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Sample records for active mri implants

  1. Finite volume analysis of temperature effects induced by active MRI implants: 2. Defects on active MRI implants causing hot spots

    Directory of Open Access Journals (Sweden)

    Grönemeyer Dietrich HW

    2006-05-01

    Full Text Available Abstract Background Active magnetic resonance imaging implants, for example stents, stent grafts or vena cava filters, are constructed as wireless inductively coupled transmit and receive coils. They are built as a resonator tuned to the Larmor frequency of a magnetic resonance system. The resonator can be added to or incorporated within the implant. This technology can counteract the shielding caused by eddy currents inside the metallic implant structure. This may allow getting diagnostic information of the implant lumen (in stent stenosis or thrombosis for example. The electro magnetic rf-pulses during magnetic resonance imaging induce a current in the circuit path of the resonator. A by material fatigue provoked partial rupture of the circuit path or a broken wire with touching surfaces can set up a relatively high resistance on a very short distance, which may behave as a point-like power source, a hot spot, inside the body part the resonator is implanted to. This local power loss inside a small volume can reach ¼ of the total power loss of the intact resonating circuit, which itself is proportional to the product of the resonator volume and the quality factor and depends as well from the orientation of the resonator with respect to the main magnetic field and the imaging sequence the resonator is exposed to. Methods First an analytical solution of a hot spot for thermal equilibrium is described. This analytical solution with a definite hot spot power loss represents the worst case scenario for thermal equilibrium inside a homogeneous medium without cooling effects. Starting with this worst case assumptions additional conditions are considered in a numerical simulation, which are more realistic and may make the results less critical. The analytical solution as well as the numerical simulations use the experimental experience of the maximum hot spot power loss of implanted resonators with a definite volume during magnetic resonance imaging

  2. A temperature sensor implant for active implantable medical devices for in vivo subacute heating tests under MRI.

    Science.gov (United States)

    Silemek, Berk; Acikel, Volkan; Oto, Cagdas; Alipour, Akbar; Aykut, Zaliha Gamze; Algin, Oktay; Atalar, Ergin

    2018-05-01

    To introduce a temperature sensor implant (TSI) that mimics an active implantable medical device (AIMD) for animal testing of MRI heating. Computer simulations and phantom experiments poorly represent potential temperature increases. Animal experiments could be a better model, but heating experiments conducted immediately after the surgery suffer from alterations of the thermoregulatory and tissue properties during acute testing conditions. Therefore, the aim of this study was to introduce a temperature sensor implant that mimics an AIMD and capable of measuring the electrode temperature after implantation of the device without any further intervention at any time after the surgery in an animal model. A battery-operated TSI, which resembled an AIMD, was used to measure the lead temperature and impedance and the case temperature. The measured values were transmitted to an external computer via a low-power Bluetooth communication protocol. In addition to validation experiments on the phantom, a sheep experiment was conducted to test the feasibility of the system in subacute conditions. The measurements had a maximum of 0.5°C difference compared to fiber-optic temperature probes. In vivo animal experiments demonstrated feasibility of the system. An active implant, which can measure its own temperature, was proposed to investigate implant heating during MRI examinations. Magn Reson Med 79:2824-2832, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  3. Convex optimization of MRI exposure for mitigation of RF-heating from active medical implants

    Science.gov (United States)

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2015-09-01

    Local RF-heating of elongated medical implants during magnetic resonance imaging (MRI) may pose a significant health risk to patients. The actual patient risk depends on various parameters including RF magnetic field strength and frequency, MR coil design, patient’s anatomy, posture, and imaging position, implant location, RF coupling efficiency of the implant, and the bio-physiological responses associated with the induced local heating. We present three constrained convex optimization strategies that incorporate the implant’s RF-heating characteristics, for the reduction of local heating of medical implants during MRI. The study emphasizes the complementary performances of the different formulations. The analysis demonstrates that RF-induced heating of elongated metallic medical implants can be carefully controlled and balanced against MRI quality. A reduction of heating of up to 25 dB can be achieved at the cost of reduced uniformity in the magnitude of the B1+ field of less than 5%. The current formulations incorporate a priori knowledge of clinically-specific parameters, which is assumed to be available. Before these techniques can be applied practically in the broader clinical context, further investigations are needed to determine whether reduced access to a priori knowledge regarding, e.g. the patient’s anatomy, implant routing, RF-transmitter, and RF-implant coupling, can be accepted within reasonable levels of uncertainty.

  4. MRI of orbital hydroxyapatite implants

    International Nuclear Information System (INIS)

    Flanders, A.E.; De Potter P.; Rao, V.M.; Tom, B.M.; Shields, C.L.; Shields, J.A.

    1996-01-01

    Our aim was to use MRI for the postsurgical assessment of a new form of integrated orbital implant composed of a porous calcium phosphate hydroxyapatite substrate. We studied ten patients 24-74 years of age who underwent enucleation and implantation of a hydroxyapatite ball; 5-13 months after surgery, each patient was examined by spin-echo MRI, with fat suppression and gadolinium enhancement. Fibrovascular ingrowth was demonstrated in all ten patients as areas of enhancement at the periphery of the hydroxyapatite sphere that extended to the center to a variable degree. The radiologist should aware of the MRI appearances of the coralline hydroxyapatite orbital implant since it is now widely used following enucleation. MRI is a useful means to determine successful incorporation of the substrate into the orbital tissues. The normal pattern of contrast enhancement should not be mistaken for recurrent tumor or infection. (orig.)

  5. Finite volume analysis of temperature effects induced by active MRI implants with cylindrical symmetry: 1. Properly working devices

    Directory of Open Access Journals (Sweden)

    Schnorr Jörg

    2005-04-01

    Full Text Available Abstract Background Active Magnetic Resonance Imaging implants are constructed as resonators tuned to the Larmor frequency of a magnetic resonance system with a specific field strength. The resonating circuit may be embedded into or added to the normal metallic implant structure. The resonators build inductively coupled wireless transmit and receive coils and can amplify the signal, normally decreased by eddy currents, inside metallic structures without affecting the rest of the spin ensemble. During magnetic resonance imaging the resonators generate heat, which is additional to the usual one described by the specific absorption rate. This induces temperature increases of the tissue around the circuit paths and inside the lumen of an active implant and may negatively influence patient safety. Methods This investigation provides an overview of the supplementary power absorbed by active implants with a cylindrical geometry, corresponding to vessel implants such as stents, stent grafts or vena cava filters. The knowledge of the overall absorbed power is used in a finite volume analysis to estimate temperature maps around different implant structures inside homogeneous tissue under worst-case assumptions. The "worst-case scenario" assumes thermal heat conduction without blood perfusion inside the tissue around the implant and mostly without any cooling due to blood flow inside vessels. Results The additional power loss of a resonator is proportional to the volume and the quality factor, as well as the field strength of the MRI system and the specific absorption rate of the applied sequence. For properly working devices the finite volume analysis showed only tolerable heating during MRI investigations in most cases. Only resonators transforming a few hundred mW into heat may reach temperature increases over 5 K. This requires resonators with volumes of several ten cubic centimeters, short inductor circuit paths with only a few 10 cm and a quality

  6. Finite volume analysis of temperature effects induced by active MRI implants with cylindrical symmetry: 1. Properly working devices.

    Science.gov (United States)

    Busch, Martin H J; Vollmann, Wolfgang; Schnorr, Jörg; Grönemeyer, Dietrich H W

    2005-04-08

    Active Magnetic Resonance Imaging implants are constructed as resonators tuned to the Larmor frequency of a magnetic resonance system with a specific field strength. The resonating circuit may be embedded into or added to the normal metallic implant structure. The resonators build inductively coupled wireless transmit and receive coils and can amplify the signal, normally decreased by eddy currents, inside metallic structures without affecting the rest of the spin ensemble. During magnetic resonance imaging the resonators generate heat, which is additional to the usual one described by the specific absorption rate. This induces temperature increases of the tissue around the circuit paths and inside the lumen of an active implant and may negatively influence patient safety. This investigation provides an overview of the supplementary power absorbed by active implants with a cylindrical geometry, corresponding to vessel implants such as stents, stent grafts or vena cava filters. The knowledge of the overall absorbed power is used in a finite volume analysis to estimate temperature maps around different implant structures inside homogeneous tissue under worst-case assumptions. The "worst-case scenario" assumes thermal heat conduction without blood perfusion inside the tissue around the implant and mostly without any cooling due to blood flow inside vessels. The additional power loss of a resonator is proportional to the volume and the quality factor, as well as the field strength of the MRI system and the specific absorption rate of the applied sequence. For properly working devices the finite volume analysis showed only tolerable heating during MRI investigations in most cases. Only resonators transforming a few hundred mW into heat may reach temperature increases over 5 K. This requires resonators with volumes of several ten cubic centimeters, short inductor circuit paths with only a few 10 cm and a quality factor above ten. Using MR sequences, for which the MRI

  7. Finite volume analysis of temperature effects induced by active MRI implants with cylindrical symmetry: 1. Properly working devices

    OpenAIRE

    Schnorr Jörg; Vollmann Wolfgang; Busch Martin HJ; Grönemeyer Dietrich HW

    2005-01-01

    Abstract Background Active Magnetic Resonance Imaging implants are constructed as resonators tuned to the Larmor frequency of a magnetic resonance system with a specific field strength. The resonating circuit may be embedded into or added to the normal metallic implant structure. The resonators build inductively coupled wireless transmit and receive coils and can amplify the signal, normally decreased by eddy currents, inside metallic structures without affecting the rest of the spin ensemble...

  8. Artifacts Quantification of Metal Implants in MRI

    Science.gov (United States)

    Vrachnis, I. N.; Vlachopoulos, G. F.; Maris, T. G.; Costaridou, L. I.

    2017-11-01

    The presence of materials with different magnetic properties, such as metal implants, causes distortion of the magnetic field locally, resulting in signal voids and pile ups, i.e. susceptibility artifacts in MRI. Quantitative and unbiased measurement of the artifact is prerequisite for optimization of acquisition parameters. In this study an image gradient based segmentation method is proposed for susceptibility artifact quantification. The method captures abrupt signal alterations by calculation of the image gradient. Then the artifact is quantified in terms of its extent by an automated cross entropy thresholding method as image area percentage. The proposed method for artifact quantification was tested in phantoms containing two orthopedic implants with significantly different magnetic permeabilities. The method was compared against a method proposed in the literature, considered as a reference, demonstrating moderate to good correlation (Spearman’s rho = 0.62 and 0.802 in case of titanium and stainless steel implants). The automated character of the proposed quantification method seems promising towards MRI acquisition parameter optimization.

  9. Metallic artifact in MRI after removal of orthopedic implants

    International Nuclear Information System (INIS)

    Bagheri, Mohammad Hadi; Hosseini, Mehrdad Mohammad; Emami, Mohammad Jafar; Foroughi, Amin Aiboulhassani

    2012-01-01

    Objective: The aim of the present study was to evaluate the metallic artifacts in MRI of the orthopedic patients after removal of metallic implants. Subjects and methods: From March to August 2009, 40 orthopedic patients operated for removal of orthopedic metallic implants were studied by post-operative MRI from the site of removal of implants. A grading scale of 0–3 was assigned for artifact in MR images whereby 0 was considered no artifact; and I–III were considered mild, moderate, and severe metallic artifacts, respectively. These grading records were correlated with other variables including the type, size, number, and composition of metallic devices; and the site and duration of orthopedic devices stay in the body. Results: Metallic susceptibly artifacts were detected in MRI of 18 of 40 cases (45%). Screws and pins in removed hardware were the most important factors for causing artifacts in MRI. The artifacts were found more frequently in the patients who had more screws and pins in the removed implants. Gender, age, site of implantation of the device, length of the hardware, composition of the metallic implants (stainless steel versus titanium), and duration of implantation of the hardware exerted no effect in producing metallic artifacts after removal of implants. Short TE sequences of MRI (such as T1 weighted) showed fewer artifacts. Conclusion: Susceptibility of metallic artifacts is a frequent phenomenon in MRI of patients upon removal of metallic orthopedic implants.

  10. Metallic artifact in MRI after removal of orthopedic implants.

    Science.gov (United States)

    Bagheri, Mohammad Hadi; Hosseini, Mehrdad Mohammad; Emami, Mohammad Jafar; Foroughi, Amin Aiboulhassani

    2012-03-01

    The aim of the present study was to evaluate the metallic artifacts in MRI of the orthopedic patients after removal of metallic implants. From March to August 2009, 40 orthopedic patients operated for removal of orthopedic metallic implants were studied by post-operative MRI from the site of removal of implants. A grading scale of 0-3 was assigned for artifact in MR images whereby 0 was considered no artifact; and I-III were considered mild, moderate, and severe metallic artifacts, respectively. These grading records were correlated with other variables including the type, size, number, and composition of metallic devices; and the site and duration of orthopedic devices stay in the body. Metallic susceptibly artifacts were detected in MRI of 18 of 40 cases (45%). Screws and pins in removed hardware were the most important factors for causing artifacts in MRI. The artifacts were found more frequently in the patients who had more screws and pins in the removed implants. Gender, age, site of implantation of the device, length of the hardware, composition of the metallic implants (stainless steel versus titanium), and duration of implantation of the hardware exerted no effect in producing metallic artifacts after removal of implants. Short TE sequences of MRI (such as T1 weighted) showed fewer artifacts. Susceptibility of metallic artifacts is a frequent phenomenon in MRI of patients upon removal of metallic orthopedic implants. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  11. MRI information for commonly used otologic implants: review and update.

    Science.gov (United States)

    Azadarmaki, Roya; Tubbs, Rhonda; Chen, Douglas A; Shellock, Frank G

    2014-04-01

    To review information on magnetic resonance imaging (MRI) issues for commonly used otologic implants. Manufacturing companies, National Library of Medicine's online database, and an additional online database (www.MRIsafety.com). A literature review of the National Library of Medicine's online database with focus on MRI issues for otologic implants was performed. The MRI information on implants provided by manufacturers was reviewed. Baha and Ponto Pro osseointegrated implants' abutment and fixture and the implanted magnet of the Sophono Alpha 1 and 2 abutment-free systems are approved for 3-Tesla magnetic resonance (MR) systems. The external processors of these devices are MR Unsafe. Of the implants tested, middle ear ossicular prostheses, including stapes prostheses, except for the 1987 McGee prosthesis, are MR Conditional for 1.5-Tesla (and many are approved for 3-Tesla) MR systems. Cochlear implants with removable magnets are approved for patients undergoing MRI at 1.5 Tesla after magnet removal. The MED-EL PULSAR, SONATA, CONCERT, and CONCERT PIN cochlear implants can be used in patients undergoing MRI at 1.5 Tesla with application of a protective bandage. The MED-EL COMBI 40+ can be used in 0.2-Tesla MR systems. Implants made from nonmagnetic and nonconducting materials are MR Safe. Knowledge of MRI guidelines for commonly used otologic implants is important. Guidelines on MRI issues approved by the US Food and Drug Administration are not always the same compared with other parts of the world. This monograph provides a current reference for physicians on MRI issues for commonly used otologic implants.

  12. Dislocation of cochlear implant magnet as a complication following MRI.

    Science.gov (United States)

    Murtojärvi, Sarita; Salonen, Jaakko

    According to current best knowledge, an MRI scan can be performed for patients with cochlear implants. The warnings and recommendations of the implant manufacturers must be followed strictly to prevent complications, such as overheating, migration or demagnetization of the magnet in the implant. We report on a case of cochlear implant magnet dislocation as a complication for an MRI scan. The patient had a tight bandage around the head to hold the magnet in place as recommended by the manufacturer, but apparently the bandage was not in the correct place.

  13. Chordoma with postoperative subcutaneous implantation and meningeal dissemination: MRI

    International Nuclear Information System (INIS)

    Kinoshita, T.; Okudera, T.; Shimosegawa, E.; Hatazawa, J.; Yoshida, Y.; Yasui, N.; Ogawa, T.

    2001-01-01

    Chordomas are histologically benign tumours which are locally invasive. We present an unusual case of recurrent chordoma with subcutaneous implantation and widespread meningeal dissemination after surgery. Contrast-enhanced MRI was useful for determining the extent of the tumour. (orig.)

  14. [MR implant labelling and its use in clinical MRI practice].

    Science.gov (United States)

    Mühlenweg, M; Schaefers, G

    2015-08-01

    Before a magnetic resonance imaging (MRI) examination, implants in patients must be cleared for MR safety in order to exclude the risk of possible severe injuries and implant malfunction in an MR environment. The general contraindication for measurements of patients with implants still applies; however, in the recent past a way has been found to legally circumvent this contraindication. For this purpose special conditions are required: explicit implant identification and the original manufacturer's labelling are necessary, the required conditions for conditionally MR safe implants must be assured and a risk-benefit analysis with appropriate explanation to the patient has to be performed. This process can be very complex as the implants are often poorly documented and detailed information on the implant MR labelling is also often outdated or not easy to interpret. This article provides information about legal and normative principles of MR measurement of patients with implants. The possible physical interactions with implants will be briefly dealt with as well as possible strategies for better identification and investigation of implants and MR labelling. General approaches for minimizing the risk will be discussed using some examples. The second part deals with the content of MR implant labelling and the current test standards. Furthermore, the additional information from the operating instructions of the MR scanner that are necessary for the interpretation of the MR implant labelling, will be explained. The article concludes with an explanation of the current pattern for MR labelling of implants from the U.S. Food and Drug Administration (FDA) and an exemplary application.

  15. MR implant labelling and its use in clinical MRI practice

    International Nuclear Information System (INIS)

    Muehlenweg, M.; Schaefers, G.

    2015-01-01

    Before a magnetic resonance imaging (MRI) examination, implants in patients must be cleared for MR safety in order to exclude the risk of possible severe injuries and implant malfunction in an MR environment. The general contraindication for measurements of patients with implants still applies; however, in the recent past a way has been found to legally circumvent this contraindication. For this purpose special conditions are required: explicit implant identification and the original manufacturer's labelling are necessary, the required conditions for conditionally MR safe implants must be assured and a risk-benefit analysis with appropriate explanation to the patient has to be performed. This process can be very complex as the implants are often poorly documented and detailed information on the implant MR labelling is also often outdated or not easy to interpret. This article provides information about legal and normative principles of MR measurement of patients with implants. The possible physical interactions with implants will be briefly dealt with as well as possible strategies for better identification and investigation of implants and MR labelling. General approaches for minimizing the risk will be discussed using some examples. The second part deals with the content of MR implant labelling and the current test standards. Furthermore, the additional information from the operating instructions of the MR scanner that are necessary for the interpretation of the MR implant labelling, will be explained. The article concludes with an explanation of the current pattern for MR labelling of implants from the U.S. Food and Drug Administration (FDA) and an exemplary application. (orig.) [de

  16. Correlation between MRI results and intraoperative findings in patients with silicone breast implants.

    Science.gov (United States)

    Lindenblatt, Nicole; El-Rabadi, Karem; Helbich, Thomas H; Czembirek, Heinrich; Deutinger, Maria; Benditte-Klepetko, Heike

    2014-01-01

    Silicone gel breast implants may silently rupture without detection. This has been the main reason for magnetic resonance imaging (MRI) of the augmented or reconstructed breast. The aim of the present study was to investigate the accuracy of MRI for implant rupture. Fifty consecutive patients with 85 silicone gel implants were included in the study. The mean age of the patients was 51 (range 21-72) years, with a mean duration of implantation of 3.8 (range 1-28) years. All patients underwent clinical examination and breast MRI. Intraoperative implant rupture was diagnosed by the operating surgeon. Nineteen of the 50 patients suffered from clinical symptoms. An implant rupture was diagnosed by MRI in 22 of 85 implants (26%). In seven of 17 removed implants (41%), the intraoperative diagnosis corresponded with the positive MRI result. However, only 57% of these patients were symptomatic. Ultrasound imaging of the harvested implants showed signs of interrupted inner layers of the implant despite integrity of the outer shell. By microsurgical separation of the different layers of the implant shell, we were able to reproduce this phenomenon and to produce signs of implant rupture on MRI. Our results show that rupture of only the inner layers of the implant shell with integrity of the outer shell leads to a misdiagnosis on MRI. Correlation with clinical symptoms and the specific wishes of the patient should guide the indication for implant removal.

  17. Correlation between MRI results and intraoperative findings in patients with silicone breast implants

    NARCIS (Netherlands)

    N. Lindenblatt (Nicole); K. El-Rabadi (Karem); T. Helbich (Thomas); H. Czembirek (Heinrich); M. Deutinger (Maria); H. Benditte-Klepetko (Heike)

    2014-01-01

    textabstractBackground:Silicone gel breast implants may silently rupture without detection. This has been the main reason for magnetic resonance imaging (MRI) of the augmented or reconstructed breast. The aim of the present study was to investigate the accuracy of MRI for implant rupture.

  18. Measurement, simulation and uncertainty assessment of implant heating during MRI

    International Nuclear Information System (INIS)

    Neufeld, E; Kuehn, S; Kuster, N; Szekely, G

    2009-01-01

    The heating of tissues around implants during MRI can pose severe health risks, and careful evaluation is required for leads to be labeled as MR conditionally safe. A recent interlaboratory comparison study has shown that different groups can produce widely varying results (sometimes with more than a factor of 5 difference) when performing measurements according to current guidelines. To determine the related difficulties and to derive optimized procedures, two different generic lead structures have been investigated in this study by using state-of-the-art temperature and dosimetric probes, as well as simulations for which detailed uncertainty budgets have been determined. The agreement between simulations and measurements is well within the combined uncertainty. The study revealed that the uncertainty can be kept below 17% if appropriate instrumentation and procedures are applied. Optimized experimental assessment techniques can be derived from the findings presented herein.

  19. Measurement, simulation and uncertainty assessment of implant heating during MRI

    Energy Technology Data Exchange (ETDEWEB)

    Neufeld, E; Kuehn, S; Kuster, N [Foundation for Research on Information Technologies in Society (IT' IS), Zeughausstr. 43, 8004 Zurich (Switzerland); Szekely, G [Computer Vision Laboratory, Swiss Federal Institute of Technology (ETHZ), Sternwartstr 7, ETH Zentrum, 8092 Zurich (Switzerland)], E-mail: neufeld@itis.ethz.ch

    2009-07-07

    The heating of tissues around implants during MRI can pose severe health risks, and careful evaluation is required for leads to be labeled as MR conditionally safe. A recent interlaboratory comparison study has shown that different groups can produce widely varying results (sometimes with more than a factor of 5 difference) when performing measurements according to current guidelines. To determine the related difficulties and to derive optimized procedures, two different generic lead structures have been investigated in this study by using state-of-the-art temperature and dosimetric probes, as well as simulations for which detailed uncertainty budgets have been determined. The agreement between simulations and measurements is well within the combined uncertainty. The study revealed that the uncertainty can be kept below 17% if appropriate instrumentation and procedures are applied. Optimized experimental assessment techniques can be derived from the findings presented herein.

  20. The diagnosis of breast implant rupture: MRI findings compared with findings at explantation

    International Nuclear Information System (INIS)

    Hoelmich, Lisbet R.; Vejborg, Ilse; Conrad, Carsten; Sletting, Susanne; McLaughlin, Joseph K.

    2005-01-01

    Study objective: The aim of this study was to evaluate the accuracy of Magnetic Resonance Imaging (MRI) as performed according to a strict study protocol in diagnosing rupture of silicone breast implants. Material and methods: The study population consisted of 64 women with 118 implants, who had participated in either one or two study MRI examinations, aiming at determining the prevalence and incidence of silent implant rupture, respectively, and who subsequently underwent explantation. Implant rupture status was determined by four independent readers and a consensus diagnosis of either rupture (intracapsular or extracapsular), possible rupture or intact implant was then obtained. Strict predetermined rupture criteria were applied as described in this report and findings at surgery were abstracted in a standardised manner and results compared. Results: At MRI, 66 implants were diagnosed as ruptured, nine as possibly ruptured and 43 as intact. Among the ruptured implants, 27 were categorized as extracapsular. At surgery, on average 297 days after the MRI, 65 of the 66 rupture diagnoses were confirmed, as were 20 of the cases with extracapsular silicone. Eight of the nine possibly ruptured implants were in fact ruptured at surgery. Thirty-four of the 43 intact implants were described as intact at surgery. When categorising possible ruptures as ruptures, there were one false positive and nine false negative rupture diagnoses at MRI yielding an accuracy of 92%, a sensitivity of 89%, and a specificity of 97%. Correspondingly, the predictive value of a positive MRI examination was 99% and the predictive value of a negative MRI examination was 79%. Conclusions: We conclude that MRI is highly accurate for identification of silicone breast implant rupture, with a high sensitivity and specificity when evaluation of images are based on presence of well-defined rupture criteria

  1. Cochlear implant with a non-removable magnet: preliminary research at 3-T MRI.

    Science.gov (United States)

    Dubrulle, F; Sufana Iancu, A; Vincent, C; Tourrel, G; Ernst, O

    2013-06-01

    To perform preliminary tests in vitro and with healthy volunteers to determine the 3-T MRI compatibility of a cochlear implant with a non-removable magnet. In the in vitro phase, we tested six implants for temperature changes and internal malfunctioning. We measured the demagnetisation of 65 internal magnets with different tilt angles between the implant's magnetic field (bi) and the main magnetic field (b0). In the in vivo phase, we tested 28 operational implants attached to the scalps of volunteers with the head in three different positions. The study did not find significant temperature changes or electronic malfunction in the implants tested in vitro. We found considerable demagnetisation of the cochlear implant magnets in the in vitro and in vivo testing influenced by the position of the magnet in the main magnetic field. We found that if the bi/b0 angle is 90°, there is demagnetisation in almost 60 % of the cases. When the angle is around 90°, the risk of demagnetisation is low (6.6 %). The preliminary results on cochlear implants with non-removable magnets indicate the need to maintain the contraindication of passage through 3-T MRI. • Magnetic resonance imaging can affect cochlear implants and vice versa. • Demagnetisation of cochlear implant correlates with the angle between bi and b0. • The position of the head in the MRI influences the demagnetisation. • Three-Tesla MRI for cochlear implants is still contraindicated. • However some future solutions are discussed.

  2. MRI

    Science.gov (United States)

    ... the room. Pins, hairpins, metal zippers, and similar metallic items can distort the images. Removable dental work ... an MRI can cause heart pacemakers and other implants not to work as well. The magnets can ...

  3. MRI evaluation of post-mastectomy irradiated breast implants: prevalence and analysis of complications.

    Science.gov (United States)

    Rella, L; Telegrafo, M; Nardone, A; Milella, A; Stabile Ianora, A A; Lioce, M; Angelelli, G; Moschetta, M

    2015-09-01

    To evaluate the effect of post-mastectomy radiation therapy (RT) on breast implants as detected by magnetic resonance imaging (MRI) searching for short-term complications. One hundred and forty patients (total of 144 implants) were evaluated by MRI; 80 (group 1) had undergone RT, whereas the remaining 60 patients (group 2) underwent mastectomy with implant reconstruction without RT. Two radiologists evaluated MRI images searching for implant rupture signs, sub-capsular seromas, capsular contracture, soft-tissue oedema, peri-implant fluid collections. Implant ruptures were classified as severe complications; seromas and capsular contractures as moderate complications; oedema and fluid collections as mild complications. The prevalence of MRI findings in the two groups was calculated and compared by unpaired t-test. Cohen's kappa statistics was used to assess interobserver agreement. Sixty-nine out of 144 (48%) implants presented pathological findings at MRI with complication rates of 47.5 and 48.4 for groups 1 and 2, respectively. Two (5%) severe complications, 10 (26%) moderate complications, and 26 (69%) mild complications occurred in group 1 and surgical treatment was performed in 10 cases. Two (6%) severe complications, seven (23%) moderate complications, and 22 (71%) mild complications occurred in group 2 and surgical treatment was performed in eight cases. No significant difference between the two groups was found (p>0.1). Almost perfect agreement between the two radiologists was found for MRI image detection (k=0.86). RT does not seem to cause a significant effect on breast implants in terms of complication rate in patients undergoing implant-based breast reconstruction. One-stage immediate implant-based breast reconstruction performed at the same time as mastectomy could be proposed. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  4. Correlation between MRI results and intraoperative findings in patients with silicone breast implants

    Directory of Open Access Journals (Sweden)

    Lindenblatt N

    2014-07-01

    Full Text Available Nicole Lindenblatt,1 Karem El-Rabadi,2 Thomas H Helbich,2 Heinrich Czembirek,3 Maria Deutinger,4 Heike Benditte-Klepetko5 1Division of Plastic and Hand Surgery, Department of Surgery, University Hospital Zurich, Zurich, Switzerland; 2Department of Biomedical Imaging and Image-guided Therapy, Division of Molecular and Gender Imaging, Medical University of Vienna - General Hospital Vienna, 3Department of Radiology, Hospital Wiener Privatklinik, 4Department of Plastic and Reconstructive Surgery, Hospital Rudolfstiftung, Vienna, Austria; 5Department of Plastic and Reconstructive Surgery, Erasmus Medical Center, Rotterdam, the Netherlands Background: Silicone gel breast implants may silently rupture without detection. This has been the main reason for magnetic resonance imaging (MRI of the augmented or reconstructed breast. The aim of the present study was to investigate the accuracy of MRI for implant rupture. Methods: Fifty consecutive patients with 85 silicone gel implants were included in the study. The mean age of the patients was 51 (range 21–72 years, with a mean duration of implantation of 3.8 (range 1–28 years. All patients underwent clinical examination and breast MRI. Intraoperative implant rupture was diagnosed by the operating surgeon. Results: Nineteen of the 50 patients suffered from clinical symptoms. An implant rupture was diagnosed by MRI in 22 of 85 implants (26%. In seven of 17 removed implants (41%, the intraoperative diagnosis corresponded with the positive MRI result. However, only 57% of these patients were symptomatic. Ultrasound imaging of the harvested implants showed signs of interrupted inner layers of the implant despite integrity of the outer shell. By microsurgical separation of the different layers of the implant shell, we were able to reproduce this phenomenon and to produce signs of implant rupture on MRI. Conclusion: Our results show that rupture of only the inner layers of the implant shell with integrity of

  5. Value of contrast-enhanced MRI of breast after silicone implant

    International Nuclear Information System (INIS)

    Heinig, A.; Heywang-Koebrunner, S.H.; Viehweg, P.; Spielmann, R.P.; Lampe, D.; Buchmann, J.

    1997-01-01

    Early recognition of recurrence and work-up of clinically indeterminate lesions may be impaired after reconstruction with silicone implants due to superimposition of the implant or to scarring. This study was undertaken to evaluate the use of contrast-enhanced MRI in patients with silicone implant after breast cancer. Contrast-enhanded MRI was offered to 169 patients. Comparative two- to three-view mammography was also performed in 169 patients, as well as comparative sonography in 144 patients. Conventional imaging and clinical examination detected only 8/13 recurrences, whereas 12/13 were detected by MRI. One recurrence had been visible as a strongly enhancing 2-mm dot in a previous examination (2 years before), but was not called. It was therefore counted as false negative. In addition, multicentricity was detected by MRI alone in two of three cases. MRI correctly diagnosed scar tissue in all cases with indeterminate findings. However, due to false-positive calls caused by enhancing granulomas specificity could not be improved. Contrast-enhanded MRI allowed decisive additional information in our study group and improved the sensitivity significantly (concerning all diagnoses). Contrast-enhanded MRI allowed decisive additional information in our study group and improved the sensitivity significantly (concerning all diagnoses). Contrast-enhanded MRI is recommended in patients with diagnostic problems or high risk of recurrence after silicone implants. (orig.) [de

  6. Active implants and scaffolds for tissue regeneration

    CERN Document Server

    Zilberman, Meital

    2011-01-01

    Active implants are actually drug or protein-eluting implants that induce healing effects, in addition to their regular task, such as support. This book gives a broad overview of biomaterial platforms used as basic elements of drug-eluting implants.

  7. MRI evaluation of post-mastectomy irradiated breast implants: prevalence and analysis of complications

    International Nuclear Information System (INIS)

    Rella, L.; Telegrafo, M.; Nardone, A.; Milella, A.; Ianora, A.A. Stabile; Lioce, M.; Angelelli, G.; Moschetta, M.

    2015-01-01

    Aim: To evaluate the effect of post-mastectomy radiation therapy (RT) on breast implants as detected by magnetic resonance imaging (MRI) searching for short-term complications. Materials and methods: One hundred and forty patients (total of 144 implants) were evaluated by MRI; 80 (group 1) had undergone RT, whereas the remaining 60 patients (group 2) underwent mastectomy with implant reconstruction without RT. Two radiologists evaluated MRI images searching for implant rupture signs, sub-capsular seromas, capsular contracture, soft-tissue oedema, peri-implant fluid collections. Implant ruptures were classified as severe complications; seromas and capsular contractures as moderate complications; oedema and fluid collections as mild complications. The prevalence of MRI findings in the two groups was calculated and compared by unpaired t-test. Cohen's kappa statistics was used to assess interobserver agreement. Results: Sixty-nine out of 144 (48%) implants presented pathological findings at MRI with complication rates of 47.5 and 48.4 for groups 1 and 2, respectively. Two (5%) severe complications, 10 (26%) moderate complications, and 26 (69%) mild complications occurred in group 1 and surgical treatment was performed in 10 cases. Two (6%) severe complications, seven (23%) moderate complications, and 22 (71%) mild complications occurred in group 2 and surgical treatment was performed in eight cases. No significant difference between the two groups was found (p>0.1). Almost perfect agreement between the two radiologists was found for MRI image detection (k=0.86). Conclusion: RT does not seem to cause a significant effect on breast implants in terms of complication rate in patients undergoing implant-based breast reconstruction. One-stage immediate implant-based breast reconstruction performed at the same time as mastectomy could be proposed. -- Highlights: •RT could increase complication rates of implant-based breast reconstruction (IBR). •No general consensus

  8. MRI image characteristics of materials implanted at sellar region after transsphenoidal resection of pituitary tumours

    International Nuclear Information System (INIS)

    Bladowska, J.; Sasiadek, M.; Bednarek-Tupikowska, G.; Sokolska, V.; Badowski, R.; Moron, K.; Bonicki, W.

    2010-01-01

    Background: Post-surgical evaluation of the pituitary gland in MRI is difficult because of a change in anatomical conditions. It depends also on numerous other factors, including: size and expansion of the tumour before surgery, type of surgical access, quality and volume of implanted materials and time of its resorption. The purpose was to demonstrate the characteristics of the implanted materials on MRI performed after transsphenoidal resection of pituitary tumours and to identify imaging criteria helpful in differential diagnosis of masses within the sellar region. Material/Methods: One hundred and fifty-four patients after transsphenoidal resection of pituitary tumours were included in the study. In general, 469 MRI examinations were performed with a 1.5 T scanner. We obtained T1-weighted sagittal and coronal, enhanced and unenhanced images. In 102 cases, additional T2-weighted coronal, unenhanced images with 1.5 T unit were obtained as well. Results: The implanted materials appeared in 95 patient: fat in 86 and muscle with fascia in 3 patients. We could recognise implanted muscle and fascia in T2-weighted images, because of high signal intensity of the degenerating muscle and the line of low signal representing fascia. The implanted titanium mesh was found in 4 patients. Haemostatic materials were visible only in 2 patients in examinations performed at an early postoperative stage (1 month after the procedure). Conclusions: The knowledge of MRI characteristics of the materials implanted at the sellar region is very important in postoperative diagnosis of pituitary tumours and may help discriminate between tumorous and non-tumorous involvement of the sellar region. Some implanted materials, like fat, could be seen on MRI for as long as 10 years after the operation, others, like haemostatic materials, for only 1 month after surgery. T2-weighted imaging is a useful assessment method of the implanted muscle and fascia for a long time after surgery. (authors)

  9. Magnet dislocation: an increasing and serious complication following MRI in patients with cochlear implants.

    Science.gov (United States)

    Hassepass, F; Stabenau, V; Arndt, S; Beck, R; Bulla, S; Grauvogel, T; Aschendorff, A

    2014-07-01

    Cochlear implantation (CI) represents the gold standard in the treatment of children born deaf and postlingually deafened adults. Initial magnetic resonance imaging (MRI) was contraindicated in CI users. Meanwhile, there are specific recommendations concerning MRI compatibility depending on the type of CI system and the device manufacturer. Some CI systems are even approved for MRI with the internal magnet left in place. The aim of this study was to analyze all magnet revision surgeries in CI patients at one CI center and the relationship to MRI scans over time. Between 2000 and 2013, a total of 2027 CIs were implanted. The number of magnet dislocation (MD) surgeries and their causes was assessed retrospectively. In total 12 cases of MD resulting from an MRI scan (0.59 %) were observed, accounting for 52.2 % of all magnetic revision surgeries. As per the labeling, it was considered safe to leave the internal magnet in place during MRI while following specific manufacturer recommendations: MRI intensity of 1.5 Tesla (T) and compression head bandage during examination. A compression head bandage in a 1.5 T MRI unit does not safely prevent MD and the related serious complications in CI recipients. We recommend a Stenvers view radiograph after MRI with the internal magnet in place for early identification of MD, at least in the case of pain during or after MRI examination. MRI in CI patients should be indicated with restraint and patients should be explicitly informed about the possible risks. Recommendations regarding MRI compatibility and the handling of CI patients issued with MRI for the most common CI systems are summarized. © Georg Thieme Verlag KG Stuttgart · New York.

  10. fMRI as a Preimplant Objective Tool to Predict Postimplant Oral Language Outcomes in Children with Cochlear Implants.

    Science.gov (United States)

    Deshpande, Aniruddha K; Tan, Lirong; Lu, Long J; Altaye, Mekibib; Holland, Scott K

    2016-01-01

    Despite the positive effects of cochlear implantation, postimplant variability in speech perception and oral language outcomes is still difficult to predict. The aim of this study was to identify neuroimaging biomarkers of postimplant speech perception and oral language performance in children with hearing loss who receive a cochlear implant. The authors hypothesized positive correlations between blood oxygen level-dependent functional magnetic resonance imaging (fMRI) activation in brain regions related to auditory language processing and attention and scores on the Clinical Evaluation of Language Fundamentals-Preschool, Second Edition (CELF-P2) and the Early Speech Perception Test for Profoundly Hearing-Impaired Children (ESP), in children with congenital hearing loss. Eleven children with congenital hearing loss were recruited for the present study based on referral for clinical MRI and other inclusion criteria. All participants were stimulation. A voxel-based analysis technique was utilized to generate z maps showing significant contrast in brain activation between auditory stimulation conditions (spoken narratives and narrow band noise). CELF-P2 and ESP were administered 2 years after implantation. Because most participants reached a ceiling on ESP, a voxel-wise regression analysis was performed between preimplant fMRI activation and postimplant CELF-P2 scores alone. Age at implantation and preimplant hearing thresholds were controlled in this regression analysis. Four brain regions were found to be significantly correlated with CELF-P2 scores. These clusters of positive correlation encompassed the temporo-parieto-occipital junction, areas in the prefrontal cortex and the cingulate gyrus. For the story versus silence contrast, CELF-P2 core language score demonstrated significant positive correlation with activation in the right angular gyrus (r = 0.95), left medial frontal gyrus (r = 0.94), and left cingulate gyrus (r = 0.96). For the narrow band noise versus

  11. Sporting Activity Is Reduced 11 Years After First-Generation Autologous Chondrocyte Implantation in the Knee Joint

    DEFF Research Database (Denmark)

    Erdle, Benjamin; Herrmann, Simon; Porichis, Stella

    2017-01-01

    BACKGROUND: Little is known about long-term sporting activity after periosteal autologous chondrocyte implantation (ACI-P) and its correlation to clinical, morphological, and ultrastructural cartilage characteristics on magnetic resonance imaging (MRI). PURPOSE: To evaluate long-term sporting...

  12. Study of breast implant rupture: MRI versus surgical findings.

    Science.gov (United States)

    Vestito, A; Mangieri, F F; Ancona, A; Minervini, C; Perchinunno, V; Rinaldi, S

    2012-09-01

    This study evaluated the role of breast magnetic resonance (MR) imaging in the selective study breast implant integrity. We retrospectively analysed the signs of breast implant rupture observed at breast MR examinations of 157 implants and determined the sensitivity and specificity of the technique in diagnosing implant rupture by comparing MR data with findings at surgical explantation. The linguine and the salad-oil signs were statistically the most significant signs for diagnosing intracapsular rupture; the presence of siliconomas/seromas outside the capsule and/or in the axillary lymph nodes calls for immediate explantation. In agreement with previous reports, we found a close correlation between imaging signs and findings at explantation. Breast MR imaging can be considered the gold standard in the study of breast implants.

  13. Cerebral activity mapped by functional MRI

    International Nuclear Information System (INIS)

    Bruening, R.; Danek, A.; Wu, R.H.; Berchtenbreiter, C.; Reiser, M.

    1997-01-01

    Functional magnetic resonance imaging (fMRI) is a method to noninvasively measure the changes in cerebral activation during sensitive, cognitive or motor activity. fMRI detects activity by subtraction of states of activity and rest. During activity the signal is increased presumably due to a decrease of deoxyhemoglobin in the capillary and venous structures. Using a full field visual stimulation by flashlight goggles, a signal increase of 3% was detected in the primary visual cortex (V1). Different sequences and postprocessing algorythms will be discussed. Data from the primary cortical areas suggest a high reproducability of the experiments. Successfull experiments highly depend on cooperation of subjects. Despite success in experiments fMRI still has to be established for clinical purposes. (orig.) [de

  14. MRI assessment of thoracic stent grafts after emergency implantation in multi trauma patients: a feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Rasche, Volker [University Hospital Ulm, Department of Internal Medicine II, Ulm (Germany); University Hospital Ulm, University of Ulm, Department of Internal Medicine II, Ulm (Germany); Oberhuber, Alexander; Orend, Karl-Heinz [University Hospital Ulm, Department of Vascular and Thoracic Surgery, Ulm (Germany); Trumpp, Stephan [University Hospital Ulm, Department of Internal Medicine II, Ulm (Germany); University Hospital Ulm, Department of Vascular and Thoracic Surgery, Ulm (Germany); Bornstedt, Axel; Merkle, Nico; Rottbauer, Wolfgang [University Hospital Ulm, Department of Internal Medicine II, Ulm (Germany); Hoffmann, Martin [University Hospital Ulm, Department of Diagnostic and Interventional Radiology, Ulm (Germany)

    2011-07-15

    To evaluate the feasibility of MRI for static and dynamic assessment of the deployment of thoracic aortic stent grafts after emergency implantation in trauma patients. Twenty patients initially presenting with a rupture of the thoracic aorta were enrolled in this study. All patients underwent thoracic endovascular aortic repair (TEVAR). The deployment of the implanted stent graft was assessed by CTA and MRI, comprising the assessment of the aortic arch with and without contrast agent, and the assessment of the motion of the stent graft over the cardiac cycle. The stent graft geometry and motion over the cardiac cycle were assessable by MRI in all patients. Flow-mediated signal variations in areas of flow acceleration could be well visualised. No statistically significant differences in stent-graft diameters were observed between CT and MRI measurements. MRI appears to be a valuable tool for the assessment of thoracic stent grafts. It shows similar performance in the accurate assessment of stent-graft dimensions to the current gold standard CTA. Its capability of providing additional functional information and the lack of ionising radiation and nephrotoxic contrast agents may make MRI a valuable tool for monitoring patients after TEVAR. (orig.)

  15. MRI screening for silicone breast implant rupture: accuracy, inter- and intraobserver variability using explantation results as reference standard

    Energy Technology Data Exchange (ETDEWEB)

    Maijers, M.C.; Ritt, M.J.P.F. [VU University Medical Centre, Department of Plastic, Reconstructive and Hand Surgery, De Boelelaan 1117, PO Box 7057, Amsterdam (Netherlands); Niessen, F.B. [VU University Medical Centre, Department of Plastic, Reconstructive and Hand Surgery, De Boelelaan 1117, PO Box 7057, Amsterdam (Netherlands); Jan van Goyen Clinic, Department of Plastic Surgery, Amsterdam (Netherlands); Veldhuizen, J.F.H. [MRI Centre, Amsterdam (Netherlands); Manoliu, R.A. [MRI Centre, Amsterdam (Netherlands); VU University Medical Centre, Department of Radiology, Amsterdam (Netherlands)

    2014-06-15

    The recall of Poly Implant Prothese (PIP) silicone breast implants in 2010 resulted in large numbers of asymptomatic women with implants who underwent magnetic resonance imaging (MRI) screening. This study's aim was to assess the accuracy and interobserver variability of MRI screening in the detection of rupture and extracapsular silicone leakage. A prospective study included 107 women with 214 PIP implants who underwent explantation preceded by MRI. In 2013, two radiologists blinded for previous MRI findings or outcome at surgery, independently re-evaluated all MRI examinations. A structured protocol described the MRI findings. The ex vivo findings served as reference standard. In 208 of the 214 explanted prostheses, radiologists agreed independently about the condition of the implants. In five of the six cases they disagreed (2.6 %), but subsequently reached consensus. A sensitivity of 93 %, specificity of 93 %, positive predictive value of 77 % and negative predictive value of 98 % was found. The interobserver agreement was excellent (kappa value of 0.92). MRI has a high accuracy in diagnosing rupture in silicone breast implants. Considering the high kappa value of interobserver agreement, MRI appears to be a consistent diagnostic test. A simple, uniform classification, may improve communication between radiologist and plastic surgeon. (orig.)

  16. MRI screening for silicone breast implant rupture: accuracy, inter- and intraobserver variability using explantation results as reference standard

    International Nuclear Information System (INIS)

    Maijers, M.C.; Ritt, M.J.P.F.; Niessen, F.B.; Veldhuizen, J.F.H.; Manoliu, R.A.

    2014-01-01

    The recall of Poly Implant Prothese (PIP) silicone breast implants in 2010 resulted in large numbers of asymptomatic women with implants who underwent magnetic resonance imaging (MRI) screening. This study's aim was to assess the accuracy and interobserver variability of MRI screening in the detection of rupture and extracapsular silicone leakage. A prospective study included 107 women with 214 PIP implants who underwent explantation preceded by MRI. In 2013, two radiologists blinded for previous MRI findings or outcome at surgery, independently re-evaluated all MRI examinations. A structured protocol described the MRI findings. The ex vivo findings served as reference standard. In 208 of the 214 explanted prostheses, radiologists agreed independently about the condition of the implants. In five of the six cases they disagreed (2.6 %), but subsequently reached consensus. A sensitivity of 93 %, specificity of 93 %, positive predictive value of 77 % and negative predictive value of 98 % was found. The interobserver agreement was excellent (kappa value of 0.92). MRI has a high accuracy in diagnosing rupture in silicone breast implants. Considering the high kappa value of interobserver agreement, MRI appears to be a consistent diagnostic test. A simple, uniform classification, may improve communication between radiologist and plastic surgeon. (orig.)

  17. Comparison of MRI pulse sequences in defining prostate volume after permanent implantation

    International Nuclear Information System (INIS)

    McLaughlin, P.W.; Narayana, V.; Drake, D.G.; Miller, B.M.; Marsh, L.; Chan, J.; Gonda, R.; Winfield, R.J.; Roberson, P.L.

    2002-01-01

    Purpose: To determine the relative value of three MRI pulse sequences in defining the prostate volume after permanent implantation. Methods and Materials: A total of 45 patients who received a permanent 125 I implant were studied. Two weeks after implantation, an axial CT scan (2 mm thickness) and T 1 -weighted, T 1 -weighted fat saturation, and T 2 -weighted axial MRI (3-mm) studies were obtained. The prostate volumes were compared with the initial ultrasound planning volumes, and subsequently the CT, T 1 -weighted, and T 1 -weighted fat saturation MRI volumes were compared with the T 2 -weighted volumes. Discrepancies in volume were evaluated by visual inspection of the registered axial images and the registration of axial volumes on the sagittal T 2 -weighted volumes. In a limited set of patients, pre- and postimplant CT and T 2 -weighted MRI studies were available for comparison to determine whether prostate volume changes after implant were dependent on the imaging modality. Results: T 1 -weighted and T 1 -weighted fat saturation MRI and CT prostate volumes were consistently larger than the T 2 -weighted MRI prostate volumes, with a volume on average 1.33 (SD 0.24) times the T 2 -weighted volume. This discrepancy was due to the superiority of T 2 -weighted MRI for prostate definition at the following critical interfaces: membranous urethra, apex, and anterior base-bladder and posterior base-seminal vesicle interfaces. The differences in prostate definition in the anterior base region suggest that the commonly reported underdose may be due to overestimation of the prostate in this region by CT. The consistent difference in volumes suggests that the degree of swelling observed after implantation is in part a function of the imaging modality. In patients with pre- and postimplant CT and T 2 -weighted MRI images, swelling on the T 2 -weighted images was 1.1 times baseline and on CT was 1.3 times baseline, confirming the imaging modality dependence of prostate

  18. SU-E-J-257: Image Artifacts Caused by Implanted Calypso Beacons in MRI Studies

    International Nuclear Information System (INIS)

    Amro, H; Chetty, I; Gordon, J; Wen, N

    2014-01-01

    Purpose: The presence of Calypso Beacon-transponders in patients can cause artifacts during MRI imaging studies. This could be a problem for post-treatment follow up of cancer patients using MRI studies to evaluate metastasis and for functional imaging studies.This work assesses (1) the volume immediately surrounding the transponders that will not be visualized by the MRI due to the beacons, and (2) the dependence of the non-visualized volume on beacon orientation, and scanning techniques. Methods: Two phantoms were used in this study (1) water filled box, (2) and a 2300 cc block of pork meat. Calypso beacons were implanted in the phantoms both in parallel and perpendicular orientations with respect to the MR scanner magnetic field. MR image series of the phantom were obtained with on a 1.0T high field open MR-SIM with multiple pulse sequences, for example, T1-weighted fast field echo and T2-weighted turbo spin echo. Results: On average, a no-signal region with 2 cm radius and 3 cm length was measured. Image artifacts are more significant when beacons are placed parallel to scanner magnetic field; the no-signal area around the beacon was about 0.5 cm larger in orthogonal orientation. The no-signal region surrounding the beacons slightly varies in dimension for the different pulse sequences. Conclusion: The use of Calypso beacons can prohibit the use of MRI studies in post-treatment assessments, especially in the immediate region surrounding the implanted beacon. A characterization of the MR scanner by identifying the no-signal regions due to implanted beacons is essential. This may render the use of Calypso beacons useful for some cases and give the treating physician a chance to identify those patients prior to beacon implantation

  19. Muscle atrophy and metal-on-metal hip implants: a serial MRI study of 74 hips.

    Science.gov (United States)

    Berber, Reshid; Khoo, Michael; Cook, Erica; Guppy, Andrew; Hua, Jia; Miles, Jonathan; Carrington, Richard; Skinner, John; Hart, Alister

    2015-06-01

    Muscle atrophy is seen in patients with metal-on-metal (MOM) hip implants, probably because of inflammatory destruction of the musculo-tendon junction. However, like pseudotumors, it is unclear when atrophy occurs and whether it progresses with time. Our objective was to determine whether muscle atrophy associated with MOM hip implants progresses with time. We retrospectively reviewed 74 hips in 56 patients (32 of them women) using serial MRI. Median age was 59 (23-83) years. The median time post-implantation was 83 (35-142) months, and the median interval between scans was 11 months. Hip muscles were scored using the Pfirrmann system. The mean scores for muscle atrophy were compared between the first and second MRI scans. Blood cobalt and chromium concentrations were determined. The median blood cobalt was 6.84 (0.24-90) ppb and median chromium level was 4.42 (0.20-45) ppb. The median Oxford hip score was 34 (5-48). The change in the gluteus minimus mean atrophy score between first and second MRI was 0.12 (p = 0.002). Mean change in the gluteus medius posterior portion (unaffected by surgical approach) was 0.08 (p = 0.01) and mean change in the inferior portion was 0.10 (p = 0.05). Mean pseudotumor grade increased by 0.18 (p = 0.02). Worsening muscle atrophy and worsening pseudotumor grade occur over a 1-year period in a substantial proportion of patients with MOM hip implants. Serial MRI helps to identify those patients who are at risk of developing worsening soft-tissue pathology. These patients should be considered for revision surgery before irreversible muscle destruction occurs.

  20. SU-E-J-257: Image Artifacts Caused by Implanted Calypso Beacons in MRI Studies

    Energy Technology Data Exchange (ETDEWEB)

    Amro, H; Chetty, I; Gordon, J; Wen, N [Henry Ford Health System, Detroit, MI (United States)

    2014-06-01

    Purpose: The presence of Calypso Beacon-transponders in patients can cause artifacts during MRI imaging studies. This could be a problem for post-treatment follow up of cancer patients using MRI studies to evaluate metastasis and for functional imaging studies.This work assesses (1) the volume immediately surrounding the transponders that will not be visualized by the MRI due to the beacons, and (2) the dependence of the non-visualized volume on beacon orientation, and scanning techniques. Methods: Two phantoms were used in this study (1) water filled box, (2) and a 2300 cc block of pork meat. Calypso beacons were implanted in the phantoms both in parallel and perpendicular orientations with respect to the MR scanner magnetic field. MR image series of the phantom were obtained with on a 1.0T high field open MR-SIM with multiple pulse sequences, for example, T1-weighted fast field echo and T2-weighted turbo spin echo. Results: On average, a no-signal region with 2 cm radius and 3 cm length was measured. Image artifacts are more significant when beacons are placed parallel to scanner magnetic field; the no-signal area around the beacon was about 0.5 cm larger in orthogonal orientation. The no-signal region surrounding the beacons slightly varies in dimension for the different pulse sequences. Conclusion: The use of Calypso beacons can prohibit the use of MRI studies in post-treatment assessments, especially in the immediate region surrounding the implanted beacon. A characterization of the MR scanner by identifying the no-signal regions due to implanted beacons is essential. This may render the use of Calypso beacons useful for some cases and give the treating physician a chance to identify those patients prior to beacon implantation.

  1. MRI evaluation of a new scaffold-based allogenic chondrocyte implantation for cartilage repair

    International Nuclear Information System (INIS)

    Dhollander, A.A.M.; Huysse, W.C.J.; Verdonk, P.C.M.; Verstraete, K.L.; Verdonk, R.; Verbruggen, G.; Almqvist, K.F.

    2010-01-01

    Aim: The present study was designed to evaluate the implantation of alginate beads containing human mature allogenic chondrocytes for the treatment of symptomatic cartilage defects of the knee. MRI was used for the morphological analysis of cartilage repair. The correlation between MRI findings and clinical outcome was also studied. Methods: A biodegradable, alginate-based biocompatible scaffold containing human mature allogenic chondrocytes was used for the treatment of symptomatic chondral and osteochondral lesions in the knee. Twenty-one patients were prospectively evaluated with use of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Visual Analogue Scale (VAS) for pain preoperatively and at 3, 6, 9 and 12 months of follow-up. Of the 21 patients, 12 had consented to follow the postoperative MRI evaluation protocol. MRI data were analyzed based on the original MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) and modified MOCART scoring system. The correlation between the clinical outcome and MRI findings was evaluated. Results: A statistically significant clinical improvement became apparent after 6 months and patients continued to improve during the 12 months of follow-up. One of the two MRI scoring systems that were used, showed a statistically significant deterioration of the repair tissue at 1 year of follow-up. Twelve months after the operation complete filling or hypertrophy was found in 41.6%. Bone-marrow edema and effusion were seen in 41.7% and 25% of the study patients, respectively. We did not find a consistent correlation between the MRI criteria and the clinical results. Discussion: The present study confirmed the primary role of MRI in the evaluation of cartilage repair. Two MOCART-based scoring systems were used in a longitudinal fashion and allowed a practical and morphological evaluation of the repair tissue. However, the correlation between clinical outcome and MRI findings was poor. Further

  2. MRI evaluation of a new scaffold-based allogenic chondrocyte implantation for cartilage repair

    Energy Technology Data Exchange (ETDEWEB)

    Dhollander, A.A.M., E-mail: Aad.Dhollander@Ugent.b [Department of Orthopaedic Surgery and Traumatology, Ghent University Hospital, De Pintelaan 185, 1P5, B9000 Gent (Belgium); Huysse, W.C.J., E-mail: Wouter.Huysse@Ugent.b [Department of Radiology, Ghent University Hospital, De Pintelaan 185, -1K12 IB, B9000 Gent (Belgium); Verdonk, P.C.M., E-mail: pverdonk@yahoo.co [Department of Orthopaedic Surgery and Traumatology, Ghent University Hospital, De Pintelaan 185, 1P5, B9000 Gent (Belgium); Verstraete, K.L., E-mail: Koenraad.Verstraete@Ugent.b [Department of Radiology, Ghent University Hospital, De Pintelaan 185, -1K12 IB, B9000 Gent (Belgium); Verdonk, R., E-mail: Rene.Verdonk@Ugent.b [Department of Orthopaedic Surgery and Traumatology, Ghent University Hospital, De Pintelaan 185, 1P5, B9000 Gent (Belgium); Verbruggen, G., E-mail: Gust.Verbruggen@Ugent.b [Laboratory of Connective Tissue Biology, Department of Rheumatology, Ghent University Hospital, De Pintelaan 185, Ghent (Belgium); Almqvist, K.F., E-mail: Fredrik.Almqvist@Ugent.b [Department of Orthopaedic Surgery and Traumatology, Ghent University Hospital, De Pintelaan 185, 1P5, B9000 Gent (Belgium)

    2010-07-15

    Aim: The present study was designed to evaluate the implantation of alginate beads containing human mature allogenic chondrocytes for the treatment of symptomatic cartilage defects of the knee. MRI was used for the morphological analysis of cartilage repair. The correlation between MRI findings and clinical outcome was also studied. Methods: A biodegradable, alginate-based biocompatible scaffold containing human mature allogenic chondrocytes was used for the treatment of symptomatic chondral and osteochondral lesions in the knee. Twenty-one patients were prospectively evaluated with use of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Visual Analogue Scale (VAS) for pain preoperatively and at 3, 6, 9 and 12 months of follow-up. Of the 21 patients, 12 had consented to follow the postoperative MRI evaluation protocol. MRI data were analyzed based on the original MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) and modified MOCART scoring system. The correlation between the clinical outcome and MRI findings was evaluated. Results: A statistically significant clinical improvement became apparent after 6 months and patients continued to improve during the 12 months of follow-up. One of the two MRI scoring systems that were used, showed a statistically significant deterioration of the repair tissue at 1 year of follow-up. Twelve months after the operation complete filling or hypertrophy was found in 41.6%. Bone-marrow edema and effusion were seen in 41.7% and 25% of the study patients, respectively. We did not find a consistent correlation between the MRI criteria and the clinical results. Discussion: The present study confirmed the primary role of MRI in the evaluation of cartilage repair. Two MOCART-based scoring systems were used in a longitudinal fashion and allowed a practical and morphological evaluation of the repair tissue. However, the correlation between clinical outcome and MRI findings was poor. Further

  3. Focused tight dressing does not prevent cochlear implant magnet migration under 1.5 Tesla MRI.

    Science.gov (United States)

    Cuda, D; Murri, A; Succo, G

    2013-04-01

    We report a retrospective case of inner magnet migration, which occurred after 1.5 Tesla MRI scanning in an adult recipient of a bilateral cochlear implant (CI) despite a focused head dressing. The patient, bilaterally implanted with Nucleus 5 CIs (Cochlear LTD, Sydney, Australia), underwent a 1.5 Tesla cholangio-MRI scan for biliary duct pathology. In subsequent days, a focal skin alteration appeared over the left inner coil. Plain skull radiographs showed partial magnet migration on the left side. Surgical exploration confirmed magnet twisting; the magnet was effectively repositioned. Left CI performance was restored to pre-migration level. The wound healed without complications. Thus, focused dressing does not prevent magnet migration in CI recipients undergoing 1.5 Tesla MRI. All patients should be counselled on this potential complication. A minor surgical procedure is required to reposition the magnet. Nevertheless, timely diagnosis is necessary to prevent skin breakdown and subsequent device contamination. Plain skull radiograph is very effective in identifying magnet twisting; it should be performed systematically after MRI or minimally on all suspected cases.

  4. Hexagonal undersampling for faster MRI near metallic implants.

    Science.gov (United States)

    Sveinsson, Bragi; Worters, Pauline W; Gold, Garry E; Hargreaves, Brian A

    2015-02-01

    Slice encoding for metal artifact correction acquires a three-dimensional image of each excited slice with view-angle tilting to reduce slice and readout direction artifacts respectively, but requires additional imaging time. The purpose of this study was to provide a technique for faster imaging around metallic implants by undersampling k-space. Assuming that areas of slice distortion are localized, hexagonal sampling can reduce imaging time by 50% compared with conventional scans. This work demonstrates this technique by comparisons of fully sampled images with undersampled images, either from simulations from fully acquired data or from data actually undersampled during acquisition, in patients and phantoms. Hexagonal sampling is also shown to be compatible with parallel imaging and partial Fourier acquisitions. Image quality was evaluated using a structural similarity (SSIM) index. Images acquired with hexagonal undersampling had no visible difference in artifact suppression from fully sampled images. The SSIM index indicated high similarity to fully sampled images in all cases. The study demonstrates the ability to reduce scan time by undersampling without compromising image quality. © 2014 Wiley Periodicals, Inc.

  5. Fully phase-encoded MRI near metallic implants using ultrashort echo times and broadband excitation.

    Science.gov (United States)

    Wiens, Curtis N; Artz, Nathan S; Jang, Hyungseok; McMillan, Alan B; Koch, Kevin M; Reeder, Scott B

    2018-04-01

    To develop a fully phase-encoded MRI method for distortion-free imaging near metallic implants, in clinically feasible acquisition times. An accelerated 3D fully phase-encoded acquisition with broadband excitation and ultrashort echo times is presented, which uses a broadband radiofrequency pulse to excite the entire off-resonance induced by the metallic implant. Furthermore, fully phase-encoded imaging is used to prevent distortions caused by frequency encoding, and to obtain ultrashort echo times for rapidly decaying signal. Phantom and in vivo acquisitions were used to describe the relationship among excitation bandwidth, signal loss near metallic implants, and T 1 weighting. Shorter radiofrequency pulses captured signal closer to the implant by improving spectral coverage and allowing shorter echo times, whereas longer pulses improved T 1 weighting through larger maximum attainable flip angles. Comparisons of fully phase-encoded acquisition with broadband excitation and ultrashort echo times to T 1 -weighted multi-acquisition with variable resonance image combination selective were performed in phantoms and subjects with metallic knee and hip prostheses. These acquisitions had similar contrast and acquisition efficiency. Accelerated fully phase-encoded acquisitions with ultrashort echo times and broadband excitation can generate distortion free images near metallic implants in clinically feasible acquisition times. Magn Reson Med 79:2156-2163, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  6. Evaluation of permanent I-125 prostate implants using radiographs and MRI

    International Nuclear Information System (INIS)

    Moerland, M.A.; Beersma, R.; Bhagwandien, R.; Wijrdeman, H.K.; Battermann, J.J.

    1995-01-01

    Introduction: Localized prostatic cancer is managed by radical prostatectomy, external beam irradiation or a permanent implant with I-125 seeds. Permanent implants are indicated for small tumours (T1-T2) with a well to moderate histological differentiation. The technique used is a transrectal ultrasound guided transperineal implantation technique, which aims for a seed and dose distribution such that the initial doserate line of 7.8 cGy/h encompasses the prostate resulting in an accumulated dose of 160 Gy. Up till now the seed and dose distribution is evaluated from isocentric radiographs, which do not show the relation with the prostate. Objectives: The aim of this study is the development of a technique to reconstruct and evaluate the seed and dose distribution within the prostate. Methods: Twenty patients underwent radiography on the simulator and scanning on a whole body NMR system within 3 days after implantation of the I-125 seeds. Isocentric radiographs were used for reconstruction of the seed distribution, after which registration with the MR images provided the seed positions in relation to the prostate. Volume dose histograms were used to evaluate the implants. Results: The I-125 seeds and the prostate anatomy were well depicted on T1-weighted spin echo images with minimal read out gradient strength. To date, ten implants were evaluated. According to our method, the prostate volumes receiving the prescribed dose of 160 Gy ranged from 30 to 70% of the total prostate volumes. Conclusion: The combination of isocentric radiographs and MRI enables reconstruction of the seed and dose distribution in relation to the prostate and the computation of dose volume histograms, which may be of value in the evaluation of implant quality

  7. The role of endorectal coil MRI in patient selection and treatment planning for prostate seed implants

    International Nuclear Information System (INIS)

    Clarke, Daniel H.; Banks, Stephen J.; Wiederhorn, A. Roger; Klousia, John W.; Lissy, Jeanne M.; Miller, Michelle; Able, Arnold M.; Artiles, Carlos; Hindle, William V.; Blair, Deborah N.; Houk, Russell R.; Sheridan, Michael J.

    2002-01-01

    Purpose: To assess the role of endorectal coil magnetic resonance imaging (MRI) staging for patients undergoing seed implantation (SI) with or without external beam radiotherapy (EBRT). Methods and Materials: Between October 1994 and December 1998, 390 patients underwent prostate SI (98% Pd-103, 2% I-125). Seventy-six percent of patients had a prostate serum antigen (PSA) 20. Ten percent of patients had a Gleason score (GS) of 4-5, 54% had GS 6, 29% had GS 7, and 7% had GS ≥ 8. Monotherapy was employed in 46% of patients, and the remaining 54% received combined EBRT and SI. Three hundred twenty-seven were staged by high-resolution phased array pelvic coil, or in most cases, an endorectal coil MRI. The MRI findings were used to guide stage-appropriate treatment recommendations, and to assist in the preplanning and optimization of seed distributions. The criteria utilized to determine MRI-based stage were founded on the reported literature from the University of Pennsylvania. All MRI studies were reviewed by C.A., D.B., or W.H., who were unaware of clinical stage at the time of their review. The biopsy report was available to them as the only clinical correlate. Results: Of the 327 patients staged by MRI, 70% were upstaged from the digital rectal examination-based clinical stage; 26% of T 1 , T 2 patients were upstaged to T 3 . Perineural invasion and the percentage of positive cores predicted for T 3 MRI stage (p 3 intermediate-risk group patients treated by combined therapy with a previous study of T 3 intermediate-risk group treated by radical prostatectomy (RP) at the University of Pennsylvania. Our 36-month PSA FFP was 94% compared with 21% for the previous study's RP patients. Conclusion: MRI is a valuable staging procedure for prostate cancer patients treated by SI. PSA FFP results appear to be improved by MRI staging. MRI T 3 disease can be treated more effectively by SI + EBRT than by RP

  8. A protocol for patients with cardiovascular implantable devices undergoing magnetic resonance imaging (MRI): should defibrillation threshold testing be performed post-(MRI).

    Science.gov (United States)

    Burke, Peter Thomas; Ghanbari, Hamid; Alexander, Patrick B; Shaw, Michael K; Daccarett, Marcos; Machado, Christian

    2010-06-01

    Magnetic resonance imaging (MRI) in patients with Cardiovascular Implantable Electronic Devices (CIED) has not been approved by the Food and Drug Administration. Recent data suggests MRI as a relative rather than absolute contraindication in CIED patients. Recently, the American Heart Association has recommended defibrillation threshold testing (DFTT) in implantable cardioverter defibrillator (ICD) patients undergoing MRI. We evaluated the feasibility and safety of a protocol for MRI in CIED patients, incorporating the new recommendations on DFTT. Consecutive patients with CIED undergoing MRI were included. The protocol consisted of continuous monitoring during imaging, device interrogation pre- and post-MRI, reprogramming of the pacemaker to an asynchronous mode in pacemaker-dependent (PMD) patients and a non-tracking/sensing mode for non-PMD patients. All tachyarrhythmia therapies were disabled. Devices were interrogated for lead impedance, battery life, pacing, and sensing thresholds. All patients with ICD underwent DFTT/defibrillator safety margin testing (DSMT) post-MRI. A total of 92 MRI's at 1.5 Tesla were performed in 38 patients. A total of 13 PMD patients, ten ICD patients, four cardiac resynchronization therapy with defibrillator (CRT-D) patients, and 11 non-PMD patients were scanned from four major manufacturers. No device circuitry damage, programming alterations, inappropriate shocks, failure to pace, or changes in sensing, pacing, or defibrillator thresholds were found on single or multiple MRI sessions. Our protocol for MRI in CIED patients appears safe, feasible, and reproducible. This is irrespective of the type of CIED, pacemaker dependancy or multiple 24-h scanning sessions. Our protocol addresses early detection of potential complications and establishes a response system for potential device-related complications. Our observation suggests that routine DFTT/DSMT post-MRI may not be necessary.

  9. MRI of the labyrinth with volume rendering for cochlear implants candidates

    International Nuclear Information System (INIS)

    Sakata, Motomichi; Harada, Kuniaki; Shirase, Ryuji; Suzuki, Junpei; Nagahama, Hiroshi

    2009-01-01

    We demonstrated three-dimensional models of the labyrinth by volume rendering (VR) in preoperative assessment for cochlear implantation. MRI data sets were acquired in selected subjects using three-dimensional-fast spin echo sequences (3D-FSE). We produced the three-dimensional models of the labyrinth from axial heavily T2-weighted images. The three-dimensional models distinguished the scala tympani and scala vestibuli and provided multidirectional images. The optimal threshold three-dimensional models clearly showed the focal region of signal loss in the cochlear turns (47.1%) and the presence of inner ear anomalies (17.3%) in our series of patients. This study was concluded that these three-dimensional models by VR provide the oto-surgeon with precise, detailed, and easily interpreted information about the cochlear turns for cochlear implants candidates. (author)

  10. Cranial MRI in a young child with cochlear implants after bilateral magnet removal.

    Science.gov (United States)

    Helbig, Silke; Stöver, Timo; Burck, Iris; Kramer, Sabine

    2017-12-01

    A young bilateral cochlear implant (CI) user required magnetic resonance imaging (MRI) to determine the cause of hydrocephalus. The images obtained with the CIs in place were not diagnostically useful due to large artefacts generated by the CI magnets. We obtained useful images by bilaterally explanting the CI-magnets and replacing them with non-magnetic placeholder dummies then conducted the imaging. The artefact in the new images was greatly reduced and the images were diagnostically useful. Lastly, we explanted the dummies and reimplanted the CI-magnets. This procedure should be useful to obtain useful images in CI users. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Positive Contrast MRI Techniques for Visualization of Iron-Loaded Hernia Mesh Implants in Patients.

    Directory of Open Access Journals (Sweden)

    Alexander Ciritsis

    Full Text Available In MRI, implants and devices can be delineated via susceptibility artefacts. To discriminate susceptibility voids from proton-free structures, different positive contrast techniques were implemented. The purpose of this study was to evaluate a pulse sequence-based positive contrast technique (PCSI and a post-processing susceptibility gradient mapping algorithm (SGM for visualization of iron loaded mesh implants in patients.Five patients with iron-loaded MR-visible inguinal hernia mesh implants were examined at 1.5 Tesla. A gradient echo sequence (GRE; parameters: TR: 8.3ms; TE: 4.3ms; NSA:2; FA:20°; FOV:350mm² and a PCSI sequence (parameters: TR: 25ms; TE: 4.6ms; NSA:4; FA:20°; FOV:350mm² with on-resonant proton suppression were performed. SGM maps were calculated using two algorithms. Image quality and mesh delineation were independently evaluated by three radiologists.On GRE, the iron-loaded meshes generated distinct susceptibility-induced signal voids. PCSI exhibited susceptibility differences including the meshes as hyperintense signals. SGM exhibited susceptibility differences with positive contrast. Visually, the different algorithms presented no significant differences. Overall, the diagnostic value was rated best in GRE whereas PCSI and SGM were barely "sufficient".Both "positive contrast" techniques depicted implanted meshes with hyperintense signal. SGM comes without additional acquisition time and can therefore be utilized in every patient.

