled by the introduction of an opposite gradient; The second approach is an adaptation of the "double doughnut" architecture, in which the cavity widens at the center to provide additional room for the subject. The detailed design of this kind of structure has proven the feasibility of the solution.

  2. MRI appearances of borderline ovarian tumours.

    PubMed

    Bent, C L; Sahdev, A; Rockall, A G; Singh, N; Sohaib, S A; Reznek, R H

    2009-04-01

    This review was performed to describe the range of magnetic resonance imaging (MRI) appearances of borderline ovarian tumours. The MRI findings in 26 patients with 31 borderline ovarian tumours (mean age: 40.1 years, range: 14-85 years) were retrospectively reviewed. For each tumour, site, size, MRI characteristics, and enhancement following gadolinium administration were recorded. There were 20 serous and 11 mucinous borderline ovarian subtypes. Nine of 26 patients demonstrated bilateral disease on MRI; synchronous contralateral ovarian disease included three benign, five serous borderline, and one serous invasive tumour. A history of a metachronous mucinous borderline tumour was identified in one patient. MRI appearances were classified into four morphological categories: group 1 (6/31, 19%), unilocular cysts; group 2 (6/31, 19%), minimally septate cysts with papillary projections; group 3 (14/31, 45%), markedly septate lesions with plaque-like excrescences; and group 4 (5/31, 16%), predominantly solid with exophytic papillary projections, all of serous subtype. There was a significant difference in mean volume between serous (841.5 cm(3)) and mucinous (6358.2 cm(3)) subtypes (p=0.009). All tumours demonstrated at least one MRI feature suggestive of malignancy. The present review demonstrates the variable MRI appearances of borderline ovarian tumours along with imaging features suggestive of tumour subtype. In patients in whom the clinical features are suggestive of a borderline ovarian tumour (young age and normal or minimally elevated CA125), the ability to predict a borderline disease using morphological features observed on MRI would be extremely helpful in surgical planning, with the potential to offer fertility or ovary-preserving surgery. Future studies are required to further this aim.

  3. Cranial MRI in neonatal hypernatraemic dehydration.

    PubMed

    Korkmaz, A; Yiğit, S; Firat, M; Oran, O

    2000-05-01

    Severe neonatal hypernatraemia is a life-threatening electrolyte disorder because of its neurological complications. These are brain oedema, intracranial haemorrhages, haemorrhagic infarcts and thromboses. There are few reports concerning the radiological findings in the central nervous system in severe neonatal hypernatraemia. Cranial MRI findings in hypernatraemia have been reported in an older child, but have not been described in newborn infants. We report the cranial MRI findings in a newborn infant with acute renal failure and severe hypernatraemia.

  4. Infantile Refsum disease: serial evaluation with MRI.

    PubMed

    Cakirer, Sinan; Savas, Mahmut R

    2005-02-01

    Refsum disease is a rare metabolic disorder, which is characterized by the accumulation of phytanic acid in the blood and tissues, including the brain. A variant of this condition that occurs in young children is called infantile Refsum disease. The MRI findings of symmetrical signal change involving the corticospinal tracts, cerebellar dentate nuclei, and corpus callosum are characteristic. We report the serial MRI findings of a child with this rare metabolic disorder.

  5. MRI and MRS of human brain tumors.

    PubMed

    Hou, Bob L; Hu, Jiani

    2009-01-01

    The purpose of this chapter is to provide an introduction to magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) of human brain tumors, including the primary applications and basic terminology involved. Readers who wish to know more about this broad subject should seek out the referenced books (1. Tofts (2003) Quantitative MRI of the brain. Measuring changes caused by disease. Wiley; Bradley and Stark (1999) 2. Magnetic resonance imaging, 3rd Edition. Mosby Inc; Brown and Semelka (2003) 3. MRI basic principles and applications, 3rd Edition. Wiley-Liss) or reviews (4. Top Magn Reson Imaging 17:127-36, 2006; 5. JMRI 24:709-724, 2006; 6. Am J Neuroradiol 27:1404-1411, 2006).MRI is the most popular means of diagnosing human brain tumors. The inherent difference in the magnetic resonance (MR) properties of water between normal tissues and tumors results in contrast differences on the image that provide the basis for distinguishing tumors from normal tissues. In contrast to MRI, which provides spatial maps or images using water signals of the tissues, proton MRS detects signals of tissue metabolites. MRS can complement MRI because the observed MRS peaks can be linked to inherent differences in biochemical profiles between normal tissues and tumors.The goal of MRI and MRS is to characterize brain tumors, including tumor core, edge, edema, volume, types, and grade. The commonly used brain tumor MRI protocol includes T2-weighted images and T1-weighted images taken both before and after the injection of a contrast agent (typically gadolinium: Gd). The commonly used MRS technique is either point-resolved spectroscopy (PRESS) or stimulated echo acquisition mode (STEAM).

  6. What physics does affect the MRI threshold

    SciTech Connect

    Ilgisonis, V. I.; Lakhin, V. P.; Khalzov, I. V.; Smolyakov, A. I.

    2010-06-16

    Several physical effects, which can considerably decrease the magnetorotational instability (MRI) threshold are discussed. First, we show that MRI features are changed significantly in non-uniform magnetic field. Second, the buoyancy effect is shown to can be destabilizing for azimuthal flow of a resistive plasma. Third, we demonstrate that the rotating fluid may be unstable with respect to non-axisymmetric modes at much lower rotation velocities than with respect to usual symmetric modes.

  7. MRI-powered Actuators for Robotic Interventions

    PubMed Central

    Vartholomeos, Panagiotis; Qin, Lei; Dupont, Pierre E.

    2012-01-01

    This paper presents a novel actuation technology for robotically assisted MRI-guided interventional procedures. Compact and wireless, the actuators are both powered and controlled by the MRI scanner. The design concept and performance limits are described and derived analytically. Simulation and experiments in a clinical MR scanner are used to validate the analysis and to demonstrate the capability of the approach for needle biopsies. The concepts of actuator locking mechanisms and multi-axis control are also introduced. PMID:22287082

  8. A computational atlas of the hippocampal formation using ex vivo, ultra-high resolution MRI: Application to adaptive segmentation of in vivo MRI.

