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1

Amplification of Xenon NMR and MRI by remote detection  

Energy Technology Data Exchange (ETDEWEB)

A novel technique is proposed in which a nuclear magneticresonance (NMR) spectrum or magnetic resonance image (MRI) is encoded andstored as spin polarization and is then moved to a different physicallocation to be detected. Remote detection allows the separateoptimization of the encoding and detection steps, permitting theindependent choice of experimental conditions, and excitation anddetection methodologies. In the first experimental demonstration of thistechnique, we show that NMR signal can be amplified by taking diluted129Xe from a porous sample placed inside a large encoding coil, andconcentrating it into a smaller detection coil. In general, the study ofNMR active molecules at low concentration that have low physical fillingfactor is facilitated by remote detection. In the second experiment, MRIinformation encoded in a very low field magnet (4-7mT) is transferred toa high field magnet (4.2 T) in order to be detected under optimizedconditions. Furthermore, remote detection allows the utilization ofultra-sensitive optical or superconducting detection techniques, whichbroadens the horizon of NMR experimentation.

Moule, Adam J.; Spence, Megan M.; Han, Song-I.; Seeley, JulietteA.; Pierce, Kimberly L.; Saxena, Sunil; Pines, Alexander

2003-03-31

2

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

3

Remote detection system  

Energy Technology Data Exchange (ETDEWEB)

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.

Nixon, K.V.; France, S.W.; Garcia, C.; Hastings, R.D.

1981-05-01

4

Remote control catheter navigation: options for guidance under MRI.  

UK PubMed Central (United Kingdom)

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 L; Saeed M; Wilson MW; Hetts SW

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; Saeed Maythem; Wilson Mark W; Hetts Steven W

2012-01-01

6

Role of MRI in prostate cancer detection.  

Science.gov (United States)

The standard approach for the detection of prostate cancer -- prostate-specific antigen (PSA) screening followed by transrectal ultrasonography (TRUS)-guided biopsy -- has low sensitivity and provides limited information about the true extent and aggressiveness of the cancer. Improved methods are needed to assess the extent and aggressiveness of the cancer and to identify patients who will benefit from therapy. In recent years, there has been tremendous development of acquisition and processing tools for physiological and metabolic MRI techniques which play a potential role in the detection, localization and characterization of prostate cancer, such as dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted MRI (DW-MRI) and/or proton MR spectroscopic imaging ((1) H MRSI). The standard protocol for prostate MRI without the use of a contrast agent involves multi-planar T1 -weighted MRI, T2 -weighted MRI and DW-MRI. This review discusses the potential role of MRI in the detection of prostate cancer, specifically describing the status of MRI as a tool for guiding targeted prostate biopsies and for detecting cancer in the untreated and treated gland. In addition, future areas of MRI research are briefly discussed. Groups conducting clinical trials should consider the recommendations put forward by the European Consensus Meeting, which state that the minimum requirements for prostate MRI are T1 -weighted MRI, T2 -weighted MRI, DCE-MRI (which involves the use of a contrast agent) and DW-MRI with a pelvic phased-array coil and propose the use of transperineal template mapping biopsies as the optimal reference standard. Copyright © 2013 John Wiley & Sons, Ltd. PMID:23495081

Shukla-Dave, Amita; Hricak, Hedvig

2013-03-13

7

Detecting coal fires using remote sensing techniques  

Energy Technology Data Exchange (ETDEWEB)

This paper gives an overview of the theory and case studies of detecting coal fires by using remote sensing techniques. Coal fires, either man-made or spontaneous combustion, not only cause losses of natural resources, but also cause environmental problems. The surface feature and by-products of coal fires include pyro-metamorphic rocks, fumarolic minerals, burnt pits and trench, subsidence and cracks, and surface thermal anomalies. These features can be detected from visible, near infrared, short-wave infrared, radar and thermal infrared remote sensing images. The ability to detect these features is limited by the spectral, spatial and temporal resolution of the remote sensing data. The advances of new remote sensing systems will enhance the capability to detect coal fire related features.

Zhang, J.; Wagner, W.; Prakash, A.; Mehl, H.; Voigt, S. [German Aerospace Center DLR, Wessling (Germany). German Remote Sensing Data Center DFD

2004-08-01

8

Website Detection Using Remote Traffic Analysis  

CERN Multimedia

Recent work in traffic analysis has shown that traffic patterns leaked through side channels can be used to recover important semantic information. For instance, attackers can find out which website, or which page on a website, a user is accessing simply by monitoring the packet size distribution. We show that traffic analysis is even a greater threat to privacy than previously thought by introducing a new attack that can be carried out remotely. In particular, we show that, to perform traffic analysis, adversaries do not need to directly observe the traffic patterns. Instead, they can gain sufficient information by sending probes from a far-off vantage point that exploits a queuing side channel in routers. To demonstrate the threat of such remote traffic analysis, we study a remote website detection attack that works against home broadband users. Because the remotely observed traffic patterns are more noisy than those obtained using previous schemes based on direct local traffic monitoring, we take a dynamic...

Gong, Xun; Schear, Nabíl; Borisov, Nikita

2011-01-01

9

Remote detection of explosives using trained canines  

Energy Technology Data Exchange (ETDEWEB)

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. (DLC)

Smith, J.C.

1983-03-01

10

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

1983-01-01

11

Remote sensing for oil spill detection and response  

Energy Technology Data Exchange (ETDEWEB)

This paper focuses on the use of remote sensing for marine oil spill detection and response. The surveillance and monitoring of discharges, and the main elements of effective surveillance are discussed. Tactical emergency response and the requirements for selecting a suitable remote sensing approach, airborne remote sensing systems, and the integration of satellite and airborne imaging are examined. Specifications of satellite surveillance systems potentially usable for oil spill detection, and specifications of airborne remote sensing systems suitable for oil spill detection, monitoring and supplemental actions are tabulated, and a schema of integrated satellite-airborne remote sensing (ISARS) is presented. (UK)

Engelhardt, F.R. [ENOVA Research Applications, Orleans, ON (Canada)

1999-01-01

12

Remote detection of rhizomania in sugar beets.  

Science.gov (United States)

ABSTRACT As a prelude to remote sensing of rhizomania, hyper-spectral leaf reflectance and multi-spectral canopy reflectance were used to study the physiological differences between healthy sugar beets and beets infested with Beet necrotic yellow vein virus. This study was conducted over time in the presence of declining nitrogen levels. Total leaf nitrogen was significantly lower in symptomatic beets than in healthy beets. Chlorophyll and carotenoid levels were reduced in symptomatic beets. Vegetative indices calculated from leaf spectra showed reductions in chlorophyll and carotenoids in symptomatic beets. Betacyanin levels estimated from leaf spectra were decreased at the end of the 2000 season and not in 2001. The ratio of betacyanins to chlorophyll, estimated from canopy spectra, was increased in symptomatic beets at four of seven sampling dates. Differences in betacyanin and carotenoid levels appeared to be related to disease and not nitrogen content. Vegetative indices calculated from multi-spectral canopy spectra supported results from leaf spectra. Logistic regression models that incorporate vegetative indices and reflectance correctly predicted 88.8% of the observations from leaf spectra and 87.9% of the observations for canopy reflectance into healthy or symptomatic classes. Classification was best in August with a gradual decrease in accuracy until harvest. These results indicate that remote sensing technologies can facilitate detection of rhizomania. PMID:18943059

Steddom, K; Heidel, G; Jones, D; Rush, C M

2003-06-01

13

Remote detection of rhizomania in sugar beets.  

UK PubMed Central (United Kingdom)

ABSTRACT As a prelude to remote sensing of rhizomania, hyper-spectral leaf reflectance and multi-spectral canopy reflectance were used to study the physiological differences between healthy sugar beets and beets infested with Beet necrotic yellow vein virus. This study was conducted over time in the presence of declining nitrogen levels. Total leaf nitrogen was significantly lower in symptomatic beets than in healthy beets. Chlorophyll and carotenoid levels were reduced in symptomatic beets. Vegetative indices calculated from leaf spectra showed reductions in chlorophyll and carotenoids in symptomatic beets. Betacyanin levels estimated from leaf spectra were decreased at the end of the 2000 season and not in 2001. The ratio of betacyanins to chlorophyll, estimated from canopy spectra, was increased in symptomatic beets at four of seven sampling dates. Differences in betacyanin and carotenoid levels appeared to be related to disease and not nitrogen content. Vegetative indices calculated from multi-spectral canopy spectra supported results from leaf spectra. Logistic regression models that incorporate vegetative indices and reflectance correctly predicted 88.8% of the observations from leaf spectra and 87.9% of the observations for canopy reflectance into healthy or symptomatic classes. Classification was best in August with a gradual decrease in accuracy until harvest. These results indicate that remote sensing technologies can facilitate detection of rhizomania.

Steddom K; Heidel G; Jones D; Rush CM

2003-06-01

14

Remote Optical Detection of Alpha Radiation  

International Nuclear Information System (INIS)

Alpha emitting radiation sources are typically hard to detect with conventional detectors due to the short range of alpha particles in the air. However, previous studies have shown that remote detection of alpha radiation is possible by measuring the ionization-induced fluorescence of air molecules. The alpha-induced ultraviolet (UV) light is mainly emitted by molecular nitrogen and its fluorescence properties are well known. The benefit of this method is the long range of UV photons in the air. Secondly, the detection is possible also under a strong beta and gamma radiation backgrounds as they do not cause localized molecular excitation. In this work, the optical detection was studied using two different detection schemes; spectral separation of fluorescence from the background lighting and coincidence detection of UV photons originating from a single radiative decay event. Our spectrally integrated measurements have shown that one alpha decay event yields up to 400 fluorescence photons in the air and all these UV photons are induced in a 5 ns time-window. On the other hand, the probability of a background coincidence event in 5 ns scale is very rare compared to the number of background photons. This information can be applied in fluorescence coincidence filtering to discriminate the alpha radiation initiated fluorescence signal from much more intense background lighting. A device called HAUVA (Handheld Alpha UV Application) was built during this work for demonstration purposes. HAUVA utilizes spectral filtering and it is designed to detect alpha emitters from a distance of about 40 cm. Using specially selected room lighting, the device is able to separate 1 kBq alpha emitter from the background lighting with 1 second integration time. (author)

2010-01-01

15

Detection of a deep lipoblastoma by MRI and ultrasound.  

UK PubMed Central (United Kingdom)

Lipoblastoma is a rare benign tumor of the soft tissue occurring predominantly during the first two years of life. We report here the application of MRI and ultrasound to the detection of a soft tissue lipoblastoma. By MRI and ultrasound, we precisely evaluated the extent of the tumor, the presence of atypical areas of cystic and mucoid degeneration within the tumor, and its lack of vascularity. Our patient's lipoblastoma did not demonstrate the signal characteristics of a fatty tumor on MRI.

Schultz E; Rosenblatt R; Mitsudo S; Weinberg G

1993-01-01

16

Detecting hydrocarbon microseepage using remotely sensed data  

Energy Technology Data Exchange (ETDEWEB)

Many petroleum reservoirs leak, and the upwardly migrating hydrocarbons and associated fluids can produce a series of chemical changes that may affect plant physiology and the mineralogical and physical attributes of the overlying strata. Alterations manifested the surface depend on the composition of both the upwardly migrating fluid and the strata overlying the leaking reservoir. These alterations may appear on airborne spectroradiometric or satellite multispectral data as tonal (mineral or plant spectral) or textural (geomorphic or plant ecological) anomalies, or both. Examples include: (1) bleaching of red beds due to loss of hematite and/or anomalous clay mineral distributions in strata overlying petroleum accumulations at Lisbon Valley, Utah, and at Cement and Velma fields, Oklahoma; (2) mineral alterations such as replacement of calcium sulfates by calcite at Cement, Oklahoma, and Limestone Buttes, Gypsum Plain, Texas, resulting in anomalous geomorphology; and (3) geobotanical manifestations caused by soil chemistry variations resulting in anomalous plant communities above Lost River gas field, West Virginia, or physiological alteration (stunting) of plant communities such as at Patrick Draw field, Wyoming. The diagnostic visible and near-infrared absorption features exhibited by iron oxides, clay minerals, and botanical assemblages permit airborne and satellite-borne sensors to be used to distinguish and map spatial patterns of these materials, and form the basis for remote detection of surficial phenomena that may indicate hydrocarbon microseepage. The ability to detect these anomalies using remotely sensed data depends on the susceptibility of the surface to alteration, the inherent heterogeneity of the surface, and the degree of exposure.

Merin, I.S.; Segal, D.B.; Staskowski, R.J.; Everett, J.R.

1986-05-01

17

MRI diagnosis of hypertrophic osteoarthropathy from a remote childhood malignancy  

International Nuclear Information System (INIS)

Hypertrophic osteoarthropathy (HOA) is a clinico-radiological syndrome characterized by digital clubbing, periosteal proliferation, bone pain, synovitis and arthralgia, all of these being commonly symmetrical. It is occasionally associated with nasopharyngeal lymphoepitheliomas and may develop before or after development of lung metastases in these patients. We report a case of a healthy 22-year-old female who presented to our institution with pain and swelling in the thighs and legs. She had a history of childhood nasopharyngeal lymphoepithelioma. Radiographs of the knees were negative. Magnetic resonance imaging (MRI) showed features suggestive of bilateral periostitis. Because of the propensity of the rare childhood nasopharyngeal lymphoepithelioma to present with HOA, this entity was included in the differential diagnosis. A subsequent chest radiograph and CT demonstrated a lung and mediastinal mass that were histologically confirmed to be metastatic. To the best of our knowledge, HOA and metastases from nasopharyngeal lymphoepithelioma occurring after such a long time interval have not been previously reported. Early demonstration and consideration of HOA on the basis of MRI, lead to expeditious and appropriate subsequent investigation. (orig.)

2007-01-01

18

MRI for occult physeal fracture detection in children and adolescents.  

Science.gov (United States)

BackgroundConventional radiography has limitations in the detection of physeal fractures before the closure of the physis occurs. Fracture detection may be improved by using magnetic resonance imaging (MRI).PurposeTo evaluate the usefulness of MRI for the detection of occult fractures involving the physis when radiography results are negative.Material and MethodsIn this prospective study, 24 children (age range, 3-15 years; mean age, 10.7 years) received MRI if they met the following criteria: acute joint trauma, swelling and tenderness around the joint, limitations in bearing weight, an open physis, and negative radiography results for fractures. Fractures revealed by the MRI were classified according to the Salter-Harris classification system. Joint effusion, bone marrow edema, and periosteal alterations were graded on a three-point scale. The non-parametric Wilcoxon test and Fisher's exact test were used for the statistical evaluation.ResultsFrom a total of 24 MR data-sets, 23 were evaluated (one patient was excluded due to poor MR image quality). Elbow injuries were present in 10 patients (43.5%), distal tibia injuries in 10 patients (43.5%), and distal femur injuries in three patients (13%). MRI results excluded physeal fractures in 15 (65.2%) of the 23 children. An occult physeal fracture was detected with MRI in eight (34.8%) patients; of these, five (21.7%) had fractures of the elbow, two (8.7%) had fractures of the distal tibia, and one (4.3%) had a fracture of the distal femur. All of the patients with fractures and 11 of the 15 patients without fractures demonstrated bone marrow edema.ConclusionThe frequency of occult fracture, as detected by MRI, was 34.8%. Thus, MRI is a useful additional imaging method for the detection of occult fractures when radiography is negative. PMID:23436831

Gufler, Hubert; Schulze, Christian Georg; Wagner, Sabine; Baumbach, Lutz

2013-02-23

19

MRI for occult physeal fracture detection in children and adolescents.  

UK PubMed Central (United Kingdom)

BackgroundConventional radiography has limitations in the detection of physeal fractures before the closure of the physis occurs. Fracture detection may be improved by using magnetic resonance imaging (MRI).PurposeTo evaluate the usefulness of MRI for the detection of occult fractures involving the physis when radiography results are negative.Material and MethodsIn this prospective study, 24 children (age range, 3-15 years; mean age, 10.7 years) received MRI if they met the following criteria: acute joint trauma, swelling and tenderness around the joint, limitations in bearing weight, an open physis, and negative radiography results for fractures. Fractures revealed by the MRI were classified according to the Salter-Harris classification system. Joint effusion, bone marrow edema, and periosteal alterations were graded on a three-point scale. The non-parametric Wilcoxon test and Fisher's exact test were used for the statistical evaluation.ResultsFrom a total of 24 MR data-sets, 23 were evaluated (one patient was excluded due to poor MR image quality). Elbow injuries were present in 10 patients (43.5%), distal tibia injuries in 10 patients (43.5%), and distal femur injuries in three patients (13%). MRI results excluded physeal fractures in 15 (65.2%) of the 23 children. An occult physeal fracture was detected with MRI in eight (34.8%) patients; of these, five (21.7%) had fractures of the elbow, two (8.7%) had fractures of the distal tibia, and one (4.3%) had a fracture of the distal femur. All of the patients with fractures and 11 of the 15 patients without fractures demonstrated bone marrow edema.ConclusionThe frequency of occult fracture, as detected by MRI, was 34.8%. Thus, MRI is a useful additional imaging method for the detection of occult fractures when radiography is negative.

Gufler H; Schulze CG; Wagner S; Baumbach L

2013-02-01

20

SQUID-detected ultra-low field MRI.  

UK PubMed Central (United Kingdom)

MRI remains the premier method for non-invasive imaging of soft-tissue. Since the first demonstration of ULF MRI the trend has been towards ever higher magnetic fields. This is because the signal, and efficiency of Faraday detectors, increases with ever higher magnetic fields and corresponding Larmor frequencies. Nevertheless, there are many compelling reasons to continue to explore MRI at much weaker magnetic fields, the so-called ultra-low field or (ULF) regime. In the past decade many excellent proof-of-concept demonstrations of ULF MRI have been made. These include combined MRI and magnetoencephalography, imaging in the presence of metal, unique tissue contrast, and implementation in situations where a high magnetic field is simply impractical. These demonstrations have routinely used pulsed pre-polarization (at magnetic fields from ?10 to 100mT) followed by read-out in a much weaker (1-100?T) magnetic fields using the ultra-sensitive Superconducting Quantum Interference Device (SQUID) sensor. Even with pre-polarization and SQUID detection, ULF MRI suffers from many challenges associated with lower magnetization (i.e. signal) and inherently long acquisition times compared to conventional >1T MRI. These are fundamental limitations imposed by the low measurement and gradient fields used. In this review article we discuss some of the techniques, potential applications, and inherent challenges of ULF MRI.

Espy M; Matlashov A; Volegov P

2013-03-01

 
 
 
 
21

SQUID-detected ultra-low field MRI  

Science.gov (United States)

MRI remains the premier method for non-invasive imaging of soft-tissue. Since the first demonstration of ULF MRI the trend has been towards ever higher magnetic fields. This is because the signal, and efficiency of Faraday detectors, increases with ever higher magnetic fields and corresponding Larmor frequencies. Nevertheless, there are many compelling reasons to continue to explore MRI at much weaker magnetic fields, the so-called ultra-low field or (ULF) regime. In the past decade many excellent proof-of-concept demonstrations of ULF MRI have been made. These include combined MRI and magnetoencephalography, imaging in the presence of metal, unique tissue contrast, and implementation in situations where a high magnetic field is simply impractical. These demonstrations have routinely used pulsed pre-polarization (at magnetic fields from ˜10 to 100 mT) followed by read-out in a much weaker (1-100 ?T) magnetic fields using the ultra-sensitive Superconducting Quantum Interference Device (SQUID) sensor. Even with pre-polarization and SQUID detection, ULF MRI suffers from many challenges associated with lower magnetization (i.e. signal) and inherently long acquisition times compared to conventional >1 T MRI. These are fundamental limitations imposed by the low measurement and gradient fields used. In this review article we discuss some of the techniques, potential applications, and inherent challenges of ULF MRI.

Espy, Michelle; Matlashov, Andrei; Volegov, Petr

2013-04-01

22

SQUID-detected ultra-low field MRI.  

UK PubMed Central (United Kingdom)

MRI remains the premier method for non-invasive imaging of soft-tissue. Since the first demonstration of ULF MRI the trend has been towards ever higher magnetic fields. This is because the signal, and efficiency of Faraday detectors, increases with ever higher magnetic fields and corresponding Larmor frequencies. Nevertheless, there are many compelling reasons to continue to explore MRI at much weaker magnetic fields, the so-called ultra-low field or (ULF) regime. In the past decade many excellent proof-of-concept demonstrations of ULF MRI have been made. These include combined MRI and magnetoencephalography, imaging in the presence of metal, unique tissue contrast, and implementation in situations where a high magnetic field is simply impractical. These demonstrations have routinely used pulsed pre-polarization (at magnetic fields from ~10 to 100 mT) followed by read-out in a much weaker (1-100 ?T) magnetic fields using the ultra-sensitive Superconducting Quantum Interference Device (SQUID) sensor. Even with pre-polarization and SQUID detection, ULF MRI suffers from many challenges associated with lower magnetization (i.e. signal) and inherently long acquisition times compared to conventional >1 T MRI. These are fundamental limitations imposed by the low measurement and gradient fields used. In this review article we discuss some of the techniques, potential applications, and inherent challenges of ULF MRI.

Espy M; Matlashov A; Volegov P

2013-04-01

23

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 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)

2000-01-01

24

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; Dr.Tanuja Sarode,; Ms.Kavita Raut

2010-01-01

25

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 (

1999-01-01

26

Automated detection of multiple sclerosis lesions in serial brain MRI  

Energy Technology Data Exchange (ETDEWEB)

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 single studies with the analysis of the change detection in serial MRI. (orig.)

Llado, Xavier; Ganiler, Onur; Oliver, Arnau; Marti, Robert; Freixenet, Jordi [University of Girona, Computer Vision and Robotics Group, Girona (Spain); Valls, Laia [Dr. Josep Trueta University Hospital, Department of Radiology, Girona (Spain); Vilanova, Joan C. [Girona Magnetic Resonance Center, Girona (Spain); Ramio-Torrenta, Lluis [Dr. Josep Trueta University Hospital, Institut d' Investigacio Biomedica de Girona, Multiple Sclerosis and Neuroimmunology Unit, Girona (Spain); Rovira, Alex [Vall d' Hebron University Hospital, Magnetic Resonance Unit, Department of Radiology, Barcelona (Spain)

2012-08-15

27

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 single studies with the analysis of the change detection in serial MRI. (orig.)

2012-01-01

28

A low cost fMRI-compatible tracking system using the Nintendo Wii remote.  

UK PubMed Central (United Kingdom)

It is sometimes necessary during functional magnetic resonance imaging (fMRI) experiments to capture different movements made by the subjects, e.g. to enable them to control an item or to analyze its kinematics. The aim of this work is to present an inexpensive hand tracking system suitable for use in a high field MRI environment. It works by introducing only one light-emitting diode (LED) in the magnet room, and by receiving its signal with a Nintendo Wii remote (the primary controller for the Nintendo Wii console) placed outside in the control room. Thus, it is possible to take high spatial and temporal resolution registers of a moving point that, in this case, is held by the hand. We tested it using a ball and racket virtual game inside a 3 Tesla MRI scanner to demonstrate the usefulness of the system. The results show the involvement of a number of areas (mainly occipital and frontal, but also parietal and temporal) when subjects are trying to stop an object that is approaching from a first person perspective, matching previous studies performed with related visuomotor tasks. The system presented here is easy to implement, easy to operate and does not produce important head movements or artifacts in the acquired images. Given its low cost and ready availability, the method described here is ideal for use in basic and clinical fMRI research to track one or more moving points that can correspond to limbs, fingers or any other object whose position needs to be known.

Modroño C; Rodríguez-Hernández AF; Marcano F; Navarrete G; Burunat E; Ferrer M; Monserrat R; González-Mora JL

2011-11-01

29

Squid detected NMR and MRI at ultralow fields  

Energy Technology Data Exchange (ETDEWEB)

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); McDermott, Robert (Louisville, CO); Pines, Alexander (Berkeley, CA); Trabesinger, Andreas Heinz (CH-8006 Zurich, CH)

2007-05-15

30

Micro-MRI methods to detect renal cysts in mice.  

UK PubMed Central (United Kingdom)

BACKGROUND: Mouse models of disease, especially using transgenic and knockout technologies, are powerful tools to analyze the molecular basis of disease. We recently reported that a new dynamic micro-MRI method with dendrimer-based contrast agents can visualize renal structure and function in normal living mice and mice with acute renal failure. While MRI contrast enhancement is useful for detecting functional impairment of the kidneys, this technology has limitations in assessing morphologic changes, particularly cystic disease, because contrast-enhanced micro-MRI depicts cysts as low-intensity areas that cannot be distinguished from fibrotic foci. METHODS: In the current study, we evaluated if micro-MRI employing a new three-dimensional MR hydrography signal sequence [three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA)] can visualize chronic cystic changes without any contrast agents. RESULTS: We were able to positively depict multiple renal cortical cysts of approximately 0.2 mm diameter in a mouse model of sickle cell disease and observe serial changes of renal cysts (>0.2 mm diameter) in cyclooxygenase-2 (COX-2) knockout mice during a 21/2-month period. Some cysts decreased in size over time. CONCLUSIONS: Micro-MRI with 3D-FIESTA can depict cyst formation in the diseased kidneys of living mice without injection of contrast agents.

Kobayashi H; Kawamoto S; Brechbiel MW; Jo SK; Hu X; Yang T; Diwan BA; Waldmann TA; Schnermann J; Choyke PL; Star RA

2004-04-01

31

Detecting brown adipose tissue activity with BOLD MRI in mice.  

Science.gov (United States)

The recent discovery of active brown adipose tissue (BAT) in adult humans and the correlation found between the activity of this tissue and resting metabolic rate strongly suggest that this tissue may be implicated in the development of obesity in humans, as it is in rodents. Despite the possible physiological role of this tissue in the onset of human obesity, few noninvasive imaging techniques to detect BAT activity in humans exist. The scope of this work is to investigate the possibility of detecting BAT activity using blood-oxygen-level-dependent MRI. Our results show that the strong increase in oxygen consumption and consequent increase in blood deoxyhemoglobin levels following BAT activation lead to a well-localized signal drop in BAT. This strongly suggests the possibility to use blood-oxygen-level-dependent MRI for the noninvasive detection of BAT activity. PMID:22231619

Khanna, Arjun; Branca, Rosa T

2012-01-09

32

Detecting brown adipose tissue activity with BOLD MRI in mice.  

UK PubMed Central (United Kingdom)

The recent discovery of active brown adipose tissue (BAT) in adult humans and the correlation found between the activity of this tissue and resting metabolic rate strongly suggest that this tissue may be implicated in the development of obesity in humans, as it is in rodents. Despite the possible physiological role of this tissue in the onset of human obesity, few noninvasive imaging techniques to detect BAT activity in humans exist. The scope of this work is to investigate the possibility of detecting BAT activity using blood-oxygen-level-dependent MRI. Our results show that the strong increase in oxygen consumption and consequent increase in blood deoxyhemoglobin levels following BAT activation lead to a well-localized signal drop in BAT. This strongly suggests the possibility to use blood-oxygen-level-dependent MRI for the noninvasive detection of BAT activity.

Khanna A; Branca RT

2012-10-01

33

Methods and systems for remote detection of gases  

Energy Technology Data Exchange (ETDEWEB)

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. (Pasco, WA)

2007-11-27

34

Methods and systems for remote detection of gases  

Energy Technology Data Exchange (ETDEWEB)

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

35

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; B K Mohan; G Athithan

2011-01-01

36

Stress cine MRI for detection of coronary artery disease  

International Nuclear Information System (INIS)

[en] 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 [de] 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 (?1-Mimetika

2002-01-01

37

Millimetre-wave remote sensing for detection of effluent species  

International Nuclear Information System (INIS)

Millimetre waves are electromagnetic waves that lie between the microwave and far-infrared regions of the electromagnetic spectrum, occupying a frequency range from 30 to 300 GHz. This paper discusses the use of millimetre waves for remote detection of nuclear and chemical proliferation by measuring effluent species that may be released from proliferation sites.

1993-01-01

38

Modelling and interpretation of gas detection using remote laser pointers.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have developed a quantitative model of the performance of laser pointer style gas leak detectors, which are based on remote detection of backscattered radiation. The model incorporates instrumental noise limits, the reflectivity of the target background surface and a mathematical description of g...

Hodgkinson, Jane; van Well, Ben; Padgett, Miles; Pride, Russ D.

39

Motion Detection in Diffusion MRI via Online ODF Estimation.  

UK PubMed Central (United Kingdom)

The acquisition of high angular resolution diffusion MRI is particularly long and subject motion can become an issue. The orientation distribution function (ODF) can be reconstructed online incrementally from diffusion-weighted MRI with a Kalman filtering framework. This online reconstruction provides real-time feedback throughout the acquisition process. In this article, the Kalman filter is first adapted to the reconstruction of the ODF in constant solid angle. Then, a method called STAR (STatistical Analysis of Residuals) is presented and applied to the online detection of motion in high angular resolution diffusion images. Compared to existing techniques, this method is image based and is built on top of a Kalman filter. Therefore, it introduces no additional scan time and does not require additional hardware. The performance of STAR is tested on simulated and real data and compared to the classical generalized likelihood ratio test. Successful detection of small motion is reported (rotation under 2°) with no delay and robustness to noise.

Caruyer E; Aganj I; Lenglet C; Sapiro G; Deriche R

2013-01-01

40

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 ...

 
 
 
 
41

MRI  

Medline Plus

Full Text Available ... Resonance Imaging Scan (MRI) Introduction An MRI scan, or magnetic resonance imaging scan, is a test that ... help diagnose various diseases such as brain tumors or torn ligaments. If your doctor recommends an MRI, ...

42

Detecting, Locating, and Characterizing Remote Power Sources  

Energy Technology Data Exchange (ETDEWEB)

A feasibility study to determine range and back-azimuth detection methods for an isolated generator powering common loads was completed. The study deployed 3-component E and B field sensors with sampling rates of 100 kHz in a low noise test location in Southern California. Scripted power and load cycling was recorded at ranges of 40 meters to 4 km from the generator/load source. Three loads were tested: a 100 meter string of lights, an inverter powering an air blower, and a resistive heater. No E-field or B-field radiated signals were detected at ranges greater than 40 meters with a signal-to-noise ratio greater than one. Large variations in the broadband background electromagnetic noise were observed and may have been responsible for null detections at some measurement locations. At the 40-meter station, a frequency shift upon generator loading was observed for all load types. Harmonics from the detuned generator (operating at 56.7 Hz) could be observed for all load types but were most pronounced for the inverter source. A back-azimuth estimation methodology was applied to detected harmonics with stable and consistent results. For the inverter source, consistent back azimuths to the source were determined for the fundamental and higher detected harmonics up to the 31st. The method was applied to narrow band ''noise'' at 60 Hz and produced bimodal directions that roughly pointed to large population centers. Details of the method are withheld in this report pending a record of invention submittal. Although the generator/load combinations, which utilized wiring that tended to minimize stray signals, cannot yet be detected at large stand-off range without application of noise-filtering methods, the back-azimuth method appears promising and should be applied to other source types and frequency ranges where an E and B field can be detected. A record of invention describing this new back-azimuth method has been submitted to the Intellectual Property Law Group.

Harben, P; Carrigan, C; Kirkendall, B; Simons, D

2005-02-10

43

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

44

Automatic probe artifact detection in MRI-guided cryoablation  

Science.gov (United States)

Probe or needle artifact detection in 3D scans gives an approximate location for the tools inserted, and is thus crucial in assisting many image-guided procedures. Conventional needle localization algorithms often start with cropped images, where unwanted parts of raw scans are cropped either manually or by applying pre-defined masks. In cryoablation, however, the number of probes used, the placement and direction of probe insertion, and the portions of abdomen scanned differs significantly from case to case, and probes are often constantly being adjusted during the Probe Placement Phase. These features greatly reduce the practicality of approaches based on image cropping. In this work, we present a fully Automatic Probe Artifact Detection method, APAD, that works directly on uncropped raw MRI images, taken during the Probe Placement Phase in 3Tesla MRI-guided cryoablation. The key idea of our method is to first locate an initial 2D line strip within a slice of the MR image which approximates the position and direction of the 3D probes bundle, noting that cryoprobes or biopsy needles create a signal void (black) artifact in MRI with a bright cylindrical border. With the initial 2D line, standard approaches to detect line structures such as the 3D Hough Transform can be applied to quickly detect each probe's axis. By comparing with manually labeled probes, the analysis of 5 patient treatment cases of kidney cryoablation with varying probe placements demonstrates that our algorithm combined with standard 3D line detection is an accurate and robust method to detect probe artifacts.

Liu, Xinyang; Tuncali, Kemal; Wells, William M.; Zientara, Gary P.

2013-03-01

45

Remote detection of pressure compartments. Topical report  

Energy Technology Data Exchange (ETDEWEB)

A significant portion of the Cretaceous shale section in the Rocky Mountain Laramide Basins (RMLB) is anomalously pressured and gas saturated. The top of the anomalously pressured zone is identified by marked increases in sonic transit time, hydrocarbon production index (P.I.), clay diagenesis (smectite to illite), and vitrinite reflectance gradients. The driving mechanism of anomalous pressure development and compartmentalization is the generation and storage of liquid hydrocarbons that subsequently partially react to gas, converting the fluid-flow system to a multiphase regime in which capillarity controls permeability; the result is elevated displacement pressure within the shales. Sandstone reservoirs within this anomalously pressured shale section are subdivided stratigraphically and diagenetically into relatively small, isolated pressure or fluid-flow compartments. The saturation of these compartments with hydrocarbons and the subsequent oil-to-gas reaction causes explusion of a significant portion of the free water, resulting in anomalously pressured gas accumulations characterized by depletion drive. The determination of the position and configuration of the pressure boundary between normal and anomalously pressured regimes and the detection and delineation of porosity/permeability `sweet spots` below this boundary are the two most important elements in exploring for basin center gas in the RMLB.

Surdam, R.C.; Boyd, N.; Jiao, Z.; Maucione, D.; Kubicheck, S.

1996-02-01

46

Detection of abrupt motion in DCE-MRI  

Science.gov (United States)

Dynamic Contrast Enhanced MRI (DCE-MRI) is being increasingly used as a method for studying the tumor vasculature. It is also used as a biomarker to evaluate the response to anti-angiogenic therapies and the efficacy of a therapy. The uptake of contrast in the tissue is analyzed using pharmacokinetic models for understanding the perfusion characteristics and cell structure, which are indicative of tumor proliferation. However, in most of these 4D acquisitions the time required for the complete scan are quite long as sufficient time must be allowed for the passage of contrast medium from the vasculature to the tumor interstitium and subsequent extraction. Patient motion during such long scans is one of the major challenges that hamper automated and robust quantification. A system that could automatically detect if motion has occurred during the acquisition would be extremely beneficial. Patient motion observed during such 4D acquisitions are often rapid shifts, probably due to involuntary actions such as coughing, sneezing, peristalsis, or jerk due to discomfort. The detection of such abrupt motion would help to decide on a course of action for correction for motion such as eliminating time frames affected by motion from analysis, or employing a registration algorithm, or even considering the exam us unanalyzable. In this paper a new technique is proposed for effective detection of motion in 4D medical scans by determination of the variation in the signal characteristics from multiple regions of interest across time. This approach offers a robust, powerful, yet simple technique to detect motion.

Rajamani, Kumar; Shanbhag, Dattesh; Mullick, Rakesh; Ranjan, Sohan; Patil, Uday; Gupta, Sandeep N.

2012-02-01

47

Diffractive optic sensor for remote-point detection of ammonia.  

Science.gov (United States)

Remote-point photonic sensors are fabricated and evaluated. They are based on nanocomposite thin films comprising NiCl(2) nanocrystals embedded in sol-gel silica matrix and are patterned using direct UV laser microetching techniques to form surface relief structures, which exhibit environment sensitive optical diffraction effects. A strong response to ammonia is detected via the alteration of diffraction efficiency of its orders upon exposure to the analyte. Detection of ammonia in the 2 ppm level with a typical response time of about 30 s in the ambient, 50% RH 20 degrees C, room environment is demonstrated. PMID:20436608

Vasileiadis, M; Athanasekos, L; Meristoudi, A; Alexandropoulos, D; Mousdis, G; Karoutsos, V; Botsialas, A; Vainos, N A

2010-05-01

48

Diffractive optic sensor for remote-point detection of ammonia.  

UK PubMed Central (United Kingdom)

Remote-point photonic sensors are fabricated and evaluated. They are based on nanocomposite thin films comprising NiCl(2) nanocrystals embedded in sol-gel silica matrix and are patterned using direct UV laser microetching techniques to form surface relief structures, which exhibit environment sensitive optical diffraction effects. A strong response to ammonia is detected via the alteration of diffraction efficiency of its orders upon exposure to the analyte. Detection of ammonia in the 2 ppm level with a typical response time of about 30 s in the ambient, 50% RH 20 degrees C, room environment is demonstrated.

Vasileiadis M; Athanasekos L; Meristoudi A; Alexandropoulos D; Mousdis G; Karoutsos V; Botsialas A; Vainos NA

2010-05-01

49

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; John H. Healey

2007-01-01

50

Diffusion-weighted MRI provides additional value to conventional dynamic contrast-enhanced MRI for detection of hepatocellular carcinoma  

International Nuclear Information System (INIS)

The purpose of this study was to evaluate the accuracy of diffusion-weighted magnetic resonance imaging (DW-MRI) in differentiating HCC from benign cirrhotic lesions compared with conventional dynamic contrast-enhanced MRI. Fifty-five patients with cirrhosis underwent conventional and DW-MRI at 1.5 Tesla. Signal intensity ratios (SIratio) of solid liver lesions to adjacent hepatic parenchyma were measured for b0, b100, b600 and b1000, and the apparent diffusion coefficients (ADC) were calculated. In 27 patients, imaging results were compared to histopathology, and in 28 patients, to imaging follow-up. Based on predetermined thresholds, sensitivity and specificity of DW-MRI and conventional MRI were compared. SIratio was significantly different between malignant and benign lesions at all b-values (Pratio yielded a sensitivity of 95.2% compared to 80.6% for conventional MRI (P = 0.023) and a specificity of 82.7% compared to 65.4% (P=0.064). The improved accuracy was most beneficial for differentiating malignant lesions smaller than 2 cm. DW-MRI with b600-SIratio improved the detection of small HCC and the differentiation of pseudotumoral lesions compared with conventional MRI. (orig.)

2009-01-01

51

Motion Detection in Diffusion MRI via Online ODF Estimation.  

Science.gov (United States)

The acquisition of high angular resolution diffusion MRI is particularly long and subject motion can become an issue. The orientation distribution function (ODF) can be reconstructed online incrementally from diffusion-weighted MRI with a Kalman filtering framework. This online reconstruction provides real-time feedback throughout the acquisition process. In this article, the Kalman filter is first adapted to the reconstruction of the ODF in constant solid angle. Then, a method called STAR (STatistical Analysis of Residuals) is presented and applied to the online detection of motion in high angular resolution diffusion images. Compared to existing techniques, this method is image based and is built on top of a Kalman filter. Therefore, it introduces no additional scan time and does not require additional hardware. The performance of STAR is tested on simulated and real data and compared to the classical generalized likelihood ratio test. Successful detection of small motion is reported (rotation under 2°) with no delay and robustness to noise. PMID:23509445

Caruyer, Emmanuel; Aganj, Iman; Lenglet, Christophe; Sapiro, Guillermo; Deriche, Rachid

2013-02-21

52

Underwater remote detection and monitoring of spilled Orimulsion using sonar  

Energy Technology Data Exchange (ETDEWEB)

An accidental spill of Orimulsion on water presents special challenges because the Orimulsion will go into suspension as microscopic surfactant coated bitumen particles in the first 2-3 metres below the water surface. This makes it difficult to detect and monitor the plume. Fleming Co. Environmental examined the potential use of sonar for the underwater remote detection and monitoring of spilled Orimulsion in a small-scale saltwater tank test in Denmark. For the test, a sonar was placed 0.75 m below the water surface at one end of the tank. Acoustic measurements showed that a gradually spreading cloud containing only 5.6 liters of hydrocarbon particles could be detected from 17 meters away in a body of 180,000 liters, even when the sonar was functioning at only 6 per cent of its full power. These positive results may lead to further tank testing or offshore testing in Venezuela. 4 refs., 9 figs.

Hvidbak, F. [Fleming Co. Environmental APS, Aalborg (Denmark); Jacobsen, S.M. [Reson A/S, Slangerop (Denmark); Masciangioli, P. [Intevep, Caracas (Venezuela)

2000-07-01

53

Underwater remote detection and monitoring of spilled Orimulsion using sonar  

International Nuclear Information System (INIS)

An accidental spill of Orimulsion on water presents special challenges because the Orimulsion will go into suspension as microscopic surfactant coated bitumen particles in the first 2-3 metres below the water surface. This makes it difficult to detect and monitor the plume. Fleming Co. Environmental examined the potential use of sonar for the underwater remote detection and monitoring of spilled Orimulsion in a small-scale saltwater tank test in Denmark. For the test, a sonar was placed 0.75 m below the water surface at one end of the tank. Acoustic measurements showed that a gradually spreading cloud containing only 5.6 liters of hydrocarbon particles could be detected from 17 meters away in a body of 180,000 liters, even when the sonar was functioning at only 6 per cent of its full power. These positive results may lead to further tank testing or offshore testing in Venezuela. 4 refs., 9 figs.

2000-01-01

54

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

55

Detection of mechanical ventricular asynchrony by high temporal resolution cine MRI  

International Nuclear Information System (INIS)

The purpose was to assess the feasibility of high temporal resolution cine MRI (HTRC-MRI) to detect and to quantify mechanical ventricular asynchrony in patients with left bundle branch block (LBBB). Inter- and intraventricular delays were quantified by HTRC-MRI in 32 patients with (n=17) and without (n=15) LBBB. In patients with LBBB, delays by HTRC-MRI were correlated with echocardiographic parameters using pulsed wave Doppler echocardiography (PW-Echo) and tissue Doppler imaging (TDI-Echo). The interventricular delay by HTRC-MRI was 110±50 ms in patients with and -1±18 ms in patients without LBBB (P

2008-01-01

56

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

57

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; Ohtsuka Masahiko; Mibu Akemi; Karikomi Masato; Sakata Hitomi; Yamamoto Masahiro

2012-01-01

58

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 ...