  12. Deformable registration of x-ray to MRI for post-implant dosimetry in prostate brachytherapy

    Science.gov (United States)

    Park, Seyoun; Song, Danny Y.; Lee, Junghoon

    2016-03-01

    Post-implant dosimetric assessment in prostate brachytherapy is typically performed using CT as the standard imaging modality. However, poor soft tissue contrast in CT causes significant variability in target contouring, resulting in incorrect dose calculations for organs of interest. CT-MR fusion-based approach has been advocated taking advantage of the complementary capabilities of CT (seed identification) and MRI (soft tissue visibility), and has proved to provide more accurate dosimetry calculations. However, seed segmentation in CT requires manual review, and the accuracy is limited by the reconstructed voxel resolution. In addition, CT deposits considerable amount of radiation to the patient. In this paper, we propose an X-ray and MRI based post-implant dosimetry approach. Implanted seeds are localized using three X-ray images by solving a combinatorial optimization problem, and the identified seeds are registered to MR images by an intensity-based points-to-volume registration. We pre-process the MR images using geometric and Gaussian filtering. To accommodate potential soft tissue deformation, our registration is performed in two steps, an initial affine transformation and local deformable registration. An evolutionary optimizer in conjunction with a points-to-volume similarity metric is used for the affine registration. Local prostate deformation and seed migration are then adjusted by the deformable registration step with external and internal force constraints. We tested our algorithm on six patient data sets, achieving registration error of (1.2+/-0.8) mm in < 30 sec. Our proposed approach has the potential to be a fast and cost-effective solution for post-implant dosimetry with equivalent accuracy as the CT-MR fusion-based approach.

  13. Evaluation of MRI issues for a new neurological implant, the Sensor Reservoir.

    Science.gov (United States)

    Shellock, Frank G; Knebel, Jörg; Prat, Angelina D

    2013-09-01

    A new neurological implant, the Sensor-Reservoir, was developed to provide a relative measurement of ICP, which permits a noninvasive technique to detect and localize occlusions in ventricular drainage systems and, thus, to identify mechanical damage to shunt valves. The "reservoir" of this device can be used to administer medication or a contrast agent, to extract cerebral spinal fluid (CSF), and with the possibility of directly measuring ICP. The Sensor-Reservoir was evaluated to identify possible MRI-related issues at 1.5-T/64-MHz and 3-T/128-MHz. Standard testing techniques were utilized to evaluate magnetic field interactions (i.e., translational attraction and torque), MRI-related heating, and artifacts at 3-T for the Sensor-Reservoir. In addition, 12 samples of the Sensor-Reservoir underwent testing to determine if the function of these devices was affected by exposures to various MRI conditions at 1.5-T/64-MHz and 3-T/128-MHz. Magnetic field interactions for the Sensor-Reservoir were not substantial. The heating results indicated a highest temperature rise of 1.8 °C, which poses no patient risks. Artifacts were relatively small in relation to the size and shape of the Sensor-Reservoir, but may interfere diagnostically if the area of interest is near the device. All devices were unaffected by exposures to MRI conditions at 1.5-T/64-MHz and 3-T/128-MHz. When specific guidelines are followed, the Sensor-Reservoir is "MR conditional" for patients undergoing MRI examinations at 3-T or less. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Cardiac MRI in patients with complex CHD following primary or secondary implantation of MRI-conditional pacemaker system.

    Science.gov (United States)

    Al-Wakeel, Nadya; O h-Ici, Darach; Schmitt, Katharina R; Messroghli, Daniel R; Riesenkampff, Eugénie; Berger, Felix; Kuehne, Titus; Peters, Bjoern

    2016-02-01

    In patients with CHD, cardiac MRI is often indicated for functional and anatomical assessment. With the recent introduction of MRI-conditional pacemaker systems, cardiac MRI has become accessible for patients with pacemakers. The present clinical study aims to evaluate safety, susceptibility artefacts, and image reading of cardiac MRI in patients with CHD and MRI-conditional pacemaker systems. Material and methods CHD patients with MRI-conditional pacemaker systems and a clinical need for cardiac MRI were examined with a 1.5-T MRI system. Lead function was tested before and after MRI. Artefacts and image readings were evaluated using a four-point grading scale. A total of nine patients with CHD (mean age 34.0 years, range 19.5-53.6 years) received a total of 11 cardiac MRI examinations. Owing to clinical indications, seven patients had previously been converted from conventional to MRI-conditional pacemaker systems. All MRI examinations were completed without adverse effects. Device testing immediately after MRI and at follow-up showed no alteration of pacemaker device and lead function. Clinical questions could be addressed and answered in all patients. Cardiac MRI can be performed safely with high certainty of diagnosis in CHD patients with MRI-conditional pacemaker systems. In case of clinically indicated lead and box changing, CHD patients with non-MRI-conditional pacemaker systems should be considered for complete conversion to MRI-conditional systems.

  15. MRI-based, wireless determination of the transfer function of a linear implant: Introduction of the transfer matrix.

    Science.gov (United States)

    Tokaya, Janot P; Raaijmakers, Alexander J E; Luijten, Peter R; van den Berg, Cornelis A T

    2018-04-24

    We introduce the transfer matrix (TM) that makes MR-based wireless determination of transfer functions (TFs) possible. TFs are implant specific measures for RF-safety assessment of linear implants. The TF relates an incident tangential electric field on an implant to a scattered electric field at its tip that generally governs local heating. The TM extends this concept and relates an incident tangential electric field to a current distribution in the implant therewith characterizing the RF response along the entire implant. The TM is exploited to measure TFs with MRI without hardware alterations. A model of rightward and leftward propagating attenuated waves undergoing multiple reflections is used to derive an analytical expression for the TM. This allows parameterization of the TM of generic implants, e.g., (partially) insulated single wires, in a homogeneous medium in a few unknowns that simultaneously describe the TF. These unknowns can be determined with MRI making it possible to measure the TM and, therefore, also the TF. The TM is able to predict an induced current due to an incident electric field and can be accurately parameterized with a limited number of unknowns. Using this description the TF is determined accurately (with a Pearson correlation coefficient R ≥ 0.9 between measurements and simulations) from MRI acquisitions. The TM enables measuring of TFs with MRI of the tested generic implant models. The MR-based method does not need hardware alterations and is wireless hence making TF determination in more realistic scenarios conceivable. © 2018 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

  16. Cochlear implant benefits in deafness rehabilitation: PET study of temporal voice Activations

    Energy Technology Data Exchange (ETDEWEB)

    Coez, A.; Zilbovicius, M. [CEA, Serv Hosp Frederic Joliot, INSERM, Res Unit Neuroimaging and Psychiat, U797, IFR49, F-91406 Orsay (France); Zilbovicius, M.; Syrota, A.; Samson, Y. [CEA, DSV, DRM, Serv Hosp Frederic Joliot, F-91406 Orsay (France); Bizaguet, E. [Lab Correct Audit, Paris (France); Coez, A. [Univ Paris Sud 11, Paris (France); Ferrary, E.; Bouccara, D.; Mosnier, I.; Sterkers, O. [INSERM, Unit M 867, Paris (France); Ambert-Dahan, E. [Hop Beaujon, Serv ORL Chirurg Cervicofaciale, AP-HP, Clichy (France); Ferrary, E.; Bouccara, D.; Mosnier, I.; Sterkers, O. [Inst Fed Rech Claude Bernard Physiol et Pathol, IFR02, Paris (France); Samson, Y. [Hop La Pitie Salpetriere, Serv Urgences Cerebro-vasc, AP-HP, Paris (France); Samson, Y. [Univ Paris 06, Paris (France); Sterkers, O. [Univ Denis Diderot Paris 7, Paris (France)

    2008-07-01

    Cochlear implants may improve the medical and social prognosis of profound deafness. Nevertheless, some patients have experienced poor results without any clear explanations. One correlate may be an alteration in cortical voice processing. To test this hypothesis, we studied the activation of human temporal voice areas (TVA) using a well-standardized PET paradigm adapted from previous functional MRI (fMRI) studies. Methods: A PET H{sub 2}{sup 15}O activation study was performed on 3 groups of adult volunteers: normal-hearing control subjects (n 6) and cochlear-implanted post-lingually deaf patients with {>=}2 y of cochlear implant experience, with intelligibility scores in the 'Lafon monosyllabic task' {>=}80% (Good group; n 6) or {<=}20% (Poor group; n 6). Relative cerebral blood flow was measured in 3 conditions: rest, passive listening to human voice, and non-voice stimuli. Results: Compared with silence, the activations induced by non-voice stimuli were bilaterally located in the superior temporal regions in all groups. However these activations were significantly and similarly reduced in both cochlear implant groups, whereas control subjects showed supplementary activations. Compared with non-voice, the voice stimuli induced bilateral activation of the TVA along the superior temporal sulcus (STS) in both the control and the Good groups. In contrast, these activations were not detected in the Poor group, which showed only left unilateral middle STS activation. Conclusion: These results suggest that PET is an adequate method to explore cochlear implant benefits and that this benefit could be linked to the activation of the TVA. (authors)

  17. Cochlear implant benefits in deafness rehabilitation: PET study of temporal voice Activations

    International Nuclear Information System (INIS)

    Coez, A.; Zilbovicius, M.; Zilbovicius, M.; Syrota, A.; Samson, Y.; Bizaguet, E.; Coez, A.; Ferrary, E.; Bouccara, D.; Mosnier, I.; Sterkers, O.; Ambert-Dahan, E.; Ferrary, E.; Bouccara, D.; Mosnier, I.; Sterkers, O.; Samson, Y.; Samson, Y.; Sterkers, O.

    2008-01-01

    Cochlear implants may improve the medical and social prognosis of profound deafness. Nevertheless, some patients have experienced poor results without any clear explanations. One correlate may be an alteration in cortical voice processing. To test this hypothesis, we studied the activation of human temporal voice areas (TVA) using a well-standardized PET paradigm adapted from previous functional MRI (fMRI) studies. Methods: A PET H 2 15 O activation study was performed on 3 groups of adult volunteers: normal-hearing control subjects (n 6) and cochlear-implanted post-lingually deaf patients with ≥2 y of cochlear implant experience, with intelligibility scores in the 'Lafon monosyllabic task' ≥80% (Good group; n 6) or ≤20% (Poor group; n 6). Relative cerebral blood flow was measured in 3 conditions: rest, passive listening to human voice, and non-voice stimuli. Results: Compared with silence, the activations induced by non-voice stimuli were bilaterally located in the superior temporal regions in all groups. However these activations were significantly and similarly reduced in both cochlear implant groups, whereas control subjects showed supplementary activations. Compared with non-voice, the voice stimuli induced bilateral activation of the TVA along the superior temporal sulcus (STS) in both the control and the Good groups. In contrast, these activations were not detected in the Poor group, which showed only left unilateral middle STS activation. Conclusion: These results suggest that PET is an adequate method to explore cochlear implant benefits and that this benefit could be linked to the activation of the TVA. (authors)

  18. 3D CISS, 3D MP-PAGE and 2D TSE for MRI prior to Cochlear implantation

    International Nuclear Information System (INIS)

    Seitz, J.; Held, P.; Voelk, M.; Lenhart, M.; Strotzer, M.; Waldeck, A.

    2000-01-01

    Purpose: The aim of this study was to determine the presurgical predictive value of high resolution MRI in patients scheduled for chochlear implantation. Method and material: The presurgical MRI (3D CISS, 3D MP-RAGE with and without i.v. contrast medium, 2D TSE) findings of 54 patients and the intraoperative situation reported by the surgeon were compared retrospectively. The surgical and functional success of the cochlear implantation was evaluated. Results: We found a high degree of correlation between MRI and intraoperative findings concerning the patency of the whole cochlea and anomalies as well as in the diagnosis of pathology of the cochlear, vestibular and facial nerves and in anomalies of the internal auditory canal. However, in four out of 54 patients there was a false negative prediction regarding the patency of the cochlea. The sensitivity was 50% (4/8), the specificity 100% (46/46). Concerning the surgical success the accuracy was 100%. In all patients MRI gave sufficient anatomical information to the surgeon concerning the jugular bulb and the facial nerve. Conclusion: A high-resolution MRI protocol consisting of coronal 2D T2w TSE, 3D T2*w transverse CISS; plain and contrast enhanced sagittal T1w 3D MP-RAGE is recommended for the evaluation of candidates scheduled for cochlear implantation. (orig.) [de

  19. Implanting Glioblastoma Spheroids into Rat Brains and Monitoring Tumor Growth by MRI Volumetry.

    Science.gov (United States)

    Löhr, Mario; Linsenmann, Thomas; Jawork, Anna; Kessler, Almuth F; Timmermann, Nils; Homola, György A; Ernestus, Ralf-Ingo; Hagemann, Carsten

    2017-01-01

    The outcome of patients suffering from glioblastoma multiforme (GBM) remains poor with a median survival of less than 15 months. To establish innovative therapeutical approaches or to analyze the effect of protein overexpression or protein knockdown by RNA interference in vivo, animal models are mandatory. Here, we describe the implantation of C6 glioma spheroids into the rats' brain and how to follow tumor growth by MRI scans. We show that C6 cells grown in Sprague-Dawley rats share several morphologic features of human glioblastoma like pleomorphic cells, areas of necrosis, vascular proliferation, and tumor cell invasion into the surrounding brain tissue. In addition, we describe a method for tumor volumetry utilizing the CISS 3D- or contrast-enhanced T1-weighted 3D sequence and freely available post-processing software.

  20. MRI-Based Multiscale Model for Electromagnetic Analysis in the Human Head with Implanted DBS

    Directory of Open Access Journals (Sweden)

    Maria Ida Iacono

    2013-01-01

    Full Text Available Deep brain stimulation (DBS is an established procedure for the treatment of movement and affective disorders. Patients with DBS may benefit from magnetic resonance imaging (MRI to evaluate injuries or comorbidities. However, the MRI radio-frequency (RF energy may cause excessive tissue heating particularly near the electrode. This paper studies how the accuracy of numerical modeling of the RF field inside a DBS patient varies with spatial resolution and corresponding anatomical detail of the volume surrounding the electrodes. A multiscale model (MS was created by an atlas-based segmentation using a 1 mm3 head model (mRes refined in the basal ganglia by a 200 μm2 ex-vivo dataset. Four DBS electrodes targeting the left globus pallidus internus were modeled. Electromagnetic simulations at 128 MHz showed that the peak of the electric field of the MS doubled (18.7 kV/m versus 9.33 kV/m and shifted 6.4 mm compared to the mRes model. Additionally, the MS had a sixfold increase over the mRes model in peak-specific absorption rate (SAR of 43.9 kW/kg versus 7 kW/kg. The results suggest that submillimetric resolution and improved anatomical detail in the model may increase the accuracy of computed electric field and local SAR around the tip of the implant.

  1. Fully refocused multi-shot spatiotemporally encoded MRI: robust imaging in the presence of metallic implants.

    Science.gov (United States)

    Ben-Eliezer, Noam; Solomon, Eddy; Harel, Elad; Nevo, Nava; Frydman, Lucio

    2012-12-01

    An approach has been recently introduced for acquiring arbitrary 2D NMR spectra or images in a single scan, based on the use of frequency-swept RF pulses for the sequential excitation and acquisition of the spins response. This spatiotemporal-encoding (SPEN) approach enables a unique, voxel-by-voxel refocusing of all frequency shifts in the sample, for all instants throughout the data acquisition. The present study investigates the use of this full-refocusing aspect of SPEN-based imaging in the multi-shot MRI of objects, subject to sizable field inhomogeneities that complicate conventional imaging approaches. 2D MRI experiments were performed at 7 T on phantoms and on mice in vivo, focusing on imaging in proximity to metallic objects. Fully refocused SPEN-based spin echo imaging sequences were implemented, using both Cartesian and back-projection trajectories, and compared with k-space encoded spin echo imaging schemes collected on identical samples under equal bandwidths and acquisition timing conditions. In all cases assayed, the fully refocused spatiotemporally encoded experiments evidenced a ca. 50 % reduction in signal dephasing in the proximity of the metal, as compared to analogous results stemming from the k-space encoded spin echo counterparts. The results in this study suggest that SPEN-based acquisition schemes carry the potential to overcome strong field inhomogeneities, of the kind that currently preclude high-field, high-resolution tissue characterizations in the neighborhood of metallic implants.

  2. Diagnostic Value of MRI in Patients With Implanted Pacemakers and Implantable Cardioverter-Defibrillators Across a Cross Population: Does the Benefit Justify the Risk? A Proof of Concept Study.

    Science.gov (United States)

    Samar, Huma; Yamrozik, June A; Williams, Ronald B; Doyle, Mark; Shah, Moneal; Bonnet, Christopher A; Biederman, Robert W W

    2017-09-01

    The objective of this study was to assess the diagnostic usefulness of thoracic and nonthoracic magnetic resonance imaging (MRI) imaging in patients with implantable cardiac devices (permanent pacemaker or implantable cardioverter-defibrillators [ICDs]) to determine if there was a substantial benefit to patients with regard to diagnosis and/or management. MRI is infrequently performed on patients with conventional pacemakers or ICDs. Multiple studies have documented the safety of MRI scans in patients with implanted devices, yet the diagnostic value of this approach has not been established. Evaluation data were acquired in 136 patients with implanted cardiac devices who underwent MRIs during a 10-year period at a single institution. Specific criteria were followed for all patients to objectively define if the diagnosis by MRI enhanced patient care; 4 questions were answered after scan interpretation by both MRI technologists and MRI physicians who performed the scan. 1) Did the primary diagnosis change? 2) Did the MRI provide additional information to the existing diagnosis? 3) Was the pre-MRI (tentative) diagnosis confirmed? 4) Did patient management change? If "Yes" was answered to any of the preceding questions, the MRI scan was considered to be of value to patient diagnosis and/or therapy. In 97% (n = 132) of patients, MR added value to patient diagnosis and management. In 49% (n = 67) of patients, MRI added additional valuable information to the primary diagnosis, and in 30% (n = 41) of patients, MRI changed the principle diagnosis and subsequent management of the patient. No safety issues were encountered, and no adverse effects of undergoing the MRI scan were noted in any patient. MRI in patients with implanted pacemakers and defibrillators added value to patient diagnosis and management, which justified the risk of the procedure. Published by Elsevier Inc.

  3. Non-invasive in vivo evaluation of in situ forming PLGA implants by benchtop magnetic resonance imaging (BT-MRI) and EPR spectroscopy.

    Science.gov (United States)

    Kempe, Sabine; Metz, Hendrik; Pereira, Priscila G C; Mäder, Karsten

    2010-01-01

    In the present study, we used benchtop magnetic resonance imaging (BT-MRI) for non-invasive and continuous in vivo studies of in situ forming poly(lactide-co-glycolide) (PLGA) implants without the use of contrast agents. Polyethylene glycol (PEG) 400 was used as an alternative solvent to the clinically used NMP. In addition to BT-MRI, we applied electron paramagnetic resonance (EPR) spectroscopy to characterize implant formation and drug delivery processes in vitro and in vivo. We were able to follow key processes of implant formation by EPR and MRI. Because EPR spectra are sensitive to polarity and mobility, we were able to follow the kinetics of the solvent/non-solvent exchange and the PLGA precipitation. Due to the high water affinity of PEG 400, we observed a transient accumulation of water in the implant neighbourhood. Furthermore, we detected the encapsulation by BT-MRI of the implant as a response of the biological system to the polymer, followed by degradation over a period of two months. We could show that MRI in general has the potential to get new insights in the in vivo fate of in situ forming implants. The study also clearly shows that BT-MRI is a new viable and much less expensive alternative for superconducting MRI machines to monitor drug delivery processes in vivo in small mammals. Copyright 2009 Elsevier B.V. All rights reserved.

  4. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... Examples include but are not limited to: artificial heart valves implanted drug infusion ports artificial limbs or ... imaging based on the electrical activity of the heart, such as electrocardiography (EKG). MRI generally is not ...

  5. Measurements of RF Heating during 3.0T MRI of a Pig Implanted with Deep Brain Stimulator

    Science.gov (United States)

    Gorny, Krzysztof R; Presti, Michael F; Goerss, Stephan J; Hwang, Sun C; Jang, Dong-Pyo; Kim, Inyong; Shu, Yunhong; Favazza, Christopher P; Lee, Kendall H; Bernstein, Matt A

    2012-01-01

    Purpose To present preliminary, in vivo temperature measurements during MRI of a pig implanted with a deep brain stimulation (DBS) system. Materials and Methods DBS system (Medtronic Inc., Minneapolis, MN) was implanted in the brain of an anesthetized pig. 3.0T MRI was performed with a T/R head coil using the low-SAR GRE EPI and IR-prepped GRE sequences (SAR: 0.42 W/kg and 0.39 W/kg, respectively), and the high-SAR 4-echo RF spin echo (SAR: 2.9 W/kg). Fluoroptic thermometry was used to directly measure RF-related heating at the DBS electrodes, and at the implantable pulse generator (IPG). For reference the measurements were repeated in the same pig at 1.5T and, at both field strengths, in a phantom. Results At 3.0T, the maximal temperature elevations at DBS electrodes were 0.46 °C and 2.3 °C, for the low- and high-SAR sequences, respectively. No heating was observed on the implanted IPG during any of the measurements. Measurements of in-vivo heating differed from those obtained in the phantom. Conclusion The 3.0T MRI using GRE EPI and IR-prepped GRE sequences resulted in local temperature elevations at DBS electrodes of no more than 0.46°C. Although no extrapolation should be made to human exams and much further study will be needed, these preliminary data are encouraging for the future use 3.0T MRI in patients with DBS. PMID:23228310

  6. Measurements of RF heating during 3.0-T MRI of a pig implanted with deep brain stimulator.

    Science.gov (United States)

    Gorny, Krzysztof R; Presti, Michael F; Goerss, Stephan J; Hwang, Sun C; Jang, Dong-Pyo; Kim, Inyong; Min, Hoon-Ki; Shu, Yunhong; Favazza, Christopher P; Lee, Kendall H; Bernstein, Matt A

    2013-06-01

    To present preliminary, in vivo temperature measurements during MRI of a pig implanted with a deep brain stimulation (DBS) system. DBS system (Medtronic Inc., Minneapolis, MN) was implanted in the brain of an anesthetized pig. 3.0-T MRI was performed with a T/R head coil using the low-SAR GRE EPI and IR-prepped GRE sequences (SAR: 0.42 and 0.39 W/kg, respectively), and the high-SAR 4-echo RF spin echo (SAR: 2.9 W/kg). Fluoroptic thermometry was used to directly measure RF-related heating at the DBS electrodes, and at the implantable pulse generator (IPG). For reference the measurements were repeated in the same pig at 1.5 T and, at both field strengths, in a phantom. At 3.0T, the maximal temperature elevations at DBS electrodes were 0.46 °C and 2.3 °C, for the low- and high-SAR sequences, respectively. No heating was observed on the implanted IPG during any of the measurements. Measurements of in vivo heating differed from those obtained in the phantom. The 3.0-T MRI using GRE EPI and IR-prepped GRE sequences resulted in local temperature elevations at DBS electrodes of no more than 0.46 °C. Although no extrapolation should be made to human exams and much further study will be needed, these preliminary data are encouraging for the future use 3.0-T MRI in patients with DBS. Copyright © 2013 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    Gill, Amreeta; Shellock, Frank G

    2012-01-09

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

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

    Directory of Open Access Journals (Sweden)

    Gill Amreeta

    2012-01-01

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

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

    Science.gov (United States)

    2012-01-01

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

  10. Implantation activation annealing of Si-implanted gallium nitride at temperatures > 1,100 C

    International Nuclear Information System (INIS)

    Zolper, J.C.; Han, J.; Biefeld, R.M.

    1997-01-01

    The activation annealing of Si-implanted GaN is reported for temperatures from 1,100 to 1,400 C. Although previous work has shown that Si-implanted GaN can be activated by a rapid thermal annealing at ∼1,100 C, it was also shown that significant damage remained in the crystal. Therefore, both AlN-encapsulated and uncapped Si-implanted GaN samples were annealed in a metal organic chemical vapor deposition system in a N 2 /NH 3 ambient to further assess the annealing process. Electrical Hall characterization shows increases in carrier density and mobility for annealing up to 1,300 C before degrading at 1,400 C due to decomposition of the GaN epilayer. Rutherford backscattering spectra show that the high annealing temperatures reduce the implantation induced damage profile but do not completely restore the as-grown crystallinity

  11. Activation Detection in fMRI Using Jeffrey Divergence

    Science.gov (United States)

    Seghouane, Abd-Krim

    2009-12-01

    A statistical test for detecting activated pixels in functional MRI (fMRI) data is proposed. For the derivation of this test, the fMRI time series measured at each voxel is modeled as the sum of a response signal which arises due to the experimentally controlled activation-baseline pattern, a nuisance component representing effects of no interest, and Gaussian white noise. The test is based on comparing the dimension of the voxels fMRI time series fitted data models with and without controlled activation-baseline pattern. The Jeffrey divergence is used for this comparison. The test has the advantage of not requiring a level of significance or a threshold to be provided.

  12. Halofuginone Inhibits Angiogenesis and Growth in Implanted Metastatic Rat Brain Tumor Model-an MRI Study

    Directory of Open Access Journals (Sweden)

    Rinat Abramovitch

    2004-09-01

    Full Text Available Tumor growth and metastasis depend on angiogenesis; therefore, efforts are made to develop specific angiogenic inhibitors. Halofuginone (HF is a potent inhibitor of collagen type α1(I. In solid tumor models, HF has a potent antitumor and antiangiogenic effect in vivo, but its effect on brain tumors has not yet been evaluated. By employing magnetic resonance imaging (MRI, we monitored the effect of HF on tumor progression and vascularization by utilizing an implanted malignant fibrous histiocytoma metastatic rat brain tumor model. Here we demonstrate that treatment with HF effectively and dose-dependently reduced tumor growth and angiogenesis. On day 13, HF-treated tumors were fivefold smaller than control (P < .001. Treatment with HF significantly prolonged survival of treated animals (142%; P = .001. In HF-treated rats, tumor vascularization was inhibited by 30% on day 13 and by 37% on day 19 (P < .05. Additionally, HF treatment inhibited vessel maturation (P = .03. Finally, in HF-treated rats, we noticed the appearance of a few clusters of satellite tumors, which were distinct from the primary tumor and usually contained vessel cores. This phenomenon was relatively moderate when compared to previous reports of other antiangiogenic agents used to treat brain tumors. We therefore conclude that HF is effective for treatment of metastatic brain tumors.

  13. Spatial resolution and maximum compensation factor of two-dimensional selective excitation pulses for MRI of objects containing conductive implants

    Directory of Open Access Journals (Sweden)

    Taeseong Woo

    2017-05-01

    Full Text Available A quantitative diagnosis using magnetic resonance imaging (MRI can be disturbed by radiofrequency (RF field inhomogeneity induced by the conductive implants. This inhomogeneity causes a local decrease of the signal intensity around the conductor, resulting in a deterioration of the accurate quantification. In a previous study, we developed an MRI imaging method using a two-dimensional selective excitation pulse (2D pulse to mitigate signal inhomogeneity induced by metallic implants. In this paper, the effect of 2D pulse was evaluated quantitatively by numerical simulation and MRI experiments. We introduced two factors for evaluation, spatial resolution and maximum compensation factor. Numerical simulations were performed with two groups. One group was composed of four models with different signal loss width, to evaluate the spatial resolution of the 2D pulse. The other group is also composed of four models with different amounts of signal loss for evaluating maximum compensation factor. In MRI experiments, we prepared phantoms containing conductors, which have different electrical conductivities related with the amounts of signal intensity decrease. The recovery of signal intensity was observed by 2D pulses, in both numerical simulations and experiments.

  14. Brain activation in response to visceral stimulation in rats with amygdala implants of corticosterone: an FMRI study.

    Directory of Open Access Journals (Sweden)

    Anthony C Johnson

    2010-01-01

    Full Text Available Although visceral pain of gastrointestinal (GI origin is the major complaint in patients with irritable bowel syndrome (IBS it remains poorly understood. Brain imaging studies suggest a defect in brain-gut communication in IBS with a greater activation of central arousal circuits including the amygdala. Previously, we found that stereotaxic implantation of corticosterone (CORT onto the amygdala in rats induced anxiety and colonic hypersensitivity. In the present study we used functional magnetic resonance imaging (fMRI to identify specific brain sites activated in a rat model characterized by anxiety and colonic hypersensitivity.Anesthetized male rats received micropellets (30 microg each of either CORT or cholesterol (CHOL, to serve as a control, implanted stereotaxically on the dorsal margin of each amygdala. Seven days later, rats were anesthetized and placed in the fMRI magnet (7T. A series of isobaric colorectal balloon distensions (CRD - 90s 'off', 30s 'on', 8 replicates at two pressures (40 and 60 mmHg were performed in a standard block-design. Cross correlation statistical analysis was used to determine significant differences between distended and non-distended states in CORT and CHOL-treated animals. Analysis of the imaging data demonstrated greater overall brain activation in response to CRD in rats with CORT implants compared to CHOL controls. Additionally, CORT implants produced significant positive bilateral increases in MRI signal in response to CRD in specific nuclei known as integration sites important in anxiety and pain perception.These data indicate that chronic exposure of the amygdala to elevated levels of CORT enhances overall brain activation in response to CRD, and identified other specific brain regions activated in response to mechanical distension of the colon. These results demonstrate the feasibility of performing fMRI imaging in a rodent model that supports clinical observations in IBS patients with enhanced

  15. Fast and direct detection of neuronal activation with diffusion MRI

    International Nuclear Information System (INIS)

    Le Bihan, D.; Urayama, S.; Aso, T.; Hanakawa, T.; Fukuyama, H.

    2006-01-01

    Over the last 30 years functional neuroimaging has emerged as a revolutionary path to study the brain and the mind. This has been possible because of significant advances mainly in two imaging modalities, namely Positron Emission Tomograph y (PET) and Magnetic Resonance Imaging (MRI). Amazingly, although those two modalities are based on radically different physical approaches (detection of 1 3 radioactivity for the first one and nuclear magnetization for the second), both allo w brain activation images to be obtained through measurements involving water molecules. So far, PET and MRI functional imaging have relied on the same principle that neuronal activation and blood flow are coupled through metabolism: Blood flow increases locally in activated brain regions. In the case of PET one uses H 2 O radioactive water which is produced by using a cyclotron and injected to the subject vasculature. In activated brain regions the increase in blood flow leads to a local increase in the tissue radioactive water content detected and localized by the PE T camera. With MRI the hydrogen nuclei of brain endogenous water molecules are magnetized by a strong external magnetic field. In activated regions the increase in blood flow results in an increase of blood oxygenation which induces a slight perturbation of the magnetization relaxation properties of the water molecules around blood vessels detected by the MRI scanner (so called 'BOLD' effect). I n both approaches water is, thus, merely an indirect means to look at changes in cerebral blood flow which accompany brain activation, and although PET and BOLD f MRI have been extremely successful for the functional neuroimaging community, present well known limitations. While the coupling between neuronal activation, metabolism and blood flow has been verified in most instances including BOLD f MRI, the degree and the mechanism of coupling remains largely debated (Magistratt, Pellerin, Mangia) and may fail in some pathological

  16. Cortical language activation in aphasia: a functional MRI study

    International Nuclear Information System (INIS)

    Xu Xiaojun; Zhang Minming; Shang Desheng; Wang Qidong; Luo Benyan

    2004-01-01

    Objective: To investigate the differences of the underlying neural basis of language processing between normal subjects and aphasics, and to study the feasibility for functional magnetic resonance imaging (fMRI) in examining the cortical language activation in clinical aphasics. Methods: fMRI was used to map language network in 6 normal subjects and 3 patients with aphasia who were in the stage of recovery from acute stroke. The participants performed word generation task during fMRI scanning, which measured the signal changes associated with regional neural activity induced by the task. These signal changes were processed to statistically generate the activation map that represented the language area. Results: In normal subjects, a distributed language network was activated. Activations were present in the frontal, temporal, parietal and occipital regions in normal group. In the patient group, however, no activation was showed in the left inferior frontal gyrus whether or not the patient had lesion in the left frontal lobe. Two patients showed activations in some right hemisphere regions where no activation appeared in normal subjects. Conclusion: The remote effect of focal lesion and functional redistribution or reorganization was found in aphasic patients. fMRI was useful in evaluating the language function in aphasic patients. (authors)

  17. Randomized study on the effect of single-implant versus two-implant retained overdentures on implant loss and muscle activity: a 12-month follow-up report.

    Science.gov (United States)

    Alqutaibi, A Y; Kaddah, A F; Farouk, M

    2017-06-01

    The objective was to evaluate and compare single- and two-implant retained overdentures for the rehabilitation of the edentulous mandible. Fifty-six edentulous subjects were eligible for inclusion. Using a random sampling system, a single implant or two implants were placed in the mandible. After 3 months, locator attachments were connected to the implants and the denture delivered with the retentive components incorporated in the denture base. Implant failure and muscle activity were evaluated at the 3-, 6-, and 12-month follow-up examinations. The study sample comprised 56 patients (32 male, 24 female), with a mean age of 58.2 years. A total of 84 implants were placed (28 in the single-implant group and 56 in the two-implant group). All patients completed the 12 months of follow-up. No significant differences were found between subjects in the two groups with respect to implant failure. With regard to improvements in muscle activity, the two-implant group showed statistically significant but perhaps not clinically important differences. Single-implant mandibular overdentures may be suggested as an alternative treatment modality for the rehabilitation of edentulous patients who cannot afford the cost of a two-implant overdenture. Copyright © 2017 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  18. On the estimation of the worst-case implant-induced RF-heating in multi-channel MRI

    Science.gov (United States)

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2017-06-01

    The increasing use of multiple radiofrequency (RF) transmit channels in magnetic resonance imaging (MRI) systems makes it necessary to rigorously assess the risk of RF-induced heating. This risk is especially aggravated with inclusions of medical implants within the body. The worst-case RF-heating scenario is achieved when the local tissue deposition in the at-risk region (generally in the vicinity of the implant electrodes) reaches its maximum value while MRI exposure is compliant with predefined general specific absorption rate (SAR) limits or power requirements. This work first reviews the common approach to estimate the worst-case RF-induced heating in multi-channel MRI environment, based on the maximization of the ratio of two Hermitian forms by solving a generalized eigenvalue problem. It is then shown that the common approach is not rigorous and may lead to an underestimation of the worst-case RF-heating scenario when there is a large number of RF transmit channels and there exist multiple SAR or power constraints to be satisfied. Finally, this work derives a rigorous SAR-based formulation to estimate a preferable worst-case scenario, which is solved by casting a semidefinite programming relaxation of this original non-convex problem, whose solution closely approximates the true worst-case including all SAR constraints. Numerical results for 2, 4, 8, 16, and 32 RF channels in a 3T-MRI volume coil for a patient with a deep-brain stimulator under a head imaging exposure are provided as illustrative examples.

  19. Magnet discolation - An increasing and serious complication following MRI in patients with chochlear implants; Magnetdiskolation - eine zunehmende und folgenreiche Komplikation nach MRT bei Patienten mit Cochlea Implantat

    Energy Technology Data Exchange (ETDEWEB)

    Hassepass, F.; Staubenau, V.; Arndt, S.; Beck, R.; Grauvogel, T.; Aschendorff, A. [Univ. Medical Center Freiburg (Germany). Dept. of Otorhinolaryngology-Head and Neck Surgery; Bulla, S. [Univ. Medical Center Freiburg (Germany). Dept. of Diagnostic Radiology

    2014-07-15

    Cochlear implantation (CI) represents the gold standard in the treatment of children born deaf and postlingually deafened adults. Initial magnetic resonance imaging (MRI) was contraindicated in CI users. Meanwhile, there are specific recommendations concerning MRI compatibility depending on the type of CI system and the device manufacturer. Some CI systems are even approved for MRI with the internal magnet left in place. The aim of this study was to analyze all magnet revision surgeries in CI patients at one CI center and the relationship to MRI scans over time. Between 2000 and 2013, a total of 2027 CIs were implanted. The number of magnet dislocation (MD) surgeries and their causes was assessed retrospectively. In total 12 cases of MD resulting from an MRI scan (0.59 %) were observed, accounting for 52.2 % of all magnetic revision surgeries. As per the labeling, it was considered safe to leave the internal magnet in place during MRI while following specific manufacturer recommendations: MRI intensity of 1.5 Tesla (T) and compression head bandage during examination. A compression head bandage in a 1.5 T MRI unit does not safely prevent MD and the related serious complications in CI recipients. We recommend a Stenvers view radiograph after MRI with the internal magnet in place for early identification of MD, at least in the case of pain during or after MRI examination. MRI in CI patients should be indicated with restraint and patients should be explicitly informed about the possible risks. Recommendations regarding MRI compatibility and the handling of CI patients issued with MRI for the most common CI systems are summarized.

  20. Brain activation studies with PET and functional MRI

    Energy Technology Data Exchange (ETDEWEB)

    Yonekura, Yoshiharu [Fukui Medical Univ., Matsuoka (Japan). Biomedical Imaging Research Center; Sadato, Norihiro [Okazaki National Research Inst., Aichi (Japan). National Inst. for Physiological Sciences

    2002-01-01

    Application of PET and functional MRI in brain activation studies is reviewed. 3D-PET images obtained repeatedly after intravenous injection of about 370 MBq of H{sub 2}{sup 15}O can detect a faint blood flow change in the brain. Functional MRI can also detect the blood flow change in the brain due to blood oxygen level-dependent effect. Echo-planar imaging is popular in MRI with 1.5 or 3 T. Images are analyzed by statistical parametric mapping with correction of cerebral regions, anatomical normalization and statistics. PET data give the blood flow change by the H{sub 2}{sup 15}O incorporation into the brain and MRI data, by the scarce tissue oxygen consumption despite the change. Actual images during the cognition task-performance and of frequent artifacts are given. PET is suitable for studies of brain functions like sensibility and emotion and functional MRI, like cortex functions and clinical practices in identification of functional regions prior to surgery and evaluation of functional recovery of damaged brain. (K.H.)

  1. Brain activation studies with PET and functional MRI

    International Nuclear Information System (INIS)

    Yonekura, Yoshiharu; Sadato, Norihiro

    2002-01-01

    Application of PET and functional MRI in brain activation studies is reviewed. 3D-PET images obtained repeatedly after intravenous injection of about 370 MBq of H 2 15 O can detect a faint blood flow change in the brain. Functional MRI can also detect the blood flow change in the brain due to blood oxygen level-dependent effect. Echo-planar imaging is popular in MRI with 1.5 or 3 T. Images are analyzed by statistical parametric mapping with correction of cerebral regions, anatomical normalization and statistics. PET data give the blood flow change by the H 2 15 O incorporation into the brain and MRI data, by the scarce tissue oxygen consumption despite the change. Actual images during the cognition task-performance and of frequent artifacts are given. PET is suitable for studies of brain functions like sensibility and emotion and functional MRI, like cortex functions and clinical practices in identification of functional regions prior to surgery and evaluation of functional recovery of damaged brain. (K.H.)

  2. Decoding subjective mental states from fMRI activity patterns

    International Nuclear Information System (INIS)

    Tamaki, Masako; Kamitani, Yukiyasu

    2011-01-01

    In recent years, functional magnetic resonance imaging (fMRI) decoding has emerged as a powerful tool to read out detailed stimulus features from multi-voxel brain activity patterns. Moreover, the method has been extended to perform a primitive form of 'mind-reading,' by applying a decoder 'objectively' trained using stimulus features to more 'subjective' conditions. In this paper, we first introduce basic procedures for fMRI decoding based on machine learning techniques. Second, we discuss the source of information used for decoding, in particular, the possibility of extracting information from subvoxel neural structures. We next introduce two experimental designs for decoding subjective mental states: the 'objective-to-subjective design' and the 'subjective-to-subjective design.' Then, we illustrate recent studies on the decoding of a variety of mental states, such as, attention, awareness, decision making, memory, and mental imagery. Finally, we discuss the challenges and new directions of fMRI decoding. (author)

  3. MRI

    DEFF Research Database (Denmark)

    Schroeter, Aileen; Rudin, Markus; Gianolio, Eliana

    2017-01-01

    This chapter discusses principles of nuclear magnetic resonance (NMR) and MRI followed by a survey on the major classes of MRI contrast agents (CA), their modes of action, and some of the most significative applications. The two more established classes of MRI-CA are represented by paramagnetic...... been attained that markedly increase the number and typology of systems with CEST properties. Currently much attention is also devoted to hyperpolarized molecules that display a sensitivity enhancement sufficient for their direct exploitation for the formation of the MR image. A real breakthrough...

  4. Anomalous activation of shallow B+ implants in Ge

    DEFF Research Database (Denmark)

    Yates, B.R.; Darby, B.L.; Rudawski, N.G.

    2011-01-01

    The electrical activation of B+ implantation at 2 keV to doses of 5.0×1013-5.0×1015 cm-2 in crystalline and pre-amorphized Ge following annealing at 400 °C for 1.0 h was studied using micro Hall effect measurements. Preamorphization improved activation for all samples with the samples implanted...... to a dose of 5.0×1015 cm-2 displaying an estimated maximum active B concentration of 4.0×1020 cm-3 as compared to 2.0×1020 cm-3 for the crystalline sample. However, incomplete activation was observed for all samples across the investigated dose range. For the sample implanted to a dose of 5.0×1013 cm -2......, activation values were 7% and 30%, for c-Ge and PA-Ge, respectively. The results suggest the presence of an anomalous clustering phenomenon of shallow B+ implants in Ge. © 2011 Elsevier B.V. All rights reserved....

  5. Prevention of Cutaneous Tissue Contracture During Removal of Craniofacial Implant Superstructures for CT and MRI Studies

    Directory of Open Access Journals (Sweden)

    Maureen Sullivan

    2010-04-01

    Full Text Available Objectives: Head and neck cancer patients who have lost facial parts following surgical intervention frequently require craniofacial implant retained facial prostheses for restoration. Many craniofacial implant patients require computed tomography and magnetic resonance imaging scans as part of their long-term follow-up care. Consequently removal of implant superstructures and peri-abutment tissue management is required for those studies. The purpose of the present paper was to describe a method for eliminating cranial imaging artifacts in patients with craniofacial implants.Material and Methods: Three patients wearing extraoral implant retained facial prostheses needing either computed tomography or magnetic resonance imaging studies were discussed. Peri-implant soft tissues contracture after removal of percutaneous craniofacial implant abutments during computed tomography and magnetic resonance imaging studies was prevented using a method proposed by authors. The procedure involves temporary removal of the supra-implant components prior to imaging and filling of the tissue openings with polyvinyl siloxane dental impression material.Results: Immediately after filling of the tissue openings with polyvinyl siloxane dental impression material patients were sent for the imaging studies, and were asked to return for removal of the silicone plugs and reconnection of all superstructure hardware after imaging procedures were complete. The silicone plugs were easily removed with a dental explorer. The percutaneous abutments were immediately replaced and screwed into the implants which were at the bone level.Conclusions: Presented herein method eliminates the source of artifacts and prevents contracture of percutaneous tissues upon removal of the implant abutments during imaging.

  6. Optimization of scan time in MRI for total hip prostheses. SEMAC tailoring for prosthetic implants containing different types of metals

    Energy Technology Data Exchange (ETDEWEB)

    Deligianni, X. [University of Basel Hospital, Basel (Switzerland). Div. of Radiological Physics; Merian Iselin Klinik, Basel (Switzerland). Inst. of Radiology; Bieri, O. [University of Basel Hospital, Basel (Switzerland). Div. of Radiological Physics; Elke, R. [Orthomerian, Basel (Switzerland); Wischer, T.; Egelhof, T. [Merian Iselin Klinik, Basel (Switzerland). Inst. of Radiology

    2015-12-15

    Magnetic resonance imaging (MRI) of soft tissues after total hip arthroplasty is of clinical interest for the diagnosis of various pathologies that are usually invisible with other imaging modalities. As a result, considerable effort has been put into the development of metal artifact reduction MRI strategies, such as slice encoding for metal artifact correction (SEMAC). Generally, the degree of metal artifact reduction with SEMAC directly relates to the overall time spent for acquisition, but there is no specific consensus about the most efficient sequence setup depending on the implant material. The aim of this article is to suggest material-tailored SEMAC protocol settings. Five of the most common total hip prostheses (1. Revision prosthesis (S-Rom), 2. Titanium alloy, 3. Mueller type (CoNiCRMo alloy), 4. Old Charnley prosthesis (Exeter/Stryker), 5. MS-30 stem (stainless-steel)) were scanned on a 1.5 T MRI clinical scanner with a SEMAC sequence with a range of artifact-resolving slice encoding steps (SES: 2 - 23) along the slice direction (yielding a total variable scan time ranging from 1 to 10 min). The reduction of the artifact volume in comparison with maximal artifact suppression was evaluated both quantitatively and qualitatively in order to establish a recommended number of steps for each case. The number of SES that reduced the artifact volume below approximately 300 mm{sup 3} ranged from 3 to 13, depending on the material. Our results showed that although 3 SES steps can be sufficient for artifact reduction for titanium prostheses, at least 11 SES should be used for prostheses made of materials such as certain alloys of stainless steel. Tailoring SES to the implant material and to the desired degree of metal artifact reduction represents a simple tool for workflow optimization of SEMAC imaging near total hip arthroplasty in a clinical setting.

  7. Optimization of scan time in MRI for total hip prostheses. SEMAC tailoring for prosthetic implants containing different types of metals

    International Nuclear Information System (INIS)

    Deligianni, X.; Wischer, T.; Egelhof, T.

    2015-01-01

    Magnetic resonance imaging (MRI) of soft tissues after total hip arthroplasty is of clinical interest for the diagnosis of various pathologies that are usually invisible with other imaging modalities. As a result, considerable effort has been put into the development of metal artifact reduction MRI strategies, such as slice encoding for metal artifact correction (SEMAC). Generally, the degree of metal artifact reduction with SEMAC directly relates to the overall time spent for acquisition, but there is no specific consensus about the most efficient sequence setup depending on the implant material. The aim of this article is to suggest material-tailored SEMAC protocol settings. Five of the most common total hip prostheses (1. Revision prosthesis (S-Rom), 2. Titanium alloy, 3. Mueller type (CoNiCRMo alloy), 4. Old Charnley prosthesis (Exeter/Stryker), 5. MS-30 stem (stainless-steel)) were scanned on a 1.5 T MRI clinical scanner with a SEMAC sequence with a range of artifact-resolving slice encoding steps (SES: 2 - 23) along the slice direction (yielding a total variable scan time ranging from 1 to 10 min). The reduction of the artifact volume in comparison with maximal artifact suppression was evaluated both quantitatively and qualitatively in order to establish a recommended number of steps for each case. The number of SES that reduced the artifact volume below approximately 300 mm 3 ranged from 3 to 13, depending on the material. Our results showed that although 3 SES steps can be sufficient for artifact reduction for titanium prostheses, at least 11 SES should be used for prostheses made of materials such as certain alloys of stainless steel. Tailoring SES to the implant material and to the desired degree of metal artifact reduction represents a simple tool for workflow optimization of SEMAC imaging near total hip arthroplasty in a clinical setting.

  8. PET/MRI in the Presence of Metal Implants: Completion of the Attenuation Map from PET Emission Data.

    Science.gov (United States)

    Fuin, Niccolo; Pedemonte, Stefano; Catalano, Onofrio A; Izquierdo-Garcia, David; Soricelli, Andrea; Salvatore, Marco; Heberlein, Keith; Hooker, Jacob M; Van Leemput, Koen; Catana, Ciprian

    2017-05-01

    We present a novel technique for accurate whole-body attenuation correction in the presence of metallic endoprosthesis, on integrated non-time-of-flight (non-TOF) PET/MRI scanners. The proposed implant PET-based attenuation map completion (IPAC) method performs a joint reconstruction of radioactivity and attenuation from the emission data to determine the position, shape, and linear attenuation coefficient (LAC) of metallic implants. Methods: The initial estimate of the attenuation map was obtained using the MR Dixon method currently available on the Siemens Biograph mMR scanner. The attenuation coefficients in the area of the MR image subjected to metal susceptibility artifacts are then reconstructed from the PET emission data using the IPAC algorithm. The method was tested on 11 subjects presenting 13 different metallic implants, who underwent CT and PET/MR scans. Relative mean LACs and Dice similarity coefficients were calculated to determine the accuracy of the reconstructed attenuation values and the shape of the metal implant, respectively. The reconstructed PET images were compared with those obtained using the reference CT-based approach and the Dixon-based method. Absolute relative change (aRC) images were generated in each case, and voxel-based analyses were performed. Results: The error in implant LAC estimation, using the proposed IPAC algorithm, was 15.7% ± 7.8%, which was significantly smaller than the Dixon- (100%) and CT- (39%) derived values. A mean Dice similarity coefficient of 73% ± 9% was obtained when comparing the IPAC- with the CT-derived implant shape. The voxel-based analysis of the reconstructed PET images revealed quantification errors (aRC) of 13.2% ± 22.1% for the IPAC- with respect to CT-corrected images. The Dixon-based method performed substantially worse, with a mean aRC of 23.1% ± 38.4%. Conclusion: We have presented a non-TOF emission-based approach for estimating the attenuation map in the presence of metallic implants, to

  9. Neutron activation analysis for calibration of phosphorus implantation dose

    International Nuclear Information System (INIS)

    Paul, Rick L.; Simons, David S.

    2001-01-01

    A feasibility study was undertaken to determine if radiochemical neutron activation analysis (RNAA) can be used to certify the retained dose of phosphorus implanted in silicon, with the goal of producing a phosphorus SRM. Six pieces of silicon, implanted with a nominal phosphorus dose of 8.5x10 14 atoms·cm -2 were irradiated at a neutron flux of 1.05x10 14 cm -2 ·s -1 . The samples were mixed with carrier, dissolved in acid, the phosphorus isolated by chemical separation, and 32 P measured using a beta proportional counter. A mean phosphorus concentration of (8.35±0.20)x10 14 atoms·cm -2 (uncertainty=1 standard deviation) was determined for the six samples, in agreement with the nominal implanted dose

  10. Active MRI tracking for robotic assisted FUS

    Science.gov (United States)

    Xiao, Xu; Huang, Zhihong; Melzer, Andreas

    2017-03-01

    MR guided FUS is a noninvasive method producing thermal necrosis at the position of tumors with high accuracy and temperature control. Because the typical size of the ultrasound focus is smaller than the area of interested treatment tissues, focus repositioning become necessary to achieve multiple sonications to cover the whole targeted area. Using MR compatible mechanical actuators could help the ultrasound beam to reach a wider treatment range than using electrical beam steering technique and more flexibility in position the transducer. An active MR tracking technique was combined into the MRgFUS system to help locating the position of the mechanical actuator and the FUS transducer. For this study, a precise agar reference model was designed and fabricated to test the performance of the active tracking technique when it was used on the MR-compatible robotics InnoMotion™ (IBSMM, Engineering spol. s r.o. / Ltd, Czech Republic). The precision, tracking range and positioning speed of the combined robotic FUS system were evaluated in this study. Compared to the existing MR guided HIFU systems, the combined robotic system with active tracking techniques provides a potential that allows the FUS treatment to operate in a larger spatial range and with a faster speed, which is one of the main challenges for organ motion tracking.

  11. Caval filter implantation under MRI control - experimental in vitro and in vivo investigations

    International Nuclear Information System (INIS)

    Neuerburg, J.; Buecker, A.; Adam, G.; Leenen, M.; Guenther, R.W.; Hurtak, M.S.W.

    1997-01-01

    Purpose: An instrument has been developed for the introduction of caval filters which can be used with MRI; it has been investigated in in vitro and in in vivo experiments. Material and method: The ferromagnetic components of a commercially available instrument for the femoral introduction of the MR-eye TM Tulip IVC filter were changed for similar, non-ferromagnetic parts and the lock and dilator marked with dysprosium oxide rings. The instrument was used in a flow phantom and in animal experiments (two domestic pigs) in order to insert filters under MRI control on a 1.5 T Philips Gyroscan with integrated mobile digital subtraction angiography. Results: Both in vitro and in vivo, the introducer, catheter and caval filter could be identified by MRI and positioned under MRI control. The position of the filter as indicated by MRI corresponded with radiological and macroscopic findings in all cases (5 phantoms, 2 pigs). Conclusion: The early experimental results indicate that percutaneous introduction of caval filters with placement under MRI control is possible. (orig.) [de

  12. Ventricular Assist Device implant (AB 5000 prototype cannula: In vitro assessment of MRI issues at 3-Tesla

    Directory of Open Access Journals (Sweden)

    Valencerina Samuel

    2008-05-01

    Full Text Available Abstract Purpose To evaluate MRI issues at 3-Tesla for a ventricular assist device (VAD. Methods The AB5000 Ventricle with a prototype Nitinol wire-reinforced In-Flow Cannula and Out-Flow Cannula attached (Abiomed, Inc., Danvers, MA was evaluated for magnetic field interactions, heating, and artifacts at 3-Tesla. MRI-related heating was assessed with the device in a gelled-saline-filled, head/torso phantom using a transmit/received RF body coil while performing MRI at a whole body averaged SAR of 3-W/kg for 15-min. Artifacts were assessed for the main metallic component of this VAD (atrial cannula using T1-weighted, spin echo and gradient echo pulse sequences. Results The AB5000 Ventricle with the prototype In-Flow Cannula and Out-Flow Cannula attached showed relatively minor magnetic field interactions that will not cause movement in situ. Heating was not excessive (highest temperature change, +0.8°C. Artifacts may create issues for diagnostic imaging if the area of interest is in the same area or close to the implanted metallic component of this VAD (i.e., the venous cannula. Conclusion The results of this investigation demonstrated that it would be acceptable for a patient with this VAD (AB5000 Ventricle with a prototype Nitinol wire-reinforced In-Flow Cannula and Out-Flow Cannula attached to undergo MRI at 3-Tesla or less. Notably, it is likely that the operation console for this device requires positioning a suitable distance (beyond the 100 Gauss line or in the MR control room from the 3-Tesla MR system to ensure proper function of the VAD.

  13. Fast and direct detection of neuronal activation with diffusion MRI

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-01

    Over the last 30 years functional neuroimaging has emerged as a revolutionary path to study the brain and the mind. This has been possible because of significant advances mainly in two imaging modalities, namely Positron Emission Tomograph y (PET) and Magnetic Resonance Imaging (MRI). Amazingly, although those two modalities are based on radically different physical approaches (detection of 1 3 radioactivity for the first one and nuclear magnetization for the second), both allo w brain activation images to be obtained through measurements involving water molecules. So far, PET and MRI functional imaging have relied on the same principle that neuronal activation and blood flow are coupled through metabolism: Blood flow increases locally in activated brain regions. In the case of PET one uses H{sub 2}O radioactive water which is produced by using a cyclotron and injected to the subject vasculature. In activated brain regions the increase in blood flow leads to a local increase in the tissue radioactive water content detected and localized by the PE T camera. With MRI the hydrogen nuclei of brain endogenous water molecules are magnetized by a strong external magnetic field. In activated regions the increase in blood flow results in an increase of blood oxygenation which induces a slight perturbation of the magnetization relaxation properties of the water molecules around blood vessels detected by the MRI scanner (so called 'BOLD' effect). I n both approaches water is, thus, merely an indirect means to look at changes in cerebral blood flow which accompany brain activation, and although PET and BOLD f MRI have been extremely successful for the functional neuroimaging community, present well known limitations. While the coupling between neuronal activation, metabolism and blood flow has been verified in most instances including BOLD f MRI, the degree and the mechanism of coupling remains largely debated (Magistratt, Pellerin, Mangia) and may fail in some

  14. Comparative studies of brain activation with MEG and functional MRI

    International Nuclear Information System (INIS)

    George, J.S.; Aine, C.J.; Sanders, J.A.; Lewine, J.D.; Caprihan, A.

    1993-01-01

    The past two years have witnessed the emergence of MRI as a functional imaging methodology. Initial demonstrations involved the injection of a paramagnetic contrast agent and required ultrafast echo planar imaging capability to adequately resolve the passage of the injected bolus. By measuring the local reduction in image intensity due to magnetic susceptibility, it was possible to calculate blood volume, which changes as a function of neural activation. Later developments have exploited endogenous contrast mechanisms to monitor changes in blood volume or in venous blood oxygen content. Recently, we and others have demonstrated that it is possible to make such measurements in a clinical imager, suggesting that the large installed base of such machines might be utilized for functional imaging. Although it is likely that functional MRI (fMRI) will subsume some of the clinical and basic neuroscience applications now touted for MEG, it is also clear that these techniques offer different largely complementary, capabilities. At the very least, it is useful to compare and cross-validate the activation maps produced by these techniques. Such studies will be valuable as a check on results of neuromagnetic distributed current reconstructions and will allow better characterization of the relationship between neurophysiological activation and associated hemodynamic changes. A more exciting prospect is the development of analyses that combine information from the two modalities to produce a better description of underlying neural activity than is possible with either technique in isolation. In this paper we describe some results from initial comparative studies and outline several techniques that can be used to treat MEG and fMRI data within a unified computational framework

  15. MRI of hip prostheses using single-point methods : in vitro studies towards the artifact-free imaging of individuals with metal implants

    NARCIS (Netherlands)

    Ramos Cabrer, P.; Duynhoven, van J.P.M.; Toorn, van der A.; Nicolaij, K.

    2004-01-01

    Use of magnetic resonance imaging (MRI) in individuals with orthopedic implants is limited because of the large distortions caused by metallic components. As a possible solution for this problem, we suggest the use of single-point imaging (SPI) methods, which are immune to the susceptibility

  16. Treatment of hepatocellular carcinoma adjacent to large blood vessels using 1.5T MRI-guided percutaneous radiofrequency ablation combined with iodine-125 radioactive seed implantation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zheng-Yu, E-mail: linsinlan@yahoo.com.cn [The Department of Radiology, First Affiliated Hospital of Fujian Medical University, 20 Chazhong Road, Fuzhou 350005 (China); Chen, Jin, E-mail: snow8968851@163.com [The Department of Radiology, First Affiliated Hospital of Fujian Medical University, 20 Chazhong Road, Fuzhou 350005 (China); Deng, Xiu-Fen, E-mail: dxf197286@yahoo.com.cn [The Department of Radiology, First Affiliated Hospital of Fujian Medical University, 20 Chazhong Road, Fuzhou 350005 (China)

    2012-11-15

    Objective: The objective is to study the technology associated with and feasibility of the treatment of hepatocellular carcinoma (HCC) adjacent to large blood vessels using 1.5T MRI-guided radiofrequency ablation combined with iodine-125 (I-125) radioactive seed implantation. Methods: Sixteen patients with a total of 24 HCC lesions (average maximum diameter: 2.35 {+-} 1.03 cm) were pathologically confirmed by biopsy or clinically diagnosed received 1.5T MRI-guided percutaneous radiofrequency ablation (RFA) treatment. Each patient had one lesion adjacent to large blood vessels ({>=}3 mm); after the ablation, I-125 radioactive seeds were implanted in the portions of the lesions that were adjacent to the blood vessels. Results: All the ablations and I-125 radioactive seed implantations were successful; a total of 118 seeds were implanted. The ablated lesions exhibited hypointense signals on the T2WI sequence with a thin rim of hyperintense signals; they also exhibited significant hyperintense signals on the T1WI sequence with clear boundaries. The average follow-up period was 11.1 {+-} 6.2 months. There were 23 complete responses and one partial response in the 24 lesions. The alpha-fetoprotein (AFP) levels of the patients significantly decreased. Conclusion: The 1.5T MRI-guided RFA combined with I-125 radioactive seed implantation for the treatment of HCC adjacent to large blood vessels is an effective technology.

  17. Implanted, inductively-coupled, radiofrequency coils fabricated on flexible polymeric material: Application to in vivo rat brain MRI at 7 T

    International Nuclear Information System (INIS)

    Ginefri, J.C.; Poirier-Quinot, M.; Darrasse, L.; Rubin, A.; Tatoulian, M.; Woytasik, M.; Boumezbeur, F.; Djemai, B.; Lethimonnier, F.

    2012-01-01

    Combined with high-field MRI scanners, small implanted coils allow for high resolution imaging with locally improved SNR, as compared to external coils. Small flexible implantable coils dedicated to in vivo MRI of the rat brain at 7 T were developed. Based on the Multi-turn Transmission Line Resonator design, they were fabricated with a Teflon substrate using copper micro-molding process and a specific metal-polymer adhesion treatment. The implanted coils were made biocompatible by Polydimethylsiloxane (PDMS) encapsulation. The use of low loss tangent material achieves low dielectric losses within the substrate and the use of the PDMS layer reduces the parasitic coupling with the surrounding media. An implanted coil was implemented in a 7 T MRI system using inductive coupling and a dedicated external pick-up coil for signal transmission. In vivo images of the rat brain acquired with in plane resolution of (150 μm) 2 thanks to the implanted coil revealed high SNR near the coil, allowing for the visualization of fine cerebral structures. (authors)

  18. Defining active sacroiliitis on MRI for classification of axial spondyloarthritis: update by the ASAS MRI working group

    DEFF Research Database (Denmark)

    Lambert, Robert G W; Bakker, Pauline A C; van der Heijde, Désirée

    2016-01-01

    OBJECTIVES: To review and update the existing definition of a positive MRI for classification of axial spondyloarthritis (SpA). METHODS: The Assessment in SpondyloArthritis International Society (ASAS) MRI working group conducted a consensus exercise to review the definition of a positive MRI...... for inclusion in the ASAS classification criteria of axial SpA. Existing definitions and new data relevant to the MRI diagnosis and classification of sacroiliitis and spondylitis in axial SpA, published since the ASAS definition first appeared in print in 2009, were reviewed and discussed. The precise wording...... of the existing definition was examined in detail and the data and a draft proposal were presented to and voted on by the ASAS membership. RESULTS: The clear presence of bone marrow oedema on MRI in subchondral bone is still considered to be the defining observation that determines the presence of active...

  19. The Role of MRI in Prostate Cancer Active Surveillance

    Directory of Open Access Journals (Sweden)

    Linda M. Johnson

    2014-01-01

    Full Text Available Prostate cancer is the most common cancer diagnosis in American men, excluding skin cancer. The clinical behavior of prostate cancer varies from low-grade, slow growing tumors to high-grade aggressive tumors that may ultimately progress to metastases and cause death. Given the high incidence of men diagnosed with prostate cancer, conservative treatment strategies such as active surveillance are critical in the management of prostate cancer to reduce therapeutic complications of radiation therapy or radical prostatectomy. In this review, we will review the role of multiparametric MRI in the selection and follow-up of patients on active surveillance.

  20. Autogenic training alters cerebral activation patterns in fMRI.

    Science.gov (United States)

    Schlamann, Marc; Naglatzki, Ryan; de Greiff, Armin; Forsting, Michael; Gizewski, Elke R

    2010-10-01

    Cerebral activation patterns during the first three auto-suggestive phases of autogenic training (AT) were investigated in relation to perceived experiences. Nineteen volunteers trained in AT and 19 controls were studied with fMRI during the first steps of autogenic training. FMRI revealed activation of the left postcentral areas during AT in those with experience in AT, which also correlated with the level of AT experience. Activation of prefrontal and insular cortex was significantly higher in the group with experience in AT while insular activation was correlated with number years of simple relaxation exercises. Specific activation in subjects experienced in AT may represent a training effect. Furthermore, the correlation of insular activation suggests that these subjects are different from untrained subjects in emotional processing or self-awareness.

  1. WE-AB-BRA-12: Post-Implant Dosimetry in Prostate Brachytherapy by X-Ray and MRI Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Park, S; Song, D; Lee, J [Johns Hopkins University, Baltimore, MD (United States); Le, Y [Indiana University, Indianapolis, IN (United States)

    2016-06-15

    Purpose: For post-implant dosimetric assessment after prostate brachytherapy, CT-MR fusion approach has been advocated due to the superior accuracy on both seeds localization and soft tissue delineation. However, CT deposits additional radiation to the patient, and seed identification in CT requires manual review and correction. In this study, we propose an accurate, low-dose, and cost-effective post-implant dosimetry approach based on X-ray and MRI. Methods: Implanted seeds are reconstructed using only three X-ray fluoroscopy images by solving a combinatorial optimization problem. The reconstructed seeds are then registered to MR images using an intensity-based points-to-volume registration. MR images are first pre-processed by geometric and Gaussian filtering, yielding smooth candidate seed-only images. To accommodate potential soft tissue deformation, our registration is performed in two steps, an initial affine followed by local deformable registrations. An evolutionary optimizer in conjunction with a points-to-volume similarity metric is used for the affine registration. Local prostate deformation and seed migration are then adjusted by the deformable registration step with external and internal force constraints. Results: We tested our algorithm on twenty patient data sets. For quantitative evaluation, we obtained ground truth seed positions by fusing the post-implant CT-MR images. Seeds were semi-automatically extracted from CT and manually corrected and then registered to the MR images. Target registration error (TRE) was computed by measuring the Euclidean distances from the ground truth to the closest registered X-ray seeds. The overall TREs (mean±standard deviation in mm) are 1.6±1.1 (affine) and 1.3±0.8 (affine+deformable). The overall computation takes less than 1 minute. Conclusion: It has been reported that the CT-based seed localization error is ∼1.6mm and the seed localization uncertainty of 2mm results in less than 5% deviation of prostate D

  2. WE-AB-BRA-12: Post-Implant Dosimetry in Prostate Brachytherapy by X-Ray and MRI Fusion

    International Nuclear Information System (INIS)

    Park, S; Song, D; Lee, J; Le, Y

    2016-01-01

    Purpose: For post-implant dosimetric assessment after prostate brachytherapy, CT-MR fusion approach has been advocated due to the superior accuracy on both seeds localization and soft tissue delineation. However, CT deposits additional radiation to the patient, and seed identification in CT requires manual review and correction. In this study, we propose an accurate, low-dose, and cost-effective post-implant dosimetry approach based on X-ray and MRI. Methods: Implanted seeds are reconstructed using only three X-ray fluoroscopy images by solving a combinatorial optimization problem. The reconstructed seeds are then registered to MR images using an intensity-based points-to-volume registration. MR images are first pre-processed by geometric and Gaussian filtering, yielding smooth candidate seed-only images. To accommodate potential soft tissue deformation, our registration is performed in two steps, an initial affine followed by local deformable registrations. An evolutionary optimizer in conjunction with a points-to-volume similarity metric is used for the affine registration. Local prostate deformation and seed migration are then adjusted by the deformable registration step with external and internal force constraints. Results: We tested our algorithm on twenty patient data sets. For quantitative evaluation, we obtained ground truth seed positions by fusing the post-implant CT-MR images. Seeds were semi-automatically extracted from CT and manually corrected and then registered to the MR images. Target registration error (TRE) was computed by measuring the Euclidean distances from the ground truth to the closest registered X-ray seeds. The overall TREs (mean±standard deviation in mm) are 1.6±1.1 (affine) and 1.3±0.8 (affine+deformable). The overall computation takes less than 1 minute. Conclusion: It has been reported that the CT-based seed localization error is ∼1.6mm and the seed localization uncertainty of 2mm results in less than 5% deviation of prostate D

  3. MRI Near Metallic Implants Using MAVRIC SL: Initial Clinical Experience at 3T

    Science.gov (United States)

    Gutierrez, Luis B.; Do, Bao H.; Gold, Garry E.; Hargreaves, Brian A.; Koch, Kevin M.; Worters, Pauline W.; Stevens, Kathryn J.

    2014-01-01

    Rationale and Objectives To compare the effectiveness of MAVRIC SL with conventional 2D-FSE MR techniques at 3T in imaging patients with a variety of metallic implants. Materials and Methods Twenty-one 3T MR studies were obtained in 19 patients with different types of metal implants. Paired MAVRIC SL and 2D-FSE sequences were reviewed by 2 radiologists, and compared for in-plane and through-plane metal artifact, visualization of the bone implant interface and surrounding soft tissues, blurring, and overall image quality using a 2-tailed Wilcoxon signed rank test. The area of artifact on paired images was measured and compared using a paired Wilcoxon signed rank test. Changes in patient management resulting from MAVRIC SL imaging were documented. Results Significantly less in-plane and through-plane artifact was seen with MAVRIC SL, with improved visualization of the bone-implant interface and surrounding soft tissues, and superior overall image quality (p = 0.0001). Increased blurring was seen with MAVRIC SL (p=0.0016). MAVRIC SL significantly decreased the image artifact compared to 2D-FSE (p=0.0001). Inclusion of MAVRIC SL to the imaging protocol determined the need for surgery or type of surgery in 5 patients, and ruled out the need for surgery in 13 patients. In 3 patients the area of interest was well seen on both MAVRIC SL and 2D-FSE images, so the addition of MAVRIC had no effect on patient management. Conclusion Imaging around metal implants with MAVRIC SL at 3T significantly improved image quality and decreased image artifact compared to conventional 2D-FSE imaging techniques, and directly impacted patient management. PMID:25435186

  4. Realistic modeling of deep brain stimulation implants for electromagnetic MRI safety studies.

    Science.gov (United States)

    Guerin, Bastien; Serano, Peter; Iacono, Maria Ida; Herrington, Todd M; Widge, Alik S; Dougherty, Darin D; Bonmassar, Giorgio; Angelone, Leonardo M; Wald, Lawrence L

    2018-05-04

    We propose a framework for electromagnetic (EM) simulation of deep brain stimulation (DBS) patients in radiofrequency (RF) coils. We generated a model of a DBS patient using post-operative head and neck computed tomography (CT) images stitched together into a 'virtual CT' image covering the entire length of the implant. The body was modeled as homogeneous. The implant path extracted from the CT data contained self-intersections, which we corrected automatically using an optimization procedure. Using the CT-derived DBS path, we built a model of the implant including electrodes, helicoidal internal conductor wires, loops, extension cables, and the implanted pulse generator. We also built four simplified models with straight wires, no extension cables and no loops to assess the impact of these simplifications on safety predictions. We simulated EM fields induced by the RF birdcage body coil in the body model, including at the DBS lead tip at both 1.5 Tesla (64 MHz) and 3 Tesla (123 MHz). We also assessed the robustness of our simulation results by systematically varying the EM properties of the body model and the position and length of the DBS implant (sensitivity analysis). The topology correction algorithm corrected all self-intersection and curvature violations of the initial path while introducing minimal deformations (open-source code available at http://ptx.martinos.org/index.php/Main_Page). The unaveraged lead-tip peak SAR predicted by the five DBS models (0.1 mm resolution grid) ranged from 12.8 kW kg -1 (full model, helicoidal conductors) to 43.6 kW kg -1 (no loops, straight conductors) at 1.5 T (3.4-fold variation) and 18.6 kW kg -1 (full model, straight conductors) to 73.8 kW kg -1 (no loops, straight conductors) at 3 T (4.0-fold variation). At 1.5 T and 3 T, the variability of lead-tip peak SAR with respect to the conductivity ranged between 18% and 30%. Variability with respect to the position and length of the DBS implant ranged between 9.5% and 27.6%.

  5. Realistic modeling of deep brain stimulation implants for electromagnetic MRI safety studies

    Science.gov (United States)

    Guerin, Bastien; Serano, Peter; Iacono, Maria Ida; Herrington, Todd M.; Widge, Alik S.; Dougherty, Darin D.; Bonmassar, Giorgio; Angelone, Leonardo M.; Wald, Lawrence L.

    2018-05-01

    We propose a framework for electromagnetic (EM) simulation of deep brain stimulation (DBS) patients in radiofrequency (RF) coils. We generated a model of a DBS patient using post-operative head and neck computed tomography (CT) images stitched together into a ‘virtual CT’ image covering the entire length of the implant. The body was modeled as homogeneous. The implant path extracted from the CT data contained self-intersections, which we corrected automatically using an optimization procedure. Using the CT-derived DBS path, we built a model of the implant including electrodes, helicoidal internal conductor wires, loops, extension cables, and the implanted pulse generator. We also built four simplified models with straight wires, no extension cables and no loops to assess the impact of these simplifications on safety predictions. We simulated EM fields induced by the RF birdcage body coil in the body model, including at the DBS lead tip at both 1.5 Tesla (64 MHz) and 3 Tesla (123 MHz). We also assessed the robustness of our simulation results by systematically varying the EM properties of the body model and the position and length of the DBS implant (sensitivity analysis). The topology correction algorithm corrected all self-intersection and curvature violations of the initial path while introducing minimal deformations (open-source code available at http://ptx.martinos.org/index.php/Main_Page). The unaveraged lead-tip peak SAR predicted by the five DBS models (0.1 mm resolution grid) ranged from 12.8 kW kg‑1 (full model, helicoidal conductors) to 43.6 kW kg‑1 (no loops, straight conductors) at 1.5 T (3.4-fold variation) and 18.6 kW kg‑1 (full model, straight conductors) to 73.8 kW kg‑1 (no loops, straight conductors) at 3 T (4.0-fold variation). At 1.5 T and 3 T, the variability of lead-tip peak SAR with respect to the conductivity ranged between 18% and 30%. Variability with respect to the position and length of the DBS implant ranged between 9

  6. Brain Activity Associated with Emoticons: An fMRI Study

    Science.gov (United States)

    Yuasa, Masahide; Saito, Keiichi; Mukawa, Naoki

    In this paper, we describe that brain activities associated with emoticons by using fMRI. In communication over a computer network, we use abstract faces such as computer graphics (CG) avatars and emoticons. These faces convey users' emotions and enrich their communications. However, the manner in which these faces influence the mental process is as yet unknown. The human brain may perceive the abstract face in an entirely different manner, depending on its level of reality. We conducted an experiment using fMRI in order to investigate the effects of emoticons. The results show that right inferior frontal gyrus, which associated with nonverbal communication, is activated by emoticons. Since the emoticons were created to reflect the real human facial expressions as accurately as possible, we believed that they would activate the right fusiform gyrus. However, this region was not found to be activated during the experiment. This finding is useful in understanding how abstract faces affect our behaviors and decision-making in communication over a computer network.

