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1

Sensitivity Quantification of Remote Detection NMR and MRI  

Energy Technology Data Exchange (ETDEWEB)

A sensitivity analysis of the remote detection NMR techniqueis presented. With remote detection, information about a sample isencoded onto a mobile sensor fluid, which facilitates a spatialseparation of encoding and detection of spin magnetization. This approachcan be interpreted as a two-dimensional NMR experiment, therefore thesame general formalism can be used for a sensitivity analysis. Eventhough remote detection is a point-by-point experiment, the sensitivitydoes not scale unfavorably with the number of detected points compared totransient detection. It is proportional to the relative sensitivitybetween the remote detector and the circuit that is used for encoding.The influence of the different signal decay times is analyzed, and thedistinction between spectroscopy and imaging experiments ismade.

Granwehr, Josef; Seeley, Juliette A.

2005-10-25

2

Quantifying the Diffusion of a Fluid through Membranes by RemoteDetection MRI  

Energy Technology Data Exchange (ETDEWEB)

We present a method to measure self-diffusion acrossmembranes without the need for concentration or pressure gradients.Hyperpolarized xenon in combination with remote detection of NMR allowsthe measurement of membrane permeation, even in the gas phase. Theresulting images allow quantification of the amount of fluid diffusedthrough the membrane, and represent an alternative, potentially moreprecise way of measuring a membrane diffusion coefficient. The use ofremote detection of NMR allows for non-invasive signal encoding coupledto sensitive detection, making this approach ideal for the study ofdiffusion in intact devices such as fuel cells or separationsystems.

Telkki, Ville-Veikko; Hilty, Christian; Garcia, Sandra; Harel,Elad; Pines, Alexander

2006-10-24

3

Remote detection system  

International Nuclear Information System (INIS)

A newly designed remote detection system has been developed at Los Alamos that allows the collection of high-resolution gamma-ray spectra and neutron data from a remote location. The system consists of the remote unit and a command unit. The remote unit collects data in a potentially hostile environment while the operator controls the unit by either radio or wire link from a safe position. Both units are battery powered and are housed in metal carrying cases

4

Remote control catheter navigation: options for guidance under MRI  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Image-guided endovascular interventions have gained increasing popularity in clinical practice, and magnetic resonance imaging (MRI) is emerging as an attractive alternative to X-ray fluoroscopy for guiding such interventions. Steering catheters by remote control under MRI guidance offers unique challenges and opportunities. Methods In this review, the benefits and limitations of MRI-guided remote control intervention are addressed, and the t...

Muller Leah; Saeed Maythem; Wilson Mark W; Hetts Steven W

2012-01-01

5

Remote control catheter navigation: options for guidance under MRI  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Image-guided endovascular interventions have gained increasing popularity in clinical practice, and magnetic resonance imaging (MRI is emerging as an attractive alternative to X-ray fluoroscopy for guiding such interventions. Steering catheters by remote control under MRI guidance offers unique challenges and opportunities. Methods In this review, the benefits and limitations of MRI-guided remote control intervention are addressed, and the tools for guiding such interventions in the magnetic environment are summarized. Designs for remote control catheter guidance include a catheter tip electromagnetic microcoil design, a ferromagnetic sphere-tipped catheter design, smart material-actuated catheters, and hydraulically actuated catheters. Remote control catheter guidance systems were compared and contrasted with respect to visualization, safety, and performance. Performance is characterized by bending angles achievable by the catheter, time to achieve bending, degree of rotation achievable, and miniaturization capacity of the design. Necessary improvements for furthering catheter design, especially for use in the MRI environment, are addressed, as are hurdles that must be overcome in order to make MRI guided endovascular procedures more accessible for regular use in clinical practice. Conclusions MR-guided endovascular interventions under remote control steering are in their infancy due to issues regarding safety and reliability. Additional experimental studies are needed prior to their use in humans.

Muller Leah

2012-06-01

6

[MRI for troubleshooting detection of prostate cancer].  

Science.gov (United States)

Prostate cancer is the most common malignancy in males. Men aged 50 and older are recommended to undergo an annual digital rectal examination (DRE) and determination of prostate-specific antigen (PSA) in serum for early detection. However, prostate biopsies guided by transrectal ultrasound (TRUS) come up negative for cancer in many patients despite having PSA levels above 4 ng/ml. T2-weighted Magnetic Resonance Imaging (MRI) is able to represent the prostate including the surrounding anatomy and depict suspicious areas of low intensity within a high-intensity peripheral zone. MRI has a higher sensitivity for detecting prostate carcinomas than DRE and TRUS in patients having an elevated PSA value and a negative core biopsy. However, its specificity is poor since other abnormalities such as prostatic intraepithelial neoplasia (PIN), prostatitis, scars, or haemorrhage have a similar MRI appearance. The use of additional techniques such as MR spectroscopy and contrast-enhanced dynamic MRI improves sensitivity, but in particular it improves the specificity of tumor detection. Newly developed biopsy devices enable the performance of targeted biopsies in areas that appear suspicious in the MRI. PMID:15902626

Beyersdorff, D; Hamm, B

2005-06-01

7

MRI for troubleshooting detection of prostate cancer  

International Nuclear Information System (INIS)

Prostate cancer is the most common malignancy in males. Men aged 50 and older are recommended to undergo an annual digital rectal examination (DRE) and determination of prostate-specific antigen (PSA) in serum for early detection. However, prostate biopsies guided by transrectal ultrasound (TRUS) come up negative for cancer in many patients despite having PSA levels above 4 ng/ml. T2-weighted Magnetic Resonance Imaging (MRI) is able to represent the prostate including the surrounding anatomy and depict suspicious areas of low intensity within a high-intensity peripheral zone. MRI has a higher sensitivity for detecting prostate carcinomas than DRE and TRUS in patients having an elevated PSA value and a negative core biopsy. However, its specificity is poor since other abnormalities such as prostatic intraepithelial neoplasia (PIN), prostatitis, scars, or haemmorrhage have a similar MRI appearance. The use of additional techniques such as MR spectroscopy and contrast-enhanced dynamic MRI improves sensitivity, but in particular it improves the specificity of tumor detection. Newly developed biopsy devices enable the performance of targeted biopsies in areas that appear suspicious in the MRI. (orig.)

8

??????????????????MRI?????  

Directory of Open Access Journals (Sweden)

Full Text Available ???????????????????????????????????????????????????——????MRI??(??????????????????????????????????????????????????????????????????????????“?????”???????????????????????????????????????????????????????????????????????????

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2013-12-01

9

MRI  

Medline Plus

Full Text Available ... implant is MRI safe and compatible. Summary A magnetic resonance imaging scan can be helpful in detecting many kinds of problems in the body. To get the clearest picture, you should lie ...

10

Role of MRI for detection and characterization of pulmonary nodules  

International Nuclear Information System (INIS)

Due to physical and technical limitations, magnetic resonance imaging (MRI) has hitherto played only a minor role in image-based diagnostics of the lungs. However, as a consequence of important methodological developments during recent years, MRI has developed into a technically mature and clinically well-proven method for specific pulmonary questions. The purpose of this article is to provide an overview on the currently available sequences and techniques for assessment of pulmonary nodules and analyzes the clinical significance according to the current literature. The main focus is on the detection of lung metastases, the detection of primary pulmonary malignancies in high-risk individuals and the differentiation between pulmonary nodules of benign and malignant character. The MRI technique has a sensitivity of approximately 80 % for detection of malignant pulmonary nodules compared to the reference standard low-dose computed tomography (CT) and is thus somewhat inferior to CT. Advantages of MRI on the other hand are a higher specificity in differentiating malignant and benign pulmonary nodules and the absence of ionizing radiation exposure. A systematic use of MRI as a primary tool for detection and characterization of pulmonary nodules is currently not recommended due to insufficient data. The diagnostic potential of MRI for early detection and staging of malignant pulmonary diseases, however, seems promising. Therefore, further evaluation of MRI as a secondary imaging modality in clinical trials is highly warranted. (orig.)

11

Remote detection of explosives using trained canines  

International Nuclear Information System (INIS)

Use of dogs is a search method which combines high probability of detection, speed of search, and low cost. It was concluded that the canine could be used for explosive screening of personnel, but that it was imperative that the dog be in a position remote from employees and employee traffic. A study was made of the design of booths and air flow for this purpose. Results of tests and conclusions are given and discussed

12

DETECTION OF TUMOR IN MRI USING VECTOR QUANTIZATION SEGMENTATION  

Directory of Open Access Journals (Sweden)

Full Text Available Magnetic Resonance Imaging (MRI is the state-of-the-art medical imaging technology which allows cross sectional view of the body with unprecedented tissue contrast. MRI plays an important role in assessing pathological conditions of the ankle, foot and brain. It has rapidly evolved into an accepted modality for medical imaging ofdisease processes in the musculoskeletal system, especially the foot and brain due to the use of non-ionizing radiation. MRI provides a digital representation of tissue characteristic that can be obtained in any tissue plane. The images produced by an MRI scanner are best described as slices through the brain. MRI has the added advantage ofbeing able to produce images which slice through the brain in both horizontal and vertical planes. This paper presents a vector quantization segmentation method to detect cancerous mass from MRI images. In order to increase radiologist’s diagnostic performance, computer-aided diagnosis (CAD scheme have been developed to improve the detection of primary signatures of this disease: masses and microcalcifications.

Dr. H. B. Kekre

2010-08-01

13

Automated detection of multiple sclerosis lesions in serial brain MRI  

International Nuclear Information System (INIS)

Multiple sclerosis (MS) is a serious disease typically occurring in the brain whose diagnosis and efficacy of treatment monitoring are vital. Magnetic resonance imaging (MRI) is frequently used in serial brain imaging due to the rich and detailed information provided. Time-series analysis of images is widely used for MS diagnosis and patient follow-up. However, conventional manual methods are time-consuming, subjective, and error-prone. Thus, the development of automated techniques for the detection and quantification of MS lesions is a major challenge. This paper presents an up-to-date review of the approaches which deal with the time-series analysis of brain MRI for detecting active MS lesions and quantifying lesion load change. We provide a comprehensive reference source for researchers in which several approaches to change detection and quantification of MS lesions are investigated and classified. We also analyze the results provided by the approaches, discuss open problems, and point out possible future trends. Lesion detection approaches are required for the detection of static lesions and for diagnostic purposes, while either quantification of detected lesions or change detection algorithms are needed to follow up MS patients. However, there is not yet a single approach that can emerge as a standard for the clinical practice, automatically providing an accurate MS lesion evolution quantification. Future trends will focus on combining the lesion detection in sins on combining the lesion detection in single studies with the analysis of the change detection in serial MRI. (orig.)

14

Detecting breast microcalcifications with high-field MRI.  

Science.gov (United States)

The aim of this study was to detect microcalcifications in human whole breast specimens using high-field MRI. Four mastectomy specimens, obtained with approval of the institutional review board, were subjected to gradient-echo MRI acquisitions on a high-field MR scanner. The phase derivative was used to detect microcalcifications. The echo time and imaging resolution were varied to study the sensitivity of the proposed method. Computed tomography images of the mastectomy specimens and prior acquired mammography images were used to validate the results. A template matching algorithm was designed to detect microcalcifications automatically. The three spatial derivatives of the signal phase surrounding a field-perturbing object allowed three-dimensional localization, as well as the discrimination of diamagnetic field-perturbing objects, such as calcifications, and paramagnetic field-perturbing structures, e.g. blood. A longer echo time enabled smaller disturbances to be detected, but also resulted in shading as a result of other field-disturbing materials. A higher imaging resolution increased the detection sensitivity. Microcalcifications in a linear branching configuration that spanned over 8 mm in length were detected. After manual correction, the automatic detection tool identified up to 18 microcalcifications within the samples, which was in close agreement with the number of microcalcifications found on previously acquired in vivo mammography images. Microcalcifications can be detected by MRI in human whole breast specimens by the application of phase derivative imaging. PMID:24535752

de Leeuw, Hendrik; Stehouwer, Bertine L; Bakker, Chris J G; Klomp, Dennis W J; van Diest, Paul J; Luijten, Peter R; Seevinck, Peter R; van den Bosch, Maurice A A J; Viergever, Max A; Veldhuis, Wouter B

2014-05-01

15

Detection and size of pulmonary lesions: how accurate is MRI? A prospective comparison of CT and MRI  

International Nuclear Information System (INIS)

Background. Although CT is the modality of choice for morphological lung imaging, an increasing proportion of chest imaging is performed by MRI due to the utilization of whole-body MRI. Therefore, the diagnostic performance of MRI in reliably detecting pulmonary lesions should be established. Purpose. To investigate the detection rate of pulmonary lesions by MRI that can be expected in a clinical setting and to assess the accuracy of lesion measurement by MRI compared to CT. Material and Methods. Twenty-eight patients (median age 66 years) with indication for CT imaging due to suspected thoracic malignancy were prospectively included. Chest MRI performed on the same day as CT, comprised unenhanced TrueFisp, ecg-gated T2-weighted HASTE, T1-weighted VIBE, and contrast-enhanced T1-weighted, fat-saturated VIBE sequences. MR sequences were evaluated for lesion detection by two readers independently and measurement of lesion size was performed. MR findings were correlated with CT. Results. One hundred and eight pulmonary lesions (20 thoracic malignancies, 88 lung nodules) were detected by CT in 26 patients. Lesions were ruled out in two patients. All thoracic malignancies were identified by MRI with strong correlation (r 0.97-0.99; P 1 cm in diameter. If a lung lesion is detected by MRI, it is a reliable finding and its measurement is accurate. CT remains superior in detecting small lung nodules (<6 mm). Detection rate of MRI for small lesions is improved using a multi-sequence protocol including contrast administration

16

Stress cine MRI for detection of coronary artery disease  

International Nuclear Information System (INIS)

Stress testing is the cornerstone in the diagnosis of patients with suspected coronary artery disease (CAD). Stress echocardiography has become a well-established modality for the detection of ischemia-induced wall motion abnormalities. However, display and reliable interpretation of stress echocardiography studies are user-dependent, the test reproducibility is low, and 10 to 15% of patients yield suboptimal or non-diagnostic images. Due to its high spatial and contrast resolution, MRI is known to permit an accurate determination of left ventricular function and wall thickness at rest. Early stress MRI studies provided promising results with respect to the detection of CAD. However, the clinical impact was limited due to long imaging time and problematic patient monitoring in the MRI environment. Recent technical improvements - namely ultrafast MR image acquisition - led to a significant reduction of imaging time and improved patient safety. Stress can be induced by physical exercise or pharmacologically by administration of a beta1-agonist (dobutamine) or vasodilatator (dipyridamole and adenosine). The best developed and most promising stress MRI technique is a high-dose dobutamine/atropine stress protocol (10, 20, 30, 40 ?g/kg/min; optionally 0.25-mg fractions of atropine up to maximal dose 1 mg). Severe complications (myocardial infarction, ventricular fibrillation and sustained tachycardia, cardiogenic shock) may be expected in 0.25% of patients. Currently, data of three high-dose dobutamine stress MRI studies are available, revealing a good sensitivity (83 - 87%) and specificity (83 - 86%) in the assessment of CAD. The direct comparison between echocardiography and MRI for the detection of stress-induced wall motion abnormalities yielded better results for dobutamine-MRI in terms of sensitivity (86.2% vs. 74.3%; p < 0.05) and specificity (85.7% vs. 69.8% p < 0.05) as compared to dobutamine stress echocardiography. The superior results of MRI can mainly be explained by the better image quality with sharp delineation of the endocardial and epicardial borders. Currently, stress MRI is already a realistic clinical alternative for the non-invasive assessment of CAD in patients with impaired image quality in echocardiography. (orig.)

17

Detection of brain metastases from lung cancer by CT and MRI  

International Nuclear Information System (INIS)

To compare the detectability of brain metastases from lung cancer, both CT and MRI were performed on all patients. Thirty-two lung cancer patients with brain metastases admitted from December 1990 to June 1994 were examined by CT and MRI using contrast enhancement. Six radiologists individually evaluated CT and MRI films for brain metastases. In 3 of 32 cases, multiple small metastatic lesions which could not be detected on CT were detected on MRI. In 29 of the 32 cases, 56 metastatic lesions were detected on CT, whereas 103 lesions were detected on MRI. There were no lesions that were detected only by CT and were not detected by MRI. MRI was superior to CT for determining small lesions less than 9 mm and inferior tentorial lesions. As a result, we consider that CT is not sufficiently effective for detecting brain metastases of lung cancer, and that MRI is now indispensable. (author)

18

Detection of brain metastases from lung cancer by CT and MRI  

Energy Technology Data Exchange (ETDEWEB)

To compare the detectability of brain metastases from lung cancer, both CT and MRI were performed on all patients. Thirty-two lung cancer patients with brain metastases admitted from December 1990 to June 1994 were examined by CT and MRI using contrast enhancement. Six radiologists individually evaluated CT and MRI films for brain metastases. In 3 of 32 cases, multiple small metastatic lesions which could not be detected on CT were detected on MRI. In 29 of the 32 cases, 56 metastatic lesions were detected on CT, whereas 103 lesions were detected on MRI. There were no lesions that were detected only by CT and were not detected by MRI. MRI was superior to CT for determining small lesions less than 9 mm and inferior tentorial lesions. As a result, we consider that CT is not sufficiently effective for detecting brain metastases of lung cancer, and that MRI is now indispensable. (author)

Nakamura, Tetsu; Ohno, Yoshiharu [Kobe Univ. (Japan). School of Medicine; Endo, Masahiro [and others

1996-08-01

19

Fast and direct detection of neuronal activation with diffusion MRI  

Energy Technology Data Exchange (ETDEWEB)

Over the last 30 years functional neuroimaging has emerged as a revolutionary path to study the brain and the mind. This has been possible because of significant advances mainly in two imaging modalities, namely Positron Emission Tomograph y (PET) and Magnetic Resonance Imaging (MRI). Amazingly, although those two modalities are based on radically different physical approaches (detection of 1 3 radioactivity for the first one and nuclear magnetization for the second), both allo w brain activation images to be obtained through measurements involving water molecules. So far, PET and MRI functional imaging have relied on the same principle that neuronal activation and blood flow are coupled through metabolism: Blood flow increases locally in activated brain regions. In the case of PET one uses H{sub 2}O radioactive water which is produced by using a cyclotron and injected to the subject vasculature. In activated brain regions the increase in blood flow leads to a local increase in the tissue radioactive water content detected and localized by the PE T camera. With MRI the hydrogen nuclei of brain endogenous water molecules are magnetized by a strong external magnetic field. In activated regions the increase in blood flow results in an increase of blood oxygenation which induces a slight perturbation of the magnetization relaxation properties of the water molecules around blood vessels detected by the MRI scanner (so called 'BOLD' effect). I n both approaches water is, thus, merely an indirect means to look at changes in cerebral blood flow which accompany brain activation, and although PET and BOLD f MRI have been extremely successful for the functional neuroimaging community, present well known limitations. While the coupling between neuronal activation, metabolism and blood flow has been verified in most instances including BOLD f MRI, the degree and the mechanism of coupling remains largely debated (Magistratt, Pellerin, Mangia) and may fail in some pathological conditions or in the presence of drugs. Also, it has been pointed out that the spatial functional resolution of vascular based functional neuroimaging might be limited, because vessels responsible for the increase of blood flow and blood volume feed or drain somewhat large territories which include clusters of neurons with potentially different functions. Similarly the physiological delay necessary for the mechanisms triggering the vascular response to work intrinsically limits the temporal resolution of BOLD f MRI. On the other hand, a fundamentally new paradigm is being proposed to look at brain activity through the observation with MRI of the diffusion behavior of the water molecules. It has been shown that the diffusion of water slightly slows down during brain activation. This slowdown, which occurs several seconds before the hemodynamic response detected by BOLD f MRI, has been described in terms of a phase transition of the water molecules in the cells undergoing activation and tentatively attributed to the swelling of those cells. This finding marks a significant departure from the former blood flow based PET and MRI approaches, and potentially offers improved spatial and temporal resolution, because the proposed mechanism appears more intimately linked to neuronal activation. However, the step might even extend further: Contrarily to the former approaches based on changes in artificially induced water physical properties, namely radioactivity and magnetization, required for the external PET or MR I detection, the new, diffusion based approach, merely uses MRI as a means to reveal changes in intrinsic water physical properties. These changes in the diffusion behaviour of water during activation seem to belong to an endogenous part of the activation process, and perhaps even more, could be an active component of this process that evolution has capitalized upon. The aim of this presentation is to review our current knowledge on the water physical properties i n biological tissues, which could be relevant to diffusion f MRI, and to review the bioph

Le Bihan, D. [Service Hospitalier Frederic Joliot (CEA/DSV/DRM), Lab. Anatomical and Functional Neuroimaging, 91 - Orsay (France); Urayama, S.; Aso, T.; Hanakawa, T.; Fukuyama, H. [Kyoto Univ. Graduate School of Medicine, Human Brain Research Center, Kyoto (Japan)

2006-07-01

20

Information fusion approach for detection of brain structures in MRI  

Science.gov (United States)

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

Shademan, Azad; Soltanian-Zadeh, Hamid

2002-05-01

 
 
 
 
21

Semiparametric detection of significant activation for brain fMRI  

CERN Document Server

Functional magnetic resonance imaging (fMRI) aims to locate activated regions in human brains when specific tasks are performed. The conventional tool for analyzing fMRI data applies some variant of the linear model, which is restrictive in modeling assumptions. To yield more accurate prediction of the time-course behavior of neuronal responses, the semiparametric inference for the underlying hemodynamic response function is developed to identify significantly activated voxels. Under mild regularity conditions, we demonstrate that a class of the proposed semiparametric test statistics, based on the local linear estimation technique, follow $\\chi^2$ distributions under null hypotheses for a number of useful hypotheses. Furthermore, the asymptotic power functions of the constructed tests are derived under the fixed and contiguous alternatives. Simulation evaluations and real fMRI data application suggest that the semiparametric inference procedure provides more efficient detection of activated brain areas than ...

Zhang, Chunming

2008-01-01

22

Squid detected NMR and MRI at ultralow fields  

Science.gov (United States)

Nuclear magnetic resonance (NMR) signals are detected in microtesla fields. Prepolarization in millitesla fields is followed by detection with an untuned dc superconducting quantum interference device (SQUID) magnetometer. Because the sensitivity of the SQUID is frequency independent, both signal-to-noise ratio (SNR) and spectral resolution are enhanced by detecting the NMR signal in extremely low magnetic fields, where the NMR lines become very narrow even for grossly inhomogeneous measurement fields. MRI in ultralow magnetic field is based on the NMR at ultralow fields. Gradient magnetic fields are applied, and images are constructed from the detected NMR signals.

Clarke, John (Berkeley, CA); Pines, Alexander (Berkeley, CA); McDermott, Robert F. (Monona, WI); Trabesinger, Andreas H. (London, GB)

2008-12-16

23

Reporting and management of breast lesions detected using MRI  

Energy Technology Data Exchange (ETDEWEB)

Magnetic resonance imaging (MRI) is the most accurate technique for diagnosing and delineating the extent of both invasive and in-situ breast cancer and is increasingly being used as part of the preoperative work-up to assess the local extent of disease. It is proving invaluable in providing information that allows successful single-stage surgery. An inevitable consequence of the high sensitivity of MRI is that it will identify additional lesions that may or may not represent significant extra disease. This may complicate and delay the preoperative process. This paper outlines a strategy for managing MRI-detected lesions to optimize the benefits of breast MRI as a local staging tool while minimizing the false-positive diagnoses. It discusses the importance of good technique to reduce the number of indeterminate lesions. Methods to refine the patient pathway to minimize delays are discussed. The format of MRI reporting is discussed in detail as is the usefulness of discussion of cases at multidisciplinary meetings. Illustrative cases are used to clarify the points made.

Dall, B.J.G., E-mail: Barbara.dall@leedsth.nhs.uk [Department of Radiology, Leeds General Infirmary, Leeds (United Kingdom); Vinnicombe, S. [Department of Radiology, St Bartholomew' s Hospital, London (United Kingdom); Gilbert, F.J. [Aberdeen Biomedical Imaging Centre, Aberdeen (United Kingdom)

2011-12-15

24

White matter injury detection in neonatal MRI  

Science.gov (United States)

Early detection of white matter injury in premature newborns can facilitate timely clinical treatments reducing the potential risk of later developmental deficits. It was reported that there were more than 5% premature newborns in British Columbia, Canada, among which 5-10% exhibited major motor deficits and 25-50% exhibited significant developmental and visual deficits. With the advancement of computer assisted detection systems, it is possible to automatically identify white matter injuries, which are found inside the grey matter region of the brain. Atlas registration has been suggested in the literature to distinguish grey matter from the soft tissues inside the skull. However, our subjects are premature newborns delivered at 24 to 32 weeks of gestation. During this period, the grey matter undergoes rapid changes and differs significantly from one to another. Besides, not all detected white spots represent injuries. Additional neighborhood information and expert input are required for verification. In this paper, we propose a white matter feature identification system for premature newborns, which is composed of several steps: (1) Candidate white matter segmentation; (2) Feature extraction from candidates; (3) Validation with data obtained at a later stage on the children; and (4) Feature confirmation for automated detection. The main challenge of this work lies in segmenting white matter injuries from noisy and low resolution data. Our approach integrates image fusion and contrast enhancement together with a fuzzy segmentation technique to achieve promising results. Other applications, such as brain tumor and intra-ventricular haemorrhage detection can also benefit from our approach.

Cheng, Irene; Hajari, Nasim; Firouzmanesh, Amirhossein; Shen, Rui; Miller, Steven; Poskitt, Ken; Basu, Anup

2013-02-01

25

Fast and direct detection of neuronal activation with diffusion MRI  

International Nuclear Information System (INIS)

BOLD' effect). I n both approaches water is, thus, merely an indirect means to look at changes in cerebral blood flow which accompany brain activation, and although PET and BOLD f MRI have been extremely successful for the functional neuroimaging community, present well known limitations. While the coupling between neuronal activation, metabolism and blood flow has been verified in most instances including BOLD f MRI, the degree and the mechanism of coupling remains largely debated (Magistratt, Pellerin, Mangia) and may fail in some pathological conditions or in the presence of drugs. Also, it has been pointed out that the spatial functional resolution of vascular based functional neuroimaging might be limited, because vessels responsible for the increase of blood flow and blood volume feed or drain somewhat large territories which include clusters of neurons with potentially different functions. Similarly the physiological delay necessary for the mechanisms triggering the vascular response to work intrinsically limits the temporal resolution of BOLD f MRI. On the other hand, a fundamentally new paradigm is being proposed to look at brain activity through the observation with MRI of the diffusion behavior of the water molecules. It has been shown that the diffusion of water slightly slows down during brain activation. This slowdown, which occurs several seconds before the hemodynamic response detected by BOLD f MRI, has been described in terms of a phase transition of the water molecules in the cells undergoing activation and tentatively attributed to the swelling of those cells. This finding marks a significant departure from the former blood flow based PET and MRI approaches, and potentially offers improved spatial and temporal resolution, because the proposed mechanism appears more intimately linked to neuronal activation. However, the step might even extend further: Contrarily to the former approaches based on changes in artificially induced water physical properties, namely radioactivity and magnetization, required for the external PET or MR I detection, the new, diffusion based approach, merely uses MRI as a means to reveal changes in intrinsic water physical properties. These changes in the diffusion behaviour of water during activation seem to belong to an endogenous part of the activation process, and perhaps even more, could be an active component of this process that evolution has capitalized upon. The aim of this presentation is to review our current knowledge on the water physical properties i n biological tissues, which could be relevant to diffusion f MRI, and to review the biophysical mechanisms underlying brain activation to shed light on their intimacy with the physical properties of water, the 'molecule of the mind'? (author)

26

Detection of colorectal liver metastases: a prospective multicenter trial comparing unenhanced MRI, MnDPDP-enhanced MRI, and spiral CT  

Energy Technology Data Exchange (ETDEWEB)

The aim of this study was to compare unenhanced MRI, MnDPDP-enhanced MRI, and spiral CT in the detection of hepatic colorectal metastases. Forty-four patients with hepatic colorectal metastases were examined with unenhanced and MnDPDP-enhanced MRI and with unenhanced and contrast-enhanced spiral CT. The MR examination protocol included baseline T1-weighted spin-echo (SE), T1-weighted gradient-recalled-echo (GRE), and T2-weighted fast-SE sequences; and T1-weighted SE and T1-weighted GRE sequences obtained 30-60 min after administration of 0.5 {mu}mol/kg (0.5 ml/kg) mangafodipir trisodium (MnDPDP). Images were interpreted by three blinded readers. Findings at CT and MRI were compared with those at intraoperative US, which were used as term of reference. Intraoperative US detected 128 metastases. In a lesion-by-lesion analysis, the overall detection rate was 71% (91 of 128) for spiral CT, 72% (92 of 128) for unenhanced MRI, and 90% (115 of 128) for MnDPDP-enhanced MRI. MnDPDP-enhanced MRI was more sensitive than either unenhanced MRI (p<0.0001) or spiral CT (p=0.0007). In a patient-by-patient analysis, agreement with gold standard was higher for MnDPDP-enhanced MRI (33 of 44 cases) than for spiral CT (22 of 44 cases, p=0.0023) and unenhanced MRI (21 of 44 cases, p=0.0013). MnDPDP-enhanced MRI is superior to unenhanced MRI and spiral CT in the detection of hepatic colorectal metastases. (orig.)

Bartolozzi, Carlo; Donati, Francescamaria; Cioni, Dania; Lencioni, Riccardo [Department of Radiology, University of Pisa, Via Roma 67, 56100, Pisa (Italy); Procacci, Carlo; Morana, Giovanni [Department of Radiology, University of Verona, Piazzale L.A. Scuro 1, 37134, Verona (Italy); Chiesa, Antonio; Grazioli, Luigi [Department of Radiology, University of Brescia, Piazzale Spedali Civili 1, 25023, Brescia (Italy); Cittadini, Giorgio; Cittadini, Giuseppe [Department of Radiology, University of Genova, Largo R. Benzi 10, 16132, Genova (Italy); Giovagnoni, Andrea [Department of Radiology, University of Ancona, Concam, Torrette, 60020, Ancona (Italy); Gandini, Giovanni; Maass, Jochen [Department of Radiology, University of Torino, Genova 3, 10110, Torino (Italy)

2004-01-01

27

Detection of colorectal liver metastases: a prospective multicenter trial comparing unenhanced MRI, MnDPDP-enhanced MRI, and spiral CT  

International Nuclear Information System (INIS)

The aim of this study was to compare unenhanced MRI, MnDPDP-enhanced MRI, and spiral CT in the detection of hepatic colorectal metastases. Forty-four patients with hepatic colorectal metastases were examined with unenhanced and MnDPDP-enhanced MRI and with unenhanced and contrast-enhanced spiral CT. The MR examination protocol included baseline T1-weighted spin-echo (SE), T1-weighted gradient-recalled-echo (GRE), and T2-weighted fast-SE sequences; and T1-weighted SE and T1-weighted GRE sequences obtained 30-60 min after administration of 0.5 ?mol/kg (0.5 ml/kg) mangafodipir trisodium (MnDPDP). Images were interpreted by three blinded readers. Findings at CT and MRI were compared with those at intraoperative US, which were used as term of reference. Intraoperative US detected 128 metastases. In a lesion-by-lesion analysis, the overall detection rate was 71% (91 of 128) for spiral CT, 72% (92 of 128) for unenhanced MRI, and 90% (115 of 128) for MnDPDP-enhanced MRI. MnDPDP-enhanced MRI was more sensitive than either unenhanced MRI (p<0.0001) or spiral CT (p=0.0007). In a patient-by-patient analysis, agreement with gold standard was higher for MnDPDP-enhanced MRI (33 of 44 cases) than for spiral CT (22 of 44 cases, p=0.0023) and unenhanced MRI (21 of 44 cases, p=0.0013). MnDPDP-enhanced MRI is superior to unenhanced MRI and spiral CT in the detection of hepatic colorectal metastases. (orig.)

28

Detection of Prodromal Alzheimer's Disease via Pattern Classification of MRI  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report evidence that computer-based high-dimensional pattern classification of MRI detects patterns of brain structure characterizing mild cognitive impairment (MCI), often a prodromal phase of Alzheimer's Disease (AD). 90% diagnostic accuracy was achieved, using cross-validation, for 30 participants in the Baltimore Longitudinal Study of Aging. Retrospective evaluation of serial scans obtained during prior years revealed gradual increases in structural abnormality for the MCI group, often...

Davatzikos, Christos; Fan, Yong; Wu, Xiaoying; Shen, Dinggang; Resnick, Susan M.

2008-01-01

29

MRI  

Medline Plus

Full Text Available Magnetic Resonance Imaging Scan (MRI) Introduction An MRI scan, or magnetic resonance imaging scan, is a test that provides very clear pictures of structures inside the body. Doctors may recommend an MRI ...

30

MRI  

Medline Plus

Full Text Available Magnetic Resonance Imaging Scan (MRI) Introduction An MRI scan, or magnetic resonance imaging scan, is a test that provides very ... and risks of this procedure. Test A Magnetic Resonance Imaging scan, known as an MRI scan or ...

31

MRI  

Medline Plus

Full Text Available Magnetic Resonance Imaging Scan (MRI) Introduction An MRI scan, or magnetic resonance imaging scan, is a test that provides ... benefits and risks of this procedure. Test A Magnetic Resonance Imaging scan, known as an MRI scan ...

32

Error detection failures in schizophrenia: ERPs and fMRI  

Science.gov (United States)

Self-monitoring of actions, critical for guiding goal-directed behavior, is deficient in schizophrenia. Defective error-monitoring may reflect more general self-monitoring deficiencies. The error-related negativity (ERN) component of the event-related potential (ERP) is smaller in patients with schizophrenia, and anterior cingulate cortex (ACC) and dorsolateral pre-frontal cortex (DLPFC), both critical for error detection, are less responsive to errors in patients with schizophrenia, as revealed with functional magnetic resonance imaging (fMRI). ERP and fMRI data were collected while 11 patients with schizophrenia and 10 healthy controls performed a Go-NoGo task requiring a button press to Xs (p=.88) while withholding responses to Ks (p=.12). We measured the ERN and ACC and DLPFC activations to false alarms. The task elicited a robust ERN and modest activations in ACC and DLPFC to false alarms. As expected, ERN was larger in controls than patients. However, ACC and DLPFC activations were not greater in controls than patients. Surprisingly, DLPFC was more activated by errors in patients than controls. ERPs may be superior for assessing error processing because (1) ERNs can be measured precisely without needing to control for the multiple comparisons of fMRI, and (2) ERPs have the temporal precision to detect transient activity necessary for error detection and on-the-fly behavioral adjustments. PMID:19414043

Ford, Judith M.; Jorgensen, Kasper W.; Roach, Brian J.; Mathalon, Daniel H.

2009-01-01

33

Quantitative MRI can detect subclinical disease progression in muscular dystrophy.  

Science.gov (United States)

Oculopharyngeal muscular dystrophy (OPMD) is a rare autosomal dominant muscular dystrophy with late onset and slow progression. The aim of this study was to compare different methods of quantitative MRI in the follow-up of OPMD to semiquantitative evaluation of MRI images and to functional parameters. We examined 8 patients with genetically confirmed OPMD and 5 healthy volunteers twice at an interval of 13 months. Motor function measurements (MFM) were assessed. Imaging at 1.5 T (Siemens Magnetom Avanto) comprised two axial slice groups at the largest diameter of thigh and calf and included T1w TSE, 2-point Dixon for muscular fat fraction (MFF) and a multi-contrast TSE sequence to calculate quantitative T2 values. T1 images were analyzed using Fischer's semiquantitative 5-point (0–4) scale. MFM and visual scores showed no significant difference over the study period. Overall T2 values increased in patients over the study period from 49.4 to 51.6 ms, MFF increased from 19.2 to 20.7%. Neither T2 values nor MFF increased in controls. Changes in T2 correlated with the time interval between examinations (r 2 = 0.42). In this small pilot trial, it was shown that quantitative muscle MRI can detect subclinical changes in patients with OPMD. Quantitative MRI might, therefore, be a useful tool for monitoring disease progression in future therapeutic trials. PMID:22297459

Fischmann, Arne; Hafner, Patricia; Fasler, Susanne; Gloor, Monika; Bieri, Oliver; Studler, Ueli; Fischer, Dirk

2012-08-01

34

MRI  

... MRI magnetic MRI Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to produce an image that is dependent on the ...Education I am a teacher Resources for the classroom Teaching Medical Physics MRI I am a teacher Resources for the classroom Teaching Medical Physics ...Pulse oximeters Ultrasound scans X-ray imaging Electrocardiograms Gamma camera PET MRI MRI Magnetic resonance imaging (MRI) uses magnetic fields and radio waves ... Another distinguishing feature of MRI, especially when compared to techniques that use ionising radiation such as X-ray or gamma imaging is that ...

35

Novel Miniature Spectrometer For Remote Chemical Detection  

International Nuclear Information System (INIS)

New chemical sensing technologies are critically important for addressing many of EM's priority needs as discussed in detail at http://emsp.em.doe.gov/needs. Many technology needs were addressed by this research. For example, improved detection strategies are needed for non-aqueous phase liquids (NAPL's), such as PCE (Cl2C=CCl2) and TCE (HClC=CCl2), which persist in the environment due their highly stable structures. By developing a miniature, ultra-sensitive, selective, and field-deployable detector for NAPL's, the approximate source location could be determined with minimal investigative expense. Contaminant plumes could also be characterized in detail. The miniature spectrometer developed under Project No.60231 could also permit accurate rate measurements in less time, either in the field or the laboratory, which are critically important in the development, testing, and ultimate utilization of models for describing contaminant transport. The technology could also be used for long-term groundwater monitoring or long-term stewardship in general. Many science needs are also addressed by the Project 60231, since the effort significantly advances the measurement science of chemical detection. Developed under Project No.60231, evanescent wave cavity ring-down spectroscopy (EW-CRDS) is a novel form of CRDS, which is an the emerging optical absorption technique. Several review articles on CRDS, which has been generally applied only to gas-phase diagnostics, have been publi to gas-phase diagnostics, have been published1-3. EW-CRDS4-10 forms the basis for a new class of chemical sensors that extends CRDS to other states of matter and leads to a miniaturized version of the concept. EW-CRDS uses miniature solid-state optical resonators that incorporate one or more total internal reflection (TIR) surfaces, which create evanescent waves. The evanescent waves emanate from the TIR surfaces, sampling the surrounding medium. The utility of evanescent waves in chemical analysis forms the basis for the field of attenuated total reflectance (ATR)11 spectroscopy. Many diagnostic problems can be solved by ATR methods that are intractable by ordinary methods, but ATR typically lacks sensitivity for ultra-trace chemical detection. In EWCRDS, the ring-down time of a resonator sensitively responds to chemical species present in the evanescent wave thereby combining the advantages of ATR with the sensitivity of CRDS. Furthermore, EW-CRDS forms the basis for a rugged miniature chemical sensor for which the laser source and photodetector can be located remotely by using optical fiber. Work on EW-CRDS began at NIST with the NRC postdoctoral associateship of the current Principal Investigator during fiscal 1996-1997. Since completion of the NRC associateship, work on EW-CRDS has been majority funded through Project 60231, with some additional funding from the Advanced Technology Program (35K/year in 2000)

36

Research on Remote Network Bidirectional Detect and Control Model  

Directory of Open Access Journals (Sweden)

Full Text Available Remote network bidirectional detect and control technologies are the key factors to solve local network allopatry expansibility and management. With studying gateway integration technology, bidirectional VPN technology, identity authentication technology and dynamic host management technology can be integrated into gateway. Thus, bidirectional connect and control among allopatry local networks based on Internet can be solved. Whole area expansibility of local network is realized. With experiment, the model is proved to finish remote bidirectional interconnection of local network automatically and to obtain allopatry local users authority. The equipment detecting and controlling in remote local networks are realized.  

Hongyao Ju

2013-09-01

37

Novel Miniature Spectrometer for Remote Chemical Detection  

International Nuclear Information System (INIS)

A entirely new class of chemical sensors is being developed that will enable qualitative and quantitative remote, real-time, optical diagnostics of chemical species in hazardous gas, liquid, and semi-solid phases through a completely novel implementation of cavity ring-down spectroscopy. The sensor design uses a tiny, solid block (< 1cm3) of ultra-high purity optical material that is fabricated into a regular, planar polygon with a single convex facet to form a total-internal-reflection (TIR) ring minicavity. The lifetime of a light pulse that is injected into the cavity is extremely sensitive to chemical species in contact with the cavity. By using optical fiber to remotely locate the light source and detector, this new technology will permit high-sensitivity, remote chemical sensing with a rugged, cost-effective device

38

Development of remote surgical navigation and biopsy needle guidance system using Open-MRI and high-speed network  

Science.gov (United States)

This study describes a remote surgical guidance and navigation system developed for surgery using "Open-MRI" and high-speed network. We connected Osaka University Hospital and Kawasaki Hospital which has deployed Open- MRI with high speed IP over ATM network. The distance between two hospitals is approximately 50 km. Two video cameras were installed with an angle of 40 degrees on an open-MRI gantry to obtain intraoperative images. Two pairs of CODEC (AD/DA converter) were equipped on the network to transfer both images and sound in real time. A pointer system to indicate a region on an image was also developed. MRI images obtained by Open-MRI were transferred to a 3D workstation in Osaka University Hospital. The system was designed for a senior surgeon in Osaka University to advise regarding accurate needle direction for a remote patient by checking the reconstructed 3D images and schemata shown by the navigation software. The schemata were also superimposed on intraoperative images from two cameras, and the superimposed images were sent back to Kawasaki Hospital. This system allowed a surgeon in the operation room at Kawasaki Hospital to accurately view navigation schema under supervision by a senior surgeon in a remote university hospital with superimposion of intraoperative images. The pointer system allowed both doctors to share intraoperative images during a virtual-real surgical operation. A successful biopsy case using this newly developed system illustrates the effectiveness of this system.

Okura, Yasuhiko; Matsumura, Yasushi; Kuwata, Shigeki; Takeda, Hiroshi

2004-05-01

39

FDG-PET Lacks Sufficient Sensitivity to Detect Myxoid Liposarcoma Spinal Metastases Detected by MRI  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose. To document a case of myxoid liposarcoma in which PET scan was less sensitive than MRI in detecting spinal metastasis. Materials and Methods. The case of a 65-year-old female with a history of myxoid liposarcoma (MLS of the thigh resected 5 years previously and now presenting with low back pain is presented. Her medical oncologist ordered an FDG-PET scan to evaluate distant recurrence. Subsequently, an MRI of her spine was obtained by her surgeon. Results. The FDG-PET scan was obtained 1 week prior to the MRI, and it did not show increased glucose uptake in the spine. Her MRI did show increased signal intensity in her lumbar spine. CT needle biopsy confirmed the lesion to be metastatic MLS. Conclusion. FDG-PET scans are utilized to detect distant recurrence of cancerous lesions. Myxoid liposarcoma has a unique propensity to metastasize to the spine. Previous reports have documented the unreliability of bone scintigraphy to diagnose these metastases. Our report demonstrates that FDG-PET may also lack the sensitivity needed to detect these lesions. We advocate total spine MRI when screening for metastases in this population when they present with back pain.

Joseph H. Schwab

2007-05-01

40

MRI  

Medline Plus

Full Text Available ... Complications MRI scans are very safe. Because MRI technology is relatively recent, the very long-term effects ... can help avoid potentially deadly complications. Because medical technology is continuously improving, biomedical companies are manufacturing more ...

 
 
 
 
41

Computer-aided detection of prostate cancer in MRI.  

Science.gov (United States)

Prostate cancer is one of the major causes of cancer death for men in the western world. Magnetic resonance imaging (MRI) is being increasingly used as a modality to detect prostate cancer. Therefore, computer-aided detection of prostate cancer in MRI images has become an active area of research. In this paper we investigate a fully automated computer-aided detection system which consists of two stages. In the first stage, we detect initial candidates using multi-atlas-based prostate segmentation, voxel feature extraction, classification and local maxima detection. The second stage segments the candidate regions and using classification we obtain cancer likelihoods for each candidate. Features represent pharmacokinetic behavior, symmetry and appearance, among others. The system is evaluated on a large consecutive cohort of 347 patients with MR-guided biopsy as the reference standard. This set contained 165 patients with cancer and 182 patients without prostate cancer. Performance evaluation is based on lesion-based free-response receiver operating characteristic curve and patient-based receiver operating characteristic analysis. The system is also compared to the prospective clinical performance of radiologists. Results show a sensitivity of 0.42, 0.75, and 0.89 at 0.1, 1, and 10 false positives per normal case. In clinical workflow the system could potentially be used to improve the sensitivity of the radiologist. At the high specificity reading setting, which is typical in screening situations, the system does not perform significantly different from the radiologist and could be used as an independent second reader instead of a second radiologist. Furthermore, the system has potential in a first-reader setting. PMID:24770913

Litjens, Geert; Debats, Oscar; Barentsz, Jelle; Karssemeijer, Nico; Huisman, Henkjan

2014-05-01

42

Hemorrhage detection in MRI brain images using images features  

Science.gov (United States)

The abnormalities appear frequently on Magnetic Resonance Images (MRI) of brain in elderly patients presenting either stroke or cognitive impairment. Detection of brain hemorrhage lesions in MRI is an important but very time-consuming task. This research aims to develop a method to extract brain tissue features from T2-weighted MR images of the brain using a selection of the most valuable texture features in order to discriminate between normal and affected areas of the brain. Due to textural similarity between normal and affected areas in brain MR images these operation are very challenging. A trauma may cause microstructural changes, which are not necessarily perceptible by visual inspection, but they could be detected by using a texture analysis. The proposed analysis is developed in five steps: i) in the pre-processing step: the de-noising operation is performed using the Daubechies wavelets; ii) the original images were transformed in image features using the first order descriptors; iii) the regions of interest (ROIs) were cropped from images feature following up the axial symmetry properties with respect to the mid - sagittal plan; iv) the variation in the measurement of features was quantified using the two descriptors of the co-occurrence matrix, namely energy and homogeneity; v) finally, the meaningful of the image features is analyzed by using the t-test method. P-value has been applied to the pair of features in order to measure they efficacy.

Moraru, Luminita; Moldovanu, Simona; Bibicu, Dorin; Stratulat (Visan), Mirela

2013-11-01

43

Differential Geometric Approach to Change Detection Using Remotely Sensed Images  

Directory of Open Access Journals (Sweden)

Full Text Available Change Detection using multi-temporal satellite images of same area is an established as well as actively pursued research problem. Most of the change detection techniques use algebraic or transform methods to do a pixel by pixel comparison of change detection. These techniques heavily depend upon the correct choice of threshold value to segregate the real changed pixels from the apparent changed ones. Also all these techniques can only compute the two dimensional change of the terrain surface from remotely sensed data. In this paper we propose a differential geometry approach to detect changes from remotely sensed images, which can detect the change using the geometric property of the pixels with respect to its surroundings. It can compute and filter the changed pixels having high curvature from that of flat (2D changed pixels.

N Panigrahi

2011-08-01

44

Methods and systems for remote detection of gases  

Science.gov (United States)

Novel systems and methods for remotely detecting at least one constituent of a gas via infrared detection are provided. A system includes at least one extended source of broadband infrared radiation and a spectrally sensitive receiver positioned remotely from the source. The source and the receiver are oriented such that a surface of the source is in the field of view of the receiver. The source includes a heating component thermally coupled to the surface, and the heating component is configured to heat the surface to a temperature above ambient temperature. The receiver is operable to collect spectral infrared absorption data representative of a gas present between the source and the receiver. The invention advantageously overcomes significant difficulties associated with active infrared detection techniques known in the art, and provides an infrared detection technique with a much greater sensitivity than passive infrared detection techniques known in the art.

Johnson, Timothy J

2012-09-18

45

SQUID-Detected In Vivo MRI at Microtesla Magnetic Fields  

Energy Technology Data Exchange (ETDEWEB)

We use a low transition temperature (T{sub c}) Super-conducting Quantum Interference Device (SQUID) to perform in vivo magnetic resonance imaging (MRI) at magnetic fields around 100 microtesla, corresponding to proton Larmor frequencies of about 5 kHz. In such low fields, broadening of the nuclear magnetic resonance lines due to inhomogeneous magnetic fields and susceptibility variations of the sample are minimized, enabling us to obtain high quality images. To reduce environmental noise the signal is detected by a second-order gradiometer, coupled to the SQUID, and the experiment is surrounded by a 3-mm thick Al shield. To increase the signal-to-noise ratio (SNR), we prepolarize the samples in a field up to 100 mT. Three-dimensional images are acquired in less than 6 minutes with a standard spin-echo phase-encoding sequence. Using encoding gradients of {approx}100 {micro}T/m we obtain three-dimensional images of bell peppers with a resolution of 2 x 2 x 8 mm{sup 3}. Our system is ideally suited to acquiring images of small, peripheral parts of the human body such as hands and arms. In vivo images of an arm, acquired at 132 {micro}T, show 24-mm sections of the forearm with a resolution of 3 x 3 mm{sup 2} and a SNR of 10. We discuss possible applications of MRI at these low magnetic fields.

Moble, Michael; Myers, Whittier R; Lee, SeungKyun; Kelso, Nathan; Hatridge, Michael; Pines, Alexander; Clarke, John

2005-06-01

46

SQUID-Detected In Vivo MRI at Microtesla Magnetic Fields  

International Nuclear Information System (INIS)

We use a low transition temperature (Tc) Super-conducting Quantum Interference Device (SQUID) to perform in vivo magnetic resonance imaging (MRI) at magnetic fields around 100 microtesla, corresponding to proton Larmor frequencies of about 5 kHz. In such low fields, broadening of the nuclear magnetic resonance lines due to inhomogeneous magnetic fields and susceptibility variations of the sample are minimized, enabling us to obtain high quality images. To reduce environmental noise the signal is detected by a second-order gradiometer, coupled to the SQUID, and the experiment is surrounded by a 3-mm thick Al shield. To increase the signal-to-noise ratio (SNR), we prepolarize the samples in a field up to 100 mT. Three-dimensional images are acquired in less than 6 minutes with a standard spin-echo phase-encoding sequence. Using encoding gradients of ?100 (micro)T/m we obtain three-dimensional images of bell peppers with a resolution of 2 x 2 x 8 mm3. Our system is ideally suited to acquiring images of small, peripheral parts of the human body such as hands and arms. In vivo images of an arm, acquired at 132 (micro)T, show 24-mm sections of the forearm with a resolution of 3 x 3 mm2 and a SNR of 10. We discuss possible applications of MRI at these low magnetic fields

47

Comparison of gadoxetic acid-enhanced MRI and superparamagnetic iron oxide-enhanced MRI for the detection of hepatocellular carcinoma  

International Nuclear Information System (INIS)

Aim: To compare the diagnostic accuracy and sensitivity of gadoxetic acid-enhanced MRI and superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) for the detection of hepatocellular carcinoma (HCC). Materials and methods: Eighty-nine patients (118 HCCs) who underwent three-dimensional gadoxetic acid-enhanced MRI and SPIO-enhanced MRI with a mean interval of 4.7 days (range 3-7 days), were included in this study. Two observers reviewed the gadoxetic acid set (unenhanced, early dynamic, 10 and 20 min hepatocyte-phase images) and SPIO set [unenhanced and ferucarbotran-enhanced T1-, T2-turbo spin-echo (TSE), and T2* weighted imaging (WI)] in consensus. Diagnostic accuracy and sensitivity were evaluated using the alternative-free response receiver operator characteristic (ROC) method. Results: The area under ROC curve (Az value) and sensitivity of the gadoxetic acid set (Az 0.964; sensitivity 90.7%) were significantly higher than those of the SPIO set (Az 0.830; sensitivity 84.7%; p < 0.05). There were 14 and seven lesions that were verified only on the gadoxetic acid set and only on the SPIO set, respectively. Four HCCs were clearly revealed as hypointense only on gadoxetic acid-enhanced hepatocyte phase imaging, but were occult on other sequences, including the SPIO set. Conclusion: Gadoxetic acid-enhanced MRI is better than SPIO-enhanced MRI for the detection of HCCs.

48

Diagnostic imaging strategy for MDCT- or MRI-detected breast lesions: use of targeted sonography  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Leading-edge technology such as magnetic resonance imaging (MRI or computed tomography (CT often reveals mammographically and ultrasonographically occult lesions. MRI is a well-documented, effective tool to evaluate these lesions; however, the detection rate of targeted sonography varies for MRI detected lesions, and its significance is not well established in diagnostic strategy of MRI detected lesions. We assessed the utility of targeted sonography for multidetector-row CT (MDCT- or MRI-detected lesions in practice. Methods We retrospectively reviewed 695 patients with newly diagnosed breast cancer who were candidates for breast conserving surgery and underwent MDCT or MRI in our hospital between January 2004 and March 2011. Targeted sonography was performed in all MDCT- or MRI-detected lesions followed by imaging-guided biopsy. Patient background, histopathology features and the sizes of the lesions were compared among benign, malignant and follow-up groups. Results Of the 695 patients, 61 lesions in 56 patients were detected by MDCT or MRI. The MDCT- or MRI-detected lesions were identified by targeted sonography in 58 out of 61 lesions (95.1%. Patients with pathological diagnoses were significantly older and more likely to be postmenopausal than the follow-up patients. Pathological diagnosis proved to be benign in 20 cases and malignant in 25. The remaining 16 lesions have been followed up. Lesion size and shape were not significantly different among the benign, malignant and follow-up groups. Conclusions Approximately 95% of MDCT- or MRI-detected lesions were identified by targeted sonography, and nearly half of these lesions were pathologically proven malignancies in this study. Targeted sonography is a useful modality for MDCT- or MRI-detected breast lesions.

Nakano Satoko

2012-06-01

49

PERFORMANCE OF IMPULSE NOISE DETECTION METHODS IN REMOTE SENSING IMAGES  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Remote sensing (RS) images are affected by different types of noises like Gaussian noise, speckle noise and impulse noise. These noises are introduced into the RS images during acquisition or transmission process. The main challenge in impulse noise removal is to suppress the noise as well as to preserve the details (edges). Removal ofthe impulse noise is done by two stages: detection of noisy pixel and replacement of that pixel. Detecting and Removing or reducing impulse noise is a very acti...

Mrs.V.RADHIKA,; Padmavathi, Dr G.

2010-01-01

50

Two-Dimensional Change Detection Methods Remote Sensing Applications  

CERN Document Server

Change detection using remotely sensed images has many applications, such as urban monitoring, land-cover change analysis, and disaster management. This work investigates two-dimensional change detection methods. The existing methods in the literature are grouped into four categories: pixel-based, transformation-based, texture analysis-based, and structure-based. In addition to testing existing methods, four new change detection methods are introduced: fuzzy logic-based, shadow detection-based, local feature-based, and bipartite graph matching-based. The latter two methods form the basis for a

Ilsever, Murat

2012-01-01

51

US correlation for MRI-detected breast lesions in women with familial risk of breast cancer  

Energy Technology Data Exchange (ETDEWEB)

AIM: To examine the value of US correlation for MRI-detected breast lesions in women with familial risk of breast cancer. METHODS: From an initial dataset of 245 women with positive family history who had breast cancer surveillance involving mammography or MRI between November 1994 and February 2001, 179 subjects with follow-up data were selected. A total of 43 women with 48 MRI-detected lesions underwent further assessment with US. Histopathological correlation was available from 38 breast biopsies performed for 33 women. RESULTS: Sonographic correlates were identified in 32 (66.7%) of the 48 MRI-detected lesions, with cancer present in 11 (34.4%) of these. This compares with 1 (6.3%) cancer found in the 16 lesions without sonographic correlates. Of the 12 malignant lesions, 11 (91.7%) had sonographic correlates whereas 21 (58.3%) of the 36 benign lesions had sonographic correlates. In all 74% of breast biopsies were performed under US guidance compared with 8% under MRI guidance. The proportion of MRI- and US-correlated benign and malignant lesions undergoing US-guided biopsy were 85.7% and 90.9%, respectively. CONCLUSION: The probability of cancer was significantly higher in MRI-detected breast lesions with sonographic correlates compared with those without such correlation. The advantage of convenient biopsy under US guidance as opposed to MRI guidance highlights the value of sonographic assessment of MRI-detected breast lesions.

Sim, L.S.J. [Department of Diagnostic Radiology, Singapore General Hospital (Singapore); Hendriks, J.H.C.L. [Department of Radiology, University Medical Centre St Radboud, Nijmegen (Netherlands); Bult, P. [Department of Pathology, University Medical Centre St Radboud, Nijmegen (Netherlands); Fook-Chong, S.M.C. [Department of Clinical Research, Singapore General Hospital, Singapore (Singapore)

2005-07-01

52

Preoperative detection of colorectal liver metastases in fatty liver: MDCT or MRI?  

International Nuclear Information System (INIS)

ons > 1 cm. Conclusion: For the detection of colorectal liver metastases after neoadjuvant chemotherapy and consecutive diffuse fatty infiltration of the liver, MRI is superior to MDCT, especially for the detection of small lesions.

53

MRI  

Medline Plus

Full Text Available ... MRI scan or just MRI, does NOT use x-rays. This document is for informational purposes and is ... body, let the technologists know. They can take x-rays of these areas to This document is for ...

54

MRI  

Medline Plus

Full Text Available ... and keep your belongings out of the MRI room. This will protect your watch, beepers, credit cards, and other magnet-sensitive devices from the effects of the MRI machine. You will be placed inside a magnet. Some ...

