Sample records for tesla mri scanner

  1. Occupational exposure of healthcare and research staff to static magnetic stray fields from 1.5–7 Tesla MRI scanners is associated with reporting of transient symptoms

    PubMed Central

    Schaap, Kristel; Christopher-de Vries, Yvette; Mason, Catherine K; de Vocht, Frank; Portengen, Lützen; Kromhout, Hans

    2014-01-01

    Objectives Limited data is available about incidence of acute transient symptoms associated with occupational exposure to static magnetic stray fields from MRI scanners. We aimed to assess the incidence of these symptoms among healthcare and research staff working with MRI scanners, and their association with static magnetic field exposure. Methods We performed an observational study among 361 employees of 14 clinical and research MRI facilities in The Netherlands. Each participant completed a diary during one or more work shifts inside and/or outside the MRI facility, reporting work activities and symptoms (from a list of potentially MRI-related symptoms, complemented with unrelated symptoms) experienced during a working day. We analysed 633 diaries. Exposure categories were defined by strength and type of MRI scanner, using non-MRI shifts as the reference category for statistical analysis. Non-MRI shifts originated from MRI staff who also participated on MRI days, as well as CT radiographers who never worked with MRI. Results Varying per exposure category, symptoms were reported during 16–39% of the MRI work shifts. We observed a positive association between scanner strength and reported symptoms among healthcare and research staff working with closed-bore MRI scanners of 1.5 Tesla (T) and higher (1.5?T OR=1.88; 3.0?T OR=2.14; 7.0?T OR=4.17). This finding was mainly driven by reporting of vertigo and metallic taste. Conclusions The results suggest an exposure-response association between exposure to strong static magnetic fields (and associated motion-induced time-varying magnetic fields) and reporting of transient symptoms on the same day of exposure. Trial registration number 11-032/C PMID:24714654

  2. An RF dosimeter for independent SAR measurement in MRI scanners

    SciTech Connect

    Qian, Di; Bottomley, Paul A. [Division of MR Research, Department of Radiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21287 and Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States)] [Division of MR Research, Department of Radiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21287 and Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); El-Sharkawy, AbdEl-Monem M.; Edelstein, William A., E-mail: w.edelstein@gmail.com [Division of MR Research, Department of Radiology, Johns Hopkins School of Medicine, Baltimore, Maryland 21287 (United States)

    2013-12-15

    Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B{sub 1}) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ?3%. With the torso landmarked at the xiphoid, human adult whole?body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on average independent of the imaging subject, albeit with fluctuations. Conclusions: Our 3T RF dosimeter and transducers accurately measure RF exposure in body-equivalent loads and provide scanner-independent assessments of whole-body RF power deposition for establishing safety compliance useful for MRI sequence and device testing.

  3. Repeated fMRI Using Iron Oxide Contrast Agent in Awake, Behaving Macaques at 3 Tesla

    Microsoft Academic Search

    Francisca P. Leite; Doris Tsao; Wim Vanduffel; Denis Fize; Yuka Sasaki; Larry L. Wald; Anders M. Dale; Ken K. Kwong; Guy A. Orban; Bruce R. Rosen; Roger B. H. Tootell; Joseph B. Mandeville

    2002-01-01

    Iron oxide contrast agents have been employed extensively in anesthetized rodents to enhance fMRI sensitivity and to study the physiology of cerebral blood volume (CBV) in relation to blood oxygen level-dependent (BOLD) signal following neuronal activation. This study quantified the advantages of exogenous agent for repeated neuroimaging in awake, nonhuman primates using a clinical 3 Tesla scanner. A monocrystalline iron

  4. Combined PET/MRI scanner

    DOEpatents

    Schlyer, David (Bellport, NY); Woody, Craig L. (Setauket, NY); Rooney, William (Miller Place, NY); Vaska, Paul (Sound Beach, NY); Stoll, Sean (Wading River, NY); Pratte, Jean-Francois (Stony Brook, NY); O'Connor, Paul (Bellport, NY)

    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.

  5. Rapid Proton Density Weighted Abdominal MRI at 3 Tesla With RF Non-Uniformity Correction , and K. S. Nayak1

    E-print Network

    Southern California, University of

    Rapid Proton Density Weighted Abdominal MRI at 3 Tesla With RF Non-Uniformity Correction H. H. Hu1. Experiments ­ A 30-cm sphere and bottles filled with doped water were imaged with an eight element torso and 20 seconds, respectively. All experiments were performed on a GE 3T scanner. Results ­ In Fig. 1A

  6. Mapping local hippocampal changes in Alzheimer's disease and normal ageing with MRI at 3 Tesla

    E-print Network

    Thompson, Paul

    Mapping local hippocampal changes in Alzheimer's disease and normal ageing with MRI at 3 Tesla and Alzheimer's disease based on high resolution MRI at 3 Tesla. T1-weighted images were acquired from 19

  7. BRIEF COMMUNICATION A 7 Tesla fMRI Study of Amygdala Responses to Fearful Faces

    E-print Network

    Hadjikhani, Nouchine

    BRIEF COMMUNICATION A 7 Tesla fMRI Study of Amygdala Responses to Fearful Faces Wietske van der field strength. In this study, the feasibility of fMRI in the amygdalae at 7 Tesla was investigated in a fearful face depends on stimulus duration. Keywords Amygdala Á fMRI Á 7 Tesla Á Fear Á Face perception

  8. 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. PMID:25227008

  9. 7 Tesla MRI in cerebral small vessel disease.

    PubMed

    Benjamin, Philip; Viessmann, Olivia; MacKinnon, Andrew D; Jezzard, Peter; Markus, Hugh S

    2015-07-01

    Cerebral small vessel disease (SVD) is a major cause of stroke and cognitive decline. Magnetic resonance imaging (MRI) currently plays a central role in diagnosis, and advanced MRI techniques are widely used in research but are limited by spatial resolution. Human 7 Tesla (7T) MRI has recently become available offering the ability to image at higher spatial resolution. This may provide additional insights into both the vascular pathology itself as well as parenchymal markers which could only previously be examined post mortem. In this review we cover the advantages and limitations of 7T MRI, review studies in SVD performed to date, and discuss potential future insights into SVD which 7T MRI may provide. PMID:25845965

  10. Development of a simultaneous PET\\/MRI scanner

    Microsoft Academic Search

    D. Schlyer; W. Rooney; C. Woody; P. Vaska; A. Kriplani; S. Stoll

    2004-01-01

    A combined magnetic resonance imaging (MRI) and positron emission tomography (PET) scanner would be a great benefit to nuclear medicine. The anatomical detail given by MRI and spectroscopy available with magnetic resonance spectroscopy (MRS) complement the quantitative physiological imaging obtained with PET. Such a device has not become a reality because of the incompatibilities of photomultiplier tubes (PMTs) and their

  11. Quantitative evaluation of ischemic myocardial scar tissue by unenhanced T1 mapping using 3.0 Tesla MR scanner

    PubMed Central

    Okur, Aylin; Kantarc?, Mecit; K?zrak, Ye?im; Y?ld?z, Sema; Pirimo?lu, Berhan; Karaca, Leyla; O?ul, Hayri; Sevimli, Serdar

    2014-01-01

    PURPOSE We aimed to use a noninvasive method for quantifying T1 values of chronic myocardial infarction scar by cardiac magnetic resonance imaging (MRI), and determine its diagnostic performance. MATERIALS AND METHODS We performed cardiac MRI on 29 consecutive patients with known coronary artery disease (CAD) on 3.0 Tesla MRI scanner. An unenhanced T1 mapping technique was used to calculate T1 relaxation time of myocardial scar tissue, and its diagnostic performance was evaluated. Chronic scar tissue was identified by delayed contrast-enhancement (DE) MRI and T2-weighted images. Sensitivity, specificity, and accuracy values were calculated for T1 mapping using DE images as the gold standard. RESULTS Four hundred and forty-two segments were analyzed in 26 patients. While myocardial chronic scar was demonstrated in 45 segments on DE images, T1 mapping MRI showed a chronic scar area in 54 segments. T1 relaxation time was higher in chronic scar tissue, compared with remote areas (1314±98 ms vs. 1099±90 ms, P < 0.001). Therefore, increased T1 values were shown in areas of myocardium colocalized with areas of DE and normal signal on T2-weighted images. There was a significant correlation between T1 mapping and DE images in evaluation of myocardial wall injury extent (P < 0.05). We calculated sensitivity, specificity, and accuracy as 95.5%, 97%, and 96%, respectively. CONCLUSION The results of the present study reveal that T1 mapping MRI combined with T2-weighted images might be a feasible imaging modality for detecting chronic myocardial infarction scar tissue. PMID:25010366

  12. A fiber-optic system for recording skin conductance in the MRI scanner.

    PubMed

    Lagopoulos, Jim; Malhi, Gin S; Shnier, Ronald C

    2005-11-01

    The acquisition of the skin conductance response (SCR) during functional magnetic resonance imaging (fMRI) raises significant safety issues, as well as practical ones, which need to be addressed in order for these experiments to be conducted safely and successfully. Metallic and conductive wires in the presence of time-varying gradient magnetic fields such as those present in fMRI experiments may induce heating, as well as electric fields, in these components and, if in contact with the subject, could produce severe burns and electric shocks. Moreover, these metallic and conductive components can significantly distort the magnetic field, resulting in image artifacts. A system for recording the SCR in humans simultaneously with fMRI is presented. The device is a fiber-optic-based transducer, which records the SCR from two fingers of the same hand, using electrodes containing inline radio frequency (RF) suppression filters and protective resistive loads. The fiber-optic SCR transducer was tested using 1.5 and 3.0 Tesla MRI scanners running EPI sequences. This system was able to safely record SCRs free of RF interference during an fMRI experiment, and the fiber-optic design of the transducer eliminated any artifacts on the MRI scan. PMID:16629299

  13. MAPPING HUMAN BRAIN FUNCTION WITH MRI AT 7 TESLA Xiaoping HU, Essa YACOUB, Josef PFEUFFER, Amir SCHUMEL,

    E-print Network

    MAPPING HUMAN BRAIN FUNCTION WITH MRI AT 7 TESLA Xiaoping HU, Essa YACOUB, Josef PFEUFFER, Amir of the BOLD response to neural activity increase with the field strength. With the establishment of a 7 Tesla at a magnetic field strength that significantly exceeds 4 Tesla. Functional mapping using echo-planar imaging

  14. Dynamic MRI of the temporomandibular joint at 3 Tesla using a gradient echo sequence , J. L. Go2

    E-print Network

    Southern California, University of

    -time gradient echo (GRE) imaging at 3 Tesla. Methods and Results Experiments were performed on a GE Signa ExciteDynamic MRI of the temporomandibular joint at 3 Tesla using a gradient echo sequence Y-C. Kim1 , J sequence at 1.5 Tesla [1]. In this work, we report our preliminary studies on the feasibility of a real

  15. 7-Tesla MRI demonstrates absence of structural lesions in patients with vestibular paroxysmia

    PubMed Central

    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. PMID:26106306

  16. Functional MRI at 1.5 tesla: A comparison of the blood oxygenation level-dependent signal

    E-print Network

    Krubitzer, Leah A.

    Functional MRI at 1.5 tesla: A comparison of the blood oxygenation level-dependent signal) How well does the functional MRI (fMRI) signal reflect underlying electrophysiology? Despite cortical maps generated based on the indirect blood oxygenation level-dependent signal of fMRI with maps

  17. Vestibular Effects of a 7 Tesla MRI Examination Compared to 1.5 T and 0 T in Healthy Volunteers

    PubMed Central

    Theysohn, Jens M.; Kraff, Oliver; Eilers, Kristina; Andrade, Dorian; Gerwig, Marcus; Timmann, Dagmar; Schmitt, Franz; Ladd, Mark E.; Ladd, Susanne C.; Bitz, Andreas K.

    2014-01-01

    Ultra-high-field MRI (7 Tesla (T) and above) elicits more temporary side-effects compared to 1.5 T and 3 T, e.g. dizziness or “postural instability” even after exiting the scanner. The current study aims to assess quantitatively vestibular performance before and after exposure to different MRI scenarios at 7 T, 1.5 T and 0 T. Sway path and body axis rotation (Unterberger's stepping test) were quantitatively recorded in a total of 46 volunteers before, 2 minutes after, and 15 minutes after different exposure scenarios: 7 T head MRI (n?=?27), 7 T no RF (n?=?22), 7 T only B0 (n?=?20), 7 T in & out B0 (n?=?20), 1.5 T no RF (n?=?20), 0 T (n?=?15). All exposure scenarios lasted 30 minutes except for brief one minute exposure in 7 T in & out B0. Both measures were documented utilizing a 3D ultrasound system. During sway path evaluation, the experiment was repeated with eyes both open and closed. Sway paths for all long-lasting 7 T scenarios (normal, no RF, only B0) with eyes closed were significantly prolonged 2 minutes after exiting the scanner, normalizing after 15 minutes. Brief exposure to 7 T B0 or 30 minutes exposure to 1.5 T or 0 T did not show significant changes. End positions after Unterberger's stepping test were significantly changed counter-clockwise after all 7 T scenarios, including the brief in & out B0 exposure. Shorter exposure resulted in a smaller alteration angle. In contrast to sway path, reversal of changes in body axis rotation was incomplete after 15 minutes. 1.5 T caused no rotational changes. The results show that exposure to the 7 Tesla static magnetic field causes only a temporary dysfunction or “over-compensation” of the vestibular system not measurable at 1.5 or 0 Tesla. Radiofrequency fields, gradient switching, and orthostatic dysregulation do not seem to play a role. PMID:24658179

  18. 7 Tesla fMRI Reveals Systematic Functional Organization for Binocular Disparity in Dorsal Visual Cortex

    E-print Network

    Goncalves, Nuno R.; Ban, Hiroshi; Sánchez-Panchuelo, Rosa M.; Francis, Susan T.; Schluppeck, Denis; Welchman, Andrew E.

    2015-02-18

    animal models, comparatively little is known about the local architecture of stereoscopic processing in the human brain. Here, we take advantage of the high spatial specificity and image contrast offered by 7 tesla fMRI to test for systematic organization...

  19. Real-Time Cardiac MRI at 3 Tesla Krishna S. Nayak,1,2* Charles H. Cunningham,1

    E-print Network

    Southern California, University of

    Real-Time Cardiac MRI at 3 Tesla Krishna S. Nayak,1,2* Charles H. Cunningham,1 Juan M. Santos,1, phantom, and in vivo results are presented. MATERIALS AND METHODS Experiments were performed on a GE Signa

  20. 7 Tesla MRI with a Transmit/Receive Loopless Antenna and B1-Insensitive Selective Excitation

    PubMed Central

    Erturk, M. Arcan; El-Sharkawy, AbdEl-Monem M.; Moore, Jay; Bottomley, Paul A.

    2014-01-01

    Purpose Use of external coils with internal detectors or conductors is challenging at 7 Tesla (T) due to radiofrequency (RF) field (B1) penetration, B1-inhomogeneity, mutual coupling, and potential local RF heating. The present study tests whether the near-quadratic gains in signal-to-noise ratio and field-of-view with field-strength previously reported for internal loopless antennae at 7T can suffice to perform MRI with an interventional transmit/receive antenna without using any external coils. Methods External coils were replaced by semi-rigid or biocompatible transmit/receive loopless antennae requiring only a few Watts of peak RF power. Slice selection was provided by spatially selective B1-insensitive composite RF pulses that compensate for the antenna’s intrinsically nonuniform B1-field. Power was adjusted to maintain local temperature rise ?1° C. Fruit, intravascular MRI of diseased human vessels in vitro, and MRI of rabbit aorta in vivo are demonstrated. Results Scout MRI with the transmit/receive antennae yielded a ?10 cm cylindrical field-of-view, enabling subsequent targeted localization at ~100 ?m resolution in 10-50 s and/or 50 ?m MRI in ~2 min in vitro, and 100–300 ?m MRI of the rabbit aorta in vivo. Conclusion A simple, low-power, one-device approach to interventional MRI at 7T offers the potential of truly high-resolution MRI, while avoiding issues with external coil excitation and interactions at 7T. PMID:23963978

  1. Design and development of a respiratory monitoring device to be used in conjuction with MRI scanners

    Microsoft Academic Search

    Aidan McNally

    2004-01-01

    The aim of this project was to design and manufacture a respiratory monitoring device that operates in conjunction with MRI scanners to produce higher quality images. The resultant quality of many MRI images depends on how well the patient can control their breathing activity. This research has been successful in designing and manufacturing a device that can be used to

  2. System for Prostate Brachytherapy and Biopsy in a Standard 1.5 T MRI Scanner

    E-print Network

    Atalar, Ergin

    System for Prostate Brachytherapy and Biopsy in a Standard 1.5 T MRI Scanner Robert C. Susil,1-dose-rate (HDR) prostate brachytherapy and needle biopsy in a standard 1.5 T MRI scan- ner is demonstrated. In each of eight procedures (in four pa- tients with intermediate to high risk localized prostate cancer

  3. Validation of radiocarpal joint contact models based on images from a clinical MRI scanner

    Microsoft Academic Search

    Joshua E. Johnson; Terence E. McIff; Phil Lee; E. Bruce Toby; Kenneth J. Fischer

    2012-01-01

    This study was undertaken to assess magnetic resonance imaging (MRI)-based radiocarpal surface contact models of functional loading in a clinical MRI scanner for future in vivo studies, by comparison with experimental measures from three cadaver forearm specimens. Experimental data were acquired using a Tekscan sensor during simulated light grasp. Magnetic resonance (MR) images were used to obtain model geometry and

  4. EEG–MRI Co-registration and Sensor Labeling Using a 3D Laser Scanner

    Microsoft Academic Search

    L. Koessler; T. Cecchin; O. Caspary; A. Benhadid; H. Vespignani; L. Maillard

    2011-01-01

    This paper deals with the co-registration of an MRI scan with EEG sensors. We set out to evaluate the effectiveness of a 3D\\u000a handheld laser scanner, a device that is not widely used for co-registration, applying a semi-automatic procedure that also\\u000a labels EEG sensors. The scanner acquired the sensors’ positions and the face shape, and the scalp mesh was obtained

  5. Acoustic analysis of a gradient coil winding in an MRI scanner

    Microsoft Academic Search

    W. Shao; C. K. Mechefske

    2005-01-01

    An analytical model for the acoustic radiation from finite cylindrical ducts with infinite flanges is presented in this article. This model will be used for the design of low-noise gradient coils for MRI scanners. The expression of the sound field inside the duct satisfies the boundary conditions at the wall and at the open ends. The wave reflection phenomenon at

  6. Transrectal Prostate Biopsy and Fiducial Marker Placement in a Standard 1.5T MRI Scanner

    E-print Network

    Whitcomb, Louis L.

    Transrectal Prostate Biopsy and Fiducial Marker Placement in a Standard 1.5T MRI Scanner Robert C-mail: eatalar@jhu.edu Supported in part by Sup U.S. Army Prostate Cancer Research Program Award DAMD17 #108095). Submission Type: Original Research #12;Transrectal Prostate Biopsy and Fiducial Marker Placement

  7. Recording of the Event-Related Potentials During Functional MRI at 3.0 Tesla Field Strength

    E-print Network

    Gabrieli, John

    electromagnetic fields (here measured by event- related potentials (ERP)) and the hemodynamic response (hereRecording of the Event-Related Potentials During Functional MRI at 3.0 Tesla Field Strength F-ballistic effect; filtering; multi-modal imaging Measurable correlates of neuronal activation in the brain include

  8. Clinical Evaluation of Stereotactic Target Localization Using 3-Tesla MRI for Radiosurgery Planning

    SciTech Connect

    MacFadden, Derek [University of Toronto Faculty of Medicine, Toronto, ON (Canada); Zhang Beibei; Brock, Kristy K. [Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, ON (Canada); Hodaie, Mojgan [Division of Neurosurgery, Toronto Western Hospital, Toronto, ON (Canada); Laperriere, Normand [Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, ON (Canada); Department of Radiation Oncology, University of Toronto, Toronto, ON (Canada); Schwartz, Michael [Division of Neurosurgery, Toronto Western Hospital, Toronto, ON (Canada); Tsao, May [Department of Radiation Oncology, University of Toronto, Toronto, ON (Canada); Department of Radiation Oncology, Sunnybrook Regional Cancer Centre, Toronto, ON (Canada); Stainsby, Jeffrey [Applied Science Laboratories, GE Healthcare, Mississauga, ON (Canada); Lockwood, Gina [Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, ON (Canada); Mikulis, David [Department of Medical Imaging, University Health Network, Toronto, ON (Canada); Menard, Cynthia, E-mail: cynthia.menard@rmp.uhn.on.c [Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, ON (Canada); Department of Radiation Oncology, University of Toronto, Toronto, ON (Canada)

    2010-04-15

    Purpose: Increasing the magnetic resonance imaging (MRI) field strength can improve image resolution and quality, but concerns remain regarding the influence on geometric fidelity. The objectives of the present study were to spatially investigate the effect of 3-Tesla (3T) MRI on clinical target localization for stereotactic radiosurgery. Methods and Materials: A total of 39 patients were enrolled in a research ethics board-approved prospective clinical trial. Imaging (1.5T and 3T MRI and computed tomography) was performed after stereotactic frame placement. Stereotactic target localization at 1.5T vs. 3T was retrospectively analyzed in a representative cohort of patients with tumor (n = 4) and functional (n = 5) radiosurgical targets. The spatial congruency of the tumor gross target volumes was determined by the mean discrepancy between the average gross target volume surfaces at 1.5T and 3T. Reproducibility was assessed by the displacement from an averaged surface and volume congruency. Spatial congruency and the reproducibility of functional radiosurgical targets was determined by comparing the mean and standard deviation of the isocenter coordinates. Results: Overall, the mean absolute discrepancy across all patients was 0.67 mm (95% confidence interval, 0.51-0.83), significantly <1 mm (p < .010). No differences were found in the overall interuser target volume congruence (mean, 84% for 1.5T vs. 84% for 3T, p > .4), and the gross target volume surface mean displacements were similar within and between users. The overall average isocenter coordinate discrepancy for the functional targets at 1.5T and 3T was 0.33 mm (95% confidence interval, 0.20-0.48), with no patient-specific differences between the mean values (p >.2) or standard deviations (p >.1). Conclusion: Our results have provided clinically relevant evidence supporting the spatial validity of 3T MRI for use in stereotactic radiosurgery under the imaging conditions used.

  9. Development of a PET Scanner for Simultaneously Imaging Small Animals with MRI and PET

    PubMed Central

    Thompson, Christopher J; Goertzen, Andrew L; Thiessen, Jonathan D; Bishop, Daryl; Stortz, Greg; Kozlowski, Piotr; Retière, Fabrice; Zhang, Xuezhu; Sossi, Vesna

    2014-01-01

    Recently, positron emission tomography (PET) is playing an increasingly important role in the diagnosis and staging of cancer. Combined PET and X-ray computed tomography (PET-CT) scanners are now the modality of choice in cancer treatment planning. More recently, the combination of PET and magnetic resonance imaging (MRI) is being explored in many sites. Combining PET and MRI has presented many challenges since the photo-multiplier tubes (PMT) in PET do not function in high magnetic fields, and conventional PET detectors distort MRI images. Solid state light sensors like avalanche photo-diodes (APDs) and more recently silicon photo-multipliers (SiPMs) are much less sensitive to magnetic fields thus easing the compatibility issues. This paper presents the results of a group of Canadian scientists who are developing a PET detector ring which fits inside a high field small animal MRI scanner with the goal of providing simultaneous PET and MRI images of small rodents used in pre-clinical medical research. We discuss the evolution of both the crystal blocks (which detect annihilation photons from positron decay) and the SiPM array performance in the last four years which together combine to deliver significant system performance in terms of speed, energy and timing resolution. PMID:25120157

  10. Characterization of Ballistocardiogram Recorded at 1.5 and 3.0 Tesla in Simultaneous EEG-fMRI Zempel, J. M., Vincent, J. L., Larson-Prior, L. J., and Snyder, A. Z.

    E-print Network

    Larson-Prior, Linda

    Characterization of Ballistocardiogram Recorded at 1.5 and 3.0 Tesla in Simultaneous EEG of BKG at 1.5 and 3.0 Tesla: ·3 subjects Experimental protocol: ·Functional images were simultaneously in the scanner (1.5 and 3 Tesla) with the same EEG equipment (amplifier, cap, cables) in consecutive sessions. ·3

  11. Occupational exposure measurements of static and pulsed gradient magnetic fields in the vicinity of MRI scanners

    NASA Astrophysics Data System (ADS)

    Kännälä, Sami; Toivo, Tim; Alanko, Tommi; Jokela, Kari

    2009-04-01

    Recent advances in magnetic resonance imaging (MRI) have increased occupational exposure to magnetic fields. In this study, we examined the assessment of occupational exposure to gradient magnetic fields and time-varying magnetic fields generated by motion in non-homogeneous static magnetic fields of MRI scanners. These magnetic field components can be measured simultaneously with an induction coil setup that detects the time rate of change of magnetic flux density (dB/dt). The setup developed was used to measure the field components around two MRI units (1 T open and 3 T conventional). The measured values can be compared with dB/dt reference levels derived from magnetic flux density reference levels given by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The measured motion-induced dB/dt values were above the dB/dt reference levels for both MRI units. The measured values for the gradient fields (echo planar imaging (EPI) and fast field echo (FFE) sequences) also exceeded the dB/dt reference levels in positions where the medical staff may have access during interventional procedures. The highest motion-induced dB/dt values were 0.7 T s-1 for the 1 T scanner and 3 T s-1 for the 3 T scanner when only the static field was present. Even higher values (6.5 T s-1) were measured for simultaneous exposure to motion-induced and gradient fields in the vicinity of the 3 T scanner.

  12. Fast T2*-Weighted MRI of the Prostate at 3 Tesla

    PubMed Central

    Hardman, Rulon L.; El-Merhi, Fadi; Jung, Adam J.; Ware, Steve; Thompson, Ian M.; Friel, Harry T.; Peng, Qi

    2011-01-01

    Purpose To describe a rapid T2*-weighted (T2*W), three-dimensional (3D) echo planar imaging (EPI) sequence and its application in mapping local magnetic susceptibility variations in 3 Tesla (T) prostate MRI. To compare the sensitivity of T2*W EPI with routinely used T1-weighted turbo-spin echo sequence (T1W TSE) in detecting hemorrhage and the implications on sequences sensitive to field inhomogeneities such as MR spectroscopy (MRS). Materials and Methods B0 susceptibility weighted mapping was performed using a 3D EPI sequence featuring a 2D spatial excitation pulse with gradients of spiral k-space trajectory. A series of 11 subjects were imaged using 3T MRI and combination endorectal (ER) and six-channel phased array cardiac coils. T1W TSE and T2*W EPI sequences were analyzed quantitatively for hemorrhage contrast. Point resolved spectroscopy (PRESS MRS) was performed and data quality was analyzed. Results Two types of susceptibility variation were identified: hemorrhagic and nonhemorrhagic T2*W-positive areas. Post-biopsy hemorrhage lesions showed on average five times greater contrast on the T2*W images than T1W TSE images. Six nonhemorrhage regions of severe susceptibility artifact were apparent on the T2*W images that were not seen on standard T1W or T2W images. All nonhemorrhagic susceptibility artifact regions demonstrated compromised spectral quality on 3D MRS. Conclusion The fast T2*W EPI sequence identifies hemorrhagic and nonhemorrhagic areas of susceptibility variation that may be helpful in prostate MRI planning at 3.0T. PMID:21448956

  13. MRI-derived measurements of human subcortical, ventricular and intracranial brain volumes: Reliability effects of scan sessions, acquisition sequences, data analyses, scanner upgrade, scanner vendors and field strengths

    Microsoft Academic Search

    Jorge Jovicich; Silvester Czanner; Xiao Han; David Salat; Andre van der Kouwe; Brian Quinn; Jenni Pacheco; Marilyn Albert; Ronald Killiany; Deborah Blacker; Paul Maguire; Diana Rosas; Nikos Makris; Randy Gollub; Anders Dale; Bradford C. Dickerson; Bruce Fischl

    2009-01-01

    Automated MRI-derived measurements of in-vivo human brain volumes provide novel insights into normal and abnormal neuroanatomy, but little is known about measurement reliability. Here we assess the impact of image acquisition variables (scan session, MRI sequence, scanner upgrade, vendor and field strengths), FreeSurfer segmentation pre-processing variables (image averaging, B1 field inhomogeneity correction) and segmentation analysis variables (probabilistic atlas) on resultant

  14. High-resolution phased-array MRI of the human brain at 7 tesla: initial experience in multiple sclerosis patients

    Microsoft Academic Search

    Meredith Metcalf; Duan Xu; Darin T Okuda; Lucas Carvajal; Radhika Srinivasan; Douglas A C Kelley; Pratik Mukherjee; Sarah J Nelson; Daniel B Vigneron; Daniel Pelletier

    2010-01-01

    Recent advancement for magnetic resonance imaging (MRI) involves the incorporation of higher-field strengths. Although imagers with higher magnetic field strengths were developed and tested in research labs, the direct application to patient MR studies have been extremely limited. Imaging at 7 Tesla (7T) affords advantages in signal-to-noise ratio and image contrast and resolution; however, these benefits can only be realized

  15. Qualification test of a MPPC-based PET module for future MRI-PET scanners

    NASA Astrophysics Data System (ADS)

    Kurei, Y.; Kataoka, J.; Kato, T.; Fujita, T.; Funamoto, H.; Tsujikawa, T.; Yamamoto, S.

    2014-11-01

    We have developed a high-resolution, compact Positron Emission Tomography (PET) module for future use in MRI-PET scanners. The module consists of large-area, 4×4 ch MPPC arrays (Hamamatsu S11827-3344MG) optically coupled with Ce:LYSO scintillators fabricated into 12×12 matrices of 1×1 mm2 pixels. At this stage, a pair of module and coincidence circuits was assembled into an experimental prototype gantry arranged in a ring of 90 mm in diameter to form the MPPC-based PET system. The PET detector ring was then positioned around the RF coil of the 4.7 T MRI system. We took an image of a point 22Na source under fast spin echo (FSE) and gradient echo (GE), in order to measure interference between the MPPC-based PET and the MRI. We only found a slight degradation in the spatial resolution of the PET image from 1.63 to 1.70 mm (FWHM; x-direction), or 1.48-1.55 mm (FWHM; y-direction) when operating with the MRI, while the signal-to-noise ratio (SNR) of the MRI image was only degraded by 5%. These results encouraged us to develop a more advanced version of the MRI-PET gantry with eight MPPC-based PET modules, whose detailed design and first qualification test are also presented in this paper.

  16. Evaluation of Artifacts and Distortions of Titanium Applicators on 3.0-Tesla MRI: Feasibility of Titanium Applicators in MRI-Guided Brachytherapy for Gynecological Cancer

    SciTech Connect

    Kim, Yusung, E-mail: yusung-kim@uiowa.edu [Department of Radiation Oncology, University of Iowa, Iowa City, IA (United States); Muruganandham, Manickam; Modrick, Joseph M.; Bayouth, John E. [Department of Radiation Oncology, University of Iowa, Iowa City, IA (United States)

    2011-07-01

    Purpose: The aim of this study was to characterize the levels of artifacts and distortions of titanium applicators on 3.0-Tesla magnetic resonance imaging (MRI). Methods and Materials: Fletcher-Suit-Delclos-style tandem and ovoids (T and O) and tandem and ring applicator (T and R) were examined. The quality assurance (QA) phantoms for each applicator were designed and filled with copper sulphate solution (1.5 g/l). The artifacts were quantified with the registration of corresponding computed tomography (CT) images. A favorable MR sequence was searched in terms of artifacts. Using the sequence, the artifacts were determined. The geometric distortions induced by the applicators were quantified through each registration of CT and MRI without applicators. The artifacts of T and O were also evaluated on in vivo MRI datasets of 5 patients. Results: T1-weighted MRI with 1-mm slice thickness was found as a favorable MR sequence. Applying the sequence, the artifacts at the tandem tip of T and O and T and R were determined as 1.5 {+-} 0.5 mm in a superior direction in phantom studies. In the ovoids of T and O, we found artifacts less than 1.5 {+-} 0.5 mm. The artifacts of a T and O tandem in vivo were found as less than 2.6 {+-} 1.3 mm on T1-weighted MRI, whereas less than 6.9 {+-} 3.4 mm on T2-weighted MRI. No more than 1.2 {+-} 0.6 mm (3.0 {+-} 1.5 mm) of distortions, due to a titanium applicator, were measured on T1-weighted MRI (T2-). Conclusion: In 3.0-Tesla MRI, we found the artifact widths at the tip of tandem were less than 1.5 {+-} 0.5 mm for both T and O and T and R when using T1-weighted MRI in phantom studies. However, exclusive 3.0-Tesla MRI-guided brachytherapy planning with a titanium applicator should be cautiously implemented.

  17. Voltage-based Device Tracking in a 1.5 Tesla MRI during Imaging: Initial validation in swine models

    PubMed Central

    Schmidt, Ehud J; Tse, Zion TH; Reichlin, Tobias R; Michaud, Gregory F; Watkins, Ronald D; Butts-Pauly, Kim; Kwong, Raymond Y; Stevenson, William; Schweitzer, Jeffrey; Byrd, Israel; Dumoulin, Charles L

    2013-01-01

    Purpose Voltage-based device-tracking (VDT) systems are commonly used for tracking invasive devices in electrophysiological (EP) cardiac-arrhythmia therapy. During EP procedures, electro-anatomic-mapping (EAM) workstations provide guidance by integrating VDT location and intra-cardiac-ECG information with X-ray, CT, Ultrasound, and MR images. MR assists navigation, mapping and radio-frequency-ablation. Multi-modality interventions require multiple patient transfers between an MRI and the X-ray/ultrasound EP suite, increasing the likelihood of patient-motion and image mis-registration. An MRI-compatible VDT system may increase efficiency, since there is currently no single method to track devices both inside and outside the MRI scanner. Methods An MRI-compatible VDT system was constructed by modifying a commercial system. Hardware was added to reduce MRI gradient-ramp and radio-frequency-unblanking-pulse interference. VDT patches and cables were modified to reduce heating. Five swine cardiac VDT EAM-mapping interventions were performed, navigating inside and thereafter outside the MRI. Results Three-catheter VDT interventions were performed at >12 frames-per-second both inside and outside the MRI scanner with <3mm error. Catheters were followed on VDT- and MRI-derived maps. Simultaneous VDT and imaging was possible in repetition-time (TR) >32 msec sequences with <0.5mm errors, and <5% MRI SNR loss. At shorter TRs, only intra-cardiac-ECG was reliable. RF Heating was <1.5C°. Conclusion An MRI-compatible VDT system is feasible. PMID:23580479

  18. Validation of radiocarpal joint contact models based on images from a clinical MRI scanner

    PubMed Central

    Johnson, Joshua E.; McIff, Terence E.; Lee, Phil; Toby, E. Bruce; Fischer, Kenneth J.

    2012-01-01

    This study was undertaken to assess MRI-based radiocarpal surface contact models of functional loading in a clinical MRI scanner for future in vivo studies, by comparison with experimental measures from three cadaver forearm specimens. Experimental data was acquired using a Tekscan sensor during simulated light grasp. MR images were used to obtain model geometry and kinematics (image registration). Peak and average contact pressures, contact forces and contact areas were determined in the radiolunate and radioscaphoid joints. Contact area was also measured directly from MR images acquired with load and compared to model data. Based on the validation criteria (within 25% of experimental data), out of the six articulations (three specimens with two articulations each), two met the criterion for average contact pressure (0%, 14%); one for peak pressure (20%); one for contact force (5%); four for contact area with respect to experiment (8%, 13%, 19%, 23%), and three contact areas met the criterion with respect to direct measurements (14%, 21%, 21%). Absolute differences between model and experimental peak contact pressures were reasonably low (within 2.5 MPa). Overall, the results indicate that MRI-based models generated from 3T clinical MR scanner appear sufficient to obtain clinically relevant data. PMID:22631873

  19. Validation of radiocarpal joint contact models based on images from a clinical MRI scanner.

    PubMed

    Johnson, Joshua E; McIff, Terence E; Lee, Phil; Toby, E Bruce; Fischer, Kenneth J

    2014-01-01

    This study was undertaken to assess magnetic resonance imaging (MRI)-based radiocarpal surface contact models of functional loading in a clinical MRI scanner for future in vivo studies, by comparison with experimental measures from three cadaver forearm specimens. Experimental data were acquired using a Tekscan sensor during simulated light grasp. Magnetic resonance (MR) images were used to obtain model geometry and kinematics (image registration). Peak contact pressures (PPs) and average contact pressures (APs), contact forces and contact areas were determined in the radiolunate and radioscaphoid joints. Contact area was also measured directly from MR images acquired with load and compared with model data. Based on the validation criteria (within 25% of experimental data), out of the six articulations (three specimens with two articulations each), two met the criterion for AP (0%, 14%); one for peak pressure (20%); one for contact force (5%); four for contact area with respect to experiment (8%, 13%, 19% and 23%), and three contact areas met the criterion with respect to direct measurements (14%, 21% and 21%). Absolute differences between model and experimental PPs were reasonably low (within 2.5 MPa). Overall, the results indicate that MRI-based models generated from 3T clinical MR scanner appear sufficient to obtain clinically relevant data. PMID:22631873

  20. Effect of scanner acoustic background noise on strict resting-state fMRI

    PubMed Central

    Rondinoni, C.; Amaro, E.; Cendes, F.; Santos, A.C.dos; Salmon, C.E.G.

    2013-01-01

    Functional MRI (fMRI) resting-state experiments are aimed at identifying brain networks that support basal brain function. Although most investigators consider a ‘resting-state’ fMRI experiment with no specific external stimulation, subjects are unavoidably under heavy acoustic noise produced by the equipment. In the present study, we evaluated the influence of auditory input on the resting-state networks (RSNs). Twenty-two healthy subjects were scanned using two similar echo-planar imaging sequences in the same 3T MRI scanner: a default pulse sequence and a reduced “silent” pulse sequence. Experimental sessions consisted of two consecutive 7-min runs with noise conditions (default or silent) counterbalanced across subjects. A self-organizing group independent component analysis was applied to fMRI data in order to recognize the RSNs. The insula, left middle frontal gyrus and right precentral and left inferior parietal lobules showed significant differences in the voxel-wise comparison between RSNs depending on noise condition. In the presence of low-level noise, these areas Granger-cause oscillations in RSNs with cognitive implications (dorsal attention and entorhinal), while during high noise acquisition, these connectivities are reduced or inverted. Applying low noise MR acquisitions in research may allow the detection of subtle differences of the RSNs, with implications in experimental planning for resting-state studies, data analysis, and ergonomic factors. PMID:23579634

  1. Preliminary studies of a simultaneous PET/MRI scanner based on the RatCAP small animal tomograph

    NASA Astrophysics Data System (ADS)

    Woody, C.; Schlyer, D.; Vaska, P.; Tomasi, D.; Solis-Najera, S.; Rooney, W.; Pratte, J.-F.; Junnarkar, S.; Stoll, S.; Master, Z.; Purschke, M.; Park, S.-J.; Southekal, S.; Kriplani, A.; Krishnamoorthy, S.; Maramraju, S.; O'Connor, P.; Radeka, V.

    2007-02-01

    We are developing a scanner that will allow simultaneous acquisition of high resolution anatomical data using magnetic resonance imaging (MRI) and quantitative physiological data using positron emission tomography (PET). The approach is based on the technology used for the RatCAP conscious small animal PET tomograph which utilizes block detectors consisting of pixelated arrays of LSO crystals read out with matching arrays of avalanche photodiodes and a custom-designed ASIC. The version of this detector used for simultaneous PET/MRI imaging will be constructed out of all nonmagnetic materials and will be situated inside the MRI field. We have demonstrated that the PET detector and its electronics can be operated inside the MRI, and have obtained MRI images with various detector components located inside the MRI field. The MRI images show minimal distortion in this configuration even where some components still contain traces of certain magnetic materials. We plan to improve on the image quality in the future using completely non-magnetic components and by tuning the MRI pulse sequences. The combined result will be a highly compact, low mass PET scanner that can operate inside an MRI magnet without distorting the MRI image, and can be retrofitted into existing MRI instruments.

  2. Diffusion imaging of whole, post-mortem human brains on a clinical MRI scanner

    PubMed Central

    Miller, Karla L.; Stagg, Charlotte J.; Douaud, Gwenaëlle; Jbabdi, Saad; Smith, Stephen M.; Behrens, Timothy E.J.; Jenkinson, Mark; Chance, Steven A.; Esiri, Margaret M.; Voets, Natalie L.; Jenkinson, Ned; Aziz, Tipu Z.; Turner, Martin R.; Johansen-Berg, Heidi; McNab, Jennifer A.

    2011-01-01

    Diffusion imaging of post mortem brains has great potential both as a reference for brain specimens that undergo sectioning, and as a link between in vivo diffusion studies and “gold standard” histology/dissection. While there is a relatively mature literature on post mortem diffusion imaging of animals, human brains have proven more challenging due to their incompatibility with high-performance scanners. This study presents a method for post mortem diffusion imaging of whole, human brains using a clinical 3-Tesla scanner with a 3D segmented EPI spin-echo sequence. Results in eleven brains at 0.94 × 0.94 × 0.94 mm resolution are presented, and in a single brain at 0.73 × 0.73 × 0.73 mm resolution. Region-of-interest analysis of diffusion tensor parameters indicate that these properties are altered compared to in vivo (reduced diffusivity and anisotropy), with significant dependence on post mortem interval (time from death to fixation). Despite these alterations, diffusion tractography of several major tracts is successfully demonstrated at both resolutions. We also report novel findings of cortical anisotropy and partial volume effects. PMID:21473920

  3. 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.

  4. MRI-derived measurements of human subcortical, ventricular and intracranial brain volumes: Reliability effects of scan sessions, acquisition sequences, data analyses, scanner upgrade, scanner vendors and field strengths.

    PubMed

    Jovicich, Jorge; Czanner, Silvester; Han, Xiao; Salat, David; van der Kouwe, Andre; Quinn, Brian; Pacheco, Jenni; Albert, Marilyn; Killiany, Ronald; Blacker, Deborah; Maguire, Paul; Rosas, Diana; Makris, Nikos; Gollub, Randy; Dale, Anders; Dickerson, Bradford C; Fischl, Bruce

    2009-05-15

    Automated MRI-derived measurements of in-vivo human brain volumes provide novel insights into normal and abnormal neuroanatomy, but little is known about measurement reliability. Here we assess the impact of image acquisition variables (scan session, MRI sequence, scanner upgrade, vendor and field strengths), FreeSurfer segmentation pre-processing variables (image averaging, B1 field inhomogeneity correction) and segmentation analysis variables (probabilistic atlas) on resultant image segmentation volumes from older (n=15, mean age 69.5) and younger (both n=5, mean ages 34 and 36.5) healthy subjects. The variability between hippocampal, thalamic, caudate, putamen, lateral ventricular and total intracranial volume measures across sessions on the same scanner on different days is less than 4.3% for the older group and less than 2.3% for the younger group. Within-scanner measurements are remarkably reliable across scan sessions, being minimally affected by averaging of multiple acquisitions, B1 correction, acquisition sequence (MPRAGE vs. multi-echo-FLASH), major scanner upgrades (Sonata-Avanto, Trio-TrioTIM), and segmentation atlas (MPRAGE or multi-echo-FLASH). Volume measurements across platforms (Siemens Sonata vs. GE Signa) and field strengths (1.5 T vs. 3 T) result in a volume difference bias but with a comparable variance as that measured within-scanner, implying that multi-site studies may not necessarily require a much larger sample to detect a specific effect. These results suggest that volumes derived from automated segmentation of T1-weighted structural images are reliable measures within the same scanner platform, even after upgrades; however, combining data across platform and across field-strength introduces a bias that should be considered in the design of multi-site studies, such as clinical drug trials. The results derived from the young groups (scanner upgrade effects and B1 inhomogeneity correction effects) should be considered as preliminary and in need for further validation with a larger dataset. PMID:19233293

  5. Simultaneous PET/MR body imaging in rats: initial experiences with an integrated PET/MRI scanner.

    PubMed

    Tatsumi, Mitsuaki; Yamamoto, Seiichi; Imaizumi, Masao; Watabe, Tadashi; Kanai, Yasukazu; Aoki, Masaaki; Kato, Hiroki; Shimosegawa, Eku; Hatazawa, Jun

    2012-02-23

    OBJECTIVE: We recently developed an integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) (iPET/MRI) scanner for small animals, which had relatively large field-of-view (FOV) covering up to the size of a rat body. The purpose of this study was to report results of simultaneous PET/MRI of a rat body using this scanner with some radiotracers. METHODS: C-11-methionine (MET), F-18-fluorodeoxyglucose (FDG), or F-18-sodium fluoride (NaF) was injected as a radiotracer for PET portion in addition to gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid, a hepatobiliary contrast agent, for MRI portion. Simultaneous PET/MRI was performed in normal rats. PET, MRI, and co-registered fusion images were evaluated regarding image quality and feasibility for rat imaging studies. RESULTS: MET uptake was clearly shown in the liver and pancreas, which was confirmed with magnetic resonance (MR) and fused PET/MR images. PET/MR images depicted intense FDG uptake in the brain, Harderian glands, and myocardium. NaF uptake was observed in all bones and joints within FOV, except in ribs, which was well recognized with the help of MR and fused PET/MR images. CONCLUSION: This study demonstrated that simultaneous PET/MRI with an integrated dual-modality molecular imaging scanner was a feasible technique for imaging studies targeting on a rat body. However, further developments including attenuation correction methods are required to use this technique routinely in rat imaging studies. PMID:22359223

  6. The Spinal Curvature of Three Different Sitting Positions Analysed in an Open MRI Scanner

    PubMed Central

    Baumgartner, Daniel; Zemp, Roland; List, Renate; Stoop, Mirjam; Naxera, Jaroslav; Elsig, Jean Pierre; Lorenzetti, Silvio

    2012-01-01

    Sitting is the most frequently performed posture of everyday life. Biomechanical interactions with office chairs have therefore a long-term effect on our musculoskeletal system and ultimately on our health and wellbeing. This paper highlights the kinematic effect of office chairs on the spinal column and its single segments. Novel chair concepts with multiple degrees of freedom provide enhanced spinal mobility. The angular changes of the spinal column in the sagittal plane in three different sitting positions (forward inclined, reclined, and upright) for six healthy subjects (aged 23 to 45 years) were determined using an open magnetic resonance imaging (MRI) scanner. An MRI-compatible and commercially available office chair was adapted for use in the scanner. The midpoint coordinates of the vertebral bodies, the wedge angles of the intervertebral discs, and the lumbar lordotic angle were analysed. The mean lordotic angles were 16.0 ± 8.5° (mean ± standard deviation) in a forward inclined position, 24.7 ± 8.3° in an upright position, and 28.7 ± 8.1° in a reclined position. All segments from T10-T11 to L5-S1 were involved in movement during positional changes, whereas the range of motion in the lower lumbar segments was increased in comparison to the upper segments. PMID:23226980

  7. Feasibility study using MRI and two optical CT scanners for readout of polymer gel and PresageTM

    NASA Astrophysics Data System (ADS)

    Svensson, H.; Skyt, P. S.; Ceberg, S.; Doran, S.; Muren, L. P.; Balling, P.; Petersen, J. B. B.; Bäck, S. Å. J.

    2013-06-01

    The aim of this study was to compare the conventional combination of three-dimensional dosimeter (nPAG gel) and readout method (MRI) with other combinations of three-dimensional dosimeters (nPAG gel/PresageTM) and readout methods (optical CT scanners). In the first experiment, the dose readout of a gel irradiated with a four field-box technique was performed with both an Octopus IQ scanner and MRI. It was seen that the MRI readout agreed slightly better to the TPS. In another experiment, a gel and a PresageTM sample were irradiated with a VMAT field and read out using MRI and a fast laser scanner, respectively. A comparison between the TPS and the volumes revealed that the MRI/gel readout had closer resemblance to the TPS than the optical CT/PresageTM readout. There are clearly potential in the evaluated optical CT scanners, but more time has to be invested in the particular scanning scenario than was possible in this study.

  8. Relationship of clinical and cognitive variables with brain morphometric abnormalities in Alzheimer's disease: a voxel based morphometric study using 3-tesla MRI.

    PubMed

    Bagepally, Bhavani S; John, John P; Varghese, Mathew; Halahalli, Harsha N; Kota, Lakshminarayanan; Sivakumar, Palanimuthu T; Bharath, Srikala; Jain, Sanjeev

    2013-01-01

    Alzheimer's disease (AD) is associated with widespread structural and functional brain alterations. The current study examined the gray matter (GM) voxel based morphometric (VBM) correlates of cognitive and clinical severity scores in patients with AD. The study included 34 patients with AD according to NINCDS/ADRDA AD criteria and 28 matched elderly controls. All subjects were clinically evaluated using Hindi Mental Status Examination (HMSE), Everyday Abilities Scale for India (EASI) and the Clinical Dementia Rating (CDR) scale. The structural Magnetic Resonance Imaging (MRI) data were acquired using a 3 Tesla MRI scanner and VBM analysis was performed using VBM5.1 toolbox. The patients with AD had significantly lower GM volume, white matter volume and total brain volume as compared to controls. The HMSE scores were positively correlated (p=0.009) and EASI (p=0.04) & CDR (p=0.0004) were negatively correlated with the total GM volumes in patients with AD. The VBM analysis revealed diffuse GM atrophy in patients with AD. Frontal& temporal GM volumes were positively correlated with the HMSE scores. Thus the results of the study replicate the previous observations of generalized GM atrophy, in an Indian sample with AD. The cognitive decline, clinical dementia severity and impairment in activities of daily living were correlated whole brain GM and WM volumes as well as with specific brain regional atrophy in AD. However further studies with larger samples & with more detailed cognitive evaluation are required for confirmation & validation of the relationship between regional morphometric abnormalities and cognitive deficits in AD. PMID:24124629

  9. Studies of the interactions of an MRI system with the shielding in a combined PET/MRI scanner

    PubMed Central

    Peng, Bo J.; Walton, Jeffrey H.; Cherry, Simon R.; Willig-Onwuachi, Jacob

    2010-01-01

    A positron emission tomography (PET) system or ‘insert’ has been constructed for placement and operation in the bore of a small animal magnetic resonance imaging (MRI) scanner to allow simultaneous MR and PET imaging. The insert contains electronics, components with a variety of magnetic properties, and large continuous sheets of metal— all characteristics of an object that should, by conventional wisdom, never be placed in the bore of an MR scanner, especially near the imaging volume. There are a variety of ways the two systems might be expected to interact that could negatively impact the performance of either or both. In this article, the interaction mechanisms, particularly the impacts of the PET insert and shielding on MR imaging, are defined and explored. Additionally, some of the difficulties in quantifying errors introduced into the MR images as a result of the presence of the PET components are demonstrated. Several different approaches are used to characterize image artifacts and determine optimal placement of the shielding. Data are also presented that suggest ways the shielding could be modified to reduce errors and enable placement closer to the isocenter of the magnet. PMID:20009193

  10. Measuring and shimming the magnetic field of a 4 Tesla MRI magnet 

    E-print Network

    Kyriazis, Georgios

    1993-01-01

    The Biomedical Magnetic Resonance Laboratory (BMRL) of the University of Illinois at Urbana-Champaign (UIUC) has ordered from the Texas Accelerator Center (TAC) a superconducting, self-shielded, solenoidal magnet with a maximum field of 4 Tesla...

  11. Measuring and shimming the magnetic field of a 4 Tesla MRI magnet

    E-print Network

    Kyriazis, Georgios

    1993-01-01

    The Biomedical Magnetic Resonance Laboratory (BMRL) of the University of Illinois at Urbana-Champaign (UIUC) has ordered from the Texas Accelerator Center (TAC) a superconducting, self-shielded, solenoidal magnet with a maximum field of 4 Tesla...

  12. Journal of Neuroscience Methods 169 (2008) 7683 Visual stimulus presentation using fiber optics in the MRI scanner

    E-print Network

    Sereno, Martin

    2008-01-01

    Journal of Neuroscience Methods 169 (2008) 76­83 Visual stimulus presentation using fiber optics-face space using fiber optics in the MRI scanner. The feasibility of fiber-optic based displays-encoded paradigms in both experiments. The results suggest that fiber-optic based displays can be a complementary

  13. CHARACTERIZATION OF ACOUSTIC NOISE AND MAGNETIC FIELD FLUCTUATIONS IN A 4 T WHOLE-BODY MRI SCANNER

    Microsoft Academic Search

    CHRIS K. MECHEFSKE; Yuhua Wu; Brian Rutt

    2002-01-01

    High-field, high-speed magnetic resonance imaging (MRI) can generate high levels of sound within and around the scanner. The process that produces the gradient magnetic field is the primary cause of this noise. With the push to greater background magnetic field strength and gradient field switching speed, in order to improve image quality and resolution, the noise situation is becoming worse.

  14. Inner experience in the scanner: can high fidelity apprehensions of inner experience be integrated with fMRI?

    PubMed Central

    Kühn, Simone; Fernyhough, Charles; Alderson-Day, Benjamin; Hurlburt, Russell T.