  7. Spatial heterogeneity analysis of brain activation in fMRI

    Directory of Open Access Journals (Sweden)

    Lalit Gupta

    2014-01-01

    Full Text Available In many brain diseases it can be qualitatively observed that spatial patterns in blood oxygenation level dependent (BOLD activation maps appear more (diffusively distributed than in healthy controls. However, measures that can quantitatively characterize this spatial distributiveness in individual subjects are lacking. In this study, we propose a number of spatial heterogeneity measures to characterize brain activation maps. The proposed methods focus on different aspects of heterogeneity, including the shape (compactness, complexity in the distribution of activated regions (fractal dimension and co-occurrence matrix, and gappiness between activated regions (lacunarity. To this end, functional MRI derived activation maps of a language and a motor task were obtained in language impaired children with (Rolandic epilepsy and compared to age-matched healthy controls. Group analysis of the activation maps revealed no significant differences between patients and controls for both tasks. However, for the language task the activation maps in patients appeared more heterogeneous than in controls. Lacunarity was the best measure to discriminate activation patterns of patients from controls (sensitivity 74%, specificity 70% and illustrates the increased irregularity of gaps between activated regions in patients. The combination of heterogeneity measures and a support vector machine approach yielded further increase in sensitivity and specificity to 78% and 80%, respectively. This illustrates that activation distributions in impaired brains can be complex and more heterogeneous than in normal brains and cannot be captured fully by a single quantity. In conclusion, heterogeneity analysis has potential to robustly characterize the increased distributiveness of brain activation in individual patients.

  8. Head MRI

    Science.gov (United States)

    ... hearing aids Pins, hairpins, metal zippers, and similar metallic items Removable dental work How the Test will ... an MRI can make heart pacemakers and other implants not work as well. It can also cause ...

  9. In-vivo evaluation of the kinematic behavior of an artificial medial meniscus implant: A pilot study using open-MRI.

    Science.gov (United States)

    De Coninck, Tineke; Elsner, Jonathan J; Linder-Ganz, Eran; Cromheecke, Michiel; Shemesh, Maoz; Huysse, Wouter; Verdonk, René; Verstraete, Koenraad; Verdonk, Peter

    2014-09-01

    In this pilot study we wanted to evaluate the kinematics of a knee implanted with an artificial polycarbonate-urethane meniscus device, designed for medial meniscus replacement. The static kinematic behavior of the implant was compared to the natural medial meniscus of the non-operated knee. A second goal was to evaluate the motion pattern, the radial displacement and the deformation of the meniscal implant. Three patients with a polycarbonate-urethane implant were included in this prospective study. An open-MRI was used to track the location of the implant during static weight-bearing conditions, within a range of motion of 0° to 120° knee flexion. Knee kinematics were evaluated by measuring the tibiofemoral contact points and femoral roll-back. Meniscus measurements (both natural and artificial) included anterior-posterior meniscal movement, radial displacement, and meniscal height. No difference (P>0.05) was demonstrated in femoral roll-back and tibiofemoral contact points during knee flexion between the implanted and the non-operated knees. Meniscal measurements showed no significant difference in radial displacement and meniscal height (P>0.05) at all flexion angles, in both the implanted and non-operated knees. A significant difference (P ≤ 0.05) in anterior-posterior movement during flexion was observed between the two groups. In this pilot study, the artificial polycarbonate-urethane implant, indicated for medial meniscus replacement, had no influence on femoral roll-back and tibiofemoral contact points, thus suggesting that the joint maintains its static kinematic properties after implantation. Radial displacement and meniscal height were not different, but anterior-posterior movement was slightly different between the implant and the normal meniscus. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Magnetic resonance imaging (MRI) evaluation of residual breast tissue following mastectomy and reconstruction with silicone implants.

    Science.gov (United States)

    Zippel, Douglas; Tsehmaister-Abitbol, Vered; Rundstein, Arie; Shalmon, Anat; Zbar, Andrew; Nardini, Gil; Novikov, Ilya; Sklair-Levy, Miri

    2015-01-01

    We present our use of magnetic resonance (MR) measurement to determine the amount of residual breast tissue (RBT) following total mastectomy with reconstruction. Breast MR images of 45 women who underwent surgery between January and November 2011 were reviewed. The cohort included therapeutic and prophylactic mastectomies. RBT was evaluated at four points with a digital caliper assessing T2-weighted and T1-weighted images. Patients undergoing mastectomy for carcinoma tended to have less RBT than in prophylactic surgery. Greater age and recent surgery both correlated with larger RBT. Variable thickness of RBT is demonstrable following mastectomy and implant reconstruction using MR imaging. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Temperature Activated Diffusion of Radicals through Ion Implanted Polymers

    DEFF Research Database (Denmark)

    Wakelin, Edgar A.; Davies, Michael J.; Bilek, Marcela M. M.

    2015-01-01

    Plasma immersion ion implantation (PIII) is a promising technique for immobilizing biomolecules on the surface of polymers. Radicals generated in a subsurface layer by PIII treatment diffuse throughout the substrate, forming covalent bonds to molecules when they reach the surface. Understanding...... to the surface. The model makes useful predictions for the lifetime over which the surface is sufficiently active to covalently immobilize biomolecules and it can be used to determine radical fluence during biomolecule incubation for a range of storage and incubation temperatures so facilitating selection...

  12. Advanced metal artifact reduction MRI of metal-on-metal hip resurfacing arthroplasty implants: compressed sensing acceleration enables the time-neutral use of SEMAC

    International Nuclear Information System (INIS)

    Fritz, Jan; Thawait, Gaurav K.; Fritz, Benjamin; Raithel, Esther; Nittka, Mathias; Gilson, Wesley D.; Mont, Michael A.

    2016-01-01

    Compressed sensing (CS) acceleration has been theorized for slice encoding for metal artifact correction (SEMAC), but has not been shown to be feasible. Therefore, we tested the hypothesis that CS-SEMAC is feasible for MRI of metal-on-metal hip resurfacing implants. Following prospective institutional review board approval, 22 subjects with metal-on-metal hip resurfacing implants underwent 1.5 T MRI. We compared CS-SEMAC prototype, high-bandwidth TSE, and SEMAC sequences with acquisition times of 4-5, 4-5 and 10-12 min, respectively. Outcome measures included bone-implant interfaces, image quality, periprosthetic structures, artifact size, and signal- and contrast-to-noise ratios (SNR and CNR). Using Friedman, repeated measures analysis of variances, and Cohen's weighted kappa tests, Bonferroni-corrected p-values of 0.005 and less were considered statistically significant. There was no statistical difference of outcomes measures of SEMAC and CS-SEMAC images. Visibility of implant-bone interfaces and pseudocapsule as well as fat suppression and metal reduction were ''adequate'' to ''good'' on CS-SEMAC and ''non-diagnostic'' to ''adequate'' on high-BW TSE (p < 0.001, respectively). SEMAC and CS-SEMAC showed mild blur and ripple artifacts. The metal artifact size was 63 % larger for high-BW TSE as compared to SEMAC and CS-SEMAC (p < 0.0001, respectively). CNRs were sufficiently high and statistically similar, with the exception of CNR of fluid and muscle and CNR of fluid and tendon, which were higher on intermediate-weighted high-BW TSE (p < 0.005, respectively). Compressed sensing acceleration enables the time-neutral use of SEMAC for MRI of metal-on-metal hip resurfacing implants when compared to high-BW TSE and image quality similar to conventional SEMAC. (orig.)

  13. SU-D-207B-04: Morphological Features of MRI as a Correlate of Capsular Contracture in Breast Cancer Patients with Implant-Based Reconstructions

    International Nuclear Information System (INIS)

    Tyagi, N; Sutton, E; Hunt, M; Apte, A; Zhang, J; Oh, J; Mechalakos, J; Mehrara, B; Matros, E; Ho, A

    2016-01-01

    Purpose: Capsular contracture (CC) is a serious complication in patients receiving implant-based reconstruction for breast cancer. The goal of this study was to identify image-based correlates of CC using MRI imaging in breast cancer patients who received both MRI and clinical evaluation following reconstructive surgery. Methods: We analyzed a retrospective dataset of 50 patients who had both a diagnostic MR and a plastic surgeon’s evaluations of CC score (Baker’s score) within a six month period following mastectomy and reconstructive surgery. T2w sagittal MRIs (TR/TE = 3500/102 ms, slice thickness = 4 mm) were used for morphological shape features (roundness, eccentricity, solidity, extent and ratio-length) and histogram features (median, skewness and kurtosis) of the implant and the pectoralis muscle overlying the implant. Implant and pectoralis muscles were segmented in 3D using Computation Environment for Radiological Research (CERR) and shape and histogram features were calculated as a function of Baker’s score. Results: Shape features such as roundness and eccentricity were statistically significant in differentiating grade 1 and grade 2 (p = 0.009; p = 0.06) as well as grade 1 and grade 3 CC (p = 0.001; p = 0.006). Solidity and extent were statistically significant in differentiating grade 1 and grade 3 CC (p = 0.04; p = 0.04). Ratio-length was statistically significant in differentiating all grades of CC except grade 2 and grade 3 that showed borderline significance (p = 0.06). The muscle thickness, median intensity and kurtosis were significant in differentiating between grade 1 and grade 3 (p = 0.02), grade 1 and grade 2 (p = 0.03) and grade 1 and grade 3 (p = 0.01) respectively. Conclusion: Morphological shape features described on MR images were associated with the severity of CC. MRI may be important in objectively evaluating outcomes in breast cancer patients who undergo implant reconstruction.

  14. Advanced metal artifact reduction MRI of metal-on-metal hip resurfacing arthroplasty implants: compressed sensing acceleration enables the time-neutral use of SEMAC

    Energy Technology Data Exchange (ETDEWEB)

    Fritz, Jan; Thawait, Gaurav K. [Johns Hopkins University School of Medicine, Russell H. Morgan Department of Radiology and Radiological Science, Section of Musculoskeletal Radiology, Baltimore, MD (United States); Fritz, Benjamin [University of Freiburg, Department of Radiology, Freiburg im Breisgau (Germany); Raithel, Esther; Nittka, Mathias [Siemens Healthcare GmbH, Erlangen (Germany); Gilson, Wesley D. [Siemens Healthcare USA, Inc., Baltimore, MD (United States); Mont, Michael A. [Cleveland Clinic Foundation, Department of Orthopedic Surgery, Cleveland, OH (United States)

    2016-10-15

    Compressed sensing (CS) acceleration has been theorized for slice encoding for metal artifact correction (SEMAC), but has not been shown to be feasible. Therefore, we tested the hypothesis that CS-SEMAC is feasible for MRI of metal-on-metal hip resurfacing implants. Following prospective institutional review board approval, 22 subjects with metal-on-metal hip resurfacing implants underwent 1.5 T MRI. We compared CS-SEMAC prototype, high-bandwidth TSE, and SEMAC sequences with acquisition times of 4-5, 4-5 and 10-12 min, respectively. Outcome measures included bone-implant interfaces, image quality, periprosthetic structures, artifact size, and signal- and contrast-to-noise ratios (SNR and CNR). Using Friedman, repeated measures analysis of variances, and Cohen's weighted kappa tests, Bonferroni-corrected p-values of 0.005 and less were considered statistically significant. There was no statistical difference of outcomes measures of SEMAC and CS-SEMAC images. Visibility of implant-bone interfaces and pseudocapsule as well as fat suppression and metal reduction were ''adequate'' to ''good'' on CS-SEMAC and ''non-diagnostic'' to ''adequate'' on high-BW TSE (p < 0.001, respectively). SEMAC and CS-SEMAC showed mild blur and ripple artifacts. The metal artifact size was 63 % larger for high-BW TSE as compared to SEMAC and CS-SEMAC (p < 0.0001, respectively). CNRs were sufficiently high and statistically similar, with the exception of CNR of fluid and muscle and CNR of fluid and tendon, which were higher on intermediate-weighted high-BW TSE (p < 0.005, respectively). Compressed sensing acceleration enables the time-neutral use of SEMAC for MRI of metal-on-metal hip resurfacing implants when compared to high-BW TSE and image quality similar to conventional SEMAC. (orig.)

  15. Functional cine MRI of the abdomen for the assessment of implanted synthetic mesh in patients after incisional hernia repair: initial results

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Tanja [Ludwig-Maximilians-University Munich, Department of Clinical Radiology, Munich (Germany); Ludwig-Maximilians-University Munich, Department of Clinical Radiology, Klinikum Innenstadt, Munich (Germany); Ladurner, Roland; Mussack, Thomas [Ludwig-Maximilians-University Munich, Department of Surgery and Traumatology, Klinikum Innenstadt, Munich (Germany); Gangkofer, Alexander; Reiser, Maximilian; Lienemann, Andreas [Ludwig-Maximilians-University Munich, Department of Clinical Radiology, Munich (Germany)

    2007-12-15

    The aim of our study was to develop a method that allows the vizualiation and evaluation of implanted mesh in patients after incisional hernia repair with MRI. Furthermore, we assessed problems typically related with mesh implantation like adhesions and muscular atrophy. We enrolled 28 patients after incisional hernia repair. In 10 patients mesh implantation was done by laparoscopy (expanded polytetrafluoroethylene=ePTFE mesh) and in 18 by laparotomy (polypropylene mesh). Functional MRI was performed on a 1.5-T system in supine position. Sagittal and axial TrueFISP images of the entire abdomen were acquired with the patient repeatedly straining. Evaluation included: correct position and intact fixation of the mesh, furthermore visceral adhesions, recurrent hernia and atrophy of the rectus muscle. The ePTFE mesh was visible in all cases; the polypropylene mesh was not detectable. In seven of the ten ePTFE meshes the fixation was not intact; two recurrent hernias were detected. Twenty of 28 patients had intraabdominal adhesions. In 5 cases mobility of the abdominal wall was reduced, and 16 patients showed an atropy of the rectus muscle. Functional cine MRI is a suitable method for follow-up studies in patients after hernia repair. ePTFE meshes can be visualized directly, and typical complications like intestinal adhesions and abdominal wall dysmotility can be assessed reliably. (orig.)

  16. Appearance of low signal intensity lines in MRI of silicone breast implants.

    Science.gov (United States)

    Stroman, P W; Rolland, C; Dufour, M; Grondin, P; Guidoin, R G

    1996-05-01

    Magnetic resonance (MR) images of five explanted mammary prostheses were obtained with a 1.5 T GE Signa system using a conventional spin-echo pulse sequence, in order to investigate the low-intensity curvilinear lines which may be observed in MR images of silicone gel-filled breast implants under pressure from fibrous capsules. MR images showed ellipsoid prostheses, often containing multiple low-intensity curvilinear lines which in some cases presented an appearance very similar to that of the linguine sign. Upon opening the fibrous capsules, however, all of the prostheses were found to be completely intact demonstrating that the appearance of multiple low signal intensity curvilinear lines in MR images of silicone gel-filled prostheses is not necessarily a sign of prosthesis rupture. The MR image features which are specific to the linguine sign must be more precisely defined.

  17. Functional MRI study of cerebral cortical activation during volitional swallowing

    International Nuclear Information System (INIS)

    Wakasa, Toru; Aiga, Hideki; Yanagi, Yoshinobu; Kawai, Noriko; Sugimoto, Tomosada; Kuboki, Takuo; Kishi, Kanji

    2002-01-01

    The purpose of this study was to investigate the somatotropic distribution and lateralization of motor and sensory cortical activity during swallowing in healthy adult human subjects using functional MR imaging. Nine healthy right-handed adult volunteers (6 men, 3 women; ages 22-38) were examined. Their cortical activities were evoked by having them swallow, five times, a small bolus of water (3 ml) supplied through a plastic catheter. As a positive control, the subjects performed five repetitions of right-handed grasping tasks. Blood oxygenation level-dependent images were obtained using a 1.5 Tesla MR system (Magnetom Vision, Siemens Germany; repetition time/echo time (TR/TE)=0.96/0.66, flip angle (FA)=90 deg). T1 weighted anatomical images were obtained for the same slices in each subject. Cerebral activity was observed most notably in the primary motor cortex and primary somatosensory cortex, followed by the premotor cortex, anterior cingulate cortex, frontal operculum, and insula. The hand-grasping task activated relatively superior parts of the primary motor and somatosensory cortices. The swallowing task, on the other hand, activated the inferior parts of the pre- and postcentral gyri. The hand-grasping activation of motor and sensory cortices was localized absolutely on the contralateral side, whereas swallowing activated the motor cortex either bilaterally or unilaterally. Swallowing activated the sensory cortex almost always bilaterally. This study suggested that fMRI could be used to identify the specific areas of cortical activation caused by various tasks, and to differentiate the locations of cortical activation between tasks. (author)

  18. Functional MRI study of cerebral cortical activation during volitional swallowing

    Energy Technology Data Exchange (ETDEWEB)

    Wakasa, Toru; Aiga, Hideki; Yanagi, Yoshinobu; Kawai, Noriko; Sugimoto, Tomosada; Kuboki, Takuo; Kishi, Kanji [Okayama Univ. (Japan). Graduate School of Medicine and Dentistry

    2002-12-01

    The purpose of this study was to investigate the somatotropic distribution and lateralization of motor and sensory cortical activity during swallowing in healthy adult human subjects using functional MR imaging. Nine healthy right-handed adult volunteers (6 men, 3 women; ages 22-38) were examined. Their cortical activities were evoked by having them swallow, five times, a small bolus of water (3 ml) supplied through a plastic catheter. As a positive control, the subjects performed five repetitions of right-handed grasping tasks. Blood oxygenation level-dependent images were obtained using a 1.5 Tesla MR system (Magnetom Vision, Siemens Germany; repetition time/echo time (TR/TE)=0.96/0.66, flip angle (FA)=90 deg). T1 weighted anatomical images were obtained for the same slices in each subject. Cerebral activity was observed most notably in the primary motor cortex and primary somatosensory cortex, followed by the premotor cortex, anterior cingulate cortex, frontal operculum, and insula. The hand-grasping task activated relatively superior parts of the primary motor and somatosensory cortices. The swallowing task, on the other hand, activated the inferior parts of the pre- and postcentral gyri. The hand-grasping activation of motor and sensory cortices was localized absolutely on the contralateral side, whereas swallowing activated the motor cortex either bilaterally or unilaterally. Swallowing activated the sensory cortex almost always bilaterally. This study suggested that fMRI could be used to identify the specific areas of cortical activation caused by various tasks, and to differentiate the locations of cortical activation between tasks. (author)

  19. Receptor activator of nuclear factor kappa B (RANK as a determinant of peri-implantitis

    Directory of Open Access Journals (Sweden)

    Rakić Mia

    2013-01-01

    Full Text Available Background/Aim. Peri-implantitis presents inflammatory process that affects soft and hard supporting tissues of osseointegrated implant based on inflammatory osteoclastogenesis. The aim of this study was to investigate whether receptor activator of nuclear factor kappa B (RANK concentrations in peri-implant crevicular fluid could be associated with clinical parameters that reflect inflammatory nature of peri-implantitis. Methods. The study included 67 patients, 22 with diagnosed peri-implantitis, 22 persons with healthy peri-implant tissues and 23 patients with periodontitis. Clinical parameters from each patient were recorded and samples of peri-implant/gingival crevicular fluid were collected for the enzyme-linked immunosorbent assay (ELISA analysis. Results. RANK concentration was significantly increased in samples from the patients with periimplantitis when compared to healthy implants (p < 0.0001, where the average levels were 9 times higher. At the same time RANK concentration was significantly higher in periimplantitis than in periodontitis sites (p < 0.0001. In implant patients pocket depths and bleeding on probing values were positively associated with high RANK concentrations (p < 0.0001. Conclusion. These results revealed association of increased RANK concentration in samples of periimplant/ gingival crevicular fluid with peri-implant inflammation and suggests that RANK could be a pathologic determinant of peri-implantitis, thereby a potential parameter in assessment of peri-implant tissue inflammation and a potential target in designing treatment strategies.

  20. Inferior frontal gyrus activation predicts individual differences in perceptual learning of cochlear-implant simulations.

    Science.gov (United States)

    Eisner, Frank; McGettigan, Carolyn; Faulkner, Andrew; Rosen, Stuart; Scott, Sophie K

    2010-05-26

    This study investigated the neural plasticity associated with perceptual learning of a cochlear implant (CI) simulation. Normal-hearing listeners were trained with vocoded and spectrally shifted speech simulating a CI while cortical responses were measured with functional magnetic resonance imaging (fMRI). A condition in which the vocoded speech was spectrally inverted provided a control for learnability and adaptation. Behavioral measures showed considerable individual variability both in the ability to learn to understand the degraded speech, and in phonological working memory capacity. Neurally, left-lateralized regions in superior temporal sulcus and inferior frontal gyrus (IFG) were sensitive to the learnability of the simulations, but only the activity in prefrontal cortex correlated with interindividual variation in intelligibility scores and phonological working memory. A region in left angular gyrus (AG) showed an activation pattern that reflected learning over the course of the experiment, and covariation of activity in AG and IFG was modulated by the learnability of the stimuli. These results suggest that variation in listeners' ability to adjust to vocoded and spectrally shifted speech is partly reflected in differences in the recruitment of higher-level language processes in prefrontal cortex, and that this variability may further depend on functional links between the left inferior frontal gyrus and angular gyrus. Differences in the engagement of left inferior prefrontal cortex, and its covariation with posterior parietal areas, may thus underlie some of the variation in speech perception skills that have been observed in clinical populations of CI users.

  1. MRI of the Chest

    Medline Plus

    Full Text Available ... metallic items, which can distort MRI images removable dental work pens, pocket knives and eyeglasses body piercings In most cases, an MRI exam is safe for patients with metal implants, except for a few types. ...

  2. MRI of the Chest

    Medline Plus

    Full Text Available ... items, which can distort MRI images removable dental work pens, pocket knives and eyeglasses body piercings In most cases, an MRI exam is safe for patients with metal implants, except for a ...

  3. Chronotype Modulates Language Processing-Related Cerebral Activity during Functional MRI (fMRI.

    Directory of Open Access Journals (Sweden)

    Jessica Rosenberg

    Full Text Available Based on individual daily physiological cycles, humans can be classified as early (EC, late (LC and intermediate (IC chronotypes. Recent studies have verified that chronotype-specificity relates to performance on cognitive tasks: participants perform more efficiently when tested in the chronotype-specific optimal time of day than when tested in their non-optimal time. Surprisingly, imaging studies focussing on the underlying neural mechanisms of potential chronotype-specificities are sparse. Moreover, chronotype-specific alterations of language-related semantic processing have been neglected so far.16 male, healthy ECs, 16 ICs and 16 LCs participated in a fast event-related functional Magnetic Resonance Imaging (fMRI paradigm probing semantic priming. Subjects read two subsequently presented words (prime, target and were requested to determine whether the target word was an existing word or a non-word. Subjects were tested during their individual evening hours when homeostatic sleep pressure and circadian alertness levels are high to ensure equal entrainment.Chronotype-specificity is associated with task-performance and brain activation. First, ECs exhibited slower reaction times than LCs. Second, ECs showed attenuated BOLD responses in several language-related brain areas, e.g. in the left postcentral gyrus, left and right precentral gyrus and in the right superior frontal gyrus. Additionally, increased BOLD responses were revealed for LCs as compared to ICs in task-related areas, e.g. in the right inferior parietal lobule and in the right postcentral gyrus.These findings reveal that even basic language processes are associated with chronotype-specific neuronal mechanisms. Consequently, results might change the way we schedule patient evaluations and/or healthy subjects in e.g. experimental research and adding "chronotype" as a statistical covariate.

  4. TU-AB-201-11: A Novel Theoretical Framework for MRI-Only Image Guided LDR Prostate and Breast Brachytherapy Implant Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Soliman, A; Elzibak, A; Fatemi, A; Safigholi, H; Ravi, A; Morton, G; Song, W [Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); Han, D [Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, Ontario (Canada); University of California, San Diego, La Jolla, CA (United States)

    2015-06-15

    Purpose: To propose a novel framework for accurate model-based dose calculations using only MR images for LDR prostate and breast seed implant brachytherapy. Methods: Model-based dose calculation methodologies recommended by TG-186 require further knowledge about specific tissue composition, which is challenging with MRI. However, relying on MRI-only for implant dosimetry would reduce the soft tissue delineation uncertainty, costs, and uncertainties associated with multi-modality registration and fusion processes. We propose a novel framework to address this problem using quantitative MRI acquisitions and reconstruction techniques. The framework includes three steps: (1) Identify the locations of seeds(2) Identify the presence (or absence) of calcification(s)(3) Quantify the water and fat content in the underlying tissueSteps (1) and (2) consider the sources that limit patient dosimetry, particularly the inter-seed attenuation and the calcified regions; while step (3) targets the quantification of the tissue composition to consider the heterogeneities in the medium. Our preliminary work has shown that the seeds and the calcifications can be identified with MRI using both the magnitude and the phase images. By employing susceptibility-weighted imaging with specific post-processing techniques, the phase images can be further explored to distinguish the seeds from the calcifications. Absolute quantification of tissue, water, and fat content is feasible and was previously demonstrated in phantoms and in-vivo applications, particularly for brain diseases. The approach relies on the proportionality of the MR signal to the number of protons in an image volume. By employing appropriate correction algorithms for T1 - and T2*-related biases, B1 transmit and receive field inhomogeneities, absolute water/fat content can be determined. Results: By considering calcification and interseed attenuation, and through the knowledge of water and fat mass density, accurate patient

  5. MRI of pituitary macroadenomas with reference to hormonal activity

    Energy Technology Data Exchange (ETDEWEB)

    Lundin, P.; Nyman, R. (Akademiska Sjukhuset, Uppsala (Sweden). Dept. of Diagnostic Radiology); Burmann, P. (Akademiska Sjukhuset, Uppsala (Sweden). Dept. of Internal Medicine); Lundberg, P.O. (Akademiska Sjukhuset, Uppsala (Sweden). Dept. of Neurology)

    1992-02-01

    In 115 patients with pituitary macroadenomas, the findings on mid-field MRI were correlated with the hormonal activity of the tumours. Adenomas secreting growth hormone (GH), prolactin (PRL) and clinically nonsecretory adenomas were studied. Tumour size, invasiveness and signal intensity patterns were recorded. Relaxation times and ratios of signal intensity and proton density (relative to the corpus callosum) were analysed in areas of apparently solid tissue in a subgroup of 59 previously untreated patients. Invasiveness was more common in PRL- and GH-secreting adenomas than in the nonsecreting ones. Diffuse invasion of the base of the skull was most common in prolactinomas, and associated with a lower frequency of suprasellar tumour extension. In prolactinomas, a correlation was found between the maximum serum PRL level and tumour size. Haemorrhagic, cystic or necrotic areas were less common in GH-secreting tumours than in the other types. Haemorrhage was more common in prolactinomas than in nonsecreting tumours. MR parameters were similar in prolactinomas and nonsecreting adenomas, but indicated a smaller amount of water in GH-secreting tumours. (orig.).

  6. Does functional MRI detect activation in white matter? A review of emerging evidence, issues, and future directions

    Science.gov (United States)

    Gawryluk, Jodie R.; Mazerolle, Erin L.; D'Arcy, Ryan C. N.

    2014-01-01

    Functional magnetic resonance imaging (fMRI) is a non-invasive technique that allows for visualization of activated brain regions. Until recently, fMRI studies have focused on gray matter. There are two main reasons white matter fMRI remains controversial: (1) the blood oxygen level dependent (BOLD) fMRI signal depends on cerebral blood flow and volume, which are lower in white matter than gray matter and (2) fMRI signal has been associated with post-synaptic potentials (mainly localized in gray matter) as opposed to action potentials (the primary type of neural activity in white matter). Despite these observations, there is no direct evidence against measuring fMRI activation in white matter and reports of fMRI activation in white matter continue to increase. The questions underlying white matter fMRI activation are important. White matter fMRI activation has the potential to greatly expand the breadth of brain connectivity research, as well as improve the assessment and diagnosis of white matter and connectivity disorders. The current review provides an overview of the motivation to investigate white matter fMRI activation, as well as the published evidence of this phenomenon. We speculate on possible neurophysiologic bases of white matter fMRI signals, and discuss potential explanations for why reports of white matter fMRI activation are relatively scarce. We end with a discussion of future basic and clinical research directions in the study of white matter fMRI. PMID:25152709

  7. MRI grading method for active and chronic spinal changes in spondyloarthritis

    International Nuclear Information System (INIS)

    Madsen, K.B.; Jurik, A.G.

    2010-01-01

    Aim: To describe a magnetic resonance imaging (MRI) grading method for both active and chronic spondyloarthritis (SpA) changes in the spine, to test its validity, and compare chronic MRI scores with findings obtained by radiography. Material and methods: A total of 91 patients (41 males; 50 females) with back pain fulfilling the European Spondylarthropathy Study Group (ESSG) criteria for SpA were examined using MRI and radiography of the spine. The mean age was 36.7 years (range 16-51 years) and symptom duration was between 3 and 27 years. The MRI images were assessed for signs of disease activity (bone marrow oedema at the vertebral plates and costo-vertebral joints) and chronic structural changes [syndesmophytes/vertebral fusion, erosion, and fatty marrow deposition (FMD)]. The interobserver agreement was analysed based on 37 examinations. Radiographs were assessed for the presence of shiny corners, vertebral squaring, syndesmophytes/fusion, and erosion. Results: The interobserver agreement for the assessed MRI abnormalities was acceptable, with kappa values between 0.62 and 0.77. A total of 56 patients had SpA-related spinal abnormalities as depicted using MRI. The total chronic MRI score was not significantly related to the radiographic score, mainly because syndesmophytes were difficult to detect by MRI and FMD was only visualized by MRI. However, FMD was significantly related to the total radiographic score and vertebral squaring. Conclusion: The described MRI grading method was reliable for assessing both disease activity and chronic changes. MRI is promising for estimating chronic changes, but cervical radiography may still be needed. FMD seems to be an important sign of chronicity.

  8. MRI grading method for active and chronic spinal changes in spondyloarthritis

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, K.B. [Department of Radiology, Aarhus University Hospital, Aarhus Sygehus (Denmark); Jurik, A.G., E-mail: anne.jurik@aarhus.rm.d [Department of Radiology, Aarhus University Hospital, Aarhus Sygehus (Denmark)

    2010-01-15

    Aim: To describe a magnetic resonance imaging (MRI) grading method for both active and chronic spondyloarthritis (SpA) changes in the spine, to test its validity, and compare chronic MRI scores with findings obtained by radiography. Material and methods: A total of 91 patients (41 males; 50 females) with back pain fulfilling the European Spondylarthropathy Study Group (ESSG) criteria for SpA were examined using MRI and radiography of the spine. The mean age was 36.7 years (range 16-51 years) and symptom duration was between 3 and 27 years. The MRI images were assessed for signs of disease activity (bone marrow oedema at the vertebral plates and costo-vertebral joints) and chronic structural changes [syndesmophytes/vertebral fusion, erosion, and fatty marrow deposition (FMD)]. The interobserver agreement was analysed based on 37 examinations. Radiographs were assessed for the presence of shiny corners, vertebral squaring, syndesmophytes/fusion, and erosion. Results: The interobserver agreement for the assessed MRI abnormalities was acceptable, with kappa values between 0.62 and 0.77. A total of 56 patients had SpA-related spinal abnormalities as depicted using MRI. The total chronic MRI score was not significantly related to the radiographic score, mainly because syndesmophytes were difficult to detect by MRI and FMD was only visualized by MRI. However, FMD was significantly related to the total radiographic score and vertebral squaring. Conclusion: The described MRI grading method was reliable for assessing both disease activity and chronic changes. MRI is promising for estimating chronic changes, but cervical radiography may still be needed. FMD seems to be an important sign of chronicity.

  9. MR implant labelling and its use in clinical MRI practice; MR-Implantatkennzeichnungen und ihre Anwendung in der klinischen MRT-Praxis

    Energy Technology Data Exchange (ETDEWEB)

    Muehlenweg, M. [Krankenhaus Martha-Maria Halle-Doelau, Institut fuer Radiologie, Halle (Saale) (Germany); Schaefers, G. [MR:comp GmbH, Gelsenkirchen (Germany)

    2015-08-15

    Before a magnetic resonance imaging (MRI) examination, implants in patients must be cleared for MR safety in order to exclude the risk of possible severe injuries and implant malfunction in an MR environment. The general contraindication for measurements of patients with implants still applies; however, in the recent past a way has been found to legally circumvent this contraindication. For this purpose special conditions are required: explicit implant identification and the original manufacturer's labelling are necessary, the required conditions for conditionally MR safe implants must be assured and a risk-benefit analysis with appropriate explanation to the patient has to be performed. This process can be very complex as the implants are often poorly documented and detailed information on the implant MR labelling is also often outdated or not easy to interpret. This article provides information about legal and normative principles of MR measurement of patients with implants. The possible physical interactions with implants will be briefly dealt with as well as possible strategies for better identification and investigation of implants and MR labelling. General approaches for minimizing the risk will be discussed using some examples. The second part deals with the content of MR implant labelling and the current test standards. Furthermore, the additional information from the operating instructions of the MR scanner that are necessary for the interpretation of the MR implant labelling, will be explained. The article concludes with an explanation of the current pattern for MR labelling of implants from the U.S. Food and Drug Administration (FDA) and an exemplary application. (orig.) [German] Implantate in Patienten muessen vor einer MR-Untersuchung auf MR-Sicherheit abgeklaert werden, um moegliche z. T. schwere Verletzungen und Implantatfehlfunktionen in einer MR-Umgebung weitestgehend auszuschliessen. Es gilt unveraendert die generelle Kontraindikation von

  10. iNOS Activity Modulates Inflammation, Angiogenesis, and Tissue Fibrosis in Polyether-Polyurethane Synthetic Implants.

    Science.gov (United States)

    Cassini-Vieira, Puebla; Araújo, Fernanda Assis; da Costa Dias, Filipi Leles; Russo, Remo Castro; Andrade, Silvia Passos; Teixeira, Mauro Martins; Barcelos, Luciola Silva

    2015-01-01

    There is considerable interest in implantation techniques and scaffolds for tissue engineering and, for safety and biocompatibility reasons, inflammation, angiogenesis, and fibrosis need to be determined. The contribution of inducible nitric oxide synthase (iNOS) in the regulation of the foreign body reaction induced by subcutaneous implantation of a synthetic matrix was never investigated. Here, we examined the role of iNOS in angiogenesis, inflammation, and collagen deposition induced by polyether-polyurethane synthetic implants, using mice with targeted disruption of the iNOS gene (iNOS(-/-)) and wild-type (WT) mice. The hemoglobin content and number of vessels were decreased in the implants of iNOS(-/-) mice compared to WT mice 14 days after implantation. VEGF levels were also reduced in the implants of iNOS(-/-) mice. In contrast, the iNOS(-/-) implants exhibited an increased neutrophil and macrophage infiltration. However, no alterations were observed in levels of CXCL1 and CCL2, chemokines related to neutrophil and macrophage migration, respectively. Furthermore, the implants of iNOS(-/-) mice showed boosted collagen deposition. These data suggest that iNOS activity controls inflammation, angiogenesis, and fibrogenesis in polyether-polyurethane synthetic implants and that lack of iNOS expression increases foreign body reaction to implants in mice.

  11. Comparison of Carina active middle-ear implant with conventional hearing aids for mixed hearing loss.

    Science.gov (United States)

    Savaş, V A; Gündüz, B; Karamert, R; Cevizci, R; Düzlü, M; Tutar, H; Bayazit, Y A

    2016-04-01

    To compare the auditory outcomes of Carina middle-ear implants with those of conventional hearing aids in patients with moderate-to-severe mixed hearing loss. The study comprised nine patients (six males, three females) who underwent middle-ear implantation with Carina fully implantable active middle-ear implants to treat bilateral moderate-to-severe mixed hearing loss. The patients initially used conventional hearing aids and subsequently received the Carina implants. The hearing thresholds with implants and hearing aids were compared. There were no significant differences between: the pre-operative and post-operative air and bone conduction thresholds (p > 0.05), the thresholds with hearing aids and Carina implants (p > 0.05), or the pre-operative (mean, 72.8 ± 19 per cent) and post-operative (mean, 69.9 ± 24 per cent) speech discrimination scores (p > 0.05). One of the patients suffered total sensorineural hearing loss three months following implantation despite an initial 38 dB functional gain. All except one patient showed clinical improvements after implantation according to quality of life questionnaire (Glasgow Benefit Inventory) scores. Acceptance of Carina implants is better than with conventional hearing aids in patients with mixed hearing loss, although both yield similar hearing amplification. Cosmetic reasons appear to be critical for patient acceptance.

  12. iNOS Activity Modulates Inflammation, Angiogenesis, and Tissue Fibrosis in Polyether-Polyurethane Synthetic Implants

    Science.gov (United States)

    Cassini-Vieira, Puebla; Araújo, Fernanda Assis; da Costa Dias, Filipi Leles; Russo, Remo Castro; Andrade, Silvia Passos; Teixeira, Mauro Martins; Barcelos, Luciola Silva

    2015-01-01

    There is considerable interest in implantation techniques and scaffolds for tissue engineering and, for safety and biocompatibility reasons, inflammation, angiogenesis, and fibrosis need to be determined. The contribution of inducible nitric oxide synthase (iNOS) in the regulation of the foreign body reaction induced by subcutaneous implantation of a synthetic matrix was never investigated. Here, we examined the role of iNOS in angiogenesis, inflammation, and collagen deposition induced by polyether-polyurethane synthetic implants, using mice with targeted disruption of the iNOS gene (iNOS−/−) and wild-type (WT) mice. The hemoglobin content and number of vessels were decreased in the implants of iNOS−/− mice compared to WT mice 14 days after implantation. VEGF levels were also reduced in the implants of iNOS−/− mice. In contrast, the iNOS−/− implants exhibited an increased neutrophil and macrophage infiltration. However, no alterations were observed in levels of CXCL1 and CCL2, chemokines related to neutrophil and macrophage migration, respectively. Furthermore, the implants of iNOS−/− mice showed boosted collagen deposition. These data suggest that iNOS activity controls inflammation, angiogenesis, and fibrogenesis in polyether-polyurethane synthetic implants and that lack of iNOS expression increases foreign body reaction to implants in mice. PMID:26106257

  13. In vitro assessment of MRI safety at 1.5 T and 3.0 T for bone-anchored hearing aid implant

    Energy Technology Data Exchange (ETDEWEB)

    Yeon, Kyoo Jin; KIm, Hyun Soo; Lee, Seung Keun [Dept. of Radiology, Samsung Medical Center, Seoul (Korea, Republic of); Lee, Tae Soo [Dept. of Biomedical Engineering, Chungbuk National University, Cheongju (Korea, Republic of)

    2017-03-15

    The aim of this study was to evaluate Magnetic Resonance Imaging safety by measuring the translational attraction, torque and susceptibility artifact for Bone-Anchored Hearing Aid (BAHA) implant at 1.5 T and 3.0 T MRI by standard criteria. In vitro assessment tools were made of acrylic-resin by American Society for Testing and Materials (ASTM) F2052-06 and F2119-07 standard. Translational attraction of BAHA implant was measured by the maximum deflection angle at 96 cm position, where the magnetically induced deflection was the greatest. The torque was assessed by the qualitative criteria of evaluating the alignment and rotation pattern, when the BAHA implant was positioned on a line with 45° intervals inside the circular container in the center of the bore. The susceptibility artifact images were obtained using the hanged test tool, which was filled with CuSO4 solution. And then the artifact size was measured using Susceptibility Artifact Measurement (SAM) software. In results, the translational attraction was 0 mm at both 1.5 T and 3.0 T and the torque was 0(no torque) at 1.5 T, and +1(mild torque) at 3.0 T. The size of susceptibility artifacts was between 13.20 mm and 38.91 mm. Therefore, The BAHA implant was safe for the patient in clinical MR environment.

  14. In vitro assessment of MRI safety at 1.5 T and 3.0 T for bone-anchored hearing aid implant

    International Nuclear Information System (INIS)

    Yeon, Kyoo Jin; KIm, Hyun Soo; Lee, Seung Keun; Lee, Tae Soo

    2017-01-01

    The aim of this study was to evaluate Magnetic Resonance Imaging safety by measuring the translational attraction, torque and susceptibility artifact for Bone-Anchored Hearing Aid (BAHA) implant at 1.5 T and 3.0 T MRI by standard criteria. In vitro assessment tools were made of acrylic-resin by American Society for Testing and Materials (ASTM) F2052-06 and F2119-07 standard. Translational attraction of BAHA implant was measured by the maximum deflection angle at 96 cm position, where the magnetically induced deflection was the greatest. The torque was assessed by the qualitative criteria of evaluating the alignment and rotation pattern, when the BAHA implant was positioned on a line with 45° intervals inside the circular container in the center of the bore. The susceptibility artifact images were obtained using the hanged test tool, which was filled with CuSO4 solution. And then the artifact size was measured using Susceptibility Artifact Measurement (SAM) software. In results, the translational attraction was 0 mm at both 1.5 T and 3.0 T and the torque was 0(no torque) at 1.5 T, and +1(mild torque) at 3.0 T. The size of susceptibility artifacts was between 13.20 mm and 38.91 mm. Therefore, The BAHA implant was safe for the patient in clinical MR environment

  15. Comparison of the artifacts caused by metallic implants in breast MRI using dual-echo dixon versus conventional fat-suppression techniques.

    Science.gov (United States)

    Le, Yuan; Kipfer, Hal D; Majidi, Shadie S; Holz, Stephanie; Lin, Chen

    2014-09-01

    The purpose of this article is to evaluate and compare the artifacts caused by metal implants in breast MR images acquired with dual-echo Dixon and two conventional fat-suppression techniques. Two types of biopsy markers were embedded into a uniform fat-water emulsion. T1-weighted gradient-echo images were acquired on a clinical 3-T MRI scanner with three different fat-suppression techniques-conventional or quick fat saturation, spectrally selective adiabatic inversion recovery (SPAIR), and dual-echo Dixon-and the 3D volumes of artifacts were measured. Among the subjects of a clinical breast MRI study using the same scanner, five patients were found to have one or more metal implants. The artifacts in Dixon and SPAIR fat-suppressed images were evaluated by three radiologists, and the results were compared with those of the phantom study. In the phantom study, the artifacts appeared as interleaved bright and dark rings on SPAIR and quick-fat-saturation images, whereas they appeared as dark regions with a thin bright rim on Dixon images. The artifacts imaged with the Dixon technique had the smallest total volume. However, the reviewers found larger artifact diameters on patient images using the Dixon sequence because only the central region was recognized as an artifact on the SPAIR images. Metal implants introduce artifacts of different types and sizes, according to the different fat-suppression techniques used. The dual-echo Dixon technique produces a larger central void, allowing the implant to be easily identified, but presents a smaller overall artifact volume by obscuring less area in the image, according to a quantitative phantom study.

  16. Clinical safety of an MRI conditional implantable cardioverter defibrillator system: A prospective Monocenter ICD-Magnetic resonance Imaging feasibility study (MIMI).

    Science.gov (United States)

    Kypta, Alexander; Blessberger, Hermann; Hoenig, Simon; Saleh, Karim; Lambert, Thomas; Kammler, Juergen; Fellner, Franz; Lichtenauer, Michael; Steinwender, Clemens

    2016-03-01

    The aim of this study was to evaluate the safety and efficacy of the Lumax 740(®) Implantable Cardioverter Defibrillator (ICD) system in patients undergoing a defined 1.5 Tesla (T) MRI. Between November 2013 and April 2014, eighteen patients (age range, 41-78 years; mean age, 64 years) implanted with a Lumax 740(®) ICD system for at least 6 weeks before an MRI were enrolled into this single-center feasibility study. The local ethics committee approved the study before patients gave written informed consent. Patients underwent defined MRI 1.5T of the brain and lower lumbar spine with three safety follow-up evaluations obtained during the 3-month study period. Data were analyzed descriptively. Study endpoints were the absence of either MRI and pacing system related serious adverse device effects (SADE), or of a ventricular pacing threshold increase >0.5V, or of an R-wave amplitude attenuation battery status. Sixteen patients completed the MRI and the follow-up period. As no SADE occurred, the SADE free rate was 100%. Freedom from ventricular pacing threshold increase was 100% (16/16; 95%CI: 82.9%; 100.0%). There were no significant differences between baseline and follow-up measurements of sensing amplitudes (-0.58 ± 2.07 mV, P = 0.239, -0.41 ± 1.04 mV, P = 0.133, and -0.25 ± 1.36 mV, P = 0.724, for immediately after, 1 month and 3 months after MRI scan, respectively) and pacing thresholds (-0.047 ± 0.18 V, P = 0.317, -0.019 ± 0.11 V, P = 0.490, and 0.075 ± 0.19 V, P = 0.070, for immediately after, 1 month and 3 months after MRI scan, respectively). Lead impedances after the MRI scan were significantly lower as compared with baseline values (-22.8 ± 21.69 Ω, P = 0.001, -21.62 ± 39.71 Ω, P = 0.040, and -33.68 ± 57.73 Ω, P = 0.018, for immediately after, 1 month and 3 months after MRI scan, respectively). MRI scans in patients with MRI conditional ICD system (Lumax 740(

  17. Assessment of activated porous granules on implant fixation and early bone formation in sheep

    Directory of Open Access Journals (Sweden)

    Ming Ding

    2016-04-01

    Conclusion: In conclusion, despite nice bone formation and implant fixation in all groups, bioreactor activated graft material did not convincingly induce early implant fixation similar to allograft, and neither bioreactor nor by adding BMA credited additional benefit for bone formation in this model.

  18. Whole-Body MRI versus PET in assessment of multiple myeloma disease activity.

    LENUS (Irish Health Repository)

    Shortt, Conor P

    2009-04-01

    The purpose of this study was to compare FDG PET; whole-body MRI; and the reference standard, bone marrow aspiration and biopsy, to determine the best imaging technique for assessment of disease activity in multiple myeloma.

  19. Estimation of the neuronal activation using fMRI data: An observer-based approach

    KAUST Repository

    Laleg-Kirati, Taous-Meriem; Arabi, Hossein; Tadjine, Mohamed; Zayane, Chadia

    2013-01-01

    This paper deals with the estimation of the neuronal activation and some unmeasured physiological information using the Blood Oxygenation Level Dependent (BOLD) signal measured using functional Magnetic Resonance Imaging (fMRI). We propose to use

  20. EEG-fMRI Bayesian framework for neural activity estimation: a simulation study

    Science.gov (United States)

    Croce, Pierpaolo; Basti, Alessio; Marzetti, Laura; Zappasodi, Filippo; Del Gratta, Cosimo

    2016-12-01

    Objective. Due to the complementary nature of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), and given the possibility of simultaneous acquisition, the joint data analysis can afford a better understanding of the underlying neural activity estimation. In this simulation study we want to show the benefit of the joint EEG-fMRI neural activity estimation in a Bayesian framework. Approach. We built a dynamic Bayesian framework in order to perform joint EEG-fMRI neural activity time course estimation. The neural activity is originated by a given brain area and detected by means of both measurement techniques. We have chosen a resting state neural activity situation to address the worst case in terms of the signal-to-noise ratio. To infer information by EEG and fMRI concurrently we used a tool belonging to the sequential Monte Carlo (SMC) methods: the particle filter (PF). Main results. First, despite a high computational cost, we showed the feasibility of such an approach. Second, we obtained an improvement in neural activity reconstruction when using both EEG and fMRI measurements. Significance. The proposed simulation shows the improvements in neural activity reconstruction with EEG-fMRI simultaneous data. The application of such an approach to real data allows a better comprehension of the neural dynamics.

  1. Auditory brainstem activity and development evoked by apical versus basal cochlear implant electrode stimulation in children.

    Science.gov (United States)

    Gordon, K A; Papsin, B C; Harrison, R V

    2007-08-01

    The role of apical versus basal cochlear implant electrode stimulation on central auditory development was examined. We hypothesized that, in children with early onset deafness, auditory development evoked by basal electrode stimulation would differ from that evoked more apically. Responses of the auditory nerve and brainstem, evoked by an apical and a basal implant electrode, were measured over the first year of cochlear implant use in 50 children with early onset severe to profound deafness who used hearing aids prior to implantation. Responses at initial stimulation were of larger amplitude and shorter latency when evoked by the apical electrode. No significant effects of residual hearing or age were found on initial response amplitudes or latencies. With implant use, responses evoked by both electrodes showed decreases in wave and interwave latencies reflecting decreased neural conduction time through the brainstem. Apical versus basal differences persisted with implant experience with one exception; eIII-eV interlatency differences decreased with implant use. Acute stimulation shows prolongation of basally versus apically evoked auditory nerve and brainstem responses in children with severe to profound deafness. Interwave latencies reflecting neural conduction along the caudal and rostral portions of the brainstem decreased over the first year of implant use. Differences in neural conduction times evoked by apical versus basal electrode stimulation persisted in the caudal but not rostral brainstem. Activity-dependent changes of the auditory brainstem occur in response to both apical and basal cochlear implant electrode stimulation.

  2. Antimicrobial and bone-forming activity of a copper coated implant in a rabbit model.

    Science.gov (United States)

    Prinz, Cornelia; Elhensheri, Mohamed; Rychly, Joachim; Neumann, Hans-Georg

    2017-08-01

    Current strategies in implant technology are directed to generate bioactive implants that are capable to activate the regenerative potential of the surrounding tissue. On the other hand, implant-related infections are a common problem in orthopaedic trauma patients. To meet both challenges, i.e. to generate a bone implant with regenerative and antimicrobial characteristics, we tested the use of copper coated nails for surgical fixation in a rabbit model. Copper acetate was galvanically deposited with a copper load of 1 µg/mm 2 onto a porous oxide layer of Ti6Al4V nails, which were used for the fixation of a tibia fracture, inoculated with bacteria. After implantation of the nail the concentration of copper ions did not increase in blood which indicates that copper released from the implant was locally restricted to the fracture site. After four weeks, analyses of the extracted implants revealed a distinct antimicrobial effect of copper, because copper completely prevented both a weak adhesion and firm attachment of biofilm-forming bacteria on the titanium implant. To evaluate fracture healing, radiographic examination demonstrated an increased callus index in animals with copper coated nails. This result indicates a stimulated bone formation by releasing copper ions. We conclude that the use of implants with a defined load of copper ions enables both prevention of bacterial infection and the stimulation of regenerative processes.

  3. SU-E-J-214: MR Protocol Development to Visualize Sirius MRI Markers in Prostate Brachytherapy Patients for MR-Based Post-Implant Dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Lim, T; Wang, J; Frank, S; Stafford, R; Bruno, T; Bathala, T; Mahmood, U; Pugh, T; Ibbott, G; Kudchadker, R [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: The current CT-based post-implant dosimetry allows precise seed localization but limited anatomical delineation. Switching to MR-based post-implant dosimetry is confounded by imprecise seed localization. One approach is to place positive-contrast markers (Sirius) adjacent to the negative-contrast seeds. This patient study aims to assess the utility of a 3D fast spoiled gradient-recalled echo (FSPGR) sequence to visualize Sirius markers for post-implant dosimetry. Methods: MRI images were acquired in prostate implant patients (n=10) on Day 0 (day-of-implant) and Day 30. The post-implant MR protocol consisted of 3D T2-weighted fast-spin-echo (FSE), T2-weighted 2D-FSE (axial) and T1-weighted 2D-FSE (axial/sagittal/coronal). We incorporated a 3D-FSPGR sequence into the post-implant MR protocol to visualize the Sirius markers. Patients were scanned with different number-of-excitations (6, 8, 10), field-of-view (10cm, 14cm, 18cm), slice thickness (1mm, 0.8mm), flip angle (14 degrees, 20 degrees), bandwidth (122.070 Hz/pixel, 325.508 Hz/pixel, 390.625 Hz/pixel), phase encoding steps (160, 192, 224, 256), frequency-encoding direction (right/left, anterior/posterior), echo-time type (minimum-full, out-of-phase), field strength (1.5T, 3T), contrast (with, without), scanner vendor (Siemens, GE), coil (endorectal-coil only, endorectal-and-torso-coil, torsocoil only), endorectal-coil filling (30cc, 50cc) and endorectal-coil filling type (air, perfluorocarbon [PFC]). For post-implant dosimetric evaluation with greater anatomical detail, 3D-FSE images were fused with 3D-FSPGR images. For comparison with CT-based post-implant dosimetry, CT images were fused with 3D-FSPGR images. Results: The 3D-FSPGR sequence facilitated visualization of markers in patients. Marker visualization helped distinguish signal voids as seeds versus needle tracks for more definitive MR-based post-implant dosimetry. On the CT-MR fused images, the distance between the seed on CT to MR images was 3

  4. SU-E-J-214: MR Protocol Development to Visualize Sirius MRI Markers in Prostate Brachytherapy Patients for MR-Based Post-Implant Dosimetry

    International Nuclear Information System (INIS)

    Lim, T; Wang, J; Frank, S; Stafford, R; Bruno, T; Bathala, T; Mahmood, U; Pugh, T; Ibbott, G; Kudchadker, R

    2015-01-01

    Purpose: The current CT-based post-implant dosimetry allows precise seed localization but limited anatomical delineation. Switching to MR-based post-implant dosimetry is confounded by imprecise seed localization. One approach is to place positive-contrast markers (Sirius) adjacent to the negative-contrast seeds. This patient study aims to assess the utility of a 3D fast spoiled gradient-recalled echo (FSPGR) sequence to visualize Sirius markers for post-implant dosimetry. Methods: MRI images were acquired in prostate implant patients (n=10) on Day 0 (day-of-implant) and Day 30. The post-implant MR protocol consisted of 3D T2-weighted fast-spin-echo (FSE), T2-weighted 2D-FSE (axial) and T1-weighted 2D-FSE (axial/sagittal/coronal). We incorporated a 3D-FSPGR sequence into the post-implant MR protocol to visualize the Sirius markers. Patients were scanned with different number-of-excitations (6, 8, 10), field-of-view (10cm, 14cm, 18cm), slice thickness (1mm, 0.8mm), flip angle (14 degrees, 20 degrees), bandwidth (122.070 Hz/pixel, 325.508 Hz/pixel, 390.625 Hz/pixel), phase encoding steps (160, 192, 224, 256), frequency-encoding direction (right/left, anterior/posterior), echo-time type (minimum-full, out-of-phase), field strength (1.5T, 3T), contrast (with, without), scanner vendor (Siemens, GE), coil (endorectal-coil only, endorectal-and-torso-coil, torsocoil only), endorectal-coil filling (30cc, 50cc) and endorectal-coil filling type (air, perfluorocarbon [PFC]). For post-implant dosimetric evaluation with greater anatomical detail, 3D-FSE images were fused with 3D-FSPGR images. For comparison with CT-based post-implant dosimetry, CT images were fused with 3D-FSPGR images. Results: The 3D-FSPGR sequence facilitated visualization of markers in patients. Marker visualization helped distinguish signal voids as seeds versus needle tracks for more definitive MR-based post-implant dosimetry. On the CT-MR fused images, the distance between the seed on CT to MR images was 3

  5. A graphical simulator for active learning of MRI basics

    DEFF Research Database (Denmark)

    Wilhjelm, Jens E.; Duun-Henriksen, Jonas; Hanson, Lars G.

    2014-01-01

    This paper presents a MATLAB-based graphical user interface (GUI) for simulation of a simple magnetic resonance imaging (MRI) scanner that the student can operate and obtain results with. It is intended for the students in an introductory course in medical imaging and provides the students with a...

  6. Carbamazepine reduces memory induced activation of mesial temporal lobe structures: a pharmacological fMRI-study

    Directory of Open Access Journals (Sweden)

    Okujava Michael

    2001-11-01

    Full Text Available Abstract Background and Purpose It is not known whether carbamazepine (CBZ; a drug widely used in neurology and psychiatry influences the blood oxygenation level dependent (BOLD contrast changes induced by neuronal activation and measured by functional MRI (fMRI. We aimed to investigate the influence of CBZ on memory induced activation of the mesial temporal lobes in patients with symptomatic temporal lobe epilepsy (TLE. Material and Methods Twenty-one individual patients with refractory symptomatic TLE with different CBZ serum levels and 20 healthy controls were studied using BOLD fMRI. Mesial temporal lobe (MTL activation was induced by a task that is based on the retrieval of individually familiar visuo-spatial knowledge. The extent of significant MTL fMRI activation was measured and correlated with the CBZ serum level. Results In TLE patients, the extent of significant fMRI activation over both MTL was negatively correlated to the CBZ serum level (Spearman r = -0.654, P Conclusions In TLE patients, carbamazepine reduces the fMRI-detectable changes within the mesial temporal lobes as induced by effortful memory retrieval. FMRI appears to be suitable to study the effects of chronic drug treatment in patients with epilepsy.

  7. Correlation of geomagnetic activity with implantable cardioverter defibrillator shocks and antitachycardia pacing

    Czech Academy of Sciences Publication Activity Database

    Ebrille, E.; Konecny, T.; Konecny, D.; Špaček, R.; Jones, P.; Ambrož, Pavel; DeSimone, C.V.; Powel, B.D.; Hayes, D.L.; Friedman, P.A.; Asirvatham, S.J.

    2015-01-01

    Roč. 90, č. 2 (2015), s. 202-208 ISSN 0025-6196 Institutional support: RVO:67985815 Keywords : geomagnetic activity * implantable cardioverter defibrillator Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 5.920, year: 2015

  8. Sporting Activity Is Reduced 11 Years After First-Generation Autologous Chondrocyte Implantation in the Knee Joint.

    Science.gov (United States)

    Erdle, Benjamin; Herrmann, Simon; Porichis, Stella; Uhl, Markus; Ghanem, Nadir; Schmal, Hagen; Suedkamp, Norbert; Niemeyer, Philipp; Salzmann, Gian M

    2017-10-01

    Little is known about long-term sporting activity after periosteal autologous chondrocyte implantation (ACI-P) and its correlation to clinical, morphological, and ultrastructural cartilage characteristics on magnetic resonance imaging (MRI). To evaluate long-term sporting activity after ACI-P and to correlate with clinical and MRI findings. Case series; Level of evidence, 4. Patients who underwent ACI-P for isolated cartilage defects of the knee joint between 1997 and 2001 were analyzed for sporting ability for 3 different time points: lifetime until the onset of pain, the year before ACI-P, and 11 years (range, 9.0-13.4 years) postoperatively. Sporting activity was assessed and patients' level of activity scaled using standardized questionnaires. MRI scans of the affected knee joint at follow-up were analyzed using the MOCART (magnetic resonance observation of cartilage repair tissue) score and T2 mapping. Seventy of 86 patients (81% follow-up rate) consisting of 25 female and 45 male patients, with a mean age of 33.3 ± 10.2 years at the time of surgery, mean defect size of 6.5 ± 4.0 cm 2 , and 1.17 treated defects per patient, agreed to participate in the study at a mean 10.9 ± 1.1 years after ACI-P. Fifty-nine patients (69% of total; 84% of follow-up) agreed to MRI, allowing the complete evaluation of 71 transplant sites. Before the onset of symptoms (lifetime), 95.7% of patients played a mean 6.0 sporting activities at a competitive level. In the year before ACI-P, 81.4% of patients played a mean 3.4 sporting activities in 2.4 sessions during 5.4 hours per week at a recreational level. At follow-up, 82.9% of the patients played a mean 3.0 sporting activities in 1.8 sessions during 3.0 hours per week at a recreational level. In contrast to objective factors, 65.6% of the patients felt that their subjective sporting ability had improved or strongly improved after ACI-P, whereas 12.9% felt that their situation had declined or strongly declined, and 21.4% stated

  9. Functional brain activation differences in stuttering identified with a rapid fMRI sequence

    Science.gov (United States)

    Kraft, Shelly Jo; Choo, Ai Leen; Sharma, Harish; Ambrose, Nicoline G.

    2011-01-01

    The purpose of this study was to investigate whether brain activity related to the presence of stuttering can be identified with rapid functional MRI (fMRI) sequences that involved overt and covert speech processing tasks. The long-term goal is to develop sensitive fMRI approaches with developmentally appropriate tasks to identify deviant speech motor and auditory brain activity in children who stutter closer to the age at which recovery from stuttering is documented. Rapid sequences may be preferred for individuals or populations who do not tolerate long scanning sessions. In this report, we document the application of a picture naming and phoneme monitoring task in three minute fMRI sequences with adults who stutter (AWS). If relevant brain differences are found in AWS with these approaches that conform to previous reports, then these approaches can be extended to younger populations. Pairwise contrasts of brain BOLD activity between AWS and normally fluent adults indicated the AWS showed higher BOLD activity in the right inferior frontal gyrus (IFG), right temporal lobe and sensorimotor cortices during picture naming and and higher activity in the right IFG during phoneme monitoring. The right lateralized pattern of BOLD activity together with higher activity in sensorimotor cortices is consistent with previous reports, which indicates rapid fMRI sequences can be considered for investigating stuttering in younger participants. PMID:22133409

  10. Auditory cortical activation and plasticity after cochlear implantation measured by PET using fluorodeoxyglucose.

    Science.gov (United States)

    Łukaszewicz-Moszyńska, Zuzanna; Lachowska, Magdalena; Niemczyk, Kazimierz

    2014-01-01

    The purpose of this study was to evaluate possible relationships between duration of cochlear implant use and results of positron emission tomography (PET) measurements in the temporal lobes performed while subjects listened to speech stimuli. Other aspects investigated were whether implantation side impacts significantly on cortical representations of functions related to understanding speech (ipsi- or contralateral to the implanted side) and whether any correlation exists between cortical activation and speech therapy results. Objective cortical responses to acoustic stimulation were measured, using PET, in nine cochlear implant patients (age range: 15 to 50 years). All the patients suffered from bilateral deafness, were right-handed, and had no additional neurological deficits. They underwent PET imaging three times: immediately after the first fitting of the speech processor (activation of the cochlear implant), and one and two years later. A tendency towards increasing levels of activation in areas of the primary and secondary auditory cortex on the left side of the brain was observed. There was no clear effect of the side of implantation (left or right) on the degree of cortical activation in the temporal lobe. However, the PET results showed a correlation between degree of cortical activation and speech therapy results.

  11. Activation of boron and phosphorus atoms implanted in polycrystalline silicon films at low temperatures

    International Nuclear Information System (INIS)

    Andoh, Nobuyuki; Sameshima, Toshiyuki; Andoh, Yasunori

    2005-01-01

    Phosphorus atoms implanted in laser crystallized polycrystalline silicon films were activated by a heat treatment in air at 260 deg. C for 1, 3 and 24 h. Analysis of ultraviolet reflectivity of phosphorus-doped silicon films implanted by ion doping method at 4 keV revealed that the thickness of the top disordered layer formed by ion bombardment was 6 nm. It is reduced to 4 nm by a 3 h heat treatment at 260 deg. C by recrystallization of disordered region. The electrical conductance of silicon films implanted increased to 1.7x10 5 S/sq after 3 h heat treatment

  12. Biting Force and Muscle Activity in Implant-Supported Single Mandibular Overdentures Opposing Fixed Maxillary Dentition.

    Science.gov (United States)

    Al-Magaleh, Wafaʼa R; Abbas, Nadia A; Amer, Ashraf A; Abdelkader, Ann A; Bahgat, Basma

    2016-04-01

    This study aimed to investigate the relation between biting force and masticatory muscle activity in patients treated by 3 modalities of single mandibular dentures. Forty implants were placed in 10 patients with completely edentulous mandibles. The study was divided into 3 treatment stages. Initially, each patient received a conventional mandibular complete denture. At the second stage, 4 mandibular implants were placed and the denture was refitted to their abutments. Third stage comprised connecting the denture to the implants through ball attachments. During each treatment stage, maximum biting force and muscle activity were measured during maximum clenching and chewing of soft and hard food. Biting force demonstrated a statistically significant increase by time for the 3 treatment stages. The highest muscle activity was recorded for the conventional denture followed by the implant-supported overdenture without attachment, whereas the lowest values were recorded for the implant-supported overdenture with attachment. Biting force was related mainly to the quality of denture support. Muscle activity was higher in patients with conventional denture than with implant-supported prostheses (with or without attachments).

  13. The effect of excimer laser pretreatment on diffusion and activation of boron implanted in silicon

    International Nuclear Information System (INIS)

    Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Italia, M.; Privitera, V.; Fortunato, G.; Cuscuna, M.; Mariucci, L.

    2005-01-01

    We have investigated the effect of excimer laser annealing (ELA) on transient enhanced diffusion (TED) and activation of boron implanted in Si during subsequent rapid thermal annealing (RTA). It is observed that ELA with partial melting of the implanted region causes reduction of TED in the region that remains solid during ELA, where the diffusion length of boron is reduced by a factor of ∼4 as compared to the as-implanted sample. This is attributed to several mechanisms such as liquid-state annealing of a fraction of the implantation induced defects, introduction of excess vacancies during ELA, and solid-state annealing of the defects beyond the maximum melting depth by the heat wave propagating into the Si wafer. The ELA pretreatment provides a substantially improved electrical activation of boron during subsequent RTA

  14. Serial MRI studies using gadolinium DTPA in active multiple sclerosis

    International Nuclear Information System (INIS)

    Miller, D.H.; Johnson, G.; Barnes, D.; Rudge, P.; McDonald, W.I.

    1988-01-01

    It has been suggested that blood brain barrier (BBB) impairment is a necessary early event in the pathogenesis of the multiple sclerosis (MS) lesions. To evaluate such an hypothesis in vivo would require: (1) serial imaging studies using a modality with high sensitivity for detecting plaques; (2) a contrast enhancing agent which demonstrates BBB impairment. A serial magnetic resonance imaging (MRI) study was undertaken of a group of MS patients using the contrast agent gadolinium-DTPA. As it has been suggested that T 1 and T 2 relaxation times are longer in acute than chronic MS lesions, these were also measured. 3 refs.; 1 figure

  15. Intersession reliability of fMRI activation for heat pain and motor tasks.

    Science.gov (United States)

    Quiton, Raimi L; Keaser, Michael L; Zhuo, Jiachen; Gullapalli, Rao P; Greenspan, Joel D

    2014-01-01

    As the practice of conducting longitudinal fMRI studies to assess mechanisms of pain-reducing interventions becomes more common, there is a great need to assess the test-retest reliability of the pain-related BOLD fMRI signal across repeated sessions. This study quantitatively evaluated the reliability of heat pain-related BOLD fMRI brain responses in healthy volunteers across 3 sessions conducted on separate days using two measures: (1) intraclass correlation coefficients (ICC) calculated based on signal amplitude and (2) spatial overlap. The ICC analysis of pain-related BOLD fMRI responses showed fair-to-moderate intersession reliability in brain areas regarded as part of the cortical pain network. Areas with the highest intersession reliability based on the ICC analysis included the anterior midcingulate cortex, anterior insula, and second somatosensory cortex. Areas with the lowest intersession reliability based on the ICC analysis also showed low spatial reliability; these regions included pregenual anterior cingulate cortex, primary somatosensory cortex, and posterior insula. Thus, this study found regional differences in pain-related BOLD fMRI response reliability, which may provide useful information to guide longitudinal pain studies. A simple motor task (finger-thumb opposition) was performed by the same subjects in the same sessions as the painful heat stimuli were delivered. Intersession reliability of fMRI activation in cortical motor areas was comparable to previously published findings for both spatial overlap and ICC measures, providing support for the validity of the analytical approach used to assess intersession reliability of pain-related fMRI activation. A secondary finding of this study is that the use of standard ICC alone as a measure of reliability may not be sufficient, as the underlying variance structure of an fMRI dataset can result in inappropriately high ICC values; a method to eliminate these false positive results was used in this

  16. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... metallic items, which can distort MRI images removable dental work pens, pocket knives and eyeglasses body piercings In most cases, an MRI exam is safe for patients with metal implants, except for a few types. ...

  17. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... items, which can distort MRI images removable dental work pens, pocket knives and eyeglasses body piercings In most cases, an MRI exam is safe for patients with metal implants, except for a ...

  18. Comparison of PET and fMRI activation patterns during declarative memory processes

    International Nuclear Information System (INIS)

    Mottaghy, F.M.; Krause, B.J.; Schmidt, D.; Hautzel, H.; Mueller-Gaertner, H.-W.; Herzog, H.; Shah, N.J.; Halsband, U.