59

A remote canister-positioning and glass level detection system  

International Nuclear Information System (INIS)

[en] This paper presents a remote, contactless microprocessor-based control system has been designed, developed, tested, and used that accurately positions glass-receiving canisters beneath a radioactive liquid-fed ceramic melter and monitors the height and extent of cross-sectional glass fill. Both tasks are accomplished using in-cell gamma-ray sources and out-of-cell detection, analysis and data interpretation equipment. The system aligns the canister axis with the melter overflow section to within ? 3 mm. The canister glass level at 11 fixed elevations is measured to within ± 5 mm, while as little as 5 mm of linear cross-sectional voiding (or equivalent glass thickness) can be detected in 30-cm-diam canisters

1990-01-01

60

Sensitivity of enhanced MRI for the detection of breast cancer: new, multicentric, residual, and recurrent  

International Nuclear Information System (INIS)

[en] Magnetic resonance imaging (MRI) of the breast brings the advantages of high resolution cross-sectional imaging to breast cancer diagnosis, treatment and research: improved cancer detection, staging, selection of therapy, evaluation of therapeutic response in vivo, detection of recurrence, and even the development of new therapies. Until now breast cancer treatment and research has been impeded by the limited means of evaluating the breast cancer in vivo: primarily clinical palpation and mammography of the breast tumor. A review of the initial studies shows that with the use of paramagnetic contrast agents, MRI has a sensitivity of 96 % for detecting breast cancers. MRI detects multicentric disease with a sensitivity of 98 %, superior to any other modality. The ability of MRI to detect recurrent local breast cancer in the conservatively treated breast is nearly 100 %. MRI is capable of monitoring tumor response to chemotherapy and actually guiding therapeutic interventions such as interstitial laser photocoagulation. (orig.)

1996-11-16

 
 
 
 
61

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

International Nuclear Information System (INIS)

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.

2005-01-01

62

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.

Rangwala Huzefa; Karypis George

2006-01-01

63

Can optical remote sensing techniques detect air contaminants?  

Energy Technology Data Exchange (ETDEWEB)

The American Petroleum Institute (API) is sponsoring a program to evaluate if and how optical remote sensing techniques can be used to detect air contaminant emissions at a processing facility. This study is also gathering database information to assess whether dispersion modeling accurately depicts air plume migrations within a petrochemical site. In early 1995, an initial field study was conducted at an open field site (Duke Forest, North Carolina). To duplicate actual air contaminant transport, tracer gas was released from simulated point, area and volume sources. Tracer gas bag samples and optical remote sensing (ORS) measurements located up to 200 m from the source captured samples and gathered data. Using results from the first test, API moved forward with a second field study, Project OPTEX (Operational Petrochemical Tracer Experiment). This field study investigated and tried to duplicate actual air contaminant migrations occurring within an operating facility. In Project OPTEX, researchers used open-path Fourier transform infrared (OP-FTIR) spectroscopy to infer air contaminant emissions in an actual industrial environment. Information gathered from this study would then be used to model and verify air plume migrations from plant sources and to beyond the fenceline.

Paine, R.J. [ENSR Corp., Acton, MA (United States); Zwicker, J.O. [Remote Sensing-Air, St. Louis, MO (United States); Feldman, H.J. [American Petroleum Inst., Washington, DC (United States)

1998-01-01

64

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

65

MRI  

Medline Plus

Full Text Available ... This is usually done with a blood test. Risks and Complications MRI scans are very safe. Because ... except when the benefits clearly outweigh the potential risk to the unborn child. Allergic reactions to the ...

66

MRI  

Medline Plus

Full Text Available ... imaging scan, is a test that provides very clear pictures of structures inside the body. Doctors may ... lie very still during the test to get clear pictures. MRI technologists are sitting in the next ...

67

MRI  

Medline Plus

Full Text Available ... cards, and other magnet-sensitive devices from the effects of the MRI machine. You will be placed ... technology is relatively recent, the very long-term effects are not known. There are no reasons to ...

68

MRI  

Medline Plus

Full Text Available ... provides very clear pictures of structures inside the body. Doctors may recommend an MRI to help diagnose ... generate excellent pictures of the inside of the body. The test takes a long time, sometimes as ...

69

Recent trends in Remote homology detection: an Indian Medley  

Directory of Open Access Journals (Sweden)

Full Text Available 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.

Venkataraman S. Gowri; Sankaran Sandhya

2006-01-01

70

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

2012-01-01

71

HASTE diffusion-weighted MRI for the reliable detection of cholesteatoma.  

UK PubMed Central (United Kingdom)

PURPOSE: To assess the detection efficiency of Half-Fourier acquisition single-shot turbo spin-echo (HASTE) diffusion-weighted magnetic resonance imaging (MRI) for cholesteatoma. MATERIALS AND METHODS: A total of 21 patients with suspected primary (n=16) or recurrent cholesteatoma (n=5) underwent MRI in a 1.5 Tesla scanner using an adapted protocol for cholesteatoma detection that included a coronal HASTE diffusion-weighted MRI sequence. The cholesteatoma diagnosis was based on evidence of a hyperintense lesion at b-1000 on diffusion-weighted images. The imaging findings were correlated with findings from surgery or clinical evaluations in all patients. RESULTS: HASTE diffusion-weighted MRI successfully detected 11 primary and 5 recurrent lesions out of 17 cholesteatomas (sensitivity, 94.1%). One primary cholesteatoma with a diameter of 4-5 mm was missed. MRI of patients without cholesteatoma were correctly interpreted as negative for cholesteatoma (specificity, 100%). The positive and negative predictive values for the HASTE diffusion-weighted MRI in detecting cholesteatoma were 100% and 80%, respectively. CONCLUSION: HASTE diffusion-weighted MRI offers great promise for cholesteatoma screening. The addition of this sequence to the posterior fossa MRI protocol may preclude unnecessary cholesteatoma surgery.

Il?ca AT; H?d?r Y; Bulakba?? N; Satar B; Güvenç I; Arslan HH; Imre N

2012-03-01

72

MR-guided localization of suspected breast lesions detected exclusively by postcontrast MRI.  

UK PubMed Central (United Kingdom)

OBJECTIVE: We describe and evaluate a preoperative MRI localization procedure for suspected breast lesions. MATERIALS AND METHODS: Fourteen consecutive patients underwent MR localization of suspected breast lesions discovered with contrast-enhanced MRI but not detected by conventional mammography or ultrasound. In each case diagnostic MRI was repeated after the application of special skin markers. A non-magnetic wire was subsequently inserted into the breast and a second MRI performed to document the position of the wire tip relative to the lesion. RESULTS: The procedure was successful in all 14 patients, enabling excision of the lesion and allowing histological diagnoses. CONCLUSION: We found the described procedure to be quite useful.

Fischer U; Vosshenrich R; Bruhn H; Keating D; Raab BW; Oestmann JW

1995-01-01

73

REMOTE DETECTION OF RADIOACTIVE PLUMES USING MILLIMETER WAVE TECHNOLOGY  

Energy Technology Data Exchange (ETDEWEB)

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

74

Microfluidic gas flow profiling using remote detection NMR  

Energy Technology Data Exchange (ETDEWEB)

Miniaturized fluid handling devices have recently attracted considerable interest in many areas of science1. Such microfluidic chips perform a variety of functions, ranging from analysis of biological macromolecules2,3 to catalysis of reactions and sensing in the gas phase4,5. To enable precise fluid handling, accurate knowledge of the flow properties within these devices is important. Due to low Reynolds numbers, laminar flow is usually assumed. However, either by design or unintentionally, the flow characteristic in small channels is often altered, for example by surface interactions, viscous and diffusional effects, or electrical potentials. Therefore, its prediction is not always straight-forward6-8. Currently, most microfluidic flow measurements rely on optical detection of markers9,10, requiring the injection of tracers and transparent devices. Here, we show profiles of microfluidic gas flow in capillaries and chip devices obtained by NMR in the remote detection modality11,12. Through the transient measurement of dispersion13, NMR is well adaptable for non-invasive, yet sensitive determination of the flow field and provides a novel and potentially more powerful tool to profile flow in capillaries and miniaturized flow devices.

Hilty, Christian; McDonnell, Erin; Granwehr, Josef; Pierce,Kimberly; Han, Song-I Han; Pines, Alexander

2005-05-06

75

Advances in Electrostatic Dust Detection on Remote Surfaces  

International Nuclear Information System (INIS)

[en] 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 (micro)m to 25 (micro)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 (micro)m grid showed a sensitivity more than an order of magnitude higher than the 125 (micro)m grid. The response to the finest particle categories (5-30 (micro)m) was two orders of magnitude higher than the largest (125-250 (micro)m) category. Longer duration current pulses were observed from the coarser particles. The results indicate a detection threshold for fine particles below 1 (micro)g/cm2

2005-01-01

76

Detection of Brain Tumor in MRI Images Using Mean Shift Algorithm and Normalized Cut Method  

Directory of Open Access Journals (Sweden)

Full Text Available This paper introduces an efficient method fordetection of brain tumor from Magnetic Resonance Images(MRI). In the process of detection of tumor from MRI,segmentation plays vital role for partitioning an image intodifferent subregion with homogeneous properties. Themethodology introduced here consist of combination of twoconventional algorithms i.e. Mean shift algorithm and Normalizedcut (Ncut) Method which provides automatic detection of exactsurface area of brain tumor in MRI. By incorporating theadvantages of the mean shift segmentation and Ncut method,Magnetic Resonance image (MRI) will be preprocessed first byusing the mean shift algorithm to form segmented regions, thenNcut method will be used for region nodes clustering after thisconnect component extraction analysis is used to locate the exacttumorous area in MRI Images.

Vishal B. Padole; D. S. Chaudhari

2012-01-01

77

Renin secreting tumor detected by MRI; Tumeur a renine decouverte par IRM  

Energy Technology Data Exchange (ETDEWEB)

We report an uncommon case of small renin secreting tumor of the kidney located in the medulla. The tumor was primarily detected by MRI and subsequently studied by spiral CT. The results and limitations of both techniques are discussed. (author)

Rossier, S.; Chague, D.; Gollentz, B.; Baralli, E.; KLingelschmitt, S.; Marchal, H.; Penin, H.; Winiszewski, P. [Centre Hospitalier de Belfort, 90 (France)

1998-08-01

78

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

International Nuclear Information System (INIS)

[en] Objective: To compare the diagnostic value of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the preoperative detection of colorectal liver metastases in diffuse fatty infiltration of the liver, associated with neoadjuvant chemotherapy. Materials and methods: Twenty preoperative tri-phasic MDCT (4-64-row, Siemens) and dynamic contrast-enhanced MRI (1.5 T or 3.0 T, Siemens) examinations of patients with colorectal cancer and liver metastases in diffuse steatosis were retrospectively evaluated. All patients underwent surgical resection for liver metastases (time interval 1-60 days). The amount of fatty infiltration of the liver was determined histopathologically by semi-quantitative percent-wise estimation and ranged from 25 to 75%. Results: Overall, 51 metastases were found by histopathology of the resected liver segments/lobes. The size of the metastases ranged from 0.4 to 13 cm, with 18 (35%) being up to 1 cm in diameter. In the overall rating, MDCT detected 33/51 lesions (65%), and MRI 45/51 (88%). For lesions up to 1 cm, MDCT detected only 2/18 (11%) and MRI 12/18 (66%). One false positive lesion was detected by MDCT. Statistical analysis showed that MRI is markedly superior to MDCT, with a statistically significant difference (p 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.

2011-01-01

79

Detection of mechanical ventricular asynchrony by high temporal resolution cine MRI  

Energy Technology Data Exchange (ETDEWEB)

The purpose was to assess the feasibility of high temporal resolution cine MRI (HTRC-MRI) to detect and to quantify mechanical ventricular asynchrony in patients with left bundle branch block (LBBB). Inter- and intraventricular delays were quantified by HTRC-MRI in 32 patients with (n=17) and without (n=15) LBBB. In patients with LBBB, delays by HTRC-MRI were correlated with echocardiographic parameters using pulsed wave Doppler echocardiography (PW-Echo) and tissue Doppler imaging (TDI-Echo). The interventricular delay by HTRC-MRI was 110{+-}50 ms in patients with and -1{+-}18 ms in patients without LBBB (P<0.0001). The intraventricular delay was 336{+-}86 ms in patients with compared to 40{+-}49 ms in patients without LBBB (P<0.0001). A strong correlation (r=0.78, P=0.0002) and good agreement (mean difference: 39{+-}36 ms) was found for the interventricular delay between HTRC-MRI and PW-Echo. A good correlation (r=0.66, P=0.0042), but a large discrepancy (mean difference: 257{+-}64 ms) was found for the intraventricular delay between HTRC-MRI and TDI-Echo. Detection and quantification of mechanical ventricular asynchrony using HTRC-MRI is feasible. However, further comparison with other imaging modalities is required. (orig.)

Muellerleile, Kai; Barmeyer, Achim; Dinkelacker, Alexander; Baholli, Loant; Koester, Ralf [University Medical Center Hamburg-Eppendorf, Center for Cardiology and Cardiovascular Surgery, Hamburg (Germany); Stork, Alexander; Bansmann, Martin; Adam, Gerhard [University Medical Center Hamburg-Eppendorf, Department of Diagnostic and Interventional Radiology, Hamburg (Germany); Graessner, Joachim [Siemens Medical Solutions Health Services GmbH, Hamburg (Germany); Lund, Gunnar [Cardiovascular Imaging, Roentgeninstitut Duesseldorf, Duesseldorf (Germany)

2008-07-15

80

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

 
 
 
 
81

Apparatus for detecting a magnetic anomaly contiguous to remote location by squid gradiometer and magnetometer systems  

Energy Technology Data Exchange (ETDEWEB)

A superconducting quantum interference device (SQUID) magnetic detection apparatus detects magnetic fields, signals, and anomalies at remote locations. Two remotely rotatable SQUID gradiometers may be housed in a cryogenic environment to search for and locate unambiguously magnetic anomalies. The SQUID magnetic detection apparatus can be used to determine the azimuth of a hydrofracture by first flooding the hydrofracture with a ferrofluid to create an artificial magnetic anomaly therein.

Overton, Jr., William C. (Los Alamos, NM); Steyert, Jr., William A. (Los Alamos, NM)

1984-01-01

82

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

Energy Technology Data Exchange (ETDEWEB)

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.)

Bink, Andrea; Berkefeld, Joachim; Wagner, Marlies; You, Se-Jong; Mesnil de Rochemont, Richard du [Johann Wolfgang Goethe University, Department of Neuroradiology, Frankfurt am Main (Germany); Ackermann, Hanns [Johann Wolfgang Goethe University, Institute of Biostatistics and Mathematical Modeling, Frankfurt/Main (Germany); Lorenz, Matthias W. [Johann Wolfgang Goethe University, Department of Neurology, Frankfurt/Main (Germany); Senft, Christian [Johann Wolfgang Goethe University, Department of Neurosurgery, Frankfurt/Main (Germany)

2012-02-15

83

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.)

2012-01-01

84

Development of Remote Control Laboratory for Radiation Detection via Internet  

International Nuclear Information System (INIS)

[en] The role of experiments in science education is essential for understanding the natural phenomena and principle related to a subject. Therefore, the remote control experiment via Internet is one of key solution for distance learners in science education. The remote experiments are also necessary for the time-consuming experiment which takes several days, collaborative experiment between distance learners, expensive laboratory equipment which is not usually available to students, experimental procedure which is dangerous, etc. In this study, we have developed a general method for a remote control laboratory system using internet and interface techniques. It is possible for students to learn the nuclear physics to control the real instruments and conduct physics experimentation with internet techniques. We proposed the remote control radiation measurement system as a sample application. This system could be useful for the monitoring near a nuclear power plants in order to improve the environment data credibility to the public

2002-01-01

85

Volume based DCE-MRI breast cancer detection with 3D visualization system  

International Nuclear Information System (INIS)

In this paper, a computer aided design auto probing system is presented to detect breast lesions based on Dynamic contrast enhanced Magnetic resonance imaging (DCE-MRI) images. The system is proposed in order to aid the radiologists and doctors in the interpretation of MRI breast images and enhance the detection accuracy. A series of approaches are presented to enhance the detection accuracy and refine the breast region of interest (Roil) automatically. Besides, a semi-quantitative analysis is used to segment the breast lesions from selected breast Roil and classify the detected tumour is whether benign, suspicious or malignant. The entire breast Roil including the detected tumour will display in 3D. The methodology has been applied on 104 sets of digital imaging and communications in medicine (Dico) breast MRI datasets images. The biopsy results are verified by 2 radiologists from Hospital Malaysia. The experimental results are demonstrated the proposed scheme can precisely identify breast cancer regions with 93% accuracy. (author)

2011-05-01

86

Diagnostic value of MRI for detection and differential diagnostic evaluation of focal liver lesions  

International Nuclear Information System (INIS)

Magnetic resonance imaging (MRI) of the liver has made considerable progress due to improvements in the examination technique. Sensitivity for the detection of focal liver lesions is higher for MRI than for CT. In the differential diagnosis of liver tumors MRI is remarkably accurate. This is particularly true for hemangiomas, liver cell carcinomas and focal nodular hyperplasias. From a clinical view point differentiation between hemangiomas and metastases is of utmost importance. Future improvements in MR diagnosis of liver diseases are expected due to fast imaging techniques and liver-specific contrast agents. (orig.)

1992-01-01

87

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

88

A Method of Target Detection in Remote Sensing Image Captured based for Sensor Network  

Directory of Open Access Journals (Sweden)

Full Text Available A refined energy constrained minimization method is developed for target detection in hyperspectral remote sensing images captured by unmanned aerial vehicles (UAVs) during their surveillance missions, which has been tested in the experiment under this paper. The experiment result proves, in the detection process, this method can effectively restrain noises so far as the spectral characteristics of any potential target are known, and find sub-pixel targets out effectively from the hyperspectral remote sensing image in unknown background spectrum

Yingchun Shen; Hai Jin

2012-01-01

89

Detection of Cardiac Infarction in MRI C-SENC Images  

Directory of Open Access Journals (Sweden)

Full Text Available Composite Strain Encoding (C-SENC) is an Magnetic Resonance Imaging (MRI) technique for acquiring simultaneous viability and functional and images of the heart. It combines two imaging techniques, Delayed Enhancement (DE) and Strain Encoding (SENC). In this work, a novel multi-stage method is proposed to identify ventricular infarction in the functional and viability images provided by C-SENC MRI. The proposed method is based on sequential application of Otsu’s thresholding, morphological opening, square boundary tracing and the subtractive clustering algorithm. This method is tested on images of ten patients with and without myocardial infarction (MI). The resulting clustered images are compared with those marked up by expert cardiologists who assisted in validating results coming from the proposed method. Infarcted tissues are correctly identified using the proposed method with high levels of sensitivity and specificity.

Ahmad O. Algohary; Ahmed M. El-Bialy; Ahmed H. Kandil; Nael F. Osman

2010-01-01

90

Detecting Fleeting MRI Signals with Frequency-Modulated Pulses.  

Science.gov (United States)

We describe a fundamentally different approach to MRI referred to as SWIFT (sweep imaging with Fourier transformation). SWIFT exploits time-shared RF excitation and signal acquisition, allowing capture of signal from spins with extremely short transverse relaxation time, T(2)*. The MR signal is acquired in gaps inserted into a broadband frequency-swept excitation pulse, which results in acquisition delays of only 1 - 2 microseconds. In SWIFT, 3D k-space is sampled in a radial manner, whereby one projection of the object is acquired in the gaps of each frequency-swept pulse, allowing a repetition time (TR) on the order of the pulse length (typically 1 - 3 milliseconds). Since the orientation of consecutive projections varies in a smooth manner (i.e., only small increments in the values of the x, y, z gradients occur from view to view), SWIFT scanning is close to inaudible and is insensitive to gradient timing errors and eddy currents. SWIFT images can be acquired in scan times similar to and sometimes faster than conventional 3D gradient echo techniques. With its ability to capture signals from ultrashort T(2)* spins, SWIFT promises to expand the role of MRI in areas of research where MRI previously played no or negligible role. In this article, we show wood and tooth images obtained with SWIFT as examples of materials with ultrashort T(2)*. Early experience suggests SWIFT can play a role in materials science and porous media research. PMID:22661791

Kobayashi, Naoharu; Idiyatullin, Djaudat; Corum, Curtis; Moeller, Steen; Chamberlain, Ryan; O'Connell, Robert; Nixdorf, Donald R; Garwood, Michael

2011-03-29

91

Mapping litter decomposition by remote-detected indicators  

Directory of Open Access Journals (Sweden)

Full Text Available Leaf litter decomposition is a key process for the functioning of natural ecosystems. An important limiting factor for this process is detritus availability, which we have estimated by remote sensed indices of canopy green biomass (NDVI). Here, we describe the use of multivariate geostatistical analysis to couple in situ measures with hyper-spectral and multi-spectral remote-sensed data for producing maps of litter decomposition. A direct relationship between the decomposition rates in four different CORINE habitats and NDVI, calculated at different scales from Landsat ETM+ multi-spectral data and MIVIS hyper-spectral data was found. Variogram analysis was used to evaluate the spatial properties of each single variable and their common interaction. Co-variogram and co-kriging analysis of the two variables turned out to be an effective approach for decomposition mapping from remote-sensed spatial explicit data.

L. Sabetta; N. Zaccarelli; G. Mancinelli; S. Mandrone; R. Salvatori; M. L. Costantini; G. Zurlini; L. Rossi

2006-01-01

92

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

93

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

2012-01-01

94

Usefulness of magnetic resonance imaging (MRI) in the detection of the lesions of gestational trophoblastic disease  

International Nuclear Information System (INIS)

Twenty patients with gestational trophoblastic disease (GTN) were examined by magnetic resonance imaging (MRI), computed tomography (CT) and digital subtraction angiography (DSA), to evaluate their usefulness in the diagnosis of the disease. The lesions of hydatidiform mole were mainly composed of molar vesicles, dilated vessels and hemorrhage which were depicted as small round high intensity lesions on the T2-weighted images and as tree-like low intensity lesions and high or low intensity lesions of various shapes in the T1-, T2-weighted images. These MRI findings closely corresponded to the histopathological findings. On the other hand, CT findings obtained with hydatidiform mole were characterized by filling defects or a small round low density area on contrast enhanced images. The detection ratio for intramural lesions of invasive mole and choriocarcinoma by MRI was 83% (5/6), while that by CT was 50% (3/6). The obliteration of the junctional zone and interruption of the myometrium observed in MRI were significant signs suggesting intramural invasion of the disease. In fact, these signs in MRI were observed in all of the six cases of invasive mole or choriocarcinoma examined. In conclusion, MRI is a powerful means for the determining the intramural invasive mole and choriocarcinoma. Thus more accurate diagnosis of GTN will be obtained with the combined use of MRI and DSA. (author).

1992-01-01

95

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

International Nuclear Information System (INIS)

[en] 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

2010-01-01

96

First report of an accessory popliteal muscle: detection with MRI  

Energy Technology Data Exchange (ETDEWEB)

During an MRI examination of the knee in a 48-year-old patient suffering from degenerative changes of a partly resected medial meniscus and concomitant osteoarthritis of the knee joint, an unusual variant of an accessory muscle in the popliteal fossa was found. To our best knowledge this muscle has never been described before. Because of the close relationship to the popliteal muscle with regard to course and localisation in the deep popliteal fossa ventral to the popliteal artery, the term ''accessory popliteal muscle'' is proposed. (orig.)

Duc, Sylvain R.; Wentz, Klaus U.; Zollikofer, Christoph L. [MR Research Group of the Institute of Diagnostic Radiology, Kantonsspital Winterthur, Brauerstrasse 15, 8401, Winterthur (Switzerland); Kaech, Kurt P. [Department of Trauma Surgery, Kantonsspital Winterthur, Winterthur (Switzerland)

2004-07-01

97

[A method of object detection for remote sensing-imagery based on spectral space transformation].  

UK PubMed Central (United Kingdom)

Object detection is an intermediate link for remote sensing image processing, which is an important guarantee of remote sensing application and services aspects. In view of the characteristics of remotely sensed imagery in frequency domain, a novel object detection algorithm based on spectral space transformation was proposed in the present paper. Firstly, the Fourier transformation method was applied to transform the image in spatial domain into frequency domain. Secondly, the wedge-shaped sample and overlay analysis methods for frequency energy were used to decompose signal into different frequency spectrum zones, and the center frequency values of object's features were acquired as detection marks in frequency domain. Finally, object information was detected with the matched Gabor filters which have direction and frequency selectivity. The results indicate that the proposed algorithm here performs better and it has good detection capability in specific direction as well.

Wu GP; Xiao PF; Feng XZ; Wang K

2013-03-01

98

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

2007-01-01

99

Comparison of detection pattern of HCC by ferumoxide-enhanced MRI and intratumoral blood flow pattern  

International Nuclear Information System (INIS)

We compared the detection rate and pattern of ferumoxide-enhanced magnetic resonance imaging (Fe-MRI) with the intratumoral blood flow pattern determined by CT angiography (CTA) and CT portography (CTAP) in 124 nodes (34 cases) diagnosed as hepatocellular carcinoma (HCC) or borderline HCC, based on the clinical course. Sequences to obtain a T1-weighted images (T1W), proton density-weighted images (PDW), T2-weighted images (T2W), T2*-weighted images (T2*W) were used in Fe-MRI. In nodes shown to be hypervascular on CTA, the detection rate by Fe-MRI was 69.7%. In nodes shown to be avascular by CTAP, the detection rate by Fe-MRI was 67.3%. These rates were higher than with other flow patterns. In nodes showing high signal intensity (HSI) on any sequences, arterial blood flow was increased and portal blood flow decreased in comparison with nodes without high signal intensity. All nodes showing HSI, both on Fe-MRI T2W and T2*W, were hypervascular on CTA, and portal blood flow was absent on CTAP. Nodes showing HSI on both T2*W and T2W were considered to have greater arterial blood flow and decreased portal blood flow compared with nodes appearing as HSI on T2*W, but only as iso- or low signal intensity on T2W (Mann-Whitney U-test; p

2000-01-01

100

CT and MRI improve detection of hepatocellular carcinoma, compared with ultrasound alone, in patients with cirrhosis.  

UK PubMed Central (United Kingdom)

BACKGROUND & AIMS: In patients with cirrhosis, hepatocellular carcinoma (HCC) is detected by ultrasound (US), computed tomography (CT), or magnetic resonance imaging (MRI); US is recommended for screening and surveillance. We performed a retrospective analysis of the abilities of these cross-sectional imaging modalities to detect HCC. METHODS: We analyzed data from 638 consecutive adult patients with cirrhosis who received liver transplants within 6 months of imaging at a tertiary care institution. Imaging reports and serum alpha-fetoprotein levels were compared with results from pathology analysis of explants as the reference standard. Sensitivities of US, CT, and MRI were calculated overall and in defined size categories. False-positive imaging results and patient-based specificities were evaluated. RESULTS: Of the 638 patients, 225 (35%) had HCC, confirmed by pathology analysis of liver explants. In 23 cases, the lesions were infiltrative or extensively multifocal. In the remaining 202 explants (337 numerable, discrete nodules), respective lesion-based sensitivities of US, CT, and MRI were 46%, 65%, and 72% overall and 21%, 40%, and 47% for small (<2 cm) HCC. The sensitivity of US increased with the availability of CT or MRI data (P = .049); sensitivity values were 62% and 85% for lesions 2-4 and ? 4 cm, respectively. Patient-based specificities of US, CT, and MRI were 96%, 96%, and 87%, respectively. CONCLUSIONS: US, CT, and MRI did not detect small HCC lesions with high levels of sensitivity, although CT and MRI provide substantial improvements over unenhanced US in patients with cirrhosis who received liver transplants.

Yu NC; Chaudhari V; Raman SS; Lassman C; Tong MJ; Busuttil RW; Lu DS

2011-02-01

 
 
 
 
101

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

102

SQUID-Detected Microtesla MRI in the presence of Metal  

Energy Technology Data Exchange (ETDEWEB)

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

103

Research on the Detection of Underground Hot Water Resources by Using Quantitative Remote Sensing  

Science.gov (United States)

: Based on the success of detecting the terrestrial heat resources qualitatively and positionally, this paper, by using the quantitative remote sensing theory, firstly analyzes systematically all kinds of impacting factors in the inversion of the terrestrial heat temperature through Thermal Infrared Remote Sensing; then gets a correlation function between the ground surface temperature and underground temperature combining geological and meteorological data and builds the digital 3D model of the terrestrial heat abnormal area by using the DEM of the study area; finally, establishes the algorithm of inverse model of the terrestrial heat resources and advances a new simple feasible and quantitative research method to detect the scope and depth of the underground hot water resources. The main research content includes: the algorithm and model of surface temperature inversion by using Thermal Infrared Remote Sensing, the processing method of remote sensing images and the interpreting method of geological structure, the correlation function between the ground surface temperature and underground temperature, and the method to acquire the parameters of the digital 3D model of the terrestrial heat abnormal area. Faced to the increasingly tense situation of the energy shortage internationally, this paper deeply studies the technology of quantitative remote sensing to rapidly detect underground hot water resources, a new green energy resource. Through the establishment of new method to detect the scope and depth of underground hot water resources quantificationally by using remote sensing technology, it not only has important theory value to the development of the quantitative remote sensing, but also has vital practical value to improve the conventional geophysical technology to find underground hot water and boost the geothermal resource development and protection. Key words: underground hot water; Thermal Infrared Remote Sensing; quantitative research

Qiao, Yuliang; Shangmin, Shangmin; Mingquan, Mingquan

104

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,; Ms. Tanuja K. Sarode; Ms. Saylee M. Gharge.

2009-01-01

105

Detection of recurrent rectal cancer with CT, MRI and PET/CT  

Energy Technology Data Exchange (ETDEWEB)

Computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) all have the potential to directly visualize local and distant relapse of colorectal cancer (CRC). Nevertheless, the role of diagnostic imaging for routine follow-up of CRC patients remains controversial. Although MRI and PET have advantages over CT in the detection of local recurrence, until now only a few surveillance programs recommend the use of annual CT for routine follow-up. The objective of this review is to elucidate the current status of diagnostic imaging for the detection of recurrent rectal cancer based on the recent literature and our own experience. Furthermore, an insight into contemporary surveillance programs and an outlook concerning a novel technical approach to moving-table MRI at 1.5 Tesla for staging purposes are given. (orig.)

Schaefer, O.; Langer, M. [University Hospital Feiburg, Department of Diagnostic Radiology, Freiburg (Germany)

2007-08-15

106

Detection of recurrent rectal cancer with CT, MRI and PET/CT.  

UK PubMed Central (United Kingdom)

Computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) all have the potential to directly visualize local and distant relapse of colorectal cancer (CRC). Nevertheless, the role of diagnostic imaging for routine follow-up of CRC patients remains controversial. Although MRI and PET have advantages over CT in the detection of local recurrence, until now only a few surveillance programs recommend the use of annual CT for routine follow-up. The objective of this review is to elucidate the current status of diagnostic imaging for the detection of recurrent rectal cancer based on the recent literature and our own experience. Furthermore, an insight into contemporary surveillance programs and an outlook concerning a novel technical approach to moving-table MRI at 1.5 Tesla for staging purposes are given.

Schaefer O; Langer M

2007-08-01

107

Detection and Demarcation of Tumor using Vector Quantization in MRI images  

CERN Multimedia

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

108

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)

1989-01-01

109

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

Energy Technology Data Exchange (ETDEWEB)

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

110

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

Energy Technology Data Exchange (ETDEWEB)

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.)

Chassang, M.; Novellas, S.; Bloch-Marcotte, C.; Chevallier, P. [Hopital Archet 2, Service d' Imagerie Diagnostique et Interventionnelle, Centre Hospitalier Regional et Universitaire de Nice, 151 route de Saint Antoine de Ginestiere, B.P. 3079, Nice Cedex 3 (France); Delotte, J.; Bongain, A. [Hopital Archet 2, Service de Gynecologie-Obstetrique, Centre Hospitalier Regional et Universitaire de Nice, 151 route de Saint Antoine de Ginestiere, B.P. 3079, Nice Cedex 3 (France); Toullalan, O. [Hopital de Cannes, Service de Gynecologie, 15 avenue des Broussailles, B.P. 264, Cannes Cedex (France)

2010-04-15

111

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

112

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

113

Detecting and assessing macrophages in vivo to evaluate atherosclerosis noninvasively using molecular MRI  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigated the ability of targeted immunomicelles to detect and assess macrophages in atherosclerotic plaque using MRI in vivo. There is a large clinical need for a noninvasive tool to assess atherosclerosis from a molecular and cellular standpoint. Macrophages play a central role in atheroscle...

Amirbekian, Vardan; Lipinski, Michael J.; Briley-Saebo, Karen C.; Amirbekian, Smbat; Aguinaldo, Juan Gilberto S.

114

The contribution of MRI to the detection of endovascular aneurysm repair  

International Nuclear Information System (INIS)

Purpose: Evaluation of MR-imaging in the follow-up of patients after endovascular repair of abdominal aortic aneurysms concerning detection of endoleaks. Materials and Methods: In the postoperative follow-up after endovascular repair of aortic aneurysms, 10 consecutive patients (mean age: 68 years) were suspected to have an endoleak by helical CT and were scheduled for conventional angiography, preceded by supplemental MR-imaging to confirm or refute the diagnosis. The images of helical CT and MRI were evaluated by two independent readers concerning leak, feeding vessel and artifacts. Results: The follow-up MRI was able to detect all endoleaks (type 1 endoleak, n=7; type 2 endoleak, n=3) compared to all but one detected by helical CT. Of the 10 patients with an endoleak, MR-angiography visualized the feeding vessel in 7 patients and CT in one patient. MRI did show fewer metal artifacts from the stent wire than CT. For the visualization of feeding vessels and endoleaks, MRA achieved statistically significant superiority. In a single case, helical-CT was not reliable because of strange metal artefacts after previous coil embolization. Conclusion: MRI is comparable to helical-CT in detecting endoleaks and superior to CT in demonstrating the anatomy of the feeding vessel after endovascular repair of aortic aneurysms. The major advantages are fewer artifacts after coil embolization and absent radiation exposure. (orig.)

2002-01-01

115

Comparison of MRI (including SS SE-EPI and SPIO-enhanced MRI) and FDG-PET/CT for the detection of colorectal liver metastases  

International Nuclear Information System (INIS)

Fluoro-18-deoxyglucose positron emission tomography computed tomography (FDG-PET/CT) and magnetic resonance imaging (MRI), including unenhanced single-shot spin-echo echo planar imaging (SS SE-EPI) and small paramagnetic iron oxide (SPIO) enhancement, were compared prospectively for detecting colorectal liver metastases. Twenty-four consecutive patients suspected for metastases underwent MRI and FDG-PET/CT. Fourteen patients (58%) had previously received chemotherapy, including seven patients whose chemotherapy was still continuing to within 1 month of the PET/CT study. The mean interval between PET/CT and MRI was 10.2±5.2 days. Histopathology (n=18) or follow-up imaging (n=6) were used as reference. Seventy-seven metastases were detected. In nine patients, MRI and PET/CT gave concordant results. Sensitivities for unenhanced SS SE-EPI, MRI without SS SE-EPI and FDG-PET/CT were, respectively, 100% (p=9 x 10-10 vs PET, p=8 x 10-3 vs MRI without SS SE-EPI), 90% (p=2 x 10-7 vs PET) and 60%. PET/CT sensitivity dropped significantly with decreasing size, from 100% in lesions larger than 20 mm (identical to MRI), over 54% in lesions between 10 and 20 mm (p=3 x 105 versus unenhanced SS SE-EPI), to 32% in lesions under 10 mm (p=6 x 10-5 versus unenhanced SS SE-EPI). Positive predictive value of PET was 100% (identical to MRI). MRI, particularly unenhanced SS SE-EPI, has good sensitivity and positive predictive value for detecting liver metastases from colorectal carcinoma. Its sensitivity is better than that of FDG-PET/CT, especially for small lesions. (orig.)

2009-01-01

116

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.)

2008-01-01

117

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

118

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

Energy Technology Data Exchange (ETDEWEB)

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.

Demirgian, J.C.; Macha, S.M.; Darby, S.M. [Argonne National Lab., IL (United States); Ditillo, J. [Army Edgewood Research, Development, and Engineering Center, Aberdeen Proving Ground, MD (United States)

1995-04-01

119

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

2012-01-01

120

Analysis of remote detection travel time curves measured from microfluidic channels.  

Science.gov (United States)

Remote detection technique can increase sensitivity of an NMR experiment by several orders of magnitude in microfluidic applications. Travel time experiment is a basic remote detection NMR experiment, which reveals the travel time distribution of the molecules flowing from the encoding coil region to the detector. In this article, we focus on analyzing how flow type (Poiseuille or plug flow), diffusion, dispersion and geometry of the flow channels are manifested in the travel time curves measured from microfluidic channels. We demonstrate that remote detection travel time experiment could be used even as an alternative NMR method for measuring self-diffusion coefficient of a fluid without magnetic field gradients. In addition, we introduce a modified travel time pulse sequence, which removes the signal of unencoded fluid spins as well as the background signal arising from the material inside or close to the detector. PMID:21459639

Telkki, Ville-Veikko; Zhivonitko, Vladimir V

2011-03-17

 
 
 
 
121

Detectability and clinical usefulness of the intraparotid facial nerve on MRI  

Energy Technology Data Exchange (ETDEWEB)

The detectability and its clinical usefulness of the intraparotid facial nerve on MRI with SPGR method were investigated. In 18 of 20 normal sides (90%) and in all sides of parotid tumors, intraparotid facial nerve was identified. This result was superior to past reports. In 5 operated cases, the location diagnosis of the parotid tumor was correct in all of 5 cases on MRI, and 3 of 4 cases on CT. In future, we need consider the problems of artifacts and fitting coil for better images. (author).

Sugai, Yukio; Nagahata, Fumiko; Hasegawa, Tomohiko; Sakata, Ken [Yamagata Prefectural Shinjo Hospital (Japan); Tada, Yuichiro

1995-06-01

122

[Fusion imaging in urology: combination of MRI and TRUS for detection of prostate cancer].  

Science.gov (United States)

Multiparametric magnetic resonance imaging (MRI) represents the most accurate imaging modality for prostate cancer imaging to date. Transrectal ultrasound (TRUS) is easily applied and therefore remains the gold standard for systematic prostate biopsies. However, the advantages of both modalities can be combined by image fusion. Currently, several image fusion devices are being implemented into clinical routine. First data show an increased detection rate of prostate cancer compared to systematic TRUS biopsies. At present prostatic deformation and intracorporeal movement represent technical challenges yet to be overcome. The present article gives an overview about the status of MRI-based biopsy techniques and highlights the current studies on the topic. PMID:23483269

Schilling, D; Kurosch, M; Mager, R; Tsaur, I; Haferkamp, A; Röthke, M

2013-04-01

123

[Fusion imaging in urology: combination of MRI and TRUS for detection of prostate cancer].  

UK PubMed Central (United Kingdom)

Multiparametric magnetic resonance imaging (MRI) represents the most accurate imaging modality for prostate cancer imaging to date. Transrectal ultrasound (TRUS) is easily applied and therefore remains the gold standard for systematic prostate biopsies. However, the advantages of both modalities can be combined by image fusion. Currently, several image fusion devices are being implemented into clinical routine. First data show an increased detection rate of prostate cancer compared to systematic TRUS biopsies. At present prostatic deformation and intracorporeal movement represent technical challenges yet to be overcome. The present article gives an overview about the status of MRI-based biopsy techniques and highlights the current studies on the topic.

Schilling D; Kurosch M; Mager R; Tsaur I; Haferkamp A; Röthke M

2013-04-01

124

MRI: A method to detect minor brain damage following coronary bypass surgery  

Energy Technology Data Exchange (ETDEWEB)

In order to assess the occurrence of minor focal brain lesions after coronary bypass surgery, magnetic resonance imaging (MRI) was used. Nine male patients (age 42-63) with angina pectoris were investigated at 0.5 Tesla. The investigation was performed one to seven weeks prior to the operation and one month after the operation. Before surgery, the images demonstrated more than five high intensity spots in the white matter of the brain in all but two patients. No additional spots were found after operation. This pilot study indicates that it might be difficult to use MRI to detect minor parenchymal lesions after cardiopulmonary bypass surgery. (orig.).

Vik, A.; Brubakk, A.O. (Trondheim Univ. (Norway). Dept. of Biomedical Engineering); Rinck, P.A. (Trondheim Univ. (Norway). MR Center); Sande, E.; Levang, O.W. (Trondheim Univ. Hospital (Norway). Dept. of Surgery); Sellevold, O. (Trondheim Univ. Hospital (Norway). Dept. of Anaesthesiology)

1991-10-01

125

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)

2008-01-01

126

Detection of cranial meningiomas: comparison of {sup 68}Ga-DOTATOC PET/CT and contrast-enhanced MRI  

Energy Technology Data Exchange (ETDEWEB)

PET imaging with somatostatin receptor ligands, such as {sup 68}Ga-DOTATOC, is a well-established method for detection and target volume definition of meningiomas prior to radiotherapy. Since DOTATOC PET delivers a higher contrast between meningiomas and surrounding tissues than MRI, we conducted a retrospective analysis to compare the diagnostic accuracy of contrast-enhanced MRI (CE-MRI) with {sup 68}Ga-DOTATOC PET/CT in patients with cranial meningiomas prior to radiotherapy. Over a period of 6 years, 134 patients (20-82 years of age, 107 women and 27 men) underwent cranial CE-MRI and {sup 68}Ga-DOTATOC PET/CT. To compare the two methods, the lesions considered typical of meningiomas visually were counted and analysed with respect to their location and SUVmax. In the 134 patients investigated by both modalities, 190 meningiomas were detected by {sup 68}Ga-DOTATOC PET/CT and 171 by CE-MRI. With knowledge of the PET/CT data, the MRI scans were reinvestigated, which led to the detection of 4 of the 19 incidental meningiomas, resulting in an overall detection rate of 92 % of the meningioma lesions that were found by PET/CT. Ga-DOTATOC PET/CT demonstrated an improved sensitivity in meningioma detection when compared to CE-MRI. Tumours adjacent to the falx cerebri, located at the skull base or obscured by imaging artefacts or calcification are particularly difficult to detect by MRI. Therefore {sup 68}Ga-DOTATOC PET/CT may provide additional information in patients with uncertain or equivocal results on MRI or could help to confirm a diagnosis of meningioma based on MRI or could help to confirm MRI-based diagnosis of meningiomas in cases of biopsy limitations. It is possible that not only radiotherapy and surgical planning, but also follow-up strategies would benefit from this imaging modality. (orig.)

Afshar-Oromieh, Ali; Giesel, Frederik L.; Haberkorn, Uwe; Haufe, Sabine; Kratochwil, Clemens [University Hospital of Heidelberg, Department of Nuclear Medicine, Heidelberg (Germany); Linhart, Heinz G. [DKFZ, National Center for Tumor Diseases (NCT), Heidelberg (Germany); Combs, Stephanie E. [University Hospital of Heidelberg, Department of Radiation Oncology and Therapy, Heidelberg (Germany); Podlesek, Dino [University Hospital of Dresden, Department of Neurosurgery, Dresden (Germany); Eisenhut, Michael [DKFZ, Department of Radiopharmacy, Heidelberg (Germany)

2012-09-15

127

Engineering novel detectors and sensors for MRI.  