55

Preoperative detection of the eloquent areas of the brain using functional MRI  

International Nuclear Information System (INIS)

Forty-eight patients with 50 supratentorial gliomas were studied by functional MRI for motor and language areas before operation. Reliability of fMRI was evaluated comparing with Wada test and the brain mapping and/or cortical stimulation during awake surgery. For detecting motor area, activation of fMRI presented a reliable correlation with brain mapping when patients could follow tasks. Combined examination of fMRI with Wada test is useful to detect the speech area of the brain. (author)

56

?????????????????? Detection Automation of the Electric Car Remote Monitoring System Terminal  

Directory of Open Access Journals (Sweden)

Full Text Available ???????????????????????????????????????????????????????(??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? At this stage, with the great support of pure electric vehicles from the State, pure electric vehicle industry line has been very clear. Along with the development of electric car production, electric vehicle remote monitoring system (safety equipment will be mass produced. However, electric cars remote monitoring system terminal in use, maintenance of the production process and test cost is difficult to control, it has a direct impact on the quality of the terminal and the precision of data collection. This paper mainly introduces the electric vehicle remote monitoring system terminal in the production process of detection automation. By using computer software and terminal communication terminal, access to important information and guide the operators fast processing, thereby improving the production efficiency and product quality.

???

2013-04-01

57

Automatic brain tumor detection in MRI: methodology and statistical validation  

Science.gov (United States)

Automated brain tumor segmentation and detection are immensely important in medical diagnostics because it provides information associated to anatomical structures as well as potential abnormal tissue necessary to delineate appropriate surgical planning. In this work, we propose a novel automated brain tumor segmentation technique based on multiresolution texture information that combines fractal Brownian motion (fBm) and wavelet multiresolution analysis. Our wavelet-fractal technique combines the excellent multiresolution localization property of wavelets to texture extraction of fractal. We prove the efficacy of our technique by successfully segmenting pediatric brain MR images (MRIs) from St. Jude Children"s Research Hospital. We use self-organizing map (SOM) as our clustering tool wherein we exploit both pixel intensity and multiresolution texture features to obtain segmented tumor. Our test results show that our technique successfully segments abnormal brain tissues in a set of T1 images. In the next step, we design a classifier using Feed-Forward (FF) neural network to statistically validate the presence of tumor in MRI using both the multiresolution texture and the pixel intensity features. We estimate the corresponding receiver operating curve (ROC) based on the findings of true positive fractions and false positive fractions estimated from our classifier at different threshold values. An ROC, which can be considered as a gold standard to prove the competence of a classifier, is obtained to ascertain the sensitivity and specificity of our classifier. We observe that at threshold 0.4 we achieve true positive value of 1.0 (100%) sacrificing only 0.16 (16%) false positive value for the set of 50 T1 MRI analyzed in this experiment.

Iftekharuddin, Khan M.; Islam, Mohammad A.; Shaik, Jahangheer; Parra, Carlos; Ogg, Robert

2005-04-01

58

PERFORMANCE OF IMPULSE NOISE DETECTION METHODS IN REMOTE SENSING IMAGES  

Directory of Open Access Journals (Sweden)

Full Text Available Remote sensing (RS images are affected by different types of noises like Gaussian noise, speckle noise and impulse noise. These noises are introduced into the RS images during acquisition or transmission process. The main challenge in impulse noise removal is to suppress the noise as well as to preserve the details (edges. Removal ofthe impulse noise is done by two stages: detection of noisy pixel and replacement of that pixel. Detecting and Removing or reducing impulse noise is a very active research area in image processing. In this paper three different existing detection methods are discussed with the intension of developing a new one.

Mrs.V.RADHIKA,

2010-09-01

59

MRI breast screening in high-risk women: cancer detection and survival analysis.  

Science.gov (United States)

Women with a genetic predisposition to breast cancer tend to develop the disease at a younger age with denser breasts making mammography screening less effective. The introduction of magnetic resonance imaging (MRI) for familial breast cancer screening programs in recent years was intended to improve outcomes in these women. We aimed to assess whether introduction of MRI surveillance improves 5- and 10-year survival of high-risk women and determine the accuracy of MRI breast cancer detection compared with mammography-only or no enhanced surveillance and compare size and pathology of cancers detected in women screened with MRI + mammography and mammography only. We used data from two prospective studies where asymptomatic women with a very high breast cancer risk were screened by either mammography alone or with MRI also compared with BRCA1/2 carriers with no intensive surveillance. 63 cancers were detected in women receiving MRI + mammography and 76 in women receiving mammography only. Sensitivity of MRI + mammography was 93 % with 63 % specificity. Fewer cancers detected on MRI were lymph node positive compared to mammography/no additional screening. There were no differences in 10-year survival between the MRI + mammography and mammography-only groups, but survival was significantly higher in the MRI-screened group (95.3 %) compared to no intensive screening (73.7 %; p = 0.002). There were no deaths among the 21 BRCA2 carriers receiving MRI. There appears to be benefit from screening with MRI, particularly in BRCA2 carriers. Extended follow-up of larger numbers of high-risk women is required to assess long-term survival. PMID:24687378

Evans, D Gareth; Gareth, Evans D; Kesavan, Nisha; Nisha, Kesavan; Lim, Yit; Yit, Lim; Gadde, Soujanye; Soujanye, Gadde; Hurley, Emma; Emma, Hurley; Massat, Nathalie J; Maxwell, Anthony J; Ingham, Sarah; Sarah, Ingham; Eeles, Rosalind; Rosalind, Eeles; Leach, Martin O; Howell, Anthony; Anthony, Howell; Duffy, Stephen W; Stephen, Duffy

2014-06-01

60

MRI  

Medline Plus

Full Text Available ... sensitive devices from the effects of the MRI machine. You will be placed inside a magnet. Some ... artificial cardiac valves are NOT allowed near the machine. Some newer devices may be compatible with certain ...

 
 
 
 
61

MRI  

Medline Plus

Full Text Available ... a test that provides very clear pictures of structures inside the body. Doctors may recommend an MRI ... dye given through the vein to help visualize structures better inside the body. This dye is relatively ...

62

MRI  

Medline Plus

Full Text Available ... the MRI. The patients at highest risk for metal fragments are welders and people injured by shrapnel ... However, because of the magnet, people who have metal of any kind implanted in their bodies should ...

63

Microfluidic gas-flow profiling using remote-detection NMR  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have used nuclear magnetic resonance (NMR) to obtain spatially and temporally resolved profiles of gas flow in microfluidic devices. Remote detection of the NMR signal both overcomes the sensitivity limitation of NMR and enables time-of-flight measurement in addition to spatially resolved imaging. Thus, detailed insight is gained into the effects of flow, diffusion, and mixing in specific geometries. The ability for noninvasive measurement of microfluidic flow, without the introduction of ...

Hilty, Christian; Mcdonnell, Erin E.; Granwehr, Josef; Pierce, Kimberly L.; Han, Song-i; Pines, Alexander

2005-01-01

64

Remote homology detection incorporating the context of physicochemical properties.  

Science.gov (United States)

A new method for remote protein homology detection, called support vector machine incorporating the context of physicochemical properties (SVM-CP), is presented. Recent discriminative methods are based on concatenating information extracted from each protein by considering several physicochemical properties. We show that there are physicochemical properties that reflect the functional or structural characteristics of each specific protein family, but there are also some physicochemical properties that affect the accuracy of the classification techniques. The research highlights the importance of the selection of physicochemical properties in remote homology detection. Most of the methods slide a window over every protein sequence to extract physicochemical information. This extraction is usually performed by giving the same importance to every value in the window, i.e., averaging the physicochemical values in the observation window. SVM-CP takes into account that every residue in a sliding window has a different weight, which reflects the importance or contribution to the representative value of the window. The SVM-CP method reaches a receiver operating characteristic (ROC) score of 0.93462, which is the highest value for a remote homology detection method based on the sequence composition information. PMID:24480162

Bedoya, Oscar; Tischer, Irene

2014-02-01

65

Gadoxetic Acid (Gd-EOB-DTPA)-Enhanced MRI versus Gadobenate Dimeglumine (Gd-BOPTA)-Enhanced MRI for Preoperatively Detecting Hepatocellular Carcinoma: an Initial Experience  

International Nuclear Information System (INIS)

This study was designed to compare the diagnostic performance of gadoxetic acid-enhanced magnetic resonance imaging (MRI) with gadobenate dimeglumine-enhanced MRI for preoperatively detecting hepatocellular carcinoma (HCC). Eighteen consecutive patients (17 men and one woman, age range: 31-73 years) with 22 HCCs underwent examinations with gadoxetic acid enhanced MRI and gadobenate dimeglumine-enhanced MRI on a 3.0-Tesla unit. The diagnosis of HCC was established after surgical resection and pathological conformation. Three observers independently reviewed each MR image in a random order on a tumor-by-tumor basis. The diagnostic accuracy of these techniques for the detection of HCC was assessed by performing an alternative free-response receiver operating characteristic (ROC) analysis. The sensitivity and positive predictive values were evaluated. The average value of the area under the ROC curve (Az) for gadoxetic acid enhanced MRI (0.887) was not significantly different from the Az (0.899) for gadobenate dimeglumine-enhanced MRI (p > 0.05). The overall sensitivities of gadoxetic acid enhanced MRI and gadobenate dimeglumine-enhanced MRI were 80% and 83%, respectively, with no significant difference (p > 0.05). The differences of the positive predictive values for the two contrast agents for each observer were not statistically significant (p > 0.05). The diagnostic performance of gadoxetic acid-enhanced MRI and gadobenate dimeglumine-enhanced MRI for preoperatively deglumine-enhanced MRI for preoperatively detecting HCC is quite similar

66

Whole-body muscle MRI to detect myopathies in non-extrapyramidal bent spine syndrome  

International Nuclear Information System (INIS)

Bent spine syndrome (BSS), defined as an abnormal forward flexion of the trunk resolving in supine position, is usually related to parkinsonism, but can also be encountered in myopathies. This study evaluates whole-body muscle MRI (WB-mMRI) as a tool for detecting underlying myopathy in non-extrapyramidal BSS. Forty-three patients (90 % women; 53-86 years old) with a non-extrapyramidal BSS were prospectively included. All underwent a 1.5-T WB-mMRI and a nerve conduction study. Muscle biopsy was performed if a myopathy could not be eliminated based on clinical examination and all tests. Systematic MRI interpretation focused on peripheral and axial muscle injury; spinal posture and incidental findings were also reported. WB-mMRI was completed for all patients, with 13 muscle biopsies ultimately needed and myopathy revealed as the final etiological diagnosis in five cases (12 %). All biopsy-proven myopathies were detected by the WB-mMRI. Relevant incidental MRI findings were made in seven patients. This study supports WB-mMRI as a sensitive and feasible tool for detecting myopathy in BSS patients. Associated with electroneuromyography, it can better indicate when a muscle biopsy is needed and guide it when required. Rigorous radiological interpretation is mandatory, so as not to miss incidental findings of clinical consequence. (orig.)

67

Laser radar for remote detection of oils spills  

Energy Technology Data Exchange (ETDEWEB)

A laser radar system that is capable of remotely detecting oil spills, in the daytime and at night, in sea water has been developed. The system employs the second harmonic and fourth harmonic of a repetitively Q-switched Nd:YAG laser as the light sources and a gated optical multichannel analyzer as a high speed detection device. The results show that the comparison of backscattering spectra obtained from different samples enables us to detect and characterize oil spills in sea water. Raman backscattering and backscattered fluorescence of kerosene, light oil, heavy oil, and sea water have been investigated both in the laboratory and in the harbor of Seto Inland Sea of Japan by using the laser radar system described above. The SNR of this laser radar system for the detection of Raman backscattering of kerosene and fluorescence of oil is also described.

Sato, T.; Suzuki, Y.; Kashiwagi, H.; Nanjo, M.; Kakui, Y.

1978-12-01

68

Laser radar for remote detection of oil spills.  

Science.gov (United States)

A laser radar system that is capable of remotely detecting oil spills, in the daytime and at night, in sea water has been developed. The system employs the second harmonic and fourth harmonic of a repetitively Q-switched Nd:YAG laser as the light sources and a gated optical multichannel analyzer as a high speed detection device. The results show that the comparison of backscattering spectra obtained from different samples enables us to detect and characterize oil spills in sea water. Raman backscattering and backscattered fluorescence of kerosene, light oil, heavy oil, and sea water have been investigated both in the laboratory and in the harbor of Seto Inland Sea of Japan by using the laser radar system described above. The SNR of this laser radar system for the detection of Raman backscattering of kerosene and fluorescence of oil is also described. PMID:20208611

Sato, T; Suzuki, Y; Kashiwagi, H; Nanjo, M; Kakui, Y

1978-12-01

69

Comparison of bone scintigraphy and MRI imaging in detecting vertebral metastatic tumors  

International Nuclear Information System (INIS)

Objective: To compare the diagnostic value of bone scintigraphy and MRI in detecting vertebral metastastic tumors. Method:A retrospective comparison was made between 99mTc-MDP bone scintigraphy and corresponding spine MRI in 76 patients who had complementary studies within 1 month. There were 42 male and 34 female patients diagnosed with cancer prior to these studies. Cancer diagnoses included 29 lung, 15 breast, 5 liver, 5 esophagus, 4 rectum, 2 bladder, 2 thymus, 1 nasopharynx, 1 endometrium, 3 cervix uterus, 1 mucinous cystadenocarcinoma, 2 stomach,1syringocarcinoma. Ninteen patients complained backpain. Forty-two patients had bone scintigraphies done before MRI, 30 patients had MRI done after bone scintigraphy, only 4 patients had both studies on the same day. The spinal and pelvic bones which were in the scan field of MRI were observed to compare the demonstration of the lesions using bone scintigraphy and MRI. Bone scintigraphy were obtained using GE STARCAM 4000 SPECT, equipped with a parallel-hole, low-energy, high resolution collimator, 2 to 3 hrs after intravenous injection of 25 mCi (925MBq) of 99mTc-MDP, in anterior and post position after urinating.. MR studies were performed with a GE 1.5 tesla signal scanner. All patients were studied with T1-weihgted and T2-weighted spin echo sequences obtained in the sagittal plane, T1-weighted in trasversal plane ordinarily, and contrast enhancement or in coronal plane if necessary. The spinal and pelvic bones which essary. The spinal and pelvic bones which were in the scan field of MRI were observed to compare the demonstration of the lesions using bone scintigraphy and MRI. Bone scintigraphy regions were read positive when its uptake of tracer was increased or decreased obviously compared to adjacent or contralateral structures. The criteria for the MRI diagnosis of metastases were the presence fof a well defined focus of low signals on the T1-weighted images , high and low mixed or high signal intensity on T2-weighted spin echo sequences.The comparison of the paired data were determined with a chi-square test and #P­# 0.05 was considered significant Results: Among the 76 patients, bone scintigraphy and MRI almost detected the same vertebral metastatic cases and metastatic foci .The rate of positive cases was 83.95% (68/81) and 75.30% (61/81). The rate of positive metastatic foci was 31.15% (167/536) and 29.10% (156/536). Two methods revealed that the lesions most commonly located in thoracic vertebrae, MRI detected more metastatic foci than bone scintigraphy in the site 83%(83/237) and 64% (64/237). There was no difference between bone scintigraphy and MRI in detecting metastatic foci in lumbar vertebrae. Bone scintigraphy was better than MRI in detecting cervical spine and sacrum (15/63 and 6/63 , 23/78 and 10/78 , respectively ) . MRI was better than bone scintigraphy in detecting multiple metastatic foci (143/237 and 116/237, respectively ). There were fasle positive of single focus both in bone scintigraphy (3/16) and MRI (2/11), and fasle negative foci in rapidly progressive condition in bone scintigraphy. Bone scintigraphy revealed 111 foci outside spine in 42 patients. Conclusion: The sensitivity of bone scintigraphy and MRI in detecting vertebral metastatic lesions were similar. MRI is more efficient in detecting thoracic and multiple vertebral metastases. However bone scintigraphy is more efficient in detecting vertebral metastases in cervical spine and sacrum than MRI. Considering its cost and the convenience of performing a whole-body survey for metastasis, bone scintigraphy remains the study of choice for initial evaluation of patients with cancer. MRI is a further complementary technique when bone scintigraphy findings are inadequate for answering clinical questions

70

MRI Detects Cancers in the Opposite Breast of Women Newly Diagnosed with Breast Cancer  

Science.gov (United States)

Magnetic Resonance Imaging (MRI) scans of women who were diagnosed with cancer in one breast detected over 90 percent of cancers in the other breast that were missed by mammography and clinical breast exam at initial diagnosis, according to a new study. Given the established rates of mammography and clinical breast exams for detecting cancer in the opposite, or contralateral breast, adding an MRI scan to the diagnostic evaluation effectively doubled the number of cancers immediately found in these women.

71

Remote excitation and remote detection of a single quantum dot using propagating surface plasmons on silver nanowire  

Science.gov (United States)

Using propagating surface plasmons (SPs) on a silver nanowire (NW), we demonstrate that a focused laser light at the end of the silver NW can excite a single quantum dot (QD) microns away from the excitation spot. The QD—NW interaction allows the excited QD convert part of its energy into propagating SPs, which then can be detected at remote sites. Simultaneous multi-QD remote excitation and remote detection can also be realized. Furthermore, the tight confinement of the propagating SPs around the NW surface enables the selective excitation of QDs very close in space, which cannot be realized under the conventional excitation condition. This remote excitation and remote detection approach may find applications in optical imaging and the sensing of chemical and biological systems.

Li, Qiang; Wei, Hong; Xu, Hong-Xing

2014-09-01

72

Detection of intraplaque hemorrhage with use of screening black-blood MRI  

International Nuclear Information System (INIS)

The evaluation of plaque characteristics as well as the degree of luminal narrowing is important in the management of carotid stenosis. Several reports have shown that intraplaque hemorrhage (IPH), which plays a pivotal role in plaque vulnerability, emits high signal intensity on T1-weighted images of high-resolution black-blood (BB) MRIs. When an MRI is used to screen for vulnerable plaque, a short scanning duration and a simple MRI protocol are required. This study assessed the utility of screening BB-MRI to detect IPH. Ninety-three consecutive cases with atherosclerotic carotid stenosis scheduled for carotid endarterectomy (CEA) or carotid artery stenting between January 2005 and December 2007 were included. High-resolution BB-MRI scans were obtained with 2D double-inversion recovery fast spin-echo sequences with cardiac gating. Screening BB-MRIs were performed with 3D gradient-echo sequences suppressing blood flow signals by radiofrequency wave spatial saturation over the scanning field of 3D time-of-flight MR angiography (MRA). The relative overall plaque signal intensities with reference to the sternocleidomastoid muscle were calculated, and the correlation of intensities on T1-weighted images between high-resolution BB-MRI and screening BB-MRI was investigated. We excluded 50 cases because of restenosis following CEA, use of a pacemaker, a long interval (>10 days) between high-resolution and screening BB-MRI examinations, or poor-quality images. Among the 43 cas, or poor-quality images. Among the 43 cases included, the relative overall plaque signal intensity of high-resolution BB-MRI and screening BB-MRI were closely correlated (r=0.568, p<0.001). Screening BB-MRI can be an alternative to high-resolution BB-MRI in the assessment of IPH and may be a useful tool for detection of vulnerable plaque. (author)

73

Does MRI-detected cranial nerve involvement affect the prognosis of locally advanced nasopharyngeal carcinoma treated with intensity modulated radiotherapy?  

Science.gov (United States)

Nasopharyngeal carcinoma (NPC) is one of the common cancers in South China. It can easily invade into cranial nerves, especially in patients with local advanced disease. Despite the fact that the magnetic resonance imaging (MRI) findings are not always consistent with the symptoms of CN palsy, MRI is recommended for the detection of CN involvement (CNI). However, the prognostic impact of MRI-detected CNI in NPC patients is still controversial. To investigate the prognostic value of MRI detected CNI, we performed a retrospective analysis on the clinical data of 375 patients with NPC who were initially diagnosed by MRI. All patients had T3-4 disease and received radical intensity modulated radiation therapy (IMRT) as their primary treatment. The incidence of MRI-detected CNI was 60.8%. A higher incidence of MRI-detected CNI was observed in T4 disease compared with T3 disease (96.8% vs. 42.8%, PIII disease (91.5% vs. 42.3%; PIII patients with or without MRI-detected CNI was significantly superior to that of Stage IV patients (PIII patients with or without MRI-detected CNI for all endpoints. Therefore, when treated with IMRT, MRI-detected CNI in patients with NPC does not appear to affect the prognosis. In patients with clinical T3 disease, the presence of MRI-detected CNI is not sufficient evidence for defining T4 disease. PMID:24963626

Zong, Jingfeng; Lin, Shaojun; Chen, Yunbin; Wang, Bingyi; Xiao, Youping; Lin, Jin; Li, Rui; Pan, Jianji

2014-01-01

74

Can breast MRI computer-aided detection (CAD) improve radiologist accuracy for lesions detected at MRI screening and recommended for biopsy in a high-risk population?  

Energy Technology Data Exchange (ETDEWEB)

Aim: To evaluate the sensitivity and specificity of magnetic resonance imaging (MRI) computer-aided detection (CAD) for breast MRI screen-detected lesions recommended for biopsy in a high-risk population. Material and methods: Fifty-six consecutive Breast Imaging Reporting and Data System (BI-RADS) 3-5 lesions with histopathological correlation [nine invasive cancers, 13 ductal carcinoma in situ (DCIS) and 34 benign] were retrospectively evaluated using a breast MRI CAD prototype (CAD-Gaea). CAD evaluation was performed separately and in consensus by two radiologists specializing in breast imaging, blinded to the histopathology. Thresholds of 50, 80, and 100% and delayed enhancement were independently assessed with CAD. Lesions were rated as malignant or benign according to threshold and delayed enhancement only and in combination. Sensitivities, specificities, and negative predictive values (NPV) were determined for CAD assessments versus pathology. Initial MRI BI-RADS interpretation without CAD versus CAD assessments were compared using paired binary diagnostic tests. Results: Threshold levels for lesion enhancement were: 50% to include all malignant (and all benign) lesions; and 100% for all invasive cancer and high-grade DCIS. Combined use of threshold and enhancement patterns for CAD assessment was best (73% sensitivity, 56% specificity and 76% NPV for all cancer). Sensitivities and NPV were better for invasive cancer (100%/100%) than for all malignancies (54%/76%). Radiologists' MRI interpretation was more sensitive than CAD (p = 0.05), but less specific (p = 0.001) for cancer detection. Conclusion: The breast MRI CAD system used could not improve the radiologists' accuracy for distinguishing all malignant from benign lesions, due to the poor sensitivity for DCIS detection.

Arazi-Kleinman, T., E-mail: t_arazikleinman@yahoo.co [Department of Medical Imaging, Sunnybrook Health Sciences Centre, University of Toronto, Toronto (Canada); Department of Medical Imaging Tel Aviv Sourasky Medical Centre, Sackler School of Medicine Tel Aviv University, Tel Aviv (Israel); Causer, P.A.; Jong, R.A. [Department of Medical Imaging, Sunnybrook Health Sciences Centre, University of Toronto, Toronto (Canada); Hill, K.; Warner, E. [Division of Medical Oncology, Department of Medicine, Sunnybrook Health Sciences Centre, University of Toronto, Toronto (Canada)

2009-12-15

75

Can breast MRI computer-aided detection (CAD) improve radiologist accuracy for lesions detected at MRI screening and recommended for biopsy in a high-risk population?  

International Nuclear Information System (INIS)

Aim: To evaluate the sensitivity and specificity of magnetic resonance imaging (MRI) computer-aided detection (CAD) for breast MRI screen-detected lesions recommended for biopsy in a high-risk population. Material and methods: Fifty-six consecutive Breast Imaging Reporting and Data System (BI-RADS) 3-5 lesions with histopathological correlation [nine invasive cancers, 13 ductal carcinoma in situ (DCIS) and 34 benign] were retrospectively evaluated using a breast MRI CAD prototype (CAD-Gaea). CAD evaluation was performed separately and in consensus by two radiologists specializing in breast imaging, blinded to the histopathology. Thresholds of 50, 80, and 100% and delayed enhancement were independently assessed with CAD. Lesions were rated as malignant or benign according to threshold and delayed enhancement only and in combination. Sensitivities, specificities, and negative predictive values (NPV) were determined for CAD assessments versus pathology. Initial MRI BI-RADS interpretation without CAD versus CAD assessments were compared using paired binary diagnostic tests. Results: Threshold levels for lesion enhancement were: 50% to include all malignant (and all benign) lesions; and 100% for all invasive cancer and high-grade DCIS. Combined use of threshold and enhancement patterns for CAD assessment was best (73% sensitivity, 56% specificity and 76% NPV for all cancer). Sensitivities and NPV were better for invasive cancer (100%/100%) than for all malignancies (54%/760%/100%) than for all malignancies (54%/76%). Radiologists' MRI interpretation was more sensitive than CAD (p = 0.05), but less specific (p = 0.001) for cancer detection. Conclusion: The breast MRI CAD system used could not improve the radiologists' accuracy for distinguishing all malignant from benign lesions, due to the poor sensitivity for DCIS detection.

76

T1-weighted MRI for the detection of coronary artery plaque haemorrhage  

International Nuclear Information System (INIS)

Hyperintense areas in atherosclerotic plaques on pre-contrast T1-weighted MRI have been shown to correlate with intraplaque haemorrhage. We evaluated the presence of T1 hyperintensity in coronary artery plaques in coronary artery disease (CAD) patients and correlated results with multi-detector computed tomography (MDCT) findings. Fifteen patients with CAD were included. Plaques detected by MDCT were categorised based on their Hounsfield number. T1-weighted inversion recovery (IR) MRI prepared coronary MRI for the detection of plaque and steady-state free-precession coronary MR-angiography for anatomical correlation was performed. After registration of MDCT and MRI, regions of interest were defined on MDCT-visible plaques and in corresponding vessel segments acquired with MRI. MDCT density and MR signal measurement were performed in each plaque. Forty-three plaques were identified with MDCT. With IR-MRI 5/43 (12%) plaques were hyperintense, 2 of which were non-calcified and 3 mixed. Average signal-to-noise and contrast-to-noise ratios of hyperintense plaques were 15.7 and 9.1, compared with 5.6 and 1.2 for hypointense plaques. Hyperintense plaques exhibited a significantly lower CT density than hypointense plaques (63.6 vs. 140.8). There was no correlation of plaque signal intensity with degree of stenosis. T1-weighted IR-MRI may be useful for non-invasive detection and characterisation of intraplaque haemorrhage in coronary artery plaques. (orig.)

77

Detection and grading of dAVF: prospects and limitations of 3T MRI  

International Nuclear Information System (INIS)

DSA is currently the criterion standard for the assessment of dural arteriovenous fistulas (dAVF). Recently, evolving MRA techniques have emerged as a non-invasive alternative. The aim of this study is to assess the value of 3 T MRI in detecting and describing dAVF and to determine whether MRI can replace DSA as diagnostic procedure. A total of 19 patients with dAVF and 19 without dAVF underwent the same MRI protocol, including 3D time-of-flight MRA and time-resolved contrast-enhanced MRA. The images were evaluated retrospectively by three independent readers with different levels of experience blinded to clinical information. The readers assessed the presence, the site, the venous drainage and the feeders of dAVF. Sensitivity, specificity, accuracy, intertechnique and interobserver agreements were calculated. DAVF can be detected with high sensitivity, specificity and accuracy by experienced and also by less experienced readers. However, MRI has limitations when used for grading and evaluation of the angioarchitecture of the dAVF. Different experience, the limited resolution of MRI and its inability to selectively display arteries were the reasons for these limitations. With MRI dAVF can be detected reliably. Nevertheless, at present MRI can not fully replace DSA, especially for treatment planning. (orig.)

78

Pathophysiological changes detected by MRI within 24 hours after head injury  

International Nuclear Information System (INIS)

This report concerns the evaluation of the usefulness of high-field magnetic resonance imaging (MRI) for the diagnosis and prognosis of patients with head injuries. For this purpose we compared the CT and MRI results obtained on 48 such patients. MRI of all cases was taken within 24 hours after head injury using a 1.5-Tesla unit. The sensitivity of the two modalities in the detection of small traumatic lesions was compared. Traumatic lesions of 23 patients (47.9%) were not detected by CT, but they were demonstrated on MRI. Overall, MRI was significantly more sensitive than CT in detecting early and/or subtle traumatic changes of the brain parenchyma (P1-WI and T2-WI. (B) Corpus callosum lesions with hyperintensity on T2-WI were in fact hemorrhagic contusions by signal changes on sequential MRI. The follow-up of chronological changes of a given corpus callosum lesion was essential for confirmation of its pathology. (C) In one case, scratch-like lesions with strong hypointensity on T1-WI and hyperintensity on T2-WI were clearly demonstrated in the white matter. Tharly demonstrated in the white matter. These observations appeared to indicate axonal damages. (D) Even if initial GCS score is low (2-WI and subsequently disappeared completely. We conclude that performing MRI in the early stage of a head injury is of utility for the understanding of pertinent pathophysiological changes and for predicting outcome. (author)

79

Management of breast lesions detectable only on MRI; Abklaerung ausschliesslich MRT-detektierbarer Mammalaesionen  

Energy Technology Data Exchange (ETDEWEB)

Breast MR imaging has become established as the most sensitive imaging method for diagnosing breast cancer. As a result of the increasing examination volume and improved image quality, the number of breast lesions detected only on MRI and requiring further clarification has risen in recent years. According to the S3-guideline 'Diagnosis, Therapy, and Follow-Up of Breast Cancer' as revised in July 2012, institutions performing breast MRI should provide the option of an MRI-guided intervention for clarification. This review describes the indications, methods and results of MRI-guided interventions for the clarification of breast lesions only visible on MRI. Recent guidelines and study results are also addressed and alternative methods and pitfalls are presented. (orig.)

Siegmann-Luz, K.C.; Bahrs, S.D.; Preibsch, H.; Hattermann, V.; Claussen, C.D. [Universitaetsklinikum Tuebingen (Germany). Abt. Diagnostische und Interventionelle Radiologie

2014-01-15

80

NMR analysis on microfluidic devices by remote detection  

Energy Technology Data Exchange (ETDEWEB)

We present a novel approach to perform high-sensitivity NMR imaging and spectroscopic analysis on microfluidic devices. The application of NMR, the most information rich spectroscopic technique, to microfluidic devices remains a challenge because the inherently low sensitivity of NMR is aggravated by small fluid volumes leading to low NMR signal, and geometric constraints resulting in poor efficiency for inductive detection. We address the latter by physically separating signal detection from encoding of information with remote detection. Thereby, we use a commercial imaging probe with sufficiently large diameter to encompass the entire device, enabling encoding of NMR information at any location on the chip. Because large-diameter coils are too insensitive for detection, we store the encoded information as longitudinal magnetization and flow it into the outlet capillary. There, we detect the signal with optimal sensitivity using a solenoidal microcoil, and reconstruct the information encoded in the fluid. We present a generally applicable design for a detection-only microcoil probe that can be inserted into the bore of a commercial imaging probe. Using hyperpolarized 129Xe gas, we show that this probe enables sensitive reconstruction of NMR spectroscopic information encoded by the large imaging probe while keeping the flexibility of a large coil.

McDonnell, Erin E.; Han, SongI; Hilty, Christian; Pierce,Kimberly; Pines, Alexander

2005-08-15

 
 
 
 
81

Supercooled large drop detection with NASA's Icing Remote Sensing System  

Science.gov (United States)

In-flight icing occurs when aircraft impact supercooled liquid drops. The supercooled liquid freezes on contact and the accreted ice changes a plane's aerodynamic characteristics, which can lead to dangerous loss of control. NASA's Icing Remote Sensing System consists of a multi-channel radiometer, a laser ceilometer and a vertically-pointing Kaband radar, whos fields are merged with internal software logic to arrive at a hazard classification for in-flight icing. The radiometer is used to derive atmospheric temperature soundings and integrated liquid water and the ceilometer and radar are used to define cloud boundaries. The integrated liquid is then distributed within the determined cloud boundaries and layers to arrive at liquid water content profiles, which if present below freezing are categorized as icing hazards. This work outlines how the derived liquid water content and measured Ka-band reflectivity factor profiles can be used to derive a vertical profile of radar-estimated particle size. This is only possible because NASA's system arrives at independent and non-correlated measures of liquid water and reflectivity factor for a given range volume. The size of the drops significantly effect the drop collection efficiency and the location that icing accretion occurs on the craft's superstructure and thus how a vehicle's performance is altered. Large drops, generally defined as over 50 ?m in diameter, tend to accrete behind the normal ice protected areas of the leading edge of the wing and other control surfaces. The NASA Icing Remote Sensing System was operated near Montreal, Canada for the Alliance Icing Research Study II in 2003 and near Cleveland, Ohio from 2006 onward. In this study, we present case studies to show how NASA's Icing Remote Sensing System can detect and differentiate between no icing, small drop and large drop in-flight icing hazards to aircraft. This new product provides crucial realtime hazard detection capabilities which improve avaiation safety in the near-airport environment with cost-effective, existing instrumentation technologies.

Serke, David J.; Reehorst, Andrew L.; Politovich, Marcia K.

2010-10-01

82

Whole-body MRI using a rolling table platform for the detection of bone metastases  

Energy Technology Data Exchange (ETDEWEB)

The aim of this study was to compare the results of whole-body MRI using a recently developed rolling table platform with findings of nuclear scintigraphy in patients with bone metastases. Twenty-six patients with known or suspected bone metastases who had undergone radionuclide scintigraphy were examined by MRI. Patients were placed on a rolling table platform with integrated phased-array surface coils [BodySURF (system for unlimited field of view)] capable of pulling the patient through the isocenter of the magnet. Using a five-station approach three different image sets (T1-weighted gradient recalled echo, half-Fourier acquired single-shot turbo spin echo, and short tau inversion recovery) were collected in the coronal plane. In addition, the spine was imaged in the sagittal plane. The MRI findings were compared with the results obtained by scintigraphy. The whole-body MR examination lasting merely 40 min was feasible in all 26 patients. The MRI revealed excellent correlation with scintigraphy regarding metastatic lesions. A total of 60 regions with metastatic lesions were identified on bone scintigraphy. Fifty-three regions were detected on identical locations by MRI. The regions missed by MRI were located mainly in ribs and skull. The MRI could identify additional bone metastases in spine, pelvis, and femur. The MRI screening for bone metastases correlated well with bone scintigraphy. Use of the rolling table platform permits rapid imaging based on three different contrast mechanisms of the entire skeletal system. (orig.)

Lauenstein, Thomas C.; Goehde, Susanne C.; Ruehm, Stefan G.; Goyen, Mathias; Bosk, Silke; Debatin, Joerg F.; Barkhausen, Joerg [Department of Diagnostic Radiology, University Hospital Essen, Hufelandstrasse 55, 45122 Essen (Germany); Freudenberg, Lutz S. [Department of Nuclear Medicine, University Hospital Essen, Hufelandstrasse 55, 45122 Essen (Germany)

2002-08-01

83

Whole-body MRI using a rolling table platform for the detection of bone metastases  

International Nuclear Information System (INIS)

The aim of this study was to compare the results of whole-body MRI using a recently developed rolling table platform with findings of nuclear scintigraphy in patients with bone metastases. Twenty-six patients with known or suspected bone metastases who had undergone radionuclide scintigraphy were examined by MRI. Patients were placed on a rolling table platform with integrated phased-array surface coils [BodySURF (system for unlimited field of view)] capable of pulling the patient through the isocenter of the magnet. Using a five-station approach three different image sets (T1-weighted gradient recalled echo, half-Fourier acquired single-shot turbo spin echo, and short tau inversion recovery) were collected in the coronal plane. In addition, the spine was imaged in the sagittal plane. The MRI findings were compared with the results obtained by scintigraphy. The whole-body MR examination lasting merely 40 min was feasible in all 26 patients. The MRI revealed excellent correlation with scintigraphy regarding metastatic lesions. A total of 60 regions with metastatic lesions were identified on bone scintigraphy. Fifty-three regions were detected on identical locations by MRI. The regions missed by MRI were located mainly in ribs and skull. The MRI could identify additional bone metastases in spine, pelvis, and femur. The MRI screening for bone metastases correlated well with bone scintigraphy. Use of the rolling table platform permits rapid imaging based on three differenmits rapid imaging based on three different contrast mechanisms of the entire skeletal system. (orig.)

84

A remote fiber optic dosimeter network for detecting hydrazine vapor  

International Nuclear Information System (INIS)

A fiber optic chemical dosimeter has been developed for use in the remote detection of vapors of toxic amine rocket fuels (hydrazine and its substituted derivatives) that are used as Air Force and civilian launch sites. The dosimeter employs a colorimetric indicating reagent immobilized in a porous sol-gel cladding on multimode fiber. This reagent reacts selectively with the fuel vapor to produce a strongly absorbing cladding that introduces light propagation losses in the fiber; these losses indicate the presence of hydrazine (N2H4) vapor. The absorption occurs over a broad spectral range ideally suited for interrogation by semiconductor diode lasers. The authors have shown that the dosimeter yields an average hydrazine detectivity of 2.3 exposures of the dosimeter to laboratory air have not adversely affected the dosimeter. Additionally, its response to ammonia vapor has been determined to be 9,200 times smaller than its response to hydrazine vapor

85

Sensitive change detection for remote sensing monitoring of nuclear treaties  

DEFF Research Database (Denmark)

Triggered in part by the advent of high resolution commercial optical satellites, the analysis of open-source satellite imagery has now established itself as an important tool for monitoring nuclear activities throughout the world (Chitumbo et al 2001). Whereas detection of land cover and land use change is a commonplace application in remote sensing, the detection of anthropogenic changes associated with nuclear activities, whether declared or clandestine, presents a difficult challenge. It is necessary to discriminate subtle, often weak signals of interest on a background of irrelevant or uninteresting changes, see e.g. (Canty and Schlittenhardt 2001). In our contribution we focus attention on the use of conventional multispectral earth observation satellite platforms with moderate ground resolution (Landsat TM, ASTER, SPOT) to detect changes over wide areas which are relevant to nuclear non-proliferation and disarmament treaties. The analysis is based upon the multivariate alteration detection (MAD) algorithm proposed by Nielsen et al. 1998 with the inclusion of a recent refinement which puts weight on difficult observations (Nielsen to be published). The multispectral data are pre-processed by orthorectification, illumination angle correction, image registration to sub-pixel accuracy and, where appropriate, wavelet-based panchromatic sharpening. We illustrate the techniques with a number of case studies involving the location of underground nuclear explosions and detection of uranium mining sites. In the former case the change signals are compared with existing seismic data, which include explosion times, locations, yields and depths of burial as well as data about surface collapse (subsidence) phenomena like e.g. crater depth and diameter and test surface-collapse times. The work has been carried out within the framework of the Global Monitoring for Security and Stability Network of Excellence (GMOSS) initiated by the European Commission. Chitumbo, K., Robb, S., Bunney, J. and Lev\\$\\backslash\\$'e, G., IAEA Satellite imagery and the Department of Safeguards, Proceedings of the Symposium on International Safeguards, Vienna 2001 IAEA-SM-367/16/08) on CD-ROM. Canty, M. J., Schlittenhardt, J., Locating the 1998 Indian nuclear tests, Eos, Transactions American Geophysical Union 82(3), 2001, pp. 25--29. Nielsen, A. A., Conradsen, K. and Simpson, J. J., Multivariate alteration detection (MAD) and MAF processing in multispectral, bitemporal image data: New approaches to change detection studies, Remote Sens. Environ. 64(1), 1998, pp. 1--19. Nielsen, A. A., Iteratively re-weighted multivariate alteration detection in multi- and hyperspectral data, to be published.

Nielsen, Allan Aasbjerg

2005-01-01

86

A Comprehensive Segmentation, Registration, and Cancer Detection Scheme on 3 Tesla In Vivo Prostate DCE MRI  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recently, high resolution 3 Tesla (T) Dynamic Contrast-Enhanced MRI (DCE-MRI) of the prostate has emerged as a promising technique for detecting prostate cancer (CaP). Computer-aided diagnosis (CAD) schemes for DCE-MRI data have thus far been primarily developed for breast cancer and typically involve model fitting of dynamic intensity changes as a function of contrast agent uptake by the lesion, as done by schemes such as the 3 time point (TP) scheme. Non-linear dimensionality reduction sche...

Viswanath, Satish; Bloch, Nicholas; Rofsky, Neil; Lenkinski, Robert; Genega, Elisabeth; Chappelow, Jonathan; Toth, Robert; Madabhushi, Anant

2008-01-01

87

Detection of apical hypertrophic cardiomyopathy by cardiovascular MRI  

International Nuclear Information System (INIS)

Objective: To investigate the clinical value of cardiovascular magnetic resonance imaging (cMRI) in identifying apical hypertrophic cardiomyopathy. Methods: Sixty-five patients with typical apical hypertrophic cardiomyopathy (T-AHCM), 51 patients with pre-apical hypertrophic cardiomyopathy (P-AHCM)and 26 normal controls were confirmed by cMRI. All cases underwent electrocardiogram and echocardiography, of which 16 and 34 cases were studied by radionuclide 99Tcm-MIBI SPECT myocardial scanning and coronary angiography plus left ventriculography, respectively. Results: cMRI confirmed all patients with apical hypertrophic cardiomyopathy, but echocardiography missed 96 cases. Two chamber and four chamber views of cine-cMRI were considered as the best position to show detailed structure of cardiac apex. Forty-seven cases showed spade-like configuration of left ventricular cavity in T-AHCM group, but only 15 patients in P-AHCM group presented the same character. T-AHCM group showed higher apical thickness and ratio of the apical wall thickness to that at basal level than P-AHCM group(18.6±2.7) mm vs (13.6±1.0) mm, 2.2±0.5 vs 1.6±0.3, P<0.05), and the ratios of both T-AHCM group and P-AHCM group were significantly higher than that of control group (9.5±1.7) mm, 1.1±0.1, P<0.05). Hypertrophic wall thickening was lesser in T-AHCM group than in P-AHCM group, while the values of both T-AHCM group and P-AHCM group were significantly lesser than that of control one. Conclusion: MRI is the best diagnostic modality for AHCM, which is highly accurate and better than echocardiography, especially for the diagnosis of mild hypertrophy in the early stage. (authors)

88

Comparative study of whole-body MRI and bone scintigraphy for the detection of bone metastases  

International Nuclear Information System (INIS)

Aim: To assess and compare the diagnostic accuracy of whole-body magnetic resonance imaging (MRI) and bone scintigraphy in the detection of metastases to bone. Material and methods: Forty randomly selected patients with known malignant tumours were prospectively studied using bone scintigraphy and whole-body MRI. Two patients were excluded. Symptoms of bone metastasis were present in 29 (76%) patients and absent in nine (24%). Findings were classified into four categories according to the probability of bone metastasis: (1) negative, (2) probably negative, (3) probably positive, and (4) positive. Diagnostic accuracy was determined according to the area under the receiver operating characteristic (ROC) curve. The definitive diagnosis was reached using other imaging techniques, biopsy, or 12 months clinical follow-up. Results: Metastases were present in 18 patients. The sensitivity, specificity, and diagnostic accuracy were 94, 90, and 92%, respectively, for whole-body MRI and 72, 75, and 74%, respectively, for bone scintigraphy. Diagnostic accuracy measured by the area under the ROC curve was significantly higher for whole-body MRI (96%) than for bone scintigraphy (77%; p<0.05). Interobserver agreement measured by the kappa index was significantly higher for whole-body MRI (0.895) than for bone scintigraphy (0.524; p<0.05). Whole-body MRI detected lesions in tissues other than bone in 17 (45%) patients. Conclusions: Whole-body MRI is more accurate and more objective than bone scintigraphy for the detection of bone metastases. Whole-body MRI can also detect lesions in tissues other than bone.

89

Comparative study of whole-body MRI and bone scintigraphy for the detection of bone metastases  

Energy Technology Data Exchange (ETDEWEB)

Aim: To assess and compare the diagnostic accuracy of whole-body magnetic resonance imaging (MRI) and bone scintigraphy in the detection of metastases to bone. Material and methods: Forty randomly selected patients with known malignant tumours were prospectively studied using bone scintigraphy and whole-body MRI. Two patients were excluded. Symptoms of bone metastasis were present in 29 (76%) patients and absent in nine (24%). Findings were classified into four categories according to the probability of bone metastasis: (1) negative, (2) probably negative, (3) probably positive, and (4) positive. Diagnostic accuracy was determined according to the area under the receiver operating characteristic (ROC) curve. The definitive diagnosis was reached using other imaging techniques, biopsy, or 12 months clinical follow-up. Results: Metastases were present in 18 patients. The sensitivity, specificity, and diagnostic accuracy were 94, 90, and 92%, respectively, for whole-body MRI and 72, 75, and 74%, respectively, for bone scintigraphy. Diagnostic accuracy measured by the area under the ROC curve was significantly higher for whole-body MRI (96%) than for bone scintigraphy (77%; p<0.05). Interobserver agreement measured by the kappa index was significantly higher for whole-body MRI (0.895) than for bone scintigraphy (0.524; p<0.05). Whole-body MRI detected lesions in tissues other than bone in 17 (45%) patients. Conclusions: Whole-body MRI is more accurate and more objective than bone scintigraphy for the detection of bone metastases. Whole-body MRI can also detect lesions in tissues other than bone.

Balliu, E., E-mail: eballiu@gmail.co [Department of Magnetic Resonance, IDI Girona, Hospital Universitari de Girona Dr Josep Trueta, Girona (Spain); Boada, M.; Pelaez, I. [Department of Magnetic Resonance, IDI Girona, Hospital Universitari de Girona Dr Josep Trueta, Girona (Spain); Vilanova, J.C. [Department of Magnetic Resonance, Clinica Girona - Hospital Sta Caterina, Girona (Spain); Barcelo-Vidal, C. [Department of Computer Science and Applied Mathematics, University of Girona (Spain); Rubio, A.; Galofre, P. [Department of Nuclear Medicine, IDI Girona, Hospital Universitari de Girona Dr Josep Trueta, Girona (Spain); Castro, A. [Department of Internal Medicine, Hospital Universitari de Girona Dr Josep Trueta, Girona (Spain); Pedraza, S. [Department of Magnetic Resonance, IDI Girona, Hospital Universitari de Girona Dr Josep Trueta, Girona (Spain)

2010-12-15

90

MRI in the evaluation of spina bifida patients in the remote period after meningomyelocele repair  

Energy Technology Data Exchange (ETDEWEB)

MRI was performed on 22 patients ranging in age from 3 months to 16 years who had closure of their meningomyelocele shortly after birth. These patients had developed new clinical findings suggestive of spinal cord dysfunction. MRI showed low placement of the spinal cord in all 22. Six patients had lipomas, five had diastematomyelia and six had hydromyelia. Four patients had an obviously dysplastic terminal cord. (orig.).

Williamson, M.R.; Glasier, C.M.; Chadduck, W.M.; Angtuaco, E.J.C.; Binet, E.F.

1989-07-01

91

Fast spin echo MRI and bone scintigraphy in the detection of skeletal metastases  

International Nuclear Information System (INIS)

Twenty-one patients with a suspicion of carcinomatous bone metastases were evaluated with both conventional T1 weighted (T1w), T2 weighted (T2w) and fast T2w SE (FSE) sequences (thoraco-lumbar spine and pelvis) and whole body bone scintigraphy. Conventional and fast T2w SE sequences detected the same number of lesions while bone scintigraphy detected only 70% of the lesions seen on MRI. However, more importantly, in 11 of the 21 patients bone scintigraphy detected lesions outside the MR field of view, lying in the ribs, skull, scapulae and extremities and in 4 of them, MRI was negative. Our results suggest first that fast SE MRI can replace conventional SE MRI when looking for carcinomatous bone metastases in the axial skeleton, with the advantage of a four to six times reduced acquisition time for fast T2w sequences. However, the limited field of view still limits the usefulness of MRI and whole body bone scintigraphy remains the screening modality for bone metastases. Fast MRI plays an important complementary role. (orig.)

92

Building multiclass classifiers for remote homology detection and fold recognition  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Protein remote homology detection and fold recognition are central problems in computational biology. Supervised learning algorithms based on support vector machines are currently one of the most effective methods for solving these problems. These methods are primarily used to solve binary classification problems and they have not been extensively used to solve the more general multiclass remote homology prediction and fold recognition problems. Results We present a comprehensive evaluation of a number of methods for building SVM-based multiclass classification schemes in the context of the SCOP protein classification. These methods include schemes that directly build an SVM-based multiclass model, schemes that employ a second-level learning approach to combine the predictions generated by a set of binary SVM-based classifiers, and schemes that build and combine binary classifiers for various levels of the SCOP hierarchy beyond those defining the target classes. Conclusion Analyzing the performance achieved by the different approaches on four different datasets we show that most of the proposed multiclass SVM-based classification approaches are quite effective in solving the remote homology prediction and fold recognition problems and that the schemes that use predictions from binary models constructed for ancestral categories within the SCOP hierarchy tend to not only lead to lower error rates but also reduce the number of errors in which a superfamily is assigned to an entirely different fold and a fold is predicted as being from a different SCOP class. Our results also show that the limited size of the training data makes it hard to learn complex second-level models, and that models of moderate complexity lead to consistently better results.

Karypis George

2006-10-01

93

Asparagine in plums detected by CEST-MRI.  

Science.gov (United States)

Magnetic resonance imaging (MRI) relies on the topological distribution of the intense water NMR signal and may be used to report about changes in the internal structures of fruits associated to ripening, storing, pathogen infection. Herein the use of CEST-MRI (chemical exchange saturation transfer) is introduced to show that in addition to structural information, insights into the presence in the fruits of specific chemicals may be gained. Asparagine is present in plums at relatively high concentration (?10-20mM) and owns two amide protons (at 2.1 and 2.8ppm down field from water) in slow exchange with water protons. By irradiating the amide resonances with a proper rf-field it is possible to transfer saturated magnetization to the "bulk" water signal. The attained change in signal intensity reflects the extent of prototropic exchange between amide and water protons that is modulated by the local pH. PMID:25236190

Podda, Rachele; Delli Castelli, Daniela; Digilio, Giuseppe; Gullino, Maria Lodovica; Aime, Silvio

2015-02-15

94

Pathophysiological changes detected by MRI within 24 hours after head injury  

Energy Technology Data Exchange (ETDEWEB)

This report concerns the evaluation of the usefulness of high-field magnetic resonance imaging (MRI) for the diagnosis and prognosis of patients with head injuries. For this purpose we compared the CT and MRI results obtained on 48 such patients. MRI of all cases was taken within 24 hours after head injury using a 1.5-Tesla unit. The sensitivity of the two modalities in the detection of small traumatic lesions was compared. Traumatic lesions of 23 patients (47.9%) were not detected by CT, but they were demonstrated on MRI. Overall, MRI was significantly more sensitive than CT in detecting early and/or subtle traumatic changes of the brain parenchyma (P<0.01, {chi}-square with 2df.), particularly lesions adjacent to bone and beneath extra-axial hematomas. Only for diagnosing acute subarachnoid hemorrhages was MRI inferior to CT. The MRI findings in the acute stage of head injury can be summarized as follows : (A) Many small hemorrhagic lesions were detected by MRI in the acute stage as hypointense spots on T{sub 1}-WI and T{sub 2}-WI. (B) Corpus callosum lesions with hyperintensity on T{sub 2}-WI were in fact hemorrhagic contusions by signal changes on sequential MRI. The follow-up of chronological changes of a given corpus callosum lesion was essential for confirmation of its pathology. (C) In one case, scratch-like lesions with strong hypointensity on T{sub 1}-WI and hyperintensity on T{sub 2}-WI were clearly demonstrated in the white matter. These observations appeared to indicate axonal damages. (D) Even if initial GCS score is low (<8), a negative MRI finding seemed to indicate a relatively favorable outcome. (E) We had one patient whose lesions, considered to be an edema, showed transient hyperintensity on T{sub 2}-WI and subsequently disappeared completely. We conclude that performing MRI in the early stage of a head injury is of utility for the understanding of pertinent pathophysiological changes and for predicting outcome. (author).

Nagaoka, Tsukasa; Wakabayashi, Shinichi; Nariai, Tadashi; Ohno, Kikuo; Hirakawa, Kimiyoshi [Tokyo Medical and Dental Univ. (Japan). School of Medicine; Fukui, Shinsuke; Takei, Hidenori

1995-03-01

95

A tunable MWIR laser remote sensor for chemical vapor detection  

Science.gov (United States)

The Air Force vision for Global Virtual Presence suggests a need for active remote sensing systems that provide both global coverage and the ability to detect multiple gaseous chemical species at low concentration from a significant standoff distance. The system will need to have acceptable weight, volume, and power characteristics, as well as a long operating lifetime for integration with various surveillance platforms. Laser based remote sensing systems utilizing the differential absorption lidar (DIAL) technique are promising for long range chemical sensing applications. Recent advancements in pulsed, diode pumped solid state laser (DPSSL) technology and in tunable optical parametric oscillators (OPO) make broadly tunable laser transmitters possible for the DIAL system. Also the characteristic narrow spectral bandwidth of these laser devices provides high measurement sensitivity and spectral selectivity with the potential to avoid interfering species. Rocketdyne has built and tested a tunable, midwave infrared (MWIR) DIAL system using DPSSL/OPO technology. The key to the system is a novel tuning and line narrowing technology developed for the OPO. The tuning system can quickly adjust to the desired wavelength and precisely locate a narrow spectral feature of interest. Once the spectral feature is located, a rapid dither tuning technique is employed. The laser pulses are tuned ``on'' and ``off'' the spectral resonance of a molecule with precise and repeatable performance as required to make the DIAL measurement. To date, the breadboard system has been tested by measuring methane, ethane, and sulfur dioxide in a calibrated gas cell at a range of 60 meters.

Bunn, Thomas L.; Noblett, Patricia M.; Otting, William D.

1998-01-01

96

Remote detection of organics using Fourier transform infrared spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

Fourier transform infrared (FTIR) spectroscopy is an ideal technique for remote detection of organic emissions. There is an atmospheric window in the 1200 to 800 cm{sup {minus}1} region, which corresponds to the fingerprint'' region for organic molecules. Virtually all organic molecules have a unique absorption/emission pattern in the fingerprint region. A remote-passive FTIR relies on ambient emission of infrared energy from organics to obtain spectra. The instrumentation consists of inlet optics, and interferometer, a mercury cadmium telluride (MCT) detector, and an on-board computer. The transportable unit measures 40 cm by 50 cm and has been used to collect data while mounted on a helicopter or ground vehicle. Through the use of this FTIR combined with least squares software, it is possible to analyze qualitatively and quantitatively for organic vapors from either the air or ground. The data presented will include quantitative releases of common organics present in incinerator stacks, hazardous wastes, and illegal laboratories. Data will be presented for pure compounds, mixtures, and target analytes in the presence of interfering compounds. The sensitivity, reproducibility, and the potential of the technique will be discussed. 1 ref., 8 figs., 6 tabs.

Demirgian, J.C.; Spurgash, S.M.

1990-01-01

97

Remote detection of organics using Fourier transform infrared spectroscopy  

International Nuclear Information System (INIS)

Fourier transform infrared (FTIR) spectroscopy is an ideal technique for remote detection of organic emissions. There is an atmospheric window in the 1200 to 800 cm-1 region, which corresponds to the ''fingerprint'' region for organic molecules. Virtually all organic molecules have a unique absorption/emission pattern in the fingerprint region. A remote-passive FTIR relies on ambient emission of infrared energy from organics to obtain spectra. The instrumentation consists of inlet optics, and interferometer, a mercury cadmium telluride (MCT) detector, and an on-board computer. The transportable unit measures 40 cm by 50 cm and has been used to collect data while mounted on a helicopter or ground vehicle. Through the use of this FTIR combined with least squares software, it is possible to analyze qualitatively and quantitatively for organic vapors from either the air or ground. The data presented will include quantitative releases of common organics present in incinerator stacks, hazardous wastes, and illegal laboratories. Data will be presented for pure compounds, mixtures, and target analytes in the presence of interfering compounds. The sensitivity, reproducibility, and the potential of the technique will be discussed. 1 ref., 8 figs., 6 tabs

98

Bladder cancer: utility of MRI in detection of occult muscle-invasive disease  

Energy Technology Data Exchange (ETDEWEB)

Background. The presence of muscularis propria invasion by bladder cancer is a key factor in prognosis and treatment decisions, although may be missed by biopsy due to sampling error. MRI has shown potential for detection of muscle invasion but has not specifically been evaluated for this purpose in the setting of bladder cancer patients without evidence of muscle invasion on initial biopsy. Purpose. To evaluate the role of MRI in detection of muscularis propria invasion by bladder cancer following a pathologic diagnosis of non-invasive tumor. Material and Methods. This retrospective study included 23 patients who underwent pelvic MRI following a pathologic diagnosis of bladder cancer without muscularis propria invasion and in whom additional histologic evaluation was performed following MRI. Two radiologists in consensus reviewed T2-weighted images to identify those cases suspicious for muscle invasion on MRI. The radiologists identified whether cases suspicious for invasion demonstrated disruption of the T2-hypointense muscularis layer of the bladder wall, peri-vesical fat stranding, and peri-vesical soft tissue nodularity. Findings were compared with pathologic results obtained after MRI. Results. Suspicion was raised for muscle invasion in eight of 23 cases, four of which exhibited invasion on follow-up pathology. No case without suspicion on MRI exhibited invasion on follow-up pathology. Therefore, sensitivity and specificity were 100% and 79%, respectively. Among individual findings, muscularis disruption on T2WI exhibited sensitivity of 100% and specificity of 79%, peri-vesical fat stranding exhibited sensitivity and specificity of 50% and 84%, and peri-vesical soft tissue nodularity exhibited sensitivity and specificity of 25% and 100%. Conclusion. MRI demonstrated high sensitivity for detection of muscle invasion in cases of bladder cancer without invasion on initial histologic assessment. Muscularis disruption on T2WI appeared to exhibit a better combination of sensitivity and specificity than did peri-vesical changes.