    2000-01-01

    Aim: In this study neuronal correlates of encoding and retrieval in paired association learning were compared using two different neuroimaging methods: Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Methods: 6 right-handed normal male volunteers took part in the study. Each subject underwent six 0-15-butanol PET scans and an fMRI study comprising four single epochs on a different day. The subjects had to learn and retrieve 12 word pairs which were visually presented (highly imaginable words, not semantically related). Results: Mean recall accuracy was 93% in the PET as well as in the fMRI experiment. During encoding and retrieval we found anterior cingulate cortex activation, and bilateral prefrontal cortex activation in both imaging modalities. Furthermore, we demonstrate the importance of the precuneus in episodic memory. With PET the results demonstrate frontopolar activations whereas fMRI fails to show activations in this area probably due to susceptibility artifacts. In fMRI we found additionally parahippocampal activation and due to the whole-brain coverage cerebellar activation during encoding. The distance between the center-of-mass activations in both modalities was 7.2±6.5 mm. Conclusion: There is a preponderance of commonalities in the activation patterns yielded with fMRI and PET. However, there are also important differences. The decision to choose one or the other neuroimaging modality should among other aspects depend on the study design (single subject vs. group study) and the task of interest. (orig.) [de

  19. Cost Analysis of MRI Services in Iran: An Application of Activity Based Costing Technique

    International Nuclear Information System (INIS)

    Bayati, Mohsen; Mahboub Ahari, Alireza; Badakhshan, Abbas; Gholipour, Mahin; Joulaei, Hassan

    2015-01-01

    Considerable development of MRI technology in diagnostic imaging, high cost of MRI technology and controversial issues concerning official charges (tariffs) have been the main motivations to define and implement this study. The present study aimed to calculate the unit-cost of MRI services using activity-based costing (ABC) as a modern cost accounting system and to fairly compare calculated unit-costs with official charges (tariffs). We included both direct and indirect costs of MRI services delivered in fiscal year 2011 in Shiraz Shahid Faghihi hospital. Direct allocation method was used for distribution of overhead costs. We used micro-costing approach to calculate unit-cost of all different MRI services. Clinical cost data were retrieved from the hospital registering system. Straight-line method was used for depreciation cost estimation. To cope with uncertainty and to increase the robustness of study results, unit costs of 33 MRI services was calculated in terms of two scenarios. Total annual cost of MRI activity center (AC) was calculated at USD 400,746 and USD 532,104 based on first and second scenarios, respectively. Ten percent of the total cost was allocated from supportive departments. The annual variable costs of MRI center were calculated at USD 295,904. Capital costs measured at USD 104,842 and USD 236, 200 resulted from the first and second scenario, respectively. Existing tariffs for more than half of MRI services were above the calculated costs. As a public hospital, there are considerable limitations in both financial and administrative databases of Shahid Faghihi hospital. Labor cost has the greatest share of total annual cost of Shahid Faghihi hospital. The gap between unit costs and tariffs implies that the claim for extra budget from health providers may not be relevant for all services delivered by the studied MRI center. With some adjustments, ABC could be implemented in MRI centers. With the settlement of a reliable cost accounting system

  20. Cost Analysis of MRI Services in Iran: An Application of Activity Based Costing Technique.

    Science.gov (United States)

    Bayati, Mohsen; Mahboub Ahari, Alireza; Badakhshan, Abbas; Gholipour, Mahin; Joulaei, Hassan

    2015-10-01

    Considerable development of MRI technology in diagnostic imaging, high cost of MRI technology and controversial issues concerning official charges (tariffs) have been the main motivations to define and implement this study. The present study aimed to calculate the unit-cost of MRI services using activity-based costing (ABC) as a modern cost accounting system and to fairly compare calculated unit-costs with official charges (tariffs). We included both direct and indirect costs of MRI services delivered in fiscal year 2011 in Shiraz Shahid Faghihi hospital. Direct allocation method was used for distribution of overhead costs. We used micro-costing approach to calculate unit-cost of all different MRI services. Clinical cost data were retrieved from the hospital registering system. Straight-line method was used for depreciation cost estimation. To cope with uncertainty and to increase the robustness of study results, unit costs of 33 MRI services was calculated in terms of two scenarios. Total annual cost of MRI activity center (AC) was calculated at USD 400,746 and USD 532,104 based on first and second scenarios, respectively. Ten percent of the total cost was allocated from supportive departments. The annual variable costs of MRI center were calculated at USD 295,904. Capital costs measured at USD 104,842 and USD 236, 200 resulted from the first and second scenario, respectively. Existing tariffs for more than half of MRI services were above the calculated costs. As a public hospital, there are considerable limitations in both financial and administrative databases of Shahid Faghihi hospital. Labor cost has the greatest share of total annual cost of Shahid Faghihi hospital. The gap between unit costs and tariffs implies that the claim for extra budget from health providers may not be relevant for all services delivered by the studied MRI center. With some adjustments, ABC could be implemented in MRI centers. With the settlement of a reliable cost accounting system

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

    International Nuclear Information System (INIS)

    Zhang Zhiqiang; Lu Guangming; Tian Lei; Sun Kanjian; Tan Qifu; Zhu Jianguo; Nie Cong; Hao Shaowei; Jiang Li; Liu Yijun

    2007-01-01

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

  2. EGF increases expression and activity of PAs in preimplantation rat embryos and their implantation rate

    Directory of Open Access Journals (Sweden)

    Har-Vardi Iris

    2007-01-01

    Full Text Available Abstract Background Embryo implantation plays a major role in embryogenesis and the outcome of pregnancy. Plasminogen activators (PAs have been implicated in mammalian fertilization, early stages of development and embryo implantation. As in-vitro developing embryos resulted in lower implantation rate than those developed in-vivo we assume that a reduced PAs activity may be involved. In the present work we studied the effect of EGF on PAs activity, quantity and embryo implantation. Methods Zygotes were flushed from rat oviducts on day one of pregnancy and grown in-vitro in R1ECM supplemented with EGF (10 ng/ml and were grown up to the blastocyst stage. The control groups were grown in the same medium without EGF. The distribution and quantity of the PAs were examined using fluorescence immunohistochemistry followed by measurement of PAs activity using the chromogenic assay. Implantation rate was studied using the embryo donation model. Results PAs distribution in the embryos was the same in EGF treated and untreated embryos. Both PAs were localized in the blastocysts' trophectoderm, supporting the assumption that PAs play a role in the implantation process in rats. EGF increased the quantity of uPA at all stages studied but the 8-cell stage as compared with controls. The tissue type PA (tPA content was unaffected except the 8-cell stage, which was increased. The activity of uPA increased gradually towards the blastocyst stage and more so due to the presence of EGF. The activity of tPA did not vary with the advancing developmental stages although it was also increased by EGF. The presence of EGF during the preimplantation development doubled the rate of implantation of the treated group as compared with controls.

  3. A living thick nanofibrous implant bifunctionalized with active growth factor and stem cells for bone regeneration

    Directory of Open Access Journals (Sweden)

    Eap S

    2015-02-01

    Full Text Available Sandy Eap,1,2,* Laetitia Keller,1–3,* Jessica Schiavi,1,2 Olivier Huck,1,2 Leandro Jacomine,4 Florence Fioretti,1,2 Christian Gauthier,4 Victor Sebastian,1,3,5 Pascale Schwinté,1,2 Nadia Benkirane-Jessel1,21INSERM, UMR 1109, Osteoarticular and Dental Regenerative Nanomedicine Laboratory, FMTS, Faculté de Médecine, Strasbourg, France; 2Faculté de Chirurgie Dentaire, Université de Strasbourg, Strasbourg, France; 3Department of Chemical Engineering, Aragon Nanoscience Institute, University of Zaragoza, Zaragoza, Spain; 4CNRS (National Center for Scientific Research, ICS (Charles Sadron Institute, Strasbourg, France; 5Networking Research Center of Bioengineering, Biomaterials and Nanomedicine, Zaragoza, Spain*These authors contributed equally to this workAbstract: New-generation implants focus on robust, durable, and rapid tissue regeneration to shorten recovery times and decrease risks of postoperative complications for patients. Herein, we describe a new-generation thick nanofibrous implant functionalized with active containers of growth factors and stem cells for regenerative nanomedicine. A thick electrospun poly(ε-caprolactone nanofibrous implant (from 700 µm to 1 cm thick was functionalized with chitosan and bone morphogenetic protein BMP-7 as growth factor using layer-by-layer technology, producing fish scale-like chitosan/BMP-7 nanoreservoirs. This extracellular matrix-mimicking scaffold enabled in vitro colonization and bone regeneration by human primary osteoblasts, as shown by expression of osteocalcin, osteopontin, and bone sialoprotein (BSPII, 21 days after seeding. In vivo implantation in mouse calvaria defects showed significantly more newly mineralized extracellular matrix in the functionalized implant compared to a bare scaffold after 30 days’ implantation, as shown by histological scanning electron microscopy/energy dispersive X-ray microscopy study and calcein injection. We have as well bifunctionalized our BMP-7

  4. Controlling the Biomimetic Implant Interface: Modulating Antimicrobial Activity by Spacer Design

    Science.gov (United States)

    Wisdom, Cate; Vanoosten, Sarah Kay; Boone, Kyle W.; Khvostenko, Dmytro; Arnold, Paul M.; Snead, Malcolm L.; Tamerler, Candan

    2016-08-01

    Surgical site infection is a common cause of post-operative morbidity, often leading to implant loosening, ultimately requiring revision surgery, increased costs and worse surgical outcomes. Since implant failure starts at the implant surface, creating and controlling the bio-material interface will play a critical role in reducing infection while improving host cell-to-implant interaction. Here, we engineered a biomimetic interface based upon a chimeric peptide that incorporates a titanium binding peptide (TiBP) with an antimicrobial peptide (AMP) into a single molecule to direct binding to the implant surface and deliver an antimicrobial activity against S. mutans and S. epidermidis, two bacteria which are linked with clinical implant infections. To optimize antimicrobial activity, we investigated the design of the spacer domain separating the two functional domains of the chimeric peptide. Lengthening and changing the amino acid composition of the spacer resulted in an improvement of minimum inhibitory concentration by a three-fold against S. mutans. Surfaces coated with the chimeric peptide reduced dramatically the number of bacteria, with up to a nine-fold reduction for S. mutans and a 48-fold reduction for S. epidermidis. Ab initio predictions of antimicrobial activity based on structural features were confirmed. Host cell attachment and viability at the biomimetic interface were also improved compared to the untreated implant surface. Biomimetic interfaces formed with this chimeric peptide offer interminable potential by coupling antimicrobial and improved host cell responses to implantable titanium materials, and this peptide based approach can be extended to various biomaterials surfaces.

  5. Effect of Unpleasant Loud Noise on Hippocampal Activities during Picture Encoding: An fMRI Study

    Science.gov (United States)

    Hirano, Yoshiyuki; Fujita, Masafumi; Watanabe, Kazuko; Niwa, Masami; Takahashi, Toru; Kanematsu, Masayuki; Ido, Yasushi; Tomida, Mihoko; Onozuka, Minoru

    2006-01-01

    The functional link between the amygdala and hippocampus in humans has not been well documented. We examined the effect of unpleasant loud noise on hippocampal and amygdaloid activities during picture encoding by means of fMRI, and on the correct response in humans. The noise reduced activity in the hippocampus during picture encoding, decreased…

  6. Pectus excavatum with delayed diagnosis of implant tear on MRI apparently causing recurrent postoperative seromas: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Iyer, Arti R.; Powell, Daniel K.; Irish, Robert D.; Math, Kevin R. [Mount Sinai Beth Israel Medical Center, Department of Radiology, New York, NY (United States)

    2015-08-15

    Seroma formation is the most common early postoperative complication after pectus excavatum repair, but later seromas are rare. While many seromas eventually resorb or decrease in size after aspiration, our case demonstrates recurrent seroma formation as a late complication of pectus excavatum repair in a patient with an implant tear. Postoperative seromas can result in prolonged chest wall pain, large chest wall masses, and increased mass effect on the heart with potential risk for resultant right ventricular outflow obstruction. This case report illustrates a solid silicone implant tear. Though rare, early recognition may help to decrease the likelihood of recurrent postoperative seromas. (orig.)

  7. Adhesion molecules levels in blood correlate with MRI activity and clinical activity in multiple sclerosis

    International Nuclear Information System (INIS)

    Millers, A.; Enina, G.; Platkajis, A.; Metra, M.; Kukaine, R.

    2002-01-01

    Research into pathogenesis of multiple sclerosis (MS) has prompted efforts to identify immunological markers associated with disease activity. Adhesion molecules ICAM-1 and VCAM-1 are associated with inflammatory mediated blood-brain barrier (BBB) dysfunction. In this study investigates the correlation between blood level of circulating ICAM-1 and VCAM-1 and magnetic resonance imaging (MRI) activity in different clinical phases of patients with MS. We show that RRMS and SPMS patients in clinically active phase with Gd-enhancing lesions in CNS had higher blood levels of cICAM-1 and cVCAM-1 compared these parameters levers of RRMS patients in remission stage. These results suggest that cICAM-1 and cVCAM-1 is a sensitive indicator of disease activity associated with BBB inflammatory dysfunction. Elevated blood level of cICAM-1 more strongly correlated with clinical activity and BBB damage, than cVCAM-1 and that could be used as biological marker of disease activity. Circulating VCAM-1 as an early indicator of BBB disturbance, may also serve as marker of beneficial activity in relapses phase of MS course. (authors)

  8. An eight-year prospective controlled study about the safety and diagnostic value of cardiac and non-cardiac 1.5-T MRI in patients with a conventional pacemaker or a conventional implantable cardioverter defibrillator.

    Science.gov (United States)

    Lupo, Pierpaolo; Cappato, Riccardo; Di Leo, Giovanni; Secchi, Francesco; Papini, Giacomo D E; Foresti, Sara; Ali, Hussam; De Ambroggi, Guido M G; Sorgente, Antonio; Epicoco, Gianluca; Cannaò, Paola M; Sardanelli, Francesco

    2018-06-01

    To investigate safety and diagnostic value of 1.5-T MRI in carriers of conventional pacemaker (cPM) or conventional implantable defibrillator (cICD). We prospectively compared cPM/cICD-carriers undergoing MRI (study group, SG), excluding those device-dependent or implanted cPM/cICD-carriers undergoing chest x-ray, CT or follow-up (reference group, RG). 142 MRI (55 cardiac) were performed in 120 patients with cPM (n=71) or cICD (n=71). In the RG 98 measurements were performed in 95 patients with cPM (n=40) or cICD (n=58). No adverse events were observed. No MRI prolonged/interrupted. All cPM/cICD were correctly reprogrammed after MRI without malfunctions. One temporary communication failure was observed in one cPM-carrier. Immediately after MRI, 12/14 device interrogation parameters did not change significantly (clinically negligible changes of battery voltage and cICD charging time), without significant variations for SG versus RG. Three-12 months after MRI, 9/11 device interrogation parameters did not change significantly (clinically negligible changes of battery impedance/voltage). Non-significant changes of three markers of myocardial necrosis. Non-cardiac MRI: 82/87 diagnostic without artefacts; 4/87 diagnostic with artefacts; 1/87 partially diagnostic. Cardiac MRI: in cPM-carriers, 14/15 diagnostic with artefacts, 1/15 partially diagnostic; in cICD-carriers, 9/40 diagnostic with artefacts, 22 partially diagnostic, nine non-diagnostic. A favourable risk-benefit ratio of 1.5-T MRI in cPM/cICD carriers was reported. • Cooperation between radiologists and cardiac electrophysiologists allowed safe 1.5-T MRI in cPM/cICD-carriers. • No adverse events for 142 MRI in 71 cPM-carriers and 71 cICD-carriers. • Ninety-nine per cent (86/87) of non-cardiac MRI in cPM/cICD-carriers were diagnostic. • All cPM-carrier cardiac MRIs had artefacts, 14 examinations diagnostic, 1 partially diagnostic. • Twenty-three per cent (9/40) of cardiac MRI in cICD-carriers were non-diagnostic.

  9. Predicting and monitoring response to chemotherapy by 1,3-bis(2-chloroethyl)-1-nitrosourea in subcutaneously implanted 9L glioma using the apparent diffusion coefficient of water and 23Na MRI.

    Science.gov (United States)

    Babsky, Andriy M; Hekmatyar, S K; Zhang, Hong; Solomon, James L; Bansal, Navin

    2006-07-01

    To examine the effects of the alkylating anticancer drug 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) on (23)Na MRI and the water apparent diffusion coefficient (ADC) in subcutaneously- (sc-) implanted 9L glioma in rats. (23)Na MRI and (1)H water ADC measurements were performed on sham-treated control (N = 6) and BCNU-treated (N = 15) Fisher rats one day before BCNU injection and then one, three, and five days after BCNU injection. The BCNU-treated tumors were divided into BCNU-responsive (R(BCNU)) and BCNU-nonresponsive (NR(BCNU)) groups depending on the tumor volume changes that occurred after therapy. The pretreatment (23)Na MRI signal intensity (SI) and water ADC values were higher in R(BCNU) tumors compared to NR(BCNU) tumors. (23)Na MRI SI and water ADC increased with tumor growth in control and NR(BCNU) groups, but these changes were interrupted by BCNU therapy in R(BCNU) group. (23)Na MRI and water ADC measurements may be useful for predicting and monitoring response to chemotherapy in some tumors. However, the changes that occurred in (23)Na MRI SI and water ADC in sc-implanted 9L tumors are in contrast to previously published results for BCNU therapy of orthotopic 9L tumors. This may have important implications for monitoring therapy response in tumors. (c) 2006 Wiley-Liss, Inc.

  10. Cobalt Alloy Implant Debris Induces Inflammation and Bone Loss Primarily through Danger Signaling, Not TLR4 Activation: Implications for DAMP-ening Implant Related Inflammation

    OpenAIRE

    Samelko, Lauryn; Landgraeber, Stefan; McAllister, Kyron; Jacobs, Joshua; Hallab, Nadim James

    2016-01-01

    Cobalt alloy debris has been implicated as causative in the early failure of some designs of current total joint implants. The ability of implant debris to cause excessive inflammation via danger signaling (NLRP3 inflammasome) vs. pathogen associated pattern recognition receptors (e.g. Toll-like receptors; TLRs) remains controversial. Recently, specific non-conserved histidines on human TLR4 have been shown activated by cobalt and nickel ions in solution. However, whether this TLR activation ...

  11. Activation and thermal stability of ultra-shallow B+-implants in Ge

    International Nuclear Information System (INIS)

    Yates, B. R.; Darby, B. L.; Jones, K. S.; Petersen, D. H.; Hansen, O.; Lin, R.; Nielsen, P. F.; Romano, L.; Doyle, B. L.; Kontos, A.

    2012-01-01

    The activation and thermal stability of ultra-shallow B + implants in crystalline (c-Ge) and preamorphized Ge (PA-Ge) following rapid thermal annealing was investigated using micro Hall effect and ion beam analysis techniques. The residual implanted dose of ultra-shallow B + implants in Ge was characterized using elastic recoil detection and was determined to correlate well with simulations with a dose loss of 23.2%, 21.4%, and 17.6% due to ion backscattering for 2, 4, and 6 keV implants in Ge, respectively. The electrical activation of ultra-shallow B + implants at 2, 4, and 6 keV to fluences ranging from 5.0 × 10 13 to 5.0 × 10 15 cm −2 was studied using micro Hall effect measurements after annealing at 400–600 °C for 60 s. For both c-Ge and PA-Ge, a large fraction of the implanted dose is rendered inactive due to the formation of a presumable B-Ge cluster. The B lattice location in samples annealed at 400 °C for 60 s was characterized by channeling analysis with a 650 keV H + beam by utilizing the 11 B(p, α)2α nuclear reaction and confirmed the large fraction of off-lattice B for both c-Ge and PA-Ge. Within the investigated annealing range, no significant change in activation was observed. An increase in the fraction of activated dopant was observed with increasing energy which suggests that the surface proximity and the local point defect environment has a strong impact on B activation in Ge. The results suggest the presence of an inactive B-Ge cluster for ultra-shallow implants in both c-Ge and PA-Ge that remains stable upon annealing for temperatures up to 600 °C.

  12. Delayed gadolinium-enhanced MRI of cartilage and T2 mapping for evaluation of reparative cartilage-like tissue after autologous chondrocyte implantation associated with Atelocollagen-based scaffold in the knee

    Energy Technology Data Exchange (ETDEWEB)

    Tadenuma, Taku; Uchio, Yuji; Kumahashi, Nobuyuki; Iwasa, Junji [Shimane University School of Medicine, Department of Orthopaedic Surgery, Izumo-shi, Shimane-ken (Japan); Fukuba, Eiji; Kitagaki, Hajime [Shimane University School of Medicine, Department of Radiology, Izumo-shi, Shimane-ken (Japan); Ochi, Mitsuo [Hiroshima University, Department of Orthopaedic Surgery, Integrated Health Sciences, Institute of Biomedical and Health Sciences, Minami-ku, Hiroshima (Japan)

    2016-10-15

    To elucidate the quality of tissue-engineered cartilage after an autologous chondrocyte implantation (ACI) technique with Atelocollagen gel as a scaffold in the knee in the short- to midterm postoperatively, we assessed delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and T2 mapping and clarified the relationship between T1 and T2 values and clinical results. In this cross-sectional study, T1 and T2 mapping were performed on 11 knees of 8 patients (mean age at ACI, 37.2 years) with a 3.0-T MRI scanner. T1{sub implant} and T2{sub implant} values were compared with those of the control cartilage region (T1{sub control} and T2{sub control}). Lysholm scores were also assessed for clinical evaluation. The relationships between the T1 and T2 values and the clinical Lysholm score were also assessed. There were no significant differences in the T1 values between the T1{sub implant} (386.64 ± 101.78 ms) and T1{sub control} (375.82 ± 62.89 ms) at the final follow-up. The implants showed significantly longer T2 values compared to the control cartilage (53.83 ± 13.89 vs. 38.21 ± 4.43 ms). The postoperative Lysholm scores were significantly higher than the preoperative scores. A significant correlation was observed between T1{sub implant} and clinical outcomes, but not between T2{sub implant} and clinical outcomes. Third-generation ACI implants might have obtained an almost equivalent glycosaminoglycan concentration compared to the normal cartilage, but they had lower collagen density at least 3 years after transplantation. The T1{sub implant} value, but not the T2 value, might be a predictor of clinical outcome after ACI. (orig.)

  13. Delayed gadolinium-enhanced MRI of cartilage and T2 mapping for evaluation of reparative cartilage-like tissue after autologous chondrocyte implantation associated with Atelocollagen-based scaffold in the knee

    International Nuclear Information System (INIS)

    Tadenuma, Taku; Uchio, Yuji; Kumahashi, Nobuyuki; Iwasa, Junji; Fukuba, Eiji; Kitagaki, Hajime; Ochi, Mitsuo

    2016-01-01

    To elucidate the quality of tissue-engineered cartilage after an autologous chondrocyte implantation (ACI) technique with Atelocollagen gel as a scaffold in the knee in the short- to midterm postoperatively, we assessed delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and T2 mapping and clarified the relationship between T1 and T2 values and clinical results. In this cross-sectional study, T1 and T2 mapping were performed on 11 knees of 8 patients (mean age at ACI, 37.2 years) with a 3.0-T MRI scanner. T1 implant and T2 implant values were compared with those of the control cartilage region (T1 control and T2 control ). Lysholm scores were also assessed for clinical evaluation. The relationships between the T1 and T2 values and the clinical Lysholm score were also assessed. There were no significant differences in the T1 values between the T1 implant (386.64 ± 101.78 ms) and T1 control (375.82 ± 62.89 ms) at the final follow-up. The implants showed significantly longer T2 values compared to the control cartilage (53.83 ± 13.89 vs. 38.21 ± 4.43 ms). The postoperative Lysholm scores were significantly higher than the preoperative scores. A significant correlation was observed between T1 implant and clinical outcomes, but not between T2 implant and clinical outcomes. Third-generation ACI implants might have obtained an almost equivalent glycosaminoglycan concentration compared to the normal cartilage, but they had lower collagen density at least 3 years after transplantation. The T1 implant value, but not the T2 value, might be a predictor of clinical outcome after ACI. (orig.)

  14. Delayed gadolinium-enhanced MRI of cartilage and T2 mapping for evaluation of reparative cartilage-like tissue after autologous chondrocyte implantation associated with Atelocollagen-based scaffold in the knee.

    Science.gov (United States)

    Tadenuma, Taku; Uchio, Yuji; Kumahashi, Nobuyuki; Fukuba, Eiji; Kitagaki, Hajime; Iwasa, Junji; Ochi, Mitsuo

    2016-10-01

    To elucidate the quality of tissue-engineered cartilage after an autologous chondrocyte implantation (ACI) technique with Atelocollagen gel as a scaffold in the knee in the short- to midterm postoperatively, we assessed delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and T2 mapping and clarified the relationship between T1 and T2 values and clinical results. In this cross-sectional study, T1 and T2 mapping were performed on 11 knees of 8 patients (mean age at ACI, 37.2 years) with a 3.0-T MRI scanner. T1implant and T2implant values were compared with those of the control cartilage region (T1control and T2control). Lysholm scores were also assessed for clinical evaluation. The relationships between the T1 and T2 values and the clinical Lysholm score were also assessed. There were no significant differences in the T1 values between the T1implant (386.64 ± 101.78 ms) and T1control (375.82 ± 62.89 ms) at the final follow-up. The implants showed significantly longer T2 values compared to the control cartilage (53.83 ± 13.89 vs. 38.21 ± 4.43 ms). The postoperative Lysholm scores were significantly higher than the preoperative scores. A significant correlation was observed between T1implant and clinical outcomes, but not between T2implant and clinical outcomes. Third-generation ACI implants might have obtained an almost equivalent glycosaminoglycan concentration compared to the normal cartilage, but they had lower collagen density at least 3 years after transplantation. The T1implant value, but not the T2 value, might be a predictor of clinical outcome after ACI.

  15. Study on cerebral activation areas during repetition with functional MRI in normal adults

    International Nuclear Information System (INIS)

    Koseki, Yohju

    2009-01-01

    For cerebral activation of speech areas in functional MRI (f-MRI) study, the usefulness of an optical microphone, which made it possible to perform task repetition at real time during scanning, was examined. Subjects were 25 healthy adults (mean age, 27.1±5.6 years), who consisted of 15 right-handed and 10 left-handed or ambidextrous persons. Tasks comprised repetition of monosyllables, non-words, words and sentences. The repetition tasks were covertly performed during scanning of f-MRI by using an optical microphone. In both the right-handed and non-right-handed groups, activations in the left superior temporal gyrus (sensory speech area) were most frequently observed during all of the tasks. In the right-handed group, activations in the left inferior frontal (motor speech area) and superior temporal gyri were significantly more often observed than those in the right inferior frontal and superior temporal gyri. From an assessment of the laterality index (LI), left-side dominant activation was frequently seen in most of the cerebral regions including sensory and motor speech areas, although right-side and bilateral dominant activations were observed in a few cases. In both groups, activations in regions associated with sensory speech were significantly more often seen than those in regions associated with motor speech. The present predominant activations in regions involved in sensory speech indicate that the optical microphone is useful in f-MRI studies using task repetition. (author)

  16. Activation and thermal stability of ultra-shallow B+-implants in Ge

    DEFF Research Database (Denmark)

    Yates, B. R.; Darby, B. L.; Petersen, Dirch Hjorth

    2012-01-01

    The activation and thermal stability of ultra-shallow B+ implants in crystalline (c-Ge) and preamorphized Ge (PA-Ge) following rapid thermal annealing was investigated using micro Hall effect and ion beam analysis techniques. The residual implanted dose of ultra-shallow B+ implants in Ge...... from 5.0 × 1013 to 5.0 × 1015 cm-2 was studied using micro Hall effect measurements after annealing at 400-600 °C for 60 s. For both c-Ge and PA-Ge, a large fraction of the implanted dose is rendered inactive due to the formation of a presumable B-Ge cluster. The B lattice location in samples annealed...... was characterized using elastic recoil detection and was determined to correlate well with simulations with a dose loss of 23.2%, 21.4%, and 17.6% due to ion backscattering for 2, 4, and 6 keV implants in Ge, respectively. The electrical activation of ultra-shallow B+ implants at 2, 4, and 6 keV to fluences ranging...

  17. Efficacy of ultrasound elastography in detecting active myositis in children: can it replace MRI?

    Energy Technology Data Exchange (ETDEWEB)

    Berko, Netanel S.; Levin, Terry L. [Montefiore Medical Center, Department of Radiology, Bronx, NY (United States); Hay, Arielle [Montefiore Medical Center, Department of Pediatrics, Division of Pediatric Rheumatology, Bronx, NY (United States); Miami Children' s Hospital, Department of Pediatrics, Miami, FL (United States); Sterba, Yonit; Wahezi, Dawn [Montefiore Medical Center, Department of Pediatrics, Division of Pediatric Rheumatology, Bronx, NY (United States)

    2015-09-15

    Juvenile idiopathic inflammatory myopathy is a rare yet potentially debilitating condition. MRI is used both for diagnosis and to assess response to treatment. No study has evaluated the performance of US elastography in the diagnosis of this condition in children. To assess the performance of compression-strain US elastography in detecting active myositis in children with clinically confirmed juvenile idiopathic inflammatory myopathy and to compare its efficacy to MRI. Children with juvenile idiopathic inflammatory myopathy underwent non-contrast MR imaging as well as compression-strain US elastography of the quadriceps muscles. Imaging findings from both modalities were compared to each other as well as to the clinical determination of active disease based on physical examination and laboratory data. Active myositis on MR was defined as increased muscle signal on T2-weighted images. Elastography images were defined as normal or abnormal based on a previously published numerical scale of muscle elastography in normal children. Muscle echogenicity was graded as normal or abnormal based on gray-scale sonographic images. Twenty-one studies were conducted in 18 pediatric patients (15 female, 3 male; age range 3-19 years). Active myositis was present on MRI in ten cases. There was a significant association between abnormal MRI and clinically active disease (P = 0.012). US elastography was abnormal in 4 of 10 cases with abnormal MRI and in 4 of 11 cases with normal MRI. There was no association between abnormal elastography and either MRI (P > 0.999) or clinically active disease (P > 0.999). Muscle echogenicity was normal in 11 patients; all 11 had normal elastography. Of the ten patients with increased muscle echogenicity, eight had abnormal elastography. There was a significant association between muscle echogenicity and US elastography (P < 0.001). The positive and negative predictive values for elastography in the determination of active myositis were 75% and 31

  18. Efficacy of ultrasound elastography in detecting active myositis in children: can it replace MRI?

    International Nuclear Information System (INIS)

    Berko, Netanel S.; Levin, Terry L.; Hay, Arielle; Sterba, Yonit; Wahezi, Dawn

    2015-01-01

    Juvenile idiopathic inflammatory myopathy is a rare yet potentially debilitating condition. MRI is used both for diagnosis and to assess response to treatment. No study has evaluated the performance of US elastography in the diagnosis of this condition in children. To assess the performance of compression-strain US elastography in detecting active myositis in children with clinically confirmed juvenile idiopathic inflammatory myopathy and to compare its efficacy to MRI. Children with juvenile idiopathic inflammatory myopathy underwent non-contrast MR imaging as well as compression-strain US elastography of the quadriceps muscles. Imaging findings from both modalities were compared to each other as well as to the clinical determination of active disease based on physical examination and laboratory data. Active myositis on MR was defined as increased muscle signal on T2-weighted images. Elastography images were defined as normal or abnormal based on a previously published numerical scale of muscle elastography in normal children. Muscle echogenicity was graded as normal or abnormal based on gray-scale sonographic images. Twenty-one studies were conducted in 18 pediatric patients (15 female, 3 male; age range 3-19 years). Active myositis was present on MRI in ten cases. There was a significant association between abnormal MRI and clinically active disease (P = 0.012). US elastography was abnormal in 4 of 10 cases with abnormal MRI and in 4 of 11 cases with normal MRI. There was no association between abnormal elastography and either MRI (P > 0.999) or clinically active disease (P > 0.999). Muscle echogenicity was normal in 11 patients; all 11 had normal elastography. Of the ten patients with increased muscle echogenicity, eight had abnormal elastography. There was a significant association between muscle echogenicity and US elastography (P < 0.001). The positive and negative predictive values for elastography in the determination of active myositis were 75% and 31

  19. PET/MRI in the presence of metal implants: Completion of the attenuation map from PET emission data

    DEFF Research Database (Denmark)

    Fuin, Niccolo; Pedemonte, Stefano; Catalano, Onofrio A.

    2017-01-01

    of radioactivity and attenuation from the emission data to determine the position, shape, and linear attenuation coefficient (LAC) of metallic implants. Methods: The initial estimate of the attenuation map was obtained using the MR Dixon method currently available on the Siemens Biograph mMR scanner...

  20. Evaluation of MRI artifacts caused by metallic dental implants and classification of the dental materials in use

    Czech Academy of Sciences Publication Activity Database

    Starčuk jr., Zenon; Bartušek, Karel; Hubálková, H.; Bachorec, T.; Starčuková, Jana; Krupa, P.

    2006-01-01

    Roč. 6, č. 2 (2006), s. 24-27 ISSN 1335-8871 R&D Projects: GA MZd NR8110 Institutional research plan: CEZ:AV0Z20650511 Keywords : magnetic resonance imaging * artifacts * metallic implants * dental alloys * magnetic susceptibility Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  1. Bioreactor activated graft material for early implant fixation in bone

    DEFF Research Database (Denmark)

    Snoek Henriksen, Susan; Ding, Ming; Overgaard, Søren

    2011-01-01

    from the iliac crest. For both groups, mononuclear cells were isolated, and injected into a perfusion bioreactor (Millenium Biologix AG, Switzerland). Scaffold granules (Ø~900-1500 µm, ~88% porosity) in group 1, consisted of hydroxyapatite (HA, 70%) with β-tricalcium-phosphate (β-TCP, 30%) (Danish....... The superficial part was used for mechanical testing and micro-CT scanning, and the profound part for histomorphometry. Push-out tests were performed on an 858 Bionix MTS hydraulic materials testing machine (MTS Systems Corporation, USA). Shear mechanical properties between implant and newly generated bone were...

  2. Efficacy of ultrasound elastography in detecting active myositis in children: can it replace MRI?

    Science.gov (United States)

    Berko, Netanel S; Hay, Arielle; Sterba, Yonit; Wahezi, Dawn; Levin, Terry L

    2015-09-01

    Juvenile idiopathic inflammatory myopathy is a rare yet potentially debilitating condition. MRI is used both for diagnosis and to assess response to treatment. No study has evaluated the performance of US elastography in the diagnosis of this condition in children. To assess the performance of compression-strain US elastography in detecting active myositis in children with clinically confirmed juvenile idiopathic inflammatory myopathy and to compare its efficacy to MRI. Children with juvenile idiopathic inflammatory myopathy underwent non-contrast MR imaging as well as compression-strain US elastography of the quadriceps muscles. Imaging findings from both modalities were compared to each other as well as to the clinical determination of active disease based on physical examination and laboratory data. Active myositis on MR was defined as increased muscle signal on T2-weighted images. Elastography images were defined as normal or abnormal based on a previously published numerical scale of muscle elastography in normal children. Muscle echogenicity was graded as normal or abnormal based on gray-scale sonographic images. Twenty-one studies were conducted in 18 pediatric patients (15 female, 3 male; age range 3-19 years). Active myositis was present on MRI in ten cases. There was a significant association between abnormal MRI and clinically active disease (P = 0.012). US elastography was abnormal in 4 of 10 cases with abnormal MRI and in 4 of 11 cases with normal MRI. There was no association between abnormal elastography and either MRI (P > 0.999) or clinically active disease (P > 0.999). Muscle echogenicity was normal in 11 patients; all 11 had normal elastography. Of the ten patients with increased muscle echogenicity, eight had abnormal elastography. There was a significant association between muscle echogenicity and US elastography (P myositis were 75% and 31%, respectively, with a sensitivity of 40% and specificity of 67%. Compression-strain US

  3. Exposures to 222Rn and its progeny derived from implanted 210Po activity

    International Nuclear Information System (INIS)

    Nikezic, D.; Yu, K.N.

    2006-01-01

    The Jacobi room model was applied to study the relative contributions from the unattached and attached fractions to the implanted activity of 210 Po. It was found that under normal conditions, about 85% of the implantation was due to the unattached fraction. Sensitivity analysis was performed to identify the most important factors that influence the deposition and implantation of radon progeny. The main factors affecting the incorporation of 210 Po are the attachment rate, deposition rate of unattached progeny and the surface to volume ratio of the room. The calibration curves, which related the 210 Po activity per unit surface area to the concentrations of 222 Rn and of the radon progeny, were determined as functions of exposure times. The implanted activity is found to distribute close to a lognormal distribution. For an exposure of 20 years, the distribution has a geometric standard deviation of 2.2 and a geometric mean of 0.023Bq/m 2 /(Bq/m 3 ). The last value is considered as the calibration coefficient of the glass response in terms of the implanted 210 Po activity per unit surface area per unit concentration of 222 Rn for an exposure period of 20 years

  4. HACMAC: A reliable human activity-based medium access control for implantable body sensor networks

    NARCIS (Netherlands)

    Karuppiah Ramachandran, Vignesh Raja; Havinga, Paul J.M.; Meratnia, Nirvana

    Chronic care is an eminent application of implantable body sensor networks (IBSN). Performing physical activities such as walking, running, and sitting is unavoidable during the long-term monitoring of chronic-care patients. These physical activities cripple the radio frequency (RF) signal between

  5. Early functional MRI activation predicts motor outcome after ischemic stroke: a longitudinal, multimodal study.

    Science.gov (United States)

    Du, Juan; Yang, Fang; Zhang, Zhiqiang; Hu, Jingze; Xu, Qiang; Hu, Jianping; Zeng, Fanyong; Lu, Guangming; Liu, Xinfeng

    2018-05-15

    An accurate prediction of long term outcome after stroke is urgently required to provide early individualized neurorehabilitation. This study aimed to examine the added value of early neuroimaging measures and identify the best approaches for predicting motor outcome after stroke. This prospective study involved 34 first-ever ischemic stroke patients (time since stroke: 1-14 days) with upper limb impairment. All patients underwent baseline multimodal assessments that included clinical (age, motor impairment), neurophysiological (motor-evoked potentials, MEP) and neuroimaging (diffusion tensor imaging and motor task-based fMRI) measures, and also underwent reassessment 3 months after stroke. Bivariate analysis and multivariate linear regression models were used to predict the motor scores (Fugl-Meyer assessment, FMA) at 3 months post-stroke. With bivariate analysis, better motor outcome significantly correlated with (1) less initial motor impairment and disability, (2) less corticospinal tract injury, (3) the initial presence of MEPs, (4) stronger baseline motor fMRI activations. In multivariate analysis, incorporating neuroimaging data improved the predictive accuracy relative to only clinical and neurophysiological assessments. Baseline fMRI activation in SMA was an independent predictor of motor outcome after stroke. A multimodal model incorporating fMRI and clinical measures best predicted the motor outcome following stroke. fMRI measures obtained early after stroke provided independent prediction of long-term motor outcome.

  6. Enhancing motor network activity using real-time functional MRI neurofeedback of left premotor cortex

    Directory of Open Access Journals (Sweden)

    Theo Ferreira Marins

    2015-12-01

    Full Text Available Neurofeedback by functional Magnetic Resonance Imaging (fMRI is a technique of potential therapeutic relevance that allows individuals to be aware of their own neurophysiological responses and to voluntarily modulate the activity of specific brain regions, such as the premotor cortex (PMC, important for motor recovery after brain injury. We investigated (i whether healthy human volunteers are able to up-regulate the activity of the left PMC during a right hand finger tapping motor imagery (MI task while receiving continuous fMRI-neurofeedback, and (ii whether successful modulation of brain activity influenced non-targeted motor control regions. During the MI task, participants of the neurofeedback group (NFB received ongoing visual feedback representing the level of fMRI responses within their left PMC. Control (CTL group participants were shown similar visual stimuli, but these were non-contingent on brain activity. Both groups showed equivalent levels of behavioral ratings on arousal and motor imagery, before and during the fMRI protocol. In the NFB, but not in CLT group, brain activation during the last run compared to the first run revealed increased activation in the left PMC. In addition, the NFB group showed increased activation in motor control regions extending beyond the left PMC target area, including the supplementary motor area, basal ganglia and cerebellum. Moreover, in the last run, the NFB group showed stronger activation in the left PMC/inferior frontal gyrus when compared to the CTL group. Our results indicate that modulation of PMC and associated motor control areas can be achieved during a single neurofeedback-fMRI session. These results contribute to a better understanding of the underlying mechanisms of MI-based neurofeedback training, with direct implications for rehabilitation strategies in severe brain disorders, such as stroke.

  7. Self-Regulation of Amygdala Activation Using Real-Time fMRI Neurofeedback

    Science.gov (United States)

    Phillips, Raquel; Alvarez, Ruben P.; Simmons, W. Kyle; Bellgowan, Patrick; Drevets, Wayne C.; Bodurka, Jerzy

    2011-01-01

    Real-time functional magnetic resonance imaging (rtfMRI) with neurofeedback allows investigation of human brain neuroplastic changes that arise as subjects learn to modulate neurophysiological function using real-time feedback regarding their own hemodynamic responses to stimuli. We investigated the feasibility of training healthy humans to self-regulate the hemodynamic activity of the amygdala, which plays major roles in emotional processing. Participants in the experimental group were provided with ongoing information about the blood oxygen level dependent (BOLD) activity in the left amygdala (LA) and were instructed to raise the BOLD rtfMRI signal by contemplating positive autobiographical memories. A control group was assigned the same task but was instead provided with sham feedback from the left horizontal segment of the intraparietal sulcus (HIPS) region. In the LA, we found a significant BOLD signal increase due to rtfMRI neurofeedback training in the experimental group versus the control group. This effect persisted during the Transfer run without neurofeedback. For the individual subjects in the experimental group the training effect on the LA BOLD activity correlated inversely with scores on the Difficulty Identifying Feelings subscale of the Toronto Alexithymia Scale. The whole brain data analysis revealed significant differences for Happy Memories versus Rest condition between the experimental and control groups. Functional connectivity analysis of the amygdala network revealed significant widespread correlations in a fronto-temporo-limbic network. Additionally, we identified six regions — right medial frontal polar cortex, bilateral dorsomedial prefrontal cortex, left anterior cingulate cortex, and bilateral superior frontal gyrus — where the functional connectivity with the LA increased significantly across the rtfMRI neurofeedback runs and the Transfer run. The findings demonstrate that healthy subjects can learn to regulate their amygdala

  8. Effect of B+ Flux on the electrical activation of ultra-shallow B+ implants in Ge

    DEFF Research Database (Denmark)

    Yates, B.R.; Darby, B.L.; Petersen, Dirch Hjorth

    2012-01-01

    + implants at 2 keV to a dose of 5.0×1014 cm-2 at beam currents ranging from 0.4 to 6.4 mA has been studied using micro Hall effect measurements after annealing at 400°C for 60 s. It has been shown that the sheet number increases with beam current across the investigated range with electrical activation......The residual implanted dose of ultra-shallow B+ implants in Ge was characterized using elastic recoil detection and was determined to correlate well with simulations with a dose loss of 23% due to ion backscattering for 2 keV implants in Ge. The electrical characterization of ultra-shallow B...... being 76% higher at 6.4 mA as compared to 0.4mA. However, at 6.4 mA, the electrically active fraction remained low at 11.4%. Structural characterization revealed that the implanted region remained crystalline and amorphization is not able to explain the increased activation. The results suggest...

  9. Cerebral activation during Chinese semantic associative task in Xinjiang' Uyghurs: a functional MRI study

    International Nuclear Information System (INIS)

    Yang Lixia; Jia Wenxiao; Tang Weijun; Wang Hong; Ding Shuang; Wang Hao

    2010-01-01

    Objective: To explore the cerebral activation in Xinjiang' Uyghurs when performing a Chinese word tasks by the functional magnetic resonance image (fMRI). Methods: Twenty-one healthy Xinjiang' Uyghurs and 11 healthy Hans were scanned using functional magnetic resonance imaging (fMRI) on a 1.5 T MRI scanner with a single run. Different Chinese words were displayed in each block to avoid any practice effect. SPM5.0 software was used for image data processing. To evaluate the inter subject consistency of brain activations associated with Chinese character and word reading, we created penetrance maps by combining binary individual functional maps. Results: For Uyghur-Chinese bilingual subjects, activations related to generated a word that was semantically related to each stimulus. The results indicated that reading Chinese is characterized by extensive activity of the neural systems. Peak activations occurred in the left middle frontal cortex at Brodmann Areas (BA9 and BA47). The left temporal (BA37) cortices were also strongly activated. Other important activated areas included bilateral visual systems (BA17-19) and cerebellum. The location of peak activation in the left frontal regions was similar in Native Uyghurs and Hans. But the active areas in Uyghurs are more extensive than that of Hans. Conclusions: The location of peak activation in the left frontal regions was similar in Native Uyghurs and Hans. More brain areas were needed for Xinjiang' Uyghur speakers during processing Chinese words. (authors)

  10. Contrast-enhanced MRI compared with the physical examination in the evaluation of disease activity in juvenile idiopathic arthritis

    International Nuclear Information System (INIS)

    Hemke, Robert; Maas, Mario; Veenendaal, Mira van; Kuijpers, Taco W.; Dolman, Koert M.; Rossum, Marion A.J. van; Berg, J.M. van den

    2014-01-01

    To assess the value of magnetic resonance imaging (MRI) in discriminating between active and inactive juvenile idiopathic arthritis (JIA) patients and to compare physical examination outcomes with MRI outcomes in the assessment of disease status in JIA patients. Consecutive JIA patients with knee involvement were prospectively studied using an open-bore MRI. Imaging findings from 146 JIA patients were analysed (59.6 % female; mean age, 12.9 years). Patients were classified as clinically active or inactive. MRI features were evaluated using the JAMRIS system, comprising validated scores for synovial hypertrophy, bone marrow oedema, cartilage lesions and bone erosions. Inter-reader reliability was good for all MRI features (intra-class correlation coefficient [ICC] = 0.87-0.94). No differences were found between the two groups regarding MRI scores of bone marrow oedema, cartilage lesions or bone erosions. Synovial hypertrophy scores differed significantly between groups (P = 0.016). Nonetheless, synovial hypertrophy was also present in 14 JIA patients (35.9 %) with clinically inactive disease. Of JIA patients considered clinically active, 48.6 % showed no signs of MRI-based synovitis. MRI can discriminate between clinically active and inactive JIA patients. However, physical examination is neither very sensitive nor specific in evaluating JIA disease activity compared with MRI. Subclinical synovitis was present in >35 % of presumed clinically inactive patients. (orig.)

  11. A sensitive zinc-activated 129Xe MRI probe

    International Nuclear Information System (INIS)

    Kotera, N.; Delacour, L.; Traore, T.; Buisson, D.A.; Taran, F.; Coudert, S.; Rousseau, B.; Tassali, N.; Leonce, E.; Boutin, C.; Berthault, P.; Brotin, T.; Dutasta, J.P.

    2012-01-01

    Herein we propose the use of hyper-polarized 129 Xe nuclear magnetic resonance (NMR) spectroscopy for the sensitive detection of Zn 2+ ions. To achieve this goal, the noble gas is encapsulated in dedicated host systems bearing a ligand that chelates the Zn 2+ ions. Cryptophanes, aromatic cage molecules made of cyclotriveratrylene groups, are perfectly suited to this purpose as 1) they can easily be rendered water-soluble, 2) the noble gas has a high affinity for their cavity, 3) when xenon is encapsulated, it takes a specific NMR frequency, and 4) xenon exchange in and out of the cavity insures a continuous refreshment of the Xe-cryptophane environment in hyper-polarization. We constructed a powerful 129 Xe NMR-based sensor of Zn 2+ ions, which enables for the first time measurement of Zn 2+ concentrations as low as 100 nm. This high sensitivity was achieved thanks to a smart 129 Xe MRI sensor, where the binding of the ion to the target is accompanied by a change in NMR parameters. We have also demonstrated the importance of working with enantiopure cryptophane derivatives. (O.M.)

  12. Intrinsic network activity in tinnitus investigated using functional MRI

    Science.gov (United States)

    Leaver, Amber M.; Turesky, Ted K.; Seydell-Greenwald, Anna; Morgan, Susan; Kim, Hung J.; Rauschecker, Josef P.

    2016-01-01

    Tinnitus is an increasingly common disorder in which patients experience phantom auditory sensations, usually ringing or buzzing in the ear. Tinnitus pathophysiology has been repeatedly shown to involve both auditory and non-auditory brain structures, making network-level studies of tinnitus critical. In this magnetic resonance imaging (MRI) study, we used two resting-state functional connectivity (RSFC) approaches to better understand functional network disturbances in tinnitus. First, we demonstrated tinnitus-related reductions in RSFC between specific brain regions and resting-state networks (RSNs), defined by independent components analysis (ICA) and chosen for their overlap with structures known to be affected in tinnitus. Then, we restricted ICA to data from tinnitus patients, and identified one RSN not apparent in control data. This tinnitus RSN included auditory-sensory regions like inferior colliculus and medial Heschl’s gyrus, as well as classically non-auditory regions like the mediodorsal nucleus of the thalamus, striatum, lateral prefrontal and orbitofrontal cortex. Notably, patients’ reported tinnitus loudness was positively correlated with RSFC between the mediodorsal nucleus and the tinnitus RSN, indicating that this network may underlie the auditory-sensory experience of tinnitus. These data support the idea that tinnitus involves network dysfunction, and further stress the importance of communication between auditory-sensory and fronto-striatal circuits in tinnitus pathophysiology. PMID:27091485

  13. Value of whole body MRI and dynamic contrast enhanced MRI in the diagnosis, follow-up and evaluation of disease activity and extent in multiple myeloma

    Energy Technology Data Exchange (ETDEWEB)

    Dutoit, Julie C., E-mail: Julie.Dutoit@UGent.be; Vanderkerken, Matthias A., E-mail: Matthias.Vanderkerken@UGent.be; Verstraete, Koenraad L., E-mail: Koenraad.Verstraete@UGent.be

    2013-09-15

    Purpose: To evaluate the significance of dynamic contrast enhanced MRI (DCE-MRI) and whole body MRI (WB-MRI) in the diagnosis, prognosis and assessment of therapy for patients with monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM). Materials and methods: The retrospective study includes 219 patients providing 463 WB-MRI and DCE-MRI investigations for the subgroups MGUS (n = 70), MM active disease (n = 126; this includes 70 patients with new diagnosis of MM, according to the International Staging System (ISS): 41.4% ISS stage I, 20.0% ISS stage II, 7.1% ISS stage III, 31.4% insufficient for staging; and 56 patients with ‘(re-)active disease’: 16.07% relapse, 32.14% progressive disease and 51.79% stable disease) and MM remission (n = 23; 60.87% complete remission, 17.39% very good partial remission and 21.74% partial remission). Investigations of patients with hereditary multiple exostoses (n = 5), neurofibromatosis (n = 7) and healthy persons (n = 9) were added as control subjects (n = 21). WB-MRI evaluation was done by evaluating thirteen skeletal regions, providing a ‘skeletal score’. DCE-MRI images of the spine, were analyzed with regions-of-interest and time-intensity-curves (TIC). Results: All TIC parameters can significantly differentiate between the predefined subgroups (p < 0.001). One hundred days after autologous stem cell transplantation a 75% decrease of the slope wash-in value (p < 0.001) can be seen. A cubic regression trend between ‘skeletal score’ and slope wash-in (adj.R{sup 2} = 0.412) could demonstrate a significant increase bone marrow perfusion if MM affects more than 10 skeletal regions (p < 0.001), associated with a poorer prognosis (p < 0.001). Conclusion: DCE-MRI evaluation of the spine is useful for diagnosis of MM, follow-up after stem cell transplantation and evaluation of disease activity. A combined evaluation with WB-MRI and DCE-MRI provides additional micro-vascular information on the

  14. Magnetic resonance imaging investigation of the bone conduction implant – a pilot study at 1.5 Tesla

    Science.gov (United States)

    Jansson, Karl-Johan Fredén; Håkansson, Bo; Reinfeldt, Sabine; Rigato, Cristina; Eeg-Olofsson, Måns

    2015-01-01

    Purpose The objective of this pilot study was to investigate if an active bone conduction implant (BCI) used in an ongoing clinical study withstands magnetic resonance imaging (MRI) of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO), total harmonic distortion (THD), and demagnetization were investigated. Implant activation and image artifacts were also evaluated. Methods and materials One implant was placed on the head of a test person at the position corresponding to the normal position of an implanted BCI and applied with a static pressure using a bandage and scanned in a 1.5 Tesla MRI camera. Scanning was performed both with and without the implant, in three orthogonal planes, and for one spin-echo and one gradient-echo pulse sequence. Implant functionality was verified in-between the scans using an audio processor programmed to generate a sequence of tones when attached to the implant. Objective verification was also carried out by measuring MPO and THD on a skull simulator as well as retention force, before and after MRI. Results It was found that the exposure of 1.5 Tesla MRI only had a minor effect on the MPO, ie, it decreased over all frequencies with an average of 1.1±2.1 dB. The THD remained unchanged above 300 Hz and was increased only at lower frequencies. The retention magnet was demagnetized by 5%. The maximum image artifacts reached a distance of 9 and 10 cm from the implant in the coronal plane for the spin-echo and the gradient-echo sequence, respectively. The test person reported no MRI induced sound from the implant. Conclusion This pilot study indicates that the present BCI may withstand 1.5 Tesla MRI with only minor effects on its performance. No MRI induced sound was reported, but the head image was highly distorted near the implant. PMID:26604836

  15. Magnetic resonance imaging investigation of the bone conduction implant - a pilot study at 1.5 Tesla.

    Science.gov (United States)

    Jansson, Karl-Johan Fredén; Håkansson, Bo; Reinfeldt, Sabine; Rigato, Cristina; Eeg-Olofsson, Måns

    2015-01-01

    The objective of this pilot study was to investigate if an active bone conduction implant (BCI) used in an ongoing clinical study withstands magnetic resonance imaging (MRI) of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO), total harmonic distortion (THD), and demagnetization were investigated. Implant activation and image artifacts were also evaluated. One implant was placed on the head of a test person at the position corresponding to the normal position of an implanted BCI and applied with a static pressure using a bandage and scanned in a 1.5 Tesla MRI camera. Scanning was performed both with and without the implant, in three orthogonal planes, and for one spin-echo and one gradient-echo pulse sequence. Implant functionality was verified in-between the scans using an audio processor programmed to generate a sequence of tones when attached to the implant. Objective verification was also carried out by measuring MPO and THD on a skull simulator as well as retention force, before and after MRI. It was found that the exposure of 1.5 Tesla MRI only had a minor effect on the MPO, ie, it decreased over all frequencies with an average of 1.1±2.1 dB. The THD remained unchanged above 300 Hz and was increased only at lower frequencies. The retention magnet was demagnetized by 5%. The maximum image artifacts reached a distance of 9 and 10 cm from the implant in the coronal plane for the spin-echo and the gradient-echo sequence, respectively. The test person reported no MRI induced sound from the implant. This pilot study indicates that the present BCI may withstand 1.5 Tesla MRI with only minor effects on its performance. No MRI induced sound was reported, but the head image was highly distorted near the implant.

  16. Defining active sacroiliitis on magnetic resonance imaging (MRI) for classification of axial spondyloarthritis: a consensual approach by the ASAS/OMERACT MRI group

    DEFF Research Database (Denmark)

    Rudwaleit, M; Jurik, A G; Hermann, K-G A

    2009-01-01

    BACKGROUND: Magnetic resonance imaging (MRI) of sacroiliac joints has evolved as the most relevant imaging modality for diagnosis and classification of early axial spondyloarthritis (SpA) including early ankylosing spondylitis. OBJECTIVES: To identify and describe MRI findings in sacroiliitis and...... relevant for sacroiliitis have been defined by consensus by a group of rheumatologists and radiologists. These definitions should help in applying correctly the imaging feature "active sacroiliitis by MRI" in the new ASAS classification criteria for axial SpA.......BACKGROUND: Magnetic resonance imaging (MRI) of sacroiliac joints has evolved as the most relevant imaging modality for diagnosis and classification of early axial spondyloarthritis (SpA) including early ankylosing spondylitis. OBJECTIVES: To identify and describe MRI findings in sacroiliitis...... conditions which may mimic SpA. Descriptions of the pathological findings and technical requirements for the appropriate acquisition were formulated. In a consensual approach MRI findings considered to be essential for sacroiliitis were defined. RESULTS: Active inflammatory lesions such as bone marrow oedema...

  17. The effect of flexible acrylic resin on masticatory muscle activity in implant-supported mandibular overdentures: a controlled clinical trial

    OpenAIRE

    Ibraheem, Eman Mostafa Ahmed; Nassani, Mohammad Zakaria

    2016-01-01

    Background It is not yet clear from the current literature to what extent masticatory muscle activity is affected by the use of flexible acrylic resin in the construction of implant-supported mandibular overdentures. Objective To compare masticatory muscle activity between patients who were provided with implant-supported mandibular overdentures constructed from flexible acrylic resin and those who were provided with implant-supported mandibular overdentures constructed from heat-cured conven...

  18. Concurrent tACS-fMRI Reveals Causal Influence of Power Synchronized Neural Activity on Resting State fMRI Connectivity.

    Science.gov (United States)

    Bächinger, Marc; Zerbi, Valerio; Moisa, Marius; Polania, Rafael; Liu, Quanying; Mantini, Dante; Ruff, Christian; Wenderoth, Nicole

    2017-05-03

    Resting state fMRI (rs-fMRI) is commonly used to study the brain's intrinsic neural coupling, which reveals specific spatiotemporal patterns in the form of resting state networks (RSNs). It has been hypothesized that slow rs-fMRI oscillations (5 Hz); however, causal evidence for this relationship is currently lacking. Here we measured rs-fMRI in humans while applying transcranial alternating current stimulation (tACS) to entrain brain rhythms in left and right sensorimotor cortices. The two driving tACS signals were tailored to the individual's α rhythm (8-12 Hz) and fluctuated in amplitude according to a 1 Hz power envelope. We entrained the left versus right hemisphere in accordance to two different coupling modes where either α oscillations were synchronized between hemispheres (phase-synchronized tACS) or the slower oscillating power envelopes (power-synchronized tACS). Power-synchronized tACS significantly increased rs-fMRI connectivity within the stimulated RSN compared with phase-synchronized or no tACS. This effect outlasted the stimulation period and tended to be more effective in individuals who exhibited a naturally weak interhemispheric coupling. Using this novel approach, our data provide causal evidence that synchronized power fluctuations contribute to the formation of fMRI-based RSNs. Moreover, our findings demonstrate that the brain's intrinsic coupling at rest can be selectively modulated by choosing appropriate tACS signals, which could lead to new interventions for patients with altered rs-fMRI connectivity. SIGNIFICANCE STATEMENT Resting state fMRI (rs-fMRI) has become an important tool to estimate brain connectivity. However, relatively little is known about how slow hemodynamic oscillations measured with fMRI relate to electrophysiological processes. It was suggested that slowly fluctuating power envelopes of electrophysiological signals synchronize across brain areas and that the topography of this activity is spatially correlated to

  19. Laser activation of Ultra Shallow Junctions (USJ) doped by Plasma Immersion Ion Implantation (PIII)

    International Nuclear Information System (INIS)

    Vervisch, Vanessa; Larmande, Yannick; Delaporte, Philippe; Sarnet, Thierry; Sentis, Marc; Etienne, Hasnaa; Torregrosa, Frank; Cristiano, Fuccio; Fazzini, Pier Francesco

    2009-01-01

    Today, the main challenges for the realization of the source/drain extensions concern the ultra-low energy implantation and the activation of the maximum amount of dopants with a minimized diffusion. Among the different annealing processes, one solution is the laser thermal annealing. Many studies [F. Torregrosa, C. Laviron, F. Milesi, M. Hernandez, H. Faik, J. Venturini, Proc. 14th International Conference on Ion Implant Technology, 2004; M. Hernandez, J. Venturini, D. Zahorski, J. Boulmer, D. Debarre, G. Kerrien, T. Sarnet, C. Laviron, M.N Semeria, D. Camel, J.L Santailler, Appl. Surf. Sci. 208-209 (2003) 345-351] have shown that the association of Plasma Immersion Ion Implantation (PIII) and Laser Thermal Process (LTP) allows to obtain junctions of a few nanometers with a high electrical activation. All the wafers studied have been implanted by PULSION (PIII implanter developed by Ion Beam Services) with an acceleration voltage of 1 kV and a dose of 6 x 10 15 at./cm 2 . In this paper, we compare the annealing process achieved with three excimer lasers: ArF, KrF and XeCl with a wavelength of respectively 193, 248 and 308 nm. We analyse the results in terms of boron activation and junction depth. To complete this study, we have observed the effect of pre-amorphization implantation (PAI) before PIII process on boron implantation and boron activation. We show that Ge PAI implanted by classical beam line allows a decrease of the junction depth from 20 down to 12 nm in the as-implanted condition. Transmission Electron Microscopy (TEM) analyses were performed in order to study the structure of pre-amorphized silicon and to estimate the thickness of the amorphous layer. In order to determine the sheet resistance (R s ) and the junction depth (X j ), we have used the four-point probe technique (4PP) and secondary ion mass spectrometry (SIMS) analysis. To complete the electrical characterizations some samples have been analyzed by non-contact optical measurements. All the

  20. Motion or activity: their role in intra- and inter-subject variation in fMRI

    DEFF Research Database (Denmark)

    Lund, Torben E; Nørgaard, Minna D; Rostrup, Egill

    2005-01-01

    MRI to pre-surgical planning because of a higher requirement for intra-subject precision. The purpose of this study was to investigate the impact of residual movement artefacts on intra-subject and inter-subject variability in the observed fMRI activation. Ten subjects were examined using three different...... word-generation tasks. Two of the subjects were examined 10 times on 10 different days using the same paradigms. We systematically investigated one approach of correcting for residual movement effects: the inclusion of regressors describing movement-related effects in the design matrix of a General...

  1. Acute patellofemoral pain: aggravating activities, clinical examination, MRI and ultrasound findings

    DEFF Research Database (Denmark)

    Brushoj, C.; Holmich, P.; Nielsen, M.B.

    2008-01-01

    Objective: To investigate acute anterior knee pain caused by overuse in terms of pain location, aggravating activities, findings on clinical examination and ultrasound/MRI examination. To determine if acute anterior knee pain caused by overuse should be classified as a subgroup of patellofemoral......%)), but other synovial covered structures including the fat pad of Hoffa (12 patients (40%)), the medial plica and the joint line (12 patients (40%)) were also involved. Only eight patients (27%) experienced pain on the patellofemoral compression test. Only discrete changes was detected on MRI...

  2. Effects of hypoglycemia on human brain activation measured with fMRI.

    Science.gov (United States)

    Anderson, Adam W; Heptulla, Rubina A; Driesen, Naomi; Flanagan, Daniel; Goldberg, Philip A; Jones, Timothy W; Rife, Fran; Sarofin, Hedy; Tamborlane, William; Sherwin, Robert; Gore, John C

    2006-07-01

    Functional magnetic resonance imaging (fMRI) was used to measure the effects of acute hypoglycemia caused by passive sensory stimulation on brain activation. Visual stimulation was used to generate blood-oxygen-level-dependent (BOLD) contrast, which was monitored during hyperinsulinemic hypoglycemic and euglycemic clamp studies. Hypoglycemia (50 +/- 1 mg glucose/dl) decreased the fMRI signal relative to euglycemia in 10 healthy human subjects: the fractional signal change was reduced by 28 +/- 12% (P variations in blood glucose levels may modulate BOLD signals in the healthy brain.

  3. Enhanced osteogenic activity of poly ether ether ketone using calcium plasma immersion ion implantation.

    Science.gov (United States)

    Lu, Tao; Qian, Shi; Meng, Fanhao; Ning, Congqin; Liu, Xuanyong

    2016-06-01

    As a promising implantable material, poly ether ether ketone (PEEK) possesses similar elastic modulus to that of cortical bones yet suffers from bio-inertness and poor osteogenic properties, which limits its application as orthopedic implants. In this work, calcium is introduced onto PEEK surface using calcium plasma immersion ion implantation (Ca-PIII). The results obtained from scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) confirm the modified layer with varying contents of calcium are formed on PEEK surfaces. Water contact angle measurements reveal the increasing hydrophobicity of both Ca-PIII treated surfaces. In vitro cell adhesion, viability assay, alkaline phosphatase activity and collagen secretion analyses disclose improved the adhesion, proliferation, and osteo-differentiation of rat bone mesenchymal stem cells (bMSCs) on Ca-PIII treated surfaces. The obtained results indicate that PEEK surface with enhanced osteogenic activity can be produced by calcium incorporation. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Submicron confinement effect on electrical activation of B implanted in Si

    International Nuclear Information System (INIS)

    Bruno, E.; Mirabella, S.; Impellizzeri, G.; Priolo, F.; Giannazzo, F.; Raineri, V.; Napolitani, E.

    2005-01-01

    In this work we studied the effect of B implantation in Si through submicron laterally confined area on B clustering and its electrical activation. For this study, we implanted B 3 keV into a Si wafer grown by Molecular Beam Epitaxy (MBE) through a patterned oxide mask with opening widths down to 0.38 μm. Then, we annealed the sample at 800 deg. C for several times up to 120 min and monitored the 2D carrier profile by quantitative high resolution Scanning Capacitance Microscopy (SCM). We show that by reducing the opening widths, not only the B clustering is strongly reduced, but also the B cluster dissolution is accelerated. This demonstrates the beneficial role of implanted B confinement on the B electrical activation. The above results have a significant impact in the modern Si based electronic device engineering

  5. fMRI activation patterns in an analytic reasoning task: consistency with EEG source localization

    Science.gov (United States)

    Li, Bian; Vasanta, Kalyana C.; O'Boyle, Michael; Baker, Mary C.; Nutter, Brian; Mitra, Sunanda

    2010-03-01

    Functional magnetic resonance imaging (fMRI) is used to model brain activation patterns associated with various perceptual and cognitive processes as reflected by the hemodynamic (BOLD) response. While many sensory and motor tasks are associated with relatively simple activation patterns in localized regions, higher-order cognitive tasks may produce activity in many different brain areas involving complex neural circuitry. We applied a recently proposed probabilistic independent component analysis technique (PICA) to determine the true dimensionality of the fMRI data and used EEG localization to identify the common activated patterns (mapped as Brodmann areas) associated with a complex cognitive task like analytic reasoning. Our preliminary study suggests that a hybrid GLM/PICA analysis may reveal additional regions of activation (beyond simple GLM) that are consistent with electroencephalography (EEG) source localization patterns.

  6. MRI of the Chest

    Medline Plus

    Full Text Available ... has any questions. Some implanted devices require a short period of time after placement (usually six weeks) ... center of the magnet. Some MRI units, called short-bore systems , are designed so that the magnet ...

  7. MRI of the Chest

    Medline Plus

    Full Text Available ... a risk, depending on their nature and the strength of the MRI magnet. Many implanted devices will ... abnormalities where Chest CT is a preferred imaging test. MR imaging can assess blood flow without risking ...

  8. MRI of the Chest

    Medline Plus

    Full Text Available ... it may cause some medical devices to malfunction. Most orthopedic implants pose no risk, but you should ... or if you have asthma. The contrast material most commonly used for an MRI exam contains a ...

  9. MRI of the Chest

    Medline Plus

    Full Text Available ... is not harmful, but it may cause some medical devices to malfunction. Most orthopedic implants pose no ... Chest? Magnetic resonance imaging (MRI) is a noninvasive medical test that physicians use to diagnose medical conditions. ...

  10. MRI of the Breast

    Science.gov (United States)

    ... in evaluating women at high risk for breast cancer. MRI can successfully image the dense breast tissue common in younger women, and it can successfully image breast implants. Both of these are difficult to image using ...

  11. MRI of the Chest

    Medline Plus

    Full Text Available ... contrast for an MRI. If you have a history of kidney disease or liver transplant, it will ... are not limited to: artificial heart valves implanted drug infusion ports artificial limbs or metallic joint prostheses ...

  12. MRI of the Chest

    Medline Plus

    Full Text Available ... their nature and the strength of the MRI magnet. Many implanted devices will have a pamphlet explaining ... large cylinder-shaped tube surrounded by a circular magnet. You will lie on a moveable examination table ...

  13. ICN_Atlas: Automated description and quantification of functional MRI activation patterns in the framework of intrinsic connectivity networks.

    Science.gov (United States)

    Kozák, Lajos R; van Graan, Louis André; Chaudhary, Umair J; Szabó, Ádám György; Lemieux, Louis

    2017-12-01

    Generally, the interpretation of functional MRI (fMRI) activation maps continues to rely on assessing their relationship to anatomical structures, mostly in a qualitative and often subjective way. Recently, the existence of persistent and stable brain networks of functional nature has been revealed; in particular these so-called intrinsic connectivity networks (ICNs) appear to link patterns of resting state and task-related state connectivity. These networks provide an opportunity of functionally-derived description and interpretation of fMRI maps, that may be especially important in cases where the maps are predominantly task-unrelated, such as studies of spontaneous brain activity e.g. in the case of seizure-related fMRI maps in epilepsy patients or sleep states. Here we present a new toolbox (ICN_Atlas) aimed at facilitating the interpretation of fMRI data in the context of ICN. More specifically, the new methodology was designed to describe fMRI maps in function-oriented, objective and quantitative way using a set of 15 metrics conceived to quantify the degree of 'engagement' of ICNs for any given fMRI-derived statistical map of interest. We demonstrate that the proposed framework provides a highly reliable quantification of fMRI activation maps using a publicly available longitudinal (test-retest) resting-state fMRI dataset. The utility of the ICN_Atlas is also illustrated on a parametric task-modulation fMRI dataset, and on a dataset of a patient who had repeated seizures during resting-state fMRI, confirmed on simultaneously recorded EEG. The proposed ICN_Atlas toolbox is freely available for download at http://icnatlas.com and at http://www.nitrc.org for researchers to use in their fMRI investigations. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  14. Intersession reliability of fMRI activation for heat pain and motor tasks

    Science.gov (United States)

    Quiton, Raimi L.; Keaser, Michael L.; Zhuo, Jiachen; Gullapalli, Rao P.; Greenspan, Joel D.

    2014-01-01

    As the practice of conducting longitudinal fMRI studies to assess mechanisms of pain-reducing interventions becomes more common, there is a great need to assess the test–retest reliability of the pain-related BOLD fMRI signal across repeated sessions. This study quantitatively evaluated the reliability of heat pain-related BOLD fMRI brain responses in healthy volunteers across 3 sessions conducted on separate days using two measures: (1) intraclass correlation coefficients (ICC) calculated based on signal amplitude and (2) spatial overlap. The ICC analysis of pain-related BOLD fMRI responses showed fair-to-moderate intersession reliability in brain areas regarded as part of the cortical pain network. Areas with the highest intersession reliability based on the ICC analysis included the anterior midcingulate cortex, anterior insula, and second somatosensory cortex. Areas with the lowest intersession reliability based on the ICC analysis also showed low spatial reliability; these regions included pregenual anterior cingulate cortex, primary somatosensory cortex, and posterior insula. Thus, this study found regional differences in pain-related BOLD fMRI response reliability, which may provide useful information to guide longitudinal pain studies. A simple motor task (finger-thumb opposition) was performed by the same subjects in the same sessions as the painful heat stimuli were delivered. Intersession reliability of fMRI activation in cortical motor areas was comparable to previously published findings for both spatial overlap and ICC measures, providing support for the validity of the analytical approach used to assess intersession reliability of pain-related fMRI activation. A secondary finding of this study is that the use of standard ICC alone as a measure of reliability may not be sufficient, as the underlying variance structure of an fMRI dataset can result in inappropriately high ICC values; a method to eliminate these false positive results was used in this

  15. A reliability study on brain activation during active and passive arm movements supported by an MRI-compatible robot.

    Science.gov (United States)

    Estévez, Natalia; Yu, Ningbo; Brügger, Mike; Villiger, Michael; Hepp-Reymond, Marie-Claude; Riener, Robert; Kollias, Spyros

    2014-11-01

    In neurorehabilitation, longitudinal assessment of arm movement related brain function in patients with motor disability is challenging due to variability in task performance. MRI-compatible robots monitor and control task performance, yielding more reliable evaluation of brain function over time. The main goals of the present study were first to define the brain network activated while performing active and passive elbow movements with an MRI-compatible arm robot (MaRIA) in healthy subjects, and second to test the reproducibility of this activation over time. For the fMRI analysis two models were compared. In model 1 movement onset and duration were included, whereas in model 2 force and range of motion were added to the analysis. Reliability of brain activation was tested with several statistical approaches applied on individual and group activation maps and on summary statistics. The activated network included mainly the primary motor cortex, primary and secondary somatosensory cortex, superior and inferior parietal cortex, medial and lateral premotor regions, and subcortical structures. Reliability analyses revealed robust activation for active movements with both fMRI models and all the statistical methods used. Imposed passive movements also elicited mainly robust brain activation for individual and group activation maps, and reliability was improved by including additional force and range of motion using model 2. These findings demonstrate that the use of robotic devices, such as MaRIA, can be useful to reliably assess arm movement related brain activation in longitudinal studies and may contribute in studies evaluating therapies and brain plasticity following injury in the nervous system.

  16. Dynamic Three-Dimensional Shoulder Mri during Active Motion for Investigation of Rotator Cuff Diseases.

    Directory of Open Access Journals (Sweden)

    Christine Tempelaere

    Full Text Available MRI is the standard methodology in diagnosis of rotator cuff diseases. However, many patients continue to have pain despite treatment, and MRI of a static unloaded shoulder seems insufficient for best diagnosis and treatment. This study evaluated if Dynamic MRI provides novel kinematic data that can be used to improve the understanding, diagnosis and best treatment of rotator cuff diseases.Dynamic MRI provided real-time 3D image series and was used to measure changes in the width of subacromial space, superior-inferior translation and anterior-posterior translation of the humeral head relative to the glenoid during active abduction. These measures were investigated for consistency with the rotator cuff diseases classifications from standard MRI.The study included: 4 shoulders with massive rotator cuff tears, 5 shoulders with an isolated full-thickness supraspinatus tear, 5 shoulders with tendinopathy and 6 normal shoulders. A change in the width of subacromial space greater than 4mm differentiated between rotator cuff diseases with tendon tears (massive cuff tears and supraspinatus tear and without tears (tendinopathy (p = 0.012. The range of the superior-inferior translation was higher in the massive cuff tears group (6.4mm than in normals (3.4mm (p = 0.02. The range of the anterior-posterior translation was higher in the massive cuff tears (9.2 mm and supraspinatus tear (9.3 mm shoulders compared to normals (3.5mm and tendinopathy (4.8mm shoulders (p = 0.05.The Dynamic MRI enabled a novel measure; 'Looseness', i.e. the translation of the humeral head on the glenoid during an abduction cycle. Looseness was better able at differentiating different forms of rotator cuff disease than a simple static measure of relative glenohumeral position.