    2014-01-01

    To provide full accounts of human experience and behavior, research in cognitive neuroscience must be linked to inner experience, but introspective reports of inner experience have often been found to be unreliable. The present case study aimed at providing proof of principle that introspection using one method, descriptive experience sampling (DES), can be reliably integrated with fMRI. A participant was trained in the DES method, followed by nine sessions of sampling within an MRI scanner. During moments where the DES interview revealed ongoing inner speaking, fMRI data reliably showed activation in classic speech processing areas including left inferior frontal gyrus. Further, the fMRI data validated the participant’s DES observations of the experiential distinction between inner speaking and innerly hearing her own voice. These results highlight the precision and validity of the DES method as a technique of exploring inner experience and the utility of combining such methods with fMRI. PMID:25538649

  15. A cradle-shaped gradient coil to expand the clear-bore width of an animal MRI scanner

    Microsoft Academic Search

    K. M. Gilbert; J. S. Gati; L. M. Klassen; R. S. Menon

    2010-01-01

    The never ending quest for higher magnetic field strengths in MRI and MRS has led to small and medium bore scanners at 9.4 T and above for both human and animal use; however, these bore diameters restrict the size of object that can be accommodated when using a conventional gradient coil. By replacing a cylindrical gradient-coil insert with a single-sided

  16. Superparamagnetic MRI probes for in vivo tracking of dendritic cell migration with a clinical 3 T scanner.

    PubMed

    Xu, Ye; Wu, Changqiang; Zhu, Wencheng; Xia, Chunchao; Wang, Dan; Zhang, Houbin; Wu, Jun; Lin, Gan; Wu, Bing; Gong, Qiyong; Song, Bin; Ai, Hua

    2015-07-01

    Dendritic cell (DC) based vaccines have shown promising results in the immunotherapy of cancers and other diseases. How to track the in vivo fate of DC vaccines will provide important insights to the final therapeutic results. In this study, we chose magnetic resonance imaging (MRI) to track murine DCs migration to the draining lymph node under a clinical 3 T scanner. Different from labeling immature DCs usually reported in literature, this study instead labeled matured DC with superparamagnetic iron oxide (SPIO) nanoparticle based imaging probes. The labeling process did not show negative impacts on cell viability, morphology, and surface biomarker expression. To overcome the imaging challenges brought by the limitations of the scanner, the size of lymph node, and the number of labeled cell, we optimized MRI pulse sequences. As a result, the signal reduction, caused either by gelatin phantoms containing as low as 12 SPIO-laden cells in each voxel or by the homing SPIO-laden DCs within the draining nodes after footpad injection of only 1 × 10(5) cells, can be clearly depicted under a 3 T MR scanner. Overall, the MRI labeling probes offer a low-toxic and high-efficient MR imaging platform for the assessment of DC-based immunotherapies. PMID:25941783

  17. Quantitative Apparent Diffusion Coefficient Measurements Obtained by 3-Tesla MRI Are Correlated with Biomarkers of Bladder Cancer Proliferative Activity

    PubMed Central

    Sevcenco, Sabina; Haitel, Andrea; Ponhold, Lothar; Susani, Martin; Fajkovic, Harun; Shariat, Shahrokh F.; Hiess, Manuela; Spick, Claudio; Szarvas, Tibor; Baltzer, Pascal A. T.

    2014-01-01

    Purpose To investigate the association between Apparent Diffusion Coefficient (ADC) values and cell cycle and proliferative biomarkers (p53, p21, Ki67,) in order to establish its potential role as a noninvasive biomarker for prediction of cell cycle, proliferative activity and biological aggressiveness in bladder cancer. Materials and Methods Patients with bladder cancer who underwent 3,0 Tesla DW-MRI of the bladder before TUR-B or radical cystectomy were eligible for this prospective IRB-approved study. Histological specimen were immunohistochemically stained for the following markers: p53, p21 and ki67. Two board-certified uropathologists reviewed the specimens blinded to DW-MRI results. Histological grade and T-stage were classified according to the WHO 2004 and the 2009 TNM classification, respectively. Nonparametric univariate and multivariate statistics including correlation, logistic regression and ROC analysis were applied. Results Muscle invasive bladder cancer was histologically confirmed in 10 out of 41 patients. All examined tissue biomarkers were significantly correlated with ADC values (p<0.05, respectively). Based on multivariate analysis, p53 and ADC are both independent prognostic factors for muscle invasiveness of bladder cancer (>/?=?T2). (p?=?0.013 and p?=?0.018). Conclusion ADC values are associated with cell cycle and proliferative biomarkers and do thereby reflect invasive and proliferative potential in bladder cancer. ADC and p53 are both independent prognostic factors for muscle invasiveness in bladder cancer. PMID:25202965

  18. Numerical field simulation for parallel transmission in MRI at 7 tesla

    E-print Network

    Bernier, Jessica A. (Jessica Ashley)

    2011-01-01

    Parallel transmission (pTx) is a promising improvement to coil design that has been demonstrated to mitigate B1* inhomogeneity, manifest as center brightening, for high-field magnetic resonance imaging (MRI). Parallel ...

  19. Iron Accumulation in Deep Cortical Layers Accounts for MRI Signal Abnormalities in ALS: Correlating 7 Tesla MRI and Pathology

    PubMed Central

    Kwan, Justin Y.; Jeong, Suh Young; Van Gelderen, Peter; Deng, Han-Xiang; Quezado, Martha M.; Danielian, Laura E.; Butman, John A.; Chen, Lingye; Bayat, Elham; Russell, James; Siddique, Teepu; Duyn, Jeff H.; Rouault, Tracey A.; Floeter, Mary Kay

    2012-01-01

    Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by cortical and spinal motor neuron dysfunction. Routine magnetic resonance imaging (MRI) studies have previously shown hypointense signal in the motor cortex on T2-weighted images in some ALS patients, however, the cause of this finding is unknown. To investigate the utility of this MR signal change as a marker of cortical motor neuron degeneration, signal abnormalities on 3T and 7T MR images of the brain were compared, and pathology was obtained in two ALS patients to determine the origin of the motor cortex hypointensity. Nineteen patients with clinically probable or definite ALS by El Escorial criteria and 19 healthy controls underwent 3T MRI. A 7T MRI scan was carried out on five ALS patients who had motor cortex hypointensity on the 3T FLAIR sequence and on three healthy controls. Postmortem 7T MRI of the brain was performed in one ALS patient and histological studies of the brains and spinal cords were obtained post-mortem in two patients. The motor cortex hypointensity on 3T FLAIR images was present in greater frequency in ALS patients. Increased hypointensity correlated with greater severity of upper motor neuron impairment. Analysis of 7T T2*-weighted gradient echo imaging localized the signal alteration to the deeper layers of the motor cortex in both ALS patients. Pathological studies showed increased iron accumulation in microglial cells in areas corresponding to the location of the signal changes on the 3T and 7T MRI of the motor cortex. These findings indicate that the motor cortex hypointensity on 3T MRI FLAIR images in ALS is due to increased iron accumulation by microglia. PMID:22529995

  20. Comparison of diffusion-weighted MRI acquisition techniques for normal pancreas at 3.0 Tesla

    PubMed Central

    Yao, Xiu-Zhong; Kuang, Tiantao; Wu, Li; Feng, Hao; Liu, Hao; Cheng, Wei-Zhong; Rao, Sheng-Xiang; Wang, He; Zeng, Meng-Su

    2014-01-01

    PURPOSE We aimed to optimize diffusion-weighted imaging (DWI) acquisitions for normal pancreas at 3.0 Tesla. MATERIALS AND METHODS Thirty healthy volunteers were examined using four DWI acquisition techniques with b values of 0 and 600 s/mm2 at 3.0 Tesla, including breath-hold DWI, respiratory-triggered DWI, respiratory-triggered DWI with inversion recovery (IR), and free-breathing DWI with IR. Artifacts, signal-to-noise ratio (SNR) and apparent diffusion coefficient (ADC) of normal pancreas were statistically evaluated among different DWI acquisitions. RESULTS Statistical differences were noticed in artifacts, SNR, and ADC values of normal pancreas among different DWI acquisitions by ANOVA (P < 0.001). Normal pancreas imaging had the lowest artifact in respiratory-triggered DWI with IR, the highest SNR in respiratory-triggered DWI, and the highest ADC value in free-breathing DWI with IR. The head, body, and tail of normal pancreas had statistically different ADC values on each DWI acquisition by ANOVA (P < 0.05). CONCLUSION The highest image quality for normal pancreas was obtained using respiratory-triggered DWI with IR. Normal pancreas displayed inhomogeneous ADC values along the head, body, and tail structures. PMID:25010365

  1. Assessment of MRI issues at 3-Tesla for metallic surgical implants: findings applied to 61 additional skin closure staples and vessel ligation clips

    PubMed Central

    2012-01-01

    Purpose Metallic skin closure staples and vessel ligation clips should be tested at 3-Tesla to characterize MRI issues in order to ensure patient safety. Therefore, metallic surgical implants were assessed at 3-Tesla for magnetic field interactions, MRI-related heating, and artifacts. Methods A skin closure staple (Visistat Skin Stapler, staple, Polytetrafluoroethylene, PTFE, coated 316L/316LVM stainless steel; Teleflex Medical, Durham, NC) and a vessel ligation clip (Hemoclip Traditional, stainless steel; Teleflex Medical, Durham, NC) that represented the largest metallic sizes made from materials with the highest magnetic susceptibilities (i.e., based on material information) among 61 other surgical implants (52 metallic implants, 9 nonmetallic implants) underwent evaluation for magnetic field interactions, MRI-related heating, and artifacts using standardized techniques. MRI-related heating was assessed by placing each implant in a gelled-saline-filled phantom with MRI performed using a transmit/receive RF body coil at an MR system reported, whole body averaged SAR of 2.9-W/kg for 15-min. Artifacts were characterized using T1-weighted, SE and GRE pulse sequences. Results Each surgical implant showed minor magnetic field interactions (20- and 27-degrees, which is acceptable from a safety consideration). Heating was not substantial (highest temperature change, ? 1.6°C). Artifacts may create issues if the area of interest is in the same area or close to the respective surgical implant. Conclusions The results demonstrated that it would be acceptable for patients with these metallic surgical implants to undergo MRI at 3-Tesla or less. Because of the materials and dimensions of the surgical implants that underwent testing, these findings pertain to 61 additional similar implants. PMID:22230200

  2. 3D 23Na MRI of human skeletal muscle at 7 Tesla: initial experience

    PubMed Central

    Wang, Ligong; Schweitzer, Mark E.; Regatte, Ravinder R.

    2013-01-01

    Objective To evaluate healthy skeletal muscle pre- and post-exercise via 7 T 23Na MRI and muscle proton T2 mapping, and to evaluate diabetic muscle pre- and post-exercise via 7 T 23Na MRI. Methods The calves of seven healthy subjects underwent imaging pre- and post-exercise via 7 T 23Na MRI (3D fast low angle shot, TR/TE=80 ms/0.160 ms, 4 mm × 4 mm × 4 mm) and 1 week later by 1H MRI (multiple spin-echo sequence, TR/TE=3,000 ms/15–90 ms). Four type 2 diabetics also participated in the 23Na MRI protocol. Pre- and post-exercise sodium signal intensity (SI) and proton T2 relaxation values were measured/calculated for soleus (S), gastrocnemius (G), and a control, tibialis anterior (TA). Two-tailed t tests were performed. Results In S/G in healthy subjects post-exercise, sodium SI increased 8–13% (p<0.03), then decreased (t1/2=22 min), and 1H T2 values increased 12–17% (p<0.03), then decreased (t1/2=12–15 min). In TA, no significant changes in sodium SI or 1H T2 values were seen (?2.4 to 1%, p>0.17). In S/G in diabetics, sodium SI increased 10–11% (p<0.04), then decreased (t1/2=27–37 min) without significant change in the TA SI (?3.6%, p= 0.066). Conclusion It is feasible to evaluate skeletal muscle via 3D 23Na MRI at 7 T. Post-exercise muscle 1H T2 values return to baseline more rapidly than sodium SI. Diabetics may demonstrate delayed muscle sodium SI recovery compared with healthy subjects. PMID:20309556

  3. A cradle-shaped gradient coil to expand the clear-bore width of an animal MRI scanner.

    PubMed

    Gilbert, K M; Gati, J S; Klassen, L M; Menon, R S

    2010-01-21

    The never ending quest for higher magnetic field strengths in MRI and MRS has led to small and medium bore scanners at 9.4 T and above for both human and animal use; however, these bore diameters restrict the size of object that can be accommodated when using a conventional gradient coil. By replacing a cylindrical gradient-coil insert with a single-sided gradient coil, the scanner's functionality can be extended to include localized imaging of wider samples. As a prototype, a three-axis, cradle-shaped gradient coil was designed, fabricated and implemented in a 9.4 T animal MRI scanner. Since gradient fields are required only to be monotonic over the desired field of view, the cradle gradient coil was designed to produce high gradient efficiencies (up to 2.25 mT m(-1) A(-1) over a 5 cm imaging region) at the expense of gradient linearity. A dedicated three-dimensional algorithm was developed to correct the resultant image distortion. Preliminary images of a grid phantom and a mouse demonstrated the fidelity of the algorithm in correcting image distortion of greater than 200%. Eddy currents were measured along each gradient axis. A large 65.2 (Hz mT(-1) m) B(0) eddy current was produced by the y-axis, suggesting potential limitations of single-sided gradient coils. PMID:20023323

  4. A cradle-shaped gradient coil to expand the clear-bore width of an animal MRI scanner

    NASA Astrophysics Data System (ADS)

    Gilbert, K. M.; Gati, J. S.; Klassen, L. M.; Menon, R. S.

    2010-01-01

    The never ending quest for higher magnetic field strengths in MRI and MRS has led to small and medium bore scanners at 9.4 T and above for both human and animal use; however, these bore diameters restrict the size of object that can be accommodated when using a conventional gradient coil. By replacing a cylindrical gradient-coil insert with a single-sided gradient coil, the scanner's functionality can be extended to include localized imaging of wider samples. As a prototype, a three-axis, cradle-shaped gradient coil was designed, fabricated and implemented in a 9.4 T animal MRI scanner. Since gradient fields are required only to be monotonic over the desired field of view, the cradle gradient coil was designed to produce high gradient efficiencies (up to 2.25 mT m-1 A-1 over a 5 cm imaging region) at the expense of gradient linearity. A dedicated three-dimensional algorithm was developed to correct the resultant image distortion. Preliminary images of a grid phantom and a mouse demonstrated the fidelity of the algorithm in correcting image distortion of greater than 200%. Eddy currents were measured along each gradient axis. A large 65.2 (Hz mT-1 m) B0 eddy current was produced by the y-axis, suggesting potential limitations of single-sided gradient coils.

  5. Off-resonance and detuned surface coils for B? inhomogeneity in 7-Tesla MRI

    E-print Network

    Zakszewski, Elizabeth K

    2006-01-01

    A problem with high-field MRI is the lack of B1 homogeneity, particularly signal cancellation in the outer parts of the head. Here we attempt to correct this by adding surface coils. To adjust the mutual coupling, we vary ...

  6. BOLD MRI of the human cervical spinal cord at 3 tesla

    Microsoft Academic Search

    P. W. Stroman; P. W. Nance; L. N. Ryner

    1999-01-01

    The feasibility of functional MRI of the spinal cord was investi- gated by carrying out blood oxygen-level dependent (BOLD) imaging of the human cervical spinal cord at a field of 3 T. BOLD imaging of the cervical spinal cord showed an average intensity increase of 7.0% during repeated exercise with the dominant hand with a return to baseline during rest

  7. A high-resolution 7-Tesla fMRI dataset from complex natural stimulation with an audio movie

    PubMed Central

    Hanke, Michael; Baumgartner, Florian J.; Ibe, Pierre; Kaule, Falko R.; Pollmann, Stefan; Speck, Oliver; Zinke, Wolf; Stadler, Jörg

    2014-01-01

    Here we present a high-resolution functional magnetic resonance (fMRI) dataset – 20 participants recorded at high field strength (7 Tesla) during prolonged stimulation with an auditory feature film (“Forrest Gump”). In addition, a comprehensive set of auxiliary data (T1w, T2w, DTI, susceptibility-weighted image, angiography) as well as measurements to assess technical and physiological noise components have been acquired. An initial analysis confirms that these data can be used to study common and idiosyncratic brain response patterns to complex auditory stimulation. Among the potential uses of this dataset are the study of auditory attention and cognition, language and music perception, and social perception. The auxiliary measurements enable a large variety of additional analysis strategies that relate functional response patterns to structural properties of the brain. Alongside the acquired data, we provide source code and detailed information on all employed procedures – from stimulus creation to data analysis. In order to facilitate replicative and derived works, only free and open-source software was utilized. PMID:25977761

  8. Scanning fast and slow: current limitations of 3 Tesla functional MRI and future potential

    NASA Astrophysics Data System (ADS)

    Boubela, Roland N.; Kalcher, Klaudius; Nasel, Christian; Moser, Ewald

    2014-02-01

    Functional MRI at 3T has become a workhorse for the neurosciences, e.g., neurology, psychology, and psychiatry, enabling non-invasive investigation of brain function and connectivity. However, BOLD-based fMRI is a rather indirect measure of brain function, confounded by fluctuation related signals, e.g. head or brain motion, brain pulsation, blood flow, intermixed with susceptibility differences close or distant to the region of neuronal activity. Even though a plethora of preprocessing strategies have been published to address these confounds, their efficiency is still under discussion. In particular, physiological signal fluctuations closely related to brain supply may mask BOLD signal changes related to "true" neuronal activation. Here we explore recent technical and methodological advancements aimed at disentangling the various components, employing fast multiband vs. standard EPI, in combination with fast temporal ICA.Our preliminary results indicate that fast (TR< 0.5s) scanning may help to identify and eliminate physiologic components, increasing tSNR and functional contrast. In addition, biological variability can be studied and task performance better correlated to other measures. This should increase specificity and reliability in fMRI studies. Furthermore, physiological signal changes during scanning may then be recognized as a source of information rather than a nuisance. As we are currently still undersampling the complexity of the brain, even at a rather coarse macroscopic level, we should be very cautious in the interpretation of neuroscientific findings, in particular when comparing different groups (e.g., age, sex, medication, pathology, etc.). From a technical point of view our goal should be to sample brain activity at layer specific resolution with low TR, covering as much of the brain as possible without violating SAR limits. We hope to stimulate discussion towards a better understanding and a more quantitative use of fMRI.

  9. A 32-Channel Lattice Transmission Line Array for Parallel Transmit and Receive MRI at 7 Tesla

    PubMed Central

    Adriany, Gregor; Auerbach, Edward J.; Snyder, Carl J.; Gözübüyük, Ark; Moeller, Steen; Ritter, Johannes; van de Moortele, Pierre-Francois; Vaughan, Tommy; U?urbil, Kamil

    2010-01-01

    Transmit and receive RF coil arrays have proven to be particularly beneficial for ultra-high-field MR. Transmit coil arrays enable such techniques as B1+ shimming to substantially improve transmit B1 homogeneity compared to conventional volume coil designs, and receive coil arrays offer enhanced parallel imaging performance and SNR. Concentric coil arrangements hold promise for developing transceiver arrays incorporating large numbers of coil elements. At magnetic field strengths of 7 tesla and higher where the Larmor frequencies of interest can exceed 300 MHz, the coil array design must also overcome the problem of the coil conductor length approaching the RF wavelength. In this study, a novel concentric arrangement of resonance elements built from capacitively-shortened half-wavelength transmission lines is presented. This approach was utilized to construct an array with whole-brain coverage using 16 transceiver elements and 16 receive-only elements, resulting in a coil with a total of 16 transmit and 32 receive channels. PMID:20512850

  10. Correction of inter-scanner and within-subject variance in structural MRI based automated diagnosing.

    PubMed

    Kostro, Daniel; Abdulkadir, Ahmed; Durr, Alexandra; Roos, Raymund; Leavitt, Blair R; Johnson, Hans; Cash, David; Tabrizi, Sarah J; Scahill, Rachael I; Ronneberger, Olaf; Klöppel, Stefan

    2014-09-01

    Automated analysis of structural magnetic resonance images is a promising way to improve early detection of neurodegenerative brain diseases. Clinical applications of such methods involve multiple scanners with potentially different hardware and/or acquisition sequences and demographically heterogeneous groups. To improve classification performance, we propose to correct effects of subject-specific covariates (such as age, total intracranial volume, and sex) as well as effects of scanner by using a non-linear Gaussian process model. To test the efficacy of the correction, we performed classification of carriers of the genetic mutation leading to Huntington's disease (HD) versus healthy controls. Half of the HD carriers were free of typical HD symptoms and had an estimated 5 to 20years before onset of clinical symptoms, thus providing a model for preclinical diagnosis of a neurodegenerative disease. Structural magnetic resonance brain images were acquired at four sites with pairs of sites which had the identical scanner type, equipment, and acquisition parameters. For automatic classification, we used spatially normalized probabilistic maps of gray matter, then removed confounding effects by Gaussian process regression, and then performed classification with a support vector machine. Voxel-based morphometry of gray matter maps showed disease effects that were spatially wider spread than effects of scanner, but no significant interactions between scanner and disease were found. A model trained with data from a single scanner generalized well to data from a different scanner. When confounding diagnostics groups and scanner during training, e.g. by using controls from one scanner and gene carriers from another, classification accuracy dropped significantly in many cases. By regressing out confounds with Gaussian process regression, the performance levels were comparable to those obtained in scenarios without confound. We conclude that models trained on data acquired with a single scanner generalized well to data acquired with a different same-generation scanner even when the vendor differed. When confounding grouping and scanner during training is unavoidable to gather training data, regressing out inter-scanner and between-subject variability can reduce the loss in accuracy due to the confound. PMID:24791746

  11. The Virtual Patient Simulator of Deep Brain Stimulation in the Obsessive Compulsive Disorder Based on Connectome and 7 Tesla MRI Data

    PubMed Central

    Bonmassar, Giorgio; Makris, Nikos

    2014-01-01

    We present work in progress on the virtual patient model for patients with Deep Brain Stimulation (DBS) implants based on Connectome and 7 Tesla Magnetic Resonance Imaging (MRI) data. Virtual patients are realistic computerized models of patients that allow medical-device companies to test new products earlier, helping the devices get to market more quickly and cheaply according to the Food and Drug Administration. We envision that the proposed new virtual patient simulator will enable radio frequency power dosimetry on patients with the DBS implant undergoing MRI. Future patients with DBS implants may profit from the proposed virtual patient by allowing for a MRI investigation instead of more invasive Computed Tomography (CT) scans. The virtual patient will be flexible and morphable to relate to neurological and psychiatric conditions such as Obsessive Compulsive Disorder (OCD), which benefit from DBS. PMID:25506052

  12. Functional subdivision of the human periaqueductal grey in respiratory control using 7 tesla fMRI

    PubMed Central

    Faull, Olivia K.; Jenkinson, Mark; Clare, Stuart; Pattinson, Kyle T.S.

    2015-01-01

    The periaqueductal grey (PAG) is a nucleus within the midbrain, and evidence from animal models has identified its role in many homeostatic systems including respiration. Animal models have also demonstrated a columnar structure that subdivides the PAG into four columns on each side, and these subdivisions have different functions with regard to respiration. In this study we used ultra-high field functional MRI (7 T) to image the brainstem and superior cortical areas at high resolution (1 mm3 voxels), aiming to identify activation within the columns of the PAG associated with respiratory control. Our results showed deactivation in the lateral and dorsomedial columns of the PAG corresponding with short (~ 10 s) breath holds, along with cortical activations consistent with previous respiratory imaging studies. These results demonstrate the involvement of the lateral and dorsomedial PAG in the network of conscious respiratory control for the first time in humans. This study also reveals the opportunities of 7 T functional MRI for non-invasively investigating human brainstem nuclei at high-resolutions. PMID:25703831

  13. Improved assessment of cartilage repair tissue using fluid-suppressed 23Na inversion recovery MRI at 7 Tesla: preliminary results

    PubMed Central

    Madelin, Guillaume; Sherman, Orrin H.; Strauss, Eric J.; Xia, Ding; Recht, Michael P.; Jerschow, Alexej; Regatte, Ravinder R.

    2013-01-01

    Objectives To evaluate cartilage repair and native tissue using a three-dimensional (3D), radial, ultra-short echo time (UTE) 23Na MR sequence without and with an inversion recovery (IR) preparation pulse for fluid suppression at 7 Tesla (T). Methods This study had institutional review board approval. We recruited 11 consecutive patients (41.5±11.8 years) from an orthopaedic surgery practice who had undergone a knee cartilage restoration procedure. The subjects were examined postoperatively (median=26 weeks) with 7-T MRI using: proton-T2 (TR/TE=3,000 ms/60 ms); sodium UTE (TR/TE=100 ms/0.4 ms); fluid-suppressed, sodium UTE adiabatic IR. Cartilage sodium concentrations in repair tissue ([Na+]R), adjacent native cartilage ([Na+]N), and native cartilage within the opposite, non-surgical compartment ([Na+]N2) were calculated using external NaCl phantoms. Results For conventional sodium imaging, mean [Na+]R, [Na+]N, [Na+]N2 were 177.8±54.1 mM, 170.1±40.7 mM, 172.2±30 mM respectively. Differences in [Na+]R versus [Na+]N (P=0.59) and [Na+]N versus [Na+]N2 (P=0.89) were not significant. For sodium IR imaging, mean [Na+]R, [Na+]N, [Na+]N2 were 108.9±29.8 mM, 204.6±34.7 mM, 249.9± 44.6 mM respectively. Decreases in [Na+]R versus [Na+]N (P=0.0.0000035) and [Na+]N versus [Na+]N2 (P=0.015) were significant. Conclusions Sodium IR imaging at 7 T can suppress the signal from free sodium within synovial fluid. This may allow improved assessment of [Na+] within cartilage repair and native tissue. PMID:22350437

  14. A fast multiparameter MRI approach for acute stroke assessment on a 3T clinical scanner: preliminary results in a non-human primate model with transient ischemic occlusion

    PubMed Central

    Tong, Frank; Li, Chun-Xia; Yan, Yumei; Nair, Govind; Nagaoka, Tsukasa; Tanaka, Yoji; Zola, Stuart; Howell, Leonard

    2014-01-01

    Many MRI parameters have been explored and demonstrated the capability or potential to evaluate acute stroke injury, providing anatomical, microstructural, functional, or neurochemical information for diagnostic purposes and therapeutic development. However, the application of multiparameter MRI approach is hindered in clinic due to the very limited time window after stroke insult. Parallel imaging technique can accelerate MRI data acquisition dramatically and has been incorporated in modern clinical scanners and increasingly applied for various diagnostic purposes. In the present study, a fast multiparameter MRI approach including structural T1-weighted imaging (T1W), T2-weighted imaging (T2W), diffusion tensor imaging (DTI), T2-mapping, proton magnetic resonance spectroscopy, cerebral blood flow (CBF), and magnetization transfer (MT) imaging, was implemented and optimized for assessing acute stroke injury on a 3T clinical scanner. A macaque model of transient ischemic stroke induced by a minimal interventional approach was utilized for evaluating the multiparameter MRI approach. The preliminary results indicate the surgical procedure successfully induced ischemic occlusion in the cortex and/or subcortex in adult macaque monkeys (n=4). Application of parallel imaging technique substantially reduced the scanning duration of most MRI data acquisitions, allowing for fast and repeated evaluation of acute stroke injury. Hence, the use of the multiparameter MRI approach with up to five quantitative measures can provide significant advantages in preclinical or clinical studies of stroke disease. PMID:24834423

  15. Performance Test of an LSO-APD Detector in a 7-T MRI Scanner for Simultaneous PET\\/MRI

    Microsoft Academic Search

    Bernd J. Pichler; Martin S. Judenhofer; Ciprian Catana; Jeffrey H. Walton; Manfred Kneilling; Robert E. Nutt; Stefan B. Siegel; Claus D. Claussen; Simon R. Cherry

    PETcombined withCThasproventobe avaluablemultimodality imaging device revealing both functional and anatomic informa- tion. Although PET\\/CT has become completely integrated into routine clinical application and also has been used insmall-animal imaging, CT provides only limited soft-tissue contrast and, in preclinical studies, exposes the animal to a relatively high radia- tion dose. Unlike CT, MRI provides good soft-tissue contrast even without application of

  16. Initial experience with MR-imaging of intracranial midline-lesions and lesions of the cervical spine at half tesla

    Microsoft Academic Search

    Rainer Guido Bluemm; Danièle Balériaux; Gerhard Lausberg; Jacques Brotchi

    1984-01-01

    Summary Fifty-two patients were examined both with computed tomography using a different third generation scanner and by magnetic resonance imaging (MRI) at half Tesla field strength (Philips Gyroscan 5 S). Excellent contrast and spatial resolution as well as initial comparative results of normal anatomy and also selected clinical cases were demonstrated with the spin-echo (SE) and\\/or inversion recovery (IR) technique.

  17. New shielding configurations for a simultaneous PET/MRI scanner at 7T

    NASA Astrophysics Data System (ADS)

    Peng, Bo J.; Wu, Yibao; Cherry, Simon R.; Walton, Jeffrey H.

    2014-02-01

    Understanding sources of electromagnetic interference are important in designing any electronic system. This is especially true when combining positron emission tomography (PET) and magnetic resonance imaging (MRI) in a multimodality system as coupling between the subsystems can degrade the performance of either modality. For this reason, eliminating radio frequency (RF) interference and gradient-induced eddy currents have been major challenges in building simultaneous hybrid PET/MRI systems. MRI requires negligible RF interference at the Larmor resonance frequency, while RF interference at almost any frequency may corrupt PET data. Moreover, any scheme that minimizes these interactions would, ideally, not compromise the performance of either subsystem. This paper lays out a plan to resolve these problems. A carbon fiber composite material is found to be a good RF shield at the Larmor frequency (300 MHz in this work) while introducing negligible gradient eddy currents. This carbon fiber composite also provides excellent structural support for the PET detector components. Low frequency electromagnetic radiation (81 kHz here) from the switching power supplies of the gradient amplifiers was also found to interfere with the PET detector. Placing the PET detector module between two carbon fiber tubes and grounding the inner carbon fiber tube to the PET detector module ground reduced this interference. Further reductions were achieved by adding thin copper (Cu) foil on the outer carbon fiber case and electrically grounding the PET detector module so that all 3 components had a common ground, i.e. with the PET detector in an electrostatic cage. Finally, gradient switching typical in MRI sequences can result in count losses in the particular PET detector design studied. Moreover, the magnitude of this effect depends on the location of the detector within the magnet bore and which MRI gradient is being switched. These findings have a bearing on future designs of PET/MRI systems.

  18. New shielding configurations for a simultaneous PET/MRI scanner at 7T

    PubMed Central

    Peng, Bo J.; Wu, Yibao; Cherry, Simon R.; Walton, Jeffrey H.

    2014-01-01

    Understanding sources of electromagnetic interference are important in designing any electronic system. This is especially true when combining positron emission tomography (PET) and magnetic resonance imaging (MRI) in a multimodality system as coupling between the subsystems can degrade the performance of either modality. For this reason, eliminating radio frequency (RF) interference and gradient-induced eddy currents have been major challenges in building simultaneous hybrid PET/MRI systems. MRI requires negligible RF interference at the Larmor resonance frequency, while RF interference at almost any frequency may corrupt PET data. Moreover, any scheme that minimizes these interactions would, ideally, not compromise the performance of either subsystem. This paper lays out a plan to resolve these problems. A carbon fiber composite material is found to be a good RF shield at the Larmor frequency (300 MHz in this work) while introducing negligible gradient eddy currents. This carbon fiber composite also provides excellent structural support for the PET detector components. Low frequency electromagnetic radiation (81 kHz here) from the switching power supplies of the gradient amplifiers was also found to interfere with the PET detector. Placing the PET detector module between two carbon fiber tubes and grounding the inner carbon fiber tube to the PET detector module ground reduced this interference. Further reductions were achieved by adding thin copper (Cu) foil on the outer carbon fiber case and electrically grounding the PET detector module so that all 3 components had a common ground, i.e. with the PET detector in an electrostatic cage. Finally, gradient switching typical in MRI sequences can result in count losses in the particular PET detector design studied. Moreover, the magnitude of this effect depends on the location of the detector within the magnet bore and which MRI gradient is being switched. These findings have a bearing on future designs of PET/MRI systems. PMID:24380812

  19. New shielding configurations for a simultaneous PET/MRI scanner at 7T.

    PubMed

    Peng, Bo J; Wu, Yibao; Cherry, Simon R; Walton, Jeffrey H

    2014-02-01

    Understanding sources of electromagnetic interference are important in designing any electronic system. This is especially true when combining positron emission tomography (PET) and magnetic resonance imaging (MRI) in a multimodality system as coupling between the subsystems can degrade the performance of either modality. For this reason, eliminating radio frequency (RF) interference and gradient-induced eddy currents have been major challenges in building simultaneous hybrid PET/MRI systems. MRI requires negligible RF interference at the Larmor resonance frequency, while RF interference at almost any frequency may corrupt PET data. Moreover, any scheme that minimizes these interactions would, ideally, not compromise the performance of either subsystem. This paper lays out a plan to resolve these problems. A carbon fiber composite material is found to be a good RF shield at the Larmor frequency (300MHz in this work) while introducing negligible gradient eddy currents. This carbon fiber composite also provides excellent structural support for the PET detector components. Low frequency electromagnetic radiation (81kHz here) from the switching power supplies of the gradient amplifiers was also found to interfere with the PET detector. Placing the PET detector module between two carbon fiber tubes and grounding the inner carbon fiber tube to the PET detector module ground reduced this interference. Further reductions were achieved by adding thin copper (Cu) foil on the outer carbon fiber case and electrically grounding the PET detector module so that all 3 components had a common ground, i.e. with the PET detector in an electrostatic cage. Finally, gradient switching typical in MRI sequences can result in count losses in the particular PET detector design studied. Moreover, the magnitude of this effect depends on the location of the detector within the magnet bore and which MRI gradient is being switched. These findings have a bearing on future designs of PET/MRI systems. PMID:24380812

  20. Evaluation of preoperative high magnetic field motor functional MRI (3 Tesla) in glioma patients by navigated electrocortical stimulation and postoperative outcome

    PubMed Central

    Roessler, K; Donat, M; Lanzenberger, R; Novak, K; Geissler, A; Gartus, A; Tahamtan, A; Milakara, D; Czech, T; Barth, M; Knosp, E; Beisteiner, R

    2005-01-01

    Objectives: The validity of 3 Tesla motor functional magnetic resonance imaging (fMRI) in patients with gliomas involving the primary motor cortex was investigated by intraoperative navigated motor cortex stimulation (MCS). Methods: Twenty two patients (10 males, 12 females, mean age 39 years, range 10–65 years) underwent preoperative fMRI studies, performing motor tasks including hand, foot, and mouth movements. A recently developed high field clinical fMRI technique was used to generate pre-surgical maps of functional high risk areas defining a motor focus. Motor foci were tested for validity by intraoperative motor cortex stimulation (MCS) employing image fusion and neuronavigation. Clinical outcome was assessed using the Modified Rankin Scale. Results: FMRI motor foci were successfully detected in all patients preoperatively. In 17 of 22 patients (77.3%), a successful stimulation of the primary motor cortex was possible. All 17 correlated patients showed 100% agreement on MCS and fMRI motor focus within 10 mm. Technical problems during stimulation occurred in three patients (13.6%), no motor response was elicited in two (9.1%), and MCS induced seizures occurred in three (13.6%). Combined fMRI and MCS mapping results allowed large resections in 20 patients (91%) (gross total in nine (41%), subtotal in 11 (50%)) and biopsy in two patients (9%). Pathology revealed seven low grade and 15 high grade gliomas. Mild to moderate transient neurological deterioration occurred in six patients, and a severe hemiparesis in one. All patients recovered within 3 months (31.8% transient, 0% permanent morbidity). Conclusions: The validation of clinically optimised high magnetic field motor fMRI confirms high reliability as a preoperative and intraoperative adjunct in glioma patients selected for surgery within or adjacent to the motor cortex. PMID:16024896

  1. Safety Implications of High-Field MRI: Actuation of Endogenous Magnetic Iron Oxides in the Human Body

    Microsoft Academic Search

    Jon Dobson; Richard Bowtell; Ana Garcia-Prieto; Quentin Pankhurst; Igor Sokolov

    2009-01-01

    BackgroundMagnetic Resonance Imaging scanners have become ubiquitous in hospitals and high-field systems (greater than 3 Tesla) are becoming increasingly common. In light of recent European Union moves to limit high-field exposure for those working with MRI scanners, we have evaluated the potential for detrimental cellular effects via nanomagnetic actuation of endogenous iron oxides in the body.MethodologyTheoretical models and experimental data

  2. Characterization of Nyquist ghost in EPI-fMRI acquisition sequences implemented on two clinical 1.5 T MR scanner systems: effect of readout bandwidth and echo spacing.

    PubMed

    Giannelli, Marco; Diciotti, Stefano; Tessa, Carlo; Mascalchi, Mario

    2010-01-01

    In EPI-fMRI acquisitions, various readout bandwidth (BW) values are used as a function of gradients' characteristics of the MR scanner system. Echo spacing (ES) is another fundamental parameter of EPI-fMRI sequences, but the employed ES value is not usually reported in fMRI studies. Nyquist ghost is a typical EPI artifact that can degrade the overall quality of fMRI time series. In this work, the authors assessed the basic effect of BW and ES for two clinical 1.5 T MR scanner systems (scanner-A, scanner-B) on Nyquist ghost of gradient-echo EPI-fMRI sequences. BW range was: scanner-A, 1953-3906 Hz/pixel; scanner-B, 1220-2894 Hz/pixel. ES range was: scanner-A, scanner-B: 0.75-1.33 ms. The ghost-to-signal ratio of time series acquisition (GSRts) and drift of ghost-to-signal ratio (DRGSR) were measured in a water phantom. For both scanner-A (93% of variation) and scanner-B (102% of variation) the mean GSRts significantly increased with increasing BW. GSRts values of scanner-A did not significantly depended on ES. On the other hand, GSRts values of scanner-B significantly varied with ES, showing a downward trend (81% of variation) with increasing ES. In addition, a GSRts spike point at ES = 1.05 ms indicating a potential resonant effect was revealed. For both scanners, no significant effect of ES on DRGSR was revealed. DRGSR values of scanner-B did not significantly vary with BW, whereas DRGSR values of scanner-A significantly depended on BW showing an upward trend from negative to positive values with increasing BW. GSRts and DRGSR can significantly vary with BW and ES, and the specific pattern of variation may depend on gradients performances, EPI sequence calibrations and functional design of radiofrequency coil. Thus, each MR scanner system should be separately characterized. In general, the employment of low BW values seems to reduce the intensity and temporal variation of Nyquist ghost in EPI-fMRI time series. On the other hand, the use of minimum ES value might not be entirely advantageous when the MR scanner is characterized by gradients with low performances and suboptimal EPI sequence calibration. PMID:21081879

  3. Development of a MPPC-based prototype gantry for future MRI-PET scanners

    NASA Astrophysics Data System (ADS)

    Kurei, Y.; Kataoka, J.; Kato, T.; Fujita, T.; Ohshima, T.; Taya, T.; Yamamoto, S.

    2014-12-01

    We have developed a high spatial resolution, compact Positron Emission Tomography (PET) module designed for small animals and intended for use in magnetic resonance imaging (MRI) systems. This module consists of large-area, 4 × 4 ch MPPC arrays (S11830-3344MF; Hamamatsu Photonics K.K.) optically coupled with Ce-doped (Lu,Y)2(SiO4)O (Ce:LYSO) scintillators fabricated into 16 × 16 matrices of 0.5 × 0.5 mm2 pixels. We set the temperature sensor (LM73CIMK-0; National Semiconductor Corp.) at the rear of the MPPC acceptance surface, and apply optimum voltage to maintain the gain. The eight MPPC-based PET modules and coincidence circuits were assembled into a gantry arranged in a ring 90 mm in diameter to form the MPPC-based PET system. We have developed two types PET gantry: one made of non-magnetic metal and the other made of acrylonitrile butadiene styrene (ABS) resins. The PET gantry was positioned around the RF coil of the 4.7 T MRI system. We took an image of a point }22Na source under fast spin echo (FSE) and gradient echo (GE), in order to measure the interference between the MPPC-based PET and MRI. The spatial resolution of PET imaging in a transaxial plane of about 1 mm (FWHM) was achieved in all cases. Operating with PET made of ABS has no effect on MR images, while operating with PET made of non-magnetic metal has a significant detrimental effect on MR images. This paper describes our quantitative evaluations of PET images and MR images, and presents a more advanced version of the gantry for future MRI/DOI-PET systems.

  4. In vivo imaging of pancreatic tumours and liver metastases using 7 Tesla MRI in a murine orthotopic pancreatic cancer model and a liver metastases model

    PubMed Central

    2011-01-01

    Background Pancreatic cancer is the fourth leading cause of tumour death in the western world. However, appropriate tumour models are scarce. Here we present a syngeneic murine pancreatic cancer model using 7 Tesla MRI and evaluate its clinical relevance and applicability. Methods 6606PDA murine pancreatic cancer cells were orthotopically injected into the pancreatic head. Liver metastases were induced through splenic injection. Animals were analyzed by MRI three and five weeks following injection. Tumours were detected using T2-weighted high resolution sequences. Tumour volumes were determined by callipers and MRI. Liver metastases were analyzed using gadolinium-EOB-DTPA and T1-weighted 3D-Flash sequences. Tumour blood flow was measured using low molecular gadobutrol and high molecular gadolinium-DTPA. Results MRI handling and applicability was similar to human systems, resolution as low as 0.1 mm. After 5 weeks tumour volumes differed significantly (p < 0.01) when comparing calliper measurments (n = 5, mean 1065 mm3+/-243 mm3) with MRI (mean 918 mm3+/-193 mm3) with MRI being more precise. Histology (n = 5) confirmed MRI tumour measurements (mean size MRI 38.5 mm2+/-22.8 mm2 versus 32.6 mm2+/-22.6 mm2 (histology), p < 0,0004) with differences due to fixation and processing of specimens. After splenic injection all mice developed liver metastases with a mean of 8 metastases and a mean volume of 173.8 mm3+/-56.7 mm3 after 5 weeks. Lymphnodes were also easily identified. Tumour accumulation of gadobutrol was significantly (p < 0.05) higher than gadolinium-DTPA. All imaging experiments could be done repeatedly to comply with the 3R-principle thus reducing the number of experimental animals. Conclusions This model permits monitoring of tumour growth and metastasis formation in longitudinal non-invasive high-resolution MR studies including using contrast agents comparable to human pancreatic cancer. This multidisciplinary environment enables radiologists, surgeons and physicians to further improve translational research and therapies of pancreatic cancer. PMID:21276229

  5. Magnetosomes, biogenic magnetic nanomaterials for brain molecular imaging with 17.2 T MRI scanner.

    PubMed

    Mériaux, Sébastien; Boucher, Marianne; Marty, Benjamin; Lalatonne, Yoann; Prévéral, Sandra; Motte, Laurence; Lefèvre, Christopher T; Geffroy, Françoise; Lethimonnier, Franck; Péan, Michel; Garcia, Daniel; Adryanczyk-Perrier, Géraldine; Pignol, David; Ginet, Nicolas

    2015-05-01

    The fast development of sensitive molecular diagnostic tools is currently paving the way for a personalized medicine. A new class of ultrasensitive magnetic resonance imaging (MRI) T2 -contrast agents based on magnetosomes, magnetite nanocrystals biomineralized by magnetotactic bacteria, is proposed here. The contrast agents can be injected into the blood circulation and detected in the picomolar range. Purified magnetosomes are water-dispersible and stable within physiological conditions and exhibit at 17.2 T a transverse relaxivity r2 four times higher than commercial ferumoxide. The subsequent gain in sensitivity by T2 (*) -weighted imaging at 17.2 T of the mouse brain vasculature is evidenced in vivo after tail vein injection of magnetosomes representing a low dose of iron (20 ?moliron kg(-1) ), whereas no such phenomenon with the same dose of ferumoxide is observed. Preclinical studies of human pathologies in animal models will benefit from the combination of high magnetic field MRI with sensitive, low dose, easy-to-produce biocompatible contrast agents derived from bacterial magnetosomes. PMID:25676134

  6. Exposure to static and time-varying magnetic fields from working in the static magnetic stray fields of MRI scanners: a comprehensive survey in the Netherlands.

    PubMed

    Schaap, Kristel; Christopher-De Vries, Yvette; Crozier, Stuart; De Vocht, Frank; Kromhout, Hans

    2014-11-01

    Clinical and research staff who work around magnetic resonance imaging (MRI) scanners are exposed to the static magnetic stray fields of these scanners. Although the past decade has seen strong developments in the assessment of occupational exposure to electromagnetic fields from MRI scanners, there is insufficient insight into the exposure variability that characterizes routine MRI work practice. However, this is an essential component of risk assessment and epidemiological studies. This paper describes the results of a measurement survey of shift-based personal exposure to static magnetic fields (SMF) (B) and motion-induced time-varying magnetic fields (dB/dt) among workers at 15 MRI facilities in the Netherlands. With the use of portable magnetic field dosimeters, >400 full-shift and partial shift exposure measurements were collected among various jobs involved in clinical and research MRI. Various full-shift exposure metrics for B and motion-induced dB/dt exposure were calculated from the measurements, including instantaneous peak exposure and time-weighted average (TWA) exposures. We found strong correlations between levels of static (B) and time-varying (dB/dt) exposure (r = 0.88-0.92) and between different metrics (i.e. peak exposure, TWA exposure) to express full-shift exposure (r = 0.69-0.78). On average, participants were exposed to MRI-related SMFs during only 3.7% of their work shift. Average and peak B and dB/dt exposure levels during the work inside the MRI scanner room were highest among technical staff, research staff, and radiographers. Average and peak B exposure levels were lowest among cleaners, while dB/dt levels were lowest among anaesthesiology staff. Although modest exposure variability between workplaces and occupations was observed, variation between individuals of the same occupation was substantial, especially among research staff. This relatively large variability between workers with the same job suggests that exposure classification based solely on job title may not be an optimal grouping strategy for epidemiological purposes. PMID:25139484

  7. Functional MRI at 1.5 tesla: A comparison of the blood oxygenation level-dependent signal and electrophysiology

    Microsoft Academic Search

    Elizabeth A. Disbrow; Daniel A. Slutsky; Timothy P. L. Roberts; Leah A. Krubitzer

    2000-01-01

    ntil recently, noninvasive techniques used to image the human brain and its activity were not widely accessible. However, in the past few years, procedures such as functional MRI (fMRI) have become readily available and are used in a wide range of disciplines including Radiology, Psychology, Psy- chiatry, Neurology, Neurosurgery, and Neuroscience. The in- vestigations undertaken by different groups are diverse

  8. Recording of the event-related potentials during functional MRI at 3.0 Tesla field strength

    Microsoft Academic Search

    F. Kruggel; C. J. Wiggins; C. S. Herrmann; D. Y. von Cramon

    2000-01-01

    The feasibility of recording event-related potentials (ERP) dur- ing functional MRI (fMRI) scanning was studied. Using an alter- nating checkerboard stimulus in a blocked presentation, visu- ally evoked potentials were obtained with their expected con- figuration and latencies. A clustered echoplanar imaging protocol was applied to observe the hemodynamic response due to the visual stimulus interleaved with measuring ERPs. Influences

  9. Detection power, temporal response, and spatial resolution of IRON fMRI in awake, behaving monkeys at 3 Tesla

    E-print Network

    Leite, Francisca Maria Pais Horta

    2007-01-01

    The main goal of this thesis was to systematically characterize the detection sensitivity, temporal response, and spatial resolution of IRON contrast for fMRI within the awake, behaving monkey. Understanding these issues ...

  10. Ultrashort echo time MRI of pulmonary water content: assessment in a sponge phantom at 1.5 and 3.0 Tesla

    PubMed Central

    Molinari, Francesco; Madhuranthakam, Ananth J.; Lenkinski, Robert; Bankier, Alexander A.

    2014-01-01

    PURPOSE We aimed to develop a predictive model for lung water content using ultrashort echo time (UTE) magnetic resonance imaging (MRI) and a sponge phantom. MATERIALS AND METHODS Image quality was preliminarily optimized, and the signal-to-noise ratio (SNR) of UTE was compared with that obtained from a three-dimensional fast gradient echo (FGRE) sequence. Four predetermined volumes of water (3.5, 3.0, 2.5, and 2.0 mL) were soaked in cellulose foam sponges 1.8 cm3 in size and were imaged with UTE-MRI at 1.5 and 3.0 Tesla (T). A multiple echo time experiment (range, 0.1–9.6 ms) was conducted, and the T2 signal decay curve was determined at each volume of water. A three-parameter equation was fitted to the measured signal, allowing for the calculation of proton density and T2*. The calculation error of proton density was determined as a function of echo time. The constants that allowed for the determination of unknown volumes of water from the measured proton density were calculated using linear regression. RESULTS UTE-MRI provided excellent image quality for the four phantoms and showed a higher SNR, compared to that of FGRE. Proton density decreased proportionally with the decreases in both lung water and field strength (from 3.5 to 2.0 mL; proton density range at 1.5 T, 30.5–17.3; at 3.0 T, 84.2–41.5). Minimum echo time less than 0.6 ms at 1.5 T and 1 ms at 3.0 T maintained calculation errors for proton density within the range of 0%–10%. The slopes of the lines for determining the unknown volumes of water with UTE-MRI were 0.12±0.003 at 1.5 T and 0.05±0.002 at 3.0 T (P < 0.0001). CONCLUSION In a sponge phantom imaged at 1.5 and 3.0 T, unknown volumes of water can be predicted with high accuracy using UTE-MRI. PMID:24317335

  11. A six-channel pediatric coil array for detection of children spinal pathologies by MRI at 1.5 Tesla

    NASA Astrophysics Data System (ADS)

    López Terrones, Marcos Alonso; Solís-Nájera, Sergio Enrique

    2014-11-01

    Nowadays, magnetic resonance (MR) in Mexico has become a standard technique for clinical imaging. Although most of the times the MR systems contain only coils oriented for adults. Radiologists use these coils for children studies due to the non-availability of pediatric coils. Image quality is decreased due to the low signal to noise ratio delivered to the system. The development of RF coils is always focused towards increasing SNR and optimizing the RF penetration into the sample. Moreover, spinal pathologies in children, which are an important topic in pediatric care, cover congenital and neuromuscular disorders that occur in childhood. In this work, the design of a dedicated six-channel coil for detection of spinal pathologies at 1.5 Tesla is addressed. Numerical electromagnetic simulations were performed in order to evaluate their magnetic field performance at (63.6 MHz) 1.5 Tesla. The magnetic field uniformity as well as the RF penetration depth of the coil configurations was evaluated in order to find the best/optimized coil array configuration. The coil is comprised of three rows, one with 4 coil elements and two with only one coil element. Phantom and in vivo images were acquired with the six-channel pediatric coil array. The phantom images agree with the simulated data. In vivo images acquired with the 6-channel pediatric coil array have shown very good penetration depth and homogeneity, which allow better image quality throughout the whole FOV. In addition, the parallel imaging capabilities of the array allow the acceleration of the experiments avoiding possible motion artifacts.

  12. Prediction of Prostate Cancer Extracapsular Extension with High Spatial Resolution Dynamic Contrast-Enhanced 3 Tesla MRI

    PubMed Central

    Bloch, B. Nicolas; Genega, Elizabeth M.; Costa, Daniel N.; Pedrosa, Ivan; Smith, Martin P.; Kressel, Herbert Y.; Ngo, Long; Sanda, Martin G.; DeWolf, William C.; Rofsky, Neil M.

    2013-01-01

    Objectives To assess the value of dynamic contrast-enhanced (DCE) combined with T2-weighted (T2W) endorectal coil (ERC) magnetic resonance imaging (MRI) at 3 T (3T) for determining extracapsular extension (ECE) of prostate cancer. Methods In this IRB-approved study, ERC 3T MRI of the prostate was performed in 108 patients prior to radical prostatectomy. T2W fast spin-echo and DCE 3D gradient echo images were acquired. The interpretations of readers with varied experience were analyzed. MRI-based staging results were compared with radical prostatectomy histology. Descriptive statistics were generated for prediction of ECE and staging accuracies were determined by the area under the receiver-operating-characteristic curve. Results The overall sensitivity, specificity, positive predictive value, and negative predictive value for ECE were 75%, 92%, 79% and 91%, respectively. Diagnostic accuracy for staging was 86%, 80% and 91% for all readers, experienced and less experienced readers, respectively. Conclusions ERC 3T MRI of the prostate combining DCE and T2W imaging is an accurate pretheurapeutic staging tool for assessment of ECE in clinical practice across varying levels of reader experience. PMID:22661019

  13. Rat model of metastatic breast cancer monitored by MRI at 3 tesla and bioluminescence imaging with histological correlation

    PubMed Central

    Song, Ho-Taek; Jordan, Elaine K; Lewis, Bobbi K; Liu, Wei; Ganjei, Justin; Klaunberg, Brenda; Despres, Daryl; Palmieri, Diane; Frank, Joseph A

    2009-01-01

    Background Establishing a large rodent model of brain metastasis that can be monitored using clinically relevant magnetic resonance imaging (MRI) techniques is challenging. Non-invasive imaging of brain metastasis in mice usually requires high field strength MR units and long imaging acquisition times. Using the brain seeking MDA-MB-231BR transfected with luciferase gene, a metastatic breast cancer brain tumor model was investigated in the nude rat. Serial MRI and bioluminescence imaging (BLI) was performed and findings were correlated with histology. Results demonstrated the utility of multimodality imaging in identifying unexpected sights of metastasis and monitoring the progression of disease in the nude rat. Methods Brain seeking breast cancer cells MDA-MB-231BR transfected with firefly luciferase (231BRL) were labeled with ferumoxides-protamine sulfate (FEPro) and 1-3 × 106 cells were intracardiac (IC) injected. MRI and BLI were performed up to 4 weeks to monitor the early breast cancer cell infiltration into the brain and formation of metastases. Rats were euthanized at different time points and the imaging findings were correlated with histological analysis to validate the presence of metastases in tissues. Results Early metastasis of the FEPro labeled 231BRL were demonstrated onT2*-weighted MRI and BLI within 1 week post IC injection of cells. Micro-metastatic tumors were detected in the brain on T2-weighted MRI as early as 2 weeks post-injection in greater than 85% of rats. Unexpected skeletal metastases from the 231BRL cells were demonstrated and validated by multimodal imaging. Brain metastases were clearly visible on T2 weighted MRI by 3-4 weeks post infusion of 231BRL cells, however BLI did not demonstrate photon flux activity originating from the brain in all animals due to scattering of the photons from tumors. Conclusion A model of metastatic breast cancer in the nude rat was successfully developed and evaluated using multimodal imaging including MRI and BLI providing the ability to study the temporal and spatial distribution of metastases in the brain and skeleton. PMID:19840404

  14. A Prototype RF Dosimeter for Independent Measurement of the Average Specific Absorption Rate (SAR) During MRI

    PubMed Central

    Stralka, John P; Bottomley, Paul A

    2008-01-01

    Purpose To develop a scanner-independent dosimeter for measuring the average radio frequency (RF) power deposition and specific absorption rates (SAR) for human MRI exposure. Materials and Methods A prototype dosimeter has a transducer with orthogonal conducting loops surrounding a small signal-generating MRI sample. The loops contain resistors whose values are adjusted to load the scanner’s MRI coils equivalent to an average head or body during MRI. The scanner adjusts its power output to normal levels during setup, using the MRI sample. Following calibration, the total power and average SAR deposited in the transducer are measured from the root-mean-square (rms) power induced in the transducer during MRI. Results A 1.5 Tesla head transducer was adjusted to elicit the same load as the average of nine adult volunteers. Once adjusted, the transducer loads other head coils the same as the head does. The dosimeter is calibrated at up to 20 W total deposited power and 4.5 W/kg SAR in the average head, with about 5% accuracy. Conclusion This dosimeter provides a simple portable means of measuring the power deposited in a body-equivalent sample load, independent of the scanner. Further work will develop SAR dosimetry for the torso and for higher fields. PMID:17969145

  15. Signal abnormalities on 1.5 and 3 Tesla brain MRI in multiple sclerosis patients and healthy controls. A morphological and spatial quantitative comparison study.