Rosenkrantz, Andrew B. [Dept. of Radiology, NYU Langone Medical Center, New York (United States)], E-mail: Andrew.rosenkrantz@nyumc.org; Mussi, Thais C. [Dept. of Radiology, NYU Langone Medical Center, New York (United States); Hospital Israelita Albert Einstein, Sao Paulo (Brazil); Melamed, Jonathan [Dept. of Pathology, NYU Langone Medical Center, New York (United States); Taneja, Samir S.; Huang, William C. [Dept. of Urology, Div. of Urologic Oncology, NYU Langone Medical Center, New York (United States)

2012-07-15

99

Bladder cancer: utility of MRI in detection of occult muscle-invasive disease  

International Nuclear Information System (INIS)

Background. The presence of muscularis propria invasion by bladder cancer is a key factor in prognosis and treatment decisions, although may be missed by biopsy due to sampling error. MRI has shown potential for detection of muscle invasion but has not specifically been evaluated for this purpose in the setting of bladder cancer patients without evidence of muscle invasion on initial biopsy. Purpose. To evaluate the role of MRI in detection of muscularis propria invasion by bladder cancer following a pathologic diagnosis of non-invasive tumor. Material and Methods. This retrospective study included 23 patients who underwent pelvic MRI following a pathologic diagnosis of bladder cancer without muscularis propria invasion and in whom additional histologic evaluation was performed following MRI. Two radiologists in consensus reviewed T2-weighted images to identify those cases suspicious for muscle invasion on MRI. The radiologists identified whether cases suspicious for invasion demonstrated disruption of the T2-hypointense muscularis layer of the bladder wall, peri-vesical fat stranding, and peri-vesical soft tissue nodularity. Findings were compared with pathologic results obtained after MRI. Results. Suspicion was raised for muscle invasion in eight of 23 cases, four of which exhibited invasion on follow-up pathology. No case without suspicion on MRI exhibited invasion on follow-up pathology. Therefore, sensitivity and specificity were 100% and 79%, respectively. Among individual findings, muscularis disruption on T2WI exhibited sensitivity of 100% and specificity of 79%, peri-vesical fat stranding exhibited sensitivity and specificity of 50% and 84%, and peri-vesical soft tissue nodularity exhibited sensitivity and specificity of 25% and 100%. Conclusion. MRI demonstrated high sensitivity for detection of muscle invasion in cases of bladder cancer without invasion on initial histologic assessment. Muscularis disruption on T2WI appeared to exhibit a better combination of sensitivity and specificity than did peri-vesical changes

100

Detection of local recurrences of limb soft tissue sarcomas: Is magnetic resonance imaging (MRI) relevant?  

Energy Technology Data Exchange (ETDEWEB)

The role of systematic magnetic resonance imaging (MRI) after resection of soft tissue sarcomas (STS) of the limb is opened to debate. The aim of our study was to retrospectively evaluate the effectiveness of a systematic MRI examination performed in 124 adult patients treated between 1996 and 2006 for a non-metastatic limb STS at our centre: 86 patients (70%) had clear resection margins (R0) and 111 patients (90%) received an adjuvant radiotherapy. Among the 11 local recurrences (9%) which were observed, MRI was able to detect only 2 asymptomatic local recurrences, one with and one without synchronous metastasis. Both had microscopically involved margins (R1). In contrast, MRI showed 11 false positive cases. As the predictive positive value of MRI was 42%, clinical follow-up seems to be more effective. As observed in our study, systematic MRI examination is not relevant for the follow-up of all limb soft tissue sarcomas. A prospective study could be promoted to evaluate the role of MRI in patients at high risk of local recurrence.

Labarre, D. [Department of Radiology, Institut Claudius Regaud, 20-24 rue du Pont Saint Pierre, 31052 Toulouse (France); Aziza, R. [Department of Radiology, Institut Claudius Regaud, 20-24 rue du Pont Saint Pierre, 31052 Toulouse (France)], E-mail: aziza.richard@claudiusregaud.fr; Filleron, T. [Department of Biostatistics, Institut Claudius Regaud, 20-24 rue du Pont Saint Pierre, 31052 Toulouse (France); Delannes, M. [Department of Radiotherapy, Institut Claudius Regaud, 20-24 rue du Pont Saint Pierre, 31052 Toulouse (France); Delaunay, F. [Department of Radiology, Institut Claudius Regaud, 20-24 rue du Pont Saint Pierre, 31052 Toulouse (France); Marques, B. [Department of Anatomic Pathology, Institut Claudius Regaud, 20-24 rue du Pont Saint Pierre, 31052 Toulouse (France); Ferron, G. [Department of Surgery, Institut Claudius Regaud, 20-24 rue du Pont Saint Pierre, 31052 Toulouse (France); Chevreau, C. [Department of Clinical Oncology, Institut Claudius Regaud, 20-24 rue du Pont Saint Pierre, 31052 Toulouse (France)

2009-10-15

 
 
 
 
101

Remote photoacoustic detection of liquid contamination of a surface.  

Science.gov (United States)

A method for the remote detection and identification of liquid chemicals at ranges of tens of meters is presented. The technique uses pulsed indirect photoacoustic spectroscopy in the 10-microm wavelength region. Enhanced sensitivity is brought about by three main system developments: (1) increased laser-pulse energy (150 microJ/pulse), leading to increased strength of the generated photoacoustic signal; (2) increased microphone sensitivity and improved directionality by the use of a 60-cm-diameter parabolic dish; and (3) signal processing that allows improved discrimination of the signal from noise levels through prior knowledge of the pulse shape and pulse-repetition frequency. The practical aspects of applying the technique in a field environment are briefly examined, and possible applications of this technique are discussed. PMID:12952337

Perrett, Brian; Harris, Michael; Pearson, Guy N; Willetts, David V; Pitter, Mark C

2003-08-20

102

Recent trends in Remote homology detection: an Indian Medley  

Science.gov (United States)

The development of remote homology detection methods is a challenging area in Bioinformatics. Sequence analysis-based approaches that address this problem have employed the use of profiles, templates and Hidden Markov Models (HMMs). These methods often face limitations due to poor sequence similarities and non-uniform sequence dispersion in protein sequence space. Search procedures are often asymmetrical due to over or under-representation of some protein families and outliers often remain undetected. Intermediate sequences that share high similarities with more than one protein can help overcome such problems. Methods such as MulPSSM and Cascade PSI-BLAST that employ intermediate sequences achieve better coverage of members in searches. Others employ peptide modules or conserved patterns of motifs or residues and are effective in overcoming dependencies on high sequence similarity to establish homology by using conserved patterns in searches. We review some of these recent methods developed in India in the recent past. PMID:17597865

Gowri, Venkataraman S.; Sandhya, Sankaran

2006-01-01

103

Whole-body MRI for detecting osseous metastases: comparison with bone scintigraphy  

International Nuclear Information System (INIS)

Objective: The aim of the study was to evaluate the reliability of whole-body MRI (WB- MRI) in detecting osseous metastases. Methods: Thirty patients verified with malignant tumor by histology were enrolled. All the patients underwent WB-MRI and bone scintigraphy (BS) with a two week interval. Clinical information, conventional MRI and CT images, and follow-up data were collected as gold standard for the diagnosis of bone metastases. The data of 30 patients and 270 segments as study unit respectively were analyzed. The sensitivity and specificity between WB-MRI and BS were compared with McNemar test. Results: Bone metastases were confirmed in 27 of 30 patients by gold standard. Twenty-five patients with bone metastases were detected by WB-MRI and no false-positive cases. Twenty-seven patients with bone metastases were found by BS but having two false-positive cases. With patients as study unit, the diagnostic sensitivity of WB-MRI and BS were both 92.6% (25/27) and the specificity were 100% (3/3) and 33.3% (1/3), respectively. The area under ROC curve of WB-MRI and BS were 0.9630 and 0.6296, respectively (P>0.05). With segments as study unit, 119 bone metastases segments were confirmed. The diagnostic sensitivity of WB-MRI and BS were 90.8% (108/119) and 70.6% (84/119) (P<0.01). while the specificity were 98.0% (148/151) and 90.7% (137/151), respectively (P<0.01). The area under ROC curve of WB-MRI and BS were 0.9438 and 0.8066. The former was obviously higher than the latter (P< 0.01). Meanwhile, by WB-MRI, 3 cases coexisting with brain metastases, 4 cases with lung metastases, and 4 cases with hepatic metastases were found. Conclusion: WB-MRI was a good tool for screening osseous metastases. (authors)

104

Active remote detection of radioactivity based on electromagnetic signatures  

Energy Technology Data Exchange (ETDEWEB)

This paper presents a new concept for the remote detection of radioactive materials. The concept is based on the detection of electromagnetic signatures in the vicinity of radioactive material and can enable stand-off detection at distances greater than 100?m. Radioactive materials emit gamma rays, which ionize the surrounding air. The ionized electrons rapidly attach to oxygen molecules forming O{sub 2}{sup ?} ions. The density of O{sub 2}{sup ?} around radioactive material can be several orders of magnitude greater than background levels. The elevated population of O{sub 2}{sup ?} extends several meters around the radioactive material. Electrons are easily photo-detached from O{sub 2}{sup ?} ions by laser radiation. The photo-detached electrons, in the presence of laser radiation, initiate avalanche ionization which results in a rapid increase in electron density. The rise in electron density induces a frequency modulation on a probe beam, which becomes a direct spectral signature for the presence of radioactive material.

Sprangle, P. [Plasma Physics Division, Naval Research Laboratory, Washington, District of Columbia 20375 (United States); University of Maryland, College Park, Maryland 20742-4111 (United States); Hafizi, B. [Plasma Physics Division, Naval Research Laboratory, Washington, District of Columbia 20375 (United States); Milchberg, H.; Nusinovich, G. [University of Maryland, College Park, Maryland 20742-4111 (United States); Zigler, A. [University of Maryland, College Park, Maryland 20742-4111 (United States); Icarus Research, Inc., PO Box 30780, Bethesda, Maryland 20824-0780 (United States); The Hebrew University of Jerusalem, Jerusalem (Israel)

2014-01-15

105

Incident and Traffic-Bottleneck Detection Algorithm in High-Resolution Remote Sensing Imagery  

Digital Repository Infrastructure Vision for European Research (DRIVER)

One of the most important methods to solve traffic congestion is to detect the incident state of a roadway. This paper describes the development of a method for road traffic monitoring aimed at the acquisition and analysis of remote sensing imagery. We propose a strategy for road extraction, vehicle detection and incident detection from remote sensing imagery using techniques based on neural networks, Radon transform for angle detection and traffic-flow measurements. Traffic-bottleneck detect...

Kahaki, S. M. M.; Md. Jan Nordin; Amir Hossein Ashtari

2012-01-01

106

Vehicle Accident Automatic Detection and Remote Alarm Device  

Directory of Open Access Journals (Sweden)

Full Text Available The Rapid growth of  technology and infrastructure has made our lives more easy . The advent of technology has also increased the traffic hazards and the  road  accident take place frequently which causes huge loss of life and property because of the poor emergency facilities. Our project will provide an optimum solution to this draw back. An accelerometer can be used in a car alarm application so that dangerous driving can be detected . It can be used as a crash or rollover detector of the vehicle during and after a crash. With signals from an accelerometer, a severe accident can be recognized. According to this project when a vehicle meets with an accident immediately Vibration sensor will detect the signal or if a car rolls over, an Micro electro mechanical system(MEMS sensor will detects the signal and sends it to ARM controller. Microcontroller sends the alert message through the GSM MODEM including the location to police control room or a rescue team. So the police can immediately trace the location through the GPS MODEM, after receiving the information. Then after conforming the location necessary action will be taken. If the person meets with a small accident or if there is no serious threat to anyone`s life, then the alert message can be terminated by the driver by a switch provided in order to avoid wasting the valuable time of the medical rescue team. This paper is useful in detecting the accident precisely by means of both vibration sensor and Micro electro Mechanical system(MEMS or accelerometer. As there is a scope for improvement and as a future implementation we can add a wireless webcam for capturing the images which will help in providing driver`s assistance. Keywords - Accident ,Automatic Detection, Micro electro Mechanical system , Remote Alarm Device, Vehicle

Varsha Goud

2012-06-01

107

A comprehensive system for evaluation of remote sequence similarity detection  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Accurate and sensitive performance evaluation is crucial for both effective development of better structure prediction methods based on sequence similarity, and for the comparative analysis of existing methods. Up to date, there has been no satisfactory comprehensive evaluation method that (i is based on a large and statistically unbiased set of proteins with clearly defined relationships; and (ii covers all performance aspects of sequence-based structure predictors, such as sensitivity and specificity, alignment accuracy and coverage, and structure template quality. Results With the aim of designing such a method, we (i select a statistically balanced set of divergent protein domains from SCOP, and define similarity relationships for the majority of these domains by complementing the best of information available in SCOP with a rigorous SVM-based algorithm; and (ii develop protocols for the assessment of similarity detection and alignment quality from several complementary perspectives. The evaluation of similarity detection is based on ROC-like curves and includes several complementary approaches to the definition of true/false positives. Reference-dependent approaches use the 'gold standard' of pre-defined domain relationships and structure-based alignments. Reference-independent approaches assess the quality of structural match predicted by the sequence alignment, with respect to the whole domain length (global mode or to the aligned region only (local mode. Similarly, the evaluation of alignment quality includes several reference-dependent and -independent measures, in global and local modes. As an illustration, we use our benchmark to compare the performance of several methods for the detection of remote sequence similarities, and show that different aspects of evaluation reveal different properties of the evaluated methods, highlighting their advantages, weaknesses, and potential for further development. Conclusion The presented benchmark provides a new tool for a statistically unbiased assessment of methods for remote sequence similarity detection, from various complementary perspectives. This tool should be useful both for users choosing the best method for a given purpose, and for developers designing new, more powerful methods. The benchmark set, reference alignments, and evaluation codes can be downloaded from ftp://iole.swmed.edu/pub/evaluation/.

Kim Bong-Hyun

2007-08-01

108

Whole body MRI for detecting metastatic bone tumor. Comparison with bone scintigrams  

International Nuclear Information System (INIS)

The purpose of this study was to compare the effectiveness of whole body MRI (WB-MRI [magnetic resonance imaging]) and bone scintigram (BS) at detecting bone metastasis. WB-MRI was performed on 16 patients for detecting bone metastasis (6 breast carcinoma, 7 prostatic carcinoma, 1 renal cell carcinoma [RCC], 1 hepatocellular carcinoma [HCC], and 1 primary unknown). BS was also performed in all cases. Patients were placed on a table top extender (Philips Medical Systems). The maximal longitudinal field of view (FOV) was 200 cm. At first, the total spine was imaged in the sagittal plane with a three-station approach for two image sets (fast spin-echo [SE] T1-weighted images [T1WI] and short tau inversion recovery [STIR] images). The whole body was then imaged in the coronal plane with a seven-station approach for two image sets (fast field echo [FFE] T1WI and STIR). Total examination time, including patient positioning, was within 40 min. Three independent radiologists interpreted the imaging data. WB-MRI identified 5 cases of 24 lesions as bone metastasis, while BS identified 3 cases of 25 lesions. Concordance between WB-MRI and BS was seen in 3 cases of 22 lesions (81%). For two cases of 2 lesions, which were identified only with WB-MRI, the lesions were located in the sacrum and thoracic spine. For one case of 3 lesions, which was identified only with BS, the lesions were located in the skull and rib. WB-MRI was an excellent method foand rib. WB-MRI was an excellent method for screening bone metastasis, especially the vertebral body. (author)

109

Small colorectal liver metastases: Detection with SPIO-enhanced MRI in comparison with gadobenate dimeglumine-enhanced MRI and CT imaging  

International Nuclear Information System (INIS)

The aim of this prospective study was to compare the diagnostic role of superparamagnetic iron oxide (SPIO)-enhanced liver magnetic resonance imaging (MRI) versus gadobenate dimeglumine (GbD)-enhanced MRI and computed tomography (CT) investigations for detection of small (less than 1 cm) colorectal liver metastases (LMs) of colorectal cancer. Seventy-eight LMs in 16 patients were evaluated with dynamic CT imaging, GbD-enhanced dynamic MR imaging and SPIO-enhanced MR imaging. Two radiologists were reviewed the LMs seperately. Agreement between the readers and three algorithms was analyzed. Differences between the lesion detection ratios of the methods were analyzed by two proportion z test. Sensitivity values of each modality were also calculated. Interobserver agreement values with kappa analysis were found to be the best for three modalities and kappa values were 0.866, 0.843, and 1.0 respectively. For all 78 LMs, SPIO-enhanced MRI detected all lesions (100% sensitivity). This sensitivity value was higher than GbD-enhanced MRI, and there was a significant difference (p < 0.05). GbD-enhanced MRI depicted 71 lesions and this modality could not detected 7 lesions (91% sensitivity). This modality had moderate sensitivity, and this value is greater than CT imaging, so there was a significant difference also (p < 0.05). Dynamic triphasic CT imaging detected 64 (R1) and 65 (R2) LMs. This modality had the lowest sensitivity (R1: 0.82, R2: 0.83 respectively). Only SPIO-enhanced MRI was able to detect all LMs less than 1 cm. LMs were the best detected with SPIO-enhanced MRI. We recommend SPIO-enhanced MRI to be the primary alternative modality especially for diagnosis of small colorectal LMs.

110

MRI for troubleshooting detection of prostate cancer; MRT zur Problemloesung beim Nachweis des Prostatakarzinoms  

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Prostate cancer is the most common malignancy in males. Men aged 50 and older are recommended to undergo an annual digital rectal examination (DRE) and determination of prostate-specific antigen (PSA) in serum for early detection. However, prostate biopsies guided by transrectal ultrasound (TRUS) come up negative for cancer in many patients despite having PSA levels above 4 ng/ml. T2-weighted Magnetic Resonance Imaging (MRI) is able to represent the prostate including the surrounding anatomy and depict suspicious areas of low intensity within a high-intensity peripheral zone. MRI has a higher sensitivity for detecting prostate carcinomas than DRE and TRUS in patients having an elevated PSA value and a negative core biopsy. However, its specificity is poor since other abnormalities such as prostatic intraepithelial neoplasia (PIN), prostatitis, scars, or haemmorrhage have a similar MRI appearance. The use of additional techniques such as MR spectroscopy and contrast-enhanced dynamic MRI improves sensitivity, but in particular it improves the specificity of tumor detection. Newly developed biopsy devices enable the performance of targeted biopsies in areas that appear suspicious in the MRI. (orig.)

Beyersdorff, D.; Hamm, B. [Universitaetsmedizin Berlin, Charite Mitte (Germany)

2005-06-01

111

Detection of focal epileptic activity using combined simultaneous electroencephalogram-functional MRI  

International Nuclear Information System (INIS)

Objective: To observe the brain activation of interictal epiletiform discharges (IEDs) and to localize the epileptogenic foci of epilepsy. Methods: The electroencephalogram (EEG) and functional MRI data of 12 focal epileptic patients were acquired using a combination of EEG and functional MRI simultaneously. The IEDs onset time detected with EEG were set as the time parameters in an event- related paradigm of functional MRI analysis. The spatial and temporal characters of IEDs activation were analyzed in detail. In order to confirm the consistency of this method, all patients were scanned repeatedly and the results were correlated with clinical evaluation. Results: Of the 12 patients, valid data from EEG- fMRI were obtained from 10 patients in a total of 18 sessions. Compared with the structural foci, the epileptic foci localization results of eleven sessions were good, five sessions were fairly good, and two sessions were poor. The results obtained from six patients in two separate sessions were concordant, respectively. Moreover, thalamic activation was detected in ten sessions, cerebellar activation was detected in all sessions, and the deactivation was found in the default mode loci in nine sessions. Conclusion: The method of performing EEG and fMRI simultaneously can potentially be a useful tool in epilepsy research. (authors)

112

REMOTE DETECTION OF RADIOACTIVE PLUMES USING MILLIMETER WAVE TECHNOLOGY  

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The reprocessing of spent nuclear fuel, a common method for manufacturing weapons-grade special nuclear materials, is accompanied by the release of fi ssion products trapped within the fuel. One of these fi ssion products is a radioactive isotope of Krypton (Kr-85); a pure ?- emitter with a half-life of 10.72 years. Due to its chemical neutrality and relatively long half life, nearly all of the Kr-85 is released into the surrounding air during reprocessing, resulting in a concentration of Kr-85 near the source that is several orders of magnitude higher than the typical background (atmospheric) concentrations. This high concentration of Kr-85 is accompanied by a proportionately high increase in air ionization due to the release of beta radiation from Kr-85 decay. Millimeter wave (MMW) sensing technology can be used to detect the presence of Kr-85 induced plumes since a high concentration of ions in the air increases the radar cross section due to a combination of atmospheric phenomena. Possible applications for this technology include the remote sensing of reprocessing activities across national borders bolstering global anti-proliferation initiatives. The feasibility of using MMW radar technology to uniquely detect the presence of Kr-85 can be tested using commercial ion generators or sealed radioactive sources in the laboratory. In this paper we describe our work to derive an ion dispersion model that will describe the spatial distribution of ions from Kr-85 and other common lab sources. The types and energies of radiation emitted by isotopes Co-60 and Cs-137 were researched, and these parameters were incorporated into these dispersion models. Our results can be compared with the results of MMW detection experiments in order to quantify the relationship between radar cross section and air ionization as well as to further calibrate the MMW detection equipment.

Barnowski, R.; Chien; H.; Gopalsami, N.

2009-01-01

113

Advances in Electrostatic Dust Detection on Remote Surfaces  

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The inventory of dust in next-step magnetic fusion devices will be regulated for safety reasons, however diagnostics to measure in-vessel dust are still in their infancy. Advances in dust particle detection on remote surfaces are reported. Two grids of interlocking circuit traces with spacing in the range 125 mu m to 25 mu m are biased to 30 V. Impinging dust creates a short circuit and the result current pulse is recorded. The detector response was measured with particles scraped from a carbon fiber composite tile and sorted by size category. The finest 25 mu m grid showed a sensitivity more than an order of magnitude higher than the 125 mu m grid. The response to the finest particle categories (5 ?30 mu m) was two orders of magnitude higher than the largest (125 ?250 mu m) category. Longer duration current pulses were observed from the coarser particles. The results indicate a detection threshold for fine particles below 1 mu g/cm^2.

C. Voinier; C.H. Skinner; A.L. Roquemore

2005-02-09

114

Remote-excitation and remote-detection of single quantum dot using propagating surface plasmons on silver nanowire  

CERN Document Server

Using propagating surface plasmons (SPs) on silver nanowire (NW), we demonstrate that focused laser light at the end of silver nanowire can excite single quantum dot (QD) microns away from the excitation spot. The QD-NW interaction allows the excited QD convert part of its energy into propagating SPs which then can be detected at the remote sites. Simultaneous multi-QDs remote-excitation and detection are also realized. Furthermore, the tight confinement of propagating SPs around the NW surface enables selective excitation of QDs very close in space, which cannot be realized under conventional excitation condition. This remote excitation and detection approach may find applications in optical imaging and sensing of chemical and biological systems.

Li, Qiang; Xu, Hong-Xing

2014-01-01

115

Whole-body MRI in comparison to skeletal scintigraphy for detection of skeletal metastases in patients with solid tumors  

International Nuclear Information System (INIS)

The aim of this study was to compare the diagnostic efficacy of whole-body magnetic resonance imaging (WB-MRI) as a new and rapid examination technique with skeletal scintigraphy for detection of skeletal metastases from solid tumors. In 129 patients with solid malignant tumors, WB-MRI was performed for individual comparison with skeletal scintigraphy. Examinations were performed with the innovative AngioSURF trademark rolling table with integrated phased array surface coil and coronary TIRM sequences for different body regions. The results for WB-MRI and skeletal scintigraphy were concordant in 81% of the cases, whereby both procedures excluded skeletal metastases in 43%. WB-MRI and skeletal scintigraphy demonstrated skeletal metastases in 38% of the cases, whereby WB-MRI provided more comprehensive findings in 45%. In 12% of the cases, skeletal scintigraphy was superior to WB-MRI and in 19% the findings were discordant, whereby WB-MRI detected skeletal metastases in 15 cases which had not been found on skeletal scintigraphy. In nine cases, skeletal scintigraphy was positive when the WB-MRI was negative. In 60% of the cases, WB-MRI evidenced tumor-associated findings. WB-MRI represents a promising new staging technique for detection of skeletal metastases, which is more sensitive in many cases than skeletal scintigraphy in detecting and assessing the extent of skeletal metastases - and tumor-associated findings that are relevant for treatment strategy. (ort are relevant for treatment strategy. (orig.)

116

Magnetic resonance imaging goes postmortem: noninvasive detection and assessment of myocardial infarction by postmortem MRI  

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To investigate the performance of postmortem magnetic resonance imaging (pmMRI) in identification and characterization of lethal myocardial infarction in a non-invasive manner on human corpses. Before forensic autopsy, 20 human forensic corpses were examined on a 1.5-T system for the presence of myocardial infarction. Short axis, transversal and longitudinal long axis images (T1-weighted; T2-weighted; PD-weighted) were acquired in situ. In subsequent autopsy, the section technique was adapted to short axis images. Histological investigations were conducted to confirm autopsy and/or radiological diagnoses. Nineteen myocardial lesions were detected and age staged with pmMRI, of which 13 were histologically confirmed (chronic, subacute and acute). Six lesions interpreted as peracute by pmMRI showed no macroscopic or histological finding. Five of the six peracute lesions correlated well to coronary pathology, and one case displayed a severe hypertrophic alteration. pmMRI reliably demonstrates chronic, subacute and acute myocardial infarction in situ. In peracute cases pmMRI may display ischemic lesions undetectable at autopsy and routine histology. pmMRI has the potential to substantiate autopsy and to counteract the loss of reliable information on causes of death due to the recent disappearance of the clinical autopsy. (orig.)

Jackowski, Christian [University Hospital, University of Linkoeping, Center for Medical Image Science and Visualization, CMIV, Linkoeping (Sweden); Department of Forensic Medicine, Linkoeping (Sweden); University of Zuerich, Institute of Legal Medicine, Zuerich (Switzerland); Warntjes, Marcel J.B.; Persson, Anders [University Hospital, University of Linkoeping, Center for Medical Image Science and Visualization, CMIV, Linkoeping (Sweden); Berge, Johan [Department of Forensic Medicine, Linkoeping (Sweden); Baer, Walter [University of Zuerich, Institute of Legal Medicine, Zuerich (Switzerland)

2011-01-15

117

Magnetic resonance imaging goes postmortem: noninvasive detection and assessment of myocardial infarction by postmortem MRI  

International Nuclear Information System (INIS)

To investigate the performance of postmortem magnetic resonance imaging (pmMRI) in identification and characterization of lethal myocardial infarction in a non-invasive manner on human corpses. Before forensic autopsy, 20 human forensic corpses were examined on a 1.5-T system for the presence of myocardial infarction. Short axis, transversal and longitudinal long axis images (T1-weighted; T2-weighted; PD-weighted) were acquired in situ. In subsequent autopsy, the section technique was adapted to short axis images. Histological investigations were conducted to confirm autopsy and/or radiological diagnoses. Nineteen myocardial lesions were detected and age staged with pmMRI, of which 13 were histologically confirmed (chronic, subacute and acute). Six lesions interpreted as peracute by pmMRI showed no macroscopic or histological finding. Five of the six peracute lesions correlated well to coronary pathology, and one case displayed a severe hypertrophic alteration. pmMRI reliably demonstrates chronic, subacute and acute myocardial infarction in situ. In peracute cases pmMRI may display ischemic lesions undetectable at autopsy and routine histology. pmMRI has the potential to substantiate autopsy and to counteract the loss of reliable information on causes of death due to the recent disappearance of the clinical autopsy. (orig.)

118

The usefulness of MRI for detection of the thymus gland in myasthenia gravis  

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Seven patients with myasthenia gravis (MG) were examined to find thymus or thymoma employing chest radiographs, computed tomography (CT), pneumomediastinography (PMG), computed tomography after pneumomediastinography (PMG-CT) and magnetic resonance imaging (MRI). X-ray CT examination could reveal thymus only in half out of 6 cases scanned. On the other hand, MRI confirmed thymus or thymoma in 6 out of 7 patients. PMG and PMG-CT confirmed thymus or thymoma clearly in all of the 4 cases studied. PMG and PMG-CT examinations revealed thymus or thymoma more clearly than MRI. MRI is, however, an examination causing no pain to the patients and also more superior to X-ray CT in distinguishing between a thymus and mediastinal fat or vascular structure. In addition, MRI could reveal even capsules in thymoma which were never revealed by X-ray CT. We concluded that MRI could be an alternative method to CT and PMG in detection of thymus or thymoma in MG. (author).

Hokezu, Youichi; Kaseda, Syun; Arimura, Kimiyoshi; Osame, Mitsuhiro; Baba, Kuniaki (Kagoshima Univ. (Japan). Faculty of Medicine); Ohkubo, Koichi; Hagiwara, Hiroshi

1989-08-01

119

The usefulness of MRI for detection of the thymus gland in myasthenia gravis  

International Nuclear Information System (INIS)

Seven patients with myasthenia gravis (MG) were examined to find thymus or thymoma employing chest radiographs, computed tomography (CT), pneumomediastinography (PMG), computed tomography after pneumomediastinography (PMG-CT) and magnetic resonance imaging (MRI). X-ray CT examination could reveal thymus only in half out of 6 cases scanned. On the other hand, MRI confirmed thymus or thymoma in 6 out of 7 patients. PMG and PMG-CT confirmed thymus or thymoma clearly in all of the 4 cases studied. PMG and PMG-CT examinations revealed thymus or thymoma more clearly than MRI. MRI is, however, an examination causing no pain to the patients and also more superior to X-ray CT in distinguishing between a thymus and mediastinal fat or vascular structure. In addition, MRI could reveal even capsules in thymoma which were never revealed by X-ray CT. We concluded that MRI could be an alternative method to CT and PMG in detection of thymus or thymoma in MG. (author)

120

Ultra-low-field MRI for the detection of liquid explosives  

International Nuclear Information System (INIS)

Recently it has become both possible and practical to use magnetic resonance (MR) at magnetic fields in the range from ?T to mT, the so-called ultra-low-field (ULF) regime. SQUID (superconducting quantum interference device) sensor technology allows for ultra-sensitive detection while pulsed pre-polarizing fields greatly enhance the signal. The instrumentation allows for unprecedented flexibility in signal acquisition sequences and simplified MRI instrumentation. Here we present results for a new application of ULF MRI and relaxometry for the detection and characterization of liquids. We briefly describe the motivation and advantages of the ULF MR approach, and present recent results from a seven-channel ULF MRI/relaxometer system constructed to non-invasively inspect liquids at a security checkpoint for the presence of hazardous material. The instrument was deployed at the Albuquerque International Airport in December 2008, and results from that endeavor are also presented.

 
 
 
 
121

Detection and Demarcation of Tumor using Vector Quantization in MRI images  

CERN Document Server

Segmenting a MRI images into homogeneous texture regions representing disparate tissue types is often a useful preprocessing step in the computer-assisted detection of breast cancer. That is why we proposed new algorithm to detect cancer in mammogram breast cancer images. In this paper we proposed segmentation using vector quantization technique. Here we used Linde Buzo-Gray algorithm (LBG) for segmentation of MRI images. Initially a codebook of size 128 was generated for MRI images. These code vectors were further clustered in 8 clusters using same LBG algorithm. These 8 images were displayed as a result. This approach does not leads to over segmentation or under segmentation. For the comparison purpose we displayed results of watershed segmentation and Entropy using Gray Level Co-occurrence Matrix along with this method.

Kekre, H B; Gharge, Saylee M

2010-01-01

122

Detection and Demarcation of Tumor using Vector Quantization in MRI images  

Directory of Open Access Journals (Sweden)

Full Text Available Segmenting a MRI images into homogeneous texture regions representing disparate tissue types is often a useful preprocessing step in the computer-assisted detection of breast cancer. That is why we proposednew algorithm to detect cancer in mammogram breast cancer images. In this paper we proposed segmentation using vector quantization technique. Here we used Linde Buzo-Gray algorithm (LBG for segmentation of MRI images. Initially a codebook of size 128 was generated for MRI images. These code vectors were further clustered in 8 clusters using same LBG algorithm. These 8 images were displayed as a result. This approach does not leads to over segmentation or under segmentation. For the comparison purpose we displayed results ofwatershed segmentation and Entropy using Gray Level Co-occurrence Matrix along with this method.

Dr. H. B. Kekre,

2009-11-01

123

SQUID-Detected Microtesla MRI in the presence of Metal  

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In magnetic resonance imaging (MRI) performed at fields of 1 T and above, the presence of a metal insert can distort the image because of susceptibility differences within the sample and modification of the radiofrequency fields by screening currents. Furthermore, it is not feasible to perform nuclear magnetic resonance (NMR) spectroscopy or acquire a magnetic resonance image if the sample is enclosed in a metal container. Both problems can be overcome by substantially lowering the NMR frequency. Using a microtesla imaging system operating at 2.8 kHz, with a superconducting quantum interference device (SQUID) as the signal detector, we have obtained distortion-free images of a phantom containing a titanium bar and three-dimensional images of an object enclosed in an aluminum can; in both cases high-field images are inaccessible.

Moessle, Michael; Han, Song-I.; Myers, Whittier; Lee, Seung-Kyun; Kelso, Nathan; Hatridge, Michael; Pines, Alexander; Clarke, John

2006-09-06

124

SQUID-Detected Microtesla MRI in the presence of Metal  

International Nuclear Information System (INIS)

In magnetic resonance imaging (MRI) performed at fields of 1 T and above, the presence of a metal insert can distort the image because of susceptibility differences within the sample and modification of the radiofrequency fields by screening currents. Furthermore, it is not feasible to perform nuclear magnetic resonance (NMR) spectroscopy or acquire a magnetic resonance image if the sample is enclosed in a metal container. Both problems can be overcome by substantially lowering the NMR frequency. Using a microtesla imaging system operating at 2.8 kHz, with a superconducting quantum interference device (SQUID) as the signal detector, we have obtained distortion-free images of a phantom containing a titanium bar and three-dimensional images of an object enclosed in an aluminum can; in both cases high-field images are inaccessible

125

Utility of vaginal and rectal contrast medium in MRI for the detection of deep pelvic endometriosis  

International Nuclear Information System (INIS)

To study the sensitivity of MRI performed utilising vaginal and rectal opacification with ultrasound gel in the detection of deep pelvic endometriosis. This was a prospective monocentric study. All patients evaluated by the gynaecologist for pelvic pain, endometriosis or infertility were included. Axial and sagittal T2-weighted images were performed both with and without vaginal and rectal opacification with ultrasound gel. Three radiologists, all blinded, interpreted the images with a minimum of 15 days between the two readings. MRI performance with and without vaginal and rectal opacification was evaluated by calculating sensitivity, specificity and both positive and negative predictive values. Seventy-eight patients were included. Among these, 31 patients had deep pelvic endometriosis of which 24 were confirmed by laparoscopy. Seventy-six locations of deep pelvic endometriosis were discovered on MRI. For the three reviewers there was a significant improvement in sensitivity between pre- and post-contrast MRI (p < 0.0002). Opacification of the vagina and rectum significantly improved the sensitivity of MRI for the detection of deep pelvic endometriosis by expanding the vagina and rectum, thus allowing better delineation of the pelvic organs. This was especially apparent for lesions localised to the vagina and rectovaginal septum. (orig.)

126

Involvement patterns in myotilinopathy and desminopathy detected by a novel neuromuscular whole-body MRI protocol  

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Whole-body MRI (WB-MRI) has been successfully applied for oncologic and cardiovascular diagnostics, whereas imaging in myopathies usually employs dedicated protocols restricted to areas of specific interest. In this study, we propose a comprehensive neuromuscular WB-MRI protocol. Eighteen patients with degenerative and inflammatory muscle diseases were included. Whole-body imaging was performed on a 1.5-T MR system using parallel imaging. Examination time was 41:26 min. Coronal and axial T1-weighted and coronal short tau inversion recovery (STIR) sequences of the whole body were acquired. Images were analysed by two radiologists. With this protocol we could detect characteristic involvement patterns in different myofibrillar myopathies (MFMs): Patients with myotilinopathy showed frequent involvement of the rhomboid muscles (4/5), the erector spinae (5/5), the biceps femoris and the semimembranosus (5/5), while the semitendinosus was relatively spared (2/5). In contrast, in desminopathy patients the ilipsoas (3/4), the sartorius, (3/4), the gracilis (3/4) and the semitendinosus (3/4) were frequently involved, while the semimembranosus was spared (1/4). As shown for MFMs, WB-MRI is an appropriate modality to detect fatty infiltration and oedema in skeletal muscles. WB-MRI could be more useful than dedicated examinations for differential diagnosis, muscle biopsy planning and noninvasive follow-up examinations. (orig.)

Schramm, Nicolai; Born, Christine; Weckbach, Sabine; Reiser, Maximilian F. [Ludwig-Maximilians-University, Institute for Clinical Radiology, Munich (Germany); Reilich, Peter; Walter, Maggie C. [Ludwig-Maximilians-University, Friedrich-Baur-Institute, Department of Neurology, Munich (Germany)

2008-12-15

127

MRI for the detection of ureteral opening and ipsilateral kidney in children with single ectopic ureter  

International Nuclear Information System (INIS)

To assess the usefulness of MRI in the detection of a single ectopic ureteral opening and the location and dysplastic change of ipsilateral kidney. Nine patients (mean age; 4.8 years, M:F=3:6) in whom a single ectopic ureter was suspected clinically and sonographically underwent conventional radiologic studies (IVP, VCUG, 99mTc-DM-SA scan, as well as US) and MRI. We evaluated images of the point of the ectopic ureteral opening and the location and dysplastic or hydronephrotic change of the ipsilateral kidney, and compared those findings with the endoscopic, surgical, and pathological findings. Eight patients had a unilateral single ectopic ureter and one had bilateral lesions. Seven normally positioned kidneys in six patients showed dysplastic (n=3) or hydronephrotic (n=4) change. In two patients an ectopic dysplastic kidney was located in the pelvis and one had ipsilateral renal agenesis. Conventional radiologic studies failed to reveal two ectopic dysplastic kidneys, one renal agenesis, and eight ectopic ureteral openings. In all patients, MRI clearly demonstrated the location of the kidney and ectopic ureteral opening, and dysplastic or hydronephrotic change of the kidney, and in one patient, uterine duplication. Except in two patients whose ectopic ureteral opening was not found on endoscopy, MRI findings were concordant with endoscopic and surgical findings. MRI was useful for the detection of a single ectopic ureteral opening and for demonstrating the location aening and for demonstrating the location and dysplastic change of ipsilateral kidney

128

MRI for the detection of ureteral opening and ipsilateral kidney in children with single ectopic ureter  

Energy Technology Data Exchange (ETDEWEB)

To assess the usefulness of MRI in the detection of a single ectopic ureteral opening and the location and dysplastic change of ipsilateral kidney. Nine patients (mean age; 4.8 years, M:F=3:6) in whom a single ectopic ureter was suspected clinically and sonographically underwent conventional radiologic studies (IVP, VCUG, 99mTc-DM-SA scan, as well as US) and MRI. We evaluated images of the point of the ectopic ureteral opening and the location and dysplastic or hydronephrotic change of the ipsilateral kidney, and compared those findings with the endoscopic, surgical, and pathological findings. Eight patients had a unilateral single ectopic ureter and one had bilateral lesions. Seven normally positioned kidneys in six patients showed dysplastic (n=3) or hydronephrotic (n=4) change. In two patients an ectopic dysplastic kidney was located in the pelvis and one had ipsilateral renal agenesis. Conventional radiologic studies failed to reveal two ectopic dysplastic kidneys, one renal agenesis, and eight ectopic ureteral openings. In all patients, MRI clearly demonstrated the location of the kidney and ectopic ureteral opening, and dysplastic or hydronephrotic change of the kidney, and in one patient, uterine duplication. Except in two patients whose ectopic ureteral opening was not found on endoscopy, MRI findings were concordant with endoscopic and surgical findings. MRI was useful for the detection of a single ectopic ureteral opening and for demonstrating the location and dysplastic change of ipsilateral kidney.

Kim, Myung Joon; Lim, Joon Seok; Yoon, Choon Sik; Han, Sang Won [Yonsei Univ. College of Medicine, Seoul (Korea, Republic of)

1999-06-01

129

MRI  

Medline Plus

Full Text Available ... will hear loud noises. The combination of the magnetic field and different radio frequencies allow a specialized computer to generate excellent pictures of the inside of the body. ... Summary A magnetic resonance imaging scan can be helpful in detecting ...

130

Detection of bone metastasis of prostate cancer. Comparison of whole-body MRI and bone scintigraphy  

International Nuclear Information System (INIS)

Purpose: prostate cancer continues to be the third leading cancer-related mortality of western men. Early diagnosis of bone metastasis is important for the therapy regime and for assessing the prognosis. The standard method is bone scintigraphy. Whole-body MRI proved to be more sensitive for early detection of skeletal metastasis. However, studies of homogenous tumor entities are not available. The aim of the study was to compare bone scintigraphy and whole-body MRI regarding the detection of bone metastasis of prostate cancer. Materials and methods: 14 patients with histologically confirmed prostate cancer and a bone scintigraphy as well as whole-body MRI within one month were included. The mean age was 68 years. Scintigraphy was performed using the planar whole-body technique (ventral and dorsal projections). Suspect areas were enlarged. Whole-body MRI was conducted using native T1w and STIR sequences in the coronary plane of the whole body, sagittal imaging of spine and breath-hold STIR and T1w-Flash-2D sequences of ribs and chest. Bone scintigraphy and whole-body MRI were evaluated retrospectively by experienced radiologists in a consensus reading on a lesion-based level. Results: whole-body MRI detected significantly more bone metastasis (p = 0.024). 96.4% of the demonstrated skeletal metastases in bone scintigraphy were founded in whole-body MRI while only 58.6% of the depicted metastases in MRI were able to be located in scintigraphy. There was no significant difference regarding bone metastasis greater than one centimeter (p = 0.082) in contrast to metastasis less than one centimeter (p = 0.035). Small osteoblastic metastases showed a considerably higher contrast in T1w sequences than in STIR imaging. Further advantages of whole-body MRI were additional information about extra-osseous tumor infiltration and their complications, for example stenosis of spinal canal or vertebral body fractures, found in 42.9% of patients. (orig.)

131

Screening applications for MRI in the detection of upper abdominal disease: comparative study of non-contrast-enhanced single-shot MRI and contrast-enhanced helical CT  

Energy Technology Data Exchange (ETDEWEB)

Purpose: To compare the value of `push-button` singe-shot non-contrast-enhanced MRI and contrast-enhanced helical CT for detection of upper abdominal disease. Methods: In 120 patients, images obtained with non contrast-enhanced single-shot MRI (T2: double echo HASTE, and T1: turbo FLASH) and contrast-enhanced helical CT were compared. Lesions or abnormalities were divided in 8 anatomical categories (1: liver; 2: pancreatobiliary; 3: kidney/adrenal gland; 4: retroperitoneum; 5: vascular; 6: spleen; 7: gastrointestinal tract and peritoneum; 8: base of thorax) and classified as follows: 2: seen at MRI only; 1: better seen at MRI; 0: no difference; -1: better seen at CT; -2: seen at CT only. Also recorded were the `door-to-door` examination times. Results: Of a total of 629 abnormalities, 594 were detected at MRI (94 %) and 536 at CT (85 %). CT offered better results in two categories only: retroperitoneum (mean score: -0.68) and vascular (mean score -0.87). Mean examination times were 19 min for CT and 14.8 min for MRI. Conclusion: Unenhanced single-shot MRI is a valuable first step of a comprehensive upper abdominal MR exam and may even be the final step in many patients. (orig.) With 4 figs., 1 tab., 21 refs.

Jaegere, T. de; Hoe, L. van; Steenbergen, W. van; Cutsem, E. van; Bosmans, H.; Heindryckx, E.; Loubeyre, P.; Marchal, G. [Department of Radiology, Leuven (Belgium)

1999-06-01

132

INFARCT DETECTION IN BRAIN MRI USING IMPROVED SEGMENTATION ALGORITHM AND VOLUME VISUALIZATION?  

Directory of Open Access Journals (Sweden)

Full Text Available In the present days, for the human body anatomical study and for the treatment planning medicalscience very much depend on the medical imaging technology and medical images. Specifically for thehuman brain, MRI widely prefers and using for the imaging. But by nature medical images are complex andnoisy.This leads to the necessity of processes that reduces difficulties in analysis and improves quality ofoutput.This paper discuss about an improved segmentation algorithm for infarct detection in brain MRI andhave compared the performance of this method with conventional method. This Proposed algorithm offersthe advantages of producing good quality segmentation and also easily visualizes the segmented region in 3Dimensional views.

Praveen Kumar E

2013-10-01

133

Brain mapping and detection of functional patterns in fMRI using wavelet transform; application in detection of dyslexia  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Functional Magnetic Resonance Imaging (fMRI has been proven to be useful for studying brain functions. However, due to the existence of noise and distortion, mapping between the fMRI signal and the actual neural activity is difficult. Because of the difficulty, differential pattern analysis of fMRI brain images for healthy and diseased cases is regarded as an important research topic. From fMRI scans, increased blood ows can be identified as activated brain regions. Also, based on the multi-sliced images of the volume data, fMRI provides the functional information for detecting and analyzing different parts of the brain. Methods In this paper, the capability of a hierarchical method that performed an optimization algorithm based on modified maximum model (MCM in our previous study is evaluated. The optimization algorithm is designed by adopting modified maximum correlation model (MCM to detect active regions that contain significant responses. Specifically, in the study, the optimization algorithm is examined based on two groups of datasets, dyslexia and healthy subjects to verify the ability of the algorithm that enhances the quality of signal activities in the interested regions of the brain. After verifying the algorithm, discrete wavelet transform (DWT is applied to identify the difference between healthy and dyslexia subjects. Results We successfully showed that our optimization algorithm improves the fMRI signal activity for both healthy and dyslexia subjects. In addition, we found that DWT based features can identify the difference between healthy and dyslexia subjects. Conclusion The results of this study provide insights of associations of functional abnormalities in dyslexic subjects that may be helpful for neurobiological identification from healthy subject.

Najarian Kayvan

2009-11-01

134

The role of ultrasound-guided vacuum-assisted biopsy in the management of MRI-detected lesions  

International Nuclear Information System (INIS)

We evaluated the accuracy of ultrasound-guided vacuum-assisted breast biopsy (US-VAB) for lesions detected by MRI only (MRI-detected lesions). We performed US-VAB for 493 patients with 516 lesions between January 2003 and March 2005 in our hospital. There were 159 nonpalpable, MRI-detected lesions. Second look US was performed for all lesions, and US-VAB was considered successful'' if the lesion had disappeared on postinterventional MRI. One hundred forty-four of 159 procedures (91%) were considered successful. Histological examination demonstrated 13 (9%) malignant, 1 (0.7%) atypical ductal hyperplasia, and 130 (90%) benign lesions. In 15 of 159 procedures, US-VAB was considered unsuccessful. In these patients, rebiopsy was not recommended because of a constant appearance over a 22-month follow-up period. US-VAB is sufficiently accurate for obtaining histologic proof of MRI-detected lesions. (author)

135

Intrinsically radiolabelled [59Fe]-SPIONs for dual MRI/radionuclide detection  

Science.gov (United States)

Towards the development of iron oxide nanoparticles with intrinsically incorporated radionuclides for dual Positron Emission Tomography/Magnetic Resonance Imaging (PET/MRI) and more recently of Single Photon Emission Computed Tomography/Magnetic Resonance Imaging (SPECT/MRI), we have developed intrinsically radiolabeled [59Fe]-superparamagnetic iron oxide nanoparticles ([59Fe]-SPIONs) as a proof of concept for an intrinsic dual probe strategy. 59Fe was incorporated into Fe3O4 nanoparticle crystal lattice with 92±3% efficiency in thermal decomposition synthesis. Multidentate poly(acrylic acid)-dopamine-poly(ethylene-glycol-2000) (PAA-DOP-PEG) ligands were designed and synthesized based on facile EDC chemistry and utilized to functionalize the [59Fe]-SPIONs. The transverse relaxivity of [59Fe]-SPIONs (97±3 s-1mM-1) was characterized and found to be similar to non-radioactive SPIONs (72±10 s-1mM-1), indicating that 59Fe incorporation does not alter the SPIONs’ MRI contrast properties. [59Fe]-SPIONs were used to evaluate the nanoparticle biodistribution by ex vivo gamma counting and MRI. Nude mice (n=15) were injected with [59Fe]-SPIONs and imaged at various time points with 7T small animal MRI scanner. Ex vivo biodistribution was evaluated by tissue-based gamma counting. MRI signal contrast qualitatively correlates with the %ID/g of [59Fe]-SPIONs, with high contrast in liver (45±6%), medium contrast in kidneys (21±5%), and low contrast in brain (4±6%) at 24 hours. This work demonstrates the synthesis and in vivo application of intrinsically radiolabeled [59Fe]-SPIONs for bimodal detection and provides a proof of concept for incorporation of both gamma- and positron-emitting inorganic radionuclides into the core of metal based MRI contrast agent nanoparticles. PMID:25250204

Hoffman, David; Sun, Minghao; Yang, Likun; McDonagh, Philip R; Corwin, Frank; Sundaresan, Gobalakrishnan; Wang, Li; Vijayaragavan, Vimalan; Thadigiri, Celina; Lamichhane, Narottam; Zweit, Jamal

2014-01-01

136

Evaluation of the potential of PET-MRI fusion for detection of liver metastases in patients with neuroendocrine tumours  

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This study was performed to assess the role of retrospective PET-MRI fusion with Ga-68-DOTA(0)-Phe(1)-Tyr(3)-octreotide (Ga-68-DOTATOC) PET and Gd-EOB-DTPA MRI in the detection of hepatic metastases from neuroendocrine tumours (NET). Twenty-two consecutive patients with suspected liver metastases from histopathologically proven NET were examined with Gd-EOB-DTPA MRI and multiphase contrast-enhanced Ga-68-DOTATOC PET/CT. PET and MRI images were retrospectively fused using commercially available software. Two physicians experienced in nuclear medicine and radiology analysed the images to assess diagnostic confidence and characterise liver lesions. A total of 181 lesions were detected. PET-MRI showed a sensitivity of 91.2% (significantly superior to PET/CT; P < 0.05) and a specificity of 95.6% (significantly superior to MRI; P < 0.05). PET/CT had a sensitivity of 73.5% and a specificity of 88.2%. MRI had a sensitivity of 87.6% and a specificity of 86.8%. The area under the curve was 0.98 for PET-MRI, 0.96 for MRI, and 0.89 for PET/CT (P < 0.05). Retrospectively fused PET-MRI was superior to multiphase contrast-enhanced Ga-68-DOTATOC PET/CT and Gd-EOB-DTPA MRI in the detection of NET liver metastases. It was more sensitive than PET/CT and more specific than MRI. Fused PET-MRI therefore seems well suited for surgical and interventional treatment planning of NET liver metastases. (orig.)

Schreiter, Nils F.; Steffen, Ingo; Brenner, Winfried; Roettgen, Rainer [Charite, Department of Nuclear Medicine, Berlin (Germany); Nogami, Munenobu [Kochi University, Department of Nuclear Medicine, Kochi (Japan); Pape, Ulrich-Frank [Charite, Department of Gastroenterology, Berlin (Germany); Hamm, Bernd [Charite, Department of Radiology, Berlin (Germany)

2012-02-15

137

Hyperspectral remote sensing techniques for early detection of plant diseases  

Science.gov (United States)

Hyperspectral remote sensing is an emerging, multidisciplinary field with diverse applications in Earth observation. Nowadays spectral remote sensing techniques allow presymptomatic monitoring of changes in the physiological state of plants with high spectral resolution. Hyperspectral leaf reflectance and chlorophyll fluorescence proved to be highly suitable for identification of growth anomalies of cultural plants that result from the environmental changes and different stress factors. Hyperspectral technologies can find place in many scientific areas, as well as for monitoring of plants status and functioning to help in making timely management decisions. This research aimed to detect a presence of viral infection in young pepper plants (Capsicum annuum L.) caused by Cucumber Mosaic Virus (CMV) by using hyperspectral reflectance and fluorescence data and to assess the effect of some growth regulators on the development of the disease. In Bulgaria CMV is one of the widest spread pathogens, causing the biggest economical losses in crop vegetable production. Leaf spectral reflectance and fluorescence data were collected by a portable fibre-optics spectrometer in the spectral ranges 450÷850 nm and 600-900 nm. Greenhouse experiment with pepper plants of two cultivars, Sivria (sensitive to CMV) and Ostrion (resistant to CMV) were used. The plants were divided into six groups. The first group consisted of healthy (control) plants. At growth stage 4-6 expanded leaf, the second group was inoculated with CMV. The other four groups were treated with growth regulators: Spermine, MEIA (beta-monomethyl ester of itaconic acid), ??? (benzo(1,2,3)thiadiazole-7-carbothioic acid-S-methyl ester) and Phytoxin. On the next day, the pepper plants of these four groups were inoculated with CMV. The viral concentrations in the plants were determined by the serological method DAS-ELISA. Statistical, first derivative and cluster analysis were applied and several vegetation indices were calculated for assessment the differences between the spectral data of healthy and injured (stressed) plants of two cultivars. The averaged reflectance spectra for all groups were analyzed in the most informative for green plants spectral ranges: green, red, red edge, and near infrared. Fluorescence spectra were analyzed at five characteristic wavelengths located at the maximums of the emitted radiation and at the forefronts and rear slopes. On the 7th day no visual changes in the leaves occurred but a decrease of spectral reflectance was established in the green and red ranges for all cases of two cultivars. On the 14th day an increase of the number of statistically significant differences between spectral reflectance of healthy and treated plants was observed. A shift of the red edge position to the blue region was observed for the case of treatment only with CMV. The growth regulator MEIA is with the best preventing action on the leaves. The correlation of the results from spectral analyses and the DAS-ELISA findings for presence of CMV demonstrates the efficiency and sensitivity of these remote sensing techniques for reliable diagnosis of viral infection and injuries of the plants.

Krezhova, Dora; Maneva, Svetla; Zdravev, Tomas

138

Comparison between SPECT and MRI in detecting skull-base invasion in nasopharyngeal carcinoma  

International Nuclear Information System (INIS)

Objective: To investigate the ability of single photon emission computed tomography (SPECT) and MRI in detecting skull-base invasion in nasopharyngeal carcinoma. Methods: Sixty-one patients with nasopharyngeal carcinoma received whole body and skull-base tomography SPECT, and nasopharynx and skull-base MRI before radiotherapy. The results were double-blind compared and evaluated. Results: The overall positive rates of skull-base invasion detected by SPECT and MRI were 51% and 46% (P =0.508). In patients with headache, cranial nerve palsy or both, the rates were 83% and 86% (P= 1.000), 80% and 80% (P=1.000), 88% and 94% (P=1.000 ), respectively. In patients with T1 + T2 and T3 + T4 lesions, the rates were 22% and 0 (P=0.031), 74% and 82% (P=0.250), respectively. In patients with N0 + N1 and N2 + N3 lesions, they were 50% and 48% (P=1.000), 53% and 40% (P= 0.500), respectively. The conformation rate between SPECT and MRI was 85%. Binary Logistic regression analysis showed that T stage was a risk factor for positive SPECT(?2=4.23, P=0.040, OR=3.04). Head- ache tended to be a risk factor for both positive SPECT and positive MRI(?2=3.13, P=0.077, OR=4.54; ?2=3.64, P=0.056, OR=12.00). Conclusions: The detection sensitivity of SPECT in skull-base invasion in nasopharyngeal carcinoma is equivalent to that of MRI. The consistency between SPECT and MRI is good. Moreover, there is a good correlation between SPECT and symptoms, signs and stage. SPECT of skull-base tomography is necessary for patients with severe headache, negative CT and those who can not receive MRI. When SPECT result is positive,skull-base should be considered to be invaded and should be defined as gross tumor volume in radiotherapy planning. (authors)

139

Further studies on the remote detection of submerged Orimulsion with a range-gated laser fluorosensor  

Energy Technology Data Exchange (ETDEWEB)

A study was conducted to evaluate the capabilities of range-gated laser fluorosensors for the remote, subsurface detection of heavy oils and other products such as Orimulsion. The series of studies initiated by Environment Canada and the Canadian Coast Guard are continuing. They were designed to develop technologies capable of real-time remote detection of neutrally buoyant and/or submerged fuels in the marine environment. In this paper, the authors presented the results of the second phase of the study into the remote detection of submerged Orimulsion with a range-gated fluorosensor. 13 refs., 1 tab., 5 figs.

Brown, C.E.; Marois, R.; Gamble, R.L.; Fingas, M.F. [Environment Canada, Ottawa, ON (Canada). Emergencies Science Div

2003-07-01

140

Multiparametric MRI of the prostate. Method for early detection of prostate cancer?  