UK PubMed Central (United Kingdom)

Increasing detection sensitivity and image contrast have always been major topics of research in MRI. In this perspective, we summarize two engineering approaches to make detectors and sensors that have potential to extend the capability of MRI. The first approach is to integrate miniaturized detectors with a wireless powered parametric amplifier to enhance the detection sensitivity of remotely coupled detectors. The second approach is to microfabricate contrast agents with encoded multispectral frequency shifts, whose properties can be specified and fine-tuned by geometry. These two complementary approaches will benefit from the rapid development in nanotechnology and microfabrication which should enable new opportunities for MRI.

Qian C; Zabow G; Koretsky A

2013-04-01

128

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.)

2010-01-01

129

[Extensive left ventricular myocardial fat deposition detected by cardiac MRI.  

UK PubMed Central (United Kingdom)

Although it is well known from pathological studies that intramyocardial fat deposition frequently occurs after left ventricular myocardial infarction, a left ventricular fat deposition is rarely diagnosed in the clinical routine. We report the case of extensive fat deposition in the left ventricular myocardium which was detected by routine cardiac magnetic resonance imaging.

Nassenstein K; Nensa F; Bruder O

2013-08-01

130

[Change detection from high-resolution remote sensing image based on MSE model].  

UK PubMed Central (United Kingdom)

At present, most of the traditional change detection methods from high-resolution remote sensing image are based on a feature information, the information of multi-feature information cannot be extracted, so it is difficult to detect the complete information. In order to solve this problem, a change detection algorithm of high-resolution remote sensing image based on multiview spectral embedding is proposed in the present paper. Firstly, change image is obtained using traditional difference change detection method, and multi-feature information is extracted. The feature vector information is fused by a MSE model and the complete change information can be obtained. The experimental results show that the detection accuracy of the proposed method is better than the accuracy of traditional methods, and its stability is outstanding.

Wei LF; Wang HB

2013-03-01

131

The efficacy of plain films vs MRI in the detection of scaphoid fractures  

Energy Technology Data Exchange (ETDEWEB)

An investigation was carried out to determine whether or not professionals perceived plain film radiography to be the 'gold-standard' in the detection of scaphoid fractures. Literature highlighted that plain film radiography was an unreliable method for detecting such fractures and that magnetic resonance imaging (MRI) should now be regarded as the new 'gold-standard'. Using a quantitative method, a total of 100 postal questionnaires were sent out to radiologists in 20 different imaging departments throughout the United Kingdom (UK) asking them their opinion on this controversial subject. In addition, the investigation looked into the use of MRI within each department in trying to determine whether or not it was surpassing plain film radiography as an established practice for detecting scaphoid fractures. Of the 100 questionnaires that were sent out, a total of 45 were returned from a total of 13 different departments. The results of this investigation conclude that plain film radiography is still used as a primary imaging modality to detect scaphoid fractures in all departments. There was much support for the use of plain film radiography with the modality being praised time and time again for its ease, 24-h availability, low cost and reproducibility. MRI was acknowledged as being superior in its capability to detect scaphoid fractures in comparison to plain films; its current use, however, is limited owing to high costs, lack of availability and long waiting lists. It would appear from this study that MRI is regarded as a useful modality in cases whereby plain film radiography fails to detect the presence or absence of a fracture in clinically positive patients, with great future potential.

Trigg, Mark [Bronglais Hospital, Aberystwyth (United Kingdom); Reeves, Pauline Jane [X-Ray Department, Arrowe Park Hospital, Upton, Wirral CH49 5PE (United Kingdom)]. E-mail: pauline.reeves@whnt.nhs.uk

2007-02-15

132

The efficacy of plain films vs MRI in the detection of scaphoid fractures  

International Nuclear Information System (INIS)

An investigation was carried out to determine whether or not professionals perceived plain film radiography to be the 'gold-standard' in the detection of scaphoid fractures. Literature highlighted that plain film radiography was an unreliable method for detecting such fractures and that magnetic resonance imaging (MRI) should now be regarded as the new 'gold-standard'. Using a quantitative method, a total of 100 postal questionnaires were sent out to radiologists in 20 different imaging departments throughout the United Kingdom (UK) asking them their opinion on this controversial subject. In addition, the investigation looked into the use of MRI within each department in trying to determine whether or not it was surpassing plain film radiography as an established practice for detecting scaphoid fractures. Of the 100 questionnaires that were sent out, a total of 45 were returned from a total of 13 different departments. The results of this investigation conclude that plain film radiography is still used as a primary imaging modality to detect scaphoid fractures in all departments. There was much support for the use of plain film radiography with the modality being praised time and time again for its ease, 24-h availability, low cost and reproducibility. MRI was acknowledged as being superior in its capability to detect scaphoid fractures in comparison to plain films; its current use, however, is limited owing to high costs, lack of availability and long waiting lists. It would appear from this study that MRI is regarded as a useful modality in cases whereby plain film radiography fails to detect the presence or absence of a fracture in clinically positive patients, with great future potential.

2007-01-01

133

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

134

Detection of abnormalities in MRI images of brain  

International Nuclear Information System (INIS)

[en] Cancer is currently one of the leading causes of death. This paper presents an approach for not only the detection but also early stage of tumours can be detectable. Medical imaging technique is most commonly used to visualize the internal structure and function of the body. Magnetic Resonance Imaging provides much greater contrast between the different soft tissues of the body than computed tomography (CT) does, making it especially useful in neurological (brain), musculoskeletal, cardiovascular, and oncological (cancer) imaging. In recent years the image processing mechanisms are used widely in several medical areas for improving earlier detection and treatment stages, in which the time factor is very important to discover the disease in the patient as possible as fast, especially in various cancer tumours such as the brain cancer, lung cancer, breast cancer. We passed the available brain cancer images and its database in basic three stages to achieve more quality and accuracy in our experimental results: firstly image enhancement stage which we used low pre-processing image techniques: Gabor filter using a Gaussian rule in which produced the best resultant enhanced images. In the image segmentation stage we used thresholding segmentation mechanism by Otsu thresholding algorithm. Finally we relied on general features which help us to make a comparison between normal and abnormal images. (author)

2011-01-01

135

Generation and remote detection of THz sound using semiconductor superlattices  

CERN Multimedia

The authors introduce a novel approach to study the propagation of high frequency acoustic phonons in which the generation and detection involves two spatially separated superlattices $\\sim 1 {\\rm \\mu m}$ apart. Propagating modes of frequencies up to $\\sim 1 {\\rm THz}$ escape from the superlattice where they are generated and reach the second superlattice where they are detected. The measured frequency spectrum reveals finite size effects, which can be accounted for by a continuum elastic model.

Trigo, M; Wahlstrand, J K; Merlin, R; Reason, M; Goldman, R S

2007-01-01

136

Feature analysis for detecting people from remotely sensed images  

Science.gov (United States)

We propose a novel approach using airborne image sequences for detecting dense crowds and individuals. Although airborne images of this resolution range are not enough to see each person in detail, we can still notice a change of color and intensity components of the acquired image in the location where a person exists. Therefore, we propose a local feature detection-based probabilistic framework to detect people automatically. Extracted local features behave as observations of the probability density function (PDF) of the people locations to be estimated. Using an adaptive kernel density estimation method, we estimate the corresponding PDF. First, we use estimated PDF to detect boundaries of dense crowds. After that, using background information of dense crowds and previously extracted local features, we detect other people in noncrowd regions automatically for each image in the sequence. To test our crowd and people detection algorithm, we use airborne images taken over Munich during the Oktoberfest event, two different open-air concerts, and an outdoor festival. In addition, we apply tests on GeoEye-1 satellite images. Our experimental results indicate possible use of the algorithm in real-life mass events.

Sirmacek, Beril; Reinartz, Peter

2013-01-01

137

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

138

Automatic Cloud Detection and Removal Algorithm for MODIS Remote Sensing Imagery  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Lingjia Gu; Ruizhi Ren; Shuang Zhang

139

Strategies for remote detection of life--DARWIN-IRSI and TPF missions.  

UK PubMed Central (United Kingdom)

Having selected a general definition of a living system, we wonder whether a remote detection of such systems can be made, at least in some cases. Quite fortunately, we find that this seems possible. We describe the present status of missions with this goal.

Leger A

2000-06-01

140

Armor-piercing bullet: 3-T MRI findings and identification by a ferromagnetic detection system.  

UK PubMed Central (United Kingdom)

The objective of this project was to evaluate magnetic resonance imaging (MRI) issues at 3 T for an armor-piercing bullet and to determine if this item could be identified using a ferromagnetic detection system. An armor-piercing bullet (.30 caliber, 7.62 × 39, copper-jacketed round, steel core; Norinco) underwent evaluation for magnetic field interactions, heating, and artifacts using standardized techniques. Heating was assessed with the bullet in a gelled-saline-filled phantom with MRI performed using a transmit/receive radio frequency body coil at a whole-body-averaged specific absorption rate of 2.9 W/kg for 15 minutes. Artifacts were characterized using T1-weighted spin echo and gradient echo pulse sequences. In addition, a special ferromagnetic detection system (Ferroguard Screener; Metrasens, Lisle, Illinois) was used in an attempt to identify this armor-piercing bullet. The findings indicated that the armor-piercing bullet showed substantial magnetic field interactions. Heating was not excessive. Artifacts were large and may create diagnostic problems if the area of interest is close to this bullet. The ferromagnetic detection system yielded a positive result. We concluded that this armor-piercing bullet is MR unsafe. Importantly, this ballistic item was identified using the particular ferromagnetic detection system utilized in this investigation, which has important implications for MRI screening and patient safety.

Karacozoff AM; Pekmezci M; Shellock FG

2013-03-01

 
 
 
 
141

Diffusion-weighted MRI for detecting and monitoring cancer: a review of current applications in body imaging.  

UK PubMed Central (United Kingdom)

Diffusion-weighted magnetic resonance imaging (MRI), which involves the acquisition of a magnetic resonance signal related to the Brownian motion of water protons in tissue, has become a useful technique for assessing tumors. In this article, we review the basic concepts, imaging strategies, and body applications of diffusion-weighted MRI in detecting and monitoring cancer.

Türkbey B; Aras Ö; Karabulut N; Turgut AT; Akpinar E; Alibek S; Pang Y; Ertürk ?M; El Khouli RH; Bluemke DA; Choyke PL

2012-01-01

142

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.)

2005-01-01

143

Comparison of triple dose versus standard dose gadolinium-DTPA for detection of MRI enhancing lesions in patients with MS.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We studied whether a triple dose of gadolinium-DTPA alone or in combination with delayed scanning increases the sensitivity of brain MRI for detecting enhancing lesions in patients with MS. We obtained T1-weighted brain MRI scans in two sessions for 22 patients with clinically definite MS. In the fi...

Filippi, M; Yousry, T; Campi, A; Kandziora, C; Colombo, B; Voltz, R; Martinelli, V; Spuler, S; Bressi, S; Scotti, G; Comi, G

144

Detecting Weed Infestations in Soybean Using Remote Sensing.  

Science.gov (United States)

Can weed distribution maps be developed from remote sensed reflectance data? When are the appropriate times to collect these data during the season? What wavebands can be used to distinguish weedy from weed- free areas? This research examined if and when reflectance could be used to distinguish between weed-free and weed-infested (mixed species) areas in soybean and to determine the most useful wavebands to separate crop, weed, and soil reflectance differences. Treatments in the two-year study included no vegetation (bare soil), weed-free soybean, and weed-infested soybean and, in one year, 80% corn residue cover. Reflectance was measured at several sampling times from May through September in 2001 and 2002 using a hand-held multispectral radiometer equipped with band-limited optical interference filters (460 - 1650 nm). Pixel resolution was 0.8-m. Reflectance in the visible spectral range (460 to 700 nm) generally was similar among treatments. In the near-infrared (NIR) range (>700 to 1650 nm), differences among treatments were observed from soybean growth stage V-3 (about 4 weeks after planting) until mid-July to early August depending on crop vigor and canopy closure (76 cm row spacing in 2001 and 19 cm row spacing in 2002). Reflectance rankings in the NIR range when treatments could be differentiated were consistent between years and, from lowest to highest reflectance, were soil < weed-free < weed-infested areas. Increased reflectance from weed-infested areas was most likely due to increased biomass and canopy cover. Residue masked differences between weed-free and weed- infested areas during the early stages of growth due to high reflectance from the residue and reduced weed numbers in these areas. These results suggest that NIR spectral reflectance collected prior to canopy closure can be used to distinguish weed-infested from weed-free areas.

Clay, S. A.; Chang, J.; Clay, D. E.; Dalsted, K.; Reese, C.

2007-12-01

145

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

UK PubMed Central (United Kingdom)

BACKGROUND: Accurate assessment of splenic disease is important for staging Hodgkin lymphoma. OBJECTIVE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: T2-weighted imaging when complemented by DCE-MRI imaging may improve evaluation of Hodgkin disease splenic involvement.

Punwani S; Cheung KK; Skipper N; Bell N; Bainbridge A; Taylor SA; Groves AM; Hain SF; Ben-Haim S; Shankar A; Daw S; Halligan S; Humphries PD

2013-08-01

146

Late widespread skeletal metastases from myxoid liposarcoma detected by MRI only  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Myxoid liposarcoma is the second most commonly occurring sub-type of liposarcomas. In contrast to other soft tissue sarcomas, it is known to have a tendency to spread toward extrapulmonary sites, such as soft tissues, retroperitoneum, and the peritoneal surface. Bony spread, however, is not as common. Case presentation We report an unusual case of diffuse skeletal metastases from myxoid liposarcoma occurring 13 years after treatment of the primary tumour in the left lower limb. The skeletal spread of the disease was demonstrated on MRI only after other imaging modalities (plain radiography, CT and TC99 bone scans) had failed to detect these metastases. Conclusion MRI is an extremely sensitive and specific screening tool in the detection of skeletal involvement in these types of sarcomas, and therefore, should be a part of the staging process.

Hanna Sammy A; Qureshi Yassar A; Bayliss Lee; David Lee A; O'Donnell Paul; Judson Ian R; Briggs Timothy WR

2008-01-01

147

Symmetry-based detection and diagnosis of DCIS in breast MRI  

Science.gov (United States)

The delineation and diagnosis of non-mass-like lesions, most notably DCIS (ductal carcinoma in situ), is among the most challenging tasks in breast MRI reading. Even for human observers, DCIS is not always easy to diferentiate from patterns of active parenchymal enhancement or from benign alterations of breast tissue. In this light, it is no surprise that CADe/CADx approaches often completely fail to classify DCIS. Of the several approaches that have tried to devise such computer aid, none achieve performances similar to mass detection and classification in terms of sensitivity and specificity. In our contribution, we show a novel approach to combine a newly proposed metric of anatomical breast symmetry calculated on subtraction images of dynamic contrast-enhanced (DCE) breast MRI, descriptive kinetic parameters, and lesion candidate morphology to achieve performances comparable to computer-aided methods used for masses. We have based the development of the method on DCE MRI data of 18 DCIS cases with hand-annotated lesions, complemented by DCE-MRI data of nine normal cases. We propose a novel metric to quantify the symmetry of contralateral breasts and derive a strong indicator for potentially malignant changes from this metric. Also, we propose a novel metric for the orientation of a finding towards a fix point (the nipple). Our combined scheme then achieves a sensitivity of 89% with a specificity of 78%, matching CAD results for breast MRI on masses. The processing pipeline is intended to run on a CAD server, hence we designed all processing to be automated and free of per-case parameters. We expect that the detection results of our proposed non-mass aimed algorithm will complement other CAD algorithms, or ideally be joined with them in a voting scheme.

Srikantha, Abhilash; Harz, Markus T.; Newstead, Gillian; Wang, Lei; Platel, Bram; Hegenscheid, Katrin; Mann, Ritse M.; Hahn, Horst K.; Peitgen, Heinz-Otto

2013-02-01

148

Detection of the dynamic renal function using MRI by gadolinium-DTPA  

Energy Technology Data Exchange (ETDEWEB)

A study of the dynamic renal function in rabbits using MRI by Gd-DTPA was performed. T1 of rabbit kidney, which had been operated (complete unilateral ureteral occlusion or incomplete unilateral occulusion of the renal artery) was calculated before and after intravenous injection of 0.05 mmol/kg of Gd-DTPA, continuously for 90 minutes. All images were obtained by the 0.1 Tesla resistive type MRI. The changes of 1/T1 of cortex and medulla of both kidneys were plotted (MRI renography). T1 of renal cortex was shorter than that of renal medulla in normal kidney by plain T1 image, and T1 of both parts of the kidney was elongated day after day in unilateral hydronephrosis without contrast media. The peak was marked 2 minutes after injection of Gd-DTPA and the half-life of the excretory phase was 30 minute in the cortex and 40 minute in the medulla in normal MRI renography. The operated site was higher than the opposite-site in the change of 1/T1 (the peak value-the value before administration) immediately after operation, but after 24 hours the operated site was lower, in hydronephrotic rabbits. The renal parenchymal damage due to ureteral obstruction was accurately and sensitively detected. In renal arterial stenosis, the change of 1/T1 was minimal in the operated-site because of the reduction of excretion of contrast media due to decrease of GFR. It was concluded that MRI renography was able to detect regional dynamic renal function and it was expected that calculation of ERBF, GFR and tubular excretory function was quantitively examined by mathematical analysis.

Torii, Shinichiro; Tateno, Yukio.

1988-03-01

149

A simple method to detect land changes sourcing from overgrazing using remote sensing  

Science.gov (United States)

This is a technical paper, in the context of CASCADE project, describing an overgrazed area in Cyprus and how remote sensing techniques can assist the procedure for detecting land degradation sourcing from animal overgrazing. Remote sensing is a tool recently introduced to such studies but indeed very useful and vital. Using satellite images it is possible to retrieve consecutive vegetation indices which can identify if there is any further land-vegetation degradation in a specific area of interest. This is crucial in the procedure for monitoring semi or highly overgrazed areas since this change detection can inform policy makers regarding the status of an area, in terms of degradation. In this paper remotely sensed data is analyzed to detect, in specific areas which are known as overgrazed, to detect if there is a change using three main vegetation indices, namely WDVI, NDVI and SAVI. Change detection techniques are applied on these three vegetation indices maps in order to detect any further areas overgrazing.

Papadavid, G.; Themistocleous, K.; Christoforou, M.; Carmen, B.; Tsaltas, D.; Hadjimitsis, D.

2013-08-01

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

Remote Mine Detection Technologies for Land and Water Environments  

Energy Technology Data Exchange (ETDEWEB)

The detection of mines, both during and after hostilities, is a growing international problem. It limits military operations during wartime and unrecovered mines create tragic consequences for civilians. From a purely humanitarian standpoint an estimated 100 million or more unrecovered mines are located in over 60 countries worldwide. This paper presents an overview of some of the technologies currently being investigated by Sandia National Laboratories for the detection and monitoring of minefields in land and water environments. The three technical areas described in this paper are: 1) the development of new mathematical techniques for combining or fusing the data from multiple sources for enhanced decision-making; 2) an environmental fate and transport (EF&T) analysis approach that is central to improving trace chemical sensing technique; and 3) the investigation of an underwater range imaging device to aid in locating and characterizing mines and other obstacles in coastal waters.

Hoover, Eddie R.

1999-05-11

152

Vibration detection and calibration method used to remote sensing optical camera  

Science.gov (United States)

In order to obtain sharp remote sensing images, the image stabilization technology of space camera and the remote sensing image restoration technology are usually used now. Vibration detection is the key to realize these technologies: an image stabilization system needs the displacement vector derived from vibration detection to drive the compensation mechanism; and the remote sensing image restoration technology needs the vibration displacement vector to construct the point spread function (PSF). Vibration detection not only can be used to improve image quality of panchromatic camera, infrared cameras and other optical camera, also is motion compensation basis of satellite radar equipment. In this paper we have constructed a vibration measuring method based on Fiber optic gyro (FOG). FOG is a device sensitive to angular velocity or angular displacement. High-precision FOG can be used to measure the jitter angle of the optic axis of a space camera fixed on satellite platform. According to the measured data, the vibration displacement vector of the imaging plane can be calculated. Consequently the vibration data provide a basis for image stabilization of space camera and restoration of remote sensing images. We simulated the vibration of a space camera by using a piezoelectric ceramic deflection platform, and calibrated vibration measurement by using laser beam and a high-speed linear array camera. We compared the feedback output of the deflection platform, the FOG measured data and the calibrated data of the linear array camera, and obtained a calibration accuracy better than 1.5 ?rad.

Li, Qi; Dong, Wende; Xu, Zhihai; Feng, Huajun

2013-09-01

153

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

International Nuclear Information System (INIS)

[en] 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

2010-01-01

154

TELEMETRY THROUGH REMOTE DETECTION OF NMR-ACTIVE PARTICLES  

UK PubMed Central (United Kingdom)

Various methods of telemetry for nuclear magnetic resonance applications are described. NMR-active particles are introduced into a system which is to undergo an NMR measurement. In various embodiments, the NMR-active particles have a resonance peak in a spectral region which is substantially free from any NMR signal originating from material native to the system. In some embodiments, the NMR-active particles are chemically functionalized to target a constituent within the system. In certain applications, changes in the detected resonance peak can be used to quantify certain characteristics about the system, e.g., a concentration of an analyte, whether a targeted constituent is present within the system.

MARCUS CHARLES M; MARMUREK JONATHAN; APTEKAR JACOB W; VON MALTZAHN GEOFFREY

155

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

156

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; Hongliang Li; Guanghui Liu

2012-01-01

157

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

158

Photoacoustic spectroscopy (PAS) system for remote detection of explosives, chemicals, and special nuclear materials  

Science.gov (United States)

This paper describes a practical photoacoustic spectroscopy technique applied to remote sensing of chemicals in an open environment. A laboratory system that consists of a high-power CO2 laser and an open-field acoustic resonator is described. The acoustic resonator is a combination of a parabolic reflector and a narrow-band cylindrical acoustic resonator that resonates at the laser modulation frequency. The performance of the resonator is theoretically analyzed and experimentally verified. Significant improvement in signal-to-noise ratio has been achieved. Detection of gas-phase photoacoustic signals was demonstrated at a remote distance of several meters from the target. Potential applications to the detection of condensed-phase chemicals are discussed; the detection of the photoacoustic spectrum of trinitrotoluene (TNT) in an open environment is presented.

Chien, Hual-Te; Wang, Ke; Sheen, Shuh-Haw; Raptis, A. C. Paul

2012-05-01

159

Detection of hippocampal atrophy in patients with temporal lobe epilepsy: A 3-Tesla MRI shape.  

Science.gov (United States)

In patients with mesial temporal lobe epilepsy (MTLE), brain MRI often detects hippocampal sclerosis (HS). Almost half of patients with MTLE do not show any hippocampal damage on visual or volumetric assessment. Here, we wished to prospectively assess 65 patients with MTLE (41 women, mean age: 39±10years, range: 21-69; right (12/65 patients) (MRI-negative) nMTLE; right (14/65 patients) (MRI-positive with HS) pMTLE; left (24/65 patients) nMTLE; and left (15/65 patients) pMTLE) using shape analysis (SA). There were significant differences among pMTLE versus nMTLE for age at seizure onset (20.2±12.8 vs. 31.8±16.7years; p=.0029), duration of epilepsy (14.6±12.7 vs. 21.3±9.6years; p=.0227), risk of refractoriness (p=.0067), frequency of antecedent febrile convulsions (FCs) (pTesla MRI protocol. Shape analysis of hippocampal formation was conducted comparing each group versus 44 matched controls. In all four subgroups, SA detected a significant atrophy in the corresponding hippocampus that coincided with the epileptogenic area. The damage was significantly more severe in patients with pMTLE (F value: 5.00) than in subgroups with nMTLE (F value: 3.50) and mainly corresponded to the CA1 subregion and subiculum. In the patients with MTLE, SA detects hippocampal damage that lateralizes with the epileptogenic area. Such damage is most prominent in the CA1 subregion and subiculum that are crucial in the pathogenesis of MTLE. PMID:23892579

Mumoli, Laura; Labate, Angelo; Vasta, Roberta; Cherubini, Andrea; Ferlazzo, Edoardo; Aguglia, Umberto; Quattrone, Aldo; Gambardella, Antonio

2013-07-25

160

Detection of hippocampal atrophy in patients with temporal lobe epilepsy: A 3-Tesla MRI shape.  

UK PubMed Central (United Kingdom)

In patients with mesial temporal lobe epilepsy (MTLE), brain MRI often detects hippocampal sclerosis (HS). Almost half of patients with MTLE do not show any hippocampal damage on visual or volumetric assessment. Here, we wished to prospectively assess 65 patients with MTLE (41 women, mean age: 39±10years, range: 21-69; right (12/65 patients) (MRI-negative) nMTLE; right (14/65 patients) (MRI-positive with HS) pMTLE; left (24/65 patients) nMTLE; and left (15/65 patients) pMTLE) using shape analysis (SA). There were significant differences among pMTLE versus nMTLE for age at seizure onset (20.2±12.8 vs. 31.8±16.7years; p=.0029), duration of epilepsy (14.6±12.7 vs. 21.3±9.6years; p=.0227), risk of refractoriness (p=.0067), frequency of antecedent febrile convulsions (FCs) (p<.001), as well as a history of epilepsy or FCs (p=.0104). All the subjects underwent the same 3-Tesla MRI protocol. Shape analysis of hippocampal formation was conducted comparing each group versus 44 matched controls. In all four subgroups, SA detected a significant atrophy in the corresponding hippocampus that coincided with the epileptogenic area. The damage was significantly more severe in patients with pMTLE (F value: 5.00) than in subgroups with nMTLE (F value: 3.50) and mainly corresponded to the CA1 subregion and subiculum. In the patients with MTLE, SA detects hippocampal damage that lateralizes with the epileptogenic area. Such damage is most prominent in the CA1 subregion and subiculum that are crucial in the pathogenesis of MTLE.

Mumoli L; Labate A; Vasta R; Cherubini A; Ferlazzo E; Aguglia U; Quattrone A; Gambardella A

2013-09-01

 
 
 
 
161

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; Md. Jan Nordin; Amir Hossein Ashtari

2012-01-01

162

In vivo MRI cell tracking using perfluorocarbon probes and fluorine-19 detection.  

UK PubMed Central (United Kingdom)

This article presents a brief review of preclinical in vivo cell-tracking methods and applications using perfluorocarbon (PFC) probes and fluorine-19 ((19) F) MRI detection. Detection of the (19) F signal offers high cell specificity and quantification ability in spin density-weighted MR images. We discuss the compositions of matter, methods and applications of PFC-based cell tracking using ex vivo and in situ PFC labeling in preclinical studies of inflammation and cellular therapeutics. We also address the potential applicability of (19) F cell tracking to clinical trials.

Ahrens ET; Zhong J

2013-07-01

163

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

164

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

UK PubMed Central (United Kingdom)

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.

Li X; Priest RA; Woodward WJ; Tagge IJ; Siddiqui F; Huang W; Rooney WD; Beer TM; Garzotto MG; Springer CS Jr

2013-01-01

165

Self-delivering nanoemulsions for dual fluorine-19 MRI and fluorescence detection.  

Science.gov (United States)

We report the design, synthesis, and biological testing of highly stable, nontoxic perfluoropolyether (PFPE) nanoemulsions for dual 19F MRI-fluorescence detection. A linear PFPE polymer was covalently conjugated to common fluorescent dyes (FITC, Alexa647 and BODIPy-TR), mixed with pluronic F68 and linear polyethyleneimine (PEI), and emulsified by microfluidization. Prepared nanoemulsions (<200 nm) were readily taken up by both phagocytic and non-phagocytic cells in vitro after a short (approximately 3 h) co-incubation. Following cell administration in vivo, 19F MRI selectively visualizes cell migration. Exemplary in vivo MRI images are presented of T cells labeled with a dual-mode nanoemulsion in a BALB/c mouse. Fluorescence detection enables fluorescent microscopy and FACS analysis of labeled cells, as demonstrated in several immune cell types including Jurkat cells, primary T cells and dendritic cells. The intracellular fluorescence signal is directly proportional to the 19F NMR signal and can be used to calibrate cell loading in vitro. PMID:18266363

Janjic, Jelena M; Srinivas, Mangala; Kadayakkara, Deepak K K; Ahrens, Eric T

2008-02-12

166

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

International Nuclear Information System (INIS)

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

2009-01-01

167

Assessment of Gd-EOB-DTPA-enhanced MRI for HCC and dysplastic nodules and comparison of detection sensitivity versus MDCT.  

UK PubMed Central (United Kingdom)

BACKGROUND: We aimed to evaluate gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) for the detection of hepatocellular carcinomas (HCCs) and dysplastic nodules (DNs) compared with dynamic multi-detector row computed tomography (MDCT), and to discriminate between HCCs and DNs. METHODS: Eighty-six nodules diagnosed as HCC or DNs were retrospectively investigated. Gd-EOB-DTPA-enhanced MRI and dynamic MDCT were compared with respect to their diagnostic ability for hypervascular HCCs and detection sensitivity for hypovascular tumors. The ability of hepatobiliary images of Gd-EOB-DTPA-enhanced MRI to discriminate between these nodules was assessed. We also calculated the EOB enhancement ratio of the tumors. RESULTS: For hypervascular HCCs, the diagnostic ability of Gd-EOB-DTPA-enhanced MRI was significantly higher than that of MDCT for tumors less than 2 cm (p = 0.048). There was no difference in the detection of hypervascular HCCs between hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI (43/45: 96%) and dynamic MDCT (40/45: 89%), whereas the detection sensitivity of hypovascular tumors by Gd-EOB-DTPA-enhanced MRI was significantly higher than that by dynamic MDCT (39/41: 95% vs. 25/41: 61%, p = 0.001). EOB enhancement ratios were decreased in parallel with the degree of differentiation in DNs and HCCs, although there was no difference between DNs and hypovascular well-differentiated HCCs. CONCLUSION: The diagnostic ability of Gd-EOB-DTPA-enhanced MRI for hypervascular HCCs less than 2 cm was significantly higher than that of MDCT. For hypovascular tumors, the detection sensitivity of hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI was significantly higher than that of dynamic Gd-EOB-DTPA-enhanced MRI and dynamic MDCT. It was difficult to distinguish between DNs and hypovascular well-differentiated HCCs based on the EOB enhancement ratio.

Inoue T; Kudo M; Komuta M; Hayaishi S; Ueda T; Takita M; Kitai S; Hatanaka K; Yada N; Hagiwara S; Chung H; Sakurai T; Ueshima K; Sakamoto M; Maenishi O; Hyodo T; Okada M; Kumano S; Murakami T

2012-09-01

168

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

169

Improve quality of care with remote activity and fall detection using ultrasonic sensors.  

UK PubMed Central (United Kingdom)

In this paper a fall detection system is presented that automatically detects the fall of a person and their location using an array of ultrasonic wave transducers connected to a field-programmable gate array (FPGA) processor. Experimental results are provided on a prototype deployment installed at an assisted living community. The system can provide a cost-effective and intelligent method to help caregivers detect a fall quickly so that patients are treated in a timely manner. In addition to room monitoring and local alert functions, the system incorporates a personal computer and wireless connection to enable remote monitoring of patient's activity and health status.

Huang Y; Newman K

2012-01-01

170

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; Ruizhi Ren; Shuang Zhang

2011-01-01

171

Using fMRI to Detect Activation of the Cortical and Subcortical Auditory Centers: Development of a Standard Protocol for a Conventional 1.5-T MRI Scanner  

International Nuclear Information System (INIS)

We wanted to develop a standard protocol for auditory functional magnetic resonance imaging (fMRI) for detecting blood oxygenation level-dependent (BOLD) responses at the cortical and subcortical auditory centers with using a 1.5-T MRI scanner. Fourteen normal volunteers were enrolled in the study. The subjects were stimulated by four repetitions of 32 sec each with broadband white noise and silent period blocks as a run (34 echo planar images [EPIs]). Multiple regression analysis for the individual analysis and one-sample t-tests for the group analysis were applied (FDR, p

2009-01-01

172

Performance of a fully automatic lesion detection system for breast DCE-MRI.  

UK PubMed Central (United Kingdom)

PURPOSE: To describe and test a new fully automatic lesion detection system for breast DCE-MRI. MATERIALS AND METHODS: Studies were collected from two institutions adopting different DCE-MRI sequences, one with and the other one without fat-saturation. The detection pipeline consists of (i) breast segmentation, to identify breast size and location; (ii) registration, to correct for patient movements; (iii) lesion detection, to extract contrast-enhanced regions using a new normalization technique based on the contrast-uptake of mammary vessels; (iv) false positive (FP) reduction, to exclude contrast-enhanced regions other than lesions. Detection rate (number of system-detected malignant and benign lesions over the total number of lesions) and sensitivity (system-detected malignant lesions over the total number of malignant lesions) were assessed. The number of FPs was also assessed. RESULTS: Forty-eight studies with 12 benign and 53 malignant lesions were evaluated. Median lesion diameter was 6 mm (range, 5-15 mm) for benign and 26 mm (range, 5-75 mm) for malignant lesions. Detection rate was 58/65 (89%; 95% confidence interval [CI] 79%-95%) and sensitivity was 52/53 (98%; 95% CI 90%-99%). Mammary median FPs per breast was 4 (1st-3rd quartiles 3-7.25). CONCLUSION: The system showed promising results on MR datasets obtained from different scanners producing fat-sat or non-fat-sat images with variable temporal and spatial resolution and could potentially be used for early diagnosis and staging of breast cancer to reduce reading time and to improve lesion detection. Further evaluation is needed before it may be used in clinical practice.

Vignati A; Giannini V; De Luca M; Morra L; Persano D; Carbonaro LA; Bertotto I; Martincich L; Regge D; Bert A; Sardanelli F

2011-12-01

173

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

UK PubMed Central (United Kingdom)

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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. KEY POINTS: • Contrast-enhanced spectral mammography (CESM) is slowly being introduced into clinical practice. • Access to breast MRI is limited by availability and lack of reimbursement. • Initial results show a better sensitivity of CESM and MRI than conventional mammography. • CESM showed a good correlation with postoperative histology in size assessment. • Contrast-enhanced spectral mammography offers promise, seemingly providing information comparable to MRI.

Fallenberg EM; Dromain C; Diekmann F; Engelken F; Krohn M; Singh JM; Ingold-Heppner B; Winzer KJ; Bick U; Renz DM

2013-09-01

174

Multi-kernel graph embedding for detection, Gleason grading of prostate cancer via MRI/MRS.  

UK PubMed Central (United Kingdom)

Even though 1 in 6 men in the US, in their lifetime are expected to be diagnosed with prostate cancer (CaP), only 1 in 37 is expected to die on account of it. Consequently, among many men diagnosed with CaP, there has been a recent trend to resort to active surveillance (wait and watch) if diagnosed with a lower Gleason score on biopsy, as opposed to seeking immediate treatment. Some researchers have recently identified imaging markers for low and high grade CaP on multi-parametric (MP) magnetic resonance (MR) imaging (such as T2 weighted MR imaging (T2w MRI) and MR spectroscopy (MRS)). In this paper, we present a novel computerized decision support system (DSS), called Semi Supervised Multi Kernel Graph Embedding (SeSMiK-GE), that quantitatively combines structural, and metabolic imaging data for distinguishing (a) benign versus cancerous, and (b) high- versus low-Gleason grade CaP regions from in vivo MP-MRI. A total of 29 1.5Tesla endorectal pre-operative in vivo MP MRI (T2w MRI, MRS) studies from patients undergoing radical prostatectomy were considered in this study. Ground truth for evaluation of the SeSMiK-GE classifier was obtained via annotation of disease extent on the pre-operative imaging by visually correlating the MRI to the ex vivo whole mount histologic specimens. The SeSMiK-GE framework comprises of three main modules: (1) multi-kernel learning, (2) semi-supervised learning, and (3) dimensionality reduction, which are leveraged for the construction of an integrated low dimensional representation of the different imaging and non-imaging MRI protocols. Hierarchical classifiers for diagnosis and Gleason grading of CaP are then constructed within this unified low dimensional representation. Step 1 of the hierarchical classifier employs a random forest classifier in conjunction with the SeSMiK-GE based data representation and a probabilistic pairwise Markov Random Field algorithm (which allows for imposition of local spatial constraints) to yield a voxel based classification of CaP presence. The CaP region of interest identified in Step 1 is then subsequently classified as either high or low Gleason grade CaP in Step 2. Comparing SeSMiK-GE with unimodal T2w MRI, MRS classifiers and a commonly used feature concatenation (COD) strategy, yielded areas (AUC) under the receiver operative curve (ROC) of (a) 0.89±0.09 (SeSMiK), 0.54±0.18 (T2w MRI), 0.61±0.20 (MRS), and 0.64±0.23 (COD) for distinguishing benign from CaP regions, and (b) 0.84±0.07 (SeSMiK),0.54±0.13 (MRI), 0.59±0.19 (MRS), and 0.62±0.18 (COD) for distinguishing high and low grade CaP using a leave one out cross-validation strategy, all evaluations being performed on a per voxel basis. Our results suggest that following further rigorous validation, SeSMiK-GE could be developed into a powerful diagnostic and prognostic tool for detection and grading of CaP in vivo and in helping to determine the appropriate treatment option. Identifying low grade disease in vivo might allow CaP patients to opt for active surveillance rather than immediately opt for aggressive therapy such as radical prostatectomy.

Tiwari P; Kurhanewicz J; Madabhushi A

2013-02-01

175

Multi-kernel graph embedding for detection, Gleason grading of prostate cancer via MRI/MRS.  

Science.gov (United States)

Even though 1 in 6 men in the US, in their lifetime are expected to be diagnosed with prostate cancer (CaP), only 1 in 37 is expected to die on account of it. Consequently, among many men diagnosed with CaP, there has been a recent trend to resort to active surveillance (wait and watch) if diagnosed with a lower Gleason score on biopsy, as opposed to seeking immediate treatment. Some researchers have recently identified imaging markers for low and high grade CaP on multi-parametric (MP) magnetic resonance (MR) imaging (such as T2 weighted MR imaging (T2w MRI) and MR spectroscopy (MRS)). In this paper, we present a novel computerized decision support system (DSS), called Semi Supervised Multi Kernel Graph Embedding (SeSMiK-GE), that quantitatively combines structural, and metabolic imaging data for distinguishing (a) benign versus cancerous, and (b) high- versus low-Gleason grade CaP regions from in vivo MP-MRI. A total of 29 1.5Tesla endorectal pre-operative in vivo MP MRI (T2w MRI, MRS) studies from patients undergoing radical prostatectomy were considered in this study. Ground truth for evaluation of the SeSMiK-GE classifier was obtained via annotation of disease extent on the pre-operative imaging by visually correlating the MRI to the ex vivo whole mount histologic specimens. The SeSMiK-GE framework comprises of three main modules: (1) multi-kernel learning, (2) semi-supervised learning, and (3) dimensionality reduction, which are leveraged for the construction of an integrated low dimensional representation of the different imaging and non-imaging MRI protocols. Hierarchical classifiers for diagnosis and Gleason grading of CaP are then constructed within this unified low dimensional representation. Step 1 of the hierarchical classifier employs a random forest classifier in conjunction with the SeSMiK-GE based data representation and a probabilistic pairwise Markov Random Field algorithm (which allows for imposition of local spatial constraints) to yield a voxel based classification of CaP presence. The CaP region of interest identified in Step 1 is then subsequently classified as either high or low Gleason grade CaP in Step 2. Comparing SeSMiK-GE with unimodal T2w MRI, MRS classifiers and a commonly used feature concatenation (COD) strategy, yielded areas (AUC) under the receiver operative curve (ROC) of (a) 0.89±0.09 (SeSMiK), 0.54±0.18 (T2w MRI), 0.61±0.20 (MRS), and 0.64±0.23 (COD) for distinguishing benign from CaP regions, and (b) 0.84±0.07 (SeSMiK),0.54±0.13 (MRI), 0.59±0.19 (MRS), and 0.62±0.18 (COD) for distinguishing high and low grade CaP using a leave one out cross-validation strategy, all evaluations being performed on a per voxel basis. Our results suggest that following further rigorous validation, SeSMiK-GE could be developed into a powerful diagnostic and prognostic tool for detection and grading of CaP in vivo and in helping to determine the appropriate treatment option. Identifying low grade disease in vivo might allow CaP patients to opt for active surveillance rather than immediately opt for aggressive therapy such as radical prostatectomy. PMID:23294985

Tiwari, Pallavi; Kurhanewicz, John; Madabhushi, Anant

2012-12-13

176

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

International Nuclear Information System (INIS)

[en] 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

2004-01-01

177

Multiparametric MRI maps for detection and grading of dominant prostate tumors.  

UK PubMed Central (United Kingdom)

PURPOSE: To develop an image-based technique capable of detection and grading of prostate cancer, which combines features extracted from multiparametric MRI into a single parameter map of cancer probability. MATERIALS AND METHODS: A combination of features extracted from diffusion tensor MRI and dynamic contrast enhanced MRI was used to characterize biopsy samples from 29 patients. Support vector machines were used to separate the cancerous samples from normal biopsy samples and to compute a measure of cancer probability, presented in the form of a cancer colormap. The classification results were compared with the biopsy results and the classifier was tuned to provide the largest area under the receiver operating characteristic (ROC) curve. Based solely on the tuning of the classifier on the biopsy data, cancer colormaps were also created for whole-mount histopathology slices from four radical prostatectomy patients. RESULTS: An area under ROC curve of 0.96 was obtained on the biopsy dataset and was validated by a "leave-one-patient-out" procedure. The proposed measure of cancer probability shows a positive correlation with Gleason score. The cancer colormaps created for the histopathology patients do display the dominant tumors. The colormap accuracy increases with measured tumor area and Gleason score. CONCLUSION: Dynamic contrast enhanced imaging and diffusion tensor imaging, when used within the framework of supervised classification, can play a role in characterizing prostate cancer.

Moradi M; Salcudean SE; Chang SD; Jones EC; Buchan N; Casey RG; Goldenberg SL; Kozlowski P

2012-06-01

178

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.)

2011-01-01

179

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

Energy Technology Data Exchange (ETDEWEB)

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.)

Dorrius, Monique D.; Weide, Marijke C.J. der; Ooijen, Peter M.A. van; Pijnappel, Ruud M.; Oudkerk, Matthijs [University Medical Center Groningen, Department of Radiology, Center for Medical Imaging, Hanzeplein 1, PO box 30.001, Groningen (Netherlands)

2011-08-15

180

Toxicity, biodistribution, and ex vivo MRI detection of intravenously injected cationized ferritin.  