    PubMed

    Di Perri, Carol; Dwyer, Michael G; Wack, David S; Cox, Jennifer L; Hashmi, Komal; Saluste, Erik; Hussein, Sara; Schirda, Claudiu; Stosic, Milena; Durfee, Jacqueline; Poloni, Guy U; Nayyar, Navdeep; Bergamaschi, Roberto; Zivadinov, Robert

    2009-10-01

    Previous studies in patients with multiple sclerosis (MS) revealed increased lesion count and volume on 3 T compared to 1.5 T. Morphological and spatial lesion characteristics between 1.5 T and 3 T have not been examined. The aim of this study was to investigate the effect of changing from a 1.5 T to a 3 T MRI scanner on the number, volume and spatial distribution of signal abnormalities (SA) on brain MRI in a sample of MS patients and normal controls (NC), using pair- and voxel-wise comparison procedures. Forty-one (41) MS patients (32 relapsing-remitting and 9 secondary-progressive) and 38 NC were examined on both 1.5 T and 3 T within one week in random order. T2-weighted hyperintensities (T2H) and T1-weighted hypointensities (T1H) were outlined semiautomatically by two operators in a blinded fashion on 1.5 T and 3 T images. Spatial lesion distribution was assessed using T2 and T1 voxel-wise SA probability maps (SAPM). Pair-wise analysis examined the proportion of SA not simultaneously outlined on 1.5 T and 3 T. A posteriori unblinded analysis was conducted to examine the non-overlapping identifications of SA between the 1.5 T and 3 T. For pair-wise T2- and T1-analyses, a higher number and individual volume of SA were detected on 3 T compared to 1.5 T (p<0.0001) in both MS and NC. Logistic regression analysis showed that the likelihood of missing SA on 1.5 T was significantly higher for smaller SA in both MS and NC groups. SA probability map (SAPM) analysis revealed significantly more regionally distinct spatial SA differences on 3 T compared to 1.5 T in both groups (p<0.05); these were most pronounced in the occipital, periventricular and cortical regions for T2H. This study provides important information regarding morphological and spatial differences between data acquired using 1.5 T and 3 T protocols at the two scanner field strengths. PMID:19371784

  16. TESLA Report 1998-28 TESLA Report 1998-28

    E-print Network

    TESLA Report 1998-28 #12;TESLA Report 1998-28 #12;TESLA Report 1998-28TESLA Report 1998-28TESLA Report 1998-28 Page 3 TESLA Report 1998-28 Page 1 #12;TESLA Report 1998-28TESLA Report 1998-28TESLA Report 1998-28 Page 4 TESLA Report 1998-28 Page 2 #12;TESLA Report 1998-28TESLA Report 1998-28TESLA

  17. A high resolution 7-Tesla resting-state fMRI test-retest dataset with cognitive and physiological measures.

    PubMed

    Gorgolewski, Krzysztof J; Mendes, Natacha; Wilfling, Domenica; Wladimirow, Elisabeth; Gauthier, Claudine J; Bonnen, Tyler; Ruby, Florence J M; Trampel, Robert; Bazin, Pierre-Louis; Cozatl, Roberto; Smallwood, Jonathan; Margulies, Daniel S

    2015-01-01

    Here we present a test-retest dataset of functional magnetic resonance imaging (fMRI) data acquired at rest. 22 participants were scanned during two sessions spaced one week apart. Each session includes two 1.5?mm isotropic whole-brain scans and one 0.75?mm isotropic scan of the prefrontal cortex, giving a total of six time-points. Additionally, the dataset includes measures of mood, sustained attention, blood pressure, respiration, pulse, and the content of self-generated thoughts (mind wandering). This data enables the investigation of sources of both intra- and inter-session variability not only limited to physiological changes, but also including alterations in cognitive and affective states, at high spatial resolution. The dataset is accompanied by a detailed experimental protocol and source code of all stimuli used. PMID:25977805

  18. In vivo detection of microscopic anisotropy using quadruple pulsed-field gradient (qPFG) diffusion MRI on a clinical scanner

    PubMed Central

    Avram, Alexandru V.; Özarslan, Evren; Sarlls, Joelle E.; Basser, Peter J.

    2012-01-01

    We report our design and implementation of a quadruple pulsed-field gradient (qPFG) diffusion MRI pulse sequence on a whole-body clinical scanner and demonstrate its ability to non-invasively detect restriction-induced microscopic anisotropy in human brain tissue. The microstructural information measured using qPFG diffusion MRI in white matter complements that provided by diffusion tensor imaging (DTI) and exclusively characterizes diffusion of water trapped in microscopic compartments with unique measures of average cell geometry. We describe the effect of white matter fiber orientation on the expected MR signal and highlight the importance of incorporating such information in the axon diameter measurement using a suitable mathematical framework. Integration of qPFG diffusion-weighted images (DWI) with fiber orientations measured using high-resolution DTI allows the estimation of average axon diameters in the corpus callosum of healthy human volunteers. Maps of inter-hemispheric average axon diameters reveal an anterior-posterior variation in good topographical agreement with anatomical measurements reported in previous post-mortem studies. With further technical refinements and additional clinical validation, qPFG diffusion MRI could provide a quantitative whole-brain histological assessment of white and gray matter, enabling a wide range of neuroimaging applications for improved diagnosis of neurodegenerative pathologies, monitoring neurodevelopmental processes, and mapping brain connectivity. PMID:22939872

  19. High-field 4.23 tesla magnetic resonance imaging: initial experience in turbo-inversion recovery imaging and fMRI physics

    Microsoft Academic Search

    Rakesh Sharma

    2004-01-01

    High-field magnetic resonance imaging (MRI) offers functional, biochemical and physiological information. High field is advantageous for both fMRI signal generated from deoxyhemoglobin and blood oxygen, and intracellular sodium by inversion recovery MRI imaging. High field MRI was used to image human and primates for sodium MRI imaging.

  20. 7 Tesla Magnetic Resonance Imaging to Detect Cortical Pathology in Multiple Sclerosis

    PubMed Central

    van Gelderen, Peter; Merkle, Hellmuth; Chen, Christina; Lassmann, Hans; Duyn, Jeff H.; Bagnato, Francesca

    2014-01-01

    Background Neocortical lesions (NLs) are an important pathological component of multiple sclerosis (MS), but their visualization by magnetic resonance imaging (MRI) remains challenging. Objectives We aimed at assessing the sensitivity of multi echo gradient echo (ME-GRE) T2*-weighted MRI at 7.0 Tesla in depicting NLs compared to myelin and iron staining. Methods Samples from two MS patients were imaged post mortem using a whole body 7T MRI scanner with a 24-channel receive-only array. Isotropic 200 micron resolution images with varying T2* weighting were reconstructed from the ME-GRE data and converted into R2* maps. Immunohistochemical staining for myelin (proteolipid protein, PLP) and diaminobenzidine-enhanced Turnbull blue staining for iron were performed. Results Prospective and retrospective sensitivities of MRI for the detection of NLs were 48% and 67% respectively. We observed MRI maps detecting only a small portion of 20 subpial NLs extending over large cortical areas on PLP stainings. No MRI signal changes suggestive of iron accumulation in NLs were observed. Conversely, R2* maps indicated iron loss in NLs, which was confirmed by histological quantification. Conclusions High-resolution post mortem imaging using R2* and magnitude maps permits detection of focal NLs. However, disclosing extensive subpial demyelination with MRI remains challenging. PMID:25303286

  1. TESLA Report 1997-22 TESLA Report 1997-22

    E-print Network

    TESLA Report 1997-22 #12;TESLA Report 1997-22 #12;TESLA Report 1997-22 #12;TESLA Report 1997-22 #12;TESLA Report 1997-22 #12;TESLA Report 1997-22 #12;TESLA Report 1997-22 #12;TESLA Report 1997-22 #12;TESLA Report 1997-22 #12;TESLA Report 1997-22 #12;TESLA Report 1997-22 #12;TESLA Report 1997-22 #12

  2. Patient-induced susceptibility effect on geometric distortion of clinical brain MRI for radiation treatment planning on a 3T scanner

    NASA Astrophysics Data System (ADS)

    Wang, H.; Balter, J.; Cao, Y.

    2013-02-01

    Concerns about the geometric accuracy of MRI in radiation therapy (RT) have been present since its invention. Although modern scanners typically have system levels of geometric accuracy that meet requirements of RT, subject-specific distortion is variable, and methods to in vivo assess and control patient-induced geometric distortion are not yet resolved. This study investigated the nature and magnitude of the subject-induced susceptibility effect on geometric distortions in clinical brain MRI, and tested the feasibility of in vivo quality control using field inhomogeneity mapping. For 19 consecutive patients scanned on a dedicated 3T MR scanner, B0 field inhomogeneity maps were acquired and analyzed to determine subject-induced distortions. For 3D T1 weighted images frequency-encoded with a bandwidth of 180 Hz/pixel, 86.9% of the estimated displacements were <0.5 mm, 97.4% <1 mm, and only 0.1% of displacements > 2 mm. The maximum displacement was <4 mm. The greatest distortions were observed at the interfaces with air at the sinuses. Displacements decayed to less than 1 mm over a distance of 8 mm. Metal surgical wires generated smaller distortions, with an averaged maximum displacement of 0.76 mm. Repeat acquisition of the field maps in 17 patients revealed a within-subject standard deviation of 0.25 ppm, equivalent to 0.22 mm displacement in the frequency-encoding direction in the 3D T1 weighted images. Susceptibility-induced voxel displacements in the brain are generally small, but should be monitored for precision RT. These effects are manageable at 3T and lower fields, and the methods applied can be used to monitor for potential local errors in individual patients, as well as to correct for local distortions as needed.

  3. Preliminary evaluation of a monolithic detector module for integrated PET/MRI scanner with high spatial resolution

    NASA Astrophysics Data System (ADS)

    Pani, R.; Gonzalez, A. J.; Bettiol, M.; Fabbri, A.; Cinti, M. N.; Preziosi, E.; Borrazzo, C.; Conde, P.; Pellegrini, R.; Di Castro, E.; Majewski, S.

    2015-06-01

    The proposal of Mindview European Project concerns with the development of a very high resolution and high efficiency brain dedicated PET scanner simultaneously working with a Magnetic Resonance scanner, that expects to visualize neurotransmitter pathways and their disruptions in the quest to better diagnose schizophrenia. On behalf of this project, we propose a low cost PET module for the first prototype, based on monolithic crystals, suitable to be integrated with a head Radio Frequency (RF) coil. The aim of the suggested module is to achieve high performances in terms of efficiency, planar spatial resolution (expected about 1 mm) and discrimination of gamma Depth Of Interaction (DOI) in order to reduce the parallax error. Our preliminary results are very promising: a DOI resolution of about 3 mm, a spatial resolution ranging from about 1 to 1.5 mm and a good position linearity.

  4. Haptic fMRI: combining functional neuroimaging with haptics for studying the brain's motor control representation.

    PubMed

    Menon, Samir; Brantner, Gerald; Aholt, Chris; Kay, Kendrick; Khatib, Oussama

    2013-01-01

    A challenging problem in motor control neuroimaging studies is the inability to perform complex human motor tasks given the Magnetic Resonance Imaging (MRI) scanner's disruptive magnetic fields and confined workspace. In this paper, we propose a novel experimental platform that combines Functional MRI (fMRI) neuroimaging, haptic virtual simulation environments, and an fMRI-compatible haptic device for real-time haptic interaction across the scanner workspace (above torso ? .65×.40×.20m(3)). We implement this Haptic fMRI platform with a novel haptic device, the Haptic fMRI Interface (HFI), and demonstrate its suitability for motor neuroimaging studies. HFI has three degrees-of-freedom (DOF), uses electromagnetic motors to enable high-fidelity haptic rendering (>350Hz), integrates radio frequency (RF) shields to prevent electromagnetic interference with fMRI (temporal SNR >100), and is kinematically designed to minimize currents induced by the MRI scanner's magnetic field during motor displacement (<2cm). HFI possesses uniform inertial and force transmission properties across the workspace, and has low friction (.05-.30N). HFI's RF noise levels, in addition, are within a 3 Tesla fMRI scanner's baseline noise variation (?.85±.1%). Finally, HFI is haptically transparent and does not interfere with human motor tasks (tested for .4m reaches). By allowing fMRI experiments involving complex three-dimensional manipulation with haptic interaction, Haptic fMRI enables-for the first time-non-invasive neuroscience experiments involving interactive motor tasks, object manipulation, tactile perception, and visuo-motor integration. PMID:24110643

  5. Towards undistorted and noise-free speech in an MRI scanner: correlation subtraction followed by spectral noise gating.

    PubMed

    Inouye, Joshua M; Blemker, Silvia S; Inouye, David I

    2014-03-01

    Noise cancellation in an MRI environment is difficult due to the high noise levels that are in the spectral range of human speech. This paper describes a two-step method to cancel MRI noise that combines operations in both the time domain (correlation subtraction) and the frequency domain (spectral noise gating). The resulting filtered recording has a noise power suppression of over 100?dB, a significant improvement over previously described techniques on MRI noise cancellation. The distortion is lower and the noise suppression higher than using spectral noise gating in isolation. Implementation of this method will aid in detailed studies of speech in relation to vocal tract and velopharyngeal function. PMID:24606243

  6. Slice profile distortions in single slice continuously moving table MRI

    NASA Astrophysics Data System (ADS)

    Sengupta, Saikat; Smith, David S.; Welch, E. B.

    2015-03-01

    Continuously Moving Table (CMT) MRI is a rapid imaging technique that allows scanning of extended fields of view (FOVs) such as the whole-body in a single continuous scan.1 A highly efficient approach to CMT MRI is single slice imaging, where data are continuously acquired from a single axial slice at isocenter with concurrent movement of the patient table.2 However, the continuous motion of the scanner table and supply of fresh magnetization into the excited slice can introduce deviations in the slice magnetization profile. The goal of this work is to investigate and quantify the distortion in the slice profile in CMT MRI. CMT MRI with a table speed of 20 mm/s was implemented on a 3 Tesla whole-body MRI scanner, with continuous radial data acquisition. Simulations were performed to characterize the transient and steady state slice profiles and magnetization effects. Simulated slice profiles were compared to actual slice profile measurements performed in the scanner. Both simulations and experiments revealed an asymmetric slice profile characterized by a skew towards the lagging edge of the moving table, in contrast to the nominal profiles associated with scanning a stationary object. The true excited slice width (FWHM) and pitch of the acquisition was observed to be dependent on table velocity, with larger table speeds resulting in larger slice profile deviations from the nominal shape.

  7. Functional diffusion tensor imaging at 3 Tesla

    PubMed Central

    Mandl, René C. W.; Schnack, Hugo G.; Zwiers, Marcel P.; Kahn, René S.; Hulshoff Pol, Hilleke E.

    2013-01-01

    In a previous study we reported on a non-invasive functional diffusion tensor imaging (fDTI) method to measure neuronal signals directly from subtle changes in fractional anisotropy along white matter tracts. We hypothesized that these fractional anisotropy changes relate to morphological changes of glial cells induced by axonal activity. In the present study we set out to replicate the results of the previous study with an improved fDTI scan acquisition scheme. A group of twelve healthy human participants were scanned on a 3 Tesla MRI scanner. Activation was revealed in the contralateral thalamo-cortical tract and optic radiations during tactile and visual stimulation, respectively. Mean percent signal change in FA was 3.47% for the tactile task and 3.79% for the visual task, while for the MD the mean percent signal change was only -0.10 and -0.09%. The results support the notion of different response functions for tactile and visual stimuli. With this study we successfully replicated our previous findings using the same types of stimuli but on a different group of healthy participants and at different field-strength. The successful replication of our first fDTI results suggests that the non-invasive fDTI method is robust enough to study the functional neural networks in the human brain within a practically feasible time period. PMID:24409133

  8. Probabilistic atlas-based segmentation of combined T1-weighted and DUTE MRI for calculation of head attenuation maps in integrated PET/MRI scanners.

    PubMed

    Poynton, Clare B; Chen, Kevin T; Chonde, Daniel B; Izquierdo-Garcia, David; Gollub, Randy L; Gerstner, Elizabeth R; Batchelor, Tracy T; Catana, Ciprian

    2014-01-01

    We present a new MRI-based attenuation correction (AC) approach for integrated PET/MRI systems that combines both segmentation- and atlas-based methods by incorporating dual-echo ultra-short echo-time (DUTE) and T1-weighted (T1w) MRI data and a probabilistic atlas. Segmented atlases were constructed from CT training data using a leave-one-out framework and combined with T1w, DUTE, and CT data to train a classifier that computes the probability of air/soft tissue/bone at each voxel. This classifier was applied to segment the MRI of the subject of interest and attenuation maps (?-maps) were generated by assigning specific linear attenuation coefficients (LACs) to each tissue class. The ?-maps generated with this "Atlas-T1w-DUTE" approach were compared to those obtained from DUTE data using a previously proposed method. For validation of the segmentation results, segmented CT ?-maps were considered to the "silver standard"; the segmentation accuracy was assessed qualitatively and quantitatively through calculation of the Dice similarity coefficient (DSC). Relative change (RC) maps between the CT and MRI-based attenuation corrected PET volumes were also calculated for a global voxel-wise assessment of the reconstruction results. The ?-maps obtained using the Atlas-T1w-DUTE classifier agreed well with those derived from CT; the mean DSCs for the Atlas-T1w-DUTE-based ?-maps across all subjects were higher than those for DUTE-based ?-maps; the atlas-based ?-maps also showed a lower percentage of misclassified voxels across all subjects. RC maps from the atlas-based technique also demonstrated improvement in the PET data compared to the DUTE method, both globally as well as regionally. PMID:24753982

  9. Comparison of 1.5T and 3T MRI scanners in evaluation of acute bone stress in the foot

    Microsoft Academic Search

    Markus J Sormaala; Juha-Petri Ruohola; Ville M Mattila; Seppo K Koskinen; Harri K Pihlajamäki

    2011-01-01

    Background  Bone stress injuries are common in athletes and military recruits. Only a minority of bone stress changes are available on\\u000a plain radiographs. Acute bone stress is often visible on MRI as bone marrow edema, which is also seen in many other disease\\u000a processes such as malignancies, inflammatory conditions and infections. The purpose of this study was to investigate the ability

  10. TESLA Polarimeters

    E-print Network

    V. Gharibyan; N. Meyners; K. P. Schuler

    2003-10-22

    We describe a study of high-energy Compton beam polarimeters for the future e+e- linear collider machine TESLA. A segment of the beam delivery system has been identified, which is aligned with the e+e- collision axis and which has a suitable configuration for high-quality beam polarization measurements. The laser envisaged for the polarimeter is similar to an existing facility at DESY. It delivers very short pulses in the 10 ps, 10-100uJ regime and operates with a pattern that matches the pulse and bunch structure of TESLA. This will permit very fast and accurate measurements and an expeditious tune-up of the spin manipulators at the low-energy end of the linac. Electron detection in the multi-event regime will be the principle operating mode of the polarimeter. Other possible operating modes include photon detection and single-event detection for calibration purposes. We expect an overall precision of dP/P=0.5% for the measurement of the beam polarization.

  11. Blood Pressure Changes Induced by Arterial Blood Withdrawal Influence Bold Signal in Anesthesized Rats at 7 Tesla: Implications for Pharmacologic MRI

    Microsoft Academic Search

    Raffael Kalisch; Gregor-Konstantin Elbel; Christoff Gössl; Michael Czisch; Dorothee P. Auer

    2001-01-01

    Functional magnetic resonance imaging (fMRI) using the blood oxygenation level-dependent (BOLD) contrast is now increasingly applied for measuring drug effects on brain activity. A possible confound in pharmacologic fMRI (phMRI) is that the BOLD signal may be sensitive to systemic cardiovascular or respiratory parameters, which can themselves be modulated by a drug. To assess whether abrupt changes in arterial blood

  12. Safety Implications of High-Field MRI: Actuation of Endogenous Magnetic Iron Oxides in the Human Body

    PubMed Central

    Dobson, Jon; Bowtell, Richard; Garcia-Prieto, Ana; Pankhurst, Quentin

    2009-01-01

    Background Magnetic Resonance Imaging scanners have become ubiquitous in hospitals and high-field systems (greater than 3 Tesla) are becoming increasingly common. In light of recent European Union moves to limit high-field exposure for those working with MRI scanners, we have evaluated the potential for detrimental cellular effects via nanomagnetic actuation of endogenous iron oxides in the body. Methodology Theoretical models and experimental data on the composition and magnetic properties of endogenous iron oxides in human tissue were used to analyze the forces on iron oxide particles. Principal Finding and Conclusions Results show that, even at 9.4 Tesla, forces on these particles are unlikely to disrupt normal cellular function via nanomagnetic actuation. PMID:19412550

  13. Can the Neural Basis of Repression Be Studied in the MRI Scanner? New Insights from Two Free Association Paradigms

    PubMed Central

    Kessler, Henrik; Do Lam, Anne T. A.; Fell, Juergen; Schmidt, Anna-Christine; Axmacher, Nikolai

    2013-01-01

    Background The psychodynamic theory of repression suggests that experiences which are related to internal conflicts become unconscious. Previous attempts to investigate repression experimentally were based on voluntary, intentional suppression of stimulus material. Unconscious repression of conflict-related material is arguably due to different processes, but has never been studied with neuroimaging methods. Methods We used functional magnetic resonance imaging (fMRI) in addition with skin conductance recordings during two free association paradigms to identify the neural mechanisms underlying forgetting of freely associated words according to repression theory. Results In the first experiment, free association to subsequently forgotten words was accompanied by increases in skin conductance responses (SCRs) and reaction times (RTs), indicating autonomic arousal, and by activation of the anterior cingulate cortex. These findings are consistent with the hypothesis that these associations were repressed because they elicited internal conflicts. To test this idea more directly, we conducted a second experiment in which participants freely associated to conflict-related sentences. Indeed, these associations were more likely to be forgotten than associations to not conflict-related sentences and were accompanied by increases in SCRs and RTs. Furthermore, we observed enhanced activation of the anterior cingulate cortex and deactivation of hippocampus and parahippocampal cortex during association to conflict-related sentences. Conclusions These two experiments demonstrate that high autonomic arousal during free association predicts subsequent memory failure, accompanied by increased activation of conflict-related and deactivation of memory-related brain regions. These results are consistent with the hypothesis that during repression, explicit memory systems are down-regulated by the anterior cingulate cortex. PMID:23638050

  14. Skin and proximity effects in the conductors of split gradient coils for a hybrid Linac-MRI scanner

    NASA Astrophysics Data System (ADS)

    Tang, Fangfang; Lopez, Hector Sanchez; Freschi, Fabio; Smith, Elliot; Li, Yu; Fuentes, Miguel; Liu, Feng; Repetto, Maurizio; Crozier, Stuart

    2014-05-01

    In magnetic resonance imaging (MRI), rapidly changing gradient fields are applied to encode the magnetic resonance signal with spatial position; however eddy currents are induced in the surrounding conducting structures depending on the geometry of the conductor and the excitation waveform. These alternating fields change the spatial profile of the current density within the coil track with the applied frequencies of the input waveform and by their proximity to other conductors. In this paper, the impact of the conductor width and the excited frequency over the parameters that characterise the performance of split transverse and longitudinal gradient coils are studied. Thirty x-gradient coils were designed using a “free-surface” coil design method and the track width was varied from 1 mm to 30 mm with an increment value of 1 mm; a frequency sweep analysis in the range of 100 Hz to 10 kHz was performed using the multi-layer integral method (MIM) and parameters such as power loss produced by the coil and generated in the cryostat, inductance, coil efficiency (field strength/operating current), magnetic field profile produced by the coil and the eddy currents were studied. An experimental validation of the theoretical model was performed on an example coil. Coils with filamentary conductor segments were also studied to compare the simulated parameters with those produced by coils with a finite track. There was found to be a significant difference between the parameters calculated using filamentary coils and those obtained when the coil is simulated using finite size tracks. A wider track width produces coil with superior efficiency and low resistance; however, due to the skin effect, the power loss increases faster in wider tracks than in those generated in coils with narrow tracks. It was demonstrated that rapidly changing current paths must be avoided in order to mitigate the power loss and the spatial asymmetry in the current density profile. The decision of using narrow or wider tracks in split coils should be carefully investigated using a temperature analysis which includes skin and proximity effects.

  15. Skin and proximity effects in the conductors of split gradient coils for a hybrid Linac-MRI scanner.

    PubMed

    Tang, Fangfang; Lopez, Hector Sanchez; Freschi, Fabio; Smith, Elliot; Li, Yu; Fuentes, Miguel; Liu, Feng; Repetto, Maurizio; Crozier, Stuart

    2014-05-01

    In magnetic resonance imaging (MRI), rapidly changing gradient fields are applied to encode the magnetic resonance signal with spatial position; however eddy currents are induced in the surrounding conducting structures depending on the geometry of the conductor and the excitation waveform. These alternating fields change the spatial profile of the current density within the coil track with the applied frequencies of the input waveform and by their proximity to other conductors. In this paper, the impact of the conductor width and the excited frequency over the parameters that characterise the performance of split transverse and longitudinal gradient coils are studied. Thirty x-gradient coils were designed using a "free-surface" coil design method and the track width was varied from 1mm to 30mm with an increment value of 1mm; a frequency sweep analysis in the range of 100Hz to 10kHz was performed using the multi-layer integral method (MIM) and parameters such as power loss produced by the coil and generated in the cryostat, inductance, coil efficiency (field strength/operating current), magnetic field profile produced by the coil and the eddy currents were studied. An experimental validation of the theoretical model was performed on an example coil. Coils with filamentary conductor segments were also studied to compare the simulated parameters with those produced by coils with a finite track. There was found to be a significant difference between the parameters calculated using filamentary coils and those obtained when the coil is simulated using finite size tracks. A wider track width produces coil with superior efficiency and low resistance; however, due to the skin effect, the power loss increases faster in wider tracks than in those generated in coils with narrow tracks. It was demonstrated that rapidly changing current paths must be avoided in order to mitigate the power loss and the spatial asymmetry in the current density profile. The decision of using narrow or wider tracks in split coils should be carefully investigated using a temperature analysis which includes skin and proximity effects. PMID:24607826

  16. Functional MRI compliance in children with attention deficit hyperactivity disorder

    PubMed Central

    Karaka?, Sirel; Dinçer, Elvin Do?utepe; Ceylan, Arzu Özkan; Tileylio?lu, Emre; Karaka?, Hakk? Muammer; Tal?, E. Turgut

    2015-01-01

    PURPOSE We aimed to test the effect of prescan training and orientation in functional magnetic resonance imaging (fMRI) in children with attention deficit hyperactivity disorder (ADHD) and to investigate whether fMRI compliance was modified by state anxiety. METHODS Subjects included 77 males aged 6–12 years; there were 53 patients in the ADHD group and 24 participants in the healthy control group. Exclusion criteria included neurological and/or psychiatric comorbidities (other than ADHD), the use of psychoactive drugs, and an intelligence quotient outside the normal range. Children were individually subjected to prescan orientation and training. Data were acquired using a 1.5 Tesla scanner and an 8-channel head coil. Functional scans were performed using a standard neurocognitive task. RESULTS The neurocognitive task led to reliable fMRI maps. Compliance was not significantly different between ADHD and control groups based on success, failure, and repetition rates of fMRI. Compliance of ADHD patients with extreme levels of anxiety was also not significantly different. CONCLUSION The fMRI compliance of ADHD children is typically lower than that of healthy children. However, compliance can be increased to the level of age-matched healthy control children by addressing concerns about the technical and procedural aspects of fMRI, providing orientation programs, and performing on-task training. In patients thus trained, compliance does not change with the level of state anxiety suggesting that the anxiety hypothesis of fMRI compliance is not supported. PMID:25519454

  17. Early Metacarpal Bone Mineral Density Loss Using Digital X-Ray Radiogrammetry and 3-Tesla Wrist MRI in Established Rheumatoid Arthritis: A Longitudinal One-Year Observational Study

    PubMed Central

    Algulin, Jakob; Mangat, Pamela; Lim, Adrian K. P.; Satchithananda, Keshthra; Hajnal, Joseph V.; Taylor, Peter C.

    2015-01-01

    Objectives. Early change in rheumatoid arthritis (RA) is characterised by periarticular osteopenia. We investigated the relationship of early metacarpal digital X-ray radiogrammetry bone mineral density (DXR-BMD) change rate (RC-BMD, mg/cm2/month) to longitudinal changes in hand and feet radiographic and wrist MRI scores over 1 year. Materials and Methods. 10 RA patients completed the study and had wrist 3T-MRI and hand and feet X-rays at various time points over 1 year. MRI was scored by RAMRIS, X-ray was done by van der Heijde modified Sharp scoring, and RC-BMD was analysed using dxr-online. Results. There was good correlation amongst the two scorers for MRI measures and ICC for erosions: 0.984, BME: 0.943, and synovitis: 0.657. Strong relationships were observed between RC-BMD at 12-week and 1-year change in wrist marrow oedema (BME) (r = 0.78, P = 0.035) but not with erosion, synovitis, or radiographic scores. Conclusion. Early RC-BMD correlates with 1-year wrist BME change, which is a known predictor of future erosion and joint damage. However, in our pilot study, early RC-BMD did not show relationships to MRI erosion or radiographic changes over 1 year. This may reflect a slower kinetic in the appearance of MRI/radiographic erosions, generating the hypothesis that RC-BMD may be a more sensitive and early structural prognostic marker in RA follow-up. PMID:25785197

  18. Simultaneous Measurement of Kidney Function by Dynamic Contrast Enhanced MRI and FITC-Sinistrin Clearance in Rats at 3 Tesla: Initial Results

    PubMed Central

    Bäcker, Sandra; Neudecker, Sabine; Gretz, Norbert; Schad, Lothar R.

    2013-01-01

    Glomerular filtration rate (GFR) is an essential parameter of kidney function which can be measured by dynamic contrast enhanced magnetic resonance imaging (MRI-GFR) and transcutaneous approaches based on fluorescent tracer molecules (optical-GFR). In an initial study comparing both techniques in separate measurements on the same animal, the correlation of the obtained GFR was poor. The goal of this study was to investigate if a simultaneous measurement was feasible and if thereby, the discrepancies in MRI-GFR and optical-GFR could be reduced. For the experiments healthy and unilateral nephrectomised (UNX) Sprague Dawley (SD) rats were used. The miniaturized fluorescent sensor was fixed on the depilated back of an anesthetized rat. A bolus of 5 mg/100 g b.w. of FITC-sinistrin was intravenously injected. For dynamic contrast enhanced perfusion imaging (DCE-MRI) a 3D time-resolved angiography with stochastic trajectories (TWIST) sequence was used. By means of a one compartment model the excretion half-life (t1/2) of FITC-sinistrin was calculated and converted into GFR. GFR from DCE-MRI was calculated by fitting pixel-wise a two compartment renal filtration model. Mean cortical GFR and GFR by FITC-sinistrin were compared by Bland-Altman plots and pair-wise t-test. Results show that a simultaneous GFR measurement using both techniques is feasible. Mean optical-GFR was 4.34±2.22 ml/min (healthy SD rats) and 2.34±0.90 ml/min (UNX rats) whereas MRI-GFR was 2.10±0.64 ml/min (SD rats) and 1.17±0.38 ml/min (UNX rats). Differences between healthy and UNX rats were significant (p<0.05) and almost equal percentage difference (46.1% and 44.3%) in mean GFR were assessed with both techniques. Overall mean optical-GFR values were approximately twice as high compared to MRI-GFR values. However, compared to a previous study, our results showed a higher agreement. In conclusion, the possibility to use the transcutaneous method in MRI may have a huge impact in improving and validating MRI methods for GFR assessment in animal models. PMID:24260332

  19. Simultaneous measurement of kidney function by dynamic contrast enhanced MRI and FITC-sinistrin clearance in rats at 3 tesla: initial results.

    PubMed

    Zöllner, Frank G; Schock-Kusch, Daniel; Bäcker, Sandra; Neudecker, Sabine; Gretz, Norbert; Schad, Lothar R

    2013-01-01

    Glomerular filtration rate (GFR) is an essential parameter of kidney function which can be measured by dynamic contrast enhanced magnetic resonance imaging (MRI-GFR) and transcutaneous approaches based on fluorescent tracer molecules (optical-GFR). In an initial study comparing both techniques in separate measurements on the same animal, the correlation of the obtained GFR was poor. The goal of this study was to investigate if a simultaneous measurement was feasible and if thereby, the discrepancies in MRI-GFR and optical-GFR could be reduced. For the experiments healthy and unilateral nephrectomised (UNX) Sprague Dawley (SD) rats were used. The miniaturized fluorescent sensor was fixed on the depilated back of an anesthetized rat. A bolus of 5 mg/100 g b.w. of FITC-sinistrin was intravenously injected. For dynamic contrast enhanced perfusion imaging (DCE-MRI) a 3D time-resolved angiography with stochastic trajectories (TWIST) sequence was used. By means of a one compartment model the excretion half-life (t1/2) of FITC-sinistrin was calculated and converted into GFR. GFR from DCE-MRI was calculated by fitting pixel-wise a two compartment renal filtration model. Mean cortical GFR and GFR by FITC-sinistrin were compared by Bland-Altman plots and pair-wise t-test. Results show that a simultaneous GFR measurement using both techniques is feasible. Mean optical-GFR was 4.34 ± 2.22 ml/min (healthy SD rats) and 2.34 ± 0.90 ml/min (UNX rats) whereas MRI-GFR was 2.10 ± 0.64 ml/min (SD rats) and 1.17 ± 0.38 ml/min (UNX rats). Differences between healthy and UNX rats were significant (p<0.05) and almost equal percentage difference (46.1% and 44.3%) in mean GFR were assessed with both techniques. Overall mean optical-GFR values were approximately twice as high compared to MRI-GFR values. However, compared to a previous study, our results showed a higher agreement. In conclusion, the possibility to use the transcutaneous method in MRI may have a huge impact in improving and validating MRI methods for GFR assessment in animal models. PMID:24260332

  20. Simultaneous hyperpolarized (13)C-pyruvate MRI and (18)F-FDG-PET in cancer (hyperPET): feasibility of a new imaging concept using a clinical PET/MRI scanner.

    PubMed

    Gutte, Henrik; Hansen, Adam E; Henriksen, Sarah T; Johannesen, Helle H; Ardenkjaer-Larsen, Jan; Vignaud, Alexandre; Hansen, Anders E; Børresen, Betina; Klausen, Thomas L; Wittekind, Anne-Mette N; Gillings, Nic; Kristensen, Annemarie T; Clemmensen, Andreas; Højgaard, Liselotte; Kjær, Andreas

    2015-01-01

    In this paper we demonstrate, for the first time, the feasibility of a new imaging concept - combined hyperpolarized (13)C-pyruvate magnetic resonance spectroscopic imaging (MRSI) and (18)F-FDG-PET imaging. This procedure was performed in a clinical PET/MRI scanner with a canine cancer patient. We have named this concept hyper PET. Intravenous injection of the hyperpolarized (13)C-pyruvate results in an increase of (13)C-lactate, (13)C-alanine and (13)C-CO2 ((13)C-HCO3) resonance peaks relative to the tissue, disease and the metabolic state probed. Accordingly, with dynamic nuclear polarization (DNP) and use of (13)C-pyruvate it is now possible to directly study the Warburg Effect through the rate of conversion of (13)C-pyruvate to (13)C-lactate. In this study, we combined it with (18)F-FDG-PET that studies uptake of glucose in the cells. A canine cancer patient with a histology verified local recurrence of a liposarcoma on the right forepaw was imaged using a combined PET/MR clinical scanner. PET was performed as a single-bed, 10 min acquisition, 107 min post injection of 310 MBq (18)F-FDG. (13)C-chemical shift imaging (CSI) was performed just after FDG-PET and 30 s post injection of 23 mL hyperpolarized (13)C-pyruvate. Peak heights of (13)C-pyruvate and (13)C-lactate were quantified using a general linear model. Anatomic (1)H-MRI included axial and coronal T1 vibe, coronal T2-tse and axial T1-tse with fat saturation following gadolinium injection. In the tumor we found clearly increased (13)C-lactate production, which also corresponded to high (18)F-FDG uptake on PET. This is in agreement with the fact that glycolysis and production of lactate are increased in tumor cells compared to normal cells. Yet, most interestingly, also in the muscle of the forepaw of the dog high (18)F-FDG uptake was observed. This was due to activity in these muscles prior to anesthesia, which was not accompanied by a similarly high (13)C-lactate production. Accordingly, this clearly demonstrates how the Warburg Effect directly can be demonstrated by hyperpolarized (13)C-pyruvate MRSI. This was not possible with (18)F-FDG-PET imaging due to inability to discriminate between causes of increased glucose uptake. We propose that this new concept of simultaneous hyperpolarized (13)C-pyruvate MRSI and PET may be highly valuable for image-based non-invasive phenotyping of tumors. This methods may be useful for treatment planning and therapy monitoring. PMID:25625025

  1. Scanner Art

    ERIC Educational Resources Information Center

    Jaworski, Joy; Murphy, Kris

    2009-01-01

    In this article, the authors describe how they incorporated environmental awareness into their art curriculum. Here, they describe a digital photography project in which their students used flatbed scanners as cameras. Their students composed their objects directly on the scanner. The lesson enabled students to realize that artists have voices…

  2. Real-time magnetic resonance imagingguided radiofrequency atrial ablation and visualization of lesion formation at 3 Tesla

    E-print Network

    Utah, University of

    of lesion formation at 3 Tesla Gaston R. Vergara, MD,* Sathya Vijayakumar, MS,* Eugene G. Kholmovski, Ph. In this study, we report a novel 3-Tesla RT -RI based porcine RF ablation model and visuali- zation of lesion-Tesla RT MRI-based catheter ablation and lesion visualization system. METHODS RF energy was delivered

  3. Functional MRI at 4.7 Tesla of the Rat Brain during Electric Stimulation of Forepaw, Hindpaw, or Tail in Single and Multislice Experiments

    Microsoft Academic Search

    C. Spenger; A. Josephson; T. Klason; M. Hoehn; W. Schwindt; M. Ingvar; L. Olson

    2000-01-01

    Stimulation of peripheral nerves activates corresponding regions in sensorimotor cortex. We have applied functional magnetic resonance imaging (fMRI) techniques to monitor activated brain regions by means of measuring changes of blood oxygenation level-dependent contrast during electric stimulation of the forepaw, hindpaw, or tail in rats. During ?-chloralose anesthesia, artificial respiration, and complete muscle relaxation, stimulations were delivered at 3 Hz

  4. Preoperative 3-Tesla multiparametric endorectal MRI findings and the odds of upgrading and upstaging at radical prostatectomy in men with clinically localized prostate cancer

    PubMed Central

    Hegde, John V.; Chen, Ming-Hui; Mulkern, Robert V.; Fennessy, Fiona M.; D’Amico, Anthony V.; Tempany, Clare M. C.

    2012-01-01

    Purpose To investigate whether 3T multiparametric endorectal MRI (erMRI) can add information to established predictors regarding occult extraprostatic or high-grade prostate cancer (PC) in men with clinically localized PC. Methods and Materials At a single academic medical center, this retrospective study’s cohort included 118 men with clinically localized PC who underwent 3T multiparametric erMRI followed by radical prostatectomy (RP) from 2008 to 2011. Multivariable logistic regression analyses in all men and in 100 with favorable-risk PC addressed whether erMRI evidence of T3 disease was associated with prostatectomy T3 or Gleason score (GS) 8–10 (in patients with biopsy GS ? 7) PC, adjusting for age, PSA level, clinical T-category, biopsy GS, and percent positive biopsies. Results The accuracy of erMRI prediction of extracapsular extension and seminal vesicle invasion was 75% and 95%, respectively. For all men, erMRI evidence of a T3 lesion vs. T2 was associated with an increased odds of having pT3 disease (adjusted odds ratio (AOR) 4.81, 95% confidence interval (CI) (1.36, 16.98), p=0.015) and pGS 8–10 (AOR 5.56, (1.10, 28.18), p=0.038). In the favorable-risk population, these results were AOR 4.14, (1.03, 16.56), p=0.045 and AOR 7.71, (1.36, 43.62), p=0.021, respectively. Conclusions 3T multiparametric erMRI in men with favorable-risk PC provides information beyond that contained in known preoperative predictors about the presence of occult extraprostatic and/or high-grade PC. If validated in additional studies, this information can be used to counsel men planning to undergo RP or radiotherapy (RT) about the possible need for adjuvant RT or the utility of adding hormone therapy, respectively. PMID:23040223

  5. MRI

    NSDL National Science Digital Library

    Patient Education Institute

    This patient education program explains Magnetic Resonance Imaging (MRI), the role of this imaging in diagnosis, the procedure itself, and associated benefits and risks. This is a MedlinePlus Interactive Health Tutorial from the National Library of Medicine, designed and developed by the Patient Education Institute. NOTE: The tutorial requires a special Flash plug-in, version 4 or above. If you do not have Flash, you will be prompted to obtain a free download of the software before you start the tutorial. You will also need an Acrobat Reader, available as a free download, in order to view the Reference Summary.

  6. Edison vs. Tesla

    SciTech Connect

    Hogan, Kathleen; Wallace, Hal; Ivestor, Rob

    2013-11-20

    As Edison vs. Tesla week heats up at the Energy Department, we are exploring the rivalry between Thomas Edison and Nikola Tesla and how their work is still impacting the way we use energy today. Whether you're on Team Tesla or Team Edison, both inventors were key players in creating things like batteries, power plants and wireless technologies -- all innovations we still use today. And as we move toward a clean energy future, energy efficient lighting, like LED bulbs, and more efficient electric motors not only help us save money on electricity costs but help combat climate change. For this, Tesla and Edison both deserve our recognition.

  7. Edison vs. Tesla

    ScienceCinema

    Hogan, Kathleen; Wallace, Hal; Ivestor, Rob

    2014-01-07

    As Edison vs. Tesla week heats up at the Energy Department, we are exploring the rivalry between Thomas Edison and Nikola Tesla and how their work is still impacting the way we use energy today. Whether you're on Team Tesla or Team Edison, both inventors were key players in creating things like batteries, power plants and wireless technologies -- all innovations we still use today. And as we move toward a clean energy future, energy efficient lighting, like LED bulbs, and more efficient electric motors not only help us save money on electricity costs but help combat climate change. For this, Tesla and Edison both deserve our recognition.

  8. TESLA-Report 1993-33 TESLA-Report 1993-33

    E-print Network

    #12;TESLA-Report 1993-33 #12;TESLA-Report 1993-33 #12;TESLA-Report 1993-33 #12;TESLA-Report 1993-33 #12;TESLA-Report 1993-33 #12;TESLA-Report 1993-33 #12;TESLA-Report 1993-33 #12;TESLA-Report 1993-33 #12;TESLA-Report 1993-33 #12;TESLA-Report 1993-33 #12;TESLA-Report 1993-33 #12;TESLA-Report 1993

  9. TESLA-Report 1995-11 TESLA-Report 1995-11

    E-print Network

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  10. TESLA-Report 2002-07 TESLA-Report 2002-07

    E-print Network

    #12;#12;#12;#12;TESLA-Report 2002-07 #12;TESLA-Report 2002-07 #12;TESLA-Report 2002-07 #12;TESLA-Report 2002-07 #12;TESLA-Report 2002-07 #12;TESLA-Report 2002-07 #12;TESLA-Report 2002-07 #12;TESLA-Report 2002-07 #12;TESLA-Report 2002-07 #12;TESLA-Report 2002-07 #12;TESLA-Report 2002-07 #12;TESLA

  11. Line Scanners Basic line-scanner principle

    E-print Network

    Giger, Christine

    to the ground coordinate system · NB: satellite line scanners · line scanners are especially popularLine Scanners #12;Principle · Basic line-scanner principle #12;Principle · Sensor · single CCD line oriented perpendicular to the scanning (=flight) direction, often called "pushbroom scanner" · Scanning

  12. Multi-Channel Metabolic Imaging, with SENSE reconstruction, of Hyperpolarized [1-13C] Pyruvate in a Live Rat at 3.0 tesla on a Clinical MR Scanner*

    PubMed Central

    Tropp, James; Lupo, Janine M.; Chen, Albert; Calderon, Paul; McCune, Don; Grafendorfer, Thomas; Ozturk-Isik, Esin; Larson, Peder E. Z.; Hu, Simon; Yen, Yi-Fen; Robb, Fraser; Bok, Robert; Schulte, Rolf; Xu, Duan; Hurd, Ralph; Vigneron, Daniel; Nelson, Sarah

    2012-01-01

    We report metabolic images of 13C, following injection of a bolus of of hyperpolarized [1-13C] pyruvate in a live rat. The data were acquired on a clinical scanner, using custom coils for volume transmission and array reception. Proton blocking of all carbon resonators enabled proton anatomic imaging with the system body coil, to allow for registration of anatomic and metabolic images, for which good correlation was achieved, with some anatomic features (kidney and heart) clearly visible in a carbon image, without reference to the corresponding proton image. Parallel imaging with sensitivity encoding was used to increase the spatial resolution in the SI direction of the rat. The signal to noise ratio in was in some instances unexpectedly high in the parallel images; variability of the polarization among different trials, plus partial volume effects, are noted as a possible cause of this. PMID:21130012

  13. Permeability Parameters Measured with Dynamic Contrast-Enhanced MRI: Correlation with the Extravasation of Evans Blue in a Rat Model of Transient Cerebral Ischemia

    PubMed Central

    Choi, Hyun Seok; Ahn, Sung Soo; Shin, Na-Young; Kim, Jinna; Kim, Jae Hyung; Lee, Jong Eun; Lee, Hye Yeon; Heo, Ji Hoe

    2015-01-01

    Objective The purpose of this study was to correlate permeability parameters measured with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) using a clinical 3-tesla scanner with extravasation of Evans blue in a rat model with transient cerebral ischemia. Materials and Methods Sprague-Dawley rats (n = 13) with transient middle cerebral artery occlusion were imaged using a 3-tesla MRI with an 8-channel wrist coil. DCE-MRI was performed 12 hours, 18 hours, and 36 hours after reperfusion. Permeability parameters (Ktrans, ve, and vp) from DCE-MRI were calculated. Evans blue was injected after DCE-MRI and extravasation of Evans blue was correlated as a reference with the integrity of the blood-brain barrier. Correlation analysis was performed between permeability parameters and the extravasation of Evans blue. Results All permeability parameters (Ktrans, ve, and vp) showed a linear correlation with extravasation of Evans blue. Among them, Ktrans showed highest values of both the correlation coefficient and the coefficient of determination (0.687 and 0.473 respectively, p < 0.001). Conclusion Permeability parameters obtained by DCE-MRI at 3-T are well-correlated with Evans blue extravasation, and Ktrans shows the strongest correlation among the tested parameters. PMID:26175578

  14. Development of functional imaging in the human brain (fMRI); the University of Minnesota experience.

    PubMed

    U?urbil, Kâmil

    2012-08-15

    The human functional magnetic resonance imaging (fMRI) experiments performed in the Center for Magnetic Resonance Research (CMRR), University of Minnesota, were planned between two colleagues who had worked together previously in Bell Laboratories in the late nineteen seventies, namely myself and Seiji Ogawa. These experiments were motivated by the Blood Oxygenation Level Dependent (BOLD) contrast developed by Seiji. We discussed and planned human studies to explore imaging human brain activity using the BOLD mechanism on the 4 Tesla human system that I was expecting to receive for CMRR. We started these experiments as soon as this 4 Tesla instrument became marginally operational. These were the very first studies performed on the 4 Tesla scanner in CMRR; had the scanner become functional earlier, they would have been started earlier as well. We were aware of the competing effort at the Massachusetts General Hospital (MGH) and we knew that they had been informed of our initiative in Minneapolis to develop fMRI. We had positive results certainly by August 1991 annual meeting of the Society of Magnetic Resonance in Medicine (SMRM). I believe, however, that neither the MGH colleagues nor us, at the time, had enough data and/or conviction to publish these extraordinary observations; it took more or less another six months or so before the papers from these two groups were submitted for publication within five days of each other to the Proceedings of the National Academy of Sciences, USA, after rejection by Nature in our case. Thus, fMRI was achieved independently and at about the same time at MGH, in an effort credited largely to Ken Kwong, and in CMRR, University of Minnesota in an effort led by myself and Seiji Ogawa. PMID:22342875

  15. Miniaturized fiber-optic transmission system for MRI signals.

    PubMed

    Memis, Omer Gokalp; Eryaman, Yigitcan; Aytur, Orhan; Atalar, Ergin

    2008-01-01

    Conventional MRI instruments transmit received MRI signals through electrical cables. Although this design has proved to be effective over the years, we report a fiber-optic system that addresses the needs of recent developments in MRI technology. One of these technologies is phased array coils with a high number of elements, where total size of interconnections is a primary problem, and other problem is internal MRI coils, where there is a need for improvements in safety. The Miniature Fiber-Optic Transmission (FOT) System was developed to address these issues. The system consists of a receiver coil with active detuning, a low-noise preamplifier, and a laser diode connected to a photodetector with fiber-optic cabling. The overall noise figure of the system is lower than 1 dB. Total power consumption is 50 mW, and the device is switchable with another fiber-optic line, which can also control active detuning. A prototype device was tested in a GE 1.5 Tesla MRI scanner, and several images were acquired with a signal to noise ratio similar to coaxial cabling. We believe that this design will reduce the cabling problems of arrays and enable placement of internal coils into body cavities with no safety hazard to the patient, such as electrical shock or burns. PMID:18098294

  16. Physics at TESLA

    E-print Network

    Grahame A. Blair

    2001-04-25

    The physics at a 500-800 GeV electron positron linear collider, TESLA, is reviewed. The machine parameters that impact directly on the physics are discussed and a few key performance goals for a detector at TESLA are given. Emphasis is placed on precision measurements in the Higgs and top sectors and on extrapolation to high energy scales in the supersymmetric scenario.

  17. TESLA Report 2003-32 FPGA based TESLA cavity SIMCON

    E-print Network

    TESLA Report 2003-32 FPGA based TESLA cavity SIMCON DOOCS server design, implementation of the laboratory solution of the FPGA based TESLA cavity simulator and controller (SIMCON) is presented. The major is a first description of the working DOOCS server for the FPGA based TESLA cavity SIMCON (which is a part

  18. TESLA FEL-Report 1999-03 TESLA FEL-Report 1999-03

    E-print Network

    TESLA FEL-Report 1999-03 #12;TESLA FEL-Report 1999-03 #12;TESLA FEL-Report 1999-03 #12;TESLA FEL-Report 1999-03 #12;TESLA FEL-Report 1999-03 #12;TESLA FEL-Report 1999-03 #12;TESLA FEL-Report 1999-03 #12;TESLA FEL-Report 1999-03 #12;TESLA FEL-Report 1999-03 #12;TESLA FEL-Report 1999-03 #12;TESLA FEL

  19. TESLA FEL Report 1996-06 TESLA FEL Report 1996-06

    E-print Network

    TESLA FEL Report 1996-06 #12;TESLA FEL Report 1996-06 #12;TESLA FEL Report 1996-06 #12;TESLA FEL Report 1996-06 #12;TESLA FEL Report 1996-06 #12;TESLA FEL Report 1996-06 #12;TESLA FEL Report 1996-06 #12;TESLA FEL Report 1996-06 #12;TESLA FEL Report 1996-06 #12;TESLA FEL Report 1996-06 #12;TESLA FEL Report

  20. TESLA FEL-Report 1996-16 TESLA FEL-Report 1996-16

    E-print Network

    #12;TESLA FEL-Report 1996-16 #12;TESLA FEL-Report 1996-16 #12;TESLA FEL-Report 1996-16 #12;TESLA FEL-Report 1996-16 #12;TESLA FEL-Report 1996-16 #12;TESLA FEL-Report 1996-16 #12;TESLA FEL-Report 1996-16 #12;TESLA FEL-Report 1996-16 #12;TESLA FEL-Report 1996-16 #12;TESLA FEL-Report 1996-16 #12;TESLA FEL

  1. TESLA FEL-Report 1995-02 TESLA FEL-Report 1995-02

    E-print Network

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  2. TESLA FEL-Report 1995-04 TESLA FEL-Report 1995-04

    E-print Network

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  3. TESLA FEL Report 1996-07 TESLA FEL Report 1996-07

    E-print Network

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  4. TESLA FEL-Report 1996-10 TESLA FEL-Report 1996-10

    E-print Network

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  5. TESLA FEL-Report 1996-13 TESLA FEL-Report 1996-13

    E-print Network

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  6. TESLA FEL-Report 2000-02 TESLA FEL-Report 2000-02

    E-print Network

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  7. TESLA FEL-Report 1997-02 TESLA FEL-Report 1997-02

    E-print Network

    TESLA FEL-Report 1997-02 #12;TESLA FEL-Report 1997-02 #12;TESLA FEL-Report 1997-02 #12;TESLA FEL-Report 1997-02 #12;TESLA FEL-Report 1997-02 #12;TESLA FEL-Report 1997-02 #12;TESLA FEL-Report 1997-02 #12;TESLA FEL-Report 1997-02 #12;TESLA FEL-Report 1997-02 #12;TESLA FEL-Report 1997-02 #12;TESLA FEL

  8. In Vivo13C Magnetic Resonance Spectroscopy of Human Brain on a Clinical 3 Tesla Scanner Using [2-13C]Glucose Infusion and Low Power Stochastic Decoupling

    PubMed Central

    Li, Shizhe; Zhang, Yan; Wang, Shumin; Yang, Jehoon; Araneta, Maria Ferraris; Farris, Amanda; Johnson, Christopher; Fox, Stephen; Innis, Robert; Shen, Jun

    2009-01-01

    This study presents the detection of [2-13C]glucose metabolism in the carboxylic/amide region in the human brain, and demonstrates that the cerebral metabolism of [2-13C]glucose can be studied in human subjects in the presence of severe hardware constraints of widely available 3 T clinical scanners and with low power stochastic decoupling. In the carboxylic/amide region of human brain, the primary products of 13C label incorporation from [2-13C]glucose into glutamate, glutamine, aspartate, ?-aminobutyric acid, and N-acetylaspartate were detected. Unlike the commonly used alkanyl region where lipid signals spread over a broad frequency range, the carboxylic carbon signal of lipids was found to be confined to a narrow range centered at 172.5 ppm and present no spectral interference in the absence of lipid suppression. Comparison using phantoms shows that stochastic decoupling is far superior than the commonly used WALTZ sequence at very low decoupling power at 3 T. It was found that glutamine C1 and C5 can be decoupled using stochastic decoupling at 2.2 W although glutamine protons span a frequency range of ?700 Hz. Detailed specific absorption rate analysis was also performed using finite difference time domain numerical simulation. PMID:19526500

  9. Magnetic resonance imaging of iron-oxide labeled SK-Mel 28 human melanoma cells in the chick embryo using a clinical whole body MRI scanner

    Microsoft Academic Search

    M. Oppitz; J. Pintaske; R. Kehlbach; F. Schick; G. Schriek; C. Busch

    2007-01-01

    Purpose: To evaluate advantages and limitations of magnetic resonance imaging (MRI) to monitor the migration of superparamagnetic\\u000a iron oxide (SPIO) labeled cells in the chick embryo.\\u000a \\u000a \\u000a Materials and methods: Labeled human SK-Mel 28 melanoma cells were injected into the E2 chick embryo neural tube. Embryos were examined with a\\u000a clinical 3 T MRI whole body system using 3D T2*-weighted sequences

  10. Role of HRCT and MRI of the Temporal Bone in Predicting and Grading the Degree of Difficulty of Cochlear Implant Surgery.