International Nuclear Information System (INIS)

Current approaches for the early detection of prostate cancer are controversially discussed because the disease is characterized by a high incidence rate with a relatively low morbidity rate, availability of only limited prognostic markers, and continued therapy-related morbidity. Conventional morphological MRI does not play a role in early detection since small tumor foci cannot be delineated. However, if there is clinical suspicion for prostate cancer, multiparametric MRI is currently the most accurate method for detecting and characterizing suspicious lesions in the prostate. The potential to identify the so-called 'index lesion', i.e., the tumor area that is most aggressive and determines treatment, is particularly important. This information can increase the accuracy of prostate biopsy and serve as a biomarker for follow-up during active surveillance. The method may considerably contribute to the urgently required separation of clinically significant from clinically insignificant prostate cancers. (orig.)

 
 
 
 
141

Development of contaminant detection system based on ultra-low field SQUID-NMR/MRI  

Science.gov (United States)

We have developed an ultra-low field (ULF) NMR/MRI system using an HTS-rf-SQUID and evaluated performance of the system as a contaminant detection system for foods and drinks. In this work, we measured 1D MRIs from water samples with or without various contaminants, such as aluminum and glass balls using the system. In the 1D MRIs, changes of the MRI spectra were detected, corresponding to positions of the contaminants. We measured 2D MRIs from food samples with and without a hole. In the 2D MRIs, the hole position in the sample was well visualized. These results show that the feasibility of the system to detect and localize contaminants in foods and drinks.

Tsunaki, S.; Yamamoto, M.; Hatta, J.; Hatsukade, Y.; Tanaka, S.

2014-05-01

142

Higher lesion conspicuity for SENSE dynamic MRI in detecting hypervascular hepatocellular carcinoma: analysis through the measurements of liver SNR and lesion-liver CNR comparison with conventional dynamic MRI.  

Science.gov (United States)

The aim of our study was to compare the signal-to-noise ratio (SNR) of liver parenchyma and the contrast-to-noise ratio (CNR) of hypervascular hepatocellular carcinoma (HCC) between conventional and SENSE dynamic MRI. Thirty-one consecutive patients who were strongly suspected of having HCC were enrolled in our study. The subjects consisted of 20 men and 11 women aged 52 years to 79 years (mean 66.8 years). Dynamic MRI was performed for each patient, with SENSE (SENSE MRI) and without SENSE (conventional MRI) on separate days. For the quantitative analysis, the liver SNR and the lesion-liver CNR of 25 hypervascular HCCs detected on both conventional and SENSE dynamic MRI were measured. The liver SNR of the arterial phase and the portal venous phase was 84.1+/-24.7 and 104.7+/-34.3, respectively, in conventional MRI, while it was 62.9+/-19.5 and 44.5+/-18.2, respectively, in SENSE MRI. SENSE MRI showed a statistically significantly lower SNR than conventional MRI (P<0.01). The lesion-liver CNR was 26.3+/-15.9 in conventional MRI and 39.0+/-19.6 in SENSE MRI. The lesion-liver CNR in SENSE MRI was significantly higher than in conventional MRI (P<0.01). The SNR in SENSE MRI is significantly lower than in conventional MRI, although the lesion CNR is significantly higher than in conventional MRI. PMID:16041592

Tanaka, Osamu; Ito, Hirotoshi; Yamada, Kei; Kubota, Takao; Kizu, Osamu; Kato, Takeharu; Yamagami, Takuji; Nishimura, Tsunehiko

2005-12-01

143

Higher lesion conspicuity for SENSE dynamic MRI in detecting hypervascular hepatocellular carcinoma: analysis through the measurements of liver SNR and lesion-liver CNR comparison with conventional dynamic MRI  

Energy Technology Data Exchange (ETDEWEB)

The aim of our study was to compare the signal-to-noise ratio (SNR) of liver parenchyma and the contrast-to-noise ratio (CNR) of hypervascular hepatocellular carcinoma (HCC) between conventional and SENSE dynamic MRI. Thirty-one consecutive patients who were strongly suspected of having HCC were enrolled in our study. The subjects consisted of 20 men and 11 women aged 52 years to 79 years (mean 66.8 years). Dynamic MRI was performed for each patient, with SENSE (SENSE MRI) and without SENSE (conventional MRI) on separate days. For the quantitative analysis, the liver SNR and the lesion-liver CNR of 25 hypervascular HCCs detected on both conventional and SENSE dynamic MRI were measured. The liver SNR of the arterial phase and the portal venous phase was 84.1{+-}24.7 and 104.7{+-}34.3, respectively, in conventional MRI, while it was 62.9{+-}19.5 and 44.5{+-}18.2, respectively, in SENSE MRI. SENSE MRI showed a statistically significantly lower SNR than conventional MRI (P<0.01). The lesion-liver CNR was 26.3{+-}15.9 in conventional MRI and 39.0{+-}19.6 in SENSE MRI. The lesion-liver CNR in SENSE MRI was significantly higher than in conventional MRI (P<0.01). The SNR in SENSE MRI is significantly lower than in conventional MRI, although the lesion CNR is significantly higher than in conventional MRI. (orig.)

Tanaka, Osamu; Ito, Hirotoshi; Yamada, Kei; Kubota, Takao; Kizu, Osamu; Kato, Takeharu; Yamagami, Takuji; Nishimura, Tsunehiko [Kyoto Prefectural University of Medicine, Department of Radiology (Japan)

2005-12-01

144

Can MRI replace DMSA in the detection of renal parenchymal defects in children with urinary tract infections?  

Energy Technology Data Exchange (ETDEWEB)

Renal parenchymal defects may be a consequence of urinary tract infections (UTI) in childhood. MRI is a non-radiation imaging modality compared with DMSA scanning. To compare DMSA with MRI for the detection of renal parenchymal defects in children presenting for radiological investigation after a first UTI. Both DMSA and MRI were performed at the same appointment in 37 children (aged 4 months-13 years; mean 4.5 years) with a history of UTI. Both planar and SPECT DMSA were performed. MRI of the kidneys employed axial and coronal T1-, T2- and fat-saturated T1-weighted (T1-W) sequences. Some children had imaging after IV contrast medium. The coronal fat-saturated T1-W sequence was the best sequence and it detected all the findings on MRI. MRI had a sensitivity of 77% and a specificity of 87% for the detection of a scarred kidney using DMSA as the gold standard. MRI diagnosed pyelonephritis in two children that had been interpreted as scarring on DMSA. Renal MRI using a single, coronal, fat-saturated T1-W sequence is a rapid, accurate and minimally invasive technique for the detection of renal scarring that does not employ ionizing radiation. (orig.)

Kavanagh, Eoin C.; Ryan, Stephanie; McCourbrey, Siobhan; O' Connor, Rachel; Donoghue, Veronica [Children' s University Hospital, Department of Radiology, Dublin (Ireland); Awan, Atif [Children' s University Hospital, Department of Paediatrics, Dublin (Ireland)

2005-03-01

145

Can MRI replace DMSA in the detection of renal parenchymal defects in children with urinary tract infections?  

International Nuclear Information System (INIS)

Renal parenchymal defects may be a consequence of urinary tract infections (UTI) in childhood. MRI is a non-radiation imaging modality compared with DMSA scanning. To compare DMSA with MRI for the detection of renal parenchymal defects in children presenting for radiological investigation after a first UTI. Both DMSA and MRI were performed at the same appointment in 37 children (aged 4 months-13 years; mean 4.5 years) with a history of UTI. Both planar and SPECT DMSA were performed. MRI of the kidneys employed axial and coronal T1-, T2- and fat-saturated T1-weighted (T1-W) sequences. Some children had imaging after IV contrast medium. The coronal fat-saturated T1-W sequence was the best sequence and it detected all the findings on MRI. MRI had a sensitivity of 77% and a specificity of 87% for the detection of a scarred kidney using DMSA as the gold standard. MRI diagnosed pyelonephritis in two children that had been interpreted as scarring on DMSA. Renal MRI using a single, coronal, fat-saturated T1-W sequence is a rapid, accurate and minimally invasive technique for the detection of renal scarring that does not employ ionizing radiation. (orig.)

146

Remote sensing detection model of damaged forest by tomicus piniperda in Yunnan Province, China  

Science.gov (United States)

Remote sensing detection model of damaged forest by tomicus piniperda was studied. It analyzed different detection models using multiple types of remote sensing data, such as TM, CBERS-1, AVHRR and MODIS data. The spectral features of the above remote sensing data (March, 2001) were given. And two detection models were put forward according to the spectral changing characteristics. One was named Difference Rate (DR) model with NIR and VIR data, which applied for TM, CBERS-1, AVHRR and MODIS. If DR was bigger, the forest grew healthier. Based on the typical sample, the different guidelines distinguished healthy and damaged forests were obtained. The other model was named Disaster Index (DI) model with thermal and NIR data, only suitable for MODIS. The guidelines of healthy and damaged forest were determined too. Greater DI was, the forest was stricken more badly. In conclusion, it will help monitor and assess the vermin occurrence and impact by remote sensing detection model.

Dong, Xieqiong; Zhao, Shuhe; Luo, Weijia; Feng, Xuezhi; Yang, Xiaopeng; Liu, Hongping; Xu, Hong

2006-01-01

147

Dynamic contrast-enhanced MRI improves accuracy for detecting focal splenic involvement in children and adolescents with Hodgkin disease  

International Nuclear Information System (INIS)

Accurate assessment of splenic disease is important for staging Hodgkin lymphoma. The purpose of this study was to assess T2-weighted imaging with and without dynamic contrast-enhanced (DCE) MRI for evaluation of splenic Hodgkin disease. Thirty-one children with Hodgkin lymphoma underwent whole-body T2-weighted MRI with supplementary DCE splenic imaging, and whole-body PET-CT before and following chemotherapy. Two experienced nuclear medicine physicians derived a PET-CT reference standard for splenic disease, augmented by follow-up imaging. Unaware of the PET-CT, two experienced radiologists independently evaluated MRI exercising a locked sequential read paradigm (T2-weighted then DCE review) and recorded the presence/absence of splenic disease at each stage. Performance of each radiologist was determined prior to and following review of DCE-MRI. Incorrect MRI findings were ascribed to reader (lesion present on MRI but missed by reader) or technical (lesion not present on MRI) error. Seven children had splenic disease. Sensitivity/specificity of both radiologists for the detection of splenic involvement using T2-weighted images alone was 57%/100% and increased to 100%/100% with DCE-MRI. There were three instances of technical error on T2-weighted imaging; all lesions were visible on DCE-MRI. T2-weighted imaging when complemented by DCE-MRI imaging may improve evaluation of Hodgkin disease splenic involvement. (orig.)

148

Dynamic contrast-enhanced MRI improves accuracy for detecting focal splenic involvement in children and adolescents with Hodgkin disease  

Energy Technology Data Exchange (ETDEWEB)

Accurate assessment of splenic disease is important for staging Hodgkin lymphoma. The purpose of this study was to assess T2-weighted imaging with and without dynamic contrast-enhanced (DCE) MRI for evaluation of splenic Hodgkin disease. Thirty-one children with Hodgkin lymphoma underwent whole-body T2-weighted MRI with supplementary DCE splenic imaging, and whole-body PET-CT before and following chemotherapy. Two experienced nuclear medicine physicians derived a PET-CT reference standard for splenic disease, augmented by follow-up imaging. Unaware of the PET-CT, two experienced radiologists independently evaluated MRI exercising a locked sequential read paradigm (T2-weighted then DCE review) and recorded the presence/absence of splenic disease at each stage. Performance of each radiologist was determined prior to and following review of DCE-MRI. Incorrect MRI findings were ascribed to reader (lesion present on MRI but missed by reader) or technical (lesion not present on MRI) error. Seven children had splenic disease. Sensitivity/specificity of both radiologists for the detection of splenic involvement using T2-weighted images alone was 57%/100% and increased to 100%/100% with DCE-MRI. There were three instances of technical error on T2-weighted imaging; all lesions were visible on DCE-MRI. T2-weighted imaging when complemented by DCE-MRI imaging may improve evaluation of Hodgkin disease splenic involvement. (orig.)

Punwani, Shonit; Taylor, Stuart A.; Halligan, Steve [University College London, Centre for Medical Imaging, London (United Kingdom); University College London Hospital, Department of Radiology, London (United Kingdom); Cheung, King Kenneth; Skipper, Nicholas [University College London, Centre for Medical Imaging, London (United Kingdom); Bell, Nichola; Humphries, Paul D. [University College London Hospital, Department of Radiology, London (United Kingdom); Bainbridge, Alan [University College London, Department of Medical Physics and Bioengineering, London (United Kingdom); Groves, Ashley M.; Hain, Sharon F.; Ben-Haim, Simona [University College Hospital, Institute of Nuclear Medicine, London (United Kingdom); Shankar, Ananth; Daw, Stephen [University College London Hospital, Department of Paediatrics, London (United Kingdom)

2013-08-15

149

Detecting brain activation in fMRI using group random walker.  

Science.gov (United States)

Due to the complex noise structure of functional magnetic resonance imaging (fMRI) data, methods that rely on information within a single subject often results in unsatisfactory functional segmentation. We thus propose a new graph-theoretic method, "Group Random Walker" (GRW), that integrates group information in detecting single-subject activation. Specifically, we extend each subject's neighborhood system in such a way that enables the states of both intra- and inter-subject neighbors to be regularized without having to establish a one-to-one voxel correspondence as required in standard fMRI group analysis. Also, the GRW formulation provides an exact, unique closed-form solution for jointly estimating the probabilistic activation maps of all subjects with global optimality guaranteed. Validation is performed on synthetic and real data to demonstrate GRW's superior detection power over standard analysis methods. PMID:20879332

Ng, Bernard; Hamarneh, Ghassan; Abugharbieh, Rafeef

2010-01-01

150

MRI of the Breast for the Detection and Assessment of the Size of Ductal Carcinoma in Situ  

Energy Technology Data Exchange (ETDEWEB)

The aim of the study was to compare the accuracy of magnetic resonance imaging (MRI) and mammography for the detection and assessment of the size of ductal carcinoma in situ (DCIS). The preoperative contrast-enhanced MRI and mammography were analyzed in respect of the detection and assessment of the size of DCIS in 72 patients (age range: 30 67 years, mean age: 47 years). The MRI and mammographic measurements were compared with the histopathologic size with using the Pearson's correlation coefficients and the Mann-Whitney u test. We evaluated whether the breast density, the tumor nuclear grade, the presence of comedo necrosis and microinvasion influenced the MRI and mammographic size estimates by using the chi-square test. Of the 72 DCIS lesions, 68 (94%) were detected by MRI and 62 (86%) were detected by mammography. Overall, the Pearson's correlation of the size between MRI and histopathology was 0.786 versus 0.633 between mammography and histopathology (p < 0.001). MRI underestimated the size by more than 1 cm (including false negative examination) in 12 patients (17%), was accurate in 52 patients (72%) and overestimated the size by more than 1 cm in eight patients (11%) whereas mammography underestimated the size in 25 patients (35%), was accurate in 31 patients (43%) and overestimated the size in 16 patients (22%). The MRI, but not the mammography, showed significant correlation for the assessment of the size of tumor in noncomedo DCIS (p < 0.001 vs p = 0.060). The assessment of tumor size by MRI was affected by the nuclear grade (p = 0.008) and the presence of comedo necrosis (p = 0.029), but not by the breast density (p 0.747) or microinvasion (p = 0.093). MRI was more accurate for the detection and assessment of the size of DCIS than mammography.

Kim, Do Youn; Moon, Woo Kyung; Cho, Nariya [Seoul National University and The Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul (Korea, Republic of)] (and others)

2007-02-15

151

MRI of the Breast for the Detection and Assessment of the Size of Ductal Carcinoma in Situ  

International Nuclear Information System (INIS)

The aim of the study was to compare the accuracy of magnetic resonance imaging (MRI) and mammography for the detection and assessment of the size of ductal carcinoma in situ (DCIS). The preoperative contrast-enhanced MRI and mammography were analyzed in respect of the detection and assessment of the size of DCIS in 72 patients (age range: 30 67 years, mean age: 47 years). The MRI and mammographic measurements were compared with the histopathologic size with using the Pearson's correlation coefficients and the Mann-Whitney u test. We evaluated whether the breast density, the tumor nuclear grade, the presence of comedo necrosis and microinvasion influenced the MRI and mammographic size estimates by using the chi-square test. Of the 72 DCIS lesions, 68 (94%) were detected by MRI and 62 (86%) were detected by mammography. Overall, the Pearson's correlation of the size between MRI and histopathology was 0.786 versus 0.633 between mammography and histopathology (p < 0.001). MRI underestimated the size by more than 1 cm (including false negative examination) in 12 patients (17%), was accurate in 52 patients (72%) and overestimated the size by more than 1 cm in eight patients (11%) whereas mammography underestimated the size in 25 patients (35%), was accurate in 31 patients (43%) and overestimated the size in 16 patients (22%). The MRI, but not the mammography, showed significant correlation for the assessment of the size of tumor in noncomedo DCIS (p < 0.001 vs p = 0.060). Tnoncomedo DCIS (p < 0.001 vs p = 0.060). The assessment of tumor size by MRI was affected by the nuclear grade (p = 0.008) and the presence of comedo necrosis (p = 0.029), but not by the breast density (p 0.747) or microinvasion (p = 0.093). MRI was more accurate for the detection and assessment of the size of DCIS than mammography

152

Detection of osseous metastases of the spine: Comparison of high resolution multi-detector-CT with MRI  

Energy Technology Data Exchange (ETDEWEB)

Purpose: The aim of the study was to evaluate the diagnostic accuracy of multi-slice-computed tomography (MDCT) for the detection of vertebral metastases in comparison to magnetic resonance imaging (MRI). Materials and methods: In a retrospective analysis, 639 vertebral bodies of 41 patients with various histologically confirmed primary malignancies were analysed. The MDCT-images were acquired on a 16/64-row-MDCT scanner (Siemens Somatom Sensation 16/64). MRI was performed on 1.5 T scanners (SIEMENS Symphony/Sonata). The MDCT- and MRI-images were evaluated separately by two experienced radiologists in a consensus reading. The combination of MDCT and MRI in an expert reading including follow-up examinations and/or histology as well as clinical data served as the gold standard. Results: 201/639 vertebral bodies were defined as metastatically affected by the gold standard. In MDCT 133/201 lesions, in MRI 198/201 lesions were detected. 68 vertebral bodies were false negative in MDCT, whereas 3 false negatives were found in MRI. 3 false positive results were obtained in MDCT, 5 in MRI. Sensitivity was significantly lower for MDCT (66.2%) than for MRI (98.5%) (p < 0.0001). Specificity was not significantly different for both methods (MDCT: 99.3%; MRI: 98.9%). The diagnostic accuracy resulted in 88.8% for MDCT and 98.7% for MRI. Conclusion: Although 16/64-row-MDCT provides excellent image quality and a high spatial resolution in the assessment of bony structures, metastatic lesions without significant bone destruction may be missed. The diagnostic accuracy of MRI proved to be significantly superior to 16/64-row-MDCT for the detection of osseous metastases.

Buhmann, Sonja [Department of Radiology, University Hospital Munich-Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany)], E-mail: Sonja.Buhmann@med.uni-muenchen.de; Becker, Christoph [Department of Radiology, University Hospital Munich-Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany)], E-mail: Christoph.Becker@med.uni-muenchen.de; Duerr, Hans Roland [Department of Orthopaedic Surgery, University Hospital Munich-Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany)], E-mail: Hans_Roland.Duerr@med.uni-muenchen.de; Reiser, Maximilian [Department of Radiology, University Hospital Munich-Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany)], E-mail: Maximilian.Reiser@med.uni-muenchen.de; Baur-Melnyk, Andrea [Department of Radiology, University Hospital Munich-Grosshadern, Marchioninistrasse 15, 81377 Munich (Germany)], E-mail: Andrea.Baur@med.uni-muenchen.de

2009-03-15

153

Clinical evaluation of asymptomatic sinus disease detected by MRI  

International Nuclear Information System (INIS)

The detection of lesions of the paranasal sinuses as incidental findings during magnetic resonance imaging of patients suspected of intracranial disease who have no nasal symptoms has been far more common than we expected. The present study was performed on 325 patients with a mean age of 60.7 years. Medical histories were taken whether they had any nasal symptoms or not. Asymptomatic sinus disease was present in 41.6% of the 257 patients who had no nasal symptoms, and 9.7% of the patients had either marked mucosal thickening, excessive fluid or polyps in the maxillary sinuses. Although the mean age of these patients was comparatively high, we can infer that 1 in 10 have relatively severe sinus lesions. Mucociliary transport time was measured using the saccharin method in 15 patients who had sinus disease but no nasal symptoms. The mean transport time was 15.6 minutes and within normal limits. Routine ENT examination revealed no lesions in the nasal cavity of any of the subjects. We classified the patients with asymptomatic sinus disease into two groups -- group A: patients with sinus disease associated with some nasal manifestations but who did not complain about them, and group B: patients who had sinus disease but did not have any nasal problems. Group B represents genuine asymptomatic sinus disease in the narrow sense. Most asymptomatic patients in this study appeared to belong to group B. They had some sinus disease, but because their mucociliary function in their nasal cavity was normal, they did not have any nasal symptoms. When we find patients with asymptomatic sinus disease, we have to determine which group they belong to by examining their nasal cavity and measuring their saccharin time. Patients in group A should be medically treated, but those in group B should be followed without medical treatment. (author)

154

Detection of rheumatoid arthritis bone erosions by two different dedicated extremity MRI units and conventional radiography  

DEFF Research Database (Denmark)

Objectives: To compare the ability of two different dedicated extremity MRI (E-MRI) units and conventional radiography (CR) for identifying bone erosions in rheumatoid arthritis (RA) metacarpophalangeal (MCP) and wrist joints. Methods: CR and two MRI examinations (using 0.2 T Esaote Artoscan and 0.2 T portable MagneVu MV1000 units) of 418 bones in the dominant wrist and second to fifth MCP joints of 15 patients with RA and 4 healthy controls were performed and evaluated blindly for bones being visible and for erosions. Results: In MCP joints, MagneVu visualised 18.5% of bones entirely and 71.1% were 67-99% visualised. In wrists, MagneVu visualised 1.5% of bones entirely, 39.8% were 67-99% visualised and 19% were not visualised at all. Artoscan and CR visualised all bones entirely. Artoscan, MagneVu and CR found 22, 19 and 15 bones with erosions in MCP joints and 66, 40 and 13 bones with erosions in wrist joints, respectively. With the previously validated Artoscan unit as standard reference, MagneVu and CR had sensitivities of 0.82 and 0.55, respectively, in MCP joint bones and 0.41 and 0.14 in wrist bones. Specificities of CR and MagneVu were comparable (0.82-0.99). The MagneVu unit was particularly more sensitive than CR for metacarpal heads and carpal bones. MagneVu MRI and CR detected 100% and 89%, respectively, of large erosions (Outcome Measures in Rheumatoid Arthritis Clinical Trials-Rheumatoid Arthritis MRI Scoring System (OMERACT-RAMRIS) score >1 on Artoscan) in MCP joints and 69% and 15.8% of large erosions in wrists. Conclusions: Both E-MRI units detected more erosions than CR, in particular due to a higher sensitivity in metacarpal heads and carpal bones. The MagneVu unit detected fewer erosions than the Artoscan unit due to a lower average image quality and a smaller proportion of bones being visualised Udgivelsesdato: 2008/7

Duer-Jensen, A.; Vestergaard, A.

2008-01-01

155

Role of ultrasonography and MRI in the detection of wide intraductal component of invasive breast cancer-a prospective study  

International Nuclear Information System (INIS)

rs. Sensitivity, specificity and accuracy for detection of wide intraductal components towards the nipple by US were 87.5, 88.3, and 88.1%, respectively. Sensitivity, specificity and accuracy for detection of wide intraductal components towards the nipple by MRI were 50, 79.1, and 72.1%, respectively. When the results of both diagnostic methods namely US and MRI were combined, sensitivity rose to 93.7%, specificity was 72.1% and accuracy was 78.0%. Conclusion: Although ultrasound is more sensitive than MRI in the delineation of intraductal extension towards the nipple, there is no statistically significant difference in overall accuracy between the two modalities

156

Feasibility of shutter-speed DCE-MRI for improved prostate cancer detection.  

Science.gov (United States)

The feasibility of shutter-speed model dynamic-contrast-enhanced MRI pharmacokinetic analyses for prostate cancer detection was investigated in a prebiopsy patient cohort. Differences of results from the fast-exchange-regime-allowed (FXR-a) shutter-speed model version and the fast-exchange-limit-constrained (FXL-c) standard model are demonstrated. Although the spatial information is more limited, postdynamic-contrast-enhanced MRI biopsy specimens were also examined. The MRI results were correlated with the biopsy pathology findings. Of all the model parameters, region-of-interest-averaged K(trans) difference [?K(trans) ? K(trans)(FXR-a) - K(trans)(FXL-c)] or two-dimensional K(trans)(FXR-a) vs. k(ep)(FXR-a) values were found to provide the most useful biomarkers for malignant/benign prostate tissue discrimination (at 100% sensitivity for a population of 13, the specificity is 88%) and disease burden determination. (The best specificity for the fast-exchange-limit-constrained analysis is 63%, with the two-dimensional plot.) K(trans) and k(ep) are each measures of passive transcapillary contrast reagent transfer rate constants. Parameter value increases with shutter-speed model (relative to standard model) analysis are larger in malignant foci than in normal-appearing glandular tissue. Pathology analyses verify the shutter-speed model (FXR-a) promise for prostate cancer detection. Parametric mapping may further improve pharmacokinetic biomarker performance. PMID:22457233

Li, Xin; Priest, Ryan A; Woodward, William J; Tagge, Ian J; Siddiqui, Faisal; Huang, Wei; Rooney, William D; Beer, Tomasz M; Garzotto, Mark G; Springer, Charles S

2013-01-01

157

Progress on detection of liquid explosives using ultra-low field MRI  

Energy Technology Data Exchange (ETDEWEB)

Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) methods are widely used in medicine, chemistry and industry. Over the past several years there has been increasing interest in performing NMR and MRI in the ultra-low field (ULF) regime, with measurement field strengths of 10-100 microTesla and pre-polarization fields of 30-50 mTesla. The real-time signal-to-noise ratio for such measurements is about 100. Our group at LANL has built and demonstrated the performance of SQUID-based ULF NMR/MRI instrumentation for classification of materials and detection of liquid explosives via their relaxation properties measured at ULF, using T{sub 1}, and T{sub 2}, and T{sub 1} frequency dispersion. We are also beginning to investigate the performance of induction coils as sensors. Here we present recent progress on the applications of ULF MR to the detection of liquid explosives, in imaging and relaxometry.

Espy, Michelle A [Los Alamos National Laboratory; Matlashov, Andrei N [Los Alamos National Laboratory; Volegov, Petr L [Los Alamos National Laboratory; Schuttz, Larry M [Los Alamos National Laboratory; Baguisa, Shermiyah [Los Alamos National Laboratory; Dunkerley, David [Los Alamos National Laboratory; Magnelind, Per [Los Alamos National Laboratory; Owens, Tuba [Los Alamos National Laboratory; Sandin, Henrik [Los Alamos National Laboratory; Urbaitis, Algis [Los Alamos National Laboratory

2010-01-01

158

Incremental activation detection for real-time fMRI series using robust Kalman filter.  

Science.gov (United States)

Real-time functional magnetic resonance imaging (rt-fMRI) is a technique that enables us to observe human brain activations in real time. However, some unexpected noises that emerged in fMRI data collecting, such as acute swallowing, head moving and human manipulations, will cause much confusion and unrobustness for the activation analysis. In this paper, a new activation detection method for rt-fMRI data is proposed based on robust Kalman filter. The idea is to add a variation to the extended kalman filter to handle the additional sparse measurement noise and a sparse noise term to the measurement update step. Hence, the robust Kalman filter is designed to improve the robustness for the outliers and can be computed separately for each voxel. The algorithm can compute activation maps on each scan within a repetition time, which meets the requirement for real-time analysis. Experimental results show that this new algorithm can bring out high performance in robustness and in real-time activation detection. PMID:24511325

Li, Liang; Yan, Bin; Tong, Li; Wang, Linyuan; Li, Jianxin

2014-01-01

159

New hybrid remote sensing method using HPM illumination/IR detection for mine detection  

Science.gov (United States)

A new hybrid remote-sensing method using active high-power microwave (HPM) illumination and passive infrared (IR) detection is presented for the detection of shallow buried landmines. A 2.45 GHz, 5 kW microwave source was used for illumination. The thermal signature of the mine at the soil surface was detected in the 8 - 12 micrometer region both in near real-time as well as after a brief time-delay following illumination. The thermal signature at the soil surface is primarily made up of two components. A thermal signature occurs at the soil surface in near real-time due to the interference of the incident beam and the beam reflected by the mine. A second thermal signature is generated when the variations in heating due to differential microwave absorption by the mine and the surrounding soil is conducted upwards from the mine location to the surface. Both signatures are dependent on the complex dielectric constants of the mine and the soil. Results will be presented from laboratory experiments and field trials with different types of metallic and non-metallic mine surrogates, dummy mines without explosives and live mines with explosives but without fuses.

Khanna, Shyam M.; Paquet, Francois; Apps, Rene; Seregelyi, Joe S.

1998-09-01

160

Neuronal event detection in fMRI time series using iterative deconvolution techniques.  

Science.gov (United States)

An iterative estimation algorithm for deconvolution of neuronal activity from Blood Oxygen Level Dependent (BOLD) time series data is presented. The algorithm requires knowledge of the hemodynamic impulse response function but does not require knowledge of the stimulation function. The method uses majorization-minimization of a cost function to find an optimal solution to the inverse problem. The cost function includes penalties for the l(1) norm, total variation and negativity. The algorithm is able to identify the occurrence of neuronal activity bursts from BOLD time series accurately. The accuracy of the algorithm was tested in simulations and experimental fMRI data using blocked and event-related designs. The simulations revealed that the algorithm is most sensitive to contrast-to-noise ratio levels and to errors in the assumed hemodynamic model and least sensitive to autocorrelation in the noise. Within normal fMRI conditions, the method is effective for event detection. PMID:21232893

Hernandez-Garcia, Luis; Ulfarsson, Magnus O

2011-04-01

 
 
 
 
161

In vitro and in vivo magnetic resonance imaging (MRI) detection of GFP through magnetization transfer contrast (MTC).  

Science.gov (United States)

Green fluorescent protein (GFP) is a widely utilized molecular marker of gene expression. However, its use in in vivo imaging has been restricted to transparent tissue mainly due to the tissue penetrance limitation of optical imaging. Here, we report a novel approach to detect GFP with Magnetization transfer contrast (MTC) magnetic resonance imaging (MRI). MTC is an MRI methodology currently utilized to detect macromolecule changes such as decrease in myelin and increase in collagen content. We employed MTC MRI imaging to detect GFP both in vitro and in in vivo mouse models. We demonstrated that our approach produces values that are protein specific, and concentration dependent. This approach provides a flexible, non-invasive in vivo molecular MRI imaging strategy that is dependent upon the presence and concentration of the GFP reporter. PMID:20060482

Pérez-Torres, Carlos J; Massaad, Cynthia A; Hilsenbeck, Susan G; Serrano, Faridis; Pautler, Robia G

2010-04-01

162

Detection of epileptogenic cortical malformations with surface-based MRI morphometry.  

Science.gov (United States)

Magnetic resonance imaging has revolutionized the detection of structural abnormalities in patients with epilepsy. However, many focal abnormalities remain undetected in routine visual inspection. Here we use an automated, surface-based method for quantifying morphometric features related to epileptogenic cortical malformations to detect abnormal cortical thickness and blurred gray-white matter boundaries. Using MRI morphometry at 3T with surface-based spherical averaging techniques that precisely align anatomical structures between individual brains, we compared single patients with known lesions to a large normal control group to detect clusters of abnormal cortical thickness, gray-white matter contrast, local gyrification, sulcal depth, jacobian distance and curvature. To assess the effects of threshold and smoothing on detection sensitivity and specificity, we systematically varied these parameters with different thresholds and smoothing levels. To test the effectiveness of the technique to detect lesions of epileptogenic character, we compared the detected structural abnormalities to expert-tracings, intracranial EEG, pathology and surgical outcome in a homogeneous patient sample. With optimal parameters and by combining thickness and GWC, the surface-based detection method identified 92% of cortical lesions (sensitivity) with few false positives (96% specificity), successfully discriminating patients from controls 94% of the time. The detected structural abnormalities were related to the seizure onset zones, abnormal histology and positive outcome in all surgical patients. However, the method failed to adequately describe lesion extent in most cases. Automated surface-based MRI morphometry, if used with optimized parameters, may be a valuable additional clinical tool to improve the detection of subtle or previously occult malformations and therefore could improve identification of patients with intractable focal epilepsy who may benefit from surgery. PMID:21326599

Thesen, Thomas; Quinn, Brian T; Carlson, Chad; Devinsky, Orrin; DuBois, Jonathan; McDonald, Carrie R; French, Jacqueline; Leventer, Richard; Felsovalyi, Olga; Wang, Xiuyuan; Halgren, Eric; Kuzniecky, Ruben

2011-01-01

163

Presumptive subarticular stress reactions of the knee: MRI detection and association with meniscal tear patterns  

Energy Technology Data Exchange (ETDEWEB)

MRI detects subchondral marrow findings in painful knees which bear resemblance to spontaneous osteonecrosis of the knee (SONK). Gathering evidence suggests that the primary or predominant pathogenesis of these lesions is physical stress. This study analyzes the patient characteristics and meniscal pathology associated with these lesions - herein referred to as ''presumptive subarticular stress related'' (PSSR) lesions. All patients were scanned using a standardized imaging protocol. The criterion for a PSSR lesion was a subchondral marrow edema pattern encompassing a more focal, low-signal zone adjacent to or contiguous with the subchondral cortex. Patients were identified using an electronic database search of cases reported by one experienced musculoskeletal radiologist. Twenty-five PSSR lesions were identified among 1,948 MRI evaluations of the knee. Twenty-one PSSR lesions occurred in the medial compartment, and four occurred in the lateral compartment. There was no sex predilection. Patients with PSSR lesions were older than other patients undergoing MRI evaluation (mean 66 years versus 52 years, P<0.001). Meniscal tears occurred more commonly in cases with PSSR lesions than in the group as a whole (76% versus 45%, P<0.001). Radial and posterior root tears were more common in knees with PSSR lesions than in other knees with meniscal tears (53% versus 26%, P<0.01). PSSR lesions are associated with meniscal tears and, more specifically, with meniscal tear patterns that dramatically increase contact forces across the knee joint. This observation supports the hypothesis that mechanical stress is important in the pathogenesis of these subarticular lesions that are detected by MRI. (orig.)

Yao, Lawrence [Diagnostic Radiology Department, National Institutes of Health, Building 10, Room 1C640, 10 Center Drive, MSC 1182, MD 20892-1182, Bethesda (United States); Stanczak, Jeffrey [Fairfax Radiological Consultants, PC, 2722 Merrilee Drive, Suite 230, VA 22031, Fairfax (United States); Boutin, Robert D. [MedTel International, 1430 Spring Hill Road, State 500, VA 22102, Mclean (United States)

2004-05-01

164

A pooled analysis of MRI in the detection of bone marrow infiltration in patients with malignant lymphoma  

International Nuclear Information System (INIS)

Aim: To explore the role of magnetic resonance imaging (MRI) in detecting bone marrow infiltration of malignant lymphoma through a systematic review and meta-analysis. Materials and methods: Studies that evaluated the diagnostic performance of MRI in detecting bone marrow infiltration of malignant lymphoma were acquired from the MEDLINE, EMBASE, Cancerlit, and Cochrane Library database, from February 1987 to May 2012. Pooled estimation and subgroup analysis data were obtained by statistical analysis. Results: A total of 13 studies involving 634 patients who fulfilled all of the inclusion criteria were considered for the analysis. No publication bias was found (p = 0.70). The pooled sensitivity of MRI was 0.82 [95% confidence intervals (CI): 0.70–0.90] and the pooled specificity was 0.79 (95% CI: 0.72–0.84). Overall, positive likelihood ratios (LR+) was 3.9 (95% CI: 2.8–5.4) and negative likelihood ratios (LR?) was 0.23 (95% CI: 0.13–0.41). In patients with high pre-test probabilities, MRI enabled confirmation of bone marrow involvement; in patients with low pre-test probabilities, MRI enabled exclusion of bone marrow involvement. Worst-case-scenario (pre-test probability, 50%) post-test probabilities were 80% and 18% for positive and negative MRI results, respectively. In subgroup analysis, MRI performed with 1.5 T devices had higher pooled specificity (0.80, 95% CI: 0.71–0.88) than the MRI with ?1 T (0.78, 95% CI: 0.71–0.85; p < 0.05). The pooled sensitivity of MRI with diffusion-weighted imaging (DWI) was 0.65 (95% CI: 0.39–0.92) and the pooled specificity was 0.83 (95% CI: 0.69–0.97). The sensitivity and specificity of MRI without DWI was 0.85 (95% CI: 0.76–0.94) and 0.79 (95% CI: 0.72–0.85), respectively. Conclusion: A limited number of small studies indicate that MRI can serve as a valuable tool for detecting bone marrow infiltration of malignant lymphoma. Results were most promising when performing MRI using high field strength devices. MRI with DWI is shown to be more specific than conventional MRI techniques. This deserves further investigation in future studies

165

Modeling Chemical Detection Sensitivities of Active and Passive Remote Sensing Systems  

Energy Technology Data Exchange (ETDEWEB)

During nearly a decade of remote sensing programs under the auspices of the U. S. Department of Energy (DOE), LLNL has developed a set of performance modeling codes--called APRS--for both Active and Passive Remote Sensing systems. These codes emphasize chemical detection sensitivity in the form of minimum detectable quantities with and without background spectral clutter and in the possible presence of other interfering chemicals. The codes have been benchmarked against data acquired in both active and passive remote sensing programs at LLNL and Los Alamos National Laboratory (LANL). The codes include, as an integral part of the performance modeling, many of the data analysis techniques developed in the DOE's active and passive remote sensing programs (e.g., ''band normalization'' for an active system, principal component analysis for a passive system).

Scharlemann, E T

2003-07-28

166

Application of MultiScale Hidden Markov Modeling Wavelet Coefficients to fMRI Activation Detection  

Directory of Open Access Journals (Sweden)

Full Text Available Problem Statement: The problem of detection of functional magnetic resonance images (fMRIs, that is, to decide active and nonactive regions of human brain from fMRIs is studied in this paper. fMRI research is finding and will find more and more applications in diagnosing and treating brain diseases like depression and schizophrenia. At its initial stage fMRI detection are pixel-wise methods, which do not take advantage of mutual information among neighboring pixels. Ignoring such spatial information can reduce detection accuracy. During past decade, many efforts have been focusing on taking advantage of spatial correlation inherent in fMRI data. Most well known is smoothing using a fixed Gaussian filter and the compensation for multiple testing using Gaussian random field theory as used by Statistical Parametric Mapping (SPM. Other methods including wavelets had also been proposed by the community. Approach: In this study a novel two-step approach was put forward that incorporates spatial correlation information and is amenable to analysis and optimization. First, a new multi scale image segmentation algorithm was proposed to decompose the correlation image into several different regions, each of which is of homogeneous statistical behavior. Second, each region will be classified independently as active or inactive using existing pixel-wise test methods. The image segmentation consists of two procedures: Edge detection followed by label estimation. To deduce the presence or absence of an edge from continuous data, two fundamental assumption of our algorithm are 1 each wavelet coefficient was described by a 2-state Gaussian Mixture Model (GMM; 2 across scale, each state is caused by its parent state, hence the Multiscale Hidden Markov Model (MHMM. The states of Markov chain are unknown ("hidden" and represent the presence (state 1 or absence (state 0 of edges. Using this interpretation, the edge detection problem boils down to the posterior state estimation given observation. Results: Data processing results demonstrate much improved efficiency of our algorithm compared with pixel-wise detection methods. Conclusions: Our methods and results stress the importance of spatial-temporal modeling in fMRI research.

Fangyuan Nan

2008-01-01

167

A Novel Datamining Based Approach for Remote Intrusion Detection  

Directory of Open Access Journals (Sweden)

Full Text Available Today, as information systems are more open to the Internet,attacks and intrusions are also increasing rapidly so the importance of secure networks is also vital. New intelligent Intrusion Detection Systems which are based on sophisticated algorithms are in demand.Intrusion Detection System (IDS is an important detection used as a countermeasure to preserve data integrity and system availability from attacks. It is a combination of software and hardware that attempts to perform intrusion detection.In data mining based intrusion detection system, we should make use of particular domain knowledge in relation to intrusion detection in order to efficiently extract relative rules from large amounts of records.This paper proposes boosting method for intrusion detection and it is possible to detect the intrusions in all the Systems, without installing the Software in client System (like client-server via Web service (Apache tomcat by using the ip address of the client system.

Renu Deepti.S, Loshma.G

2012-06-01

168

Frequency Modulation Spectroscopy Modeling for Remote Chemical Detection  

Energy Technology Data Exchange (ETDEWEB)

Frequency modulation (FM) spectroscopy techniques show promise for active infrared remote chemical sensing. FM spectroscopy techniques have reduced sensitivity to optical and electronic noise, and are relatively immune to the effects of various electronic and mechanical drifts. FM systems are responsive to sharp spectral features and can therefore reduce the effects of spectral clutter due to interfering chemicals in the plume or in the atmosphere. The relatively high modulation frequencies used for FM also reduces the effects of albedo (reflectance) and plume variations. Conventional differential absorption lidar (DIAL) systems are performance limited by the noise induced by speckle. Analysis presented in this report shows that FM based sensors may reduce the effects of speckle by one to two orders of magnitude. This can result in reduced dwell times and faster area searches, as well as reducing various forms of spatial clutter. FM systems will require a laser system that is continuously tunable at relatively high frequencies (0.1 to 20 MHz). One promising candidate is the quantum-cascade (QC) laser [1, 2]. The QC laser is potentially capable of power levels on the order of 1 Watt and frequency tuning on the order of 3 - 6 GHz, which is the performance level required for FM spectroscopy based remote sensing. In this report we describe a high-level numerical model for an FM spectroscopy based remote sensing system, and application to two unmanned airborne vehicle (UAV) scenarios. A Predator scenario operating at a slant range of 6.5 km with a 10 cm diameter telescope, and a Global Hawk scenario operating at a range of 30 km with a 20 cm diameter telescope, has been assumed to allow estimation of the performance of potential FM systems.

Sheen, David M.

2000-09-30

169

Detection of Gypsy Moth Defoliation--Remote Sensing Lesson  

Science.gov (United States)

This module uses satellite remote sensing images to identify the forest defoliation caused by Gypsy Moth Larva. The continued annual defoliation causes the trees to die and results in a significant loss in the value of the forests. The project study area covers the highland mountain areas of Virginia and West Virginia in the 2001 growing season, as both satellite images and other proof of defoliation are available for that year. The educational materials are available for download in PDF, ZIP and RAR format.

2012-03-09

170

Breast MRI in detecting primary malignancy of patients presenting with axillary metastases and negative X-ray mammography  

International Nuclear Information System (INIS)

Objective: To evaluate the role of breast MRI in detecting the primary malignancy in patients presenting solely with axillary lymph node metastases. Methods: Thirty-three patients with axillary lymph node metastases but negative findings on either physical examination or mammography underwent breast MRI to identify occult breast carcinoma. MRI of the breast was assessed according to BI-RADS criteria. The pathologic diagnosis was made according to the standard criteria by the WHO Classification of' Tumor. Results: Among 33 patients presenting solely with axillary metastases, 30 patients underwent modified radical mastectomy. Primary breast carcinoma was proven in 17 patients. MRI detected lesions in 16 patients, including 10 masses and 6 non-mass lesions. Size of the masses ranged from 0.5 to 2.6 cm (mean 1.5 cm). Six lesions were smaller than 1.5 cm in size. Non-mass lesions showed ductal enhancement in 4 cases and segmental enhancement in 2 cases. One patient with tumor detected by histopathology showed no abnormal enhancement on MRI. No tumor was found at mastectomy in the other 13 women, and negative MR findings were revealed in 9. Four cases with suspicious enhancement on MRI had no corresponding primary foci on pathology. Three patients didn't undergo surgical procedure, The sensitivity, specificity, and accuracy of MRI in the diagnosis of the primary malignancy were 94.1%, 69.2%, and 83.3%, respectively. Conclusions: Small size of mass and ductal or segmental enhancement of non-mass lesion were common MR features of occult malignancy. MRI showed high sensitivity and accuracy in diagnosing occult breast carcinoma. Breast MRI should be taken in search of occult malignancy in patients with axillary metastases. (authors)

171

Detection of emission sources using passive-remote Fourier transform infrared spectroscopy  

International Nuclear Information System (INIS)

The detection and identification of toxic chemicals released in the environment is important for public safety. Passive-remote Fourier transform infrared (FTIR) spectrometers can be used to detect these releases. Their primary advantages are their small size and ease of setup and use. Open-path FTIR spectrometers are used to detect concentrations of pollutants from a fixed frame of reference. These instruments detect plumes, but they are too large and difficult to aim to be used to track a plume to its source. Passive remote FTIR spectrometers contain an interferometer, optics, and a detector. They can be used on tripods and in some cases can be hand-held. A telescope can be added to most units. We will discuss the capability of passive-remote FTIR spectrometers to detect the origin of plumes. Low concentration plumes were released using a custom-constructed vaporizer. These plumes were detected with different spectrometers from different distances. Passive-remote spectrometers were able to detect small 10 cm on a side chemical releases at concentration-pathlengths at the low parts per million-meter (ppm-m) level

172

Computer-aided detection in breast MRI: a systematic review and meta-analysis  

International Nuclear Information System (INIS)

To evaluate the additional value of computer-aided detection (CAD) in breast MRI by assessing radiologists' accuracy in discriminating benign from malignant breast lesions. A literature search was performed with inclusion of relevant studies using a commercially available CAD system with automatic colour mapping. Two independent researchers assessed the quality of the studies. The accuracy of the radiologists' performance with and without CAD was presented as pooled sensitivity and specificity. Of 587 articles, 10 met the inclusion criteria, all of good methodological quality. Experienced radiologists reached comparable pooled sensitivity and specificity before and after using CAD (sensitivity: without CAD: 89%; 95% CI: 78-94%, with CAD: 89%; 95%CI: 81-94%) (specificity: without CAD: 86%; 95% CI: 79-91%, with CAD: 82%; 95% CI: 76-87%). For residents the pooled sensitivity increased from 72% (95% CI: 62-81%) without CAD to 89% (95% CI: 80-94%) with CAD, however, not significantly. Concerning specificity, the results were similar (without CAD: 79%; 95% CI: 69-86%, with CAD: 78%; 95% CI: 69-84%). CAD in breast MRI has little influence on the sensitivity and specificity of experienced radiologists and therefore their interpretation remains essential. However, residents or inexperienced radiologists seem to benefit from CAD concerning breast MRI evaluation. (orig.)

173

Remote sensing detection of droughts in Amazonian forest canopies.  

Science.gov (United States)

*Remote sensing data are a key tool to assess large forested areas, where limitations such as accessibility and lack of field measurements are prevalent. Here, we have analysed datasets from moderate resolution imaging spectroradiometer (MODIS) satellite measurements and field data to assess the impacts of the 2005 drought in Amazonia. *We combined vegetation indices (VI) and climatological variables to evaluate the spatiotemporal patterns associated with the 2005 drought, and explore the relationships between remotely-sensed indices and forest inventory data on tree mortality. *There were differences in results based on c4 and c5 MODIS products. C5 VI showed no spatial relationship with rainfall or aerosol optical depth; however, distinct regions responded significantly to the increased radiation in 2005. The increase in the Enhanced VI (EVI) during 2005 showed a significant positive relationship (P < 0.07) with the increase of tree mortality. By contrast, the normalized difference water index (NDWI) exhibited a significant negative relationship (P < 0.09) with tree mortality. *Previous studies have suggested that the increase in EVI during the 2005 drought was associated with a positive response of forest photosynthesis to changes in the radiation income. We discuss the evidence that this increase could be related to structural changes in the canopy. PMID:20659255

Anderson, Liana O; Malhi, Yadvinder; Aragão, Luiz E O C; Ladle, Richard; Arai, Egidio; Barbier, Nicolas; Phillips, Oliver

2010-08-01

174

Agricultural practices in grasslands detected by spatial remote sensing.  

Science.gov (United States)

The major decrease in grassland surfaces associated with changes in their management that has been observed in many regions of the earth during the last half century has major impacts on environmental and socio-economic systems. This study focuses on the identification of grassland management practices in an intensive agricultural watershed located in Brittany, France, by analyzing the intra-annual dynamics of the surface condition of vegetation using remotely sensed and field data. We studied the relationship between one vegetation index (NDVI) and two biophysical variables (LAI and fCOVER) derived from a series of three SPOT images on one hand and measurements collected during field campaigns achieved on 120 grasslands on the other. The results show that the LAI appears as the best predictor for monitoring grassland mowing and grazing. Indeed, because of its ability to characterize vegetation status, LAI estimated from remote sensing data is a relevant variable to identify these practices. LAI values derived from the SPOT images were then classified based on the K-Nearest Neighbor (KNN) supervised algorithm. The results points out that the distribution of grassland management practices such as grazing and mowing can be mapped very accurately (Kappa index?=?0.82) at a field scale over large agricultural areas using a series of satellite images. PMID:25182683

Dusseux, Pauline; Vertès, Françoise; Corpetti, Thomas; Corgne, Samuel; Hubert-Moy, Laurence

2014-12-01

175

Contrast-enhanced spectral mammography versus MRI: Initial results in the detection of breast cancer and assessment of tumour size  

International Nuclear Information System (INIS)

To compare mammography (MG), contrast-enhanced spectral mammography (CESM), and magnetic resonance imaging (MRI) in the detection and size estimation of histologically proven breast cancers using postoperative histology as the gold standard. After ethical approval, 80 women with newly diagnosed breast cancer underwent MG, CESM, and MRI examinations. CESM was reviewed by an independent experienced radiologist, and the maximum dimension of suspicious lesions was measured. For MG and MRI, routine clinical reports of breast specialists, with judgment based on the BI-RADS lexicon, were used. Results of each imaging technique were correlated to define the index cancer. Fifty-nine cases could be compared to postoperative histology for size estimation. Breast cancer was visible in 66/80 MG, 80/80 CESM, and 77/79 MRI examinations. Average lesion largest dimension was 27.31 mm (SD 22.18) in MG, 31.62 mm (SD 24.41) in CESM, and 27.72 mm (SD 21.51) in MRI versus 32.51 mm (SD 29.03) in postoperative histology. No significant difference was found between lesion size measurement on MRI and CESM compared with histopathology. Our initial results show a better sensitivity of CESM and MRI in breast cancer detection than MG and a good correlation with postoperative histology in size assessment. (orig.)

176

Contrast-enhanced spectral mammography versus MRI: Initial results in the detection of breast cancer and assessment of tumour size  

Energy Technology Data Exchange (ETDEWEB)

To compare mammography (MG), contrast-enhanced spectral mammography (CESM), and magnetic resonance imaging (MRI) in the detection and size estimation of histologically proven breast cancers using postoperative histology as the gold standard. After ethical approval, 80 women with newly diagnosed breast cancer underwent MG, CESM, and MRI examinations. CESM was reviewed by an independent experienced radiologist, and the maximum dimension of suspicious lesions was measured. For MG and MRI, routine clinical reports of breast specialists, with judgment based on the BI-RADS lexicon, were used. Results of each imaging technique were correlated to define the index cancer. Fifty-nine cases could be compared to postoperative histology for size estimation. Breast cancer was visible in 66/80 MG, 80/80 CESM, and 77/79 MRI examinations. Average lesion largest dimension was 27.31 mm (SD 22.18) in MG, 31.62 mm (SD 24.41) in CESM, and 27.72 mm (SD 21.51) in MRI versus 32.51 mm (SD 29.03) in postoperative histology. No significant difference was found between lesion size measurement on MRI and CESM compared with histopathology. Our initial results show a better sensitivity of CESM and MRI in breast cancer detection than MG and a good correlation with postoperative histology in size assessment. (orig.)

Fallenberg, E.M.; Renz, D.M. [Charite - Universitaetsmedizin Berlin, Clinic of Radiology, Berlin (Germany); Dromain, C. [Institut Gustave Roussy, Department of Radiology, Villejuif cedex (France); Diekmann, F. [St. Joseph-Stift Bremen, Department of Medical Imaging, Bremen (Germany); Engelken, F.; Krohn, M.; Singh, J.M.; Bick, U. [Charite - Universitaetsmedizin Berlin, Department of Radiology, Berlin (Germany); Ingold-Heppner, B. [Charite - Universitaetsmedizin Berlin, Institute of Pathology, Berlin (Germany); Winzer, K.J. [Charite - Universitaetsmedizin Berlin, Breast Center, Department of Gynecology, Berlin (Germany)

2014-01-15

177

[Detection of oculomotor nerve compression by 3D-FIESTA MRI in a patient with pituitary apoplexy and diabetes mellitus].  

Science.gov (United States)

We report the usefulness of 3D-FIESTA magnetic resonance imaging(MRI)for the detection of oculomotor nerve palsy in a case of pituitary apoplexy. A 69-year-old man with diabetes mellitus presented with complete left-side blepharoptosis. Computed tomography of the brain showed an intrasellar mass with hemorrhage. MRI demonstrated a pituitary adenoma with a cyst toward the left cavernous sinus, which was diagnosed as pituitary apoplexy. 3D-FIESTA revealed that the left oculomotor nerve was compressed by the cyst. He underwent trans-sphenoid tumor resection at 5 days after his hospitalization. Post-operative 3D-FIESTA MRI revealed decrease in compression of the left oculomotor nerve by the cyst. His left oculomotor palsy recovered completely within a few months. Oculomotor nerve palsy can occur due to various diseases, and 3D-FIESTA MRI is useful for detection of oculomotor nerve compression, especially in the field of parasellar lesions. PMID:24501187

Yamauchi, Takahiro; Kitai, Ryuhei; Neishi, Hiroyuki; Tsunetoshi, Kenzo; Matsuda, Ken; Arishima, Hidetaka; Kodera, Toshiaki; Arai, Yoshikazu; Takeuchi, Hiroaki; Kikuta, Ken-ichiro

2014-02-01

178

Detection of Focal Cortical Dysplasia Lesions in MRI Using Textural Features  

Science.gov (United States)

Focal cortical dysplasia (FCD) is a frequent cause of medically refractory partial epilepsy. The visual identification of FCD lesions on magnetic resonance images (MRI) is a challenging task in standard radiological analysis. Quantitative image analysis which tries to assist in the diagnosis of FCD lesions is an active field of research. In this work we investigate the potential of different texture features, in order to explore to what extent they are suitable for detecting lesional tissue. As a result we can show first promising results based on segmentation and texture classification.

Loyek, Christian; Woermann, Friedrich G.; Nattkemper, Tim W.

179

Detection of Spontaneous Schwannomas by MRI in a Transgenic Murine Model of Neurofibromatosis Type 21  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Spontaneous schwannomas were detected by magnetic resonance imaging (MRI) in a transgenic murine model of neurofibromatosis type 2 (NF2) expressing a dominant mutant form of merlin under the Schwann cell-specific P0 promoter. Approximately 85% of the investigated mice showed putative tumors by 24 months of age. Specifically, 21% of the mice showed tumors in the intercostal muscles, 14% in the limb muscles, 7% in the spinal cord and spinal ganglia, 7% in the external ear, 14% in the muscle of ...

Messerli, Sm; Tang, Y.; Giovannini, M.; Bronsonx, R.; Weissleder, R.; Breakefield, Xo

2002-01-01

180

Diffusion-weighted and conventional MRI in detection of Multiple Sclerosis lesions in brain: a comparative study  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Multiple sclerosis (MS is a chronic disease that begins most commonly in young adults and is characterized pathologically by multiple areas of central nervous system (CNS white matter inflammation, demyelination, and glial scarring. The most valuable aid for diagnosis is magnetic resonance imaging (MRI. New type of MRI has been developed on the basis of molecular diffusion which capable of detecting acute and active lesions. Early diagnosis and treatment is possible to stop or slow down progression of disease. The aim of this study is to compare the findings of conventional and diffusion- weighted (DW MRI in detection cerebral lesions of MS. Methods: Thirty patients with clinically definite MS and 30 healthy volunteers were studied in a descriptive-prospective survey over a twelve-month period of time. Conventional and DW MRI were used in both groups. Total number, morphology, location and the mean size of the intra-cerebral plaques of MS were compared between group. The sensitivity and the specificity of both imaging methods in detecting these plaques were determined. Results: Thirty patients with MS with the mean age of 32.76±8.79 years and 30 healthy individuals with the mean age of 32.75± 9.23 years were enrolled. Plaque within the brain was significantly higher by the conventional method (P< 0.05. Ovoid lesions were greater in number in the conventional method group. More lesions were detected by the conventional method in the areas of periventricle, centrum semiovale and corpus callosum. Regarding the size of plaque, the minimum measurement was significantly lower in the conventional method group. The sensitivity of both methods was 100%. The specificity of conventional and DW MRI was 86.6% and 96.6%, respectively. Conclusion: In our study the sensitivity of both methods was the same but the specificity of DW MRI was higher. DW MRI may detect lesions which are not detectable by the routine methods.

"Z. Miabi

2006-07-01

 
 
 
 
181

Remote detection of gases by gas correlation spectroradiometry  

Science.gov (United States)

The present investigation is concerned with the application of a pressure modulated radiometer (PMR) to the remote sensing of trace amounts of gases in the atmospheres as well as to the direct measurement of upper atmospheric winds. The PMR operates as a gas correlation spectrometer. Compared to conventional gas correlation parameters, it has some advantages which are related to greater versatility and the employment of a simpler method for maintaining electrical/optical balance. The PMR has a high sensitivity in connection with its essentially very high effective resolution. It represents a passive system and emits no radiation. A PMR is flown on Nimbus 6 which was launched in 1975. The instrument has also been used on the Nimbus 7 satellite and the Tiros N satellite.