    PubMed

    Iglesias, Juan Eugenio; Augustinack, Jean C; Nguyen, Khoa; Player, Christopher M; Player, Allison; Wright, Michelle; Roy, Nicole; Frosch, Matthew P; McKee, Ann C; Wald, Lawrence L; Fischl, Bruce; Van Leemput, Koen

    2015-07-15

    Automated analysis of MRI data of the subregions of the hippocampus requires computational atlases built at a higher resolution than those that are typically used in current neuroimaging studies. Here we describe the construction of a statistical atlas of the hippocampal formation at the subregion level using ultra-high resolution, ex vivo MRI. Fifteen autopsy samples were scanned at 0.13 mm isotropic resolution (on average) using customized hardware. The images were manually segmented into 13 different hippocampal substructures using a protocol specifically designed for this study; precise delineations were made possible by the extraordinary resolution of the scans. In addition to the subregions, manual annotations for neighboring structures (e.g., amygdala, cortex) were obtained from a separate dataset of in vivo, T1-weighted MRI scans of the whole brain (1mm resolution). The manual labels from the in vivo and ex vivo data were combined into a single computational atlas of the hippocampal formation with a novel atlas building algorithm based on Bayesian inference. The resulting atlas can be used to automatically segment the hippocampal subregions in structural MRI images, using an algorithm that can analyze multimodal data and adapt to variations in MRI contrast due to differences in acquisition hardware or pulse sequences. The applicability of the atlas, which we are releasing as part of FreeSurfer (version 6.0), is demonstrated with experiments on three different publicly available datasets with different types of MRI contrast. The results show that the atlas and companion segmentation method: 1) can segment T1 and T2 images, as well as their combination, 2) replicate findings on mild cognitive impairment based on high-resolution T2 data, and 3) can discriminate between Alzheimer's disease subjects and elderly controls with 88% accuracy in standard resolution (1mm) T1 data, significantly outperforming the atlas in FreeSurfer version 5.3 (86% accuracy) and

  9. A computational atlas of the hippocampal formation using ex vivo, ultra-high resolution MRI: Application to adaptive segmentation of in vivo MRI.

    PubMed

    Iglesias, Juan Eugenio; Augustinack, Jean C; Nguyen, Khoa; Player, Christopher M; Player, Allison; Wright, Michelle; Roy, Nicole; Frosch, Matthew P; McKee, Ann C; Wald, Lawrence L; Fischl, Bruce; Van Leemput, Koen

    2015-07-15

    Automated analysis of MRI data of the subregions of the hippocampus requires computational atlases built at a higher resolution than those that are typically used in current neuroimaging studies. Here we describe the construction of a statistical atlas of the hippocampal formation at the subregion level using ultra-high resolution, ex vivo MRI. Fifteen autopsy samples were scanned at 0.13 mm isotropic resolution (on average) using customized hardware. The images were manually segmented into 13 different hippocampal substructures using a protocol specifically designed for this study; precise delineations were made possible by the extraordinary resolution of the scans. In addition to the subregions, manual annotations for neighboring structures (e.g., amygdala, cortex) were obtained from a separate dataset of in vivo, T1-weighted MRI scans of the whole brain (1mm resolution). The manual labels from the in vivo and ex vivo data were combined into a single computational atlas of the hippocampal formation with a novel atlas building algorithm based on Bayesian inference. The resulting atlas can be used to automatically segment the hippocampal subregions in structural MRI images, using an algorithm that can analyze multimodal data and adapt to variations in MRI contrast due to differences in acquisition hardware or pulse sequences. The applicability of the atlas, which we are releasing as part of FreeSurfer (version 6.0), is demonstrated with experiments on three different publicly available datasets with different types of MRI contrast. The results show that the atlas and companion segmentation method: 1) can segment T1 and T2 images, as well as their combination, 2) replicate findings on mild cognitive impairment based on high-resolution T2 data, and 3) can discriminate between Alzheimer's disease subjects and elderly controls with 88% accuracy in standard resolution (1mm) T1 data, significantly outperforming the atlas in FreeSurfer version 5.3 (86% accuracy) and

  10. Multimodal MRI-Based Classification of Trauma Survivors with and without Post-Traumatic Stress Disorder.

    PubMed

    Zhang, Qiongmin; Wu, Qizhu; Zhu, Hongru; He, Ling; Huang, Hua; Zhang, Junran; Zhang, Wei

    2016-01-01

    Post-traumatic stress disorder (PTSD) is a debilitating psychiatric disorder. It can be difficult to discern the symptoms of PTSD and obtain an accurate diagnosis. Different magnetic resonance imaging (MRI) modalities focus on different aspects, which may provide complementary information for PTSD discrimination. However, none of the published studies assessed the diagnostic potential of multimodal MRI in identifying individuals with and without PTSD. In the current study, we investigated whether the complementary information conveyed by multimodal MRI scans could be combined to improve PTSD classification performance. Structural and resting-state functional MRI (rs-fMRI) scans were conducted on 17 PTSD patients, 20 trauma-exposed controls without PTSD (TEC) and 20 non-traumatized healthy controls (HC). Gray matter volume (GMV), amplitude of low-frequency fluctuations (ALFF), and regional homogeneity were extracted as classification features, and in order to integrate the information of structural and functional MRI data, the extracted features were combined by a multi-kernel combination strategy. Then a support vector machine (SVM) classifier was trained to distinguish the subjects at individual level. The performance of the classifier was evaluated using the leave-one-out cross-validation (LOOCV) method. In the pairwise comparison of PTSD, TEC, and HC groups, classification accuracies obtained by the proposed approach were 2.70, 2.50, and 2.71% higher than the best single feature way, with the accuracies of 89.19, 90.00, and 67.57% for PTSD vs. HC, TEC vs. HC, and PTSD vs. TEC respectively. The proposed approach could improve PTSD identification at individual level. Additionally, it provides preliminary support to develop the multimodal MRI method as a clinical diagnostic aid. PMID:27445664

  11. Multimodal MRI-Based Classification of Trauma Survivors with and without Post-Traumatic Stress Disorder

    PubMed Central

    Zhang, Qiongmin; Wu, Qizhu; Zhu, Hongru; He, Ling; Huang, Hua; Zhang, Junran; Zhang, Wei