    PubMed

    Vaid, Sanjay; Vaid, Neelam; Manikoth, Manoj; Zope, Amit

    2015-06-01

    This study proposes a grading system based on a 10-point scoring chart of high resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) imaging findings in patients being assessed preoperatively for cochlear implantation. This system helps in objectively assessing the degree of difficulty of the surgical procedure and alerts the surgeons to any potential intraoperative complications. This is a prospective study carried out at a tertiary referral center where 55 patients with bilateral profound sensorineural hearing loss were evaluated by HRCT and MRI and subsequently underwent cochlear implantation. HRCT examinations were performed on a 64 slice multidetector CT scanner. MRI examinations were performed on a 3.0 Tesla MRI scanner. A 10-point scoring chart was devised based on specific imaging findings and all patients were assigned potential difficulty scores (PDS) based on HRCT and MRI findings. Surgical times were documented in each case and each imaging point on the scoring chart was correlated with the surgical times. Eight out of theó ten points in the scoring chart proved to be statistically significant in predicting the degree of difficulty of the surgical procedure. After grading the pre-operative imaging examinations based on the 10-point scoring chart we concluded that patients who have PDS between 0 and 3 (Grade 1) have uneventful and uncomplicated surgery with the lowest intraoperative times. Patients with PDS between 4 and 7 alert the surgeon to moderate surgical difficulty and longer intraoperative times. PDS of 8 and above indicate prolonged and difficult surgery. PMID:26075170

  11. TESLA-Report 1994-24 TESLA-Report 1994-24

    E-print Network

    TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12;TESLA-Report 1994-24 #12

  12. TESLA-Report 1994-17 TESLA-Report 1994-17

    E-print Network

    TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12;TESLA-Report 1994-17 #12

  13. TESLA-Report 1993-39 TESLA-Report 1993-39

    E-print Network

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  14. TESLA-Report 1994-11 TESLA-Report 1994-11

    E-print Network

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  15. TESLA-Report 1994-31 TESLA-Report 1994-31

    E-print Network

    TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12;TESLA-Report 1994-31 #12

  16. TESLA-Report 1999-18 TESLA-Report 1999-18

    E-print Network

    TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12;TESLA-Report 1999-18 #12

  17. TESLA-Report 1996-12 TESLA-Report 1996-12

    E-print Network

    TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12;TESLA-Report 1996-12 #12

  18. TESLA FEL-Report 1999-04 TESLA FEL-Report 1999-07

    E-print Network

    TESLA FEL-Report 1999-04 TESLA FEL-Report 1999-07 #12;TESLA FEL-Report 1999-04 TESLA FEL-Report 1999-07 #12;TESLA FEL-Report 1999-04 TESLA FEL-Report 1999-07 #12;TESLA FEL-Report 1999-04 TESLA FEL-Report 1999-07 #12;TESLA FEL-Report 1999-04 TESLA FEL-Report 1999-07 #12;TESLA FEL-Report 1999-04 TESLA FEL

  19. Design of an fMRI-compatible optical touch stripe based on frustrated total internal reflection.

    PubMed

    Jarrahi, Behnaz; Wanek, Johann

    2014-08-01

    Previously we developed a low-cost, multi-configurable handheld response system, using a reflective-type intensity modulated fiber-optic sensor (FOS) [1] to accurately gather participants' behavioral responses during functional magnetic resonance imaging (fMRI). Inspired by the popularity and omnipresence of the fingertip-based touch sensing user interface devices, in this paper we present the design of a prototype fMRI-compatible optical touch stripe (OTS) as an alternative configuration. The prototype device takes advantage of a proven frustrated total internal reflection (FTIR) technique. By using a custom-built wedge-shaped optically transparent acrylic prism as an optical waveguide, and a plano-concave lens to provide the required light beam profile, the position of a fingertip touching the surface of the wedge prism can be determined from the deflected light beams that become trapped within the prism by total internal reflection. To achieve maximum sensitivity, the optical design of the wedge prism and lens were optimized through a series of light beam simulations using WinLens 3D Basic software suite. Furthermore, OTS performance and MRI-compatibility were assessed on a 3.0 Tesla MRI scanner running echo planar imaging (EPI) sequences. The results show that the OTS can detect a touch signal at high spatial resolution (about 0.5 cm), and is well suited for use within the MRI environment with average time-variant signal-to-noise ratio (tSNR) loss <; 3%. PMID:25571103

  20. Dynamic multi-coil technique (DYNAMITE) shimming for echo-planar imaging of the human brain at 7 Tesla.

    PubMed

    Juchem, Christoph; Umesh Rudrapatna, S; Nixon, Terence W; de Graaf, Robin A

    2015-01-15

    Gradient-echo echo-planar imaging (EPI) is the primary method of choice in functional MRI and other methods relying on fast MRI to image brain activation and connectivity. However, the high susceptibility of EPI towards B0 magnetic field inhomogeneity poses serious challenges. Conventional magnetic field shimming with low-order spherical harmonic (SH) functions is capable of compensating shallow field distortions, but performs poorly for global brain shimming or on specific areas with strong susceptibility-induced B0 distortions such as the prefrontal cortex (PFC). Excellent B0 homogeneity has been demonstrated recently in the human brain at 7 Tesla with the DYNAmic Multi-coIl TEchnique (DYNAMITE) for magnetic field shimming (J Magn Reson (2011) 212:280-288). Here, we report the benefits of DYNAMITE shimming for multi-slice EPI and T2* mapping. A standard deviation of 13Hz was achieved for the residual B0 distribution in the human brain at 7 Tesla with DYNAMITE shimming and was 60% lower compared to conventional shimming that employs static zero through third order SH shapes. The residual field inhomogeneity with SH shimming led to an average 8mm shift at acquisition parameters commonly used for fMRI and was reduced to 1.5-3mm with DYNAMITE shimming. T2* values obtained from the prefrontal and temporal cortices with DYNAMITE shimming were 10-50% longer than those measured with SH shimming. The reduction of the confounding macroscopic B0 field gradients with DYNAMITE shimming thereby promises improved access to the relevant microscopic T2* effects. The combination of high spatial resolution and DYNAMITE shimming allows largely artifact-free EPI and T2* mapping throughout the brain, including prefrontal and temporal lobe areas. DYNAMITE shimming is expected to critically benefit a wide range of MRI applications that rely on excellent B0 magnetic field conditions including EPI-based fMRI to study various cognitive processes and assessing large-scale brain connectivity in vivo. As such, DYNAMITE shimming has the potential to replace conventional SH shim systems in human MR scanners. PMID:25462795

  1. Prostate magnetic resonance imaging at 3 Tesla: Is administration of hyoscine-N-butyl-bromide mandatory?

    PubMed Central

    Roethke, Matthias C; Kuru, Timur H; Radbruch, Alexander; Hadaschik, Boris; Schlemmer, Heinz-Peter

    2013-01-01

    AIM: To evaluate the value of administration of hyoscine-N-butyl-bromide (HBB) for image quality magnetic resonance imaging (MRI) of the prostate. METHODS: Seventy patients were retrospectively included in the study. Thirty-five patients were examined with administration of 40 milligrams of HBB (Buscopan®; Boehringer, Ingelheim, Germany); 35 patients were examined without HBB. A multiparametric MRI protocol was performed on a 3.0 Tesla scanner without using an endorectal coil. The following criteria were evaluated independently by two experienced radiologists on a five-point Likert scale: anatomical details (delineation between peripheral and transitional zone of the prostate, visualisation of the capsule, depiction of the neurovascular bundles); visualisation of lymph nodes; motion related artefacts; and overall image quality. RESULTS: Comparison of anatomical details between the two cohorts showed no statistically significant difference (3.9 ± 0.7 vs 4.0 ± 0.9, P = 0.54, and 3.8 ± 0.7 vs 4.2 ± 0.6, P = 0.07) for both readers. There was no significant advantage regarding depiction of local and iliac lymph nodes (3.9 ± 0.6 vs 4.2 ± 0.6, P = 0.07, and 3.8 ± 0.9 vs 4.1 ± 0.8, P = 0.19). Motion artefacts were rated as “none” to “few” in both groups and showed no statistical difference (2.3 ± 1.0 vs 1.9 ± 0.9, P = 0.19, and 2.3 ± 1.1 vs 1.9 ± 0.7, P = 0.22). Overall image quality was rated “good” in average for both cohorts without significant difference (4.0 ± 0.6 vs 4.0 ± 0.9, P = 0.78, and 3.8 ± 0.8 vs 4.2 ± 0.6, P = 0.09). CONCLUSION: The results demonstrated no significant effect of HBB administration on image quality. The study suggests that use of HBB is not mandatory for MRI of the prostate at 3.0 Tesla. PMID:23908696

  2. TESLA detector magnet design

    NASA Astrophysics Data System (ADS)

    Kircher, François; Gastineau, Bernard; Klioukhine, Viatcheslav; Pabot, Yves

    2001-07-01

    The TESLA detector asks for a strong and very homogeneous magnetic field within its useful volume. In this respect, a large superconducting magnet has been designed, with special attention to get the requested field homogeneity. The design of the magnet, a superconducting solenoid with its iron yoke, is described in this paper, with some emphasis on the achievement of the field homogeneity.

  3. Photon collider at TESLA

    E-print Network

    Valery Telnov

    2001-03-06

    High energy photon colliders (gamma-gamma, gamma-electron) based on backward Compton scattering of laser light is a very natural addition to e+e- linear colliders. In this report we consider this option for the TESLA project. Recent study has shown that the horizontal emittance in the TESLA damping ring can be further decreased by a factor of four. In this case the gamma-gamma luminosity luminosity in the high energy part of spectrum can reach (1/3)L_{e+e-}. Typical cross sections of interesting processes in gamma-gamma collisions are higher than those in e+e- collisions by about one order of magnitude, so the number of events in gamma-gamma collisions will be more than that in e+e- collisions. Photon colliders can, certainly, give additional information and they are the best for the study of many phenomena. The main question is now the technical feasibility. The key new element in photon colliders is a very powerful laser system. An external optical cavity is a promising approach for the TESLA project. A free electron laser is another option. However, a more straightforward solution is ``an optical storage ring (optical trap)'' with diode pumped solid state laser injector which is today technically feasible. This paper briefly reviews the status of a photon collider based at TESLA, its possible parameters and existing problems.

  4. The TESLA Detector

    E-print Network

    Klaus Moenig

    2001-11-05

    For the superconducting linear collider TESLA a multi purpose detector has been designed. This detector is optimised for the important physics processes expected at a next generation linear collider up to around 1 TeV and is designed for the specific environment of a superconducting collider.

  5. High-Field fMRI for Human Applications: An Overview of Spatial Resolution and Signal Specificity

    PubMed Central

    Olman, Cheryl A; Yacoub, Essa

    2011-01-01

    In the last decade, dozens of 7 Tesla scanners have been purchased or installed around the world, while 3 Tesla systems have become a standard. This increased interest in higher field strengths is driven by a demonstrated advantage of high fields for available signal-to-noise ratio (SNR) in the magnetic resonance signal. Functional imaging studies have additional advantages of increases in both the contrast and the spatial specificity of the susceptibility based BOLD signal. One use of this resultant increase in the contrast to noise ratio (CNR) for functional MRI studies at high field is increased image resolution. However, there are many factors to consider in predicting exactly what kind of resolution gains might be made at high fields, and what the opportunity costs might be. The first part of this article discusses both hardware and image quality considerations for higher resolution functional imaging. The second part draws distinctions between image resolution, spatial specificity, and functional specificity of the fMRI signals that can be acquired at high fields, suggesting practical limitations for attainable resolutions of fMRI experiments at a given field, given the current state of the art in imaging techniques. Finally, practical resolution limitations and pulse sequence options for studies in human subjects are considered. PMID:22216080

  6. TESLA Linear-Collider Projekt Abbildung 134: Das hydrogeologische Profil entlang der TESLA-Trasse. Der TESLA-

    E-print Network

    TESLA Linear-Collider Projekt Abbildung 134: Das hydrogeologische Profil entlang der TESLA-Trasse. Der TESLA- Tunnel liegt in wasserdurchlässigen und -undurchlässigen Schichten. Die wasserdurch gesättigt. 230 #12;TESLA Linear-Collider Projekt Voruntersuchungen zum TESLA Linear-Collider Projekt Ein

  7. MRI gradient coil cylinder sound field simulation and measurement.

    PubMed

    Mechefske, Chris K; Wu, Yuhua; Rutt, Brian K

    2002-08-01

    High-field, high-speed Magnetic Resonance Imaging (MRI) generates high sound levels within and nearby the scanner. The mechanism and process that produces the gradient magnetic field (a cylindrical electro-magnet, called the gradient coil cylinder, which produces a spatially and temporally varying magnetic field inside a static background magnetic field) is the primary source of this noise. This noise can cause difficulties in verbal communication in and around the scanner, heightened patient anxiety, temporary hearing loss and possible permanent hearing impairment for health care workers and patients. In order to effectively suppress the sound radiation from the gradient coil cylinder the sound field within and nearby the gradient coil needs to be characterized This characterization may be made using an analytical solution of the sound pressure field, computational simulation, measurement analysis or some combination of these three methods. This paper presents the computational simulation and measurement results of a study of the sound radiation from a head and neck gradient coil cylinder within a 4 Tesla MRI whole body scanner. The measurement results for the sound pressure level distribution along the centerline of the gradient coil cylinder are presented. The sound pressure distributions predicted from Finite Element Analysis of the gradient coil movement during operation and subsequent Boundary Element Analysis of the sound field generated are also presented. A comparison of the measured results and the predicted results shows close agreement. Because of the extremely complex nature of the analytical solution for the gradient coil cylinder, a treatment of the analytical solution and comparison to the computational results for a simple cylinder vibrating in a purely radial direction are also presented and also show close agreement between the two methods thus validating the computational approach used with the more complex gradient coil cylinder. PMID:12188211

  8. SASE FEL at the TESLA Facility, Phase 2 The TESLA Test Facility FEL team

    E-print Network

    SASE FEL at the TESLA Facility, Phase 2 The TESLA Test Facility FEL team June 2002, TESLA-FEL 2002-01 #12;SASE FEL at the TESLA Facility, Phase 2 Abstract The last description of the TESLA Test Facility FEL has been written in 1995 (TESLA- FEL report 95-03). Since then, many changes have developed

  9. Theory and Performance of Tesla Turbines

    E-print Network

    Romanin, Vincent D.

    2012-01-01

    while experiments evaluated performance of the entire TeslaTESLA ROTOR flow between flat plates with roughened surfaces, experiments[Experiment and analysis for an improved design of the inlet and nozzle in Tesla

  10. TESLA-Report 1999-05 TESLA-Report 1999-05

    E-print Network

    TESLA-Report 1999-05 1 of 38 #12;TESLA-Report 1999-05 2 of 38 #12;TESLA-Report 1999-05 3 of 38 #12;TESLA-Report 1999-05 4 of 38 #12;TESLA-Report 1999-05 5 of 38 #12;TESLA-Report 1999-05 6 of 38 #12;TESLA-Report 1999-05 7 of 38 #12;TESLA-Report 1999-05 8 of 38 #12;TESLA-Report 1999-05 9 of 38 #12;TESLA-Report 1999

  11. 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

  12. TESLA-N: Polarized electron-nucleon scattering at TESLA

    Microsoft Academic Search

    Frank Ellinghaus; E. C. Aschenauer

    2001-01-01

    Measurements of polarized e-N scattering can be realized at the TESLA linear collider facility with projected luminosities that are about two orders of magnitude higher than those expected of other experiments at comparable energies. Longitudinally polarized electrons, accelerated as a small fraction of the total current in the e+ arm of TESLA, can be directed onto a solid state target

  13. MRI of Cartilage: Standard Techniques

    Microsoft Academic Search

    Thomas M. Link

    \\u000a Magnetic resonance imaging (MRI) is the only imaging technique that allows direct visualization of cartilage with sufficient\\u000a contrast. However, cartilage imaging is challenging and MRI needs to be tailored to best visualize cartilage morphology, which\\u000a includes using scanners with adequate field strength, coils which allow high spatial resolution imaging, and optimized imaging\\u000a sequences. Also MRI should not only allow to

  14. Effect of the static magnetic field of the MR-scanner on ERPs: Evaluation of visual, cognitive and motor potentials

    E-print Network

    Effect of the static magnetic field of the MR-scanner on ERPs: Evaluation of visual, cognitive December 2009 Available online 25 January 2010 Keywords: ERP EEG­fMRI 3 T static magnetic field of the static magnetic field of the MR-scanner on ERPs extracted from simultaneous EEG­fMRI recordings

  15. Individual preferences modulate incentive values: Evidence from functional MRI

    PubMed Central

    Koeneke, Susan; Pedroni, Andreas F; Dieckmann, Anja; Bosch, Volker; Jäncke, Lutz

    2008-01-01

    Background In most studies on human reward processing, reward intensity has been manipulated on an objective scale (e.g., varying monetary value). Everyday experience, however, teaches us that objectively equivalent rewards may differ substantially in their subjective incentive values. One factor influencing incentive value in humans is branding. The current study explores the hypothesis that individual brand preferences modulate activity in reward areas similarly to objectively measurable differences in reward intensity. Methods A wheel-of-fortune game comprising an anticipation phase and a subsequent outcome evaluation phase was implemented. Inside a 3 Tesla MRI scanner, 19 participants played for chocolate bars of three different brands that differed in subjective attractiveness. Results Parametrical analysis of the obtained fMRI data demonstrated that the level of activity in anatomically distinct neural networks was linearly associated with the subjective preference hierarchy of the brands played for. During the anticipation phases, preference-dependent neural activity has been registered in premotor areas, insular cortex, orbitofrontal cortex, and in the midbrain. During the outcome phases, neural activity in the caudate nucleus, precuneus, lingual gyrus, cerebellum, and in the pallidum was influenced by individual preference. Conclusion Our results suggest a graded effect of differently preferred brands onto the incentive value of objectively equivalent rewards. Regarding the anticipation phase, the results reflect an intensified state of wanting that facilitates action preparation when the participants play for their favorite brand. This mechanism may underlie approach behavior in real-life choice situations. PMID:19032746

  16. FEB 19, 2001 TESLA-2001-17

    E-print Network

    ­i­ FEB 19, 2001 TESLA-2001-17 CONCEPTUAL DESIGN FOR THE FINAL FOCUS QUADRUPOLE MAGNETS FOR TESLA A a preliminary design of the superconducting final focusing quadrupole magnets for TESLA and all their associated Electron volts Superconducting Linear Accelerator (TESLA) is an electron/positron linear collider

  17. TESLA'S VISION OF THE WIRELESS GLOBAL COMMUNICATIONS

    E-print Network

    Trajkovic, Ljiljana

    TESLA'S VISION OF THE WIRELESS GLOBAL COMMUNICATIONS Ljiljana Trajkovi Communication Networks;March 12, 2004 Kwantlen College Ljiljana Trajkovic, Simon Fraser University 2 Road map Tesla in 1890's Alternate currents Tesla left Edison in 1885. He formed his own laboratory "Tesla Electric Company" in 1887

  18. FEB 19, 2001 TESLA-2001-17

    E-print Network

    ­i­ FEB 19, 2001 TESLA-2001-17 CONCEPTUAL DESIGN FOR THE FINAL FOCUS QUADRUPOLE MAGNETS FOR TESLA A a preliminary design of the superconducting final focusing quadrupole magnets for TESLA and all their associated The Tera Electron volts Superconducting Linear Accelerator (TESLA) is an electron/positron linear collider

  19. TESLA-LNF TECHNICAL NOTE Divisione Acceleratori

    E-print Network

    TESLA-LNF TECHNICAL NOTE _____________ Divisione Acceleratori Frascati, November 20, 2003 Note: TESLA Report 2003-26 TESLA DAMPING RING: INJECTION/EXTRACTION SCHEMES WITH RF DEFLECTORS D. Alesini, S/extraction schemes in the Damping Ring of TESLA using RF deflectors. We illustrate different possible solutions using

  20. Tesla TechFair Call for Proposals

    E-print Network

    Tesla TechFair Call for Proposals Thayer School of Engineering and the Hopkins Center are celebrating Nikola Tesla, in conjunction with Tesla in New York, an opera by filmmaker Jim Jarmusch & composer Phil Kline. Thayer will host a Tesla TechFair, including a panel discussion and demonstrations

  1. Brain Activation in Response to Visually Evoked Sexual Arousal in Male-to-Female Transsexuals: 3.0 Tesla Functional Magnetic Resonance Imaging

    PubMed Central

    Oh, Seok-Kyun; Kim, Gwang-Won; Yang, Jong-Chul; Kim, Seok-Kwun; Kang, Heoung-Keun

    2012-01-01

    Objective This study used functional magnetic resonance imaging (fMRI) to contrast the differential brain activation patterns in response to visual stimulation with both male and female erotic nude pictures in male-to-female (MTF) transsexuals who underwent a sex reassignment surgery. Materials and Methods A total of nine healthy MTF transsexuals after a sex reassignment surgery underwent fMRI on a 3.0 Tesla MR Scanner. The brain activation patterns were induced by visual stimulation with both male and female erotic nude pictures. Results The sex hormone levels of the postoperative MTF transsexuals were in the normal range of healthy heterosexual females. The brain areas, which were activated by viewing male nude pictures when compared with viewing female nude pictures, included predominantly the cerebellum, hippocampus, putamen, anterior cingulate gyrus, head of caudate nucleus, amygdala, midbrain, thalamus, insula, and body of caudate nucleus. On the other hand, brain activation induced by viewing female nude pictures was predominantly observed in the hypothalamus and the septal area. Conclusion Our findings suggest that distinct brain activation patterns associated with visual sexual arousal in postoperative MTF transsexuals reflect their sexual orientation to males. PMID:22563262

  2. Whole body scanners

    Microsoft Academic Search

    Hein A. M. Daanen; G. Jeroen van de Water

    1998-01-01

    Whole body scanning is a useful technique with applications in the apparel industry, human systems engineering and medical field. A worldwide review of whole body scanners describes eight commercially available systems. The scanners differ considerably in price (US$50?000–410?000), resolution (1–8mm) and speed (0.2–3s). Most scanners use laser stripe projection; other techniques are patterned light projection and stereo photogrammetry. To cover

  3. Design and Use of Tailored Hard-Pulse Trains for Uniformed Saturation of Myocardium at 3 Tesla

    E-print Network

    Southern California, University of

    Design and Use of Tailored Hard-Pulse Trains for Uniformed Saturation of Myocardium at 3 Tesla of the proposed tailored pulse train is tested using simulations and in vivo experiments at 3 T. METHODS Experimental Methods Experiments were performed on a commercial whole-body 3.0-T scanner (Signa Excite HD; GE

  4. Gd-EOB-DTPA-enhanced 3.0-Tesla MRI findings for the preoperative detection of focal liver lesions: Comparison with iodine-enhanced multi-detector computed tomography

    NASA Astrophysics Data System (ADS)

    Park, Hyong-Hu; Goo, Eun-Hoe; Im, In-Chul; Lee, Jae-Seung; Kim, Moon-Jib; Kwak, Byung-Joon; Chung, Woon-Kwan; Dong, Kyung-Rae

    2012-12-01

    The safety of gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic-acid (Gd-EOB-DTPA) has been confirmed, but more study is needed to assess the diagnostic accuracy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) in patients with a hepatocellular carcinoma (HCC) for whom surgical treatment is considered or with a metastatic hepatoma. Research is also needed to examine the rate of detection of hepatic lesions compared to multi-detector computed tomography (MDCT), which is used most frequently to localize and characterize a HCC. Gd-EOB-DTPA-enhanced MRI and iodine-enhanced MDCT imaging were compared for the preoperative detection of focal liver lesions. The clinical usefulness of each method was examined. The current study enrolled 79 patients with focal liver lesions who preoperatively underwent MRI and MDCT. In these patients, there was less than one month between the two diagnostic modalities. Imaging data were taken before and after contrast enhancement in both methods. To evaluate the images, we analyzed the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) in the lesions and the liver parenchyma. To compare the sensitivity of the two methods, we performed a quantitative analysis of the percentage signal intensity of the liver (PSIL) on a high resolution picture archiving and communication system (PACS) monitor (paired-samples t-test, p < 0.05). The enhancement was evaluated based on a consensus of four observers. The enhancement pattern and the morphological features during the arterial and the delayed phases were correlated between the Gd-EOB-DTPA-enhanced MRI findings and the iodine-enhanced MDCT by using an adjusted x2 test. The SNRs, CNRs, and PSIL all had a greater detection rate in Gd-EOB-DTPA enhanced MRI than in iodine-enhanced MDCT. Hepatocyte-selective uptake was observed 20 minutes after the injection in the focal nodular hyperplasia (FNH, 9/9), adenoma (9/10), and highly-differentiated HCC (grade G1, 27/30). Rim enhancement was detected in all metastases (30/30). During the arterial and the delayed phases, good overall agreement between the gadoxetic-acid-enhanced MR and CT was observed (x2 test, p < 0.05). For the preoperative detection of focal liver lesions, Gd-EOB-DTPA-enhanced MRI had a higher diagnostic value and higher detection rate than iodine-enhanced MDCT. The arterial and the delayed dynamic enhancement patterns, and the gadoxetic-acid-enhanced MR imaging can provide information on the possible degree of cellular differentiation of a HCC, adenoma or metastatic tumor.

  5. Navigation of a telepresence robot via covert visuospatial attention and real-time fMRI.

    PubMed

    Andersson, Patrik; Pluim, Josien P W; Viergever, Max A; Ramsey, Nick F

    2013-01-01

    Brain-computer interfaces (BCIs) allow people with severe neurological impairment and without ability to control their muscles to regain some control over their environment. The BCI user performs a mental task to regulate brain activity, which is measured and translated into commands controlling some external device. We here show that healthy participants are capable of navigating a robot by covertly shifting their visuospatial attention. Covert Visuospatial Attention (COVISA) constitutes a very intuitive brain function for spatial navigation and does not depend on presented stimuli or on eye movements. Our robot is equipped with motors and a camera that sends visual feedback to the user who can navigate it from a remote location. We used an ultrahigh field MRI scanner (7 Tesla) to obtain fMRI signals that were decoded in real time using a support vector machine. Four healthy subjects with virtually no training succeeded in navigating the robot to at least three of four target locations. Our results thus show that with COVISA BCI, realtime robot navigation can be achieved. Since the magnitude of the fMRI signal has been shown to correlate well with the magnitude of spectral power changes in the gamma frequency band in signals measured by intracranial electrodes, the COVISA concept may in future translate to intracranial application in severely paralyzed people. PMID:22965825

  6. Geographic Distribution of CT, MRI and PET Devices in Japan: A Longitudinal Analysis Based on National Census Data

    PubMed Central

    Matsumoto, Masatoshi; Koike, Soichi; Kashima, Saori; Awai, Kazuo

    2015-01-01

    Background Japan has the most CT and MRI scanners per unit population in the world; however, the geographic distribution of these technologies is currently unknown. Moreover, nothing is known of the cause-effect relationship between the number of diagnostic imaging devices and their geographic distribution. Methods Data on the number of CT, MRI and PET devices and that of their utilizations in all 1829 municipalities of Japan was generated, based on the Static Survey of Medical Institutions conducted by the government. The inter-municipality equity of the number of devices or utilizations was evaluated with Gini coefficient. Results Between 2005 and 2011, the number of CT, MRI and PET devices in Japan increased by 47% (8789 to 12945), 19% (5034 to 5990) and 70% (274 to 466), respectively. Gini coefficient of the number of devices was largest for PET and smallest for CT (p for PET-MRI difference <0.001; MRI-CT difference <0.001). For all three modalities, Gini coefficient steadily decreased (p for 2011-2005 difference: <0.001 for CT; 0.003 for MRI; and <0.001 for PET). The number of devices in old models (single-detector CT, MRI<1.5 tesla, and conventional PET) decreased, while that in new models (multi-detector CT, MRI?1.5 tesla, and PET-CT) increased. Gini coefficient of the old models increased or remained unchanged (increase rate of 9%, 3%, and -1%; p for 2011-2008 difference <0.001, 0.072, and 0.562, respectively), while Gini coefficient of the new models decreased (-10%, -9%, and -10%; p for 2011-2008 difference <0.001, <0.001, and <0.001 respectively). Similar results were observed in terms of utilizations. Conclusions The more abundant a modality, the more equal the modality’s distribution. Any increase in the modality made its distribution more equal. The geographic distribution of the diagnostic imaging technology in Japan appears to be affected by spatial competition derived from a market force. PMID:25946125

  7. Initial experience of 3 tesla endorectal coil magnetic resonance imaging and 1H-spectroscopic imaging of the prostate

    Microsoft Academic Search

    J. J. Fütterer; Tom W. J. Scheenen; Henkjan J. Huisman; Dennis W. J. Klomp; Ferdi A. van Dorsten; J Alfred Witjes; Arend Heerschap; Jelle O. Barentsz

    2004-01-01

    RATIONALE AND OBJECTIVES: We sought to explore the feasibility of magnetic resonance imaging (MRI) of the prostate at 3T, with the knowledge of potential drawbacks of MRI at high field strengths. MATERIAL AND METHOD: MRI, dynamic MRI, and 1H-MR spectroscopic imaging were performed in 10 patients with prostate cancer on 1.5T and 3T whole-body scanners. Comparable scan protocols were used,

  8. PERFORMANCE OF THE TESLA TEST FACILITY LINAC for the TESLA Collaboration

    E-print Network

    PERFORMANCE OF THE TESLA TEST FACILITY LINAC P. Castro for the TESLA Collaboration Abstract In order to test the performance of a superconducting linac, the TESLA Collaboration has built and operated for the TESLA design. Results of recent running periods will be summarized in this paper. 1 INTRODUCTION

  9. 26 July 2000 TESLA Report 2000-13 Compensation of Solenoid Effects at the TESLA

    E-print Network

    26 July 2000 TESLA Report 2000-13 Compensation of Solenoid Effects at the TESLA Interaction Point at the TESLA interaction point is 5 nm. The long solenoid encompassing the detector introduces coupling effects along the beam line. This is a concern for a linear collider such as TESLA, where the vertical beam size

  10. TESLA 2004-14 Test Measurements of a new TESLA Cavity

    E-print Network

    TESLA 2004-14 Test Measurements of a new TESLA Cavity Beam Position Monitor at the ELBE Linac V Abstract A new type of a cavity BPM proposed for beam position determination along the TESLA linac to TESLA would fulfil the demands for precise bunch-to-bunch position determination. Possible improvements

  11. TESLA Report 2003-28 TESLA cavity modeling and digital implementation

    E-print Network

    TESLA Report 2003-28 TESLA cavity modeling and digital implementation with FPGA technology solution, Warsaw University of Technology Stefan Simrock TESLA, DESY, Hamburg ABSTRACT The cavity resonator modeling for the TESLA - TeV­Energy Superconducting Linear Accelerator project is initially introduced

  12. Status of the TESLA Test Facility Linac H. Weise, for the TESLA Collaboration

    E-print Network

    Status of the TESLA Test Facility Linac H. Weise, for the TESLA Collaboration Deutsches Elektronen-Synchrotron DESY D-22603 Hamburg, Germany Abstract The TTF linac, a major effort of the TESLA Test Facility, is now GeV collider is the usage of superconducting (s.c.) accelerating structures. The international TESLA

  13. UC Santa Cruz Tesla at Aptos HighUC Santa Cruz Tesla at Aptos HighSCIPP UC Santa Cruz

    E-print Network

    California at Santa Cruz, University of

    UC Santa Cruz Tesla at Aptos HighUC Santa Cruz Tesla at Aptos HighSCIPP UC Santa Cruz UC Santa Cruz Tesla Coil ShowUC Santa Cruz Tesla Coil Show at Aptos High Schoolat Aptos High School #12;UC Santa Cruz Tesla at Aptos HighUC Santa Cruz Tesla at Aptos HighSCIPP UC Santa Cruz Santa Cruz Institute

  14. Technical Note Functional MRI of the Thoracic Spinal Cord During

    E-print Network

    Smith, Stephen D.

    Technical Note Functional MRI of the Thoracic Spinal Cord During Vibration Sensation Jennifer functional magnetic resonance images from thoracic spinal cord neurons. Materials and Methods: The lower spinal cord using a HASTE sequence on a 3 Tesla MRI system. Results: Signal increases were observed

  15. Liquid-explosives scanners stand trial in airports

    SciTech Connect

    Matthews, Jermey N. A.

    2010-07-15

    Air passengers may once more be allowed to pack beverages, lotions, and hair spray in their carry-on luggage, if imaging technologies to detect liquid explosives can prove their worth. Several competing systems, including multi-energy x-ray systems and a low-field magnetic resonance imaging (MRI) scanner, are undergoing field tests at some airports worldwide.

  16. LCDETxxxxxxx Improved TESLA Optics and Beam Induced

    E-print Network

    LC­DET­xxxx­xxx Improved TESLA Optics and Beam Induced Backgrounds Update Karsten BË?uÃ?er, DESY and Olivier Napoly, CEA/Saclay LCWS 2002, Jeju, Korea Abstract A new tesla optics with l*=5m is under development. An update is given on the simulation of the beam induced backgrounds in the TESLA detector. 1

  17. TESLA'S VISION OF THE WIRELESS GLOBAL COMMUNICATIONS

    E-print Network

    Trajkovic, Ljiljana

    TESLA'S VISION OF THE WIRELESS GLOBAL COMMUNICATIONS Ljiljana Trajkovi Communication Networks;January 17, 2005 UBC Ljiljana Trajkovic, Simon Fraser University 2 Road map Tesla in 1890's First wireless;January 17, 2005 UBC Ljiljana Trajkovic, Simon Fraser University 4 Alternate currents Tesla left Edison

  18. MRI-based preplanning using CT and MRI data fusion in patients with cervical cancer treated with 3D-based brachytherapy: feasibility and accuracy study

    Microsoft Academic Search

    Martin Dolezel; Karel Odrazka; Jan Zizka; Jaroslav Vanasek; Tereza Kohlova; Tomas Kroulik; Dusan Spitzer; Pavel Ryska; Michal Tichy; Milan Kostal; Lubica Jalcova

    PurposeMRI assisted radiation treatment planning enables enhanced target contouring. The purpose of this study is to analyze the feasibility and accuracy of CT and MRI data fusion for MRI-based treatment planning in an institution where an MRI scanner is not available in the radiotherapy department.

  19. TESLA-N electron scattering with polarized targets at TESLA

    Microsoft Academic Search

    2001-01-01

    Measurements of polarized eN scattering can be realized at the TESLA linear collider facility at DESY with luminosities that are about two orders of magnitude higher than those expected for other experiments at comparable energies. A large variety of polarized parton distribution and fragmentation functions can be determined with unprecedented accuracy, many of them for the first time. .

  20. Forensics for flatbed scanners

    NASA Astrophysics Data System (ADS)

    Gloe, Thomas; Franz, Elke; Winkler, Antje

    2007-02-01

    Within this article, we investigate possibilities for identifying the origin of images acquired with flatbed scanners. A current method for the identification of digital cameras takes advantage of image sensor noise, strictly speaking, the spatial noise. Since flatbed scanners and digital cameras use similar technologies, the utilization of image sensor noise for identifying the origin of scanned images seems to be possible. As characterization of flatbed scanner noise, we considered array reference patterns and sensor line reference patterns. However, there are particularities of flatbed scanners which we expect to influence the identification. This was confirmed by extensive tests: Identification was possible to a certain degree, but less reliable than digital camera identification. In additional tests, we simulated the influence of flatfielding and down scaling as examples for such particularities of flatbed scanners on digital camera identification. One can conclude from the results achieved so far that identifying flatbed scanners is possible. However, since the analyzed methods are not able to determine the image origin in all cases, further investigations are necessary.

  1. Tracking of primary human hepatocytes with clinical MRI: initial results with Tat-peptide modified superparamagnetic iron oxide particles.

    PubMed

    Morgul, M H; Raschzok, N; Schwartlander, R; Vondran, F W; Michel, R; Stelter, L; Pinkernelle, J; Jordan, A; Teichgraber, U; Sauer, I M

    2008-03-01

    The transplantation of primary human hepatocytes is a promising approach in the treatment of specific liver diseases. However, little is known about the fate of the cells following application. Magnetic resonance imaging (MRI) could enable real-time tracking and long-term detection of transplanted hepatocytes. The use of superparamagnetic iron oxide particles as cellular contrast agents should allow for the non-invasive detection of labelled cells on high-resolution magnetic resonance images. Experiments were performed on primary human hepatocytes to transfer the method of detecting labelled cells via clinical MRI into human hepatocyte transplantation. For labelling, Tat-peptide modified nano-sized superparamagnetic MagForce particles were used. Cells were investigated via a clinical MR scanner at 3.0 Tesla and the particle uptake within single hepatocytes was estimated using microscopic examinations. The labelled primary human hepatocytes were clearly detectable by MRI, proving the feasibility of this new concept. Therefore, this method is a useful tool to investigate the effects of human hepatocyte transplantation and to improve safety aspects of this method. PMID:18373319

  2. Blood Flow MRI of the Human Retina/Choroid during Rest and Isometric Exercise

    PubMed Central

    Zhang, Yi; Nateras, Oscar San Emeterio; Peng, Qi; Rosende, Carlos A.; Duong, Timothy Q.

    2012-01-01

    Purpose. To investigate blood flow (BF) in the human retina/choroid during rest and handgrip isometric exercise using magnetic resonance imaging (MRI). Methods. Four healthy volunteers (25–36 years old) in multiple sessions (1–3) on different days. MRI studies were performed on a 3-Tesla scanner using a custom-made surface coil (7 × 5cm in diameter) at the spatial resolution of 0.5 × 0.8 × 6.0 mm. BF was measured using the pseudo-continuous arterial-spin-labeling technique with background suppression and turbo-spin-echo acquisition. During MRI, subjects rested for 1 minute followed by 1 minute of handgrip, repeating three times, while maintaining stable eye fixation on a target with cued eye blinks at the end of each data acquisition (every 4.6 seconds). Results. Robust BF of the unanesthetized human retina/choroid was detected. Basal BF in the posterior retina/choroid was 149 ± 48 mL/100 mL/min with a mean heart rate of 60 ± 5 beats per minute, mean arterial pressure of 78 ± 5 mm Hg, ocular perfusion pressure of 67 ± 4 mm Hg at rest (mean ± SD, n = 4 subjects). Handgrip significantly increased retina/choroid BF by 25% ± 7%, heart rate by 19% ± 8%, mean arterial pressure by 22% ± 5% (measured at the middle of the handgrip task), and ocular perfusion pressure by 25% ± 6% (averaged across the entire handgrip task) (P < 0.01), but did not change intraocular pressure, arterial oxygen saturation, end-tidal CO2, and respiration rate (P > 0.05). Conclusions. This study demonstrates a novel MRI application to image quantitative BF of the human retina/choroid during rest and isometric exercise. Retina/choroid BF increases during brief handgrip exercise, paralleling increases in mean arterial pressure. Handgrip exercise changes ocular perfusion pressure free of potential drug side effect and can be done in the MRI scanner. MRI offers quantitative BF with large field of view without depth limitation, potentially providing insights into retinal pathophysiology. PMID:22661466

  3. The TESLA Time Projection Chamber

    E-print Network

    Nabil Ghodbane

    2002-12-12

    A large Time Projection Chamber is proposed as part of the tracking system for a detector at the TESLA electron positron linear collider. Different ongoing R&D studies are reviewed, stressing progress made on a new type readout technique based on Micro-Pattern Gas Detectors.

  4. Dynamics of fMRI signals during human brain activations to a stimulus

    NASA Astrophysics Data System (ADS)

    Liu, Haiying; Kato, Toshinori; Neves, Carlos

    2001-05-01

    In fMRI memory study, the temporal behavior of BOLD fMRI signals were consistently observed from various brain processing areas at 1.5 Tesla and consistent with the expected functions. Also, all the activations generally exhibit three types of temporal characteristics: short, sustained and delayed responses in relation to the primary stimuli. To address these cerebral multiphasic responses, a suitable functional data analysis scheme has been used, in which the neural response of a specific brain area to a pre-determined stimulation input of some sort was assumed to be linear. The visual memory study was performed on 6 normal subjects on a clinical MR scanner using a 5 min long rapid dynamical whole brain imaging using EPI acquisition during a single memory task, which involved a 45 sec visual presentation of three simple abstract geometric figures to the subject via LCD projector. The results showed that the activations in visual cortex were tightly correlated with the visual stimulus, while the activations detected in interior temporal, entorhinal cortex and inferior temporal area were delayed. Using the new technique, the brian activations were further characterized quantitatively in terms of delay and prolonged response. The resulting effective impulse response functions corresponding to these brain activations revealed much clearly all the temporal components.

  5. MRI Evaluation of Spinal Length and Vertebral Body Angle During Loading with a Spinal Compression Harness

    NASA Technical Reports Server (NTRS)

    Campbell, James A.; Hargens, Alan R.; Murthy, G.; Ballard, R. E.; Watenpaugh, D. E.; Hargens, Alan, R.; Sanchez, E.; Yang, C.; Mitsui, I.; Schwandt, D.; Fechner, K. P.; Holton, Emily M. (Technical Monitor)

    1998-01-01

    Weight bearing by the spinal column during upright posture often plays a role in the common problem of low back pain. Therefore, we developed a non-ferromagnetic spinal compression harness to enable MRI investigations of the spinal column during axial loading. Human subjects were fitted with a Nest and a footplate which were connected by adjustable straps to an analog load cell. MRI scans of human subjects (5 males and 1 female with age range of 27-53 yrs) during loaded and unloaded conditions were accomplished with a 1.5 Tesla GE Signa scanner. Studies of two subjects undergoing sequentially increasing spinal loads revealed significant decreases (r(sup 2) = 0.852) in spinal length between T4 and L5 culminating in a 1.5 to 2% length decrease during loading with 75% body weight. Sagittal vertebral body angles of four subjects placed under a constant 50% body weight load for one hour demonstrated increased lordotic and kyphotic curvatures. In the lumbar spine, the L2 vertebral body experienced the greatest angular change (-3 deg. to -5 deg.) in most subjects while in the thoracic spine, T4 angles increased from the unloaded state by +2 deg. to +9 deg. Overall, our studies demonstrate: 1) a progressive, although surprisingly small, decrease in spinal length with increasing load and 2) relatively large changes in spinal column angulation with 50% body weight.

  6. Diffusion tensor imaging of the normal prostate at 3 Tesla.

    PubMed

    Gürses, Bengi; Kabakci, Neslihan; Kovanlikaya, Arzu; Firat, Zeynep; Bayram, Ali; Ulu?, Aziz Müfit; Uluo, Aziz Müfit; Kovanlikaya, Ilhami

    2008-04-01

    The aim of this study was to assess the feasibility of diffusion tensor imaging (DTI) of the prostate and to determine normative fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of healthy prostate with a 3-Tesla magnetic resonance imaging (MRI) system. Thirty volunteers with a mean age of 28 (25-35) years were scanned with a 3-Tesla MRI (Intera Achieva; Philips, The Netherlands) system using a six-channel phased array coil. Initially, T2-weighted turbo spin-echo (TSE) axial images of the prostate were obtained. In two subjects, a millimetric hypointense signal change was detected in the peripheral zones on T2-weighted TSE images. These two subjects were excluded from the study. DTI with single-shot echo-planar imaging (ssEPI) was performed in the remaining 28 subjects. ADC and FA values were measured using the manufacturer supplied software by positioning 9-pixel ROIs on each zone. Differences between parameters of the central and peripheral zones were assessed. Mean ADC value of the central (1.220 +/- 0.271 x 10(-3) mm(2)/s) was found to be significantly lower when compared with the peripheral gland (1.610 +/- 0.347 x 10(-3) mm(2)/s) (P < 0.01). Mean FA of the central gland was significantly higher (0.26), compared with the peripheral gland (0.16) (P < 0.01). This study shows the feasibility of prostate DTI with a 3-Tesla MR system and the normative FA and ADC values of peripheral and central zones of the normal prostate. The results are compatible with the microstructural organization of the gland. PMID:17960389

  7. Biochip scanner device

    DOEpatents

    Perov, Alexander (Troitsk, RU); Belgovskiy, Alexander I. (Mayfield Heights, OH); Mirzabekov, Andrei D. (Darien, IL)

    2001-01-01

    A biochip scanner device used to detect and acquire fluorescence signal data from biological microchips or biochips and method of use are provided. The biochip scanner device includes a laser for emitting a laser beam. A modulator, such as an optical chopper modulates the laser beam. A scanning head receives the modulated laser beam and a scanning mechanics coupled to the scanning head moves the scanning head relative to the biochip. An optical fiber delivers the modulated laser beam to the scanning head. The scanning head collects the fluorescence light from the biochip, launches it into the same optical fiber, which delivers the fluorescence into a photodetector, such as a photodiode. The biochip scanner device is used in a row scanning method to scan selected rows of the biochip with the laser beam size matching the size of the immobilization site.

  8. TESLA Report 2003-08 Cavity control system

    E-print Network

    TESLA Report 2003-08 Cavity control system essential modeling for TESLA linear accelerator Tomasz of Technology, Poland Stefan Simrock DESY, TESLA, Hamburg, Germany ABSTRACT The pioneering TESLA linear are proposed. Keywords: TESLA, free electron laser, accelerator, high power microwave cavity, vector and phasor

  9. MRI driven magnetic microswimmers

    PubMed Central

    Jakab, Péter; Székely, Gábor; Hata, Nobuhiko

    2013-01-01

    Capsule endoscopy is a promising technique for diagnosing diseases in the digestive system. Here we design and characterize a miniature swimming mechanism that uses the magnetic fields of the MRI for both propulsion and wireless powering of the capsule. Our method uses both the static and the radio frequency (RF) magnetic fields inherently available in MRI to generate a propulsive force. Our study focuses on the evaluation of the propulsive force for different swimming tails and experimental estimation of the parameters that influence its magnitude. We have found that an approximately 20 mm long, 5 mm wide swimming tail is capable of producing 0.21 mN propulsive force in water when driven by a 20 Hz signal providing 0.85 mW power and the tail located within the homogeneous field of a 3 T MRI scanner. We also analyze the parallel operation of the swimming mechanism and the scanner imaging. We characterize the size of artifacts caused by the propulsion system. We show that while the magnetic micro swimmer is propelling the capsule endoscope, the operator can locate the capsule on the image of an interventional scene without being obscured by significant artifacts. Although this swimming method does not scale down favorably, the high magnetic field of the MRI allows self propulsion speed on the order of several millimeter per second and can propel an endoscopic capsule in the stomach. PMID:22037673

  10. Usefulness assessment of preoperative MRI fistulography in patients with perianal fistulas

    PubMed Central

    Waniczek, Dariusz; Adamczyk, Tomasz; Arendt, Jerzy; Kluczewska, Ewa; Kozi?ska-Marek, Ewa

    2011-01-01

    Summary Background: Accurate preoperative assessment of the perianal fistulous tract is the main purpose of the diagnostics and to a large extend determines surgery effectiveness. One of the useful diagnostic methods in perianal fistulas is magnetic resonance imaging. The authors presented experiences in the application of MRI fistulography for evaluation of cases of perianal fistulas difficult to diagnose and treat. Material/Methods: Own examination method was described; MRI fistulography findings were analyzed and compared with intraoperative conditions in 14 patients (11 men and 3 women) diagnosed in the years 2005– 2009. Eight patients had recurrent fistulas and 6 had primary fistulas. Imaging was performed with a GE SIGNA LX HS scanner with a 1.5-Tesla field strength and a dedicated surface coil placed at the level of hip joints. Contrast agent was a gadolinium-based solution. Results: Intraoperative findings were consistent with radiological descriptions of 13 MRI fistulographies. Only in one case, according to surgery findings, it was a transsphincteric fistula with an abscess in the ischioanal fossa, with an orifice in the posterior crypt; the radiologist described it as a transsphincteric, internal blind fistula. Conclusions: Due to its accuracy in the assessment of the perianal fistulous tracts in soft tissues, MRI fistulography becomes a useful and recommended diagnostic method in this pathology. It shows the location of the fistula regarding the system of anal sphincters, and identifies the internal orifice and branching of the fistula. It enables precise planning of surgical treatment. Authors suggest that this diagnostic method should be improved and applied more commonly. PMID:22802853

  11. Application of 3.0 Tesla Magnetic Resonance Imaging for Diagnosis in the Orthotopic Nude Mouse Model of Pancreatic Cancer

    PubMed Central

    Wu, Li; Wang, Chen; Yao, Xiuzhong; Liu, Kai; Xu, Yanjun; Zhang, Haitao; Fu, Caixia; Wang, Xiaolin; Li, Yingyi

    2014-01-01

    The aim of this study was to successfully establish an orthotopic murine model using two different human pancreatic adenocarcinoma cell lines and to propose a 3.0 tesla MRI protocol for noninvasive characterization of this model. SW1990 and MIAPaca-2 tumor cells were injected into the pancreas of BALB/C nu/nu mice. Tumor growth rate and morphological information were assessed by 3.0 tesla MRI (T1WI, T2WI and DCE-MRI) and immunohistology. Proliferation of SW1990 was significantly faster than that of MIAPaca-2 (P=0.000), but MIAPaca-2 mice had a significantly shorter survival than SW1990 mice (41 days and 44 days respectively, P=0.027). MRI could reliably monitor tumor growth in both cell lines: the tumors exhibiting a spherical growth pattern showed a high-intensity signal, and the SW1990 group developed significantly larger tumors compared with the MIAPaCa-2 group. There were no statistical differences between the two groups in which tumor size was assessed using electronic calipers and an MRI scan (P=0.680). Both tumors showed a slow gradual enhancement pattern. Immunohistochemistry demonstrated tumor tissues showing high expression of Ki-67. This model closely mimics human pancreatic cancer and permits monitoring of tumor growth and morphological information by noninvasive 3.0 tesla MRI studies reducing the number of mice required. PMID:25048266

  12. THE TESLA CRYOGENIC DISTRIBUTION SYSTEM

    Microsoft Academic Search

    S. Wolff; H. Lierl; B. Petersen

    2001-01-01

    The construction of the 33 km long 500 GeV centre- of-mass energy (upgradeable to 800 GeV) super- conducting linear collider TESLA at DESY with an integrated X-ray FEL facility of 0.1 nm wavelength has been proposed by an international collaboration. The collider will consist of more than 21000 superconducting 9-cell 1.3 GHz RF cavities assembled in about 1800 cryomodules containing

  13. High throughput optical scanner

    Microsoft Academic Search

    David A. Basiji; Gerrit J. van den Engh

    2001-01-01

    A scanning apparatus is provided to obtain automated, rapid and sensitive scanning of substrate fluorescence, optical density or phosphorescence. The scanner uses a constant path length optical train, which enables the combination of a moving beam for high speed scanning with phase-sensitive detection for noise reduction, comprising a light source, a scanning mirror to receive light from the light source

  14. Hybrid Dispersion Laser Scanner

    PubMed Central

    Goda, K.; Mahjoubfar, A.; Wang, C.; Fard, A.; Adam, J.; Gossett, D. R.; Ayazi, A.; Sollier, E.; Malik, O.; Chen, E.; Liu, Y.; Brown, R.; Sarkhosh, N.; Di Carlo, D.; Jalali, B.