Margolis, J. S.; Mccleese, B. J.; Martonchik, J. V.

1983-01-01

182

Improved detection of localized prostate cancer using co-registered MRI and {sup 11}C-acetate PET/CT  

Energy Technology Data Exchange (ETDEWEB)

Objectives: We aimed to study the ability of contrast enhanced MRI at 1.5 T and {sup 11}C-acetate PET/CT, both individually and using fused data, to detect localized prostate cancer. Methods: Thirty-six men with untreated prostate cancer and negative for metastatic disease on pelvic CT and bone scan were prospectively enrolled. A pelvic {sup 11}C-acetate PET/CT scan was performed in all patients, and a contrast enhanced MRI scan in 33 patients (6 examinations using both endorectal coil and surface coils, and 27 examinations using surface coils only). After the imaging studies 10 patients underwent prostatectomy and 26 were treated by image guided external beam radiation treatment. Image fusion of co-registered PET and MRI data was performed based on anatomical landmarks visible on CT and MRI using an advanced in-house developed software package. PET/CT, MRI and fused PET/MRI data were evaluated visually and compared with biopsy findings on a lobar level, while a sextant approach was used for patients undergoing prostatectomy. Results: When using biopsy samples as method of reference, the sensitivity, specificity and accuracy for visual detection of prostate cancer on a lobar level by contrast enhanced MRI was 85%, 37%, 73% and that of {sup 11}C-acetate PET/CT 88%, 41%, 74%, respectively. Fusion of PET with MRI data increased sensitivity, specificity and accuracy to 90%, 72% and 85%, respectively. Conclusions: Fusion of sequentially obtained PET/CT and MRI data for the localization of prostate cancer is feasible and superior to the performance of each individual modality alone.

Jambor, Ivan, E-mail: ivjamb@utu.fi [Department of Diagnostic Radiology, University of Turku, Turku (Finland); 2nd Department of Radiology, Comenius University and St. Elisabeth Oncology Institute, Bratislava (Slovakia); Turku PET Centre, University of Turku, Turku (Finland); Borra, Ronald, E-mail: ronald.borra@tyks.fi [Department of Diagnostic Radiology, University of Turku, Turku (Finland); Turku PET Centre, University of Turku, Turku (Finland); Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku (Finland); Kemppainen, Jukka, E-mail: Jukka.Kemppainen@tyks.fi [Turku PET Centre, University of Turku, Turku (Finland); Department of Clinical Physiology and Nuclear Medicine, Turku University Hospital, Turku (Finland); Lepomaeki, Virva, E-mail: Virva.Lepomaki@tyks.fi [Turku PET Centre, University of Turku, Turku (Finland); Parkkola, Riitta, E-mail: Riitta.Parkkola@tyks.fi [Department of Diagnostic Radiology, University of Turku, Turku (Finland); Turku PET Centre, University of Turku, Turku (Finland); Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku (Finland); Dean, Kirsti, E-mail: Kirsti.Dean@tyks.fi [Department of Diagnostic Radiology, University of Turku, Turku (Finland); Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku (Finland); Alanen, Kalle, E-mail: Kalle.Alanen@tyks.fi [Department of Pathology, Turku University Hospital, Turku (Finland); Arponen, Eveliina, E-mail: Eveliina.Arponen@utu.fi [Turku PET Centre, University of Turku, Turku (Finland); Nurmi, Martti, E-mail: Martti.Nurmi@tyks.fi [Department of Surgery, Division of Urology, Turku University Hospital, Turku (Finland); Aronen, Hannu J., E-mail: Hannu.Aronen@tyks.fi [Department of Diagnostic Radiology, University of Turku, Turku (Finland); Medical Imaging Centre of Southwest Finland, Turku University Hospital, Turku (Finland); and others

2012-11-15

183

Improved detection of localized prostate cancer using co-registered MRI and 11C-acetate PET/CT  

International Nuclear Information System (INIS)

Objectives: We aimed to study the ability of contrast enhanced MRI at 1.5 T and 11C-acetate PET/CT, both individually and using fused data, to detect localized prostate cancer. Methods: Thirty-six men with untreated prostate cancer and negative for metastatic disease on pelvic CT and bone scan were prospectively enrolled. A pelvic 11C-acetate PET/CT scan was performed in all patients, and a contrast enhanced MRI scan in 33 patients (6 examinations using both endorectal coil and surface coils, and 27 examinations using surface coils only). After the imaging studies 10 patients underwent prostatectomy and 26 were treated by image guided external beam radiation treatment. Image fusion of co-registered PET and MRI data was performed based on anatomical landmarks visible on CT and MRI using an advanced in-house developed software package. PET/CT, MRI and fused PET/MRI data were evaluated visually and compared with biopsy findings on a lobar level, while a sextant approach was used for patients undergoing prostatectomy. Results: When using biopsy samples as method of reference, the sensitivity, specificity and accuracy for visual detection of prostate cancer on a lobar level by contrast enhanced MRI was 85%, 37%, 73% and that of 11C-acetate PET/CT 88%, 41%, 74%, respectively. Fusion of PET with MRI data increased sensitivity, specificity and accuracy to 90%, 72% and 85%, respectively. Conclusions: Fusion of sequentially obtained PET/CT and MRI data for the localization of prostate cancer is feasible and superior to the performance of each individual modality alone.

184

Remote laser detection of natural gas leakages from pipelines  

International Nuclear Information System (INIS)

A differential absorption lidar based on a tunable TEA CO2 laser emitting at 42 lines of the 'hot' 0111 - 1110 band in the range from 10.9 to 11.4 ?m is developed for detecting natural gas leakages from oil pipelines by measuring the ethane content in the atmosphere. The ethane detection sensitivity is 0.9 ppm km. The presence of methane does not distort the measurement results. The developed lidar can detect the natural gas leakage from kilometre heights at the flying velocities up to 200 km h-1 and a probe pulse repetition rate of 5 Hz. (laser applications and other topics in quantum electronics)

185

Feasibility study of contaminant detection for food with ULF-NMR/MRI system using HTS-SQUID  

Energy Technology Data Exchange (ETDEWEB)

Highlights: •Feasibility of application of ultra-low field (ULF) NMR/MRI was studied. •ULF-NMR/MRI system utilized HTS-rf-SQUID and permanent magnet of 1.1 T. •Magnetic contaminants in water were successfully detected by NMR measurements. •Non-magnetic contaminants in water were distinguished by 1D-MRI measurements. -- Abstract: We have developed an ultra-low frequency (ULF) nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) system utilizing an HTS-SQUID for an application of contaminant detection in food and drink. In the system, a permanent magnet of 1.1 T was used to pre-polarize protons in a water sample. We measured NMR signals from water samples with or without various contaminants, such as stainless steel (SUS304), aluminum, and glass balls using the system. In the case that the contaminant was the SUS304 ball, the NMR signal intensity was reduced compared to that from the sample without the contaminant due to the remnant field of the contaminant. One-dimensional (1D) MRIs of the samples were also acquired to detect non-magnetic contaminants. In the 1D MRIs, changes of the MRI spectra were detected, corresponding to positions of the contaminants. These results show that the feasibility of the system to detect various contaminants in foods.

Hatsukade, Yoshimi, E-mail: hatukade@ens.tut.ac.jp; Tsunaki, Shingo; Yamamoto, Masaaki; Abe, Takayuki; Hatta, Junichi; Tanaka, Saburo

2013-11-15

186

CLASSIFICATION OF LAND USE LAND COVER CHANGE DETECTION USING REMOTELY SENSED DATA  

Directory of Open Access Journals (Sweden)

Full Text Available Image classification is perhaps the most important part of digital image analysis. With supervised classification, the information classes of interest like land cover type image. These are called “training sites”. The image processing software system is then used to develop a statistical characterization of the reflectance foreach information class. This stage is often called “ Signature analysis” .Unsupervised classification is a method which examines a large number of unknown pixels and divides into a number of classes based on natural groupings present in the image values. Unsupervised classification is becoming increasingly popular in agencies involved in long term GIS database maintenance. The reason is thatthere are now systems that use clustering procedures that are extremely fast and require little in the nature of operational parameters. Thus it is becoming possible to train GIS analysis with only a general familiarity with remote sensing to undertake classification that meet typical map accuracy standards. With suitable ground truth accuracy assessment procedures , this tool can provide a remarkably rapid means of producing quality land cover data on a continuing basis.The profusion information of the earth surface offered by the high resolution satellite images for remote sensing applications. Using change detection methodologies to extract the target changes in the areas from high resolution images and rapidly updates geodatabase information processing.However, the traditional method of change detection are not suitable for high resolution remote sensing images. To overcome the limitations of traditional pixel-level change detection of high resolution remote sensing images, based on georeferencing and analysis method, this paper presents a clean way of multi-scaleamalgamation for the high resolution remote sensing images change detection. Experiment shows that this method has a stronger advantage than the traditional pixel-level method of high resolution remote sensing image change detection.

Y.Babykalpana

2011-04-01

187

Morphological MRI criteria improve the detection of lymph node metastases in head and neck squamous cell carcinoma: multivariate logistic regression analysis of MRI features of cervical lymph nodes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim was to evaluate whether morphological criteria in addition to the size criterion results in better diagnostic performance of MRI for the detection of cervical lymph node metastases in patients with head and neck squamous cell carcinoma (HNSCC). Two radiologists evaluated 44 consecutive patients in which lymph node characteristics were assessed with histopathological correlation as gold standard. Assessed criteria were the short axial diameter and morphological criteria such as border ...

Bondt, R. B. J.; Nelemans, P. J.; Bakers, F.; Casselman, J. W.; Peutz-kootstra, C.; Kremer, B.; Hofman, P. A. M.; Beets-tan, R. G. H.

2009-01-01

188

Regularisation in multi- and hyperspectral remote sensing change detection  

DEFF Research Database (Denmark)

Change detection methods for multi- and hypervariate data look for differences in data acquired over the same area at different points in time. These differences may be due to noise or differences in (atmospheric etc.) conditions at the two acquisition time points. To prevent a change detection method from detecting uninteresting change due to noise or arbitrary spurious differences the application of regularisation also known as penalisation is considered to be important. Two types of regularisation in change detected by the multivariate alteration detection (MAD) transformation are considered: 1) ridge regression type and smoothing operators applied to the estimated weights in the MAD transform; and 2) pre-processing (before applying the MAD transformation) by noise reducing orthogonal transformations where the number of retained transformed variables can be considered a regularisation parameter. Regularisation by the former methods smooth the weights given to the individual bands in the MAD transformation and thus it penalises weights that fluctuate wildly as a function of wavelength; regularisation by the latter methods tends to smooth in the image domain. Also, regularisation may be necessary to prevent numerical instability especially when working on hyperspectral data.

Nielsen, Allan Aasbjerg

2005-01-01

189

Improved performance of sequence search approaches in remote homology detection  

Science.gov (United States)

The protein sequence space is vast and diverse, spanning across different families. Biologically meaningful relationships exist between proteins at superfamily level. However, it is highly challenging to establish convincing relationships at the superfamily level by means of simple sequence searches. It is necessary to design a rigorous sequence search strategy to establish remote homology relationships and achieve high coverage. We have used iterative profile-based methods, along with constraints of sequence motifs, to specify search directions. We address the importance of multiple start points (queries) to achieve high coverage at protein superfamily level. We have devised strategies to employ a structural regime to search sequence space with good specificity and sensitivity. We employ two well-known sequence search methods, PSI-BLAST and PHI-BLAST, with multiple queries and multiple patterns to enhance homologue identification at the structural superfamily level. The study suggests that multiple queries improve sensitivity, while a pattern-constrained iterative sequence search becomes stringent at the initial stages, thereby driving the search in a specific direction and also achieves high coverage. This data mining approach has been applied to the entire structural superfamily database.

Joshi, Adwait Govind; Raghavender, Upadhyayula Surya; Sowdhamini, Ramanathan

2014-01-01

190

Clustering of fMRI data for activation detection using HDR models.  

Science.gov (United States)

The aim of this work is to perform parametric estimation and detection of activation in fMRI data. The proposed procedure is a segmentation algorithm where clustering is based on estimated parameters for a chosen hemodynamic response (HDR) model. These parameters are estimated for each individual voxel by performing a weighted least-squares nonlinear curve fit to its time series. The parameters are used to decide which voxels are candidates for activation. A segmentation algorithm is executed on a subset of the image voxels, selected based upon fitting parameters. Our procedure will yield activation maps constructed from possibly 2-D (i.e., multi-voxel) regions of activation as opposed to identifying voxels based on individual voxel statistical significance, followed by merging into regions. The approach is intended to reduce false detections, producing "cleaner" activation results without resorting to filtering techniques that may sacrifice spatial resolution. PMID:17272077

Rao, Ashish; Talavage, Thomas M

2004-01-01

191

Diagnostic performance of MRI for detection of intestinal fistulas in patients with complicated inflammatory bowel conditions  

International Nuclear Information System (INIS)

The diagnostic performance of magnetic resonance imaging (MRI) for detection of intestinal fistulas, other than perianal, in patients with known complicated inflammatory bowel conditions (CIBC) was investigated. Our study group consisted of 20 patients (12 women, mean age 43 years) with CIBC, including Crohn's disease (n=13), colonic diverticulitis (n=3), colitis after radiotherapy (n=3) and of postoperative origin (n=1). Eleven surgically proven enteral fistulas were known in ten (50%) of these patients, being of enterovesical (n=3), enterocolic (n=2), enteroenteral (n=2), rectovaginal (n=2), rectovaginovesical (n=1) and of entercutaneous (n=1) localisation. The other ten patients (50%), used as the control group, showed MR features of CIBC, although without any fistulous tract. Multiplanar T1- and T2-weighted sequences had been performed, including gadolinium-enhanced acquisition with fat saturation (1.5 T). MR findings were independently blindly and retrospectively reviewed by three radiologists for the presence and etiology of any fistula, as well as visualization and characterization of the fistulous tract. Results were compared with surgical findings (n=16) and clinical evolution (n=4). Interobserver agreement was calculated. Interobserver agreement kappa for fistula detection was 0.71. Overall sensitivity, specificity and accuracy for fistula detection were 78.6%, 75% and 77.2%, respectively. Sensitivity for fistula characterization was 80.6%, with visualization of the fistulous tract in all cases, whereby T1-weighted gadolinium-enhanced fat-saturated images were considered the most useful sequences. Gadolinium-enhanced MRI is a reliable and reproducible tool for detection of enteral fistulas secondary to inflammatory conditions. (orig.)

192

Diagnostic performance of MRI for detection of intestinal fistulas in patients with complicated inflammatory bowel conditions  

Energy Technology Data Exchange (ETDEWEB)

The diagnostic performance of magnetic resonance imaging (MRI) for detection of intestinal fistulas, other than perianal, in patients with known complicated inflammatory bowel conditions (CIBC) was investigated. Our study group consisted of 20 patients (12 women, mean age 43 years) with CIBC, including Crohn's disease (n=13), colonic diverticulitis (n=3), colitis after radiotherapy (n=3) and of postoperative origin (n=1). Eleven surgically proven enteral fistulas were known in ten (50%) of these patients, being of enterovesical (n=3), enterocolic (n=2), enteroenteral (n=2), rectovaginal (n=2), rectovaginovesical (n=1) and of entercutaneous (n=1) localisation. The other ten patients (50%), used as the control group, showed MR features of CIBC, although without any fistulous tract. Multiplanar T1- and T2-weighted sequences had been performed, including gadolinium-enhanced acquisition with fat saturation (1.5 T). MR findings were independently blindly and retrospectively reviewed by three radiologists for the presence and etiology of any fistula, as well as visualization and characterization of the fistulous tract. Results were compared with surgical findings (n=16) and clinical evolution (n=4). Interobserver agreement was calculated. Interobserver agreement kappa for fistula detection was 0.71. Overall sensitivity, specificity and accuracy for fistula detection were 78.6%, 75% and 77.2%, respectively. Sensitivity for fistula characterization was 80.6%, with visualization of the fistulous tract in all cases, whereby T1-weighted gadolinium-enhanced fat-saturated images were considered the most useful sequences. Gadolinium-enhanced MRI is a reliable and reproducible tool for detection of enteral fistulas secondary to inflammatory conditions. (orig.)

Schmidt, S.; Meuwly, J.Y.; Meuli, R.; Schnyder, P.; Denys, A. [Universitaire Vaudois - CHUV, Service de radiodiagnostic et radiologie interventionnelle, Centre Hospitalier, Lausanne (Switzerland); Chevallier, P. [Hopital Archet II, Imagerie Medicale, Nice (France); Bessoud, B. [Hopital Kremlin-Bicetre, Radiologie Generale, Kremlin-Bicetre (France); Felley, C. [University Hospital, CHUV, Service de Gastroenterologie, Lausanne (Switzerland)

2007-11-15

193

[Review of change detection methods using multi-temporal remotely sensed images].  

Science.gov (United States)

With the development of platforms and sensors, continuous repetition of remote sensing observation of the earth surface has been realized, and a mass of multi-source, multi-scale, multi-resolution remote sensing data has been accumulated. Those images have detailedly recorded the changing process of ground objects on the earth, which makes the long term global change research, such as change detection, based on remote sensing become possible, and greatly push forward the research on image processing and application. Although plenty of successful research has been reported, there are still enormous challenges in multi-temporal imagery change detection. A relatively complete mature theoretical system has not formed, and there is still a lack of systematic summary of research progress. Firstly, the current progress in change detection methods using multi-temporal remotely sensed imagery has been reviewed in this paper. Then, the methods are classified into three categories and summarized according to the type and amount of the input data, single-phase post-classification comparison, two-phase comparison, and time series analysis. After that, the possible existing problems in the current development of multi-temporal change detection are analyzed, and the development trend is discussed finally. PMID:24611399

Yin, Shou-Jing; Wu, Chuan-Qing; Wang, Qiao; Ma, Wan-Dong; Zhu, Li; Yao, Yan-Juan; Wang, Xue-Lei; Wu, Di

2013-12-01

194

An integrated remote sensing and GIS approach in the detection of changes in Beijing  

Science.gov (United States)

Beijing is the center of politics, economy and culture in China. In recent years, the rapid development has been taking place in the city, especially, after the successful application for 2008 Olympic Games. In order to know and control the city development it is necessary to monitor the changes. Timely and accurate change detection of the city is important for the administrant departments to promote better decision making. Given the current techniques available, remote sensing provides the most feasible approach to regional and larger scale land surface change detection. A critical step of many change detection methods is to select an appropriate threshold value to extract change information. In the paper, an adaptive determination method based on polygon area fit rate is brought forward. A method based on the integration of remote sensing and GIS is presented to analyze the change types. We apply this method in the change detection practical project of Beijing city and get good result.

Zhang, Xiaodong; Li, Deren; Gong, Jianya; Qin, Qianqing

2005-10-01

195

Detecting plant metabolic responses induced by ground shock using hyperspectral remote sensing and physiological contact measurements  

Energy Technology Data Exchange (ETDEWEB)

A series of field experiments were done to determine if ground shock could have induced physiological responses in plants and if the level of the response could be observed. The observation techniques were remote sensing techniques and direct contact physiological measurements developed by Carter for detecting pre-visual plant stress. The remote sensing technique was similar to that used by Pickles to detect what appeared to be ground shock induced plant stress above the 1993 Non Proliferation Experiment`s underground chemical explosion. The experiment was designed to provide direct plant physiological measurements and remote sensing ratio images and from the same plants at the same time. The simultaneous direct and remote sensing measurements were done to establish a ground truth dataset to compare to the results of the hyperspectral remote sensing measurements. In addition, the experiment was designed to include data on what was thought to be the most probable interfering effect, dehydration. The experimental design included investigating the relative magnitude of the shock induced stress effects compared to dehydration effects.

Pickles, W.L.; Cater, G.A.

1996-12-03

196

Progress in the Development of Practical Remote Detection of Icing Conditions  

Science.gov (United States)

The NASA Icing Remote Sensing System (NIRSS) has been under definition and development at NASA Glenn Research Center since 1997. The goal of this development activity is to produce and demonstrate the required sensing and data processing technologies required to accurately remotely detect and measure icing conditions aloft. As part of that effort NASA has teamed with NCAR to develop software to fuse data from multiple instruments into a single detected icing condition product. The multiple instrument approach utilizes a X-band vertical staring radar, a multifrequency microwave, and a lidar ceilometer. The radar data determine cloud boundaries, the radiometer determines the sub-freezing temperature heights and total liquid water content, and the ceilometer refines the lower cloud boundary. Data is post-processed with a LabVIEW program with a resultant supercooled liquid water profile and aircraft hazard depiction. Ground-based, remotely-sensed measurements and in-situ measurements from research aircraft were gathered during the international 2003-2004 Alliance Icing Research Study (AIRS II). Comparisons between the remote sensing system s fused icing product and the aircraft measurements are reviewed here. While there are areas where improvement can be made, the cases examined suggest that the fused sensor remote sensing technique appears to be a valid approach.

Reehorst, Andrew; Politovich, Marcia K.; Zednik, Stephan; Isaac, George A.; Cober, Stewart

2006-01-01

197

Value of gadolinium-enhanced MRI in detection of acute appendicitis in children and adolescents.  

Science.gov (United States)

OBJECTIVE. The aim of this study was to determine both the value of gadolinium-enhanced MRI in children with suspected acute appendicitis and the best sequences for detecting acute appendicitis, to thereby decrease imaging time. MATERIALS AND METHODS. This was a retrospective review of pediatric patients with suspected appendicitis who had undergone MRI at our institution between 2010 and 2011 after an indeterminate ultrasound examination. MRI examinations included T1-weighted unenhanced and contrast-enhanced, T2-weighted, and balanced steady-state free precession (SSFP) sequences in axial and coronal planes. Sequences were reviewed together and individually by five radiologists who were blinded to the final diagnosis. Radiologists were asked to score their confidence of appendicitis diagnosis using a 5-point scale. The diagnostic performance of each MR sequence was obtained by comparing the mean area under the curve (AUC) using receiver operating characteristic (ROC) analysis. RESULTS. A total of 49 patients with clinically suspected appendicitis were included, of whom 16 received a diagnosis of appendicitis. The mean AUCs for reviewing all sequences together, contrast-enhanced sequences alone, T2-weighted sequences alone, and balanced SSFP alone were 0.984, 0.979, 0.944, and 0.910, respectively. No significant difference was observed between reviewing all sequences together versus contrast-enhanced sequences alone (p = 0.90) and T2-weighted sequences alone (p = 0.23). A significant difference was observed between contrast-enhanced sequences and balanced SSFP (p appendicitis in the pediatric population. These findings have led to protocol modifications that have reduced imaging time. PMID:25341169

Rosines, Lucila A; Chow, Daniel S; Lampl, Brooke S; Chen, Susie; Gordon, Samantha; Mui, Leonora W; Aspelund, Gudrun; Ruzal-Shapiro, Carrie B

2014-11-01

198

Detecting network modules in fMRI time series: a weighted network analysis approach.  

Science.gov (United States)

Many network analyses of fMRI data begin by defining a set of regions, extracting the mean signal from each region and then analyzing the correlations between regions. One essential question that has not been addressed in the literature is how to best define the network neighborhoods over which a signal is combined for network analyses. Here we present a novel unsupervised method for the identification of tightly interconnected voxels, or modules, from fMRI data. This approach, weighted voxel coactivation network analysis (WVCNA), is based on a method that was originally developed to find modules of genes in gene networks. This approach differs from many of the standard network approaches in fMRI in that connections between voxels are described by a continuous measure, whereas typically voxels are considered to be either connected or not connected depending on whether the correlation between the two voxels survives a hard threshold value. Additionally, instead of simply using pairwise correlations to describe the connection between two voxels, WVCNA relies on a measure of topological overlap, which not only compares how correlated two voxels are but also the degree to which the pair of voxels is highly correlated with the same other voxels. We demonstrate the use of WVCNA to parcellate the brain into a set of modules that are reliably detected across data within the same subject and across subjects. In addition we compare WVCNA to ICA and show that the WVCNA modules have some of the same structure as the ICA components, but tend to be more spatially focused. We also demonstrate the use of some of the WVCNA network metrics for assessing a voxel's membership to a module and also how that voxel relates to other modules. Last, we illustrate how WVCNA modules can be used in a network analysis to find connections between regions of the brain and show that it produces reasonable results. PMID:20553896

Mumford, Jeanette A; Horvath, Steve; Oldham, Michael C; Langfelder, Peter; Geschwind, Daniel H; Poldrack, Russell A

2010-10-01

199

Urban area change detection procedures with remote sensing data  

Science.gov (United States)

The underlying factors affecting the detection and identification of nonurban to urban land cover change using satellite data were studied. Computer programs were developed to create a digital scene and to simulate the effect of the sensor point spread function (PSF) on the transfer of modulation from the scene to an image of the scene. The theory behind the development of a digital filter representing the PSF is given as well as an example of its application. Atmospheric effects on modulation transfer are also discussed. A user's guide and program listings are given.

Maxwell, E. L. (principal investigator); Riordan, C. J.

1980-01-01

200

Remote domain wall chirality measurement via stray field detection  

Science.gov (United States)

We have calculated magnetostatic fields from transverse and vortex magnetic domain walls in a planar Ni81Fe19 nanowire using micromagnetic simulations. Magnetic fields were calculated either side of the wire in the wire plane. Asymmetries in the stray field from the two types of domain walls can be understood in terms of monopole, dipole and quadrupole contributions. These calculations indicate the required sensitivity of a nearby sensor for domain wall detection or being able to distinguish domain wall character. We demonstrate this by modeling the electrical response of a magnetoresistive multilayer element to a domain wall in a nearby magnetic nanowire.

Bashir, M. A.; Bryan, M. T.; Allwood, D. A.; Schrefl, T.; Claydon, J. S.; Burnell, G.; Marrows, C. H.

2011-12-01

 
 
 
 
201

Computer-aided detection (CAD) for breast MRI: evaluation of efficacy at 3.0 T  

International Nuclear Information System (INIS)

The purpose of the study was to evaluate the accuracy of 3.0-T breast MRI interpretation using manual and fully automated kinetic analyses. Manual MRI interpretation was done on an Advantage Workstation. Retrospectively, all examinations were processed with a computer-aided detection (CAD) system. CAD data sets were interpreted by two experienced breast radiologists and two residents. For each lesion automated analysis of enhancement kinetics was evaluated at 50% and 100% thresholds. Forty-nine malignant and 22 benign lesions were evaluated. Using threshold enhancement alone, the sensitivity and specificity of CAD were 97.9% and 86.4%, respectively, for the 50% threshold, and 97.9% and 90%, respectively, for the 100% threshold. Manual interpretation by two breast radiologists showed a sensitivity of 84.6% and a specificity of 68.8%. For the same two radiologists the mean sensitivity and specificity for CAD-based interpretation was 90.4% (not significant) and 81.3% (significant at p < 0.05), respectively. With one-way ANOVA no significant differences were found between the two breast radiologists and the two residents together, or between any two readers separately. CAD-based analysis improved the specificity compared with manual analysis of enhancement. Automated analysis at 50% and 100% thresholds showed a high sensitivity and specificity for readers with varying levels of experience. (orig.)

202

Voxel-based analysis of MRI detects abnormal visual cortex in children and adults with amblyopia.  

Science.gov (United States)

Amblyopia, sometimes called "lazy eye," is a relatively common developmental visual disorder well characterized behaviorally; however, the neural substrates associated with amblyopia in humans remain unclear. We hypothesized that abnormalities in the cerebral cortex of subjects with amblyopia exist, possibly as a result of experience-dependent neuronal plasticity. Anatomic magnetic resonance imaging (MRI) and psychophysical vision testing was carried out on 74 subjects divided into two age ranges, 7-12 years and 18-35 years, and three diagnoses, strabismic amblyopia, anisometropic amblyopia, and normal vision. We report a behavioral impairment in contrast sensitivity for subjects with amblyopia, consistent with previous reports. When the high-resolution MRI brain images were analyzed quantitatively with optimized voxel-based morphometry, results indicated that adults and children with amblyopia have decreased gray matter volume in visual cortical regions, including the calcarine sulcus, known to contain primary visual cortex. This finding was confirmed with a separate region-of-interest analysis. For the children with amblyopia, additional gray matter reductions in parietal-occipital areas and ventral temporal cortex were detected, consistent with recent reports that amblyopia can result in spatial location and object processing deficits. These data are the first to provide possible neuroanatomic bases for the loss of binocularity and visual sensitivity in children and adults with amblyopia. PMID:15846772

Mendola, Janine D; Conner, Ian P; Roy, Anjali; Chan, Suk-Tak; Schwartz, Terry L; Odom, J Vernon; Kwong, Kenneth K

2005-06-01

203

Detection of hepatocellular carcinoma in gadoxetic acid-enhanced MRI and diffusion-weighted MRI with respect to the severity of liver cirrhosis  

Energy Technology Data Exchange (ETDEWEB)

Background As gadoxetic acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) have been widely used for the evaluation of hepatocellular carcinoma (HCC), it is clinically relevant to determine the diagnostic efficacy of gadoxetic acid-enhanced MRI and DWI for detection of HCCs with respect to the severity of liver cirrhosis. Purpose To compare the diagnostic accuracy and sensitivity of gadoxetic acid-enhanced MRI and DWI for detection of HCCs with respect to the severity of liver cirrhosis. Material and Methods A total of 189 patients with 240 HCCs ({<=}3.0 cm) (Child-Pugh A, 81 patients with 90 HCCs; Child-Pugh B, 65 patients with 85 HCCs; Child-Pugh C, 43 patients with 65 HCCs) underwent DWI and gadoxetic acid-enhanced MRI at 3.0 T. A gadoxetic acid set (dynamic and hepatobiliary phase plus T2-weighted image) and DWI set (DWI plus unenhanced MRIs) for each Child-Pugh class were analyzed independently by two observers for detecting HCCs using receiver-operating characteristic analysis. The diagnostic accuracy and sensitivity were calculated. Results There was a trend toward decreased diagnostic accuracy for gadoxetic acid and DWI set with respect to the severity of cirrhosis (Child-Pugh A [mean 0.974, 0.961], B [mean 0.904, 0.863], C [mean 0.779, 0.760]). For both observers, the sensitivities of both image sets were highest in Child-Pugh class A (mean 95.6%, 93.9%), followed by class B (mean 83.0%, 77.1%), and class C (mean 60.6%, 60.0%) (P < 0.05). Conclusion In HCC detection, the diagnostic accuracy and sensitivity for gadoxetic acid-enhanced MRI and DWI were highest in Child-Pugh class A, followed by Child-Pugh class B, and Child-Pugh class C, indicating a tendency toward decreased diagnostic capability with the severity of cirrhosis.

Kim, Ah Yeong; Kim, Young Kon; Lee, Min Woo; Park, Min Jung; Hwang, Jiyoung; Lee, Mi Hee; Lee, Jae Won [Dept. of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan Univ. School of Medicine, Seoul (Korea, Republic of)], e-mail: jmyr@dreamwiz.com

2012-10-15

204

Detection of rheumatoid arthritis bone erosions by 2 different dedicated extremity MRI units and conventional radiography.  

DEFF Research Database (Denmark)

OBJECTIVES: To compare the ability of 2 different dedicated extremity magnetic resonance imaging (E-MRI) units and conventional radiography (CR) for identifying bone erosions in rheumatoid arthritis (RA) metacarpophalangeal (MCP) and wrist joints. METHODS: CR and 2 MRI-examinations (on 0.2T Esaote Artoscan and 0.2T portable MagneVu MV1000 units) of 418 bones in the dominant wrist and 2.-5. MCP-joints of 15 RA patients and 4 healthy controls were performed and blindedly evaluated for bones being visible and for erosions. RESULTS: In MCP-joints, MagneVu visualized 18.5% of bones entirely and 71.1% were 67-99% visualized. In wrists, MagneVu visualized 1.5% of bones entirely, 39.8% were 67-99% visualized and 19% were not visualized at all. Artoscan and CR visualized all bones entirely. Artoscan/MagneVu/CR found 22/19/15 bones with erosions in MCP-joints and 66/40/13 in wrist joints. With the previously validated Artoscan-unit as standard reference, MagneVu and CR had sensitivities of 0.82 and 0.55, respectively, in MCP-joint bones and 0.41 and 0.14 in wrist bones. Specificities of CR and MagneVu were comparable (0.82-0.99). MagneVu was particularly more sensitive than CR in metacarpal heads and carpal bones. MagneVu and CR detected 100% and 89%, respectively, of large erosions (OMERACT-RAMRIS-score > 1 on Artoscan) in MCP-joints, and 69% and 15.8% of large erosions in wrists. CONCLUSIONS: Both E-MRI units detected more erosions than CR, particularly due to a higher sensitivity in metacarpal heads and carpal bones. The MagneVu detected fewer erosions than the Artoscan, due to a lower average image quality and a smaller proportion of bones being visualized. Udgivelsesdato: 2007-Nov-16

Duer, Anne; Vestergaard, Aage

2008-01-01

205

Evaluation of selected edge detection techniques in remotely sensing images  

Science.gov (United States)

This paper describes the experience gained from the evaluation of selected automatic edge detection techniques applied to LANDSAT TM, SPOT HRV, IRS 1C and IKONOS images. Emphasis was given to the detection of man-made objects and linear features such as coastlines, roads and parcel boundaries in combination with selected preprocessing and postprocessing operations. As preprocessing Gaussian, adaptive and morphological operators were implemented and tested for image enhancement and smoothing. Edge extraction processing followed. First the Canny edge detector was applied. Then a morphological nonlinear Laplacian operator was applied and its zero-crossings yielded edge locations. Finally an edge detector resulting by overlaying two thresholded images from the Prewitt gradient, preserving edges appearing in both images, was applied. Postprocessing followed to eliminate noisy edges and restore edge connectivity through morphological operators. An analysis of the relative performance of the processing scheme indicated each detector's relation to noise (features at certain undesired scales, shadows along roads boundaries, irrelevant edges within parcel boundaries) and the set of specific parameters needed for proper enhancement and smoothing before edge extraction.

Karantzalos, Konstantinos G.; Argialas, Demetre P.

2003-03-01

206

Incident and Traffic-Bottleneck Detection Algorithm in High-Resolution Remote Sensing Imagery  

Directory of Open Access Journals (Sweden)

Full Text Available One of the most important methods to solve traffic congestion is to detect the incident state of a roadway. This paper describes the development of a method for road traffic monitoring aimed at the acquisition and analysis of remote sensing imagery. We propose a strategy for road extraction, vehicle detection and incident detection from remote sensing imagery using techniques based on neural networks, Radon transform for angle detection and traffic-flow measurements. Traffic-bottleneck detection is another method that is proposed for recognizing incidents in both offline and real-time mode. Traffic flows and incidents are extracted from aerial images of bottleneck zones. The results show that the proposed approach has a reasonable detection performance compared to other methods. The best performance of the learning system was a detection rate of 87% and a false alarm rate of less than 18% on 45 aerial images of roadways. The performance of the traffic-bottleneck detection method had a detection rate of 87.5%.

S.M.M. Kahaki

2012-09-01

207

Detection of intraductal component around invasive breast cancer using ultrasound. Correlation with MRI and histopathological findings  

International Nuclear Information System (INIS)

and 50.0%, 89.5% and 65.9% for MRI, respectively. When both US and MRI results were combined, sensitivity, specificity, and accuracy were 75.0%, 84.2%, and 78.7%. Current US examination depicted the intraductal component of breast cancer more accurately than MRI. Further, our study suggests that the use of both US and MRI together is complementary and offers more advantage than US alone. (author)

208

Characterization of in vivo MRI detectable thalamic amyloid plaques from APP/PS1 mice  

International Nuclear Information System (INIS)

Amyloid deposits are one of the hallmarks of Alzheimer's disease. Recent studies, in transgenic mice modeling Alzheimer's disease showed that, using in vivo, contrast agent-free, MRI, thalamic amyloid plaques are more easily detected than other plaques of the brain. Our study evaluated the characteristics of these thalamic plaques in a large population of APP/PS1, PS1 and C57BL/6 mice. Thalamic spots were detected in all mice but with different frequency and magnitude. Hence, the prevalence and size of the lesions were higher in APP/PS1 mice. However, even in APP/PS1 mice, thalamic spots did not occur in all the old animals. In APP/PS1 mice, spots detection was related to high iron and calcium load within amyloid plaques and thus reflects the ability of such plaque to capture large amounts of minerals. Interestingly, calcium and iron was also detected in extra-thalamic plaques but with a lower intensity. Hypointense lesions in the thalamus were not associated with the iron load in the tissue surrounding the plaques, nor with micro-hemorrhages, inflammation, or a neuro-degenerative context. (authors)

209

Characterization of in vivo MRI detectable thalamic amyloid plaques from APP/PS1 mice  

Energy Technology Data Exchange (ETDEWEB)

Amyloid deposits are one of the hallmarks of Alzheimer's disease. Recent studies, in transgenic mice modeling Alzheimer's disease showed that, using in vivo, contrast agent-free, MRI, thalamic amyloid plaques are more easily detected than other plaques of the brain. Our study evaluated the characteristics of these thalamic plaques in a large population of APP/PS1, PS1 and C57BL/6 mice. Thalamic spots were detected in all mice but with different frequency and magnitude. Hence, the prevalence and size of the lesions were higher in APP/PS1 mice. However, even in APP/PS1 mice, thalamic spots did not occur in all the old animals. In APP/PS1 mice, spots detection was related to high iron and calcium load within amyloid plaques and thus reflects the ability of such plaque to capture large amounts of minerals. Interestingly, calcium and iron was also detected in extra-thalamic plaques but with a lower intensity. Hypointense lesions in the thalamus were not associated with the iron load in the tissue surrounding the plaques, nor with micro-hemorrhages, inflammation, or a neuro-degenerative context. (authors)

Dhenain, M. [URA CEA CNRS 2210, I2BM, SHFJ, 4 Place du General Leclerc, 91401 Orsay Cedex (France); Dhenain, M.; El Tannir El Tayara, N.; Wu, T.D.; Volk, A.; Quintana, C. [U759 INSERM, Centre Universitaire, Laboratoire 112, 91405 Orsay Cedex (France); Dhenain, M.; El Tannir El Tayara, N.; Wu, T.D.; Volk, A.; Quintana, C. [Institut Curie, Centre Universitaire, Laboratoire 112, 91405 Orsay Cedex (France); Guegan, M.; Delatour, B. [Instituto de Microelectronica de Madrid-CSIC, 8, Isaac Newton, 28760 Tres Cantos, Madrid (Spain)

2009-07-01

210

Non-contact biopotential sensor for remote human detection  

Energy Technology Data Exchange (ETDEWEB)

This paper describes a new low-cost, low-noise displacement current sensor developed for non-contact measurements of human biopotentials and well suited for detection of human presence applications. The sensor employs a simple, improvised transimpedance amplifier that eliminates the need for ultra high values resistors normally needed in current amplifiers required for this type of measurements. The sensor provides an operational bandwidth of 0.5 - 250 Hz, and a noise level of 7.8{mu}V{radical}Hz at 1 Hz down to 30nV/{radical}Hz at 1 kHz. Reported experimental results demonstrate the sensor's capability in measuring heart related biopotentials within 0.5m off-body distance, and muscle related biopotentials within 10m no obstacles off-body distance, and 5m off-body distance with a concrete wall in between.

Mahdi, A E [Department of Electronic and Computer Engineering, University of Limerick, Limerick (Ireland); Faggion, L, E-mail: hussain.mahdi@ul.ie, E-mail: lorenzo.faggion@jrc.ec.europa.eu [Joint Research Centre of the European Commission, Institute for the Protection and Safety of the Citizen, Ispra (Italy)

2011-08-17

211

Change Detection and Dynamic Analysis Based on Remote Sensing Images  

Science.gov (United States)

A radar uses the time elapsed between the transmission and reception of an electromagnetic waveform to locate targets present in the illuminated area. Different objects will reflect the radiation with different intensities and phase. The signal provided by standard radar is a profile of the intensity backscattered from the scene as a function of the distance. The resolution, i.e. the capability to distinguish different targets, is related to instrumental parameters and, for conventional radar, is in the range of tens of centimetres. The elementary sampling volume of a radar measurement is usually called radar bin. A radar image can be obtained when an azimuth and a range resolution is available, and this can be attained in different ways: performing a mechanical scanning of the antenna, the most familiar mode used for surveillance, meteorological radar etc, or modifying its spatial features by changing the characteristics of the radiated signal or finally through a specific processing of the acquired data, as in the case of Synthetic Aperture Radar (SAR). In this paper only 1D data without any cross range resolution are used. The vibration of a target corresponds to a small and rapid variation of the radar-target distance to which the phase of the received signal is related. Coherent radar is able to provide measurements of the phase variation along time exploiting the interferometric technique. The received radar signals permits to retrieve distance variations of the observed objects in the order of small fractions of the transmitted wavelength, by comparing the phase of signals acquired at different times. Use a short span bridge as a test-bed this study investigates the actual capability of a Real Aperture Radar (RAR) interferometer to detect the natural vibration caused by wind or pass pedestrians. It is found that RAR can pick up bridge displacements of a few tens of ?m and detect a wide range of vibrations.

Luzi, G.; Crosetto, M.; Devanthéry, N.; Cuevas, M.; Meng, X.

2013-08-01

212

Joint Change Detection and Image Registration for Optical Remote Sensing Images  

Directory of Open Access Journals (Sweden)

Full Text Available In this letter, a novel method is proposed for jointly unsupervised change detection and image registration over multi-temporal optical remote sensing images. An iterative energy minimization scheme is employed to extract the pixel opacity. Specifically, we extract the consistent points which provide the initial seed nodes and the feature nodes for random walker image segmentation and image registration, respectively. And the seed nodes will be updated according to the analysis of the changed and unchanged regions. Experimental results demonstrate that the proposed method can perform change detection as well as the state of the art methods. In particular, it can perform change detection rapidly and automatically over unregistered optical remote sensing images.

Wang Luo

2012-03-01

213

AIRBORNE, OPTICAL REMOTE SENSNG OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION  

Energy Technology Data Exchange (ETDEWEB)

Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. The scope of the work involved designing and developing an airborne, optical remote sensor capable of sensing methane and, if possible, ethane for the detection of natural gas pipeline leaks. Flight testing using a custom dual wavelength, high power fiber amplifier was initiated in February 2005. Ophir successfully demonstrated the airborne system, showing that it was capable of discerning small amounts of methane from a simulated pipeline leak. Leak rates as low as 150 standard cubic feet per hour (scf/h) were detected by the airborne sensor.

Jerry Myers

2005-04-15

214

RoboHound:developing sample collection and preconcentration hardware for a remote trace explosives detection system.  

Energy Technology Data Exchange (ETDEWEB)

The RoboHound{trademark} Project was a three-year, multiphase project at Sandia National Laboratories to build and refine a working prototype trace explosive detection system as a tool for a commercial robot. The RoboHound system was envisioned to be a tool for emergency responders to test suspicious items (i.e., packages or vehicles) for explosives while maintaining a safe distance. The project investigated combining Sandia's expertise in trace explosives detection with a wheeled robotic platform that could be programmed to interrogate suspicious items remotely for the presence of explosives. All of the RoboHound field tests were successful, especially with regards to the ability to collect and detect trace samples of RDX. The project has gone from remote sampling with human intervention to a fully automatic system that requires no human intervention until the robot returns from a sortie. A proposal is being made for additional work leading towards commercialization.

Peterson, David J. (New Mexico Tech, Socorro, NM); Denning, David J.; Hobart, Clinton G.; Lenz, Michael C.; Anderson, Robert J.; Carlson, Dennis L.; Hunter, John Anthony; Gladwell, T. Scott; Mitchell, Mary-Anne; Hannum, David W.; Baumann, Mark J.

2005-09-01

215

Passive remote detection in a combustion system with a tunable heterodyne receiver: application to sulfur dioxide  

International Nuclear Information System (INIS)

Here is presented the possibility of remote detection of sulfur dioxide in a combustion chamber. It is of major interest as part of the program of global pollution reduction. The remote detection of combustion products in the middle infrared region can be very useful for engine diagnostics or industrial pollution control. We used a tunable diode laser heterodyne receiver working in the middle infrared. Such an apparatus is able to perform passive emission spectroscopy on distant sources. It is a very sensitive and selective technique for radiation detection able to extract weak signals from the background. To validate our prototype and demonstrate its efficiency, we recorded high-temperature sulfur dioxide emission spectra around 1336 cm-1 (?3 ro-vibrational band), in the case of a polluted CH4/air flame

216

Study on Method of Geohazard Change Detection Based on Integrating Remote Sensing and GIS  

Science.gov (United States)

Following a comprehensive literature review, this paper looks at analysis of geohazard using remote sensing information. This paper compares the basic types and methods of change detection, explores the basic principle of common methods and makes an respective analysis of the characteristics and shortcomings of the commonly used methods in the application of geohazard. Using the earthquake in JieGu as a case study, this paper proposes a geohazard change detection method integrating RS and GIS. When detecting the pre-earthquake and post-earthquake remote sensing images at different phases, it is crucial to set an appropriate threshold. The method adopts a self-adapting determination algorithm for threshold. We select a training region which is obtained after pixel information comparison and set a threshold value. The threshold value separates the changed pixel maximum. Then we apply the threshold value to the entire image, which could also make change detection accuracy maximum. Finally, we output the result to the GIS system to make change analysis. The experimental results show that this method of geohazard change detection based on integrating remote sensing and GIS information has higher accuracy with obvious advantages compared with the traditional methods.

Zhao, Zhenzhen; Yan, Qin; Liu, Zhengjun; Luo, Chengfeng

2014-03-01

217

MnDPDP-enhanced MRI vs dual-phase spiral CT in the detection of hepatocellular carcinoma in cirrhosis  

Energy Technology Data Exchange (ETDEWEB)

The objectives of this study were twofold: (a) to assess safety and tolerability of the hepatobiliary MR contrast agent MnDPDP; and (b) to investigate the sensitivity of MnDPDP-enhanced MRI, in comparison with dual-phase spiral CT, in the detection of hepatocellular carcinoma (HCC) in cirrhosis. Fifty patients with liver cirrhosis and histologically proven HCC were enrolled in a prospective phase-IIIB clinical trial. All patients underwent evaluation with dual-phase spiral CT and pre-contrast and post-contrast MRI at 1.5 T. The MR examination protocol included spin-echo (SE) and gradient-recalled-echo (GRE) T1-weighted images acquired before and 60-120 min after administration of 0.5 {mu}mol/kg (0.5 ml/kg) MnDPDP (Teslascan, Nycomed Amersham, Oslo, Norway); and fast T2-weighted SE images obtained solely before contrast injection. Gold standard was provided by findings at Lipiodol CT in combination with follow-up spiral CT studies, which were repeated at 4-month intervals over a 10- to 27-month (mean {+-} SD 20.1 {+-} 5.1 months) follow-up period. No serious adverse event occurred. Eighty tumors ranging 0.8-9.1 cm in diameter (mean {+-} SD 3.2 {+-} 2.4 cm) were detected by Lipiodol CT or confirmed as cancerous foci by follow-up CT studies. Pre-contrast MRI detected 38 of 80 lesions (48 %); MnDPDP-enhanced MRI, 65 of 80 lesions (81 %); pre-contrast plus post-contrast MRI, 69 of 80 lesions (86 %); and dual-phase spiral CT, 64 of 80 lesions (80 %). The difference between unenhanced and MnDPDP-enhanced MRI was statistically significant (p < 0.001). The difference between MRI (pre-contrast plus post-contrast) and dual-phase spiral CT was not statistically significant (p = 0.33). The confidence in the final diagnosis, however, was significantly higher for MRI as compared with spiral CT (p < 0.001). MnDPDP is a safe and well-tolerated hepatobiliary MR contrast agent. Magnetic resonance imaging with use of MnDPDP is significantly more sensitive than unenhanced MRI and as good as dual-phase spiral CT for detection of HCC in cirrhosis. (orig.)

Bartolozzi, C.; Donati, F.; Cioni, D.; Crocetti, L.; Lencioni, R. [Pisa Univ. (Italy). Dept. of Oncology

2000-11-01

218

MnDPDP-enhanced MRI vs dual-phase spiral CT in the detection of hepatocellular carcinoma in cirrhosis  

International Nuclear Information System (INIS)

The objectives of this study were twofold: (a) to assess safety and tolerability of the hepatobiliary MR contrast agent MnDPDP; and (b) to investigate the sensitivity of MnDPDP-enhanced MRI, in comparison with dual-phase spiral CT, in the detection of hepatocellular carcinoma (HCC) in cirrhosis. Fifty patients with liver cirrhosis and histologically proven HCC were enrolled in a prospective phase-IIIB clinical trial. All patients underwent evaluation with dual-phase spiral CT and pre-contrast and post-contrast MRI at 1.5 T. The MR examination protocol included spin-echo (SE) and gradient-recalled-echo (GRE) T1-weighted images acquired before and 60-120 min after administration of 0.5 ?mol/kg (0.5 ml/kg) MnDPDP (Teslascan, Nycomed Amersham, Oslo, Norway); and fast T2-weighted SE images obtained solely before contrast injection. Gold standard was provided by findings at Lipiodol CT in combination with follow-up spiral CT studies, which were repeated at 4-month intervals over a 10- to 27-month (mean ± SD 20.1 ± 5.1 months) follow-up period. No serious adverse event occurred. Eighty tumors ranging 0.8-9.1 cm in diameter (mean ± SD 3.2 ± 2.4 cm) were detected by Lipiodol CT or confirmed as cancerous foci by follow-up CT studies. Pre-contrast MRI detected 38 of 80 lesions (48 %); MnDPDP-enhanced MRI, 65 of 80 lesions (81 %); pre-contrast plus post-contrast MRI, 69 of 80 lesions (86 %); and dual-phase spiral CT, 64 of 80 lesions (80 %). The difference between unenhanced and MnDPDP-enhanced MRI was statistically significant (p < 0.001). The difference between MRI (pre-contrast plus post-contrast) and dual-phase spiral CT was not statistically significant (p = 0.33). The confidence in the final diagnosis, however, was significantly higher for MRI as compared with spiral CT (p < 0.001). MnDPDP is a safe and well-tolerated hepatobiliary MR contrast agent. Magnetic resonance imaging with use of MnDPDP is significantly more sensitive than unenhanced MRI and as good as dual-phase spiral CT for detection of HCC in cirrhosis. (orig.)

219

Can Remote Sensing Detect Aquifer Characteristics?: A Case Study in the Guarani Aquifer System  

Science.gov (United States)

Global water supply resiliency depends on groundwater, especially regions threatened by population growth and climate change. Aquifer characteristics, even as basic as confined versus unconfined, are necessary to prescribe regulations to sustainably manage groundwater supplies. A significant barrier to sustainable groundwater management exists in the difficulties associated with mapping groundwater resources and characteristics at a large spatial scale. This study addresses this challenge by investigating if remote sensing, including with NASA's Gravity Recovery and Climate Experiment (GRACE), can detect and quantify key aquifer parameters and characteristics. We explore this through a case study in the Guarani Aquifer System (GAS) of South America, validating our remote sensing-based findings against the best available regional estimates. The use of remote sensing to advance the understanding of large aquifers is beneficial to sustainable groundwater management, especially in a trans-boundary system, where consistent information exchange can occur within hydrologic boundaries instead of political boundaries.

Richey, A. S.; Thomas, B.; Famiglietti, J. S.

2013-12-01

220

Comparison of gadolinium-EOB-DTPA-enhanced and diffusion-weighted liver MRI for detection of small hepatic metastases  

Energy Technology Data Exchange (ETDEWEB)

To compare the accuracy of gadolinium ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI with that of diffusion-weighted MRI (DWI) in the detection of small hepatic metastases (2 cm or smaller). Forty-five patients underwent abdominal MRI at 3 T, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), heavily T2WI (HASTE), DWI with a b-value of 500 s/mm{sup 2} and contrast-enhanced MRI with Gd-EOB-DTPA. Two groups were assigned and compared: group A (T1WI, T2WI, HASTE and contrast-enhanced study with Gd-EOB-DTPA), and group B (T1WI, T2WI, HASTE and DWI). Two observers independently interpreted the images obtained in a random order. For all hepatic metastases, the diagnostic performance using each imaging set was evaluated by receiver-operating characteristic (ROC) curve analysis. A total of 51 hepatic metastases were confirmed. The area under the ROC curve (Az) of group A was larger than that of group B, and the difference in the mean Az values between the two image sets was statistically significant, whereas, there were three metastases that lay near thin vessels or among multiple cysts and were better visualised in group B than in group A. Gd-EOB-DTPA-enhanced MRI showed higher accuracy in the detection of small metastases than DWI. (orig.)

Shimada, Kotaro; Isoda, Hiroyoshi; Hirokawa, Yuusuke; Arizono, Shigeki; Shibata, Toshiya; Togashi, Kaori [Kyoto University Graduate School of Medicine, Department of Diagnostic Imaging and Nuclear Medicine, Kyoto (Japan)

2010-11-15

 
 
 
 
221

Comparison of gadolinium-EOB-DTPA-enhanced and diffusion-weighted liver MRI for detection of small hepatic metastases  

International Nuclear Information System (INIS)

To compare the accuracy of gadolinium ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI with that of diffusion-weighted MRI (DWI) in the detection of small hepatic metastases (2 cm or smaller). Forty-five patients underwent abdominal MRI at 3 T, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), heavily T2WI (HASTE), DWI with a b-value of 500 s/mm2 and contrast-enhanced MRI with Gd-EOB-DTPA. Two groups were assigned and compared: group A (T1WI, T2WI, HASTE and contrast-enhanced study with Gd-EOB-DTPA), and group B (T1WI, T2WI, HASTE and DWI). Two observers independently interpreted the images obtained in a random order. For all hepatic metastases, the diagnostic performance using each imaging set was evaluated by receiver-operating characteristic (ROC) curve analysis. A total of 51 hepatic metastases were confirmed. The area under the ROC curve (Az) of group A was larger than that of group B, and the difference in the mean Az values between the two image sets was statistically significant, whereas, there were three metastases that lay near thin vessels or among multiple cysts and were better visualised in group B than in group A. Gd-EOB-DTPA-enhanced MRI showed higher accuracy in the detection of small metastases than DWI. (orig.)

222

Optical detection system for multispectral UV fluorescence laser remote sensing measurements  

Energy Technology Data Exchange (ETDEWEB)

A mobile laser remote sensing system is being developed for multispectral UV fluorescence detection of vapor, liquid, and solid effluents. TM system uses laser wavelengths between 250 and 400 nm to excite UV fluorescence spectra that can be used to detect and identify species in multicomponent chemical mixtures. With a scanning mirror assembly, the system is designed to map chemical concentrations with a range resolution of {approximately}5 m. In this paper we describe the optical detection system (scanning mirror assembly, 76 cm diameter collection telescope, relay optics, spectrometers, and detectors) associated data acquisition and control electronics. We also describe unique diagnostic software that is used for instrument setup and control.

Tisone, G.C.; Clark, B.; Wakefield-Reyes, C.; Hargis, P.H. Jr.; Michie, B.; Downey, T.L.; Mills, R.A.

1994-05-25

223

Joint estimation of shape and deformation for the detection of lesions in dynamic contrast-enhanced breast MRI  

International Nuclear Information System (INIS)

ffectiveness of the developed algorithm has been demonstrated on a number of clinical DCE breast MRI data in the application of breast lesion detection and the results show its potential to improve the accuracy and the efficiency in the diagnosis of breast cancer. (paper)

224

Automatic Cloud Detection and Removal Algorithm for MODIS Remote Sensing Imagery  

Directory of Open Access Journals (Sweden)

Full Text Available Cloud is one of the most common interferers in Moderate Resolution Imaging Spectrum-radiometer (MODIS remote sensing imagery. Because of cloud interference, much important and useful information covered by cloud cannot be recovered well. How to detect and remove cloud from MODIS imagery is an important issue for wide application of remote sensing data. In general, cloud can be roughly divided into two types, namely, thin cloud and thick cloud. In order to effectively detect and eliminate cloud, an automatic algorithm of cloud detection and removal is proposed in this paper. Firstly, several necessary preprocessing works need to be done for MODIS L1B data, including geometric precision correction, bowtie effect elimination and stripe noise removal. Furthermore, through analyzing the cloud spectral characters derived from the thirty-six bands of MODIS data, it can be found the spectral reflections of ground and cloud are different in various MODIS bands. Hence, cloud and ground can be respectively identified based on the analysis of multispectral characters derived from MODIS imagery. Cloud removal processing mainly aims at cloud region rather than whole image, which can improve processing efficiency. As for thin cloud and thick cloud regions, the corresponding cloud removal algorithms are proposed in this paper. Experimental results demonstrate that the proposed algorithms can effectively detect and remove cloud from MODIS imagery, which can meet the demands of post-processing of remote sensing imagery.

Lingjia Gu

2011-07-01

225

An investigation of the white matter microstructure in motion detection using diffusion MRI.  