    2016-01-01

    Post-traumatic stress disorder (PTSD) is a debilitating psychiatric disorder. It can be difficult to discern the symptoms of PTSD and obtain an accurate diagnosis. Different magnetic resonance imaging (MRI) modalities focus on different aspects, which may provide complementary information for PTSD discrimination. However, none of the published studies assessed the diagnostic potential of multimodal MRI in identifying individuals with and without PTSD. In the current study, we investigated whether the complementary information conveyed by multimodal MRI scans could be combined to improve PTSD classification performance. Structural and resting-state functional MRI (rs-fMRI) scans were conducted on 17 PTSD patients, 20 trauma-exposed controls without PTSD (TEC) and 20 non-traumatized healthy controls (HC). Gray matter volume (GMV), amplitude of low-frequency fluctuations (ALFF), and regional homogeneity were extracted as classification features, and in order to integrate the information of structural and functional MRI data, the extracted features were combined by a multi-kernel combination strategy. Then a support vector machine (SVM) classifier was trained to distinguish the subjects at individual level. The performance of the classifier was evaluated using the leave-one-out cross-validation (LOOCV) method. In the pairwise comparison of PTSD, TEC, and HC groups, classification accuracies obtained by the proposed approach were 2.70, 2.50, and 2.71% higher than the best single feature way, with the accuracies of 89.19, 90.00, and 67.57% for PTSD vs. HC, TEC vs. HC, and PTSD vs. TEC respectively. The proposed approach could improve PTSD identification at individual level. Additionally, it provides preliminary support to develop the multimodal MRI method as a clinical diagnostic aid. PMID:27445664

  12. A brain MRI atlas of the common squirrel monkey, Saimiri sciureus

    NASA Astrophysics Data System (ADS)

    Gao, Yurui; Schilling, Kurt G.; Khare, Shweta P.; Panda, Swetasudha; Choe, Ann S.; Stepniewska, Iwona; Li, Xia; Ding, Zhoahua; Anderson, Adam; Landman, Bennett A.

    2014-03-01

    The common squirrel monkey, Saimiri sciureus, is a New World monkey with functional and microstructural organization of central nervous system similar to that of humans. It is one of the most commonly used South American primates in biomedical research. Unlike its Old World macaque cousins, no digital atlases have described the organization of the squirrel monkey brain. Here, we present a multi-modal magnetic resonance imaging (MRI) atlas constructed from the brain of an adult female squirrel monkey. In vivo MRI acquisitions include high resolution T2 structural imaging and low resolution diffusion tensor imaging. Ex vivo MRI acquisitions include high resolution T2 structural imaging and high resolution diffusion tensor imaging. Cortical regions were manually annotated on the co-registered volumes based on published histological sections.

  13. Multimodal image registration of ex vivo 4 Tesla MRI with whole mount histology for prostate cancer detection

    NASA Astrophysics Data System (ADS)

    Chappelow, Jonathan; Madabhushi, Anant; Rosen, Mark; Tomaszeweski, John; Feldman, Michael

    2007-03-01

    In this paper we present novel methods for registration and subsequent evaluation of whole mount prostate histological sections to corresponding 4 Tesla ex vivo magnetic resonance imaging (MRI) slices to complement our existing computer-aided diagnosis (CAD) system for detection of prostatic adenocarcinoma from high resolution MRI. The CAD system is trained using voxels labeled as cancer on MRI by experts who visually aligned histology with MRI. To address voxel labeling errors on account of manual alignment and delineation, we have developed a registration method called combined feature ensemble mutual information (COFEMI) to automatically map spatial extent of prostate cancer from histology onto corresponding MRI for prostatectomy specimens. Our method improves over intensity-based similarity metrics (mutual information) by incorporating unique information from feature spaces that are relatively robust to intensity artifacts and which accentuate the structural details in the target and template images to be registered. Our registration algorithm accounts for linear gland deformations in the histological sections resulting from gland fixing and serial sectioning. Following automatic registration of MRI and histology, cancer extent from histological sections are mapped to the corresponding registered MRI slices. The manually delineated cancer areas on MRI obtained via manual alignment of histological sections and MRI are compared with corresponding cancer extent obtained via COFEMI by a novel registration evaluation technique based on use of non-linear dimensionality reduction (locally linear embedding (LLE)). The cancer map on MRI determined by COFEMI was found to be significantly more accurate compared to the manually determined cancer mask. The performance of COFEMI was also found to be superior compared to image intensity-based mutual information registration.

  14. The PRESTO technique for fMRI.

    PubMed

    van Gelderen, P; Duyn, J H; Ramsey, N F; Liu, G; Moonen, C T W

    2012-08-15

    In the early days of BOLD fMRI, the acquisition of T(2)(*) weighted data was greatly facilitated by rapid scan techniques such as EPI. The latter, however, was only available on a few MRI systems that were equipped with specialized hardware that allowed rapid switching of the imaging gradients. For this reason, soon after the invention of fMRI, the scan technique PRESTO was developed to make rapid T(2)(*) weighted scanning available on standard clinical scanners. This method combined echo shifting, which allows for echo times longer than the sequence repetition time, with acquisition of multiple k-space lines per excitation. These two concepts were combined in order to achieve a method fast enough for fMRI, while maintaining a sufficiently long echo time for optimal contrast. PRESTO has been primarily used for 3D scanning, which minimized the contribution of large vessels due to inflow effects. Although PRESTO is still being used today, its appeal has lessened somewhat due to increased gradient performance of modern MRI scanners. Compared to 2D EPI, PRESTO may have somewhat reduced temporal stability, which is a disadvantage for fMRI that may not outweigh the advantage of reduced inflow effects provided by 3D scanning. In this overview, the history of the development of the PRESTO is presented, followed by a qualitative comparison with EPI. PMID:22245350

  15. Advanced flow MRI: emerging techniques and applications.

    PubMed

    Markl, M; Schnell, S; Wu, C; Bollache, E; Jarvis, K; Barker, A J; Robinson, J D; Rigsby, C K

    2016-08-01

    Magnetic resonance imaging (MRI) techniques provide non-invasive and non-ionising methods for the highly accurate anatomical depiction of the heart and vessels throughout the cardiac cycle. In addition, the intrinsic sensitivity of MRI to motion offers the unique ability to acquire spatially registered blood flow simultaneously with the morphological data, within a single measurement. In clinical routine, flow MRI is typically accomplished using methods that resolve two spatial dimensions in individual planes and encode the time-resolved velocity in one principal direction, typically oriented perpendicular to the two-dimensional (2D) section. This review describes recently developed advanced MRI flow techniques, which allow for more comprehensive evaluation of blood flow characteristics, such as real-time flow imaging, 2D multiple-venc phase contrast MRI, four-dimensional (4D) flow MRI, quantification of complex haemodynamic properties, and highly accelerated flow imaging. Emerging techniques and novel applications are explored. In addition, applications of these new techniques for the improved evaluation of cardiovascular (aorta, pulmonary arteries, congenital heart disease, atrial fibrillation, coronary arteries) as well as cerebrovascular disease (intra-cranial arteries and veins) are presented. PMID:26944696