    2012-01-01

    Laser scanning technology is one of the most integral parts of today's scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ?1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100?MHz at 800?nm. To show our scanner's broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100?kHz with 27,000 resolvable points. PMID:22685627

  15. LCPHSM200060TESLA 29th December 2000

    E-print Network

    LC­PHSM­2000­60­TESLA 29th December 2000 Measurement of the Differential Luminosity using Bhabha events in the Forward­Tracking region at TESLA K. M¨onig DESY­Zeuthen Abstract For most analyses at an e at TESLA is studied. #12; 1 Introduction One of the few unpleasant features of an e + e \\Gamma ­linear

  16. TESLA Technical Design Report Executive Summary

    E-print Network

    TESLA Technical Design Report PART I Executive Summary March 2001 Editors: F.Richard, J.R.Schneider, D.Trines, A.Wagner #12;#12;Dedicated to the memory of Bjørn H. Wiik (1937-1999) #12;#12;TESLA ­ A Summary This report describes the scientific aims and potential as well as the technical de- sign of TESLA

  17. Weight-bearing MRI of patellofemoral joint cartilage contact area

    Microsoft Academic Search

    Garry E. Gold; Thor F. Besier; Christine E. Draper; Deanna S. Asakawa; Scott L. Delp; Gary S. Beaupre

    2004-01-01

    Purpose: To measure contact area of cartilage in the patel- lofemoral joint during weight bearing using an open MRI scanner. Materials and Methods: We developed an MR-compatible back support that allows three-dimensional imaging of the patellofemoral cartilage under physiologic weight-bearing conditions with negligible motion artifact in an open MRI scanner. To measure contact areas, we trained observers us- ing a

  18. High-Resolution, In Vivo Magnetic Resonance Imaging of Drosophila at 18.8 Tesla

    PubMed Central

    Null, Brian; Liu, Corey W.; Hedehus, Maj; Conolly, Steven; Davis, Ronald W.

    2008-01-01

    High resolution MRI of live Drosophila was performed at 18.8 Tesla, with a field of view less than 5 mm, and administration of manganese or gadolinium-based contrast agents. This study demonstrates the feasibility of MR methods for imaging the fruit fly Drosophila with an NMR spectrometer, at a resolution relevant for undertaking future studies of the Drosophila brain and other organs. The fruit fly has long been a principal model organism for elucidating biology and disease, but without capabilities like those of MRI. This feasibility marks progress toward the development of new in vivo research approaches in Drosophila without the requirement for light transparency or destructive assays. PMID:18665264

  19. Static field influences on transcranial magnetic stimulation: Considerations for TMS in the scanner environment

    PubMed Central

    Yau, Jeffrey M.; Jalinous, Reza; Cantarero, Gabriela L.; Desmond, John E.

    2014-01-01

    Background: Transcranial magnetic stimulation (TMS) can be combined with functional magnetic resonance imaging (fMRI) to simultaneously manipulate and monitor human cortical responses. Although tremendous efforts have been directed at characterizing the impact of TMS on image acquisition, the influence of the scanner’s static field on the TMS coil has received limited attention. Objective/Hypothesis: The aim of this study was to characterize the influence of the scanner’s static field on TMS. We hypothesized that spatial variations in the static field could account for TMS field variations in the scanner environment. Methods: Using a MRI-compatible TMS coil, we estimated TMS field strengths based on TMS-induced voltage changes measured in a search coil. We compared peak field strengths obtained with the TMS coil positioned at different locations (B0 field vs fringe field) and orientations in the static field. We also measured the scanner’s static field to derive a field map to account for TMS field variations. Results: TMS field strength scaled depending on coil location and orientation with respect to the static field. Larger TMS field variations were observed in fringe field regions near the gantry as compared to regions inside the bore or further removed from the bore. The scanner’s static field also exhibited the greatest spatial variations in fringe field regions near the gantry. Conclusions: The scanner’s static field influences TMS fields and spatial variations in the static field correlate with TMS field variations. TMS field variations can be minimized by delivering TMS in the bore or outside of the 0 - 70 cm region from the bore entrance. PMID:24656916

  20. Multishot versus Single-Shot Pulse Sequences in Very High Field fMRI: A Comparison Using Retinotopic Mapping

    Microsoft Academic Search

    Jascha D. Swisher; John A. Sexton; J. Christopher Gatenby; John C. Gore; Frank Tong

    2012-01-01

    High-resolution functional MRI is a leading application for very high field (7 Tesla) human MR imaging. Though higher field strengths promise improvements in signal-to-noise ratios (SNR) and BOLD contrast relative to fMRI at 3 Tesla, these benefits may be partially offset by accompanying increases in geometric distortion and other off-resonance effects. Such effects may be especially pronounced with the single-shot

  1. Omnipresence of Tesla's Work and Ideas

    Microsoft Academic Search

    Milos D. Ercegovac

    HIS paper discusses several examples of the continuing presence of Tesla's work in science, engineering, and other areas. We analyze papers and patents over an extensive period of time that cite directly Tesla's work and comment on his ideas. It is evident that the impact of some of his creations is still present in several research and industrial areas, attesting

  2. Scanner focus metrology for advanced node scanner monitoring and control

    NASA Astrophysics Data System (ADS)

    Kim, Jimyung; Park, Youngsik; Jeong, Taehwa; Kim, Suhyun; Yoon, Kwang-Sub; Choi, Byoung-il; Levinski, Vladimir; Kandel, Daniel; Feler, Yoel; Gutman, Nadav; Island-Ashwal, Eltsafon; Cooper, Moshe; Choi, DongSub; Herzel, Eitan; David, Tien; Kim, JungWook

    2015-03-01

    Scanner Focus window of the lithographic process becomes much smaller due to the shrink of the device node and multipatterning approach. Consequently, the required performance of scanner focus becomes tighter and more complicated. Focus control/monitoring methods such as "field-by-field focus control" or "intra-field focus control" is a necessity. Moreover, tight scanner focus performance requirement starts to raise another fundamental question: accuracy of the reported scanner focus. The insufficient accuracy of the reported scanner focus using the existing methods originates from: a) Focus measurement quality, which is due to low sensitivity of measured targets, especially around the nominal production focus. b) The scanner focus is estimated using special targets, e.g. large pitch target and not using the device-like structures (irremovable aberration impact). Both of these factors are eliminated using KLA-Tencor proprietary "Focus Offset" technology.

  3. 3-Tesla MRI Response to TACE in HCC (Liver Cancer)

    ClinicalTrials.gov

    2014-03-20

    Adult Primary Hepatocellular Carcinoma; Advanced Adult Primary Liver Cancer; Localized Resectable Adult Primary Liver Cancer; Localized Unresectable Adult Primary Liver Cancer; Stage A Adult Primary Liver Cancer (BCLC); Stage B Adult Primary Liver Cancer (BCLC)

  4. Sentence Reading: A Functional MRI Study at 4 Tesla

    Microsoft Academic Search

    D. Bavelier; D. Corina; P. Jezzard; S. Padmanabhan; V. P. Clark; A. Karni; A. Prinster; A. Braun; A. Lalwani; J. P. Rauschecker; R. Turner; H. Neville

    1997-01-01

    In this study, changes in blood oxygenation and volume were monitored while monolingual right-handed subjects read English sentences. Our results confirm the role of the left peri-sylvian cortex in language processing. Interestingly, individual subject analyses reveal a pattern of activation characterized by several small, limited patches rather than a few large, anatomically well-circumscribed centers. Between-subject analyses confirm a lateralized pattern

  5. Multi-Level TESLA: Broadcast Authentication for Distributed Sensor Networks

    E-print Network

    Ning, Peng

    Multi-Level µTESLA: Broadcast Authentication for Distributed Sensor Networks DONGGANG LIU and PENG named multi-level µTESLA based on µTESLA, a broadcast authentication protocol whose scalability is limited by its unicast-based initial parameter distribution. Multi-level µTESLA satisfies several nice

  6. A functional MRI study of working memory in adolescents and young adults at genetic risk for bipolar disorder: preliminary findings

    PubMed Central

    Thermenos, Heidi W; Makris, Nikos; Whitfield-Gabrieli, Susan; Brown, Ariel B; Giuliano, Anthony J; Lee, Erica H; Faraone, Stephen V; Tsuang, Ming T; Seidman, Larry J

    2013-01-01

    Objectives In this report, we seek to (i) identify a potential neuroimaging endophenotype for bipolar disorder (BD) in emotion regulatory and autonomic circuitry in young first-degree relatives of persons with BD; and (ii) replicate our previous work identifying the functional neuroanatomy of working memory (WM) in an older sample of relatives of persons with BD. Methods Ten adolescent and young adult (age 13–24) unmedicated, non-ill, first-degree relatives of persons with BD (RELS) and 10 demographically comparable healthy controls performed a 2-back WM task and a 0-back control task during functional magnetic resonance imaging (fMRI). fMRI data were collected on a 1.5 Tesla scanner and analyzed using SPM-2. Mood was assessed on the day of scanning. Results The groups did not differ on any demographic, neuropsychological, or in-scanner task performance variables. In contrast to controls, RELS showed (i) weak task-dependent modulation activity in the cerebellar vermis (CV), insula, and amygdala/parahippocampal region, and (ii) exaggerated modulation of activity in the frontopolar cortex and brainstem, even after controlling for potential confounders. Many of the group differences were driven by differences in activity in the low-level (0-back) baseline task. Conclusions Young, unmedicated RELS exhibited altered task-dependent modulation of frontopolar, CV, and insula activity during WM, especially during the low-level (0-back) baseline task. Results are largely consistent with our initial study of older adult RELS, suggesting these alterations may represent biomarkers of genetic risk for BD. PMID:21676130

  7. [Recent advances in newborn MRI].

    PubMed

    Morel, B; Hornoy, P; Husson, B; Bloch, I; Adamsbaum, C

    2014-07-01

    The accurate morphological exploration of the brain is a major challenge in neonatology that advances in magnetic resonance imaging (MRI) can now provide. MRI is the gold standard if an hypoxic ischemic pathology is suspected in a full term neonate. In prematures, the specific role of MRI remains to be defined, secondary to US in any case. We present a state of the art of hardware and software technical developments in MRI. The increase in magnetic field strength (3 tesla) and the emergence of new MRI sequences provide access to new information. They both have positive and negative consequences on the daily clinical data acquisition use. The semiology of brain imaging in full term newborns and prematures is more extensive and complex and thereby more difficult to interpret. The segmentation of different brain structures in the newborn, even very premature, is now available. It is now possible to dissociate the cortex and basal ganglia from the cerebral white matter, to calculate the volume of anatomical structures, which improves the morphometric quantification and the understanding of the normal and abnormal brain development. MRI is a powerful tool to analyze the neonatal brain. The relevance of the diagnostic contribution requires an adaptation of the parameters of the sequences to acquire and of the image processing methods. PMID:24837857

  8. Integrated display scanner

    DOEpatents

    Veligdan, James T.

    2004-12-21

    A display scanner includes an optical panel having a plurality of stacked optical waveguides. The waveguides define an inlet face at one end and a screen at an opposite end, with each waveguide having a core laminated between cladding. A projector projects a scan beam of light into the panel inlet face for transmission from the screen as a scan line to scan a barcode. A light sensor at the inlet face detects a return beam reflected from the barcode into the screen. A decoder decodes the return beam detected by the sensor for reading the barcode. In an exemplary embodiment, the optical panel also displays a visual image thereon.

  9. An MRI-Compatible Robotic System With Hybrid Tracking for MRI-Guided Prostate Intervention

    PubMed Central

    Krieger, Axel; Iordachita, Iulian I.; Guion, Peter; Singh, Anurag K.; Kaushal, Aradhana; Ménard, Cynthia; Pinto, Peter A.; Camphausen, Kevin; Fichtinger, Gabor

    2012-01-01

    This paper reports the development, evaluation, and first clinical trials of the access to the prostate tissue (APT) II system—a scanner independent system for magnetic resonance imaging (MRI)-guided transrectal prostate interventions. The system utilizes novel manipulator mechanics employing a steerable needle channel and a novel six degree-of-freedom hybrid tracking method, comprising passive fiducial tracking for initial registration and subsequent incremental motion measurements. Targeting accuracy of the system in prostate phantom experiments and two clinical human-subject procedures is shown to compare favorably with existing systems using passive and active tracking methods. The portable design of the APT II system, using only standard MRI image sequences and minimal custom scanner interfacing, allows the system to be easily used on different MRI scanners. PMID:22009867

  10. Open MRI-Guided Neurosurgery

    Microsoft Academic Search

    V. Seifert; M. Zimmermann; C. Trantakis; H.-E. Vitzthum; K. Kühnel; A. Raabe; F. Bootz; J.-P. Schneider; F. Schmidt; J. Dietrich

    1999-01-01

    Summary  ?Objectives. A number of different image-guided surgical techniques have been developed during the past decade. None of these methods\\u000a can provide the surgeon with information about the dynamic changes that occur intra-operatively.\\u000a \\u000a ?Material and Method. The first vertical open 0.5 T MRI-scanner for intra-operative MRI-guided neurosurgery in Germany was installed at the University\\u000a of Leipzig during the summer 1996. Since

  11. First Thoughts on Commissioning of the TESLA Compiled by P. Castro for the TESLA commissioning study group.

    E-print Network

    First Thoughts on Commissioning of the TESLA Collider Compiled by P. Castro for the TESLA commissioning study group. September 6, 2002 Abstract The TESLA collider[1] is a large scale project be included in the plans of the construction and installation work of the TESLA collider. A working group

  12. SERI laser scanner system

    SciTech Connect

    Matson, R.J.; Cannon, T.W.

    1980-10-01

    A Laser Scanner System (LSS) produces a photoresponse map and can be used for the nondestructive detection of nonuniformities in the photoresponse of a semiconductor device. At SERI the photoresponse maps are used to identify solar cell faults including microcracks, metallization breaks, regions of poor contact between metallization and the underlying emitter surface, and variations in emitter sheet resistance. The SERI LSS is patterned after the LSS unit documented in the NBS Special Publication 400-24 A Laser Scanner for Semiconductor Devices by D.E. Sawyer and D.W. Berning. Assuming reader familiarity with the above publication, the modifications introduced by SERI are specified with the intention that the two reports can be used to reproduce the SERI LSS. The optical and electronic systems are reviewed, briefly discussing the significant items of each. The most notable difference between the two systems is the SERI substitution of commercially available state-of-the-art modular electronics for the discreet component circuitry used in the NBS LSS.

  13. Attenuation correction synthesis for hybrid PET-MR scanners: application to brain studies.

    PubMed

    Burgos, Ninon; Cardoso, M Jorge; Thielemans, Kris; Modat, Marc; Pedemonte, Stefano; Dickson, John; Barnes, Anna; Ahmed, Rebekah; Mahoney, Colin J; Schott, Jonathan M; Duncan, John S; Atkinson, David; Arridge, Simon R; Hutton, Brian F; Ourselin, Sebastien

    2014-12-01

    Attenuation correction is an essential requirement for quantification of positron emission tomography (PET) data. In PET/CT acquisition systems, attenuation maps are derived from computed tomography (CT) images. However, in hybrid PET/MR scanners, magnetic resonance imaging (MRI) images do not directly provide a patient-specific attenuation map. The aim of the proposed work is to improve attenuation correction for PET/MR scanners by generating synthetic CTs and attenuation maps. The synthetic images are generated through a multi-atlas information propagation scheme, locally matching the MRI-derived patient's morphology to a database of MRI/CT pairs, using a local image similarity measure. Results show significant improvements in CT synthesis and PET reconstruction accuracy when compared to a segmentation method using an ultrashort-echo-time MRI sequence and to a simplified atlas-based method. PMID:25055381

  14. A multichannel, real-time MRI RF power monitor for independent SAR determination

    SciTech Connect

    El-Sharkawy, AbdEl-Monem M.; Qian Di; Bottomley, Paul A.; Edelstein, William A. [Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins, University School of Medicine, Baltimore, Maryland 21287 (United States); Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins, University School of Medicine, Baltimore, Maryland 21287 (United States) and Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21287 (United States); Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins, University School of Medicine, Baltimore, Maryland 21287 (United States)

    2012-05-15

    Purpose: Accurate measurements of the RF power delivered during clinical MRI are essential for safety and regulatory compliance, avoiding inappropriate restrictions on clinical MRI sequences, and for testing the MRI safety of peripheral and interventional devices at known RF exposure levels. The goal is to make independent RF power measurements to test the accuracy of scanner-reported specific absorption rate (SAR) over the extraordinary range of operating conditions routinely encountered in MRI. Methods: A six channel, high dynamic range, real-time power profiling system was designed and built for monitoring power delivery during MRI up to 440 MHz. The system was calibrated and used in two 3 T scanners to measure power applied to human subjects during MRI scans. The results were compared with the scanner-reported SAR. Results: The new power measurement system has highly linear performance over a 90 dB dynamic range and a wide range of MRI duty cycles. It has about 0.1 dB insertion loss that does not interfere with scanner operation. The measurements of whole-body SAR in volunteers showed that scanner-reported SAR was significantly overestimated by up to about 2.2 fold. Conclusions: The new power monitor system can accurately and independently measure RF power deposition over the wide range of conditions routinely encountered during MRI. Scanner-reported SAR values are not appropriate for setting exposure limits during device or pulse sequence testing.

  15. A multichannel, real-time MRI RF power monitor for independent SAR determination

    PubMed Central

    El-Sharkawy, AbdEl-Monem M.; Qian, Di; Bottomley, Paul A.; Edelstein, William A.

    2012-01-01

    Purpose: Accurate measurements of the RF power delivered during clinical MRI are essential for safety and regulatory compliance, avoiding inappropriate restrictions on clinical MRI sequences, and for testing the MRI safety of peripheral and interventional devices at known RF exposure levels. The goal is to make independent RF power measurements to test the accuracy of scanner-reported specific absorption rate (SAR) over the extraordinary range of operating conditions routinely encountered in MRI. Methods: A six channel, high dynamic range, real-time power profiling system was designed and built for monitoring power delivery during MRI up to 440 MHz. The system was calibrated and used in two 3 T scanners to measure power applied to human subjects during MRI scans. The results were compared with the scanner-reported SAR. Results: The new power measurement system has highly linear performance over a 90 dB dynamic range and a wide range of MRI duty cycles. It has about 0.1 dB insertion loss that does not interfere with scanner operation. The measurements of whole-body SAR in volunteers showed that scanner-reported SAR was significantly overestimated by up to about 2.2 fold. Conclusions: The new power monitor system can accurately and independently measure RF power deposition over the wide range of conditions routinely encountered during MRI. Scanner-reported SAR values are not appropriate for setting exposure limits during device or pulse sequence testing. PMID:22559603

  16. MEMS optical scanners for microscopes

    Microsoft Academic Search

    Hiroshi Miyajima; Kenzi Murakami; Masahiro Katashiro

    2004-01-01

    Microelectromechanical systems (MEMS) optical scanners have been around for more than two decades. Various applications have been presented, but few of them have advanced to the commercial level to date due to the difficulties of combination of optics and MEMS devices. This paper presents our activities of investigating MEMS scanner applications related to microscopic imaging. First, we started with developing

  17. Development of Timd2 as a Reporter Gene for MRI

    E-print Network

    Patrick, P. Stephen; Rodrigues, Tiago B.; Kettunen, Mikko I.; Lyons, Scott K.; Neves, André A.; Brindle, Kevin M.

    2015-05-15

    on ice before imaging. MRI Experiments were carried out in a 7 Tesla (T) horizontal magnet (Oxford Instruments, UK) interfaced to a VNMRS (Varian Inc) imaging console. A 72-mm-diameter quadra- ture volume coil (Rapid Biomedical) was used in trans- mit...

  18. Functional MRI in the rat brain with single-shot gradient echo EPI at 16.4 T D. Z. Balla1

    E-print Network

    animals above 9.4 Tesla. However, the high SNR and spatial specificity expected at ultra-high field f protocol as basis for future fMRI-investigations. Methods Experiments were performed on a horizontal bore

  19. The physics goals of the TESLA project

    E-print Network

    Klaus Moenig

    2001-12-03

    As next generation e+e- linear collider the superconducting accelerator project TESLA has been proposed. In this note the physics potential goals of this project, which is highly complementary to LHC, are described.

  20. White matter hyperintensities on MRI in high-altitude U-2 pilots

    PubMed Central

    Sherman, Paul; Profenna, Leonardo; Grogan, Patrick; Sladky, John; Brown, Anthony; Robinson, Andrew; Rowland, Laura; Hong, Elliot; Patel, Beenish; Tate, David; Kawano, Elaine S.; Fox, Peter; Kochunov, Peter

    2013-01-01

    Objective: To demonstrate that U-2 pilot occupational exposure to hypobaria leads to increased incidence of white matter hyperintensities (WMH) with a more uniform distribution throughout the brain irrespective of clinical neurologic decompression sickness history. Methods: We evaluated imaging findings in 102 U-2 pilots and 91 controls matched for age, health, and education levels. Three-dimensional, T2-weighted, high-resolution (1-mm isotropic) imaging data were collected using fluid-attenuated inversion recovery sequence on a 3-tesla MRI scanner. Whole-brain and regional WMH volume and number were compared between groups using a 2-tailed Wilcoxon rank sum test. Results: U-2 pilots demonstrated an increase in volume (394%; p = 0.004) and number (295%; p < 0.001) of WMH. Analysis of regional distribution demonstrated WMH more uniformly distributed throughout the brain in U-2 pilots compared with mainly frontal distribution in controls. Conclusion: Pilots with occupational exposure to hypobaria showed a significant increase in WMH lesion volume and number. Unlike the healthy controls with predominantly WMH in the frontal white matter, WMH in pilots were more uniformly distributed throughout the brain. This is consistent with our hypothesized pattern of damage produced by interaction between microemboli and cerebral tissue, leading to thrombosis, coagulation, inflammation, and/or activation of innate immune response, although further studies will be necessary to clarify the pathologic mechanisms responsible. PMID:23960192

  1. Racetrack Coils for Dedicated MRI Magnets

    Microsoft Academic Search

    S. Pittaluga; S. Besio; V. Punzo; A. Trequattrini

    2010-01-01

    The need to optimize the magnet shape, size and region of homogeneity with respect to the anatomy of the patient is particularly strong in dedicated MRI magnet design: cost and weight are often determining factors for success in the market. An elongated coil geometry could be useful in cases where the scanner is designed for imaging non axisymmetric parts of

  2. Laser Scanner Demonstration

    SciTech Connect

    Fuss, B.

    2005-09-06

    In the Summer of 2004 a request for proposals went out to potential vendors to offer a three-dimensional laser scanner for a number of unique metrology tasks at the Stanford Linear Accelerator Center (SLAC). Specifications were established including range, accuracy, scan density, resolution and field of view in consideration of anticipated department requirements. Four vendors visited the site to present their system and they were asked to perform three unique tests with their system on a two day visit to SLAC. Two of the three tests were created to emulate real-world applications at SLAC while the third was an accuracy and resolution series of experiments. The scope of these tests is presented and some of the vendor's results are included.

  3. Multispectral scanner optical system

    NASA Technical Reports Server (NTRS)

    Stokes, R. C.; Koch, N. G. (inventors)

    1980-01-01

    An optical system for use in a multispectral scanner of the type used in video imaging devices is disclosed. Electromagnetic radiation reflected by a rotating scan mirror is focused by a concave primary telescope mirror and collimated by a second concave mirror. The collimated beam is split by a dichroic filter which transmits radiant energy in the infrared spectrum and reflects visible and near infrared energy. The long wavelength beam is filtered and focused on an infrared detector positioned in a cryogenic environment. The short wavelength beam is dispersed by a pair of prisms, then projected on an array of detectors also mounted in a cryogenic environment and oriented at an angle relative to the optical path of the dispersed short wavelength beam.

  4. TESLA Report 2004-10 Software layer for FPGA-based TESLA cavity control system

    E-print Network

    for superconducting Cavity Controller and Simulator (SIMCON) for the TESLA experiment in DESY (Hamburg). A number in the TESLA experiment [2,3,4,5] base on the newest FPGA chips [1,9]. This system requires not only. A significant feature of the FPGA-based systems is the possibility of easy modification of the functional layer

  5. fMRI evidence of improved visual function in patients with progressive retinitis pigmentosa by eye-movement training.

    PubMed

    Yoshida, Masako; Origuchi, Maki; Urayama, Shin-Ichi; Takatsuki, Akira; Kan, Shigeyuki; Aso, Toshihiko; Shiose, Takayuki; Sawamoto, Nobukatsu; Miyauchi, Satoru; Fukuyama, Hidenao; Seiyama, Akitoshi

    2014-01-01

    To evaluate changes in the visual processing of patients with progressive retinitis pigmentosa (RP) who acquired improved reading capability by eye-movement training (EMT), we performed functional magnetic resonance imaging (fMRI) before and after EMT. Six patients with bilateral concentric contraction caused by pigmentary degeneration of the retina and 6 normal volunteers were recruited. Patients were given EMT for 5 min every day for 8-10 months. fMRI data were acquired on a 3.0-Tesla scanner while subjects were performing reading tasks. In separate experiments (before fMRI scanning), visual performances for readings were measured by the number of letters read correctly in 5 min. Before EMT, activation areas of the primary visual cortex of patients were 48.8% of those of the controls. The number of letters read correctly in 5 min was 36.6% of those by the normal volunteers. After EMT, the activation areas of patients were not changed or slightly decreased; however, reading performance increased in 5 of 6 patients, which was 46.6% of that of the normal volunteers (p< 0.05). After EMT, increased activity was observed in the frontal eye fields (FEFs) of all patients; however, increases in the activity of the parietal eye fields (PEFs) were observed only in patients who showed greater improvement in reading capability. The improvement in reading ability of the patients after EMT is regarded as an effect of the increased activity of FEF and PEF, which play important roles in attention and working memory as well as the regulation of eye movements. PMID:25068106

  6. Conduction-coupled Tesla transformer.

    PubMed

    Reed, J L

    2015-03-01

    A proof-of-principle Tesla transformer circuit is introduced. The new transformer exhibits the high voltage-high power output signal of shock-excited transformers. The circuit, with specification of proper circuit element values, is capable of obtaining extreme oscillatory voltages. The primary and secondary portions of the circuit communicate solely by conduction. The destructive arcing between the primary and secondary inductors in electromagnetically coupled transformers is ubiquitous. Flashover is eliminated in the new transformer as the high-voltage inductors do not interpenetrate and so do not possess an annular volume of electric field. The inductors are remote from one another. The high voltage secondary inductor is isolated in space, except for a base feed conductor, and obtains earth by its self-capacitance to the surroundings. Governing equations, for the ideal case of no damping, are developed from first principles. Experimental, theoretical, and circuit simulator data are presented for the new transformer. Commercial high-temperature superconductors are discussed as a means to eliminate the counter-intuitive damping due to small primary inductances in both the electromagnetic-coupled and new conduction-coupled transformers. PMID:25832281

  7. Conduction-coupled Tesla transformer

    NASA Astrophysics Data System (ADS)

    Reed, J. L.

    2015-03-01

    A proof-of-principle Tesla transformer circuit is introduced. The new transformer exhibits the high voltage-high power output signal of shock-excited transformers. The circuit, with specification of proper circuit element values, is capable of obtaining extreme oscillatory voltages. The primary and secondary portions of the circuit communicate solely by conduction. The destructive arcing between the primary and secondary inductors in electromagnetically coupled transformers is ubiquitous. Flashover is eliminated in the new transformer as the high-voltage inductors do not interpenetrate and so do not possess an annular volume of electric field. The inductors are remote from one another. The high voltage secondary inductor is isolated in space, except for a base feed conductor, and obtains earth by its self-capacitance to the surroundings. Governing equations, for the ideal case of no damping, are developed from first principles. Experimental, theoretical, and circuit simulator data are presented for the new transformer. Commercial high-temperature superconductors are discussed as a means to eliminate the counter-intuitive damping due to small primary inductances in both the electromagnetic-coupled and new conduction-coupled transformers.

  8. Mental Rotation Studied by Functional Magnetic Resonance Imaging at High Field (4 Tesla): Performance and Cortical Activation

    Microsoft Academic Search

    Georgios A. Tagaris; Seong-Gi Kim; John P. Strupp; Peter Andersen; Kamil U??urbil; Apostolos P. Georgopoulos

    1997-01-01

    We studied the performance and cortical activation patterns during a mental rotation task (Shepard & Metzler, 1971) using functional magnetic resonance imaging (fMlU) at high field (4 Tesla). Twenty-four human subjects were imaged (fMRI group), whereas six additional subjects performed the task without being imaged (control group). All subjects were shown pairs of perspective drawings of 31, objects and asked

  9. Intraoral 3D scanner

    NASA Astrophysics Data System (ADS)

    Kühmstedt, Peter; Bräuer-Burchardt, Christian; Munkelt, Christoph; Heinze, Matthias; Palme, Martin; Schmidt, Ingo; Hintersehr, Josef; Notni, Gunther

    2007-09-01

    Here a new set-up of a 3D-scanning system for CAD/CAM in dental industry is proposed. The system is designed for direct scanning of the dental preparations within the mouth. The measuring process is based on phase correlation technique in combination with fast fringe projection in a stereo arrangement. The novelty in the approach is characterized by the following features: A phase correlation between the phase values of the images of two cameras is used for the co-ordinate calculation. This works contrary to the usage of only phase values (phasogrammetry) or classical triangulation (phase values and camera image co-ordinate values) for the determination of the co-ordinates. The main advantage of the method is that the absolute value of the phase at each point does not directly determine the coordinate. Thus errors in the determination of the co-ordinates are prevented. Furthermore, using the epipolar geometry of the stereo-like arrangement the phase unwrapping problem of fringe analysis can be solved. The endoscope like measurement system contains one projection and two camera channels for illumination and observation of the object, respectively. The new system has a measurement field of nearly 25mm × 15mm. The user can measure two or three teeth at one time. So the system can by used for scanning of single tooth up to bridges preparations. In the paper the first realization of the intraoral scanner is described.

  10. Prevalence of Incidental Pancreatic Cysts on 3 Tesla Magnetic Resonance

    PubMed Central

    de Oliveira, Patricia Bedesco; Puchnick, Andrea; Szejnfeld, Jacob; Goldman, Suzan Menasce

    2015-01-01

    Objectives To ascertain the prevalence of pancreatic cysts detected incidentally on 3-Tesla magnetic resonance imaging (MRI) of the abdomen and correlate this prevalence with patient age and gender; assess the number, location, and size of these lesions, as well as features suspicious for malignancy; and determine the prevalence of incidentally detected dilatation of the main pancreatic duct (MPD). Methods Retrospective analysis of 2,678 reports of patients who underwent abdominal MRI between January 2012 and June 2013. Patients with a known history of pancreatic conditions or surgery were excluded, and the remaining 2,583 reports were examined for the presence of pancreatic cysts, which was then correlated with patient age and gender. We also assessed whether cysts were solitary or multiple, as well as their location within the pancreatic parenchyma, size, and features suspicious for malignancy. Finally, we calculated the prevalence of incidental MPD dilatation, defined as MPD diameter ? 2.5 mm. Results Pancreatic cysts were detected incidentally in 9.3% of patients (239/2,583). The prevalence of pancreatic cysts increased significantly with age (p<0.0001). There were no significant differences in prevalence between men and women (p=0.588). Most cysts were multiple (57.3%), distributed diffusely throughout the pancreas (41.8%), and 5 mm or larger (81.6%). In 12.1% of cases, cysts exhibited features suspicious for malignancy. Overall, 2.7% of subjects exhibited incidental MPD dilatation. Conclusions In this sample, the prevalence of pancreatic cysts detected incidentally on 3T MRI of the abdomen was 9.3%. Prevalence increased with age and was not associated with gender. The majority of cysts were multiple, diffusely distributed through the pancreatic parenchyma, and ? 5 mm in size; 12.1% were suspicious for malignancy. An estimated 2.7% of subjects had a dilated MPD. PMID:25798910

  11. Split gradient coils for simultaneous PET-MRI.

    PubMed

    Poole, Michael; Bowtell, Richard; Green, Dan; Pittard, Simon; Lucas, Alun; Hawkes, Rob; Carpenter, Adrian

    2009-11-01

    Combining positron emission tomography (PET) and MRI necessarily involves an engineering tradeoff as the equipment needed for the two modalities vies for the space closest to the region where the signals originate. In one recently described scanner configuration for simultaneous positron emission tomography-MRI, the positron emission tomography detection scintillating crystals reside in an 80-mm gap between the 2 halves of a 1-T split-magnet cryostat. A novel set of gradient and shim coils has been specially designed for this split MRI scanner to include an 110-mm gap from which wires are excluded so as not to interfere with positron detection. An inverse boundary element method was necessarily employed to design the three orthogonal, shielded gradient coils and shielded Z0 shim coil. The coils have been constructed and tested in the hybrid positron emission tomography-MRI system and successfully used in simultaneous positron emission tomography-MRI experiments. PMID:19780167

  12. Coronary Artery Flow Measurement Using Navigator Echo Gated Phase Contrast Magnetic Resonance Velocity Mapping at 3.0 Tesla

    PubMed Central

    Johnson, Kevin; Sharma, Puneet; Oshinski, John

    2009-01-01

    A validation study and early results for noninvasive, in vivo measurement of coronary artery blood flow using phase contrast magnetic resonance imaging (PC-MRI) at 3.0 Tesla is presented. Accuracy of coronary artery blood flow measurements by phase contrast MRI is limited by heart and respiratory motion as well as the small size of the coronary arteries. In this study, a navigator-echo gated, cine phase velocity mapping technique is described to obtain time-resolved velocity and flow waveforms of small diameter vessels at 3.0 Tesla. Phantom experiments using steady, laminar flow are presented to validate the technique and show flow rates measured by 3.0 Tesla phase contrast MRI to be accurate within 15% of true flow rates. Subsequently, in vivo scans on healthy volunteers yield velocity measurements for blood flow in the right, left anterior descending, and left circumflex arteries. Measurements of average, cross-sectional velocity were obtainable in 224/243 (92%) of the cardiac phases. Time-averaged, cross-sectional velocity of the blood flow was 6.8±4.3 cm/s in the LAD, 8.0±3.8 cm/s in the LCX, and 6.0±1.6 cm/s in the RCA. PMID:18036532

  13. MSS D Multispectral Scanner System

    NASA Technical Reports Server (NTRS)

    Lauletta, A. M.; Johnson, R. L.; Brinkman, K. L. (principal investigators)

    1982-01-01

    The development and acceptance testing of the 4-band Multispectral Scanners to be flown on LANDSAT D and LANDSAT D Earth resources satellites are summarized. Emphasis is placed on the acceptance test phase of the program. Test history and acceptance test algorithms are discussed. Trend data of all the key performance parameters are included and discussed separately for each of the two multispectral scanner instruments. Anomalies encountered and their resolutions are included.

  14. The Impact of the fMRI Environment on Cognitive Function: A Visual Working Memory Study 

    E-print Network

    Dunbar, Jill

    2008-12-04

    The environment within an fMRI scanner can be intimidating, featuring characteristics such as extreme noise levels, postural constraints, and claustrophobic conditions. It is likely that these external pressures can have ...

  15. A study of quantification of aortic compliance in mice using radial acquisition phase contrast MRI

    NASA Astrophysics Data System (ADS)

    Zhao, Xuandong

    Spatiotemporal changes in blood flow velocity measured using Phase contrast Magnetic Resonance Imaging (MRI) can be used to quantify Pulse Wave Velocity (PWV) and Wall Shear Stress (WSS), well known indices of vessel compliance. A study was conducted to measure the PWV in the aortic arch in young healthy children using conventional phase contrast MRI and a post processing algorithm that automatically track the peak velocity in phase contrast images. It is shown that the PWV calculated using peak velocity-time data has less variability compared to that using mean velocity and flow. Conventional MR data acquisition techniques lack both the spatial and temporal resolution needed to accurately calculate PWV and WSS in in vivo studies using transgenic animal models of arterial diseases. Radial k-space acquisition can improve both spatial and temporal resolution. A major part of this thesis was devoted to developing technology for Radial Phase Contrast Magnetic Resonance (RPCMR) cine imaging on a 7 Tesla Animal scanner. A pulse sequence with asymmetric radial k-space acquisition was designed and implemented. Software developed to reconstruct the RPCMR images include gridding, density compensation and centering of k-Space that corrects the image ghosting introduced by hardware response time. Image processing software was developed to automatically segment the vessel lumen and correct for phase offset due to eddy currents. Finally, in vivo and ex vivo aortic compliance measurements were conducted in a well-established mouse model for atherosclerosis: Apolipoprotein E-knockout (ApoE-KO). Using RPCMR technique, a significantly higher PWV value as well as a higher average WSS was detected among 9 months old ApoE-KO mice compare to in wild type mice. A follow up ex-vivo test of tissue elasticity confirmed the impaired distensibility of aortic arteries among ApoE-KO mice.

  16. Acoustic noise reduction in MRI using Silent Scan: an initial experience

    PubMed Central

    Alibek, Sedat; Vogel, Mika; Sun, Wei; Winkler, David; Baker, Christopher A.; Burke, Michael; Gloger, Hubertus

    2014-01-01

    PURPOSE Acoustic noise during magnetic resonance imaging (MRI) is the main source for patient discomfort and leads to verbal communication problems, difficulties in sedation, and hearing impairment. Silent Scan technology uses less changes in gradient excitation levels, which is directly related to noise levels. Here, we report our preliminary experience with this technique in neuroimaging with regard to subjective and objective noise levels and image quality. MATERIALS AND METHODS Ten patients underwent routine brain MRI with 3 Tesla MR750w system and 12-channel head coil. T1-weighted gradient echo (BRAVO) and Silenz pulse sequence (TE=0, 3D radial center-out k-space filling and data sampling with relatively small gradient steps) were performed. Patients rated subjective sound impression for both sequences on a 6-point scale. Objective sound level measurements were performed with a dedicated device in gantry at different operation modes. Image quality was subjectively assessed in consensus by two radiologists on a 3-point scale. RESULTS Readers rated image quality as fully diagnostic in all patients. Measured mean noise was reduced significantly with Silenz sequence (68.8 dB vs. 104.65 dB with BRAVO, P = 0.024) corresponding to 34.3% reduction in sound intensity and 99.97% reduction in sound pressure. No significant difference was observed between Silenz sound levels and ambient sounds (i.e., background noise in the scanner room, 68.8 dB vs. 68.73 dB, P = 0.5). The patients’ subjective sound level score was lower for Silenz compared with conventional sequence (1.1 vs. 2.3, P = 0.003). CONCLUSION T1-weighted Silent Scan is a promising technique for acoustic noise reduction and improved patient comfort. PMID:24808439

  17. fMRI-acoustic noise alters brain activation during working memory tasks

    Microsoft Academic Search

    D. Tomasi; E. C. Caparelli; L. Chang; T. Ernst

    2005-01-01

    Scanner noise during functional magnetic resonance imaging (fMRI) may interfere with brain function and change blood oxygenation level dependent (BOLD) signals, a problem that generally worsens at the higher field strengths. Therefore, we studied the effect of increased acoustic noise on fMRI during verbal working memory (WM) processing. The sound pressure level of scanner noise was increased by 12 dBA

  18. Design and scaling of microscale Tesla turbines

    NASA Astrophysics Data System (ADS)

    Krishnan, Vedavalli G.; Romanin, Vince; Carey, Van P.; Maharbiz, Michel M.

    2013-12-01

    We report on the scaling properties and loss mechanisms of Tesla turbines and provide design recommendations for scaling such turbines to the millimeter scale. Specifically, we provide design, fabrication and experimental data for a low-pressure head hydro Tesla micro-turbine. We derive the analytical turbine performance for incompressible flow and then develop a more detailed model that predicts experimental performance by including a variety of loss mechanisms. We report the correlation between them and the experimental results. Turbines with 1 cm rotors, 36% peak efficiency (at 2 cm3 s-1 flow) and 45 mW unloaded peak power (at 12 cm3 s-1 flow) are demonstrated. We analyze the causes for head loss and shaft power loss and derive constraints on turbine design. We then analyze the effect of scaling down on turbine efficiency, power density and rotor revolutions/min. Based on the analysis, we make recommendations for the design of ˜1 mm microscale Tesla turbines.

  19. Determination of beam energy at TESLA using radiative return events

    E-print Network

    Determination of beam energy at TESLA using radiative return events ARND HINZE DESY Zeuthen at TESLA. It was suggested to use this method to cross check and calibrate the magnet spectrometer used for measurement of the beam energy at TESLA. A preliminary assessment of the statistical and systematic errors

  20. Analyse de l'architecture GPU Tesla Sylvain Collange

    E-print Network

    Boyer, Edmond

    Analyse de l'architecture GPU Tesla Sylvain Collange DALI, ELIAUS, Universit´e de Perpignan sylvain comprise. Nous pr´esentons ici une description du fonctionnement de l'architecture Tesla de NVIDIA et de;2 Tesla Nous nous pencherons dans cet article sur l'architecture des GPU NVIDIA d´ebut´ee avec le G80 (Ge

  1. Hydrodynamic Tesla Wheel Flume for Model and Prototype Testing

    E-print Network

    Wood, Stephen L.

    Hydrodynamic Tesla Wheel Flume for Model and Prototype Testing Spencer Jenkins, Chris Scott, Jacob Engineering department at Florida Institute of Technology (Florida Tech) has developed a Hydrodynamic Tesla, hydrodynamic, laminar, fluid, flow, model, prototype testing, Tesla wheel. I. INTRODUCTION The southeast region

  2. TESLA 2002-10 CBP Tech Note-268

    E-print Network

    LCC-0108 TESLA 2002-10 CBP Tech Note-268 Comparison of Emittance Tuning Simulations in the NLC and TESLA Damping Rings A. Wolski LBNL W. Decking DESY November 11th , 2002 Abstract Vertical emittance is a critical issue for future linear collider damping rings. Both NLC and TESLA specify vertical emittance

  3. TESLA Technical Design Report Editors: R.Klanner

    E-print Network

    TESLA Technical Design Report PART VI Appendices March 2001 Editors: R.Klanner Chapter 1: V.Rith #12;#12;Introduction VI-i Introduction These appendices to the TESLA Technical Design Report (TDR) describe four addi- tional particle-physics projects, which can be carried out at the TESLA e+ e- -collider

  4. TESLA POLARIMETERS V.GHARIBYAN, N. MEYNERS, K. P. SCH

    E-print Network

    TESLA POLARIMETERS V.GHARIBYAN, N. MEYNERS, K. P. SCH  ULER DESY, Deutsches Elektronen Synchrotron + e linear collider machine TESLA. A segment of the beam delivery system has been identi#12;ed, which the pulse and bunch structure of TESLA. This will permit very fast and ac- curate measurements

  5. TESLA Report 2005-08 Hamburg 28.02.2005

    E-print Network

    TESLA Report 2005-08 Hamburg 28.02.2005 First Generation of Optical Fiber Phase Reference Distribution System for TESLA Krzysztof Czubaa , Frank Eintsb , Matthias Felberb , Janusz Dobrowolskia , Stefan describes the design of a phase stable Fiber Optic (FO) link for the TESLA technology based projects

  6. LCM2003045 Improved TESLA Optics and Beam Induced

    E-print Network

    LC­M­2003­045 Improved TESLA Optics and Beam Induced Backgrounds Update Karsten BË?uÃ?er, DESY and Olivier Napoly, CEA/Saclay LCWS 2002, Jeju, Korea Abstract A new tesla optics with l*=5m is under development. An update is given on the simulation of the beam induced backgrounds in the TESLA detector. 1

  7. Luminosity Stability Issues for the TESLA Beam Delivery System (BDS)

    E-print Network

    Luminosity Stability Issues for the TESLA Beam Delivery System (BDS) Nicholas Walker1 (DESY, Germany) Andrzej Wolski2 (Daresbury Laboratory, UK) TESLA 2000-22 October 17, 2000 1 Introduction Given of ground motion and vibration in linear colliders both for TESLA and NLC/JLC (see for example [1

  8. TESLA: A Formally Defined Event Specification Language Gianpaolo Cugola

    E-print Network

    Cugola, Gianpaolo

    TESLA: A Formally Defined Event Specification Language Gianpaolo Cugola Dip. di Elettronica e to clearly state how the system should behave. Moving from these premises, we present TESLA, a complex event specification language. Each TESLA rule considers incoming data items as notifi- cations of events and defines

  9. TESLA Report 2006-04 DESY Thesis 2006-000

    E-print Network

    TESLA Report 2006-04 DESY Thesis 2006-000 WARSAW UNIVERSITY OF TECHNOLOGY Faculty of Electronics and Informational Technologies Institute of Electronic Systems ELHEP Laboratory DESY TESLA LLRF Team Jerzy Stefan Zieliski Synchronic, optical transmission data link integrated with FPGA circuits (for TESLA LLRF control

  10. Multicore Platforms for Scientific Computing: Cell BE and NVIDIA Tesla

    E-print Network

    Acacio, Manuel

    Multicore Platforms for Scientific Computing: Cell BE and NVIDIA Tesla J. Fern´andez, M.E. Acacio Tesla computing solutions. The former is a re- cent heterogeneous chip-multiprocessor (CMP) architecture, multicore, Cell BE, NVIDIA Tesla, CUDA 1 Introduction Nowadays, multicore architectures are omnipresent

  11. Beam Dynamics Study for TESLA with the Integrated FEL

    E-print Network

    Beam Dynamics Study for TESLA with the Integrated FEL V.M. Tsakanov Yerevan Physics Institute : : : : : : : : : : : : : : : : : : : : : : : 7 2.3 Conclusion 1 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 10 3 The TESLA high based trajectory correction : : : : : : : : : : : : 22 5 Summary 25 1 #12;. 1 Introduction In the TESLA

  12. MRI Stealth” robot for prostate interventions

    PubMed Central

    STOIANOVICI, DAN; SONG, DANNY; PETRISOR, DORU; URSU, DANIEL; MAZILU, DUMITRU; MUTENER, MICHAEL; SCHAR, MICHAEL; PATRICIU, ALEXANDRU

    2011-01-01

    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-dose radiation seed brachytherapy. This paper gives an introduction to the challenges of MRI robot compatibility and presents the solutions adopted in making the MrBot. Its multi-imager compatibility and other preclinical tests are included. The robot shows the technical feasibility of MRI-guided prostate interventions, yet its clinical utility is still to be determined. PMID:17763098

  13. Impairment of chondrocyte biosynthetic activity by exposure to 3-tesla high-field magnetic resonance imaging is temporary

    PubMed Central

    Sunk, Ilse-Gerlinde; Trattnig, Siegfried; Graninger, Winfried B; Amoyo, Love; Tuerk, Birgit; Steiner, Carl-Walter; Smolen, Josef S; Bobacz, Klaus

    2006-01-01

    The influence of magnetic resonance imaging (MRI) devices at high field strengths on living tissues is unknown. We investigated the effects of a 3-tesla electromagnetic field (EMF) on the biosynthetic activity of bovine articular cartilage. Bovine articular cartilage was obtained from juvenile and adult animals. Whole joints or cartilage explants were subjected to a pulsed 3-tesla EMF; controls were left unexposed. Synthesis of sulfated glycosaminoglycans (sGAGs) was measured by using [35S]sulfate incorporation; mRNA encoding the cartilage markers aggrecan and type II collagen, as well as IL-1?, were analyzed by RT–PCR. Furthermore, effects of the 3-tesla EMF were determined over the course of time directly after exposure (day 0) and at days 3 and 6. In addition, the influence of a 1.5-tesla EMF on cartilage sGAG synthesis was evaluated. Chondrocyte cell death was assessed by staining with Annexin V and TdT-mediated dUTP nick end labelling (TUNEL). Exposure to the EMF resulted in a significant decrease in cartilage macromolecule synthesis. Gene expression of both aggrecan and IL-1?, but not of collagen type II, was reduced in comparison with controls. Staining with Annexin V and TUNEL revealed no evidence of cell death. Interestingly, chondrocytes regained their biosynthetic activity within 3 days after exposure, as shown by proteoglycan synthesis rate and mRNA expression levels. Cartilage samples exposed to a 1.5-tesla EMF remained unaffected. Although MRI devices with a field strength of more than 1.5 T provide a better signal-to-noise ratio and thereby higher spatial resolution, their high field strength impairs the biosynthetic activity of articular chondrocytes in vitro. Although this decrease in biosynthetic activity seems to be transient, articular cartilage exposed to high-energy EMF may become vulnerable to damage. PMID:16831232

  14. George Gollin, Investigation of TESLA Damping Ring Kickers using the A0 Photoinjector Beam 1 Investigation of TESLA Damping

    E-print Network

    Gollin, George

    George Gollin, Investigation of TESLA Damping Ring Kickers using the A0 Photoinjector Beam 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .. . . .. .. . . . .. . . . .. . . . . . . .. .. . . . . . . IPhysicsP Illinois Investigation of TESLA Damping Ring Kickers using the A0 Photoinjector Beam George, Investigation of TESLA Damping Ring Kickers using the A0 Photoinjector Beam 2

  15. MRI with an atomic magnetometer suitable for practical imaging applications

    NASA Astrophysics Data System (ADS)

    Savukov, I. M.; Zotev, V. S.; Volegov, P. L.; Espy, M. A.; Matlashov, A. N.; Gomez, J. J.; Kraus, R. H.

    2009-08-01

    Conventionally implemented MRI is performed in a strong magnetic field, typically >1 T. The high fields, however, can lead to many limitations. To overcome these limitations, ultra-low field (ULF) [or microtesla] MRI systems have been proposed and implemented. To-date such systems rely on low-Tc Superconducting Quantum Interference Devices (SQUIDs) leading to the requirement of cryogens. In this letter, we report ULF-MRI obtained with a non-cryogenic atomic magnetometer. This demonstration creates opportunities for developing inexpensive and widely applicable MRI scanners.

  16. MRI with an atomic magnetometer suitable for practical imaging applications.

    PubMed

    Savukov, I M; Zotev, V S; Volegov, P L; Espy, M A; Matlashov, A N; Gomez, J J; Kraus, R H

    2009-08-01

    Conventionally implemented MRI is performed in a strong magnetic field, typically >1T. The high fields, however, can lead to many limitations. To overcome these limitations, ultra-low field (ULF) [or microtesla] MRI systems have been proposed and implemented. To-date such systems rely on low-Tc Superconducting Quantum Interference Devices (SQUIDs) leading to the requirement of cryogens. In this letter, we report ULF-MRI obtained with a non-cryogenic atomic magnetometer. This demonstration creates opportunities for developing inexpensive and widely applicable MRI scanners. PMID:19435672

  17. Neurodegenerative changes in Alzheimer's disease: a comparative study of manual, semi-automated, and fully automated assessment using MRI

    NASA Astrophysics Data System (ADS)

    Fritzsche, Klaus H.; Giesel, Frederik L.; Heimann, Tobias; Thomann, Philipp A.; Hahn, Horst K.; Pantel, Johannes; Schröder, Johannes; Essig, Marco; Meinzer, Hans-Peter

    2008-03-01

    Objective quantification of disease specific neurodegenerative changes can facilitate diagnosis and therapeutic monitoring in several neuropsychiatric disorders. Reproducibility and easy-to-perform assessment are essential to ensure applicability in clinical environments. Aim of this comparative study is the evaluation of a fully automated approach that assesses atrophic changes in Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI). 21 healthy volunteers (mean age 66.2), 21 patients with MCI (66.6), and 10 patients with AD (65.1) were enrolled. Subjects underwent extensive neuropsychological testing and MRI was conducted on a 1.5 Tesla clinical scanner. Atrophic changes were measured automatically by a series of image processing steps including state of the art brain mapping techniques. Results were compared with two reference approaches: a manual segmentation of the hippocampal formation and a semi-automated estimation of temporal horn volume, which is based upon interactive selection of two to six landmarks in the ventricular system. All approaches separated controls and AD patients significantly (10 -5 < p < 10 -4) and showed a slight but not significant increase of neurodegeneration for subjects with MCI compared to volunteers. The automated approach correlated significantly with the manual (r = -0.65, p < 10 -6) and semi automated (r = -0.83, p < 10 -13) measurements. It proved high accuracy and at the same time maximized observer independency, time reduction and thus usefulness for clinical routine.

  18. Effect of 1. 5 tesla nuclear magnetic resonance imaging scanner on implanted permanent pacemakers

    Microsoft Academic Search

    David L. Hayes; David R. Holmes Jr.; Joel E. Gray

    1987-01-01

    Patients with a permanent pacemaker are currently restricted from diagnostic nuclear magnetic resonance (NMR) imaging because of potential adverse effects on the pacemaker by the magnet. Previous work has shown that NMR imaging will result in asynchronous pacing of the pulse generator within a given distance of the magnet. The radiofrequency signal generated by the system may also result in

  19. Post-mortem magnetic resonance microscopy (MRM) of the murine brain at 7 Tesla results in a gain of resolution as compared to in vivo MRM

    PubMed Central

    von Bohlen und Halbach, Oliver; Lotze, Martin; Pfannmöller, Jörg P.

    2014-01-01

    Small-animal MRI with high field strength allows imaging of the living animal. However, spatial resolution in in vivo brain imaging is limited by the scanning time. Measurements of fixated mouse brains allow longer measurement time, but fixation procedures are time consuming, since the process of fixation may take several weeks. We here present a quick and simple post-mortem approach without fixation that allows high-resolution MRI even at 7 Tesla (T2-weighted MRI). This method was compared to in vivo scans with optimized spatial resolution for the investigation of anesthetized mice (T1-weighted MRI) as well as to ex situ scans of fixed brains (T1- and T2-weighted scans) by using standard MRI-sequences, along with anatomic descriptions of areas observable in the MRI, analysis of tissue shrinkage and post-processing procedures (intensity inhomogeneity correction, PCNN3D brain extract, SPMMouse segmentation, and volumetric measurement). Post-mortem imaging quality was sufficient to determine small brain substructures on the morphological level, provided fast possibilities for volumetric acquisition and for automatized processing without manual correction. Moreover, since no fixation was used, tissue shrinkage due to fixation does not occur as it is, e.g., the case by using ex vivo brains that have been kept in fixatives for several days. Thus, the introduced method is well suited for comparative investigations, since it allows determining small structural alterations in the murine brain at a reasonable high resolution even by MRI performed at 7 Tesla. PMID:24982617

  20. Multispectral Scanner for Monitoring Plants

    NASA Technical Reports Server (NTRS)

    Gat, Nahum

    2004-01-01

    A multispectral scanner has been adapted to capture spectral images of living plants under various types of illumination for purposes of monitoring the health of, or monitoring the transfer of genes into, the plants. In a health-monitoring application, the plants are illuminated with full-spectrum visible and near infrared light and the scanner is used to acquire a reflected-light spectral signature known to be indicative of the health of the plants. In a gene-transfer- monitoring application, the plants are illuminated with blue or ultraviolet light and the scanner is used to capture fluorescence images from a green fluorescent protein (GFP) that is expressed as result of the gene transfer. The choice of wavelength of the illumination and the wavelength of the fluorescence to be monitored depends on the specific GFP.