Science.gov (United States)

One of the most widely investigated functions of the brain is vision. Whereas special attention is often paid to motion detection and its modulation by attention, comparatively still little is known about the structural background of this function. We therefore, examined the white matter microstructural background of coherent motion detection. A random-dot kinematogram paradigm was used to measure the sensitivity of healthy individuals? to movement coherence. The potential correlation was investigated between the motion detection threshold and the white matter microstructure as measured by high angular resolution diffusion MRI. The Track Based Spatial Statistics method was used to address this correlation and probabilistic tractography to reveal the connection between identified regions. A significant positive correlation was found between the behavioural data and the local fractional anisotropy in the posterior part of the right superior frontal gyrus, the right juxta-cortical superior parietal lobule, the left parietal white matter, the left superior temporal gyrus and the left optic radiation. Probabilistic tractography identified pathways that are highly similar to the segregated attention networks, which have a crucial role in the paradigm. This study draws attention to the structural determinant of a behavioural function. PMID:24833063

Csete, Gerg?; Szabó, Nikoletta; Rokszin, Alice; Tóth, Eszter; Braunitzer, Gábor; Benedek, György; Vécsei, László; Kincses, Zsigmond Tamás

2014-06-27

226

Development of CAD System Based on Enhanced Clustering Based Segmentation Algorithm for Detection of Masses in Breast DCE-MRI  

Directory of Open Access Journals (Sweden)

Full Text Available Breast cancer continues to be a significant public health problem in the world. Early detection is the key for improving breast cancer prognosis. Mammography is currently the primary method of early detection. But recent research has shown that many cases missed by mammography can be detected in Breast DCE-MRI. Magnetic Resonance (MR imaging is emerging as the most sensitive modality that is currently available for the detection of primary or recurrent breast cancer. Breast DCE-MRI is more effective than mammography, because it generates much more data. Magnetic resonance imaging (MRI is emerging as a powerful tool for the diagnosis of breast abnormalities. Computer Aided Detection (CAD is of great help to this situation and image segmentation is most important process of computer Aided Detection, Magnetic Resonance Imaging data are a major challenge to any image processing software because of the huge amount of image voxels. Automatic approaches to breast cancer detection can help radiologists in this hard task and speed up the inspection process. To segment the mass of the breast region from 3D MRI set, a multistage image processing procedure was proposed. Data acquisition, processing and visualization techniques facilitate diagnosis. Image segmentation is an established necessity for an improved analysis of Magnetic Resonance (MR images. Segmentation from MR images may aid in tumor treatment by tracking the progress of tumor growth and shrinkage. The advantages of Magnetic Resonance Imaging are that the spatial resolution is high and provides detailed images. The tumor segmentation in Breast MRI image is difficult due to the complicated galactophore structure. The work in this paper attempts to accurately segment the abnormal breast mass in DCE-MRI Images. The mass is segmented using a novel clustering algorithm based on unsupervised segmentation, through neural network techniques, of an optimized space in which to perform clustering. The effectiveness of the proposed technique is determined by the extent to which potential abnormalities can be extracted from corresponding breast MRI based on its analysis, this algorithm also proposes changes that could reduce this error, and help to give good results all around. Tests performed on both real and simulated MR images shows good result.

D. Janaki Sathya

2011-09-01

227

BP fusion model for the detection of oil spills on the sea by remote sensing  

Science.gov (United States)

Oil spills are very serious marine pollution in many countries. In order to detect and identify the oil-spilled on the sea by remote sensor, scientists have to conduct a research work on the remote sensing image. As to the detection of oil spills on the sea, edge detection is an important technology in image processing. There are many algorithms of edge detection developed for image processing. These edge detection algorithms always have their own advantages and disadvantages in the image processing. Based on the primary requirements of edge detection of the oil spills" image on the sea, computation time and detection accuracy, we developed a fusion model. The model employed a BP neural net to fuse the detection results of simple operators. The reason we selected BP neural net as the fusion technology is that the relation between simple operators" result of edge gray level and the image"s true edge gray level is nonlinear, while BP neural net is good at solving the nonlinear identification problem. Therefore in this paper we trained a BP neural net by some oil spill images, then applied the BP fusion model on the edge detection of other oil spill images and obtained a good result. In this paper the detection result of some gradient operators and Laplacian operator are also compared with the result of BP fusion model to analysis the fusion effect. At last the paper pointed out that the fusion model has higher accuracy and higher speed in the processing oil spill image"s edge detection.

Chen, Weiwei; An, Jubai; Zhang, Hande; Lin, Bin

2003-06-01

228

Detection of understory bamboo in giant panda habitats using an indirect remote sensing approach  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The bamboo is the exclusive food of the wild giant pandas. Detection of the bamboo forest in giant panda habitat will help scientists further understand the spatial distribution pattern of giant pandas and their habitats. Moreover, it provides crucial scientific evidence for estimating habitat suitability, the level of habitat fragmentation as well as its ecological carrying capacity for pandas. However, it is a big challenge to map bamboo forests using direct remote sensing approach as most ...

Bian, B. M.; Wang, T.; Liu, Y. F.; Fei, T.; Skidmore, A. K.

2007-01-01

229

Detecting functional connectivity change points for single-subject fMRI data  

Directory of Open Access Journals (Sweden)

Full Text Available Recently in functional magnetic resonance imaging (fMRI studies there has been an increased interest in understanding the dynamic manner in which brain regions communicate with one another, as subjects perform a set of experimental tasks or as their psychological state changes. Dynamic Connectivity Regression (DCR is a data-driven technique used for detecting temporal change points in functional connectivity between brain regions where the number and location of the change points are unknown a priori. After finding the change points, DCR estimates a graph or set of relationships between the brain regions for data that falls between pairs of change points. In previous work, the method was predominantly validated using multi-subject data. In this paper, we concentrate on single-subject data and introduce a new DCR algorithm. The new algorithm increases accuracy for individual subject data with a small number of observations and reduces the number of false positives in the estimated undirected graphs. We also introduce a new Likelihood Ratio test for comparing sparse graphs across (or within subjects; thus allowing us to determine whether data should be combined across subjects. We perform an extensive simulation analysis on vector autoregression (VAR data as well as to an fMRI data set from a study (n=23 of a state anxiety induction using a socially evaluative threat challenge. The focus on single-subject data allows us to study the variation between individuals and may provide us with a deeper knowledge of the workings of the brain.

IvorCribben

2013-10-01

230

Introducing a new definition towards clinical detection of Microvascular changes using diffusion and perfusion MRI  

International Nuclear Information System (INIS)

Based on MRI diffusion's and perfusion, a new criterion for detection and the healing progress of damaged tissue is suggested. The study is based on the ratio of capillary radii in symmetrical damaged and normal tissue neighboring spaces. The apparent diffusion coefficient and cerebral blood flow were measured in the brain tissues of six male wistar rats utilizing suggested MRI measurement techniques. The apparent diffusion coefficient values of damaged and normal regions were (392±34.1) x10-6 mm2s-1 and (659±40.7)x10-6 mm2s-1, respectively. The cerebral blood flow values of damaged and normal regions were 14.5±10.13 mi/min/100 g and 125±41.03 mi/min/100 g, respectively. The geometrical parameters of the capillary for damaged and normal regions midle root/? ?, where midle root is the mean radius and ? is the mean capillary segment length , were calculated to be 5.45±2.01mm0.5g-0.5 (mean±Sd) and 12.8±2.04 mm0.5g-0.5, respectively. Furthermore, based on constant ?, the damaged, versus normal region, mean radius, was shown to follow the criterionmidle root Damaged?0.13xmidle root Normal. A further analysis was conducted through suitable theoretical modeling and assumptions for the above-mentioned criterion. The analysis showed a distinct difference between normal and damaged tissues in various healing progress conditions. Moreover, a new image, namely, Diffusion/Flow map (DF map), which is a mere division of the ADC map to the cerebral blood flow map, was introduced and utilized to contrast between normal and damaged tissue

231

SQUID-detected microtesla MRI: a new modality for tumor detection?  

Science.gov (United States)

We are investigating the use of low-field magnetic resonance imaging with enhanced longitudinal-relaxation-time (T1)-weighted contrast to detect tumors. Our technique involves prepolarizing the sample in a magnetic field up to 0.3 T and detecting the nuclear magnetic resonance (NMR) signal at microtesla fields using a superconducting quantum interference device. This technique enables us to obtain T1 dispersion curves and T1-weighted contrast images in fields from 1.4 ?T to 0.3 T. We have shown that for materials such as agarose gel the T1-weighted contrast is greatly enhanced in microtesla fields. To investigate the use of this enhancement for tumor imaging we measured the T1 relaxation times of healthy and cancerous tissue specimens, maintained at 4 C, shortly after their surgical removal. To minimize artifacts we measured normal and cancerous tissues simultaneously and separated their NMR signals by applying a magnetic field gradient. We present T1 dispersion curves for several sets of samples, and discuss the applicability of this technique to in vivo imaging. Work supported by USDOE.

Mößle, Michael; Busch, Sarah; Hatridge, Michael; Myers, Whittier; Pines, Alexander; Clarke, John; Schmitt, Lars; Simko, Jeff

2006-03-01

232

Experience acquired by the Mobile Remote-Control Operation and Detection Group of the CEA  

International Nuclear Information System (INIS)

In recent years the Mobile Remote-Control Operation and Detection Group of the CEA have intervened on various occasions as follows: to replace personnel required to spend time in working areas in which dose rates were permanently high or very high; to support personnel required to work near high-activity sources producing or likely to produce mobile or short-lived beams of ionizing radiation; and to support personnel required to perform tedious and/or repetitive operations in working areas in which only a limited amount of time may be spent. Among the interventions performed, mention is made of the recovery of radioactive sources which have been placed in abnormal positions as a result of incorrect handling or incidents involving machinery; the transfer of radioactive sources during the loading or unloading of irradiation devices; the inspection by television camera, modification, dismantling or reassembly of protective devices in the neighbourhood of high- or very high-activity sources; and the cleaning of installations polluted by radioactive contaminants which present a high risk of external irradiation of the personnel required to work there. After obtaining a hermetically sealed version of the ''Mobile Remote-Control Intervention Operator'' (TOMI) and an ''Intervention Dose and Dose-Rate Measurement Unit'' (EDDI) in 1979, the Mobile Remote-Control Operation and Detection Group has very recently put into operation a remote-controlled intervention module which take-controlled intervention module which takes up very little space and can carry over 100 kg of different types of equipment. The authors summarize development work on the MERITE module and on master-slave remote handling devices with servo control and feedback of the MA-23 type, the flexibility of which has yet again been verified very recently during an intervention at a nuclear installation. (author)

233

Remote detection of nuclear magnetic resonance with an anisotropic magnetoresistive sensor.  

Science.gov (United States)

We report the detection of nuclear magnetic resonance (NMR) using an anisotropic magnetoresistive (AMR) sensor. A "remote-detection" arrangement was used in which protons in flowing water were prepolarized in the field of a superconducting NMR magnet, adiabatically inverted, and subsequently detected with an AMR sensor situated downstream from the magnet and the adiabatic inverter. AMR sensing is well suited for NMR detection in microfluidic "lab-on-a-chip" applications because the sensors are small, typically on the order of 10 mum. An estimate of the sensitivity for an optimized system indicates that approximately 6 x 10(13) protons in a volume of 1,000 mum(3), prepolarized in a 10-kG magnetic field, can be detected with a signal-to-noise ratio of 3 in a 1-Hz bandwidth. This level of sensitivity is competitive with that demonstrated by microcoils in superconducting magnets and with the projected sensitivity of microfabricated atomic magnetometers. PMID:18268323

Verpillat, F; Ledbetter, M P; Xu, S; Michalak, D J; Hilty, C; Bouchard, L-S; Antonijevic, S; Budker, D; Pines, A

2008-02-19

234

Diagnostic performance of combined cardiac MRI for detection of coronary artery disease  

International Nuclear Information System (INIS)

Highlights: ? In this study, we evaluated the accuracy of a Combined CMR protocol in the detection of significant CAD. ? The invasive coronary angiography was the reference standard. ? Results obtained in our study indicate that combination of perfusion and cine-MR during stress/rest, associated to delayed enhancement in the same protocol improves CMRI diagnostic accuracy and sensitivity for patients with significant coronary stenosis. ? The Combined CMR protocol may therefore be helpful for risk stratification and defining treatment strategies. -- Abstract: Objective: To evaluate the diagnostic performance of stress perfusion cardiac MR (CMR) for detecting significant CAD (?70% narrowing) in comparison with invasive coronary angiography (ICA) as a reference standard. Methods: Examinations of 54 patients who underwent both stress perfusion CMR and ICA for investigation of CAD between 2007 and 2009 were evaluated. The CMR protocol included dipyridamole stress and rest perfusion, stress and rest cine MRI for assessment of ventricular function and delayed gadolinium enhancement for assessment of myocardial viability and detection of infarction. CMR interpretation was performed by 2 observers blinded to the results of ICA and the clinical history. Results: From a total of 54 patients, 37 (68.5%) showed significant CAD in 71 coronary territories. A perfusion defect was detected in 35 patients and in 69 coronary territories. Individual stress perfusion CMR evaluation showed the highest accuracy (83%) of the CMR techniques. The combined analysis using all sequences increased the overall accuracy of CMR to 87%. Conclusion: Combination of perfusion and cine-MR during stress/rest, associated to delayed enhancement in the same protocol improves CMRI diagnostic accuracy and sensitivity for patients with significant coronary stenosis, and may therefore be helpful for risk stratification and defining treatment strategies.

235

Diagnostic performance of combined cardiac MRI for detection of coronary artery disease  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer In this study, we evaluated the accuracy of a Combined CMR protocol in the detection of significant CAD. Black-Right-Pointing-Pointer The invasive coronary angiography was the reference standard. Black-Right-Pointing-Pointer Results obtained in our study indicate that combination of perfusion and cine-MR during stress/rest, associated to delayed enhancement in the same protocol improves CMRI diagnostic accuracy and sensitivity for patients with significant coronary stenosis. Black-Right-Pointing-Pointer The Combined CMR protocol may therefore be helpful for risk stratification and defining treatment strategies. -- Abstract: Objective: To evaluate the diagnostic performance of stress perfusion cardiac MR (CMR) for detecting significant CAD ({>=}70% narrowing) in comparison with invasive coronary angiography (ICA) as a reference standard. Methods: Examinations of 54 patients who underwent both stress perfusion CMR and ICA for investigation of CAD between 2007 and 2009 were evaluated. The CMR protocol included dipyridamole stress and rest perfusion, stress and rest cine MRI for assessment of ventricular function and delayed gadolinium enhancement for assessment of myocardial viability and detection of infarction. CMR interpretation was performed by 2 observers blinded to the results of ICA and the clinical history. Results: From a total of 54 patients, 37 (68.5%) showed significant CAD in 71 coronary territories. A perfusion defect was detected in 35 patients and in 69 coronary territories. Individual stress perfusion CMR evaluation showed the highest accuracy (83%) of the CMR techniques. The combined analysis using all sequences increased the overall accuracy of CMR to 87%. Conclusion: Combination of perfusion and cine-MR during stress/rest, associated to delayed enhancement in the same protocol improves CMRI diagnostic accuracy and sensitivity for patients with significant coronary stenosis, and may therefore be helpful for risk stratification and defining treatment strategies.

Andrade Fernandes de Mello, Ricardo, E-mail: ricardoafmello@gmail.com [Hospital de Clinicas de Niteroi - HCN, Niteroi, RJ (Brazil); Radiology Department, Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, RJ (Brazil); Universidade Federal do Espirito Santo - UFES, Vitroria, ES (Brazil); Nacif, Marcelo Souto, E-mail: msnacif@gmail.com [Hospital de Clinicas de Niteroi - HCN, Niteroi, RJ (Brazil); Radiology Department, Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, RJ (Brazil); Radiology and Imaging Sciences, National Institutes of Health Clinical Center, Bethesda, MD (United States); Radiology Department, Universidade Federal Fluminense - UFF, Niteroi, RJ (Brazil); Sarmet dos Santos, Alair Augusto Sarmet, E-mail: alairsarmet@globo.com [Hospital de Clinicas de Niteroi - HCN, Niteroi, RJ (Brazil); Radiology Department, Universidade Federal Fluminense - UFF, Niteroi, RJ (Brazil); Cury, Ricardo Caldeira, E-mail: RCury@baptisthealth.net [Baptist Cardiac and Vascular Institute, Miami, FL (United States); Rochitte, Carlos Eduardo, E-mail: rochitte@incor.usp.br [Department of Cardiovascular MRI and CT InCor - HCFMUSP, SP (Brazil); Marchiori, Edson, E-mail: edmarchiori@gmail.com [Radiology Department, Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, RJ (Brazil); Radiology Department, Universidade Federal Fluminense - UFF, Niteroi, RJ (Brazil)

2012-08-15

236

Sensitive technique for detecting outer defect on tube with remote field eddy current testing  

International Nuclear Information System (INIS)

In the remote field eddy current testing, we proposed the method of enhancing the magnetic flux density in the vicinity of an exciter coil by controlling the magnetic flux direction for increasing the sensitivity of detecting outer defects on a tube and used the flux guide made of a magnetic material for the method. The optimum structural shape of the flux guide was designed by the magnetic field analysis. On the experiment with the application of the flux guide, the magnetic flux density increased by 59% and the artificial defect detection signal became clear. We confirmed the proposed method was effective in a high sensitivity. (author)

237

Capabilities of Remote Sensing Hyperspectral Images for the Detection of Lead Contamination: a Review  

Science.gov (United States)

Advances in remote sensing technologies are increasingly becoming more useful for resource, ecosystem and agricultural management applications to the extent that these techniques can now also be applied for monitoring of soil contamination and human health risk assessment. While, extensive previous studies have shown that Visible and Near Infrared Spectroscopy (VNIRS) in the spectral range 400-2500 nm can be used to quantify various soil constituents simultaneously, the direct determination of metal concentrations by remote sensing and reflectance spectroscopy is not as well examined as other soil parameters. The application of VNIRS, including laboratory hyperpectral measurements, field spectrometer measurements or image spectroscopy, generally achieves a good prediction of metal concentrations when compared to traditional wet chemical methods and has the advantage of being relatively less expensive and faster, allowing chemical assessment of contamination in close to real time. Furthermore, imaging spectroscopy can potentially provide significantly more samples over a larger spatial extent than traditional ground sampling methods. Thus the development of remote sensing techniques (field based and either airborne or satellite hyperspectral imaging) can support the monitoring and efficient mapping of metal contamination (in dust and soil) for environmental and health impact assessment. This review is concerned with the application of remote sensing and reflectance spectroscopy to the detection of heavy metals and discusses how current methods could be applied for the quantification of Pb contaminated soil surrounding mines and smelters.

Maliki, A. A.; Owens, G.; Bruce, D.

2012-07-01

238

Dynamic MRI-based computer aided diagnostic systems for early detection of kidney transplant rejection: A survey  

Science.gov (United States)

Early detection of renal transplant rejection is important to implement appropriate medical and immune therapy in patients with transplanted kidneys. In literature, a large number of computer-aided diagnostic (CAD) systems using different image modalities, such as ultrasound (US), magnetic resonance imaging (MRI), computed tomography (CT), and radionuclide imaging, have been proposed for early detection of kidney diseases. A typical CAD system for kidney diagnosis consists of a set of processing steps including: motion correction, segmentation of the kidney and/or its internal structures (e.g., cortex, medulla), construction of agent kinetic curves, functional parameter estimation, diagnosis, and assessment of the kidney status. In this paper, we survey the current state-of-the-art CAD systems that have been developed for kidney disease diagnosis using dynamic MRI. In addition, the paper addresses several challenges that researchers face in developing efficient, fast and reliable CAD systems for the early detection of kidney diseases.

Mostapha, Mahmoud; Khalifa, Fahmi; Alansary, Amir; Soliman, Ahmed; Gimel'farb, Georgy; El-Baz, Ayman

2013-10-01

239

Monitoring Forests: A New Paradigm of Remote Sensing & GIS Based Change Detection  

Directory of Open Access Journals (Sweden)

Full Text Available Remote sensing has emerged as the main tool for mapping and monitoring of forest resources globally. In India, this technological tool is in use for biennial monitoring of forest cover of the country for the last 25 years. Among the numerous applications of remote sensing in forest management, change detection is the one which is most frequently used. In this paper, a new paradigm of change detection has been presented in which change of vegetation in a grid (a square shaped unit area is the basis of change analysis instead of change at the pixel level. The new method is a simpler approach and offers several advantages over the conventional approaches of remote sensing based change detection. The study introduces an index termed as ‘Grid Vegetation Change Index (GVCI’, its numerical value gives quantified assessment of the degree of change. The minus value of GVCI indicates loss or negative change and similarly positive value vice versa. By applying the GVCI on a pair of remotely sensed images of two dates of an area, one can know degree of vegetation change in every unit area (grid of the large landscape. Based on the GVCI values, one can select those grids which show significant changes. Such ‘candidate grids with significant changes’ may be shortlisted for ground verification and studying the causes of change. Since the change identification is based on the index value, it is free from human subjectivity or bias. Though there may be some limitations of the methodology, the GVCI based approach offers an operational application for monitoring forests in India and elsewhere for complete scanning of forest areas to pointedly identify change locations, identifying the grids with significant changes for objective and discrete field inspections with the help of GPS. It also offers a method to monitor progress of afforestation and conservation schemes, monitor habitats of wildlife areas and potential application in carbon assessment methodologies of CDM and REDD+.

Subhash Ashutosh

2012-11-01

240

Ship Detection of Remote Sensing Image on FRHT and Multi-Points Curvature Based Polygon Approximation  

Directory of Open Access Journals (Sweden)

Full Text Available One of the most difficult tasks of ship detection is detecting the ship which is docking at the port in remote sensing image. Traditional methods of automatic detection cannot be used to detect the land/waterboundaries, because both the gray values and textural features of a port are similar to those of the ships which are docking at the port. Therefore, ships cannot be accurately detected in this case. In this study, a novel method of land/water-boundaries detection is proposed, which is based on a polygon approximation method by incorporating two techniques, i.e., Fuzzy Randomized Hough Transform (FRHT and Multi-Points Curvature (MPC. The method considered the feature of human vision that the straight-line of the land/water-boundaries can be detected more accurately and rapidly. With the detection result of land/water-boundaries, ships docking at the port can be accurately detected. The experiment results demonstrate that this method can achieve good result of ship detection.

Wang Luo

2012-08-01

 
 
 
 
241

Detection of ancient Egyptian archaeological sites using satellite remote sensing and digital image processing  

Science.gov (United States)

Satellite remote sensing is playing an increasingly important role in the detection and documentation of archaeological sites. Surveying an area from the ground using traditional methods often presents challenges due to the time and costs involved. In contrast, the multispectral synoptic approach afforded by the satellite sensor makes it possible to cover much larger areas in greater spectral detail and more cost effectively. This is especially the case for larger scale regional surveys, which are helping to contribute to a better understanding of ancient Egyptian settlement patterns. This study presents an overview of satellite remote sensing data products, methodologies, and image processing techniques for detecting lost or undiscovered archaeological sites with reference to Egypt and the Near East. Key regions of the electromagnetic spectrum useful for site detection are discussed, including the visible near-infrared (VNIR), shortwave infrared (SWIR), thermal infrared (TIR), and microwave (radar). The potential of using Google Earth as both a data provider and a visualization tool is also examined. Finally, a case study is presented for detecting tell sites in Egypt using Landsat ETM+, ASTER, and Google Earth imagery. The results indicated that principal components analysis (PCA) was successfully able to detect and differentiate tell sites from modern settlements in Egypt's northwestern Nile Delta region.

Corrie, Robert K.

2011-11-01

242

Incremental value of diffusion weighted and dynamic contrast enhanced MRI in the detection of locally recurrent prostate cancer after radiation treatment: preliminary results  

Energy Technology Data Exchange (ETDEWEB)

To assess the incremental value of diffusion-weighted (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) to T2-weighted MRI (T2WI) in detecting locally recurrent prostate cancer after radiotherapy. Twenty-four patients (median age, 70 years) with a history of radiotherapy-treated prostate cancer underwent multi-parametric MRI (MP-MRI) and transrectal prostate biopsy. Two readers independently scored the likelihood of cancer on a 1-5 scale, using T2WI alone and then adding DW-MRI and DCE-MRI. Areas under receiver operating characteristic curves (AUCs) were estimated at the patient and prostate-side levels. The apparent diffusion coefficient (ADC) from DW-MRI and the K{sup trans}, k{sub ep}, v{sub e}, AUGC90 and AUGC180 from DCE-MRI were recorded. Biopsy was positive in 16/24 (67%) and negative in 8/24 (33%) patients. AUCs for readers 1 and 2 increased from 0.64 and 0.53 to 0.95 and 0.86 with MP-MRI, at the patient level, and from 0.73 and 0.66 to 0.90 and 0.79 with MP-MRI, at the prostate-side level (p values < 0.05). Biopsy-positive and biopsy-negative prostate sides differed significantly in median ADC [1.44 vs. 1.68 (x 10{sup -3} mm{sup 2}/s)], median K{sup trans} [1.07 vs. 0.34 (1/min)], and k{sub ep} [2.06 vs 1.0 (1/min)] (p values < 0.05). MP-MRI was significantly more accurate than T2WI alone in detecting locally recurrent prostate cancer after radiotherapy. (orig.)

Akin, Oguz; Vargas, Hebert Alberto; Hricak, Hedvig [Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York, NY (United States); Gultekin, David H. [Memorial Sloan-Kettering Cancer Center, Medical Physics, New York, NY (United States); Zheng, Junting; Moskowitz, Chaya [Memorial Sloan-Kettering Cancer Center, Epidemiology and Biostatistics, New York, NY (United States); Pei, Xin; Sperling, Dahlia; Zelefsky, Michael J. [Memorial Sloan-Kettering Cancer Center, Radiation Oncology, New York, NY (United States); Schwartz, Lawrence H. [Columbia University College of Physicians and Surgeons, Radiology, New York, NY (United States)

2011-09-15

243

Incremental value of diffusion weighted and dynamic contrast enhanced MRI in the detection of locally recurrent prostate cancer after radiation treatment: preliminary results  

International Nuclear Information System (INIS)

To assess the incremental value of diffusion-weighted (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) to T2-weighted MRI (T2WI) in detecting locally recurrent prostate cancer after radiotherapy. Twenty-four patients (median age, 70 years) with a history of radiotherapy-treated prostate cancer underwent multi-parametric MRI (MP-MRI) and transrectal prostate biopsy. Two readers independently scored the likelihood of cancer on a 1-5 scale, using T2WI alone and then adding DW-MRI and DCE-MRI. Areas under receiver operating characteristic curves (AUCs) were estimated at the patient and prostate-side levels. The apparent diffusion coefficient (ADC) from DW-MRI and the Ktrans, kep, ve, AUGC90 and AUGC180 from DCE-MRI were recorded. Biopsy was positive in 16/24 (67%) and negative in 8/24 (33%) patients. AUCs for readers 1 and 2 increased from 0.64 and 0.53 to 0.95 and 0.86 with MP-MRI, at the patient level, and from 0.73 and 0.66 to 0.90 and 0.79 with MP-MRI, at the prostate-side level (p values -3 mm2/s)], median Ktrans [1.07 vs. 0.34 (1/min)], and kep [2.06 vs 1.0 (1/min)] (p values < 0.05). MP-MRI was significantly more accurate than T2WI alone in detecting locally recurrent prostate cancer after radiotherapy. (orig.)

244

Early detection of femoral head avascular necrosis by bone SPECT compared to MRI in renal allograft recipients  

Energy Technology Data Exchange (ETDEWEB)

The prevalence of avascular necrosis (AVN) of femoral head in patients who receive immunosuppresive agents after renal transplantation is reported to be 4-29%. Among patients who develop AVN after renal transplantation, 80% become symptomatic within 2 years after transplantation. As the number of renal transplantation has been increased recently, early detection of femoral head AVN is very important because early surgical core decompression of femoral head can prevent collapse of the head. MRI is known to be very sensitive to diagnose femoral head AVN. However in three cases we report here, bone SPECT showed early changes of femoral head AVN, whereas MRI showed no specific abnormality. Case 1. A 53-year-old female received an allograft kidney transplantation in 1994. Preoperative bone scan was normal. She complained of both hip pain on Mar. 18 1997. Bone SPECT showed cold defect in both femoral heads but MRI showed no abnormality. After 3 months, bone SPECT and MRI showed AVN of both femoral heads. She underwent bilateral total hip replacement arthroplasty. AVN of femoral heads was confirmed by microscopic examination. Case 2. A 38-year-old female received an allograft kidney transplantation in Feb. 27 1997. Preoperative bone scan was normal. She ran a fever and creatinine was elevated from 1.2 to 2.8 mg/dL. She took high dose methylprednisolone therapy for acute reanl rejection. After two days, she complained pain in both hip joints and knee joints. Bone SPECT showed cold defects in both femoral heads but MRI showed no abnormality. A follow-up bone SPECT and MRI 20 days later revealed AVN of both femoral heads. Case 3. A 50-year-old male received an allograft kidney transplantation on Jul. 12 1995. Preoperative bone scan was normal. He complained of right hip pain on Jul, 26 1995. His bone SPECT showed cold defects in both femoral heads while MRI showed only minimal hip joint effusion. He also complained of left hip pain on Oct. 2 1995. He was admitted on Mar 17 1996 because of both hip pain and fever. MRI showed advanced AVN of femoral heads was confirmed by microscopic examination. Bone SPECT can diagnose early AVN of femoral head in renal allograft recipients when MRI could be normal.

Kang, Do Young; Yang, Seoung Oh; Lee, Hee Kyung; Han, Duck Jong; Shin, Myung Jin [Asan Mecical Center, Seoul (Korea, Republic of)

1997-07-01

245

Detection of VX-2 carcinoma in rabbit livers: comparison of sonography, CT, and MRI  

International Nuclear Information System (INIS)

Our study was designed to investigate the value of different imaging techniques in the early detection of VX-2 carcinoma in rabbit livers by direct comparison of sonography, CT, and MR imaging with pathologic specimens. VX-2 carcinomas were induced in 20 rabbit livers by direct inoculation of 0.1 ml of aliquot of the tumor tissue suspension (1 x 106/mm3) to hepatic parenchyma with an 18 gauge needle after laparotomy. One week after the inoculation of tumor cells, sonography with a 5 MHz transducer, CT after a bolus injection of contrast medium (3 mL/kg), and T1-weighted MR imaging at a 2.0 T with spin-echo techniques (TR/TE : 500/30 msec, 2000/30, 80 msec) as well as enhanced T1-weighted MR imaging with GD-DTPA (0.1 mmole/kg) were performed in each rabbit. At pathologic specimens, adequate induction of tumor nodules were 69 with 3-21 mm size (average 8.3 mm). All 69 tumors had fibrous capsules and central necrosis pathologically. The sensitivities of sonography, contrast enhanced CT and MR imaging were 54%, 61%, and 87%, respectively. Among MR images, the sensitivities of T1-weighted images, proton density images, T2-weighted images, and enhanced T1-weighted images were 33%, 77%, 83%, and 81%, respectively. On sonograms and CT scans, VX-2 carcinomas show variable appearance regardless of the tumor size and histopathologic findings. On MR images, the tumors were ring shape with variable thickness on all pulse sequences. There was no significant correlation among the findings of three imaging techniques. MR imaging has the highest detectability for the VX-2 carcinomas in rabbit liver. Therefore, MRI may be the most valuable imaging technique for the detection of small hepatic tumors with extensive necrosis like VX-2 carcinomas

246

A robust anomaly based change detection method for time-series remote sensing images  

Science.gov (United States)

Time-series remote sensing images record changes happening on the earth surface, which include not only abnormal changes like human activities and emergencies (e.g. fire, drought, insect pest etc.), but also changes caused by vegetation phenology and climate changes. Yet, challenges occur in analyzing global environment changes and even the internal forces. This paper proposes a robust Anomaly Based Change Detection method (ABCD) for time-series images analysis by detecting abnormal points in data sets, which do not need to follow a normal distribution. With ABCD we can detect when and where changes occur, which is the prerequisite condition of global change studies. ABCD was tested initially with 10-day SPOT VGT NDVI (Normalized Difference Vegetation Index) times series tracking land cover type changes, seasonality and noise, then validated to real data in a large area in Jiangxi, south of China. Initial results show that ABCD can precisely detect spatial and temporal changes from long time series images rapidly.

Shoujing, Yin; Qiao, Wang; Chuanqing, Wu; Xiaoling, Chen; Wandong, Ma; Huiqin, Mao

2014-03-01

247

In vivo MRI for effective non-invasive detection and follow-up of an orthotopic mouse model of lung cancer.  

Science.gov (United States)

One of the main reasons for the dismal prognosis of lung cancer is related to the late diagnosis of this pathology. In this study, we evaluated the potential of optimized lung MRI techniques as a completely non-invasive approach for non-small-cell lung cancer (NSCLC) MRI in vivo detection and follow-up in a mouse model of lung adenocarcinoma expressing the luciferase gene. Bioluminescent lung tumour cells were orthotopically implanted in immuno-deficient mice. Ultra-short echo-time (UTE) MRI free-breathing acquisitions were compared with standard gradient-echo lung MRI (FLASH) using both respiratory-gated and free-breathing protocols. The MRI findings were validated against bioluminescence imaging (BLI) and gold-standard histopathology analysis. Adenocarcinoma-like pathological tissue was successfully identified in all the mice with gated-FLASH and non-gated UTE MRI, and good tumour co-localization was found between MRI, BLI and histological analyses. An excellent or good correlation was found between the measured bioluminescent signal and the total tumour volumes quantified with UTE MRI or gated-FLASH MRI, respectively. No significant correlation was found when the tumours were segmented on non-gated MR FLASH images. MRI was shown to be a powerful imaging tool able to detect, quantify and longitudinally monitor the development of sub-millimetric NSCLCs. To our knowledge, this is the first study which proves the feasibility of a completely non-invasive MRI quantitative detection of lung adenocarcinoma in freely breathing mice. The absence of ionizing radiation and the high-resolution of MRI, along with the complete non-invasiveness and good reproducibility of the proposed non-gated protocol, make this imaging tool ideal for direct translational applications. PMID:24913958

Bianchi, Andrea; Dufort, Sandrine; Fortin, Pierre-Yves; Lux, François; Raffard, Gérard; Tassali, Nawal; Tillement, Olivier; Coll, Jean-Luc; Crémillieux, Yannick

2014-08-01

248

Detection of environmental change using hyperspectral remote sensing at Olkiluoto repository site  

International Nuclear Information System (INIS)

In this report methods related to hyperspectral monitoring of Olkiluoto repository site are described. A short introduction to environmental remote sensing is presented, followed by more detailed description of hyperspectral imaging and a review of applications of hyperspectral remote sensing presented in the literature. The trends of future hyperspectral imaging are discussed exploring the possibilities of long-wave infrared hyperspectral imaging. A detailed description of HYPE08 hyperspectral flight campaign at the Olkiluoto region in 2008 is presented. In addition, related pre-processing and atmospheric correction methods, necessary in monitoring use, and the quality control methods applied, are described. Various change detection methods presented in the literature are described, too. Finally, a system for hyperspectral monitoring is proposed. The system is based on continued hyperspectral airborne flight campaigns and precisely defined data processing procedure. (orig.)

249

Detection of Surface Temperature Anomalies in the Coso Geothermal Field Using Thermal Infrared Remote Sensing  

Science.gov (United States)

We use thermal infrared (TIR) data from the spaceborne ASTER instrument to detect surface temperature anomalies in the Coso geothermal field in eastern California. The identification of such anomalies in a known geothermal area serves as an incentive to search for similar markers to areas of unknown geothermal potential. We carried out field measurements concurrently with the collection of ASTER images. The field data included reflectance, subsurface and surface temperatures, and radiosonde atmospheric profiles. We apply techniques specifically targeted to correct for thermal artifacts caused by topography, albedo, and thermal inertia. This approach has the potential to reduce data noise and to reveal thermal anomalies which are not distinguishable in the uncorrected imagery. The combination of remote sensing and field data can be used to evaluate the performance of TIR remote sensing as a cost-effective geothermal exploration tool.

Coolbaugh, M.; Eneva, M.; Bjornstad, S.; Combs, J.

2007-12-01

250

Remote detection of radioactive materials via Coherent Anti-Stokes Raman Scattering  

International Nuclear Information System (INIS)

A sensible nonlinear optical method for remote detection of small quantities of radioactive materials such as deuterium, plutonium, uranium-235, uranium enriched in the isotopes of uranium-233 or uranium-235 with concentration >1 ppb at distances greater than 100 m is proposed. The proposed method is based on remote sensing of the chemo-nuclear by-products(O3, HNO3, HO2NO2, and NO2 with the molar fractions ? 5 10-7, 3 10-7, 2 10-7 and 4 10-7 correspondingly, produced by gamma and neutron radiation interacting with the surrounding atmosphere. The possibility of Coherent Anti-Stokes Raman Scattering (CARS) registration from specific trace gases is discussed. (author)

251

Detection and identification of Arctic landforms - An assessment of remotely sensed data  

Science.gov (United States)

The use of remote sensing data to monitor and analyze the arctic environment is examined. Landsat MSS, TM simulated, NS001, Seasat, and airborne radar are employed to investigate the Strand and Dune areas on the Arctic Coastal Plain in Alaska. The Strand area contains landforms associated with permafrost and the Dune area is dominated by eolian deposits consisting of large longitudinal dunes. The remote sensing data are compared to baseline geomorphic maps derived from aerial photography. It is observed that the multispectral data are better than the radar data for the detection and recognition of arctic landforms, and the NS001 data provided the highest spatial resolution and correlated well with the high-altitude aerial photography.

Dean, Kenneson G.; Morrissey, Leslie A.

1988-01-01

252

Classification of LULC Change Detection using Remotely Sensed Data for Coimbatore City, Tamilnadu, India  

CERN Document Server

Maps are used to describe far-off places . It is an aid for navigation and military strategies. Mapping of the lands are important and the mapping work is based on (i). Natural resource management & development (ii). Information technology ,(iii). Environmental development ,(iv). Facility management and (v). e-governance. The Landuse / Landcover system espoused by almost all Organisations and scientists, engineers and remote sensing community who are involved in mapping of earth surface features, is a system which is derived from the united States Geological Survey (USGS) LULC classification system. The application of RS and GIS involves influential of homogeneous zones, drift analysis of land use integration of new area changes or change detection etc.,National Remote Sensing Agency(NRSA) Govt. of India has devised a generalized LULC classification system respect to the Indian conditions based on the various categories of Earth surface features , resolution of available satellite data, capabilities of se...

Babykalpana, Y

2010-01-01

253

Determination of Change Detection of Lanscape of the Kucuk Menderes Delta Using GIS and the Remote Sensing Techniques  

Directory of Open Access Journals (Sweden)

Full Text Available Remote sensing and GIS offers an important means of detecting and analyzing temporal changes occurring in the earth surface. This research used remote sensing and GIS to quantify landscape changes at the Kucuk Menderes Basin, Izmir, Turkey. In this study, we concentrated on determining the geomorphology of the with time of the coastal strip and the coastal part of the Kucuk Menderes Basin towards terrestrial formation using aerial photographs and satellite images involving remote sensing techniques. Making use of satellite images of 2001, topographic maps and aerial photographs of previous years, were used to determine geomorphological aspects of change detection and geomorphology of the region.

Mustafa Bolca

2005-01-01

254

The change detection of multi-temporal remote sensing images based on D-S algorithm  

Science.gov (United States)

Change Detection is one of the most popular topics in the field of Multi-temporal Remote Sensing (RS) applications. In this paper, a novel approach was introduced for the change detection of the urban area. This approach adopts the Dempster-Shafer(D-S) algorithm for feature fusion of the multi-temporal RS images. It, in the first place,,constructs difference images of pixel and context respectively. These two difference images present the features of changes in different scales. The pixel difference image is obtained by fusing the results of the subtraction operation and the division operation, while the context difference image is obtained by the image context. Secondly, by using the difference images, two evidences could be constructed. These evidences are not certain, but they can give more reliable combination result if considering the average support of the evidence to different subsets in the assignment framework. And based on these evidences, the criterion function could be established by the D-S theory. At last, an improved D-S algorithm is applied to fuse the two different features for detecting the change information of the RS images. An experiment, using the SPOT and TM images of Wuhan urban area, has compared the accuracy of edge detection by using the new fusion algorithm and the existent ones. The result shows that the method of improved D-S is solid and efficacious, which has preferable value in remote sensing applications.

Dian, Yuanyong; Fang, Shenghui

2009-10-01

255

Fiber optic TDLAS-based multi-gas remote detection system for mine goaf fire  

Science.gov (United States)

Spontaneous combustion in coal goaf area is one of major disasters in coal mines. Detection technology based on signature Gas is the primary means of spontaneous combustion forecasting of coal goaf area. A real-time remote fire gas detection system is proposed based on tunable diode laser absorption spectroscopy technology, to achieve valid test of signature gas (CO, CO2, CH4, C2H2 and C2H4). The System uses the wavelength, respectively 1.567um, 1.608um, 1.653um, 1.530um, 1.623um near-infrared band fiber-coupled distributed feedback laser (DFB) as the light source, Combined wavelength modulation spectroscopy and harmonic detection technique, developed a fiber-coupled white-type long-path gas absorption cell, to achieve high sensitivity detection of gas concentration. The system achieved a remote on-line monitoring of multi-component gas concentration,to meet the fire forecast need for Coal goaf area. There are obvious advantages Compared with the existing beam tube monitoring system in coal mine.

Wei, Yubin; Li, Yanfang; Shang, Ying; Zhang, Tingting; Song, Zhiqiang; Wang, Chang; Liu, Tongyu

2010-10-01

256

Detection of TNT using a sensitive two-photon organic dendrimer for remote sensing  

Energy Technology Data Exchange (ETDEWEB)

There is currently a need for superior stand-off detection schemes for protection against explosive weapons of mass destruction. Fluorescence detection at small distances from the target has proven to be attractive. A novel unexplored route in fluorescence chemical sensing that utilizes the exceptional spectroscopic capabilities of nonlinear optical methods is two-photon excited fluorescence. This approach utilizes infra-red light for excitation of remote sensors. Infra-red light suffers less scattering in porous materials which is beneficial for vapor sensing and has greater depth of penetration through the atmosphere, and there are fewer concerns regarding eye safety in remote detection schemes. We demonstrate this method using a novel dendritic system which possesses both excellent fluorescence sensitivity to the presence of TNT with infra-red pulses of light and high two-photon absorption (TPA) response. This illustrates the use of TPA for potential stand-off detection of energetic materials in the infra-red spectral regions in a highly two-photon responsive dendrimer.

Narayanan, Aditya; Varnavski, Oleg; Goodson, Theodore III [Department of Chemistry and Macromolecular Science and Engineering, NSF Center for Ultra-fast Optical Science (FOCUS), University of Michigan, Ann Arbor, MI 48109 (United States); Mongin, Oliver; Blanchard-Desce, Mireille [Synthese et ElectroSynthese Organiques (CNRS, UMR 6510), Universite de Rennes 1, Institut de Chimie, Campus Scientifique de Beaulieu, Bat 10A, F-35042 Rennes Cedex (France); Majoral, Jean-Pierre [Laboratoire de Chimie de Coordination, CNRS, 205 route de Narbonne, F-31077, Toulouse Cedex 4 (France)], E-mail: tgoodson@umich.edu

2008-03-19

257

Detection of TNT using a sensitive two-photon organic dendrimer for remote sensing  

International Nuclear Information System (INIS)

There is currently a need for superior stand-off detection schemes for protection against explosive weapons of mass destruction. Fluorescence detection at small distances from the target has proven to be attractive. A novel unexplored route in fluorescence chemical sensing that utilizes the exceptional spectroscopic capabilities of nonlinear optical methods is two-photon excited fluorescence. This approach utilizes infra-red light for excitation of remote sensors. Infra-red light suffers less scattering in porous materials which is beneficial for vapor sensing and has greater depth of penetration through the atmosphere, and there are fewer concerns regarding eye safety in remote detection schemes. We demonstrate this method using a novel dendritic system which possesses both excellent fluorescence sensitivity to the presence of TNT with infra-red pulses of light and high two-photon absorption (TPA) response. This illustrates the use of TPA for potential stand-off detection of energetic materials in the infra-red spectral regions in a highly two-photon responsive dendrimer

258

Cardiac MRI. Diagnostic gain of an additional axial SSFP chest sequence for the detection of potentially significant extracardiac findings in the cardiac MRI examination setting  

International Nuclear Information System (INIS)

Purpose: Cardiac MRI (CMRI) is an effective method for imaging of the heart. The aim of our study was to assess whether an axial chest sequence in addition to the standard CMR examination setting has advantages in the detection of potentially significant extracardiac findings (PSEF). Materials and Methods: 400 consecutive patients were imaged at 1.5 T for clinical reasons. In addition to the standard long and short-axis views, an axial SSFP sequence was obtained covering the thorax from the lung apex to the diaphragm. All sequences were separately evaluated for PSEF. Results: A total of 25 PSEF were diagnosed in 400 patients, including 16 pleural effusions, a pulmonary fibrosis, a spondylodiscitis, ascites, lymphadenopathies, relapse of a mamma carcinoma, growth of adrenal glands metastases and diaphragmatic elevation. All 25 PSEF were detected by reading survey sequences. 24 of the 25 PSEF were detected by the additional SSFP chest sequence as well as the CINE sequences. Conclusion: In our study the additional axial SSFP chest sequence didn't show a benefit in the detection of PSEF. With the survey sequences we were able to detect all PSEF. We conclude that survey images should be assessed for additional findings. (orig.)

259

Cardiac MRI. Diagnostic gain of an additional axial SSFP chest sequence for the detection of potentially significant extracardiac findings in the cardiac MRI examination setting  

Energy Technology Data Exchange (ETDEWEB)

Purpose: Cardiac MRI (CMRI) is an effective method for imaging of the heart. The aim of our study was to assess whether an axial chest sequence in addition to the standard CMR examination setting has advantages in the detection of potentially significant extracardiac findings (PSEF). Materials and Methods: 400 consecutive patients were imaged at 1.5 T for clinical reasons. In addition to the standard long and short-axis views, an axial SSFP sequence was obtained covering the thorax from the lung apex to the diaphragm. All sequences were separately evaluated for PSEF. Results: A total of 25 PSEF were diagnosed in 400 patients, including 16 pleural effusions, a pulmonary fibrosis, a spondylodiscitis, ascites, lymphadenopathies, relapse of a mamma carcinoma, growth of adrenal glands metastases and diaphragmatic elevation. All 25 PSEF were detected by reading survey sequences. 24 of the 25 PSEF were detected by the additional SSFP chest sequence as well as the CINE sequences. Conclusion: In our study the additional axial SSFP chest sequence didn't show a benefit in the detection of PSEF. With the survey sequences we were able to detect all PSEF. We conclude that survey images should be assessed for additional findings. (orig.)

Roller, F.C.; Schneider, C.; Krombach, G.A. [University Hospital Giessen (Germany). Dept. Radiology; Schuhbaeck, A. [University Hospital Giessen (Germany). Dept. Cardiology; Rolf, A. [Kerckhoff Hospital Bad Nauheim (Germany). Dept. Cardiology

2014-01-15

260

Detection of rice sheath blight for in-season disease management using multispectral remote sensing  

Science.gov (United States)

Timely diagnosis of crop diseases in fields is critical for precision on-farm disease management. Remote sensing technology can be used as an effective and inexpensive method to identify diseased plants in a field scale. However, due to the diversity of crops and their associated diseases, application of the technology to agriculture is still in research stage, which needs to be elaborately investigated for algorithm development and standard image processing procedures. In this paper, we examined the applicability of broadband high spatial-resolution ADAR (Airborne Data Acquisition and Registration) remote sensing data to detect rice sheath blight and developed an approach to further explore the applicability. Based on the field symptom measurements, a comprehensive field disease index (DI) was constructed to measure infection severity of the disease and to relate to image sampled infections. In addition to direct band digital number (DN) values, band ratio indices and standard difference indices were used to examine possible correlations between field and image data. The results indicated that the broadband remote sensing imagery has the capability to detect the disease. Some image indices such as RI 14, SDI 14 and SDI 24 worked better than others. A correlation coefficient above 0.62 indicated that these indices would be valuable to use for identification of the rice disease. In the validation analysis, we obtained a small root mean square error (RMS = 9.1), confirming the applicability of the developed method. Although the results were encouraging, it was difficult to discriminate healthy plants from light infection ones when DI severe levels (DI > 35). This phenomenon illustrated that remote sensing images with higher spectral resolution (more bands and narrower bandwidth) were required in order to further examine the capability of separating the light diseased plants from healthy plants.

Qin, Zhihao; Zhang, Minghua

2005-08-01

 
 
 
 
261

An experimental model for MRI-detected measurements of oxygen uptake in the lungs  

Science.gov (United States)

Oxygen, which is paramagnetic, influences the nuclear relaxation rate of helium-3, and can be the limiting factor when hyperpolarized (HP) gases are used as inhaled contrast agents in MR lung imaging. The decay rate of a HP 3He NMR signal, acquired during a single breath-hold, will thus change as oxygen is exchanged with the bloodstream. We model this effect in vitro using a time-varying magnetic field gradient to mimic oxygen uptake in the lung. The goal of the study is to investigate the expected accuracy and precision with which oxygen concentrations and uptake rates can be extracted from lung imaging experiments performed in vivo. Particular emphasis is placed on the effects of varying signal-to-noise ratio and acquisition time. These experiments are expected to inform developments in the field of hyperpolarized gas MRI, and may lead to new tools for the treatment and detection of lung diseases and disorders. Keywords: Low-field NMR; Oxygen uptake; Lung model; Diffusion; Relaxation.

Cogswell, Sebastian

262

Contextualizing Neuro-Collaborations: Reflections on a Transdisciplinary fMRI Lie Detection Experiment  

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Full Text Available Recent neuroscience initiatives (including the E.U.’s Human Brain Project and the U.S.’s BRAIN Initiative have reinvigorated discussions about the possibilities for transdisciplinary collaboration between the neurosciences, the social sciences, and the humanities. As STS scholars have argued for decades, however, such inter- and transdisciplinary collaborations are potentially fraught with tensions between researchers. This essay build on such claims by arguing that the tensions of transdisciplinary research also exist within researchers’ own experiences of working between disciplines – a phenomenon that we call ‘Disciplinary Double Consciousness’ (DDC. Building on previous work that has characterized similar spaces (and especially on the Critical Neuroscience literature, we argue that ‘neuro-collaborations’ inevitably engage researchers in DDC – a phenomenon that allows us to explore the useful dissonance that researchers can experience when working between a “home” discipline and a secondary discipline. Our case study is a five-year case study in fMRI lie detection involving a transdisciplinary research team made up of social scientists, a neuroscientist, and a humanist. In addition to theorizing neuro-collaborations from the inside-out, this essay presents practical suggestions for developing transdisciplinary infrastructures that could support future neuro-collaborations.

Melissa M. Littlefield

2014-03-01

263

Tumorsize dependent detection rate of endorectal MRI of prostate cancer-A histopathologic correlation with whole-mount sections in 70 patients with prostate cancer  

International Nuclear Information System (INIS)

Purpose: To evaluate the value of T2w endorectal MRI (eMRI) for correct detection of tumor foci within the prostate regarding tumor size. Materials and Methods: 70 patients with histologically proven prostate cancer were examined with T2w eMRI before radical prostatectomy at a 1.5 T scanner. For evaluation of eMRI, two radiologists evaluated each tumor focus within the gland. After radical prostatectomy, the prostates were prepared as whole-mount sections, according to transversal T2w eMRI. For each slice, tumor surroundings were marked and compared with eMRI. Based on whole-mount section, 315 slices were evaluated and 533 tumor lesions were documented. Results: Based on the T2w eMRI, 213 tumor lesions were described. In 137/213, histology could prove these lesions. EMRI was able to visualize 0/56 lesions with a maximum size of 2 cm 50/56 (89%). False positive eMRI findings were: 2 cm n = 2. Conclusion: T2w eMRI cannot exclude prostate cancer with lesions smaller 10 mm and 0.4 cm3 respectively. The detection rate for lesions more than 20 mm (1.6 cm3) is to be considered as high.

264

The research on island change detection techniques of multiple-band oriented high resolution remote sensing image  

Science.gov (United States)

Digital change detection is the computerized process of identifying changes in the state of an object, or other earthsurface features, between different data. During the last years, a large number of change detection methods have evolved that differ widely in refinement, robustness and complexity. Some traditional change detection methods could not any more adapt to high resolution remote sensing images. The prime tendency of remote sensing change detection is from pixels level to object level. In the paper, with respect to the views of object-oriented change detection in remote sensing images, an unsupervised technique for change detection (CD) in very high geometrical resolution images is proposed, which is based on the use of morphological filters. This technique integrates the nonlinear and adaptive properties of the morphological filters with a change vector analysis (CVA) procedure. Different morphological operators are analyzed and compared with respect to the CD problem. Alternating sequential filters by reconstruction proved to be the most effective, permitting the preservation of the geometrical information of the structures in the scene while filtering the homogeneous areas. We collect two multi-temporal SPOT5 remote sensing images to analyze YangSan island change detection in this procedure as above mentioned. Experimental results confirm the effectiveness of the proposed technique. It increases the accuracy of the CD in high remote sensing change detection as compared with the standard CVA approach.

Zhang, HanSong; Wang, Difeng; Pan, Delu

2009-07-01

265

A technique to reduce motion artifact for externally triggered cine-MRI(EC-MRI) based on detecting the onset of the articulated word with spectral analysis  

International Nuclear Information System (INIS)

One issue in externally triggered cine-magnetic resonance imaging (EC-MRI) for the dynamic observation of speech organs is motion artifact in the phase-encoding direction caused by unstable repetitions of speech during data acquisition. We propose a technique to reduce such artifact by rearranging the k-space data used to reconstruct MR images based on the analysis of recorded speech sounds. We recorded the subject's speech sounds during EC-MRI and used post hoc acoustical processing to reduce scanning noise and detect the onset of each utterance based on analysis of the recorded sounds. We selected each line of k-space from several data acquisition sessions and rearranged them to reconstruct a new series of dynamic MR images according to the analyzed time of utterance onset. Comparative evaluation showed significant reduction in motion artifact signal in the dynamic MR images reconstructed by the proposed method. The quality of the reconstructed images was sufficient to observe the dynamic aspects of speech production mechanisms. (author)

266

Sensitivity and specificity of interictal EEG-fMRI for detecting the ictal onset zone at different statistical thresholds.  

Directory of Open Access Journals (Sweden)

Full Text Available There is currently a lack of knowledge about EEG-fMRI specificity. Our aim was to define sensitivity and specificity of Blood Oxygen Level Dependent (BOLD responses to interictal epileptic spikes during EEG-fMRI for detecting the ictal onset zone (IOZ. We studied 21 refractory focal epilepsy patients who had a well-defined IOZ after a full presurgical evaluation and interictal spikes during EEG-fMRI. Areas of spike-related BOLD changes overlapping the IOZ in patients were considered as true positives; if no overlap was found, they were treated as false negatives. Matched healthy case-controls underwent similar EEG-fMRI in order to determine true negative and false positive fractions. The spike-related regressor of the patient was used in the design matrix of the healthy case-control. Suprathreshold BOLD changes in the brain of controls were considered as false positives, absence of these changes as true negatives. Sensitivity and specificity were calculated for different statistical thresholds at the voxel level combined with different cluster size thresholds and represented in receiver operating characteristic (ROC-curves. Additionally, we calculated the ROC-curves based upon the cluster containing the maximal significant activation. We achieved a combination of 100% specificity and 62% sensitivity, using a Z-threshold in the interval 3.4-3.5 and cluster size threshold of 350 voxels. We could obtain higher sensitivity at the expense of specificity. Similar performance was found when using the cluster containing the maximal significant activation. Our data provide a guideline for different EEG-fMRI settings with their respective sensitivity and specificity for detecting the ictal onset zone. The unique cluster containing the maximal significant BOLD activation was a sensitive and specific marker of the ictal onset zone.

SimonTousseyn

2014-07-01

267

Comparison of X-ray, CT and MRI in detection of abnormal sacroiliac joint changes in patients with early stage of ankylosing spondylitis  

International Nuclear Information System (INIS)

Objective: To compare X-ray, CT, and MRI in detection of abnormal sacroiliac joint changes in patients with early stage of ankylosing spondylitis (AS). Methods: Fifty-three patients with clinical suspected early stage of AS underwent X-ray and MRI scan. MR scan sequences for the sacroiliac joints consisted of T1-weighted, T2-weighted, short time inversion recovery (STIR) and three dimensional balance turbo field echo with water selective excitation (3D-BTFE-WATS) in all patients. In 24 of the patients, fat-saturated contrast-enhanced T1-weighted was used. Twenty-five of 53 patients underwent CT scan. The Chi-square test was used to analyse the uniformity of bone erosions detected by X-ray, CT, and MRI. Results: Of the 106 sacroiliac joints in 53 patients, 16 sacroiliac joints with bone erosions were detected by X-ray and 63 sacroiliac joints by MRI. Of the 50 sacroiliac joints in 25 patients, 26 sacroiliac joints with bone erosions were found by CT. With regard to the detection of bone erosions, there was no difference between Cf and MRI (?2=0.16, P>0.05) and there was significant difference between CT and X-ray or MRI and X-ray (?2=14.44 and 17.36, P<0.05). 3D-BTFE-WATS was better than other sequences in detection of bone erosions. Acute inflammatory changes were determined by MRI, which included subchondral bone marrow edema in 32 patients, synovitis in 35 patients, fat depositions in 16 patients, enthesitis in 15 patients, capsulitis in 9 patients, and cartilaginous disruption in 31 patients. Conclusions: MRI can detect acute inflammatory changes that can not display by X-ray and CT. Compared with radiography and CT, MRI is more useful in detection of abnormal sacroiliac joint changes in patients with early stage of AS. (authors)

268

Comparison of Technetium-99m-MIBI imaging with MRI for detection of spine involvement in patients with multiple myeloma  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Recently, radiopharmaceutical scanning with Tc-99m-MIBI was reported to depict areas with active bone disease in multiple myeloma (MM) with both high sensitivity and specificity. This observation was explained by the uptake of Tc-99m-MIBI by neoplastic cells. The present investigation evaluates whether Tc-99m-MIBI imaging and magnetic resonance imaging (MRI) perform equally well in detecting myelomatous bone marrow lesions. Methods In 21 pati...