UK PubMed Central (United Kingdom)

The goal of the work was to establish the toxicity and biodistribution of the superparamagnetic protein cationized ferritin (CF) after intravenous injection. Intravenously injected CF has been used to target the extracellular matrix with high specificity in the kidney glomerulus, allowing measurements of individual glomeruli using T2*-weighted MRI. For the routine use of CF as an extracellular matrix-specific tracer, it is important to determine whether CF is toxic. In this work, we investigated the renal and hepatic toxicity, leukocyte count, and clearance of intravenously injected CF. Furthermore, we studied CF labeling in several organs using MRI and immunohistochemistry. Serum measurements of biomarkers suggest that intravenous injection of CF is neither nephrotoxic nor hepatotoxic and does not increase leukocyte counts in healthy rats at a dose of 5.75 mg/100 g. In addition to known glomerular labeling, confocal and MRI suggest that intravenously injected CF labels the extracellular matrix of the hepatic sinusoid, extracellular glycocalyx of alveolar endothelial cells, and macrophages in the spleen. Liver T2* values suggest that CF is cleared by 7 days after injection. These results suggest that CF may serve as a useful contrast agent for detection of a number of structures and functions with minimal toxicity.

Beeman SC; Georges JF; Bennett KM

2013-03-01

 
 
 
 
181

Accuracy and interpretation time of computer-aided detection among novice and experienced breast MRI readers.  

UK PubMed Central (United Kingdom)

OBJECTIVE: The purpose of this study was to compare the diagnostic accuracy and interpretation times of breast MRI with and without use of a computer-aided detection (CAD) system by novice and experienced readers. SUBJECTS AND METHODS: A reader study was undertaken with 20 radiologists, nine experienced and 11 novice. Each radiologist participated in two reading sessions spaced 6 months apart that consisted of 70 cases (27 benign, 43 malignant), read with and without CAD assistance. Sensitivity, specificity, negative predictive value, positive predictive value, and overall accuracy as measured by the area under the receiver operating characteristic curve (AUC) were reported for each radiologist. Accuracy comparisons across use of CAD and experience level were examined. Time to interpret and report on each case was recorded. RESULTS: CAD improved sensitivity for both experienced (AUC, 0.91 vs 0.84; 95% CI on the difference, 0.04, 0.11) and novice readers (AUC, 0.83 vs 0.77; 95% CI on the difference, 0.01, 0.10). The increase in sensitivity was statistically higher for experienced readers (p = 0.01). Diagnostic accuracy, measured by AUC, for novices without CAD was 0.77, for novices with CAD was 0.79, for experienced readers without CAD was 0.80, and for experienced readers with CAD was 0.83. An upward trend was noticed, but the differences were not statistically significant. There were no significant differences in interpretation times. CONCLUSION: MRI sensitivity improved with CAD for both experienced readers and novices with no overall increase in time to evaluate cases. However, overall accuracy was not significantly improved. As the use of breast MRI with CAD increases, more attention to the potential contributions of CAD to the diagnostic accuracy of MRI is needed.

Lehman CD; Blume JD; DeMartini WB; Hylton NM; Herman B; Schnall MD

2013-06-01

182

Comparison of delayed enhanced cine MRI, single photon emission computed tomography and echocardiography for the detection of viable myocardium  

International Nuclear Information System (INIS)

Objective: To evaluate the accuracy of delayed enhanced cardiac MRI(DE-MRI), nitrate stress 99Tcm-MIBI imaging (N-SPECT) and low-dose dobutamine stress echocardiography (LDDSE) for the detection of viable myocardium. Methods: Cardiac rest cine MRI(cine-MRI), DE-URI, N-SPECT and LDDSE were performed in 32 patients within one week after onset of acute myocardial infarction and undertaking percutaneous coronary intervention (PCI) thereafter. Second cine-MRI was performed 6- 11 months after PCI. A 16-segment model was adopted for the image analysis. Wall motion improvement after PCI was considered as a myocardial viability. The sensitivity, specificity and accuracy of three methods for the detection of viable segments were compared dy t and ?2 test. Results: The sensitivity, specificity and accuracy of DE-MRI were 76.7% (79/103), 83.8% (88/105)and 80.3% (167/208), respectively. The sensitivity, specificity and accuracy of N-SPECT were 75.9% (82/108), 65.2% (60/92) and 71.0% (142/200), respectively. The specificity and accuracy of N-SPECT were significantly lower than that of DE- MRI(P

2009-01-01

183

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)

2008-01-01

184

New development of MRI lung nodule simulator for detecting on pulmonary nodule. Experimental study  

Energy Technology Data Exchange (ETDEWEB)

In an effort to augment the value of MRI in detecting lung nodules, we devised a new lung nodule phantom made of polyvinylalcohol. Besides, a thoracic phantom made of polyvinyl alcohol, solidoils, and artificial bone was prepared to evaluate the environmental effect around the nodule phantom. The p, T1 and T2 values of these simulators were equivalent to those of chest wall tissues. T1 and T2 of these phantoms were calculated by use of a 0.2T resistive magnetic resonance machine. Our findings suggested that T1 and T2 of the lung nodule phantom varies as a function of position.

Tanaka, Koji; Yamasaki, Katsuhito; Adachi, Shuji; Kusumoto, Masahiko; Kameda, Kyoko; Kono, Michio

1988-02-01

185

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

186

Improving inferences from fisheries capture-recapture studies through remote detection of PIT tags  

Science.gov (United States)

Models for capture-recapture data are commonly used in analyses of the dynamics of fish and wildlife populations, especially for estimating vital parameters such as survival. Capture-recapture methods provide more reliable inferences than other methods commonly used in fisheries studies. However, for rare or elusive fish species, parameter estimation is often hampered by small probabilities of re-encountering tagged fish when encounters are obtained through traditional sampling methods. We present a case study that demonstrates how remote antennas for passive integrated transponder (PIT) tags can increase encounter probabilities and the precision of survival estimates from capture-recapture models. Between 1999 and 2007, trammel nets were used to capture and tag over 8,400 endangered adult Lost River suckers (Deltistes luxatus) during the spawning season in Upper Klamath Lake, Oregon. Despite intensive sampling at relatively discrete spawning areas, encounter probabilities from Cormack-Jolly-Seber models were consistently low (< 0.2) and the precision of apparent annual survival estimates was poor. Beginning in 2005, remote PIT tag antennas were deployed at known spawning locations to increase the probability of re-encountering tagged fish. We compare results based only on physical recaptures with results based on both physical recaptures and remote detections to demonstrate the substantial improvement in estimates of encounter probabilities (approaching 100%) and apparent annual survival provided by the remote detections. The richer encounter histories provided robust inferences about the dynamics of annual survival and have made it possible to explore more realistic models and hypotheses about factors affecting the conservation and recovery of this endangered species. Recent advances in technology related to PIT tags have paved the way for creative implementation of large-scale tagging studies in systems where they were previously considered impracticable.

Hewitt, David A.; Janney, Eric C.; Hayes, Brian S.; Shively, Rip S.

2010-01-01

187

Temporally consistent probabilistic detection of new multiple sclerosis lesions in brain MRI.  

UK PubMed Central (United Kingdom)

Detection of new Multiple Sclerosis (MS) lesions on magnetic resonance imaging (MRI) is important as a marker of disease activity and as a potential surrogate for relapses. We propose an approach where sequential scans are jointly segmented, to provide a temporally consistent tissue segmentation while remaining sensitive to newly appearing lesions. The method uses a two-stage classification process: 1) a Bayesian classifier provides a probabilistic brain tissue classification at each voxel of reference and follow-up scans, and 2) a random-forest based lesion-level classification provides a final identification of new lesions. Generative models are learned based on 364 scans from 95 subjects from a multi-center clinical trial. The method is evaluated on sequential brain MRI of 160 subjects from a separate multi-center clinical trial, and is compared to 1) semi-automatically generated ground truth segmentations and 2) fully manual identification of new lesions generated independently by nine expert raters on a subset of 60 subjects. For new lesions greater than 0.15 cc in size, the classifier has near perfect performance (99% sensitivity, 2% false detection rate), as compared to ground truth. The proposed method was also shown to exceed the performance of any one of the nine expert manual identifications.

Elliott C; Arnold DL; Collins DL; Arbel T

2013-08-01

188

Whole body MRI: Improved lesion detection and characterization with diffusion weighted techniques.  

UK PubMed Central (United Kingdom)

Diffusion-weighted imaging (DWI) is an established functional imaging technique that interrogates the delicate balance of water movement at the cellular level. Technological advances enable this technique to be applied to whole-body MRI. Theory, b-value selection, common artifacts and target to background for optimized viewing will be reviewed for applications in the neck, chest, abdomen, and pelvis. Whole-body imaging with DWI allows novel applications of MRI to aid in evaluation of conditions such as multiple myeloma, lymphoma, and skeletal metastases, while the quantitative nature of this technique permits evaluation of response to therapy. Persisting signal at high b-values from restricted hypercellular tissue and viscous fluid also permits applications of DWI beyond oncologic imaging. DWI, when used in conjunction with routine imaging, can assist in detecting hemorrhagic degradation products, infection/abscess, and inflammation in colitis, while aiding with discrimination of free fluid and empyema, while limiting the need for intravenous contrast. DWI in conjunction with routine anatomic images provides a platform to improve lesion detection and characterization with findings rivaling other combined anatomic and functional imaging techniques, with the added benefit of no ionizing radiation. J. Magn. Reson. Imaging 2013;38:253-268. © 2013 Wiley Periodicals, Inc.

Attariwala R; Picker W

2013-08-01

189

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

2008-03-19

190

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

191

Using Biogenic Sulfur Gases as Remotely Detectable Biosignatures on Anoxic Planets  

Science.gov (United States)

We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS2, OCS, CH3SH, CH3SCH3, and CH3S2CH3) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH3SCH3, or DMS) and dimethyl disulfide (CH3S2CH3, or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C2H6) over that which would be predicted based on the planet's methane (CH4) concentration. Thus, a characterization mission could detect these organic sulfur gases - and therefore the life that produces them - ;if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere.

Domagal-Goldman, Shawn D.; Meadows, Victoria S.; Claire, Mark W.; Kasting, James F.

2011-06-01

192

Using biogenic sulfur gases as remotely detectable biosignatures on anoxic planets.  

UK PubMed Central (United Kingdom)

We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS(2), OCS, CH(3)SH, CH(3)SCH(3), and CH(3)S(2)CH(3)) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH(3)SCH(3), or DMS) and dimethyl disulfide (CH(3)S(2)CH(3), or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C(2)H(6)) over that which would be predicted based on the planet's methane (CH(4)) concentration. Thus, a characterization mission could detect these organic sulfur gases-and therefore the life that produces them-if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere.

Domagal-Goldman SD; Meadows VS; Claire MW; Kasting JF

2011-06-01

193

Remote ischemic perconditioning in thrombolysed stroke patients : Randomized study of activating endogenous neuroprotection - design and MRI measurements  

DEFF Research Database (Denmark)

BACKGROUND: Intravenous administration of alteplase is the only approved treatment for acute ischemic stroke. Despite the effectiveness of this treatment, 50% of patients suffer chronic neurological disability, which may in part be caused by ischemia-reperfusion injury. Remote ischemic perconditioning, performed as a transient ischemic stimulus by blood-pressure cuff inflation to an extremity, has proven effective in attenuating ischemia-reperfusion injury in animal models of stroke. Remote ischemic perconditioning increases myocardial salvage in patients undergoing acute revascularization for acute myocardial infarction. To clarify whether a similar benefit can be obtained in patients undergoing thrombolysis for acute stroke, we included patients from June 2009 to January 2011. AIM AND DESIGN: The aims of the study are: to estimate the effect of remote ischemic perconditioning as adjunctive therapy to intravenous alteplase of acute ischemic stroke within the 4-h time window and to investigate the feasibilityof remote ischemic perconditioning performed during transport to hospital in patients displaying symptoms of acute stroke. Patients are randomized to remote ischemic perconditioning in a single-blinded fashion during transportation to hospital. Only patients with magnetic resonance imaging-proven ischemic stroke, who subsequently are treated with intravenous alteplase, and in selected cases additional endovascular treatment, are finally included in the study. STUDY OUTCOMES: Primary end-point is penumbral salvage. Penumbra is defined as hypoperfused yet viable tissue identified as the mismatch between perfusion-weighted imaging and diffusion-weighted imaging lesion on magnetic resonance imaging scans. Primary outcome is a mismatch volume not progressing to infarction on one-month follow-up T2 fluid attenuated inversion recovery. Secondary end-points include: infarct growth (expansion of the diffusion-weighted imaging lesion) from baseline to the 24-h and one-month follow-up examination. Infarct growth insideand outside the acute perfusion-weighted imaging-diffusion-weighted imaging mismatch zone is quantified by use of coregistration. Clinical outcome after three-months. The influence of physical activity (Physical Activity Scale for the Elderly score) on effect of remote ischemic perconditioning. Feasibility of remote ischemic perconditioning in acute stroke patients. SUMMARY: This phase 3 trial is the first study in patients with acute ischemic stroke to evaluate the effect size of remote ischemic perconditioning as a pretreatment to intravenous alteplase, measured as penumbral salvage on multimodal magnetic resonance imaging and clinical outcome after three-months follow-up.

Hougaard, K D; Hjort, N

2013-01-01

194

Detection of suspected placental invasion by MRI: do the results depend on observer' experience?  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate the diagnostic value of previously described MR features used for detecting suspected placental invasion according to observers' experience. MATERIALS AND METHODS: Our population included 25 pregnant women (mean age 35.16) investigated by prenatal MRI (1.5T, T1- and T2-weighted MR-sequences without i.v. contrast), among them 12 with histopathologically proven placental invasion and 13 women (52%) without placental invasion used as control group. Two senior and two junior radiologists blindly and independently reviewed MR-examinations in view of 6 previously defined MR-features indicating presence and degree of placental invasion (placenta increta, accreta or percreta). For each reader the sensibility, specificity, and receiver operating curve (ROC) were calculated. Interobserver agreements between senior and junior readers were determined. Stepwise logistic regression was performed including the 6 MR-features predictive of placental invasion. RESULTS: Demographics between both groups were statistically equivalent. Overall sensitivity and specificity for placental invasion was 90.9% and 75.0% for seniors and 81.8% and 61.8% for juniors, respectively. The best single MR-feature indicating placental invasion was T2-hypointense placental bands (r(2)=0.28), followed by focally interrupted myometrial border, infiltration of pelvic organs and tenting of the bladder (r(2)=0.36). Interobserver agreement for detecting placental invasion was 0.64 for seniors and 0.41 for juniors, thus substantial and moderate, respectively. Seniors detected placental invasion and depth of infiltration with significantly higher diagnostic certitude than juniors (p=0.0002 and p=0.0282, respectively). CONCLUSION: MRI can be a reliable and reproducible tool for the detection of suspected placental invasion, but the diagnostic value significantly depends on observers' experience.

Alamo L; Anaye A; Rey J; Denys A; Bongartz G; Terraz S; Artemisia S; Meuli R; Schmidt S

2013-02-01

195

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

International Nuclear Information System (INIS)

[en] 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

2012-01-01

196

Remote Detection and Location of Illegal Radioactive Materials Units in Uzbekistan  

International Nuclear Information System (INIS)

Uzbekistan is a checkpoint for transportation between Russia and some Asian countries, such as Iran, Pakistan, Afghanistan and Tajikistan that might be attractive destinations for those smuggling nuclear materials or weapons. Currently there are over 200 border crossing points. Most of them have equipped with monitors able to reliably detect nuclear materials. Uzbekistan also has substantial radioactive ore mining, and these monitors also allow the Customs Service to maintain safe conditions for their inspectors as well as for population of Uzbekistan and its neighbors. But it is very important to detect radioactive materials inland, their location and travel. This task cannot be solved by using stationary detectors which are used at border crossing points. New method, electronic scheme and software for remote detection, location and travel of radioactive sources were developed. The operation principle lies in detection of radiation by 6 detectors situated in a leaden cylindrical shield collimating gamma-radiation in 6 directions. Besides the detection system contains 6 amplifiers, 6 counters and JPS-system connected with computer. The detection system is transported by car. Field tests of the detection system have shown that the detection limit is 5. 106 Bq and 4.106 Bq for Co60 and Cs137 respectively when the radioactive sources distance is 400 m. (author).

2007-01-01

197

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

198

Change detection monitoring of Khoramabad Region(IRAN) via remote sensing  

Science.gov (United States)

The importance of accurate and timely information describing the nature and extent of land resources and changes over time is increasing, especially in rapidly growing metropolitan areas. Change detection is a technique in remote sensing for detecting the changes which have occurred in the existing phenomena over two or more periods of time in a particular area. In this paper, Khoramabad a city in Lorestan province of Iran, was examined in a case study via three techniques of remote sensing: (1) NDVI comparison, (2) Principle Component Analysis, and (3) the Post Classification. To carry out these three techniques, TM and ETM+ data obtained from Landsat Satellite within the years 1991 to 2002was used to monitor environmental changes especially the physical development of the area and its devastating effects on the green space. In this research, one of the capabilities of Thematic Mapper of Landsat Satellite is presented which is oriented towards determining land use changes and methodology in comparison to the change detection techniques via the standard method.. The result presented here indicates that the farming land area decreased between 1991 and 2002 by 14% from 4975 to 3672 ha. Also the urban and non arable land area increased from 5376 to 6678 ha. We may conclude any land use/land cover change must be permitted by land management expert

Matinfar, Hamid Reza

2010-05-01

199

SVM-BALSA: Remote Homology Detection based on Bayesian Sequence Alignment  

Energy Technology Data Exchange (ETDEWEB)

Using biopolymer sequence comparison methods to identify evolutionarily related proteins is one of the most common tasks in bioinformatics. Recently, support vector machines (SVMs) utilizing statistical learning theory have been employed in the problem of remote homology detection and shown to outperform iterative profile methods such as PSI-BLAST. In this study we demonstrate the utilization of a Bayesian alignment score, which accounts for the uncertainty of all possible alignments, in the SVM construction improves sensitivity compared to the traditional dynamic programming implementation.

Webb-Robertson, Bobbie-Jo M.; Oehmen, Chris S.; Matzke, Melissa M.

2005-11-10

200

Detection of thrombus size and protein content by ex vivo magnetization transfer and diffusion weighted MRI  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background To utilize a rabbit model of plaque disruption to assess the accuracy of different magnetic resonance sequences [T1-weighted (T1W), T2-weighted (T2W), magnetization transfer (MT) and diffusion weighting (DW)] at 11.7?T for the ex vivo detection of size and composition of thrombus associated with disrupted plaques. Methods Atherosclerosis was induced in the aorta of male New Zealand White rabbits (n?=?17) by endothelial denudation and high-cholesterol diet. Subsequently, plaque disruption was induced by pharmacological triggering. Segments of infra-renal aorta were excised fixed in formalin and examined by ex vivo magnetic resonance imaging (MRI) at 11.7?T and histology. Results MRI at 11.7?T showed that: (i) magnetization transfer contrast (MTC) and diffusion weighted images (DWI) detected thrombus with higher sensitivity compared to T1W and T2W images [sensitivity: MTC?=?88.2%, DWI?=?76.5%, T1W?=?66.6% and T2W?=?43.7%, P?P?(ii) MTC and DWI provided a more accurate detection of thrombus area with histology as the gold-standard [underestimation of 6% (MTC) and 17.6% (DWI) compared to an overestimation of thrombus area of 53.7% and 46.4% on T1W and T2W images, respectively]; (iii) the percent magnetization transfer rate (MTR) correlated with the fibrin (r?=?0.73, P?=?0.003) and collagen (r?=?0.9, P?=?0.004) content of the thrombus. Conclusions The conspicuity of the thrombus was increased on MTC and DW compared to T1W and T2W images. Changes in the %MTR and apparent diffusion coefficient can be used to identify the organization stage of the thrombus.

Phinikaridou Alkystis; Qiao Ye; Giordano Nick; Hamilton James A

2012-01-01

 
 
 
 
201

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

Energy Technology Data Exchange (ETDEWEB)

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.

Coolbaugh, T.S. [ExxonMobil Research and Engineering, Fairfax, VA (United States). Safety, Civil and Marine Section, Oil Spill Response Group

2008-07-01

202

Investigation of performance, noise and detectability characteristics of small-scale remotely piloted vehicle /RPV/ propellers  

Science.gov (United States)

Several small-scale propeller configurations, applicable to a conceptual remotely piloted vehicle, were tested under static and simulated forward flight conditions in a wind tunnel to determine their performance, acoustic, and detectability characteristics. The propellers tested had tractor, pusher, and ducted configurations, designed to develop 4 thrust horsepower at a cruise speed of 75 knots at 4000 ft altitude and 95 F. The acoustic data were used to determine the slant range and altitude of no detection of each propeller configuration. The acoustic and detectability characteristics of small-scale propellers were found to be significantly different from those of the large-scale propellers; this is explained by low disk loading or the low operating Reynolds numbers of the propellers. An increase in forward velocity caused a significant drop in SPLs at higher harmonics of the blade passage frequency. Tip speed had a strong effect on noise and detectability in forward flight: most of the propellers were detected at either the first or second harmonic of their blade passage frequency. Three-bladed propellers were generally less detectable than twoor four-bladed propellers for most of the forward velocities. Finally, ducted and pusher propeller configurations were more detectable and less efficient than their free and tractor counterparts.

Janakiram, D. S.; Scruggs, B. W.

1981-10-01

203

Technology Gap Analysis for the Detection of Process Signatures Using Less Than Remote Methods  

Energy Technology Data Exchange (ETDEWEB)

Although remote sensing methods offer advantages for monitoring important illicit process activities, remote and stand-off technologies cannot successfully detect all important processes with the sensitivity and certainty that is desired. The main scope of the program is observables, with a primary focus on chemical signatures. A number of key process signatures elude remote or stand-off detection for a variety of reasons (e.g., heavy particulate emissions that do not propagate far enough for detection at stand-off distances, semi-volatile chemicals that do not tend to vaporize and remain in the environment near the source, etc.). Some of these compounds can provide persistent, process-specific information that is not available through remote techniques; however, the associated measurement technologies have their own set of advantages, disadvantages and technical challenges that may need to be overcome before additional signature data can be effectively and reliably exploited. The main objective of this report is to describe a process to identify high impact technology gaps for important less-than-remote detection applications. The subsequent analysis focuses on the technology development needed to enable exploitation of important process signatures. The evaluation process that was developed involves three interrelated and often conflicting requirements generation activities: • Identification of target signature chemicals with unique intelligence value and their associated attributes as mitigated by environmentally influenced fate and transport effects (i.e., what can you expect to actually find that has intelligence value, where do you need to look for it and what sensitivity and selectivity do you need to see it) • Identification of end-user deployment scenario possibilities and constraints with a focus on alternative detection requirements, timing issues, logistical consideration, and training requirements for a successful measurement • Identification of available measurement technology alternatives and their associated attributes (available off-the-shelf, in near-term development, likely longer-term development and research-phase possibilities). Assembling these requirements into attribute verses generic acceptance criteria level tables and then comparing related attributes between tables allows for rapid visualization of technology gaps and gross estimates of the gap size. By simply weighting the attributes and the requirements in various ways one can also derive the importance of the identified technology gaps. This output can provide the basis for both a near-term technology development roadmap and research focus as well as a decision support tool for selecting the “most likely to succeed” approach. The evaluation process as presented is generally applicable for the determination of measurement technology gaps for a broad range of applications [e.g., nuclear weapons process, chemical weapons production, biological weapons production as well as classical signature categories (e.g., chemical and radionuclide signatures)]. In this paper the method is applied to the specific case of detecting nuclear weapons production processes using semi-volatile chemical signatures as an illustration. This particular case selection allows the leveraging of significant prior knowledge and experience while still being highly relevant to current detection scenario needs.

Hartman, John S.; Atkinson, David A.; Lind, Michael A.; Maughan, A. D.; Kelly, James F.

2005-01-01

204

Intraindividual comparison of 123I-mIBG SPECT/MRI, 123I-mIBG SPECT/CT, and MRI for the detection of adrenal pheochromocytoma in patients with elevated urine or plasma catecholamines.  

UK PubMed Central (United Kingdom)

PURPOSE: To determine the diagnostic performance of ¹²³I-metaiodobenzylguanidine (mIBG) SPECT/MRI fusion, ¹²³I-mIBG SPECT/CT and adrenal MRI for the detection of pheochromocytoma in patients with elevated urine or plasma catecholamines. PATIENTS AND METHODS: Twenty-two consecutive patients underwent both a whole-body ¹²³I-mIBG scan with SPECT/CT of the adrenal region and MRI of the adrenal glands. Fused SPECT/MRI, SPECT/CT, and MRI scans were evaluated. Imaging results were analyzed both on a per-patient and on a per-lesion basis. Histopathology and/or clinical and radiological follow-up served as the reference standard. RESULTS: Sixteen adrenal tumors were found in thirteen patients. On a per-lesion basis, SPECT/CT had a sensitivity of 87.5%, a specificity of 93.8%, and an overall accuracy of 92.5%. MRI had a sensitivity of 87.5%, a specificity of 96.9%, and an overall accuracy of 95.0%. On a per-patient basis, both SPECT/CT and MRI had a sensitivity of 85.7%, a specificity of 93.3%, and an overall accuracy of 90.9%. SPECT/CT was concordant with MRI in 81.8% of cases. SPECT/MRI fusion was superior to both SPECT/CT and MRI and had a sensitivity of 100% on both a per-lesion and a per-patient basis. CONCLUSIONS: ¹²³I-mIBG SPECT/MRI has the highest sensitivity and accuracy for the detection and localization of pheochromocytomas. SPECT/CT and MRI of the adrenal glands are equivalent diagnostic procedures. However, MRI offers the advantage of fully diagnostic assessment of adrenal lesions other than pheochromocytoma undetectable by ¹²³I-mIBG.

Derlin T; Busch JD; Wisotzki C; Schoennagel BP; Bannas P; Papp L; Klutmann S; Habermann CR

2013-01-01

205

A least angle regression method for fMRI activation detection in phase-encoded experimental designs.  

UK PubMed Central (United Kingdom)

This paper presents a new regression method for functional magnetic resonance imaging (fMRI) activation detection. Unlike general linear models (GLM), this method is based on selecting models for activation detection adaptively which overcomes the limitation of requiring a predefined design matrix in GLM. This limitation is because GLM designs assume that the response of the neuron populations will be the same for the same stimuli, which is often not the case. In this work, the fMRI hemodynamic response model is selected from a series of models constructed online by the least angle regression (LARS) method. The slow drift terms in the design matrix for the activation detection are determined adaptively according to the fMRI response in order to achieve the best fit for each fMRI response. The LARS method is then applied along with the Moore-Penrose pseudoinverse (PINV) and fast orthogonal search (FOS) algorithm for implementation of the selected model to include the drift effects in the design matrix. Comparisons with GLM were made using 11 normal subjects to test method superiority. This paper found that GLM with fixed design matrix was inferior compared to the described LARS method for fMRI activation detection in a phased-encoded experimental design. In addition, the proposed method has the advantage of increasing the degrees of freedom in the regression analysis. We conclude that the method described provides a new and novel approach to the detection of fMRI activation which is better than GLM based analyses.

Li X; Coyle D; Maguire L; McGinnity TM; Watson DR; Benali H

2010-10-01

206

A least angle regression method for fMRI activation detection in phase-encoded experimental designs.  

Science.gov (United States)

This paper presents a new regression method for functional magnetic resonance imaging (fMRI) activation detection. Unlike general linear models (GLM), this method is based on selecting models for activation detection adaptively which overcomes the limitation of requiring a predefined design matrix in GLM. This limitation is because GLM designs assume that the response of the neuron populations will be the same for the same stimuli, which is often not the case. In this work, the fMRI hemodynamic response model is selected from a series of models constructed online by the least angle regression (LARS) method. The slow drift terms in the design matrix for the activation detection are determined adaptively according to the fMRI response in order to achieve the best fit for each fMRI response. The LARS method is then applied along with the Moore-Penrose pseudoinverse (PINV) and fast orthogonal search (FOS) algorithm for implementation of the selected model to include the drift effects in the design matrix. Comparisons with GLM were made using 11 normal subjects to test method superiority. This paper found that GLM with fixed design matrix was inferior compared to the described LARS method for fMRI activation detection in a phased-encoded experimental design. In addition, the proposed method has the advantage of increasing the degrees of freedom in the regression analysis. We conclude that the method described provides a new and novel approach to the detection of fMRI activation which is better than GLM based analyses. PMID:20472078

Li, Xingfeng; Coyle, Damien; Maguire, Liam; McGinnity, Thomas M; Watson, David R; Benali, Habib

2010-05-25

207

Remote Monitoring of Cardiovascular Implantable Devices in the Pediatric Population Improves Detection of Adverse Events.  

UK PubMed Central (United Kingdom)

With the exponential growth of cardiovascular implantable electronic devices (CIEDs) in pediatric patients, a new method of long-term surveillance, remote monitoring (RM), has become the standard of care. The purpose of this study was to determine the usefulness of RM as a monitoring tool in the pediatric population. A retrospective review was performed of 198 patients at the University of Iowa Children's Hospital who had CIEDs. Data transmitted by RM were analyzed. The following data were examined: patient demographics; median interval between transmissions; detection of adverse events requiring corrective measures, including detection of lead failure; detection of arrhythmias and device malfunctions independent of symptoms; time gained in the detection of events using RM versus standard practice; the validity of RM; and the impact of RM on data management. Of 198 patients, 162 submitted 615 RM transmissions. The median time between remote transmissions was 91 days. Of 615 total transmissions, 16 % had true adverse events with 11 % prompting clinical intervention. Of those events requiring clinical response, 61 % of patients reported symptoms. The median interval between last follow-up and occurrence of events detected by RM was 46 days, representing a gain of 134 days for patients followed-up at 6-month intervals and 44 days for patients followed-up at 3 month-intervals. The sensitivity and specificity of RM were found to be 99 and 72 %, respectively. The positive and negative predictive values were found to be 41 and 99 %, respectively. RM allows for early identification of arrhythmias and device malfunctions, thus prompting earlier corrective measures and improving care and safety in pediatric patients.

Malloy LE; Gingerich J; Olson MD; Atkins DL

2013-08-01

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)

2009-01-01

209

Detecting computer-induced errors in remote-sensing JPEG compression algorithms.  

Science.gov (United States)

The JPEG image compression standard is very sensitive to errors. Even though it contains error resilience features, it cannot easily cope with induced errors from computer soft faults prevalent in remote-sensing applications. Hence, new fault tolerance detection methods are developed to sense the soft errors in major parts of the system while also protecting data across the boundaries where data flow from one subsystem to the other. The design goal is to guarantee no compressed or decompressed data contain computer-induced errors without detection. Detection methods are expressed at the algorithm level so that a wide range of hardware and software implementation techniques can be covered by the fault tolerance procedures while still maintaining the JPEG output format. The major subsystems to be addressed are the discrete cosine transform, quantizer, entropy coding, and packet assembly. Each error detection method is determined by the data representations within the subsystem or across the boundaries. They vary from real number parities in the DCT to bit-level residue codes in the quantizer, cyclic redundancy check parities for entropy coding, and packet assembly. The simulation results verify detection performances even across boundaries while also examining roundoff noise effects in detecting computer-induced errors in processing steps. PMID:16830897

Nguyen, Cung; Redinbo, G Robert

2006-07-01

210

Detecting computer-induced errors in remote-sensing JPEG compression algorithms.  

UK PubMed Central (United Kingdom)

The JPEG image compression standard is very sensitive to errors. Even though it contains error resilience features, it cannot easily cope with induced errors from computer soft faults prevalent in remote-sensing applications. Hence, new fault tolerance detection methods are developed to sense the soft errors in major parts of the system while also protecting data across the boundaries where data flow from one subsystem to the other. The design goal is to guarantee no compressed or decompressed data contain computer-induced errors without detection. Detection methods are expressed at the algorithm level so that a wide range of hardware and software implementation techniques can be covered by the fault tolerance procedures while still maintaining the JPEG output format. The major subsystems to be addressed are the discrete cosine transform, quantizer, entropy coding, and packet assembly. Each error detection method is determined by the data representations within the subsystem or across the boundaries. They vary from real number parities in the DCT to bit-level residue codes in the quantizer, cyclic redundancy check parities for entropy coding, and packet assembly. The simulation results verify detection performances even across boundaries while also examining roundoff noise effects in detecting computer-induced errors in processing steps.

Nguyen C; Redinbo GR

2006-07-01

211

Protein Remote Homology Detection and Fold Recognition based on Features Extracted from Frequency Profiles  

Directory of Open Access Journals (Sweden)

Full Text Available Protein remote homology detection and fold recognition are central problems in bioinformatics. Currently, discriminative methods based on support vector machine (SVM) are the most effective and accurate methods for solving these problems. The performance of SVM depends on the method of protein vectorization, so a suitable representation of the protein sequence is a key step for the SVM-based methods. In this paper, two kinds of profile-level building blocks of proteins, binary profiles and N-nary profiles, have been presented, which contain the evolutionary information of the protein sequence frequency profile. The protein sequence frequency profiles calculated from the multiple sequence alignments outputted by PSI-BLAST are converted into binary profiles or N-nary profiles. The protein sequences are transformed into fixed-dimension feature vectors by the occurrence times of each binary profile or N-nary profile and then the corresponding vectors are inputted to support vector machines. The latent semantic analysis (LSA) model, an efficient feature extraction algorithm, is adopted to further improve the performance of our methods. Experiments with protein remote homology detection and fold recognition show that the methods based on profile-level building blocks give better results compared to related methods.

Lei Lin; Bin Liu; Xiaolong Wang; Xuan Wang; Buzhou Tang

2011-01-01

212

Detecting remote evolutionary relationships among proteins by large-scale semantic embedding.  

UK PubMed Central (United Kingdom)

Virtually every molecular biologist has searched a protein or DNA sequence database to find sequences that are evolutionarily related to a given query. Pairwise sequence comparison methods--i.e., measures of similarity between query and target sequences--provide the engine for sequence database search and have been the subject of 30 years of computational research. For the difficult problem of detecting remote evolutionary relationships between protein sequences, the most successful pairwise comparison methods involve building local models (e.g., profile hidden Markov models) of protein sequences. However, recent work in massive data domains like web search and natural language processing demonstrate the advantage of exploiting the global structure of the data space. Motivated by this work, we present a large-scale algorithm called ProtEmbed, which learns an embedding of protein sequences into a low-dimensional "semantic space." Evolutionarily related proteins are embedded in close proximity, and additional pieces of evidence, such as 3D structural similarity or class labels, can be incorporated into the learning process. We find that ProtEmbed achieves superior accuracy to widely used pairwise sequence methods like PSI-BLAST and HHSearch for remote homology detection; it also outperforms our previous RankProp algorithm, which incorporates global structure in the form of a protein similarity network. Finally, the ProtEmbed embedding space can be visualized, both at the global level and local to a given query, yielding intuition about the structure of protein sequence space.

Melvin I; Weston J; Noble WS; Leslie C

2011-01-01

213

Preattentive mechanisms of change detection in early auditory cortex: a 7 Tesla fMRI study.  

UK PubMed Central (United Kingdom)

The auditory system continuously monitors the environment for irregularities in an automatic, preattentive fashion. This is presumably accomplished by two mechanisms: a sensory mechanism detects a deviant sound on the basis of differential refractoriness of neural populations sensitive to the standard and deviant sounds, whereas the cognitive mechanism reveals deviance by comparing incoming auditory information with a template derived from previous input. Using fast event-related high resolution fMRI at 7 Tesla we show that both mechanisms can be mapped to different parts of the auditory cortex both at the group level and the single subject level. The sensory mechanism is supported by primary auditory areas in Heschl's gyrus whereas the cognitive mechanism is implemented in more anterior secondary auditory areas. Both mechanisms are equally engaged by simple sine-wave tones and speech-related phonemes indicating that streams of speech and non-speech stimuli are processed in a similar fashion.

Szycik GR; Stadler J; Brechmann A; Münte TF

2013-08-01

214

Detection of renal artery stenoses using MRI with surface shaded display. Interest in azotemic patients  

International Nuclear Information System (INIS)

Forty-three patients with renal artery stenoses were examined with time of flight MR angiography using maximum intensity projection and surface shaded rendering, and with digital substraction angiography. Sensitivity and specificity were 0.83 and 0.78 for main and secondary arteries, 0.87 and 0.84 for main arteries. In azotemic patients, the positive predictive value was estimated at 40 %-70 % and the negative predictive value at 95 %- 98 %, while the prevalence of renal artery stenoses varied from 10 % to 30 %. These results validate MRI for the detection of renal artery stenoses in this population. Surface shaded display was more accurate than maximum intensity projection to reconstruct time of flight sequences and to grade renal artery stenoses. (authors).

1997-01-01

215

Critical evaluation of MRI-targeted TRUS-guided transperineal fusion biopsy for detection of prostate cancer.  

UK PubMed Central (United Kingdom)

PURPOSE: Diagnosis and precise risk stratification of prostate cancer (PC) is essential for individualized treatment decisions. MRI/TRUS fusion has shown encouraging results for detecting clinically significant prostate cancer. Here we critically evaluate MRI-targeted TRUS-guided transperineal fusion biopsy in routine clinical practice. MATERIALS AND METHODS: 347 consecutive patients with suspicion of PC were prospectively included. The median age of patients was 65 years (range 42-84). Mean PSA level was 9.85ng/ml (0.5-104). 49% of men had previous negative TRUS-guided biopsies, 51% underwent primary biopsy. All patients underwent multiparametric (mp)-MRI at 3T and received systematic stereotactic prostate biopsies plus MRI-targeted TRUS-guided biopsies in case of MRI abnormalities. Imaging data and biopsy results were analyzed and a self-designed questionnaire was sent to all men regarding further clinical history and adverse effects of the biopsy. RESULTS: 200 of 347 (58%) biopsy samples showed PC. 73.5% of biopsy proven PC was clinically relevant (NCCN criteria). On mp-MRI, 104 men were reported as highly suspicious for PC and, in these, the tumor detection rate was 82.6% (86/104) with 72% Gleason scores ?7. Overall, targeted cores detected significantly more cancer than systematic biopsies (30% vs. 8.2%). In patients without cancer-suspicious MRI-lesions, 11.7% (11/94) were diagnosed with intermediate risk disease. Regarding adverse effects, 50.6% of patients (152/300) reported mild hematuria, 26% temporary erectile dysfunction and 2.6% needed short-term catheterization after biopsy. In three patients (1%) non-septic febrile urinary tract infection occurred. CONCLUSIONS: MRI-targeted TRUS-guided transperineal fusion biopsy provides high detection rates of clinically significant tumors. mp-MRI still has some limitations, and therefore systematic biopsies should currently not be omitted. The morbidity of the transperineal saturation approach is reasonable and mainly self-limiting.

Kuru TH; Roethke MC; Seidenader J; Simpfendörfer T; Boxler S; Alammar K; Rieker P; Popeneciu VI; Roth W; Pahernik S; Schlemmer HP; Hohenfellner M; Hadaschik BA

2013-04-01

216

Is MRI better than CT for detecting a vascular component to dementia? A systematic review and meta-analysis  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Identification of causes of dementia soon after symptom onset is important, because appropriate treatment of some causes of dementia can slow or halt its progression or enable symptomatic treatment where appropriate. The accuracy of MRI and CT, and whether MRI is superior to CT, in detecting a vascular component to dementia in autopsy confirmed and clinical cohorts of patients with VaD, combined AD and VaD (“mixed dementia”), and AD remain unclear. We conducted a systematic review and meta-analysis to investigate this question. Methods We searched eight databases and screened reference lists to identify studies addressing the review question. We assessed study quality using QUADAS. We estimated summary diagnostic accuracy according to imaging finding, and ratios of diagnostic odds ratios (RDORs) for MRI versus CT and high versus low risk of bias. Results We included 7 autopsy and 31 non-autopsy studies. There was little evidence that selective patient enrolment and risk of incorporation bias impacted on diagnostic accuracy (p?=?0.12 to 0.95). The most widely reported imaging finding was white matter hyperintensities. For CT (11 studies) summary sensitivity and specificity were 71% (95% CI 53%-85%) and 55% (44%-66%). Corresponding figures for MRI (6 studies) were 95% (87%-98%) and 26% (12%-50%). General infarcts was the most specific imaging finding on MRI (96%; 95% CI 94%-97%) and CT (96%; 93%-98%). However, sensitivity was low for both MRI (53%; 36%-70%) and CT (52%; 22% to 80%). No imaging finding had consistently high sensitivity. Based on non-autopsy studies, MRI was more accurate than CT for six of seven imaging findings, but confidence intervals were wide. Conclusion There is insufficient evidence to suggest that MRI is superior to CT with respect to identifying cerebrovascular changes in autopsy-confirmed and clinical cohorts of VaD, AD, and ‘mixed dementia’.

Beynon Rebecca; Sterne Jonathan A C; Wilcock Gordon; Likeman Marcus; Harbord Roger M; Astin Margaret; Burke Margaret; Bessell Alysson; Ben-Shlomo Yoav; Hawkins James; Hollingworth William; Whiting Penny

2012-01-01

217

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

2009-01-01

218

A remote sensor for detecting methane based on palladium-decorated single walled carbon nanotubes.  

UK PubMed Central (United Kingdom)

The remote detection of the concentration of methane at room temperature is performed by a sensor that is configured by the combination of radio frequency identification (RFID), and functionalized carbon nanotubes (CNTs). The proposed sensor is schemed as a thin film RFID tag in a polyethylene substrate, on which a metal trace dipole, a metal trace T impedance matching networks, a 0.5 µm-CMOS RF/DC rectifier chipset and a sensor head of palladium-decorated single walled carbon nanotubes (Pd-SWCNTs) are surface mounted in cascade. The performances of the sensor are examined and described by the defined parameters of the received signal strength index (RSSI) and the comparative analog identifier (?AID). Results validate the sensor's ability to detect molecules of methane at room temperature, showing that the RSSI can increase 4 dB and the ?AID can increase 3% in response to methane concentrations ranging from zero to 100 ppm.

Liu J; Li G

2013-01-01

219

A Remote Sensor for Detecting Methane Based on Palladium-Decorated Single Walled Carbon Nanotubes  

Science.gov (United States)

The remote detection of the concentration of methane at room temperature is performed by a sensor that is configured by the combination of radio frequency identification (RFID), and functionalized carbon nanotubes (CNTs). The proposed sensor is schemed as a thin film RFID tag in a polyethylene substrate, on which a metal trace dipole, a metal trace T impedance matching networks, a 0.5 ?m-CMOS RF/DC rectifier chipset and a sensor head of palladium-decorated single walled carbon nanotubes (Pd-SWCNTs) are surface mounted in cascade. The performances of the sensor are examined and described by the defined parameters of the received signal strength index (RSSI) and the comparative analog identifier (?AID). Results validate the sensor's ability to detect molecules of methane at room temperature, showing that the RSSI can increase 4 dB and the ?AID can increase 3% in response to methane concentrations ranging from zero to 100 ppm.