  16. Pediatric multifocal liver lesions evaluated by MRI

    PubMed Central

    Almotairi, Majed; Oudjhane, Kamaldine; Chavhan, Govind B

    2015-01-01

    Objective: The purpose of this study is to present our experience with MRI evaluation of multifocal liver lesions in children and describe the MRI characteristics of these lesions. Patients and Methods: A retrospective review of consecutive MRI exams performed for the evaluation of multiple liver lesions between 1 January 2007 and 31 December 2012 was done to note the number of lesions, the size of the largest lesion, MR signal characteristics, and background liver. Final diagnosis was assigned to each case based on pathology in the available cases and a combination of clinical features, imaging features, and follow-up in the remaining cases. Results: A total of 48 children (22 boys, 26 girls; age between 3 months and 18 years with average age 10.58 years and median age 11 years) were included in the study. Totally 51 lesion diagnoses were seen in 48 children that included 17 focal nodular hyperplasia (FNH), 8 hemangiomas, 7 metastases, 6 regenerative nodules, 3 adenomas, 3 abscesses, and one each of angiomyolipoma, epithelioid hemangioendothelioma, focal fatty infiltration, hepatocellular carcinoma, hepatic infarction, nodular regenerative hyperplasia, and hepatic cyst. Background liver was normal in 33, cirrhotic in 10, fatty in 3, and siderotic in 2 children. Most FNH, hemangiomas, and regenerative nodules showed characteristic MRI features, while metastases were variable in signal pattern. Conclusion: Many commonly seen multifocal liver lesions in children have characteristic MRI features. MRI can help to arrive at reasonable differential diagnoses for multifocal liver lesions in children and guide further investigation and management. PMID:26288526

  17. MRI atlas of the brain

    SciTech Connect

    Bradley, W.G. ); Bydder, G. )

    1990-01-01

    Since most radiologists will start from a basic of familiarity with pathophysiology of disease and a knowledge of cross-sectional imaging (at least in the transaxial plane), they are in a good position to recognize and diagnose many of the abnormalities we can currently see with CT. The appearance of these lesions on MRI is the basis for the majority of the images in this book. Chapters on Tumors, Infarcts and Ischemia, Demyelination and Infection. Hydrocephalus, and Pediatrics feature multiple images displaying the MR appearance of many common lesions with minimal associated text. Instead of focusing on pathophysiology, attention is directed to the variable appearance of these disease states using various MR imaging techniques. Although the MR contrast agent, Gadolinium-DTPA, has similar behavior (physiologically) to meglumine diatrizoate in CT, the MR techniques which result in optimal visualization of enhancing lesions are nonintuitive and are discussed. Similarly, the appearance of flowing blood and CSF and hemorrhage does not follow easily from a pre-existing CT base, therefore additional text has been devoted to these subjects.

  18. Development and assessment of a new 3D neuroanatomy teaching tool for MRI training.

    PubMed

    Drapkin, Zachary A; Lindgren, Kristen A; Lopez, Michael J; Stabio, Maureen E

    2015-01-01

    A computerized three-dimensional (3D) neuroanatomy teaching tool was developed for training medical students to identify subcortical structures on a magnetic resonance imaging (MRI) series of the human brain. This program allows the user to transition rapidly between two-dimensional (2D) MRI slices, 3D object composites, and a combined model in which 3D objects are overlaid onto the 2D MRI slices, all while rotating the brain in any direction and advancing through coronal, sagittal, or axial planes. The efficacy of this tool was assessed by comparing scores from an MRI identification quiz and survey in two groups of first-year medical students. The first group was taught using this new 3D teaching tool, and the second group was taught the same content for the same amount of time but with traditional methods, including 2D images of brain MRI slices and 3D models from widely used textbooks and online sources. Students from the experimental group performed marginally better than the control group on overall test score (P = 0.07) and significantly better on test scores extracted from questions involving C-shaped internal brain structures (P < 0.01). Experimental participants also expressed higher confidence in their abilities to visualize the 3D structure of the brain (P = 0.02) after using this tool. Furthermore, when surveyed, 100% of the students in the experimental group recommended this tool for future students. These results suggest that this neuroanatomy teaching tool is an effective way to train medical students to read an MRI of the brain and is particularly effective for teaching C-shaped internal brain structures.

  19. Active-contour-model-based edge restriction and attraction field regularization for brain MRI segmentation

    NASA Astrophysics Data System (ADS)

    Luan, H.; Qi, Feihu

    2004-11-01

    Constructing 3D models of the object of interest from brain MRI is useful in numerous biomedical imaging application. In general, the construction of the 3D models is generally carried out according to the contours obtained from a 2D segmentation of each MR slice, so the equality of the 3D model strongly depends on the precision of the segmentation process. Active contour model is an effective edge-based method in segmenting an object of interest. However, its application, which segment boundary of anatomical structure of brain MRI, encounters many difficulties due to undesirable properties of brain MRI, for example complex background, intensity inhomogeneity and discontinuous edges. This paper proposes an active contour model to solve the problems of automatically segmenting the object of interest from a brain MRI. In this proposed algorithm, a new method of calculating attraction field has been developed. This method is based on edge restriction and attraction field regularization. Edge restriction introduces prior knowledge about the object of interest to free contours of being affected by edges of other anatomical structures or spurious edges, while attraction field regularization enables our algorithm to extract boundary correctly even at the place, where the edge of object of interest is discontinuous, by diffusing the edge information gotten after edge restriction. When we apply this proposed algorithm to brain MRI, the result shows this proposed algorithm could overcome those difficulties we mentioned above and convergence to object boundary quickly and accurately.

  20. Imaging artifacts induced by electrical stimulation during conventional fMRI of the brain

    PubMed Central

    Antal, Andrea; Bikson, Marom; Datta, Abhishek; Lafon, Belen; Dechent, Peter; Parra, Lucas C.; Paulus, Walter

    2013-01-01

    Functional magnetic resonance imaging (fMRI) of brain activation during transcranial electrical stimulation is used to provide insight into the mechanisms of neuromodulation and targeting of particular brain structures. However, the passage of current through the body may interfere with the concurrent detection of blood oxygen level dependent (BOLD) signal, which is sensitive to local magnetic fields. To test whether these currents can affect concurrent fMRI recordings we performed conventional gradient echo-planar imaging (EPI) during transcranial direct current (tDCS) and alternating current stimulation (tACS) on two post-mortem subjects. TDCS induced signals in both superficial and deep structures. The signal was specific to the electrode montage, with the strongest signal near cerebrospinal fluid (CSF) and scalp. The direction of change relative to non-stimulation reversed with tDCS stimulation polarity. For tACS there was no net effect of the MRI signal. High-resolution individualized modeling of current flow and induced static magnetic fields suggested a strong coincidence of the change EPI signal with regions of large current density and magnetic fields. These initial results indicate that: 1) fMRI studies of tDCS must consider this potentially confounding interference from current flow and 2) conventional MRI imaging protocols can be potentially used to measure current flow during transcranial electrical stimulation. The optimization of current measurement and artifact correction techniques, including consideration of the underlying physics, remains to be addressed. PMID:23099102