  17. Study of physiology of visual cortex activated by rotating grating with functional MRI

    International Nuclear Information System (INIS)

    Liang Ping; Shao Qing; Zhang Zhiqiang; Lu Guangming

    2004-01-01

    Objective: To research the physiology of visual cortex activated by rotating grating with functional-MRI (fMRI), and to identify the components of the activation. Methods: Functional MRI was performed in 9 healthy volunteers by using GRE-EPI sequences on a 1.5 T MR scanner. In the block designing, rotating grating, static grating, and luminance were plotted as task states, while static grating, luminance, and darkness were set as control states. The stimuli tasks included six steps. Imaging processing and statistical analysis was carried out off-line using SPM99 in single-subject method. Results: Some respective areas of visual cortex were activated by the various stimuli information supplied by rotating grating. The strong activation in the middle of occipital lobe located at primary vision area was related to the stimuli of white luminance. Its average maximum points were at 13, -98, -2 and 11, -100, -41 The bilateral activations of Brodmann 19th area located at MT area were related to visual motion perception. Its average maximum points were at 46, -72, -2 and -44, -74, 0. The mild activation in the middle of occipital lobe was related to form perception. Its average maximum points were at -12, -98, -6 and -16, -96, -6. Conclusion: The plotting of control state is important in bock design. The effective visual information of rotating grating includes components of luminance, visual motion perception, and form perception. FMRI has potential as a tool for studying the basic physiology of visual cortex. (authors)

  18. The effects of physical activity on functional MRI activation associated with cognitive control in children: a randomized controlled intervention

    Directory of Open Access Journals (Sweden)

    Laura eChaddock-Heyman

    2013-03-01

    Full Text Available This study used functional magnetic resonance imaging (fMRI to examine the influence of a 9-month physical activity program on task-evoked brain activation during childhood. The results demonstrated that 8- to 9-year-old children who participated in 60+ minutes of physical activity, 5 days per week, for 9 months, showed decreases in fMRI brain activation in the right anterior prefrontal cortex coupled with within-group improvements in performance on a task of attentional and interference control. Children assigned to a wait list control group did not show changes in brain function. Furthermore, at post-test, children in the physical activity group showed similar anterior frontal brain patterns and incongruent accuracy rates to a group of college-aged young adults. Children in the wait list control group still differed from the young adults in terms of anterior prefrontal activation and performance at post-test. There were no significant changes in fMRI activation in the anterior cingulate cortex for either group. These results suggest that physical activity during childhood may enhance specific elements of prefrontal cortex function involved in cognitive control.

  19. Hermetic diamond capsules for biomedical implants enabled by gold active braze alloys.

    Science.gov (United States)

    Lichter, Samantha G; Escudié, Mathilde C; Stacey, Alastair D; Ganesan, Kumaravelu; Fox, Kate; Ahnood, Arman; Apollo, Nicholas V; Kua, Dunstan C; Lee, Aaron Z; McGowan, Ceara; Saunders, Alexia L; Burns, Owen; Nayagam, David A X; Williams, Richard A; Garrett, David J; Meffin, Hamish; Prawer, Steven

    2015-01-01

    As the field of biomedical implants matures the functionality of implants is rapidly increasing. In the field of neural prostheses this is particularly apparent as researchers strive to build devices that interact with highly complex neural systems such as vision, hearing, touch and movement. A retinal implant, for example, is a highly complex device and the surgery, training and rehabilitation requirements involved in deploying such devices are extensive. Ideally, such devices will be implanted only once and will continue to function effectively for the lifetime of the patient. The first and most pivotal factor that determines device longevity is the encapsulation that separates the sensitive electronics of the device from the biological environment. This paper describes the realisation of a free standing device encapsulation made from diamond, the most impervious, long lasting and biochemically inert material known. A process of laser micro-machining and brazing is described detailing the fabrication of hermetic electrical feedthroughs and laser weldable seams using a 96.4% gold active braze alloy, another material renowned for biochemical longevity. Accelerated ageing of the braze alloy, feedthroughs and hermetic capsules yielded no evidence of corrosion and no loss of hermeticity. Samples of the gold braze implanted for 15 weeks, in vivo, caused minimal histopathological reaction and results were comparable to those obtained from medical grade silicone controls. The work described represents a first account of a free standing, fully functional hermetic diamond encapsulation for biomedical implants, enabled by gold active alloy brazing and laser micro-machining. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Distribution pattern of MRI abnormalities within the knee and wrist of juvenile idiopathic arthritis patients: signature of disease activity

    NARCIS (Netherlands)

    Nusman, Charlotte M.; Hemke, Robert; Schonenberg, Dieneke; Dolman, Koert M.; van Rossum, Marion A. J.; van den Berg, J. Merlijn; Kuijpers, Taco W.; Maas, Mario

    2014-01-01

    The aim of this study in clinically active juvenile idiopathic arthritis (JIA) was to assess the frequency and distribution pattern of synovitis as hallmark of disease and additional soft-tissue and bony abnormalities on MRI in the knee and wrist as two target joints. MRI datasets of 153 clinically

  1. Glucose Administration Enhances fMRI Brain Activation and Connectivity Related to Episodic Memory Encoding for Neutral and Emotional Stimuli

    Science.gov (United States)

    Parent, Marise B.; Krebs-Kraft, Desiree L.; Ryan, John P.; Wilson, Jennifer S.; Harenski, Carla; Hamann, Stephan

    2011-01-01

    Glucose enhances memory in a variety of species. In humans, glucose administration enhances episodic memory encoding, although little is known regarding the neural mechanisms underlying these effects. Here we examined whether elevating blood glucose would enhance functional MRI (fMRI) activation and connectivity in brain regions associated with…

  2. Motor association cortex activity in Parkinson's disease. A functional MRI study

    International Nuclear Information System (INIS)

    Tada, Yukiko

    1998-01-01

    The purpose of this study was to examine the activation of motor association cortex using functional magnetic resonance imaging (fMRI) in patients with Parkinson's disease (PD) and control subjects during performed hand movements. There were 26 patients with PD (12 patients with Hoehn and Yahr stage I-II, 14 patients with stage III) and 8 control subjects. Functional imaging was performed using a 1.5 tesla MRI system equipped with a single-shot, echo-planar pulse sequence. The significant signal changes were observed within the primary sensorimotor area, the supplementary motor area (SMA), and the parietal association area in both PD and control subjects. In PD subjects, the SMA was less activated than in control subjects; there were significant differences in the number of pixels activated in SMA between control and Yahr III group (p<0.01), and between Yahr I-II and Yahr III group (p<0.01). Our results demonstrated that movement related cerebral activity in the SMA is reduced in PD subjects, consistent with previously published data using other methods. It is well known from anatomical studies that one of the major cortical outputs of the basal ganglia is the SMA. This may explain the hypoactivation of the SMA in PD. Studies using fMRI provide a promising method not only for localizing cortical activation related to voluntary movements but also for investigating pathophysiology of movement disorders. (author)

  3. Incremental Activation Detection for Real-Time fMRI Series Using Robust Kalman Filter

    Directory of Open Access Journals (Sweden)

    Liang Li

    2014-01-01

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

  4. Brain Activities Associated with Graphic Emoticons: An fMRI Study

    Science.gov (United States)

    Yuasa, Masahide; Saito, Keiichi; Mukawa, Naoki

    In this paper, we describe the brain activities that are associated with graphic emoticons by using functional MRI (fMRI). We use various types of faces from abstract to photorealistic in computer network applications. A graphics emoticon is an abstract face in communication over computer network. In this research, we created various graphic emoticons for the fMRI study and the graphic emoticons were classified according to friendliness and level of arousal. We investigated the brain activities of participants who were required to evaluate the emotional valence of the graphic emoticons (happy or sad). The experimental results showed that not only the right inferior frontal gyrus and the cingulate gyrus, but also the inferior and middle temporal gyrus and the fusiform gyrus, were found to be activated during the experiment. Forthermore, it is possible that the activation of the right inferior frontal gyrus and the cingulate gyrus is related to the type of abstract face. Since the inferior and middle temporal gyrus were activated, even though the graphic emoticons are static, we may perceive graphic emoticons as dynamic and living agents. Moreover, it is believed that text and graphics emoticons play an important role in enriching communication among users.

  5. A Biodistribution and Toxicity Study of Cobalt Dichloride-N-Acetyl Cysteine in an Implantable MRI Marker for Prostate Cancer Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Frank, Steven J., E-mail: sjfrank@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Texas (United States); Johansen, Mary J. [Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Texas (United States); Martirosyan, Karen S. [Department of Physics and Astronomy, The University of Texas at Brownsville, Texas (United States); Gagea, Mihai; Van Pelt, Carolyn S.; Borne, Agatha [Department of Veterinary Medicine, Surgery, and Pathology, The University of Texas MD Anderson Cancer Center, Texas (United States); Carmazzi, Yudith; Madden, Timothy [Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Texas (United States)

    2013-03-15

    Purpose: C4, a cobalt dichloride-N-acetyl cysteine complex, is being developed as a positive-signal magnetic resonance imaging (MRI) marker to localize implanted radioactive seeds in prostate brachytherapy. We evaluated the toxicity and biodistribution of C4 in rats with the goal of simulating the systemic effects of potential leakage from C4 MRI markers within the prostate. Methods and Materials: 9-μL doses (equivalent to leakage from 120 markers in a human) of control solution (0.9% sodium chloride), 1% (proposed for clinical use), and 10% C4 solution were injected into the prostates of male Sprague-Dawley rats via laparotomy. Organ toxicity and cobalt disposition in plasma, tissues, feces, and urine were evaluated. Results: No C4-related morbidity or mortality was observed in the biodistribution arm (60 rats). Biodistribution was measurable after 10% C4 injection: cobalt was cleared rapidly from periprostatic tissue; mean concentrations in prostate were 163 μg/g and 268 μg/g at 5 and 30 minutes but were undetectable by 60 minutes. Expected dual renal-hepatic elimination was observed, with percentages of injected dose recovered in tissues of 39.0 ± 5.6% (liver), >11.8 ± 6.5% (prostate), and >5.3 ± 0.9% (kidney), with low plasma concentrations detected up to 1 hour (1.40 μg/mL at 5-60 minutes). Excretion in urine was 13.1 ± 4.6%, with 3.1 ± 0.54% recovered in feces by 24 hours. In the toxicity arm, 3 animals died in the control group and 1 each in the 1% and 10% groups from surgical or anesthesia-related complications; all others survived to scheduled termination at 14 days. No C4-related adverse clinical signs or organ toxicity were observed. Conclusion: C4-related toxicity was not observed at exposures at least 10-fold the exposure proposed for use in humans. These data demonstrating lack of systemic toxicity with dual routes of elimination in the event of in situ rupture suggest that C4 warrants further investigation as an MRI marker for prostate

  6. Evaluation of feasibility of 1.5 Tesla prostate MRI using body coil RF transmit in a patient with an implanted vagus nerve stimulator.

    Science.gov (United States)

    Favazza, Christopher P; Edmonson, Heidi A; Ma, Chi; Shu, Yunhong; Felmlee, Joel P; Watson, Robert E; Gorny, Krzysztof R

    2017-11-01

    To assess risks of RF-heating of a vagus nerve stimulator (VNS) during 1.5 T prostate MRI using body coil transmit and to compare these risks with those associated with MRI head exams using a transmit/receive head coil. Spatial distributions of radio-frequency (RF) B1 fields generated by transmit/receive (T/R) body and head coils were empirically assessed along the long axis of a 1.5 T MRI scanner bore. Measurements were obtained along the center axis of the scanner and laterally offset by 15 cm (body coil) and 7 cm (head coil). RF-field measurements were supplemented with direct measurements of RF-heating of 15 cm long copper wires affixed to and submerged in the "neck" region of the gelled saline-filled (sodium chloride and polyacrylic acid) "head-and-torso" phantom. Temperature elevations at the lead tips were measured using fiber-optic thermometers with the phantom positioned at systematically increased distances from the scanner isocenter. B1 field measurements demonstrated greater than 10 dB reduction in RF power at distances beyond 28 cm and 24 cm from isocenter for body and head coil, respectively. Moreover, RF power from body coil transmit at distances greater than 32 cm from isocenter was found to be lower than from the RF power from head coil transmit measured at locations adjacent to the coil array at its opening. Correspondingly, maximum temperature elevations at the tips of the copper wires decreased with increasing distance from isocenter - from 7.4°C at 0 cm to no appreciable heating at locations beyond 40 cm. For the particular scanner model evaluated in this study, positioning an implanted VNS farther than 32 cm from isocenter (configuration achievable for prostate exams) can reduce risks of RF-heating resulting from the body coil transmit to those associated with using a T/R head coil. © 2017 American Association of Physicists in Medicine.

  7. Neurofeedback fMRI-mediated learning and consolidation of regional brain activation during motor imagery

    Science.gov (United States)

    Yoo, Seung-Schik; Lee, Jong-Hwan; O’Leary, Heather; Panych, Lawrence P.; Jolesz, Ferenc A.

    2009-01-01

    We report the long-term effect of real-time functional MRI (rtfMRI) training on voluntary regulation of the level of activation from a hand motor area. During the performance of a motor imagery task of a right hand, blood-oxygenation-level-dependent (BOLD) signal originating from a primary motor area was presented back to the subject in real-time. Demographically matched individuals also received the same procedure without valid feedback information. Followed by the initial rtfMRI sessions, both groups underwent two-week long, daily-practice of the task. Off-line data analysis revealed that the individuals in the experimental group were able to increase the level of BOLD signal from the regulatory target to a greater degree compared to the control group. Furthermore, the learned level of activation was maintained after the two-week period, with the recruitment of additional neural circuitries such as the hippocampus and the limbo-thalamo-cortical pathway. The activation obtained from the control group, in the absence of proper feedback, was indifferent across the training conditions. The level of BOLD activity from the target regulatory region was positively correlated with a self evaluative score within the experimental group, while the majority of control subjects had difficulty adopting a strategy to attain the desired level of functional regulation. Our results suggest that rtfMRI helped individuals learn how to increase region-specific cortical activity associated with a motor imagery task, and the level of increased activation in motor areas was consolidated after the two-week self-practice period, with the involvement of neural circuitries implicated in motor skill learning. PMID:19526048

  8. MRI of the Chest

    Medline Plus

    Full Text Available ... metallic items, which can distort MRI images removable dental work pens, pocket knives and eyeglasses body piercings In most cases, an MRI exam is safe for patients with metal implants, except for a few types. People with the ...

  9. Material-Dependent Implant Artifact Reduction Using SEMAC-VAT and MAVRIC: A Prospective MRI Phantom Study.

    Science.gov (United States)

    Filli, Lukas; Jud, Lukas; Luechinger, Roger; Nanz, Daniel; Andreisek, Gustav; Runge, Val M; Kozerke, Sebastian; Farshad-Amacker, Nadja A

    2017-06-01

    The aim of this study was to compare the degree of artifact reduction in magnetic resonance imaging achieved with slice encoding for metal artifact correction (SEMAC) in combination with view angle tilting (VAT) and multiacquisition variable resonance image combination (MAVRIC) for standard contrast weightings and different metallic materials. Four identically shaped rods made of the most commonly used prosthetic materials (stainless steel, SS; titanium, Ti; cobalt-chromium-molybdenum, CoCr; and oxidized zirconium, oxZi) were scanned at 3 T. In addition to conventional fast spin-echo sequences, metal artifact reduction sequences (SEMAC-VAT and MAVRIC) with varying degrees of artifact suppression were applied at different contrast weightings (T1w, T2w, PDw). Two independent readers measured in-plane and through-plane artifacts in a standardized manner. In addition, theoretical frequency-offset and frequency-offset-gradient maps were calculated. Interobserver agreement was assessed using intraclass correlation coefficient. Interobserver agreement was almost perfect (intraclass correlation coefficient, 0.86-0.99). Stainless steel caused the greatest artifacts, followed by CoCr, Ti, and oxZi regardless of the imaging sequence. While for Ti and oxZi rods scanning with weak SEMAC-VAT showed some advantage, for SS and CoCr, higher modes of SEMAC-VAT or MAVRIC were necessary to achieve artifact reduction. MAVRIC achieved better artifact reduction than SEMAC-VAT at the cost of longer acquisition times. Simulations matched well with the apparent geometry of the frequency-offset maps. For Ti and oxZi implants, weak SEMAC-VAT may be preferred as it is faster and produces less artifact than conventional fast spin-echo. Medium or strong SEMAC-VAT or MAVRIC modes are necessary for significant artifact reduction for SS and CoCr implants.

  10. Enhanced electrical activation of Zn and Be implants in GaAs by the co-implantation of phosphorus

    International Nuclear Information System (INIS)

    Tang, A.C.T.; Sealy, B.J.; Rezazadeh, A.A.

    1989-01-01

    In this paper, we report that, through the use of rapid thermal annealing (RTA) and the co-implantation of phosphorus, an effective way of preventing the in- and out-diffusion of zinc and beryllium has been achieved in GaAs. This is of particular significance in the case of the beryllium implanted samples because, to date, there has been no method for preventing the out-diffusion of beryllium atoms at high annealing temperatures. We have observed that the reverse annealing behaviour of the Be-implanted samples has been modified after the co-implantation of phosphorus. Furthermore, abrupt electrical profiles with hole concentrations of the order of 6x10 19 cm -3 have been achieved with the Zn+P implants after annealing at 850 0 C for 30 s. (author)

  11. Limited role of gadolinium to detect active sacroiliitis on MRI in juvenile spondyloarthritis

    Energy Technology Data Exchange (ETDEWEB)

    Herregods, N.; Leus, A.; Verstraete, K.; Jans, L. [Ghent University Hospital, Department of Radiology and Medical Imaging, Ghent (Belgium); Jaremko, J.L. [University of Alberta Hospital, Department of Radiology and Diagnostic Imaging, Edmonton, AB (Canada); Baraliakos, X. [Ruhr-University Bochum, Rheumazentrum Ruhrgebiet, Herne (Germany); Dehoorne, J. [Ghent University Hospital, Department of Pediatric Rheumatology, Ghent (Belgium)

    2015-11-15

    The aim of this study is to determine the added diagnostic value of contrast-enhanced (CE) magnetic resonance imaging (MRI) compared to routine non contrast-enhanced MRI to detect active sacroiliitis in clinically juvenile spondyloarthritis (JSpA). A total of 80 children clinically suspected for sacroiliitis prospectively underwent MRI of the sacroiliac (SI) joints. Axial and coronal T1-weighted (T1), Short-tau inversion recovery (STIR) and fat-saturated T1-weighted gadolinium-DTPA (Gd) contrast-enhanced (T1/Gd) sequences were obtained. The presence of bone marrow edema (BME), capsulitis, enthesitis, high intra-articular STIR signal, synovial enhancement and a global diagnostic impression of the MRI for diagnosis of sacroiliitis was recorded. STIR and T1/Gd sequences had 100 % agreement for depiction of BME, capsulitis and enthesitis. High intra-articular STIR signal was seen in 18/80 (22.5 %) patients, 15 (83 %) of whom also showed synovial enhancement in the T1/Gd sequence. Sensitivity (SN) and specificity (SP) for a clinical diagnosis of JSpA were similar for high STIR signal (SN = 33 %, SP = 85 %) and T1/Gd synovial enhancement (SN = 36 %, SP = 92 %). Positive likelihood ratio (LR+) for JSpA was twice as high for synovial enhancement than high STIR signal (4.5 compared to 2.2). Global diagnostic impression was similar (STIR: SN = 55 %, SP = 87 %, LR + =4.2; T1/Gd: SN = 55 %, SP = 92 %, LR + = 6.9). MRI without contrast administration is sufficient to identify bone marrow edema, capsulitis and retroarticular enthesitis as features of active sacroiliitis in juvenile spondyloarthritis. In selected cases when high STIR signal in the joint is the only finding, gadolinium-enhanced images may help to confirm the presence of synovitis. (orig.)

  12. Localized Fluctuant Oscillatory Activity by Working Memory Load: A Simultaneous EEG-fMRI Study

    Directory of Open Access Journals (Sweden)

    Xiaojie Zhao

    2017-10-01

    Full Text Available Working memory (WM is a resource-limited memory system for temporary storage and processing of brain information during the execution of cognitive tasks. Increased WM load will increase the amount and difficulty of memory information. Several studies have used electroencephalography (EEG or functional magnetic resonance imaging (fMRI to explore load-dependent cognition processing according to the time courses of electrophysiological activity or the spatial pattern of blood oxygen metabolic activity. However, the relationships between these two activities and the underlying neural mechanism are still unclear. In this study, using simultaneously collected EEG and fMRI data under an n-back verbal WM task, we modeled the spectral perturbation of EEG oscillation and fMRI activation through joint independent component analysis (JICA. Multi-channel oscillation features were also introduced into the JICA model for further analysis. The results showed that time-locked activity of theta and beta were modulated by memory load in the early stimuli evaluation stage, corresponding to the enhanced activation in the frontal and parietal lobe, which were involved in stimulus discrimination, information encoding and delay-period activity. In the late response selection stage, alpha and gamma activity changes dependent on the load correspond to enhanced activation in the areas of frontal, temporal and parietal lobes, which played important roles in attention, information extraction and memory retention. These findings suggest that the increases in memory load not only affect the intensity and time course of the EEG activities, but also lead to the enhanced activation of brain regions which plays different roles during different time periods of cognitive process of WM.

  13. Localized Fluctuant Oscillatory Activity by Working Memory Load: A Simultaneous EEG-fMRI Study.

    Science.gov (United States)

    Zhao, Xiaojie; Li, Xiaoyun; Yao, Li

    2017-01-01

    Working memory (WM) is a resource-limited memory system for temporary storage and processing of brain information during the execution of cognitive tasks. Increased WM load will increase the amount and difficulty of memory information. Several studies have used electroencephalography (EEG) or functional magnetic resonance imaging (fMRI) to explore load-dependent cognition processing according to the time courses of electrophysiological activity or the spatial pattern of blood oxygen metabolic activity. However, the relationships between these two activities and the underlying neural mechanism are still unclear. In this study, using simultaneously collected EEG and fMRI data under an n-back verbal WM task, we modeled the spectral perturbation of EEG oscillation and fMRI activation through joint independent component analysis (JICA). Multi-channel oscillation features were also introduced into the JICA model for further analysis. The results showed that time-locked activity of theta and beta were modulated by memory load in the early stimuli evaluation stage, corresponding to the enhanced activation in the frontal and parietal lobe, which were involved in stimulus discrimination, information encoding and delay-period activity. In the late response selection stage, alpha and gamma activity changes dependent on the load correspond to enhanced activation in the areas of frontal, temporal and parietal lobes, which played important roles in attention, information extraction and memory retention. These findings suggest that the increases in memory load not only affect the intensity and time course of the EEG activities, but also lead to the enhanced activation of brain regions which plays different roles during different time periods of cognitive process of WM.

  14. Identification by functional MRI of human cerebral region activated by taste stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Kakimoto, Naoya [Osaka Univ. (Japan). Faculty of Dentistry

    2000-09-01

    The purpose of this study was the examination of possible imaging of the primary taste region of human cerebral cortex by functional MRI (fMRI). Subjects were 19-36 years old, healthy adult male and female volunteers given information concerning the purpose, significance and method of the study. MRI equipment was 1.5 T Signa Horizon (GE) with Head Coil. Images were processed by the software FuncTool on the Advantage Windows Workstation (GE). Taste stimulation was done by swab bearing the solution of 4% quinine hydrochloride, 20% sodium chloride or distilled water (control) or by dripping from the syringe of the solutions, 8% tartaric acid or 80% sugar. Preliminary examinations with the swab suggested the possibility of the identification. Further, with use of dripping apparatus, the taste active region was shown to be identified by fMRI and of which area tended to be larger in male than in female: a significant difference was seen for the quinine hydrochloride. As above, the method was suggested to be a diagnostic mean for the taste perception. (K.H.)

  15. Identification by functional MRI of human cerebral region activated by taste stimulation

    International Nuclear Information System (INIS)

    Kakimoto, Naoya

    2000-01-01

    The purpose of this study was the examination of possible imaging of the primary taste region of human cerebral cortex by functional MRI (fMRI). Subjects were 19-36 years old, healthy adult male and female volunteers given information concerning the purpose, significance and method of the study. MRI equipment was 1.5 T Signa Horizon (GE) with Head Coil. Images were processed by the software FuncTool on the Advantage Windows Workstation (GE). Taste stimulation was done by swab bearing the solution of 4% quinine hydrochloride, 20% sodium chloride or distilled water (control) or by dripping from the syringe of the solutions, 8% tartaric acid or 80% sugar. Preliminary examinations with the swab suggested the possibility of the identification. Further, with use of dripping apparatus, the taste active region was shown to be identified by fMRI and of which area tended to be larger in male than in female: a significant difference was seen for the quinine hydrochloride. As above, the method was suggested to be a diagnostic mean for the taste perception. (K.H.)

  16. Low-frequency hippocampal-cortical activity drives brain-wide resting-state functional MRI connectivity.

    Science.gov (United States)

    Chan, Russell W; Leong, Alex T L; Ho, Leon C; Gao, Patrick P; Wong, Eddie C; Dong, Celia M; Wang, Xunda; He, Jufang; Chan, Ying-Shing; Lim, Lee Wei; Wu, Ed X

    2017-08-15

    The hippocampus, including the dorsal dentate gyrus (dDG), and cortex engage in bidirectional communication. We propose that low-frequency activity in hippocampal-cortical pathways contributes to brain-wide resting-state connectivity to integrate sensory information. Using optogenetic stimulation and brain-wide fMRI and resting-state fMRI (rsfMRI), we determined the large-scale effects of spatiotemporal-specific downstream propagation of hippocampal activity. Low-frequency (1 Hz), but not high-frequency (40 Hz), stimulation of dDG excitatory neurons evoked robust cortical and subcortical brain-wide fMRI responses. More importantly, it enhanced interhemispheric rsfMRI connectivity in various cortices and hippocampus. Subsequent local field potential recordings revealed an increase in slow oscillations in dorsal hippocampus and visual cortex, interhemispheric visual cortical connectivity, and hippocampal-cortical connectivity. Meanwhile, pharmacological inactivation of dDG neurons decreased interhemispheric rsfMRI connectivity. Functionally, visually evoked fMRI responses in visual regions also increased during and after low-frequency dDG stimulation. Together, our results indicate that low-frequency activity robustly propagates in the dorsal hippocampal-cortical pathway, drives interhemispheric cortical rsfMRI connectivity, and mediates visual processing.

  17. An analysis of intraoperative versus post-operative dosimetry with CT, CT-MRI fusion and XMR for the evaluation of permanent prostate brachytherapy implants

    International Nuclear Information System (INIS)

    Acher, Peter; Puttagunta, Srikanth; Rhode, Kawal; Morris, Stephen; Kinsella, Janette; Gaya, Andrew; Dasgupta, Prokar; Deehan, Charles; Beaney, Ronald; Popert, Rick; Keevil, Stephen

    2010-01-01

    Background and purpose: To assess the agreement between intraoperative and post-operative dosimetry and to identify factors that influence dose calculations of prostate brachytherapy implants. Materials and methods: Patients treated with prostate brachytherapy implants underwent post-operative CT and XMR (combined X-ray and MR) imaging. Dose-volume histograms were calculated from CT, XMR and CT-MR fusion data and compared with intraoperative values for two observers. Multiple linear regression models assessed the influences of intraoperative D90, gland oedema, gland volume, source loss and migration, and implanted activity/volume prostate on post-operative D90. Results: Forty-nine patients were studied. The mean D90 differences (95% confidence limits) between intraoperative and post-operative CT, XMR and CT-MR fusion assessments were: 11 Gy (-22, 45), 18 Gy (-13, 49) and 20 Gy (-17, 58) for Observer 1; and 15 Gy (-34, 63), 13 Gy (-29, 55) and 14 Gy (-27, 54) for Observer 2. Multiple linear regression modelling showed that the observed oedema and intraoperative D90 were significant independent variables for the prediction of post-operative D90 values for both observers using all modalities. Conclusion: This is the first study to report Bland-Altman agreement analysis between intraoperative and post-operative dosimetry. Agreement is poor. Post-operative dosimetry is dependent on the intraoperative D90 and the subjectively outlined gland volume.

  18. Correlations between histology and neuronal activity recorded by microelectrodes implanted chronically in the cerebral cortex

    Science.gov (United States)

    McCreery, Douglas; Cogan, Stuart; Kane, Sheryl; Pikov, Victor

    2016-06-01

    Objective. To quantify relations between the neuronal activity recorded with chronically-implanted intracortical microelectrodes and the histology of the surrounding tissue, using radial distance from the tip sites and time after array implantation as parameters. Approach. ‘Utah’-type intracortical microelectrode arrays were implanted into cats’ sensorimotor cortex for 275-364 days. The brain tissue around the implants was immuno-stained for the neuronal marker NeuN and for the astrocyte marker GFAP. Pearson’s product-moment correlations were used to quantify the relations between these markers and the amplitudes of the recorded neuronal action potentials (APs) and their signal-to-noise ratios (S/N). Main results. S/N was more stable over post-implant time than was AP amplitude, but its increased correlation with neuronal density after many months indicates ongoing loss of neurons around the microelectrodes. S/N was correlated with neuron density out to at least 140 μm from the microelectrodes, while AP amplitude was correlated with neuron density and GFAP density within ˜80 μm. Correlations between AP amplitude and histology markers (GFAP and NeuN density) were strongest immediately after implantation, while correlation between the neuron density and S/N was strongest near the time the animals were sacrificed. Unlike AP amplitude, there was no significant correlation between S/N and density of GFAP around the tip sites. Significance. Our findings indicate an evolving interaction between changes in the tissue surrounding the microelectrodes and the microelectrode’s electrical properties. Ongoing loss of neurons around recording microelectrodes, and the interactions between their delayed electrical deterioration and early tissue scarring around the tips appear to pose the greatest threats to the microelectrodes’ long-term functionality.

  19. Evolution of impedance field telemetry after one day of activation in cochlear implant recipients.

    Directory of Open Access Journals (Sweden)

    Hao-Chun Hu

    Full Text Available Changes in impedance between 24 hours and one month after cochlear implantation have never been explored due to the inability to switch on within one day. This study examined the effect of early activation (within 24 hours on the evolution of electrode impedance with the aim of providing information on the tissue-to-electrode interface when electrical stimulation was commenced one day post implantation.We performed a retrospective review at a single institution. Patients who received a Nucleus 24RECA implant system (Cochlear, Sydney, Australia and underwent initial switch-on within 24 hours postoperatively were included. Impedance measurements were obtained intraoperatively and postoperatively at 1 day, 1 week, 4 weeks, and 8 weeks.A significant drop in impedance was noted 1 day after an initial activation within 24 hours followed by a significant rise in impedance in all channels until 1 week, after which the impedance behaved differently in different segments. Basal and mid-portion electrodes revealed a slight increase while apical electrodes showed a slight decrease in impedance from 1 week to 8 weeks postoperatively. Impedance was relatively stable 4 weeks after surgery.This is the first study to report the evolution of impedance in all channels between initial mapping 1 day and 1 month after cochlear implantation. The underlying mechanism for the differences in behavior between different segments of the electrode may be associated with the combined effect of dynamics among the interplay of cell cover formation, electrical stimulation, and fibrotic reaction.

  20. Active implantable medical device EMI assessment for wireless power transfer operating in LF and HF bands.

    Science.gov (United States)

    Hikage, Takashi; Nojima, Toshio; Fujimoto, Hiroshi

    2016-06-21

    The electromagnetic interference (EMI) imposed on active implantable medical devices by wireless power transfer systems (WPTSs) is discussed based upon results of in vitro experiments. The purpose of this study is to present comprehensive EMI test results gathered from implantable-cardiac pacemakers and implantable cardioverter defibrillators exposed to the electromagnetic field generated by several WPTSs operating in low-frequency (70 kHz-460 kHz) and high-frequency (6.78 MHz) bands. The constructed in vitro experimental test system based upon an Irnich's flat torso phantom was applied. EMI test experiments are conducted on 14 types of WPTSs including Qi-compliant system and EV-charging WPT system mounted on current production EVs. In addition, a numerical simulation model for active implantable medical device (AIMD) EMI estimation based on the experimental test system is newly proposed. The experimental results demonstrate the risk of WPTSs emitting intermittent signal to affect the correct behavior of AIMDs when operating at very short distances. The proposed numerical simulation model is applicable to obtain basically the EMI characteristics of various types of WPTSs.

  1. Clinical application of fMRI: Activation of the motor cortex in an LIS patient

    International Nuclear Information System (INIS)

    Mao, H.; Popp, C.A.; Song, A.W.; Kennedy, P.R.

    1999-01-01

    Patients suffering from the Locked-in Syndrome are completely paralyzed over their entire body, while their brain retains full consciousness. Functional magnetic resonance imaging (fMRI) is a method applied to identify those areas of the brain where activities of neurons indicate motor performance, and which might be electronically stimulated and used for controlling electronic aids expressing intended movements of the patient. (orig./CB) [de

  2. Dopant redistribution and electrical activation in silicon following ultra-low energy boron implantation and excimer laser annealing

    International Nuclear Information System (INIS)

    Whelan, S.; La Magna, A.; Privitera, V.; Mannino, G.; Italia, M.; Bongiorno, C.; Fortunato, G.; Mariucci, L.

    2003-01-01

    Excimer laser annealing (ELA) of ultra-low-energy (ULE) B-ion implanted Si has been performed. High-resolution transmission electron microscopy has been used to assess the as-implanted damage and the crystal recovery following ELA. The electrical activation and redistribution of B in Si during ELA has been investigated as a function of the laser energy density (melted depth), the implant dose, and the number of laser pulses (melt time). The activated and retained dose has been evaluated with spreading resistance profiling and secondary ion mass spectrometry. A significant amount of the implanted dopant was lost from the sample during ELA. However, the dopant that was retained in crystal material was fully activated following rapid resolidification. At an atomic concentration below the thermodynamic limit, the activation efficiency (dose activated/dose implanted into Si material) was a constant for a fixed melt depth, irrespective of the dose implanted and hence the total activated dose was raised as the implant dose was increased. The electrical activation was increased for high laser energy density annealing when the dopant was redistributed over a deeper range

  3. The role of physiological active substances implant adaptation to stress

    International Nuclear Information System (INIS)

    Voronina, L.; Morachevskaya, E.

    2009-01-01

    It is known, that brassinosteroids are capable in small quantities (10 - 12-10 - 7M) to optimize physiology-biochemical processes in plants in stressful conditions. the aim of this study was to investigate the role of anti stress and protective properties of phyto hormone 24-epibrassinolide (24-epiBS). in view of its functional features and biological activity. (Author)

  4. Brain Activity Unique to Orgasm in Women: An fMRI Analysis.

    Science.gov (United States)

    Wise, Nan J; Frangos, Eleni; Komisaruk, Barry R

    2017-11-01

    Although the literature on imaging of regional brain activity during sexual arousal in women and men is extensive and largely consistent, that on orgasm is relatively limited and variable, owing in part to the methodologic challenges posed by variability in latency to orgasm in participants and head movement. To compare brain activity at orgasm (self- and partner-induced) with that at the onset of genital stimulation, immediately before the onset of orgasm, and immediately after the cessation of orgasm and to upgrade the methodology for obtaining and analyzing functional magnetic resonance imaging (fMRI) findings. Using fMRI, we sampled equivalent time points across female participants' variable durations of stimulation and orgasm in response to self- and partner-induced clitoral stimulation. The first 20-second epoch of orgasm was contrasted with the 20-second epochs at the beginning of stimulation and immediately before and after orgasm. Separate analyses were conducted for whole-brain and brainstem regions of interest. For a finer-grained analysis of the peri-orgasm phase, we conducted a time-course analysis on regions of interest. Head movement was minimized to a mean less than 1.3 mm using a custom-fitted thermoplastic whole-head and neck brace stabilizer. Ten women experienced orgasm elicited by self- and partner-induced genital stimulation in a Siemens 3-T Trio fMRI scanner. Brain activity gradually increased leading up to orgasm, peaked at orgasm, and then decreased. We found no evidence of deactivation of brain regions leading up to or during orgasm. The activated brain regions included sensory, motor, reward, frontal cortical, and brainstem regions (eg, nucleus accumbens, insula, anterior cingulate cortex, orbitofrontal cortex, operculum, right angular gyrus, paracentral lobule, cerebellum, hippocampus, amygdala, hypothalamus, ventral tegmental area, and dorsal raphe). Insight gained from the present findings could provide guidance toward a rational basis

  5. Assessment of muscle function using hybrid PET/MRI: comparison of 18F-FDG PET and T2-weighted MRI for quantifying muscle activation in human subjects

    International Nuclear Information System (INIS)

    Haddock, Bryan; Holm, Soeren; Poulsen, Jakup M.; Enevoldsen, Lotte H.; Larsson, Henrik B.W.; Kjaer, Andreas; Suetta, Charlotte

    2017-01-01

    The aim of this study was to determine the relationship between relative glucose uptake and MRI T 2 changes in skeletal muscles following resistance exercise using simultaneous PET/MRI scans. Ten young healthy recreationally active men (age 21 - 28 years) were injected with 18 F-FDG while activating the quadriceps of one leg with repeated knee extension exercises followed by hand-grip exercises for one arm. Immediately following the exercises, the subjects were scanned simultaneously with 18 F-FDG PET/MRI and muscle groups were evaluated for increases in 18 F-FDG uptake and MRI T 2 values. A significant linear correlation between 18 F-FDG uptake and changes in muscle T 2 (R 2 = 0.71) was found. for both small and large muscles and in voxel to voxel comparisons. Despite large intersubject differences in muscle recruitment, the linear correlation between 18 F-FDG uptake and changes in muscle T 2 did not vary among subjects. This is the first assessment of skeletal muscle activation using hybrid PET/MRI and the first study to demonstrate a high correlation between 18 F-FDG uptake and changes in muscle T 2 with physical exercise. Accordingly, it seems that changes in muscle T 2 may be used as a surrogate marker for glucose uptake and lead to an improved insight into the metabolic changes that occur with muscle activation. Such knowledge may lead to improved treatment strategies in patients with neuromuscular pathologies such as stroke, spinal cord injuries and muscular dystrophies. (orig.)

  6. A scalable multi-resolution spatio-temporal model for brain activation and connectivity in fMRI data

    KAUST Repository

    Castruccio, Stefano; Ombao, Hernando; Genton, Marc G.

    2018-01-01

    Functional Magnetic Resonance Imaging (fMRI) is a primary modality for studying brain activity. Modeling spatial dependence of imaging data at different spatial scales is one of the main challenges of contemporary neuroimaging, and it could allow

  7. Mapping brain activity in gradient-echo functional MRI using principal component analysis

    Science.gov (United States)

    Khosla, Deepak; Singh, Manbir; Don, Manuel

    1997-05-01

    The detection of sites of brain activation in functional MRI has been a topic of immense research interest and many technique shave been proposed to this end. Recently, principal component analysis (PCA) has been applied to extract the activated regions and their time course of activation. This method is based on the assumption that the activation is orthogonal to other signal variations such as brain motion, physiological oscillations and other uncorrelated noises. A distinct advantage of this method is that it does not require any knowledge of the time course of the true stimulus paradigm. This technique is well suited to EPI image sequences where the sampling rate is high enough to capture the effects of physiological oscillations. In this work, we propose and apply tow methods that are based on PCA to conventional gradient-echo images and investigate their usefulness as tools to extract reliable information on brain activation. The first method is a conventional technique where a single image sequence with alternating on and off stages is subject to a principal component analysis. The second method is a PCA-based approach called the common spatial factor analysis technique (CSF). As the name suggests, this method relies on common spatial factors between the above fMRI image sequence and a background fMRI. We have applied these methods to identify active brain ares during visual stimulation and motor tasks. The results from these methods are compared to those obtained by using the standard cross-correlation technique. We found good agreement in the areas identified as active across all three techniques. The results suggest that PCA and CSF methods have good potential in detecting the true stimulus correlated changes in the presence of other interfering signals.

  8. Presbycusis Disrupts Spontaneous Activity Revealed by Resting-State Functional MRI

    Directory of Open Access Journals (Sweden)

    Yu-Chen Chen

    2018-03-01

    Full Text Available Purpose: Presbycusis, age-related hearing loss, is believed to involve neural changes in the central nervous system, which is associated with an increased risk of cognitive impairment. The goal of this study was to determine if presbycusis disrupted spontaneous neural activity in specific brain areas involved in auditory processing, attention and cognitive function using resting-state functional magnetic resonance imaging (fMRI approach.Methods: Hearing and resting-state fMRI measurements were obtained from 22 presbycusis patients and 23 age-, sex- and education-matched healthy controls. To identify changes in spontaneous neural activity associated with age-related hearing loss, we compared the amplitude of low-frequency fluctuations (ALFF and regional homogeneity (ReHo of fMRI signals in presbycusis patients vs. controls and then determined if these changes were linked to clinical measures of presbycusis.Results: Compared with healthy controls, presbycusis patients manifested decreased spontaneous activity mainly in the superior temporal gyrus (STG, parahippocampal gyrus (PHG, precuneus and inferior parietal lobule (IPL as well as increased neural activity in the middle frontal gyrus (MFG, cuneus and postcentral gyrus (PoCG. A significant negative correlation was observed between ALFF/ReHo activity in the STG and average hearing thresholds in presbycusis patients. Increased ALFF/ReHo activity in the MFG was positively correlated with impaired Trail-Making Test B (TMT-B scores, indicative of impaired cognitive function involving the frontal lobe.Conclusions: Presbycusis patients have disrupted spontaneous neural activity reflected by ALFF and ReHo measurements in several brain regions; these changes are associated with specific cognitive performance and speech/language processing. These findings mainly emphasize the crucial role of aberrant resting-state ALFF/ReHo patterns in presbycusis patients and will lead to a better understanding of the

  9. Presbycusis Disrupts Spontaneous Activity Revealed by Resting-State Functional MRI.

    Science.gov (United States)

    Chen, Yu-Chen; Chen, Huiyou; Jiang, Liang; Bo, Fan; Xu, Jin-Jing; Mao, Cun-Nan; Salvi, Richard; Yin, Xindao; Lu, Guangming; Gu, Jian-Ping

    2018-01-01

    Purpose : Presbycusis, age-related hearing loss, is believed to involve neural changes in the central nervous system, which is associated with an increased risk of cognitive impairment. The goal of this study was to determine if presbycusis disrupted spontaneous neural activity in specific brain areas involved in auditory processing, attention and cognitive function using resting-state functional magnetic resonance imaging (fMRI) approach. Methods : Hearing and resting-state fMRI measurements were obtained from 22 presbycusis patients and 23 age-, sex- and education-matched healthy controls. To identify changes in spontaneous neural activity associated with age-related hearing loss, we compared the amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) of fMRI signals in presbycusis patients vs. controls and then determined if these changes were linked to clinical measures of presbycusis. Results : Compared with healthy controls, presbycusis patients manifested decreased spontaneous activity mainly in the superior temporal gyrus (STG), parahippocampal gyrus (PHG), precuneus and inferior parietal lobule (IPL) as well as increased neural activity in the middle frontal gyrus (MFG), cuneus and postcentral gyrus (PoCG). A significant negative correlation was observed between ALFF/ReHo activity in the STG and average hearing thresholds in presbycusis patients. Increased ALFF/ReHo activity in the MFG was positively correlated with impaired Trail-Making Test B (TMT-B) scores, indicative of impaired cognitive function involving the frontal lobe. Conclusions : Presbycusis patients have disrupted spontaneous neural activity reflected by ALFF and ReHo measurements in several brain regions; these changes are associated with specific cognitive performance and speech/language processing. These findings mainly emphasize the crucial role of aberrant resting-state ALFF/ReHo patterns in presbycusis patients and will lead to a better understanding of the

  10. Active pain coping is associated with the response in real-time fMRI neurofeedback during pain.

    Science.gov (United States)

    Emmert, Kirsten; Breimhorst, Markus; Bauermann, Thomas; Birklein, Frank; Rebhorn, Cora; Van De Ville, Dimitri; Haller, Sven

    2017-06-01

    Real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback is used as a tool to gain voluntary control of activity in various brain regions. Little emphasis has been put on the influence of cognitive and personality traits on neurofeedback efficacy and baseline activity. Here, we assessed the effect of individual pain coping on rt-fMRI neurofeedback during heat-induced pain. Twenty-eight healthy subjects completed the Coping Strategies Questionnaire (CSQ) prior to scanning. The first part of the fMRI experiment identified target regions using painful heat stimulation. Then, subjects were asked to down-regulate the pain target brain region during four neurofeedback runs with painful heat stimulation. Functional MRI analysis included correlation analysis between fMRI activation and pain ratings as well as CSQ ratings. At the behavioral level, the active pain coping (first principal component of CSQ) was correlated with pain ratings during neurofeedback. Concerning neuroimaging, pain sensitive regions were negatively correlated with pain coping. During neurofeedback, the pain coping was positively correlated with activation in the anterior cingulate cortex, prefrontal cortex, hippocampus and visual cortex. Thermode temperature was negatively correlated with anterior insula and dorsolateral prefrontal cortex activation. In conclusion, self-reported pain coping mechanisms and pain sensitivity are a source of variance during rt-fMRI neurofeedback possibly explaining variations in regulation success. In particular, active coping seems to be associated with successful pain regulation.

  11. An active learning approach to education in MRI technology for the biomedical engineering curriculum

    DEFF Research Database (Denmark)

    Hanson, Lars G.

    2012-01-01

    techniques but can also be used for student exercises which may significantly improve the understanding of MRI concepts. The presentation demonstrates software made for the first few minutes of MRI education but focuses mostly on the educational value of the more advanced Bloch Simulator. It is explored how...... sense expressed in the math is in focus. Unfortunately, the nuclear dynamics happen in four dimensions, and are therefore not well suited for illustration on blackboard. 3D movies are more appropriate, but they do not encourage active learning. The typical solution employed by educators is hand waving...... (literally), since arm motions can to a limited extent be used to illustrate nuclear dynamics. Many students find this confusing, however, and students who do not grasp the meaning during lectures, are left in a bad position. For this reason, educational software was developed over the last decade (the Bloch...

  12. Classification of autistic individuals and controls using cross-task characterization of fMRI activity

    Directory of Open Access Journals (Sweden)

    Guillaume Chanel

    2016-01-01

    Full Text Available Multivariate pattern analysis (MVPA has been applied successfully to task-based and resting-based fMRI recordings to investigate which neural markers distinguish individuals with autistic spectrum disorders (ASD from controls. While most studies have focused on brain connectivity during resting state episodes and regions of interest approaches (ROI, a wealth of task-based fMRI datasets have been acquired in these populations in the last decade. This calls for techniques that can leverage information not only from a single dataset, but from several existing datasets that might share some common features and biomarkers. We propose a fully data-driven (voxel-based approach that we apply to two different fMRI experiments with social stimuli (faces and bodies. The method, based on Support Vector Machines (SVMs and Recursive Feature Elimination (RFE, is first trained for each experiment independently and each output is then combined to obtain a final classification output. Second, this RFE output is used to determine which voxels are most often selected for classification to generate maps of significant discriminative activity. Finally, to further explore the clinical validity of the approach, we correlate phenotypic information with obtained classifier scores. The results reveal good classification accuracy (range between 69% and 92.3%. Moreover, we were able to identify discriminative activity patterns pertaining to the social brain without relying on a priori ROI definitions. Finally, social motivation was the only dimension which correlated with classifier scores, suggesting that it is the main dimension captured by the classifiers. Altogether, we believe that the present RFE method proves to be efficient and may help identifying relevant biomarkers by taking advantage of acquired task-based fMRI datasets in psychiatric populations.

  13. Spectral embedding based active contour (SEAC): application to breast lesion segmentation on DCE-MRI

    Science.gov (United States)

    Agner, Shannon C.; Xu, Jun; Rosen, Mark; Karthigeyan, Sudha; Englander, Sarah; Madabhushi, Anant

    2011-03-01

    Spectral embedding (SE), a graph-based manifold learning method, has previously been shown to be useful in high dimensional data classification. In this work, we present a novel SE based active contour (SEAC) segmentation scheme and demonstrate its applications in lesion segmentation on breast dynamic contrast enhance magnetic resonance imaging (DCE-MRI). In this work, we employ SE on DCE-MRI on a per voxel basis to embed the high dimensional time series intensity vector into a reduced dimensional space, where the reduced embedding space is characterized by the principal eigenvectors. The orthogonal eigenvector-based data representation allows for computation of strong tensor gradients in the spectrally embedded space and also yields improved region statistics that serve as optimal stopping criteria for SEAC. We demonstrate both analytically and empirically that the tensor gradients in the spectrally embedded space are stronger than the corresponding gradients in the original grayscale intensity space. On a total of 50 breast DCE-MRI studies, SEAC yielded a mean absolute difference (MAD) of 3.2+/-2.1 pixels and mean Dice similarity coefficient (DSC) of 0.74+/-0.13 compared to manual ground truth segmentation. An active contour in conjunction with fuzzy c-means (FCM+AC), a commonly used segmentation method for breast DCE-MRI, produced a corresponding MAD of 7.2+/-7.4 pixels and mean DSC of 0.58+/-0.32. In conjunction with a set of 6 quantitative morphological features automatically extracted from the SEAC derived lesion boundary, a support vector machine (SVM) classifier yielded an area under the curve (AUC) of 0.73, for discriminating between 10 benign and 30 malignant lesions; the corresponding SVM classifier with the FCM+AC derived morphological features yielded an AUC of 0.65.

  14. Classification of autistic individuals and controls using cross-task characterization of fMRI activity

    Science.gov (United States)

    Chanel, Guillaume; Pichon, Swann; Conty, Laurence; Berthoz, Sylvie; Chevallier, Coralie; Grèzes, Julie

    2015-01-01

    Multivariate pattern analysis (MVPA) has been applied successfully to task-based and resting-based fMRI recordings to investigate which neural markers distinguish individuals with autistic spectrum disorders (ASD) from controls. While most studies have focused on brain connectivity during resting state episodes and regions of interest approaches (ROI), a wealth of task-based fMRI datasets have been acquired in these populations in the last decade. This calls for techniques that can leverage information not only from a single dataset, but from several existing datasets that might share some common features and biomarkers. We propose a fully data-driven (voxel-based) approach that we apply to two different fMRI experiments with social stimuli (faces and bodies). The method, based on Support Vector Machines (SVMs) and Recursive Feature Elimination (RFE), is first trained for each experiment independently and each output is then combined to obtain a final classification output. Second, this RFE output is used to determine which voxels are most often selected for classification to generate maps of significant discriminative activity. Finally, to further explore the clinical validity of the approach, we correlate phenotypic information with obtained classifier scores. The results reveal good classification accuracy (range between 69% and 92.3%). Moreover, we were able to identify discriminative activity patterns pertaining to the social brain without relying on a priori ROI definitions. Finally, social motivation was the only dimension which correlated with classifier scores, suggesting that it is the main dimension captured by the classifiers. Altogether, we believe that the present RFE method proves to be efficient and may help identifying relevant biomarkers by taking advantage of acquired task-based fMRI datasets in psychiatric populations. PMID:26793434

  15. Damage recovery and optical activity in europium implanted wide gap oxides

    International Nuclear Information System (INIS)

    Alves, E.; Marques, C.; Franco, N.; Alves, L.C.; Peres, M.; Soares, M.J.; Monteiro, T.

    2010-01-01

    In this study we compare and discuss the defects and optical behaviour of sapphire and magnesium oxide single crystals implanted at room temperature with different fluences (1 x 10 15 -1 x 10 16 cm -2 ) of europium ions. Rutherford backscattering channelling shows that for fluences above 5 x 10 15 cm -2 the surface disorder level in the Al-sublattice reaches the random level. Implantation damage recovers fast for annealing in oxidizing atmosphere but even for the highest fluence we recover almost completely all the damage after annealing at 1300 o C, independently of the annealing environment (reducing or oxidizing). Annealing above 1000 o C promotes the formation of Eu 2 O 3 in the samples with higher concentration of Eu. The optical activation of the rare earth ions at room temperature was observed after annealing at 800 o C by photoluminescence and ionoluminescence. In Al 2 O 3 lattice the highest intensity line of the Eu 3+ ions corresponds to the forced electric dipole 5 D 0 → 7 F 2 transition that occurs ∼616 nm. For the MgO samples the Eu 3+ optical activation was also achieved after implantation with different fluences. Here, the lanthanide recombination is dominated by the magnetic dipole 5 D 0 → 7 F 1 transition near by 590 nm commonly observed for samples were Eu 3+ is placed in a high symmetry local site. The results clearly demonstrate the possibility to get Eu incorporated in optical active regular lattice sites in wide gap oxides.

  16. Pacemaker Implantation Associated Myocardial Micro-Damage: A Randomised Comparison between Active and Passive Fixation Leads.

    Science.gov (United States)

    Blažek, Patrick; Ferri-Certić, Jerko; Vražić, Hrvoje; Lennerz, Carsten; Grebmer, Christian; Kaitani, Kazuaki; Karch, Martin; Starčević, Boris; Semmler, Verena; Kolb, Christof

    2018-03-20

    Fixation of the pacemaker leads during pacemaker implantation leads to an increase of cardiac Troponin T (cTnT) that can be interpreted as a sign of minimal myocardial damage. This trial evaluates whether the mechanism type of lead fixation influences the magnitude of cTnT release. Patients having a de-novo cardiac pacemaker implantation or a lead revision were centrally randomized to receive either a ventricular lead with an active (screw) or passive (tine) fixation mechanism. High-sensitive Troponin T (hsTnT) was determined on the day of the procedure beforehand and on the following day. 326 Patients (median age (IQR) 75.0 (69.0-80.0) years, 64% male) from six international centers were randomized to receive ventricular leads with an active (n = 166) or passive (n = 160) fixation mechanism. Median (IQR) hsTnT levels increased by 0.009 (0.004-0.021) ng/ml in the group receiving screw-in ventricular leads and by 0.008 (0.003-0.030) ng/ml in the group receiving tined ventricular leads (n.s.). In conclusion pacemaker implantations are followed by a release of hsTnT. The choice between active or passive fixation ventricular leads does not have a significant influence on the extent of myocardial injury and the magnitude of hsTnT release.

  17. Activated and deactivated functional brain areas in the Deqi state: A functional MRI study.

    Science.gov (United States)

    Huang, Yong; Zeng, Tongjun; Zhang, Guifeng; Li, Ganlong; Lu, Na; Lai, Xinsheng; Lu, Yangjia; Chen, Jiarong

    2012-10-25

    We compared the activities of functional regions of the brain in the Deqi versus non-Deqi state, as reported by physicians and subjects during acupuncture. Twelve healthy volunteers received sham and true needling at the Waiguan (TE5) acupoint. Real-time cerebral functional MRI showed that compared with non-sensation after sham needling, true needling activated Brodmann areas 3, 6, 8, 9, 10, 11, 13, 20, 21, 37, 39, 40, 43, and 47, the head of the caudate nucleus, the parahippocampal gyrus, thalamus and red nucleus. True needling also deactivated Brodmann areas 1, 2, 3, 4, 5, 6, 7, 9, 10, 18, 24, 31, 40 and 46.

  18. Modality Specific Cerebro-Cerebellar Activations in Verbal Working Memory: An fMRI Study

    Directory of Open Access Journals (Sweden)

    Matthew P. Kirschen

    2010-01-01

    Full Text Available Verbal working memory (VWM engages frontal and temporal/parietal circuits subserving the phonological loop, as well as, superior and inferior cerebellar regions which have projections from these neocortical areas. Different cerebro-cerebellar circuits may be engaged for integrating aurally- and visually-presented information for VWM. The present fMRI study investigated load (2, 4, or 6 letters and modality (auditory and visual dependent cerebro-cerebellar VWM activation using a Sternberg task. FMRI revealed modality-independent activations in left frontal (BA 6/9/44, insular, cingulate (BA 32, and bilateral inferior parietal/supramarginal (BA 40 regions, as well as in bilateral superior (HVI and right inferior (HVIII cerebellar regions. Visual presentation evoked prominent activations in right superior (HVI/CrusI cerebellum, bilateral occipital (BA19 and left parietal (BA7/40 cortex while auditory presentation showed robust activations predominately in bilateral temporal regions (BA21/22. In the cerebellum, we noted a visual to auditory emphasis of function progressing from superior to inferior and from lateral to medial regions. These results extend our previous findings of fMRI activation in cerebro-cerebellar networks during VWM, and demonstrate both modality dependent commonalities and differences in activations with increasing memory load.

  19. Activation on occipital lobe in children with abacus mental calculation training: an fMRI study

    International Nuclear Information System (INIS)

    Shen Xiaojun; Long Jinfeng; Zhao Kunyuan; Li Lixin; Sun Jining; Wang Bin

    2011-01-01

    Objective: By exploring the activation on occipital lobe in children with and without abacus mental calculation training when they engaged in different calculation tasks with functional magnetic resonance imaging (fMRI), to identify the possible mechanism of occipital lobe in abacus mental calculation. Methods: fMRI was performed in children trained with and without (sixteen in each group) abacus mental calculation when they engaged in addition, subtraction. multiplication, division, and number-object control judging tasks. The data processing and statistical analysis were performed on SPM 2.0 (statistical parametric mapping 2.0) and the related-brain functional areas were identified. The activation on occipital lobe was observed carefully. The difference in activated areas of occipital lobe was statistically significant between two groups engaged in different tasks of calculations (P<0.01). Result: Bilateral occipital lobe, especially in the cuneus and lingual gyrus, were activated in children trained with abacus mental calculation. The main activated area was lingual gyrus in children without abacus mental calculation. Conclusion: The occipital lobe participates visuospatial processing in the abacus mental calculations. The neuromechanism maybe account for the specific activation in occipital lobe. (authors)

  20. Imaging seizure activity: a combined EEG/EMG-fMRI study in reading epilepsy.

    Science.gov (United States)

    Salek-Haddadi, Afraim; Mayer, Thomas; Hamandi, Khalid; Symms, Mark; Josephs, Oliver; Fluegel, Dominique; Woermann, Friedrich; Richardson, Mark P; Noppeney, Uta; Wolf, Peter; Koepp, Matthias J

    2009-02-01

    To characterize the spatial relationship between activations related to language-induced seizure activity, language processing, and motor control in patients with reading epilepsy. We recorded and simultaneously monitored several physiological parameters [voice-recording, electromyography (EMG), electrocardiography (ECG), electroencephalography (EEG)] during blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) in nine patients with reading epilepsy. Individually tailored language paradigms were used to induce and record habitual seizures inside the MRI scanner. Voxel-based morphometry (VBM) was used for structural brain analysis. Reading-induced seizures occurred in six out of nine patients. One patient experienced abundant orofacial reflex myocloni during silent reading in association with bilateral frontal or generalized epileptiform discharges. In a further five patients, symptoms were only elicited while reading aloud with self-indicated events. Consistent activation patterns in response to reading-induced myoclonic seizures were observed within left motor and premotor areas in five of these six patients, in the left striatum (n = 4), in mesiotemporal/limbic areas (n = 4), in Brodmann area 47 (n = 3), and thalamus (n = 2). These BOLD activations were overlapping or adjacent to areas physiologically activated during language and facial motor tasks. No subtle structural abnormalities common to all patients were identified using VBM, but one patient had a left temporal ischemic lesion. Based on the findings, we hypothesize that reflex seizures occur in reading epilepsy when a critical mass of neurons are activated through a provoking stimulus within corticoreticular and corticocortical circuitry subserving normal functions.

  1. Differential Activation Patterns of fMRI in Sleep-Deprived Brain: Restoring Effects of Acupuncture

    Directory of Open Access Journals (Sweden)

    Lei Gao

    2014-01-01

    Full Text Available Previous studies suggested a remediation role of acupuncture in insomnia, and acupuncture also has been used in insomnia empirically and clinically. In this study, we employed fMRI to test the role of acupuncture in sleep deprivation (SD. Sixteen healthy volunteers (8 males were recruited and scheduled for three fMRI scanning procedures, one following the individual’s normal sleep and received acupuncture SP6 (NOR group and the other two after 24 h of total SD with acupuncture on SP6 (SD group or sham (Sham group. The sessions were counterbalanced approximately two weeks apart. Acupuncture stimuli elicited significantly different activation patterns of three groups. In NOR group, the right superior temporal lobe, left inferior parietal lobule, and left postcentral gyrus were activated; in SD group, the anterior cingulate cortex, bilateral insula, left basal ganglia, and thalamus were significantly activated while, in Sham group, the bilateral thalamus and left cerebellum were activated. Different activation patterns suggest a unique role of acupuncture on SP6 in remediation of SD. SP6 elicits greater and anatomically different activations than those of sham stimuli; that is, the salience network, a unique interoceptive autonomic circuit, may indicate the mechanism underlying acupuncture in restoring sleep deprivation.

  2. Modality Specific Cerebro-Cerebellar Activations in Verbal Working Memory: An fMRI Study

    Science.gov (United States)

    Kirschen, Matthew P.; Chen, S. H. Annabel; Desmond, John E.

    2010-01-01

    Verbal working memory (VWM) engages frontal and temporal/parietal circuits subserving the phonological loop, as well as, superior and inferior cerebellar regions which have projections from these neocortical areas. Different cerebro-cerebellar circuits may be engaged for integrating aurally- and visually-presented information for VWM. The present fMRI study investigated load (2, 4, or 6 letters) and modality (auditory and visual) dependent cerebro-cerebellar VWM activation using a Sternberg task. FMRI revealed modality-independent activations in left frontal (BA 6/9/44), insular, cingulate (BA 32), and bilateral inferior parietal/supramarginal (BA 40) regions, as well as in bilateral superior (HVI) and right inferior (HVIII) cerebellar regions. Visual presentation evoked prominent activations in right superior (HVI/CrusI) cerebellum, bilateral occipital (BA19) and left parietal (BA7/40) cortex while auditory presentation showed robust activations predominately in bilateral temporal regions (BA21/22). In the cerebellum, we noted a visual to auditory emphasis of function progressing from superior to inferior and from lateral to medial regions. These results extend our previous findings of fMRI activation in cerebro-cerebellar networks during VWM, and demonstrate both modality dependent commonalities and differences in activations with increasing memory load. PMID:20714061

  3. Detecting Activation in fMRI Data: An Approach Based on Sparse Representation of BOLD Signal

    Directory of Open Access Journals (Sweden)

    Blanca Guillen

    2018-01-01

    Full Text Available This paper proposes a simple yet effective approach for detecting activated voxels in fMRI data by exploiting the inherent sparsity property of the BOLD signal in temporal and spatial domains. In the time domain, the approach combines the General Linear Model (GLM with a Least Absolute Deviation (LAD based regression method regularized by the pseudonorm l0 to promote sparsity in the parameter vector of the model. In the spatial domain, detection of activated regions is based on thresholding the spatial map of estimated parameters associated with a particular stimulus. The threshold is calculated by exploiting the sparseness of the BOLD signal in the spatial domain assuming a Laplacian distribution model. The proposed approach is validated using synthetic and real fMRI data. For synthetic data, results show that the proposed approach is able to detect most activated voxels without any false activation. For real data, the method is evaluated through comparison with the SPM software. Results indicate that this approach can effectively find activated regions that are similar to those found by SPM, but using a much simpler approach. This study may lead to the development of robust spatial approaches to further simplifying the complexity of classical schemes.

  4. Computerized liver volumetry on MRI by using 3D geodesic active contour segmentation.

    Science.gov (United States)

    Huynh, Hieu Trung; Karademir, Ibrahim; Oto, Aytekin; Suzuki, Kenji

    2014-01-01

    Our purpose was to develop an accurate automated 3D liver segmentation scheme for measuring liver volumes on MRI. Our scheme for MRI liver volumetry consisted of three main stages. First, the preprocessing stage was applied to T1-weighted MRI of the liver in the portal venous phase to reduce noise and produce the boundary-enhanced image. This boundary-enhanced image was used as a speed function for a 3D fast-marching algorithm to generate an initial surface that roughly approximated the shape of the liver. A 3D geodesic-active-contour segmentation algorithm refined the initial surface to precisely determine the liver boundaries. The liver volumes determined by our scheme were compared with those manually traced by a radiologist, used as the reference standard. The two volumetric methods reached excellent agreement (intraclass correlation coefficient, 0.98) without statistical significance (p = 0.42). The average (± SD) accuracy was 99.4% ± 0.14%, and the average Dice overlap coefficient was 93.6% ± 1.7%. The mean processing time for our automated scheme was 1.03 ± 0.13 minutes, whereas that for manual volumetry was 24.0 ± 4.4 minutes (p volumetry based on our automated scheme agreed excellently with reference-standard volumetry, and it required substantially less completion time.

  5. Vacancy clustering and acceptor activation in nitrogen-implanted ZnO

    Science.gov (United States)

    Børseth, Thomas Moe; Tuomisto, Filip; Christensen, Jens S.; Monakhov, Edouard V.; Svensson, Bengt G.; Kuznetsov, Andrej Yu.

    2008-01-01

    The role of vacancy clustering and acceptor activation on resistivity evolution in N ion-implanted n -type hydrothermally grown bulk ZnO has been investigated by positron annihilation spectroscopy, resistivity measurements, and chemical profiling. Room temperature 220keV N implantation using doses in the low 1015cm-2 range induces small and big vacancy clusters containing at least 2 and 3-4 Zn vacancies, respectively. The small clusters are present already in as-implanted samples and remain stable up to 1000°C with no significant effect on the resistivity evolution. In contrast, formation of the big clusters at 600°C is associated with a significant increase in the free electron concentration attributed to gettering of amphoteric Li impurities by these clusters. Further annealing at 800°C results in a dramatic decrease in the free electron concentration correlated with activation of 1016-1017cm-3 acceptors likely to be N and/or Li related. The samples remain n type, however, and further annealing at 1000°C results in passivation of the acceptor states while the big clusters dissociate.

  6. Motor imagery training: Kinesthetic imagery strategy and inferior parietal fMRI activation.

    Science.gov (United States)

    Lebon, Florent; Horn, Ulrike; Domin, Martin; Lotze, Martin

    2018-04-01

    Motor imagery (MI) is the mental simulation of action frequently used by professionals in different fields. However, with respect to performance, well-controlled functional imaging studies on MI training are sparse. We investigated changes in fMRI representation going along with performance changes of a finger sequence (error and velocity) after MI training in 48 healthy young volunteers. Before training, we tested the vividness of kinesthetic and visual imagery. During tests, participants were instructed to move or to imagine moving the fingers of the right hand in a specific order. During MI training, participants repeatedly imagined the sequence for 15 min. Imaging analysis was performed using a full-factorial design to assess brain changes due to imagery training. We also used regression analyses to identify those who profited from training (performance outcome and gain) with initial imagery scores (vividness) and fMRI activation magnitude during MI at pre-test (MI pre ). After training, error rate decreased and velocity increased. We combined both parameters into a common performance index. FMRI activation in the left inferior parietal lobe (IPL) was associated with MI and increased over time. In addition, fMRI activation in the right IPL during MI pre was associated with high initial kinesthetic vividness. High kinesthetic imagery vividness predicted a high performance after training. In contrast, occipital activation, associated with visual imagery strategies, showed a negative predictive value for performance. Our data echo the importance of high kinesthetic vividness for MI training outcome and consider IPL as a key area during MI and through MI training. © 2018 Wiley Periodicals, Inc.

  7. Beryllium implant activation and damage recovery study in n-type GaSb

    Science.gov (United States)

    Rahimi, N.; Behzadirad, M.; Renteria, Emma J.; Shima, D. M.; Muniz, Ayse J.; Busani, T.; Lavrova, Olga; Balakrishnan, G.; Lester, L. F.

    2014-03-01

    Damage induced by the implantation of beryllium in n-type GaSb and its removal by Rapid Thermal Annealing (RTA) are studied in detail by Atomic Force Microscopy (AFM), Cross Sectional Transmission Electron Microscopy (XTEM) and Energy Dispersive X-ray Spectroscopy (EDS). RTA has been implemented with different times and temperatures in order to optimize ion activation and to avoid Sb outdiffusion during the process. Results indicate a lattice quality that is close to pristine GaSb for samples annealed at 600 °C for 10s using a thick Si3N4 capping layer. Electrical response of the implanted diodes is measured and characterized as function of different annealing conditions.

  8. RESOLUTE PET/MRI Attenuation Correction for O-(2-F-fluoroethyl)-L-tyrosine (FET) in Brain Tumor Patients with Metal Implants

    DEFF Research Database (Denmark)

    Ladefoged, Claes N; Andersen, Flemming L; Kjær, Andreas

    2017-01-01

    of agreement for TMAX/B was for RESOLUTE (-3%; 4%), Dixon (-9%; 16%), and UTE (-7%; 10%). The absolute error when measuring BTV was 0.7 ± 1.9 mL (N.S) with RESOLUTE, 5.3 ± 10 mL using Dixon, and 1.7 ± 3.7 mL using UTE. RESOLUTE performed best in the identification of the location of peak activity and in brain...... to be quantitatively correct in order to be used clinically, which require accurate attenuation correction (AC) in PET/MRI. The aim of this study was to evaluate the use of the subject-specific MR-derived AC method RESOLUTE in post-operative brain tumor patients.Methods:We analyzed 51 post-operative brain tumor...... patients (68 examinations, 200 MBq [18F]-FET) investigated in a PET/MRI scanner. MR-AC maps were acquired using: (1) the Dixon water fat separation sequence, (2) the ultra short echo time (UTE) sequences, (3) calculated using our new RESOLUTE methodology, and (4) a same day low-dose CT used as reference...

  9. Biocompatibility and anti-microbiological activity characterization of novel coatings for dental implants: A primer for non-biologists

    Directory of Open Access Journals (Sweden)

    Thomas K Monsees

    2016-08-01

    Full Text Available With regard to biocompatibility, the cardinal requirement for dental implants and other medical devices that are in long-term contact with tissue is that the material does not cause any adverse effect to the patient. To warrant stability and function of the implant, proper osseointegration is a further prerequisite. Cells interact with the implant surface as the interface between bulk material and biological tissue. Whereas structuring, deposition of a thin film or other modifications of the surface are crucial parameters in determining favorable adhesion of cells, corrosion of metal surfaces and release of ions can affect cell viability. Both parameters are usually tested using in vitro cytotoxicity and adhesion assays with bone or fibroblasts cells. For bioactive surface modifications, further tests should be considered for biocompatibility evaluation. Depending on the type of modification, this may include analysis of specific cell functions or the determination of antimicrobial activities. The latter is of special importance as bacteria and yeast present in the oral cavity can be introduced during the implantation process and this may lead to chronic infections and implant failure. An antimicrobial coating of the implant is a way to avoid that. This review describes the essential biocompatibility assays for evaluation of new implant materials required by ISO 10993 and also gives an overview on recent test methods for specific coatings of dental implants.

  10. Biocompatibility and anti-microbiological activity characterization of novel coatings for dental implants: A primer for non-biologists

    Science.gov (United States)

    Monsees, Thomas

    2016-08-01

    With regard to biocompatibility, the cardinal requirement for dental implants and other medical devices that are in long-term contact with tissue is that the material does not cause any adverse effect to the patient. To warrant stability and function of the implant, proper osseointegration is a further prerequisite. Cells interact with the implant surface as the interface between bulk material and biological tissue. Whereas structuring, deposition of a thin film or other modifications of the surface are crucial parameters in determining favorable adhesion of cells, corrosion of metal surfaces and release of ions can affect cell viability. Both parameters are usually tested using in vitro cytotoxicity and adhesion assays with bone or fibroblasts cells. For bioactive surface modifications, further tests should be considered for biocompatibility evaluation. Depending on the type of modification, this may include analysis of specific cell functions or the determination of antimicrobial activities. The latter is of special importance as bacteria and yeast present in the oral cavity can be introduced during the implantation process and this may lead to chronic infections and implant failure. An antimicrobial coating of the implant is a way to avoid that. This review describes the essential biocompatibility assays for evaluation of new implant materials required by ISO 10993 and also gives an overview on recent test methods for specific coatings of dental implants.