Liu, Jian; Li, Guomin

2013-01-01

220

Continuously moving table MRI with sliding multislice for rectal cancer staging: Image quality and lesion detection  

International Nuclear Information System (INIS)

[en] Purpose: To determine image quality and lesion detection of sliding multislice (SMS), a recently developed moving table MRI technique, in patients with rectal cancer. Materials and methods: Twenty-seven paired SMS (Avanto, Siemens Medical Solutions) and MDCT (Sensation 64, Siemens Medical Solutions) examinations of abdomen and pelvis were performed in patients with rectal cancer and compared for detection of liver, lymph node and bone metastases by two independent observers. A contrast-enhanced, fat saturated 2D gradient echo sequence (TE, 2.0 ms; TR, 102 ms; slice, 5 mm) was acquired with SMS and a standard contrast-enhanced protocol (100 ml 2.5 ml/s; slice, 5 mm) was used for abdominal MDCT. Standard of reference consisted of a consensus evaluation of SMS, MDCT, and all available follow-up examinations after a period of 6 months. Artifact burden and image quality of SMS was assessed in comparison to stationary gradient echo sequences obtained in an age-matched group of 27 patients. Results: Whereas SMS achieved a mean quality score of 3.65 (scale, 0-4) for the liver, representing very good diagnostic properties, strong breathing artifacts in the intestinal region were observed in 19 cases by both observers. The retroperitoneum still achieved a mean quality score of 3.52, although breathing artifacts were noted in 12 and 15 cases (observers 1 and 2, respectively). The sensitivities of SMS to detect hepatic metastases were 91.2% and 94.1% for both observers, respectively, compared to 98.5%/98.5% for MDCT. The sensitivities for lymph node metastases were 87.5%/81.3% for SMS compared to 78.1%/81.3% for MDCT. The sensitivities for bone metastases were 91.7%/100% for SMS compared to 8.3%/16.7% for MDCT. Conclusion: With slightly reduced image quality in the intestinal region, SMS exhibits equal detection of lymph node and liver metastases compared to MDCT. SMS MRI proved to be superior to MDCT in detection of bone metastases.

2010-01-01

 
 
 
 
221

Continuously moving table MRI with sliding multislice for rectal cancer staging: Image quality and lesion detection  

Energy Technology Data Exchange (ETDEWEB)

Purpose: To determine image quality and lesion detection of sliding multislice (SMS), a recently developed moving table MRI technique, in patients with rectal cancer. Materials and methods: Twenty-seven paired SMS (Avanto, Siemens Medical Solutions) and MDCT (Sensation 64, Siemens Medical Solutions) examinations of abdomen and pelvis were performed in patients with rectal cancer and compared for detection of liver, lymph node and bone metastases by two independent observers. A contrast-enhanced, fat saturated 2D gradient echo sequence (TE, 2.0 ms; TR, 102 ms; slice, 5 mm) was acquired with SMS and a standard contrast-enhanced protocol (100 ml 2.5 ml/s; slice, 5 mm) was used for abdominal MDCT. Standard of reference consisted of a consensus evaluation of SMS, MDCT, and all available follow-up examinations after a period of 6 months. Artifact burden and image quality of SMS was assessed in comparison to stationary gradient echo sequences obtained in an age-matched group of 27 patients. Results: Whereas SMS achieved a mean quality score of 3.65 (scale, 0-4) for the liver, representing very good diagnostic properties, strong breathing artifacts in the intestinal region were observed in 19 cases by both observers. The retroperitoneum still achieved a mean quality score of 3.52, although breathing artifacts were noted in 12 and 15 cases (observers 1 and 2, respectively). The sensitivities of SMS to detect hepatic metastases were 91.2% and 94.1% for both observers, respectively, compared to 98.5%/98.5% for MDCT. The sensitivities for lymph node metastases were 87.5%/81.3% for SMS compared to 78.1%/81.3% for MDCT. The sensitivities for bone metastases were 91.7%/100% for SMS compared to 8.3%/16.7% for MDCT. Conclusion: With slightly reduced image quality in the intestinal region, SMS exhibits equal detection of lymph node and liver metastases compared to MDCT. SMS MRI proved to be superior to MDCT in detection of bone metastases.

Baumann, Tobias [Department of Diagnostic Radiology, University Hospital Freiburg, Hugstetter Strasse 49, 79095 Freiburg (Germany)], E-mail: tobias.baumann@uniklinik-freiburg.de; Ludwig, Ute [Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Hugstetter Strasse 49, 79095 Freiburg (Germany); Pache, Gregor [Department of Diagnostic Radiology, University Hospital Freiburg, Hugstetter Strasse 49, 79095 Freiburg (Germany); Fautz, Hans-Peter [Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Hugstetter Strasse 49, 79095 Freiburg (Germany); Kotter, Elmar; Langer, Mathias; Schaefer, Oliver [Department of Diagnostic Radiology, University Hospital Freiburg, Hugstetter Strasse 49, 79095 Freiburg (Germany)

2010-03-15

222

The John Charnley Award: Diagnostic Accuracy of MRI Versus Ultrasound for Detecting Pseudotumors in Asymptomatic Metal-on-Metal THA.  

UK PubMed Central (United Kingdom)

BACKGROUND: The prevalence of pseudotumors in patients with large-head metal-on-metal (MOM) THA has been the subject of implant recalls and warnings from various regulatory agencies. To date, there is no consensus on whether ultrasound or MRI is superior for the detection of pseudotumors. QUESTIONS/PURPOSES: We prospectively compared ultrasound to MRI for pseudotumor detection in an asymptomatic cohort of patients with MOM THAs. We also compared ultrasound to MRI for assessment of pseudotumor growth and progressive soft tissue involvement at a 6-month interval. METHODS: We enrolled 40 patients with large-head MOM THAs in the study. The mean age was 54 years (range, 34-76 years). The mean time from surgery was 54 months (range, 40-81 months). There were 28 men and 12 women. All patients underwent ultrasound and MRI using slice encoding for metal artifact correction. The gold standard was defined as follows: if both ultrasound and MRI agreed, this was interpreted as concordant and the result was considered accurate. RESULTS: Ultrasound and MRI agreed in 37 of 40 patients (93%). The prevalence of pseudotumors was 31% (12 of 39) in our cohort. Twenty-three of 39 patients (59%) had completely normal tests and four (10%) had simple fluid collections. Ultrasound had a sensitivity of 100% and specificity of 96% while MRI had a sensitivity of 92% and specificity of 100%. CONCLUSIONS: A negative ultrasound rules out pseudotumor in asymptomatic patients as this test is 100% sensitive. Given its lower cost, we recommend ultrasound as the initial screening tool for pseudotumors. LEVEL OF EVIDENCE: Level I, diagnostic study. See the Instructions for Authors for a complete description of levels of evidence.

Garbuz DS; Hargreaves BA; Duncan CP; Masri BA; Wilson DR; Forster BB

2013-07-01

223

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

224

Does the degree of background enhancement in breast MRI affect the detection and staging of breast cancer?  

International Nuclear Information System (INIS)

The purpose of this study was to assess the influence of background enhancement on the detection and staging of breast cancer using MRI as an adjunct to mammography or ultrasound. One hundred forty-six bilateral breast MRI examinations were evaluated to assess the extent of a known primary tumour and to problem solve after mammography or ultrasound without adjusting for the phase in the patients' menstrual cycle. The background enhancement was classified into four categories by visual evaluation: minimal, mild, moderate and marked. In total, 131 histologically confirmed abnormal cases (104 malignant and 27 benign) and 15 normal cases were included in the analysis. There was no tumour size-related bias between the groups (p = 0.522). For the primary index tumour, the sensitivities of MRI with minimal/mild and moderate/marked background enhancement were 100% and 76% (p = 0.001), respectively. Thus, the degree of background enhancement did not affect the specificity. For evaluating tumour extent (n = 104), the accuracy of MRI with moderate/marked background enhancement (52%) was significantly lower than that with minimal/mild background enhancement (84%; p = 0.002). The degree of background enhancement affected the detection and staging of breast cancer using MRI. (orig.)

2011-01-01

225

Does the degree of background enhancement in breast MRI affect the detection and staging of breast cancer?  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study was to assess the influence of background enhancement on the detection and staging of breast cancer using MRI as an adjunct to mammography or ultrasound. One hundred forty-six bilateral breast MRI examinations were evaluated to assess the extent of a known primary tumour and to problem solve after mammography or ultrasound without adjusting for the phase in the patients' menstrual cycle. The background enhancement was classified into four categories by visual evaluation: minimal, mild, moderate and marked. In total, 131 histologically confirmed abnormal cases (104 malignant and 27 benign) and 15 normal cases were included in the analysis. There was no tumour size-related bias between the groups (p = 0.522). For the primary index tumour, the sensitivities of MRI with minimal/mild and moderate/marked background enhancement were 100% and 76% (p = 0.001), respectively. Thus, the degree of background enhancement did not affect the specificity. For evaluating tumour extent (n = 104), the accuracy of MRI with moderate/marked background enhancement (52%) was significantly lower than that with minimal/mild background enhancement (84%; p = 0.002). The degree of background enhancement affected the detection and staging of breast cancer using MRI. (orig.)

Uematsu, Takayoshi [Shizuoka Cancer Center Hospital, Breast Imaging and Breast Intervention Section, Shizuoka (Japan); Kasami, Masako [Shizuoka Cancer Center Hospital, Department of Pathology, Naga-izumi, Shizuoka (Japan); Watanabe, Junichiro [Shizuoka Cancer Center Hospital, Division of Medical Oncology, Naga-izumi, Shizuoka (Japan)

2011-11-15

226

Automatic detection of vegetation changes in the southwestern United States using remotely sensed images  

Energy Technology Data Exchange (ETDEWEB)

The capability to automatically detect vegetation changes using multitemporal remotely sensed image data is of upmost importance to many global-change research projects. A procedure to automatically map vegetation changes within arid and semi-arid regions of the southwestern United States is presented. Multitemporal Landsat Multispectral Scanner (MSS) images were the primary data source, but some preliminary work was also done using same-date Visible-Infrared Spin-Scan Radiometer (VISSR) data for comparison with the MSS results. The change-detection procedure includes multitemporal image calibration using a hybrid method that we developed for the project; the hybrid calibration allows a radiometric calibration to be applied to historical data by using field-radiance information rather than a modeling procedure. The results indicate that a calibrated visible band is more sensitive than the widely used Normalized Difference Vegetation Index (NDVI) in detecting vegetation changes in the arid and semi-arid environments of the southwestern United States. Changes were detected in the desert environment, where the vegetation density is relatively low, with both Landsat MSS and GOES VISSR images. Some changes detected by the automatic procedure were confirmed in the field during two of the Landsat overpasses. The changes corresponded mostly to the blooming of ephemeral or annual vegetation.

Chavez, P.S.; Mackinnon, D.J. [Geological Survey, Flagstaff, AZ (United States)

1994-05-01

227

Object detection in remote sensing imagery using a discriminatively trained mixture model  

Science.gov (United States)

Automatically detecting objects with complex appearance and arbitrary orientations in remote sensing imagery (RSI) is a big challenge. To explore a possible solution to the problem, this paper develops an object detection framework using a discriminatively trained mixture model. It is mainly composed of two stages: model training and object detection. In the model training stage, multi-scale histogram of oriented gradients (HOG) feature pyramids of all training samples are constructed. A mixture of multi-scale deformable part-based models is then trained for each object category by training a latent Support Vector Machine (SVM), where each part-based model is composed of a coarse root filter, a set of higher resolution part filters, and a set of deformation models. In the object detection stage, given a test imagery, its multi-scale HOG feature pyramid is firstly constructed. Then, object detection is performed by computing and thresholding the response of the mixture model. The quantitative comparisons with state-of-the-art approaches on two datasets demonstrate the effectiveness of the developed framework.

Cheng, Gong; Han, Junwei; Guo, Lei; Qian, Xiaoliang; Zhou, Peicheng; Yao, Xiwen; Hu, Xintao

2013-11-01

228

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

2011-01-01

229

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

2011-01-01

230

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

International Nuclear Information System (INIS)

[en] 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

2008-01-01

231

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

International Nuclear Information System (INIS)

[en] 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

2000-01-01

232

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

UK PubMed Central (United Kingdom)

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.

Persinger MA; Roll WG; Tiller SG; Koren SA; Cook CM

2002-06-01

233

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.

Bernardes Juliana S; Dávila Alberto MR; Costa Vítor S; Zaverucha Gerson

2007-01-01

234

Gadolinium(III)-gold nanorods for MRI and photoacoustic imaging dual-modality detection of macrophages in atherosclerotic inflammation.  

Science.gov (United States)

Aim: One of the features of high-risk atherosclerotic plaques is the preponderance of macrophages. Gadolinium(III)-gold nanorods (Gd(III)-GNRs) have been developed as a dual-modality probe for MRI and photoacoustic imaging (PAI) to trace macrophages for determining the degree of inflammation. Materials & methods: Gd(III)-GNRs were utilized for MRI and PAI dual-modality detection of macrophages in living mice and ex vivo simulated macrophage-rich plaque. Results: Gd(III)-GNRs were shown to be endocytosed by macrophages in vitro. Macrophages labeled with Gd(III)-GNRs were detected by both PAI and MRI. With Gd(III)-GNRs, it is possible to institute a multiscale complementary imaging protocol: MRI can screen to identify the location of the probe-phagocytosed macrophages, and intravascular PAI provides a subsequent precise morphology to quantify the infiltration area and invasion depth of macrophages in the arterial wall. Conclusion: This new dual-modality nanoparticle approach has promise for enabling quantitative detection of macrophages in atherosclerotic plaques. Original submitted 2 April 2012; Revised submitted 16 September 2012. PMID:23351094

Qin, Huan; Zhou, Ting; Yang, Sihua; Chen, Qun; Xing, Da

2013-01-25

235

Exploring the detection of associatively novel events using fMRI.  

Science.gov (United States)

Identifying and evaluating events which are novel in a particular environment is crucially important for adaptive behavior. These events are often not just novel, as they typically violate expectations which may be formulated based on numerous features of our surroundings, one of which includes the ordinal structure (temporal order) of relevant stimuli. Events which violate such expectations, namely sequential deviants, constitute one category of associatively novel stimuli. The present event-related fMRI study investigated the detection of sequential deviants presented within three types of equivalently organized, attended visual sequences which differed in stimulus dimensions relevant for defining the sequential structure (position, rhythm, and object identity). Presenting deviants within perceptual sequences defined by position and rhythm stimulus properties triggered comparable patterns of activations within the lateral parietal, premotor, and prefrontal regions. However, the activations identified in the context of position sequences showed a more dorsal distribution when compared to those in rhythm sequences. In contrast, detection of deviants within object sequences was supported by right-lateralized parietal and temporal cortices. Thus, although the obtained results indicate similarities and partial overlap in activations triggered by specific pairs of deviants, differences in their processing were also revealed. This suggests that the general task context and specific stimulus features which define the deviant itself influence which brain regions within a widespread network incorporating lateral prefrontal, anterior premotor, and posterior (mainly lateral parietal) areas will become engaged in its processing. PMID:21319266

Bubic, Andreja; von Cramon, D Yves; Schubotz, Ricarda I

2011-03-01

236

Exploring the detection of associatively novel events using fMRI.  

UK PubMed Central (United Kingdom)

Identifying and evaluating events which are novel in a particular environment is crucially important for adaptive behavior. These events are often not just novel, as they typically violate expectations which may be formulated based on numerous features of our surroundings, one of which includes the ordinal structure (temporal order) of relevant stimuli. Events which violate such expectations, namely sequential deviants, constitute one category of associatively novel stimuli. The present event-related fMRI study investigated the detection of sequential deviants presented within three types of equivalently organized, attended visual sequences which differed in stimulus dimensions relevant for defining the sequential structure (position, rhythm, and object identity). Presenting deviants within perceptual sequences defined by position and rhythm stimulus properties triggered comparable patterns of activations within the lateral parietal, premotor, and prefrontal regions. However, the activations identified in the context of position sequences showed a more dorsal distribution when compared to those in rhythm sequences. In contrast, detection of deviants within object sequences was supported by right-lateralized parietal and temporal cortices. Thus, although the obtained results indicate similarities and partial overlap in activations triggered by specific pairs of deviants, differences in their processing were also revealed. This suggests that the general task context and specific stimulus features which define the deviant itself influence which brain regions within a widespread network incorporating lateral prefrontal, anterior premotor, and posterior (mainly lateral parietal) areas will become engaged in its processing.

Bubic A; von Cramon DY; Schubotz RI

2011-03-01

237

Detectability of Her2 positive tumors using monoclonal antibody conjugated iron oxide nanoparticles in MRI.  

Science.gov (United States)

Detecting an imaging signal from a small number of cells is vital when a disease needs to be diagnosed in an early stage of development. Molecular and genetic information from cancer cell types provide a guide for specific imaging based on gene expression and their activities on the cell membrane. Various physical and biological parameters affect the capability of an imaging system to provide an efficient procedure for biomarker imaging. Iron oxide based magnetic nanoparticles conjugated to breast cancer monoclonal antibody (Her2) were used as a specific contrast agent for detection of the tumor cells in nude mice models. All processes for the nanoparticle synthesis, antibody development, and conjugation strategies were designed and evaluated in the current work. The final engineered product was found to be without precipitate containing 20 microg antibody/mg magnetic nanoparticles at 10 mg Fe/ml solution. This contrast agent has a high affinity for the BT474 breast cancer cells. MRI images of nude mice bearing tumor cells confirm this specific biomarker based imaging protocol. PMID:21770186

Oghabian, M A; Jeddi-Tehrani, M; Zolfaghari, A; Shamsipour, F; Khoei, S; Amanpour, S

2011-06-01

238

Detectability of Her2 positive tumors using monoclonal antibody conjugated iron oxide nanoparticles in MRI.  

UK PubMed Central (United Kingdom)

Detecting an imaging signal from a small number of cells is vital when a disease needs to be diagnosed in an early stage of development. Molecular and genetic information from cancer cell types provide a guide for specific imaging based on gene expression and their activities on the cell membrane. Various physical and biological parameters affect the capability of an imaging system to provide an efficient procedure for biomarker imaging. Iron oxide based magnetic nanoparticles conjugated to breast cancer monoclonal antibody (Her2) were used as a specific contrast agent for detection of the tumor cells in nude mice models. All processes for the nanoparticle synthesis, antibody development, and conjugation strategies were designed and evaluated in the current work. The final engineered product was found to be without precipitate containing 20 microg antibody/mg magnetic nanoparticles at 10 mg Fe/ml solution. This contrast agent has a high affinity for the BT474 breast cancer cells. MRI images of nude mice bearing tumor cells confirm this specific biomarker based imaging protocol.

Oghabian MA; Jeddi-Tehrani M; Zolfaghari A; Shamsipour F; Khoei S; Amanpour S

2011-06-01

239

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

Energy Technology Data Exchange (ETDEWEB)

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

240

Remote Detection of Chemicals Using Femto-Second Laser Induced Breakdown Spectroscopy  

Science.gov (United States)

Laser-Induced Breakdown Spectroscopy (LIBS) is being used for the analysis of surface contaminant pollutants and chemical compounds by focusing a high power femtosecond laser beam onto a contaminated surface. A femtosecond laser has the broad bandwidth that allows pulse compression by group velocity dispersion in air to achieve high power and high intensity at controlled remote distances [1]. A short laser pulse (˜ 50 fs) produced by a Ti: Sapphire laser at 800 nm wavelength is propagated and focused in the laboratory to initiate LIBS. The research focuses on the detection of atoms, ions and chemical radicals present in the plasma generated by the high intensity laser. Emission radiation from the breakdown of contaminant is spectrally analyzed for signatures of the constituent chemical compounds. Currently, proof-of-concept studies are in progress, using representative chemicals such as sodium nitrate. Preliminary results will be presented. [1] I. Alexeev, et. al, APL 84, 4080(2004)

Ahmido, Tariq; Ting, Antonio; Misra, Prabhakar

2008-11-01

 
 
 
 
241

Application of remote sensing technique to detection of Ordovician Karst water in Fengfeng mine area  

Energy Technology Data Exchange (ETDEWEB)

Fengfeng mine area, which is situated at the foot of the eastern side of the Taihang Mountains, has been threatened by heavy Ordovician Karst Water for a long time. Remote sensing technique was used to make exploratory survey of ground water at shallow places and Ordovician Karst Water at greater depths. The following information was obtained: (1) the abundance of water is controlled by neotectonic movement and has close relationship with topography and depth of aquifer; (2) comprehensive image features of topography, shallow ground water and river drainage reflected the correlative information. The strong ground water run off zones and positions of water intake determined on the basis of the correlative information were proved by comparing with the inflow of borehole, ground water level and temperature. The method is of great significance for detecting Karst water in North China. 3 refs., 4 figs., 3 tabs.

Zhu, D.; Wang, W.; Wang, J.; Zeng, S. (Central Coal Mining Research Institute, Xian (China))

1991-06-01

242

Integrated method for long-term environmental change detection by remote sensing  

Science.gov (United States)

Remote sensing methods make it possible to analyze and describe landscape changes. However, one can hardly acquire sufficient data for direct long-term analysis. Multiple sensors, geometric distortions, phenological phase differences, atmospheric conditions, different solar angles and many other effects cause inter-scene variability. Furthermore, the temporal distribution of available data sets is often inhomogeneous, which tends to amplify the above-mentioned problems. In our work, we propose a methodology to cope with these difficulties for long-term environmental monitoring and quantitative change detection. A complex approach was chosen with the objective of integrating different methods and disciplines (radiometric and geometric correction, classification, image segmentation and GIS analysis, among others) to extract the maximum of information from the available data. This methodology is presented and tested on an interesting case study that deals the environmental effects of a barrage system in the northwestern part of Hungary.

Kristof, Daniel; Ducrot, Danielle

2004-02-01

243

A change in pituitary MRI protocol detects ACTH-secreting tumours in patients with previously negative results  

Science.gov (United States)

Objective While detection of pituitary tumors with magnetic resonance imaging (MRI) may reduce diagnostic costs and improve surgical outcomes for patients with Cushing's disease, the optimal T1-weighted spin echo MRI protocol remains unknown. We hypothesized that specific MR scanning parameters influence detection of corticotropinomas. Design and patients Between December 1997 and November 2004, 21 of 84 consecutive patients with Cushing's disease had a falsely negative initial pituitary MRI study and a lesion identified subsequently at the National Institutes of Health Clinical Center. This study retrospectively reviewed and compared technical parameters used for the two pituitary T1-weighted spin echo MRIs in 18 patients with available scans. Measurements Repetition time (TR)/echo times (TE), field of view (FOV), matrix size, magnetic field strength, slice thickness, use of Gadolinium contrast and the time interval between studies were recorded. Results The MRI inter-scan interval was 5.4 ± 1.1 months. All scans used gadolinium, matrix sizes were similar and nearly all had 3 mm slice thickness. Parameters that differed between the NIH and outside scans were: TR (400 ms vs. 492±19 ms, P = 0.0002); TE (10.3 ± 0.5 vs. 17.2 ms ± 1.2 ms, P = 0.0003); FOV (12×12 cm vs.17±0.6 × 18±0.7 cm, P<0.0001). Immunohistochemistry of tumors resected at transsphenoidal surgery confirmed all tob be corticotropinomas. Conclusions Not all “T1-weighted spin echo” scans are equally accurate. MRI technique, particularly FOV and TR/TE value, influences results. We recommend that endocrinologists consider pituitary MRI parameters when interpreting the results.

Chowdhury, Iffat N.; Sinaii, Ninet; Oldfield, Edward H.; Patronas, Nicholas; Nieman, Lynnette K.

2009-01-01

244

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

245

An initial experimental study-the value of gadolinium-enhanced MRI and delay enhanced MRI in detecting articular cartilage degeneration of the rabbit knee  

International Nuclear Information System (INIS)

Objective: To explore the appearance and value of early and delaye Gadolinium- enhanced MRI in detecting aricular cartilage generation of rabbit knee. Methods: Twenty adult New Zealand rabbits were randomly divided into five groups (A, B, C, D, E). Intra-articular injection of Papain was performed to establish animal models of different stages of cartilage degeneration in the right knees of A, B, C, D groups, and MR scan was conducted 24 hours,one week one month and three months after the last Papain injection. The knees were scanned bilaterally with T1WI and 3D-FS-SPGR in sagittal plane. The signal intensity ratio between articular cartilage and surrounding soft tissue was measured at plain scan and 0, 2, 4 hours after intravenous injection of gadolinium (Gd-DTPA). The articular cartilage was pathologically examined (HE and alcican blue stain). Results: In 3D-FS-SPGR sequence, it showed significant difference in the SIR between processing side of four groups (F=7.961, P1WI sequence in detecting the change of cartilage signal intensity. (2)SIR on early and delayed Gadolinium-enhanced MRI has the ability in evaluating the early stage change of cartilage degeneration. (authors)

2007-01-01

246

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

247

Integrating Subcellular Location for Improving Machine Learning Models of Remote Homology Detection in Eukaryotic Organisms  

Energy Technology Data Exchange (ETDEWEB)

Motivation: At the center of bioinformatics, genomics, and pro-teomics is the need for highly accurate genome annotations. Producing high-quality reliable annotations depends on identifying sequences which are related evolutionarily (homologs) on which to infer function. Homology detection is one of the oldest tasks in bioinformatics, however most approaches still fail when presented with sequences that have low residue similarity despite a distant evolutionary relationship (remote homology). Recently, discriminative approaches, such as support vector machines (SVMs) have demonstrated a vast improvement in sensitivity for remote homology detection. These methods however have only focused on one aspect of the sequence at a time, e.g., sequence similarity or motif based scores. However, supplementary information, such as the sub-cellular location of a protein within the cell would give further clues as to possible homologous pairs, additionally eliminating false relationships due to simple functional roles that cannot exist due to location. We have developed a method, SVM-SimLoc that integrates sub-cellular location with sequence similarity information into a pro-tein family classifier and compared it to one of the most accurate sequence based SVM approaches, SVM-Pairwise. Results: The SCOP 1.53 benchmark data set was utilized to assess the performance of SVM-SimLoc. As cellular location prediction is dependent upon the type of sequence, eukaryotic or prokaryotic, the analysis is restricted to the 2630 eukaryotic sequences in the benchmark dataset, evaluating a total of 27 protein families. We demonstrate that the integration of sequence similarity and sub-cellular location yields notably more accurate results than using sequence similarity independently at a significance level of 0.006.

Shah, Anuj R.; Oehmen, Chris S.; Harper, Jill K.; Webb-Robertson, Bobbie-Jo M.

2007-02-23

248

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.

Amelia M. Shannon; Hannah E. Power; Jody M. Webster; Ana Vila-Concejo

2012-01-01

249

Intraindividual comparison of gadobutrol and gadopentetate dimeglumine for detection of myocardial late enhancement in cardiac MRI.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Gadobutrol is an extracellular macrocyclic gadolinium chelate recently introduced in MRI, and it has already been used for cardiac late enhancement imaging; however, until now it has never been compared with gadopentetate dimeglumine. The purpose of our study was to compare 0.1 mmol/kg gadobutrol to 0.2 mmol/kg gadopentetate dimeglumine for the detection of myocardial late enhancement in the same group of patients. SUBJECTS AND METHODS: This was an exploratory single-blind parallel group study comparing gadobutrol (0.1 mmol/kg) to gadopentetate dimeglumine (0.2 mmol/kg) in 20 adult patients scheduled for cardiac late enhancement MRI with gadopentetate dimeglumine and whose MR images showed late enhancement. MR images were acquired at 10, 15, and 20 minutes after peripheral injection of gadobutrol by using a 3D turbo field echo inversion recovery T1-weighted sequence. Volume and percentage of late enhancement, number of involved segments, late enhancement localization and pattern, and late enhancement signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared between contrast agents. RESULTS: Late enhancement was not significantly different with gadobutrol and gadopentetate dimeglumine both in terms of total volume of myocardium (mean ± SD, 37.8 ± 56.1 and 35.1 ± 46.7 cm(3), respectively; p = 0.33) and percentage of myocardial wall involvement (22.5% ± 19.1% and 22.0% ± 17.2%, respectively; p = 0.67). The number of segments involved was not different (138 with gadobutrol vs 134 with gadopentetate dimeglumine). Furthermore, SNR and CNR were not different (gadopentetate dimeglumine, 123.8 ± 82.9 and gadobutrol, 117.2 ± 88.6, p = 0.58 and gadopentetate dimeglumine, 96.2 ± 68.9 and gadobutrol, 88.4 ± 72.9, p = 0.53, respectively). CONCLUSION: A single dose of gadobutrol seems to be as effective as a double dose of gadopentetate dimeglumine for the detection of late enhancement.

De Cobelli F; Esposito A; Perseghin G; Sallemi C; Belloni E; Ravelli S; Lanzani C; Del Maschio A

2012-04-01

250

Surface-length index: a novel index for rapid detection of right ventricles with abnormal ejection fraction using cardiac MRI.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To validate a new index, the surface-length index (SLI) based on area change in a short-axis view and length reduction in the horizontal long-axis view, which is used to quickly (<1 min) detect right ventricles with an abnormal ejection fraction (EF) during a cardiac MRI examination. SLI can be used to avoid a complete delineation of the endocardial contours of normal right ventricles. METHODS: Sixty patients (group A) were retrospectively included to calibrate the SLI formula by optimisation of the area under the ROC curves and SLI thresholds were chosen to obtain 100 % sensitivity. Another 340 patients (group B) were prospectively recruited to test SLI's capacity to detect right ventricles (RVs) with an abnormal EF (<0.5). RESULTS: The appropriate threshold to obtain 100 % sensitivity in group A was 0.58. In group B, with the 0.58 threshold, SLI yielded a sensitivity of 100 % and specificity of 51 %. SLI would have saved 35 % of the RV studies in our population, without inducing any diagnostic error. SLI and EF correlation was good (r (2)?=?0.64). CONCLUSION: SLI combines two simple RV measures, and brings significant improvement in post-processing efficiency by preselecting RVs that require a complete study. KEY POINTS: • Assessment of right ventricle ejection fraction (RVEF) with cine-MRI is time consuming. • Therefore, RVEF is not always assessed during cardiac MRI. • Surface-length index (SLI) allows rapid detection of abnormal RVEF during cardiac MRI. • SLI saves one third of the operator time. • Every cardiac MRI could include RVEF assessment by means of SLI.

Bonnemains L; Mandry D; Menini A; Stos B; Felblinger J; Marie PY; Vuissoz PA

2013-09-01

251

Using fMRI to Detect Activation of the Cortical and Subcortical Auditory Centers: Development of a Standard Protocol for a Conventional 1.5-T MRI Scanner  

Energy Technology Data Exchange (ETDEWEB)

We wanted to develop a standard protocol for auditory functional magnetic resonance imaging (fMRI) for detecting blood oxygenation level-dependent (BOLD) responses at the cortical and subcortical auditory centers with using a 1.5-T MRI scanner. Fourteen normal volunteers were enrolled in the study. The subjects were stimulated by four repetitions of 32 sec each with broadband white noise and silent period blocks as a run (34 echo planar images [EPIs]). Multiple regression analysis for the individual analysis and one-sample t-tests for the group analysis were applied (FDR, p <0.05). The auditory cortex was activated in most of the volunteers (left 100% and right 92.9% at an uncorrected p value <0.05, and left 92.9% and right 92.9% at an uncorreced p value <0.01). The cochlear nuclei (100%, 85.7%), inferior colliculi (71.4%, 64.3%), medial geniculate bodies (64.3%, 35.7%) and superior olivary complexes (35.7%, 35.7%) showed significant BOLD responses at uncorrected p values of <0.05 and p <0.01, respectively. On the group analysis, the cortical and subcortical auditory centers showed significant BOLD responses (FDR, p <0.05), except for the superior olivary complex. The signal intensity time courses of the auditory centers showed biphasic wave forms. We successfully visualized BOLD responses at the cortical and subcortical auditory centers using appropriate sound stimuli and an image acquisition method with a 1.5-T MRI scanner.

Tae, Woo Suk; Kim, Sam Soo; Lee, Kang Uk; Lee, Seung Hwan; Nam, Eui Cheol [Kangwon National University School of Medicine, Chuncheon (Korea, Republic of); Choi, Hyun Kyung [Kangwon National University Hospital, Chuncheon (Korea, Republic of)

2009-11-15

252

Lung MRI at 3.0 T: a comparison of helical CT and high-field MRI in the detection of diffuse lung disease  

International Nuclear Information System (INIS)

The purpose of this study was to evaluate the feasibility of high-field magnetic resonance imaging (MRI) of the lung using a T2-weighted fast-spin echo (TSE) sequence. Comparison was made with helical computed tomography CT findings in patients with diffuse pulmonary diseases. Prospective segment-wise analysis of high-field MR imaging findings in 15 patients with diffuse pulmonary diseases was made using helical CT and HRCT as the standard of reference. The MR studies were performed on a 3.0-T whole body system (Intera 3T, Philips Medical Systems) using a T2w TSE sequence with respiratory and cardiac gating (TE 80 ms TR 1,500-2,500 ms; turbo factor 17; 22 slices with 7/2-mm slice thickness and gap; 256 x 192 matrix). MR artifacts were graded on a three-point scale (low, moderate, high). Lung MR studies were prospectively analyzed segment-by-segment and diagnosed as healthy or pathological; results were compared with helical CT findings. In all 15 patients, MR imaging of the lung was successful. All 15 MR studies were compromised by artifacts; however, the severity of these artifacts was classified as low or moderate in 8/15, respectively, 7/15 cases. A total of 143/285 lung segments showed diffuse lung disease in helical CT. With MRI, 133 of these 143 segments (93%) were judged to be diseased. The ten segments that received false negative MR diagnoses displayed non-acute pulmonary lesions with inherently low proton density (scars, granulomas). MRI at 3.0 T can detect diffuse pulmonary disease with a high sensitivity. Based on this experience, further pulmonary studies with high-field systems appear justified and promising. (orig.)

2005-01-01

253

The Value of Non-EPI Diffusion-Weighted (DW) MRI versus EPI and Conventional MR Sequences in the Detection of Middle Ear Cholesteatoma  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background/Objective: The non-echo planar imaging diffusion-weighted (non-EPI DW) MRI sequence has recently emerged as a new imaging technique in detecting cholesteatoma. We have compared the diagnostic efficacy of conventional MRI with this new sequence. "nPatients and Methods: A group of 23 p...

Kavous Firouznia; Hashem Sharifian; Elham Taheri; Amir Reza Azizian; Madjid Shakiba; Pedram Borghei; Reza Farjad

254

Detection of local recurrent prostate cancer after radical prostatectomy in terms of salvage radiotherapy using dynamic contrast enhanced-MRI without endorectal coil  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Purpose To evaluate the value of dynamic contrast enhanced Magnetic Resonance Imaging (DCE-MRI) without endorectal coil (EC) in the detection of local recurrent prostate cancer (PC) after radical prostatectomy (RP). Material and methods Thirty-three patients with recurrent PC underwent DCE-MRI without EC before salvage radiotherapy (RT). At median 15 (mean 16±4.9, range 12–27) months after completion of RT all patients showed complete biochemical response. Additional follow up post RT DCE-MRI scans were available. Prostate specific antigen (PSA) levels at the time of imaging were correlated to the imaging findings. Results In 22/33 patients (67%) early contrast enhancing nodules were detected in the post-prostatectomy fossa on pre-RT DCE-MRI images. The average pre-RT PSA level of the 22 patients with positive pre-RT DCE-MRI findings was significantly higher (mean, 0.74±0.64 ng/mL) compared to the pre-RT PSA level of the 11 patients with negative pre-RT DCE-MRI (mean, 0.24±0.13 ng/mL) (p Conclusions This is the first study that shows that DCE-MRI without EC can detect local recurrent PC with an estimated accuracy of 83% at low PSA levels. All false negative DCE-MRI scans were detected using a PSA cut-off of ?0.54 ng/mL.

Rischke Hans Christian; Schäfer Arnd O; Nestle Ursula; Volegova-Neher Natalja; Henne Karl; Benz Matthias R; Schultze-Seemann Wolfgang; Langer Mathias; Grosu Anca L

2012-01-01

255

Comparative study of diffusion weighted imaging and dynamic contrast enhanced MRI for the detection of small breast cancers  

International Nuclear Information System (INIS)

Objective: To compare the sensitivity of diffusion weighted imaging (DWI) with dynamic contrast enhanced (DCE) MRI for the detection of small breast cancers and to evaluate the clinical value of DWI. Methods: Forty-eight patients with benign (n=25) and malignant (n=45) small breast lesions (?2 cm) proved by pathology underwent DWI and DCE MRI. The DCE MRI was performed using FLASH sequence and the time-signal intensity curve was drawn. The DWI was performed using GRAPPA- EPI sequence with different b values (800, 1000 s/mm2) and the ADC values of lesions were measured. The sensitivity and specificity of DWI for the detection of small breast cancers were compared with DCE MRI. Results: Forty of 45 small breast cancers and 19 of 25 small benign breast lesions were correctly diagnosed using DCE MRI. The sensitivity and positive predictive value of TIC were 88.9% (40/45) and 87.0% (40/46). With b values of 800 s/mm2 and 1000 s/mm2, the average ADC values of small breast cancers were (1.153±0.192) x 10-3 and (1.079±0.186) x 10-3 mm2/s, while those of benign ones were (1.473±0.252) x 10-3 and (1.419 ± 0.255) x 10-3 mm2/s, respectively. There was no significant difference for the ADC values with different b values in the same group (P>0.05), while there was a significant difference between the malignant and the benign lesions (P2. Both the sensitivity and positive predictive value of diagnosis were 86.7% (39/45). The abilities of DWI and DCE MRI for the diagnosis of small breast cancers were the same. The sensitivity (93.3%) and positive predictive value (91.3%) were improved with the combination of DCE MRI and DWI. Conclusion: DWI has a high sensitivity for the detection of small breast cancers, the ADC value can provide valuable information in the differential diagnosis. (authors)

256

Automated detection of snow avalanche deposits: segmentation and classification of optical remote sensing imagery  

Directory of Open Access Journals (Sweden)

Full Text Available Snow avalanches in mountainous areas pose a significant threat to infrastructure (roads, railways, energy transmission corridors), personal property (homes) and recreational areas as well as for lives of people living and moving in alpine terrain. The impacts of snow avalanches range from delays and financial loss through road and railway closures, destruction of property and infrastructure, to loss of life. Avalanche warnings today are mainly based on meteorological information, snow pack information, field observations, historically recorded avalanche events as well as experience and expert knowledge. The ability to automatically identify snow avalanches using Very High Resolution (VHR) optical remote sensing imagery has the potential to assist in the development of accurate, spatially widespread, detailed maps of zones prone to avalanches as well as to build up data bases of past avalanche events in poorly accessible regions. This would provide decision makers with improved knowledge of the frequency and size distributions of avalanches in such areas. We used an object–oriented image interpretation approach, which employs segmentation and classification methodologies, to detect recent snow avalanche deposits within VHR panchromatic optical remote sensing imagery. This produces avalanche deposit maps, which can be integrated with other spatial mapping and terrain data. The object-oriented approach has been tested and validated against manually generated maps in which avalanches are visually recognized and digitized. The accuracy (both users and producers) are over 0.9 with errors of commission less than 0.05. Future research is directed to widespread testing of the algorithm on data generated by various sensors and improvement of the algorithm in high noise regions as well as the mapping of avalanche paths alongside their deposits.

M. J. Lato; R. Frauenfelder; Y. Bühler

2012-01-01

257

Use of remote sensing to detect soybean cyst nematode-induced plant stress.  

UK PubMed Central (United Kingdom)

Integrating remote sensing and geographic information systems (GIS) technologies offers tremendous opportunities for farmers to more cost effectively manage the causes of crop stress. Initial soybean cyst nematode (SCN) population densities from 995 2-x-3-m quadrats were obtained from a soybean field near Ames, Iowa, in 2000. The percentage of sunlight reflected from each quadrat was measured weekly using a multispectral radiometer beginning in mid-May and continuing through mid-September. Aerial images were obtained at heights above the field ranging from 45 to 425 m on 12 dates during the soybean growing season. This was accomplished using color film and infrared film in conjunction with a filter to measure reflectance in the near-infrared region (810 nm). Satellite images (Landsat 7) were obtained for five dates during the 2000 growing season. Maps depicting initial SCN population densities, soybean yield, soy oil, and soy protein were generated using the GIS software program ArcView. Percentage reflectance (810 nm), aerial image intensity, and satellite image intensity data then were regressed against soybean yield, soy oil, and soy protein concentrations obtained from each geospatially referenced soybean quadrat. Percentage reflectance measurements explained up to 60% of the variation in initial SCN population densities within soybean quadrats and up to 91% of the variation in soybean yield. Aerial image and satellite image intensities explained up to 80% and 47% of the variation in soybean yield, respectively. Percentage reflectance data also explained 36% and 54% of the variation in oil and protein concentrations of the harvested soybeans, respectively. These results indicate that remote sensing coupled with GIS technologies may provide new tools to detect and quantify SCN population densities and their impacts on the quantity and quality of soybean yield.

Nutter FW; Tylka GL; Guan J; Moreira AJ; Marett CC; Rosburg TR; Basart JP; Chong CS

2002-09-01

258

Representations of recent and remote autobiographical memories in hippocampal subfields.  

UK PubMed Central (United Kingdom)

The hippocampus has long been implicated in supporting autobiographical memories, but little is known about how they are instantiated in hippocampal subfields. Using high resolution functional MRI combined with multi-voxel pattern analysis we found it was possible to detect representations of specific autobiographical memories in individual hippocampal subfields. Moreover, while subfields in the anterior hippocampus contained information about both recent (two weeks old) and remote (ten years old) autobiographical memories, posterior CA3 and DG only contained information about the remote memories. Thus, the hippocampal subfields are differentially involved in the representation of recent and remote autobiographical memories during vivid recall. © 2013 Wiley Periodicals, Inc.

Bonnici HM; Chadwick MJ; Maguire EA

2013-06-01

259

Remote detection of magmatic water in Bullialdus crater on the Moon  

Science.gov (United States)

Once considered dry compared with Earth, laboratory analyses of igneous components of lunar samples have suggested that the Moon’s interior is not entirely anhydrous. Water and hydroxyl have also been detected from orbit on the lunar surface, but these have been attributed to nonindigenous sources, such as interactions with the solar wind. Magmatic lunar volatiles—evidence for water indigenous to the lunar interior—have not previously been detected remotely. Here we analyse spectroscopic data from the Moon Mineralogy Mapper (M3) and report that the central peak of Bullialdus Crater is significantly enhanced in hydroxyl relative to its surroundings. We suggest that the strong and localized hydroxyl absorption features are inconsistent with a surficial origin. Instead, they are consistent with hydroxyl bound to magmatic minerals that were excavated from depth by the impact that formed Bullialdus Crater. Furthermore, estimates of thorium concentration in the central peak using data from the Lunar Prospector orbiter indicate an enhancement in incompatible elements, in contrast to the compositions of water-bearing lunar samples. We suggest that the hydroxyl-bearing material was excavated from a magmatic source that is distinct from that of samples analysed thus far.