  1. TESLA Report 2005-22 Internal Interface

    E-print Network

    of Electronic Systems, Warsaw University of Technology, ELHEP Laboratory Nowowiejska 15/19, 00-665 Warsaw/O, VHDL, Altera, Xilinx, communication interface, behavioral programming, FPGA systems parameterization- 1/63 - TESLA Report 2005-22 Internal Interface I/O communication with FPGA circuits and hardware

  2. MIT 12 Tesla Coil test results

    Microsoft Academic Search

    M. M. Steeves; M. O. Hoenig

    1985-01-01

    Test results from the MIT 12 Tesla Coil experiment are presented. The coil was tested in the High Field Test Facility (HFTF) of the Lawrence Livermore National Laboratory in October 1984 and January 1985. The experiment measured the performance of an Internally Cooled, Cabled Superconductor (ICCS) of practical size, intended for use in magnetic fusion experiments. The MIT coil carried

  3. Cortical thickness, surface area, and folding alterations in male youths with conduct disorder and varying levels of callous-unemotional traits

    E-print Network

    Fairchild, Graeme; Toschi, Nicola; Hagan, Cindy C.; Goodyer, Ian M.; Calder, Andrew J.; Passamonti, Luca

    2015-04-30

    by the Suffolk National Health Service Research Ethics Committee and written informed consent was obtained from all participants. 2.2. Magnetic resonance imaging (MRI) data acquisition Structural MRI data were acquired using a 3-Tesla Siemens Tim Trio scanner...

  4. Choosing a Scanner: Points To Consider before Buying a Scanner.

    ERIC Educational Resources Information Center

    Raby, Chris

    1998-01-01

    Outlines ten factors to consider before buying a scanner: size of document; type of document; color; speed and volume; resolution; image enhancement; image compression; optical character recognition; scanning subsystem; and the option to use a commercial bureau service. The importance of careful analysis of requirements is emphasized. (AEF)

  5. Improvements to Existing Jefferson Lab Wire Scanners

    SciTech Connect

    McCaughan, Michael D. [JLAB; Tiefenback, Michael G. [JLAB; Turner, Dennis L. [JLAB

    2013-06-01

    This poster will detail the augmentation of selected existing CEBAF wire scanners with commercially available hardware, PMTs, and self created software in order to improve the scanners both in function and utility.

  6. 2.3.' , MRI .

    E-print Network

    1 34.2.2014 2009. ".. )MRI(. - - -ELSC "- -, "- , ,' ,- - ,ELSC.8.,. ­"" ) , , "( . , , , . . , . , . . . . - - ),(. 0F 1 MRI . . MRI . 100. . . ·. ·-. · . · , . 1. #12;3 I.IV)(/ . . / . / /­ , . 1. ,., MRI,,. )-(. ):,'4.( 2. ·18,18. ·. ·. ·. · . 3. :,. :: ·-MRI

  7. Value of 3 Tesla diffusion-weighted magnetic resonance imaging for assessing liver fibrosis

    PubMed Central

    Papalavrentios, Lavrentios; Sinakos, Emmanouil; Chourmouzi, Danai; Hytiroglou, Prodromos; Drevelegas, Konstantinos; Constantinides, Manos; Drevelegas, Antonios; Talwalkar, Jayant; Akriviadis, Evangelos

    2015-01-01

    Background Limited data are available regarding the role of magnetic resonance imaging (MRI), particularly the new generation 3 Tesla technology, and especially diffusion-weighted imaging (DWI) in predicting liver fibrosis. The aim of our pilot study was to assess the clinical performance of the apparent diffusion coefficient (ADC) of liver parenchyma for the assessment of liver fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). Methods 18 patients with biopsy-proven NAFLD underwent DWI with 3 Tesla MRI. DWI was performed with single-shot echo-planar technique at b values of 0-500 and 0-1000 s/mm2. ADC was measured in four locations in the liver and the mean ADC value was used for analysis. Staging of fibrosis was performed according to the METAVIR system. Results The median age of patients was 52 years (range 23-73). The distribution of patients in different fibrosis stages was: 0 (n=1), 1 (n=7), 2 (n=1), 3 (n=5), 4 (n=4). Fibrosis stage was poorly associated with ADC at b value of 0-500 s/mm2 (r= -0.30, P=0.27). However it was significantly associated with ADC at b value of 0-1000 s/mm2 (r= -0.57, P=0.01). For this b value (0-1000 s/mm2) the area under receiver-operating characteristic curve was 0.93 for fibrosis stage ?3 and the optimal ADC cut-off value was 1.16 ×10-3 mm2/s. Conclusion 3 Tesla DWI can possibly predict the presence of advanced fibrosis in patients with NAFLD. PMID:25608776

  8. Galvanometer Optical Scanner INSTRUCTION MANUAL

    E-print Network

    Kleinfeld, David

    inside the bearing will reduce bearing life. Note: As with any high performance motor, resonances created with anything other than light finger pressure on the front shaft or damage to the front bearing can occur. Do in contact with the front bearing. It is located right at the front end ofthe scanner. Foreign material

  9. AIR BAND SCANNER WITH RETRANSMISSION

    E-print Network

    Yu, Chansu

    AIR BAND SCANNER WITH RETRANSMISSION TO LOCAL FM RADIO USING A SOFTWARE DEFINED RADIO Final Report was very low Determined that the antenna was the easiest thing to upgrade Built a quarter wave ground plane antenna $15 worth of parts from Radio Shack and Home Depot Quarter Wave Ground Plane Antenna Vertical ­ 23

  10. What Scanner products are available?

    Atmospheric Science Data Center

    2014-12-08

    There are single satellite and combined-satellite scanner products. The best source for ... all the S4G monthly mean 2.5 degree gridded data from both single satellite and combined-satellite product in ASCII format. Also, ordering ...

  11. Scanner as a Fine Art

    ERIC Educational Resources Information Center

    Fontes, Kris

    2008-01-01

    Not every art department is fortunate enough to have access to digital cameras and image-editing software, but if a scanner, computer, and printer are available, students can create some imaginative and surreal work. This high-school level lesson begins with a discussion of self-portraits, and then moves to students creating images by scanning…

  12. Inverting input scanner vibration errors

    Microsoft Academic Search

    George Wolberg; Robert C. Loce

    1995-01-01

    Images scanned in the presence of mechanical vibrations are subject to artifacts such as brightness fluctuation and geometric warping. The goal of this work is to develop an algorithm to invert these distortions and produce an output digital image consistent with a scanner operating under ideal uniform motion conditions. The image restoration algorithm described in this paper applies to typical

  13. Simulation of LANDSAT multispectral scanner spatial resolution with airborne scanner data

    NASA Technical Reports Server (NTRS)

    Hlavka, C. A.

    1986-01-01

    A technique for simulation of low spatial resolution satellite imagery by using high resolution scanner data is described. The scanner data is convolved with the approximate point spread function of the low resolution data and then resampled to emulate low resolution imagery. The technique was successfully applied to Daedalus airborne scanner data to simulate a portion of a LANDSAT multispectra scanner scene.

  14. Evaluating Commercial Scanners for Astronomical Image Digitization

    Microsoft Academic Search

    R. J. Simcoe

    2009-01-01

    Many organizations have been interested in understanding if commercially available scanners are adequate for scientifically useful digitization. These scanners range in price from a few hundred to a few tens of thousands of dollars (USD), often with little apparent difference in performance specifications. This paper describes why the underlying technology used in flatbed scanners tends to effectively limit resolutions to

  15. [MPC0910112] Visiderm Skin Scanner Analysis

    E-print Network

    New Mexico, University of

    by dermatologists for diagnostic purposes. The Visiderm Skin Scanner enhances visibility of skin texture, markings[MPC0910112] Visiderm Skin Scanner Analysis The Visiderm Skin Scanner is a registered medical device which uses a "black" or ultraviolet light with a UVA lamp. This type of light is routinely used

  16. A Laser Range Scanner Designed for Minimum

    E-print Network

    Stanford University

    and Modeling3D Digital Imaging and Modeling 3DIM 20013DIM 2001 #12;2 Scanner Designs #12;3 Scanner DesignA Laser Range Scanner Designed for Minimum Calibration Complexity James Davis,James Davis, XingXing ChenChen Stanford Computer Graphics LaboratoryStanford Computer Graphics Laboratory 3D Digital Imaging

  17. MRI-Monitored Intra-Tumoral Injection of Iron-Oxide Labeled Clostridium novyi-NT Anaerobes in Pancreatic Carcinoma Mouse Model

    PubMed Central

    Zheng, Linfeng; Zhang, Zhuoli; Khazaie, Khashayarsha; Saha, Saurabh; Lewandowski, Robert J.; Zhang, Guixiang; Larson, Andrew C.

    2014-01-01

    Objectives To validate the feasibility of labeling Clostridium novyi-NT (C.novyi-NT) anaerobes with iron-oxide nanoparticles for magnetic resonance imaging (MRI) and demonstrate the potential to use MRI to visualize intra-tumoral delivery of these iron-oxide labeled C.novyi-NT during percutaneous injection procedures. Materials and Methods All studies were approved by IACUC. C.novyi-NT were labeled with hybrid iron-oxide Texas red nanoparticles. Growth of labeled and control samples were evaluated with optical density. Labeling was confirmed with confocal fluorescence and transmission electron microscopy (TEM). MRI were performed using a 7 Tesla scanner with T2*-weighted (T2*W) sequence. Contrast-to-noise ratio (CNR) measurements were performed for phantoms and signal-to-noise ratio (SNR) measurements performed in C57BL/6 mice (n?=?12) with Panc02 xenografts before and after percutaneous injection of iron-oxide labeled C.novyi-NT. MRI was repeated 3 and 7 days post-injection. Hematoxylin-eosin (HE), Prussian blue and Gram staining of tumor specimens were performed for confirmation of intra-tumoral delivery. Results Iron-oxide labeling had no influence upon C.novyi-NT growth. The signal intensity (SI) within T2*W images was significantly decreased for iron-oxide labeled C.novyi-NT phantoms compared to unlabeled controls. Under confocal fluorescence microscopy, the iron-oxide labeled C.novyi-NT exhibited a uniform red fluorescence consistent with observed regions of DAPI staining and overall labeling efficiency was 100% (all DAPI stained C.novyi-NT exhibited red fluorescence). Within TEM images, a large number iron granules were observed within the iron-oxide labeled C.novyi-NT; these were not observed within unlabeled controls. Intra-procedural MRI measurements permitted in vivo visualization of the intra-tumoral distribution of iron-oxide labeled C.novyi-NT following percutaneous injection (depicted as punctate regions of SI reductions within T2*-weighted images); tumor SNR decreased significantly following intra-tumoral injection of C.novyi-NT (p<0.05); these SNR reductions were maintained at 3 and 7 day follow-up intervals. Prussian blue and Gram staining confirmed presence of the iron-oxide labeled anaerobes. Conclusions C.novyi-NT can be labeled with iron-oxide nanoparticles for MRI visualization of intra-tumoral deposition following percutaneous injection during bacteriolytic therapy. PMID:25549324

  18. Functional relations of empathy and mentalizing: an fMRI study on the neural basis of cognitive empathy.

    PubMed

    Schnell, Knut; Bluschke, Sarah; Konradt, Brigitte; Walter, Henrik

    2011-01-15

    This fMRI study was set up to explore how cognitive empathy, i.e. the cognitive inference on another person's affective state, can be characterized as a distinct brain function relating to pre-existing neurofunctional concepts about mentalizing and empathy. In a 3 Tesla MRI scanner 28 healthy participants were presented with four different instructions randomly combined with 32 false-belief cartoon stories of 3 subsequent pictures free of direct cues for affective states, like e.g. facial expressions. Participants were instructed to judge affective or visuospatial changes from their own (1st person perspective) or the protagonists' (3rd person perspective, 3rdpp) perspective. 3rdpp-judgements about affective states differed from visuospatial 3rdpp judgements by a significantly higher activation of the anterior mentalizing network (dorsomedial prefrontal cortex, anterior superior temporal sulcus, temporal poles) and the limbic system (left amygdala and hippocampus). Analysis of main effects revealed that the anterior part of the mentalizing network was activated significantly stronger by affective compared to visuospatial content. In contrast, the temporoparietal junction was rather activated by 3rdpp visuospatial judgements. After all, our results demonstrate a functional dissociation between cognitive empathy and cognitive visuospatial perspective taking. The simultaneous activation of the cortical mentalizing network and the amygdala indicates that cognitive empathy actually involves reference to own affective states in the observer. Notably, the cognitive reference to own affective states activated the mentalizing network as well. Moreover our results support pre-existing ideas about a functional anterior-posterior subdivision of the mentalizing network, depending on affective content and 3rd person perspective of cognition. PMID:20728556

  19. Diffusion MRI simulation with the Virtual Imaging Platform Lihui Wang, Sorina Camarasu-Pop, Tristan Glatard, Yue-Min Zhu, Isabelle E. Magnin

    E-print Network

    Paris-Sud XI, Université de

    1 Diffusion MRI simulation with the Virtual Imaging Platform Lihui Wang, Sorina Camarasu of in vivo human heart. Diffusion magnetic resonance imaging (dMRI) is one of the most potential techniques and with influence of MRI scanner noise and artifacts, it is difficult to evaluate how well the diffusion

  20. Diffusion-weighted MRI for tumour volume delineation: comparison with morphological MRI.

    PubMed

    Wolf, G; Schindler, S; Koch, A; Abolmaali, N

    2010-06-01

    Diffusion-weighted magnetic resonance imaging (dwMRI) is sensitive to tissue microstructure on the cellular level and may therefore help to define biological tumour subvolumes and add complementary information to morphology-based cancer treatment protocols and therapy monitoring. The purpose of this study was therefore to evaluate the potential of dwMRI as compared with morphological MRI (mMRI) for tumour volume delineation using a nude rat human tumour xenograft model. Sixteen tumour-bearing rats (10 H1299, six FaDu) were examined with mMRI (T2-weighted true fast imaging with steady precession (TrueFISP), T1-weighted fast low angle shot (FLASH), T2-weighted dual echo steady state (DESS)) and echo-planar dwMRI in a clinical scanner at 1.5 T. For each method, we compared tumour volume and intra- and inter-observer variability of tumour outer edge delineation (disregarding intra-tumoural structure) as well as tumour signal-to-noise ratio (SNR) and tumour-to-muscle contrast-to-noise ratio (CNR). Tumours were visualised with significantly higher SNR and CNR in dwMRI. Median tumour volumes as measured by dwMRI (3.5 cm(3)) and mMRI (TrueFISP: 3.3 cm(3); FLASH: 3.3 cm(3); DESS: 3.2 cm(3)) were not significantly different and significantly correlated. Related to partial volume effects, the intra- and inter-observer variability of dwMRI (intra/inter: 12%/12%) was larger than for mMRI (TrueFISP: 4%/4%; FLASH: 5%/5%; DESS: 5%/5%). In conclusion, dwMRI allows tumour delineation with overall volume estimation comparable with mMRI approaches but slightly higher observer variability. Thus, besides tumour outline, it may potentially supplement morphology-based therapy planning and monitoring with additional biological information. PMID:20598006

  1. Accuracy of MRI technique in measuring tendon cross-sectional area.

    PubMed

    Couppé, C; Svensson, R B; Sødring-Elbrønd, V; Hansen, P; Kjaer, M; Magnusson, S P

    2014-05-01

    Magnetic resonance imaging (MRI) has commonly been applied to determine tendon cross-sectional area (CSA) and length either to measure structural changes or to normalize mechanical measurements to stress and strain. The ability to reproduce CSA measurements on MRI images has been reported, but the accuracy in relation to actual tendon dimensions has never been investigated. The purpose of this study was to compare tendon CSA measured by MRI with that measured in vitro with the mould casting technique. The knee of a horse was MRI-scanned with 1.5 and 3 tesla, and two examiners measured the patellar tendon CSA. Thereafter, the patellar tendon of the horse was completely dissected and embedded in an alginate cast. The CSA of the embedded tendon was measured directly by optical imaging of the cast impression. 1.5 tesla grey tendon CSA and 3 tesla grey tendon CSA were 16.5% and 13.2% lower than the mould tendon CSA, respectively. Also, 3 tesla tendon CSA, based on the red-green border on the National Institute of Health (NIH) colour scale, was lower than the mould tendon CSA by 2.8%. The typical error between examiners was below 2% for all the measured CSA. The typical error between examiners was below 2% for all the measured CSA. These data show that measuring tendon CSA on the grey-scale MRI images is associated with an underestimation, but by optimizing the measurement using a 3 tesla MRI and the appropriate NIH colour scale, this underestimation could be reduced to 2.8% compared with the direct measurements on the mould. PMID:24119143

  2. Nano-thermometers with thermo-sensitive polymer grafted USPIOs behaving as positive contrast agents in low-field MRI

    NASA Astrophysics Data System (ADS)

    Hannecart, Adeline; Stanicki, Dimitri; Vander Elst, Luce; Muller, Robert N.; Lecommandoux, Sébastien; Thévenot, Julie; Bonduelle, Colin; Trotier, Aurélien; Massot, Philippe; Miraux, Sylvain; Sandre, Olivier; Laurent, Sophie

    2015-02-01

    Two commercial statistical copolymers of ethylene oxide and propylene oxide, Jeffamine® M-2005 (PEO5-st-PPO37) and M-2070 (PEO46-st-PPO13), exhibiting lower critical solution temperature (LCST) in water, were grafted onto the surface of ultra-small superparamagnetic iron oxide nanoparticles (USPIOs) using silanization and amide-bond coupling reactions. The LCSTs of the polymers in solution were measured by dynamic light scattering (DLS) and nuclear magnetic resonance (NMR). In accordance with the compositions of EO vs. PO, the transition temperature was measured to be 22 +/- 2 °C for M-2005 by both DLS and NMR, while the LCST was much higher, 52 +/- 2 °C, for M-2070 (a second transition was also detected above 80 °C by NMR in that case, ascribed to the full dehydration of chains at the molecular level). The resulting polymer-grafted USPIOs exhibit a temperature-responsive colloidal behaviour, their surface reversibly changing from hydrophilic below LCST to hydrophobic above it. This phenomenon was utilised to design thermo-sensitive contrast agents for MRI. Transverse relaxivities (r2) of the USPIO@PEO5-st-PPO37 core-shell nanoparticles were measured at 8.25, 20, 60, and 300 MHz. Nuclear magnetic resonance dispersion (NMRD) profiles, giving longitudinal relaxivities (r1) between 0.01 and 60 MHz, were acquired at temperatures ranging from 15 to 50 °C. For all tested frequencies except 300 MHz, both r1 and r2 decrease with temperature and show an inflection point at 25 °C, near the LCST. To illustrate the interest of such polymer-coated USPIOs for MRI thermometry, sample tubes were imaged on both low-field (8.25 MHz/0.194 Tesla) and high-field (300 MHz/7.05 Tesla) MRI scanners with either T1- or T2*-weighted spin echo sequences. The positive contrast on low-field MR images and the perfect linearity of the signal with a T2*-weighted sequence over the entire temperature range 15-50 °C render these LCST polymer coated USPIOs interesting positive contrast agents, also working as ``nano-thermometers''.Two commercial statistical copolymers of ethylene oxide and propylene oxide, Jeffamine® M-2005 (PEO5-st-PPO37) and M-2070 (PEO46-st-PPO13), exhibiting lower critical solution temperature (LCST) in water, were grafted onto the surface of ultra-small superparamagnetic iron oxide nanoparticles (USPIOs) using silanization and amide-bond coupling reactions. The LCSTs of the polymers in solution were measured by dynamic light scattering (DLS) and nuclear magnetic resonance (NMR). In accordance with the compositions of EO vs. PO, the transition temperature was measured to be 22 +/- 2 °C for M-2005 by both DLS and NMR, while the LCST was much higher, 52 +/- 2 °C, for M-2070 (a second transition was also detected above 80 °C by NMR in that case, ascribed to the full dehydration of chains at the molecular level). The resulting polymer-grafted USPIOs exhibit a temperature-responsive colloidal behaviour, their surface reversibly changing from hydrophilic below LCST to hydrophobic above it. This phenomenon was utilised to design thermo-sensitive contrast agents for MRI. Transverse relaxivities (r2) of the USPIO@PEO5-st-PPO37 core-shell nanoparticles were measured at 8.25, 20, 60, and 300 MHz. Nuclear magnetic resonance dispersion (NMRD) profiles, giving longitudinal relaxivities (r1) between 0.01 and 60 MHz, were acquired at temperatures ranging from 15 to 50 °C. For all tested frequencies except 300 MHz, both r1 and r2 decrease with temperature and show an inflection point at 25 °C, near the LCST. To illustrate the interest of such polymer-coated USPIOs for MRI thermometry, sample tubes were imaged on both low-field (8.25 MHz/0.194 Tesla) and high-field (300 MHz/7.05 Tesla) MRI scanners with either T1- or T2*-weighted spin echo sequences. The positive contrast on low-field MR images and the perfect linearity of the signal with a T2*-weighted sequence over the entire temperature range 15-50 °C render these LCST polymer coated USPIOs interesting positive contrast agents, also working as ``nano-thermometers''. Electronic supplement

  3. Filling and beam loading in TESLA superstructures

    Microsoft Academic Search

    M. Dohlus; H.-W. Glock; D L Hecht; U. van Rienen

    1999-01-01

    Abstract The new design of the accelerating structures for TESLA, the so-called superstructures composed,out of several mul- ticell cavities, is studied. Here a superstructure is com- posed out of four seven-cell superconducting resonators, e.g. in total 28 coupled cells. A central question is the fill- ing characteristic of the superstructure since each is fed by one coupler only. The filling

  4. Future image acquisition trends for PET/MRI.

    PubMed

    Boss, Andreas; Weiger, Markus; Wiesinger, Florian

    2015-05-01

    Hybrid PET/MRI scanners have become commercially available in the past years but are not yet widely distributed. The combination of a state-of-the-art PET with a state-of-the-art MRI scanner provides numerous potential advantages compared with the established PET/CT hybrid systems, namely, increased soft tissue contrast; functional information from MRI such as diffusion, perfusion, and blood oxygenation level-dependent techniques; true multiplanar data acquisition; and reduced radiation exposure. On the contrary, current PET/MRI technology is hampered by several shortcomings compared with PET/CT, the most important issues being how to use MR data for PET attenuation correction and the low sensitivity of MRI for small-scale pulmonary pathologies compared with high-resolution CT. Moreover, the optimal choice for hybrid PET/MRI acquisition protocols needs to be defined providing the highest possible degree of sensitivity and specificity within the constraints of the available measurement time. A multitude of new acquisition strategies of PET and MRI not only offer to overcome current obstacles of hybrid PET/MRI but also provide deeper insights into the pathophysiology of oncological, inflammatory, or degenerative diseases from the combination of molecular and functional imaging techniques. PMID:25841275

  5. Electron Scattering with Polarized Targets at TESLA

    E-print Network

    The TESLA-N Study Group; :; M. Anselmino; E. C. Aschenauer; S. Belostotski; W. Bialowons; J. Bluemlein; V. Braun; R. Brinkmann; M. Dueren; F. Ellinghaus; K. Goeke; St. Goertz; A. Gute; J. Harmsen; D. v. Harrach; R. Jakob; E. M. Kabuss; R. Kaiser; V. Korotkov; P. Kroll; E. Leader; B. Lehmann-Dronke; L. Mankiewicz; A. Meier; W. Meyer; N. Meyners; D. Mueller; P. J. Mulders; W. -D. Nowak; L. Niedermeier; K. Oganessyan; P. V. Pobilitsa; M. V. Polyakov; G. Reicherz; K. Rith; D. Ryckbosch; A. Schaefer; K. Sinram; G. v. d. Steenhoven; E. Steffens; J. Steijger; C. Weiss

    2000-11-24

    Measurements of polarized electron-nucleon scattering can be realized at the TESLA linear collider facility with projected luminosities that are about two orders of magnitude higher than those expected of other experiments at comparable energies. Longitudinally polarized electrons, accelerated as a small fraction of the total current in the e+ arm of TESLA, can be directed onto a solid state target that may be either longitudinally or transversely polarized. A large variety of polarized parton distribution and fragmentation functions can be determined with unprecedented accuracy, many of them for the first time. A main goal of the experiment is the precise measurement of the x- and Q^2-dependence of the experimentally totally unknown quark transversity distributions that will complete the information on the nucleon's quark spin structure as relevant for high energy processes. Comparing their Q^2-evolution to that of the corresponding helicity distributions constitutes an important precision test of the predictive power of QCD in the spin sector. Measuring transversity distributions and tensor charges allows access to the hitherto unmeasured chirally odd operators in QCD which are of great importance to understand the role of chiral symmetry. The possibilities of using unpolarized targets and of experiments with a real photon beam turn TESLA-N into a versatile next-generation facility at the intersection of particle and nuclear physics.

  6. [The place of MRI in the hepatic tumors].

    PubMed

    Mnif, Najla; Ellouze, Thouraya; Boubela, Tarek; Oueslati, Seddik; Hamza, Radhi

    2005-02-01

    MRI semeiology of hepatic tumors was assessed with a retrospective study of 132 patients explored between May 1998 and December 2001. MR examinations were acquired with a one Tesla operating system. All images were acquired by a T2-weighted fast spin echo MR and dynamic flash MR with Gadolinium. Hemangiomas demonstrate characteristic signs in most cases, as was described in the literature. However, adenoma, hepatocellular carcinoma and metastases have various and less specific features. PMID:15969233

  7. Image-Guided Neurosurgery with Intraoperative MRI: Update of Frameless Stereotaxy and Radicality Control

    Microsoft Academic Search

    Chrisnan R. Wirtz; Volker M. Tronnier; Mario M. Bonsanto; Michael Knauth; Andreas Staubert; Friedrich K. Albert; Stefan Kunze

    1997-01-01

    Intraoperative shifts and resulting inaccuracies have been a concern in frame-based and frameless stereotactically guided interventions, particularly in open microsurgical procedures. Trying to solve this problem, we developed a method to perform intraoperative MRI (0.2 tesla, Magnetom Open) and use intraoperatively acquired data sets to update neuronavigation. In 21 patients, intraoperative images could be used to reference navigation (mean accuracy

  8. Comparing Ensembles of Learners: Detecting Prostate Cancer from High Resolution MRI

    E-print Network

    Plotkin, Joshua B.

    Comparing Ensembles of Learners: Detecting Prostate Cancer from High Resolution MRI Anant-aided diagnosis (CAD). In this paper we investigate the performance of several state-of-the-art machine-learning methods on a CAD method for detect- ing prostatic adenocarcinoma from high resolution (4 Tesla) ex vivo

  9. Assessment of regional grey matter loss in dementia with Lewy bodies: a surface based MRI analysis

    E-print Network

    Watson, Rosie; Colloby, Sean J.; Blamire, Andrew M.; O’Brien, John T.

    2014-07-23

    participants (31 DLB, 30 AD and 33 healthy comparison subjects) underwent 3 Tesla T1-weighted MRI and completed clinical and cognitive assessments. We used the FreeSurfer analysis package to measure cortical thickness and investigated the patterns of cortical...

  10. High gain proportional rf control stability at TESLA cavities Elmar Vogel

    E-print Network

    High gain proportional rf control stability at TESLA cavities Elmar Vogel Deutsches Elektronen) based on TESLA technology. Additional control loops improve the field regulation by treating repetitive loops is desirable for the strong suppression of nonpredictive and nonrepetitive disturbances. TESLA

  11. In vivo intermolecular double-quantum imaging on a clinical 1.5 T MR scanner.

    PubMed

    Zhong, J; Chen, Z; Kwok, E

    2000-03-01

    A novel MRI method based on the intermolecular double-quantum coherence (DQC) for soft tissues is described. DQC images of human brain were obtained for the first time on a whole-body 1.5 T scanner. The combination of quantum and classical formalisms was used to characterize multiple-quantum coherences, and to aid in the design of a DQC imaging sequence. The theoretical analysis suggests that signals from the intermolecular DQCs have higher sensitivity than those from the zero-quantum coherence (ZQC) for human brain, and the sensitivity increases with increased field strength. The DQC signal may provide a new form of contrast for MRI. PMID:10725874

  12. Contributions to the LCWS99, Sitges, April 1999 TESLA Report 1999-20 Contributions to the LCWS99, Sitges, April 1999 TESLA Report 1999-20

    E-print Network

    Contributions to the LCWS99, Sitges, April 1999 TESLA Report 1999-20 #12;Contributions to the LCWS99, Sitges, April 1999 TESLA Report 1999-20 #12;Contributions to the LCWS99, Sitges, April 1999 TESLA Report 1999-20 #12;Contributions to the LCWS99, Sitges, April 1999 TESLA Report 1999-20 #12;Contributions

  13. The Design and Dimensional Analysis of a Tesla Turbine 

    E-print Network

    Richardson, Bobby Dean

    1960-01-01

    Tesla Turbine, " Rsv e M June 30, 1914, Translated by 'W. Rice. 16. Stockbridge, F. P. , "Ths Tesla Turbine, " Match 1912, pp. 543-$48. 17 ~ 18 ~ Swssey, K. M. , "Nikola Tesla, " ~198 Vol. 127, No. 3307, May 16, 1958. vi w, May 20, 1911, p. 278...THE DESIGN AND DIMENSIONAL ANALYSIS OF A TESLA TURBINE A Thesis By BOBBY DEAN RICHARDBON Submitted to the Graduate School of the Agricultural and mechanical College of Texas in psrtial fulfillment of the requirements for the degree of ASTER...

  14. Vacuum Attachment for XRF Scanner

    NASA Technical Reports Server (NTRS)

    Schramm, Harry F.; Kaiser, Bruce

    2005-01-01

    Vacuum apparatuses have been developed for increasing the range of elements that can be identified by use of x-ray fluorescent (XRF) scanners of the type mentioned in the two immediately preceding articles. As a consequence of the underlying physical principles, in the presence of air, such an XRF scanner is limited to analysis of chlorine and elements of greater atomic number. When the XRF scanner is operated in a vacuum, it extends the range of analysis to lower atomic numbers - even as far as aluminum and sodium. Hence, more elements will be available for use in XRF labeling of objects as discussed in the two preceding articles. The added benefits of the extended capabilities also have other uses for NASA. Detection of elements of low atomic number is of high interest to the aerospace community. High-strength aluminum alloys will be easily analyzed for composition. Silicon, a major contaminant in certain processes, will be detectable before the process is begun, possibly eliminating weld or adhesion problems. Exotic alloys will be evaluated for composition prior to being placed in service where lives depend on them. And in the less glamorous applications, such as bolts and fasteners, substandard products and counterfeit items will be evaluated at the receiving function and never allowed to enter the operation

  15. New directions in the design of MRI gradient coils

    Microsoft Academic Search

    Tanvir Noor Baig

    2007-01-01

    In this dissertation new designs for gradient coils are presented. The principal work is on better shielding for fringe field reduction. Fringe fields from gradient coils produce eddy currents in surrounding metal structures. Such eddy currents can degrade image quality and lead to acoustic noise. The acoustic effects are magnified for high-field Magnetic Resonance Imaging (MRI) scanners because of increased

  16. Applying Task Observations to Improve MRI Presentation Oliver Kuederle

    E-print Network

    Zhang, Richard "Hao"

    prototype. Keywords Medical imaging, user interfaces, magnetic resonance imaging, fish-eye visualization, prototyping INTRODUCTION During the process of magnetic resonance imaging (MRI), a huge tube-shaped scanner many images and up to eight volume sets may be on the light screen at the same time. However, the costs

  17. Fully Automatic Segmentation of the Brain in MRI

    Microsoft Academic Search

    M. Stella Atkins; Blair T. Mackiewich

    1998-01-01

    A robust fully automatic method for segmenting the brain from head magnetic resonance (MR) images has been developed, which works even in the presence of radio frequency (RF) inhomogeneities. It has been successful in segmenting the brain in every slice from head images acquired from several different MRI scanners, using different-resolution images and different echo sequences. The method uses an

  18. Polarized Electron-Nucleon Scattering at The TESLA-N Study-Group

    E-print Network

    DESY TESLA-N Polarized Electron-Nucleon Scattering at TESLA The TESLA-N Study-Group http://www.ifh.de/hermes/future | THE BASIC IDEA | A Polarized Fixed-Target Experiment at TESLA Basic Idea: Use one arm of the TESLA collider 0 0 1 1 01 (north arm) Magnet TESLA Main Linac TESLA­N 250 GeV Electrons Separation Building

  19. Chest MRI

    MedlinePLUS

    ... or standard x ray, MRI doesn't use radiation or pose any risk of cancer. Rarely, the contrast dye used for some chest MRIs may cause an allergic reaction or worsen kidney function in people who have ...

  20. A novel front-end chip for a human PET scanner based on monolithic detector blocks

    NASA Astrophysics Data System (ADS)

    Sarasola, I.; Rato Mendes, P.; Cuerdo, R.; García de Acilu, P.; Navarrete, J.; Cela, J. M.; Oller, J. C.; Romero, L.; Pérez, J. M.

    2011-01-01

    We are developing a positron emission tomography (PET) scanner based on avalanche photodiodes (APD), monolithic LYSO:Ce scintillator crystals and a dedicated readout chip. All these components allow operation inside a magnetic resonance imaging (MRI) scanner with the aim of building a PET/MRI hybrid imaging system for clinical human brain studies. Previous work verified the functional performance of our first chip (VATA240) based on a leading edge comparator and the principle of operation of our radiation sensors, which are capable of providing reconstructed images of positron point sources with spatial resolutions of 2.1 mm FWHM. The new VATA241 chip presented in this work has been designed with the aim of reducing the coincidence window of our final PET scanner by implementing an on-chip constant fraction discriminator (CFD), as well as providing a better robustness for its implementation in the full-scale PET scanner. Results from the characterization of the VATA241 chip are presented, together with the first results on coincidence performance, validating the new design for our application.

  1. [Intramedullary glioma. Postoperative MRI aspects].

    PubMed

    Borocco, A; Idir, A; Joubert, E; Lacroix, C; Hurth, M; Doyon, D

    1995-06-01

    MRI is the standard exploration of intramedullary tumours. Following up the patients is of prime importance to detect and treat possible recurrences at an early stage. The purpose of this paper is to specify the postoperative MRI semiology of intraspinal gliomas. During the 1986-1992 period, 47 patients operated upon in the Bicêtre hospital for primary intraspinal tumours were followed up with high-field MR (1.5 Tesla, Signa, G.E.). The retrospective visual study was carried out by two neuro-radiologists. The patients' group consisted of 24 women and 23 men aged from 15 to 67 years (mean 38 years). The tumours treated were 29 ependymomas and 18 astrocytomas. Eighty-five MRI examinations were analysed. Most of them comprised at least two planes in T1 and T2-weighted spin echo sequences with gadolinium injection, then only T1-weighted spin echo sequences after gadolinium injection (0.1 mmol/kg). The mean postoperative follow up period in the 47 patients was 32 months (range 7 to 84 months). Contrast enhancement of the spinal cord was observed in 20 cases. In the 6 patients with recurrence (5 astrocytomas, 1 malignant ependymoma) there was a segmental increase of spinal cord volume with contrast enhancement after gadolinium injection. In 3 out of these 6 patients clinical deterioration appeared later than MRI semiology. In clinically stable patients neither enhancement nor increase in spinal cord size was found in 27 cases, and enhancement alone was noted in 12 cases. There was no reliable criterion in the analysis of post gadolinium signal enhancement that could be used to differentiate recurrence from cicatricial contrast enhancement.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7629570

  2. Design of an MRI-compatible robotic stereotactic device for minimally invasive interventions in the breast.

    PubMed

    Larson, Blake T; Erdman, Arthur G; Tsekos, Nikolaos V; Yacoub, Essa; Tsekos, Panagiotis V; Koutlas, Ioannis G

    2004-08-01

    The objective of this work was to develop a robotic device to perform biopsy and therapeutic interventions in the breast with real-time magnetic resonance imaging (MRI) guidance. The device was designed to allow for (i) stabilization of the breast by compression, (ii) definition of the interventional probe trajectory by setting the height and pitch of a probe insertion apparatus, and (iii) positioning of an interventional probe by setting the depth of insertion. The apparatus is fitted with five computer-controlled degrees of freedom for delivering an interventional procedure. The entire device is constructed of MR compatible materials, i.e. nonmagnetic and non-conductive, to eliminate artifacts and distortion of the MR images. The apparatus is remotely controlled by means of ultrasonic motors and a graphical user interface, providing real-time MR-guided planning and monitoring of the operation. Joint motion measurements found probe placement in less than 50 s and sub-millimeter repeatability of the probe tip for same-direction point-to-point movements. However, backlash in the rotation joint may incur probe tip positional errors of up to 5 mm at a distance of 40 mm from the rotation axis, which may occur for women with large breasts. The imprecision caused by this backlash becomes negligible as the probe tip nears the rotation axis. Real-time MR-guidance will allow the physician to correct this error Compatibility of the device within the MR environment was successfully tested on a 4 Tesla MR human scanner PMID:15543863

  3. EUV mask particle adders during scanner exposure

    NASA Astrophysics Data System (ADS)

    Hyun, Yoonsuk; Kim, Jinsoo; Kim, Kyuyoung; Koo, Sunyoung; Kim, SeoMin; Kim, Youngsik; Lim, Changmoon; Kwak, Nohjung

    2015-03-01

    As EUV reaches high volume manufacturing, scanner source power and reticle defectivity attract a lot of attention. Keeping a EUV mask clean after mask production is as essential as producing a clean EUV mask. Even though EUV pellicle is actively investigated, we might expose EUV masks without EUV pellicle for some time. To keep clean EUV mask under pellicle-less lithography, EUV scanner cleanliness needs to meet the requirement of high volume manufacturing. In this paper, we will show the cleanliness of EUV scanners in view of mask particle adders during scanner exposure. From this we will find several tendencies of mask particle adders depending on mask environment in scanner. Further we can categorize mask particle adders, which could show the possible causes of particle adders during exposure in scanners.

  4. Magnetic Resonance Imaging (MRI)

    MedlinePLUS

    ... the MRI table. A specially trained technician (or "tech") operates the MRI machine. He or she may ... can't stay still during MRI. Sometimes MRI techs sedate teens who have trouble relaxing inside the ...

  5. Modeling of a piezoelectric micro-scanner

    Microsoft Academic Search

    A. Chaehoi; M. Begbie; D. Cornez; K. Kirk

    2008-01-01

    Micro-scanners have been widely used in many optical applications. The micro-scanner presented in this paper uses multimorph-type bending actuators to tilt a square plate mirror. This paper presents a complete analytical model of the piezoelectric micro-scanner. This theoretical model based on strength of material equations calculates the force generated by the multimorphs on the mirror, the profile of the structure

  6. Pulse Cable for TESLA Modulators Hans-Jrg Eckoldt

    E-print Network

    the modulators the switched voltage is at the 10 kV level. Via a pulse transformer the HV is achieved. DuePulse Cable for TESLA Modulators Hans-Jörg Eckoldt DESY TESLA 2000-35 #12;1 Introduction ..........................................................................................................................8 #12;1 Introduction Modulators are used to generate the pulsed power for the klystrons

  7. TESLA Report 2003-10 Studies of Electromagnetic Cascade Showers

    E-print Network

    TESLA Report 2003-10 Studies of Electromagnetic Cascade Showers Development in the TESLA Main Linac . . . . . . . . . . . . . . . . . . . . . 23 5 Simulations of the Behaviour of Field Emitted Electrons and Electromagnetic Shower Development vacuum, by quantum-mechanical tunneling of electrons from cold metal into vacuum in the presence

  8. TESLA Report 2005-06 DSP Integrated, Parameterized, FPGA Based

    E-print Network

    TESLA Report 2005-06 DSP Integrated, Parameterized, FPGA Based Cavity Simulator & Controller-Ray FEL). The controller bases on a programmable circuit Xilinx VirtexII V3000 embedded on a PCB XtremeDSP simulator, cavity controller, linear accelerators, FPGA, FPGA-DSP enhanced, VHDL, FEL, TESLA, TTF, UV

  9. Experience with superconducting cavity operation in the TESLA Test Facility

    Microsoft Academic Search

    M. Pekeler

    1999-01-01

    A description of the TESLA Test Facility, which has been set up at DESY by the TESLA Collaboration, is given. Measurements of the superconducting 9-cell cavities in vertical and horizontal test cryostats are presented, as well as the experience with the first two accelerator modules in the TTF linac. Future cavity R&D efforts are described

  10. TESLA-FEL 2006-07 Superconducting cavity driving

    E-print Network

    TESLA-FEL 2006-07 Superconducting cavity driving with FPGA controller Tomasz Czarski, Waldemar (FPGA) based system. Additionally, a single 9-cell TESLA Superconducting cavity of the FNPL Photo team using the same FPGA control system. These experiments focused attention on the general recognition

  11. HOM BEAM COUPLING MEASUREMENTS AT THE TESLA TEST FACILITY (TTF)

    Microsoft Academic Search

    G. Devanz; M. Jablonka; C. Magne; O. Napoly; Gif-sur-Yvette M. Huening; M. Wendt

    The proper damping of the higher order modes (HOM) of the TESLA superconducting accelerating cavities is a crucial requirement for the emittance preservation in the TESLA linacs. Experiments of HOM beam excitation have been performed on the accelerating modules of the TTF linac, with a recent emphasis on the measurement of the beam coupling and HOM polarization, in contrast to

  12. THE FUTURE OF THE WIRELESS ART by Nikola Tesla

    E-print Network

    Cetiner, Bedri A.

    THE FUTURE OF THE WIRELESS ART by Nikola Tesla WIRELESS TELEGRAPHY & TELEPHONY By Walter W. Massie & Charles R. Underhill, 1908, pp. 67-71. Mr. Nikola Tesla, in a recent interview by the authors impediment to the passage of a current than the whole earth. Every experiment, then, which can be performed

  13. The Design and Dimensional Analysis of a Tesla Turbine

    E-print Network

    Richardson, Bobby Dean

    1960-01-01

    THE DESIGN AND DIMENSIONAL ANALYSIS OF A TESLA TURBINE A Thesis By BOBBY DEAN RICHARDBON Submitted to the Graduate School of the Agricultural and mechanical College of Texas in psrtial fulfillment of the requirements for the degree of ASTER... . ~ ~ . ~ ~ . ~ ~ ~ ~ 24 DLSCUSSIQN OF RESULTS . ~ . . ~ . , ~. . . . . . ~ . . ~ . . ~. . . 28 CONCLUSIONS AND RECOMMENDATIONS . ~. . . . . . . ~. . . 33 BIBLIOGRAPHY ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 3 S LIST OF FIGURES Figure The Tesla...

  14. An MRI-Compatible Robotic System With Hybrid Tracking for MRI-Guided Prostate Intervention

    Microsoft Academic Search

    Axel Krieger; Iulian I. Iordachita; Peter Guion; Anurag K. Singh; Aradhana Kaushal; Cynthia Menard; Peter A. Pinto; Kevin Camphausen; Gabor Fichtinger; Louis L. Whitcomb

    2011-01-01

    This paper reports the development, evaluation, and first clinical trials of the access to the prostate tissue (APT) II system—a scanner independent system for magnetic resonance imaging (MRI)-guided transrectal prostate interventions. The sys- tem utilizes novel manipulator mechanics employing a steerable needle channel and a novel six degree-of-freedom hybrid tracking method, comprising passive fiducial tracking for initial registra- tion and

  15. 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

  16. MRI-Safe Robot for Endorectal Prostate Biopsy.

    PubMed

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

    2013-09-16

    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. A Novel MRI Marker for Prostate Brachytherapy

    SciTech Connect

    Frank, Steven J. [Department of Radiation Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX (United States)], E-mail: sjfrank@mdanderson.org; Stafford, R. Jason; Bankson, James A. [Department of Imaging Physics, University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Li Chun [Department of Experimental Diagnostic Imaging, University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Swanson, David A. [Department of Urology, University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Kudchadker, Rajat J. [Department of Radiation Physics, University of Texas M.D. Anderson Cancer Center, Houston, TX (United States); Martirosyan, Karen S. [Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX (United States)

    2008-05-01

    Purpose: Magnetic resonance imaging (MRI) is the optimal imaging modality for the prostate and surrounding critical organ structures. However, on MRI, the titanium radioactive seeds used for brachytherapy appear as black holes (negative contrast) and cannot be accurately localized. We sought to develop an encapsulated contrast agent marker (ECAM) with high-signal intensity on MRI to permit accurate localization of radioactive seeds with MRI during and after prostate brachytherapy. Methods and Materials: We investigated several agents with paramagnetic and superparamagnetic properties. The agents were injected into titanium, acrylic, and glass seeds, which were linked together in various combinations and imaged with MRI. The agent with the greatest T1-weighted signal was tested further in a canine prostate and agarose phantom. Studies were performed on a 1.5-T clinical MRI scanner. Results: The cobalt-chloride complex contrast (C4) agent with stoichiometry (CoCl{sub 2}){sub 0.8}(C{sub 2}H{sub 5}NO{sub 2}){sub 0.2} had the greatest T1-weighted signal (positive contrast) with a relaxivity ratio >1 (r{sub 2}/r{sub 1} = 1.21 {+-} 0.29). Acrylic-titanium and glass-titanium seed strands were clearly visualized with the encapsulated contrast agent marker. Conclusion: We have developed a novel ECAM that permits positive identification of the radioactive seeds used for prostate brachytherapy on MRI. Preclinical in vitro phantom studies and in vivo canine studies are needed to further optimize MRI sequencing techniques to facilitate MRI-based dosimetry.

  18. 3 tesla magnetic resonance imaging of the occipitoatlantoaxial region in the normal horse.

    PubMed

    Gutiérrez-Crespo, Beatriz; Kircher, Patrick R; Carrera, Ines

    2014-01-01

    The aim of this study was to describe the appearance of the ligamentous structures of the occipitoatlantoaxial (OAA) region in the normal horse by 3 tesla (3T) magnetic resonance imaging (MRI). The MRI images of the longitudinal odontoid ligament, tectorial membrane, dorsal and ventral atlantoaxial ligaments, dorsal atlantooccipital membrane with its reinforcing ligaments, and the lateral atlantooccipital ligaments of 10 horse cadavers were evaluated. All ligaments and membranes were identified in all planes, except for the lateral atlantooccipital ligament in the sagittal plane due to its cranioventrolateral course. All were iso to mildly hypointense to musculature of the neck in T1W with the exception of the tectorial membrane that was moderately hypointense; moderately hypointense in PD-SPIR, and markedly hypointense (isointense to cortical bone) in T2W. The PD-SPIR was the best sequence to identify all ligaments and membranes from their cranial and caudal attachments. The longitudinal odontoid ligament, ventral atlantoaxial ligament, and reinforcing bands of the dorsal atlantooccipital membrane presented a characteristic striped heterogeneous signal behavior thought to be due to fibrocartilaginous content. The remaining ligaments and membranes showed homogeneous signal intensity. Special anatomical features in this species such as the fan-shaped longitudinal odontoid ligament, absence of the transverse ligament and presence of the ventral atlantoaxial ligament were documented. Ligamentous structures that stabilize the equine OAA region were described with MRI in this study and these findings could serve as an anatomic reference for those cases where instability of this region is suspected. PMID:24219352

  19. Portable MRI

    SciTech Connect

    Espy, Michelle A. [Los Alamos National Laboratory

    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. In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla.

    PubMed

    Li, Mingyan; Jin, Jin; Zuo, Zhentao; Liu, Feng; Trakic, Adnan; Weber, Ewald; Zhuo, Yan; Xue, Rong; Crozier, Stuart

    2015-03-01

    Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) was capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo sensitivity profiles (B1(-)) become distinct at various angular positions. Therefore, sensitivity maps at other angular positions cannot be obtained by numerically rotating the acquired ones. In this work, a novel sensitivity estimation method for the RRFCA was developed and validated with human brain imaging. This method employed a library database and registration techniques to estimate coil sensitivity at an arbitrary angular position. The estimated sensitivity maps were then compared to the acquired sensitivity maps. The results indicate that the proposed method is capable of accurately estimating both magnitude and phase of sensitivity at an arbitrary angular position, which enables us to employ the rotating-SENSE algorithm to accelerate acquisition and reconstruct image. Compared to a stationary coil array with the same number of coil elements, the RRFCA was able to reconstruct images with better quality at a high reduction factor. It is hoped that the proposed rotation-dependent sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI. PMID:25635352

  1. DAPNIA/SEA-00-15 TESLA Linear Collider : Status Report

    E-print Network

    DAPNIA/SEA-00-15 TESLA Linear Collider : Status Report O. Napoly for the TESLA Collaboration CEA) October 24-28, 2000, FNAL, Batavia, IL, USA #12;#12;TESLA Linear Collider : Status Report O. Napoly for the TESLA Collaboration CEA/Saclay, DAPNIA/SEA 91191 Gif-sur-Yvette, FRANCE Abstract. We review the current

  2. TESLA Report 2003-19 THE SHORT-RANGE TRANSVERSE WAKE

    E-print Network

    TESLA Report 2003-19 THE SHORT-RANGE TRANSVERSE WAKE FUNCTION FOR TESLA ACCELERATING STRUCTURE T of a Free Electron Laser in TESLA project requires very short bunches. It results in a very long interaction calculate the short-range transverse wakefields of the TESLA linac accelerating structure. Wake fields

  3. Achievement of 35 MV/m in the Superconducting Nine-Cell Cavities for TESLA 1

    E-print Network

    Achievement of 35 MV/m in the Superconducting Nine-Cell Cavities for TESLA 1 L. Lilje2 , D. Kostin Electronvolt Superconducting Linear Accelerator TESLA is the only linear electron-positron collider project reliably achieved in the cavities of the TESLA Test Facility (TTF) accelerator. The upgrade of TESLA to 800

  4. TESLA Report No. 2000-26 September 2000 Fiber Optic Radiation Sensing Systems

    E-print Network

    TESLA Report No. 2000-26 September 2000 Fiber Optic Radiation Sensing Systems for TESLA by H, Germany F. Wulf Hahn-Meitner-Institut HMI, Germany #12;Fiber Optic Radiation Sensing Systems for TESLA of refractive index at high radiation doses 4 3. Fiber optic dosimeter types for different TESLA sections 4 3

  5. THE CRYOGENIC SYSTEM OF TESLA S. Wolff, DESY, Notkestr. 85, 22607 Hamburg, Germany

    E-print Network

    THE CRYOGENIC SYSTEM OF TESLA S. Wolff, DESY, Notkestr. 85, 22607 Hamburg, Germany for the TESLA collaboration Abstract TESLA, a 33 km long 500 GeV centre-of-mass energy superconducting linear collider The 33 km long e+ e- linear collider TESLA (Tera eV Energy Superconductiong Linear Accelerator) with 500

  6. TESLA Report 2005-05 Software Layer for SIMCON ver. 1.1.

    E-print Network

    TESLA Report 2005-05 Software Layer for SIMCON ver. 1.1. FPGA-based TESLA Cavity Control System to control FPGA-based LLRF electronic equipment for TESLA. There is presented a universal solution (SIMCON) for TESLA experiment (Test Facility) in DESY. The examples of the build and tested software

  7. PERFORMANCE STATUS OF THE RF-GUN BASED INJECTOR OF THE TESLA TEST FACILITY LINAC

    E-print Network

    PERFORMANCE STATUS OF THE RF-GUN BASED INJECTOR OF THE TESLA TEST FACILITY LINAC S. Schreiber£ for the TESLA Collaboration, DESY, 22603 Hamburg, Germany Abstract The TESLA Test Facility Linac (TTFL) at DESY uses two modules with 8 TESLA superconducting accelerat- ing structures each to accelerate an electron

  8. DESY, February 2001, TESLA Report 2001-04 Concept of the High Power e

    E-print Network

    DESY, February 2001, TESLA Report 2001-04 Concept of the High Power e± Beam Dumps for TESLA W. Bialowons, M. Maslov, M. Schmitz, V. Sytchev #12;1 Concept of the High Power e± Beam Dumps for TESLA W............................................................................................................... 19 #12;2 1 Introduction The TESLA accelerator is equipped with quite a number of extraction lines

  9. 21 CFR 882.1925 - Ultrasonic scanner calibration test block.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Ultrasonic scanner calibration test block. 882.1925 Section 882.1925 ...Ultrasonic scanner calibration test block. (a) Identification. An ultrasonic scanner calibration test block is a block of material with known...

  10. 21 CFR 882.1925 - Ultrasonic scanner calibration test block.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Ultrasonic scanner calibration test block. 882.1925 Section 882.1925 ...Ultrasonic scanner calibration test block. (a) Identification. An ultrasonic scanner calibration test block is a block of material with known...