Koehn Horst; Knoll Peter; Bergmayer Walter; Keck Andrea; Filipits Martin; Mirzaei Siroos; Ludwig Heinz; Pecherstorfer Martin

2003-01-01

269

Reversible data hiding for tampering detection in remote sensing images using histogram shifting  

Science.gov (United States)

This paper presents a reversible fragile data hiding scheme for tampering detection in remote sensing images based on the histogram shifting approach. The image to be protected is divided into blocks of a reduced size and a subset of the image bands are selected for embedding. Instead of using the histogram of each separate band, the shifting process is applied to the histogram of the maximum component (or infinity norm) of the vectors obtained with the selected bands. The proposed approach is reversible and thus, the original image can be fully recovered once it has been authenticated. The method is designed to detect specific forged blocks (areas) of the protected image and is shown to succeed to detect copy and replace attacks. In addition, the experimental results, presented for the Cuprite AVIRIS image, show that the method yields extremely high transparency, with PSNR larger than 100 dB prior to reversing the scheme and recovering the original image.

Serra-Ruiz, Jordi; Megias, David

2012-10-01

270

Remote detection of methane with a 1.66-microm diode laser.  

Science.gov (United States)

High-sensitivity real-time remote detection of methane in air with a 1.66-microm distributed-feedback diode laser operating at room temperature is demonstrated by laboratory simulations. The laser current was modulated at a high frequency of ~5 MHz, and the laser-center frequency was locked onto a methane-absorption line. The laser light directed toward the probed region was received after one-way transmission or further reflection from a topographic target. The methane absorption was detected by the second-harmonic component in the optical-power variation. The minimum-detectable concentration-path-length product in the transmission scheme was 0.3 part in 10(6) m for a signal averaging time of 1.3 s. In the reflection scheme, the amount of methane could be measured from the ratio of the fundamental and second-harmonic signal intensities independently of the received power. PMID:20720687

Uehara, K; Tai, H

1992-02-20

271

A progressive processing method for breast cancer detection via UWB based on an MRI-derived model  

Science.gov (United States)

Ultra-wideband (UWB) microwave imaging is a promising method for breast cancer detection based on the large contrast of electric parameters between the malignant tumor and its surrounded normal breast organisms. In the case of multiple tumors being present, the conventional imaging approaches may be ineffective to detect all the tumors clearly. In this paper, a progressive processing method is proposed for detecting more than one tumor. The method is divided into three stages: primary detection, refocusing and image optimization. To test the feasibility of the approach, a numerical breast model is developed based on the realistic magnetic resonance image (MRI). Two tumors are assumed embedded in different positions. Successful detection of a 3.6 mm-diameter tumor at a depth of 42 mm is achieved. The correct information of both tumors is shown in the reconstructed image, suggesting that the progressive processing method is promising for multi-tumor detection.

Xiao, Xia; Song, Hang; Wang, Zong-Jie; Wang, Liang

2014-07-01

272

Beyond blood brain barrier breakdown – in vivo detection of occult neuroinflammatory foci by magnetic nanoparticles in high field MRI  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Gadopentate dimeglumine (Gd-DTPA enhanced magnetic resonance imaging (MRI is widely applied for the visualization of blood brain barrier (BBB breakdown in multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE. Recently, the potential of magnetic nanoparticles to detect macrophage infiltration by MRI was demonstrated. We here investigated a new class of very small superparamagnetic iron oxide particles (VSOP as novel contrast medium in murine adoptive-transfer EAE. Methods EAE was induced in 17 mice via transfer of proteolipid protein specific T cells. MR images were obtained before and after application of Gd-DTPA and VSOP on a 7 Tesla rodent MR scanner. The enhancement pattern of the two contrast agents was compared, and correlated to histology, including Prussian Blue staining for VSOP detection and immunofluorescent staining against IBA-1 to identify macrophages/microglia. Results Both contrast media depicted BBB breakdown in 42 lesions, although differing in plaques appearances and shapes. Furthermore, 13 lesions could be exclusively visualized by VSOP. In the subsequent histological analysis, VSOP was localized to microglia/macrophages, and also diffusely dispersed within the extracellular matrix. Conclusion VSOP showed a higher sensitivity in detecting BBB alterations compared to Gd-DTPA enhanced MRI, providing complementary information of macrophage/microglia activity in inflammatory plaques that has not been visualized by conventional means.

Schnorr Joerg

2009-08-01

273

Structural health monitoring of wind towers: remote damage detection using strain sensors  

International Nuclear Information System (INIS)

Exploiting wind energy in complex sites like mountain terrains implies the necessity for remote structural health monitoring of the wind towers. In fact, such slender vertical structures exposed to wind may experience large vibrations and repeated stress cycles leading to fatigue cracking. Possible strategies for remote fatigue damage detection are investigated. Specifically, this paper is focused on the use of suitable strain sensors for crack detection in critical sites of the structure, suggesting several strategies taking into account the possibility of wind direction changes and/or wind calm phases. They are based on a radial arrangement of strain sensors around the tower periphery in the vicinity of the base weld joint. The most promising strategy uses the strain difference between adjacent strain sensors as an index of the presence of a crack. The number of sensors to be installed is dictated by the minimum crack size to be detected, which in turn depends on the expected extreme wind conditions and programmed inspection/repair schedule for the structure

274

Oil spill detection and remote sensing : an overview with focus on recent events  

International Nuclear Information System (INIS)

Several offshore oil spills occurred during the period from November to December 2007 in various parts of the world, each highlighting the need of quickly detect oil spills in marine settings. Several factors must be considered in order to determine the best technical approach for successful detection and oil spill monitoring. These include the reason for detection or monitoring; the location of the spill; the scale of spatial coverage; availability of detection equipment and time to deploy; high specificity for petroleum oil; weather conditions at and above the spill site; and cost of the detection approach. This paper outlined some of the key attributes of several remote sensing options that are available today or being considered. The approaches used to enhance visualization or detection of spills include traditional electromagnetic spectrum-based approaches such as ultra violet (UV), visible, infra-red (IR), radar, and fluorescence-based systems. Analytical approaches such as chemical analysis for the detection of volatile organic compounds (VOCs) or monitoring of electrical conductivity of the water surface may also provide a warning that hydrocarbons have been released. 12 refs., 3 tabs., 11 figs

275

AIRBORNE, OPTICAL REMOTE SENSING OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION  

Energy Technology Data Exchange (ETDEWEB)

Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. This second six-month technical report summarizes the progress made towards defining, designing, and developing the hardware and software segments of the airborne, optical remote methane and ethane sensor. The most challenging task to date has been to identify a vendor capable of designing and developing a light source with the appropriate output wavelength and power. This report will document the work that has been done to identify design requirements, and potential vendors for the light source. Significant progress has also been made in characterizing the amount of light return available from a remote target at various distances from the light source. A great deal of time has been spent conducting laboratory and long-optical path target reflectance measurements. This is important since it helps to establish the overall optical output requirements for the sensor. It also reduces the relative uncertainty and risk associated with developing a custom light source. The data gathered from the optical path testing has been translated to the airborne transceiver design in such areas as: fiber coupling, optical detector selection, gas filters, and software analysis. Ophir will next, summarize the design progress of the transceiver hardware and software development. Finally, Ophir will discuss remaining project issues that may impact the success of the project.

Jerry Myers

2003-11-12

276

A Dual-Mode UWB Wireless Platform with Random Pulse Length Detection for Remote Patient Monitoring  

DEFF Research Database (Denmark)

This paper presents a dual-mode ultra-wideband platform for wireless Remote Patient Monitoring (RPM). Existing RPM solutions are typically based on two different hardware platforms; one responsible for medical-data monitoring and one to handle data transmission. The proposed RPM topology is based on a single hardware platform, but it is capable of both monitoring and data transmission. This is achieved by employing a new random pulse length detection method that allows data transmission by using a modulated monitoring signal. To prove the proposed concept a test system has been built, using commercial equipment, and satisfactory results are obtained.

Reyes, Carlos; Bisbe, Sergi

2013-01-01

277

An Echelle Grating Spectrometer (EGS) for mid-IR remote chemical detection  

Energy Technology Data Exchange (ETDEWEB)

The availability of high performance two-dimensional InSb detectors enables the design and construction of mid-infrared spectrographs capable of obtaining high resolution spectra over extended spectral regions without moving components. Rugged, stable, cryo-cooled spectrographs suitable for remote field operation are now possible using prism-echelle cross dispersion designs. The authors discuss the design, fabrication, and performance of a high resolution mid-IR field spectrograph designed specifically for the detection of atmospheric-borne chemicals from airborne platforms. The instrument design provides maximum optical throughput covering the two atmospheric windows at 2.0-2.5 pm and 3.0-4.2 pm.

Stevens, C.G.; Thomas, N.; Kuzmenko, P.; Alger, T.

1994-07-01

278

Comparison of abdominal MRI with diffusion-weighted imaging to 68Ga-DOTATATE PET/CT in detection of neuroendocrine tumors of the pancreas  

International Nuclear Information System (INIS)

The aim of the study was to evaluate contrast-enhanced MRI, diffusion-weighted MRI (DW MRI), and 68Ga-DOTATATE positron emission tomography (PET)/CT in the detection of intermediate to well-differentiated neuroendocrine tumors (NET) of the pancreas. Eighteen patients with pathologically proven pancreatic NET who underwent MRI including DW MRI and PET/CT within 6 weeks of each other were included in this retrospective study. Two radiologists evaluated T2-weighted (T2w), T2w + DW MRI, T2w + contrast-enhanced T1-weighted (CE T1w) MR images, and PET/CT for NET detection. The sensitivity and level of diagnostic confidence were compared among modalities using McNemar's test and a Wilcoxon signed rank test. Apparent diffusion coefficients (ADC) of pancreatic NETs and normal pancreatic tissue were compared with Student's t test. Of the NETs, 8/23 (34.8 %) and 9/23 (39.1 %) were detected on T2w images by observers 1 and 2, respectively. Detection rates improved significantly by combining T2w images with DW MRI (observer 1: 14/23 = 61 %; observer 2: 15/23 = 65.2 %; p -3 mm2/s) was statistically significantly lower than that of normal pancreatic tissue (1.48 ± 0.39 x 10-3 mm2/s). DW MRI is a valuable adjunct to T2w imaging and comparable to CE T1w imaging in pancreatic NET detection, quantitatively differentiating between NET and normal pancreatic tissue with ADC measurements. 68Ga-DOTATATE PET/CT is more sensitive than MRI in the detection of pancreatic NET. (orig.)

279

Early detection of antiangiogenic treatment responses in a mouse xenograft tumor model using quantitative perfusion MRI.  

Science.gov (United States)

Angiogenesis plays a major role in tumor growth and metastasis, with tumor perfusion regarded as a marker for angiogenesis. To evaluate antiangiogenic treatment response in vivo, we investigated arterial spin labeling (ASL) magnetic resonance imaging (MRI) to measure tumor perfusion quantitatively. Chronic and 24-h acute treatment responses to bevacizumab were assessed by ASL and dynamic-contrast-enhanced (DCE) MRI in the A498 xenograft mouse model. After the MRI, tumor vasculature was assessed by CD34 staining. After 39 days of chronic treatment, tumor perfusion decreased to 44.8 ± 16.1 mL/100 g/min (P ASL MRI would be valuable for longitudinal assessment of tumor perfusion and in translation from animal models to human. PMID:24403176

Rajendran, Reshmi; Huang, Wei; Tang, Annie Mei Yee; Liang, Jie Ming; Choo, Stephanie; Reese, Torsten; Hentze, Hannes; van Boxtel, Susan; Cliffe, Adam; Rogers, Keith; Henry, Brian; Chuang, Kai Hsiang

2014-02-01

280

Detecting network modules in fMRI time series: A weighted network analysis approach  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Many network analyses of fMRI data begin by defining a set of regions, extracting the mean signal from each region and then analyzing the correlations between regions. One essential question that has not been addressed in the literature is how to best define the network neighborhoods over which a signal is combined for network analyses. Here we present a novel unsupervised method for the identification of tightly interconnected voxels, or modules, from fMRI data. This approach, weighted voxel...

Mumford, Jeanette A.; Horvath, Steve; Oldham, Michael C.; Langfelder, Peter; Geschwind, Daniel H.; Poldrack, Russell A.

2010-01-01

 
 
 
 
281

Detection of an occult transclival cerebrospinal fluid fistula by CT and MRI  

International Nuclear Information System (INIS)

We describe an unusual occult transclival cerebrospinal fluid (CSF) fistula to the sphenoid sinus demonstrated by MRI. CT was performed because of a posterior cerebral infarct caused by cardiac arrhythmia. Axial sections showed fluid in the sphenoid sinus. High-resolution scans revealed a bony defect 3 mm in diameter of the posterior wall of the sphenoid sinus, and MRI showed a transclival CSF fistula. This occult lesion was confirmed by surgery and duraplasty was successfully performed via an endonasal approach. (orig.)

282

Early Alzheimer Disease Detection by Bag of Visual Words and Hybrid Fusion on Structural Brain MRI  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, we tackle the problem of recognition of Alzheimer's disease (AD) in structural MRI images using visual similarity. AD yields visible changes in the brain structures. We aim to recognize patient category such as AD, or prodromal stage of the AD called Mild Cognitive impairment (MCI), or normal control subject (NC).We use visual local descriptors and the bag of words approach on the most involved regions in AD (Hippocampus and PosteriorCingulate Cortex ) in MRI images. The Conten...

Ben Ahmed, Olfa; Benois-pineau, Jenny; Chokri Ben, Amar; Allard, Miche?le; Catheline, Gwenaelle

2013-01-01

283

CT detection of basal ganglion lesions in neurofibromatosis type 1: correlation with MRI  

International Nuclear Information System (INIS)

Prospective study of CT and MRI in 41 consecutive children with suspected type 1 neurofibromatosis revealed basal ganglion lesions on T2-weighted spin echo images in 22 cases (54%) and on CT in only 7 of those (32%). T2-weighted spin-echo MRI also revealed multiple signal changes in the supra- and infratentorial white matter and brain stem that went completely unnoticed on CT. (orig.)

284

Impact of functional MRI data preprocessing pipeline on default-mode network detectability in patients with disorders of consciousness.  

Science.gov (United States)

An emerging application of resting-state functional MRI (rs-fMRI) is the study of patients with disorders of consciousness (DoC), where integrity of default-mode network (DMN) activity is associated to the clinical level of preservation of consciousness. Due to the inherent inability to follow verbal instructions, arousal induced by scanning noise and postural pain, these patients tend to exhibit substantial levels of movement. This results in spurious, non-neural fluctuations of the rs-fMRI signal, which impair the evaluation of residual functional connectivity. Here, the effect of data preprocessing choices on the detectability of the DMN was systematically evaluated in a representative cohort of 30 clinically and etiologically heterogeneous DoC patients and 33 healthy controls. Starting from a standard preprocessing pipeline, additional steps were gradually inserted, namely band-pass filtering (BPF), removal of co-variance with the movement vectors, removal of co-variance with the global brain parenchyma signal, rejection of realignment outlier volumes and ventricle masking. Both independent-component analysis (ICA) and seed-based analysis (SBA) were performed, and DMN detectability was assessed quantitatively as well as visually. The results of the present study strongly show that the detection of DMN activity in the sub-optimal fMRI series acquired on DoC patients is contingent on the use of adequate filtering steps. ICA and SBA are differently affected but give convergent findings for high-grade preprocessing. We propose that future studies in this area should adopt the described preprocessing procedures as a minimum standard to reduce the probability of wrongly inferring that DMN activity is absent. PMID:23986694

Andronache, Adrian; Rosazza, Cristina; Sattin, Davide; Leonardi, Matilde; D'Incerti, Ludovico; Minati, Ludovico

2013-01-01

285

Full automatic fiducial marker detection on coil arrays for accurate instrumentation placement during MRI guided breast interventions  

Science.gov (United States)

With its high sensitivity, dynamic contrast-enhanced MR imaging (DCE-MRI) of the breast is today one of the first-line tools for early detection and diagnosis of breast cancer, particularly in the dense breast of young women. However, many relevant findings are very small or occult on targeted ultrasound images or mammography, so that MRI guided biopsy is the only option for a precise histological work-up [1]. State-of-the-art software tools for computer-aided diagnosis of breast cancer in DCE-MRI data offer also means for image-based planning of biopsy interventions. One step in the MRI guided biopsy workflow is the alignment of the patient position with the preoperative MR images. In these images, the location and orientation of the coil localization unit can be inferred from a number of fiducial markers, which for this purpose have to be manually or semi-automatically detected by the user. In this study, we propose a method for precise, full-automatic localization of fiducial markers, on which basis a virtual localization unit can be subsequently placed in the image volume for the purpose of determining the parameters for needle navigation. The method is based on adaptive thresholding for separating breast tissue from background followed by rigid registration of marker templates. In an evaluation of 25 clinical cases comprising 4 different commercial coil array models and 3 different MR imaging protocols, the method yielded a sensitivity of 0.96 at a false positive rate of 0.44 markers per case. The mean distance deviation between detected fiducial centers and ground truth information that was appointed from a radiologist was 0.94mm.

Filippatos, Konstantinos; Boehler, Tobias; Geisler, Benjamin; Zachmann, Harald; Twellmann, Thorsten

2010-02-01

286

Remote Field Eddy Current Probes for the Detection of Stress Corrosion in Transmission Pipelines  

Energy Technology Data Exchange (ETDEWEB)

Magnetic flux leakage (MFL) is a technique used widely in non-destructive testing (NDT) of natural gas and petroleum transmission pipelines. This inspection method relies on magnetizing the pipe-wall in axial direction. The MFL inspection tool is equipped with an array of Hall sensors located around the circumference of the pipe, which registers the flux leakage caused by any defects present in the pipe-wall. Currently, the tool magnetizes the pipewall in axial direction making it largely insensitive to axially oriented defects. One type of defect, which is of a growing concern in the gas and petroleum industry is the stress corrosion crack (SCC). The SCCs are a result of aging, corrosion, fatigue and thermal stresses. SCCs are predominantly axially oriented and are extremely tight, which makes them impossible to be detected using current inspection technology. A possible solution to this problem is to utilize the remote field eddy current (RFEC) effect to detect axially oriented defects. The RFEC method has been widely used in industry in the inspection of tubular products. The method uses a pair of excitation and pick-up coils. The pick-up coil located in the remote field region, usually two, three pipe-diameters away from the excitation coil. With RFEC the presence of defects is detected by the disturbance in the phase of the signal measured by the pick-up coil relative to that of the excitation coil. Unlike conventional eddy current testing the RFEC method is sensitive to defects on the exterior of the inspected product, which makes it a good candidate for the development of in-line inspection technology. This work focuses on the development of non-destructive testing technique, which uses remote field eddy currents induced by rotating magnetic field (RMF). A major advantage of the RMF is that it makes possible to not only detect a defect but also localize its position in circumferential direction. Also, it could potentially allow detection of defects, regardless of their shape and orientation. In this work the RFEC-RMF technique is investigated and is shown to be a useful tool in the detection of axially oriented, circumferentially oriented and skewed notches, SCCs and round defects. Finally, a data acquisition system is designed, capable of performing the RFEC-RMF measurements automatically.

Plamen Alexandroz Ivanov

2002-08-27

287

Stress cine MRI for detection of coronary artery disease; Stress-Cine-MRT zur Primaeridagnostik der koronaren Herzkrankheit  

Energy Technology Data Exchange (ETDEWEB)

Stress testing is the cornerstone in the diagnosis of patients with suspected coronary artery disease (CAD). Stress echocardiography has become a well-established modality for the detection of ischemia-induced wall motion abnormalities. However, display and reliable interpretation of stress echocardiography studies are user-dependent, the test reproducibility is low, and 10 to 15% of patients yield suboptimal or non-diagnostic images. Due to its high spatial and contrast resolution, MRI is known to permit an accurate determination of left ventricular function and wall thickness at rest. Early stress MRI studies provided promising results with respect to the detection of CAD. However, the clinical impact was limited due to long imaging time and problematic patient monitoring in the MRI environment. Recent technical improvements - namely ultrafast MR image acquisition - led to a significant reduction of imaging time and improved patient safety. Stress can be induced by physical exercise or pharmacologically by administration of a beta{sub 1}-agonist (dobutamine) or vasodilatator (dipyridamole and adenosine). The best developed and most promising stress MRI technique is a high-dose dobutamine/atropine stress protocol (10, 20, 30, 40 {mu}g/kg/min; optionally 0.25-mg fractions of atropine up to maximal dose 1 mg). Severe complications (myocardial infarction, ventricular fibrillation and sustained tachycardia, cardiogenic shock) may be expected in 0.25% of patients. Currently, data of three high-dose dobutamine stress MRI studies are available, revealing a good sensitivity (83 - 87%) and specificity (83 - 86%) in the assessment of CAD. The direct comparison between echocardiography and MRI for the detection of stress-induced wall motion abnormalities yielded better results for dobutamine-MRI in terms of sensitivity (86.2% vs. 74.3%; p < 0.05) and specificity (85.7% vs. 69.8% p < 0.05) as compared to dobutamine stress echocardiography. The superior results of MRI can mainly be explained by the better image quality with sharp delineation of the endocardial and epicardial borders. Currently, stress MRI is already a realistic clinical alternative for the non-invasive assessment of CAD in patients with impaired image quality in echocardiography. (orig.) [German] Belastungsuntersuchungen sind einer der wesentlichen Pfeiler der nicht-invasiven Diagnostik der koronaren Herzkrankheit (KHK). Die Stress-Cine-Magnetresonanztomographie (Stress-MRT) beruht wie die Stressechokardiographie auf dem direkten Nachweis ischaemieinduzierter Wandbewegungsstoerungen. Ihr Einsatz bei kardialen Belastungsuntersuchungen wurde bisher vor allem durch die langen Untersuchungszeiten und die limitierten Ueberwachungsmoeglichkeiten der Patienten eingeschraenkt. Erst seit kurzem wurden durch technische Weiterentwicklungen (insbesondere ultraschnelle k-Raum-segmentierte Sequenzen) die wesentlichen Rahmenbedingungen fuer eine klinisch praktikable kardiale MRT-Belastungsdiagnostik geschaffen. Als Stress-Induktoren koennen physikalische (Fahrradergometrie) und pharmakologische Belastungsverfahren ({beta}{sub 1}-Mimetika [Dobutamin] oder Vasodilatatoren [Dipyridamol, Adenosin]) eingesetzt werden. Insbesondere seit der Etablierung von Hochdosis-Protokollen mit fakultativer Atropingabe wird die Belastung mit Dobutamin bei der Stress-MRT zum Nachweis einer KHK (Sensitivitaet: 83 - 87%; Spezifitaet: 83 - 86%) von den meisten Arbeitsgruppen favorisiert. Schwerere Komplikationen treten in 0,25% der Faelle auf. Im direkten Vergleich zeigte sich die Dobutamin-Stress-MRT aufgrund der besseren Bildqualitaet der Dobutamin-Stressechokardiographie ueberlegen (Sensitivitaet: 86,2% vs. 74,3%, p < 0,05; Spezifitaet: 85,7% vs. 69,8%, p < 0,05). Die Stress-MRT ist bereits zum jetzigen Zeitpunkt eine realistische - in der Routinediagnostik anwendbare - Alternative zur Stressechokardiographie. Vom Einsatz der Stress-MRT profitieren zur Zeit v.a. Patienten, bei denen aufgrund grundsaetzlich schlechter Schallbarkeit mit hoher Wahrscheinlichkeit von nicht oder nur eingeschra

Sommer, T.; Hofer, U.; Schild, H. [Bonn Univ. (Germany). Radiologische Klinik; Omran, H. [Medizinische Universitaetsklinik II Bonn (Germany)

2002-05-01

288

Detection of damaged forest by tomicus piniperda using multiple types of remote sensing data  

Science.gov (United States)

This paper analyzed the damaged forest by tomicus piniperda using multiple types of remote sensing data such as TM, CBERS-1, AVHRR and MODIS data. It selected a typical region including heavy damaged and healthy forest. The region was located by GPS (Global Position System). Then the spectral features of the above remote sensing data (March, 2001) were given. It indicates that the values of healthy forest of TM NIR band (0.76-0.9 ) and SWIR band (1.55-1.75 ) are distinctly greater than those of damaged forest. The values of CBERS-1 NIR bands (0.77-0.89 ), AVHRR bands (0.725-1.0 ) and MODIS bands (0.841-0.876 ) behave in the same pattern with TM. Otherwise, the values of MODIS thermal bands (3.929-3.89 , 10.78-11.28 and 11.77-12.27 ) of damaged forest are distinctly greater than those of healthy forest. The AVHRR thermal bands are not so. Finally, two detection models were put forward according to the spectral changing characteristics. One was named Difference Rate (DR) model with NIR and VIR data, which applied for TM, CBERS-1, AVHRR and MODIS. DR is greater, the forest grow healthily. Basis on the typical sample, the different guidelines distinguished healthy and damaged forests are obtained. The other model was named Disaster Index (DI) model with thermal and NIR data, only suitable for MODIS. The guidelines of healthy and damaged forest are determined too. DI is greater the forest is stricken more badly. In conclusion, it will help monitoring and assessing the vermin occurrence and impact by remote sensing detection model.

Dong, Xieqiong; Feng, Xuezhi; Zhao, Shuhe; Yang, Xiaopeng; Liu, Hongping; Xu, Hong; Ke, Yinghai

2005-01-01

289

Cloud Detection Method Based on Feature Extraction in Remote Sensing Images  

Science.gov (United States)

In remote sensing images, the existence of the clouds has a great impact on the image quality and subsequent image processing, as the images covered with clouds contain little useful information. Therefore, the detection and recognition of clouds is one of the major problems in the application of remote sensing images. Present there are two categories of method to cloud detection. One is setting spectrum thresholds based on the characteristics of the clouds to distinguish them. However, the instability and uncertainty of the practical clouds makes this kind of method complexity and weak adaptability. The other method adopts the features in the images to identify the clouds. Since there will be significant overlaps in some features of the clouds and grounds, the detection result is highly dependent on the effectiveness of the features. This paper presented a cloud detection method based on feature extraction for remote sensing images. At first, find out effective features through training pattern, the features are selected from gray, frequency and texture domains. The different features in the three domains of the training samples are calculated. Through the result of statistical analysis of all the features, the useful features are picked up to form a feature set. In concrete, the set includes three feature vectors, respectively, the gray feature vector constituted of average gray, variance, first-order difference, entropy and histogram, the frequency feature vector constituted of DCT high frequency coefficient and wavelet high frequency coefficient, and the texture feature vector constituted of the hybrid entropy and difference of the gray-gradient co-occurrence matrix and the image fractal dimension. Secondly, a thumbnail will be obtained by down sampling the original image and its features of gray, frequency and texture are computed. Last but not least, the cloud region will be judged by the comparison between the actual feature values and the thresholds determined by the sample training process. Experimental results show that the clouds and ground objects can be separated efficiently, and our method can implement rapid clouds detection and cloudiness calculation.

Changhui, Y.; Yuan, Y.; Minjing, M.; Menglu, Z.

2013-05-01

290

Detection of hepatocellular carcinoma by Gd-EOB-DTPA-enhanced liver MRI: Comparison with triple phase 64 detector row helical CT  

International Nuclear Information System (INIS)

Purpose: To compare the diagnostic performance of Gd-EOB-DTPA-enhanced MRI with that of triple phase 64-MDCT in the detection of hepatocellular carcinoma (HCC). Patients and methods: Thirty-four patients with 52 surgically proven lesions underwent Gd-EOB-DTPA-enhanced MRI and triple phase 64-MDCT. Two observers independently evaluated MR and CT imaging on a lesion-by-lesion basis. Sensitivity, positive and negative predictive values and reproducibility were evaluated. The diagnostic accuracy of each modality was assessed with alternative-free response receiver operating characteristic (ROC) analysis. Results: Both observers showed higher sensitivity in detecting lesions with MRI compared to CT, however, only the difference between the two imaging techniques for observer 2 was significant (P = 0.034). For lesions 1 cm or smaller, MRI and CT showed equal sensitivity (both 62.5%) with one observer, and MRI proved superior to CT with the other observer (MRI 75% vs. CT 56.3%), but the latter difference was not significant (P = 0.083). The difference in positive and negative predictive value between the two imaging techniques for each observer was not significant (P > 0.05). The areas under the ROC curve for each observer were 0.843 and 0.861 for MRI vs. 0.800 and 0.833 for CT and the differences were not significant. Reproducibility was higher using MRI for both observers, but the result was not significant (MRI 32/33 vs. CT 29/33, P = 0.083). Conclusion: Gd-EOB-DTPA-enhanced MRI tended to show higher diagnostic accuracy, sensitivity and reproducibility compared to triple phase 64-MDCT in the detection of hepatocellular carcinoma, however statistical significance was not achieved.

291

Motif kernel generated by genetic programming improves remote homology and fold detection  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Protein remote homology detection is a central problem in computational biology. Most recent methods train support vector machines to discriminate between related and unrelated sequences and these studies have introduced several types of kernels. One successful approach is to base a kernel on shared occurrences of discrete sequence motifs. Still, many protein sequences fail to be classified correctly for a lack of a suitable set of motifs for these sequences. Results We introduce the GPkernel, which is a motif kernel based on discrete sequence motifs where the motifs are evolved using genetic programming. All proteins can be grouped according to evolutionary relations and structure, and the method uses this inherent structure to create groups of motifs that discriminate between different families of evolutionary origin. When tested on two SCOP benchmarks, the superfamily and fold recognition problems, the GPkernel gives significantly better results compared to related methods of remote homology detection. Conclusion The GPkernel gives particularly good results on the more difficult fold recognition problem compared to the other methods. This is mainly because the method creates motif sets that describe similarities among subgroups of both the related and unrelated proteins. This rich set of motifs give a better description of the similarities and differences between different folds than do previous motif-based methods.

Sætrom Pål

2007-01-01

292

The functional neuroanatomy of target detection: an fMRI study of visual and auditory oddball tasks.  

Science.gov (United States)

The neuronal response patterns that are required for an adequate behavioural reaction to subjectively relevant changes in the environment are commonly studied by means of oddball paradigms, in which occasional 'target' stimuli have to be detected in a train of frequent 'non-target' stimuli. The detection of such task-relevant stimuli is accompanied by a parietocentral positive component of the event-related potential, the P300. We performed EEG recordings of visual and auditory event-related potentials and functional magnetic resonance imaging (fMRI) when healthy subjects performed an oddball task. Significant increases in fMRI signal for target versus non-target conditions were observed in the supramarginal gyrus, frontal operculum and insular cortex bilaterally, and in further circumscribed parietal and frontal regions. These effects were consistent over various stimulation and response modalities and can be regarded as specific for target detection in both the auditory and the visual modality. These results therefore contribute to the understanding of the target detection network in human cerebral cortex and impose constraints on attempts at localizing the neuronal P300 generator. This is of importance both from a neurobiological perspective and because of the widespread application of the physiological correlates of target detection in clinical P300 studies. PMID:10601000

Linden, D E; Prvulovic, D; Formisano, E; Völlinger, M; Zanella, F E; Goebel, R; Dierks, T

1999-12-01

293

Similarity Measures of Remotely Sensed Multi-Sensor Images for Change Detection Applications  

Directory of Open Access Journals (Sweden)

Full Text Available Change detection of remotely sensed images is a particularly challenging task when the time series data come from different sensors. Indeed, many change indicators are based on radiometry measurements, used to calculate differences or ratios, that are no longer meaningful when the data have been acquired by different instruments. For this reason, it is interesting to study those indicators that do not rely completely on radiometric values. In this work a new approach is proposed based on similarity measures. A series of such measures is employed for automatic change detection of optical and SAR images and a comparison of their performance is carried out to establish the limits of their applicability and their sensitivity to the occurred changes. Initial results are promising and suggest similarity measures as possiblechange detectors in multi-sensor configurations.

Vito Alberga

2009-07-01

294

Change detection in remote sensing imagery based on multisimilarity measures fusion  

Science.gov (United States)

Detecting regions of change in multitemporal remote-sensing images of the same scene taken at different times is of widespread interest in recent years. In this paper, we propose a new change detection method based on a fusion of multisimilarity measures. This fusion is performed in the framework of the Dempster-Shafer evidence theory, which allows you to combine evidence from different sources and arrive at a degree of belief (represented by a belief function) that takes into account all the available evidence. The proposed algorithm is applied to airport change evaluation based on two popular Gray-textural similarity measures: grayscale difference and grayscale ratio. Experimental results confirm the effectiveness of the proposed method.

Huang, Weilin; Yang, Weidong

2009-10-01

295

Global dust Detection Index (GDDI); a new remotely sensed methodology for dust storms detection.  

Science.gov (United States)

Dust storm occurs frequently in arid and semi-arid areas of the world. This natural phenomenon, which is the result of stormy winds, raises a lot of dust from desert surfaces and decreases visibility to less than 1 km. In recent years the temporal frequency of occurrences and their spatial extents has been dramatically increased. West of Iran, especially in spring and summer, suffers from significant increases of these events which cause several social and economic problems. Detecting and recognizing the extent of dust storms is very important issue in designing warning systems, management and decreasing the risk of this phenomenon. As the process of monitoring and prediction are related to detection of this phenomenon and it's separation from other atmospheric phenomena such as cloud, so the main aim of this research is establishing an automated process for detection of dust masses. In this study 20 events of dust happened in western part of Iran during 2000-2011 have been recognized and studied. To the aim of detecting dust events we used satellite images of MODIS sensor. Finally a model based on reflectance and thermal infrared bands has been developed. The efficiency of this method has been checked using dust events. Results show that the model has a good performance in all cases. It also has the ability and robustness to be used in any dust storm forecasting and warning system. PMID:24406015

Samadi, Mehdi; Darvishi Boloorani, Ali; Alavipanah, Seyed Kazem; Mohamadi, Hossein; Najafi, Mohamad Saeed

2014-01-01

296

Development of radio frequency interference detection algorithms for passive microwave remote sensing  

Science.gov (United States)

Radio Frequency Interference (RFI) signals are man-made sources that are increasingly plaguing passive microwave remote sensing measurements. RFI is of insidious nature, with some signals low power enough to go undetected but large enough to impact science measurements and their results. With the launch of the European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) satellite in November 2009 and the upcoming launches of the new NASA sea-surface salinity measuring Aquarius mission in June 2011 and soil-moisture measuring Soil Moisture Active Passive (SMAP) mission around 2015, active steps are being taken to detect and mitigate RFI at L-band. An RFI detection algorithm was designed for the Aquarius mission. The algorithm performance was analyzed using kurtosis based RFI ground-truth. The algorithm has been developed with several adjustable location dependant parameters to control the detection statistics (false-alarm rate and probability of detection). The kurtosis statistical detection algorithm has been compared with the Aquarius pulse detection method. The comparative study determines the feasibility of the kurtosis detector for the SMAP radiometer, as a primary RFI detection algorithm in terms of detectability and data bandwidth. The kurtosis algorithm has superior detection capabilities for low duty-cycle radar like pulses, which are more prevalent according to analysis of field campaign data. Most RFI algorithms developed have generally been optimized for performance with individual pulsed-sinusoidal RFI sources. A new RFI detection model is developed that takes into account multiple RFI sources within an antenna footprint. The performance of the kurtosis detection algorithm under such central-limit conditions is evaluated. The SMOS mission has a unique hardware system, and conventional RFI detection techniques cannot be applied. Instead, an RFI detection algorithm for SMOS is developed and applied in the angular domain. This algorithm compares brightness temperature values at various incidence angles for a particular grid location. This algorithm is compared and contrasted with other algorithms present in the visibility domain of SMOS, as well as the spatial domain. Initial results indicate that the SMOS RFI detection algorithm in the angular domain has a higher sensitivity and lower false-alarm rate than algorithms developed in the other two domains.

Misra, Sidharth

297

Remote viewing with the artist Ingo Swann: neuropsychological profile, electroencephalographic correlates, magnetic resonance imaging (MRI), and possible mechanisms.  

Science.gov (United States)

In the present study, the artist Ingo Swann, who helped develop the process of remote viewing (awareness of distant objects or places without employing normal senses), was exposed during a single setting of 30 min. to specific patterns of circumcerebral magnetic fields that significantly altered his subjective experiences. Several times during subsequent days, he was asked to sit in a quiet chamber and to sketch and to describe verbally distant stimuli (pictures or places) beyond his normal senses. The proportions of unusual 7-Hz spike and slow wave activity over the occipital lobes per trial were moderately correlated (rho=.50) with the ratings of accuracy between these distal, hidden stimuli and his responses. A neuropsychological assessment and Magnetic Resonance Imaging indicated a different structural and functional organization within the parieto-occipital region of the subject's right hemisphere from organizations typically noted. The results suggest that this type of paranormal phenomenon, often dismissed as methodological artifact or accepted as proofs of spiritual existence, is correlated with neurophysiological processes and physical events. Remote viewing may be enhanced by complex experimentally generated magnetic fields designed to interact with the neuromagnetic "binding factor" of consciousness. PMID:12081299

Persinger, M A; Roll, W G; Tiller, S G; Koren, S A; Cook, C M

2002-06-01

298

Conventional radiography requires a MRI-estimated bone volume loss of 20% to 30% to allow certain detection of bone erosions in rheumatoid arthritis metacarpophalangeal joints  

DEFF Research Database (Denmark)

The aim of this study was to demonstrate the ability of conventional radiography to detect bone erosions of different sizes in metacarpophalangeal (MCP) joints of rheumatoid arthritis (RA) patients using magnetic resonance imaging (MRI) as the standard reference. A 0.2 T Esaote dedicated extremity MRI unit was used to obtain axial and coronal T1-weighted gradient echo images of the dominant 2nd to 5th MCP joints of 69 RA patients. MR images were obtained and evaluated for bone erosions according to the OMERACT recommendations. Conventional radiographs of the 2nd to 5th MCP joints were obtained in posterior-anterior projection and evaluated for bone erosions. The MRI and radiography readers were blinded to each other's assessments. Grade 1 MRI erosions (1% to 10% of bone volume eroded) were detected by radiography in 20%, 4%, 7% and 13% in the 2nd, 3rd, 4th and 5th MCP joint, respectively. Corresponding results for grade 2 erosions (11% to 20% of bone volume eroded) were 42%, 10%, 60% and 24%, and for grade 3 erosions (21% to 30% of bone volume eroded) 75%, 67%, 75% and 100%. All grade 4 (and above) erosions were detected on radiographs. Conventional radiography required a MRI-estimated bone erosion volume of 20% to 30% to allow a certain detection, indicating that MRI is a better method for detection and grading of minor erosive changes in RA MCP joints.

Ejbjerg, B.; Vestergaard, Aage Steen

2006-01-01

299

Laboratory insights into the detection of surface biosignatures by remote-sensing techniques  

Science.gov (United States)

With the progress of direct imaging techniques, it will be possible in the short or long-term future to retrieve more efficiently the information on the physical properties of the light reflected by rocky exoplanets (Traub et al., 2010). The search for visible-infrared absorption bands of peculiar gases (O2, CH4 etc.) in this light could give clues for the presence of life (Kaltenegger and Selsis, 2007). Even more uplifting would be the direct detection of life itself, on the surface of an exoplanet. Considering this latter possibility, what is the potential of optical remote-sensing methods to detect surface biosignatures? Reflected light from the surface of the Earth exhibits a strong surface biosignature in the form of an abrupt change of reflectance between the visible and infrared range of the spectrum (Seager et al., 2005). This spectral feature called "vegetation red-edge" is possibly the consequence of biological evolution selecting the right chemical structures enabling the plants to absorb the visible energy, while preventing them from overheating by reflecting more efficiently the infrared. Such red-edge is also found in primitive photosynthetic bacteria, cyanobacteria, that colonized the surface of the Earth ocean and continents billions of years before multicellular plants (Knacke, 2003). If life ever arose on an Earth-like exoplanet, one could hypothesize that some form of its surface-life evolves into similar photo-active organisms, also exhibiting a red-edge. In this paper, we will present our plan and preliminary results of a laboratory study aiming at precising the potentiality of remote sensing techniques in detecting such surface biosignatures. Using equipment that has been developed in our team for surface photometry studies (Pommerol 2011, Jost 2013, Pommerol 2013), we will investigate the reflectance spectra and bidirectional reflectance function of soils containing bacteria such as cyanobacteria, in various environmental conditions. We will also present our plan to incorporate polarization measurements, and particularly circular polarization, because it can be a marker of homochirality, which is supposed to be a universal property of life. Finally, the analyses of both biotic and abiotic materials will help to assess if (or in which peculiar conditions) remote sensing techniques can discriminate between false positive and strong biomarkers. Ultimately, these laboratory data can serve as reference data to guide and interpret future observations, paving the way for the detection of life on distant exoplanets.

Poch, O.; Pommerol, A.; Jost, B.; Roditi, I.; Frey, J.; Thomas, N.

2014-03-01

300

[The role of susceptibility-weighted MRI in detection of ruptured aneurysm in multiple aneurysms].  

Science.gov (United States)

Since 2008 till 2010 years 22 patients with multiple aneurysms were examined in Burdenko Neurosurgical Institute (Moscow, Russia). The series included 13 female and 9 male patients, age ranged from 28 to 62 years (mean 45 years). 68 aneurysms of different localization were discovered in these 22 patients. We also analyzed results of examination of 2 patients with solitary aneurysms in which SW-MRI was performed to confirm or exclude the fact of hemorrhage due to rupture of the aneurysm. All patients were operated microsurgically. SW-MRI is effective technique for identification of source of hemorrhage in patients with multiple aneurysms thus allowing selection of correct tactics of management. Information value of the method declines with increase of time after hemorrhage (over 2 years). SW-MRI enables verification of the fact of hemorrhage due to aneurysm in disputable cases (minimal non-specific clinical presentation, absence of hemorrhage verification). PMID:21793292

Khe?reddin, A S; Pronin, I N; Filatov, Iu M; Eliava, Sh Sh; Podoprigora, A E; Belousova, O B; Okishev, D N

2011-01-01

 
 
 
 
301

Morphological MRI criteria improve the detection of lymph node metastases in head and neck squamous cell carcinoma: multivariate logistic regression analysis of MRI features of cervical lymph nodes  

Energy Technology Data Exchange (ETDEWEB)

The aim was to evaluate whether morphological criteria in addition to the size criterion results in better diagnostic performance of MRI for the detection of cervical lymph node metastases in patients with head and neck squamous cell carcinoma (HNSCC). Two radiologists evaluated 44 consecutive patients in which lymph node characteristics were assessed with histopathological correlation as gold standard. Assessed criteria were the short axial diameter and morphological criteria such as border irregularity and homogeneity of signal intensity on T2-weighted and contrast-enhanced T1-weighted images. Multivariate logistic regression analysis was performed: diagnostic odds ratios (DOR) with 95% confidence intervals (95% CI) and areas under the curve (AUCs) of receiver-operating characteristic (ROC) curves were determined. Border irregularity and heterogeneity of signal intensity on T{sub 2}-weighted images showed significantly increased DORs. AUCs increased from 0.67 (95% CI: 0.61-0.73) using size only to 0.81 (95% CI: 0.75-0.87) using all four criteria for observer 1 and from 0.68 (95% CI: 0.62-0.74) to 0.96 (95% CI: 0.94-0.98) for observer 2 (p < 0.001). This study demonstrated that the morphological criteria border irregularity and heterogeneity of signal intensity on T2-weighted images in addition to size significantly improved the detection of cervical lymph nodes metastases. (orig.)

Bondt, R.B.J. de; Bakers, F.; Hofman, P.A.M. [Maastricht University Medical Center, Department of Radiology, Maastricht (Netherlands); Nelemans, P.J. [Maastricht University Medical Center, Department of Epidemiology, Maastricht (Netherlands); Casselman, J.W. [AZ St. Jan Hospital, Department of Radiology, Bruges (Belgium); Peutz-Kootstra, C. [Maastricht University Medical Center, Department of Pathology, Maastricht (Netherlands); Kremer, B. [Maastricht University Medical Center, Department of Otolaryngology/ Head and Neck Surgery, Maastricht (Netherlands); Beets-Tan, R.G.H. [Academic Hospital Maastricht, Department of Radiology, Maastricht (Netherlands)

2009-03-15

302

Morphological MRI criteria improve the detection of lymph node metastases in head and neck squamous cell carcinoma: multivariate logistic regression analysis of MRI features of cervical lymph nodes  

International Nuclear Information System (INIS)

The aim was to evaluate whether morphological criteria in addition to the size criterion results in better diagnostic performance of MRI for the detection of cervical lymph node metastases in patients with head and neck squamous cell carcinoma (HNSCC). Two radiologists evaluated 44 consecutive patients in which lymph node characteristics were assessed with histopathological correlation as gold standard. Assessed criteria were the short axial diameter and morphological criteria such as border irregularity and homogeneity of signal intensity on T2-weighted and contrast-enhanced T1-weighted images. Multivariate logistic regression analysis was performed: diagnostic odds ratios (DOR) with 95% confidence intervals (95% CI) and areas under the curve (AUCs) of receiver-operating characteristic (ROC) curves were determined. Border irregularity and heterogeneity of signal intensity on T2-weighted images showed significantly increased DORs. AUCs increased from 0.67 (95% CI: 0.61-0.73) using size only to 0.81 (95% CI: 0.75-0.87) using all four criteria for observer 1 and from 0.68 (95% CI: 0.62-0.74) to 0.96 (95% CI: 0.94-0.98) for observer 2 (p < 0.001). This study demonstrated that the morphological criteria border irregularity and heterogeneity of signal intensity on T2-weighted images in addition to size significantly improved the detection of cervical lymph nodes metastases. (orig.)

303

SQUID-Detected MRI at 132 Microtesla with T1 Contrast Weighted at10 Microtelsa-300 mT  

International Nuclear Information System (INIS)

T1-weighted contrast MRI with prepolarization was detected with a superconducting quantum interference device (SQUID). A spin evolution period in a variable field between prepolarization and detection enabled the measurement of T1 in fields between 1.7 (micro)T and 300 mT; T1 dispersion curves of agarose gel samples over five decades in frequency were obtained. SQUID detection at 5.6 kHz drastically reduces the field homogeneity requirements compared to conventional field cycling methods using Faraday coil detection. This allows T1 dispersion measurements to be easily combined with MRI, so that T1 in a wide range of fields can be used for tissue contrast. Images of gel phantoms with T1-weighted contrast at four different fields between 10 (micro)T and 300 mT demonstrated dramatic contrast enhancement in low fields. A modified inversion recovery technique further enhanced the contrast by selectively suppressing the signal contribution for a specific value of the low-field T1

304

Incremental Value of Diffusion Weighted and Dynamic Contrast Enhanced MRI in the Detection of Locally Recurrent Prostate Cancer after Radiation Treatment: Preliminary Results  

Science.gov (United States)

Objectives To assess the incremental value of diffusion-weighted and dynamic contrast-enhanced MRI to T2-weighted MRI in detecting locally recurrent prostate cancer after radiotherapy. Methods Twenty-four patients (median age, 70 years) with a history of radiotherapy-treated prostate cancer underwent multi-parametric MRI (MP-MRI) and transrectal prostate biopsy. Two readers independently scored the likelihood of cancer on a 1-5 scale, using T2WI alone and then adding DWI and DCE-MRI. Areas under receiver operating characteristic curves (AUCs) were estimated at the patient and prostate-side levels. The ADC from DW-MRI and the Ktrans, kep, ve, AUGC90 and AUGC180 from DCE-MRI were recorded. Results Biopsy was positive in 16/24 (67%) and negative in 8/24 (33%) patients. AUCs for readers 1 and 2 increased from 0.64 and 0.53 to 0.95 and 0.86 with MP-MRI, at the patient level, and from 0.73 and 0.66 to 0.90 and 0.79 with MP-MRI, at the prostate-side level (p values <0.05). Biopsy-positive and biopsy-negative prostate sides differed significantly in median ADC [1.44 vs. 1.68 (× 10-3 mm2/s)], median Ktrans [1.07 vs. 0.34 (1/min)], and kep [2.06 vs 1.0 (× 1/min)] (p values <0.05). Conclusions MP-MRI was significantly more accurate than T2WI alone in detecting locally recurrent prostate cancer after radiotherapy PMID:21533634

Akin, Oguz; Gultekin, David; Vargas, Hebert Alberto; Zheng, Junting; Moskowitz, Chaya; Pei, Xin; Sperling, Dahlia; Schwartz, Lawrence; Hricak, Hedvig; Zelefsky, Michael

2013-01-01

305

Gadolinium enhancement: improved MRI detection of retinoblastoma extension into the optic nerve  

International Nuclear Information System (INIS)

We performed T1-, T2-, proton density-weighted, and T1-weighted gadolinium-enhanced MRI on 24 patients with retinoblastoma, using a 1.5 T superconducting unit and head and orbital surface coil imaging. All patients underwent a complete ophthalmologic examination, including B-scan ultrasonography. CT was performed on 10 of 24 patients. Pathologic correlation was obtained in 18 patients who required enucleation. Contrast-enhanced T1-weighted MRI with fat suppression was the sequence most sensitive to optic nerve extension and provided the greatest differentiation between tumor and uninvolved extrascleral tissue. Retinoblastoma demonstrated contrast enhancement. (orig.). With 3 figs., 1 tab

306

Coal fires in Northwest China. Detection, monitoring, and prediction using remote sensing data  

International Nuclear Information System (INIS)

Coal fires in China occur within a region that stretches over 5,000 km in the east- western part and 750 km. in the north-southern part. These fires cause an economic and environmental threat by making a significant contribution to the global CO2 budget. The studies made in this thesis can be divided into two parts. Part one is based on field work and laboratory analysis that includes the dating of the paleo coal fires; part two concerns remote sensing applications for the active coal fires. In Chapter 2, the evolution of the paleo coal fires in Toutunhe and Xinjiang areas are studied. Several age groups of burnt rock have been recognized and their relationships with the river terraces will be discussed. The causes of the paleo coal fires are addressed, and the areas of coal fires with different ages have been dated. In Chapter 3, the physical basis of thermal infrared remote sensing for the detection and measurement of coal fires are addressed with an emphasis on the spatial, spectral, and radiometric resolution. In Chapter 4, a method to reduce the effect of solar heating, the main factor of confusion when investigating the thermal anomalies of coal fires, is discussed with the help of a DEM. In Chapter 5, as the coal fires normally occupy only part of one pixel of the Landsat TM thermal channel data, the capability of sub pixel coal fire detection is addressed. In Chapter 6, the airborne data from different wavelengths acquired at different times are studied to anaired at different times are studied to analyze the spatial thermal characteristics of the coal fires. Spreading direction and different types of coal fires are studied. Chapter 7 presents, based on multi-sensor data fusion techniques, a hierarchical methodology for detection and monitoring of the coal fires. 120 refs

307

Methods and means of remote detection of oil pollutants of water. II. Active detection methods  

Energy Technology Data Exchange (ETDEWEB)

The authors discuss active methods for detecting oil pollutants of water, and they evaluate the practical use of these methods. Sensing of pollutants by the active method is based on the difference in the reflecting, scattering, or fluorescing properties of clean and oil-covered water. The methods for such active analysis involve radar and laser technology. The authors conclude that, although only the visual and photographic methods are now being used, it is expedient to introduce the radar, fluorescent, and active optical radar methods as the most promising alternatives.

Bogorodskii, V.V.; Kropotkin, M.A.

1985-07-01

308

An Assessment of Remote Visual Methods to Detect Cracking in Reactor Components  

International Nuclear Information System (INIS)

Recently, the U.S. nuclear industry has proposed replacing current volumetric and/or surface examinations of certain components in commercial nuclear power plants, as required by the American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI, Inservice Inspection of Nuclear Power Plant Components, with a simpler visual testing (VT) method. The advantages of VT are that these tests generally involve much less radiation exposure and time to perform the examination than do volumetric examinations such as ultrasonic testing. The issues relative to the reliability of VT in determining the structural integrity of reactor components were examined. Some piping and pressure vessel components in a nuclear power station are examined using VT as they are either in high radiation fields or component geometry precludes the use of ultrasonic testing (UT) methodology. Remote VT with radiation-hardened video systems has been used by nuclear utilities to find cracks in pressure vessel cladding in pressurized water reactors, core shrouds in boiling water reactors, and to investigate leaks in piping and reactor components. These visual tests are performed using a wide variety of procedures and equipment. The techniques for remote VT use submersible closed-circuit video cameras to examine reactor components and welds. PNNL conducted a parametric study that examined the important variables influencing the effectiveness of a remote visual test. Tested variables included lighting techniques, camera resolution, camera movement, and magnification. PNNL also conducted a limited laboratory test using a commercial visual testing camera system to experimentally determine the ability of the camera system to detect cracks of various widths under ideal conditions. The results of these studies and their implications are presented in this paper

309

Intrusion detection capabilities of smart video: Collaborative efforts to improve remote monitoring for safeguards surveillance  

International Nuclear Information System (INIS)

Collaborative efforts between the International Projects Division (IPD) of the Department of Advanced Technology at Brookhaven National Laboratory, Aquila Technologies Group, Inc. (Aquila), and the General Physics Institute (GPI) in Moscow have developed object recognition technologies to provide real-time intrusion detection capabilities for Aquila''s GEMINI Digital Surveillance System. The research, development and testing for integrating enhanced surveillance capabilities into Aquila''s GEMINI system will receive support from the US Industry Coalition (USIC), an initiative funded by the Initiatives for Proliferation Prevention (IPP), in the coming year. Oversight of the research and development effort is being provided by the IPD staff to ensure that the technical standards of safeguards systems for use by the International Atomic Energy Agency (IAEA) are met. The scientific expertise at GPI is providing breakthroughs in the realm of motion detection for surveillance. Aquila''s contribution to the project focuses on the integration of authenticated digital camera technology for front-end detection. This project illustrates how the application of technology can increase efficiency and reliability of remote monitoring, as well as the timely detection of Safeguards-significant events

310

An analysis of LULC change detection using remotely sensed data; A Case study of Bauchi City  

Science.gov (United States)

Bauchi is one of the cities in the north eastern part of Nigeria that has witnessed tremendous expansion as a result of rapid urbanization. For the past decade, the city has been known to be relatively small both in size and population. But today, Bauchi is one of the fastest growing cities in northern Nigeria. Therefore, it is paramount to detect the nature and magnitude of these changes in order to determine its direction of future expansion. To achieve that, Remotely Sensed data from Landsat 7 ETM+ and Landsat 8 were utilized for the purpose of LULC change detection in Bauchi city. Landsat 7 image of 2003 and Landsat 8 image of 2013 were obtained for the purpose of the study. Three change detection algorithms were used to detect areas of change. They include supervised, unsupervised and post classification comparison. While the unsupervised classification was found to be less effective, the supervised classification produced good results with overall accuracies of 93.5% and 89.7% for the 2003 and 2013 respectively. Finally, "from-to" change was obtained using the post classification comparism.

Kafi, K. M.; Shafri, H. Z. M.; Shariff, A. B. M.

2014-06-01

311

Remote Pulsed Laser Raman Spectroscopy System for Detecting Qater, Ice, and Hydrous Minerals  

Science.gov (United States)

For exploration of planetary surfaces, detection of water and ice is of great interest in supporting existence of life on other planets. Therefore, a remote Raman spectroscopy system was demonstrated at NASA Langley Research Center in collaboration with University of Hawaii for detecting ice-water and hydrous minerals on planetary surfaces. In this study, a 532 nm pulsed laser is utilized as an excitation source to allow detection in high background radiation conditions. The Raman scattered signal is collected by a 4-inch telescope positioned in front of a spectrograph. The Raman spectrum is analyzed using a spectrograph equipped with a holographic super notch filter to eliminate Rayleigh scattering, and a holographic transmission grating that simultaneously disperses two spectral tracks onto the detector for higher spectral range. To view the spectrum, the spectrograph is coupled to an intensified charge-coupled device (ICCD), which allows detection of very weak Stokes line. The ICCD is operated in gated mode to further suppress effects from background radiation and long-lived fluorescence. The sample is placed at 5.6 m from the telescope, and the laser is mounted on the telescope in a coaxial geometry to achieve maximum performance. The system was calibrated using the spectral lines of a Neon lamp source. To evaluate the system, Raman standard samples such as calcite, naphthalene, acetone, and isopropyl alcohol were analyzed. The Raman evaluation technique was used to analyze water, ice and other hydrous minerals and results from these species are presented.