Klima, Rachel; Cahill, John; Hagerty, Justin J.; Lawrence, David

2013-01-01

260

Detecting an Invasive Shrub in Deciduous Forest Understories Using Remote Sensing  

UK PubMed Central (United Kingdom)

Remote sensing has been used to directly detect and map invasive plants, but has not been used for forest understory invaders because they are obscured by a canopy. However, if the invasive species has a leaf phenology distinct from native forest species, then temporal opportunities exist to detect the invasive. Amur honeysuckle, an Asian shrub that invades North American forests, expands leaves earlier and retains leaves later than native woody species. This research project explored whether Landsat 5 TM and Landsat 7 ETM+ imagery could predict Amur honeysuckle cover in woodlots across Darke and Preble Counties in southwestern Ohio and Wayne County in adjacent eastern Indiana. The predictive abilities of six spectral vegetation indices and six reflectance bands were evaluated to determine the best predictor or predictors of Amur honeysuckle cover. The use of image differencing in which a January 2001 image was subtracted from a November 2005 image provided better prediction of Amur honeysuckle cover than the use of the single November 2005 image. The Normalized Difference Vegetation Index (NDVI) was the best-performing predictor variable, compared to other spectral indices, with a quadratic function providing a better fit (R2 = 0.75) than a linear function (R2 = 0.65). This predictive model was verified with 15 other woodlots (R2 = 0.77). With refinement, this approach could map current and past understory invasion by Amur honeysuckle.

Wilfong BryanN; Gorchov DavidL; Henry MaryC

2009-09-01

 
 
 
 
261

Remote detection of magmatic water in Bullialdus Crater on the Moon  

Science.gov (United States)

Once considered dry compared with Earth, laboratory analyses of igneous components of lunar samples have suggested that the Moon's interior is not entirely anhydrous. Water and hydroxyl have also been detected from orbit on the lunar surface, but these have been attributed to nonindigenous sources, such as interactions with the solar wind. Magmatic lunar volatiles--evidence for water indigenous to the lunar interior--have not previously been detected remotely. Here we analyse spectroscopic data from the Moon Mineralogy Mapper (M3) and report that the central peak of Bullialdus Crater is significantly enhanced in hydroxyl relative to its surroundings. We suggest that the strong and localized hydroxyl absorption features are inconsistent with a surficial origin. Instead, they are consistent with hydroxyl bound to magmatic minerals that were excavated from depth by the impact that formed Bullialdus Crater. Furthermore, estimates of thorium concentration in the central peak using data from the Lunar Prospector orbiter indicate an enhancement in incompatible elements, in contrast to the compositions of water-bearing lunar samples. We suggest that the hydroxyl-bearing material was excavated from a magmatic source that is distinct from that of samples analysed thus far.

Klima, R.; Cahill, J.; Hagerty, J.; Lawrence, D.

2013-09-01

262

Electromagnetic material changes for remote detection and monitoring: a feasibility study: Progress report  

International Nuclear Information System (INIS)

A new concept for radiation detection is proposed, allowing a decoupling of the sensing medium and the readout. An electromagnetic material, such as a magnetic ceramic ferrite, is placed near a source to be tracked such as a shipping container. The electromagnetic material changes its properties, in this case its magnetic permeability, as a function of radiation. This change is evident as a change in reflection frequency and magnitude when probed using a microwave/millimeter-wave source. This brief report discusses modeling of radiation interaction of various candidate materials using a radiation detector modeling code Geant4, system design considerations for the remote readout, and some theory of the material interaction physics. The theory of radiation change in doped magnetic insulator ferrites such as yttrium iron garnet (YIG) seems well founded based on literature documentation of the photomagnetic effect. The literature also suggests sensitivity of permittivity to neutrons in some ferroelectrics. Research to date indicates that experimental demonstration of these effects in the context of radiation detection is warranted.

2009-01-01

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.

2011-01-01

264

Diffusion-weighted imaging as part of hybrid PET/MRI protocols for whole-body cancer staging: does it benefit lesion detection?  

UK PubMed Central (United Kingdom)

PURPOSE: Positron emission tomography/magnetic resonance imaging (PET/MRI) requires efficient scan protocols for whole-body cancer staging. The aim of this study was to evaluate if the application of diffusion-weighted MR imaging (DWI) results in a diagnostic benefit for lesion detection in oncologic patients if added to a whole-body [18F]-fluorodesoxyglucose ([18F]-FDG) PET/MRI protocol. METHODS: 25 consecutive oncologic patients (16 men, 9 women; age 57 ± 12 years) prospectively underwent whole-body [18F]-FDG-PET/MRI including DWI on a hybrid PET/MRI scanner. A team of two readers assessed [18F]-FDG PET/MRI without DWI for primary tumors and metastases. In a second session, now considering DWI, readers reassessed [18F]-FDG PET/MRI accordingly. Additionally, the lesion-to-background contrast on [18F]-FDG PET and DWI was rated qualitatively (0, invisible; 1, low; 2, intermediate; 3, high). Wilcoxon's signed-rank test was performed to test for differences in the lesion-to-background contrast. RESULTS: 49 lesions were detected in 16 patients (5 primaries, 44 metastases). All 49 lesions were concordantly detected by [18F]-FDG PET/MRI alone and [18F]-FDG PET/MRI with DWI. The lesion-to-background contrast on DWI compared to [18F]-FDG PET was rated lower in 22 (44.9%) of 49 detected lesions resulting in a significantly higher lesion-to-background contrast on [18F]-FDG PET compared to DWI (P=0.001). CONCLUSIONS: DWI as part of whole-body [18F]-FDG PET/MRI does not benefit lesion detection. Given the necessity to optimize imaging protocols with regard to patient comfort and efficacy, DWI has to be questioned as a standard tool for whole-body staging in oncologic PET/MRI.

Buchbender C; Hartung-Knemeyer V; Beiderwellen K; Heusch P; Kühl H; Lauenstein TC; Forsting M; Antoch G; Heusner TA

2013-05-01

265

In Vivo Detection of Free Radicals in Mouse Septic Encephalopathy using Molecular MRI and Immuno-Spin-Trapping.  

UK PubMed Central (United Kingdom)

Free radicals are known to play a major role in sepsis. Combined immuno-spin-trapping (IST) and molecular magnetic resonance imaging (mMRI) were used to detect in vivo and in situ levels of free radicals in murine septic encephalopathy following cecal ligation and puncture (CLP). DMPO (5,5-dimethyl pyrroline N-oxide) was injected over 6h following CLP, prior to administration of an anti-DMPO probe (anti-DMPO antibody bound to albumin-Gd (gadolinium)-DTPA (diethylene triamine penta acetic acid)-biotin MRI targeting contrast agent). In vitro assessment of the anti-DMPO probe in oxidatively-stressed mouse astrocytes significantly decreased T1 relaxation (p<0.0001), compared to controls. MRI detected the presence of anti-DMPO adducts via a substantial decrease in %T1 change within the hippocampus, striatum, occipital and medial cortex brain regions (p<0.01 for all) in septic animals compared to shams, which was sustained for over 60min (p<0.05 for all). Fluorescently-labeled streptavidin was used to target the anti-DMPO probe biotin, which was elevated in septic brain, liver and lungs, compared to sham. Ex vivo DMPO adducts (qualitative), and oxidative products, including 4-hydroxynonenal and 3-nitrotyrosine (quantitative, p<0.05 for both), were elevated in septic brains compared to shams. This is the first study that has reported on the detection of in vivo and in situ levels of free radicals in murine septic encephalopathy.

Towner RA; Garteiser P; Bozza F; Smith N; Saunders D; d'Avila JC; Magno F; Oliveira MF; Ehrenshaft M; Lupu F; Silasi-Mansat R; Ramirez DC; Gomez-Mejiba SE; Mason RP; Faria-Neto HC

2013-08-01

266

Perceptual organization and visual search processes during target detection task performance in schizophrenia, as revealed by fMRI.  

UK PubMed Central (United Kingdom)

BACKGROUND: Past studies of perceptual organization in schizophrenia have demonstrated impairments binding fragmented stimulus components into unified representations. ERP and fMRI data indicate that even under conditions of adequate behavioral task performance, significant and meaningful changes in cortical and subcortical activation are present. Here, we examined, using fMRI, activation differences on a visual task wherein feature grouping was a precursor to the formation of distinct groups in the service of target location and identification. METHOD: Fourteen schizophrenia patients and 16 healthy controls completed a target detection task with 2 conditions: one in which target-distractor grouping facilitates detection (the Isolated condition) and one in which it hinders detection (the Embedded condition). Stimuli were blocked by condition. Accuracy and RT data were obtained in addition to fMRI data. RESULTS: Patients and controls did not differ significantly in accuracy or RT in either condition. Within this context, controls demonstrated greater recruitment of brain regions involved in visual-spatial processing, and the groups differed in activity in areas known to support visual search, visual analysis, decision making and response generation. CONCLUSION: These findings are consistent with past data indicating reduced processing of stimulus organization, and the subsequent use of inefficient visual search strategies, even under conditions when behavioral performance is at a high level and matches that of healthy controls.

Silverstein SM; Berten S; Essex B; All SD; Kasi R; Little DM

2010-08-01

267

Joint pain undergoes a transition in accordance with signal changes of bones detected by MRI in hip osteoarthritis.  

UK PubMed Central (United Kingdom)

OBJECTIVES: In this study, we aimed to investigate whether joint pain is derived from cartilage or bone alterations. METHODS: We reviewed 23 hip joints of 21 patients with primary hip osteoarthritis (OA), which were classified into Kellgren-Laurence (KL) grading I to IV. Plain radiographs and magnetic resonance imaging (MRI) were obtained from all of the 23 joints. Two of the 21 patients had bilateral hip OA. Pain was assessed based on the pain scale of Denis. A Welch t test was performed for age, height, weight, body mass index, bone mineral density, and a Mann-Whitney U test was performed for KL grading. RESULTS: Four of 8 hip joints with pain and OA showed broad signal changes detected by MRI. Fourteen hip joints without pain, but with OA did not show broad signal changes by MRI. Collectively, MRI analyses showed that broad signal changes in OA cases without joint pain or with a slight degree of joint pain were not observed, while broad signal changes were observed in OA cases with deteriorated joint pain. CONCLUSION: Our findings suggest that hip joint pain might be associated with bone signal alterations in the hips of OA patients.

Kamimura M; Nakamura Y; Ikegami S; Uchiyama S; Kato H

2013-01-01

268

The Hazard Mapping System (HMS)-a Multiplatform Remote Sensing Approach to Fire and Smoke Detection  

Science.gov (United States)

The HMS is a multiplatform remote sensing approach to detecting fires and smoke over the US and adjacent areas of Canada and Mexico that has been in place since June 2002. This system is an integral part of the National Environmental Satellite and Data Information Service (NESDIS) near realtime hazard detection and mitigation efforts. The system utilizes NOAA's Geostationary Operational Environmental Satellites (GOES), Polar Operational Environmental Satellites (POES) and the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra and Aqua spacecraft. Automated detection algorithms are employed for each of the satellites for the fire detects while smoke is added by a satellite image analyst. In June 2003 the HMS underwent an upgrade. A number of features were added for users of the products generated on the HMS. Sectors covering Alaska and Hawaii were added. The use of Geographic Information System (GIS) shape files for smoke analysis is a new feature. Shape files show the progression and time of a single smoke plume as each analysis is drawn and then updated. The analyst now has the ability to view GOES, POES, and MODIS data in a single loop. This allows the fire analyst the ability to easily confirm a fire in three different data sets. The upgraded HMS has faster satellite looping and gives the analyst the ability to design a false color image for a particular region. The GOES satellites provide a relatively coarse 4 km infrared resolution at satellite subpoint for thermal fire detection but provide the advantage of a rapid update cycle. GOES imagery is updated every 15 minutes utilizing both GOES-10 and GOES-12. POES imagery from NOAA-15, NOAA-16 and NOAA-17 and MODIS from Terra and Aqua are employed with each satellite providing twice per day coverage (more frequent over Alaska). While the frequency of imagery is much less than with GOES the higher resolution of these satellites (1 km along the suborbital track) allows for detection of smaller and/or cooler burning fires. Each of the algorithms utilizes a number of temporal, thermal and contextual filters in an attempt to screen out false detects. However, false detects do get processed by the algorithms to varying degrees. Therefore, the automated fire detects from each algorithm are quality controlled by an analyst who scans the imagery and may either accept or delete fire points. The analyst also has the ability to manually add additional fire points based on the imagery. Smoke is outlined by the analyst using visible imagery, primarily GOES which provides 1 km resolution. Occasionally a smoke plume seen in visible imagery is the only indicator of a fire and would be manually added to the fire detect file. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) is a forecast model that projects the trajectory and dispersion of a smoke plume over a period of time. The HYSPLIT is run for fires that are selected by the analyst that are seen to be producing a significant smoke plume. The analyst defines a smoke producing area commensurate with the size of the fire and amount of smoke detected. The output is hosted on an Air Resources Lab (ARL) web site which can be accessed from the web site listed below. All of the information is posted to the web page noted below. Besides the interactive GIS presentation users can view the product in graphical jpg format. The analyst edited points as well as the unedited automated fire detects are available for users to view directly on the web page or to download. All of the data is also archived and accessed via ftp.

Kibler, J.; Ruminski, M. G.

2003-12-01

269

GPU implementation of target and anomaly detection algorithms for remotely sensed hyperspectral image analysis  

Science.gov (United States)

Automatic target and anomaly detection are considered very important tasks for hyperspectral data exploitation. These techniques are now routinely applied in many application domains, including defence and intelligence, public safety, precision agriculture, geology, or forestry. Many of these applications require timely responses for swift decisions which depend upon high computing performance of algorithm analysis. However, with the recent explosion in the amount and dimensionality of hyperspectral imagery, this problem calls for the incorporation of parallel computing techniques. In the past, clusters of computers have offered an attractive solution for fast anomaly and target detection in hyperspectral data sets already transmitted to Earth. However, these systems are expensive and difficult to adapt to on-board data processing scenarios, in which low-weight and low-power integrated components are essential to reduce mission payload and obtain analysis results in (near) real-time, i.e., at the same time as the data is collected by the sensor. An exciting new development in the field of commodity computing is the emergence of commodity graphics processing units (GPUs), which can now bridge the gap towards on-board processing of remotely sensed hyperspectral data. In this paper, we describe several new GPU-based implementations of target and anomaly detection algorithms for hyperspectral data exploitation. The parallel algorithms are implemented on latest-generation Tesla C1060 GPU architectures, and quantitatively evaluated using hyperspectral data collected by NASA's AVIRIS system over the World Trade Center (WTC) in New York, five days after the terrorist attacks that collapsed the two main towers in the WTC complex.

Paz, Abel; Plaza, Antonio

2010-08-01

270

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

Energy Technology Data Exchange (ETDEWEB)

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.).

Menor, F. (Dept. of Diagnostic Radiology, La Fe Children' s Hospital, Valencia (Spain)); Marti-Bonmati, L. (Dr. Peset Hospital, Valencia (Spain))

1992-08-01

271

Detection of local recurrent prostate cancer after radical prostatectomy in terms of salvage radiotherapy using dynamic contrast enhanced-MRI without endorectal coil.  

UK PubMed Central (United Kingdom)

PURPOSE: To evaluate the value of dynamic contrast enhanced Magnetic Resonance Imaging (DCE-MRI) without endorectal coil (EC) in the detection of local recurrent prostate cancer (PC) after radical prostatectomy (RP). MATERIAL AND METHODS: Thirty-three patients with recurrent PC underwent DCE-MRI without EC before salvage radiotherapy (RT). At median 15 (mean 16±4.9, range 12-27) months after completion of RT all patients showed complete biochemical response. Additional follow up post RT DCE-MRI scans were available. Prostate specific antigen (PSA) levels at the time of imaging were correlated to the imaging findings. RESULTS: In 22/33 patients (67%) early contrast enhancing nodules were detected in the post-prostatectomy fossa on pre-RT DCE-MRI images. The average pre-RT PSA level of the 22 patients with positive pre-RT DCE-MRI findings was significantly higher (mean, 0.74±0.64 ng/mL) compared to the pre-RT PSA level of the 11 patients with negative pre-RT DCE-MRI (mean, 0.24±0.13 ng/mL) (p<0.001). All post-RT DCE-MRI images showed complete resolution of initial suspicious lesions. A pre-RT PSA cut-off value of ?0.54 ng/ml readily predicted a positive DCE-MRI finding. CONCLUSIONS: This is the first study that shows that DCE-MRI without EC can detect local recurrent PC with an estimated accuracy of 83% at low PSA levels. All false negative DCE-MRI scans were detected using a PSA cut-off of ?0.54 ng/mL.

Rischke HC; Schäfer AO; Nestle U; Volegova-Neher N; Henne K; Benz MR; Schultze-Seemann W; Langer M; Grosu AL

2012-01-01

272

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

UK PubMed Central (United Kingdom)

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.

Andronache A; Rosazza C; Sattin D; Leonardi M; D'Incerti L; Minati L

2013-01-01

273

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

2013-08-22

274

MRI in prostate carcinoma - conventional versus endorectal surface coil MRI  

International Nuclear Information System (INIS)

In a prospective study an attempt was made to determine the value of conventional MRI (354 patients) and MRI using the endorectal surface coil (ESC) (36 patients) in the preoperative staging of prostatic carcinoma. Local preoperative staging with conventional MRI was correct in 83.9% and 88.9% with ESC-MRI. Compared to conventional MRI, ESC-MRI was better in the delineation of the prostatic capsule and early detection of infiltration into the neurovascular bundle. Lymph node staging with MRI showed a sensitivity of 54.4% in detecting pelvic lymph node metastasis. MRI is as limited as CT in assessing pelvic lymph node metastasis. (orig.).

1994-01-01

275

Comparison of FDG PET/CT and gadolinium-enhanced MRI for the detection of bone metastases in patients with cancer: a meta-analysis.  

UK PubMed Central (United Kingdom)

OBJECTIVE: At present, the differences in the efficacy between PET/CT and MRI for the detection of bone metastases in patients with cancer have not been clearly delineated. We performed a meta-analysis to compare the performance of FDG PET/CT with that of gadolinium-enhanced MRI for the detection of bone metastases in patients with cancer. METHODS: Studies about PET/CT and MRI for the detection of bone metastases were systematically searched in the MEDLINE, EMBASE, and EBM Review databases. We calculated sensitivities, specificities, diagnostic odds ratios, positive likelihood ratios, negative likelihood ratios (NLR), and constructed summary receiver operating characteristic curves using bivariate regression models for PET/CT and MRI, respectively. RESULTS: Across 9 studies (1116 patients), FDG PET/CT has similar patient-based sensitivity (0.803 vs 0.837), specificity (0.989 vs 0.977), diagnostic odds ratio (309.0 vs 221.9), positive likelihood ratio (61.7 vs 37.0), and negative likelihood ratio (0.200 vs 0.167) with gadolinium-enhanced MRI. Areas under the curve with 95% confidence interval for FDG PET/CT and gadolinium-enhanced MRI were 0.99 (0.98-0.99) and 0.98 (0.97-0.99), respectively. CONCLUSIONS: FDG PET/CT and gadolinium-enhanced MRI have excellent diagnostic performance for the detection of bone metastases in patients with cancer.

Duo J; Han X; Zhang L; Wang G; Ma Y; Yang Y

2013-05-01

276

Detection of Usefullness of Integrating Remotely Sensed Data (Landsat TM) with GIS  

Directory of Open Access Journals (Sweden)

Full Text Available A study integrating remote sensing and Geographical Information System (GIS) was carried out in the Kuala Terengganu district, Terengganu, Malaysia to map and determine the land use change as a result of development pressure in the area. Two sets of Landsat Thematic Mapper (TM) dated 31 July 1988 and 14 July 2002, at scale 1: 150 000 were acquired. Land use classes were interpreted from these images and the resultant maps were checked in the field to determine ground truth and mapping accuracy. The land use map data were transferred directly into the computer via ILWIS (Integrated Land Water and Water Information System) version 3.1 software. It shown that in this study seven categories of land use changes were detected namely forest (-9.93%), agricultural (-1.46%), swamp (-36.92%), urban (190.29%), cleared land (-21.43%), water bodies (-7.48%) and bush/shrub (6.34%). The accuracy assessment undertaken showed that the total accuracy for produced the map is 77.89%. This study showed that Landsat TM is a useful data for study in land use change.

H. Abdul Halim; H.A. Jumaat; M.A. Juhari; A.R. Sahibin; Hafiza A. Hamid; Ramlan Bin Omar; Gire Kibe Gopir; Jumat Salimon; Barzani Qasim

2006-01-01

277

Ion probe detection of clusters in a remotely expanding thermal plasma  

Energy Technology Data Exchange (ETDEWEB)

The investigation of a remote depositing Ar/NH{sub 3}/SiH{sub 4}-fed expanding thermal plasma by means of an ion probe, under high SiH{sub 4} flow rate ( {Phi}{sub SiH{sub 4}}>1 sccs) conditions, is reported here. Given the expanding nature of the plasma in the downstream region, a Gaussian-like ion flux radial profile is observed. A peculiar local off-axis ion peak for high {Phi}{sub SiH{sub 4}} is also observed nearby. A hypothesis for this phenomenon is proposed, on the basis of the plasma chemistry occurring in the downstream region. The local depletion of electrons, being withdrawn by silicon-containing clusters formed at the boundaries between the plasma beam and the background gas, is responsible for the local enhancement of the ion flux. This hypothesis is corroborated by further studies aiming to evaluate the effects of thermophoretic and electrostatic forces on the above-mentioned clusters. The presented work suggests the application of the capacitive probe technique for cluster detection in specific plasma chemistries.

Petcu, M C; Sarkar, A; Bronneberg, A C; Creatore, M; Van de Sanden, M C M, E-mail: m.c.petcu@tue.n [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, Den Dolech 2, 5600 MB Eindhoven (Netherlands)

2010-12-15

278

Ion probe detection of clusters in a remotely expanding thermal plasma  

International Nuclear Information System (INIS)

The investigation of a remote depositing Ar/NH3/SiH4-fed expanding thermal plasma by means of an ion probe, under high SiH4 flow rate ( ?SiH4>1 sccs) conditions, is reported here. Given the expanding nature of the plasma in the downstream region, a Gaussian-like ion flux radial profile is observed. A peculiar local off-axis ion peak for high ?SiH4 is also observed nearby. A hypothesis for this phenomenon is proposed, on the basis of the plasma chemistry occurring in the downstream region. The local depletion of electrons, being withdrawn by silicon-containing clusters formed at the boundaries between the plasma beam and the background gas, is responsible for the local enhancement of the ion flux. This hypothesis is corroborated by further studies aiming to evaluate the effects of thermophoretic and electrostatic forces on the above-mentioned clusters. The presented work suggests the application of the capacitive probe technique for cluster detection in specific plasma chemistries.

2010-01-01

279

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

280

Whole-heart dipyridamole stress first-pass myocardial perfusion MRI for the detection of coronary artery disease  

International Nuclear Information System (INIS)

A whole-heart coverage MRI sequence, which employs a hybrid of fast gradient echo and echo planar acquisition imaging (FastCard EchoTrain), has recently been developed. Using this sequence, a first-pass myocardial perfusion MRI was shown to be a good non-invasive modality for detecting coronary artery disease (CAD) in a clinical setting. In addition, the clinical usefulness of delayed enhanced MRI has recently been reported. The objectives of this study were to investigate the accuracy of dipyridamole stress first-pass myocardial perfusion MRI for diagnosing CAD (> 50% stenosis) and to clarify whether additional delayed enhancement MRI has any clinical significance. We performed first-pass myocardial perfusion MRI in 102 consecutive patients (66±9 years old) suspected to have CAD or new lesions in patients with well-documented prior myocardial infarction (MI). Using a 1.5 T cardiac MR imager (GE CV/i), eight short axis MR images of the left ventricle were acquired by injecting gadolinium (0.1 mmol/kg) under dipyridamole infusion stress (0.56 mg/kg). Fifteen minutes later, aminophylline (250 mg) was injected and first-pass perfusion MRI was repeated in the resting state in order to evaluate both the presence of perfusion defect and delayed enhancement. The presence of perfusion defect and delayed enhancement was determined based on a visual qualitative analysis by the agreement of two separate readers who were blinded to any clinical information. Based on the stress and rest findings, no defect, reversible defect, or fixed defect with or without delayed enhancement was recorded in any patient. The MR findings revealed 76 CAD patients, including 24 MI patients with new lesions and 26 patients without CAD on coronary angiography. The presence of stress perfusion defect had a 93% sensitivity and an 85% specificity for diagnosing CAD. A fixed defect showed an 86% sensitivity and a 66% specificity for diagnosing a prior MI. Patients with a fixed defect with delayed enhancement had more significant stenosis in the infarct related artery than in those without any enhancement (11/26 vs 15/20, P

2004-01-01

 
 
 
 
281

Remote detection of trace effluents using Resonance Raman spectroscopy: Field results and evaluation  

Energy Technology Data Exchange (ETDEWEB)

Resonance Raman spectroscopy (RRS) possesses many characteristics that are important for detecting, identifying and monitoring chemical effluents. Raman scattering is a coherent, inelastic, two-photon scattering process where an exciting photon of energy h{nu} promotes a molecule to a virtual level and the subsequently emitted photon is shifted in frequency in accordance with the rotational-vibrational structure of the irradiated species, thereby providing a unique fingerprint of the molecule. Under resonance enhancement, the Raman scattering cross-sections have been observed to increase up to 6 orders of magnitude above the normal scattering cross-sections, thereby providing the practical basis for a remote chemical sensor. Some of the other advantages that a Raman sensor possesses are: (1) very high selectivity (chemical specific fingerprints), (2) independence of the spectral fingerprint on the excitation wavelength (ability to monitor in the solar blind region), (3) chemical mixture fingerprints are the sum of its individual components (no spectral cross-talk), (4) near independence of the Raman fingerprint to its physical state (very similar spectra for gas, liquid, solid or solutions), (5) no absolute calibration is necessary because all Raman signals observed from a given species can be compared with the Raman signal for N{sub 2}, whose concentration is known very accurately, and (6) insensitivity of the Raman signature to environmental conditions (no quenching, or interference from water vapor). In this presentation, the technology of resonance Raman spectroscopy as applied to the detection of narcotics production activities will be presented along with some recent experimental results.

Sedlacek, A.J.; Chen, C.L.

1995-10-01

282

IMAGE PROCESSING AND REMOTE SENSING – A LULC CHANGE DETECTION USING REMOTELY SENSED DATA FOR COIMBATORE DISTRICT, INDIA  

Directory of Open Access Journals (Sweden)

Full Text Available Land Use is clearly constrained by environmental factors like soil characteristics, climatic conditions, water sources and vegetation. Changes in Land Use and Land Cover is a dynamic process taking place on the earth surface, and the spatial distribution of the changes that have taken place over a period of time and space is of immense importance in many natural studies. Whether regional or local in scope, remote sensing offers a means of acquiring and presenting land cover data in timely manner. The environmental factors reflect the importance of land as a key and finite resource for most human activities including agriculture, industry, forestry, energy production, settlement, recreation and water sources and storage.Often improper land use is causing various forms of environmental humiliation. For sustainable utilization of the land ecosystems, it is essential to know the natural characteristics, extent and location, its quality, productivity, suitability and limitations of various land uses. Land use is a product of interactions between a society’s cultural background, state and itsphysical needs on the one hand, and the natural potential of land on the other. In order to improve the economic condition of the area without further deteriorating the bio environment, every bit of the available land has to be used in the most rational way. This requires the present and the past land use/land cover data of the Coimbatore district.Land use / Land cover change has become an important component in current strategies for managing natural resources and monitoring environmental changes. The advancement in the concept of vegetation of the spread and health of the world’s forest, grassland and agricultural resources has become an important priority. Viewing the earth from space is now crucial to the understanding of the influence of man’s activities on his natural resource base over time. Over past years, data fromEarth sensing satellites (digital imagery) has become vital in mapping the Earth’s features and infrastructures, managing natural resources and studying environmental change.

Dr.K. Thanushkodi, Y. Baby Kalpana, M. Sharrath

2012-01-01

283

Prostate cancer detection at repeat biopsy: can pelvic phased-array multiparametric MRI replace saturation biopsy?  

UK PubMed Central (United Kingdom)

AIM: Magnetic resonance imaging (MRI) accuracy in prostate cancer (PCa) diagnosis in men submitted to saturation prostate biopsy (SPBx) was evaluated. MATERIALS AND METHODS: From June 2011 to December 2012, 78 patients (median 63 years) underwent repeat SPBx (median 28 cores). Multiparametric MRI using a 3 Tesla pelvic phased-array coil was performed before SPBx and lesions suspicious for PCa were submitted to additional targeted biopsies. RESULTS: A T1c PCa was found in 32 (41%) cases. SPBx vs. MRI-suspicious targeted biopsy diagnosed 28 (87.5%) vs. 26 (81.2%) PCa missing four (12.5%) and six (18.8%) cancers localized in the anterior zone and in the lateral margin of the prostate, respectively; moreover, MRI diameter lesions correlated with PCa diagnosis and Gleason score (p<0.05). CONCLUSION: Multiparametric MRI improved SPBx accuracy in diagnosing PCa of the anterior zone; moreover, suspicious areas >10 mm resulted as highly predictive of cancer (about 70% of the cases).

Pepe P; Garufi A; Priolo G; Candiano G; Pietropaolo F; Pennisi M; Fraggetta F; Aragona F

2013-03-01

284

An approach for computer-aided detection of brain metastases in post-Gd T1-W MRI.  

UK PubMed Central (United Kingdom)

PURPOSE: To develop an approach for computer-aided detection (CAD) of small brain metastases in post-Gd T1-weighted magnetic resonance imaging (MRI). METHOD: A set of unevenly spaced 3D spherical shell templates was optimized to localize brain metastatic lesions by cross-correlation analysis with MRI. Theoretical and simulation analyses of effects of lesion size and shape heterogeneity were performed to optimize the number and size of the templates and the cross-correlation thresholds. Also, effects of image factors of noise and intensity variation on the performance of the CAD system were investigated. A nodule enhancement strategy to improve sensitivity of the system and a set of criteria based upon the size, shape and brightness of lesions were used to reduce false positives. An optimal set of parameters from the FROC curves was selected from a training dataset, and then the system was evaluated on a testing dataset including 186 lesions from 2753 MRI slices. Reading results from two radiologists are also included. RESULTS: Overall, a 93.5% sensitivity with 0.024 of intra-cranial false positive rate (IC-FPR) was achieved in the testing dataset. Our investigation indicated that nodule enhancement was very effective in improving both sensitivity and specificity. The size and shape criteria reduced the IC-FPR from 0.075 to 0.021, and the brightness criterion decreases the extra-cranial FPR from 0.477 to 0.083 in the training dataset. Readings from the two radiologists had sensitivities of 60% and 67% in the training dataset and 70% and 80% in the testing dataset for the metastatic lesions <5 mm in diameter. CONCLUSION: Our proposed CAD system has high sensitivity and fairly low FPR for detection of the small brain metastatic lesions in MRI compared to the previous work and readings of neuroradiologists. The potential of this method for assisting clinical decision- making warrants further evaluation and improvements.

Farjam R; Parmar HA; Noll DC; Tsien CI; Cao Y

2012-07-01

285

A remote oil spill detection system for early warning of spills at waterfront or land-based facilities  

International Nuclear Information System (INIS)

Early detection of spills during loading/unloading of crude oil or products at terminals or plants is essential for quickly stopping the spill and minimizing its impact. Such detection is particularly difficult at night or in remote areas. In order to provide a reliable and inexpensive spill detection system for such an application, a joint development process was undertaken to redesign an oil spill detection buoy system which had been successfully tested in the 1970s. The sensor's operation is based on the stimulated fluorescence of oil and selective wavelength detection of this fluorescence. The prototype system consists of a flotation buoy for remote deployment of the sensor, rechargeable battery supply, a land-based computer base station, and radio signal transmitter. The oil spill detection buoy was modified in 1991 and tested in the laboratory. Field trials are under way and tests to date have confirmed the unit's ability to detect oil and to differentiate between various types of oil and/or products, particularly if the software is alerted to the type of product being transferred. 2 figs.

1992-01-01

286

Prognostic value of unrecognised myocardial infarction detected by late gadolinium-enhanced MRI in diabetic patients with normal global and regional left ventricular systolic function.  

UK PubMed Central (United Kingdom)

OBJECTIVES: To determine whether the detection of unrecognised myocardial infarction (MI) using late gadolinium-enhanced (LGE)-magnetic resonance imaging (MRI) can provide prognostic information in diabetic patients with normal ECG as well as normal global and regional left ventricular (LV) function. METHODS: From 449 diabetic patients who had complete cine- and LGE-MRI, 321 patients with histories of CAD, ischaemic ECG changes and abnormal cine MRI findings (LV ejection fraction <50 % or presence of regional wall motion abnormality) were excluded. The presence and extent of LGE were determined in the remaining 128 patients. Follow-up information was obtained for the occurrence of major adverse cardiovascular events (MACE) defined as cardiac death, acute MI, heart failure, unstable angina and significant ventricular arrhythmias in 120 patients. RESULTS: Of 120 patients, 18 (15 %) had LGE. During follow-up (median, 27 months), six patients with LGE (33.3 %) and four patients without LGE (3.9 %) experienced MACE, resulting in an annualised event rate of 7.7 % and 0.9 %, respectively (log-rank P <0.001). The presence of LGE was associated with an eight-fold increased hazard for MACE (HR, 8.84; P?=?0.001). CONCLUSIONS: LGE-MRI can detect unrecognised MI and may improve the risk stratification of diabetic patients with no CAD history, normal ECG and normal LV systolic function. KEY POINTS: • Late gadolinium-enhanced magnetic resonance imaging (LGE-MRI) can identify subtle myocardial abnormalities. • LGE-MRI can detect myocardial infarction missed by ECG and cine-MRI. • Unrecognised MI detected by LGE-MRI was associated with adverse cardiac events. • LGE-MRI helps clinicians to assess diabetic patients with unrecognised MI.

Yoon YE; Kitagawa K; Kato S; Nakajima H; Kurita T; Dohi K; Ito M; Sakuma H

2013-08-01

287

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

288

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

Science.gov (United States)

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; Tsunaki, Shingo; Yamamoto, Masaaki; Abe, Takayuki; Hatta, Junichi; Tanaka, Saburo

2013-11-01

289

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

2004-08-09

290

Mountain permafrost detection inferred by a combined remote sensing, geomorphological and geophysical approach  

Science.gov (United States)

The detection of permafrost in high altitude regions of the Alps is an important aim of alpine studies. Geophysical research in this field is important for alpine risk, infrastructure and climate change studies. Because of the complexity of detecting ground ice, the database of permafrost maps is currently not very well evaluated for wide areas of the Alps. The research for this study was conducted at Rofenberg (Ötztal, Austria), a typical high alpine environment in mid-latitudes, which ranges between 2800 and 3229 m a.s.l.. Areas that were not covered by Little Ice Age (LIA) glaciers have been exposed to permafrost friendly conditions. These areas are well suited for investigations aiming at the detection of permafrost evidence with a combination of methods. Geomorphological observations, geophysical measurements, like ground penetrating radar (GPR), geoelectrical soundings and refraction seismic, and airborne lasercanning (ALS) based measurements of surface changes on the study site were used to obtain an integrative analysis of possible permafrost distribution. At several small areas near the mountain ridge of the "Rofenbergköpfe" south of the glacier tongue of Hintereisferner, a small but continuous lowering of the surface was detected throughout the whole data series of 20 ALS flights. The surface changes are assumed to originate from the melting of permafrost or small dead-ice bodies. To verify this assumption, several measurements have been conducted. As electrical resistivity tomography, GPR and refraction seismic are considered as important multifunctional geophysical methods for research in periglacial and permafrost related environments, these methods were applied to detect permafrost in the areas with significant surface changes. Therefore two geophysical measurement campaigns were carried out at the "Rofenbergköpfe". The parallel application enables a comparison and cross-validation of the results gained by the three techniques. After the analyses of the single datasets, a tomography including all results was created. For a further investigation of the occurrence and distribution of permafrost, 15 temperature-loggers were installed, which measured the base temperature of the snowpack (BTS) during the whole winter and so recorded potential freezing and thawing of the ground. This offered a further possibility for validation of the geophysical measurements. Additionally, the BTS was measured two times in the area close to the end of the winter snow accumulation period, to get a general idea of the possible distribution of permafrost or ice in the underground. The results of the measurements at Rofenberg show good correlation. In the areas detected within the multitemporal ALS dataset permafrost is assumed at a depth between 2 meters and 8 meters and similar ground structures can be spotted for every geophysical method. The combined approach of geophysical methods, remote sensing and field investigations allowed a profound cross-validation of the different methods.

Klug, Christoph; Mössinger, Max; Ott, Patrick; Rieg, Lorenzo; Sailer, Rudolf; Sass, Oliver; Stötter, Johann

2013-04-01

291

Far-ultraviolet imaging spectrograph and scanning grating spectrometers for the Remote Atmospheric and Ionospheric Detection System  

Science.gov (United States)

The Remote Atmospheric and Ionospheric Detection System (RAIDS) experiment is an optical remote sensing platform consisting of eight sensors, (spectrographs, spectrometers, and photometers) covering the wavelength range 550 to 8744 angstroms. RAIDS employs a mechanical scan platform to view the Earth's limb and measure line-of-sight column emission from tangent altitudes from 50 to 750 km. These measurements provide vertical profiles of atmospheric dayglow and nightglow from the mesosphere to the upper regions of the F-region ionosphere. RAIDS will be flown on the National Oceanographic and Atmospheric Administration (NOAA) J weather satellite through the auspices of the U.S. Air Force Space Test Program. The RAIDS wavelength and altitude coverage allows remote sensing of the major and many minor constituents in the thermosphere and ionosphere. These measurements will be used as part of a proof of concept for remote sensing of ionospheric and neutral density profiles. The RAIDS database will be used to study composition, thermal structure, and couplings between the mesosphere, thermosphere, and ionosphere. RAIDS is a joint venture of the Naval Research Laboratory (NRL) and The Aerospace Corporation. We describe the subset of RAIDS instruments developed at NRL covering the far to near UV regions (1300 to 4000 angstroms).

McCoy, Robert P.; Meier, Robert R.; Wolfram, Kenneth D.; Picone, J. M.; Thonnard, Stefan E.; Fritz, Gilbert G.; Morrill, Jeff S.; Hardin, David A.; Christensen, Andrew B.; Kayser, David C.; Pranke, James B.; Straus, Paul R.

1994-02-01

292

Far-ultraviolet imaging spectrograph and scanning grating spectrometers for the Remote Atmospheric and Ionospheric Detection System  

International Nuclear Information System (INIS)

The Remote Atmospheric and Ionospheric Detection System (RAIDS) experiment is an optical remote sensing platform consisting of eight sensors, (spectrographs, spectrometers, and photometers) covering the wavelength range 550 to 8744 angstrom. RAIDS employs a mechanical scan platform to view the Earth's limb and measure line-of-sight column emission from tangent altitudes from 50 to 750 km. These measurements provide vertical profiles of atmospheric dayglow and nightglow from the mesosphere to the upper regions of the F-region ionosphere. RAIDS will be flown on the National Oceanographic and Atmospheric Administration (NOAA) J weather satellite through the auspices of the US Air Force Space Test Program. The RAIDS wavelength and altitude coverage allows remote sensing of the major and many minor constituents in the thermosphere and ionosphere. These measurements will be used as part of a proof of concept for remote sensing of ionospheric and neutral density profiles. The RAIDS database will be used to study composition, thermal structure, and couplings between the mesosphere, thermosphere, thermal structure, and couplings between the mesosphere, thermosphere, and ionosphere. RAIDS is a joint venture of the Naval Research Laboratory (NRL) and the Aerospace Corporation. The authors describe the subset of RAIDS instruments developed at NRL covering the far to near UV regions (1,300 to 4,000 angstrom)

1994-01-01

293

Far-ultraviolet imaging spectrograph and scanning grating spectrometers for the Remote Atmospheric and Ionospheric Detection System  

Energy Technology Data Exchange (ETDEWEB)

The Remote Atmospheric and Ionospheric Detection System (RAIDS) experiment is an optical remote sensing platform consisting of eight sensors, (spectrographs, spectrometers, and photometers) covering the wavelength range 550 to 8744 [angstrom]. RAIDS employs a mechanical scan platform to view the Earth's limb and measure line-of-sight column emission from tangent altitudes from 50 to 750 km. These measurements provide vertical profiles of atmospheric dayglow and nightglow from the mesosphere to the upper regions of the F-region ionosphere. RAIDS will be flown on the National Oceanographic and Atmospheric Administration (NOAA) J weather satellite through the auspices of the US Air Force Space Test Program. The RAIDS wavelength and altitude coverage allows remote sensing of the major and many minor constituents in the thermosphere and ionosphere. These measurements will be used as part of a proof of concept for remote sensing of ionospheric and neutral density profiles. The RAIDS database will be used to study composition, thermal structure, and couplings between the mesosphere, thermosphere, thermal structure, and couplings between the mesosphere, thermosphere, and ionosphere. RAIDS is a joint venture of the Naval Research Laboratory (NRL) and the Aerospace Corporation. The authors describe the subset of RAIDS instruments developed at NRL covering the far to near UV regions (1,300 to 4,000 [angstrom]).

McCoy, R.P.; Meier, R.R.; Wolfram, K.D.; Picone, J.M.; Thonnard, S.E.; Fritz, G.G.; Morrill, J.S. (Naval Research Lab., Washington, DC (United States). E.O. Hulburt Center for Space Research); Hardin, D.A. (Computational Physics Inc., Annandale, VA (United States)); Christensen, A.B.; Kayser, D.C.; Pranke, J.B.; Straus, P.R. (Aerospace Corp., Los Angeles, CA (United States). Space and Environment Technology Center)

1994-02-01

294

Remote detection of anomalous mineralogy associated with hydrocarbon production, Lisbon Valley, Utah  

Energy Technology Data Exchange (ETDEWEB)

Examination of a variety of remotely sensed data and geochemistry suggest that specific diagenetic mineral assemblages within the Wingate Formation are closely associated with hydrocarbon production at Lisbon Valley, Utah. The Wingate Formation, exposed along the southwestern flank of the anticline has a relatively uniform composition and appearance over the entire Colorado Plateau, except at isolated localities such as Lisbon Valley, where it is locally bleached. Previous workers have suggested that hydrocarbon microseepage may account for the bleaching of the Wingate Sandstone and the presence of uranium mineralization in rocks overlying the reservoir at Lisbon Valley. Broad-band Landsat Multispectral Scanner (MSS) and airborne Thematic Mapper Simulator (TMS) data were used to map the bleached facies on the basis of brightness and lack of ferric iron. The TMS data provided further discrimination of bleached facies based on the relative abundances of clay minerals detectable with this sensor. Analysis of high-resolution airborne spectroradiometric data, thin sections, and x-ray diffraction data suggests that bleached rocks overlying the reservoir at Lisbon Valley contain abundant kaolinite and minor amounts of feldspar. Unbleached exposures contain substantially less clay and abundant feldspar. This study shows a correlation between the abundance of clay minerals, particularly kaolinite, and hydrocarbon production at Lisbon Valley. Because on the principal mineralogical differences between the bleached and unbleached rocks is the relative abundance of clay minerals, and the TMS (and Landsat Thematic Mapper) data are very sensitive to clays, areas of potential hydrocarbon induced diagenetic alteration may be mapped using broad-band sensors.