  11. Altered cortical activation during action observation in amyotrophic lateral sclerosis patients: a parametric functional MRI study

    International Nuclear Information System (INIS)

    Li, Haiqing; Li, Yuxin; Yin, Bo; Tang, Weijun; Yu, Xiangrong; Geng, Daoying; Chen, Yan; Huang, Weiyuan; Zhang, Biyun

    2015-01-01

    To investigate functional cerebral abnormalities in patients with amyotrophic lateral sclerosis (ALS) using functional magnetic resonance imaging (fMRI) during action observation. Thirty patients with ALS and 30 matched healthy controls underwent fMRI with an experimental paradigm while observing a video of repetitive flexion-extension of the fingers at three frequency levels or three complexity levels, alternated with periods of a static hand. A parametric analysis was applied to determine the effects of each of the two factors. Action observation activated similar neural networks as the research on execution of action in the ALS patients and healthy subjects in several brain regions related to the mirror-neuron system (MNS). In the ALS patients, in particular, the dorsal lateral premotor cortex (dPMC), inferior parietal gyrus (IPG), and SMA, were more activated compared with the activation in the controls. Increased activation within the primary motor cortex (M1), dPMC, inferior frontal gyrus (IFG), and superior parietal gyrus (SPG) mainly correlated with hand movement frequency/complexity in the videos in the patients compared with controls. The findings indicated an ongoing compensatory process occurring within the higher order motor-processing system of ALS patients, likely to overcome the loss of function. (orig.)

  12. Altered cortical activation during action observation in amyotrophic lateral sclerosis patients: a parametric functional MRI study

    Energy Technology Data Exchange (ETDEWEB)

    Li, Haiqing; Li, Yuxin; Yin, Bo; Tang, Weijun; Yu, Xiangrong; Geng, Daoying [Huashan Hospital, Department of Radiology, Fudan University, Shanghai (China); Chen, Yan [Fudan University, Department of Neurology, Huashan Hospital, Shanghai (China); Huang, Weiyuan [People' s Hospital of Hainan Province, Department of Radiology, Haikou, Hainan Province (China); Zhang, Biyun [Nanjing University of Traditional Chinese Medicine, Department of radiotherapy, Affiliated Jiangsu Province Hospital of Traditional Chinese Medicine, Nanjing (China)

    2015-09-15

    To investigate functional cerebral abnormalities in patients with amyotrophic lateral sclerosis (ALS) using functional magnetic resonance imaging (fMRI) during action observation. Thirty patients with ALS and 30 matched healthy controls underwent fMRI with an experimental paradigm while observing a video of repetitive flexion-extension of the fingers at three frequency levels or three complexity levels, alternated with periods of a static hand. A parametric analysis was applied to determine the effects of each of the two factors. Action observation activated similar neural networks as the research on execution of action in the ALS patients and healthy subjects in several brain regions related to the mirror-neuron system (MNS). In the ALS patients, in particular, the dorsal lateral premotor cortex (dPMC), inferior parietal gyrus (IPG), and SMA, were more activated compared with the activation in the controls. Increased activation within the primary motor cortex (M1), dPMC, inferior frontal gyrus (IFG), and superior parietal gyrus (SPG) mainly correlated with hand movement frequency/complexity in the videos in the patients compared with controls. The findings indicated an ongoing compensatory process occurring within the higher order motor-processing system of ALS patients, likely to overcome the loss of function. (orig.)

  13. Differentiating maturational and training influences on fMRI activation during music processing.

    Science.gov (United States)

    Ellis, Robert J; Norton, Andrea C; Overy, Katie; Winner, Ellen; Alsop, David C; Schlaug, Gottfried

    2012-04-15

    Two major influences on how the brain processes music are maturational development and active musical training. Previous functional neuroimaging studies investigating music processing have typically focused on either categorical differences between "musicians versus nonmusicians" or "children versus adults." In the present study, we explored a cross-sectional data set (n=84) using multiple linear regression to isolate the performance-independent effects of age (5 to 33 years) and cumulative duration of musical training (0 to 21,000 practice hours) on fMRI activation similarities and differences between melodic discrimination (MD) and rhythmic discrimination (RD). Age-related effects common to MD and RD were present in three left hemisphere regions: temporofrontal junction, ventral premotor cortex, and the inferior part of the intraparietal sulcus, regions involved in active attending to auditory rhythms, sensorimotor integration, and working memory transformations of pitch and rhythmic patterns. By contrast, training-related effects common to MD and RD were localized to the posterior portion of the left superior temporal gyrus/planum temporale, an area implicated in spectrotemporal pattern matching and auditory-motor coordinate transformations. A single cluster in right superior temporal gyrus showed significantly greater activation during MD than RD. This is the first fMRI which has distinguished maturational from training effects during music processing. Copyright © 2012 Elsevier Inc. All rights reserved.

  14. Altered spontaneous brain activity in patients with hemifacial spasm: a resting-state functional MRI study.

    Directory of Open Access Journals (Sweden)

    Ye Tu

    Full Text Available Resting-state functional magnetic resonance imaging (fMRI has been used to detect the alterations of spontaneous neuronal activity in various neurological and neuropsychiatric diseases, but rarely in hemifacial spasm (HFS, a nervous system disorder. We used resting-state fMRI with regional homogeneity (ReHo analysis to investigate changes in spontaneous brain activity of patients with HFS and to determine the relationship of these functional changes with clinical features. Thirty patients with HFS and 33 age-, sex-, and education-matched healthy controls were included in this study. Compared with controls, HFS patients had significantly decreased ReHo values in left middle frontal gyrus (MFG, left medial cingulate cortex (MCC, left lingual gyrus, right superior temporal gyrus (STG and right precuneus; and increased ReHo values in left precentral gyrus, anterior cingulate cortex (ACC, right brainstem, and right cerebellum. Furthermore, the mean ReHo value in brainstem showed a positive correlation with the spasm severity (r = 0.404, p = 0.027, and the mean ReHo value in MFG was inversely related with spasm severity in HFS group (r = -0.398, p = 0.028. This study reveals that HFS is associated with abnormal spontaneous brain activity in brain regions most involved in motor control and blinking movement. The disturbances of spontaneous brain activity reflected by ReHo measurements may provide insights into the neurological pathophysiology of HFS.

  15. Heart MRI

    Science.gov (United States)

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

  16. Degenerative joint disease on MRI and physical activity: a clinical study of the knee joint in 320 patients

    International Nuclear Information System (INIS)

    Bachmann, G.F.; Rauber, K.; Damian, M.S.; Rau, W.S.; Basad, E.

    1999-01-01

    We examined 320 patients with MRI and arthroscopy after an acute trauma to evaluate MRI in diagnosis of degenerative joint disease of the knee in relation to sports activity and clinical data. Lesions of cartilage and menisci on MRI were registered by two radiologists in consensus without knowledge of arthroscopy. Arthroscopy demonstrated grade-1 to grade-4 lesions of cartilage on 729 of 1920 joint surfaces of 320 knees, and MRI diagnosed 14 % of grade-1, 32 % of grade-2, 94 % of grade-3, and 100 % of grade-4 lesions. Arthroscopy explored 1280 meniscal areas and showed degenerations in 10 %, tears in 11.4 %, and complex lesions in 9.2 %. Magnetic resonance imaging was in agreement with arthroscopy in 81 % showing more degenerations but less tears of menisci than arthroscopy. Using a global system for grading the total damage of the knee joint into none, mild, moderate, or severe changes, agreement between arthroscopy and MRI was found in 82 %. Magnetic resonance imaging and arthroscopy showed coherently that degree of degenerative joint changes was significantly correlated to patient age or previous knee trauma. Patients over 40 years had moderate to severe changes on MRI in 45 % and patients under 30 years in only 22 %. Knee joints with a history of trauma without complete structural or functional reconstitution showed marked changes on MRI in 57 %, whereas stable joints without such alterations had degenerative changes in only 26 %. There was no correlation of degenerative disease to gender, weight, type, frequency, and intensity of sports activity. Therefore, MRI is an effective non-invasive imaging method for exact localization and quantification of chronic joint changes of cartilage and menisci that recommends MRI for monitoring in sports medicine. (orig.) (orig.)

  17. A functional MRI Exploration of Hamstring Activation During the Supine Bridge Exercise.

    Science.gov (United States)

    Bourne, Matthew; Williams, Morgan; Pizzari, Tania; Shield, Anthony

    2018-02-01

    The single leg supine bridge (SLB) is a commonly employed strengthening exercise and is used as a clinical test for hamstring function in sports, however, little is known about the patterns of muscle activation in this task. To explore these activation patterns, nine healthy, recreationally active males underwent functional magnetic resonance imaging (fMRI) of their thighs at rest and immediately after 5 sets of 10 repetitions of the SLB exercise. Exercise-induced increases in the transverse (T2) relaxation time of the biceps femoris long and short heads, semitendinosus and semimembranosus, were determined via signal intensity changes in pre- and post-exercise images and used as an index of muscle activation. The Bonferroni adjusted alpha was set at phamstring injury prevention and rehabilitation programs. © Georg Thieme Verlag KG Stuttgart · New York.

  18. Estimation of the neuronal activation using fMRI data: An observer-based approach

    KAUST Repository

    Laleg-Kirati, Taous-Meriem

    2013-06-01

    This paper deals with the estimation of the neuronal activation and some unmeasured physiological information using the Blood Oxygenation Level Dependent (BOLD) signal measured using functional Magnetic Resonance Imaging (fMRI). We propose to use an observer-based approach applied to the balloon hemodynamic model. The latter describes the relation between the neural activity and the BOLD signal. The balloon model can be expressed in a nonlinear state-space representation where the states, the parameters and the input (neuronal activation), are unknown. This study focuses only on the estimation of the hidden states and the neuronal activation. The model is first linearized around the equilibrium and an observer is applied to this linearized version. Numerical results performed on synthetic data are presented.

  19. Assessment of inflammatory activity in Crohn's disease by means of dynamic contrast-enhanced MRI.

    Science.gov (United States)

    Pupillo, V A; Di Cesare, E; Frieri, G; Limbucci, N; Tanga, M; Masciocchi, C

    2007-09-01

    Our aim was to perform a dynamic study of contrast enhancement of the intestinal wall in patients with Crohn's disease to quantitatively assess local inflammatory activity. We studied a population of 50 patients with histologically proven Crohn's disease. Magnetic resonance imaging (MRI) was performed using a 1.5-T magnet with a phased-array coil and acquisition of T2-weighted single-shot fast spin echo (SSFSE) half Fourier sequences before intravenous administration of gadolinium, and T1-weighted fast spoiled gradient (FSPGR) fat-saturated sequences before and after contrast administration. Before the examination, patents received oral polyethylene glycol (PEG) (1,000 ml for adults; 10 ml/Kg of body weight for children). Regions of interest (ROI) were placed on the normal and diseased intestinal wall to assess signal intensity and rate of increase in contrast enhancement over time. Data were compared with the Crohn's Disease Activity Index (CDAI). The diseased bowel wall showed early and intense uptake of contrast that increases over time until a plateau is reached. In patients in the remission phase after treatment, signal intensity was only slightly higher in diseased bowel loops than in healthy loops. There was a significant correlation between the peak of contrast uptake and CDAI. Dynamic MRI is a good technique for quantifying local inflammatory activity of bowel wall in patients with Crohn's disease.

  20. Activation of dorsolateral prefrontal cortex in a dual neuropsychological screening test: An fMRI approach

    Directory of Open Access Journals (Sweden)

    Tachibana Atsumichi

    2012-05-01

    Full Text Available Abstract Background The Kana Pick-out Test (KPT, which uses Kana or Japanese symbols that represent syllables, requires parallel processing of discrete (pick-out and continuous (reading dual tasks. As a dual task, the KPT is thought to test working memory and executive function, particularly in the prefrontal cortex (PFC, and is widely used in Japan as a clinical screen for dementia. Nevertheless, there has been little neurological investigation into PFC activity during this test. Methods We used functional magnetic resonance imaging (fMRI to evaluate changes in the blood oxygenation level-dependent (BOLD signal in young healthy adults during performance of a computerized KPT dual task (comprised of reading comprehension and picking out vowels and compared it to its single task components (reading or vowel pick-out alone. Results Behavioral performance of the KPT degraded compared to its single task components. Performance of the KPT markedly increased BOLD signal intensity in the PFC, and also activated sensorimotor, parietal association, and visual cortex areas. In conjunction analyses, bilateral BOLD signal in the dorsolateral PFC (Brodmann's areas 45, 46 was present only in the KPT. Conclusions Our results support the central bottleneck theory and suggest that the dorsolateral PFC is an important mediator of neural activity for both short-term storage and executive processes. Quantitative evaluation of the KPT with fMRI in healthy adults is the first step towards understanding the effects of aging or cognitive impairment on KPT performance.

  1. Activation of dorsolateral prefrontal cortex in a dual neuropsychological screening test: an fMRI approach.

    Science.gov (United States)

    Tachibana, Atsumichi; Noah, J Adam; Bronner, Shaw; Ono, Yumie; Hirano, Yoshiyuki; Niwa, Masami; Watanabe, Kazuko; Onozuka, Minoru

    2012-05-28

    The Kana Pick-out Test (KPT), which uses Kana or Japanese symbols that represent syllables, requires parallel processing of discrete (pick-out) and continuous (reading) dual tasks. As a dual task, the KPT is thought to test working memory and executive function, particularly in the prefrontal cortex (PFC), and is widely used in Japan as a clinical screen for dementia. Nevertheless, there has been little neurological investigation into PFC activity during this test. We used functional magnetic resonance imaging (fMRI) to evaluate changes in the blood oxygenation level-dependent (BOLD) signal in young healthy adults during performance of a computerized KPT dual task (comprised of reading comprehension and picking out vowels) and compared it to its single task components (reading or vowel pick-out alone). Behavioral performance of the KPT degraded compared to its single task components. Performance of the KPT markedly increased BOLD signal intensity in the PFC, and also activated sensorimotor, parietal association, and visual cortex areas. In conjunction analyses, bilateral BOLD signal in the dorsolateral PFC (Brodmann's areas 45, 46) was present only in the KPT. Our results support the central bottleneck theory and suggest that the dorsolateral PFC is an important mediator of neural activity for both short-term storage and executive processes. Quantitative evaluation of the KPT with fMRI in healthy adults is the first step towards understanding the effects of aging or cognitive impairment on KPT performance.

  2. Gender differences in regional cerebral activity during the perception of emotion: a functional MRI study.

    Science.gov (United States)

    Hofer, Alex; Siedentopf, Christian M; Ischebeck, Anja; Rettenbacher, Maria A; Verius, Michael; Felber, Stephan; Fleischhacker, W Wolfgang

    2006-08-15

    Whether men activate different brain regions during various emotions compared to women or whether gender differences exist in transient emotional states has been the subject of only few studies. We used event-related functional magnetic resonance imaging (fMRI) to investigate gender differences during the perception of positive or negative emotions. The experiment comprised two emotional conditions (pleasant/unpleasant visual stimuli) during which fMRI data were acquired. Altogether, 38 healthy volunteers (19 males, 19 females) were investigated. When subtracting the activation values of men from those of women, suprathreshold positive signal changes were detected in the right posterior cingulate, the left putamen and the left cerebellum during positive mood induction, and in bilateral superior temporal gyri and cerebellar vermis during negative mood induction. The subtraction of activation values of women from those of men yielded no significant differences. Our findings suggest gender-related neural responses to emotional stimuli and could contribute to the understanding of mechanisms underlying gender-related vulnerability of the prevalence and severity of neuropsychiatric disorders.

  3. Symmetry of fMRI activation in the primary sensorimotor cortex during unilateral chewing.

    Science.gov (United States)

    Lotze, M; Domin, M; Kordass, B

    2017-05-01

    Functional magnetic resonance imaging (fMRI) is one of the most advanced techniques to analyze the cerebral effects on many behavior aspects of the oral system such as chewing and mastication. Studies on imaging of the cerebral representation of chewing demonstrated differential results with respect to cortical lateralization during unilateral chewing. The aim of our study is to clarify the effects of cerebral responses during unilateral chewing. We used fMRI to compare brain activities during occlusal function in centric occlusion on natural teeth and chewing on a gum located on the right or the left teeth in 15 healthy subjects. Group data were performed by Talairach normalization and in addition by an assignment of activation maxima to individual anatomical landmarks in order to avoid possible loss of spatial preciseness of activation sites by normalization procedures. Evaluation of group data by Talairach normalization revealed representation sites for occlusal movements in bilateral primary (S1) and secondary (S2) somatosensory cortices, primary motor (M1) and premotor cortices, supplementary motor area (SMA) and medial cingulate gyrus, bilateral anterior cerebellar hemispheres and vermis, insula, orbitofrontal cortex, thalamus, and left pallidum. Right-sided chewing showed no differential activation to left-sided chewing, and both showed activation in areas also involved in bilateral occlusion. Both techniques, the one based on group normalization and the one based on an individual evaluation method, revealed remarkable low differences in activation maximum location in the primary motor, the primary and secondary somatosensory cortices, and the anterior cerebellar lobe. All chewing movements tested involved bilateral sensorimotor activation without a significant lateralization of activation intensities. Overall, a general lateralization of occlusion movements to the dominant side could not be verified in the present study. Chewing on the left or on the right

  4. Tetherless near-infrared control of brain activity in behaving animals using fully implantable upconversion microdevices.

    Science.gov (United States)

    Wang, Ying; Lin, Xudong; Chen, Xi; Chen, Xian; Xu, Zhen; Zhang, Wenchong; Liao, Qinghai; Duan, Xin; Wang, Xin; Liu, Ming; Wang, Feng; He, Jufang; Shi, Peng

    2017-10-01

    Many nanomaterials can be used as sensors or transducers in biomedical research and they form the essential components of transformative novel biotechnologies. In this study, we present an all-optical method for tetherless remote control of neural activity using fully implantable micro-devices based on upconversion technology. Upconversion nanoparticles (UCNPs) were used as transducers to convert near-infrared (NIR) energy to visible light in order to stimulate neurons expressing different opsin proteins. In our setup, UCNPs were packaged in a glass micro-optrode to form an implantable device with superb long-term biocompatibility. We showed that remotely applied NIR illumination is able to reliably trigger spiking activity in rat brains. In combination with a robotic laser projection system, the upconversion-based tetherless neural stimulation technique was implemented to modulate brain activity in various regions, including the striatum, ventral tegmental area, and visual cortex. Using this system, we were able to achieve behavioral conditioning in freely moving animals. Notably, our microscale device was at least one order of magnitude smaller in size (∼100 μm in diameter) and two orders of magnitude lighter in weight (less than 1 mg) than existing wireless optogenetic devices based on light-emitting diodes. This feature allows simultaneous implantation of multiple UCNP-optrodes to achieve modulation of brain function to control complex animal behavior. We believe that this technology not only represents a novel practical application of upconversion nanomaterials, but also opens up new possibilities for remote control of neural activity in the brains of behaving animals. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Cobalt Alloy Implant Debris Induces Inflammation and Bone Loss Primarily through Danger Signaling, Not TLR4 Activation: Implications for DAMP-ening Implant Related Inflammation.

    Directory of Open Access Journals (Sweden)

    Lauryn Samelko

    Full Text Available Cobalt alloy debris has been implicated as causative in the early failure of some designs of current total joint implants. The ability of implant debris to cause excessive inflammation via danger signaling (NLRP3 inflammasome vs. pathogen associated pattern recognition receptors (e.g. Toll-like receptors; TLRs remains controversial. Recently, specific non-conserved histidines on human TLR4 have been shown activated by cobalt and nickel ions in solution. However, whether this TLR activation is directly or indirectly an effect of metals or secondary endogenous alarmins (danger-associated molecular patterns, DAMPs elicited by danger signaling, remains unknown and contentious. Our study indicates that in both a human macrophage cell line (THP-1 and primary human macrophages, as well as an in vivo murine model of inflammatory osteolysis, that Cobalt-alloy particle induced NLRP3 inflammasome danger signaling inflammatory responses were highly dominant relative to TLR4 activation, as measured respectively by IL-1β or TNF-α, IL-6, IL-10, tissue histology and quantitative bone loss measurement. Despite the lack of metal binding histidines H456 and H458 in murine TLR4, murine calvaria challenge with Cobalt alloy particles induced significant macrophage driven in vivo inflammation and bone loss inflammatory osteolysis, whereas LPS calvaria challenge alone did not. Additionally, no significant increase (p500pg/mL. Therefore, not only do the results of this investigation support Cobalt alloy danger signaling induced inflammation, but under normal homeostasis low levels of hematogenous PAMPs (<2pg/mL from Gram-negative bacteria, seem to have negligible contribution to the danger signaling responses elicited by Cobalt alloy metal implant debris. This suggests the unique nature of Cobalt alloy particle bioreactivity is strong enough to illicit danger signaling that secondarily activate concomitant TLR activation, and may in part explain Cobalt particulate

  6. Cobalt Alloy Implant Debris Induces Inflammation and Bone Loss Primarily through Danger Signaling, Not TLR4 Activation: Implications for DAMP-ening Implant Related Inflammation

    Science.gov (United States)

    Samelko, Lauryn; Landgraeber, Stefan; McAllister, Kyron; Jacobs, Joshua; Hallab, Nadim James

    2016-01-01

    Cobalt alloy debris has been implicated as causative in the early failure of some designs of current total joint implants. The ability of implant debris to cause excessive inflammation via danger signaling (NLRP3 inflammasome) vs. pathogen associated pattern recognition receptors (e.g. Toll-like receptors; TLRs) remains controversial. Recently, specific non-conserved histidines on human TLR4 have been shown activated by cobalt and nickel ions in solution. However, whether this TLR activation is directly or indirectly an effect of metals or secondary endogenous alarmins (danger-associated molecular patterns, DAMPs) elicited by danger signaling, remains unknown and contentious. Our study indicates that in both a human macrophage cell line (THP-1) and primary human macrophages, as well as an in vivo murine model of inflammatory osteolysis, that Cobalt-alloy particle induced NLRP3 inflammasome danger signaling inflammatory responses were highly dominant relative to TLR4 activation, as measured respectively by IL-1β or TNF-α, IL-6, IL-10, tissue histology and quantitative bone loss measurement. Despite the lack of metal binding histidines H456 and H458 in murine TLR4, murine calvaria challenge with Cobalt alloy particles induced significant macrophage driven in vivo inflammation and bone loss inflammatory osteolysis, whereas LPS calvaria challenge alone did not. Additionally, no significant increase (p500pg/mL). Therefore, not only do the results of this investigation support Cobalt alloy danger signaling induced inflammation, but under normal homeostasis low levels of hematogenous PAMPs (<2pg/mL) from Gram-negative bacteria, seem to have negligible contribution to the danger signaling responses elicited by Cobalt alloy metal implant debris. This suggests the unique nature of Cobalt alloy particle bioreactivity is strong enough to illicit danger signaling that secondarily activate concomitant TLR activation, and may in part explain Cobalt particulate associated

  7. Comparison of semantic and episodic memory BOLD fMRI activation in predicting cognitive decline in older adults.

    Science.gov (United States)

    Hantke, Nathan; Nielson, Kristy A; Woodard, John L; Breting, Leslie M Guidotti; Butts, Alissa; Seidenberg, Michael; Carson Smith, J; Durgerian, Sally; Lancaster, Melissa; Matthews, Monica; Sugarman, Michael A; Rao, Stephen M

    2013-01-01

    Previous studies suggest that task-activated functional magnetic resonance imaging (fMRI) can predict future cognitive decline among healthy older adults. The present fMRI study examined the relative sensitivity of semantic memory (SM) versus episodic memory (EM) activation tasks for predicting cognitive decline. Seventy-eight cognitively intact elders underwent neuropsychological testing at entry and after an 18-month interval, with participants classified as cognitively "Stable" or "Declining" based on ≥ 1.0 SD decline in performance. Baseline fMRI scanning involved SM (famous name discrimination) and EM (name recognition) tasks. SM and EM fMRI activation, along with Apolipoprotein E (APOE) ε4 status, served as predictors of cognitive outcome using a logistic regression analysis. Twenty-seven (34.6%) participants were classified as Declining and 51 (65.4%) as Stable. APOE ε4 status alone significantly predicted cognitive decline (R(2) = .106; C index = .642). Addition of SM activation significantly improved prediction accuracy (R(2) = .285; C index = .787), whereas the addition of EM did not (R(2) = .212; C index = .711). In combination with APOE status, SM task activation predicts future cognitive decline better than EM activation. These results have implications for use of fMRI in prevention clinical trials involving the identification of persons at-risk for age-associated memory loss and Alzheimer's disease.

  8. Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

    Energy Technology Data Exchange (ETDEWEB)

    Li, Fan, E-mail: f.li.1@warwick.ac.uk [School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom); Sharma, Yogesh; Shah, Vishal; Jennings, Mike [School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom); Pérez-Tomás, Amador [ICN2 – Institut Catala de Nanociència i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona (Spain); Myronov, Maksym [Physics Department, University of Warwick, Coventry CV4 7AL (United Kingdom); Fisher, Craig [School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom); Leadley, David [Physics Department, University of Warwick, Coventry CV4 7AL (United Kingdom); Mawby, Phil [School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2015-10-30

    Highlights: • Nitrogen is fully activated by 1175 °C annealing for 1.5 × 10{sup 19} cm{sup −3} doped 3C-SiC. • Free donor concentration is found to readily saturate in 3C-SiC at ∼7 × 10{sup 19} cm{sup −3}. • 3C-SiC is found to have complete donor thermal ionization above 150 K. • Donor in 1.5 × 10{sup 19} cm{sup −3} nitrogen implanted 3C-SiC has an energy level ∼15 meV. • The SiO{sub 2} cap is found to have a bigger influence on low and medium doped samples. - Abstract: A degenerated wide bandgap semiconductor is a rare system. In general, implant levels lie deeper in the band-gap and carrier freeze-out usually takes place at room temperature. Nevertheless, we have observed that heavily doped n-type degenerated 3C-SiC films are achieved by nitrogen implantation level of ∼6 × 10{sup 20} cm{sup −3} at 20 K. According to temperature dependent Hall measurements, nitrogen activation rates decrease with the doping level from almost 100% (1.5 × 10{sup 19} cm{sup −3}, donor level 15 meV) to ∼12% for 6 × 10{sup 20} cm{sup −3}. Free donors are found to saturate in 3C-SiC at ∼7 × 10{sup 19} cm{sup −3}. The implanted film electrical performances are characterized as a function of the dopant doses and post implantation annealing (PIA) conditions by fabricating Van der Pauw structures. A deposited SiO{sub 2} layer was used as the surface capping layer during the PIA process to study its effect on the resultant film properties. From the device design point of view, the lowest sheet resistivity (∼1.4 mΩ cm) has been observed for medium doped (4 × 10{sup 19} cm{sup −3}) sample with PIA 1375 °C 2 h without a SiO{sub 2} cap.

  9. Effects of V4c-ICL Implantation on Myopic Patients’ Vision-Related Daily Activities

    Directory of Open Access Journals (Sweden)

    Taixiang Liu

    2016-01-01

    Full Text Available The new type implantable Collamer lens with a central hole (V4c-ICL is widely used to treat myopia. However, halos occur in some patients after surgery. The aim is to evaluate the effect of V4c-ICL implantation on vision-related daily activities. This retrospective study included 42 patients. Uncorrected visual acuity (UCVA, best corrected visual acuity (BCVA, intraocular pressure (IOP, endothelial cell density (ECD, and vault were recorded and vision-related daily activities were evaluated at 3 months after operation. The average spherical equivalent was -0.12±0.33 D at 3 months after operation. UCVA equal to or better than preoperative BCVA occurred in 98% of eyes. The average BCVA at 3 months after operation was -0.03±0.07 LogMAR, which was significantly better than preoperative BCVA (0.08±0.10 LogMAR (P=0.029. Apart from one patient (2.4% who had difficulty reading computer screens, all patients had satisfactory or very satisfactory results. During the early postoperation, halos occurred in 23 patients (54.8%. However there were no significant differences in the scores of visual functions between patients with and without halos (P>0.05. Patients were very satisfied with their vision-related daily activities at 3 months after operation. The central hole of V4c-ICL does not affect patients’ vision-related daily activities.

  10. Posterior midline activation during symptom provocation in acute stress disorder: An fMRI study

    Directory of Open Access Journals (Sweden)

    Jan Christopher Cwik

    2014-05-01

    Full Text Available Functional imaging studies of patients with Posttraumatic Stress Disorder showed wide-spread activation of mid-line cortical areas during symptom provocation i.e., exposure to trauma-related cues. The present study aimed at investigating neural activation during exposure to trauma-related pictures in patients with Acute Stress Disorder (ASD shortly after the traumatic event. Nineteen ASD patients and 19 healthy control participants were presented with individualized pictures of the traumatic event and emotionally neutral control pictures during the acquisition of whole-brain data with a 3-T fMRI scanner. Compared to the control group and to control pictures, ASD patients showed significant activation in mid-line cortical areas in response to trauma-related pictures including precuneus, cuneus, postcentral gyrus and pre-supplementary motor area. The results suggest that the trauma-related pictures evoke emotionally salient self-referential processing in ASD patients.

  11. Ultra-sensitive molecular MRI of cerebrovascular cell activation enables early detection of chronic central nervous system disorders

    International Nuclear Information System (INIS)

    Montagne, Axel; Gauberti, Maxime; Jullienne, Amandine; Briens, Aurelien; Docagne, Fabian; Vivien, Denis; Maubert, Eric; Macrez, Richard; Defer, Gilles; Raynaud, Jean-Sebastien; Louin, Gaelle; Buisson, Alain; Haelewyn, Benoit

    2012-01-01

    Since endothelial cells can be targeted by large contrast-carrying particles, molecular imaging of cerebrovascular cell activation is highly promising to evaluate the underlying inflammation of the central nervous system (CNS). In this study, we aimed to demonstrate that molecular magnetic resonance imaging (MRI) of cerebrovascular cell activation can reveal CNS disorders in the absence of visible lesions and symptoms. To this aim, we optimized contrast carrying particles targeting vascular cell adhesion molecule-1 and MRI protocols through both in vitro and in vivo experiments. Although, pre-contrast MRI images failed to reveal the ongoing pathology, contrast-enhanced MRI revealed hypoperfusion-triggered CNS injury in vascular dementia, unmasked amyloid-induced cerebrovascular activation in Alzheimer's disease and allowed monitoring of disease activity during experimental autoimmune encephalomyelitis. Moreover, contrast-enhanced MRI revealed the cerebrovascular cell activation associated with known risk factors of CNS disorders such as peripheral inflammation, ethanol consumption, hyperglycemia and aging. By providing a dramatically higher sensitivity than previously reported methods and molecular contrast agents, the technology described in the present study opens new avenues of investigation in the field of neuro-inflammation. (authors)

  12. Flow velocity change in the cortical vein during motor activation and its effect on functional brain MRI

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Kazuhiro [Kyoto Prefectural Univ. of Medicine (Japan)

    1998-06-01

    On the brain functional magnetic resonance imaging (fMRI) using the gradient-recalled echo technique with clinical MR scanner, the activated areas nearly correspond with the cortical veins. This suggests that the fMRI signal mainly originates from the cortical veins. In this study, we analyzed the flow velocity in the cortical vein quantitatively during brain activation and resting status using 2 dimensional time-of-flight cine MR venography (2D-TOF-cine-MRV) and 2 dimensional phase contrast MRV (2D-PC-MRV) techniques, and demonstrated that the flow velocity increased in the cortical vein corresponding to the activated area during activation status. The increase of flow velocity was calculated to be about 20%. The reason for the increased flow velocity is probably due to the increased regional cerebral blood flow and volume in the activated area. We should be careful to analyze the data of the fMRI because the flow velocity affects the fMRI signal such as the inflow effect and the oblique flow effect. When using the gradient echo method, the effect of the flow velocity is one of the important factors of the fMRI signal. (author)

  13. Grading of Crohn's disease activity using CT, MRI, US and scintigraphy: a meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Puylaert, C.A.J.; Tielbeek, J.A.W.; Bipat, S.; Stoker, J. [University of Amsterdam, Academic Medical Center, Department of Radiology, Amsterdam (Netherlands)

    2015-11-15

    To assess the grading of Crohn's disease activity using CT, MRI, US and scintigraphy. MEDLINE, EMBASE and Cochrane databases were searched (January 1983-March 2014) for studies evaluating CT, MRI, US and scintigraphy in grading Crohn's disease activity compared to endoscopy, biopsies or intraoperative findings. Two independent reviewers assessed the data. Three-by-three tables (none, mild, frank disease) were constructed for all studies, and estimates of accurate, over- and under-grading were calculated/summarized by fixed or random effects models. Our search yielded 9356 articles, 19 of which were included. Per-patient data showed accurate grading values for CT, MRI, US and scintigraphy of 86 % (95 % CI: 75-93 %), 84 % (95 % CI: 67-93 %), 44 % (95 % CI: 28-61 %) and 40 % (95 % CI: 16-70 %), respectively. In the per-patient analysis, CT and MRI showed similar accurate grading estimates (P = 0.8). Per-segment data showed accurate grading values for CT and scintigraphy of 87 % (95 % CI: 77-93 %) and 86 % (95 % CI: 80-91 %), respectively. MRI and US showed grading accuracies of 67-82 % and 56-75 %, respectively. CT and MRI showed comparable high accurate grading estimates in the per-patient analysis. Results for US and scintigraphy were inconsistent, and limited data were available. (orig.)

  14. Neural Changes following Behavioral Activation for a Depressed Breast Cancer Patient: A Functional MRI Case Study

    Directory of Open Access Journals (Sweden)

    Michael J. Gawrysiak

    2012-01-01

    Full Text Available Functional neuroimaging is an innovative but at this stage underutilized method to assess the efficacy of psychotherapy for depression. Functional magnetic resonance imaging (fMRI was used in this case study to examine changes in brain activity in a depressed breast cancer patient receiving an 8-session Behavioral Activation Treatment for Depression (BATD, based on the work of Hopko and Lejuez (2007. A music listening paradigm was used during fMRI brain scans to assess reward responsiveness at pre- and posttreatment. Following treatment, the patient exhibited attenuated depression and changes in blood oxygenation level dependence (BOLD response in regions of the prefrontal cortex and the subgenual cingulate cortex. These preliminary findings outline a novel means to assess psychotherapy efficacy and suggest that BATD elicits functional brain changes in areas implicated in the pathophysiology of depression. Further research is necessary to explore neurobiological mechanisms of change in BATD, particularly the potential mediating effects of reward responsiveness and associated brain functioning.

  15. Magnetic Resonance Imaging (MRI) -- Head

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    Full Text Available ... a risk, depending on their nature and the strength of the MRI magnet. Many implanted devices will ... full size with caption Pediatric Content Some imaging tests and treatments have special pediatric considerations. The teddy ...

  16. Magnetic Resonance Imaging (MRI) -- Head

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    Full Text Available ... it may cause some medical devices to malfunction. Most orthopedic implants pose no risk, but you should ... a digital cloud server. Currently, MRI is the most sensitive imaging test of the head (particularly the ...

  17. Magnetic Resonance Imaging (MRI) -- Head

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    Full Text Available ... is not harmful, but it may cause some medical devices to malfunction. Most orthopedic implants pose no ... Head? Magnetic resonance imaging (MRI) is a noninvasive medical test that physicians use to diagnose medical conditions. ...

  18. Magnetic Resonance Imaging (MRI) -- Head

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    Full Text Available ... contrast for an MRI. If you have a history of kidney disease or liver transplant, it will ... are not limited to: artificial heart valves implanted drug infusion ports artificial limbs or metallic joint prostheses ...

  19. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... their nature and the strength of the MRI magnet. Many implanted devices will have a pamphlet explaining ... large cylinder-shaped tube surrounded by a circular magnet. You will lie on a moveable examination table ...

  20. MRI abnormalities of foot and ankle in asymptomatic, physically active individuals

    International Nuclear Information System (INIS)

    Lohman, M.; Kivisaari, A.; Kivisaari, L.; Kallio, P.

    2001-01-01

    Objective. To assess MRI changes in the ankle and foot after physical exercise.Design and patients. Nineteen non-professional marathon runners and 19 age- and sex-matched controls volunteered for the study. All had ankle and foot MR images (1.5 T) taken in three perpendicular planes (STIR, T2F and T1FS sequences) within 3 h of running a full-length marathon (42.125 km). Three radiologists independently analysed the groups on a masked basis using a predefined form.Results. Severe bone marrow oedema was seen in one and slight bone marrow oedema in three marathon runners. Slight bone marrow oedema was found in three control subjects. Signal alteration within the soleus muscle, consistent with a grade 1 strain, was found in one marathon runner. Small punctate hyperintensities within the Achilles tendon were seen in 26% of the marathon runners and in 63% of controls (P=0.016). An increased amount of fluid in the retrocalcaneal bursa was found in one control and in none of the marathon runners. Small amounts of fluid in the retrocalcaneal bursa were seen in 68% of marathon runners and in 53% of controls. Grade 1 or 2 peritendinous joint fluid was found around 22% of tendons, among both marathon runners and controls, most often involving the tendon sheath of the flexor hallucis longus muscle. An increased amount of joint fluid was noted in 34% of the joints of the marathon runners, and in 18% of the controls.Conclusion. MRI shows several abnormalities in the ankle and foot both after marathon races and in asymptomatic physically active individuals without any preceding extraordinary strain. Recreational sports may lead to a number of positive MRI findings without correlation with clinical findings. (orig.)

  1. fMRI and brain activation after sport concussion: a tale of two cases

    Directory of Open Access Journals (Sweden)

    Michael G Hutchison

    2014-04-01

    Full Text Available Sport-related concussions are now recognized as a major public health concern: The number of participants in sport and recreation is growing, possibly playing their games faster, and there is heightened public awareness of injuries to some high-profile athletes. However, many clinicians still rely on subjective symptom reports for the clinical determination of recovery. Relying on subjective symptom reports can be dangerous, as it has been shown that some concussed athletes may downplay their symptoms. The use of neuropsychological (NP testing tools has enabled clinicians to measure the effects and extent of impairment following concussion more precisely, providing more objective metrics for determining recovery after concussion. Nevertheless, there is a remaining concern that brain abnormalities may exist beyond the point at which individuals achieve recovery in self-reported symptoms and cognition measured by NP testing. Our understanding of brain recovery after concussion is important not only from a neuroscience perspective, but also from the perspective of clinical decision making for safe return-to-play (RTP. A number of advanced neuroimaging tools, including blood oxygen level dependent (BOLD functional magnetic resonance imaging (fMRI, have independently yielded early information on these abnormal brain functions. In the two cases presented in this article, we report contrasting brain activation patterns and recovery profiles using fMRI. Importantly, fMRI was conducted using adapted versions of the most sensitive computerized NP tests administered in current clinical practice to determine impairments and recovery after sport-related concussion. One of the cases is consistent with the concept of lagging brain recovery.

  2. Characterization of functional brain activity and connectivity using EEG and fMRI in patients with sickle cell disease.

    Science.gov (United States)

    Case, Michelle; Zhang, Huishi; Mundahl, John; Datta, Yvonne; Nelson, Stephen; Gupta, Kalpna; He, Bin

    2017-01-01

    Sickle cell disease (SCD) is a red blood cell disorder that causes many complications including life-long pain. Treatment of pain remains challenging due to a poor understanding of the mechanisms and limitations to characterize and quantify pain. In the present study, we examined simultaneously recording functional MRI (fMRI) and electroencephalogram (EEG) to better understand neural connectivity as a consequence of chronic pain in SCD patients. We performed independent component analysis and seed-based connectivity on fMRI data. Spontaneous power and microstate analysis was performed on EEG-fMRI data. ICA analysis showed that patients lacked activity in the default mode network (DMN) and executive control network compared to controls. EEG-fMRI data revealed that the insula cortex's role in salience increases with age in patients. EEG microstate analysis showed patients had increased activity in pain processing regions. The cerebellum in patients showed a stronger connection to the periaqueductal gray matter (involved in pain inhibition), and negative connections to pain processing areas. These results suggest that patients have reduced activity of DMN and increased activity in pain processing regions during rest. The present findings suggest resting state connectivity differences between patients and controls can be used as novel biomarkers of SCD pain.

  3. Functional MRI activation of somatosensory and motor cortices in a hand-grafted patient with early clinical sensorimotor recovery

    International Nuclear Information System (INIS)

    Neugroschl, C.; Denolin, V.; Schuind, F.; Holder, C. van; David, P.; Baleriaux, D.; Metens, T.

    2005-01-01

    The aim of this study was to investigate somatosensory and motor cortical activity with functional MRI (fMRI) in a hand-grafted patient with early clinical recovery. The patient had motor fMRI examinations before transplantation, and motor and passive tactile stimulations after surgery. His normal hand and a normal group were studied for comparison. A patient with complete brachial plexus palsy was studied to assess the lack of a fMRI signal in somatosensory areas in the case of total axonal disconnection. Stimulating the grafted hand revealed significant activation in the contralateral somatosensory cortical areas in all fMRI examinations. The activation was seen as early as 10 days after surgery; this effect cannot be explained by the known physiological mechanisms of nerve regeneration. Although an imagination effect cannot be excluded, the objective clinical recovery of sensory function led us to formulate the hypothesis that a connection to the somatosensory cortex was rapidly established. Additional cases and fundamental studies are needed to assess this hypothesis, but several observations were compatible with this explanation. Before surgery, imaginary motion of the amputated hand produced less intense responses than executed movements of the intact hand, whereas the normal activation pattern for right-handed subjects was found after surgery, in agreement with the good clinical motor recovery. (orig.)

  4. 3D perfusion bioreactor-activated porous granules on implant fixation and early bone formation in sheep.

    Science.gov (United States)

    Ding, Ming; Henriksen, Susan S; Martinetti, Roberta; Overgaard, Søren

    2017-11-01

    Early fixation of total joint arthroplasties is crucial for ensuring implant survival. An alternative bone graft material in revision surgery is needed to replace the current gold standard, allograft, seeing that the latter is associated with several disadvantages. The incubation of such a construct in a perfusion bioreactor has been shown to produce viable bone graft materials. This study aimed at producing larger amounts of viable bone graft material (hydroxyapatite 70% and β-tricalcium-phosphate 30%) in a novel perfusion bioreactor. The abilities of the bioreactor-activated graft material to induce early implant fixation were tested in a bilateral implant defect model in sheep, with allograft as the control group. Defects were bilaterally created in the distal femurs of the animals, and titanium implants were inserted. The concentric gaps around the implants were randomly filled with either allograft, granules, granules with bone marrow aspirate or bioreactor-activated graft material. Following an observation time of 6 weeks, early implant fixation and bone formation were assessed by micro-CT scanning, mechanical testing, and histomorphometry. Bone formations were seen in all groups, while no significant differences between groups were found regarding early implant fixation. The microarchitecture of the bone formed by the synthetic graft materials resembled that of allograft. Histomorphometry revealed that allograft induced significantly more bone and less fibrous tissue (p formation was observed in all groups, while the bioreactor-activated graft material did not reveal additional effects on early implant fixation comparable to allograft in this model. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2465-2476, 2017. © 2016 Wiley Periodicals, Inc.

  5. Magnetic resonance imaging investigation of the bone conduction implant – a pilot study at 1.5 Tesla

    Directory of Open Access Journals (Sweden)

    Fredén Jansson KJ

    2015-10-01

    Full Text Available Karl-Johan Fredén Jansson,1 Bo Håkansson,1 Sabine Reinfeldt,1 Cristina Rigato,1 Måns Eeg-Olofsson2 1Department of Signals and Systems, Chalmers University of Technology, 2Deptartment of Otorhinolaryngology Head and Neck Surgery, Sahlgrenska University Hospital, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Purpose: The objective of this pilot study was to investigate if an active bone conduction implant (BCI used in an ongoing clinical study withstands magnetic resonance imaging (MRI of 1.5 Tesla. In particular, the MRI effects on maximum power output (MPO, total harmonic distortion (THD, and demagnetization were investigated. Implant activation and image artifacts were also evaluated.Methods and materials: One implant was placed on the head of a test person at the position corresponding to the normal position of an implanted BCI and applied with a static pressure using a bandage and scanned in a 1.5 Tesla MRI camera. Scanning was performed both with and without the implant, in three orthogonal planes, and for one spin-echo and one gradient-echo pulse sequence. Implant functionality was verified in-between the scans using an audio processor programmed to generate a sequence of tones when attached to the implant. Objective verification was also carried out by measuring MPO and THD on a skull simulator as well as retention force, before and after MRI.Results: It was found that the exposure of 1.5 Tesla MRI only had a minor effect on the MPO, ie, it decreased over all frequencies with an average of 1.1±2.1 dB. The THD remained unchanged above 300 Hz and was increased only at lower frequencies. The retention magnet was demagnetized by 5%. The maximum image artifacts reached a distance of 9 and 10 cm from the implant in the coronal plane for the spin-echo and the gradient-echo sequence, respectively. The test person reported no MRI induced sound from the implant.Conclusion: This pilot study indicates that the present BCI

  6. Estimation of brain activation in response to major and minor scales by fMRI

    International Nuclear Information System (INIS)

    Fujimaki, Takuya; Nemoto, Iku

    2011-01-01

    We made fMRI measurements of the brain responses to major and minor scales which are the fundamental elements for making melodies in music. In addition, we used an arpeggio of diminished 7th. For a control stimulus, we provided a sequence of repeated single tones. The ascending scales of 12 major and 12 minor keys were made starting from F no.3 to F4. Each scale was 3 s in duration. A 3 s scan was performed 2-3 s (randomized) after a scale has been finished and repeated every 14 s (sparse time scanning). Typically, major scales activated the left inferior frontal gyrus, minor scales the posterior cingulate gyrus and the diminished arpeggio the left auditory cortex. In general, the left hemisphere was more activated than usually seen in responses to music. (author)

  7. [Local brain activity in different motor subtypes of Parkinson's disease with fMRI].

    Science.gov (United States)

    Hou, Ya'nan; Zhang, Jiarong; Chen, Biao; Wu, Tao

    2015-02-17

    To explore the changes of local brain activity in motor subtypes of Parkinson's disease (PD) with functional magnetic resonance imaging (fMRI). A total of 60 idiopathic PD and 30 age- and gender-matched normal controls were examined with resting-state fMRI from January 2013 to March 2014. All subjects gave their written informed consent for the study. The amplitude of low-frequency fluctuation (ALFF) was calculated to measure local brain activity. The PD patients were divided into two groups of tremor dominant (TD) and postural instability/gait difficulty (PIGD) (n = 30 each). All subjects gave their written in formed consent for the study.One-way ANOVA and post-hoc t-test were performed to detect the differences of local brain activity between PD and normal subjects. And the correlations were examined between ALFF, scores and levodopa dose. Compared with normal subjects, the TD group showed increased activity in bilateral cerebellums (-37, -47, -38), thalamus (-18, -17,0), pons (-3, -23, -37) and left precentral gyrus (-41, -30, 46) versus decreased activity in bilateral frontal lobes (-13, 69, 6), temporal lobes (-42, 18, -21), left insula (-32, 22, 2) and left anterior cingulated (-7, 32, -5). The PIGD group showed increased activity in right postcentral gyrus (63, -18, 39) and decreased activity in bilateral putamens (-24, 12, 3), pre-supplementary motor area (10, 10, 58), frontal lobes (15, -15, 57), temporal lobes (-39, 18, -3) and left insula (-29, 20, 11). Compared with PIGD, the TD group showed increased activity in temporal lobes, but decreased activity in frontal lobes. Additionally, ALFF in bilateral cerebellums and frontal lobes was positively correlated with TD scores while ALFF in left precentral gyrus, bilateral putamens and temporal lobes negatively correlated with TD scores. ALFF in bilateral frontal lobes and left temporal lobe was positively correlated with PIGD scores.However, in right postcentral gyrus and bilateral putamens, ALFF was

  8. Increase in MST activity correlates with visual motion learning: A functional MRI study of perceptual learning.

    Science.gov (United States)

    Larcombe, Stephanie J; Kennard, Chris; Bridge, Holly

    2018-01-01

    Repeated practice of a specific task can improve visual performance, but the neural mechanisms underlying this improvement in performance are not yet well understood. Here we trained healthy participants on a visual motion task daily for 5 days in one visual hemifield. Before and after training, we used functional magnetic resonance imaging (fMRI) to measure the change in neural activity. We also imaged a control group of participants on two occasions who did not receive any task training. While in the MRI scanner, all participants completed the motion task in the trained and untrained visual hemifields separately. Following training, participants improved their ability to discriminate motion direction in the trained hemifield and, to a lesser extent, in the untrained hemifield. The amount of task learning correlated positively with the change in activity in the medial superior temporal (MST) area. MST is the anterior portion of the human motion complex (hMT+). MST changes were localized to the hemisphere contralateral to the region of the visual field, where perceptual training was delivered. Visual areas V2 and V3a showed an increase in activity between the first and second scan in the training group, but this was not correlated with performance. The contralateral anterior hippocampus and bilateral dorsolateral prefrontal cortex (DLPFC) and frontal pole showed changes in neural activity that also correlated with the amount of task learning. These findings emphasize the importance of MST in perceptual learning of a visual motion task. Hum Brain Mapp 39:145-156, 2018. © 2017 Wiley Periodicals, Inc. © 2017 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

  9. Comparative silicone breast implant evaluation using mammography, sonography, and magnetic resonance imaging: experience with 59 implants.

    Science.gov (United States)

    Ahn, C Y; DeBruhl, N D; Gorczyca, D P; Shaw, W W; Bassett, L W

    1994-10-01

    With the current controversy regarding the safety of silicone implants, the detection and evaluation of implant rupture are causing concern for both plastic surgeons and patients. Our study obtained comparative value analysis of mammography, sonography, and magnetic resonance imaging (MRI) in the detection of silicone implant rupture. Twenty-nine symptomatic patients (total of 59 silicone implants) were entered into the study. Intraoperative findings revealed 21 ruptured implants (36 percent). During physical examination, a positive "squeeze test" was highly suggestive of implant rupture. Mammograms were obtained of 51 implants (sensitivity 11 percent, specificity 89 percent). Sonography was performed on 57 implants (sensitivity 70 percent, specificity 92 percent). MRI was performed on 55 implants (sensitivity 81 percent, specificity 92 percent). Sonographically, implant rupture is demonstrated by the "stepladder sign." Double-lumen implants may appear as false-positive results for rupture on sonography. On MRI, the "linguine sign" represents disrupted fragments of a ruptured implant. The most reliable imaging modality for implant rupture detection is MRI, followed by sonogram. Mammogram is the least reliable. Our study supports the clinical indication and diagnostic value of sonogram and MRI in the evaluation of symptomatic breast implant patients.

  10. Attention and amygdala activity: an fMRI study with spider pictures in spider phobia.

    Science.gov (United States)

    Alpers, Georg W; Gerdes, Antje B M; Lagarie, Bernadette; Tabbert, Katharina; Vaitl, Dieter; Stark, Rudolf

    2009-06-01

    Facilitated detection of threatening visual cues is thought to be adaptive. In theory, detection of threat cues should activate the amygdala independently from allocation of attention. However, previous studies using emotional facial expressions as well as phobic cues yielded contradictory results. We used fMRI to examine whether the allocation of attention to components of superimposed spider and bird displays modulates amygdala activation. Nineteen spider-phobic women were instructed to identify either a moving or a stationary animal in briefly presented double-exposure displays. Amygdala activation followed a dose-response relationship: Compared to congruent neutral displays (two birds), amygdala activation was most pronounced in response to congruent phobic displays (two spiders) and less but still significant in response to mixed displays (spider and bird) when attention was focused on the phobic component. When attention was focused on the neutral component, mixed displays did not result in significant amygdala activation. This was confirmed in a significant parametric graduation of the amygdala activation in the order of congruent phobic displays, mixed displays with attention focus on the spider, mixed displays with focus on the bird and congruent neutral displays. These results challenge the notion that amygdala activation in response to briefly presented phobic cues is independent from attention.

  11. Motor programme activating therapy influences adaptive brain functions in multiple sclerosis: clinical and MRI study.

    Science.gov (United States)

    Rasova, Kamila; Prochazkova, Marie; Tintera, Jaroslav; Ibrahim, Ibrahim; Zimova, Denisa; Stetkarova, Ivana

    2015-03-01

    There is still little scientific evidence for the efficacy of neurofacilitation approaches and their possible influence on brain plasticity and adaptability. In this study, the outcome of a new kind of neurofacilitation approach, motor programme activating therapy (MPAT), was evaluated on the basis of a set of clinical functions and with MRI. Eighteen patients were examined four times with standardized clinical tests and diffusion tensor imaging to monitor changes without therapy, immediately after therapy and 1 month after therapy. Moreover, the strength of effective connectivity was analysed before and after therapy. Patients underwent a 1-h session of MPAT twice a week for 2 months. The data were analysed by nonparametric tests of association and were subsequently statistically evaluated. The therapy led to significant improvement in clinical functions, significant increment of fractional anisotropy and significant decrement of mean diffusivity, and decrement of effective connectivity at supplementary motor areas was observed immediately after the therapy. Changes in clinical functions and diffusion tensor images persisted 1 month after completing the programme. No statistically significant changes in clinical functions and no differences in MRI-diffusion tensor images were observed without physiotherapy. Positive immediate and long-term effects of MPAT on clinical and brain functions, as well as brain microstructure, were confirmed.

  12. Altered default mode network activity in patient with anxiety disorders: An fMRI study

    International Nuclear Information System (INIS)

    Zhao Xiaohu; Wang Peijun; Li Chunbo; Hu Zhenghui; Xi Qian; Wu Wenyuan; Tang Xiaowei

    2007-01-01

    Anxiety disorder, a common mental disorder in our clinical practice, is characterized by unprovoked anxiety. Medial prefrontal cortex (MPFC) and posterior cingulate cortex (PCC), which closely involved in emotional processing, are critical regions in the default mode network. We used functional magnetic resonance imaging (fMRI) to investigate whether default mode network activity is altered in patients with anxiety disorder. Ten anxiety patients and 10 healthy controls underwent fMRI while listening to emotionally neutral words alternating with rest (Experiment 1) and threat-related words alternating with emotionally neutral words (Experiment 2). In Experiment 1, regions of deactivation were observed in patients and controls. In Experiment 2, regions of deactivation were observed only in patients. The observed deactivation patterns in the two experiments, which included MPFC, PCC, and inferior parietal cortex, were similar and consistent with the default model network. Less deactivation in MPFC and greater deactivation in PCC were observed for patients group comparing to controls in Experiment 1. Our observations suggest that the default model network is altered in anxiety patients and dysfunction in MPFC and PCC may play an important role in anxiety psychopathology

  13. High level active n+ doping of strained germanium through co-implantation and nanosecond pulsed laser melting

    Science.gov (United States)

    Pastor, David; Gandhi, Hemi H.; Monmeyran, Corentin P.; Akey, Austin J.; Milazzo, Ruggero; Cai, Yan; Napolitani, Enrico; Gwilliam, Russell M.; Crowe, Iain F.; Michel, Jurgen; Kimerling, L. C.; Agarwal, Anuradha; Mazur, Eric; Aziz, Michael J.

    2018-04-01

    Obtaining high level active n+ carrier concentrations in germanium (Ge) has been a significant challenge for further development of Ge devices. By ion implanting phosphorus (P) and fluorine (F) into Ge and restoring crystallinity using Nd:YAG nanosecond pulsed laser melting (PLM), we demonstrate 1020 cm-3 n+ carrier concentration in tensile-strained epitaxial germanium-on-silicon. Scanning electron microscopy shows that after laser treatment, samples implanted with P have an ablated surface, whereas P + F co-implanted samples have good crystallinity and a smooth surface topography. We characterize P and F concentration depth profiles using secondary ion mass spectrometry and spreading resistance profiling. The peak carrier concentration, 1020 cm-3 at 80 nm below the surface, coincides with the peak F concentration, illustrating the key role of F in increasing donor activation. Cross-sectional transmission electron microscopy of the co-implanted sample shows that the Ge epilayer region damaged during implantation is a single crystal after PLM. High-resolution X-ray diffraction and Raman spectroscopy measurements both indicate that the as-grown epitaxial layer strain is preserved after PLM. These results demonstrate that co-implantation and PLM can achieve the combination of n+ carrier concentration and strain in Ge epilayers necessary for next-generation, high-performance Ge-on-Si devices.

  14. Electro active polymers : novel bio-electrodes and implants for urinary continence

    Energy Technology Data Exchange (ETDEWEB)

    Rajagopalan, S.; Sawan, M.; Savadogo, O. [Ecole Polytechnique, Montreal, PQ (Canada). Laboratoire de nouveaux materiaux pour les systemes electrochimiques et energetiques

    2006-07-01

    This paper presented a technical solution to spinal cord injuries that result in urinary bladder dysfunction. It involves miniaturized implants based on polypyrrole, an electroactive polymer, as smart drug-eluting electrodes for neural stimulation to restore bladder function. The nerve-electrode interface is the most vulnerable point in the design and operation of neuro-electronic implants. The main disadvantages are decreased impedance and protein build-up at the stimulation site due to an inflammatory reaction. Polypyrrole is a naturally conducting polymer having both electron-conducting properties as well as actuating properties, rendering it suitable as a drug-eluting electrode for a neurostimulator. Polypyrrole electrochemically coated on platinum increases biocompatibility and reduces electric impedance by increasing the surface area of the electrode. When electrically stimulated, polypyrrole also serves as a matrix to release a negatively-charged anti-inflammatory drug fosfosal. This technology may prove useful in reconstructing a severely damaged bladder through electroactive biomaterials. Polyelectrolyte gels, such as poly(sodium) acrylate, reversibly contract and relax when activated electrically or under the influx of divalent ions. These artificial muscles can be connected to a polypyrrole strain sensor to alert the microcontroller to activate the sphincter muscle, thereby creating an artificial bladder.

  15. Assessing sensory versus optogenetic network activation by combining (o)fMRI with optical Ca2+ recordings

    Science.gov (United States)

    Schmid, Florian; Wachsmuth, Lydia; Schwalm, Miriam; Prouvot, Pierre-Hugues; Jubal, Eduardo Rosales; Fois, Consuelo; Pramanik, Gautam; Zimmer, Claus; Stroh, Albrecht

    2015-01-01

    Encoding of sensory inputs in the cortex is characterized by sparse neuronal network activation. Optogenetic stimulation has previously been combined with fMRI (ofMRI) to probe functional networks. However, for a quantitative optogenetic probing of sensory-driven sparse network activation, the level of similarity between sensory and optogenetic network activation needs to be explored. Here, we complement ofMRI with optic fiber-based population Ca2+ recordings for a region-specific readout of neuronal spiking activity in rat brain. Comparing Ca2+ responses to the blood oxygenation level-dependent signal upon sensory stimulation with increasing frequencies showed adaptation of Ca2+ transients contrasted by an increase of blood oxygenation level-dependent responses, indicating that the optical recordings convey complementary information on neuronal network activity to the corresponding hemodynamic response. To study the similarity of optogenetic and sensory activation, we quantified the density of cells expressing channelrhodopsin-2 and modeled light propagation in the tissue. We estimated the effectively illuminated volume and numbers of optogenetically stimulated neurons, being indicative of sparse activation. At the functional level, upon either sensory or optogenetic stimulation we detected single-peak short-latency primary Ca2+ responses with similar amplitudes and found that blood oxygenation level-dependent responses showed similar time courses. These data suggest that ofMRI can serve as a representative model for functional brain mapping. PMID:26661247

  16. Assessing sensory versus optogenetic network activation by combining (o)fMRI with optical Ca2+ recordings.

    Science.gov (United States)

    Schmid, Florian; Wachsmuth, Lydia; Schwalm, Miriam; Prouvot, Pierre-Hugues; Jubal, Eduardo Rosales; Fois, Consuelo; Pramanik, Gautam; Zimmer, Claus; Faber, Cornelius; Stroh, Albrecht

    2016-11-01

    Encoding of sensory inputs in the cortex is characterized by sparse neuronal network activation. Optogenetic stimulation has previously been combined with fMRI (ofMRI) to probe functional networks. However, for a quantitative optogenetic probing of sensory-driven sparse network activation, the level of similarity between sensory and optogenetic network activation needs to be explored. Here, we complement ofMRI with optic fiber-based population Ca 2+ recordings for a region-specific readout of neuronal spiking activity in rat brain. Comparing Ca 2+ responses to the blood oxygenation level-dependent signal upon sensory stimulation with increasing frequencies showed adaptation of Ca 2+ transients contrasted by an increase of blood oxygenation level-dependent responses, indicating that the optical recordings convey complementary information on neuronal network activity to the corresponding hemodynamic response. To study the similarity of optogenetic and sensory activation, we quantified the density of cells expressing channelrhodopsin-2 and modeled light propagation in the tissue. We estimated the effectively illuminated volume and numbers of optogenetically stimulated neurons, being indicative of sparse activation. At the functional level, upon either sensory or optogenetic stimulation we detected single-peak short-latency primary Ca 2+ responses with similar amplitudes and found that blood oxygenation level-dependent responses showed similar time courses. These data suggest that ofMRI can serve as a representative model for functional brain mapping. © The Author(s) 2015.

  17. Common brain regions underlying different arithmetic operations as revealed by conjunct fMRI-BOLD activation.

    Science.gov (United States)

    Fehr, Thorsten; Code, Chris; Herrmann, Manfred

    2007-10-03

    The issue of how and where arithmetic operations are represented in the brain has been addressed in numerous studies. Lesion studies suggest that a network of different brain areas are involved in mental calculation. Neuroimaging studies have reported inferior parietal and lateral frontal activations during mental arithmetic using tasks of different complexities and using different operators (addition, subtraction, etc.). Indeed, it has been difficult to compare brain activation across studies because of the variety of different operators and different presentation modalities used. The present experiment examined fMRI-BOLD activity in participants during calculation tasks entailing different arithmetic operations -- addition, subtraction, multiplication and division -- of different complexities. Functional imaging data revealed a common activation pattern comprising right precuneus, left and right middle and superior frontal regions during all arithmetic operations. All other regional activations were operation specific and distributed in prominently frontal, parietal and central regions when contrasting complex and simple calculation tasks. The present results largely confirm former studies suggesting that activation patterns due to mental arithmetic appear to reflect a basic anatomical substrate of working memory, numerical knowledge and processing based on finger counting, and derived from a network originally related to finger movement. We emphasize that in mental arithmetic research different arithmetic operations should always be examined and discussed independently of each other in order to avoid invalid generalizations on arithmetics and involved brain areas.

  18. Activation of Visuomotor Systems during Visually Guided Movements: A Functional MRI Study

    Science.gov (United States)

    Ellermann, Jutta M.; Siegal, Joel D.; Strupp, John P.; Ebner, Timothy J.; Ugurbil, Kâmil

    1998-04-01

    The dorsal stream is a dominant visuomotor pathway that connects the striate and extrastriate cortices to posterior parietal areas. In turn, the posterior parietal areas send projections to the frontal primary motor and premotor areas. This cortical pathway is hypothesized to be involved in the transformation of a visual input into the appropriate motor output. In this study we used functional magnetic resonance imaging (fMRI) of the entire brain to determine the patterns of activation that occurred while subjects performed a visually guided motor task. In nine human subjects, fMRI data were acquired on a 4-T whole-body MR system equipped with a head gradient coil and a birdcage RF coil using aT*2-weighted EPI sequence. Functional activation was determined for three different tasks: (1) a visuomotor task consisting of moving a cursor on a screen with a joystick in relation to various targets, (2) a hand movement task consisting of moving the joystick without visual input, and (3) a eye movement task consisting of moving the eyes alone without visual input. Blood oxygenation level-dependent (BOLD) contrast-based activation maps of each subject were generated using period cross-correlation statistics. Subsequently, each subject's brain was normalized to Talairach coordinates, and the individual maps were compared on a pixel by pixel basis. Significantly activated pixels common to at least four out of six subjects were retained to construct the final functional image. The pattern of activation during visually guided movements was consistent with the flow of information from striate and extrastriate visual areas, to the posterior parietal complex, and then to frontal motor areas. The extensive activation of this network and the reproducibility among subjects is consistent with a role for the dorsal stream in transforming visual information into motor behavior. Also extensively activated were the medial and lateral cerebellar structures, implicating the cortico

  19. Comparison of fMRI data from passive listening and active-response story processing tasks in children.

    Science.gov (United States)

    Vannest, Jennifer J; Karunanayaka, Prasanna R; Altaye, Mekibib; Schmithorst, Vincent J; Plante, Elena M; Eaton, Kenneth J; Rasmussen, Jerod M; Holland, Scott K

    2009-04-01

    To use functional MRI (fMRI) methods to visualize a network of auditory and language-processing brain regions associated with processing an aurally-presented story. We compare a passive listening (PL) story paradigm to an active-response (AR) version including online performance monitoring and a sparse acquisition technique. Twenty children (ages 11-13 years) completed PL and AR story processing tasks. The PL version presented alternating 30-second blocks of stories and tones; the AR version presented story segments, comprehension questions, and 5-second tone sequences, with fMRI acquisitions between stimuli. fMRI data was analyzed using a general linear model approach and paired t-test identifying significant group activation. Both tasks showed activation in the primary auditory cortex, superior temporal gyrus bilaterally, and left inferior frontal gyrus (IFG). The AR task demonstrated more extensive activation, including the dorsolateral prefrontal cortex and anterior/posterior cingulate cortex. Comparison of effect size in each paradigm showed a larger effect for the AR paradigm in a left inferior frontal region-of-interest (ROI). Activation patterns for story processing in children are similar in PL and AR tasks. Increases in extent and magnitude of activation in the AR task are likely associated with memory and attention resources engaged across acquisition intervals.

  20. Determination of hemisphere dominance for language: comparison of frontal and temporal fMRI activation with intracarotid amytal testing

    International Nuclear Information System (INIS)

    Spreer, J.; Arnold, S.; Ziyeh, S.; Klisch, J.; Schumacher, M.; Quiske, A.; Altenmueller, D.; Schulze-Bonhage, A.; Wohlfarth, R.; Steinhoff, B.J.; Herpers, M.; Kassubek, J.; Honegger, J.

    2002-01-01

    The reliability of frontal and temporal fMRI activations for the determination of hemisphere language dominance was evaluated in comparison with intracarotid amytal testing (IAT). Twenty-two patients were studied by IAT (bilateral in 13, unilateral in 9 patients) and fMRI using a paradigm requiring semantic decisions. Global and regional (frontal and temporoparietal) lateralisation indices (LI) were calculated from the number of activated (r>0.4) voxels in both hemispheres. Frontolateral activations associated with the language task were seen in all patients, temporoparietal activations in 20 of 22. Regional LI corresponded better with IAT results than global LI. Frontolateral LI were consistent with IAT in all patients with bilateral IAT (including three patients with right dominant and one patient with bilateral language representation) and were not conflicting in any of the patients with unilateral IAT. Temporoparietal LI were discordant with IAT in two patients with atypical language representation. In the determination of hemisphere dominance for language, regional analysis of fMRI activation is superior to global analysis. In cases with clear-cut fMRI lateralisation, i.e. consistent lateralised activation of frontal and temporoparietal language zones, IAT may be unnecessary. FMRI should be performed prior to IAT in all patients going to be operated in brain regions potentially involved in language. (orig.)

  1. Virtual visual reminiscing pain stimulation of allodynia patients activates cortical representation of pain and emotions. fMRI study

    International Nuclear Information System (INIS)

    Ikemoto, Tatsunori; Ushida, Takahiro; Taniguchi, Shinichirou; Tania, Toshikazu; Zinchuk, V.; Morio, Kazuo; Sasaki, Toshikazu

    2004-01-01

    It is widely known that sensation of the pain is derived from sensory-discriminative factor and emotional factor. Especially in chronic pain, emotional factors and psychosocial backgrounds are more likely to contribute for the patients' discomfort. The aim of this study is to investigate how emotional factor of pain participates in intractable pain. We employed functional MRI (fMRI) to compare the brain activations occurring in the orthopaedic neuropathic pain patients with allodynia and normal individuals in response to the visual virtual painful experience. During fMRI scanning, a video demonstrating an actual tactile stimulation of the palm and its imitation were shown to participants. In contrast to normal individuals, allodynia patients also displayed activation of the areas reflecting emotions: frontal lobe and anterior cingulate. These findings suggest that brain have important role in the development and maintaining of peripheral originated chronic painful condition. (author)

  2. Electrical activation and spin coherence of ultra low doseantimony implants in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Schenkel, T.; Tyryshkin, A.M.; de Sousa, R.; Whaley, K.B.; Bokor,J.; Liddle, J.A.; Persaud, A.; Shangkuan, J.; Chakarov, I.; Lyon, S.A.

    2005-07-13

    We implanted ultra low doses (0.2 to 2 x 10{sup 11} cm{sup -2}) of Sb ions into isotopically enriched {sup 28}Si, and probed electrical activation and electron spin relaxation after rapid thermal annealing. Strong segregation of dopants towards both Si{sub 3}N{sub 4} and SiO{sub 2} interfaces limits electrical activation. Pulsed Electron Spin Resonance shows that spin echo decay is sensitive to the dopant profiles, and the interface quality. A spin decoherence time, T{sub 2}, of 1.5 ms is found for profiles peaking 25 nm below a Si/SiO{sub 2} interface, increasing to 2.1 ms when the surface is passivated with hydrogen. These measurements provide benchmark data for the development of devices in which quantum information is encoded in donor electron spins.

  3. Activation behavior of boron implanted poly-Si on glass substrate

    International Nuclear Information System (INIS)

    Furuta, M.; Shimamura, K.; Tsubokawa, H.; Tokushige, K.; Furuta, H.; Hirao, T.

    2010-01-01

    The activation behavior of boron (B) implanted poly-Si films on glass substrates has been investigated. The effect of B dose and annealing temperature on crystal defects and electrical properties of the films were evaluated by Raman spectroscopy and Hall measurement. It was found that the maximum activation ratio of the film with B dose of 1 x 10 15 cm -2 was obtained when Raman peak associated with disordered amorphous silicon disappeared. However, reverse anneal was observed in the film when the annealing temperature further increased. The results from secondary ion mass spectrometry and Hall measurement revealed that B segregation at the top and bottom interface and deactivation of B substitutional occurred simultaneously in the high-dose specimens when the annealing temperature increased from 600 to 750 o C.

  4. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... metallic items, which can distort MRI images removable dental work pens, pocket knives and eyeglasses body piercings In most cases, an MRI exam is safe for patients with metal implants, except for a few types. People with the ...

  5. Brain MRI Tumor Detection using Active Contour Model and Local Image Fitting Energy

    Science.gov (United States)

    Nabizadeh, Nooshin; John, Nigel

    2014-03-01

    Automatic abnormality detection in Magnetic Resonance Imaging (MRI) is an important issue in many diagnostic and therapeutic applications. Here an automatic brain tumor detection method is introduced that uses T1-weighted images and K. Zhang et. al.'s active contour model driven by local image fitting (LIF) energy. Local image fitting energy obtains the local image information, which enables the algorithm to segment images with intensity inhomogeneities. Advantage of this method is that the LIF energy functional has less computational complexity than the local binary fitting (LBF) energy functional; moreover, it maintains the sub-pixel accuracy and boundary regularization properties. In Zhang's algorithm, a new level set method based on Gaussian filtering is used to implement the variational formulation, which is not only vigorous to prevent the energy functional from being trapped into local minimum, but also effective in keeping the level set function regular. Experiments show that the proposed method achieves high accuracy brain tumor segmentation results.

  6. Physical activity in primary versus secondary prevention indication implantable cardioverter defibrillator recipients 6-12 months after implantation - a cross-sectional study with register follow up

    DEFF Research Database (Denmark)

    Berg, S. K.; Thygesen, L. C.; Svendsen, J. H.

    2015-01-01

    OBJECTIVE: To describe (i) physical activity status among ICD patients according to the indication for ICD implant compared to international guidelines and compared to a matched normal population in order to detect potentials for improved physical outcomes, (ii) patients' beliefs regarding...... and participation in physical exercise by ICD indication, (iii) factors predicting low physical activity, and (iv) physical activity as a predictor of mortality. DESIGN: National survey with register follow-up. Comparisons were made to a matched healthy reference population and patients were followed in registers...... MEASURES: Questions regarding physical activity and the IPAQ questionnaire were used to assess physical activity. RESULTS: The response rate was 71.7%. Mean age 65.5 years with 82% males. 37% participated in a rehabilitation programme. 21 % were sedentary compared to 8 % in the reference population (p

  7. Extraocular surgery for implantation of an active subretinal visual prosthesis with external connections: feasibility and outcome in seven patients.