Garcia, Christopher S.; Abedin, M. Nuraul; Sharma, Shiv K.; Misra, Anupam K.; Ismail, Syed; Singh, Upendra; Refaat, Tamer F.; Elsayed-Ali, Hani; Sandford, Steve

2006-01-01

312

Tumorsize dependent detection rate of endorectal MRI of prostate cancer-A histopathologic correlation with whole-mount sections in 70 patients with prostate cancer  

Energy Technology Data Exchange (ETDEWEB)

Purpose: To evaluate the value of T2w endorectal MRI (eMRI) for correct detection of tumor foci within the prostate regarding tumor size. Materials and Methods: 70 patients with histologically proven prostate cancer were examined with T2w eMRI before radical prostatectomy at a 1.5 T scanner. For evaluation of eMRI, two radiologists evaluated each tumor focus within the gland. After radical prostatectomy, the prostates were prepared as whole-mount sections, according to transversal T2w eMRI. For each slice, tumor surroundings were marked and compared with eMRI. Based on whole-mount section, 315 slices were evaluated and 533 tumor lesions were documented. Results: Based on the T2w eMRI, 213 tumor lesions were described. In 137/213, histology could prove these lesions. EMRI was able to visualize 0/56 lesions with a maximum size of <0.3 cm (detection rate 0%), between 0.3 and 0.5 cm 4/116 (3%), between 1 and 0.5 cm 22/169 (13%), between 2 and 1 cm 61/136 (45%) and for >2 cm 50/56 (89%). False positive eMRI findings were: <0.3 cm n = 0, 0.5-0.3 cm n = 12, 0.5-1 cm n = 34, 1-2 cm n = 28 and >2 cm n = 2. Conclusion: T2w eMRI cannot exclude prostate cancer with lesions smaller 10 mm and 0.4 cm{sup 3} respectively. The detection rate for lesions more than 20 mm (1.6 cm{sup 3}) is to be considered as high.

Roethke, Matthias C., E-mail: Matthias.roethke@med.uni-tuebingen.de [Departments of Diagnostic and Interventional Radiology, University of Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany); Lichy, Matthias P.; Jurgschat, Leo [Departments of Diagnostic and Interventional Radiology, University of Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany); Hennenlotter, Joerg [Departments of Urology, University of Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany); Vogel, Ulrich [Departments of Pathology, University of Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany); Schilling, David; Stenzl, Arnulf [Departments of Urology, University of Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany); Claussen, Claus D.; Schlemmer, Heinz-Peter [Departments of Diagnostic and Interventional Radiology, University of Tuebingen, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany)

2011-08-15

313

Empirical evaluation of bias field correction algorithms for computer-aided detection of prostate cancer on T2w MRI  

Science.gov (United States)

In magnetic resonance imaging (MRI), intensity inhomogeneity refers to an acquisition artifact which introduces a non-linear variation in the signal intensities within the image. Intensity inhomogeneity is known to significantly affect computerized analysis of MRI data (such as automated segmentation or classification procedures), hence requiring the application of bias field correction (BFC) algorithms to account for this artifact. Quantitative evaluation of BFC schemes is typically performed using generalized intensity-based measures (percent coefficient of variation, %CV ) or information-theoretic measures (entropy). While some investigators have previously empirically compared BFC schemes in the context of different domains (using changes in %CV and entropy to quantify improvements), no consensus has emerged as to the best BFC scheme for any given application. The motivation for this work is that the choice of a BFC scheme for a given application should be dictated by application-specific measures rather than ad hoc measures such as entropy and %CV. In this paper, we have attempted to address the problem of determining an optimal BFC algorithm in the context of a computer-aided diagnosis (CAD) scheme for prostate cancer (CaP) detection from T2-weighted (T2w) MRI. One goal of this work is to identify a BFC algorithm that will maximize the CaP classification accuracy (measured in terms of the area under the ROC curve or AUC). A secondary aim of our work is to determine whether measures such as %CV and entropy are correlated with a classifier-based objective measure (AUC). Determining the presence or absence of these correlations is important to understand whether domain independent BFC performance measures such as %CV , entropy should be used to identify the optimal BFC scheme for any given application. In order to answer these questions, we quantitatively compared 3 different popular BFC algorithms on a cohort of 10 clinical 3 Tesla prostate T2w MRI datasets (comprising 39 2D MRI slices): N3 , PABIC, and the method of Cohen et al. Results of BFC via each of the algorithms was evaluated in terms of %CV , entropy, as well as classifier AUC for CaP detection from T2w MRI. The CaP classifier was trained and evaluated on a per-pixel basis using annotations of CaP obtained via registration of T2w MRI and ex vivo whole-mount histology sections. Our results revealed that different BFC schemes resulted in a maximization of different performance measures, that is, the BFC scheme identified by minimization of %CV and entropy was not the one that maximized AUC as well. Moreover, existing BFC evaluation measures (%CV , entropy) did not correlate with AUC (application-based evaluation), but did correlate with each other, suggesting that domain-specific performance measures should be considered in making a decision regarding choice of appropriate BFC scheme. Our results also revealed that N3 provided the best correction of bias field artifacts in prostate MRI data, when the goal was to identify prostate cancer.

Viswanath, Satish; Palumbo, Daniel; Chappelow, Jonathan; Patel, Pratik; Bloch, B. Nicholas; Rofsky, Neil; Lenkinski, Robert; Genega, Elizabeth; Madabhushi, Anant

2011-03-01

314

AIRBORNE, OPTICAL REMOTE SENSING OF METHANE AND ETHANE FOR NATURAL GAS PIPLINE LEAK DETECTION  

Energy Technology Data Exchange (ETDEWEB)

Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. The third six-month technical report contains a summary of the progress made towards finalizing the design and assembling the airborne, remote methane and ethane sensor. The vendor has been chosen and is on contract to develop the light source with the appropriate linewidth and spectral shape to best utilize the Ophir gas correlation software. Ophir has expanded upon the target reflectance testing begun in the previous performance period by replacing the experimental receiving optics with the proposed airborne large aperture telescope, which is theoretically capable of capturing many times more signal return. The data gathered from these tests has shown the importance of optimizing the fiber optic receiving fiber to the receiving optic and has helped Ophir to optimize the design of the gas cells and narrowband optical filters. Finally, Ophir will discuss remaining project issues that may impact the success of the project.

Jerry Myers

2004-05-12

315

Improving model construction of profile HMMs for remote homology detection through structural alignment  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Remote homology detection is a challenging problem in Bioinformatics. Arguably, profile Hidden Markov Models (pHMMs are one of the most successful approaches in addressing this important problem. pHMM packages present a relatively small computational cost, and perform particularly well at recognizing remote homologies. This raises the question of whether structural alignments could impact the performance of pHMMs trained from proteins in the Twilight Zone, as structural alignments are often more accurate than sequence alignments at identifying motifs and functional residues. Next, we assess the impact of using structural alignments in pHMM performance. Results We used the SCOP database to perform our experiments. Structural alignments were obtained using the 3DCOFFEE and MAMMOTH-mult tools; sequence alignments were obtained using CLUSTALW, TCOFFEE, MAFFT and PROBCONS. We performed leave-one-family-out cross-validation over super-families. Performance was evaluated through ROC curves and paired two tailed t-test. Conclusion We observed that pHMMs derived from structural alignments performed significantly better than pHMMs derived from sequence alignment in low-identity regions, mainly below 20%. We believe this is because structural alignment tools are better at focusing on the important patterns that are more often conserved through evolution, resulting in higher quality pHMMs. On the other hand, sensitivity of these tools is still quite low for these low-identity regions. Our results suggest a number of possible directions for improvements in this area.

Zaverucha Gerson

2007-11-01

316

Remote Raman Spectroscopic Detection of Inorganic, Organic and Biological Materials to 100 m and More  

Science.gov (United States)

We have designed and tested a portable gated-Raman system that is capable of detecting organic and inorganic bulk chemicals over stand-off distances of 100 m and more during day and night time. Utilizing a 532 nm laser pulse (~35 mJ/pulse), Raman spectra of several organic and inorganic compounds have been measured with the portable Raman instrument over a distance of 100 m. Remote Raman spectra, obtained with a very short gate (2 micro second), from a variety of inorganic minerals such as calcite (CaCO3), ?-quartz (?-SiO2), barite (BaSO4), and FeSO4.7H2O, and organic compounds such as acetone, methanol, 2-propanol and naphthalene showed all major bands required for unambiguous chemical identification. We also measured the Raman and fluorescence spectra of plant leaves, tomato, and chicken eggshell excited with a 532 nm, 20 Hz pulsed laser and accumulated over 200 laser shots (10-s integration time) at 110 m with good signal-to-noise ratio. The results of these investigations show that remote Raman spectroscopy over a distance of 100 m can be used to identify Raman fingerprints of both inorganic, organic, and some biological compounds on planetary surfaces and could be useful for environmental monitoring.

Sharma, Shiv K.; Misra, Anupam K.

2008-11-01

317

T?-weighted MRI detects presymptomatic pathology in the SOD1 mouse model of ALS.  

Science.gov (United States)

Neuroinflammation has been identified as a potential therapeutic target in amyotrophic lateral sclerosis (ALS), but relevant biomarkers are needed. The superoxide dismutase (SOD1)(G93A) transgenic mouse model of ALS offers a unique opportunity to study and potentially manipulate presymptomatic pathology. While T?-weighted magnetic resonance imaging (MRI) has been shown to be sensitive to pathologic changes at symptom onset, no earlier biomarkers were previously identified and the underlying histopathologic correlates remain uncertain. To address these issues, we used a multimodal MRI approach targeting structural (T?, T?, apparent diffusion coefficient (ADC), magnetization transfer ratio (MTR)), vascular (gadolinium diethylene triamine pentaacetic acid), and endothelial (vascular cell adhesion molecule-microparticles of iron oxide) changes, together with histopathologic analysis from presymptomatic to symptomatic stages of disease. Presymptomatic changes in brainstem nuclei were evident on T?-weighted images from as early as 60 days (Ppermeability, or endothelial activation were found at any stage of disease. These findings suggest that T?-weighted MRI offers the strongest biomarker potential in this model, and that MRI has unique potential for noninvasive and longitudinal assessment of presymptomatically applied therapeutic and neuroprotective agents. PMID:24496176

Evans, Matthew C; Serres, Sébastien; Khrapitchev, Alexandre A; Stolp, Helen B; Anthony, Daniel C; Talbot, Kevin; Turner, Martin R; Sibson, Nicola R

2014-05-01

318

Magnetic mitoxantrone nanoparticle detection by histology, X-ray and MRI after magnetic tumor targeting  

International Nuclear Information System (INIS)

Ferrofluids coated with starch polymers can be used as biocompatible carriers. Bound to medical drugs, such magnetic particles can be enriched in a desired body compartment using an external magnetic field. In the present study, we confirm the enrichment of ferrofluids in tumor tissue using histological investigations and conventional imaging techniques, i.e. X-ray and MRI

319

T2-weighted MRI detects presymptomatic pathology in the SOD1 mouse model of ALS  

Science.gov (United States)

Neuroinflammation has been identified as a potential therapeutic target in amyotrophic lateral sclerosis (ALS), but relevant biomarkers are needed. The superoxide dismutase (SOD1)G93A transgenic mouse model of ALS offers a unique opportunity to study and potentially manipulate presymptomatic pathology. While T2-weighted magnetic resonance imaging (MRI) has been shown to be sensitive to pathologic changes at symptom onset, no earlier biomarkers were previously identified and the underlying histopathologic correlates remain uncertain. To address these issues, we used a multimodal MRI approach targeting structural (T2, T1, apparent diffusion coefficient (ADC), magnetization transfer ratio (MTR)), vascular (gadolinium diethylene triamine pentaacetic acid), and endothelial (vascular cell adhesion molecule–microparticles of iron oxide) changes, together with histopathologic analysis from presymptomatic to symptomatic stages of disease. Presymptomatic changes in brainstem nuclei were evident on T2-weighted images from as early as 60 days (P<0.05). Histologic indices of vacuolation, astro- and microglial activation all correlated with T2-weighted changes. Significant reductions in ADC (P<0.01) and MTR (P<0.05) were found at 120 days in the same brainstem nuclei. No changes in T1 relaxation, vascular permeability, or endothelial activation were found at any stage of disease. These findings suggest that T2-weighted MRI offers the strongest biomarker potential in this model, and that MRI has unique potential for noninvasive and longitudinal assessment of presymptomatically applied therapeutic and neuroprotective agents. PMID:24496176

Evans, Matthew C; Serres, Sebastien; Khrapitchev, Alexandre A; Stolp, Helen B; Anthony, Daniel C; Talbot, Kevin; Turner, Martin R; Sibson, Nicola R

2014-01-01

320

Bayesian joint detection-estimation of cerebral vasoreactivity from ASL fMRI data.  

Science.gov (United States)

Although the study of cerebral vasoreactivity using fMRI is mainly conducted through the BOLD fMRI modality, owing to its relatively high signal-to-noise ratio (SNR), ASL fMRI provides a more interpretable measure of cerebral vasoreactivity than BOLD fMRI. Still, ASL suffers from a low SNR and is hampered by a large amount of physiological noise. The current contribution aims at improving the recovery of the vasoreactive component from the ASL signal. To this end, a Bayesian hierarchical model is proposed, enabling the recovery of perfusion levels as well as fitting their dynamics. On a single-subject ASL real data set involving perfusion changes induced by hypercapnia, the approach is compared with a classical GLM-based analysis. A better goodness-of-fit is achieved, especially in the transitions between baseline and hypercapnia periods. Also, perfusion levels are recovered with higher sensitivity and show a better contrast between gray- and white matter. PMID:24579192

Vincent, Thomas; Warnking, Jan; Villien, Marjorie; Krainik, Alexandre; Ciuciu, Philippe; Forbes, Florence

2013-01-01

 
 
 
 
321

Dynamic gadolinium-enhanced MRI in the detection of spinal arteriovenous malformations  

International Nuclear Information System (INIS)

Arteriovenous fistulae and malformations (AVFs and AVMs) of the spinal cord are rare, potentially treatable causes of progressive disability. Although a variety of MRI abnormalities has been described, the diagnosis rests on the findings on selective spinal angiography. Collecting T2'-weighted MR images during the passage of a gadolinium bolus gives information about perfusion and blood volume. We carried out dynamic MRI in seven patients with vascular abnormalities (5 dural AVFs, 1 intramedullary AVM, 1 cryptic angioma) and in two patients without an AVM. High resolution T1- and T2-weighted sagittal images of the whole spinal cord were first obtained using a multiarray receiver coil. Sagittal radiofrequency spoilt gradient echo images (GE34/25, flip angle 10 ) were then obtained during bolus injection of gadolinium-DTPA. Abnormalities were seen in all seven patients with AVFs or AVMs. In the patient with an intramedullary AVM and four of the five with dural AVFs transient signal reduction was seen within the perimedullary venous plexus during passage of the bolus. The findings correlated well with those from selective spinal angiography. We conclude that dynamic MRI offers a useful adjunct to angiography and may localise an arteriovenous shunt when conventional MRI fails to do so. In combination with high-resolution imaging of the entire spinal cord the technique may make myelography redundant; it is simple, well tolerated and can be carried out without siolerated and can be carried out without significant time penalty. (orig.)

322

3 T MRI relaxometry detects T2 prolongation in the cerebral normal-appearing white matter in multiple sclerosis.  

Science.gov (United States)

MRI at 3 T has increased sensitivity in detecting overt multiple sclerosis (MS) brain lesions; a growing body of data suggests clinically relevant damage occurs in the normal-appearing white matter (NAWM). We tested a novel pulse sequence to determine whether 3 T MRI spin-spin relaxometry detected damage in NAWM of MS patients (n=13) vs. age-matched normal controls [(NL) (n=11)]. Baseline characteristics of the MS group were: age (mean+/-SD) 42.5+/-5.4 (range 33-51 years), disease duration 9.0+/-6.4 (range 1-22 years), Expanded Disability Status Scale score 2.5+/-1.7 (range 1-6.5). Brain MRI measures, obtained at 3 T, included global and regional NAWM transverse relaxation rate [R2 (=1/T2)], derived from 3D fast spin-echo T2 prepared images, and global white matter volume fraction derived from SPGR images. The regional NAWM areas investigated were the frontal lobe, parietal lobe, and the genu and splenium of the corpus callosum. Mean NAWM R2 was lower (indicating T2 prolongation) in MS than NL in the whole brain (p=0.00047), frontal NAWM (p=0.00015), parietal NAWM (p=0.0069) and callosal genu (p=0.0019). Similarly, R2 histogram peak position was lower in NAWM in MS than NL in the whole brain (p=0.019). However, the normalized WM volume fractions were similar in both MS and NL (p>0.1). This pilot study suggests that a novel 3D fast spin-echo pulse sequence at 3 T, used to derive R2 relaxation maps, can detect tissue damage in the global and regional cerebral NAWM of MS patients that is missed by conventional lesion and atrophy measures. Such findings may represent demyelination, inflammation, glial proliferation and axonal loss. PMID:19281850

Neema, Mohit; Goldberg-Zimring, Daniel; Guss, Zachary D; Healy, Brian C; Guttmann, Charles R G; Houtchens, Maria K; Weiner, Howard L; Horsfield, Mark A; Hackney, David B; Alsop, David C; Bakshi, Rohit

2009-07-01

323

EXTENDED PERFORMANCE HANDHELD AND MOBILE SENSORS FOR REMOTE DETECTION OF NATURAL GAS LEAKS  

Energy Technology Data Exchange (ETDEWEB)

This report summarizes work performed by Physical Sciences Inc. (PSI) to advance the state-of-the-art of surveying for leaks of natural gas from transmission and distribution pipelines. The principal project goal was to develop means of deploying on an automotive platform an improved version of the handheld laser-based standoff natural gas leak detector previously developed by PSI and known as the Remote Methane Leak Detector or RMLD. A laser beam which interrogates the air for methane is projected from a spinning turret mounted upon a van. As the van travels forward, the laser beam scans an arc to the front and sides of the van so as to survey across streets and to building walls from a moving vehicle. When excess methane is detected within the arc, an alarm is activated. In this project, we built and tested a prototype Mobile RMLD (MRMLD) intended to provide lateral coverage of 10 m and one lateral scan for every meter of forward motion at forward speeds up to 10 m/s. Using advanced detection algorithms developed as part of this project, the early prototype MRMLD, installed on the back of a truck, readily detected simulated gas leaks of 50 liters per hour. As a supplement to the originally planned project, PSI also participated in a DoE demonstration of several gas leak detection systems at the Rocky Mountain Oilfield Testing Center (RMOTC) during September 2004. Using a handheld RMLD upgraded with the advanced detection algorithms developed in this project, from within a moving vehicle we readily detected leaks created along the 7.4 mile route of a virtual gas transmission pipeline.

Michael B. Frish; B. David Green; Richard T. Wainner; Francesca Scire-Scappuzzo; Paul Cataldi; Matthew C. Laderer

2005-05-01

324

Detection of focal liver lesions: Comparison of MRI at 1.5. T with dynamic spiral CT  

International Nuclear Information System (INIS)

To compare dynamic spiral CT with MR imaging in the detectability of focal liver lesions. Thirty-one patients with 62 focal liver lesions (27 benign) were evaluated retrospectively. Dynamic spiral CT scans were compared with T1- and T2-weighted spin-echo (SE) sequences and in part with multi slice 2-D-FLASH and single-shot slice-selective inversion recovery Turbo-FLASH sequences at 1.5 T. Dynamic spiral CT detected 89% of all lesions and was superior to each sequence alone (56-70%), and also to MRI overall (70%) regardless of lesion size, localization, and histology. However, statistical significance (p1-weighted SE sequence. Compared to conventional SE and GE MR imaging sequences, dynamic spiral CT scanning seems to be more effective in the detection of focal liver lesions. (orig.)

325

In situ gas sensing using a remotely detectable probe with replaceable insert.  

Science.gov (United States)

We demonstrate a spectroscopic gas sensor using an optical fiber probe with a replaceable insert. The probe consists of a hollow-core photonic bandgap fiber (HC-PBGF) with a core diameter of 10.9 ?m and a glass tube where a 2-?m hollow core fiber (HCF) with a gold coated end facet can be inserted. The HCF is designed to function as both a gate where gases can enter the HC-PBGF and a mirror reflecting the guided light back to the HC-PBGF. The opposite distal end of the probe is also designed to be able to regulate the gas pressure within the HC-PBGF for a high gas flow rate, while still transmitting the reflected light to the analysis instrument. The remote sensing probe, we believe, has much potential for detecting gases in hazardous environments. PMID:22274515

Lim, Sun Do; Ma, Kyungsik; Jeong, Ji Ho; Kim, Gilhwan; Lee, Kwanil; Jeong, Je-Myung; Lee, Sang Bae

2012-01-16

326

Anomaly Detection Rudiments for the Application of Hyperspectral Sensors in Aerospace Remote Sensing  

International Nuclear Information System (INIS)

Hyperspectral imaging differs from conventional techniques by exploiting the spectral dimensionality of remote scenes. This additional information promotes discrimination of image elements, especially anomalies that are dissimilar with respect to global features. Algorithms for anomaly detection are designed to overcome the inherent difficulty of analysing hypercubes, which are the higher-dimensional analogues of conventional broadband images. Such algorithms are prolific in their variety and design, which could become an obstacle in choice or application for the neophyte researcher in this field. This paper seeks to consolidate this plethora of algorithms into succinct categories for clarity of rudimentary decision making. A duplicate of article 012048 Snapshot hyperspectral imaging and practical applications was originally published here, in error, as article 012051. The present article replaced the duplicate and was published on 18 August 2009.

327

Method of remote powering and detecting multiple UWB passive tags in an RFID system  

Science.gov (United States)

A new Radio Frequency Identification (RFID), tracking, powering apparatus/system and method using coded Ultra-wideband (UWB) signaling is introduced. The proposed hardware and techniques disclosed herein utilize a plurality of passive UWB transponders in a field of an RFID-radar system. The radar system itself enables multiple passive tags to be remotely powered (activated) at about the same time frame via predetermined frequency UWB pulsed formats. Once such tags are in an activated state, an UWB radar transmits specific "interrogating codes" to put predetermined tags in an awakened status. Such predetermined tags can then communicate by a unique "response code" so as to be detected by an UWB system using radar methods.

Dowla, Farid U. (Castro Valley, CA); Nekoogar, Faranak (San Ramon, CA); Benzel, David M. (Livermore, CA); Dallum, Gregory E. (Livermore, CA); Spiridon, Alex (Palo Alto, CA)

2012-05-29

328

Differential diagnosis of MRI detected intra cranial space occupying lesions (ICSOLS)-role of 99MTC tetrofosmin cerebral spect  

International Nuclear Information System (INIS)

Discriminating the correct etiology of Intra Cranial Space Occupying Lesions (ICSOLs) detected by MRI is of paramount importance in deciding the right therapeutic approach. Functional imaging like 99m Tc Tetrofosmin cerebral SPECT (C SPECT) can be used to differentiate malignant from other benign cerebral pathologies. Objective: Our aim was to assess the efficacy of C SPECT in differentiating various etiologies (i.e. Infective / Inflammatory, Neoplastic and Post Radiotherapy changes) of MRI detected ICSOLs. We also aimed to assess the incremental value of quantitative uptake ratios in identifying the exact nature of ICSOLs. Method: 26 Patients (M:F=20:6), age range 28-76 yrs, mean 42±7 yrs were evaluated by 99mTc Tetrofosmin cerebral SPECT. 14/26 patients were HIV positive cases while remaining 12 were treated patients of intracerebral malignancies. All these patients had one or more discrete MRI detected ICSOLs. 6/4 patients with HIV and 4/12 patients in the non HIV group showed more than 1 discrete ICSOLs. 20 mci of 99mTc Tetrofosmin was injected IV .15 min (early) and 2 hrs (delayed) post injection C SPECT images were acquired on a dual head variable angle Gamma camera. After reconstruction, transverse, coronal and sagittal images were co- registered with DICOM online available MRI images using aco- registration software. Focal Tetrofosmin uptake in MRI detected ICSOL was interpreted as abnormal. Tetrofosmin uptake index (Ix) was calculated in early and delayed images as ratio of counts in lesion to that of contra lateral region. A value of more than 1.3 was considered to be abnormal. Persistent Ix of more than 1.3 in initial and delayed images were considered to be malignant while Ix of more or less than 1.3 in initial but less than 1.3 in delayed images was considered to be benign in both groups. Results: In HIV group (14 pts), 4 patients showed an Ix of less than 1.3 in both early and delayed images and 7 patients showed an Ix of more than 1.3 in early but significant washout of Tetrofosmin in delayed images (Ix 1.3). So this 11/14 patients were diagnosed to have an infective / inflammatory SOL (etiology: TB / toxoplasmosis) and were followed up at least for 5 months.10/11 patients improved / did not show any deterioration while 1 patient deteriorated (93% specificity). Remaining 3 patients who showed significant tracer uptake in both images (more than 1.3 Ix) were diagnosed to have cerebral malignancy and underwent stereo tactic biopsy. All were proved to be positive for lymphoma (100 % sensitivity, specificity). In non HIV group (12pts), (i.e.tumour recurrence Vs Post Radiotherapy edema) 5/12 patients showed features of recurrence with a persistent Ix of more than 2.0. and 7/12 patients showed an Ix of more than 1.3 in early but significant washout of Tetrofosmin in delayed images (Ix less than 1.3) prompting a diagnosis of post radiotherapy edema. While benign etiology patients were followed up with conservative measures recurrent malignancy patients were subsequently taken up for radiotherapy. 1 patient in benign group deteriorated and was diagnosed to have a recurrence. (Specificity 85.7%) Conclusion: C SPECT is a very useful tool in further evaluating MRI detected ICSOLs both in HIV positive patients and in follow up patients of treated intra cranial malignancies. An uptake index of 1.3 seems to be a good cut off value while performing C SPECT. (authors)

329

AIRBORNE, OPTICAL REMOTE SENSING OF METHANE AND ETHANE FOR NATURAL GAS PIPELINE LEAK DETECTION  

Energy Technology Data Exchange (ETDEWEB)

Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. This six-month technical report summarizes the progress for each of the proposed tasks, discusses project concerns, and outlines near-term goals. Ophir has completed a data survey of two major natural gas pipeline companies on the design requirements for an airborne, optical remote sensor. The results of this survey are disclosed in this report. A substantial amount of time was spent on modeling the expected optical signal at the receiver at different absorption wavelengths, and determining the impact of noise sources such as solar background, signal shot noise, and electronic noise on methane and ethane gas detection. Based upon the signal to noise modeling and industry input, Ophir finalized the design requirements for the airborne sensor, and released the critical sensor light source design requirements to qualified vendors. Responses from the vendors indicated that the light source was not commercially available, and will require a research and development effort to produce. Three vendors have responded positively with proposed design solutions. Ophir has decided to conduct short path optical laboratory experiments to verify the existence of methane and absorption at the specified wavelength, prior to proceeding with the light source selection. Techniques to eliminate common mode noise were also evaluated during the laboratory tests. Finally, Ophir has included a summary of the potential concerns for project success and has established future goals.

Jerry Myers

2003-05-13

330

Evolution of Coral Rubble Deposits on a Reef Platform as Detected by Remote Sensing  

Directory of Open Access Journals (Sweden)

Full Text Available An investigation into the evolution of coral rubble deposits on a coral reef platform is assessed using high-resolution remote sensing data and geospatial analysis. Digital change detection analysis techniques are applied to One Tree Reef in the southern Great Barrier Reef by analysing aerial photographs and satellite images captured between 1964 and 2009. Two main types of rubble deposits were identified: (1 rubble flats that are featureless mass accumulations of coral rubble; and, (2 rubble spits that are shore-normal linear features. While both deposits prograde in a lagoon-ward direction, rubble spits move faster (~2 m/yr than rubble flats (~0.5 m/yr. The volume of rubble, the underlying substrate, the energy regime, and storm frequency control the rate of progradation. Rubble flat occurrence is restricted to the high-energy (windward margin of the coral reef platform, while rubble spits are distributed reef wide, both in modal high energy and modal low energy regions of the reef. Rubble spit deposition is considered to be a result of enlarged spur and groove morphology of the forereef, whereby wave energy is focused through the enlarged groove formations causing the preferential deposition of coral rubble in particular zones of the adjacent reef flat. One last control is thought to be the elevation of the reef crest whereby lower areas are more prone to rubble flat development. A vertical and ocean-ward accumulation of rubble is occurring on the windward margin of the reef leading to a build-up and build-out of the reef, governing the expansion of the reef footprint. This study shows for the first time the evolution of a coral reef rubble flat and rubble spits over decadal time scales as detected through remotely sensed images spanning 45 years.

Ana Vila-Concejo

2012-12-01

331

Application of remote sensing in coastal change detection after the tsunami event in Indonesia  

Science.gov (United States)

Shoreline mapping and shoreline change detection are critical in many coastal zone applications. This study focuses on applying remote sensing technology to identify and assess coastal changes in the Banda Aceh, Indonesia. Major changes to land cover were found along the coastal line. Using remote sensing data to detect coastal line change requires high spatial resolution data. In this study, two high spatial data with 30 meter resolution of Landsat TM images captured before and after the Tsunami event were acquired for this purpose. The two satellite images was overlain and compared with pre-Tsunami imagery and with after Tsunami. The two Landsat TM images also were used to generate land cover classification maps for the 24 December 2004 and 27 March 2005, before and after the Tsunami event respectively. The standard supervised classifier was performed to the satellite images such as the Maximum Likelihood, Minimum Distance-to-mean and Parallelepiped. High overall accuracy (>80%) and Kappa coefficient (>0.80) was achieved by the Maximum Likelihood classifier in this study. Estimation of the damage areas between the two dated was estimated from the different between the two classified land cover maps. Visible damage could be seen in either before and after image pair. The visible damage land areas were determined and draw out using the polygon tool included in the PCI Geomatica image processing software. The final set of polygons containing the major changes in the coastal line. An overview of the coastal line changes using Landsat TM images is also presented in this study. This study provided useful information that helps local decision makers make better plan and land management choices.

Lim, H. S.; MatJafri, M. Z.; Abdullah, K.; Saleh, N. Mohd.; Surbakti, M. S.

2008-10-01

332

Detection, Identification, Location, and Remote Sensing using SAW RFID Sensor Tags  

Science.gov (United States)

In this presentation, we will consider the problem of simultaneous detection, identification, location estimation, and remote sensing for multiple objects. In particular, we will describe the design and testing of a wireless system capable of simultaneously detecting the presence of multiple objects, identifying each object, and acquiring both a low-resolution estimate of location and a high-resolution estimate of temperature for each object based on wireless interrogation of passive surface acoustic wave (SAW) radiofrequency identification (RFID) sensor tags affixed to each object. The system is being studied for application on the lunar surface as well as for terrestrial remote sensing applications such as pre-launch monitoring and testing of spacecraft on the launch pad and monitoring of test facilities. The system utilizes a digitally beam-formed planar receiving antenna array to extend range and provide direction-of-arrival information coupled with an approximate maximum-likelihood signal processing algorithm to provide near-optimal estimation of both range and temperature. The system is capable of forming a large number of beams within the field of view and resolving the information from several tags within each beam. The combination of both spatial and waveform discrimination provides the capability to track and monitor telemetry from a large number of objects appearing simultaneously within the field of view of the receiving array. In the presentation, we will summarize the system design and illustrate several aspects of the operational characteristics and signal structure. We will examine the theoretical performance characteristics of the system and compare the theoretical results with results obtained from experiments in both controlled laboratory environments and in the field.

Barton, Richard J.

2009-01-01

333

Comparison of abdominal MRI with diffusion-weighted imaging to {sup 68}Ga-DOTATATE PET/CT in detection of neuroendocrine tumors of the pancreas  

Energy Technology Data Exchange (ETDEWEB)

The aim of the study was to evaluate contrast-enhanced MRI, diffusion-weighted MRI (DW MRI), and {sup 68}Ga-DOTATATE positron emission tomography (PET)/CT in the detection of intermediate to well-differentiated neuroendocrine tumors (NET) of the pancreas. Eighteen patients with pathologically proven pancreatic NET who underwent MRI including DW MRI and PET/CT within 6 weeks of each other were included in this retrospective study. Two radiologists evaluated T2-weighted (T2w), T2w + DW MRI, T2w + contrast-enhanced T1-weighted (CE T1w) MR images, and PET/CT for NET detection. The sensitivity and level of diagnostic confidence were compared among modalities using McNemar's test and a Wilcoxon signed rank test. Apparent diffusion coefficients (ADC) of pancreatic NETs and normal pancreatic tissue were compared with Student's t test. Of the NETs, 8/23 (34.8 %) and 9/23 (39.1 %) were detected on T2w images by observers 1 and 2, respectively. Detection rates improved significantly by combining T2w images with DW MRI (observer 1: 14/23 = 61 %; observer 2: 15/23 = 65.2 %; p < 0.05) or CE T1w images (observer 1: 14/23 = 61 %; observer 2: 15/23 = 65.2 %; p < 0.05). Detection rates of pancreatic NET with PET/CT (both observers: 23/23 = 100 %) were statistically significantly higher than with MRI (p < 0.05). The mean ADC value of NET (1.02 {+-} 0.26 x 10{sup -3} mm{sup 2}/s) was statistically significantly lower than that of normal pancreatic tissue (1.48 {+-} 0.39 x 10{sup -3} mm{sup 2}/s). DW MRI is a valuable adjunct to T2w imaging and comparable to CE T1w imaging in pancreatic NET detection, quantitatively differentiating between NET and normal pancreatic tissue with ADC measurements. {sup 68}Ga-DOTATATE PET/CT is more sensitive than MRI in the detection of pancreatic NET. (orig.)

Schmid-Tannwald, Christine; Schmid-Tannwald, Christoph M.; Neumann, Ralph; Nikolaou, Konstantin; Schramm, Nicolai; Reiser, Maximilian F.; Rist, Carsten [Ludwig Maximilians University Hospital Munich, Institute for Clinical Radiology, Munich (Germany); Morelli, John N. [Scott and White Hospital Temple, Department of Radiology, Temple, TX (United States); Haug, Alexander R.; Jansen, Nathalie [Ludwig Maximilians University Hospital Munich, Department of Nuclear Medicine, Munich (Germany)

2013-06-15

334

Image processing and classification for the UK remote minefield detection system infrared polarimetric camera  

Science.gov (United States)

The UK Remote Minefield Detection System (REMIDS) Technology Demonstration Programme (TDP) aims to demonstrate the applicability of emerging technologies in an integrated system for detecting mined areas from an airborne platform. The multi-sensor demonstrator is being managed by DERA on behalf of the UK MoD with an unmanned air vehicle (UAV) as the intended platform. The TDP is nearing the end of a five year programme that has developed a novel ultra wide band synthetic aperture radar (UWB SAR) and a MWIR time-parallel polarimetric IR camera (IRPC). A ground station processor has also been developed to fuse sensor outputs through a variety of detection and identification algorithms. An extensive series of data collection trials and analysis activities has been performed. This paper reports on the development by DERA of the algorithms required both to pre- process raw data from the IRPC into a useable form, and to discriminate mines from a variety of backgrounds. These algorithms are being integrated into ground station processing that will combine data from both sensors to identify mine areas and accurately delineate their boundaries. The top-level process architecture for this ground station, and how the IPRC fits within it, are also described in this paper.

Williams, John W.; Tee, Howard S.; Poulter, Mark A.

2001-10-01

335

High Energy Protons for Remote Standoff Detection of Special Nuclear Materials  

Energy Technology Data Exchange (ETDEWEB)

High energy protons can be a powerful probe for standoff detection of Special Nuclear Materials (SNM). In particular, the use of protons of 500 MeV and up with modest beam currents, 10 to 100 {mu}A, can be far more efficient in the production of fission neutrons than conventional bremsstrahlung based electron linacs. Such beams can provide both the range and, more importantly, the sensitivity to fissile materials required for remote detection at distances of hundreds of meters or more. The practical application of this technique has been limited by the requirements of producing such high energy protons using conventional proton accelerators--typically very large, fixed installations. The on-going development at MIT of a new generation of very compact superconducting cyclotrons makes a compelling case for examining this approach for a practical standoff detection system where large numbers of neutrons can be produced using an accelerator with {approx}1 GeV energy and modest beam currents in the 1 to 100 {mu}A range. We will describe current work in the design of a 250 MeV, 1 mA superconducting accelerator and its extension to higher energies, and make estimates of sensitivity to reasonable amounts of shielded fissile material.

Lanza, Richard C. [Nuclear Science and Engineering Department Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Antaya, Timothy [Nuclear Science and Engineering Department Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Plasma Science and Fusion Center Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

2011-12-13

336

Remote listening and passive acoustic detection in a 3-D environment  

Science.gov (United States)

Teleconferencing environments are a necessity in business, education and personal communication. They allow for the communication of information to remote locations without the need for travel and the necessary time and expense required for that travel. Visual information can be communicated using cameras and monitors. The advantage of visual communication is that an image can capture multiple objects and convey them, using a monitor, to a large group of people regardless of the receiver's location. This is not the case for audio. Currently, most experimental teleconferencing systems' audio is based on stereo recording and reproduction techniques. The problem with this solution is that it is only effective for one or two receivers. To accurately capture a sound environment consisting of multiple sources and to recreate that for a group of people is an unsolved problem. This work will focus on new methods of multiple source 3-D environment sound capture and applications using these captured environments. Using spherical microphone arrays, it is now possible to capture a true 3-D environment A spherical harmonic transform on the array's surface allows us to determine the basis functions (spherical harmonics) for all spherical wave solutions (up to a fixed order). This spherical harmonic decomposition (SHD) allows us to not only look at the time and frequency characteristics of an audio signal but also the spatial characteristics of an audio signal. In this way, a spherical harmonic transform is analogous to a Fourier transform in that a Fourier transform transforms a signal into the frequency domain and a spherical harmonic transform transforms a signal into the spatial domain. The SHD also decouples the input signals from the microphone locations. Using the SHD of a soundfield, new algorithms are available for remote listening, acoustic detection, and signal enhancement The new algorithms presented in this paper show distinct advantages over previous detection and listening algorithms especially for multiple speech sources and room environments. The algorithms use high order (spherical harmonic) beamforming and power signal characteristics for source localization and signal enhancement These methods are applied to remote listening, surveillance, and teleconferencing.

Barnhill, Colin

337

The usefulness of MRI and PET imaging for the detection of parametrial involvement and lymph node metastasis in patients with cervical cancer  

International Nuclear Information System (INIS)

The purpose of this study is to elucidate the usefulness of magnetic resonance imaging (MRI) and positron emission tomography (PET) for the detection of parametrial involvement and lymph node metastasis in patients with cervical cancer. Thirty-six patients with cervical cancer were retrospectively enrolled. MRI and PET scans were performed for all patients within a week before radical surgery. The criterion for malignancy on MRI was >1 cm short axis diameter of the suspected lymph node. On PET, only fluorodeoxyglucose (FDG) uptake was significantly higher than the background and, if this FDG uptake showed on at least two consecutive axial slices, then the lesion was considered as a malignancy. We compared the extent of tumor on the surgical findings with the International Federation of Gynecology and Obstetrics (FIGO) staging, MRI and PET scans. The accuracy of FIGO and MRI staging was 67 and 84.4%, respectively. The accuracy for detecting pelvic lymph node metastasis was better for PET than for MRI (78 versus 67%, respectively). All FDG uptake lymph nodes were confirmed as metastatic lymph nodes by pathological evaluation; this included five lymph nodes <1 cm in diameter. MRI provides an improved evaluation of local tumor extension, but PET is more useful for the evaluation of pelvic lymph nodes than MRI; however, PET still misses microscopic disease. Further studies are necessary to evaluate the usefulness of PET/computed tomography (CT) for the accuracy of the disease extension and the cost-effectiveness of MRI, PET or PET/CT in patients with cervical cancer. (author)

338

Usefulness of MRI detection of cervical spine and brain injuries in the evaluation of abusive head trauma  

Energy Technology Data Exchange (ETDEWEB)

In the evaluation of children younger than 3 years with intracranial hemorrhage it can be difficult to determine whether the cause of hemorrhage was traumatic, and if so, whether abusive head trauma (AHT) is a possibility. Cervical spine MRI is not a routine part of the nationally recommended imaging workup for children with suspected abusive head trauma. There is increasing evidence that spinal injuries are found at autopsy or MRI in abused children. However the prevalence of cervical spine injuries in children evaluated for abusive head trauma is unknown. We sought to determine both the incidence and the spectrum of cervical spine and brain injuries in children being evaluated for possible abusive head trauma. We also examined the relationship between cervical and brain MRI findings and selected study outcome categories. This study is a 3-year retrospective review of children evaluated for abusive head trauma. Inclusion criteria were: children with head trauma seen at our institution between 2008 and 2010, age younger than 36 months, availability of diagnostic-quality brain and cervical spine MRI, and child abuse team involvement because abusive head trauma was a possibility. A child abuse pediatrician and pediatric radiologists, all with board certification, were involved in data collection, image interpretation and data analysis. Statistical analysis was performed using Stata v12.1. The study included 74 children (43 boys, 31 girls) with a mean age of 164 days (range, 20-679 days). Study outcomes were categorized as: n = 26 children with accidental head trauma, n = 38 with abusive head trauma (n = 18 presumptive AHT, n = 20 suspicious for AHT), and n = 10 with undefined head trauma. We found cervical spine injuries in 27/74 (36%) children. Most cervical spine injuries were ligamentous injuries. One child had intrathecal spinal blood and two had spinal cord edema; all three of these children had ligamentous injury. MRI signs of cervical injury did not show a statistically significant relationship with a study outcome of abusive head trauma or help discriminate between accidental and abusive head trauma. Of the 30 children with supratentorial brain injury, 16 (53%) had a bilateral hypoxic-ischemic pattern. There was a statistically significant relationship between bilateral hypoxic-ischemic brain injury pattern and abusive head trauma (P < 0.05). In addition, the majority (81%) of children with bilateral hypoxic-ischemic brain injuries had cervical injuries. Although detection of cervical spine injuries by MRI does not discriminate between accidental and abusive head trauma, it can help to distinguish a traumatic from non-traumatic intracranial subdural hemorrhage. Cervical MRI should be considered in children with acute intracranial bleeds and otherwise non-contributory history, physical examination and ophthalmological findings. There is a statistically significant relationship between diffuse hypoxic-ischemic brain injury patterns and abusive head trauma. The high incidence of cervical injuries in children with hypoxic-ischemic injuries suggests a causal relationship. Overall, increased utilization of brain and spine MRI in children being evaluated for abusive head trauma can be helpful. (orig.)

Kadom, Nadja [Children' s National Medical Center, Department of Diagnostic Imaging and Radiology, Washington, DC (United States); Boston University Medical Center, Boston, MA (United States); Khademian, Zarir; Vezina, Gilbert; Shalaby-Rana, Eglal [Children' s National Medical Center, Department of Diagnostic Imaging and Radiology, Washington, DC (United States); Rice, Amy [Independent Consultant (Biostatistics), Chevy Chase, MD (United States); Hinds, Tanya [Children' s National Medical Center, Child and Adolescent Protection Center, Washington, DC (United States)

2014-07-15

339

Usefulness of MRI detection of cervical spine and brain injuries in the evaluation of abusive head trauma  

International Nuclear Information System (INIS)

In the evaluation of children younger than 3 years with intracranial hemorrhage it can be difficult to determine whether the cause of hemorrhage was traumatic, and if so, whether abusive head trauma (AHT) is a possibility. Cervical spine MRI is not a routine part of the nationally recommended imaging workup for children with suspected abusive head trauma. There is increasing evidence that spinal injuries are found at autopsy or MRI in abused children. However the prevalence of cervical spine injuries in children evaluated for abusive head trauma is unknown. We sought to determine both the incidence and the spectrum of cervical spine and brain injuries in children being evaluated for possible abusive head trauma. We also examined the relationship between cervical and brain MRI findings and selected study outcome categories. This study is a 3-year retrospective review of children evaluated for abusive head trauma. Inclusion criteria were: children with head trauma seen at our institution between 2008 and 2010, age younger than 36 months, availability of diagnostic-quality brain and cervical spine MRI, and child abuse team involvement because abusive head trauma was a possibility. A child abuse pediatrician and pediatric radiologists, all with board certification, were involved in data collection, image interpretation and data analysis. Statistical analysis was performed using Stata v12.1. The study included 74 children (43 boys, 31 girls) with a mean age of 164 days (range, 20-679 days). Study outcomes were categorized as: n = 26 children with accidental head trauma, n = 38 with abusive head trauma (n = 18 presumptive AHT, n = 20 suspicious for AHT), and n = 10 with undefined head trauma. We found cervical spine injuries in 27/74 (36%) children. Most cervical spine injuries were ligamentous injuries. One child had intrathecal spinal blood and two had spinal cord edema; all three of these children had ligamentous injury. MRI signs of cervical injury did not show a statistically significant relationship with a study outcome of abusive head trauma or help discriminate between accidental and abusive head trauma. Of the 30 children with supratentorial brain injury, 16 (53%) had a bilateral hypoxic-ischemic pattern. There was a statistically significant relationship between bilateral hypoxic-ischemic brain injury pattern and abusive head trauma (P < 0.05). In addition, the majority (81%) of children with bilateral hypoxic-ischemic brain injuries had cervical injuries. Although detection of cervical spine injuries by MRI does not discriminate between accidental and abusive head trauma, it can help to distinguish a traumatic from non-traumatic intracranial subdural hemorrhage. Cervical MRI should be considered in children with acute intracranial bleeds and otherwise non-contributory history, physical examination and ophthalmological findings. There is a statistically significant relationship between diffuse hypoxic-ischemic brain injury patterns and abusive head trauma. The high incidence of cervical injuries in children with hypoxic-ischemic injuries suggests a causal relationship. Overall, increased utilization of brain and spine MRI in children being evaluated for abusive head trauma can be helpful. (orig.)

340

Transient detection of early wallerian degeneration on diffusion-weighted MRI after an acute cerebrovascular accident  

Energy Technology Data Exchange (ETDEWEB)

We report three patients with a cerebrovascular accident studied serially by MRI, including diffusion-weighted imaging (DWI). In case 1, DWI 1 day after the onset of left frontoparietal cortical infarcts showed no abnormal signal in the left corticospinal tract. DWI 12 days after onset showed high signal in the corticospinal tract, interpreted as early wallerian degeneration. This had disappeared by 22 days after onset. In case 2, DWI obtained 7 days after the onset of a right internal capsule lacunar infarct showed high signal from the right corticospinal tract in the brainstem, which was less marked 15 days after onset. In case 3, MRI on postnatal day 7 showed a cerebral haemorrhage in the right corona radiata and high signal from the right corticospinal tract on DWI. The latter disappeared by day 23. DWI shows early wallerian degeneration; transient signal abnormalities within 2 weeks of stroke should not be mistaken for new ischaemic lesions. (orig.)

Uchino, A.; Sawada, A.; Takase, Y.; Egashira, R.; Kudo, S. [Department of Radiology, Saga Medical School, 5-1-1 Nabeshima, Saga, 849-8501 (Japan)

2004-03-01

 
 
 
 
341

Influence of imaging and histological factors on prostate cancer detection and localisation on multiparametric MRI: a prospective study  

International Nuclear Information System (INIS)

To assess factors influencing prostate cancer detection on multiparametric (T2-weighted, diffusion-weighted, and dynamic contrast-enhanced) MRI. One hundred and seventy-five patients who underwent radical prostatectomy were included. Pre-operative MRI performed at 1.5 T (n = 71) or 3 T (n = 104), with (n = 58) or without (n = 117) an endorectal coil were independently interpreted by two radiologists. A five-point subjective suspicion score (SSS) was assigned to all focal abnormalities (FAs). MR findings were then compared with whole-mount sections. Readers identified 192-214/362 cancers, with 130-155 false positives. Detection rates for tumours of 3), 0.5-2 cc and >2 cc were 33-45/155 (21-29 %), 15-19/35 (43-54 %) and 8-9/12 (67-75 %) for Gleason ?6, 17/27 (63 %), 42-45/51 (82-88 %) and 34/35 (97 %) for Gleason 7 and 4/5 (80 %), 13/14 (93 %) and 28/28 (100 %) for Gleason ?8 cancers respectively. At multivariate analysis, detection rates were influenced by tumour Gleason score, histological volume, histological architecture and location (P < 0.0001), but neither by field strength nor coils used for imaging. The SSS was a significant predictor of both malignancy of FAs (P < 0.005) and aggressiveness of tumours (P < 0.00001). Detection rates were significantly influenced by tumour characteristics, but neither by field strength nor coils used for imaging. The SSS significantly stratified the risk of malignancy of FAs and aggressiveness of detected tumours. (orig.)

342

Influence of imaging and histological factors on prostate cancer detection and localisation on multiparametric MRI: a prospective study  

Energy Technology Data Exchange (ETDEWEB)

To assess factors influencing prostate cancer detection on multiparametric (T2-weighted, diffusion-weighted, and dynamic contrast-enhanced) MRI. One hundred and seventy-five patients who underwent radical prostatectomy were included. Pre-operative MRI performed at 1.5 T (n = 71) or 3 T (n = 104), with (n = 58) or without (n = 117) an endorectal coil were independently interpreted by two radiologists. A five-point subjective suspicion score (SSS) was assigned to all focal abnormalities (FAs). MR findings were then compared with whole-mount sections. Readers identified 192-214/362 cancers, with 130-155 false positives. Detection rates for tumours of <0.5 cc (cm{sup 3}), 0.5-2 cc and >2 cc were 33-45/155 (21-29 %), 15-19/35 (43-54 %) and 8-9/12 (67-75 %) for Gleason {<=}6, 17/27 (63 %), 42-45/51 (82-88 %) and 34/35 (97 %) for Gleason 7 and 4/5 (80 %), 13/14 (93 %) and 28/28 (100 %) for Gleason {>=}8 cancers respectively. At multivariate analysis, detection rates were influenced by tumour Gleason score, histological volume, histological architecture and location (P < 0.0001), but neither by field strength nor coils used for imaging. The SSS was a significant predictor of both malignancy of FAs (P < 0.005) and aggressiveness of tumours (P < 0.00001). Detection rates were significantly influenced by tumour characteristics, but neither by field strength nor coils used for imaging. The SSS significantly stratified the risk of malignancy of FAs and aggressiveness of detected tumours. (orig.)

Bratan, Flavie [Hopital Edouard Herriot, Hospices Civils de Lyon, Department of Urinary and Vascular Radiology, Lyon (France); Inserm, U1032, LabTau, Lyon (France); Niaf, Emilie [Inserm, U1032, LabTau, Lyon (France); CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Villeurbanne (France); Melodelima, Christelle [Universite Joseph Fourier, Laboratoire d' Ecologie Alpine, CNRS UMR 5553, BP 53, Grenoble (France); Chesnais, Anne Laure; Mege-Lechevallier, Florence [Hopital Edouard Herriot, Hospices Civils de Lyon, Department of Pathology, Lyon (France); Souchon, Remi [Inserm, U1032, LabTau, Lyon (France); Colombel, Marc [Universite de Lyon, Lyon (France); Universite Lyon 1, Faculte de Medecine Lyon Est, Lyon (France); Hopital Edouard Herriot, Hospices Civils de Lyon, Department of Urology, Lyon (France); Rouviere, Olivier [Hopital Edouard Herriot, Hospices Civils de Lyon, Department of Urinary and Vascular Radiology, Lyon (France); Inserm, U1032, LabTau, Lyon (France); Universite de Lyon, Lyon (France); Universite Lyon 1, Faculte de Medecine Lyon Est, Lyon (France); Hopital E. Herriot, Service de Radiologie Urinaire et Vasculaire, Pavillon P, Lyon Cedex 03 (France)

2013-07-15

343

Cest Analysis: Automated Change Detection from Very-High Remote Sensing Images  

Science.gov (United States)

A fast detection, visualization and assessment of change in areas of crisis or catastrophes are important requirements for coordination and planning of help. Through the availability of new satellites and/or airborne sensors with very high spatial resolutions (e.g., WorldView, GeoEye) new remote sensing data are available for a better detection, delineation and visualization of change. For automated change detection, a large number of algorithms has been proposed and developed. From previous studies, however, it is evident that to-date no single algorithm has the potential for being a reliable change detector for all possible scenarios. This paper introduces the Combined Edge Segment Texture (CEST) analysis, a decision-tree based cooperative suite of algorithms for automated change detection that is especially designed for the generation of new satellites with very high spatial resolution. The method incorporates frequency based filtering, texture analysis, and image segmentation techniques. For the frequency analysis, different band pass filters can be applied to identify the relevant frequency information for change detection. After transforming the multitemporal images via a fast Fourier transform (FFT) and applying the most suitable band pass filter, different methods are available to extract changed structures: differencing and correlation in the frequency domain and correlation and edge detection in the spatial domain. Best results are obtained using edge extraction. For the texture analysis, different 'Haralick' parameters can be calculated (e.g., energy, correlation, contrast, inverse distance moment) with 'energy' so far providing the most accurate results. These algorithms are combined with a prior segmentation of the image data as well as with morphological operations for a final binary change result. A rule-based combination (CEST) of the change algorithms is applied to calculate the probability of change for a particular location. CEST was tested with high-resolution satellite images of the crisis areas of Darfur (Sudan). CEST results are compared with a number of standard algorithms for automated change detection such as image difference, image ratioe, principal component analysis, delta cue technique and post classification change detection. The new combined method shows superior results averaging between 45% and 15% improvement in accuracy.

Ehlers, M.; Klonus, S.; Jarmer, T.; Sofina, N.; Michel, U.; Reinartz, P.; Sirmacek, B.

2012-08-01

344

T2-weighted MRI detects presymptomatic pathology in the SOD1 mouse model of ALS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Neuroinflammation has been identified as a potential therapeutic target in amyotrophic lateral sclerosis (ALS), but relevant biomarkers are needed. The superoxide dismutase (SOD1)G93A transgenic mouse model of ALS offers a unique opportunity to study and potentially manipulate presymptomatic pathology. While T2-weighted magnetic resonance imaging (MRI) has been shown to be sensitive to pathologic changes at symptom onset, no earlier biomarkers were previously identified and the underlying his...

Evans, Mc; Serres, S.; Khrapitchev, Aa; Stolp, Hb; Anthony, Dc; Talbot, K.; Turner; Sibson, Nr

2014-01-01

345

T?-weighted MRI detects presymptomatic pathology in the SOD1 mouse model of ALS.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Neuroinflammation has been identified as a potential therapeutic target in amyotrophic lateral sclerosis (ALS), but relevant biomarkers are needed. The superoxide dismutase (SOD1)(G93A) transgenic mouse model of ALS offers a unique opportunity to study and potentially manipulate presymptomatic pathology. While T?-weighted magnetic resonance imaging (MRI) has been shown to be sensitive to pathologic changes at symptom onset, no earlier biomarkers were previously identified and the underlying...

Evans, Mc; Serres, S.; Khrapitchev, Aa; Stolp, Hb; Anthony, Dc; Talbot, K.; Turner; Sibson, Nr

2014-01-01

346

MRI of prostate cancer using three different coil systems: image quality, tumor detection, and staging  

International Nuclear Information System (INIS)

Purpose: To compare three MRI coil systems in terms of image quality, delineation of prostate cancer, and tumor staging. Materials and Methods: 49 patients with prostate cancer underwent MRI at 1.5 Tesla using a combination of an endorectal coil with a phased-array body coil (combination coil) prior to radical prostatectomy. Images were reconstructed from the data sets acquired with the endorectal coil alone and from those acquired with the combined coil. In addition, 19 patients of the study patients were examined with the body phased-array coil alone without the endorectal coil. The prostate was imaged at a slice thickness of 3 mm using axial and coronal T2-weighted sequences and an axial T1-weighted sequence. Preoperative analysis of all images acquired was done to determine the accuracy of MRI in local staging of prostate cancer. An additional retrospective analysis served to compare the different coil systems in terms of overall image quality, delineation and localization of the tumor, and criteria for local staging of prostate cancer. Results: Preoperative analysis showed MRI to have an accuracy of 59% in local tumor staging. Retrospective coil-by-coil analysis demonstrated image quality and tumor delineation to be best for the combination coil and the endorectal coil. Regarding the staging criteria for transcapsular tumor extension and infiltration of adjacent organs, a significant advantage of the combination coil compared to the endorectal coil was identified only for the criterion of smooth bulging. In addition, the endorectal coil and the combination coil were found to be superior to the body phased-array coil in assessing 15 of 17 criteria for local tumor staging but the differences were not significant. Conclusion: In view of the achieved superior image quality, the combination coil or the endorectal coil is the preferred method for staging prostate cancer. (orig.)

347

Detection of multifocal osteonecrosis in an adolescent with dermatomyositis using whole-body MRI  

Energy Technology Data Exchange (ETDEWEB)

Osteonecrosis is a well-recognized complication of corticosteroid use resulting in significant morbidity, often requiring surgical intervention. Whole-body MRI is a promising method that allows imaging of the whole patient in a reasonable time without the use of ionizing radiation. This technique has the potential for evaluating nonmalignant multifocal skeletal disease like osteonecrosis. This case highlights the value of whole-body MR in an adolescent with dermatomyositis who developed multifocal osteonecrosis. (orig.)

Castro, Tania C.M.; Terreri, Maria Teresa A.; Hilario, Maria Odete E. [Federal University of Sao Paulo, Department of Pediatrics, Division of Allergy, Clinical Immunology and Rheumatology, Sao Paulo, SP (Brazil); Lederman, Henrique [Federal University of Sao Paulo, Image Diagnosis Department, Sao Paulo (Brazil); Kaste, Sue C. [St. Jude Children' s Research Hospital, Department of Radiological Sciences, Division of Diagnostic Imaging, Memphis, TN (United States)

2010-09-15

348

Quantitative structural MRI for early detection of Alzheimer’s disease  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Alzheimer’s disease (AD) is a common progressive neurodegenerative disorder that is not currently diagnosed until a patient reaches the stage of dementia. There is a pressing need to identify AD at an earlier stage, so that treatment, when available, can begin early. Quantitative structural MRI is sensitive to the neurodegeneration that occurs in mild and preclinical AD, and is predictive of decline to dementia in individuals with mild cognitive impairment. Objective evidence of ongoing bra...

Mcevoy, Linda