Segal, D.B.; Ruth, M.D.; Merin, I.S.

1986-04-01

295

[The role of diffusion 3-Tesla MRI in detecting prostate cancer before needle biopsy: multiparametric study of 111 patients].  

UK PubMed Central (United Kingdom)

AIM: Evaluate diffusion MRI in the multiparametric assessment of prostate cancer before needle biopsy. MATERIALS AND METHODS: One hundred eleven patients with suspected prostate cancer (mean age: 63 years old, median PSA: 7 ng/mL) were examined before undergoing needle biopsy (59 patients with a history of a negative biopsy and 52 without a history of biopsy). A diffusion sequence type SS SE-EPI (TR/TE: 5357/58, fEPI: 73, b 0 and 1000 s/mm², axial) with a qualitative analysis of the ADC map was performed in addition to T2 and T1 gadolinium enhanced sequences on 3 T MRI with an endorectal coil. The histological correlations were obtained by ultrasound guided needle biopsy (85 patients) or radical prostatectomy (26 patients). RESULTS: The correlation of the results of the diffusion sequence in the series of the 111 patients and the biopsies of the entire prostate or the hemiprostate had a sensitivity of: 92%, 77%; a specificity of: 55%, 70%; a positive predictive value of: 77%, 62%; a negative predictive value of: 84%, 80% and an efficacy of 78%, 75% respectively. The agreement of the three sequences had a specificity of 84.3%. CONCLUSION: The sensitivity of diffusion MRI is high for the detection of cancer of the prostate. Specificity of sequences is good. The results of simple visual assessment of the ADC map are good.

Roy C; Pasquali R; Matau A; Bazille G; Lang H

2010-11-01

296

Automated detection of brain atrophy patterns based on MRI for the prediction of Alzheimer's disease  

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Subjects with mild cognitive impairment (MCI) have an increased risk to develop Alzheimer’s disease (AD). Voxel-based MRI studies have demonstrated that widely distributed cortical and subcortical brain areas show atrophic changes in MCI, preceding the onset of AD. Here we developed a novel data min...

HAMPEL, HARALD; BOKDE, ARUN LAWRENCE WARREN

297

Diagnostic value of MRI for detection and differential diagnostic evaluation of focal liver lesions. Wertigkeit der Magnetresonanztomographie in der Detektion und Differentialdiagnose fokaler Leberlaesionen  

Energy Technology Data Exchange (ETDEWEB)

Magnetic resonance imaging (MRI) of the liver has made considerable progress due to improvements in the examination technique. Sensitivity for the detection of focal liver lesions is higher for MRI than for CT. In the differential diagnosis of liver tumors MRI is remarkably accurate. This is particularly true for hemangiomas, liver cell carcinomas and focal nodular hyperplasias. From a clinical view point differentiation between hemangiomas and metastases is of utmost importance. Future improvements in MR diagnosis of liver diseases are expected due to fast imaging techniques and liver-specific contrast agents. (orig.).

Hamm, B. (Klinikum Steglitz, Berlin (Germany). Radiologische Klinik)

1992-05-01

298

Integrated microchip incorporating atomic magnetometer and microfluidic channel for NMR and MRI  

Energy Technology Data Exchange (ETDEWEB)

An integral microfluidic device includes an alkali vapor cell and microfluidic channel, which can be used to detect magnetism for nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI). Small magnetic fields in the vicinity of the vapor cell can be measured by optically polarizing and probing the spin precession in the small magnetic field. This can then be used to detect the magnetic field of in encoded analyte in the adjacent microfluidic channel. The magnetism in the microfluidic channel can be modulated by applying an appropriate series of radio or audio frequency pulses upstream from the microfluidic chip (the remote detection modality) to yield a sensitive means of detecting NMR and MRI.

Ledbetter, Micah P. (Oakland, CA); Savukov, Igor M. (Los Alamos, NM); Budker, Dmitry (El Cerrito, CA); Shah, Vishal K. (Plainsboro, NJ); Knappe, Svenja (Boulder, CO); Kitching, John (Boulder, CO); Michalak, David J. (Berkeley, CA); Xu, Shoujun (Houston, TX); Pines, Alexander (Berkeley, CA)

2011-08-09

299

Utilization of combined remote sensing techniques to detect environmental variables influencing malaria vector densities in rural West Africa  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Introduction The use of remote sensing has found its way into the field of epidemiology within the last decades. With the increased sensor resolution of recent and future satellites new possibilities emerge for high resolution risk modeling and risk mapping. Methods A SPOT 5 satellite image, taken during the rainy season 2009 was used for calculating indices by combining the image's spectral bands. Besides the widely used Normalized Difference Vegetation Index (NDVI) other indices were tested for significant correlation against field observations. Multiple steps, including the detection of surface water, its breeding appropriateness for Anopheles and modeling of vector imagines abundance, were performed. Data collection on larvae, adult vectors and geographic parameters in the field, was amended by using remote sensing techniques to gather data on altitude (Digital Elevation Model = DEM), precipitation (Tropical Rainfall Measurement Mission = TRMM), land surface temperatures (LST). Results The DEM derived altitude as well as indices calculations combining the satellite's spectral bands (NDTI = Normalized Difference Turbidity Index, NDWI Mac Feeters = Normalized Difference Water Index) turned out to be reliable indicators for surface water in the local geographic setting. While Anopheles larvae abundance in habitats is driven by multiple, interconnected factors - amongst which the NDVI - and precipitation events, the presence of vector imagines was found to be correlated negatively to remotely sensed LST and positively to the cumulated amount of rainfall in the preceding 15 days and to the Normalized Difference Pond Index (NDPI) within the 500 m buffer zone around capture points. Conclusions Remotely sensed geographical and meteorological factors, including precipitations, temperature, as well as vegetation, humidity and land cover indicators could be used as explanatory variables for surface water presence, larval development and imagines densities. This modeling approach based on remotely sensed information is potentially useful for counter measures that are putting on at the environmental side, namely vector larvae control via larviciding and water body reforming.

Dambach Peter; Machault Vanessa; Lacaux Jean-Pierre; Vignolles Cécile; Sié Ali; Sauerborn Rainer

2012-01-01

300

Remote sensing detection of atmospheric pollutants using lidar, sodar and correlation with air quality data in an industrial area  

Science.gov (United States)

Optical remote sensing techniques have obvious advantages for monitoring gas and aerosol emissions, since they enable the operation over large distances, far from hostile environments, and fast processing of the measured signal. In this study two remote sensing devices, namely a Lidar (Light Detection and Ranging) for monitoring the vertical profile of backscattered light intensity, and a Sodar (Acoustic Radar, Sound Detection and Ranging) for monitoring the vertical profile of the wind vector were operated during specific periods. The acquired data were processed and compared with data of air quality obtained from ground level monitoring stations, in order to verify the possibility of using the remote sensing techniques to monitor industrial emissions. The campaigns were carried out in the area of the Environmental Research Center (Cepema) of the University of Sao Paulo, in the city of Cubatao, Brazil, a large industrial site, where numerous different industries are located, including an oil refinery, a steel plant, as well as fertilizer, cement and chemical/petrochemical plants. The local environmental problems caused by the industrial activities are aggravated by the climate and topography of the site, unfavorable to pollutant dispersion. Results of a campaign are presented for a 24- hour period, showing data of a Lidar, an air quality monitoring station and a Sodar.

Steffens, Juliana; da Costa, Renata F.; Landulfo, Eduardo; Guardani, Roberto; Moreira, Paulo F., Jr.; Held, Gerhard

2011-10-01

 
 
 
 
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  

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

2009-01-01

302

Breast inflammation: indications for MRI and PET-CT.  

UK PubMed Central (United Kingdom)

Breast MRI should not be used for differential diagnosis between inflammatory breast cancer and acute mastitis (AM) prior to treatment. When mastitis symptoms persist after 10 to 15 days of well-managed medical treatment, MRI may be performed in addition to an ultrasound examination, a mammogram and to taking histological samples, in order to eliminate inflammatory breast cancer (IBC). For staging, MRI would seem to be useful in looking for a contralateral lesion, PET-CT for finding information about remote metastases and in certain centres, for information about the initial extension to local/regional lymph nodes, which would guide the fields of irradiation (since patients can become lymph node negative after neoadjuvant chemotherapy). MRI and PET-CT seems to be useful for early detection of patients responding poorly to neoadjuvant chemotherapy so that the latter may be rapidly modified.

de Bazelaire C; Groheux D; Chapellier M; Sabatier F; Scémama A; Pluvinage A; Albiter M; de Kerviler E

2012-02-01

303

Breast inflammation: indications for MRI and PET-CT.  

Science.gov (United States)

Breast MRI should not be used for differential diagnosis between inflammatory breast cancer and acute mastitis (AM) prior to treatment. When mastitis symptoms persist after 10 to 15 days of well-managed medical treatment, MRI may be performed in addition to an ultrasound examination, a mammogram and to taking histological samples, in order to eliminate inflammatory breast cancer (IBC). For staging, MRI would seem to be useful in looking for a contralateral lesion, PET-CT for finding information about remote metastases and in certain centres, for information about the initial extension to local/regional lymph nodes, which would guide the fields of irradiation (since patients can become lymph node negative after neoadjuvant chemotherapy). MRI and PET-CT seems to be useful for early detection of patients responding poorly to neoadjuvant chemotherapy so that the latter may be rapidly modified. PMID:22305594

de Bazelaire, C; Groheux, D; Chapellier, M; Sabatier, F; Scémama, A; Pluvinage, A; Albiter, M; de Kerviler, E

2012-01-21

304

Detection and localization of pulmonary air leaks using laser-polarized (3)He MRI.  

Science.gov (United States)

Pulmonary air leaks were created in the lungs of Yorkshire pigs. Dynamic, 3D MRI of laser-polarized (3)He gas was then performed using a gradient-echo pulse sequence. Coronal magnitude images of the helium distribution were acquired during gas inhalation with a voxel resolution of approximately 1.2 x 2.5 x 8 mm, and a time resolution of 5 sec. In each animal, the ventilation images reveal focal high-signal intensity within the pleural cavity at the site of the air leaks. In addition, a wedge-shaped region of increased parenchymal signal intensity was observed adjacent to the site of the air leak in one animal. (3)He MRI may prove helpful in the management of patients with pulmonary air leaks. PMID:10975888

Roberts, D A; Rizi, R R; Lipson, D A; Aranda, M; Baumgardner, J; Bearn, L; Hansen-Flaschen, J; Gefter, W B; Hatabu, H H; Leigh, J S; Schnall, M D

2000-09-01

305

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

306

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

International Nuclear Information System (INIS)

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.)

2010-01-01

307

Hybrid multidimensional T2 and diffusion-weighted MRI for prostate cancer detection.  

UK PubMed Central (United Kingdom)

PURPOSE: To study the dependence of apparent diffusion coefficient (ADC) and T2 on echo time (TE) and b-value, respectively, in normal prostate and prostate cancer, using two-dimensional MRI sampling, referred to as "hybrid multidimensional imaging." MATERIALS AND METHODS: The study included 10 patients with biopsy-proven prostate cancer who underwent 3 Tesla prostate MRI. Diffusion-weighted MRI (DWI) data were acquired at b?=?0, 750, and 1500 s/mm(2) . For each b-value, data were acquired at TEs of 47, 75, and 100 ms. ADC and T2 were measured as a function of b-value and TE, respectively, in 15 cancer and 10 normal regions of interest (ROIs). The Friedman test was used to test the significance of changes in ADC as a function of TE and of T2 as a function of b-value. RESULTS: In normal prostate ROIs, the ADC at TE of 47 ms is significantly smaller than ADC at TE of 100 ms (P?=?0.0003) and T2 at b-value of 0 s/mm(2) is significantly longer than T2 at b-value of 1500 s/mm(2) (P?=?0.001). In cancer ROIs, average ADC and T2 values do not change as a function of TE and b-value, respectively. However, in many cancer pixels, there are large decreases in the ADC as a function of TE and large increases in T2 as a function of b-value. Cancers are more conspicuous in ADC maps at longer TEs. CONCLUSION: Parameters derived from hybrid imaging that depend on coupled/associated values of ADC and T2 may improve the accuracy of MRI in diagnosing prostate cancer. J. Magn. Reson. Imaging 2013. © 2013 Wiley Periodicals, Inc.

Wang S; Peng Y; Medved M; Yousuf AN; Ivancevic MK; Karademir I; Jiang Y; Antic T; Sammet S; Oto A; Karczmar GS

2013-08-01

308

Ship-based detection of glyoxal over the remote tropical Pacific Ocean  

Directory of Open Access Journals (Sweden)

Full Text Available We present the first detection of glyoxal (CHOCHO) over the remote tropical Pacific Ocean in the Marine Boundary Layer (MBL). The measurements were conducted by means of the University of Colorado Ship Multi-Axis Differential Optical Absorption Spectroscopy (CU SMAX-DOAS) instrument aboard the research vessel Ronald H. Brown. The research vessel was on a cruise in the framework of the VAMOS Ocean-Cloud-Atmosphere-Land Study – Regional Experiment (VOCALS-REx) and the Tropical Atmosphere Ocean (TAO) projects lasting from October 2008 through January 2009 (74 days at sea). The CU SMAX-DOAS instrument features a motion compensation system to characterize the pitch and roll of the ship and to compensate for ship movements in real time. We found elevated mixing ratios of up to 140 ppt CHOCHO located inside the MBL up to 3000 km from the continental coast over biologically active upwelling regions of the tropical Eastern Pacific Ocean. This is surprising since CHOCHO is very short lived (atmospheric life time ~2 h) and highly water soluble (Henry's Law constant H = 4.2 × 105 M/atm). This CHOCHO cannot be explained by transport of it or its precursors from continental sources. Rather, the open ocean must be a source for CHOCHO to the atmosphere. Dissolved Organic Matter (DOM) photochemistry in surface waters is a source for Volatile Organic Compounds (VOCs) to the atmosphere, e.g. acetaldehyde. The extension of this mechanism to very soluble gases, like CHOCHO, is not straightforward since the air-sea flux is directed from the atmosphere into the ocean. For CHOCHO, the dissolved concentrations would need to be extremely high in order to explain our gas-phase observations by this mechanism (40–70 ?M CHOCHO, compared to ~0.01 ?M acetaldehyde and 60–70 ?M DOM). Further, while there is as yet no direct measurement of VOCs in our study area, measurements of the CHOCHO precursors isoprene, and/or acetylene over phytoplankton bloom areas in other parts of the oceans are too low (by a factor of 10–100) to explain the observed CHOCHO amounts. We conclude that our CHOCHO data cannot be explained by currently understood processes. Yet, it supports first global source estimates of 20 Tg/year CHOCHO from the oceans, which likely is a significant source of secondary organic aerosol (SOA). This chemistry is currently not considered by atmospheric models.

R. Sinreich; S. Coburn; B. Dix; R. Volkamer

2010-01-01

309

Ship-based detection of glyoxal over the remote tropical Pacific Ocean  

Directory of Open Access Journals (Sweden)

Full Text Available We present the first detection of glyoxal (CHOCHO) over the remote tropical Pacific Ocean in the Marine Boundary Layer (MBL). The measurements were conducted by means of the University of Colorado Ship Multi-Axis Differential Optical Spectroscopy (CU SMAX-DOAS) instrument aboard the research vessel Ronald H. Brown. The research vessel was on a cruise in the framework of the VAMOS Ocean-Cloud-Atmosphere-Land Study – Regional Experiment (VOCALS-REx) and the Tropical Atmosphere Ocean (TAO) projects lasting from October 2008 through January 2009 (74 days at sea). The CU SMAX-DOAS instrument features a motion compensation system to characterize the pitch and roll of the ship and to compensate for ship movements in real time. We found elevated mixing ratios of up to 170 ppt CHOCHO located inside the MBL up to 3000 km from the continental coast over biologically active upwelling regions of the tropical Eastern Pacific Ocean. This is surprising since CHOCHO is very short lived (atmospheric life time ~2 h) and highly water soluble (Henry's Law constant H=4.2×105 M/atm). This CHOCHO cannot be explained by transport of it or its precursors from continental sources. Rather, the open ocean is a source for CHOCHO to the atmosphere. Dissolved Organic Matter (DOM) photochemistry in surface waters is a source for Volatile Organic Compounds (VOCs) to the atmosphere, e.g. acetaldehyde. The extension of this mechanism to very soluble gases, like CHOCHO, is not straightforward since the air-sea flux is directed from the atmosphere into the ocean. For CHOCHO, the dissolved concentrations would need to be extremely high in order to explain our gas-phase observations by this mechanism (40–70 ?M CHOCHO, compared to ~0.01 ?M acetaldehyde and 60–70 ?M DOM). Further, while there is as yet no direct measurement of VOCs in our study area, measurements of the CHOCHO precursors isoprene, and/or acetylene over phytoplankton bloom areas in other parts of the oceans are too low (by a factor of 10–100) to explain the observed CHOCHO amounts. We conclude that our CHOCHO data cannot be explained by currently understood processes. Yet, it supports first global source estimates of 20 Tg/year CHOCHO from the oceans, which likely is a significant source of secondary organic aerosol (SOA). This chemistry is currently not considered by atmospheric models.

R. Sinreich; S. Coburn; B. Dix; R. Volkamer

2010-01-01

310

Remote Detection of Marine Microbes, Small Invertebrates, Harmful Algae, and Biotoxins using the Environmental Sample Processor (ESP)  

Directory of Open Access Journals (Sweden)

Full Text Available The advent of ocean observatories is creating unique opportunities for deploying novel sensor systems. We are exploring that potential through the development and application of the Environmental Sample Processor (ESP). ESP is an electromechanical/fluidic system designed to collect discrete water samples, concentrate microorganisms, and automate application of molecular probe technologies. Development and application of ESP grew from extensive partnerships galvanized by the National Oceanographic Partnership Program. Near-real-time observations are currently achieved using low-density DNA probe and protein arrays. Filter-based sandwich hybridization methodology enables direct detection of ribosomal RNA sequences diagnostic for groups of bacteria and archaea, as well as a variety of invertebrates and harmful algal species. An antibody-based technique is used for detecting domoic acid, an algal biotoxin. To date, ESP has been deployed in ocean waters from the near surface to 1000 m. Shallow-water deployments demonstrated application of all four types of assays in single deployments lasting up to 30 days and provided the first remote detection of such phylogenetically diverse organisms and metabolites on one platform. Deep-water applications focused on detection of invertebrates associated with whale falls, using remotely operated vehicle-based operations lasting several days. Current work emphasizes incorporating a four-channel, real-time polymerase chain reaction module, extending operations to 4000-m water depth, and increasing deployment duration.

Christopher Scholin; Gregory Doucette; Scott Jensen; Brent Roman; Douglas Pargett; Roman Marin III; Christina Preston; William Jones; Jason Feldman; Cheri Everlove; Adeline Harris; Nilo Alvarado; Eugene Massion; James Birch; Dianne Greenfield; Robert Vrijenhoek; Christina Mikulski; Kelly Jones

2009-01-01

311

Gadolinium-Hematoporphyrin: new potential MRI contrast agent for detection of breast cancer cell line (MCF-7)  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Gadolinium-porphyrins have been synthesized and are currently being investigated as magnetic resonance imaging (MRI) contrast agents. This study aimed to synthesize Gd-hematoporphyrin and applicate it for in vitro detection of breast cancer cell line (MCF-7). Methods: The naturally occurring porphyrin (hematoporphyrin) was inserted with gadolinium (III) nitrate hexahydrate to yield Gd-H. T1 relaxation times and signal enhancement of the contrast agents were presented, and the results were compared. UV spectrophotometer measured the attachment of Gd to the cell membrane of MCF-7. Results: Most of gadolinium chloride (GdCl3) was found in the washing solution, indicate that it didn`t fixed to the breast cell membranes during incubation. Gd-DTPA showed some uptake into the MCF-7 cell membranes with incubation, however, its uptake was significantly lower than Gd-H. Conclusion: Good cell memberan uptake of Gd-porphyrin is comparable to controls, indicating selective delivery it to the breast cell line and considerable potency in diagnostic MR imaging for detection of breast cancer. Key Words: Porphyrin, Contrast agent, MRI, Hematoporphyrin, Breast cancer cell (MCF-7)

D Shahbazi Gahrouei; MB Tavakoli; V Nazari

2005-01-01

312

Use of a remote sensing approach to detect landslide thermal behaviour  

Science.gov (United States)

The type, abundance and distribution of landsides in an area are controlled by the morphological, lithological and land use settings, and by the intensity and frequency of the triggers. Knowing the location and abundance of landslides is important for scientific and societal reasons. Most commonly, geomorphologists map landslides in the field or through the interpretation of stereoscopic aerial photographs. These are expensive and time consuming operations that require experienced personnel. The possibility to detect and map landslides over large area using remote sensing technology will improve the current capability to predict landslides, and to evaluate the susceptibility of an area to slope instability phenomena. In this work, we exploit airborne and space borne optical (thermal) imagery to evaluate the possibility to detect and map landslides. For the experiment, we select the Collazzone study area, that extend for about 80 square kilometers in Umbria, central Italy. For this area, detailed geomorphological information exists, including a multi-temporal landslide inventory map at 1:10,000 scale. We make the hypothesis that a difference in surface temperature exists between landslide and stable areas, due to different soil moisture conditions. We verify the hypothesis at two geographical scales: (i) at the (large) "single landslide" scale, and (ii) at the (small) catchment scale. Both approaches require the measurement of surface temperature at multiple sites, and the production of Land Surface Temperature (LST) maps. For individual landslides, we use images obtained on 3 May 2004 by a Daedalus 1268 Airborne Thematic Mapper (ATM), flown onboard a Dornier 228-110 aircraft operated by the Airborne Research and Survey Facility (ARSF) of the UK National Environment Research Council (NERC). For our catchment scale analysis, we use a L1A satellite image obtained on 3 July 2004 and acquired by ASTER sensor onboard TERRA satellite and a L1G satellite image obtained on 3 August 2001 by ETM+ sensor onboard LANDSAT 7. For our large scale, individual landslide, analysis we perform a pixel by pixel comparison of the surface temperature measurements obtained by processing the ATM data inside individual landslides, and in the immediately surrounding stable areas. For our basin scale analysis, we overlay in a GIS a map of surface temperature, obtained by processing the ASTER and LANDSAT images, on the landslide inventory map. We then compare the statistical distributions of the surface temperature measured in landslide and in stable areas. Preliminary results indicate that the mean and the mode of the distribution of surface temperature in landslide areas are lower than in the stable areas. This is consistent with the observation that in the study area landslides are wetter than stable areas. When studying individual landslides the distinction is less clear, but pixels located inside landslides are, in general, colder (i.e., wetter) than those located in the immediately surrounding stable areas where land cover types are similar.

Mondini, A.; Carlà, R.; Reichenbach, P.; Cardinali, M.; Guzzetti, F.

2009-04-01

313

Repeat Prostate Biopsy Strategies after Initial Negative Biopsy: Meta-Regression Comparing Cancer Detection of Transperineal, Transrectal Saturation and MRI Guided Biopsy  

Science.gov (United States)

Introduction There is no consensus on how to investigate men with negative transrectal ultrasound guided prostate biopsy (TRUS-B) but ongoing suspicion of cancer. Three strategies used are transperineal (TP-B), transrectal saturation (TS-B) and MRI-guided biopsy (MRI-B). We compared cancer yields of these strategies. Methods Papers were identified by search of Pubmed, Embase and Ovid Medline. Included studies investigated biopsy diagnostic yield in men with at least one negative TRUS-B and ongoing suspicion of prostate cancer. Data including age, PSA, number of previous biopsy episodes, number of cores at re-biopsy, cancer yield, and Gleason score of detected cancers were extracted. Meta-regression analyses were used to analyse the data. Results Forty-six studies were included; 12 of TS-B, 14 of TP-B, and 20 of MRI-B, representing 4,657 patients. Mean patient age, PSA and number of previous biopsy episodes were similar between the strategies. The mean number of biopsy cores obtained by TP-B and TS-B were greater than MRI-B. Cancer detection rates were 30·0%, 36·8%, and 37·6% for TS-B, TP-B, and MRI-B respectively. Meta-regression analysis showed that MRI-B had significantly higher cancer detection than TS-B. There were no significant differences however between MRI-B and TP-B, or TP-B and TS-B. In a sensitivity analysis incorporating number of previous biopsy episodes (36 studies) the difference between MRI-B and TP-B was not maintained resulting in no significant difference in cancer detection between the groups. There were no significant differences in median Gleason scores detected comparing the three strategies. Conclusions In the re-biopsy setting, it is unclear which strategy offers the highest cancer detection rate. MRI-B may potentially detect more prostate cancers than other modalities and can achieve this with fewer biopsy cores. However, well–designed prospective studies with standardised outcome measures are needed to accurately compare modalities and define an optimum re-biopsy approach.

Nelson, Adam W.; Harvey, Rebecca C.; Parker, Richard A.; Kastner, Christof; Doble, Andrew; Gnanapragasam, Vincent J.

2013-01-01

314

Repeat prostate biopsy strategies after initial negative biopsy: meta-regression comparing cancer detection of transperineal, transrectal saturation and MRI guided biopsy.  

UK PubMed Central (United Kingdom)

INTRODUCTION: There is no consensus on how to investigate men with negative transrectal ultrasound guided prostate biopsy (TRUS-B) but ongoing suspicion of cancer. Three strategies used are transperineal (TP-B), transrectal saturation (TS-B) and MRI-guided biopsy (MRI-B). We compared cancer yields of these strategies. METHODS: Papers were identified by search of Pubmed, Embase and Ovid Medline. Included studies investigated biopsy diagnostic yield in men with at least one negative TRUS-B and ongoing suspicion of prostate cancer. Data including age, PSA, number of previous biopsy episodes, number of cores at re-biopsy, cancer yield, and Gleason score of detected cancers were extracted. Meta-regression analyses were used to analyse the data. RESULTS: Forty-six studies were included; 12 of TS-B, 14 of TP-B, and 20 of MRI-B, representing 4,657 patients. Mean patient age, PSA and number of previous biopsy episodes were similar between the strategies. The mean number of biopsy cores obtained by TP-B and TS-B were greater than MRI-B. Cancer detection rates were 30·0%, 36·8%, and 37·6% for TS-B, TP-B, and MRI-B respectively. Meta-regression analysis showed that MRI-B had significantly higher cancer detection than TS-B. There were no significant differences however between MRI-B and TP-B, or TP-B and TS-B. In a sensitivity analysis incorporating number of previous biopsy episodes (36 studies) the difference between MRI-B and TP-B was not maintained resulting in no significant difference in cancer detection between the groups. There were no significant differences in median Gleason scores detected comparing the three strategies. CONCLUSIONS: In the re-biopsy setting, it is unclear which strategy offers the highest cancer detection rate. MRI-B may potentially detect more prostate cancers than other modalities and can achieve this with fewer biopsy cores. However, well-designed prospective studies with standardised outcome measures are needed to accurately compare modalities and define an optimum re-biopsy approach.

Nelson AW; Harvey RC; Parker RA; Kastner C; Doble A; Gnanapragasam VJ

2013-01-01

315

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

2005-01-01

316

Peptide-based MRI contrast agent and near-infrared fluorescent probe for intratumoral legumain detection.  

UK PubMed Central (United Kingdom)

Recent studies suggest that intratumoral legumain promotes tumorigenesis. To monitor legumain activity in tumors, we developed a new MRI contrast agent ([Gd-NBCB-TTDA-Leg(L)]) and a NIR fluorescence probe (CyTE777-Leg(L)-CyTE807). The MRI contrast agent was prepared by introduction of cyclobutyl and benzyl group residues to TTDA (3,6,10-tri(carboxymethyl)-3,6,10-triaza-dodecanedioic acid), followed by the attachment of a legumain-specific substrate peptide (Leg(L)). The NIR fluorescence probe was designed by conjugating two NIR fluorochromes (CyTE777 and CyTE807) with Leg(L). Peptide cleavage of the MRI contrast agent by legumain can increase its hydrophobicity and promote rotational correlation time (?R). Peptide cleavage of the NIR probes by the legumain relieves the self quench of the probe. Peptide cleavage of the MRI contrast agent and the NIR fluorescence probe by legumain were confirmed by T1 relaxometric studies and by fluorescence studies, respectively. In vivo MR images showed that [Gd-NBCB-TTDA-Leg(L)] attained 55.3 fold (254.2% versus 4.6%, at 2.0 h post-injection) higher imaging enhancement, as compared with control contrast agent bearing a noncleaveable peptide ([Gd-NBCB-TTDA-Leg(D)], in the CT-26 (legumain(+)) tumors. Similarly, optical imaging probe CyTE777-Leg(L)-CyTE807 attained 15.2 fold (3.34 × 10(9) photons/min versus 0.22 × 10(9) photons/min, at 24.0 h post-injection) higher imaging enhancement in the CT-26 (legumain(+)) tumors, compared to a NIR control probe (CyTE777-Leg(D)-CyTE807). These data indicate that the [Gd-NBCB-TTDA-Leg(L)] and the CyTE777-Leg(L)-CyTE807 probes may be promising tools to image the legumain-expressing cancers for diagnoses and targeted treatments.

Chen YJ; Wu SC; Chen CY; Tzou SC; Cheng TL; Huang YF; Yuan SS; Wang YM

2013-10-01

317

SVM-Hustle - An iterative semi-supervised machine learning approach for pairwise protein remote homology detection  

Energy Technology Data Exchange (ETDEWEB)

Motivation: As the amount of biological sequence data continues to grow exponentially we face the increasing challenge of assigning function to this enormous molecular ‘parts list’. The most popular approaches to this challenge make use of the simplifying assumption that similar functional molecules, or proteins, sometimes have similar composition, or sequence. However, these algorithms often fail to identify remote homologs (proteins with similar function but dissimilar sequence) which often are a significant fraction of the total homolog collection for a given sequence. We introduce a Support Vector Machine (SVM)-based tool to detect Homology Using Semisupervised iTerative LEarning (SVM-HUSTLE) that detects significantly more remote homologs than current state-of-the-art sequence or cluster-based methods. As opposed to building profiles or position specific scoring matrices, SVM-HUSTLE builds an SVM classifier for a query sequence by training on a collection of representative highconfidence training sets. SVM-HUSTLE combines principles of semi-supervised learning theory with statistical sampling to create many concurrent classifiers to iteratively detect and refine on-the-fly patterns indicating homology. Results: When compared against existing methods for identifying protein homologs (BLASTp, PSI-BLAST, RANKPROP, MOTIFPROP and their variants) on the SCOP 1.59 benchmark dataset consisting of 7329 protein sequences, SVM-HUSTLE significantly outperforms each of the above methods using the most stringent ROC1 statistic with p-values less than 1e-20.

Shah, Anuj R.; Oehmen, Chris S.; Webb-Robertson, Bobbie-Jo M.

2008-03-15

318

MRI at 3 Tesla detects no evidence for ischemic brain damage in intensively treated patients with homozygous familial hypercholesterolemia  

Energy Technology Data Exchange (ETDEWEB)

Homozygous familial hypercholesterolemia (FH) is considered a model disease for excessive plasma cholesterol levels. Patients with untreated homozygous FH have a markedly increased risk for premature atherosclerosis. The frequency and extent of ischemic brain damage detectable by high-field magnetic resonance imaging (MRI) after long-term intensive treatment are unknown. In a case control study, five patients with homozygous FH (one male and four females; mean age: 23.6 {+-} 9.2, range: 12-36 years; mean pre-treatment serum total cholesterol level: 26.9 {+-} 3.24 mmol/L; all patients with documented atherosclerotic plaques in the carotid arteries) and five age- and sex-matched healthy controls were studied. All patients had been on maximal lipid-lowering medication since early childhood, and four of them were also on treatment with low-density lipoprotein (LDL) apheresis at bi-weekly intervals. Brain MRI was performed at 3 Tesla field strength with fluid-attenuated T2-weighted inversion recovery and T1-weighted spin-echo MR pulse sequences and subsequently evaluated by two independent readers. The maximal lipid-lowering treatment reduced the total serum cholesterol by more than 50% in the patients, but their serum concentrations were still 3.6-fold higher than those found in the controls (11.9 {+-} 4.2 vs. 4.5 {+-} 0.5 mmol/L; p < 0.0047). No brain abnormality was observed in any of the patients with homozygous FH. Homozygous FH patients on intensive cholesterol-lowering therapy have no evidence of ischemic brain damage at 3 Tesla MRI despite the remaining high cholesterol levels. (orig.)

Schmitz, Stephan A.; O' Regan, Declan P.; Fitzpatrick, Julie; Hajnal, Joseph V. [Hammersmith Hospital Campus, Imaging Sciences Department, MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College, London (United Kingdom); Neuwirth, Clare; Potter, Elizabeth; Tosi, Isabella; Naoumova, Rossi P. [MRC Clinical Sciences Centre, Clinical Research Facility, London (United Kingdom); Hammersmith Hospital, Lipid Clinic, London (United Kingdom)

2007-11-15

319

Detection of contralateral normal ovary in patients with large(>10 cm) unilateral ovarian mass by using MRI  

International Nuclear Information System (INIS)

To assess the usefulness of MRI for determining the presence of a large (> 10 cm) unilateral ovarian tumor by detecting the existence of a normal contralateral ovary, and to establish the difference in detection rates between premenopausal and postmenopausal women, and benign and malignant tumors. Forty-two patients who underwent MR imaging and in whom the intraoperative gross and pathologic findings indicated the presence of a unilateral ovarian mass and a normal contralateral ovary were included in this study. The images obtained were retrospectively analyzed by two radiologists, who determined the detection rate of the normal contralateral ovary and whether this differed between premenopausal and postmenopausal women, and benign and malignant tumors. Contralateral normal ovaries were detected in 35 (83.3%) of 42 patients [22 of 23 ovaries (95.7%) in premenopausal women and 13 of 19 (68.4%) in postmenopausal women], with a statistically significant difference (p=0.018). Twelve of 16 of these ovaries (75%) were present in women with malignant tumors, and 23 (88.5%) of 26 in those with benign tumors, but the difference was not statistically significant (p=0.256). MR imaging is useful for detecting a normal contralateral ovary and for determining the site at which a large (> 10 cm) unilateral ovarian tumor originates, especially in premenopausal women

2004-01-01

320

Detection of contralateral normal ovary in patients with large(>10 cm) unilateral ovarian mass by using MRI  

Energy Technology Data Exchange (ETDEWEB)

To assess the usefulness of MRI for determining the presence of a large (> 10 cm) unilateral ovarian tumor by detecting the existence of a normal contralateral ovary, and to establish the difference in detection rates between premenopausal and postmenopausal women, and benign and malignant tumors. Forty-two patients who underwent MR imaging and in whom the intraoperative gross and pathologic findings indicated the presence of a unilateral ovarian mass and a normal contralateral ovary were included in this study. The images obtained were retrospectively analyzed by two radiologists, who determined the detection rate of the normal contralateral ovary and whether this differed between premenopausal and postmenopausal women, and benign and malignant tumors. Contralateral normal ovaries were detected in 35 (83.3%) of 42 patients [22 of 23 ovaries (95.7%) in premenopausal women and 13 of 19 (68.4%) in postmenopausal women], with a statistically significant difference (p=0.018). Twelve of 16 of these ovaries (75%) were present in women with malignant tumors, and 23 (88.5%) of 26 in those with benign tumors, but the difference was not statistically significant (p=0.256). MR imaging is useful for detecting a normal contralateral ovary and for determining the site at which a large (> 10 cm) unilateral ovarian tumor originates, especially in premenopausal women.

Jung, Young Jin; Cho, Jae Ho; Park, Won Kyu [School of Medicine, Yeungnam Univ., Daegu (Korea, Republic of); Kim, Jae Woon [Youngshin Hospital, Seoul (Korea, Republic of)

2004-02-01

 
 
 
 
321

Detection and quantification of remote microglial activation in rodent models of focal ischaemia using the TSPO radioligand CLINDE  

International Nuclear Information System (INIS)

[en] Neuroinflammation is involved in stroke pathophysiology and might be imaged using radioligands targeting the 18 kDa translocator protein (TSPO). We studied microglial reaction in brain areas remote from the primary lesion site in two rodent models of focal cerebral ischaemia (permanent or transient) using [125I]-CLINDE, a promising TSPO single photon emission computed tomography radioligand. In a mouse model of permanent middle cerebral artery occlusion (MCAO), ex vivo autoradiographic studies demonstrated, besides in the ischaemic territory, accumulation of [125I]-CLINDE in the ipsilateral thalamus with a binding that progressed up to 3 weeks after MCAO. [125I]-CLINDE binding markedly decreased in animals pre-injected with either unlabelled CLINDE or PK11195, while no change was observed with flumazenil pre-treatment, demonstrating TSPO specificity. In rats subjected to transient MCAO, [125I]-CLINDE binding in the ipsilateral thalamus and substantia nigra pars reticulata (SNr) was significantly higher than that in contralateral tissue. Moreover, [125I]-CLINDE binding in the thalamus and SNr was quantitatively correlated to the ischaemic volume assessed by MRI in the cortex and striatum, respectively. Clinical consequences of secondary neuronal degeneration in stroke might be better treated thanks to the discrimination of neuronal processes using in vivo molecular imaging and potent TSPO radioligands like CLINDE to guide therapeutic interventions. (orig.)

2010-01-01

322

Seasonal chemical-physical changes of PGI Pachino cherry tomatoes detected by magnetic resonance imaging (MRI)  

UK PubMed Central (United Kingdom)

Magnetic resonance imaging (MRI) has been used to study the variations of internal structure and chemical-physical characteristics of cherry tomatoes (Lycopersicon esculentum cv. Shiren), one the most economically valuable horticultural crops, in different harvesting seasons. In particular, the study focused on PGI (Protected Geographical Indication) Pachino cherry tomatoes, characterised by taste and nutritional value, notably in the winter production, amounting about 500ton/year. Spin-spin and spin-lattice relaxation times, T ? and T ? respectively, determined on whole fruit, provided useful data highlighting variations among samples according to the season (winter, spring and summer). MRI images evidenced differences among cellular tissues such as pericarp and endocarp, through variations of: (1) T ? and T ? measures and water tumbling and diffusion motion, (2) thicknesses of different morphological zones, (3) qualitative characteristics of the tissue covering placental cavities where seeds are contained. Results of variance analysis (ANOVA) showed that physical parameters, as the transverse and longitudinal relaxation times, T ? and T ?, measured in the morphological tissues of vegetables are excellent variables highlighting their differences in different seasons. This innovative non-destructive technique in food science has great potential in fruit quality assessment.

Ciampa Alessandra; Dell'Abate MariaTeresa; Masetti Olimpia; Valentini Massimiliano; Sequi Paolo

2010-10-01

323

A quality control method for detecting and suppressing uncorrected residual motion in fMRI studies.  

UK PubMed Central (United Kingdom)

Motion correction is an important step in the functional magnetic resonance imaging (fMRI) analysis pipeline. While many studies simply exclude subjects who are estimated to have moved beyond an arbitrary threshold, there exists no objective method for determining an appropriate threshold. Furthermore, any criterion based only upon motion estimation ignores the potential for proper realignment. The method proposed here uses unsupervised learning (specifically k-means clustering) on features derived from the mean square derivative (MSD) of the signal before and after realignment to identify problem data. These classifications are refined through analysis of correlation between subject activation maps and the mean activation map, as well as the relationship between tasking and motion as measured through regression of the canonical hemodynamic response functions to fit both estimated motion parameters and MSD. The MSD is further used to identify specific scans containing residual motion, data which is suppressed by adding nuisance regressors to the general linear model; this statistical suppression is performed for identified problem subjects, but has potential for use over all subjects. For problem subjects, our results show increased hemodynamic activity more consistent with group results; that is, the addition of nuisance regressors resulted in a doubling of the correlation between the activation map for the problem subjects and the activation map for all subjects. The proposed method should be useful in helping fMRI researchers make more efficient use of their data by reducing the need to exclude entire subjects from studies and thus collect new data to replace excluded subjects.

Christodoulou AG; Bauer TE; Kiehl KA; Feldstein Ewing SW; Bryan AD; Calhoun VD

2013-06-01

324

Detection and quantification of angiogenesis in experimental valve disease with integrin-targeted nanoparticles and 19-fluorine MRI/MRS  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Angiogenesis is a critical early feature of atherosclerotic plaque development and may also feature prominently in the pathogenesis of aortic valve stenosis. It has been shown that MRI can detect and quantify specific molecules of interest expressed in cardiovascular disease and cancer by measuring the unique fluorine signature of appropriately targeted perfluorocarbon (PFC) nanoparticles. In this study, we demonstrated specific binding of ???3 integrin targeted nanoparticles to neovasculature in a rabbit model of aortic valve disease. We also showed that fluorine MRI could be used to detect and quantify the development of neovasculature in the excised aortic valve leaflets. Methods New Zealand White rabbits consumed a cholesterol diet for ~180 days and developed aortic valve thickening, inflammation, and angiogenesis mimicking early human aortic valve disease. Rabbits (n = 7) were treated with ???3 integrin targeted PFC nanoparticles or control untargeted PFC nanoparticles (n = 6). Competitive inhibition in vivo of nanoparticle binding (n = 4) was tested by pretreatment with targeted nonfluorinated nanoparticles followed 2 hours later by targeted PFC nanoparticles. 2 hours after treatment, aortic valves were excised and 19F MRS was performed at 11.7T. Integrated 19F spectral peaks were compared using a one-way ANOVA and Hsu's MCB (multiple comparisons with the best) post hoc t test. In 3 additional rabbits treated with ???3 integrin targeted PFC nanoparticles, 19F spectroscopy was performed on a 3.0T clinical scanner. The presence of angiogenesis was confirmed by immunohistochemistry. Results Valves of rabbits treated with targeted PFC nanoparticles had 220% more fluorine signal than valves of rabbits treated with untargeted PFC nanoparticles (p ??3 integrin staining revealed the presence of neovasculature within the valve leaflets. Conclusion Integrin-targeted PFC nanoparticles specifically detect early angiogenesis in sclerotic aortic valves of cholesterol fed rabbits. These techniques may be useful for assessing atherosclerotic components of preclinical aortic valve disease in patients and could assist in defining efficacy of medical therapies.