    Science.gov (United States)

    Besch, D; Sachs, H; Szurman, P; Gülicher, D; Wilke, R; Reinert, S; Zrenner, E; Bartz-Schmidt, K U; Gekeler, F

    2008-10-01

    Due to low energy levels in microphotodiode-based subretinal visual prostheses, an external power supply is mandatory. We report on the surgical feasibility and the functional outcome of the extraocular part of an approach to connect a subretinal prosthesis to an extracorporeal connector in the retro-auricular space via a trans-scleral, transchoroidal cable. Seven volunteers with retinitis pigmentosa received an active subretinal implant; energy was supplied by gold wires on a trans-sclerally, transchoroidally implanted polyimide foil leading to the lateral orbital rim where it was fixated and connected to a silicone cable. The cable was implanted subperiostally beneath the temporal muscle using a trocar to the retro-auricular space where it penetrated the skin for connection to a stimulator. To avoid subretinal movement of the implant, three tension relief points have been introduced. All implantations were performed as planned without complications, and no serious adverse events occurred in the postoperative period. Fixation of the implants was stable throughout the entire study duration of 4 weeks; permanent skin penetration proved to be uncomplicated. Motility was minimally restricted in downgaze and ab-/adduction. Explantation was uneventful. The above-described procedure provides a method for stable fixation of a subretinal device with a trans-scleral, transchoroidal cable connection to an extracorporeal connector.

  8. Inefficient preparatory fMRI-BOLD network activations predict working memory dysfunctions in patients with schizophrenia

    Directory of Open Access Journals (Sweden)

    Anja eBaenninger

    2016-03-01

    Full Text Available Patients with schizophrenia show abnormal dynamics and structure of temporally coherent networks (TCNs assessed using fMRI, which undergo adaptive shifts in preparation for a cognitively demanding task. During working memory (WM tasks, patients with schizophrenia show persistent deficits in TCNs as well as EEG indices of WM. Studying their temporal relationship during WM tasks might provide novel insights into WM performance deficits seen in schizophrenia.Simultaneous EEG-fMRI data were acquired during the performance of a verbal Sternberg WM task with two load levels (load 2 & load 5 in 17 patients with schizophrenia and 17 matched healthy controls. Using covariance mapping, we investigated the relationship of the activity in the TCNs before the memoranda were encoded and EEG spectral power during the retention interval. We assessed four TCNs – default mode network (DMN, dorsal attention network (dAN, left and right working memory networks (WMNs – and three EEG bands – theta, alpha, and beta.In healthy controls, there was a load dependent inverse relation between DMN and frontal-midline theta power and an anti-correlation between DMN and dAN. Both effects were not significantly detectable in patients. In addition, healthy controls showed a left-lateralized load-dependent recruitment of the WMNs. Activation of the WMNs was bilateral in patients, suggesting more resources were recruited for successful performance on the WM task.Our findings support the notion of schizophrenia patients showing deviations in their neurophysiological responses before the retention of relevant information in a verbal WM task. Thus, treatment strategies as neurofeedback targeting pre-states could be beneficial as task performance relies on the preparatory state of the brain.

  9. UV-activated 7-dehydrocholesterol-coated titanium implants promote differentiation of human umbilical cord mesenchymal stem cells into osteoblasts.

    Science.gov (United States)

    Satué, María; Ramis, Joana M; Monjo, Marta

    2016-01-01

    Vitamin D metabolites are essential for bone regeneration and mineral homeostasis. The vitamin D precursor 7-dehydrocholesterol can be used after UV irradiation to locally produce active vitamin D by osteoblastic cells. Furthermore, UV-irradiated 7-dehydrocholesterol is a biocompatible coating for titanium implants with positive effects on osteoblast differentiation. In this study, we examined the impact of titanium implants surfaces coated with UV-irradiated 7-dehydrocholesterol on the osteogenic differentiation of human umbilical cord mesenchymal stem cells. First, the synthesis of cholecalciferol (D3) was achieved through the incubation of the UV-activated 7-dehydrocholesterol coating for 48 h at 23℃. Further, we investigated in vitro the biocompatibility of this coating in human umbilical cord mesenchymal stem cells and its potential to enhance their differentiation towards the osteogenic lineage. Human umbilical cord mesenchymal stem cells cultured onto UV-irradiated 7-dehydrocholesterol-coated titanium implants surfaces, combined with osteogenic supplements, upregulated the gene expression of several osteogenic markers and showed higher alkaline phosphatase activity and calcein blue staining, suggesting increased mineralization. Thus, our results show that the use of UV irradiation on 7-dehydrocholesterol -treated titanium implants surfaces generates a bioactive coating that promotes the osteogenic differentiation of human umbilical cord mesenchymal stem cells, with regenerative potential for improving osseointegration in titanium-based bone anchored implants. © The Author(s) 2015.

  10. 3D perfusion bioreactor-activated porous granules on implant fixation and early bone formation in sheep

    DEFF Research Database (Denmark)

    Ding, Ming; Snoek Henriksen, Susan; Martinetti, Roberta

    2017-01-01

    allograft, granules, granules with bone marrow aspirate or bioreactor-activated graft material. Following an observation time of 6 weeks, early implant fixation and bone formation were assessed by micro-CT scanning, mechanical testing, and histomorphometry. Bone formations were seen in all groups, while......, bone formation was observed in all groups, while the bioreactor-activated graft material did not reveal additional effects on early implant fixation comparable to allograft in this model. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016....

  11. Activation characteristics of ion-implanted Si+ in AlGaN

    International Nuclear Information System (INIS)

    Irokawa, Y.; Fujishima, O.; Kachi, T.; Pearton, S.J.; Ren, F.

    2005-01-01

    Multiple-energy Si + implantation in the range 30-360 keV into Al 0.13 Ga 0.87 N for n-type doping was carried out at room temperature, followed by annealing at 1150-1375 deg. C for 5 min. Activation efficiencies close to 100% were obtained for ion doses of 1.0x10 15 cm -2 after annealing at 1375 deg. C, with a resulting sheet resistance of 74 Ω/square. By sharp contrast, the activation efficiency at 1150 deg. C was only 4% for this dose, with a sheet resistance of 1.63x10 4 Ω/square. The activation efficiency was also a function of dose, with a maximum activation percentage of only 55% for lower doses of 1.0x10 14 cm -2 annealed at 1375 deg. C. This is due to the comparatively larger effect of compensating acceptors at the lower dose and is also lower than the corresponding activation of Si in pure GaN under these conditions (78%). The measurement temperature dependence of sheet carrier density showed an activation energy of 23 meV, consistent with the ionization energy of Si in AlGaN

  12. Comparison of laterality index of upper and lower limb movement using brain activated fMRI

    Science.gov (United States)

    Harirchian, Mohammad Hossein; Oghabian, Mohammad Ali; Rezvanizadeh, Alireza; Bolandzadeh, Niousha

    2008-03-01

    Asymmetry of bilateral cerebral function, i.e. laterality, is an important phenomenon in many brain actions such as motor functions. This asymmetry maybe altered in some clinical conditions such as Multiple Sclerosis (MS). The aim of this study was to delineate the laterality differences for upper and lower limbs in healthy subjects to compare this pattern with subjects suffering from MS in advance. Hence 9 Male healthy subjects underwent fMRI assessment, while they were asked to move their limbs in a predetermined pattern. The results showed that hands movement activates the brain with a significant lateralization in pre-motor cortex in comparison with lower limb. Also, dominant hands activate brain more lateralized than the non-dominant hand. In addition, Left basal ganglia were observed to be activated regardless of the hand used, While, These patterns of Brain activation was not detected in lower limbs. We hypothesize that this difference might be attributed to this point that hand is usually responsible for precise and fine voluntary movements, whereas lower limb joints are mainly responsible for locomotion, a function integrating voluntary and automatic bilateral movements.

  13. Brain activation profiles during kinesthetic and visual imagery: An fMRI study.

    Science.gov (United States)

    Kilintari, Marina; Narayana, Shalini; Babajani-Feremi, Abbas; Rezaie, Roozbeh; Papanicolaou, Andrew C

    2016-09-01

    The aim of this study was to identify brain regions involved in motor imagery and differentiate two alternative strategies in its implementation: imagining a motor act using kinesthetic or visual imagery. Fourteen adults were precisely instructed and trained on how to imagine themselves or others perform a movement sequence, with the aim of promoting kinesthetic and visual imagery, respectively, in the context of an fMRI experiment using block design. We found that neither modality of motor imagery elicits activation of the primary motor cortex and that each of the two modalities involves activation of the premotor area which is also activated during action execution and action observation conditions, as well as of the supplementary motor area. Interestingly, the visual and the posterior cingulate cortices show reduced BOLD signal during both imagery conditions. Our results indicate that the networks of regions activated in kinesthetic and visual imagery of motor sequences show a substantial, while not complete overlap, and that the two forms of motor imagery lead to a differential suppression of visual areas. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. MRI of the transverse and alar ligaments in rheumatoid arthritis: feasibility and relations to atlantoaxial subluxation and disease activity

    Energy Technology Data Exchange (ETDEWEB)

    Vetti, Nils; Kraakenes, Jostein; Roervik, Jarle; Espeland, Ansgar [Haukeland University Hospital, Department of Radiology, Bergen (Norway); University of Bergen, Section for Radiology, Department of Surgical Sciences, Bergen (Norway); Alsing, Rikke; Brun, Johan Gorgas [Haukeland University Hospital, Department of Rheumatology, Bergen (Norway); University of Bergen, Section for Rheumatology, Institute of Medicine, Bergen (Norway); Gilhus, Nils Erik [Haukeland University Hospital, Department of Neurology, Bergen (Norway); University of Bergen, Section for Neurology, Department of Clinical Medicine, Bergen (Norway)

    2010-03-15

    Dysfunctional transverse and alar craniovertebral ligaments can cause instability and osseous destruction in rheumatoid arthritis (RA). This study examined (1) the feasibility of high-resolution magnetic resonance imaging (MRI) of these ligaments in RA and (2) the relation between ligament high-signal changes and atlantoaxial subluxation and RA duration/severity. Consecutive RA patients (n=46) underwent clinical examination, functional radiography, and high-resolution MRI. Two blinded radiologists rated MRI image quality, graded ligament high-signal changes 0-3 on proton-weighted sequences using an existing grading system, and assessed cervical spine rheumatic changes on short tau inversion recovery images. Agreement was analyzed using kappa and relations using multiple logistic regression. MRI images had good quality in 42 (91.3%) of 46 patients and were interpretable in 44 (32 women and 12 men, median age/disease duration 60.4/9.1 years). MRI grades 2-3 changes of the transverse and alar ligaments showed moderate and good interobserver agreement (kappa 0.59 and 0.78), respectively, and prevalence 31.8% and 34.1%. Such ligament changes were more frequent with increasing anterior atlantoaxial subluxation (p=0.012 transverse, p=0.028 alar), higher erythrocyte sedimentation rate (p=0.003 transverse), positive rheumatoid factor (p=0.002 alar), and neck pain (p = 0.004 alar). This first study of high-resolution MRI of these ligaments in RA showed high feasibility and relations with atlantoaxial subluxation, RA disease activity, and neck pain. The clinical usefulness of such MRI needs further evaluation. (orig.)

  15. MRI of the transverse and alar ligaments in rheumatoid arthritis: feasibility and relations to atlantoaxial subluxation and disease activity

    International Nuclear Information System (INIS)

    Vetti, Nils; Kraakenes, Jostein; Roervik, Jarle; Espeland, Ansgar; Alsing, Rikke; Brun, Johan Gorgas; Gilhus, Nils Erik

    2010-01-01

    Dysfunctional transverse and alar craniovertebral ligaments can cause instability and osseous destruction in rheumatoid arthritis (RA). This study examined (1) the feasibility of high-resolution magnetic resonance imaging (MRI) of these ligaments in RA and (2) the relation between ligament high-signal changes and atlantoaxial subluxation and RA duration/severity. Consecutive RA patients (n=46) underwent clinical examination, functional radiography, and high-resolution MRI. Two blinded radiologists rated MRI image quality, graded ligament high-signal changes 0-3 on proton-weighted sequences using an existing grading system, and assessed cervical spine rheumatic changes on short tau inversion recovery images. Agreement was analyzed using kappa and relations using multiple logistic regression. MRI images had good quality in 42 (91.3%) of 46 patients and were interpretable in 44 (32 women and 12 men, median age/disease duration 60.4/9.1 years). MRI grades 2-3 changes of the transverse and alar ligaments showed moderate and good interobserver agreement (kappa 0.59 and 0.78), respectively, and prevalence 31.8% and 34.1%. Such ligament changes were more frequent with increasing anterior atlantoaxial subluxation (p=0.012 transverse, p=0.028 alar), higher erythrocyte sedimentation rate (p=0.003 transverse), positive rheumatoid factor (p=0.002 alar), and neck pain (p = 0.004 alar). This first study of high-resolution MRI of these ligaments in RA showed high feasibility and relations with atlantoaxial subluxation, RA disease activity, and neck pain. The clinical usefulness of such MRI needs further evaluation. (orig.)

  16. Electrical activation and local structure of Se atoms in ion-implanted indium phosphide

    International Nuclear Information System (INIS)

    Yu, K.M.; Chan, N.; Hsu, L.

    1996-01-01

    The solid phase regrowth, dopant activation, and local environments of Se-implanted InP are investigated with ion-beam techniques and extended x-ray-absorption fine structure spectroscopy. We find that the local Se endash In structure is already established in the as-implanted amorphous InP although the Se atoms have a lower average coordination number (∼3.5) and no long-range order. After high-temperature rapid thermal annealing (950 degree C, 5 s), the amorphous InP regrows, becoming a single crystal with the Se atoms bonded to four In neighbors; however, only ∼50% of the Se becomes electrically active. Part of the Se precipitates in the form of an In endash Se phase, another part is compensated by defects which are not totally removed by annealing. The Se emdash In bond distance for a Se on a P site is 4.5% longer than the matrix In emdash P bond length, introducing large strains in the crystal. The solid solubility of Se in InP is estimated from our results to be ≅8.7x10 19 /cm 3 while the electron concentration saturates at 5.4x10 19 /cm 3 . Se atoms in InP regrown at lower temperatures in a furnace are only ∼7% electrically active and are found to have different local environments (higher coordination number and shorter bond distance) than those in the InP perfectly regrown at higher temperature. copyright 1996 American Institute of Physics

  17. 'Visual' cortical activation induced by acupuncture at vision-related acupoint: A fMRI study

    International Nuclear Information System (INIS)

    Yan, B.; Shan, B.C.; Zhi, L.H.; Li, K.; Lu, N.; Li, L.; Liu, H.

    2005-01-01

    It has attracted attention recently that acupuncture at vision-related acupoints, which are used to treat eye diseases according to Traditional Chinese Medicine (TCM), could activate the visual cortex. Cho and colleagues have reported that acupuncture at vision-related acupoints in the foot, activate the visual cortex bilaterally. Similar results were reported by Siedentopf and coworkers using laser acupuncture. However, Gareus et al. did not get the result, In this study, manual acupuncture was used to examine the response of central nervous system (CNS) to acupuncture at Liv3, one of important acupoints used to treat eye-related disease in clinic. To avoid the non-specific factors such as pain and anxiety, a sham acupoint which is approximately 10 mm anterior to Liv3 and innervated by the same spinal segment was selected as control. The CNS response was obtained by subtracting fMRI brain images evoked by nearby 'sham' acupoint from that evoked by the 'real' acupoint. 17 healthy right handed volunteers were comprised in the study. The images were got on 1.5T MR with EPI sequence. After 62 baseline scans, a silver needle 0.30 mm in diameter and 25 mm long was inserted and twirled for 60 scans; then the needle was withdrawn while fMRI scanning continued, until a total of 402 scans were acquired. During acupuncture, the needle was twirled manually clockwise and anticlockwise at 1 Hz with 'even reinforcing and reducing' needle manipulation. The depth of needle insertion at the sham acupoint was approximately 15 mm, the same as at the real acupoint. All the points in this study were on the right foot. The data were analyzed with spm99 using random effects analysis, discrepancies in the activation areas between Liv3 and the sham acupoint were obtained at p<0.01. Acupuncture at Liv3 significantly activated Brodmann Area 19 (BA 19) bilaterally, middle temporal gyrus, cerebellum, ipsilateral posterior cingulate, parahippocampal gyrus, contralateral postcentral gyrus, and

  18. 'Visual' cortical activation induced by acupuncture at vision-related acupoint: a fMRI study

    International Nuclear Information System (INIS)

    Yan, B.; Shan, B.C.; Zhi, L.H.; Li, K.; Lu, N.; Li, L.; Liu, H.

    2005-01-01

    It has attracted attention recently that acupuncture at vision-related acupoints, which are used to treat eye diseases according to Traditional Chinese Medicine (TCM), could activate the visual cortex. Cho and colleagues have reported that acupuncture at vision-related acupoints in the foot, activate the visual cortex bilaterally. Similar results were reported by Siedentopf and coworkers using laser acupuncture. However, Gareus et al. did not get the result. In this study, manual acupuncture was used to examine the response of central nervous system (CNS) to acupuncture at Liv3, one of important acupoints used to treat eye-related disease in clinic. To avoid the non-specific factors such as pain and anxiety, a sham acupoint which is approximately 10 mm anterior to Liv3 and innervated by the same spinal segment was selected as control. The CNS response was obtained by subtracting fMRI brain images evoked by nearby 'sham' acupoint from that evoked by the 'real' acupoint. 17 healthy right handed volunteers were comprised in the study. The images were got on 1.5T MR with EPI sequence. After 62 baseline scans, a silver needle 0.30 mm in diameter and 25 mm long was inserted and twirled for 60 scans; then the needle was withdrawn while fMRI scanning continued, until a total of 402 scans were acquired. During acupuncture, the needle was twirled manually clockwise and anticlockwise at 1 Hz with 'even reinforcing and reducing' needle manipulation. The depth of needle insertion at the sham acupoint was approximately 15 mm, the same as at the real acupoint. All the points in this study were on the right foot. The data were analyzed with spm99 using random effects analysis, discrepancies in the activation areas between Liv3 and the sham acupoint were obtained at p<0.01. Acupuncture at Liv3 significantly activated Brodmann Area 19 (BA 19) bilaterally, middle temporal gyrus, cerebellum, ipsilateral posterior cingulate, parahippocampal gyrus, contralateral postcentral gyrus, and

  19. Brain Activation by Visual Food-Related Stimuli and Correlations with Metabolic and Hormonal Parameters: A fMRI Study

    NARCIS (Netherlands)

    Jakobsdottir, S.; de Ruiter, M.B.; Deijen, J.B.; Veltman, D.J.; Drent, M.L.

    2012-01-01

    Regional brain activity in 15 healthy, normal weight males during processing of visual food stimuli in a satiated and a hungry state was examined and correlated with neuroendocrine factors known to be involved in hunger and satiated states. Two functional Magnetic Resonance Imaging (fMRI) sessions

  20. Lateralization of functional magnetic resonance imaging (fMRI) activation in the auditory pathway of patients with lateralized tinnitus

    Energy Technology Data Exchange (ETDEWEB)

    Smits, Marion [Erasmus MC - University Medical Center Rotterdam, Department of Radiology, Hs 224, Rotterdam (Netherlands); Kovacs, Silvia; Peeters, Ronald R; Hecke, Paul van; Sunaert, Stefan [University Hospitals of the Catholic University Leuven, Department of Radiology, Leuven (Belgium); Ridder, Dirk de [University of Antwerp, Department of Neurosurgery, Edegem (Belgium)

    2007-08-15

    Tinnitus is hypothesized to be an auditory phantom phenomenon resulting from spontaneous neuronal activity somewhere along the auditory pathway. We performed fMRI of the entire auditory pathway, including the inferior colliculus (IC), the medial geniculate body (MGB) and the auditory cortex (AC), in 42 patients with tinnitus and 10 healthy volunteers to assess lateralization of fMRI activation. Subjects were scanned on a 3T MRI scanner. A T2*-weighted EPI silent gap sequence was used during the stimulation paradigm, which consisted of a blocked design of 12 epochs in which music presented binaurally through headphones, which was switched on and off for periods of 50 s. Using SPM2 software, single subject and group statistical parametric maps were calculated. Lateralization of activation was assessed qualitatively and quantitatively. Tinnitus was lateralized in 35 patients (83%, 13 right-sided and 22 left-sided). Significant signal change (P{sub corrected} < 0.05) was found bilaterally in the primary and secondary AC, the IC and the MGB. Signal change was symmetrical in patients with bilateral tinnitus. In patients with lateralized tinnitus, fMRI activation was lateralized towards the side of perceived tinnitus in the primary AC and IC in patients with right-sided tinnitus, and in the MGB in patients with left-sided tinnitus. In healthy volunteers, activation in the primary AC was left-lateralized. Our paradigm adequately visualized the auditory pathways in tinnitus patients. In lateralized tinnitus fMRI activation was also lateralized, supporting the hypothesis that tinnitus is an auditory phantom phenomenon. (orig.)

  1. Lateralization of functional magnetic resonance imaging (fMRI) activation in the auditory pathway of patients with lateralized tinnitus

    International Nuclear Information System (INIS)

    Smits, Marion; Kovacs, Silvia; Peeters, Ronald R.; Hecke, Paul van; Sunaert, Stefan; Ridder, Dirk de

    2007-01-01

    Tinnitus is hypothesized to be an auditory phantom phenomenon resulting from spontaneous neuronal activity somewhere along the auditory pathway. We performed fMRI of the entire auditory pathway, including the inferior colliculus (IC), the medial geniculate body (MGB) and the auditory cortex (AC), in 42 patients with tinnitus and 10 healthy volunteers to assess lateralization of fMRI activation. Subjects were scanned on a 3T MRI scanner. A T2*-weighted EPI silent gap sequence was used during the stimulation paradigm, which consisted of a blocked design of 12 epochs in which music presented binaurally through headphones, which was switched on and off for periods of 50 s. Using SPM2 software, single subject and group statistical parametric maps were calculated. Lateralization of activation was assessed qualitatively and quantitatively. Tinnitus was lateralized in 35 patients (83%, 13 right-sided and 22 left-sided). Significant signal change (P corrected < 0.05) was found bilaterally in the primary and secondary AC, the IC and the MGB. Signal change was symmetrical in patients with bilateral tinnitus. In patients with lateralized tinnitus, fMRI activation was lateralized towards the side of perceived tinnitus in the primary AC and IC in patients with right-sided tinnitus, and in the MGB in patients with left-sided tinnitus. In healthy volunteers, activation in the primary AC was left-lateralized. Our paradigm adequately visualized the auditory pathways in tinnitus patients. In lateralized tinnitus fMRI activation was also lateralized, supporting the hypothesis that tinnitus is an auditory phantom phenomenon. (orig.)

  2. Changes in singing performance and fMRI activation following right temporal lobe surgery.

    Science.gov (United States)

    Wilson, Sarah J; Abbott, David F; Tailby, Chris; Gentle, Ellen C; Merrett, Dawn L; Jackson, Graeme D

    2013-10-01

    This study arose in the context of having to estimate risk to the musical abilities of a trained singer (patient A.M.) recommended for right anterior temporal lobectomy (RATL) to ameliorate medically intractable seizures. To date there has been no systematic investigation of reorganisation of musical functions in the presence of epileptogenic lesions, although it is well established that RATL can impair pitch processing in nonmusicians. Using fMRI, we compared the network activated by covert singing with lyrics in A.M. before and after surgery, while taking language activation and singing expertise into consideration. Before surgery, A.M. showed lower pitch accuracy of singing relative to individuals of similar experience (experts), thus we compared her to 12 healthy controls matched for singing pitch accuracy. We found atypical organisation of A.M.'s singing network before surgery in the presence of a malformation of cortical development, including partial activation of the singing network of pitch-matched controls, and diffuse activation along the midline spreading laterally into association cortex, typical of generalised cortical hyperexcitability in intractable epilepsy. After tailored RATL, A.M. showed striking behavioural and neuroimaging changes, including significant improvement in pitch accuracy of singing relative to controls (p = .026) and the subjective experience of being a more technically proficient singer. This was accompanied by a significant reduction in cortical activation (p singing activation emerging, including decreased involvement of frontal language regions. These changes were largely specific to singing, with A.M. showing language activation and performance similar to controls. This case provides evidence for selective disruption of the singing network that reorganised after successful resection of an epileptogenic lesion and likely occurred through decoupling of the singing and language networks. Crown Copyright © 2013. Published by

  3. MRI of the Chest

    Medline Plus

    Full Text Available ... types of clips used for brain aneurysms some types of metal coils placed within blood vessels nearly all cardiac defibrillators and pacemakers You ... a preferred imaging test. MR imaging can assess blood flow without ... the opening of certain types of MRI machines. The presence of an implant ...

  4. Comparison between hybrid feedforward-feedback, feedforward, and feedback structures for active noise control of fMRI noise.

    Science.gov (United States)

    Reddy, Rajiv M; Panahi, Issa M S

    2008-01-01

    The performance of FIR feedforward, IIR feedforward, FIR feedback, hybrid FIR feedforward--FIR feedback, and hybrid IIR feedforward - FIR feedback structures for active noise control (ANC) are compared for an fMRI noise application. The filtered-input normalized least squares (FxNLMS) algorithm is used to update the coefficients of the adaptive filters in all these structures. Realistic primary and secondary paths of an fMRI bore are used by estimating them on a half cylindrical acrylic bore of 0.76 m (D)x1.52 m (L). Detailed results of the performance of the ANC system are presented in the paper for each of these structures. We find that the IIR feedforward structure produces most of the performance improvement in the hybrid IIR feedforward - FIR feedback structure and adding the feedback structure becomes almost redundant in the case of fMRI noise.

  5. 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)

    Tae, Woo Suk; Kim, Sam Soo; Lee, Kang Uk; Lee, Seung Hwan; Nam, Eui Cheol; Choi, Hyun Kyung

    2009-01-01

    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

  6. Optimization of dental implantation

    Science.gov (United States)

    Dol, Aleksandr V.; Ivanov, Dmitriy V.

    2017-02-01

    Modern dentistry can not exist without dental implantation. This work is devoted to study of the "bone-implant" system and to optimization of dental prostheses installation. Modern non-invasive methods such as MRI an 3D-scanning as well as numerical calculations and 3D-prototyping allow to optimize all of stages of dental prosthetics. An integrated approach to the planning of implant surgery can significantly reduce the risk of complications in the first few days after treatment, and throughout the period of operation of the prosthesis.

  7. Protection of active implant electronics with organosilicon open air plasma coating for plastic overmolding

    Directory of Open Access Journals (Sweden)

    Zeppenfeld Matthias

    2016-09-01

    Full Text Available To overcome challenges for manufacturing of modern smart medical plastic parts by injection molding, e.g. for active implants, the optimization of the interface between electronics and the polymer component concerning adhesion and diffusion behavior is crucial. Our results indicate that a nano-sized SiOxCyHz layer formed by plasma-enhanced chemical vapour deposition (PE-CVD via open air atmospheric pressure plasma jet (APPJ and by use of a hexamthyldisiloxane (HMDSO precursor can form a non-corrosive, anti-permeable and biocompatible coating. Due to the open air character of the APPJ process an inline coating before overmolding could be an easy applicable method and a promising advancement.

  8. Quantifying the inflammatory activity in Crohn's disease using CE dynamic MRI

    International Nuclear Information System (INIS)

    Pauls, S.; Schmidt, S.A.; Brambs, H.J.; Gabelmann, A.; Kratzer, W.; Mittrach, C.; Adler, G.; Rieber, A.

    2003-01-01

    Purpose: Evaluation of dynamic contrast enhanced MRI in patients with Crohn's disease to assess local inflammatory activity. Material and Methods: Prospective study of 13 patients with histologically proven Crohn's disease. Axial and coronal slices were acquired by a 1.5 T MR (Magnetom Vision, Siemens, Germany): T1 flash 2 D (TR 72.5 ms, TE 4.1 ms), T2 (TR 2730 ms, TE 138 ms), turbo-flash sequences T1 (TR 94.2 ms, TE 4.1 ms) post contrast media fat saturated (Magnevist circledR , 0.2 ml/kg, flow 4 ml/s). In area of maximal thickening of terminal ileal wall, axial dynamic T1 sequences (TR 11 ms, TE 4.2 ms) were acquired every 1.5 s post contrast media application for a total duration of 1 min. Contrast uptake was subjectively measured by semiquantitative score and computed assisted ROI evaluation. MR parameters were correlated with CDAI (Crohn's disease activity index) and SAI (severe activity index). Results: Contrast uptake in the intestinal wall occurred after 18.5 s (range: 3.0-28.0), contrast upslope until plateau phase lasted for 16.1 s (range: 8.0-50.0). Maximum contrast enhancement into the bowel wall was 266% (105-450%) of baseline. After maximum contrast uptake, we observed a plateau phase in all cases for the total duration of measurement. A significant correlation existed for maximum contrast uptake to CDAI (r = 0.591; p = 0.033), for beginning of contrast upslope to the time until plateau phase (r = 0.822; p = 0.001), and for the time until plateau phase to CDAI (r = 0.562; p = 0.046). CDAI was on average 108, median 106; SAI was on average 114, median 115. SAI correlated significantly to CDAI (r = 0.874). Maximum contrast uptake, beginning of contrast upslope, and time until plateau phase were independent to creeping fat, local lymphadenitis, laboratory parameters, temperature, body mass index, heart frequency and systolic blood pressure. Conclusion: Dynamic MRI enables to quantify local inflammatory activity of bowel wall in patients with Crohn

  9. Attention to emotion modulates fMRI activity in human right superior temporal sulcus.

    Science.gov (United States)

    Narumoto, J; Okada, T; Sadato, N; Fukui, K; Yonekura, Y

    2001-10-01

    A parallel neural network has been proposed for processing various types of information conveyed by faces including emotion. Using functional magnetic resonance imaging (fMRI), we tested the effect of the explicit attention to the emotional expression of the faces on the neuronal activity of the face-responsive regions. Delayed match to sample procedure was adopted. Subjects were required to match the visually presented pictures with regard to the contour of the face pictures, facial identity, and emotional expressions by valence (happy and fearful expressions) and arousal (fearful and sad expressions). Contour matching of the non-face scrambled pictures was used as a control condition. The face-responsive regions that responded more to faces than to non-face stimuli were the bilateral lateral fusiform gyrus (LFG), the right superior temporal sulcus (STS), and the bilateral intraparietal sulcus (IPS). In these regions, general attention to the face enhanced the activities of the bilateral LFG, the right STS, and the left IPS compared with attention to the contour of the facial image. Selective attention to facial emotion specifically enhanced the activity of the right STS compared with attention to the face per se. The results suggest that the right STS region plays a special role in facial emotion recognition within distributed face-processing systems. This finding may support the notion that the STS is involved in social perception.

  10. Cortical activation during power grip task with pneumatic pressure gauge: an fMRI study

    Science.gov (United States)

    Mohamad, M.; Mardan, N. H.; Ismail, S. S.

    2017-05-01

    Aging is associated with a decline in cognitive and motor function. But, the relationships with motor performance are less well understood. In this study, functional magnetic resonance imaging (fMRI) was used to assess cortical activation in older adults. This study employed power grip task that utilised block paradigm consisted of alternate 30s rest and active. A visual cue was used to pace the hand grip movement that clenched a cylindrical rubber bulb connected with pressure pneumatic gauge that measure the pressure (Psi). The objective of this study is determined the brain areas activated during motor task and the correlation between percentage signal change of each motor area (BA 4 and 6) and hand grip pressure. Result showed there was a significant difference in mean percentage signal change in BA 4 and BA 6 in both hemispheres and negative correlation obtained in BA 4 and BA 6. These results indicate that a reduced ability in the motor networks contribute to age-related decline in motor performance.

  11. Cortical activation during power grip task with pneumatic pressure gauge: an fMRI study

    International Nuclear Information System (INIS)

    Mohamad, M; Ismail, S S; Mardan, N H

    2017-01-01

    Aging is associated with a decline in cognitive and motor function. But, the relationships with motor performance are less well understood. In this study, functional magnetic resonance imaging (fMRI) was used to assess cortical activation in older adults. This study employed power grip task that utilised block paradigm consisted of alternate 30s rest and active. A visual cue was used to pace the hand grip movement that clenched a cylindrical rubber bulb connected with pressure pneumatic gauge that measure the pressure (Psi). The objective of this study is determined the brain areas activated during motor task and the correlation between percentage signal change of each motor area (BA 4 and 6) and hand grip pressure. Result showed there was a significant difference in mean percentage signal change in BA 4 and BA 6 in both hemispheres and negative correlation obtained in BA 4 and BA 6. These results indicate that a reduced ability in the motor networks contribute to age-related decline in motor performance. (paper)

  12. Intermittent compared to continuous real-time fMRI neurofeedback boosts control over amygdala activation.

    Science.gov (United States)

    Hellrung, Lydia; Dietrich, Anja; Hollmann, Maurice; Pleger, Burkhard; Kalberlah, Christian; Roggenhofer, Elisabeth; Villringer, Arno; Horstmann, Annette

    2018-02-01

    Real-time fMRI neurofeedback is a feasible tool to learn the volitional regulation of brain activity. So far, most studies provide continuous feedback information that is presented upon every volume acquisition. Although this maximizes the temporal resolution of feedback information, it may be accompanied by some disadvantages. Participants can be distracted from the regulation task due to (1) the intrinsic delay of the hemodynamic response and associated feedback and (2) limited cognitive resources available to simultaneously evaluate feedback information and stay engaged with the task. Here, we systematically investigate differences between groups presented with different variants of feedback (continuous vs. intermittent) and a control group receiving no feedback on their ability to regulate amygdala activity using positive memories and feelings. In contrast to the feedback groups, no learning effect was observed in the group without any feedback presentation. The group receiving intermittent feedback exhibited better amygdala regulation performance when compared with the group receiving continuous feedback. Behavioural measurements show that these effects were reflected in differences in task engagement. Overall, we not only demonstrate that the presentation of feedback is a prerequisite to learn volitional control of amygdala activity but also that intermittent feedback is superior to continuous feedback presentation. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  13. Brain's reward circuits mediate itch relief. a functional MRI study of active scratching.

    Directory of Open Access Journals (Sweden)

    Alexandru D P Papoiu

    Full Text Available Previous brain imaging studies investigating the brain processing of scratching used an exogenous intervention mimicking scratching, performed not by the subjects themselves, but delivered by an investigator. In real life, scratching is a conscious, voluntary, controlled motor response to itching, which is directed to the perceived site of distress. In this study we aimed to visualize in real-time by brain imaging the core mechanisms of the itch-scratch cycle when scratching was performed by subjects themselves. Secondly, we aimed to assess the correlations between brain patterns of activation and psychophysical ratings of itch relief or pleasurability of scratching. We also compared the patterns of brain activity evoked by self-scratching vs. passive scratching. We used a robust tridimensional Arterial Spin Labeling fMRI technique that is less sensitive to motion artifacts: 3D gradient echo and spin echo (GRASE--Propeller. Active scratching was accompanied by a higher pleasurability and induced a more pronounced deactivation of the anterior cingulate cortex and insula, in comparison with passive scratching. A significant involvement of the reward system including the ventral tegmentum of the midbrain, coupled with a mechanism deactivating the periaqueductal gray matter (PAG, suggests that itch modulation operates in reverse to the mechanism known to suppress pain. Our findings not only confirm a role for the central networks processing reward in the pleasurable aspects of scratching, but also suggest they play a role in mediating itch relief.

  14. Updating working memory in aircraft noise and speech noise causes different fMRI activations.

    Science.gov (United States)

    Saetrevik, Bjørn; Sörqvist, Patrik

    2015-02-01

    The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between "substitution processes," which involve adding new items to the working memory representation and suppressing old items, and "exclusion processes," which involve rejecting new items and maintaining an intact memory set. The current findings supported the findings of a previous study by showing that substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, whereas exclusion activated the anterior medial frontal cortex. Moreover, the prefrontal cortex was activated more by substitution processes when exposed to background speech than when exposed to aircraft noise. These results indicate that (a) the prefrontal cortex plays a special role when task-irrelevant materials should be denied access to working memory and (b) that, when compensating for different types of noise, either different cognitive mechanisms are involved or those cognitive mechanisms that are involved are involved to different degrees. © 2014 The Authors. Scandinavian Journal of Psychology published by Scandinavian Psychological Associations and John Wiley & Sons Ltd.

  15. Effects of active music therapy on the normal brain: fMRI based evidence.

    Science.gov (United States)

    Raglio, Alfredo; Galandra, Caterina; Sibilla, Luisella; Esposito, Fabrizio; Gaeta, Francesca; Di Salle, Francesco; Moro, Luca; Carne, Irene; Bastianello, Stefano; Baldi, Maurizia; Imbriani, Marcello

    2016-03-01

    The aim of this study was to investigate the neurophysiological bases of Active Music Therapy (AMT) and its effects on the normal brain. Twelve right-handed, healthy, non-musician volunteers were recruited. The subjects underwent 2 AMT sessions based on the free sonorous-music improvisation using rhythmic and melodic instruments. After these sessions, each subject underwent 2 fMRI scan acquisitions while listening to a Syntonic (SP) and an A-Syntonic (AP) Production from the AMT sessions. A 3 T Discovery MR750 scanner with a 16-channel phased array head coil was used, and the image analysis was performed with Brain Voyager QX 2.8. The listening to SP vs AP excerpts mainly activated: (1) the right middle temporal gyrus and right superior temporal sulcus, (2) the right middle frontal gyrus and in particular the right precentral gyrus, (3) the bilateral precuneus, (4) the left superior temporal sulcus and (5) the left middle temporal gyrus. These results are consistent with the psychological bases of the AMT approach and with the activation of brain areas involved in memory and autobiographical processes, and also in personal or interpersonal significant experiences. Further studies are required to confirm these findings and to explain possible effects of AMT in clinical settings.

  16. Extendable supervised dictionary learning for exploring diverse and concurrent brain activities in task-based fMRI.

    Science.gov (United States)

    Zhao, Shijie; Han, Junwei; Hu, Xintao; Jiang, Xi; Lv, Jinglei; Zhang, Tuo; Zhang, Shu; Guo, Lei; Liu, Tianming

    2018-06-01

    Recently, a growing body of studies have demonstrated the simultaneous existence of diverse brain activities, e.g., task-evoked dominant response activities, delayed response activities and intrinsic brain activities, under specific task conditions. However, current dominant task-based functional magnetic resonance imaging (tfMRI) analysis approach, i.e., the general linear model (GLM), might have difficulty in discovering those diverse and concurrent brain responses sufficiently. This subtraction-based model-driven approach focuses on the brain activities evoked directly from the task paradigm, thus likely overlooks other possible concurrent brain activities evoked during the information processing. To deal with this problem, in this paper, we propose a novel hybrid framework, called extendable supervised dictionary learning (E-SDL), to explore diverse and concurrent brain activities under task conditions. A critical difference between E-SDL framework and previous methods is that we systematically extend the basic task paradigm regressor into meaningful regressor groups to account for possible regressor variation during the information processing procedure in the brain. Applications of the proposed framework on five independent and publicly available tfMRI datasets from human connectome project (HCP) simultaneously revealed more meaningful group-wise consistent task-evoked networks and common intrinsic connectivity networks (ICNs). These results demonstrate the advantage of the proposed framework in identifying the diversity of concurrent brain activities in tfMRI datasets.

  17. COUP-TFII mediates progesterone regulation of uterine implantation by controlling ER activity.

    Directory of Open Access Journals (Sweden)

    Isao Kurihara

    2007-06-01

    Full Text Available Progesterone and estrogen are critical regulators of uterine receptivity. To facilitate uterine remodeling for embryo attachment, estrogen activity in the uterine epithelia is attenuated by progesterone; however, the molecular mechanism by which this occurs is poorly defined. COUP-TFII (chicken ovalbumin upstream promoter transcription factor II; also known as NR2F2, a member of the nuclear receptor superfamily, is highly expressed in the uterine stroma and its expression is regulated by the progesterone-Indian hedgehog-Patched signaling axis that emanates from the epithelium. To further assess COUP-TFII uterine function, a conditional COUP-TFII knockout mouse was generated. This mutant mouse is infertile due to implantation failure, in which both embryo attachment and uterine decidualization are impaired. Using this animal model, we have identified a novel genetic pathway in which BMP2 lies downstream of COUP-TFII. Epithelial progesterone-induced Indian hedgehog regulates stromal COUP-TFII, which in turn controls BMP2 to allow decidualization to manifest in vivo. Interestingly, enhanced epithelial estrogen activity, which impedes maturation of the receptive uterus, was clearly observed in the absence of stromal-derived COUP-TFII. This finding is consistent with the notion that progesterone exerts its control of implantation through uterine epithelial-stromal cross-talk and reveals that stromal-derived COUP-TFII is an essential mediator of this complex cross-communication pathway. This finding also provides a new signaling paradigm for steroid hormone regulation in female reproductive biology, with attendant implications for furthering our understanding of the molecular mechanisms that underlie dysregulation of hormonal signaling in such human reproductive disorders as endometriosis and endometrial cancer.

  18. RESOLUTE PET/MRI Attenuation Correction for O-(2-18F-fluoroethyl-L-tyrosine (FET in Brain Tumor Patients with Metal Implants

    Directory of Open Access Journals (Sweden)

    Claes N. Ladefoged

    2017-08-01

    Full Text Available Aim: Positron emission tomography (PET imaging is a useful tool for assisting in correct differentiation of tumor progression from reactive changes, and the radiolabeled amino acid analog tracer O-(2-18F-fluoroethyl-L-tyrosine (FET-PET is amongst the most frequently used. The FET-PET images need to be quantitatively correct in order to be used clinically, which require accurate attenuation correction (AC in PET/MRI. The aim of this study was to evaluate the use of the subject-specific MR-derived AC method RESOLUTE in post-operative brain tumor patients.Methods: We analyzed 51 post-operative brain tumor patients (68 examinations, 200 MBq [18F]-FET investigated in a PET/MRI scanner. MR-AC maps were acquired using: (1 the Dixon water fat separation sequence, (2 the ultra short echo time (UTE sequences, (3 calculated using our new RESOLUTE methodology, and (4 a same day low-dose CT used as reference “gold standard.” For each subject and each AC method the tumor was delineated by isocontouring tracer uptake above a tumor(T-to-brain background (B activity ratio of 1.6. We measured B, tumor mean and maximal activity (TMEAN, TMAX, biological tumor volume (BTV, and calculated the clinical metrics TMEAN/B and TMAX/B.Results: When using RESOLUTE 5/68 studies did not meet our predefined acceptance criteria of TMAX/B difference to CT-AC < ±0.1 or 5%, TMEAN/B < ±0.05 or 5%, and BTV < ±2 mL or 10%. In total, 46/68 studies failed our acceptance criteria using Dixon, and 26/68 using UTE. The 95% limits of agreement for TMAX/B was for RESOLUTE (−3%; 4%, Dixon (−9%; 16%, and UTE (−7%; 10%. The absolute error when measuring BTV was 0.7 ± 1.9 mL (N.S with RESOLUTE, 5.3 ± 10 mL using Dixon, and 1.7 ± 3.7 mL using UTE. RESOLUTE performed best in the identification of the location of peak activity and in brain tumor follow-up monitoring using clinical FET PET metrics.Conclusions: Overall, we found RESOLUTE to be the AC method that most robustly

  19. Activation of sensory cortex by imagined genital stimulation: an fMRI analysis

    Directory of Open Access Journals (Sweden)

    Nan J. Wise

    2016-10-01

    Full Text Available Background: During the course of a previous study, our laboratory made a serendipitous finding that just thinking about genital stimulation resulted in brain activations that overlapped with, and differed from, those generated by physical genital stimulation. Objective: This study extends our previous findings by further characterizing how the brain differentially processes physical ‘touch’ stimulation and ‘imagined’ stimulation. Design: Eleven healthy women (age range 29–74 participated in an fMRI study of the brain response to imagined or actual tactile stimulation of the nipple and clitoris. Two additional conditions – imagined dildo self-stimulation and imagined speculum stimulation – were included to characterize the effects of erotic versus non-erotic imagery. Results: Imagined and tactile self-stimulation of the nipple and clitoris each activated the paracentral lobule (the genital region of the primary sensory cortex and the secondary somatosensory cortex. Imagined self-stimulation of the clitoris and nipple resulted in greater activation of the frontal pole and orbital frontal cortex compared to tactile self-stimulation of these two bodily regions. Tactile self-stimulation of the clitoris and nipple activated the cerebellum, primary somatosensory cortex (hand region, and premotor cortex more than the imagined stimulation of these body regions. Imagining dildo stimulation generated extensive brain activation in the genital sensory cortex, secondary somatosensory cortex, hippocampus, amygdala, insula, nucleus accumbens, and medial prefrontal cortex, whereas imagining speculum stimulation generated only minimal activation. Conclusion: The present findings provide evidence of the potency of imagined stimulation of the genitals and that the following brain regions may participate in erogenous experience: primary and secondary sensory cortices, sensory-motor integration areas, limbic structures, and components of the

  20. Activation of sensory cortex by imagined genital stimulation: an fMRI analysis.

    Science.gov (United States)

    Wise, Nan J; Frangos, Eleni; Komisaruk, Barry R

    2016-01-01

    During the course of a previous study, our laboratory made a serendipitous finding that just thinking about genital stimulation resulted in brain activations that overlapped with, and differed from, those generated by physical genital stimulation. This study extends our previous findings by further characterizing how the brain differentially processes physical 'touch' stimulation and 'imagined' stimulation. Eleven healthy women (age range 29-74) participated in an fMRI study of the brain response to imagined or actual tactile stimulation of the nipple and clitoris. Two additional conditions - imagined dildo self-stimulation and imagined speculum stimulation - were included to characterize the effects of erotic versus non-erotic imagery. Imagined and tactile self-stimulation of the nipple and clitoris each activated the paracentral lobule (the genital region of the primary sensory cortex) and the secondary somatosensory cortex. Imagined self-stimulation of the clitoris and nipple resulted in greater activation of the frontal pole and orbital frontal cortex compared to tactile self-stimulation of these two bodily regions. Tactile self-stimulation of the clitoris and nipple activated the cerebellum, primary somatosensory cortex (hand region), and premotor cortex more than the imagined stimulation of these body regions. Imagining dildo stimulation generated extensive brain activation in the genital sensory cortex, secondary somatosensory cortex, hippocampus, amygdala, insula, nucleus accumbens, and medial prefrontal cortex, whereas imagining speculum stimulation generated only minimal activation. The present findings provide evidence of the potency of imagined stimulation of the genitals and that the following brain regions may participate in erogenous experience: primary and secondary sensory cortices, sensory-motor integration areas, limbic structures, and components of the 'reward system'. In addition, these results suggest a mechanism by which some individuals may

  1. fMRI activation in relation to sound intensity and loudness

    NARCIS (Netherlands)

    Langers, Dave R. M.; van Dijk, Pirn; Schoemaker, Esther S.; Backes, Walter H.

    2007-01-01

    The aim of this fMRI study was to relate cortical fMRI responses to both physical and perceptual sound level characteristics. Besides subjects with normal hearing, subjects with high-frequency sensorineural hearing loss were included, as distortion of loudness perception is a characteristic of such

  2. MRI findings in men on active surveillance for prostate cancer. Does dutasteride make MRI visible lesions less conspicuous? Results from a placebo-controlled, randomised clinical trial

    Energy Technology Data Exchange (ETDEWEB)

    Giganti, Francesco [University College London Hospital NHS Foundation Trust, Department of Radiology, London (United Kingdom); University College London, Division of Surgery and Interventional Science, London (United Kingdom); Moore, Caroline M.; Robertson, Nicola L.; Emberton, Mark [University College London, Division of Surgery and Interventional Science, London (United Kingdom); University College London Hospital NHS Foundation Trust, Department of Urology, London (United Kingdom); McCartan, Neil [University College London, Division of Surgery and Interventional Science, London (United Kingdom); Jameson, Charles [University College London Hospital NHS Foundation Trust, Department of Pathology, London (United Kingdom); Bott, Simon R.J. [Frimley Park Hospital, Department of Urology, Surrey (United Kingdom); Winkler, Mathias [Imperial College NHS Trust, Department of Urology, Charing Cross Hospital, London (United Kingdom); Gambarota, Giulio [INSERM, Rennes (France); Universite de Rennes 1, Rennes (France); Whitcher, Brandon [Klarismo, London (United Kingdom); Imperial College London, Department of Mathematics, London (United Kingdom); Castro, Ramiro [GlaxoSmithKline, Research and Development, Philadelphia, PA (United States); Allen, Clare; Kirkham, Alex [University College London Hospital NHS Foundation Trust, Department of Radiology, London (United Kingdom)

    2017-11-15

    To investigate changes in the Apparent Diffusion Coefficient (ADC) using diffusion-weighted imaging (DWI) in men on active surveillance for prostate cancer taking dutasteride 0.5 mg or placebo. We analysed 37 men, randomised to 6 months of daily dutasteride (n = 18) or placebo (n = 19), undergoing 3T multi-parametric Magnetic Resonance Imaging (mpMRI) scans at baseline and 6 months. Images were reviewed blind to treatment allocation and clinical information. Mean ADC of peripheral (PZ) and transition (TZ) zones, and MR-suspicious lesions were compared between groups over 6 months. Conspicuity was defined as the PZ divided by tumour ADC, and its change over 6 months was assessed. A decrease in mean conspicuity in the dutasteride group (but not the controls) was seen over 6 months (1.54 vs 1.38; p = 0.025). Absolute changes in ADC and conspicuity were significantly different between placebo and dutasteride groups at 6 months: (-0.03 vs 0.08, p = 0.033) and (0.11 vs -0.16, p = 0.012), as were percentage changes in the same parameters: (-2.27% vs 8.56% p = 0.048) and (9.25% vs -9.89% p = 0.013). Dutasteride was associated with increased tumour ADC and reduced conspicuity. A lower threshold for triggering biopsy might be considered in men on dutasteride undergoing mpMRI for prostate cancer. (orig.)

  3. Neural Activations of Guided Imagery and Music in Negative Emotional Processing: A Functional MRI Study.

    Science.gov (United States)

    Lee, Sang Eun; Han, Yeji; Park, HyunWook

    2016-01-01

    The Bonny Method of Guided Imagery and Music uses music and imagery to access and explore personal emotions associated with episodic memories. Understanding the neural mechanism of guided imagery and music (GIM) as combined stimuli for emotional processing informs clinical application. We performed functional magnetic resonance imaging (fMRI) to demonstrate neural mechanisms of GIM for negative emotional processing when personal episodic memory is recalled and re-experienced through GIM processes. Twenty-four healthy volunteers participated in the study, which used classical music and verbal instruction stimuli to evoke negative emotions. To analyze the neural mechanism, activated regions associated with negative emotional and episodic memory processing were extracted by conducting volume analyses for the contrast between GIM and guided imagery (GI) or music (M). The GIM stimuli showed increased activation over the M-only stimuli in five neural regions associated with negative emotional and episodic memory processing, including the left amygdala, left anterior cingulate gyrus, left insula, bilateral culmen, and left angular gyrus (AG). Compared with GI alone, GIM showed increased activation in three regions associated with episodic memory processing in the emotional context, including the right posterior cingulate gyrus, bilateral parahippocampal gyrus, and AG. No neural regions related to negative emotional and episodic memory processing showed more activation for M and GI than for GIM. As a combined multimodal stimulus, GIM may increase neural activations related to negative emotions and episodic memory processing. Findings suggest a neural basis for GIM with personal episodic memories affecting cortical and subcortical structures and functions. © the American Music Therapy Association 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Electrical Activation Studies of Silicon Implanted Aluminum Gallium Nitride with High Aluminum Mole Fraction

    National Research Council Canada - National Science Library

    Moore, Elizabeth A

    2007-01-01

    ...) alloys, and represents a comprehensive analysis of the resulting material's electrical and optical properties as a function of Al mole fraction, anneal temperature, anneal time, and implantation dose...

  5. TIMP-1 resistant matrix metalloproteinase-9 is the predominant serum active isoform associated with MRI activity in patients with multiple sclerosis.

    Science.gov (United States)

    Trentini, Alessandro; Manfrinato, Maria C; Castellazzi, Massimiliano; Tamborino, Carmine; Roversi, Gloria; Volta, Carlo A; Baldi, Eleonora; Tola, Maria R; Granieri, Enrico; Dallocchio, Franco; Bellini, Tiziana; Fainardi, Enrico

    2015-08-01

    The activity of matrix metalloproteinase-9 (MMP-9) depends on two isoforms, an 82 kDa active MMP-9 modulated by its specific tissue inhibitor (TIMP-1), and a 65 kDa TIMP-1 resistant active MMP-9. The relevance of these two enzymatic isoforms in multiple sclerosis (MS) is still unknown. To investigate the contribution of the TIMP-1 modulated and resistant active MMP-9 isoforms to MS pathogenesis. We measured the serum levels of the 82 kDa and TIMP-1 resistant active MMP-9 isoforms by activity assay systems in 86 relapsing-remitting MS (RRMS) patients, categorized according to clinical and magnetic resonance imaging (MRI) evidence of disease activity, and in 70 inflammatory (OIND) and 69 non-inflammatory (NIND) controls. Serum levels of TIMP-1 resistant MMP-9 were more elevated in MS patients than in OIND and NIND (p < 0.05, p < 0.02, respectively). Conversely, 82 kDa active MMP-9 was higher in NIND than in the OIND and MS patients (p < 0.01 and p < 0.00001, respectively). MRI-active patients had higher levels of TIMP-1 resistant MMP-9 and 82 kDa active MMP-9, than did those with MRI inactive MS (p < 0.01 and p < 0.05, respectively). Our findings suggested that the TIMP-1 resistant MMP-9 seem to be the predominantly active isoform contributing to MS disease activity. © The Author(s), 2015.

  6. Application of fMRI to obesity research: differences in reward pathway activation measured with fMRI BOLD during visual presentation of high and low calorie foods

    Science.gov (United States)

    Tsao, Sinchai; Adam, Tanja C.; Goran, Michael I.; Singh, Manbir

    2012-03-01

    The factors behind the neural mechanisms that motivate food choice and obesity are not well known. Furthermore, it is not known when these neural mechanisms develop and how they are influenced by both genetic and environmental factors. This study uses fMRI together with clinical data to shed light on the aforementioned questions by investigating how appetite-related activation in the brain changes with low versus high caloric foods in pre-pubescent girls. Previous studies have shown that obese adults have less striatal D2 receptors and thus reduced Dopamine (DA) signaling leading to the reward-deficit theory of obesity. However, overeating in itself reduces D2 receptor density, D2 sensitivity and thus reward sensitivity. The results of this study will show how early these neural mechanisms develop and what effect the drastic endocrinological changes during puberty has on these mechanisms. Our preliminary results showed increased activations in the Putamen, Insula, Thalamus and Hippocampus when looking at activations where High Calorie > Low Calorie. When comparing High Calorie > Control and Low Calorie > Control, the High > Control test showed increased significant activation in the frontal lobe. The Low > Control also yielded significant activation in the Left and Right Fusiform Gyrus, which did not appear in the High > Control test. These results indicate that the reward pathway activations previously shown in post-puberty and adults are present in pre-pubescent teens. These results may suggest that some of the preferential neural mechanisms of reward are already present pre-puberty.

  7. Combining task-evoked and spontaneous activity to improve pre-operative brain mapping with fMRI

    Science.gov (United States)

    Fox, Michael D.; Qian, Tianyi; Madsen, Joseph R.; Wang, Danhong; Li, Meiling; Ge, Manling; Zuo, Huan-cong; Groppe, David M.; Mehta, Ashesh D.; Hong, Bo; Liu, Hesheng

    2016-01-01

    Noninvasive localization of brain function is used to understand and treat neurological disease, exemplified by pre-operative fMRI mapping prior to neurosurgical intervention. The principal approach for generating these maps relies on brain responses evoked by a task and, despite known limitations, has dominated clinical practice for over 20 years. Recently, pre-operative fMRI mapping based on correlations in spontaneous brain activity has been demonstrated, however this approach has its own limitations and has not seen widespread clinical use. Here we show that spontaneous and task-based mapping can be performed together using the same pre-operative fMRI data, provide complimentary information relevant for functional localization, and can be combined to improve identification of eloquent motor cortex. Accuracy, sensitivity, and specificity of our approach are quantified through comparison with electrical cortical stimulation mapping in eight patients with intractable epilepsy. Broad applicability and reproducibility of our approach is demonstrated through prospective replication in an independent dataset of six patients from a different center. In both cohorts and every individual patient, we see a significant improvement in signal to noise and mapping accuracy independent of threshold, quantified using receiver operating characteristic curves. Collectively, our results suggest that modifying the processing of fMRI data to incorporate both task-based and spontaneous activity significantly improves functional localization in pre-operative patients. Because this method requires no additional scan time or modification to conventional pre-operative data acquisition protocols it could have widespread utility. PMID:26408860

  8. Prophylactic Cranial Irradiation (PCI) versus Active MRI Surveillance for Small Cell Lung Cancer: The Case for Equipoise.

    Science.gov (United States)

    Rusthoven, Chad G; Kavanagh, Brian D

    2017-12-01

    Prophylactic cranial irradiation (PCI) for SCLC offers a consistent reduction in the incidence of brain metastases at the cost of measurable toxicity to neurocognitive function and quality of life, in the setting of characteristic pathologic changes to the brain. The sequelae of PCI have historically been justified by the perception of an overall survival advantage specific to SCLC. This rationale has now been challenged by a randomized trial in extensive-stage SCLC demonstrating equivalent progression-free survival and a trend toward improved overall survival with PCI omission in the context of modern magnetic resonance imaging (MRI) staging and surveillance. In this article, we critically examine the randomized trials of PCI in extensive-stage SCLC and discuss their implications on the historical data supporting PCI for limited-stage SCLC from the pre-MRI era. Further, we review the toxicity of moderate doses of radiation to the entire brain that underlie the growing interest in active MRI surveillance and PCI omission. Finally, the evidence supporting prospective investigation of radiosurgery for limited brain metastases in SCLC is reviewed. Overall, our aim is to provide an evidence-based assessment of the debate over PCI versus active MRI surveillance and to highlight the need for contemporary trials evaluating optimal central nervous system management in SCLC. Copyright © 2017 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

  9. Complete p-type activation in vertical-gradient freeze GaAs co-implanted with gallium and carbon

    Science.gov (United States)

    Horng, S. T.; Goorsky, M. S.

    1996-03-01

    High-resolution triple-axis x-ray diffractometry and Hall-effect measurements were used to characterize damage evolution and electrical activation in gallium arsenide co-implanted with gallium and carbon ions. Complete p-type activation of GaAs co-implanted with 5×1014 Ga cm-2 and 5×1014 C cm-2 was achieved after rapid thermal annealing at 1100 °C for 10 s. X-ray diffuse scattering was found to increase after rapid thermal annealing at 600-900 °C due to the aggregation of implantation-induced point defects. In this annealing range, there was ˜10%-72% activation. After annealing at higher annealing temperatures, the diffuse scattered intensity decreased drastically; samples that had been annealed at 1000 °C (80% activated) and 1100 °C (˜100% activated) exhibited reciprocal space maps that were indicative of high crystallinity. The hole mobility was about 60 cm2/V s for all samples annealed at 800 °C and above, indicating that the crystal perfection influences dopant activation more strongly than it influences mobility. Since the high-temperature annealing simultaneously increases dopant activation and reduces x-ray diffuse scattering, we conclude that point defect complexes which form at lower annealing temperatures are responsible for both the diffuse scatter and the reduced activation.

  10. Activations in temporal areas using visual and auditory naming stimuli: A language fMRI study in temporal lobe epilepsy.

    Science.gov (United States)

    Gonzálvez, Gloria G; Trimmel, Karin; Haag, Anja; van Graan, Louis A; Koepp, Matthias J; Thompson, Pamela J; Duncan, John S

    2016-12-01

    Verbal fluency functional MRI (fMRI) is used for predicting language deficits after anterior temporal lobe resection (ATLR) for temporal lobe epilepsy (TLE), but primarily engages frontal lobe areas. In this observational study we investigated fMRI paradigms using visual and auditory stimuli, which predominately involve language areas resected during ATLR. Twenty-three controls and 33 patients (20 left (LTLE), 13 right (RTLE)) were assessed using three fMRI paradigms: verbal fluency, auditory naming with a contrast of auditory reversed speech; picture naming with a contrast of scrambled pictures and blurred faces. Group analysis showed bilateral temporal activations for auditory naming and picture naming. Correcting for auditory and visual input (by subtracting activations resulting from auditory reversed speech and blurred pictures/scrambled faces respectively) resulted in left-lateralised activations for patients and controls, which was more pronounced for LTLE compared to RTLE patients. Individual subject activations at a threshold of T>2.5, extent >10 voxels, showed that verbal fluency activated predominantly the left inferior frontal gyrus (IFG) in 90% of LTLE, 92% of RTLE, and 65% of controls, compared to right IFG activations in only 15% of LTLE and RTLE and 26% of controls. Middle temporal (MTG) or superior temporal gyrus (STG) activations were seen on the left in 30% of LTLE, 23% of RTLE, and 52% of controls, and on the right in 15% of LTLE, 15% of RTLE, and 35% of controls. Auditory naming activated temporal areas more frequently than did verbal fluency (LTLE: 93%/73%; RTLE: 92%/58%; controls: 82%/70% (left/right)). Controlling for auditory input resulted in predominantly left-sided temporal activations. Picture naming resulted in temporal lobe activations less frequently than did auditory naming (LTLE 65%/55%; RTLE 53%/46%; controls 52%/35% (left/right)). Controlling for visual input had left-lateralising effects. Auditory and picture naming activated

  11. Modulation of functionally localized right insular cortex activity using real-time fMRI-based neurofeedback

    Directory of Open Access Journals (Sweden)

    Brian D Berman

    2013-10-01

    Full Text Available The capacity for subjects to learn to volitionally control localized brain activity using neurofeedback is actively being investigated. We aimed to investigate the ability of healthy volunteers to quickly learn to use visual feedback during real-time functional MRI (rtfMRI to modulate brain activity within their anterior right insular cortex (RIC localized during a blink suppression task, an approach of possible interest in the use of rtfMRI to reduce urges. The RIC region of interest (RIC-ROI was functionally localized using a blink suppression task, and BOLD signal changes within RIC-ROI used to create a constantly updating display fed back to the subject in the scanner. Subjects were instructed to use emotional imagery to try and increase activity within RIC-ROI during four feedback training runs (FB1–FB4. A ‘control’ run (CNTRL before training and a ‘transfer’ run (XSFR after training were performed without feedback to assess for baseline abilities and learning effects. Fourteen participants completed all neurofeedback training runs. At the group level, increased BOLD activity was seen in the anterior RIC during all the FB runs, but a significant increase in the functionally defined RIC-ROI was only attained during FB2. In atlas-defined insular cortex ROIs, significant increases were seen bilaterally during the CNTRL, FB1, FB2, and FB4 runs. Increased activity within the insular cortices did not show lateralization. Training did, however, result in a significant increase in functional connectivity between the RIC-ROI and the medial frontal gyrus when comparing FB4 to FB1. Since neurofeedback training did not lead to an increase in BOLD signal across all feedback runs, we suggest that learning to control one’s brain activity in this fashion may require longer or repeated rtfMRI training sessions.

  12. Abnormal baseline brain activity in patients with neuromyelitis optica: A resting-state fMRI study

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yaou [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Liang Peipeng [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); International WIC institute, Beijing University of Technology, Beijing 100024 (China); Duan Yunyun; Jia Xiuqin; Wang Fei; Yu Chunshui; Qin Wen [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Dong Huiqing; Ye Jing [Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Li Kuncheng, E-mail: likuncheng1955@yahoo.com.cn [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China)

    2011-11-15

    Purpose: Recent immunopathologic and MRI findings suggest that tissue damage in neuromyelitis optica (NMO) is not limited to spinal cord and optic nerve, but also in brain. Baseline brain activity can reveal the brain functional changes to the tissue damages and give clues to the pathophysiology of NMO, however, it has never been explored by resting-state functional MRI (fMRI). We used regional amplitude of low frequency fluctuation (ALFF) as an index in resting-state fMRI to investigate how baseline brain activity changes in patients with NMO. Methods: Resting-state fMRIs collected from seventeen NMO patients and seventeen age- and sex-matched normal controls were compared to investigate the ALFF difference between the two groups. The relationships between ALFF in regions with significant group differences and the EDSS (Expanded Disability Status Scale), disease duration were further explored. Results: Our results showed that NMO patients had significantly decreased ALFF in precuneus, posterior cingulate cortex (PCC) and lingual gyrus; and increased ALFF in middle frontal gyrus, caudate nucleus and thalamus, compared to normal controls. Moderate negative correlations were found between the EDSS and ALFF in the left middle frontal gyrus (r = -0.436, p = 0.040) and the left caudate (r = -0.542, p = 0.012). Conclusion: The abnormal baseline brain activity shown by resting-state fMRI in NMO is relevant to cognition, visual and motor systems. It implicates a complex baseline brain status of both functional impairments and adaptations caused by tissue damages in these systems, which gives clues to the pathophysiology of NMO.

  13. Abnormal baseline brain activity in patients with neuromyelitis optica: A resting-state fMRI study

    International Nuclear Information System (INIS)

    Liu Yaou; Liang Peipeng; Duan Yunyun; Jia Xiuqin; Wang Fei; Yu Chunshui; Qin Wen; Dong Huiqing; Ye Jing; Li Kuncheng

    2011-01-01

    Purpose: Recent immunopathologic and MRI findings suggest that tissue damage in neuromyelitis optica (NMO) is not limited to spinal cord and optic nerve, but also in brain. Baseline brain activity can reveal the brain functional changes to the tissue damages and give clues to the pathophysiology of NMO, however, it has never been explored by resting-state functional MRI (fMRI). We used regional amplitude of low frequency fluctuation (ALFF) as an index in resting-state fMRI to investigate how baseline brain activity changes in patients with NMO. Methods: Resting-state fMRIs collected from seventeen NMO patients and seventeen age- and sex-matched normal controls were compared to investigate the ALFF difference between the two groups. The relationships between ALFF in regions with significant group differences and the EDSS (Expanded Disability Status Scale), disease duration were further explored. Results: Our results showed that NMO patients had significantly decreased ALFF in precuneus, posterior cingulate cortex (PCC) and lingual gyrus; and increased ALFF in middle frontal gyrus, caudate nucleus and thalamus, compared to normal controls. Moderate negative correlations were found between the EDSS and ALFF in the left middle frontal gyrus (r = -0.436, p = 0.040) and the left caudate (r = -0.542, p = 0.012). Conclusion: The abnormal baseline brain activity shown by resting-state fMRI in NMO is relevant to cognition, visual and motor systems. It implicates a complex baseline brain status of both functional impairments and adaptations caused by tissue damages in these systems, which gives clues to the pathophysiology of NMO.

  14. Electrical activation of solid-phase epitaxially regrown ultra-low energy boron implants in Ge preamorphised silicon and SOI

    International Nuclear Information System (INIS)

    Hamilton, J.J.; Collart, E.J.H.; Colombeau, B.; Jeynes, C.; Bersani, M.; Giubertoni, D.; Sharp, J.A.; Cowern, N.E.B.; Kirkby, K.J.

    2005-01-01

    The formation of highly activated ultra-shallow junctions (USJ) is one of the key requirements for the next generation of CMOS devices. One promising method for achieving this is the use of Ge preamorphising implants (PAI) prior to ultra-low energy B implantation. In future technology nodes, bulk silicon wafers may be supplanted by Silicon-on-Insulator (SOI), and an understanding of the Solid Phase Epitaxial (SPE) regrowth process and its correlation to dopant electrical activation in both bulk silicon and SOI is essential in order to understand the impact of this potential technology change. This kind of understanding will also enable tests of fundamental models for defect evolution and point-defect reactions at silicon/oxide interfaces. In the present work, B is implanted into Ge PAI silicon and SOI wafers with different PAI conditions and B doses, and resulting samples are annealed at various temperatures and times. Glancing-exit Rutherford Backscattering Spectrometry (RBS) is used to monitor the regrowth of the amorphous silicon, and the resulting redistribution and electrical activity of B are monitored by SIMS and Hall measurements. The results confirm the expected enhancement of regrowth velocity by B doping, and show that this velocity is otherwise independent of the substrate type and the Ge implant distribution within the amorphised layer. Hall measurements on isochronally annealed samples show that B deactivates less in SOI material than in bulk silicon, in cases where the Ge PAI end-of-range defects are close to the SOI back interface

  15. Baseline brain activity changes in patients with clinically isolated syndrome revealed by resting-state functional MRI

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yaou; Duan, Yunyun; Liang, Peipeng; Jia, Xiuqin; Yu, Chunshui [Dept. of Radiology, Xuanwu Hospital, Capital Medical Univ., Beijing (China); Ye, Jing [Dept. of Neurology, Xuanwu Hospital, Capital Medical Univ., Beijing (China); Butzkueven, Helmut [Dept. of Medicine, Univ. of Melbourne, Melbourne (Australia); Dong, Huiqing [Dept. of Neurology, Xuanwu Hospital, Capital Medical Univ., Beijing (China); Li, Kuncheng [Dept. of Radiology, Xuanwu Hospital, Capital Medical Univ., Beijing (China); Beijing Key Laboratory of MRI and Brain Informatics, Beijing (China)], E-mail: likuncheng1955@yahoo.com.cn

    2012-11-15

    Background A clinically isolated syndrome (CIS) is the first manifestation of multiple sclerosis (MS). Previous task-related functional MRI studies demonstrate functional reorganization in patients with CIS. Purpose To assess baseline brain activity changes in patients with CIS by using the technique of regional amplitude of low frequency fluctuation (ALFF) as an index in resting-state fMRI. Material and Methods Resting-state fMRIs data acquired from 37 patients with CIS and 37 age- and sex-matched normal controls were compared to investigate ALFF differences. The relationships between ALFF in regions with significant group differences and the EDSS (Expanded Disability Status Scale), disease duration, and T2 lesion volume (T2LV) were further explored. Results Patients with CIS had significantly decreased ALFF in the right anterior cingulate cortex, right caudate, right lingual gyrus, and right cuneus (P < 0.05 corrected for multiple comparisons using Monte Carlo simulation) compared to normal controls, while no significantly increased ALFF were observed in CIS. No significant correlation was found between the EDSS, disease duration, T2LV, and ALFF in regions with significant group differences. Conclusion In patients with CIS, resting-state fMRI demonstrates decreased activity in several brain regions. These results are in contrast to patients with established MS, in whom ALFF demonstrates several regions of increased activity. It is possible that this shift from decreased activity in CIS to increased activity in MS could reflect the dynamics of cortical reorganization.

  16. Correlated alpha activity with the facial expression processing network in a simultaneous EEG-fMRI experiment.

    Science.gov (United States)

    Simoes, Marco; Direito, Bruno; Lima, Joao; Castelhano, Joao; Ferreira, Carlos; Couceiro, Ricardo; Carvalho, Paulo; Castelo-Branco, Miguel

    2017-07-01

    The relationship between EEG and fMRI data is poorly covered in the literature. Extensive work has been conducted in resting-state and epileptic activity, highlighting a negative correlation between the alpha power band of the EEG and the BOLD activity in the default-mode-network. The identification of an appropriate task-specific relationship between fMRI and EEG data for predefined regions-of-interest, would allow the transfer of interventional paradigms (such as BOLD-based neurofeedback sessions) from fMRI to EEG, enhancing its application range by lowering its costs and improving its flexibility. In this study, we present an analysis of the correlation between task-specific alpha band fluctuations and BOLD activity in the facial expressions processing network. We characterized the network ROIs through a stringent localizer and identified two clusters on the scalp (one frontal, one parietal-occipital) with marked alpha fluctuations, related to the task. We then check whether such power variations throughout the time correlate with the BOLD activity in the network. Our results show statistically significant negative correlations between the alpha power in both clusters and for all the ROIs of the network. The correlation levels have still not met the requirements for transferring the protocol to an EEG setup, but they pave the way towards a better understand on how frontal and parietal-occipital alpha relates to the activity of the facial expressions processing network.