  1. MRI Detects Brain Reorganization after Human Umbilical Tissue-Derived Cells (hUTC) Treatment of Stroke in Rat

    PubMed Central

    Jiang, Quan; Thiffault, Christine; Kramer, Brian C.; Ding, Guang Liang; Zhang, Li; Nejad-Davarani, Siamak P.; Li, Lian; Arbab, Ali S.; Lu, Mei; Navia, Brad; Victor, Stephen J.; Hong, Klaudyne; Li, Qing Jiang; Wang, Shi Yang; Li, Yi; Chopp, Michael

    2012-01-01

    Human umbilical tissue-derived cells (hUTC) represent an attractive cell source and a potential technology for neurorestoration and improvement of functional outcomes following stroke. Male Wistar rats were subjected to a transient middle cerebral artery occlusion (tMCAo) and were intravenously administered hUTC (N = 11) or vehicle (N = 10) 48 hrs after stroke. White matter and vascular reorganization was monitored over a 12-week period using MRI and histopathology. MRI results were correlated with neurological functional and histology outcomes to demonstrate that MRI can be a useful tool to measure structural recovery after stroke. MRI revealed a significant reduction in the ventricular volume expansion and improvement in cerebral blood flow (CBF) in the hUTC treated group compared to vehicle treated group. Treatment with hUTC resulted in histological and functional improvements as evidenced by enhanced expression of vWF and synaptophysin, and improved outcomes on behavioral tests. Significant correlations were detected between MRI ventricular volumes and histological lesion volume as well as number of apoptotic cells. A positive correlation was also observed between MRI CBF or cerebral blood volume (CBV) and histological synaptic density. Neurological functional tests were also significantly correlated with MRI ventricular volume and CBV. Our data demonstrated that MRI measurements can detect the effect of hUTC therapy on the brain reorganization and exhibited positive correlation with histological measurements of brain structural changes and functional behavioral tests after stroke. MRI ventricular volumes provided the most sensitive index in monitoring brain remodeling and treatment effects and highly correlated with histological and functional measurements. PMID:22900057

  2. "MRI Stealth" robot for prostate interventions.

    PubMed

    Stoianovici, Dan; Song, Danny; Petrisor, Doru; Ursu, Daniel; Mazilu, Dumitru; Muntener, Michael; Mutener, Michael; Schar, Michael; Patriciu, Alexandru

    2007-01-01

    The paper reports an important achievement in MRI instrumentation, a pneumatic, fully actuated robot located within the scanner alongside the patient and operating under remote control based on the images. Previous MRI robots commonly used piezoelectric actuation limiting their compatibility. Pneumatics is an ideal choice for MRI compatibility because it is decoupled from electromagnetism, but pneumatic actuators were hardly controllable. This achievement was possible due to a recent technology breakthrough, the invention of a new type of pneumatic motor, PneuStep 1, designed for the robot reported here with uncompromised MRI compatibility, high-precision, and medical safety. MrBot is one of the "MRI stealth" robots today (the second is described in this issue by Zangos et al.). Both of these systems are also multi-imager compatible, being able to operate with the imager of choice or cross-imaging modalities. For MRI compatibility the robot is exclusively constructed of nonmagnetic and dielectric materials such as plastics, ceramics, crystals, rubbers and is electricity free. Light-based encoding is used for feedback, so that all electric components are distally located outside the imager's room. MRI robots are modern, digital medical instruments in line with advanced imaging equipment and methods. These allow for accessing patients within closed bore scanners and performing interventions under direct (in scanner) imaging feedback. MRI robots could allow e.g. to biopsy small lesions imaged with cutting edge cancer imaging methods, or precisely deploy localized therapy at cancer foci. Our robot is the first to show the feasibility of fully automated in-scanner interventions. It is customized for the prostate and operates transperineally for needle interventions. It can accommodate various needle drivers for different percutaneous procedures such as biopsy, thermal ablations, or brachytherapy. The first needle driver is customized for fully automated low

  3. "MRI Stealth" robot for prostate interventions.

    PubMed

    Stoianovici, Dan; Song, Danny; Petrisor, Doru; Ursu, Daniel; Mazilu, Dumitru; Muntener, Michael; Mutener, Michael; Schar, Michael; Patriciu, Alexandru

    2007-01-01

    The paper reports an important achievement in MRI instrumentation, a pneumatic, fully actuated robot located within the scanner alongside the patient and operating under remote control based on the images. Previous MRI robots commonly used piezoelectric actuation limiting their compatibility. Pneumatics is an ideal choice for MRI compatibility because it is decoupled from electromagnetism, but pneumatic actuators were hardly controllable. This achievement was possible due to a recent technology breakthrough, the invention of a new type of pneumatic motor, PneuStep 1, designed for the robot reported here with uncompromised MRI compatibility, high-precision, and medical safety. MrBot is one of the "MRI stealth" robots today (the second is described in this issue by Zangos et al.). Both of these systems are also multi-imager compatible, being able to operate with the imager of choice or cross-imaging modalities. For MRI compatibility the robot is exclusively constructed of nonmagnetic and dielectric materials such as plastics, ceramics, crystals, rubbers and is electricity free. Light-based encoding is used for feedback, so that all electric components are distally located outside the imager's room. MRI robots are modern, digital medical instruments in line with advanced imaging equipment and methods. These allow for accessing patients within closed bore scanners and performing interventions under direct (in scanner) imaging feedback. MRI robots could allow e.g. to biopsy small lesions imaged with cutting edge cancer imaging methods, or precisely deploy localized therapy at cancer foci. Our robot is the first to show the feasibility of fully automated in-scanner interventions. It is customized for the prostate and operates transperineally for needle interventions. It can accommodate various needle drivers for different percutaneous procedures such as biopsy, thermal ablations, or brachytherapy. The first needle driver is customized for fully automated low

  4. Quantification of AES depth profiles by the MRI model

    NASA Astrophysics Data System (ADS)

    Kovač, Janez; Zalar, Anton; Praček, Borut

    2003-02-01

    The main physical effects that contribute to interface broadening in the sputter depth profiles of polycrystalline metallic multilayer structures were studied by comparison of measured and simulated AES depth profiles. An algorithm based on the so-called mixing-roughness-information depth (MRI) model was used to simulate AES depth profiles of Ni/Cr multilayer structures with different roughnesses of the initial surfaces. The simulated depth profiles were compared with measurements performed at two different depth profiling parameters on the Ni/Cr and Al/Ni/Cr multilayer structures with an initial surface roughness of about 1.0 and 21.5 nm, respectively. The comparison of simulated and measured depth profiles enabled us to separate and estimate different contributions to the interface broadening, as well as their dependence on the sputter depth. We found that roughness was the dominant factor related to depth resolution with respect to the information depth and atomic mixing contribution. The values of roughness introduced into the simulation algorithm coincided well with the values measured by AFM at the initial surface and after depth profiling. The results showed the capability of the simulation procedure based on the MRI model to separate and evaluate different contributions to the depth resolution.