  11. Model 6240H Galvanometer Optical Scanner

    E-print Network

    Kleinfeld, David

    inside the bearing will reduce bearing life. Note: As with any high performance motor, resonances created bearing can occur. Do not expose the scanner to extremes of temperature outside the operating limits shown in contact with the front bearing. It is located right at the front end of the scanner. Foreign material

  12. Crown angulation measured by laser scanner

    Microsoft Academic Search

    Yuta Sakurai; Yasushi Nishii; Kumi Kodaka; Kunihiko Nojima; Kenji Sueishi

    2010-01-01

    The aim of this study was to measure the crown angulation of Japanese subjects with normal occlusion using a laser scanner to minimize human error. Twenty study models with normal occlusion were scanned by laser scanner. Crown angulations of each tooth in scanned 3D dental images were measured according to Andrews’ procedure. In Andrews’ procedure, a plane was established along

  13. 3D laser scanner with gazing ability

    Microsoft Academic Search

    Tomoaki Yoshida; Kiyoshi Irie; Eiji Koyanagi; Masahiro Tomono

    2011-01-01

    This paper presents a 3D laser scanner that can gaze at an arbitrary region. By modulating the secondary rotation speed of roundly swinging 3D laser scanner, it gazes at a speciøc region and measures with high density measurement points. The proposed method uses a secondary rotation motor to control the measurement point density and no extra motor is required. The

  14. Scanner Art and Links to Physics

    ERIC Educational Resources Information Center

    Russell, David

    2005-01-01

    A photocopier or scanner can be used to produce not only the standard motion graphs of physics, but a variety of other graphs that resemble gravitational and electrical fields. This article presents a starting point for exploring scanner graphics, which brings together investigation in art and design, physics, mathematics, and information…

  15. Improved reliability in skeletal age assessment using a pediatric hand MR scanner with a 0.3T permanent magnet.

    PubMed

    Terada, Yasuhiko; Kono, Saki; Uchiumi, Tomomi; Kose, Katsumi; Miyagi, Ryo; Yamabe, Eiko; Fujinaga, Yasunari; Yoshioka, Hiroshi

    2014-01-01

    The purpose of this study was to improve the reliability and validity of skeletal age assessment using an open and compact pediatric hand magnetic resonance (MR) imaging scanner. We used such a scanner with 0.3-tesla permanent magnet to image the left hands of 88 healthy children (aged 3.4 to 15.7 years, mean 8.8 years), and 3 raters (2 orthopedic specialists and a radiologist) assessed skeletal age using those images. We measured the strength of agreement in ratings by values of weighted Cohen's ? and the proportion of cases excluded from rating because of motion artifact and inappropriate positioning. We compared the current results with those of a previous study in which 93 healthy children (aged 4.1 to 16.4 years, mean 9.7 years) were examined with an adult hand scanner. The ? values between raters exceeded 0.80, which indicates almost perfect agreement, and most were higher than those of the previous study. The proportion of cases excluded from rating because of motion artifact or inappropriate positioning was also reduced. The results indicate that use of the compact pediatric hand scanner improved the reliability and validity of skeletal age assessments. PMID:24990466

  16. Non-Destructive Testing Scanner

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Bio-Imaging Research's technology that originated in an aerospace program has come full circle with a new aerospace adaptation called the Advanced Computed Tomography Inspection System, or ACTIS. The medical version of CT scans the human body for tumors or other abnormalities, the ACTIS system finds imperfections in aerospace structures and components, such as castings, assemblies, rocket motors and nozzles. ACTIS is described by its developer as the most versatile CT scanner available for non-destructive testing applications. ACTIS is a variable geometry system. ACTIS source and detectors can be moved closer together or farther apart to optimize the geometry for different sizes of test objects. The combination of variable geometry, three sources, and focusing detectors makes ACTIS cost effective for a broad range of applications. System can scan anything from very small turbine blades to large rocket assemblies.

  17. A 3.5 Tesla Laboratory Electromagnet

    NASA Astrophysics Data System (ADS)

    Pooke, D. M.; Chamritski, V.; Gibson, S.; Fee, M.; King, T.; Staines, M. P.; Flower, N. E.; Buckley, R. G.

    2004-06-01

    We report the design and construction of a laboratory electromagnet utilizing HTS coils in an iron yoke with a magnetic flux density of 3.5 Tesla in a 50-mm air-gap. With continuing improvement in the performance of HTS "BSCCO" wire, several niche HTS magnet applications have become viable at current wire prices. In this instance, the HTS conductor confers the advantages of high field strength combined with compact size and energy efficiency, in an electromagnet of a format suitable for many materials' characterization techniques, such as vibrating-sample magnetometry, for which the current magnet will be employed. The magnet employs four HTS coils, with a total of 1.6 km of BSCCO wire, which are conduction cooled using a single-stage Gifford-McMahon cryocooler, delivering approximately 25 W of cooling power at the target 35 K operating temperature; HTS current leads are utilized to minimize heat leak to the cryogenic environment.

  18. Assessment of Safety and Interference Issues of Radio Frequency Identification Devices in 0.3 Tesla Magnetic Resonance Imaging and Computed Tomography

    PubMed Central

    Periyasamy, M.; Dhanasekaran, R.

    2014-01-01

    The objective of this study was to evaluate two issues regarding magnetic resonance imaging (MRI) including device functionality and image artifacts for the presence of radio frequency identification devices (RFID) in association with 0.3?Tesla at 12.7?MHz MRI and computed tomography (CT) scanning. Fifteen samples of RFID tags with two different sizes (wristband and ID card types) were tested. The tags were exposed to several MR-imaging conditions during MRI examination and X-rays of CT scan. Throughout the test, the tags were oriented in three different directions (axial, coronal, and sagittal) relative to MRI system in order to cover all possible situations with respect to the patient undergoing MRI and CT scanning, wearing a RFID tag on wrist. We observed that the tags did not sustain physical damage with their functionality remaining unaffected even after MRI and CT scanning, and there was no alternation in previously stored data as well. In addition, no evidence of either signal loss or artifact was seen in the acquired MR and CT images. Therefore, we can conclude that the use of this passive RFID tag is safe for a patient undergoing MRI at 0.3 T/12.7?MHz and CT Scanning. PMID:24701187

  19. Complete artifact removal for EEG recorded during continuous fMRI using independent component analysis.

    PubMed

    Mantini, D; Perrucci, M G; Cugini, S; Ferretti, A; Romani, G L; Del Gratta, C

    2007-01-15

    The simultaneous recording of EEG and fMRI is a promising method for combining the electrophysiological and hemodynamic information on cerebral dynamics. However, EEG recordings performed in the MRI scanner are contaminated by imaging, ballistocardiographic (BCG) and ocular artifacts. A number of processing techniques for the cancellation of fMRI environment disturbances exist: the most popular is averaged artifact subtraction (AAS), which performs well for the imaging artifact, but has some limitations in removing the BCG artifact, due to the variability in cardiac wave duration and shape; furthermore, no processing method to attenuate ocular artifact is currently used in EEG/fMRI, and contaminated epochs are simply rejected before signal analysis. In this work, we present a comprehensive method based on independent component analysis (ICA) for simultaneously removing BCG and ocular artifacts from the EEG recordings, as well as residual MRI contamination left by AAS. The ICA method has been tested on event-related potentials (ERPs) obtained from a visual oddball paradigm: it is very effective in attenuating artifacts in order to reconstruct clear brain signals from EEG acquired in the MRI scanner. It performs significantly better than the AAS method in removing the BCG artifact. Furthermore, since ocular artifacts can be completely suppressed, a larger number of trials is available for analysis. A comparison of ERPs inside the magnetic environment with those obtained out of the MRI scanner confirms that no systematic bias in the ERP waveform is produced by the ICA method. PMID:17112747

  20. TESLA Report 2006-09 FPGA based, modular, configurable controller

    E-print Network

    TESLA Report 2006-09 1 FPGA based, modular, configurable controller with fast synchronous optical controller equipped with programmable VLSI FPGA circuit, universal expansion modules PMC, synchronous systems, programmable circuits, FPGA, behavioral programming with parameterization, VHDL, optical multi

  1. NVIDIA Tesla: A Unified Graphics and Computing Architecture

    Microsoft Academic Search

    Erik Lindholm; John Nickolls; Stuart F. Oberman; John Montrym

    2008-01-01

    To enable flexible, programmable graphics and high-performance computing, NVIDIA has developed the Tesla scalable unified graphics and parallel computing architecture. Its scalable parallel array of processors is massively multithreaded and programmable in C or via graphics APIs.

  2. Alternative IR geometries for TESLA with a small crossing angle

    E-print Network

    R. Appleby; D. Angal-Kalinin; P. Bambade; B. Mouton; O. Napoly; J. Payet; the TESLA Collaboration

    2005-01-24

    The formulation of hybrid crossing angle schemes has been a recent development of the TESLA collision geometry debate. Here we report on two such schemes, characterised by either a small vertical or horizontal beam crossing angle.

  3. OPERATING EXPERIENCE WITH SUPERCONDUCTING CAVITIES AT THE TESLA TEST FACILITY

    Microsoft Academic Search

    Wolf-Dietrich Möller

    A description of the TESLA Test Facility (1), which has been set up at DESY by the T eV Energy Superconducting Accelerator (TESLA) (2) collaboration, will be given as it is now after five years of installation and operation. The experience with the first three modules, each containing 8 superconducting 9-cell cavities, installed and operated in the TTF-linac will be

  4. Play the MRI Game

    MedlinePLUS

    ... Teachers' Questionnaire MRI Play MRI the Magnetic Miracle Game About the game In the MRI imaging technique, strong magnets and ... last will in Paris. Play the Blood Typing Game Try to save some patients and learn about ...

  5. Web server scanner: scanning on IIS CGI and HTTP

    Microsoft Academic Search

    Siti Rahayu Selamat

    2003-01-01

    This paper explains about the design and implementation of Web server scanner. The scanner detected the security weaknesses on IIS, CGI and HTTP. A report is produced for audit log purposes to help decrease the security weaknesses. In Internet security, no hacking tool is more celebrated than the scanner. The scanner is a program that automatically detects security weaknesses in

  6. A Laser Range Scanner Designed for Minimum Calibration Complexity

    Microsoft Academic Search

    James Davis; Xing Chen

    2001-01-01

    Laser range scanners are a popular method for acquiring three-dimensional geometry due to their accuracy and robustness. Maximizing scanner accuracy while minimizing engineering costs is a key challenge to future scanner designs. Engineering costs arise from both expensive components and difficult calibration requirements. We propose a two camera range scanner design, specifically chosen to minimize calibration complexity and cost. This

  7. Noise in 3D Laser Range Scanner Data Xianfang Sun

    E-print Network

    Martin, Ralph R.

    Noise in 3D Laser Range Scanner Data Xianfang Sun Cardiff University, UK Beihang University, China denoising algorithms are required to effectively remove real scanner noise. Keywords: 3D laser scanner, 13, 20, 26, 27]. However, real 3D laser scanner noise is, in practice, not quite Gaussian according

  8. Practical issues and development of underwater 3D laser scanners

    Microsoft Academic Search

    JunJie Liu; Anthony Jakas; Ala Al-Obaidi; Yonghuai Liu

    2010-01-01

    Nowadays, 3D laser scanners are widely used in reverse engineering, industrial design, prototyping, quality control etc. Most of these scanners operate in air. Theoretically, this technology can be extended for the development of 3D laser scanners that work in water. In this paper, we describe the development and practical issues of 3D laser scanners required for applications such as underwater

  9. Noise Analysis and Synthesis for 3D Laser Depth Scanners

    E-print Network

    Martin, Ralph R.

    Noise Analysis and Synthesis for 3D Laser Depth Scanners Xianfang Sun a,b,, Paul L. Rosin a , Ralph laser scanner, scanner noise analysis, noise modeling, 3D surface denoising 1 Introduction Surface mesh models built using data obtained from 3D laser depth scanners necessarily contain some noise. To remove

  10. Hand-held optical fuel pin scanner

    DOEpatents

    Kirchner, T.L.; Powers, H.G.

    1980-12-07

    An optical scanner for indicia arranged in a focal plane perpendicular to an optical system including a rotatable dove prism. The dove prism transmits a rotating image to a stationary photodiode array.

  11. Women are more strongly affected by dizziness in static magnetic fields of magnetic resonance imaging scanners.

    PubMed

    Heinrich, Angela; Szostek, Anne; Meyer, Patric; Reinhard, Iris; Gilles, Maria; Paslakis, Georgios; Rauschenberg, Jaane; Gröbner, Jens; Semmler, Wolfhard; Deuschle, Michael; Meyer-Lindenberg, Andreas; Flor, Herta; Nees, Frauke

    2014-10-01

    Increasing field strengths in MRI necessitate the examination of potential side effects. Previously reported results have been contradictory, possibly caused by imbalanced samples. We aimed to examine whether special groups of people are more prone to develop side effects that might have led to contradictory results in previous studies. We examined the occurrence of sensory side effects in static magnetic fields of MRI scanners of 1.5, 3, and 7?T and a mock scanner in 41 healthy participants. The contribution of field strength, sex, age, and attention to bodily processes, and stress hormone levels to the sensation of dizziness was examined in separate univariate analyses and in a joint analysis that included all variables. Field strength and sex were significant factors in the joint analysis (P=0.001), with women being more strongly affected than men by dizziness in higher static magnetic fields. This effect was not mediated by the other variables such as attention to bodily symptoms or stress hormones. Further research needs to elucidate the underlying factors of increased dizziness in women in static magnetic fields in MRI. We hypothesize that imbalanced samples of earlier studies might be one reason for previous contradictory results on the side effects of static magnetic fields. PMID:25089803

  12. From PET detectors to PET scanners.

    PubMed

    Humm, John L; Rosenfeld, Anatoly; Del Guerra, Alberto

    2003-11-01

    This review describes the properties of available and emerging radiation detector and read-out technologies and discusses how they may affect PET scanner performance. After a general introduction, there is a section in which the physical properties of several different detector scintillators are compared. This is followed by a discussion of recent advances in read-out electronics. Finally, the physical performance of the several commercial PET scanners is summarized. PMID:14579100

  13. Eddy currents in a transverse MRI gradient coil. J.M.B. Kroot, S.J.L. van Eijndhoven, A.A.F. van de Ven

    E-print Network

    Eindhoven, Technische Universiteit

    Eddy currents in a transverse MRI gradient coil. J.M.B. Kroot, S.J.L. van Eijndhoven, A.A.F. van de, 2007 Abstract A transverse gradient coil (x- or y-coil) of an MRI-scanner is modeled as a network gradient coils to induce magnetic field gradients for the spatial differentiation of the signals emitted

  14. BOLD fMRI activation induced by vagus nerve stimulation in seizure patients

    Microsoft Academic Search

    W-C Liu; K Mosier; A J Kalnin; D Marks

    2003-01-01

    Objective: To identify the cerebral activated regions associated with the vagus nerve stimulation in epilepsy patients.Design: Blood oxygenation level dependent functional magnetic resonance imaging (BOLD fMRI) was employed to detect areas of the brain activated by vagus nerve stimulation in five patients with documented complex partial seizures.Methods: Functional MRI was done on a GE 1.5T Echospeed horizon scanner. Before each

  15. 3-Tesla magnetic resonance imaging improves the prostate cancer detection rate in transrectral ultrasound-guided biopsy

    PubMed Central

    CHEN, JIE; YI, XIAO-LEI; JIANG, LI-XIN; WANG, REN; ZHAO, JUN-GONG; LI, YUE-HUA; HU, BING

    2015-01-01

    The detection rate of prostate cancer (PCa) using traditional biopsy guided by transrectal ultrasound (TRUS) is not satisfactory. The aim of this study was to determine the utility of 3-Tesla (3-T) magnetic resonance imaging (MRI) prior to TRUS-guided prostate biopsy and to investigate which subgroup of patients had the most evident improvement in PCa detection rate. A total of 420 patients underwent 3-T MRI examination prior to the first prostate biopsy and the positions of suspicious areas were recorded respectively. TRUS-guided biopsy regimes included systematic 12-core biopsy and targeted biopsy identified by MRI. Patients were divided into subgroups according to their serum prostate-specific antigen (PSA) levels, PSA density (PSAD), prostate volume, TRUS findings and digital rectal examination (DRE) findings. The ability of MRI to improve the cancer detection rate was evaluated. The biopsy positive rate of PCa was 41.2% (173/420), and 41 of the 173 (23.7%) patients were detected only by targeted biopsy in the MRI-suspicious area. Compared with the systematic biopsy, the positive rate was significantly improved by the additional targeted biopsy (P=0.0033). The highest improvement of detection rate was observed in patients with a PSA level of 4–10 ng/ml, PSAD of 0.12–0.20 ng/ml2, prostate volume >50 ml, negative TRUS findings and negative DRE findings (P<0.05). Therefore, it is considered that 3-T MRI examination could improve the PCa detection rate on first biopsy, particularly in patients with a PSA level of 4–10 ng/ml, PSAD of 0.12–0.20 ng/ml2, prostate volume of >50 ml, negative TRUS findings and negative DRE findings. PMID:25452804

  16. The Added Diagnostic Value of Dynamic Contrast-Enhanced MRI at 3.0 T in Nonpalpable Breast Lesions

    PubMed Central

    Merckel, Laura G.; Verkooijen, Helena M.; Peters, Nicky H. G. M.; Mann, Ritse M.; Veldhuis, Wouter B.; Storm, Remmert K.; Weits, Teun; Duvivier, Katya M.; van Dalen, Thijs; Mali, Willem P. Th. M.; Peeters, Petra H. M.; van den Bosch, Maurice A. A. J.

    2014-01-01

    Objective To investigate the added diagnostic value of 3.0 Tesla breast MRI over conventional breast imaging in the diagnosis of in situ and invasive breast cancer and to explore the role of routine versus expert reading. Materials and Methods We evaluated MRI scans of patients with nonpalpable BI-RADS 3–5 lesions who underwent dynamic contrast-enhanced 3.0 Tesla breast MRI. Initially, MRI scans were read by radiologists in a routine clinical setting. All histologically confirmed index lesions were re-evaluated by two dedicated breast radiologists. Sensitivity and specificity for the three MRI readings were determined, and the diagnostic value of breast MRI in addition to conventional imaging was assessed. Interobserver reliability between the three readings was evaluated. Results MRI examinations of 207 patients were analyzed. Seventy-eight of 207 (37.7%) patients had a malignant lesion, of which 33 (42.3%) patients had pure DCIS and 45 (57.7%) invasive breast cancer. Sensitivity of breast MRI was 66.7% during routine, and 89.3% and 94.7% during expert reading. Specificity was 77.5% in the routine setting, and 61.0% and 33.3% during expert reading. In the routine setting, MRI provided additional diagnostic information over clinical information and conventional imaging, as the Area Under the ROC Curve increased from 0.76 to 0.81. Expert MRI reading was associated with a stronger improvement of the AUC to 0.87. Interobserver reliability between the three MRI readings was fair and moderate. Conclusions 3.0 T breast MRI of nonpalpable breast lesions is of added diagnostic value for the diagnosis of in situ and invasive breast cancer. PMID:24713637

  17. Automatic Brachytherapy Seed Placement Under MRI Guidance

    PubMed Central

    Patriciu, Alexandru; Petrisor, Doru; Muntener, Michael; Mazilu, Dumitru; Schär, Michael; Stoianovici, Dan

    2011-01-01

    The paper presents a robotic method of performing low dose rate prostate brachytherapy under magnetic resonance imaging (MRI) guidance. The design and operation of a fully automated MR compatible seed injector is presented. This is used with the MrBot robot for transperineal percutaneous prostate access. A new image-registration marker and algorithms are also presented. The system is integrated and tested with a 3T MRI scanner. Tests compare three different registration methods, assess the precision of performing automated seed deployment, and use the seeds to assess the accuracy of needle targeting under image guidance. Under the ideal conditions of the in vitro experiments, results show outstanding image-guided needle and seed placement accuracy. PMID:17694871

  18. Solid targetry at the TESLA Accelerator Installation

    NASA Astrophysics Data System (ADS)

    ?omor, J. J.; Dakovi?, M.; Raj?evi?, M.; Košuti?, ?.; Spasi?, M.; Vidovi?, A.; ?uri?i?, J.; Nedeljkovi?, N.

    2002-03-01

    According to the concept of the TESLA Accelerator Installation, the channel for production of radioisotopes has to routinely produce 201Tl, 111In, 67Ga, 123I and 18F, and a number of other radionuclides for experimental purposes. The production of 123I and 18F will be performed in dedicated, commercial target stations, while a versatile solid target irradiation system is designed for the routine and experimental production of all other radioisotopes. The solid target station is designed to accept targets for both the 7° and 90° irradiation geometry. The targets used for the routine production will be prepared by electroplating on a silver substrate. They can be irradiated with a 1.5 kW beam using the 7° geometry. The cooling of these targets is enhanced by fins on the back of the silver substrate designed so that the highest temperature on the surface of the target does not exceed 110°C. The irradiation procedures will conform to the GMP requirements for the production of radiopharmaceuticals. The irradiated targets will be transported directly into the appropriate hot cell for radiochemical processing. All cells will be equipped with a target dissolution unit for etching the irradiated, electroplated film. After decontamination and sufficient cooling down, these targets will be reused several times.

  19. 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

  20. Two-Slotted Surface Coil Array for Magnetic Resonance Imaging at 4 Tesla

    SciTech Connect

    Solis, S. E. [Medical Department, Brookhaven National Laboratory, Upton, N.Y. 11973 (United States); Centro de Investigacion e Instrumentacion e Imagenologia Medica, Universidad Autonoma Metropolitana Iztapalapa, Mexico, DF 09340 (Mexico); Hernandez, J. A.; Rodriguez, A. O. [Centro de Investigacion e Instrumentacion e Imagenologia Medica, Universidad Autonoma Metropolitana Iztapalapa, Mexico, DF 09340 (Mexico); Tomasi, D. [Medical Department, Brookhaven National Laboratory, Upton, N.Y. 11973 (United States)

    2008-08-11

    Arrays of antennas have been widely accepted for magnetic resonance imaging applications due to their high signal-to-noise ratio (SNR) over large volumes of interest. A new surface coil based on the magnetron tube and called slotted surface coil, has been recently introduced by our group. This coil design experimentally demonstrated a significant improvement over the circular-shaped coil when used in the receive-only mode. The slotted coils formed a two-sheet structure with a 90 deg. separation and each coil had 6 circular slots. Numerical simulations were performed using the finite element method for this coil design to study the behaviour of the array magnetic field. Then, we developed a two-coil array for brain magnetic resonance imaging to be operated at the resonant frequency of 170 MHz in the transceiver mode. Phantom images were acquired with our coil array and standard pulse sequences on a research-dedicated 4 Tesla scanner. Numerical simulations demonstrated that electromagnetic interaction between the coil elements is negligible, and that the magnetic field showed a good uniformity. In vitro images showed the feasibility of this coil array for standard pulses for high field magnetic resonance imaging.

  1. Two-Slotted Surface Coil Array for Magnetic Resonance Imaging at 4 Tesla

    NASA Astrophysics Data System (ADS)

    Solís, S. E.; Hernández, J. A.; Tomasi, D.; Rodríguez, A. O.

    2008-08-01

    Arrays of antennas have been widely accepted for magnetic resonance imaging applications due to their high signal-to-noise ratio (SNR) over large volumes of interest. A new surface coil based on the magnetron tube and called slotted surface coil, has been recently introduced by our group. This coil design experimentally demonstrated a significant improvement over the circular-shaped coil when used in the receive-only mode. The slotted coils formed a two-sheet structure with a 90° separation and each coil had 6 circular slots. Numerical simulations were performed using the finite element method for this coil design to study the behaviour of the array magnetic field. Then, we developed a two-coil array for brain magnetic resonance imaging to be operated at the resonant frequency of 170 MHz in the transceiver mode. Phantom images were acquired with our coil array and standard pulse sequences on a research-dedicated 4 Tesla scanner. Numerical simulations demonstrated that electromagnetic interaction between the coil elements is negligible, and that the magnetic field showed a good uniformity. In vitro images showed the feasibility of this coil array for standard pulses for high field magnetic resonance imaging.

  2. Report on the TESLA Engineering Study/Review

    SciTech Connect

    Cornuelle, John C.

    2002-08-30

    In March, 2001, the TESLA Collaboration published its Technical Design Report (TDR, see references and links in Appendix), the first sentence of which stated ''...TESLA (TeV-Energy Superconducting Linear Collider) (will be) a superconducting electron-positron collider of initially 500 GeV total energy, extendable to 800 GeV, and an integrated X-ray laser laboratory.'' The TDR included cost and manpower estimates for a 500 GeV e{sup +}e{sup -} collider (250 on 250 GeV) based on superconducting RF cavity technology. This was submitted as a proposal to the German government. The government asked the German Science Council to evaluate this proposal. The recommendation from this body is anticipated to be available by November 2002. The government has indicated that it will react on this recommendation by mid-2003. In June 2001, Steve Holmes, Fermilab's Associate Director for Accelerators, commissioned Helen Edwards and Peter Garbincius to organize a study of the TESLA Technical Design Report and the associated cost and manpower estimates. Since the elements and methodology used in producing the TESLA cost estimate were somewhat different from those used in preparing similar estimates for projects within the U.S., it is important to understand the similarities, differences, and equivalences between the TESLA estimate and U.S. cost estimates. In particular, the project cost estimate includes only purchased equipment, materials, and services, but not manpower from DESY or other TESLA collaborating institutions, which is listed separately. It does not include the R&D on the TESLA Test Facility (TTF) nor the costs of preparing the TDR nor the costs of performing the conceptual studies so far. The manpower for the pre-operations commissioning program (up to beam) is included in the estimate, but not the electrical power or liquid Nitrogen (for initial cooldown of the cryogenics plant). There is no inclusion of any contingency or management reserve. If the U.S. were to become involved with the TESLA project, either as a collaborator for an LC in Germany, or as host country for TESLA in the U.S., it is important to begin to understand the scope and technical details of the project, what R&D still needs to be done, and how the U.S. can contribute. The charge for this study is included in the Appendix to this report.

  3. Optimized magnetic resonance diffusion protocol for ex-vivo whole human brain imaging with a clinical scanner

    NASA Astrophysics Data System (ADS)

    Scherrer, Benoit; Afacan, Onur; Stamm, Aymeric; Singh, Jolene; Warfield, Simon K.

    2015-03-01

    Diffusion-weighted magnetic resonance imaging (DW-MRI) provides a novel insight into the brain to facilitate our understanding of the brain connectivity and microstructure. While in-vivo DW-MRI enables imaging of living patients and longitudinal studies of brain changes, post-mortem ex-vivo DW-MRI has numerous advantages. Ex-vivo imaging benefits from greater resolution and sensitivity due to the lack of imaging time constraints; the use of tighter fitting coils; and the lack of movement artifacts. This allows characterization of normal and abnormal tissues with unprecedented resolution and sensitivity, facilitating our ability to investigate anatomical structures that are inaccessible in-vivo. This also offers the opportunity to develop today novel imaging biomarkers that will, with tomorrow's MR technology, enable improved in-vivo assessment of the risk of disease in an individual. Post-mortem studies, however, generally rely on the fixation of specimen to inhibit tissue decay which starts as soon as tissue is deprived from its blood supply. Unfortunately, fixation of tissues substantially alters tissue diffusivity profiles. In addition, ex-vivo DW-MRI requires particular care when packaging the specimen because the presence of microscopic air bubbles gives rise to geometric and intensity image distortion. In this work, we considered the specific requirements of post-mortem imaging and designed an optimized protocol for ex-vivo whole brain DW-MRI using a human clinical 3T scanner. Human clinical 3T scanners are available to a large number of researchers and, unlike most animal scanners, have a bore diameter large enough to image a whole human brain. Our optimized protocol will facilitate widespread ex-vivo investigations of large specimen.

  4. Magnetic shielding for MRI superconducting magnets

    SciTech Connect

    Ishiyama, A.; Hirooka, H. (Dept. of Electrical Engineering, Waseda Univ., Tokyo (JP))

    1991-03-01

    This paper describes an optimal design of a highly homogeneous superconducting coil system with magnetic shielding for Magnetic Resonance Imaging (MRI). The presented optimal design method; which is originally proposed in our earlier papers, is a combination of the hybrid finite element and boundary element method for analysis of an axially symmetric nonlinear open boundary magnetic field problem, and the mathematical programming method for solving the corresponding optimization problem. In this paper, the multi-objective goal programming method and the nonlinear least squares method have been adopted. The optimal design results of 1.5- and 4.7-Tesla-magnet systems with different types of magnetic shielding for whole-body imaging are compared and the advantages of a combination of active and yoke shields are shown.

  5. Multi-institutional validation of a novel textural analysis tool for preoperative stratification of suspected thyroid tumors on diffusion weighted MRI

    E-print Network

    Brown, Anna M.; Nagala, Sidhartha; McLean, Mary A.; Lu, Yonggang; Scoffings, Daniel; Apte, Aditya; Gonen, Mithat; Stambuk, Hilda E.; Shaha, Ashok R.; Tuttle, R. Michael; Deasy, Joseph O.; Priest, Andrew N.; Jani, Piyush; Shukla-Dave, Amita; Griffiths, John

    2015-05-20

    of texture-based pattern classification: a phan- tom study. Invest Radiol 2009;44:405–411. 30. Mayerhoefer M, Schima W. Texture-based classification of focal liver lesions on MRI at 3.0 Tesla: a feasibility study in cysts and hemangi- omas. J Magn Reson...

  6. Detection of Entorhinal Layer II Using Tesla Magnetic Resonance Imaging

    E-print Network

    Fischl, Bruce

    scanner using a solenoid coil. In 70 and 100 m isotropic data, the entorhinal islands were clearly visible lobe were robustly detected using the magnetic resonance images. Our ex vivo results could break ground used a human whole-body 7T scanner, obtaining images with 100 m isotropic voxels, and were able

  7. SEX DIFFERENCES IN THE HUMAN CONNECTOME: 4-TESLA HIGH ANGULAR RESOLUTION DIFFUSION IMAGING (HARDI)

    E-print Network

    Thompson, Paul

    SEX DIFFERENCES IN THE HUMAN CONNECTOME: 4-TESLA HIGH ANGULAR RESOLUTION DIFFUSION IMAGING (HARDI diffusion imaging at 4 Tesla, we scanned 234 young adult twins and siblings (mean age: 23.4 ± 2.0 SD years

  8. LEFT VERSUS RIGHT HEMISPHERE DIFFERENCES IN BRAIN CONNECTIVITY: 4-TESLA HARDI TRACTOGRAPHY IN 569 TWINS

    E-print Network

    Thompson, Paul

    LEFT VERSUS RIGHT HEMISPHERE DIFFERENCES IN BRAIN CONNECTIVITY: 4-TESLA HARDI TRACTOGRAPHY IN 569) and 112 adolescents (age 12-16) with 4-Tesla 105-gradient high- angular resolution diffusion imaging. We

  9. Comparing post-operative human breast specimen radiograph and MRI in lesion margin and volume assessment.

    PubMed

    Abe, Hiroyuki; Shimauchi, Akiko; Fan, Xiaobing; River, Jonathan N; Sattar, Husain; Mueller, Jeffrey; Karczmar, Gregory S; Newstead, Gillian M

    2012-01-01

    The purpose of this research is to evaluate the potential for identifying malignant breast lesions and their margins on large specimen MRI, in comparison to specimen radiography and clinical dynamic contrast enhanced MRI (DCE-MRI). Breast specimens were imaged with an MR scanner immediately after surgery, with an IRB-approved protocol and with the patients' informed consent. Specimen sizes were at least 5 cm in diameter and approximately 1 to 4 cm thick. Coronal and axial gradient echo MR images without fat suppression were acquired over the whole specimens using a 9.4T animal scanner. Findings on specimen MRI were compared with findings on specimen radiograph, and their volumes were compared with measurements obtained from clinical DCE-MRI. The results showed that invasive ductal carcinoma (IDC) lesions were easily identified using MRI and the margins were clearly distinguishable from nearby tissue. However, ductal carcinoma in situ (DCIS) lesions were not clearly discernible and were diffused with poorly defined margins on MRI. Calcifications associated with DCIS were visualized in all specimens on specimen radiograph. There is a strong correlation between the maximum diameter of lesions as measured by radiograph and MRI (r = 0.93), as well as the maximum diameter measured by pathology and radiograph/MRI (r>0.75). The volumes of IDC measured on specimen MRI were slightly smaller than those measured on DCE-MRI. Imaging of excised human breast lumpectomy specimens with high magnetic field MRI provides promising results for improvements in lesion identification and margin localization for IDC. However, there are technical challenges in visualization of DCIS lesions. Improvements in specimen imaging are important, as they will provide additional information to standard radiographic analysis. PMID:23149773

  10. Precise Indoor Localization for Mobile Laser Scanner

    NASA Astrophysics Data System (ADS)

    Kaijaluoto, R.; Hyyppä, A.

    2015-05-01

    Accurate 3D data is of high importance for indoor modeling for various applications in construction, engineering and cultural heritage documentation. For the lack of GNSS signals hampers use of kinematic platforms indoors, TLS is currently the most accurate and precise method for collecting such a data. Due to its static single view point data collection, excessive time and data redundancy are needed for integrity and coverage of data. However, localization methods with affordable scanners are used for solving mobile platform pose problem. The aim of this study was to investigate what level of trajectory accuracies can be achieved with high quality sensors and freely available state of the art planar SLAM algorithms, and how well this trajectory translates to a point cloud collected with a secondary scanner. In this study high precision laser scanners were used with a novel way to combine the strengths of two SLAM algorithms into functional method for precise localization. We collected five datasets using Slammer platform with two laser scanners, and processed them with altogether 20 different parameter sets. The results were validated against TLS reference. The results show increasing scan frequency improves the trajectory, reaching 20 mm RMSE levels for the best performing parameter sets. Further analysis of the 3D point cloud showed good agreement with TLS reference with 17 mm positional RMSE. With precision scanners the obtained point cloud allows for high level of detail data for indoor modeling with accuracies close to TLS at best with vastly improved data collection efficiency.

  11. Cognition for robot scanner based remote welding

    NASA Astrophysics Data System (ADS)

    Thombansen, U.; Ungers, Michael

    2014-02-01

    The effort for reduced cycle times in manufacturing has supported the development of remote welding systems which use a combination of scanners for beam delivery and robots for scanner positioning. Herein, close coupling of both motions requires a precise command of the robot trajectory and the scanner positioning to end up with a combined beam delivery. Especially the path precision of the robot plays a vital role in this kinematic chain. In this paper, a sensor system is being presented which allows tracking the motion of the laser beam against the work piece. It is based on a camera system which is coaxially connected to the scanner thus observing the relative motion of the laser beam relative to the work piece. The acquired images are processed with computer vision algorithms from the field of motion detection. The suitability of the algorithms is being demonstrated with a motion tracking tool which visualizes the homogeneity of the tracking result. The reported solution adds cognitive capabilities to manufacturing systems for robot scanner based materials processing. It allows evaluation of the relative motion between work piece and the laser beam. Moreover, the system can be used to adapt system programming during set-up of a manufacturing task or to evaluate the functionality of a manufacturing system during production. The presented sensor system will assist in optimizing manufacturing processes.

  12. LANSCE-R WIRE-SCANNER SYSTEM

    SciTech Connect

    Gruchalla, Michael E. [Los Alamos National Laboratory

    2011-01-01

    The National Instruments cRIO platform is used for the new LANSCE-R wire-scanner systems. All wire-scanner electronics are integrated into a single BiRa BiRIO 4U cRIO chassis specifically designed for the cRIO crate and all interface electronics. The BiRIO chassis, actuator and LabVIEW VIs provide a complete wire-scanner system integrated with EPICS. The new wire-scanner chassis includes an 8-slot cRIO crate with Virtex-5 LX 110 FPGA and Power-PC real-time controller, the LANL-developed cRIO 2-axis wire-sensor analog interface module (AFE), NI9222 cRIO 4-channel 16-bit digitizer, cRIO resolver demodulator, cRIO event receiver, front-panel touch panel display, motor driver, and all necessary software, interface wiring, connectors and ancillary components. This wirescanner system provides a complete, turn-key, 2-axis wire-scanner system including 2-channel low-noise sensewire interface with variable DC wire bias and wireintegrity monitor, 16-bit signal digitizers, actuator motor drive and control, actuator position sensing, limit-switch interfaces, event receiver, LabVIEW and EPICS interface, and both remote operation and full stand-alone operation using the touch panel.

  13. 21 CFR 862.2400 - Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical...Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical...densitometer/scanner (integrating, reflectance, thin-layer...

  14. 21 CFR 862.2400 - Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical...Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical...densitometer/scanner (integrating, reflectance, thin-layer...

  15. 21 CFR 862.2400 - Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical...Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical...densitometer/scanner (integrating, reflectance, thin-layer...

  16. 21 CFR 862.2400 - Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical...Densitometer/scanner (integrating, reflectance, TLC, or radiochromatogram) for clinical...densitometer/scanner (integrating, reflectance, thin-layer...

  17. Open Access Series of Imaging Studies: Longitudinal MRI Data in Nondemented and Demented Older Adults

    Microsoft Academic Search

    Daniel S. Marcus; Anthony F. Fotenos; John G. Csernansky; John C. Morris; Randy L. Buckner

    2010-01-01

    The Open Access Series of Imaging Studies is a series of neuroimaging data sets that are publicly available for study and analysis. The present MRI data set consists of a longitudinal collection of 150 subjects aged 60 to 96 years all acquired on the same scanner using identical sequences. Each subject was scanned on two or more visits, separated by

  18. Modal analysis and acoustic noise characterization of a 4T MRI gradient coil insert

    Microsoft Academic Search

    C. K. Mechefske; G. Yao; W. Li; C. Gazdzinski; B. K. Rutt

    2004-01-01

    High magnetic field strength and high-speed gradient coil current switching are combining to yield high acoustic sound pressure levels (SPL) in and around magnetic resonance imaging (MRI) scanners. Studies have already been conducted that partially characterize this sound field, and various methods have been investigated in an attempt to attenuate the noise generated. To more fully characterize and predict the

  19. Vibration analysis and measurement of a gradient coil insert in a 4 T MRI

    Microsoft Academic Search

    G. Z. Yao; Chris K. Mechefske; Brian K. Rutt

    2005-01-01

    High speed switching of current in gradient coils within high magnetic field strength Magnetic Resonance Imaging (MRI) scanners may result in high acoustic sound pressure levels in and around these machines. Many studies have already been conducted to characterize the sound field in and around MRIs and various methods have been investigated to attenuate the noise generated. To characterize the

  20. Short Communication Vibration analysis and measurement of a gradient coil insert in a 4 T MRI

    Microsoft Academic Search

    G. Z. Yao; Chris K. Mechefske; Brian K. Rutt

    High speed switching of current in gradient coils within high magnetic field strength Magnetic Resonance Imaging (MRI) scanners may result in high acoustic sound pressure levels in and around these machines. Many studies have already been conducted to characterize the sound field in and around MRIs and various methods have been investigated to attenuate the noise generated. To characterize the

  1. Quantitative Clinical Evaluation of a Simultaneous PETI MRI Breast Imaging System

    SciTech Connect

    Schlyer D. J.; Schlyer, D.J.

    2013-04-03

    A prototype simultaneous PET-MRI breast scanner has been developed for conducting clinical studies with the goal of obtaining high resolution anatomical and functional information in the same scan which can lead to faster and better diagnosis, reduction of unwanted biopsies, and better patient care.

  2. A Pixel Vertex Tracker for the TESLA Detector

    E-print Network

    M. Battaglia; M. Caccia; S. Borghi; R. Campagnolo; K. Domanski; P. Grabiec; B. Jaroszewicz; J. Marczewski; D. Tomaszewski; W. Kucewicz; A. Zalewska; K. Tammi

    2001-02-23

    In order to fully exploit the physics potential of a e+e- linear collider, such as TESLA, a Vertex Tracker providing high resolution track reconstruction is required. Hybrid Silicon pixel sensors are an attractive sensor technology option due to their read-out speed and radiation hardness, favoured in the high rate TESLA environment, but have been so far limited by the achievable single point space resolution. A novel layout of pixel detectors with interleaved cells to improve their spatial resolution is introduced and the results of the characterisation of a first set of test structures are discussed. In this note, a conceptual design of the TESLA Vertex Tracker, based on hybrid pixel sensors is presented

  3. CT densitometry of the lungs: Scanner performance

    SciTech Connect

    Kemerink, G.J.; Lamers, R.J.S.; Thelissen, G.R.P.; Engelshoven, J.M.A. van [University Hospital, Maastricht (Netherlands)] [University Hospital, Maastricht (Netherlands)

    1996-01-01

    Our goal was to establish the reproducibility and accuracy of the CT scanner in densitometry of the lungs. Scanner stability was assessed by analysis of daily quality checks. Studies using a humanoid phantom and polyethylene foams for lung were performed to measure reproducibility and accuracy. The dependence of the CT-estimated density on reconstruction filter, zoom factor, slice thickness, table height, data truncation, and objects outside the scan field was determined. Stability of the system at air density was within {approx}1 HU and at water density within {approx}2 HU. Reproducibility and accuracy for densities found for lung were within 2-3%. Dependence on the acquisition and reconstruction parameters was neglible, with the exceptions of the ultra high resolution reconstruction algorithm in the case of emphysema, and objects outside the scan field. The performance of the CT scanner tested is quite adequate for densitometry of the lungs. 26 refs., 5 figs., 4 tabs.

  4. Laser scanners: from industrial to biomedical applications

    NASA Astrophysics Data System (ADS)

    Duma, Virgil-Florin

    2013-11-01

    We present a brief overview of our contributions in the field of laser scanning technologies, applied for a variety of applications, from industrial, dimensional measurements to high-end biomedical imaging, such as Optical Coherence Tomography (OCT). Polygon Mirror (PM) scanners are presented, as applied from optical micrometers to laser sources scanned in frequency for Swept Sources (SSs) OCT. Galvanometer-based scanners (GSs) are approached to determine the optimal scanning function in order to obtain the highest possible duty cycle. We demonstrated that this optimal scanning function is linear plus parabolic, and not linear plus sinusoidal, as it has been previously considered in the literature. Risley prisms (rotational double wedges) scanners are pointed out, with our exact approach to determine and simulate their scan patterns in order to optimize their use in several types of applications, including OCT. A discussion on the perspectives of scanning in biomedical imaging, with a focus on OCT concludes the study.

  5. LCnote LCPHSM2005001 Determination of beam energy at TESLA using radiative

    E-print Network

    LCPHSM2005001 Determination of beam energy at TESLA using radiative return events ARND HINZE DESY Zeuthen at TESLA. It was suggested to use this method to cross check and calibrate the magnet spectrometer used for measurement of the beam energy at TESLA. A preliminary assessment of the statistical and systematic errors

  6. The TESLA Broadcast Authentication Protocol Adrian Perrig Ran Canetti J. D. Tygar Dawn Song

    E-print Network

    Xu, Wenyuan

    The TESLA Broadcast Authentication Protocol Adrian Perrig Ran Canetti J. D. Tygar Dawn Song presents the TESLA (Timed Efficient Stream Loss-tolerant Authentication) broadcast au- thentication numbers of receivers, and tolerates packet loss. TESLA is based on loose time synchro- nization between

  7. OPERATIONAL EXPERIENCE WITH THE TEST FACILITIES FOR TESLA H. Weise, DESY, Hamburg, Germany

    E-print Network

    OPERATIONAL EXPERIENCE WITH THE TEST FACILITIES FOR TESLA H. Weise, DESY, Hamburg, Germany Abstract The TESLA superconducting electron-positron linear collider with an integrated X-ray laser laboratory government in matters of science. In preparation of this, the TESLA Test Facility was set up at DESY. More

  8. Wakefield induced Losses in the Manual Valves of the TESLA Cryomodule

    E-print Network

    1 Wakefield induced Losses in the Manual Valves of the TESLA Cryomodule M.Dohlus,H.-P.Wedekind,K.Zapfe DeutschesElektronenSynchrotron Notkestr.85,D-22603Hamburg,Germany Abstract The beam pipe of the TESLA valves with spring type rf-shield which are presently used in the linac of the TESLA Test Facility

  9. TESLA: A Transparent, Extensible Session-Layer Architecture for End-to-end Network Services

    E-print Network

    TESLA: A Transparent, Extensible Session-Layer Architecture for End-to-end Network Services Jon describes TESLA, a transparent and extensible framework allowing session- layer services to be developed using a high-level flow- based abstraction. TESLA services can be deployed transparently using dynamic

  10. The TESLA Broadcast Authentication Protocol Adrian Perrig Ran Canetti J. D. Tygar Dawn Song

    E-print Network

    Tygar, Doug

    The TESLA Broadcast Authentication Protocol Adrian Perrig Ran Canetti J. D. Tygar Dawn Song presents the TESLA (Timed Efficient Stream Loss-tolerant Authentication) broadcast authentication protocol of receivers, and tolerates packet loss. TESLA is based on loose time synchronization between the sender

  11. TESLA: A Transparent, Extensible Session-Layer Architecture for End-to-end Network Services

    E-print Network

    Gummadi, Ramakrishna

    TESLA: A Transparent, Extensible Session-Layer Architecture for End-to-end Network Services Jon describes TESLA, a transparent and extensible framework allowing session- layer services to be developed using a high-level ¤ow- based abstraction. TESLA services can be deployed transparently using dynamic

  12. NHMFL Breaks the 100 Tesla Barrier Gregory S. Boebinger, National High Magnetic Field Laboratory

    E-print Network

    Weston, Ken

    NHMFL Breaks the 100 Tesla Barrier Gregory S. Boebinger, National High Magnetic Field Laboratory. 109no. 31 12404-12407 On March 22nd 2012, the NHMFL ­ Pulsed Field Facility broke the 100T tesla barrier, setting a world record of 100.75 tesla for a non-destructive magnet. By using advanced

  13. Tesla coil discharges guided by femtosecond laser filaments in air Yohann Brelet1

    E-print Network

    Boyer, Edmond

    1 Tesla coil discharges guided by femtosecond laser filaments in air Yohann Brelet1 , Aurélien, Palaiseau, France A Tesla coil generator was designed to produce high voltage pulses oscillating at 100 k experiments of laser guided discharges obtained in air by high voltage bursts delivered by a compact Tesla

  14. The TESLA Broadcast Authentication Protocol # Adrian Perrig Ran Canetti J. D. Tygar Dawn Song

    E-print Network

    Perrig, Adrian

    The TESLA Broadcast Authentication Protocol # Adrian Perrig Ran Canetti J. D. Tygar Dawn Song presents the TESLA (Timed Efficient Stream Loss­tolerant Authentication) broadcast au­ thentication numbers of receivers, and tolerates packet loss. TESLA is based on loose time synchro­ nization between

  15. Tesla: A Transparent, Extensible Session-Layer Framework for End-to-end Network Services

    E-print Network

    Tesla: A Transparent, Extensible Session-Layer Framework for End-to-end Network Services by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arthur C. Smith Chairman, Department Committee on Graduate Students #12; 2 #12; Tesla: A Transparent of these services, we describe Tesla, a transparent and extensible framework that allows session-layer services

  16. FIRST EXPERIMENTS WITH THE RF GUN BASED INJECTOR FOR THE TESLA TEST FACILITY LINAC

    E-print Network

    FIRST EXPERIMENTS WITH THE RF GUN BASED INJECTOR FOR THE TESLA TEST FACILITY LINAC S. Schreiber for the TESLA Collaboration, DESY, 22603 Hamburg, Germany Abstract During 1997 and 1998 a first accelerator module was tested successfully at the TESLA Test Facility Linac (TTFL) at DESY. Eight superconducting

  17. Electrical axes of TESLA-type cavities (Theoretical background, development of measurement equipment, measurement results)

    E-print Network

    - 1 - Electrical axes of TESLA-type cavities (Theoretical background, development of measurement equipment, measurement results) Anton Labanc, MHF-SL, DESY, January 2008 Abstract Cells in TESLA cavities. A short overview was already published at the TESLA Report 2007-01. This paper brings more details about

  18. LAL/RT 04-03 THE TESLA HIGH POWER COUPLER PROGRAM AT ORSAY

    E-print Network

    Boyer, Edmond

    LAL/RT 04-03 April 2004 1 THE TESLA HIGH POWER COUPLER PROGRAM AT ORSAY T. Garvey, H. Borie, L, Université de Paris-Sud, B.P. 34, 91898 Orsay, France Abstract Within the general TESLA collaboration-Orsay are centred on the development of RF input couplers for the cavities of the TESLA linear collider study

  19. Strongest non-destructive magnetic field: world record set at 100-tesla level

    E-print Network

    - 1 - Strongest non-destructive magnetic field: world record set at 100-tesla level March 22, 2012), the scientists achieved a whopping 100.75 tesla--a magnetic field nearly 100 times more powerful than a junkyard and insulators. The 100-tesla level is roughly equivalent to 2 million times Earth's magnetic field. #12;- 2

  20. Proving Correctness of the Basic TESLA Multicast Stream Authentication Protocol with TAME

    E-print Network

    Proving Correctness of the Basic TESLA Multicast Stream Authentication Protocol with TAME Presented, Washington, DC 20375 E-mail: archer@itd.nrl.navy.mil The TESLA multicast stream authentication protocol just been revealed. While an informal argument for the correctness of TESLA has been published

  1. Tesla: A Transparent, Extensible Session-Layer Framework for End-to-end Network Services

    E-print Network

    Gummadi, Ramakrishna

    Tesla: A Transparent, Extensible Session-Layer Framework for End-to-end Network Services by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arthur C. Smith Chairman, Department Committee on Graduate Students #12;2 #12;Tesla: A Transparent of these services, we describe Tesla, a transparent and extensible framework that allows session-layer services

  2. Failure Analysis of the Beam Vacuum in the Superconducting Cavities of the TESLA Main Linear Accelerator

    E-print Network

    1 Failure Analysis of the Beam Vacuum in the Superconducting Cavities of the TESLA Main Linear Hamburg, Germany Abstract For the long term successful operation of the superconducting TESLA accelerator The beam vacuum system of the TESLA main linear accelerators contains about 20.000 superconducting cavities

  3. Study of the TESLA preaccelerator for the polarised electron beam Aline Curtoni, Marcel Jablonka,

    E-print Network

    Study of the TESLA preaccelerator for the polarised electron beam Aline Curtoni, Marcel Jablonka, CEA, DSM/DAPNIA, Saclay, France Abstract In the mainframe of the TESLA Technical Design Report a study assumed. Figure 1 : Schematic of the TESLA injector complex. This report deals with the bottom injector

  4. TESLA Report 2005-04 Modular & reconfigurable common PCB-platform of

    E-print Network

    TESLA Report 2005-04 Modular & reconfigurable common PCB-platform of FPGA based LLRF control system for TESLA Test Facility Krzysztof T. Pozniak, Ryszard S. Romaniuk Institute of Electronic Systems in a universal motherboard (MB) for the next generation of LLRF control system for TESLA. The motherboard bases

  5. TESLA-Based Defense Against Pollution Attacks in P2P Systems with Network Coding

    E-print Network

    Markopoulou, Athina

    TESLA-Based Defense Against Pollution Attacks in P2P Systems with Network Coding Anh Le, Athina and time asymmetry (as in TESLA [1]) to provide source authentication for the detection scheme and non; pollution; detection; identification; TESLA; homomorphic MAC. I. INTRODUCTION Peer-to-peer (P2P) systems

  6. The Superconducting TESLA Cavities Dedicated to the memory of Bjrn H. Wiik

    E-print Network

    Boyer, Edmond

    The Superconducting TESLA Cavities Dedicated to the memory of Bjørn H. Wiik B. Aune1 , R, California, USA Abstract The conceptional design of the proposed linear electron-positron collider TESLA/m at a quality factor Q0 5 · 109. The design goal for the cavities of the TESLA Test Facility (TTF) linac

  7. Forschung an Lepton Collidern Abbildung 49: Perspektivische Ansicht des TESLA-Detektors.

    E-print Network

    Forschung an Lepton Collidern Abbildung 49: Perspektivische Ansicht des TESLA-Detektors. 86 #12An- strengung vieler Gruppen und Institute der ,,Tech- nical Design Report" für TESLA veröffentlicht wer- den von TESLA, besonders in Bereichen, die im TDR nicht ausreichend behandelt werden konnten, und die

  8. DESY, February 2001, TESLA Report 2001-07 Concept of the Beam Exit and Entrance Windows

    E-print Network

    DESY, February 2001, TESLA Report 2001-07 Concept of the Beam Exit and Entrance Windows of the Beam Exit and Entrance Windows for the TESLA Water based Beam Dumps and its related Beam Lines M for the TESLA project, beam windows are required for two purposes. The beam leaves the vacuum system through

  9. Time Synchronization in Hierarchical TESLA Wireless Sensor Networks

    SciTech Connect

    Jason L. Wright; Milos Manic

    2009-08-01

    Time synchronization and event time correlation are important in wireless sensor networks. In particular, time is used to create a sequence events or time line to answer questions of cause and effect. Time is also used as a basis for determining the freshness of received packets and the validity of cryptographic certificates. This paper presents secure method of time synchronization and event time correlation for TESLA-based hierarchical wireless sensor networks. The method demonstrates that events in a TESLA network can be accurately timestamped by adding only a few pieces of data to the existing protocol.

  10. The conical scanner evaluation system design

    NASA Technical Reports Server (NTRS)

    Cumella, K. E.; Bilanow, S.; Kulikov, I. B.

    1982-01-01

    The software design for the conical scanner evaluation system is presented. The purpose of this system is to support the performance analysis of the LANDSAT-D conical scanners, which are infrared horizon detection attitude sensors designed for improved accuracy. The system consists of six functionally independent subsystems and five interface data bases. The system structure and interfaces of each of the subsystems is described and the content, format, and file structure of each of the data bases is specified. For each subsystem, the functional logic, the control parameters, the baseline structure, and each of the subroutines are described. The subroutine descriptions include a procedure definition and the input and output parameters.

  11. Radiation balance mapping with multispectral scanner data.

    NASA Technical Reports Server (NTRS)

    Malila, W. A.

    1972-01-01

    Energy budget and radiation balance relationships have been measured from the ground by investigators in several disciplines. Airborne and spaceborne multispectral sensors provide a new measurement capability for large-area synoptic mapping of these quantities. Procedures for estimating and mapping total exitance and radiation balance from multispectral scanner data are discussed, and example maps for an agricultural application are presented. This information extraction technique is an extension of the usual recognition mapping performed with multispectral scanner data, and represents a first step in the quantitative interpretation and assessment of surface conditions with remote sensor data.

  12. Miniature rotating transmissive optical drum scanner

    NASA Technical Reports Server (NTRS)

    Lewis, Robert (Inventor); Parrington, Lawrence (Inventor); Rutberg, Michael (Inventor)

    2013-01-01

    A miniature rotating transmissive optical scanner system employs a drum of small size having an interior defined by a circumferential wall rotatable on a drum axis, an optical element positioned within the interior of the drum, and a light-transmissive lens aperture provided at an angular position in the circumferential wall of the drum for scanning a light beam to or from the optical element in the drum along a beam azimuth angle as the drum is rotated. The miniature optical drum scanner configuration obtains a wide scanning field-of-view (FOV) and large effective aperture is achieved within a physically small size.

  13. Infrared scanner concept verification test report

    NASA Technical Reports Server (NTRS)

    Bachtel, F. D.

    1980-01-01

    The test results from a concept verification test conducted to assess the use of an infrared scanner as a remote temperature sensing device for the space shuttle program are presented. The temperature and geometric resolution limits, atmospheric attenuation effects including conditions with fog and rain, and the problem of surface emissivity variations are included. It is concluded that the basic concept of using an infrared scanner to determine near freezing surface temperatures is feasible. The major problem identified is concerned with infrared reflections which result in significant errors if not controlled. Action taken to manage these errors result in design and operational constraints to control the viewing angle and surface emissivity.