Waters Emily A; Chen Junjie; Allen John S; Zhang Huiying; Lanza Gregory M; Wickline Samuel A

2008-01-01

325

MRI at 3 Tesla detects no evidence for ischemic brain damage in intensively treated patients with homozygous familial hypercholesterolemia  

International Nuclear Information System (INIS)

Homozygous familial hypercholesterolemia (FH) is considered a model disease for excessive plasma cholesterol levels. Patients with untreated homozygous FH have a markedly increased risk for premature atherosclerosis. The frequency and extent of ischemic brain damage detectable by high-field magnetic resonance imaging (MRI) after long-term intensive treatment are unknown. In a case control study, five patients with homozygous FH (one male and four females; mean age: 23.6 ± 9.2, range: 12-36 years; mean pre-treatment serum total cholesterol level: 26.9 ± 3.24 mmol/L; all patients with documented atherosclerotic plaques in the carotid arteries) and five age- and sex-matched healthy controls were studied. All patients had been on maximal lipid-lowering medication since early childhood, and four of them were also on treatment with low-density lipoprotein (LDL) apheresis at bi-weekly intervals. Brain MRI was performed at 3 Tesla field strength with fluid-attenuated T2-weighted inversion recovery and T1-weighted spin-echo MR pulse sequences and subsequently evaluated by two independent readers. The maximal lipid-lowering treatment reduced the total serum cholesterol by more than 50% in the patients, but their serum concentrations were still 3.6-fold higher than those found in the controls (11.9 ± 4.2 vs. 4.5 ± 0.5 mmol/L; p

2007-01-01

326

A CAD system based on multi-parametric analysis for cancer prostate detection on DCE-MRI  

Science.gov (United States)

Computer-aided diagnosis (CAD) systems using dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) data may be developed to help localize prostate cancer and guide biopsy, avoiding random sampling of the whole gland. The purpose of this study is to present a DCE-MRI CAD system, which calculates the likelihood of malignancy in a given area of the prostate by combining model-based and model-free parameters. The dataset includes 10 patients with prostate cancer, with a total of 13 foci of adenocarcinoma. The post-processing is based on the following steps: testing of registration quality, noise filtering, and extracting the proposed features needed to the CAD. Parameters with the best performance in discriminating between normal and cancer regions are selected by computing the area under the ROC curve, and by evaluating the correlation between pairs of features. A 6-dimensional parameters vector is generated for each pixel and fed into a Bayesian classifier, in which the output is the probability of malignancy. The classification performance is estimated using the leave-one-out method. The resulting area under the ROC curve is 0.899 (95%CI:0.893-0.905); sensitivity and specificity are 82.4% and 82.1% respectively at the best cut-off point (0.352). Preliminary results show that the system is accurate in detecting areas of the gland that are involved by tumor. Further studies will be necessary to confirm these promising preliminary results.

Mazzetti, Simone; de Luca, Massimo; Bracco, Christian; Vignati, Anna; Giannini, Valentina; Stasi, Michele; Russo, Filippo; Armando, Enrico; Agliozzo, Silvano; Regge, Daniele

2011-03-01

327

The detection and mapping of oil on a marshy area by a remote luminescent sensor  

Science.gov (United States)

Airborne remote sensing can be a cost-effective method for monitoring pollutants in large areas such as occur in oil spills. An opportunity to test a particular method arose when a well ruptured and for 23 days spewed a 90-meter fountain of oil into the air, dispersing the oil over a wide area. The method tested was an airborne luminescence detector with a Fraunhofer Line Discriminator (FLD) which was flown over the affected area 41 days after the well was capped to obtain a map or the deposition pattern. To calibrate the system, samples of Spartina (wire grass) and Phragmites (common reed) were collected from the contaminated area and the oil residues were eluted in cyclohexane and quantitatively analyzed in a fluorescence photometer. Good correlation was observed between the remote sensor (FLD) and the laboratory analysis. Isopleths defining the deposition pattern of oil were drawn from the remote sensing information. A discussion will be presented on the feasibility of using this instrument for similar contamination incidents for cleanup and damage assessment.

McFarlane, C.; Watson, R. D.

2005-01-01

328

A comprehensive review of earthquake-induced building damage detection with remote sensing techniques  

Science.gov (United States)

Earthquakes are among the most catastrophic natural disasters to affect mankind. One of the critical problems after an earthquake is building damage assessment. The area, amount, rate, and type of the damage are essential information for rescue, humanitarian and reconstruction operations in the disaster area. Remote sensing techniques play an important role in obtaining building damage information because of their non-contact, low cost, wide field of view, and fast response capacities. Now that more and diverse types of remote sensing data become available, various methods are designed and reported for building damage assessment. This paper provides a comprehensive review of these methods in two categories: multi-temporal techniques that evaluate the changes between the pre- and post-event data and mono-temporal techniques that interpret only the post-event data. Both categories of methods are discussed and evaluated in detail in terms of the type of remote sensing data utilized, including optical, LiDAR and SAR data. Performances of the methods and future efforts are drawn from this extensive evaluation.

Dong, Laigen; Shan, Jie

2013-10-01

329

Labeling of mesenchymal stem cells with different superparamagnetic particles of iron oxide and detectability with MRI at 3T  

International Nuclear Information System (INIS)

Purpose: In vitro evaluation of labeling efficiency of human mesenchymal stem cells (hMSCs) with different types of superparamagnetic iron oxide nanoparticles as well as detection and quantification by MRI at 3T. Material and methods: hMSCs were incubated for 24 hours with 5 ultrasmall superparamagnetic particles of iron oxide (USPIO) contrast agents (1:30-1:30,000) of different size, coating and core compound: Endorem registered, Resovist registered, citric acid coated magnetite cores of 3 nm (CMF3), 7 nm (CMF7) and 12 nm (CoF; core: cobalt ferrite). Iron uptake, intracellular retention, detection and quantification were evaluated with MRI up to 5 weeks after incubation by cytological analysis (Prussian blue) atomic absorption spectrometry and MR relaxometry measurements. Results: An effective labeling of hMSCs was achieved using Resovist registered, CMF3 and CMF7 with mean iron concentrations of 5.1/1.8, 1.9/1.4 and 1.5/1.0 pg/cell (dilutions 1:30 [933, 2100, 2800 ?g Fe/ml]/1:300 [93, 210, 280 ?g Fe/ml)] compared with 0.58/0.34 and 0.43/0.30 pg/cell (Endorem registered, CoF, dilution 1:30 [400, 4200 ?g Fe/ml]/1:300 [40, 420 ?g Fe/ml] unlabelled control cells: 0.01 pg/cell). Particle uptake correlated with the concentration of USPIO in the incubation medium. Detection of 5 x 104 labelled cells/ml with MRI was possible up to 5 weeks after incubation (Resovist registered, CMF7 and CMF3). MR relaxometry measurements showed a strong correlation between cellular iron load and R2* (1/T2*), r > 0.78. No changes in cell viability or toxic effects were found. Conclusion: Efficiency of labeling hMSCs with USPIOs depends on coating, size and core compound of used particles. Carboxydextran-coated, clinically approved SPIO (Resovist registered, 50 nm) or ultrasmall citrate-coated particles (

2005-01-01

330

Remote explosive and chemical agent detection using broadly tunable mid-infrared external cavity quantum cascade lasers  

Science.gov (United States)

Terrorists both with IEDs and suicide bombers are targeting civilian infrastructures such as transportation systems. Although explosive detection technologies exist and are used effectively in aviation, these technologies do not lend themselves well to protecting open architecture soft targets, as they are focused on a checkpoint form factor that limits throughput. However, remote detection of explosives and other chemicals would enable these kinds of targets to be protected without interrupting the flow of commerce. Tunable mid-IR laser technology offers the opportunity to detect explosives and other chemicals remotely and quickly. Most chemical compounds, including explosives, have their fundamental vibrational modes in the mid-infrared region (3 to 15?m). There are a variety of techniques that focus on examining interactions that have proven effective in the laboratory but could never work in the field due to complexity, size, reliability and cost. Daylight Solutions has solved these problems by integrating quantum cascade gain media into external tunable cavities. This has resulted in miniaturized, broadly tunable mid-IR laser sources. The laser sources have a capability to tune to +/- 5% of their center wavelength, which means they can sweep through an entire absorption spectrum to ensure very good detection and false alarm performance compared with fixed wavelength devices. These devices are also highly portable, operate at room temperature, and generate 10's to 100's of mW in optical power, in pulsed and continuous wave configurations. Daylight Solutions is in the process of developing a variety of standoff explosive and chemical weapon detection systems using this technology.

Rayner, Timothy; Weida, Miles; Pushkarsky, Michael; Day, Timothy

2007-04-01

331

A discriminative method for family-based protein remote homology detection that combines inductive logic programming and propositional models.  

UK PubMed Central (United Kingdom)

BACKGROUND: Remote homology detection is a hard computational problem. Most approaches have trained computational models by using either full protein sequences or multiple sequence alignments (MSA), including all positions. However, when we deal with proteins in the "twilight zone" we can observe that only some segments of sequences (motifs) are conserved. We introduce a novel logical representation that allows us to represent physico-chemical properties of sequences, conserved amino acid positions and conserved physico-chemical positions in the MSA. From this, Inductive Logic Programming (ILP) finds the most frequent patterns (motifs) and uses them to train propositional models, such as decision trees and support vector machines (SVM). RESULTS: We use the SCOP database to perform our experiments by evaluating protein recognition within the same superfamily. Our results show that our methodology when using SVM performs significantly better than some of the state of the art methods, and comparable to other. However, our method provides a comprehensible set of logical rules that can help to understand what determines a protein function. CONCLUSIONS: The strategy of selecting only the most frequent patterns is effective for the remote homology detection. This is possible through a suitable first-order logical representation of homologous properties, and through a set of frequent patterns, found by an ILP system, that summarizes essential features of protein functions.

Bernardes JS; Carbone A; Zaverucha G

2011-01-01

332

A discriminative method for family-based protein remote homology detection that combines inductive logic programming and propositional models  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Remote homology detection is a hard computational problem. Most approaches have trained computational models by using either full protein sequences or multiple sequence alignments (MSA), including all positions. However, when we deal with proteins in the "twilight zone" we can observe that only some segments of sequences (motifs) are conserved. We introduce a novel logical representation that allows us to represent physico-chemical properties of sequences, conserved amino acid positions and conserved physico-chemical positions in the MSA. From this, Inductive Logic Programming (ILP) finds the most frequent patterns (motifs) and uses them to train propositional models, such as decision trees and support vector machines (SVM). Results We use the SCOP database to perform our experiments by evaluating protein recognition within the same superfamily. Our results show that our methodology when using SVM performs significantly better than some of the state of the art methods, and comparable to other. However, our method provides a comprehensible set of logical rules that can help to understand what determines a protein function. Conclusions The strategy of selecting only the most frequent patterns is effective for the remote homology detection. This is possible through a suitable first-order logical representation of homologous properties, and through a set of frequent patterns, found by an ILP system, that summarizes essential features of protein functions.

Bernardes Juliana S; Carbone Alessandra; Zaverucha Gerson

2011-01-01

333

Effects of artificial lighting on the detection of plant stress with spectral reflectance remote sensing in bioregenerative life support systems  

Science.gov (United States)

Plant-based life support systems that utilize bioregenerative technologies have been proposed for long-term human missions to both the Moon and Mars. Bioregenerative life support systems will utilize higher plants to regenerate oxygen, water, and edible biomass for crews, and are likely to significantly lower the ‘equivalent system mass’ of crewed vehicles. As part of an ongoing effort to begin the development of an automatic remote sensing system to monitor plant health in bioregenerative life support modules, we tested the efficacy of seven artificial illumination sources on the remote detection of plant stresses. A cohort of pepper plants (Capsicum annuum L.) were grown 42 days at 25 °C, 70% relative humidity, and 300 ?mol m-2 s-1 of photosynthetically active radiation (PAR; from 400 to 700 nm). Plants were grown under nutritional stresses induced by irrigating subsets of the plants with 100, 50, 25, or 10% of a standard nutrient solution. Reflectance spectra of the healthy and stressed plants were collected under seven artificial lamps including two tungsten halogen lamps, plus high pressure sodium, metal halide, fluorescent, microwave, and red/blue light emitting diode (LED) sources. Results indicated that several common algorithms used to estimate biomass and leaf chlorophyll content were effective in predicting plant stress under all seven illumination sources. However, the two types of tungsten halogen lamps and the microwave illumination source yielded linear models with the highest residuals and thus the highest predictive capabilities of all lamps tested. The illumination sources with the least predictive capabilities were the red/blue LEDs and fluorescent lamps. Although the red/blue LEDs yielded the lowest residuals for linear models derived from the remote sensing data, the LED arrays used in these experiments were optimized for plant productivity and not the collection of remote sensing data. Thus, we propose that if adjusted to optimize the collectio n of remote sensing information from plants, LEDs remain the best candidates for illumination sources for monitoring plant stresses in bioregenerative life support systems.

Schuerger, Andrew C.; Richards, Jeffrey T.

2006-09-01

334

Implant detectibility of intervertebral disc spacers in post fusion MRI: evaluation of the MRI scan quality by using a scoring system - an in vitro study  

Energy Technology Data Exchange (ETDEWEB)

Intervertebral spacers for anterior spine fusion are made of different materials, such as titanium and cobalt chromium alloys and carbon fiber-reinforced polymers. Implant-related susceptibility artifacts can decrease the quality of MRI scans. The aim of this cadaveric study was to demonstrate the extent that implant-related MRI artifacting affects the postfusion differentiation of determined regions of interest (ROIs). In six cadaveric porcine spines, we evaluated the postimplantation MRI scans of a titanium, cobalt-chromium and carbon spacer that differed in shape and surface qualities. A spacer made of human cortical bone was used as a control. A defined evaluation unit was divided into ROIs to characterize the spinal canal as well as the intervertebral disc space. Considering 15 different MRI sequences read independently by an interobserver-validated team of specialists the artifact-affected image quality of the median MRI slice was rated on a score of 0-3. A maximum score of 18 points (100%) for the determined ROIs was possible. Turbo spin echo sequences produced the best scores for all spacers and the control. Only the control achieved a score of 100%. For the determined ROI maximum scores for the cobalt-chromium, titanium and carbon spacers were 24%, 32% and 84%, respectively. By using favored T1 TSE sequences the carbon spacer showed a clear advantage in postfusion spinal imaging. Independent of artifact dimensions, the scoring system used allowed us to create an implant-related ranking of MRI scan quality in reference to the bone control. (orig.)

Ernstberger, Thorsten; Schultz, Wolfgang [University of Goettingen, Department of Orthopaedic Surgery, Goettingen (Germany); Heidrich, Gabert; Grabbe, Eckhardt [Georg-August-University of Goettingen, Department of Diagnostic Radiology, Goettingen (Germany)

2007-02-15

335

Detection of physiological noise in resting state fMRI using machine learning.  

UK PubMed Central (United Kingdom)

We present a technique for predicting cardiac and respiratory phase on a time point by time point basis, from fMRI image data. These predictions have utility in attempts to detrend effects of the physiological cycles from fMRI image data. We demonstrate the technique both in the case where it can be trained on a subject's own data, and when it cannot. The prediction scheme uses a multiclass support vector machine algorithm. Predictions are demonstrated to have a close fit to recorded physiological phase, with median Pearson correlation scores between recorded and predicted values of 0.99 for the best case scenario (cardiac cycle trained on a subject's own data) down to 0.83 for the worst case scenario (respiratory predictions trained on group data), as compared to random chance correlation score of 0.70. When predictions were used with RETROICOR--a popular physiological noise removal tool--the effects are compared to using recorded phase values. Using Fourier transforms and seed based correlation analysis, RETROICOR is shown to produce similar effects whether recorded physiological phase values are used, or they are predicted using this technique. This was seen by similar levels of noise reduction noise in the same regions of the Fourier spectra, and changes in seed based correlation scores in similar regions of the brain. This technique has a use in situations where data from direct monitoring of the cardiac and respiratory cycles are incomplete or absent, but researchers still wish to reduce this source of noise in the image data.

Ash T; Suckling J; Walter M; Ooi C; Tempelmann C; Carpenter A; Williams G

2013-04-01

336

Detection of physiological noise in resting state fMRI using machine learning.  

Science.gov (United States)

We present a technique for predicting cardiac and respiratory phase on a time point by time point basis, from fMRI image data. These predictions have utility in attempts to detrend effects of the physiological cycles from fMRI image data. We demonstrate the technique both in the case where it can be trained on a subject's own data, and when it cannot. The prediction scheme uses a multiclass support vector machine algorithm. Predictions are demonstrated to have a close fit to recorded physiological phase, with median Pearson correlation scores between recorded and predicted values of 0.99 for the best case scenario (cardiac cycle trained on a subject's own data) down to 0.83 for the worst case scenario (respiratory predictions trained on group data), as compared to random chance correlation score of 0.70. When predictions were used with RETROICOR--a popular physiological noise removal tool--the effects are compared to using recorded phase values. Using Fourier transforms and seed based correlation analysis, RETROICOR is shown to produce similar effects whether recorded physiological phase values are used, or they are predicted using this technique. This was seen by similar levels of noise reduction noise in the same regions of the Fourier spectra, and changes in seed based correlation scores in similar regions of the brain. This technique has a use in situations where data from direct monitoring of the cardiac and respiratory cycles are incomplete or absent, but researchers still wish to reduce this source of noise in the image data. PMID:22121056

Ash, Tom; Suckling, John; Walter, Martin; Ooi, Cinly; Tempelmann, Claus; Carpenter, Adrian; Williams, Guy

2011-11-28

337

Acute irradiation injury of canine brain with pathology control is detected by diffusion-weighted imaging of MRI.  

UK PubMed Central (United Kingdom)

To investigate the pathological changes of canine brain after irradiation and evaluate the effect of diffusion-weighted imaging (DWI), 25 healthy dogs were treated with 70 Gy (60)Co?-ray irradiation on right temporal brain. Respectively, the apparent diffusion coefficient (ADC) values of canine alba and ectocinerea were measured by MRI T1 weighted imaging (T1WI), T2 weighted imaging (T2WI), and DWI. Compared with the control group, at every time point after irradiation, the ADC values of canine brain tissue were decreased significantly (P<.05). DWI is a very sensitive imaging technology that detects the changes of water molecule diffusion and microscopic pathological changes after canine brain irradiation.

Wang Y; Lv X; Gong H; Yuan G; Zhang B; Zhao H; Liu J

2013-05-01

338

Acute irradiation injury of canine brain with pathology control is detected by diffusion-weighted imaging of MRI.  

Science.gov (United States)

To investigate the pathological changes of canine brain after irradiation and evaluate the effect of diffusion-weighted imaging (DWI), 25 healthy dogs were treated with 70 Gy (60)Co?-ray irradiation on right temporal brain. Respectively, the apparent diffusion coefficient (ADC) values of canine alba and ectocinerea were measured by MRI T1 weighted imaging (T1WI), T2 weighted imaging (T2WI), and DWI. Compared with the control group, at every time point after irradiation, the ADC values of canine brain tissue were decreased significantly (P<.05). DWI is a very sensitive imaging technology that detects the changes of water molecule diffusion and microscopic pathological changes after canine brain irradiation. PMID:23102926

Wang, Yanming; Lv, Xiaoyan; Gong, Hai; Yuan, Guanghui; Zhang, Baoyi; Zhao, Hui; Liu, Jianguo

2012-10-25

339

Value of retrospective fusion of PET and MR images in detection of hepatic metastases: comparison with 18F-FDG PET/CT and Gd-EOB-DTPA-enhanced MRI.  

UK PubMed Central (United Kingdom)

UNLABELLED: The purpose of this study was to compare the accuracy of lesion detection and diagnostic confidence between (18)F-FDG PET/CT, gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI, and retrospectively fused PET and MRI (PET/MRI). METHODS: Thirty-seven patients (mean age +/- SD, 60.2 +/- 12 y) with suspected liver metastases underwent PET/CT and Gd-EOB-DTPA-enhanced MRI within 0-30 d (mean, 11.9 +/- 9 d). PET and Gd-EOB-DTPA-enhanced MR image data were retrospectively fused. Images were reviewed independently by 2 readers who identified and characterized liver lesions using PET/CT, Gd-EOB-DTPA-enhanced MRI, and PET/MRI. Each liver lesion was graded on a 5-point confidence scale ranging from definitely benign (grade of 1) to definitely malignant (grade of 5). The accuracy of each technique was determined by receiver-operating-characteristic analysis. Histopathology served as the standard of reference for all patients with malignant lesions. RESULTS: A total of 85 liver lesions (55 liver metastases [65%] and 30 benign lesions [35%]) were present in 29 (78%) of the 37 patients. Twenty-four (65%) of the 37 patients had liver metastases. The detection rate of liver lesions was significantly lower for PET/CT than for Gd-EOB-DTPA-enhanced MRI (64% and 85%; P = 0.002). Sensitivity in the detection and characterization of liver metastases for PET/CT, Gd-EOB-DTPA-enhanced MRI, PET/MRI in reader 1, and PET/MRI in reader 2 was 76%, 91%, 93%, and 93%, respectively; the respective specificity values were 90%, 100%, 87%, and 97%. The difference in sensitivity between PET/CT and PET/MRI was significant (P = 0.023). The level of confidence regarding liver lesions larger than 1 cm in diameter was significantly higher in PET/MRI than in PET/CT (P = 0.046). Accuracy values (area under the receiver-operating-characteristic curve) for PET/CT, Gd-EOB-DTPA-enhanced MRI, PET/MRI in reader 1, and PET/MRI in reader 2 were 0.85, 0.94, 0.92, and 0.96, respectively. CONCLUSION: The sensitivity of Gd-EOB-DTPA-enhanced MRI and PET/MRI in the detection of liver metastases is higher than that of PET/CT. Diagnostic confidence was significantly better with PET/MRI than with PET/CT regarding lesions larger than 1 cm in diameter. Compared with Gd-EOB-DTPA-enhanced MRI, PET/MRI resulted in a nonsignificant increase in sensitivity and diagnostic confidence.

Donati OF; Hany TF; Reiner CS; von Schulthess GK; Marincek B; Seifert B; Weishaupt D

2010-05-01

340

The potential of passive-remote Fourier transform infrared (FTIR) spectroscopy to detect organic emissions under the Clean Air Act  

Energy Technology Data Exchange (ETDEWEB)

The Clean Air Act of 1990 regulates the emission of 198 air toxics. Currently, there is no existing technology by which a regulatory agency can independently determine if a facility is in compliance. We have successfully tested the ability of passive-remote Fourier transform infrared (FTIR) spectroscopy to detect chemical plumes released in the field. Additional laboratory releases demonstrated that FTIR spectroscopy can detect target analytes in mixtures containing components which have overlapping absorbances. The FTIR spectrometer was able to identify and quantify each component released with an average quantitative error of less than 20% using partial least squares (PLS) analysis and 40% using classical least squares analysis (CLS) when calibration files containing pure components and mixtures were used. Calibration files containing only pure analytes resulted in CLS outperforming PLS analyses.

Demirgian, J.C.; Hammer, C.L. [Argonne National Lab., IL (United States); Kroutil, R.T. [Chemical Research, Development and Engineering Center, Aberdeen Proving Ground, MD (United States)

1992-07-01

 
 
 
 
341

The potential of passive-remote Fourier transform infrared (FTIR) spectroscopy to detect organic emissions under the Clean Air Act  

Energy Technology Data Exchange (ETDEWEB)

The Clean Air Act of 1990 regulates the emission of 198 air toxics. Currently, there is no existing technology by which a regulatory agency can independently determine if a facility is in compliance. We have successfully tested the ability of passive-remote Fourier transform infrared (FTIR) spectroscopy to detect chemical plumes released in the field. Additional laboratory releases demonstrated that FTIR spectroscopy can detect target analytes in mixtures containing components which have overlapping absorbances. The FTIR spectrometer was able to identify and quantify each component released with an average quantitative error of less than 20% using partial least squares (PLS) analysis and 40% using classical least squares analysis (CLS) when calibration files containing pure components and mixtures were used. Calibration files containing only pure analytes resulted in CLS outperforming PLS analyses.

Demirgian, J.C.; Hammer, C.L. (Argonne National Lab., IL (United States)); Kroutil, R.T. (Chemical Research, Development and Engineering Center, Aberdeen Proving Ground, MD (United States))

1992-01-01

342

Comparison of triple dose versus standard dose gadolinium-DTPA for detection of MRI enhancing lesions in patients with MS.  

Science.gov (United States)

We studied whether a triple dose of gadolinium-DTPA alone or in combination with delayed scanning increases the sensitivity of brain MRI for detecting enhancing lesions in patients with MS. We obtained T1-weighted brain MRI scans in two sessions for 22 patients with clinically definite MS. In the first session, we obtained one scan 5 to 7 minutes after the injection of 0.1 mmol/kg gadolinium-DTPA (standard dose). In the second session, 6 to 24 hours later, we obtained one scan before the two scans 5 to 7 minutes (for all patients) and one hour (for 11 patients) after the injection of 0.3 mmol/kg gadolinium-DTPA (triple dose). We detected 83 enhancing lesions in 14 patients when the standard dose of gadolinium-DTPA was used. The numbers of enhancing lesions increased to 138 (average increase 66%; p = 0.001) and the numbers of patients with such lesions to 18 (increase 28%) when we used the triple dose of gadolinium-DTPA. In addition, the total area per patient occupied by such lesions was greater (p < 0.0001) and lesion signal intensity higher (p = 0.0001) on the triple-dose scans than the standard-dose scans. There was an increase in the number of large enhancing lesions (p = 0.03) in the scans obtained 1 hour after the injection of the triple dose of gadolinium-DTPA. These data indicate that in patients with MS, a triple dose of gadolinium-DTPA can reveal many more enhancing lesions, which also appear larger. This suggests that the pathologic nature of "active" lesions in MS is heterogeneous, which might have impact on planning clinical trials. PMID:8614498

Filippi, M; Yousry, T; Campi, A; Kandziora, C; Colombo, B; Voltz, R; Martinelli, V; Spuler, S; Bressi, S; Scotti, G; Comi, G

1996-02-01

343

[MRI-based flow measurements in the main pulmonary artery to detect pulmonary arterial hypertension in patients with cystic fibrosis].  

UK PubMed Central (United Kingdom)

PURPOSE: Development of pulmonary arterial hypertension (PH) is a common problem in the course of patients suffering from cystic fibrosis (CF). This study was performed to evaluate MRI based flow measurements (MR(venc); Velocity ENCoding) to detect signs of an evolving PH in patients suffering from CF. MATERIALS AND METHODS: 48 patients (median age: 16 years, range: 10 - 40 years, 25 female) suffering from CF of different severity (mean FEV (1): 74% +/- 23, mean Shwachman-score: 63 +/- 10) were examined using MRI based flow measurements of the main pulmonary artery (MPA). Phase-contrast flash sequences (TR: 9.6 ms, TE: 2.5 ms, bandwidth: 1395 Hertz/Pixel) were utilized. Results were compared to an age- and sex-matched group of 48 healthy subjects. Analyzed flow data where: heart frequency (HF), cardiac output (HZV), acceleration time (AT), proportional acceleration time related to heart rate (ATr), mean systolic blood velocity (MFG), peak velocity (Peak), maximum fow (Fluss(max)), mean flow (Fluss(mitt)) and distensibility (Dist). RESULTS: The comparison of means revealed significant differences only for MFG, Fluss(max) and Dist, but overlap was marked. However, using a scatter-plot of AT versus MFG, it was possible to identify five CF-patients demonstrating definite signs of PH: AT = 81 ms +/- 14, MFG = 46 +/- 11 cm/s, Dist = 41% +/- 7. These CF-patients where the most severely affected in the investigated group, two of them were listed for complete heart and lung transplantation. The comparison of this subgroup and the remaining CF-patients revealed a highly significant difference for the AT (p = 0.000001) without overlap. CONCLUSION: Screening of CF-patients for the development of PH using MRvenc of the MPA is not possible. In later stages of disease, the quantification of AT, MFG and Dist in the MPA may be useful for the detection, follow-up and control of therapy of PH. MR(venc) of the MPA completes the MRI-based follow-up of lung parenchyma damage in patients suffering from CF.

Wolf T; Anjorin A; Posselt H; Smaczny C; Vogl TJ; Abolmaali N

2009-02-01

344

Using phytoplankton`s fluorescence for remote detection of radioactive pollutions in the ocean  

Energy Technology Data Exchange (ETDEWEB)

One of important ecological problems of our world is unfortunately radioactive pollutions in the ocean from sources of different types. For successful solving this problem it is important to locate precisely pollution areas using remote sensing methods. In the experiments performed we investigated the changes in fluorescence spectra of phytoplankton under an action of radiation. For this purpose we compared fluorescence spectra of samples of phytoplankton`s that were grown and maintained under the same conditions (light temperature, etc.) and the only difference between these samples was different radioactive doze obtained. Gamma irradiations of the samples was performed by bremsstrahlung of 30 Mev electrons or gamma-rays from (Ra-Be)- neutron source. To obtain reliable quantitative results the samples were simultaneously irradiated at different distances from the bremsstrahlung target or radioactive source. In such a way we could avoid possible errors due to different state of phytoplankton and temporal changes of gamma-radiation. The fluorescence spectra of phytoplankton were exited with a nitrogen laser emitting at 337 nm. An optical system focused fluorescence onto the entry slit of the polychromator of optical multichannel spectrum analyzer. A diffraction grating with a relatively weak dispersion (150 lines/mm) was used to record simultaneously spectra in a rather wide range of wavelengths (370-720 nm). We found in our experiments that very characteristic changes were relevant in fluorescence spectra of phytoplankton under radioactive influence in registered range of wavelength. Thus it is possible to use active and passive remote sensing methods of registration of phytoplankton`s fluorescence for express remote location areas of radioactive pollutions in the ocean from satellites or aircrafts.

Tsipenyuk, D.Yu. [Institute of General Physics Russian Academy of Sciences, Moscow (Russian Federation)

1996-08-01

345

Contribution of the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI to Dynamic MRI in the detection of hypovascular small (?2 cm) HCC in cirrhosis  

International Nuclear Information System (INIS)

To prospectively assess the additional value of the hepatobiliary (HB) phase of Gd-EOB-DTPA-MRI in identifying and characterising small (?2 cm) hepatocellular carcinomas (HCCs) undetermined in dynamic phases alone because of their atypical features, according to the AASLD criteria. 127 cirrhotic patients were evaluated with Gd-EOB-DTPA-MRI in two sets: unenhanced and dynamic phases; unenhanced, dynamic and HB phases. Sixty-two out of 215 nodules (29%) were atypical in 42 patients (33%). 62 atypical nodules were reported at histology: high-grade dysplastic nodules (HGDN)/early HCC (n = 20), low-grade DN (LGDN) (n = 21), regenerative nodules (n = 17) and nodular regenerative hyperplasia (n = 4). The sensitivity, specificity, accuracy, positive and negative predictive value (PPV, NPV) were increased by the addition of the HB phase: 88.4-99.4%, 88-95%, 88-98.5%, 97-99%, and 65-97.5%, respectively. Twenty atypical nodules were malignant (32%), 19 of which were characterised only during the HB phase. The HB phase is 11% more sensitive in the classification of HGDN/early HCC than dynamic MRI, with an added value of 32.5% in the NPV. The high incidence (33%) of atypical nodules and their frequent malignancy (32%) suggest the widespread employment of Gd-EOB-DTPA-MRI in the follow-up of small nodules (?2 cm) in cirrhosis. (orig.)

2011-01-01

346

Contribution of the hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI to Dynamic MRI in the detection of hypovascular small ({<=}2 cm) HCC in cirrhosis  

Energy Technology Data Exchange (ETDEWEB)

To prospectively assess the additional value of the hepatobiliary (HB) phase of Gd-EOB-DTPA-MRI in identifying and characterising small ({<=}2 cm) hepatocellular carcinomas (HCCs) undetermined in dynamic phases alone because of their atypical features, according to the AASLD criteria. 127 cirrhotic patients were evaluated with Gd-EOB-DTPA-MRI in two sets: unenhanced and dynamic phases; unenhanced, dynamic and HB phases. Sixty-two out of 215 nodules (29%) were atypical in 42 patients (33%). 62 atypical nodules were reported at histology: high-grade dysplastic nodules (HGDN)/early HCC (n = 20), low-grade DN (LGDN) (n = 21), regenerative nodules (n = 17) and nodular regenerative hyperplasia (n = 4). The sensitivity, specificity, accuracy, positive and negative predictive value (PPV, NPV) were increased by the addition of the HB phase: 88.4-99.4%, 88-95%, 88-98.5%, 97-99%, and 65-97.5%, respectively. Twenty atypical nodules were malignant (32%), 19 of which were characterised only during the HB phase. The HB phase is 11% more sensitive in the classification of HGDN/early HCC than dynamic MRI, with an added value of 32.5% in the NPV. The high incidence (33%) of atypical nodules and their frequent malignancy (32%) suggest the widespread employment of Gd-EOB-DTPA-MRI in the follow-up of small nodules ({<=}2 cm) in cirrhosis. (orig.)

Golfieri, Rita; Renzulli, Matteo; Lucidi, Vincenzo; Corcioni, Beniamino [University of Bologna, Radiology Unit, Department of Digestive Diseases and Internal Medicine, Sant' Orsola-Malpighi Hospital, Bologna (Italy); Trevisani, Franco [University of Bologna, Unit of Semeiotica, Department of Digestive Diseases and Internal Medicine, Sant' Orsola-Malpighi Hospital, Bologna (Italy); Bolondi, Luigi [University of Bologna, Unit of Internal Medicine, Department of Digestive Diseases and Internal Medicine, Sant' Orsola-Malpighi Hospital, Bologna (Italy)

2011-06-15

347

Detectability of low and intermediate or high risk prostate cancer with combined T2-weighted and diffusion-weighted MRI  

International Nuclear Information System (INIS)

To evaluate the incremental value of diffusion-weighted imaging (DWI) in combination with T2-weighted imaging to detect low (Gleason score, ? 6) and intermediate or high risk (Gleason score, ? 7) prostate cancer. Fifty-one patients who underwent MRI before prostatectomy were evaluated. Two readers independently scored the probability of tumour in eight regions of prostate on T2-weighted images (T2WI) and T2WI combined with apparent diffusion coefficient (ADC) maps. Data were divided into two groups - low risk and intermediate or high risk prostate cancer - and correlated with histopathological results. Diagnostic performance parameters, areas under the receiver-operating characteristic curve (AUCs) and interreader agreement were calculated. For both readers, AUCs of combined T2WI and ADC maps were greater than those of T2WI in intermediate or high risk (reader 1, 0.887 vs. 0.859; reader 2, 0.732 vs 0.662, P 0.05) prostate cancers. Weighted ? value of combined T2WI and ADC maps was 0.689. The addition of DWI to T2-weighted imaging improves the accuracy of detecting intermediate or high risk prostate cancers, but not for low risk prostate cancer detection. (orig.)

2012-01-01

348

A simple method for detecting tumor in T2-weighted MRI brain images. An image-based analysis  

International Nuclear Information System (INIS)

[en] The objective of this paper is to present a decision support system which uses a computer-based procedure to detect tumor blocks or lesions in digitized medical images. The authors developed a simple method with a low computation effort to detect tumors on T2-weighted Magnetic Resonance Imaging (MRI) brain images, focusing on the connection between the spatial pixel value and tumor properties from four different perspectives: cases having minuscule differences between two images using a fixed block-based method, tumor shape and size using the edge and binary images, tumor properties based on texture values using spatial pixel intensity distribution controlled by a global discriminate value, and the occurrence of content-specific tumor pixel for threshold images. Measurements of the following medical datasets were performed: different time interval images, and different brain disease images on single and multiple slice images. Experimental results have revealed that our proposed technique incurred an overall error smaller than those in other proposed methods. In particular, the proposed method allowed decrements of false alarm and missed alarm errors, which demonstrate the effectiveness of our proposed technique. In this paper, we also present a prototype system, known as PCB, to evaluate the performance of the proposed methods by actual experiments, comparing the detection accuracy and system performance. (author)

2006-01-01

349

Detection of lymph node in the neck and superior mediastinal area in the cases of esophageal cancer using magnetic resonance imaging (MRI)  

Energy Technology Data Exchange (ETDEWEB)

We devised the following three imaging plane of MRI for detection of lymph nodes in the neck and superior mediastinal area. Those are carotid artery plane, trachea-bronchus plane and trachea-axial plane. MRI was performed in 42 patients of esophageal cancer. This method was useful for a classification of lymph nodes on the basis of ``Guide Lines for the Clinical and Pathologic Studies on Carcinoma of Esophagus`` by Japanese Society for Esophageal Diseases, because the structure which became a border line was visualized distinctly. The detectability of lymph nodes according to size was 22.5% (less than 5 mm), 70.0% (more than 5 mm and less than 10 mm) and 80.1% (more than 10 mm). The highly detectable locations were cervical paraesophageal, deep cervical, supraclavicular, thoracic paraesophageal and thoracheal bifurcational lymph nodes. Compared with EUS and Dynamic CT, the detectability of lymph nodes by this method (MRI) was statistically significantly higher, and that of metastatic ones was superior, too. Thus, it was found that identification of lymph nodes by the location and the size can be easy using three planes of MRI, and that we can reveal the positional relationship between lymph nodes and the adjacent organs such as the trachea or large vessels. (author)

Yano, Yoshimasa [Chiba Univ. (Japan). School of Medicine

1998-12-01

350

MRI preclinical detection and asymptomatic course of a progressive multifocal leucoencephalopathy (PML) under natalizumab therapy.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Early detection of progressive multifocal leucoencephalopathy (PML) in the setting of natalizumab therapy currently is performed by rapid evaluation of new symptoms occurring in treated patients. The role of MR scanning has not been investigated but holds promise since MR detection is highly sensiti...

Phan-Ba, Rémy; LOMMERS, Emilie; TSHIBANDA, Luaba; CALAY, Philippe; DUBOIS, Bernard; Moonen, Gustave; Clifford, David

351

Overview of the iCATSI multi-pixels standoff chemical detection sensor and the MR-i imaging spectroradiometer  

Science.gov (United States)

ABB Bomem is expanding its line of infrared remote sensing products with the addition of a new imaging spectroradiometer. The instrument is modular and support several configurations. One of its configurations is a multipixels sensor optimised for differential acquisition in the VLWIR to support research related to chemical detection. In that configuration, the instrument is equipped with a dual-input telescope to perform optical background subtraction. The resulting signal is the differential between the spectral radiance entering each input port. The other configuration is a general purpose imaging spectroradiometer designed to acquire the spectral signature of rapid events and fast targets in infrared. Overview of the design and results from tests and first field trials will be presented.

Prel, Florent; Moreau, Louis; Lavoie, Hugo; Bouffard, François; Vallières, Christian; Roy, Claude; Levesque, Luc

2010-10-01

352

Whole body MRI and fluorescent microscopy for detection of stem cells labeled with superparamagnetic iron oxide (SPIO) nanoparticles and DiI following intramuscular and systemic delivery.  

UK PubMed Central (United Kingdom)

Methods to monitor transplanted stem cells in vivo are of great importance for potential therapeutic applications. Of particular interest are methods allowing noninvasive detection of stem cells throughout the body. Magnetic resonance imaging (MRI) is a tool that would allow detection of cells in nearly any tissue in the body and is already commonly used in the clinic. MRI tracking of stem cells is therefore feasible and likely to be easily adapted to patients receiving donor cells. Patients with Duchenne muscular dystrophy are good candidates for stem cell therapy, given the naturally regenerative nature of skeletal muscle, which repairs damage by employing endogenous stem cells from the muscle interstitium to regenerate muscle fibers throughout adulthood. We describe methods for labeling stem cells with superparamagnetic iron oxide nanoparticles (SPIO) to enhance MRI contrast, injecting them locally into skeletal and cardiac muscle, or systemically in mouse models for Duchenne muscular dystrophy, and tracking them in muscle tissue of live mice following injection. We focus on the use of whole body MRI to detect stem cells, as this is necessary for conditions such as muscular dystrophy, in which affected tissues are present throughout the body and systemic delivery of stem cells may be necessary. Emphasis is placed on the development of an MRI coil that is field of view (FOV) adjustable and can be used for both whole body imaging to determine stem cell localization as well as subsequent focusing on smaller, local regions where stem cells are present to obtain high-resolution images. We discuss the coil design and its significance for stem cell tracking. We also describe methods for labeling stem cells with a fluorescent dye and for tracking them in postmortem tissue specimens with fluorescent microscopy to correlate, compare, and contrast with results of whole body MRI in preclinical studies.

Odintsov B; Chun JL; Berry SE

2013-01-01

353

Phosphonate-modified Gd-DTPA complexes. III: The detection of myocardial infarction by MRI.  

Science.gov (United States)

The potential of a phosphonate-modified-Gd-DTPA for MR image enhancement of myocardial infarction has been demonstrated in imaging experiments on rats. The agent, 1-hydroxy-3-aminopropane-1,1-diphosphonate-modified-Gd-DTPA (Gd-DTPA-HPDP) accumulates in two models of myocardial infarction, (i.e., drug-induced diffusely infarcted whole hearts and in focal acute myocardial infarction from a left coronary artery ligation). The time course of the accumulation of the agent in the focal model of infarction and subsequent washout has also been followed in vitro. Results of this kinetics demonstrate that the agent first perfuses all normal fluid spaces and then slowly diffuses into the occluded zone where it is retained for a prolonged period, in sufficient quantities to be useful as an MRI contrast agent. Wash-out of the agent from normal myocardium is fast and complete with MR signal returning to background in minutes. The specificity of Gd-DTPA-HPDP for soft-tissue calcification and its retention within the infarcts permitted imaging at 1 to 2 h postinjection, (after unbound material has cleared the normal tissues). Infarcted tissue appeared as regions of increased signal intensity in T1-weighted images (> 200% enhancement), and correlated with histopathology. Unmodified Gd-DTPA was not retained under identical conditions. Gd-DTPA-HPDP permits a more accurate infarct delineation than is possible with the unmodified agent. PMID:8464367

Adzamli, I K; Blau, M; Pfeffer, M A; Davis, M A

1993-04-01

354

Phosphonate-modified Gd-DTPA complexes. III: The detection of myocardial infarction by MRI.  

UK PubMed Central (United Kingdom)

The potential of a phosphonate-modified-Gd-DTPA for MR image enhancement of myocardial infarction has been demonstrated in imaging experiments on rats. The agent, 1-hydroxy-3-aminopropane-1,1-diphosphonate-modified-Gd-DTPA (Gd-DTPA-HPDP) accumulates in two models of myocardial infarction, (i.e., drug-induced diffusely infarcted whole hearts and in focal acute myocardial infarction from a left coronary artery ligation). The time course of the accumulation of the agent in the focal model of infarction and subsequent washout has also been followed in vitro. Results of this kinetics demonstrate that the agent first perfuses all normal fluid spaces and then slowly diffuses into the occluded zone where it is retained for a prolonged period, in sufficient quantities to be useful as an MRI contrast agent. Wash-out of the agent from normal myocardium is fast and complete w