  5. Reprint of "Quantitative evaluation of brain development using anatomical MRI and diffusion tensor imaging".

    PubMed

    Oishi, Kenichi; Faria, Andreia V; Yoshida, Shoko; Chang, Linda; Mori, Susumu

    2014-02-01

    The development of the brain is structure-specific, and the growth rate of each structure differs depending on the age of the subject. Magnetic resonance imaging (MRI) is often used to evaluate brain development because of the high spatial resolution and contrast that enable the observation of structure-specific developmental status. Currently, most clinical MRIs are evaluated qualitatively to assist in the clinical decision-making and diagnosis. The clinical MRI report usually does not provide quantitative values that can be used to monitor developmental status. Recently, the importance of image quantification to detect and evaluate mild-to-moderate anatomical abnormalities has been emphasized because these alterations are possibly related to several psychiatric disorders and learning disabilities. In the research arena, structural MRI and diffusion tensor imaging (DTI) have been widely applied to quantify brain development of the pediatric population. To interpret the values from these MR modalities, a "growth percentile chart," which describes the mean and standard deviation of the normal developmental curve for each anatomical structure, is required. Although efforts have been made to create such a growth percentile chart based on MRI and DTI, one of the greatest challenges is to standardize the anatomical boundaries of the measured anatomical structures. To avoid inter- and intra-reader variability about the anatomical boundary definition, and hence, to increase the precision of quantitative measurements, an automated structure parcellation method, customized for the neonatal and pediatric population, has been developed. This method enables quantification of multiple MR modalities using a common analytic framework. In this paper, the attempt to create an MRI- and a DTI-based growth percentile chart, followed by an application to investigate developmental abnormalities related to cerebral palsy, Williams syndrome, and Rett syndrome, have been introduced. Future

  6. Quantitative evaluation of brain development using anatomical MRI and diffusion tensor imaging.

    PubMed

    Oishi, Kenichi; Faria, Andreia V; Yoshida, Shoko; Chang, Linda; Mori, Susumu

    2013-11-01

    The development of the brain is structure-specific, and the growth rate of each structure differs depending on the age of the subject. Magnetic resonance imaging (MRI) is often used to evaluate brain development because of the high spatial resolution and contrast that enable the observation of structure-specific developmental status. Currently, most clinical MRIs are evaluated qualitatively to assist in the clinical decision-making and diagnosis. The clinical MRI report usually does not provide quantitative values that can be used to monitor developmental status. Recently, the importance of image quantification to detect and evaluate mild-to-moderate anatomical abnormalities has been emphasized because these alterations are possibly related to several psychiatric disorders and learning disabilities. In the research arena, structural MRI and diffusion tensor imaging (DTI) have been widely applied to quantify brain development of the pediatric population. To interpret the values from these MR modalities, a "growth percentile chart," which describes the mean and standard deviation of the normal developmental curve for each anatomical structure, is required. Although efforts have been made to create such a growth percentile chart based on MRI and DTI, one of the greatest challenges is to standardize the anatomical boundaries of the measured anatomical structures. To avoid inter- and intra-reader variability about the anatomical boundary definition, and hence, to increase the precision of quantitative measurements, an automated structure parcellation method, customized for the neonatal and pediatric population, has been developed. This method enables quantification of multiple MR modalities using a common analytic framework. In this paper, the attempt to create an MRI- and a DTI-based growth percentile chart, followed by an application to investigate developmental abnormalities related to cerebral palsy, Williams syndrome, and Rett syndrome, have been introduced. Future

  7. Sodium MRI in human heart: a review.

    PubMed

    Bottomley, Paul A

    2016-02-01

    This paper offers a critical review of the properties, methods and potential clinical application of sodium ((23)Na) MRI in human heart. Because the tissue sodium concentration (TSC) in heart is about ~40 µmol/g wet weight, and the (23)Na gyromagnetic ratio and sensitivity are respectively about one-quarter and one-11th of that of hydrogen ((1)H), the signal-to-noise ratio of (23)Na MRI in the heart is about one-6000th of that of conventional cardiac (1)H MRI. In addition, as a quadrupolar nucleus, (23)Na exhibits ultra-short and multi-component relaxation behavior (T1 ~ 30 ms; T2 ~ 0.5-4 ms and 12-20 ms), which requires fast, specialized, ultra-short echo-time MRI sequences, especially for quantifying TSC. Cardiac (23)Na MRI studies from 1.5 to 7 T measure a volume-weighted sum of intra- and extra-cellular components present at cytosolic concentrations of 10-15 mM and 135-150 mM in healthy tissue, respectively, at a spatial resolution of about 0.1-1 ml in 10 min or so. Currently, intra- and extra-cellular sodium cannot be unambiguously resolved without the use of potentially toxic shift reagents. Nevertheless, increases in TSC attributable to an influx of intra-cellular sodium and/or increased extra-cellular volume have been demonstrated in human myocardial infarction consistent with prior animal studies, and arguably might also be seen in future studies of ischemia and cardiomyopathies--especially those involving defects in sodium transport. While technical implementation remains a hurdle, a central question for clinical use is whether cardiac (23)Na MRI can deliver useful information unobtainable by other more convenient methods, including (1)H MRI.