  14. Longitudinal regional brain volume loss in schizophrenia: relationship to antipsychotic medication and change in social function

    E-print Network

    Guo, Joyce Y.; Huhtaniska, Sanna; Miettunen, Jouko; Jääskeläinen, Erika; Kiviniemi, Vesa; Nikkinen, Juha; Moilanen, Jani S.; Haapea, Marianne; Mäki, Pirjo; Jones, Peter B.; Veijola, Juha; Isohanni, Matti; Murray, Graham K.

    2015-07-14

    separately. 2.4 The MRI scanner parameters Brain MRI structural images from two time points in the present longitudinal study were collected by a GE Sigma 1.5 Tesla MRI scanner in Oulu University Hospital. See supplementary text for details of MRI... and designed the experiments: Juha Veijola, Jouko Miettunen, Erika Jääskeläinen, Vesa Kiviniemi, Peter B. Jones, Matti Isohanni, Graham K. Murray. Performed the experiments: Juha Veijola, Jani S. Moilanen, Erika Jääskeläinen, Pirjo Mäki, Vesa Kiviniemi, Juha...

  15. 24. SITE BUILDING 002 SCANNER BUILDING OPERATIONS CENTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. SITE BUILDING 002 - SCANNER BUILDING - OPERATIONS CENTER -- MWOC IN OPEARATION AT 1924 ZULU TIME. 26 OCTOBER, 1999. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  16. 23. SITE BUILDING 002 SCANNER BUILDING RADAR CONTROL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. SITE BUILDING 002 - SCANNER BUILDING - RADAR CONTROL INTERFACE "RCL NO. 2" WITH COMPUTER CONTROL DISC DRIVE UNITS IN FOREGROUND. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  17. 2. SITE BUILDING 002 SCANNER BUILDING VIEW IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. SITE BUILDING 002 - SCANNER BUILDING - VIEW IS LOOKING NORTH 80° WEST "B" FACE ALONG BUILDING "A" FACE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  18. 1. SITE BUILDING 022 SCANNER BUILDING VIEW IS LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. SITE BUILDING 022- SCANNER BUILDING - VIEW IS LOOKING NORTH 70°WEST AT "B" AND "A" FACES. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  19. 3. SITE BUILDING 002 SCANNER BUILDING VIEW IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. SITE BUILDING 002 - SCANNER BUILDING - VIEW IS LOOKING NORTH 30° WEST AT "A" FACE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  20. 4. SITE BUILDING 002 SCANNER BUILDING SOUTH 30° ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. SITE BUILDING 002 - SCANNER BUILDING - SOUTH 30° WEST - VIEW IS LOOKING AT "B" FACE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  1. Quantification of the accuracy of MRI generated 3D models of long bones compared to CT generated 3D models.

    PubMed

    Rathnayaka, Kanchana; Momot, Konstantin I; Noser, Hansrudi; Volp, Andrew; Schuetz, Michael A; Sahama, Tony; Schmutz, Beat

    2012-04-01

    Orthopaedic fracture fixation implants are increasingly being designed using accurate 3D models of long bones based on computer tomography (CT). Unlike CT, magnetic resonance imaging (MRI) does not involve ionising radiation and is therefore a desirable alternative to CT. This study aims to quantify the accuracy of MRI-based 3D models compared to CT-based 3D models of long bones. The femora of five intact cadaver ovine limbs were scanned using a 1.5 T MRI and a CT scanner. Image segmentation of CT and MRI data was performed using a multi-threshold segmentation method. Reference models were generated by digitising the bone surfaces free of soft tissue with a mechanical contact scanner. The MRI- and CT-derived models were validated against the reference models. The results demonstrated that the CT-based models contained an average error of 0.15 mm while the MRI-based models contained an average error of 0.23 mm. Statistical validation shows that there are no significant differences between 3D models based on CT and MRI data. These results indicate that the geometric accuracy of MRI based 3D models was comparable to that of CT-based models and therefore MRI is a potential alternative to CT for generation of 3D models with high geometric accuracy. PMID:21855392

  2. Thermal ablation system using high intensity focused ultrasound (HIFU) and guided by MRI

    NASA Astrophysics Data System (ADS)

    Damianou, C.; Ioannides, K.; HadjiSavas, V.; Milonas, N.; Couppis, A.; Iosif, D.; Komodromos, M.; Vrionides, F.

    2009-04-01

    In this paper magnetic resonance imaging (MRI) is investigated for monitoring lesions created by high intensity focused ultrasound (HIFU) in kidney, liver and brain in vitro and in vivo. Spherically focused transducers of 4 cm diameter, focusing at 10 cm and operating at 1 and 4 MHz were used. An MRI compatible positioning device was developed in order to scan the HIFU transducer. The MRI compatibility of the system was successfully demonstrated in a clinical high-field MRI scanner. The ability of the positioning device to accurately move the transducer thus creating discrete and overlapping lesions in biological tissue was tested successfully. A simple, cost effective, portable positioning device has been developed which can be used in virtually any clinical MRI scanner since it can be sited on the scanner's table. The propagation of HIFU can use either a lateral or superior-inferior approach. Both T1-w FSE and T2-w FSE imaged successfully lesions in kidney and liver. T1-w FSE and T2-w FSE and FLAIR shows better anatomical details in brain than T1-w FSE, but with T1-w FSE the contrast between lesion and brain is higher for both thermal and bubbly lesion. With this system we were able to create large lesions (by producing overlapping lesions). The length of the lesions in vivo brain was much higher than the length in vitro, proving that the penetration in the in vitro brain is limited by reflection due to trapped bubbles in the blood vessels.

  3. An ultra fast electron beam x-ray tomography scanner

    Microsoft Academic Search

    F. Fischer; D. Hoppe; E. Schleicher; G. Mattausch; H. Flaske; R. Bartel; U. Hampel

    2008-01-01

    This paper introduces the design of an ultra fast x-ray tomography scanner based on electron beam technology. The scanner has been developed for two-phase flow studies where frame rates of 1 kHz and higher are required. Its functional principle is similar to that of the electron beam x-ray CT scanners used in cardiac imaging. Thus, the scanner comprises an electron

  4. Design of a Second Generation Firewire Based Data Acquisition System for Small Animal PET Scanners

    PubMed Central

    Lewellen, T.K.; Miyaoka, R.S.; MacDonald, L.R.; Haselman, M.; DeWitt, D.; Hunter, William; Hauck, S.

    2009-01-01

    The University of Washington developed a Firewire based data acquisition system for the MiCES small animal PET scanner. Development work has continued on new imaging scanners that require more data channels and need to be able to operate within a MRI imaging system. To support these scanners, we have designed a new version of our data acquisition system that leverages the capabilities of modern field programmable gate arrays (FPGA). The new design preserves the basic approach of the original system, but puts almost all functions into the FPGA, including the Firewire elements, the embedded processor, and pulse timing and pulse integration. The design has been extended to support implementation of the position estimation and DOl algorithms developed for the cMiCE detector module. The design is centered around an acquisition node board (ANB) that includes 65 ADC channels, Firewire 1394b support, the FPGA, a serial command bus and signal lines to support a rough coincidence window implementation to reject singles events from being sent on the Firewire bus. Adapter boards convert detector signals into differential paired signals to connect to the ANB. PMID:20228958

  5. A Tree-Based TESLA Broadcast Authentication for Sensor Networks Donggang Liu Peng Ning Sencun Zhu Sushil Jajodia

    E-print Network

    Zhu, Sencun

    A Tree-Based µTESLA Broadcast Authentication for Sensor Networks Donggang Liu Peng Ning Sencun Zhu to multiple nodes in an authenticated way. µTESLA and multi-level µTESLA have been proposed to provide of senders. Though multi-level µTESLA schemes can scale up to large sensor networks (in terms of receivers

  6. Biomedical imaging and sensing using flatbed scanners.

    PubMed

    Göröcs, Zoltán; Ozcan, Aydogan

    2014-09-01

    In this Review, we provide an overview of flatbed scanner based biomedical imaging and sensing techniques. The extremely large imaging field-of-view (e.g., ~600-700 cm(2)) of these devices coupled with their cost-effectiveness provide unique opportunities for digital imaging of samples that are too large for regular optical microscopes, and for collection of large amounts of statistical data in various automated imaging or sensing tasks. Here we give a short introduction to the basic features of flatbed scanners also highlighting the key parameters for designing scientific experiments using these devices, followed by a discussion of some of the significant examples, where scanner-based systems were constructed to conduct various biomedical imaging and/or sensing experiments. Along with mobile phones and other emerging consumer electronics devices, flatbed scanners and their use in advanced imaging and sensing experiments might help us transform current practices of medicine, engineering and sciences through democratization of measurement science and empowerment of citizen scientists, science educators and researchers in resource limited settings. PMID:24965011

  7. Earth Radiation Budget Experiment (ERBE) scanner instrument

    NASA Technical Reports Server (NTRS)

    Kopia, Leonard P.; Lee, Robert B., III

    1990-01-01

    Orbital measurements of the earth's longwave emitted radiation, and the sun's radiation reflected by the earth are being made by scanning radiometers on three spacecraft platforms in both high altitude sun-synchronous polar (833 km) and low altitude (600 km) equatorial orbits. These ERBE instruments were carried aboard two TIROS ATN satellites (NOAA-9 and -10) in December 1984, and September 1986, and on the Earth Radiation Budget Satellite launched from Space Shuttle mission 41-G in October 1984. Electronic problems with the scanners on all platforms have halted the reception of data after surpassing the scanner design life. The ERBE instruments have been designed to measure the radiance from earth with an absolute radiometric error of less than one percent. The scanner instrument consists of three broadband radiometer channels, shortwave, 0.25 micron to 3.5 microns, longwave 5.0 to 50 microns; and total, 0.25 microns to more than 50 microns, and use thermistor bolometers as sensing elements. This paper describes the design and operation of the ERBE scanner, an overview of the ground calibration approach, the in-flight calibration stability, and an analysis of on-orbit anomalous behavior.

  8. Shutter for rotating source CT scanner

    Microsoft Academic Search

    A. B. Braden; J. Covic; J. J. Kuwik; S. K. Taylor

    1980-01-01

    In a CT scanner having a rotating source of radiation and a series of stationary radiation detectors spaced about the axis of rotation of the source, an eclipsing shutter mechanism restricts the width of the diverging fan pattern of radiation to that portion of the patient scan circle which is intermediate the array of stationary detectors and the orbiting source.

  9. Wire scanner software and firmware issues

    SciTech Connect

    Gilpatrick, John Doug [Los Alamos National Laboratory

    2008-01-01

    The Los Alamos Neutron Science Center facility presently has 110 slow wire scanning profile measurement instruments located along its various beam lines. These wire scanners were developed and have been operating for at least 30 years. While the wire scanners solved many problems to operate and have served the facility well they have increasingly suffered from several problems or limitations, such as maintenance and reliability problems, antiquated components, slow data acquisition, and etc. In order to refurbish these devices, these wire scanners will be replaced with newer versions. The replacement will consist of a completely new beam line actuator, new cables, new electronics and brand new software and firmware. This note describes the functions and modes of operation that LabVIEW VI software on the real time controller and FPGA LabVIEW firmware will be required. It will be especially interesting to understand the overall architecture of these LabVIEW VIs. While this note will endeavor to describe all of the requirements and issues for the wire scanners, undoubtedly, there will be missing details that will be added as time progresses.

  10. Novel statistical calibration method for laser scanners

    NASA Astrophysics Data System (ADS)

    Chen, Jerry X.; Yen, Yung-Tsai C.

    1998-10-01

    Calibration of laser scanner is usually a complicated procedure and is only carried out in the manufacture site. Here we report a new statistical calibration method that is simple and easy. It can be carried out in either customer or manufacture site. This new approach is much more accurate than the current factory calibration method.

  11. Enriching Scanner Panel Models with Choice Experiments

    Microsoft Academic Search

    Joffre Swait; Rick L. Andrews

    2003-01-01

    This research examines the methods, viability, and benefits of pooling scanner panel choice data with compatible preference data from designed choice experiments. The fact that different choice data sources have diverse strengths and weaknesses suggests it might be possible to pool multiple sources to achieve improved models, due to offsetting advantages and disadvantages. For example, new attributes and attribute levels

  12. Miniature 'Wearable' PET Scanner Ready for Use

    ScienceCinema

    Paul Vaska

    2013-07-22

    Scientists from BNL, Stony Brook University, and collaborators have demonstrated the efficacy of a "wearable," portable PET scanner they've developed for rats. The device will give neuroscientists a new tool for simultaneously studying brain function and behavior in fully awake, moving animals.

  13. Learning and Teaching with a Computer Scanner

    ERIC Educational Resources Information Center

    Planinsic, G.; Gregorcic, B.; Etkina, E.

    2014-01-01

    This paper introduces the readers to simple inquiry-based activities (experiments with supporting questions) that one can do with a computer scanner to help students learn and apply the concepts of relative motion in 1 and 2D, vibrational motion and the Doppler effect. We also show how to use these activities to help students think like…

  14. Developments in holographic-based scanner designs

    Microsoft Academic Search

    David M. Rowe

    1997-01-01

    Holographic-based scanning systems have been used for years in the high resolution prepress markets where monochromatic lasers are generally utilized. However, until recently, due to the dispersive properties of holographic optical elements (HOEs), along with the high cost associated with recording 'master' HOEs, holographic scanners have not been able to penetrate major scanning markets such as the laser printer and

  15. Design and Preliminary Accuracy Studies of an MRI-Guided Transrectal Prostate Intervention System

    PubMed Central

    Krieger, Axel; Csoma, Csaba; Iordachita, Iulian I.; Guion, Peter; Singh, Anurag K.; Fichtinger, Gabor; Whitcomb, Louis L.

    2012-01-01

    This paper reports a novel system for magnetic resonance imaging (MRI) guided transrectal prostate interventions, such as needle biopsy, fiducial marker placement, and therapy delivery. The system utilizes a hybrid tracking method, comprised of passive fiducial tracking for initial registration and subsequent incremental motion measurement along the degrees of freedom using fiber-optical encoders and mechanical scales. Targeting accuracy of the system is evaluated in prostate phantom experiments. Achieved targeting accuracy and procedure times were found to compare favorably with existing systems using passive and active tracking methods. Moreover, the portable design of the system using only standard MRI image sequences and minimal custom scanner interfacing allows the system to be easily used on different MRI scanners. PMID:18044553

  16. TESLA Report 2003-21 Cavity Control System Optimization Methods

    E-print Network

    algorithm of the cavity field detection is proposed. The cavity field is estimated as a resultTESLA Report 2003-21 Cavity Control System ­ Optimization Methods For Single Cavity Driving and Envelope Detection. Tomasz Czarski, Ryszard Romaniuk, Krzysztof Poniak ELHEP Laboratory, ISE, Warsaw

  17. FEASIBILITY STUDY OF A HOM IOT FOR TESLA

    Microsoft Academic Search

    P. Sch; T. Weiland; A. Gamp

    1998-01-01

    For the TESLA linear collider 1.3 GHz RF sources with 10 MW peak power and about 70% efficiency are needed. As an alternative to the development of a Multibeam-Klystron, we investigate the feasibility of an IOT (Inductive Output Tube). This is a very compact RF source: The time struc- ture of the beam is produced by a gated emission cathode

  18. Study of orbit feedback systems for the TESLA Linear Collider

    Microsoft Academic Search

    R. Lorenz; I. Reyzl; S. Sabah

    1997-01-01

    In order to reduce the influence of magnet vibrations which can cause luminosity reduction in the TESLA Linear Collider, several feedback loops are planned to control the beam orbit and to keep the beams in collision. The complete control system for orbit correction can be divided into three different feedback systems: in the main linac a slow feedback system is

  19. TESLA Report 2003-16 FPGA based RF control

    E-print Network

    .N.Simrock, DESY, Hamburg, Germany Abstract The RF control system of the TESLA Test Facility employs a digital control, feedback and feedforward system to provide flexibility of controlalgorithms, extensive, shift register logic and block memories. System Generator for DSP is seamlessly integrated

  20. Integration of TESLA and FLUTE over satellite networks

    Microsoft Academic Search

    L. Liang; M. Bhutta; H. Cruickshank; Z. Sun; C. Kulatunga; G. Fairhurst

    2009-01-01

    Multicast research has explored the security challenges faced in group communications. Multicast transport and multicast security need to work in close collaboration to realise a multicast service. However, there has been comparatively little work to combine the two technologies. In this paper the authors is presenting an example of partially integrating timed efficient stream loss-tolerant authentication (TESLA) protocol and the

  1. TESLA Report 2005-02 DSP Integrated, Parameterized, FPGA Based

    E-print Network

    TESLA Report 2005-02 DSP Integrated, Parameterized, FPGA Based Cavity Simulator & Controller circuit Xilinx VirtexII V3000 embedded on a PCB XtremeDSP Development Kit by Nallatech. The FPGA circuit conducting cavity, cold option, cavity simulator, cavity controller, linear accelerators, FPGA, FPGA-DSP

  2. LCDET2001059 TESLA Silicon diode, readout and frontend

    E-print Network

    LC­DET­2001­059 TESLA Fev. 2001 Silicon diode, readout and front­end electronics on the proposed W­Si electromagnetic calorimeter A.Karar LPNHE­Ecole Polytechnique Ch. de la Taille LAL­Orsay Abstract Silicon diode holes, is connected to the wires by bonding on the wires side. On the diodes side, a conducting glue

  3. A polarized electron-nucleon scattering experiment at TESLA

    Microsoft Academic Search

    2000-01-01

    Longitudinally polarized electrons, accelerated as a small fraction of the total current in the e+ arm of the TESLA collider, can be directed onto a solid state target that may be either longitudinally or transversely polarized. In this way, polarized electron-nucleon scattering measurements can be realized with projected luminosities that are about two orders of magnitude higher than those of

  4. Nuclear Physics at the TESLA*HERA Complex

    E-print Network

    S. Sultansoy

    2000-10-26

    Construction of the TESLA linear electron-positron collider tangentially to the HERA proton ring will provide a number of new facilities for particle and nuclear physics research. In this paper main parameters and physics goals of eA, gamma-A and FEK gamma-A colliders, as well as fixed target experiments are discussed.

  5. Prediction of adverse cardiac events in dilated cardiomyopathy using cardiac T2* MRI and MIBG scintigraphy.

    PubMed

    Nagao, Michinobu; Baba, Shingo; Yonezawa, Masato; Yamasaki, Yuzo; Kamitani, Takeshi; Isoda, Takuro; Kawanami, Satoshi; Maruoka, Yasuhiro; Kitamura, Yoshiyuki; Abe, Kohtaro; Higo, Taiki; Sunagawa, Kenji; Honda, Hiroshi

    2015-02-01

    Iron deficiency and cardiac sympathetic impairment play a role in the worsening of heart failure, and these two conditions may be linked. The present study aimed to clarify the relationship between myocardial iron deficiency, cardiac sympathetic activity, and major adverse cardiac events (MACE) in patients with dilated cardiomyopathy (DCM). Cardiac T2* MRI for iron deficiency and (123)I-Metaiodobenzylguanidine (MIBG) imaging for cardiac sympathetic activity were performed in 46 patients with DCM. Myocardial T2* value (M-T2*) was calculated by fitting signal intensity data for mid-left ventricular septum to a decay curve using 3-Tesla scanner. (123)I-MIBG washout rate (MIBG-WR) was calculated using a polar-map technique with tomographic data. We analyze the ability of M-T2* and MIBG-WR to predict MACE. MIBG-WR and M-T2* were significantly greater in DCM patients with MACE than in patients without MACE. Receiver-operating-characteristics curve analysis showed that the optimal MIBG-WR and M-T2* thresholds of 35 % and 28.1 ms, and the two combination predict MACE with C-statics of 0.69, 0.73, and 0.82, respectively. Patients with MIBG-WR <35 % and M-T2* <28.1 ms had significantly lower event-free rates than those with MIBG-WR ?35 % or M-T2* ?28.1 ms (log-rank value = 4.35, p < 0.05). Cox hazard regression analysis showed that ?(2) and the hazard ratio were 3.99 and 2.15 for development of MACE in patients with MIBG-WR ?35 % or M-T2* ?28.1 ms (p < 0.05). Iron deficiency, expressed by a high M-T2*, and MIBG-WR were both independent predictors of MACE in patients with DCM. The two combination was a more powerful predictor of MACE than either parameter alone. PMID:25348658

  6. Calibration of Aircraft Scanner Data Using Ground Reflectance Panels

    Microsoft Academic Search

    Paul E. Anuta; William R. Simmons

    1972-01-01

    An experiment is described in which aircraft scanner data from calibrated reflectance panels in the scene was used to calibrate the scanner data for nearby targets. The method used permits reflectance calibration of scanner data for areas which are in environmental proximity to the reflectance panels. That is, the calibration is valid for areas receiving the same illumination, from the

  7. Performance characterization of a volumetric breast ultrasound scanner

    Microsoft Academic Search

    Thomas R. Nelson; Jakob Nebeker; Susie Denton; Laura I. Cervino; Dolores H. Pretorius; John M. Boone

    2007-01-01

    The purpose of this project was to design, build, and characterize the performance of a volume breast ultrasound (VBUS) scanner that images the pendant breast. VBUS scanner design includes a: 1) clinical ultrasound scanner and transducer; 2) scanning table with a hole for the pendant breast; 3) rotational gantry; 4) probe mounting assembly; 5) compressionless breast stabilization device; 6) acquisition,

  8. FIRST EXPERIENCES WITH THE TRIMBLE GX SCANNER , P. Grussenmeyer b

    E-print Network

    Paris-Sud XI, Université de

    200 series and on the other hand presented as "the 3D scanner that thinks like a surveyor and geodetic adjustments to the corresponding 3D scanner survey workflow are presented, based on experiences. The scanner uses an auto focus method for the laser which showed to be very useful mainly for close range

  9. DISS. ETH NO. 17036 Calibration of a Terrestrial Laser Scanner

    E-print Network

    Giger, Christine

    , and the influencing parameters. Laser scanners are a black box instrument that produces a huge number of 3D pointsDISS. ETH NO. 17036 Calibration of a Terrestrial Laser Scanner for Engineering Geodesy. Recent developments have improved several aspects of terrestrial laser scanners, e.g. the data

  10. A performance evaluation test for laser line scanners on CMMs

    Microsoft Academic Search

    Nick Van Gestel; Steven Cuypers; Philip Bleys; Jean-Pierre Kruth

    2009-01-01

    This paper presents a performance evaluation test for laser line scanners on 3D coordinate measuring machines (CMMs). Laser line scanners are becoming more popular in recent years, mainly for free form inspection tasks and reverse engineering. Error specification of these scanners is difficult because of many influencing factors like surface quality, surface orientation and scan depth. Therefore, procedures for evaluation

  11. New devices to deliver somatosensory stimuli during functional MRI.

    PubMed

    Graham, S J; Staines, W R; Nelson, A; Plewes, D B; McIlroy, W E

    2001-09-01

    A new class of devices are described for improving investigation of somatosensory neuronal activation using fMRI. Dubbed magnetomechanical vibrotactile devices (MVDs), the principle of operation involves driving wire coils with small oscillatory currents in the large static magnetic field inherent to MRI scanners. The resulting Lorentz forces can be oriented to generate large vibrations that are easily converted to translational motions as large as several centimeters. Representative data demonstrate the flexibility of MVDs to generate different well-controlled vibratory and tactile stimuli to activate special proprioceptive and cutaneous somatosensory afferent pathways. The implications of these data are discussed with respect to the literature on existing devices for producing sensorimotor activation, as well as expanding the scope of current fMRI investigations. PMID:11550233

  12. Clinical applications of PET/MRI: current status and future perspectives

    PubMed Central

    Nensa, Felix; Beiderwellen, Karsten; Heusch, Philipp; Wetter, Axel

    2014-01-01

    Fully integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) scanners have been available for a few years. Since then, the number of scanner installations and published studies have been growing. While feasibility of integrated PET/MRI has been demonstrated for many clinical and preclinical imaging applications, now those applications where PET/MRI provides a clear benefit in comparison to the established reference standards need to be identified. The current data show that those particular applications demanding multiparametric imaging capabilities, high soft tissue contrast and/or lower radiation dose seem to benefit from this novel hybrid modality. Promising results have been obtained in whole-body cancer staging in non-small cell lung cancer and multiparametric tumor imaging. Furthermore, integrated PET/MRI appears to have added value in oncologic applications requiring high soft tissue contrast such as assessment of liver metastases of neuroendocrine tumors or prostate cancer imaging. Potential benefit of integrated PET/MRI has also been demonstrated for cardiac (i.e., myocardial viability, cardiac sarcoidosis) and brain (i.e., glioma grading, Alzheimer’s disease) imaging, where MRI is the predominant modality. The lower radiation dose compared to PET/computed tomography will be particularly valuable in the imaging of young patients with potentially curable diseases. However, further clinical studies and technical innovation on scanner hard- and software are needed. Also, agreements on adequate refunding of PET/MRI examinations need to be reached. Finally, the translation of new PET tracers from pre-clinical evaluation into clinical applications is expected to foster the entire field of hybrid PET imaging, including PET/MRI. PMID:25010371

  13. fMRI Brain-Computer Interface: A Tool for Neuroscientific Research and Treatment

    PubMed Central

    Sitaram, Ranganatha; Caria, Andrea; Veit, Ralf; Gaber, Tilman; Rota, Giuseppina; Kuebler, Andrea; Birbaumer, Niels

    2007-01-01

    Brain-computer interfaces based on functional magnetic resonance imaging (fMRI-BCI) allow volitional control of anatomically specific regions of the brain. Technological advancement in higher field MRI scanners, fast data acquisition sequences, preprocessing algorithms, and robust statistical analysis are anticipated to make fMRI-BCI more widely available and applicable. This noninvasive technique could potentially complement the traditional neuroscientific experimental methods by varying the activity of the neural substrates of a region of interest as an independent variable to study its effects on behavior. If the neurobiological basis of a disorder (e.g., chronic pain, motor diseases, psychopathy, social phobia, depression) is known in terms of abnormal activity in certain regions of the brain, fMRI-BCI can be targeted to modify activity in those regions with high specificity for treatment. In this paper, we review recent results of the application of fMRI-BCI to neuroscientific research and psychophysiological treatment. PMID:18274615

  14. Development of assessment technology for a rat myocardial infarct model using integrated PET\\/CT and MRI images

    Microsoft Academic Search

    Sang-Keun Woo; Gi Jeong Cheon; Kyeong Min Kim; WonHo Lee; Yong Jin Lee; Min Hwan Kim; Joo Hyun Kang; Young Hoon Ji; Chang Woon Choi; Sang Moo Lim

    2010-01-01

    The aim of this study was to improve quantitative assessment of rat myocardial infarct size using attenuation corrected PET polar map with gated CT image and MRI polarmap. The PET\\/CT images obtained with a small animal PET\\/CT scanner. Gating was realized with the help of an external trigger device. Contrast enhanced FLASH sequence MRI image was acquired with a 3-T

  15. A new potential of blood oxygenation level dependent (BOLD) functional MRI for evaluating cerebral centers of penile erection

    Microsoft Academic Search

    JJ Seo; HK Kang; SB Ryu; HJ Kim; GW Jeong

    2001-01-01

    It is well known that penile erection is dependent on commands from the central nervous system. However, there has been little research on the central control of penile erection. The aim of this study was to evaluate, for the first time, the cerebral centers of penile erection using BOLD-functional MRI. Functional magnetic resonance imaging (fMRI) on a 1.5T MR scanner

  16. Experimental System Setup for HIFU under MRI for mouse experiments

    NASA Astrophysics Data System (ADS)

    Long, Tao; Amin, Viren; Boska, Michael

    2009-04-01

    We describe an integrated system setup for HIFU and MRI thermometry for mouse experiments. The applications of such a system include MRI imaging and thermometry for evaluation and feedback during HIFU applications on mouse models of various diseases; and validation of temperature estimated by other methods, such as RF data. A 5 MHz geometrically focused (diameter of 16.1 mm, focal length 35 mm), MRI-compatible HIFU transducer is used, driven by a programmable signal generator and a power amplifier. The small animal MRI scanner has been programmed to acquire sequential phase information, which is used to determine frequency shift. Relative temperature rise is then calculated by proton resonance frequency (RPF) method. The current software development is done in C++ and Matlab. An integrated software is being developed to streamline the acquisition, analysis and visualization during HIFU delivery. Preliminary experiments have been performed using different phantoms. Performing HIFU (less than 100 watts) under MRI has had minimal interference for MRI data acquisition. The development is continuing for further characterizing and understanding the interference at the higher power level and accelerate data acquisition rate to achieve thermometry for a few frames per second. Further tissue experiments are under way with target of live mouse experiments. We present the overall design and discuss challenges encountered in the development of such system for experiments on mouse.

  17. Multi-centre reproducibility of diffusion MRI parameters for clinical sequences in the brain

    PubMed Central

    Grech-Sollars, Matthew; Hales, Patrick W; Miyazaki, Keiko; Raschke, Felix; Rodriguez, Daniel; Wilson, Martin; Gill, Simrandip K; Banks, Tina; Saunders, Dawn E; Clayden, Jonathan D; Gwilliam, Matt N; Barrick, Thomas R; Morgan, Paul S; Davies, Nigel P; Rossiter, James; Auer, Dorothee P; Grundy, Richard; Leach, Martin O; Howe, Franklyn A; Peet, Andrew C; Clark, Chris A

    2015-01-01

    The purpose of this work was to assess the reproducibility of diffusion imaging, and in particular the apparent diffusion coefficient (ADC), intra-voxel incoherent motion (IVIM) parameters and diffusion tensor imaging (DTI) parameters, across multiple centres using clinically available protocols with limited harmonization between sequences. An ice–water phantom and nine healthy volunteers were scanned across fives centres on eight scanners (four Siemens 1.5T, four Philips 3T). The mean ADC, IVIM parameters (diffusion coefficient D and perfusion fraction f) and DTI parameters (mean diffusivity MD and fractional anisotropy FA), were measured in grey matter, white matter and specific brain sub-regions. A mixed effect model was used to measure the intra- and inter-scanner coefficient of variation (CV) for each of the five parameters. ADC, D, MD and FA had a good intra- and inter-scanner reproducibility in both grey and white matter, with a CV ranging between 1% and 7.4%; mean 2.6%. Other brain regions also showed high levels of reproducibility except for small structures such as the choroid plexus. The IVIM parameter f had a higher intra-scanner CV of 8.4% and inter-scanner CV of 24.8%. No major difference in the inter-scanner CV for ADC, D, MD and FA was observed when analysing the 1.5T and 3T scanners separately. ADC, D, MD and FA all showed good intra-scanner reproducibility, with the inter-scanner reproducibility being comparable or faring slightly worse, suggesting that using data from multiple scanners does not have an adverse effect compared with using data from the same scanner. The IVIM parameter f had a poorer inter-scanner CV when scanners of different field strengths were combined, and the parameter was also affected by the scan acquisition resolution. This study shows that the majority of diffusion MRI derived parameters are robust across 1.5T and 3T scanners and suitable for use in multi-centre clinical studies and trials. © 2015 The Authors NMR in Biomedicine Published by John Wiley & Sons Ltd. PMID:25802212

  18. PRECISIONPNEUMATICROBOTFOR MRI-GUIDEDNEUROSURGERY

    E-print Network

    Webster III, Robert James

    PRECISIONPNEUMATICROBOTFOR MRI-GUIDEDNEUROSURGERY DavidB.Comber,DianaCardona,Robert of Energetic Systems Objective To provide a minimally invasive treatment for epilepsy in a closedbore MRI design objectives: ·Fully MRI compatible ­nonmagnetic and mostly plastic ·Safe operation ­Rod locks

  19. A prototype manipulator for magnetic resonance-guided interventions inside standard cylindrical magnetic resonance imaging scanners.

    PubMed

    Tsekos, Nikolaos V; Ozcan, Alpay; Christoforou, Eftychios

    2005-11-01

    The aim of this work is to develop a remotely controlled manipulator to perform minimally invasive diagnostic and therapeutic interventions in the abdominal and thoracic cavities, with real-time magnetic resonance imaging (MRI) guidance inside clinical cylindrical MR scanners. The manipulator is composed of a three degree of freedom Cartesian motion system, which resides outside the gantry of the scanner, and serves as the holder and global positioner of a three degree of freedom arm which extends inside the gantry of the scanner At its distal end, the arm's end-effector can carry an interventional tool such as a biopsy needle, which can be advanced to a desired depth by means of a seventh degree of freedom. These seven degrees of freedom, provided by the entire assembly, offer extended manipulability to the device and a wide envelope of operation to the user, who can select a trajectory suitable for the procedure. The device is constructed of nonmagnetic and nonconductive fiberglass, and carbon fiber composite materials, to minimize artifacts and distortion on the MR images as well as eliminate effects on its operation from the high magnetic field and the fast switching magnetic field gradients used in MR imaging. A user interface was developed for man-in-the-loop control of the device using real-time MR images. The user interface fuses all sensor signals (MR and manipulator information) in a visualization, planning, and control command environment. Path planning is performed with graphical tools for setting the trajectory of insertion of the interventional tool using multislice and/or three dimensional MR images which are refreshed in real time. The device control is performed with an embedded computer which runs real-time control software. The manipulator compatibility with the MR environment and image-guided operation was tested on a 1.5 T MR scanner. PMID:16438235

  20. Retrieval, Monitoring, and Control Processes: A 7 Tesla fMRI Approach to Memory Accuracy

    PubMed Central

    Risius, Uda-Mareke; Staniloiu, Angelica; Piefke, Martina; Maderwald, Stefan; Schulte, Frank P.; Brand, Matthias; Markowitsch, Hans J.

    2012-01-01

    Memory research has been guided by two powerful metaphors: the storehouse (computer) and the correspondence metaphor. The latter emphasizes the dependability of retrieved mnemonic information and draws upon ideas about the state dependency and reconstructive character of episodic memory. We used a new movie to unveil the neural correlates connected with retrieval, monitoring, and control processes, and memory accuracy (MAC), according to the paradigm of Koriat and Goldsmith (1996a,b). During functional magnetic resonance imaging, subjects performed a memory task which required (after an initial learning phase) rating true and false statements [retrieval phase (RP)], making confidence judgments in the respective statement [monitoring phase (MP)], and deciding for either venturing (volunteering) the respective answer or withholding the response [control phase (CP)]. Imaging data pointed to common and unique neural correlates. Activations in brain regions related to RP and MAC were observed in the precuneus, middle temporal gyrus, and left hippocampus. MP was associated with activation in the left anterior and posterior cingulate cortex along with bilateral medial temporal regions. If an answer was volunteered (as opposed to being withheld) during the CP, temporal, and frontal as well as middle and posterior cingulate areas and the precuneus revealed activations. Increased bilateral hippocampal activity was found during withholding compared to volunteering answers. The left caudate activation detected during withholding compared to venturing an answer supports the involvement of the left caudate in inhibiting unwanted responses. Contrary to expectations, we did not evidence prefrontal activations during withholding (as opposed to volunteering) answers. This may reflect our design specifications, but alternative interpretations are put forth. PMID:23580061

  1. A 128-Channel Receive-Only Cardiac Coil for Highly Accelerated Cardiac MRI at 3 Tesla

    PubMed Central

    Schmitt, Melanie; Potthast, Andreas; Sosnovik, David E.; Polimeni, Jonathan R.; Wiggins, Graham C.; Triantafyllou, Christina; Wald, Lawrence L.

    2008-01-01

    A 128-channel receive-only array coil is described and tested for cardiac imaging at 3T. The coil is closely contoured to the body with a “clam-shell” geometry with 68 posterior and 60 anterior elements, each 75 mm in diameter, and arranged in a continuous overlapped array of hexagonal symmetry to minimize nearest neighbor coupling. Signal-to-noise ratio (SNR) and noise amplification for parallel imaging (G-factor) were evaluated in phantom and volunteer experiments. These results were compared to those of commercially available 24-channel and 32-channel coils in routine use for cardiac imaging. The in vivo measurements with the 128-channel coil resulted in SNR gains compared to the 24-channel coil (up to 2.2-fold in the apex). The 128- and 32-channel coils showed similar SNR in the heart, likely dominated by the similar element diameters of these coils. The maximum G-factor values were up to seven times better for a seven-fold acceleration factor (R = 7) compared to the 24-channel coil and up to two-fold improved compared to the 32-channel coil. The ability of the 128-channel coil to facilitate highly accelerated cardiac imaging was demonstrated in four volunteers using acceleration factors up to seven-fold (R = 7) in a single spatial dimension. PMID:18506789

  2. Detection of the early negative response in fMRI at 1.5 Tesla

    Microsoft Academic Search

    E. Yacoub; X. Hu

    1999-01-01

    Recent experimental studies have revealed an initial decrease in magnetic resonance (MR) signal that is consistent with optical imaging results. This initial response, thought to arise from a transient increase in deoxyhemoglobin concentration, is prob- ably more localized to the site of neuronal activation. However, with MR imaging, this early response has only been demon- strated at high fields. In

  3. Preoperative 3-Tesla Multiparametric Endorectal Magnetic Resonance Imaging Findings and the Odds of Upgrading and Upstaging at Radical Prostatectomy in Men With Clinically Localized Prostate Cancer

    SciTech Connect

    Hegde, John V. [Harvard Medical School, Boston, Massachusetts (United States) [Harvard Medical School, Boston, Massachusetts (United States); Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts (United States); Chen, Ming-Hui [Department of Statistics, University of Connecticut, Storrs, Connecticut (United States)] [Department of Statistics, University of Connecticut, Storrs, Connecticut (United States); Mulkern, Robert V. [Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts (United States) [Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts (United States); Department of Radiology, Children's Hospital Boston, Boston, Massachusetts (United States); Fennessy, Fiona M. [Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts (United States) [Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts (United States); Department of Imaging, Dana-Farber Cancer Institute, Boston, Massachusetts (United States); D'Amico, Anthony V. [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Boston, Massachusetts (United States)] [Department of Radiation Oncology, Brigham and Women's Hospital and Dana-Farber Cancer Institute, Boston, Massachusetts (United States); Tempany, Clare M.C., E-mail: ctempany@bwh.harvard.edu [Division of MRI, Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts (United States)

    2013-02-01

    Purpose: To investigate whether 3-T esla (3T) multiparametric endorectal MRI (erMRI) can add information to established predictors regarding occult extraprostatic or high-grade prostate cancer (PC) in men with clinically localized PC. Methods and Materials: At a single academic medical center, this retrospective study's cohort included 118 men with clinically localized PC who underwent 3T multiparametric erMRI followed by radical prostatectomy, from 2008 to 2011. Multivariable logistic regression analyses in all men and in 100 with favorable-risk PC addressed whether erMRI evidence of T3 disease was associated with prostatectomy T3 or Gleason score (GS) 8-10 (in patients with biopsy GS {<=}7) PC, adjusting for age, prostate-specific antigen level, clinical T category, biopsy GS, and percent positive biopsies. Results: The accuracy of erMRI prediction of extracapsular extension and seminal vesicle invasion was 75% and 95%, respectively. For all men, erMRI evidence of a T3 lesion versus T2 was associated with an increased odds of having pT3 disease (adjusted odds ratio [AOR] 4.81, 95% confidence interval [CI] 1.36-16.98, P=.015) and pGS 8-10 (AOR 5.56, 95% CI 1.10-28.18, P=.038). In the favorable-risk population, these results were AOR 4.14 (95% CI 1.03-16.56), P=.045 and AOR 7.71 (95% CI 1.36-43.62), P=.021, respectively. Conclusions: Three-Tesla multiparametric erMRI in men with favorable-risk PC provides information beyond that contained in known preoperative predictors about the presence of occult extraprostatic and/or high-grade PC. If validated in additional studies, this information can be used to counsel men planning to undergo radical prostatectomy or radiation therapy about the possible need for adjuvant radiation therapy or the utility of adding hormone therapy, respectively.

  4. Magnetic-field-induced dose effects in MR-guided radiotherapy systems: dependence on the magnetic field strength

    Microsoft Academic Search

    A J E Raaijmakers; B W Raaymakers; J J W Lagendijk

    2008-01-01

    Several institutes are currently working on the development of a radiotherapy treatment system with online MR imaging (MRI) modality. The main difference between their designs is the magnetic field strength of the MRI system. While we have chosen a 1.5 Tesla (T) magnetic field strength, the Cross Cancer Institute in Edmonton will be using a 0.2 T MRI scanner and

  5. Hematocrit and Oxygenation Dependence of Blood 1H2O T1 At 7 Tesla

    PubMed Central

    Grgac, Ksenija; van Zijl, Peter C.M.; Qin, Qin

    2012-01-01

    Knowledge of blood 1H2O T1 is critical for perfusion-based quantification experiments such as arterial spin labeling (ASL) and CBV-weighted MRI using vascular space occupancy (VASO). The dependence of blood 1H2O T1 on hematocrit fraction (Hct) and oxygen saturation fraction (Y) was determined at 7 Tesla using in vitro bovine blood in a circulating system under physiological conditions. Blood 1H2O R1 values for different conditions could be readily fitted using a two-compartment (erythrocyte and plasma) model which are described by a monoexponential longitudinal relaxation rate constant dependence. It was found that T1 = 2171±39 ms for Y = 1 (arterial blood) and 2010±41 ms for Y = 0.6 (venous blood), for a typical Hct of 0.42. The blood 1H2O T1 values in the normal physiological range (Hct from 0.35 to 0.45, and Y from 0.6 to 1.0) were determined to range from 1900 ms to 2300 ms. The influence of oxygen partial pressure (pO2) and the effect of plasma osmolality for different anticoagulants were also investigated. It is discussed why blood 1H2O T1 values measured in vivo for human blood may be about 10-20% larger than found in vitro for bovine blood at the same field strength. PMID:23169066

  6. Telescope with a wide field of view internal optical scanner

    NASA Technical Reports Server (NTRS)

    Degnan, III, John James (Inventor); Zheng, Yunhui (Inventor)

    2012-01-01

    A telescope with internal scanner utilizing either a single optical wedge scanner or a dual optical wedge scanner and a controller arranged to control a synchronous rotation of the first and/or second optical wedges, the wedges constructed and arranged to scan light redirected by topological surfaces and/or volumetric scatterers. The telescope with internal scanner further incorporates a first converging optical element that receives the redirected light and transmits the redirected light to the scanner, and a second converging optical element within the light path between the first optical element and the scanner arranged to reduce an area of impact on the scanner of the beam collected by the first optical element.

  7. Biopsy Needle Artifact Localization in MRI-guided Robotic Transrectal Prostate Intervention

    PubMed Central

    Song, Sang-Eun; Cho, Nathan B.; Iordachita, Iulian; Guion, Peter; Fichtinger, Gabor; Kaushal, Aradhana; Camphausen, Kevin; Whitcomb, Louis L.

    2013-01-01

    Recently a number of robotic intervention systems for magnetic resonance image (MRI) guided needle placement in the prostate have been reported. In MRI-guided needle interventions, after a needle is inserted, the needle position is often confirmed with a volumetric MRI scan. Commonly used titanium needles are not directly visible in an MR image, but they generate a susceptibility artifact in the immediate neighborhood of the needle. This paper reports the results of a quantitative study of the relationship between the true position of titanium biopsy needle and the corresponding needle artifact position in MR images, thereby providing a better understanding of the influence of needle artifact on targeting errors. The titanium needle tip artifact extended 9 mm beyond the actual needle tip location with tendency to bend towards the scanner’s B0 magnetic field direction, and axially displaced 0.38 mm and 0.32 mm (mean) in scanner’s frequency and phase encoding direction, respectively. PMID:22481805

  8. Dynamic contrast MRI

    Cancer.gov

    Recommendations for MR measurement methods at 1.5-Tesla and endpoints for use in Phase 1/2a trials of anti-cancer therapeutics affecting tumor vascular function Type of measurement • Study design should incorporate quality assurance of the MR system,

  9. Evaluation of primary adnexal masses by 3T MRI: categorization with conventional MR imaging and diffusion-weighted imaging

    PubMed Central

    2012-01-01

    Background To investigate the 3.0-Tesla (3 T) magnetic resonance imaging (MRI) characteristics of primary adnexal lesions for discriminating benign from malignant lesions. Methods One hundred thirty-nine patients with pathologically proven primary adnexal masses referred for 3 T MRI assessment preoperatively were included. Baseline characteristics, components, and conventional MRI and diffusion-weighted imaging (DWI-MRI) signals were recorded and compared. Results There were 22 ovarian cysts, 33 endometriomas, 43 benign tumors and 42 malignant tumors. When ovarian cyst and endometrioma were excluded, there were no significant differences in patients’ age between benign and malignant tumor (P = 0.235). There were no significant differences (P = 0.606) in the conventional MRI signals and significant difference (P = 0.008) in DWI-MRI signal between the non-malignant and malignant lesions. There was a significant difference (P = 0.000) in the apparent diffusion coefficient values (ADCs) between the non-malignant and malignant lesions. Conclusions 3 T MRI categorized the characteristics of primary adnexal lesions. Conventional MRI signals were not useful for characterizing between benign and malignant lesions. DWI-MRI and ADCs were helpful for distinguishing malignant from benign ovarian lesions. PMID:23148860

  10. The E.M.I. Scanner

    Microsoft Academic Search

    G. N. Hounsfield

    1977-01-01

    The E.M.I. scanner is a machine which employs a method of X-raying patients whereby the information obtained from the X-rays is fully utilized. The high sensitivity thus obtained enables the machine to differentiate between the various organs of the body which are presented in three-dimensional form as a series of tomographic slices. The machine scans through the patient in a

  11. Ground location of satellite scanner data

    NASA Technical Reports Server (NTRS)

    Puccinelli, E. F.

    1976-01-01

    This paper presents simple and accurate mathematical formulation for determining the ground location of remote sensor data. The techniques used are based on elementary concepts of differential geometry and lead to the development of a relation that gives location as a function of surface ellipticity, satellite position, velocity, attitude, and scanner orientation. The formula lends itself to simply computer coding and will hopefully lead to a standardization of the various techniques which have been developed to solve this problem.

  12. Point Relay Scanner Utilizing Ellipsoidal Mirrors

    NASA Technical Reports Server (NTRS)

    Manhart, Paul K. (Inventor); Pagano, Robert J. (Inventor)

    1997-01-01

    A scanning system uses a polygonal mirror assembly with each facet of the polygon having an ellipsoidal mirror located thereon. One focal point of each ellipsoidal mirror is located at a common point on the axis of rotation of the polygonal mirror assembly. As the mirror assembly rotates. a second focal point of the ellipsoidal mirrors traces out a scan line. The scanner can be utilized for scanned output display of information or for scanning information to be detected.

  13. Improvement in measurement accuracy for hybrid scanner

    NASA Astrophysics Data System (ADS)

    Abbas, M. A.; Setan, H.; Majid, Z.; Chong, A. K.; Lichti, D. D.

    2014-02-01

    The capability to provide dense three-dimensional (3D) data (point clouds) at high speed and at high accuracy has made terrestrial laser scanners (TLS) widely used for many purposes especially for documentation, management and analysis. However, similar to other 3D sensors, proper understanding regarding the error sources is necessary to ensure high quality data. A procedure known as calibration is employed to evaluate these errors. This process is crucial for TLS in order to make it suitable for accurate 3D applications (e.g. industrial measurement, reverse engineering and monitoring). Two calibration procedures available for TLS: 1) component, and 2) system calibration. The requirements of special laboratories and tools which are not affordable by most TLS users have become principle drawback for component calibration. In contrast, system calibration only requires a room with appropriate targets. By employing optimal network configuration, this study has performed system calibration through self-calibration for Leica ScanStation C10 scanner. A laboratory with dimensions of 15.5 m × 9 m × 3 m and 138 well-distributed planar targets were used to derive four calibration parameters. Statistical analysis (e.g. t-test) has shown that only two calculated parameters, the constant rangefinder offset error (0.7 mm) and the vertical circle index error (-45.4") were significant for the calibrated scanner. Photogrammetric technique was utilised to calibrate the 3D test points at the calibration field. By using the test points, the residual pattern of raw data and self-calibration results were plotted into the graph to visually demonstrate the improvement in accuracy for Leica ScanStation C10 scanner.

  14. Full-Body Scanners: TSA's New \\

    Microsoft Academic Search

    Stuart A. Hindman

    2011-01-01

    While the world of commercial air transportation has seen major improvements in many technologies over the last decade, nothing has caused a stir quite like the implementation of full-body scanners (FBS) as a one of the first lines of defense in aviation security at U.S. airports. FBS and “enhanced” pat-downs have been the source of much debate and scrutiny among

  15. A near-infrared confocal scanner

    NASA Astrophysics Data System (ADS)

    Lee, Seungwoo; Yoo, Hongki

    2014-06-01

    In the semiconductor industry, manufacturing of three-dimensional (3D) packages or 3D integrated circuits is a high-performance technique that requires combining several functions in a small volume. Through-silicon vias, which are vertical electrical connections extending through a wafer, can be used to direct signals between stacked chips, thus increasing areal density by stacking and connecting multiple patterned chips. While defect detection is essential in the semiconductor manufacturing process, it is difficult to identify defects within a wafer or to monitor the bonding results between bonded surfaces because silicon and many other semiconductor materials are opaque to visible wavelengths. In this context, near-infrared (NIR) imaging is a promising non-destructive method to detect defects within silicon chips, to inspect bonding between chips and to monitor the chip alignment since NIR transmits through silicon. In addition, a confocal scanner provides high-contrast, optically-sectioned images of the specimen due to its ability to reject out-of-focus noise. In this study, we report an NIR confocal scanner that rapidly acquires high-resolution images with a large field of view through silicon. Two orthogonal line-scanning images can be acquired without rotating the system or the specimen by utilizing two orthogonally configured resonant scanning mirrors. This NIR confocal scanner can be efficiently used as an in-line inspection system when manufacturing semiconductor devices by rapidly detecting defects on and beneath the surface.

  16. [MRI symptomatology of primary intraspinal cord gliomas].

    PubMed

    Joubert, E; Idir, A B; Carlier, R; Belal, N; Hurth, M; Lacroix-Ciaudo, C; Ducot, B; Doyon, D

    1995-03-01

    MRI has now been recognized as the best technique for exploration of spinal tumours and, in particular, tumours within the spinal cord. Based on a retrospective study of 74 operated glial tumours, we are trying to define a specific semiology for intramedullary astrocytomas and ependymomas. Thirty-four cases were selected including 17 astrocytomas (7 low-grade, 10 high-grade) and 17 ependymomas (1 of which was grade III) for whom the pre-operative MRI examination was complete, with T1-weighted sequences without, then with gadolinium, and T2-weighted sequences. The examination was performed using a high-field and in most cases 1.5 Tesla machine. Analysis, correlated with operative data and pathology results, comprised on the one hand patients' distribution by age, sex and location of the tumour on the spinal cord, and on the other hand the MRI semiology concerning the sagittal and axial localization of the fleshy portion after gadolinium injection, the limits of the tumour, the homo- or heterogeneous character of its enhancement, the possible existence of stigmas of intra- or peritumoral chronic bleeding, and finally the presence or absence of associated cysts in the 34 exploitable cases. Some semiological differences were elicited between astrocytomas and ependymomas: the patient's age at the time of diagnosis was predominantly 0 to 20 for astrocytomas (astrocytomas 39%, ependymomas 4%), and the well-limited character of the fleshy portion of the tumour after gadolinium injection was found in 70% of ependymomas, 40% of high-grade astrocytomas and 14% of low-grade astrocytomas. The homogeneity of contrast enhancement in ependymomas has been classically defined, but it did not show in our series. Finally, it seems that high-grade astrocytomas are characterized by the rare presence of hemosiderin deposits (high-grade 20%, low-grade 57%, ependymomas 58%) and by the absence or reduced extension of overlying and underlying cysts. PMID:7707132

  17. 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

  18. A Study of Needle Image Artifact Localization in Confirmation Imaging of MRI-guided Robotic Prostate Biopsy

    PubMed Central

    Song, Sang-Eun; Cho, Nathan B.; Iordachita, Iulian I.; Guion, Peter; Fichtinger, Gabor; Whitcomb, Louis L.

    2012-01-01

    Recently several systems for magnetic resonance image (MRI) guided needle placement in the prostate have been reported. In comparison to conventional ultrasound-guided needle placement in the prostate, these MRI-guided systems promise improved targeting accuracy for prostate intervention procedures including biopsy, fiducial marker insertion, injection and focal therapy. In MRI-guided needle interventions, after a needle is inserted, the needle position is often confirmed with a volumetric MRI scan. Commonly used titanium needles are not directly visible in an MR image, but they generate a susceptibility artifact in the immediate neighborhood of the needle. This paper reports the results of a quantitative study of the relation between the true position of titanium biopsy needle and the corresponding needle artifact position in MR images. The titanium needle artifact was found to be displaced 0.38 mm and 0.32 mm shift in scanner’s frequency and phase encoding direction, respectively. The artifact at the tip of the titanium needle was observed to bend toward the scanner’s B0 magnetic field direction. PMID:22423338

  19. Sparsity in MRI RF Excitation Pulse Design Adam C. Zelinski, Vivek K Goyal, Elfar Adalsteinsson, Lawrence L. Wald

    E-print Network

    Goyal, Vivek K

    Table Scanner Magnet Gradient Coils Radio Frequency Coil B0 z y x Fig. 1. Cutaway view of a protoSparsity in MRI RF Excitation Pulse Design Adam C. Zelinski, Vivek K Goyal, Elfar Adalsteinsson are then detected using a resonant coil; images are then reconstructed from this data. Excitation pulses need

  20. Phase stability in fMRI time series: Effect of noise regression, off-resonance correction and spatial filtering techniques

    Microsoft Academic Search

    Gisela E. Hagberg; Marta Bianciardi; Valentina Brainovich; Antonio Maria Cassara; Bruno Maraviglia

    Although the majority of fMRI studies exploit magnitude changes only, there is an increasing interest regarding the potential additive information conveyed by the phase signal. This integrated part of the complex number furnished by the MR scanners can also be used for exploring direct detection of neuronal activity and for thermography. Few studies have explicitly addressed the issue of the