  8. Multichannel compressive sensing MRI using noiselet encoding.

    PubMed

    Pawar, Kamlesh; Egan, Gary; Zhang, Jingxin

    2015-01-01

    The incoherence between measurement and sparsifying transform matrices and the restricted isometry property (RIP) of measurement matrix are two of the key factors in determining the performance of compressive sensing (CS). In CS-MRI, the randomly under-sampled Fourier matrix is used as the measurement matrix and the wavelet transform is usually used as sparsifying transform matrix. However, the incoherence between the randomly under-sampled Fourier matrix and the wavelet matrix is not optimal, which can deteriorate the performance of CS-MRI. Using the mathematical result that noiselets are maximally incoherent with wavelets, this paper introduces the noiselet unitary bases as the measurement matrix to improve the incoherence and RIP in CS-MRI. Based on an empirical RIP analysis that compares the multichannel noiselet and multichannel Fourier measurement matrices in CS-MRI, we propose a multichannel compressive sensing (MCS) framework to take the advantage of multichannel data acquisition used in MRI scanners. Simulations are presented in the MCS framework to compare the performance of noiselet encoding reconstructions and Fourier encoding reconstructions at different acceleration factors. The comparisons indicate that multichannel noiselet measurement matrix has better RIP than that of its Fourier counterpart, and that noiselet encoded MCS-MRI outperforms Fourier encoded MCS-MRI in preserving image resolution and can achieve higher acceleration factors. To demonstrate the feasibility of the proposed noiselet encoding scheme, a pulse sequences with tailored spatially selective RF excitation pulses was designed and implemented on a 3T scanner to acquire the data in the noiselet domain from a phantom and a human brain. The results indicate that noislet encoding preserves image resolution better than Fouirer encoding. PMID:25965548

  9. Multichannel compressive sensing MRI using noiselet encoding.

    PubMed

    Pawar, Kamlesh; Egan, Gary; Zhang, Jingxin

    2015-01-01

    The incoherence between measurement and sparsifying transform matrices and the restricted isometry property (RIP) of measurement matrix are two of the key factors in determining the performance of compressive sensing (CS). In CS-MRI, the randomly under-sampled Fourier matrix is used as the measurement matrix and the wavelet transform is usually used as sparsifying transform matrix. However, the incoherence between the randomly under-sampled Fourier matrix and the wavelet matrix is not optimal, which can deteriorate the performance of CS-MRI. Using the mathematical result that noiselets are maximally incoherent with wavelets, this paper introduces the noiselet unitary bases as the measurement matrix to improve the incoherence and RIP in CS-MRI. Based on an empirical RIP analysis that compares the multichannel noiselet and multichannel Fourier measurement matrices in CS-MRI, we propose a multichannel compressive sensing (MCS) framework to take the advantage of multichannel data acquisition used in MRI scanners. Simulations are presented in the MCS framework to compare the performance of noiselet encoding reconstructions and Fourier encoding reconstructions at different acceleration factors. The comparisons indicate that multichannel noiselet measurement matrix has better RIP than that of its Fourier counterpart, and that noiselet encoded MCS-MRI outperforms Fourier encoded MCS-MRI in preserving image resolution and can achieve higher acceleration factors. To demonstrate the feasibility of the proposed noiselet encoding scheme, a pulse sequences with tailored spatially selective RF excitation pulses was designed and implemented on a 3T scanner to acquire the data in the noiselet domain from a phantom and a human brain. The results indicate that noislet encoding preserves image resolution better than Fouirer encoding.

  10. Multichannel Compressive Sensing MRI Using Noiselet Encoding

    PubMed Central

    Pawar, Kamlesh; Egan, Gary; Zhang, Jingxin

    2015-01-01

    The incoherence between measurement and sparsifying transform matrices and the restricted isometry property (RIP) of measurement matrix are two of the key factors in determining the performance of compressive sensing (CS). In CS-MRI, the randomly under-sampled Fourier matrix is used as the measurement matrix and the wavelet transform is usually used as sparsifying transform matrix. However, the incoherence between the randomly under-sampled Fourier matrix and the wavelet matrix is not optimal, which can deteriorate the performance of CS-MRI. Using the mathematical result that noiselets are maximally incoherent with wavelets, this paper introduces the noiselet unitary bases as the measurement matrix to improve the incoherence and RIP in CS-MRI. Based on an empirical RIP analysis that compares the multichannel noiselet and multichannel Fourier measurement matrices in CS-MRI, we propose a multichannel compressive sensing (MCS) framework to take the advantage of multichannel data acquisition used in MRI scanners. Simulations are presented in the MCS framework to compare the performance of noiselet encoding reconstructions and Fourier encoding reconstructions at different acceleration factors. The comparisons indicate that multichannel noiselet measurement matrix has better RIP than that of its Fourier counterpart, and that noiselet encoded MCS-MRI outperforms Fourier encoded MCS-MRI in preserving image resolution and can achieve higher acceleration factors. To demonstrate the feasibility of the proposed noiselet encoding scheme, a pulse sequences with tailored spatially selective RF excitation pulses was designed and implemented on a 3T scanner to acquire the data in the noiselet domain from a phantom and a human brain. The results indicate that noislet encoding preserves image resolution better than Fouirer encoding. PMID:25965548

  11. COMPARISON OF THE COMPLETE FOURIER DIRECT MRI WITH EXISTING DIFFUSION WEIGHTED MRI METHODS

    PubMed Central

    Özcan, Alpay

    2011-01-01

    The Complete Fourier Direct (CFD) MRI method introduced in earlier work for modeling the diffusion weighted MRI signal is compared with the existing methods. The preservation of Hermitian symmetry in the diffusion weighted MRI signal without affecting its energy is the key point that differentiates CFD–MRI from the existing methods. By keeping the correct Fourier relationship intact, the joint distribution function is represented ‘as it is’, without any constraints, e.g. being symmetric. The necessity to model or assume models for spin motion and try to fit the model to the samples of the Fourier transform as in case of model matching methods is not required because the Discrete Fourier Transform applied to correctly processed signal in CFD–MRI gives more accurate results. PMID:21918715

  12. D-BRAIN: Anatomically Accurate Simulated Diffusion MRI Brain Data.

    PubMed

    Perrone, Daniele; Jeurissen, Ben; Aelterman, Jan; Roine, Timo; Sijbers, Jan; Pizurica, Aleksandra; Leemans, Alexander; Philips, Wilfried

    2016-01-01

    Diffusion Weighted (DW) MRI allows for the non-invasive study of water diffusion inside living tissues. As such, it is useful for the investigation of human brain white matter (WM) connectivity in vivo through fiber tractography (FT) algorithms. Many DW-MRI tailored restoration techniques and FT algorithms have been developed. However, it is not clear how accurately these methods reproduce the WM bundle characteristics in real-world conditions, such as in the presence of noise, partial volume effect, and a limited spatial and angular resolution. The difficulty lies in the lack of a realistic brain phantom on the one hand, and a sufficiently accurate way of modeling the acquisition-related degradation on the other. This paper proposes a software phantom that approximates a human brain to a high degree of realism and that can incorporate complex brain-like structural features. We refer to it as a Diffusion BRAIN (D-BRAIN) phantom. Also, we propose an accurate model of a (DW) MRI acquisition protocol to allow for validation of methods in realistic conditions with data imperfections. The phantom model simulates anatomical and diffusion properties for multiple brain tissue components, and can serve as a ground-truth to evaluate FT algorithms, among others. The simulation of the acquisition process allows one to include noise, partial volume effects, and limited spatial and angular resolution in the images. In this way, the effect of image artifacts on, for instance, fiber tractography can be investigated with great detail. The proposed framework enables reliable and quantitative evaluation of DW-MR image processing and FT algorithms at the level of large-scale WM structures. The effect of noise levels and other data characteristics on cortico-cortical connectivity and tractography-based grey matter parcellation can be investigated as well. PMID:26930054

  13. Brain scale-free properties in awake rest and NREM sleep: a simultaneous EEG/fMRI study.

    PubMed

    Lei, Xu; Wang, Yulin; Yuan, Hong; Chen, Antao

    2015-03-01

    Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) studies revealed that spontaneous activity in the brain has scale-invariant properties, as indicated by a frequency spectrum that follows a power-law distribution. However, current knowledge about the exact relationship between scaling properties in EEG and fMRI signals is very limited. To address this question, we collected simultaneous EEG-fMRI data in healthy individuals during resting wakefulness and non-rapid eye movement (NREM) sleep. For either of these conditions, we found that both EEG and fMRI power spectra followed a power-law distribution. Furthermore, the EEG and fMRI scaling exponents were highly variable across subjects, and sensitive to the choice of reference and nuisance variables in EEG and fMRI data, respectively. Interestingly, the EEG exponent of the whole brain selectively corresponded to the fMRI exponent of the thalamus during NREM sleep. Together, our findings suggest that scale-free brain activity is characterized by robust temporal structures and behavioral significance. This motivates future studies to unravel its physiological mechanisms, as well as its relevance to behavior.

  14. Impact of an Information Technology-Enabled Initiative on the Quality of Prostate Multiparametric MRI Reports

    PubMed Central

    Silveira, Patricia C.; Dunne, Ruth; Sainani, Nisha I.; Lacson, Ronilda; Silverman, Stuart G.; Tempany, Clare M.; Khorasani, Ramin

    2015-01-01

    Rationale and Objectives Assess the impact of implementing a structured report template and a computer-aided diagnosis (CAD) tool on the quality of prostate multiparametric MRI (mp-MRI) reports. Materials and Methods Institutional Review Board approval was obtained for this HIPAA-compliant study performed at an academic medical center. The study cohort included all prostate mp-MRI reports (n=385) finalized 6 months before and after implementation of a structured report template and a CAD tool (collectively the IT tools) integrated into the PACS workstation. Primary outcome measure was quality of prostate mp-MRI reports. An expert panel of our institution’s subspecialty trained abdominal radiologists defined prostate mp-MRI report quality as optimal, satisfactory or unsatisfactory based on documentation of 9 variables. Reports were reviewed to extract the predefined quality variables and determine whether the IT tools were used to create each report. Chi-square and Student’s t-tests were used to compare report quality before and after implementation of IT tools. Results The overall proportion of optimal or satisfactory reports increased from 29.8% (47/158) to 53.3% (121/227) (p<0.001) after implementing the IT tools. While the proportion of optimal or satisfactory reports increased among reports generated using at least one of the IT tools (47/158=[29.8%] vs. 105/161=[65.2%]; p<0.001), there was no change in quality among reports generated without use of the IT tools (47/158=[29.8%] vs. 16/66=[24.2%]; p=0.404). Conclusion The use of a structured template and CAD tool improved the quality of prostate mp-MRI reports compared to free-text report format and subjective measurement of contrast enhancement kinetic curve. PMID:25863794

  15. Large-Scale, High-Resolution Neurophysiological Maps Underlying fMRI of Macaque Temporal Lobe

    PubMed Central

    Papanastassiou, Alex M.; DiCarlo, James J.

    2013-01-01

    Maps obtained by functional magnetic resonance imaging (fMRI) are thought to reflect the underlying spatial layout of neural activity. However, previous studies have not been able to directly compare fMRI maps to high-resolution neurophysiological maps, particularly in higher level visual areas. Here, we used a novel stereo microfocal x-ray system to localize thousands of neural recordings across monkey inferior temporal cortex (IT), construct large-scale maps of neuronal object selectivity at subvoxel resolution, and compare those neurophysiology maps with fMRI maps from the same subjects. While neurophysiology maps contained reliable structure at the sub-millimeter scale, fMRI maps of object selectivity contained information at larger scales (>2.5 mm) and were only partly correlated with raw neurophysiology maps collected in the same subjects. However, spatial smoothing of neurophysiology maps more than doubled that correlation, while a variety of alternative transforms led to no significant improvement. Furthermore, raw spiking signals, once spatially smoothed, were as predictive of fMRI maps as local field potential signals. Thus, fMRI of the inferior temporal lobe reflects a spatially low-passed version of neurophysiology signals. These findings strongly validate the widespread use of fMRI for detecting large (>2.5 mm) neuronal domains of object selectivity but show that a complete understanding of even the most pure domains (e.g., faces vs nonface objects) requires investigation at fine scales that can currently only be obtained with invasive neurophysiological methods. PMID:24048850

  16. Modeling fMRI signals can provide insights into neural processing in the cerebral cortex

    PubMed Central

    Sharifian, Fariba; Heikkinen, Hanna; Vigário, Ricardo

    2015-01-01

    Every stimulus or task activates multiple areas in the mammalian cortex. These distributed activations can be measured with functional magnetic resonance imaging (fMRI), which has the best spatial resolution among the noninvasive brain imaging methods. Unfortunately, the relationship between the fMRI activations and distributed cortical processing has remained unclear, both because the coupling between neural and fMRI activations has remained poorly understood and because fMRI voxels are too large to directly sense the local neural events. To get an idea of the local processing given the macroscopic data, we need models to simulate the neural activity and to provide output that can be compared with fMRI data. Such models can describe neural mechanisms as mathematical functions between input and output in a specific system, with little correspondence to physiological mechanisms. Alternatively, models can be biomimetic, including biological details with straightforward correspondence to experimental data. After careful balancing between complexity, computational efficiency, and realism, a biomimetic simulation should be able to provide insight into how biological structures or functions contribute to actual data processing as well as to promote theory-driven neuroscience experiments. This review analyzes the requirements for validating system-level computational models with fMRI. In particular, we study mesoscopic biomimetic models, which include a limited set of details from real-life networks and enable system-level simulations of neural mass action. In addition, we discuss how recent developments in neurophysiology and biophysics may significantly advance the modelling of fMRI signals. PMID:25972586

  17. Toxic leukoencepha