  17. Cortical activities of single-trial P300 amplitudes modulated by memory load using simultaneous EEG-fMRI

    Science.gov (United States)

    Zhang, Qiushi; Zhao, Xiaojie; Zhu, Chaozhe; Yang, Xueqian; Yao, Li

    2015-03-01

    The functional magnetic resonance imaging (fMRI) researches on working memory have found that activation of cortical areas appeared dependent on memory load, and event-related potentials (ERP) studies have demonstrated that amplitudes of P300 decreased significantly when working memory load increased. However, the cortical activities related with P300 amplitudes under different memory loads remains unclear. Joint fMRI and EEG analysis which fusions the time and spatial information in simultaneous EEG-fMRI recording can reveal the regional activation at each ERP time point. In this paper, we first used wavelet transform to obtain the single-trial amplitudes of P300 caused by a digital N-back task in the simultaneous EEG-fMRI recording as the ERP feature sequences. Then the feature sequences in 1-back condition and 3-back condition were introduced into general linear model (GLM) separately as parametric modulations to compare the cortical activation under different memory loads. The results showed that the average amplitudes of P300 in 3-back significantly decreased than that in 1-back, and the activities induced by ERP feature sequences in 3-back also significantly decreased than that in the 1-back, including the insular, anterior cingulate cortex, right inferior frontal gyrus, and medial frontal gyrus, which were relevant to the storage, monitoring, and manipulation of information in working memory task. Moreover, the difference in the activation caused by ERP feature showed a positive correlation with the difference in behavioral performance. These findings demonstrated the locations of P300 amplitudes differences modulated by the memory load and its relationship with the behavioral performance.

  18. Topologic analysis and comparison of brain activation in children with epilepsy versus controls: an fMRI study

    Science.gov (United States)

    Oweis, Khalid J.; Berl, Madison M.; Gaillard, William D.; Duke, Elizabeth S.; Blackstone, Kaitlin; Loew, Murray H.; Zara, Jason M.

    2010-03-01

    This paper describes the development of novel computer-aided analysis algorithms to identify the language activation patterns at a certain Region of Interest (ROI) in Functional Magnetic Resonance Imaging (fMRI). Previous analysis techniques have been used to compare typical and pathologic activation patterns in fMRI images resulting from identical tasks but none of them analyzed activation topographically in a quantitative manner. This paper presents new analysis techniques and algorithms capable of identifying a pattern of language activation associated with localization related epilepsy. fMRI images of 64 healthy individuals and 31 patients with localization related epilepsy have been studied and analyzed on an ROI basis. All subjects are right handed with normal MRI scans and have been classified into three age groups (4-6, 7-9, 10-12 years). Our initial efforts have focused on investigating activation in the Left Inferior Frontal Gyrus (LIFG). A number of volumetric features have been extracted from the data. The LIFG has been cut into slices and the activation has been investigated topographically on a slice by slice basis. Overall, a total of 809 features have been extracted, and correlation analysis was applied to eliminate highly correlated features. Principal Component analysis was then applied to account only for major components in the data and One-Way Analysis of Variance (ANOVA) has been applied to test for significantly different features between normal and patient groups. Twenty Nine features have were found to be significantly different (p<0.05) between patient and control groups

  19. Nouns, verbs, objects, actions, and abstractions: local fMRI activity indexes semantics, not lexical categories.

    Science.gov (United States)

    Moseley, Rachel L; Pulvermüller, Friedemann

    2014-05-01

    Noun/verb dissociations in the literature defy interpretation due to the confound between lexical category and semantic meaning; nouns and verbs typically describe concrete objects and actions. Abstract words, pertaining to neither, are a critical test case: dissociations along lexical-grammatical lines would support models purporting lexical category as the principle governing brain organisation, whilst semantic models predict dissociation between concrete words but not abstract items. During fMRI scanning, participants read orthogonalised word categories of nouns and verbs, with or without concrete, sensorimotor meaning. Analysis of inferior frontal/insula, precentral and central areas revealed an interaction between lexical class and semantic factors with clear category differences between concrete nouns and verbs but not abstract ones. Though the brain stores the combinatorial and lexical-grammatical properties of words, our data show that topographical differences in brain activation, especially in the motor system and inferior frontal cortex, are driven by semantics and not by lexical class. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  20. Training readers to improve their accuracy in grading Crohn's disease activity on MRI

    International Nuclear Information System (INIS)

    Tielbeek, Jeroen A.W.; Bipat, Shandra; Boellaard, Thierry N.; Nio, C.Y.; Stoker, Jaap

    2014-01-01

    To prospectively evaluate if training with direct feedback improves grading accuracy of inexperienced readers for Crohn's disease activity on magnetic resonance imaging (MRI). Thirty-one inexperienced readers assessed 25 cases as a baseline set. Subsequently, all readers received training and assessed 100 cases with direct feedback per case, randomly assigned to four sets of 25 cases. The cases in set 4 were identical to the baseline set. Grading accuracy, understaging, overstaging, mean reading times and confidence scores (scale 0-10) were compared between baseline and set 4, and between the four consecutive sets with feedback. Proportions of grading accuracy, understaging and overstaging per set were compared using logistic regression analyses. Mean reading times and confidence scores were compared by t-tests. Grading accuracy increased from 66 % (95 % CI, 56-74 %) at baseline to 75 % (95 % CI, 66-81 %) in set 4 (P = 0.003). Understaging decreased from 15 % (95 % CI, 9-23 %) to 7 % (95 % CI, 3-14 %) (P < 0.001). Overstaging did not change significantly (20 % vs 19 %). Mean reading time decreased from 6 min 37 s to 4 min 35 s (P < 0.001). Mean confidence increased from 6.90 to 7.65 (P < 0.001). During training, overall grading accuracy, understaging, mean reading times and confidence scores improved gradually. Inexperienced readers need training with at least 100 cases to achieve the literature reported grading accuracy of 75 %. (orig.)

  1. fMRI-activation during drawing a naturalistic or sketchy portrait.

    Science.gov (United States)

    Schaer, K; Jahn, G; Lotze, M

    2012-07-15

    Neural processes for naturalistic drawing might be discerned into object recognition and analysis, attention processes guiding eye hand interaction, encoding of visual features in an allocentric reference frame, a transfer into the motor command and precise motor guidance with tight sensorimotor feedback. Cerebral representations in a real life paradigm during naturalistic drawing have sparsely been investigated. Using a functional Magnetic Resonance Imaging (fMRI) paradigm we measured 20 naive subjects during drawing a portrait from a frontal face presented as a photograph. Participants were asked to draw the portrait in either a naturalistic or a sketchy characteristic way. Tracing the contours of the face with a pencil or passive viewing of the face served as control conditions. Compared to passive viewing, naturalistic and sketchy drawing recruited predominantly the dorsal visual pathway, somatosensory and motor areas and bilateral BA 44. The right occipital lobe, middle temporal (MT) and the fusiform face area were increasingly active during drawing compared to passive viewing as well. Compared to tracing with a pencil, both drawing tasks increasingly involved the bilateral precuneus together with the cuneus and right inferior temporal lobe. Overall, our study identified cerebral areas characteristic for previously proposed aspects of drawing: face perception and analysis (fusiform gyrus and higher visual areas), encoding and retrieval of locations in an allocentric reference frame (precuneus), and continuous feedback processes during motor output (parietal sulcus, cerebellar hemisphere). Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Effects of taurine on resting-state fMRI activity in spontaneously hypertensive rats.

    Science.gov (United States)

    Chen, Vincent Chin-Hung; Hsu, Tsai-Ching; Chen, Li-Jeng; Chou, Hong-Chun; Weng, Jun-Cheng; Tzang, Bor-Show

    2017-01-01

    Attention deficit hyperactivity disorder (ADHD) is a global behavior illness among children and adults. To investigate the effects of taurine on resting-state fMRI activity in ADHD, a spontaneously hypertensive rat (SHR) animal model was adopted. Significantly decreased serum C-reactive protein (CRP) was detected in rats of Wistar Kyoto (WKY) high-taurine group and significantly decreased interleukin (IL)-1β and CRP were detected in rats of SHR low-taurine and high-taurine groups. Moreover, significantly higher horizontal locomotion was detected in rats of WKY low-taurine and SHR low-taurine groups than in those of controls. In contrast, significantly lower horizontal locomotion was detected in rats of the SHR high-taurine group than in those of the SHR control group. Additionally, significantly lower functional connectivity (FC) and mean amplitude of low-frequency fluctuation (mALFF) in the bilateral hippocampus in rats of WKY high-taurine and SHR high-taurine groups was detected. Notably, the mALFF in rats of the SHR low-taurine and high-taurine groups was significantly lower than in those of the SHR control group. These findings suggest that the administration of a high-dose taurine probably improves hyperactive behavior in SHR rats by ameliorating the inflammatory cytokines and modulating brain functional signals in SHR rats.

  3. The use of UML activity diagrams and the i* language in the modeling of the balanced scorecard implantation process

    OpenAIRE

    Haya, Mariela; Franch, Xavier; Mayol, Enric

    2005-01-01

    Business management is a complex task that can be facilitated using different methodologies and models. One of their most relevant purposes is to align the organization strategy with the daily functioning of the organization. One of these models is the Balanced Scorecard (BSC). In this paper, we propose a modeling strategy for the BSC implantation process. We will model it using UML Activity Diagrams and Strategy Dependency models of the language i*. The Activity Diagrams allow determining th...

  4. Hybrid PET/MRI insert: B0 field optimization by applying active and passive shimming on PET detector level

    Energy Technology Data Exchange (ETDEWEB)

    Wehner, Jakob [Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen (Germany); Weissler, Bjoern [Philips Research Europe, Aachen (Germany); Schulz, Volkmar [Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen (Germany); Philips Research Europe, Aachen (Germany)

    2014-07-29

    Combining PET and MRI into a hybrid device is challenging since both systems might influence each other. A typical interference problem of such a combined device is the distortion of the MRI’s B{sub 0} field distribution due to the material brought inside the MRI’s FOV which is in particular challenging for small-bore PET-systems. High field homogeneity is needed for a good MRI acquisition in general as well as in certain applications. Typically, active shimming using dedicated coils is applied to improve the field homogeneity. However, these techniques are limited especially for localized distortion profiles with higher-order characteristics caused by PET/MRI inserts. As a consequence, we are exploring the potential application of shimming on PET detector level (for the Hyperion-II{sup D} PET/MRI insert), meaning that the distortion profile caused by PET modules is compensated using additional magnetic materials (passive shimming) and DC coils (active shimming). To explore the technique, B{sub 0} field measurements have been performed using a whole-body phantom in combination with the MRI body coil. An FFE sequence was used to measure distortion maps of DC loops and small magnetic objects (capacitors, ferrites). These distortion maps served as input for a software framework which has been written to perform the field optimization. The implementation was verified by measurements and fits were performed to extract characteristic parameters of the tested objects. Finally, the implemented software framework was used to homogenize a measured distortion map produced by a single PET module by superimposing distortion corrections from additional simulated materials. The resulting superimposed distortion map showed a significantly improved B{sub 0} field map quality (reduced spectral width and improved homogeneity). The simulated susceptibility distribution will be applied on PET module level and tested in experiments. Results and details about this study will be

  5. PET/MRI of metabolic activity in osteoarthritis: A feasibility study.

    Science.gov (United States)

    Kogan, Feliks; Fan, Audrey P; McWalter, Emily J; Oei, Edwin H G; Quon, Andrew; Gold, Garry E

    2017-06-01

    To evaluate positron emission tomography / magnetic resonance imaging (PET/MRI) knee imaging to detect and characterize osseous metabolic abnormalities and correlate PET radiotracer uptake with osseous abnormalities and cartilage degeneration observed on MRI. Both knees of 22 subjects with knee pain or injury were scanned at one timepoint, without gadolinium, on a hybrid 3.0T PET-MRI system following injection of 18 F-fluoride or 18 F-fluorodeoxyglucose (FDG). A musculoskeletal radiologist identified volumes of interest (VOIs) around bone abnormalities on MR images and scored bone marrow lesions (BMLs) and osteophytes using a MOAKS scoring system. Cartilage appearance adjacent to bone abnormalities was graded with MRI-modified Outerbridge classifications. On PET standardized uptake values (SUV) maps, VOIs with SUV greater than 5 times the SUV in normal-appearing bone were identified as high-uptake VOI (VOI High ). Differences in 18 F-fluoride uptake between bone abnormalities, BML, and osteophyte grades and adjacent cartilage grades on MRI were identified using Mann-Whitney U-tests. SUV max in all subchondral bone lesions (BML, osteophytes, sclerosis) was significantly higher than that of normal-appearing bone on MRI (P subchondral bone on MRI. Furthermore, many small grade 1 osteophytes (40 of 82 [49%]), often described as the earliest signs of osteoarthritis (OA), did not show high uptake. Lastly, PET SUV max in subchondral bone adjacent to grade 0 cartilage was significantly lower compared to that of grades 1-2 (P subchondral bone, which appear normal on MRI. 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;45:1736-1745. © 2016 International Society for Magnetic Resonance in Medicine.

  6. Nitroxyl Modified Tobacco Mosaic Virus as a Metal-Free High-Relaxivity MRI and EPR Active Superoxide Sensor.

    Science.gov (United States)

    Dharmarwardana, Madushani; Martins, André F; Chen, Zhuo; Palacios, Philip M; Nowak, Chance M; Welch, Raymond P; Li, Shaobo; Luzuriaga, Michael A; Bleris, Leonidas; Pierce, Brad S; Sherry, A Dean; Gassensmith, Jeremiah J

    2018-05-29

    Superoxide overproduction is known to occur in multiple disease states requiring critical care; yet, noninvasive detection of superoxide in deep tissue remains a challenge. Herein, we report a metal-free magnetic resonance imaging (MRI) and electron paramagnetic resonance (EPR) active contrast agent prepared by "click conjugating" paramagnetic organic radical contrast agents (ORCAs) to the surface of tobacco mosaic virus (TMV). While ORCAs are known to be reduced in vivo to an MRI/EPR silent state, their oxidation is facilitated specifically by reactive oxygen species-in particular, superoxide-and are largely unaffected by peroxides and molecular oxygen. Unfortunately, single molecule ORCAs typically offer weak MRI contrast. In contrast, our data confirm that the macromolecular ORCA-TMV conjugates show marked enhancement for T 1 contrast at low field (<3.0 T) and T 2 contrast at high field (9.4 T). Additionally, we demonstrated that the unique topology of TMV allows for a "quenchless fluorescent" bimodal probe for concurrent fluorescence and MRI/EPR imaging, which was made possible by exploiting the unique inner and outer surface of the TMV nanoparticle. Finally, we show TMV-ORCAs do not respond to normal cellular respiration, minimizing the likelihood for background, yet still respond to enzymatically produced superoxide in complicated biological fluids like serum.

  7. A Combined Random Forests and Active Contour Model Approach for Fully Automatic Segmentation of the Left Atrium in Volumetric MRI

    Directory of Open Access Journals (Sweden)

    Chao Ma

    2017-01-01

    Full Text Available Segmentation of the left atrium (LA from cardiac magnetic resonance imaging (MRI datasets is of great importance for image guided atrial fibrillation ablation, LA fibrosis quantification, and cardiac biophysical modelling. However, automated LA segmentation from cardiac MRI is challenging due to limited image resolution, considerable variability in anatomical structures across subjects, and dynamic motion of the heart. In this work, we propose a combined random forests (RFs and active contour model (ACM approach for fully automatic segmentation of the LA from cardiac volumetric MRI. Specifically, we employ the RFs within an autocontext scheme to effectively integrate contextual and appearance information from multisource images together for LA shape inferring. The inferred shape is then incorporated into a volume-scalable ACM for further improving the segmentation accuracy. We validated the proposed method on the cardiac volumetric MRI datasets from the STACOM 2013 and HVSMR 2016 databases and showed that it outperforms other latest automated LA segmentation methods. Validation metrics, average Dice coefficient (DC and average surface-to-surface distance (S2S, were computed as 0.9227±0.0598 and 1.14±1.205 mm, versus those of 0.6222–0.878 and 1.34–8.72 mm, obtained by other methods, respectively.

  8. Resting-state fMRI activity predicts unsupervised learning and memory in an immersive virtual reality environment.

    Directory of Open Access Journals (Sweden)

    Chi Wah Wong

    Full Text Available In the real world, learning often proceeds in an unsupervised manner without explicit instructions or feedback. In this study, we employed an experimental paradigm in which subjects explored an immersive virtual reality environment on each of two days. On day 1, subjects implicitly learned the location of 39 objects in an unsupervised fashion. On day 2, the locations of some of the objects were changed, and object location recall performance was assessed and found to vary across subjects. As prior work had shown that functional magnetic resonance imaging (fMRI measures of resting-state brain activity can predict various measures of brain performance across individuals, we examined whether resting-state fMRI measures could be used to predict object location recall performance. We found a significant correlation between performance and the variability of the resting-state fMRI signal in the basal ganglia, hippocampus, amygdala, thalamus, insula, and regions in the frontal and temporal lobes, regions important for spatial exploration, learning, memory, and decision making. In addition, performance was significantly correlated with resting-state fMRI connectivity between the left caudate and the right fusiform gyrus, lateral occipital complex, and superior temporal gyrus. Given the basal ganglia's role in exploration, these findings suggest that tighter integration of the brain systems responsible for exploration and visuospatial processing may be critical for learning in a complex environment.

  9. Photocatalytic activity of ferric oxide/titanium dioxide nanocomposite films on stainless steel fabricated by anodization and ion implantation

    Science.gov (United States)

    Zhan, Wei-ting; Ni, Hong-wei; Chen, Rong-sheng; Yue, Gao; Tai, Jun-kai; Wang, Zi-yang

    2013-08-01

    A simple surface treatment was used to develop photocatalytic activity for stainless steel. AISI 304 stainless steel specimens after anodization were implanted by Ti ions at an extracting voltage of 50 kV with an implantation dose of 3 × 1015 atoms·cm-2 and then annealed in air at 450°C for 2 h. The morphology was observed by scanning electron microscopy. The microstructure was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The photocatalytic degradation of methylene blue solution was carried out under ultraviolet light. The corrosion resistance of the stainless steel was evaluated in NaCl solution (3.5 wt%) by electrochemical polarization curves. It is found that the Ti ions depth profile resembles a Gaussian distribution in the implanted layer. The nanostructured Fe2O3/TiO2 composite film exhibits a remarkable enhancement in photocatalytic activity referenced to the mechanically polished specimen and anodized specimen. Meanwhile, the annealed Ti-implanted specimen remains good corrosion resistance.

  10. Surface Engineering for Bone Implants: A Trend from Passive to Active Surfaces

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    John Jansen

    2012-07-01

    Full Text Available The mechanical and biological properties of bone implants need to be optimal to form a quick and firm connection with the surrounding environment in load bearing applications. Bone is a connective tissue composed of an organic collagenous matrix, a fine dispersion of reinforcing inorganic (calcium phosphate nanocrystals, and bone-forming and -degrading cells. These different components have a synergistic and hierarchical structure that renders bone tissue properties unique in terms of hardness, flexibility and regenerative capacity. Metallic and polymeric materials offer mechanical strength and/or resilience that are required to simulate bone tissue in load-bearing applications in terms of maximum load, bending and fatigue strength. Nevertheless, the interaction between devices and the surrounding tissue at the implant interface is essential for success or failure of implants. In that respect, coatings can be applied to facilitate the process of bone healing and obtain a continuous transition from living tissue to the synthetic implant. Compounds that are inspired by inorganic (e.g., hydroxyapatite crystals or organic (e.g., collagen, extracellular matrix components, enzymes components of bone tissue, are the most obvious candidates for application as implant coating to improve the performance of bone implants. This review provides an overview of recent trends and strategies in surface engineering that are currently investigated to improve the biological performance of bone implants in terms of functionality and biological efficacy.

  11. Pomegranate Juice Augments Memory and fMRI Activity in Middle-Aged and Older Adults with Mild Memory Complaints

    Directory of Open Access Journals (Sweden)

    Susan Y. Bookheimer

    2013-01-01

    Full Text Available Despite increasing emphasis on the potential of dietary antioxidants in preventing memory loss and on diet as a precursor of neurological health, rigorous studies investigating the cognitive effects of foods and their components are rare. Recent animal studies have reported memory and other cognitive benefits of polyphenols, found abundantly in pomegranate juice. We performed a preliminary, placebo-controlled randomized trial of pomegranate juice in older subjects with age-associated memory complaints using memory testing and functional brain activation (fMRI as outcome measures. Thirty-two subjects (28 completers were randomly assigned to drink 8 ounces of either pomegranate juice or a flavor-matched placebo drink for 4 weeks. Subjects received memory testing, fMRI scans during cognitive tasks, and blood draws for peripheral biomarkers before and after the intervention. Investigators and subjects were all blind to group membership. After 4 weeks, only the pomegranate group showed a significant improvement in the Buschke selective reminding test of verbal memory and a significant increase in plasma trolox-equivalent antioxidant capacity (TEAC and urolithin A-glucuronide. Furthermore, compared to the placebo group, the pomegranate group had increased fMRI activity during verbal and visual memory tasks. While preliminary, these results suggest a role for pomegranate juice in augmenting memory function through task-related increases in functional brain activity.

  12. Surgical outcomes of trabeculectomy and glaucoma drainage implant for uveitic glaucoma and relationship with uveitis activity.

    Science.gov (United States)

    Kwon, Hye Jin; Kong, Yu Xiang George; Tao, Lingwei William; Lim, Lyndell L; Martin, Keith R; Green, Catherine; Ruddle, Jonathan; Crowston, Jonathan G

    2017-07-01

    This study provides ophthalmologists who manage uveitic glaucoma with important information on factors that can affect the success of surgical management of this challenging disease. This study examines surgical outcomes of trabeculectomy and glaucoma device implant (GDI) surgery for uveitic glaucoma, in particular the effect of uveitis activity on surgical outcomes. Retrospective chart review at a tertiary institution. Eighty-two cases with uveitic glaucoma (54 trabeculectomies and 28 (GDI) surgeries) performed between 1 December 2006 and 30 November 2014. Associations of factors with surgical outcomes were examined using univariate and multivariate analysis. Surgical outcomes as defined in Guidelines from World Glaucoma Association. Average follow up was 26.4 ± 21.5 months. Overall qualified success rate of the trabeculectomies was not statistically different from GDI, being 67% and 75%, respectively (P = 0.60). Primary and secondary GDI operations showed similar success rates. The most common postoperative complication was hypotony (~30%). Active uveitis at the time of operation was higher in trabeculectomy compared with GDI group (35% vs. 14%). Active uveitis at the time of surgery did not significantly increase risk of failure for trabeculectomies. Recurrence of uveitis was significantly associated with surgical failure in trabeculectomy group (odds ratio 4.8, P = 0.02) but not in GDI group. Surgical success rate of GDI was not significantly different from trabeculectomy for uveitic glaucoma in this study. Regular monitoring, early and prolonged intensive treatment of ocular inflammation is important for surgical success particularly following trabeculectomy. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

  13. Defining active sacroiliitis on magnetic resonance imaging (MRI) for classification of axial spondyloarthritis: a consensual approach by the ASAS/OMERACT MRI group

    NARCIS (Netherlands)

    Rudwaleit, M.; Jurik, A. G.; Hermann, K.-G. A.; Landewé, R.; van der Heijde, D.; Baraliakos, X.; Marzo-Ortega, H.; Ostergaard, M.; Braun, J.; Sieper, J.

    2009-01-01

    Magnetic resonance imaging (MRI) of sacroiliac joints has evolved as the most relevant imaging modality for diagnosis and classification of early axial spondyloarthritis (SpA) including early ankylosing spondylitis. To identify and describe MRI findings in sacroiliitis and to reach consensus on

  14. An implantable two axis micromanipulator made with a 3D printer for recording neural activity in free-swimming fish.

    Science.gov (United States)

    Rogers, Loranzie S; Van Wert, Jacey C; Mensinger, Allen F

    2017-08-15

    Chronically implanted electrodes allow monitoring neural activity from free moving animals. While a wide variety of implanted headstages, microdrives and electrodes exist for terrestrial animals, few have been developed for use with aquatic animals. A two axis micromanipulator was fabricated with a Formlabs 3D printer for implanting electrodes into free-swimming oyster toadfish (Opsanus tau). The five piece manipulator consisted of a base, body, electrode holder, manual screw drive and locking nut. The manipulator measured approximately 25×20×30mm (l×w×h) and weighed 5.28g after hand assembly. Microwire electrodes were inserted successfully with the manipulator to record high fidelity signals from the anterior lateral line nerve of the toadfish. The micromanipulator allowed the chronically implanted electrodes to be repositioned numerous times to record from multiple sites and extended successful recording time in the toadfish by several days. Three dimensional printing allowed an inexpensive (<$US 5 material), two axis micromanipulator to be printed relatively rapidly (<2h) to successfully record from multiple sites in the anterior lateral line nerve of free-swimming toadfish. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Analysis of occipital lobe activation during functional MRI in patients with open-angle glaucoma and correlation with clinical results

    International Nuclear Information System (INIS)

    Dai Hui; Liu Yunlian; Hu Chunhong; Li Yonggang; Guo Liang; Qi Jianpin; Xia Liming

    2013-01-01

    Objective: To evaluate the activation of the visual cortex in patients with primary open angle glaucoma (POAG) and to explore whether the neuronal activity corresponds with retinal nerve fiber layer (RNFL) and cup-to-disc (C/D) values. Methods: Twenty-five patients and 25 gender-and age matched healthy volunteers were studied. Blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) and three-dimensional brain volume imaging (3D BRAVO) sequences were obtained using 3 T MR imaging system. A full-screen black-white shift checkerboard was used for visual stimulus during the fMRI experiment and was performed on each eye of all subjects using a visual-acoustical system. All acquired data were postprocessed and analyzed by statistical parametric mapping (SPM). After analysis, individual activated mapping, intra-group mean activated mapping, and inter-group variant mapping were observed. The voxel number, intensity, and Montreal Neurological Institute (MNI) coordinate of the activated clusters were recorded. The Xjviewer software was utilized to obtain activated voxel numbers in occipital lobe. A Pearson correlated test was performed to test the correlation between the number of activated voxels and RNFL, C/D and Hodapp-Anderson-Parrish (HAP) clinical stage. Results: Intra-group mean activated mappings of both patients and volunteers showed obvious activation in bilateral occipital lobes. As compared with healthy volunteers, the POAG patients exhibited statistically significantly decreased activation in bilateral occipital lobes, left hippocampus, and left cerebellum, along with lower mean RNFL [(71.56 ± 21.54) μm versus (111.88 ± 9.96) μm] and higher C/D values (0.71 ± 0.18 versus 0.36 ± 0.08 ; t value was respectively -10.901 and 11.643, P 0.05). Conclusions: fMRI demonstrated differences in visual cortex activation in POAG patients relative to healthy volunteers, suggesting it might be a promising complementary method for diagnosing

  16. Different brain activation under left and right ventricular stimulation: an fMRI study in anesthetized rats.

    Science.gov (United States)

    Suzuki, Hideaki; Sumiyoshi, Akira; Kawashima, Ryuta; Shimokawa, Hiroaki

    2013-01-01

    Myocardial ischemia in the anterior wall of the left ventricule (LV) and in the inferior wall and/or right ventricle (RV) shows different manifestations that can be explained by the different innervations of cardiac afferent nerves. However, it remains unclear whether information from different areas of the heart, such as the LV and RV, are differently processed in the brain. In this study, we investigated the brain regions that process information from the LV or RV using cardiac electrical stimulation and functional magnetic resonance imaging (fMRI) in anesthetized rats because the combination of these two approaches cannot be used in humans. An electrical stimulation catheter was inserted into the LV or RV (n = 12 each). Brain fMRI scans were recorded during LV or RV stimulation (9 Hz and 0.3 ms width) over 10 blocks consisting of alternating periods of 2 mA for 30 sec followed by 0.2 mA for 60 sec. The validity of fMRI signals was confirmed by first and second-level analyses and temporal profiles. Increases in fMRI signals were observed in the anterior cingulate cortex and the right somatosensory cortex under LV stimulation. In contrast, RV stimulation activated the right somatosensory cortex, which was identified more anteriorly compared with LV stimulation but did not activate the anterior cingulate cortex. This study provides the first evidence for differences in brain activation under LV and RV stimulation. These different brain processes may be associated with different clinical manifestations between anterior wall and inferoposterior wall and/or RV myocardial ischemia.

  17. Postpartum suppression of ovarian activity with a Deslorelin implant enhanced uterine involution in lactating dairy cows.

    Science.gov (United States)

    Silvestre, F T; Bartolome, J A; Kamimura, S; Arteche, A C; Pancarci, S M; Trigg, T; Thatcher, W W

    2009-01-01

    Holstein cows received, subcutaneously a non-degradable implant containing 5mg of the GnRH agonist Deslorelin (DESL) or no implant (CON) at 2+/-1 days postpartum (dpp). All cows were injected with PGF(2alpha) at 9 dpp. Previous pregnant (PPH) and non-pregnant uterine horns (PNPH) were determined by palpation per rectum. In Experiment 1, cows [DESL implant (n=10) and CON (n=9)] were examined by ultrasonography to record ovarian structures (23, 30 and 37 dpp) and uterine horn and cervical diameters (16, 23, 30 and 37 dpp). Uterine tone was scored before ultrasonography. Vaginoscopy was conducted just after ultrasonography examination to assess cervical discharge and color of the external cervical os. Blood samples were collected on a weekly basis for hormonal analyses. In Experiment 2, cows [DESL implant (n=77) and CON (n=70)] were palpated per rectum and vaginoscopy at 30 dpp for scoring of uterine tone, uterine horns, cervical diameter, and discharge. Blood samples were collected only at 9 dpp. In Experiment 1, DESL-implant-treated cows had more Class 1 follicles (Pscore did not differ between treatments. Treatment with non-degradable Deslorelin (5mg) implant during postpartum: (1) suppressed ovarian follicular development, (2) enhanced physical involution of the uterus and cervix, (3) increased tone of the uterine wall, (4) decreased frequency of purulent cervical discharges, and (5) reduced inflammatory processes of the reproductive tract.

  18. Social reward improves the voluntary control over localized brain activity in fMRI-based neurofeedback training

    Directory of Open Access Journals (Sweden)

    Krystyna Anna Mathiak

    2015-06-01

    Full Text Available Neurofeedback (NF based on real-time functional magnetic resonance imaging (rt-fMRI allows voluntary regulation of the activity in a selected brain region. For the training of this regulation, a well-designed feedback system is required. Social reward may serve as an effective incentive in NF paradigms, but its efficiency has not yet been tested. Therefore, we developed a social reward NF paradigm and assessed it in comparison with a typical visual NF paradigm (moving bar.We trained 24 healthy participants, on three consecutive days, to control activation in dorsal anterior cingulate cortex (ACC with fMRI-based NF. In the social feedback group, an avatar gradually smiled when ACC activity increased, whereas in the standard feedback group, a moving bar indicated the activation level. To assess a transfer of the NF training both groups were asked to up-regulate their brain activity without receiving feedback immediately before and after the NF training (pre- and post-test. Finally, the effect of the acquired NF training on ACC function was evaluated in a cognitive interference task (Simon task during the pre- and post-test.Social reward led to stronger activity in the ACC and reward-related areas during the NF training when compared to standard feedback. After the training, both groups were able to regulate ACC without receiving feedback, with a trend for stronger responses in the social feedback group. Moreover, despite a lack of behavioral differences, significant higher ACC activations emerged in the cognitive interference task, reflecting a stronger generalization of the NF training on cognitive interference processing after social feedback.Social reward can increase self-regulation in fMRI-based NF and strengthen its effects on neural processing in related tasks, such as cognitive interference. An advantage of social feedback is that a direct external reward is provided as in natural social interactions, opening perspectives for implicit

  19. Ion implantation

    International Nuclear Information System (INIS)

    Dearnaley, Geoffrey

    1975-01-01

    First, ion implantation in semiconductors is discussed: ion penetration, annealing of damage, gettering, ion implanted semiconductor devices, equipement requirements for ion implantation. The importance of channeling for ion implantation is studied. Then, some applications of ion implantation in metals are presented: study of the corrosion of metals and alloys; influence or ion implantation on the surface-friction and wear properties of metals; hyperfine interactions in implanted metals

  20. Combined Use of Tc-99m MIBI Scan and MRI for Evaluation of Active Lesions in Multiple Myeloma

    International Nuclear Information System (INIS)

    Mititelu, R.; Marinescu, G.; Iriciuc, M.; Rimbu, A.; Ghita, S.; Mazilu, C.; Murgoci, P.; Codorean, I.

    2006-01-01

    Full text: Multiple Myeloma is a malignancy of plasma cells, in which neoplastic bone involvement is one of the leading symptoms. Many researchers have been trying to develop new imaging modalities and new methods for detecting the bone involvement, mainly because apart from the fact that bone marrow infiltration is one of the diagnostic criteria, typical radiographic findings can be found only in 60 70% of pts with first diagnosis of MM, and 10% of pts can present only osteoporosis-like changes. Purpose To evaluate the efficacy of 99mTc-MIBI whole-body scan in diagnosis of Multiple Myeloma, in correlation with other imaging modalities, and mainly with MRI. Material and Method: We performed a retrospective review of 29 cases of Multiple Myeloma Patients, all of them in active stage of the disease. All of them underwent 99mTc-MIBI whole body scan, MRI examination of the spine and a bone scan. Diagnosis and staging of the disease was made by using standard criteria. MRI was performed mainly for imaging spinal cord compression and for morphological characterization of lesions. We obtained saggital and transverse images which included T1-weighted spin-echo, T2-weighted turbo spin-echo and STIR sequences. We performed whole body MIBI scan in anterior and posterior views, 10 - 20 min after IV injection of 500-550 MBq of 99mTc-MIBI, using a dual head gamma-camera Philips- Axis. Results: We obtained pathologic changes in 25/29 pts that underwent whole-body MIBI scan(86.75%), and in 27/29(89.65%) for the MRI. Bone scan shown pathologic uptake of radiotracer in 18/29 pts(62.06%). In 4 pts that demonstrated pathologic increased uptake of MIBI we found photopenic lesions on the bone scan which were missed at the first interpretation of the bone scan; these lesions were reported only after comparative evaluation of bone scan and MIBI scan.We found three different patterns of pathologic MIBI uptake: focal increased uptake of MIBI in different sites (9 pts), diffuse increased

  1. Gender similarities and differences in brain activation strategies: Voxel-based meta-analysis on fMRI studies.

    Science.gov (United States)

    AlRyalat, Saif Aldeen

    2017-01-01

    Gender similarities and differences have long been a matter of debate in almost all human research, especially upon reaching the discussion about brain functions. This large scale meta-analysis was performed on functional MRI studies. It included more than 700 active brain foci from more than 70 different experiments to study gender related similarities and differences in brain activation strategies for three of the main brain functions: Visual-spatial cognition, memory, and emotion. Areas that are significantly activated by both genders (i.e. core areas) for the tested brain function are mentioned, whereas those areas significantly activated exclusively in one gender are the gender specific areas. During visual-spatial cognition task, and in addition to the core areas, males significantly activated their left superior frontal gyrus, compared with left superior parietal lobule in females. For memory tasks, several different brain areas activated by each gender, but females significantly activated two areas from the limbic system during memory retrieval tasks. For emotional task, males tend to recruit their bilateral prefrontal regions, whereas females tend to recruit their bilateral amygdalae. This meta-analysis provides an overview based on functional MRI studies on how males and females use their brain.

  2. Parallel feedback active noise control of MRI acoustic noise with signal decomposition using hybrid RLS-NLMS adaptive algorithms.

    Science.gov (United States)

    Ganguly, Anshuman; Krishna Vemuri, Sri Hari; Panahi, Issa

    2014-01-01

    This paper presents a cost-effective adaptive feedback Active Noise Control (FANC) method for controlling functional Magnetic Resonance Imaging (fMRI) acoustic noise by decomposing it into dominant periodic components and residual random components. Periodicity of fMRI acoustic noise is exploited by using linear prediction (LP) filtering to achieve signal decomposition. A hybrid combination of adaptive filters-Recursive Least Squares (RLS) and Normalized Least Mean Squares (NLMS) are then used to effectively control each component separately. Performance of the proposed FANC system is analyzed and Noise attenuation levels (NAL) up to 32.27 dB obtained by simulation are presented which confirm the effectiveness of the proposed FANC method.

  3. Glucose administration enhances fMRI brain activation and connectivity related to episodic memory encoding for neutral and emotional stimuli.

    Science.gov (United States)

    Parent, Marise B; Krebs-Kraft, Desiree L; Ryan, John P; Wilson, Jennifer S; Harenski, Carla; Hamann, Stephan

    2011-04-01

    Glucose enhances memory in a variety of species. In humans, glucose administration enhances episodic memory encoding, although little is known regarding the neural mechanisms underlying these effects. Here we examined whether elevating blood glucose would enhance functional MRI (fMRI) activation and connectivity in brain regions associated with episodic memory encoding and whether these effects would differ depending on the emotional valence of the material. We used a double-blind, within-participants, crossover design in which either glucose (50g) or a saccharin placebo were administered before scanning, on days approximately 1 week apart. We scanned healthy young male participants with fMRI as they viewed emotionally arousing negative pictures and emotionally neutral pictures, intermixed with baseline fixation. Free recall was tested at 5 min after scanning and again after 1 day. Glucose administration increased activation in brain regions associated with successful episodic memory encoding. Glucose also enhanced activation in regions whose activity was correlated with subsequent successful recall, including the hippocampus, prefrontal cortex, and other regions, and these effects differed for negative vs. neutral stimuli. Finally, glucose substantially increased functional connectivity between the hippocampus and amygdala and a network of regions previously implicated in successful episodic memory encoding. These findings fit with evidence from nonhuman animals indicating glucose modulates memory by selectively enhancing neural activity in brain regions engaged during memory tasks. Our results highlight the modulatory effects of glucose and the importance of examining both regional changes in activity and functional connectivity to fully characterize the effects of glucose on brain function and memory. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Combining task-evoked and spontaneous activity to improve pre-operative brain mapping with fMRI.

    Science.gov (United States)

    Fox, Michael D; Qian, Tianyi; Madsen, Joseph R; Wang, Danhong; Li, Meiling; Ge, Manling; Zuo, Huan-Cong; Groppe, David M; Mehta, Ashesh D; Hong, Bo; Liu, Hesheng

    2016-01-01

    Noninvasive localization of brain function is used to understand and treat neurological disease, exemplified by pre-operative fMRI mapping prior to neurosurgical intervention. The principal approach for generating these maps relies on brain responses evoked by a task and, despite known limitations, has dominated clinical practice for over 20years. Recently, pre-operative fMRI mapping based on correlations in spontaneous brain activity has been demonstrated, however this approach has its own limitations and has not seen widespread clinical use. Here we show that spontaneous and task-based mapping can be performed together using the same pre-operative fMRI data, provide complimentary information relevant for functional localization, and can be combined to improve identification of eloquent motor cortex. Accuracy, sensitivity, and specificity of our approach are quantified through comparison with electrical cortical stimulation mapping in eight patients with intractable epilepsy. Broad applicability and reproducibility of our approach are demonstrated through prospective replication in an independent dataset of six patients from a different center. In both cohorts and every individual patient, we see a significant improvement in signal to noise and mapping accuracy independent of threshold, quantified using receiver operating characteristic curves. Collectively, our results suggest that modifying the processing of fMRI data to incorporate both task-based and spontaneous activity significantly improves functional localization in pre-operative patients. Because this method requires no additional scan time or modification to conventional pre-operative data acquisition protocols it could have widespread utility. Copyright © 2015. Published by Elsevier Inc.

  5. A computer-aided detection system for rheumatoid arthritis MRI data interpretation and quantification of synovial activity

    International Nuclear Information System (INIS)

    Kubassova, Olga; Boesen, Mikael; Cimmino, Marco A.; Bliddal, Henning

    2010-01-01

    Rational and objective: Disease assessment and follow-up of rheumatoid arthritis (RA) patients require objective evaluation and quantification. Magnetic resonance imaging (MRI) has a large potential to supplement such information for the clinician, however, time spent on data reading and interpretation slow down development in this area. Existing scoring systems of especially synovitis are too rigid and insensitive to measure early treatment response and quantify inflammation. This study tested a novel automated, computer system for analysis of dynamic MRI data acquired from patients with RA, Dynamika-RA, which incorporates efficient data processing and analysis techniques. Materials and methods: 140 MRI scans from hands and wrists of 135 active RA patients and 5 healthy controls were processed using Dynamika-RA and evaluated with RAMRIS. To reduce patient motion artefacts, MRI data were processed using Dynamika-RA, which removed motion in 2D and 3D planes. Then synovial enhancement was visualised and qualified using a novel fully automated voxel-by-voxel analysis based algorithm. This algorithm was used to replace traditional region-of-interest (ROI) and subtraction methods, yielding observer independent quantitative results. Results: Conventional scoring performed by an observer took 30-45 min per dataset. Dynamika-RA reduced motion artefacts, visualised inflammation and quantified disease activity in less than 3 min. Data processing allowed increasing signal to noise ratio by a factor 3. Due to fully automated procedure of data processing, there was no intertest variation in the results. Conclusions: Algorithms incorporated into Dynamika-RA allow for the significant enhancement of data quality through eliminating motion artefacts and reduction of time for evaluation of synovial inflammation.

  6. Walk-related mimic word activates the extrastriate visual cortex in the human brain: an fMRI study.

    Science.gov (United States)

    Osaka, Naoyuki

    2009-03-02

    I present an fMRI study demonstrating that a mimic word highly suggestive of human walking, heard by the ear with eyes closed, significantly activates the visual cortex located in extrastriate occipital region (BA19, 18) and superior temporal sulcus (STS) while hearing non-sense words that do not imply walk under the same task does not activate these areas in humans. I concluded that BA19 and 18 would be a critical region for generating visual images of walking and related intentional stance, respectively, evoked by an onomatopoeia word that implied walking.

  7. A word expressing affective pain activates the anterior cingulate cortex in the human brain: an fMRI study.

    Science.gov (United States)

    Osaka, Naoyuki; Osaka, Mariko; Morishita, Masanao; Kondo, Hirohito; Fukuyama, Hidenao

    2004-08-12

    We present an fMRI study demonstrating that an onomatopoeia word highly suggestive of subjective pain, heard by the ear, significantly activates the anterior cingulate cortex (ACC) while hearing non-sense words that did not imply affective pain under the same task does not activate this area in humans. We concluded that the ACC would be a pivotal locus for perceiving affective pain evoked by an onomatopoeia word that implied affective pain closely associated with the unpleasantness of pain. We suggest that the pain affect sustained by pain unpleasantness may depend on ACC-prefrontal cortical interactions that modify cognitive evaluation of emotions associated with word-induced pain.

  8. Brain activation in response to randomized visual stimulation as obtained from conjunction and differential analysis: an fMRI study

    International Nuclear Information System (INIS)

    Nasaruddin, N H; Yusoff, A N; Kaur, S

    2014-01-01

    The objective of this multiple-subjects functional magnetic resonance imaging (fMRI) study was to identify the common brain areas that are activated when viewing black-and-white checkerboard pattern stimuli of various shapes, pattern and size and to investigate specific brain areas that are involved in processing static and moving visual stimuli. Sixteen participants viewed the moving (expanding ring, rotating wedge, flipping hour glass and bowtie and arc quadrant) and static (full checkerboard) stimuli during an fMRI scan. All stimuli have black-and-white checkerboard pattern. Statistical parametric mapping (SPM) was used in generating brain activation. Differential analyses were implemented to separately search for areas involved in processing static and moving stimuli. In general, the stimuli of various shapes, pattern and size activated multiple brain areas mostly in the left hemisphere. The activation in the right middle temporal gyrus (MTG) was found to be significantly higher in processing moving visual stimuli as compared to static stimulus. In contrast, the activation in the left calcarine sulcus and left lingual gyrus were significantly higher for static stimulus as compared to moving stimuli. Visual stimulation of various shapes, pattern and size used in this study indicated left lateralization of activation. The involvement of the right MTG in processing moving visual information was evident from differential analysis, while the left calcarine sulcus and left lingual gyrus are the areas that are involved in the processing of static visual stimulus

  9. Frontopolar and anterior temporal cortex activation in a moral judgment task. Preliminary functional MRI results in normal subjects

    International Nuclear Information System (INIS)

    Moll, Jorge; Oliveira-Souza, Ricardo de

    2001-01-01

    The objective was to study the brain areas which are activated when normal subjects make moral judgments. Ten normal adults underwent BOLD functional magnetic resonance imaging (fMRI) during the auditory presentation of sentences that they were instructed to silently judge as either 'right' or 'wrong'. Half of the sentences had an explicit moral content ('We break the law when necessary'), the other half comprised factual statements devoid of moral connotation ('Stones are made of water'). After scanning, each subject rated the moral content, emotional valence, and judgment difficulty of each sentence on Likert-like scales. To exclude the effect of emotion on the activation results, individual responses were hemo dynamically modeled for event-related f MRI analysis. The general linear model was used to evaluate the brain areas activated by moral judgment. Regions activated during moral judgment included the frontopolar cortex (FPC), medial frontal gyrus, right anterior temporal cortex, lenticular nucleus, and cerebellum. Activation of FPC and medial frontal gyrus (B A 10/46 and 9) were largely independent of emotional experience and represented the largest areas of activation. These results concur with clinical observations assigning a critical role for the frontal poles and right anterior temporal cortex in the mediation of complex judgment processes according to moral constraints. The FPC may work in concert with the orbitofrontal and dorsolateral cortex in the regulation of human social conduct. (author)

  10. The fMRI study on the front-parietal activation in abacus mental calculation trained children

    International Nuclear Information System (INIS)

    Zhao Kunyuan; Wang Bin; Long Jinfeng; Li Lixin; Shen Xiaojun

    2010-01-01

    Objective: To investigate the difference in front-parietal activation between the trained and untrained children engaged in addition and multiplication with functional magnetic resonance imaging (fMRI), and to explore the role of abacus mental calculation in brain development. Methods: Twenty-four children trained with abacus mental calculation and twelve untrained children performed mental calculation tasks including addition, multiplication and number-object control judging tasks. Blood oxygenation level dependence (BOLD) fMRI was performed when they were calculating. All data were analyzed by SPM2 (statistical parametric mapping 2) to generate the brain activation map. Results: The performance of the trained group had better correctness and shorter reaction time than that of the untrained group. The front-parietal activation between two groups had obvious difference. The activation involved less prefrontal cortex in the trained group than in the untrained group (P<0.05). The parietal activation in the trained group was mainly in the posterior superior parietal lobe/ precuneus, whereas the activation areas focused on the inferior parietal lobule in the untrained group. Conclusion: Abacus mental calculation involves multiple functional areas. and these areas may work together as a whole in processing arithmetic problems. Abacus mental calculation not only enhances the information processing in some brain areas and improves the utilization efficiency of neural resources, but also plays an important role in developing brain. (authors)

  11. Frontopolar and anterior temporal cortex activation in a moral judgment task. Preliminary functional MRI results in normal subjects

    Energy Technology Data Exchange (ETDEWEB)

    Moll, Jorge [LABS and Rede D' Or Hospitais, Rio de Janeiro RJ (Brazil). Grupo de Neuroimagem e Neurologia do Comportamento; Eslinger, Paul J. [Pensylvania State Univ. (United States). College of Medicine. Div. of Neurology and Behavioral Science; The Milton S. Hershey Medical Center, Hershey, PN (United States); Oliveira-Souza, Ricardo de [Universidade do Rio de Janeiro (UNI-Rio), RJ (Brazil). Hospital Universitario Gaffree e Guinle]. E-mail: neuropsychiatry@hotmail.com

    2001-09-01

    The objective was to study the brain areas which are activated when normal subjects make moral judgments. Ten normal adults underwent BOLD functional magnetic resonance imaging (fMRI) during the auditory presentation of sentences that they were instructed to silently judge as either 'right' or 'wrong'. Half of the sentences had an explicit moral content ('We break the law when necessary'), the other half comprised factual statements devoid of moral connotation ('Stones are made of water'). After scanning, each subject rated the moral content, emotional valence, and judgment difficulty of each sentence on Likert-like scales. To exclude the effect of emotion on the activation results, individual responses were hemo dynamically modeled for event-related f MRI analysis. The general linear model was used to evaluate the brain areas activated by moral judgment. Regions activated during moral judgment included the frontopolar cortex (FPC), medial frontal gyrus, right anterior temporal cortex, lenticular nucleus, and cerebellum. Activation of FPC and medial frontal gyrus (B A 10/46 and 9) were largely independent of emotional experience and represented the largest areas of activation. These results concur with clinical observations assigning a critical role for the frontal poles and right anterior temporal cortex in the mediation of complex judgment processes according to moral constraints. The FPC may work in concert with the orbitofrontal and dorsolateral cortex in the regulation of human social conduct. (author)

  12. Brain activation in response to randomized visual stimulation as obtained from conjunction and differential analysis: an fMRI study

    Science.gov (United States)

    Nasaruddin, N. H.; Yusoff, A. N.; Kaur, S.

    2014-11-01

    The objective of this multiple-subjects functional magnetic resonance imaging (fMRI) study was to identify the common brain areas that are activated when viewing black-and-white checkerboard pattern stimuli of various shapes, pattern and size and to investigate specific brain areas that are involved in processing static and moving visual stimuli. Sixteen participants viewed the moving (expanding ring, rotating wedge, flipping hour glass and bowtie and arc quadrant) and static (full checkerboard) stimuli during an fMRI scan. All stimuli have black-and-white checkerboard pattern. Statistical parametric mapping (SPM) was used in generating brain activation. Differential analyses were implemented to separately search for areas involved in processing static and moving stimuli. In general, the stimuli of various shapes, pattern and size activated multiple brain areas mostly in the left hemisphere. The activation in the right middle temporal gyrus (MTG) was found to be significantly higher in processing moving visual stimuli as compared to static stimulus. In contrast, the activation in the left calcarine sulcus and left lingual gyrus were significantly higher for static stimulus as compared to moving stimuli. Visual stimulation of various shapes, pattern and size used in this study indicated left lateralization of activation. The involvement of the right MTG in processing moving visual information was evident from differential analysis, while the left calcarine sulcus and left lingual gyrus are the areas that are involved in the processing of static visual stimulus.

  13. A scalable multi-resolution spatio-temporal model for brain activation and connectivity in fMRI data

    KAUST Repository

    Castruccio, Stefano

    2018-01-23

    Functional Magnetic Resonance Imaging (fMRI) is a primary modality for studying brain activity. Modeling spatial dependence of imaging data at different spatial scales is one of the main challenges of contemporary neuroimaging, and it could allow for accurate testing for significance in neural activity. The high dimensionality of this type of data (on the order of hundreds of thousands of voxels) poses serious modeling challenges and considerable computational constraints. For the sake of feasibility, standard models typically reduce dimensionality by modeling covariance among regions of interest (ROIs)—coarser or larger spatial units—rather than among voxels. However, ignoring spatial dependence at different scales could drastically reduce our ability to detect activation patterns in the brain and hence produce misleading results. We introduce a multi-resolution spatio-temporal model and a computationally efficient methodology to estimate cognitive control related activation and whole-brain connectivity. The proposed model allows for testing voxel-specific activation while accounting for non-stationary local spatial dependence within anatomically defined ROIs, as well as regional dependence (between-ROIs). The model is used in a motor-task fMRI study to investigate brain activation and connectivity patterns aimed at identifying associations between these patterns and regaining motor functionality following a stroke.

  14. Local activation of uterine Toll-like receptor 2 and 2/6 decreases embryo implantation and affects uterine receptivity in mice.

    Science.gov (United States)

    Sanchez-Lopez, Javier Arturo; Caballero, Ignacio; Montazeri, Mehrnaz; Maslehat, Nasim; Elliott, Sarah; Fernandez-Gonzalez, Raul; Calle, Alexandra; Gutierrez-Adan, Alfonso; Fazeli, Alireza

    2014-04-01

    Embryo implantation is a complex interaction between maternal endometrium and embryonic structures. Failure to implant is highly recurrent and impossible to diagnose. Inflammation and infections in the female reproductive tract are common causes of infertility, embryo loss, and preterm labor. The current work describes how the activation of endometrial Toll-like receptor (TLR) 2 and 2/6 reduces embryo implantation chances. We developed a morphometric index to evaluate the effects of the TLR 2/6 activation along the uterine horn (UH). TLR 2/6 ligation reduced the endometrial myometrial and glandular indexes and increased the luminal index. Furthermore, TLR 2/6 activation increased the proinflammatory cytokines such as interleukin (IL)-1beta and monocyte chemotactic protein (MCP)-1 in UH lavages in the preimplantation day and IL-1 receptor antagonist in the implantation day. The engagement of TLR 2/6 with its ligand in the UH during embryo transfer severely affected the rate of embryonic implantation (45.00% ± 6.49% vs. 16.69% ± 5.01%, P embryo implantation process was verified using an in vitro model of human embryo implantation where trophoblast spheroids failed to adhere to a monolayer of TLR 2- and TLR 2/6-activated endometrial cells. The inhibition of TLR receptors 2 and 6 in the presence of their specific ligands restored the ability of the spheroids to bind to the endometrial cells. In conclusion, the activation of the innate immune system in the uterus at the time of implantation interfered with the endometrial receptivity and reduced the chances of implantation success.

  15. Relational complexity modulates activity in the prefrontal cortex during numerical inductive reasoning: an fMRI study.

    Science.gov (United States)

    Feng, Xiao; Peng, Li; Chang-Quan, Long; Yi, Lei; Hong, Li

    2014-09-01

    Most previous studies investigating relational reasoning have used visuo-spatial materials. This fMRI study aimed to determine how relational complexity affects brain activity during inductive reasoning, using numerical materials. Three numerical relational levels of the number series completion task were adopted for use: 0-relational (e.g., "23 23 23"), 1-relational ("32 30 28") and 2-relational ("12 13 15") problems. The fMRI results revealed that the bilateral dorsolateral prefrontal cortex (DLPFC) showed enhanced activity associated with relational complexity. Bilateral inferior parietal lobule (IPL) activity was greater during the 1- and 2-relational level problems than during the 0-relational level problems. In addition, the left fronto-polar cortex (FPC) showed selective activity during the 2-relational level problems. The bilateral DLPFC may be involved in the process of hypothesis generation, whereas the bilateral IPL may be sensitive to calculation demands. Moreover, the sensitivity of the left FPC to the multiple relational problems may be related to the integration of numerical relations. The present study extends our knowledge of the prefrontal activity pattern underlying numerical relational processing. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... used in tattoos may contain iron and could heat up during an MRI scan, but this is ... imaging based on the electrical activity of the heart, such as electrocardiography (EKG). MRI generally is not ...

  17. An fMRI study of sex differences in regional activation to a verbal and a spatial task.

    Science.gov (United States)

    Gur, R C; Alsop, D; Glahn, D; Petty, R; Swanson, C L; Maldjian, J A; Turetsky, B I; Detre, J A; Gee, J; Gur, R E

    2000-09-01

    Sex differences in cognitive performance have been documented, women performing better on some phonological tasks and men on spatial tasks. An earlier fMRI study suggested sex differences in distributed brain activation during phonological processing, with bilateral activation seen in women while men showed primarily left-lateralized activation. This blood oxygen level-dependent fMRI study examined sex differences (14 men, 13 women) in activation for a spatial task (judgment of line orientation) compared to a verbal-reasoning task (analogies) that does not typically show sex differences. Task difficulty was manipulated. Hypothesized ROI-based analysis documented the expected left-lateralized changes for the verbal task in the inferior parietal and planum temporal regions in both men and women, but only men showed right-lateralized increase for the spatial task in these regions. Image-based analysis revealed a distributed network of cortical regions activated by the tasks, which consisted of the lateral frontal, medial frontal, mid-temporal, occipitoparietal, and occipital regions. The activation was more left lateralized for the verbal and more right for the spatial tasks, but men also showed some left activation for the spatial task, which was not seen in women. Increased task difficulty produced more distributed activation for the verbal and more circumscribed activation for the spatial task. The results suggest that failure to activate the appropriate hemisphere in regions directly involved in task performance may explain certain sex differences in performance. They also extend, for a spatial task, the principle that bilateral activation in a distributed cognitive system underlies sex differences in performance. Copyright 2000 Academic Press.

  18. Quantification of left ventricular volumes from cardiac cine MRI using active contour model combined with gradient vector flow

    International Nuclear Information System (INIS)

    Tanki, Nobuyoshi; Murase, Kenya; Kumashiro, Masayuki; Momoi, Risa; Yang, Xiaomei; Tabuchi, Takashi; Nagayama, Masako; Watanabe, Yuji

    2005-01-01

    We investigated the feasibility of combining the active contour model with gradient vector flow (Snakes-GVF) to estimate left ventricular (LV) volumes from cardiac cine magnetic resonance imaging (MRI). MRI data were acquired from 27 patients, including 14 adults (9 men, 5 women, 55.0±23.3 years) and 13 children (10 boys, 3 girls, 2.7±2.1 years) using Gyroscan Intera (1.5 Tesla, Philips Medical Systems). LV volumes were calculated by adding the areas surrounded by the contour extracted by Snakes-GVF and compared with volumes estimated by manual tracing. Those estimated by Snakes-GVF [y (mL)] correlated well with those estimated by manual tracing [x (mL)]. In adult cases, the regression equation and correlation coefficient were y=1.008x-0.517 and 0.996, respectively. In pediatric cases, they were y=1.174x-2.542 and 0.992, respectively. In conclusion, Snakes-GVF is a powerful and useful tool for quantifying LV volumes using cardiac MRI. (author)

  19. Ultra thin layer activation by recoil implantation of radioactive heavy ions. Applicability in wear and corrosion studies

    International Nuclear Information System (INIS)

    Lacroix, O.; Sauvage, T.; Blondiaux, G.; Guinard, L.

    1997-07-01

    A new calibration procedure is proposed for the application of recoil implantation of radioactive heavy ions (energies between a few hundred keV and a few MeV) into the near surface of materials as part of a research programme on sub-micrometric wear or corrosion phenomena. The depth profile of implanted radioelements is performed by using ultra thin deposited films obtained by cathode sputtering under argon plasma. Two curves for 56 Co ion in nickel have been determined for implantation depths of 110 and 200 nm, respectively, and stress the feasibility and reproducibility of this method for such activated depths. The achieved surface loss detection sensitivities are about 1 and 2 nm respectively. The on line detection mode is performed directly on the sample of interest. A general description of the method is presented. A study of the reaction kinematics followed by a general treatment on the irradiation parameters to be adopted are also developed with the intention of using the ultra thin layer activation method (UTLA) to further applications in research and industry. (author)

  20. Biological Activation of Inert Ceramics: Recent Advances Using Tailored Self-Assembled Monolayers on Implant Ceramic Surfaces

    Science.gov (United States)

    Böke, Frederik; Schickle, Karolina; Fischer, Horst

    2014-01-01

    High-strength ceramics as materials for medical implants have a long, research-intensive history. Yet, especially on applications where the ceramic components are in direct contact with the surrounding tissue, an unresolved issue is its inherent property of biological inertness. To combat this, several strategies have been investigated over the last couple of years. One promising approach investigates the technique of Self-Assembled Monolayers (SAM) and subsequent chemical functionalization to create a biologically active tissue-facing surface layer. Implementation of this would have a beneficial impact on several fields in modern implant medicine such as hip and knee arthroplasty, dental applications and related fields. This review aims to give a summarizing overview of the latest advances in this recently emerging field, along with thorough introductions of the underlying mechanism of SAMs and surface cell attachment mechanics on the cell side. PMID:28788687

  1. Intersubject synchronisation analysis of brain activity associated with the instant effects of acupuncture: an fMRI study.

    Science.gov (United States)

    Jin, Lingmin; Sun, Jinbo; Xu, Ziliang; Yang, Xuejuan; Liu, Peng; Qin, Wei

    2018-02-01

    To use a promising analytical method, namely intersubject synchronisation (ISS), to evaluate the brain activity associated with the instant effects of acupuncture and compare the findings with traditional general linear model (GLM) methods. 30 healthy volunteers were recruited for this study. Block-designed manual acupuncture stimuli were delivered at SP6, and de qi sensations were measured after acupuncture stimulation. All subjects underwent functional MRI (fMRI) scanning during the acupuncture stimuli. The fMRI data were separately analysed by ISS and traditional GLM methods. All subjects experienced de qi sensations. ISS analysis showed that the regions activated during acupuncture stimulation at SP6 were mainly divided into five clusters based on the time courses. The time courses of clusters 1 and 2 were in line with the acupuncture stimulation pattern, and the active regions were mainly involved in the sensorimotor system and salience network. Clusters 3, 4 and 5 displayed an almost contrary time course relative to the stimulation pattern. The brain regions activated included the default mode network, descending pain modulation pathway and visual cortices. GLM analysis indicated that the brain responses associated with the instant effects of acupuncture were largely implicated in sensory and motor processing and sensory integration. The ISS analysis considered the sustained effect of acupuncture and uncovered additional information not shown by GLM analysis. We suggest that ISS may be a suitable approach to investigate the brain responses associated with the instant effects of acupuncture. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  2. ACR/EULAR Definitions of Remission Are Associated with Lower Residual Inflammatory Activity Compared with DAS28 Remission on Hand MRI in Rheumatoid Arthritis.

    Science.gov (United States)

    Lisbona, Maria Pilar; Solano, Albert; Ares, Jesús; Almirall, Miriam; Salman-Monte, Tarek Carlos; Maymó, Joan

    2016-09-01

    To determine the level of residual inflammation [synovitis, bone marrow edema (BME), tenosynovitis, and total inflammation] quantified by hand magnetic resonance imaging (h-MRI) in patients with rheumatoid arthritis (RA) in remission according to 3 different definitions of clinical remission, and to compare these remission definitions. A cross-sectional study. To assess the level of residual MRI inflammation in remission, cutoff levels associated to remission and median scores of MRI residual inflammatory lesions were calculated. Data from an MRI register of patients with RA who have various levels of disease activity were used. These were used for the analyses: synovitis, BME according to the Rheumatoid Arthritis Magnetic Resonance Imaging Scoring system, tenosynovitis, total inflammation, and disease activity composite measures recorded at the time of MRI. Receiver-operating characteristic analysis was used to identify the best cutoffs associated with remission for each inflammatory lesion on h-MRI. Median values of each inflammatory lesion for each definition of remission were also calculated. A total of 388 h-MRI sets of patients with RA with different levels of disease activity, 130 in remission, were included. Cutoff values associated with remission according to the Simplified Disease Activity Index (SDAI) ≤ 3.3 and the Boolean American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) definitions for BME and tenosynovitis (1 and 3, respectively) were lower than BME and tenosynovitis (2 and 5, respectively) for the Disease Activity Score on 28 joints (DAS28) ≤ 2.6. Median scores for synovitis, BME, and total inflammation were also lower for the SDAI and Boolean ACR/EULAR remission criteria compared with DAS28. Patients with RA in remission according to the SDAI and Boolean ACR/EULAR definitions showed lower levels of MRI-detected residual inflammation compared with DAS28.

  3. Novel use of non-echo-planar diffusion weighted MRI in monitoring disease activity and treatment response in active Grave's orbitopathy: An initial observational cohort study.

    Science.gov (United States)

    Lingam, Ravi Kumar; Mundada, Pravin; Lee, Vickie

    2018-01-10

    To examine the novel use of non-echo-planar diffusion weighted MRI (DWI) in depicting activity and treatment response in active Grave's orbitopathy (GO) by assessing, with inter-observer agreement, for a correlation between its apparent diffusion coefficients (ADCs) and conventional Short tau Inversion Recovery (STIR) MRI signal-intensity ratios (SIRs). A total of 23 actively inflamed muscles and 30 muscle response episodes were analysed in patients with active GO who underwent medical treatment. The MRI orbit scans included STIR sequences and non-echo-planar DWI were evaluated. Two observers independently assessed the images qualitatively for the presence of activity in the extraocular muscles (EOMs) and recorded the STIR signal-intensity (SI), SIR (SI ratio of EOM/temporalis muscle), and ADC values of any actively inflamed muscle on the pre-treatment scans and their corresponding values on the subsequent post-treatment scans. Inter-observer agreement was examined. There was a significant positive correlation (0.57, p < 0.001) between ADC and both SIR and STIR SI of the actively inflamed EOM. There was also a significant positive correlation (0.75, p < 0.001) between SIR and ADC values depicting change in muscle activity associated with treatment response. There was good inter-observer agreement. Our preliminary results indicate that quantitative evaluation with non-echo-planar DWI ADC values correlates well with conventional STIR SIR in detecting active GO and monitoring its treatment response, with good inter-observer agreement.

  4. Defining optimal tracer activities in pediatric oncologic whole-body {sup 18}F-FDG-PET/MRI

    Energy Technology Data Exchange (ETDEWEB)

    Gatidis, Sergios; Schmidt, Holger; Nikolaou, Konstantin; Schwenzer, Nina F.; Schaefer, Juergen F. [University of Tuebingen, Department of Radiology, Diagnostic and Interventional Radiology, Tuebingen (Germany); La Fougere, Christian [University of Tuebingen, Department of Radiology, Nuclear Medicine, Tuebingen (Germany)

    2016-12-15

    To explore the feasibility of reducing administered tracer activities and to assess optimal activities for combined {sup 18}F-FDG-PET/MRI in pediatric oncology. 30 {sup 18}F-FDG-PET/MRI examinations were performed on 24 patients with known or suspected solid tumors (10 girls, 14 boys, age 12 ± 5.6 [1-18] years; PET scan duration: 4 min per bed position). Low-activity PET images were retrospectively simulated from the originally acquired data sets using randomized undersampling of list mode data. PET data of different simulated administered activities (0.25-2.5 MBq/kg body weight) were reconstructed with or without point spread function (PSF) modeling. Mean and maximum standardized uptake values (SUV{sub mean} and SUV{sub max}) as well as SUV variation (SUV{sub var}) were measured in physiologic organs and focal FDG-avid lesions. Detectability of organ structures and of focal {sup 18}F-FDG-avid lesions as well as the occurrence of false-positive PET lesions were assessed at different simulated tracer activities. Subjective image quality steadily declined with decreasing tracer activities. Compared to the originally acquired data sets, mean relative deviations of SUV{sub mean} and SUV{sub max} were below 5 % at {sup 18}F-FDG activities of 1.5 MBq/kg or higher. Over 95 % of anatomic structures and all pathologic focal lesions were detectable at 1.5 MBq/kg {sup 18}F-FDG. Detectability of anatomic structures and focal lesions was significantly improved using PSF. No false-positive focal lesions were observed at tracer activities of 1 MBq/kg {sup 18}F-FDG or higher. Administration of {sup 18}F-FDG activities of 1.5 MBq/kg is, thus, feasible without obvious diagnostic shortcomings, which is equivalent to a dose reduction of more than 50 % compared to current recommendations. Significant reduction in administered {sup 18}F-FDG tracer activities is feasible in pediatric oncologic PET/MRI. Appropriate activities of {sup 18}F-FDG or other tracers for specific clinical

  5. Defining optimal tracer activities in pediatric oncologic whole-body "1"8F-FDG-PET/MRI

    International Nuclear Information System (INIS)

    Gatidis, Sergios; Schmidt, Holger; Nikolaou, Konstantin; Schwenzer, Nina F.; Schaefer, Juergen F.; La Fougere, Christian

    2016-01-01

    To explore the feasibility of reducing administered tracer activities and to assess optimal activities for combined "1"8F-FDG-PET/MRI in pediatric oncology. 30 "1"8F-FDG-PET/MRI examinations were performed on 24 patients with known or suspected solid tumors (10 girls, 14 boys, age 12 ± 5.6 [1-18] years; PET scan duration: 4 min per bed position). Low-activity PET images were retrospectively simulated from the originally acquired data sets using randomized undersampling of list mode data. PET data of different simulated administered activities (0.25-2.5 MBq/kg body weight) were reconstructed with or without point spread function (PSF) modeling. Mean and maximum standardized uptake values (SUV_m_e_a_n and SUV_m_a_x) as well as SUV variation (SUV_v_a_r) were measured in physiologic organs and focal FDG-avid lesions. Detectability of organ structures and of focal "1"8F-FDG-avid lesions as well as the occurrence of false-positive PET lesions were assessed at different simulated tracer activities. Subjective image quality steadily declined with decreasing tracer activities. Compared to the originally acquired data sets, mean relative deviations of SUV_m_e_a_n and SUV_m_a_x were below 5 % at "1"8F-FDG activities of 1.5 MBq/kg or higher. Over 95 % of anatomic structures and all pathologic focal lesions were detectable at 1.5 MBq/kg "1"8F-FDG. Detectability of anatomic structures and focal lesions was significantly improved using PSF. No false-positive focal lesions were observed at tracer activities of 1 MBq/kg "1"8F-FDG or higher. Administration of "1"8F-FDG activities of 1.5 MBq/kg is, thus, feasible without obvious diagnostic shortcomings, which is equivalent to a dose reduction of more than 50 % compared to current recommendations. Significant reduction in administered "1"8F-FDG tracer activities is feasible in pediatric oncologic PET/MRI. Appropriate activities of "1"8F-FDG or other tracers for specific clinical questions have to be further established in selected

  6. Brain activity modification produced by a single radioelectric asymmetric brain stimulation pulse: a new tool for neuropsychiatric treatments. Preliminary fMRI study

    Directory of Open Access Journals (Sweden)

    Castagna A

    2011-10-01

    Full Text Available Salvatore Rinaldi1,2, Vania Fontani1, Alessandro Castagna1 1Department of Neuro-Psycho-Physio Pathology, Rinaldi Fontani Institute, Florence, Italy; 2Medical School of Occupational Medicine, University of Florence, Florence, Italy Purpose: Radioelectric asymmetric brain stimulation technology with its treatment protocols has shown efficacy in various psychiatric disorders. The aim of this work was to highlight the mechanisms by which these positive effects are achieved. The current study was conducted to determine whether a single 500-millisecond radioelectric asymmetric conveyor (REAC brain stimulation pulse (BSP, applied to the ear, can effect a modification of brain activity that is detectable using functional magnetic resonance imaging (fMRI. Methods: Ten healthy volunteers, six females and four males, underwent fMRI during a simple finger-tapping motor task before and after receiving a single 500-millisecond REAC-BSP. Results: The fMRI results indicate that the average variation in task-induced encephalic activation patterns is lower in subjects following the single REAC pulse. Conclusion: The current report demonstrates that a single REAC-BSP is sufficient to modulate brain activity in awake subjects, able to be measured using fMRI. These initial results open new perspectives into the understanding of the effects of weak and brief radio pulses upon brain activity, and provide the basis for further indepth studies using REAC-BSP and fMRI. Keywords: fMRI, brain stimulation, brain modulation, REAC, neuropsychiatric treatments

  7. Could persistency of current of injury forecast successful active-fixation pacing lead implantation?

    Science.gov (United States)

    Shali, Shalaimaiti; Su, Yangang; Qin, Shengmei; Ge, Junbo

    2018-05-01

    Presence of adequate current of injury (COI) was recognized as a sign of favorable pacemaker lead outcome. Little is known regarding the value of its dynamic behavior. We sought to test whether persistency of COI could predict active-fixation pacing lead performance. COI was monitored up to 10min after right ventricular (RV) pacing electrode fixation. COI persistency was defined as the percentage of COI magnitude relative to its initial measurement. An unacceptable pacing threshold (≥1.0V in acute evaluation or ≥2.0V over 2-year follow-up) with or without lead dislodgement was considered as lead failure. Lead implantation was attempted for 217 times in 174 patients (age 66.3±7.8years, 78 female). Acute lead failures occurred 43 times. Independent predictors of acute lead failure were RV enlargement (odds ratio [OR] 1.23, 95% confidential interval [CI] 1.11-2.04, P=0.033), absence of COI (OR 3.13, 95%CI 2.08-9.09, P=0.027), and COI persistency at 5min (OR 0.32, 95%CI 0.20-0.69, P=0.001) and 10min (OR 0.41, 95%CI 0.13-0.77, P=0.001). The optimal cutoffs were COI 5min persistency ≥50% (sensitivity 81.4%; specificity 81.9%) and COI 10min persistency ≥20% (sensitivity 86%; specificity 88.6%). There were 12 lead failures during 24.0±6.4months of follow-up. Patients with COI 5min persistency ≥50% had higher event-free survival compared to those with COI 5min persistency <50% (hazard ratio 3.54, 95% CI 1.04-12.06, P=0.043). COI persistency appears to be a valuable indicator for both acute and long-term outcome of active-fixation pacemaker leads. A precipitous decline in COI may require more attention to make sure of the lead performance. Copyright © 2018 Elsevier Ireland Ltd. All rights reserved.

  8. Decrease in fMRI brain activation during working memory performed after sleeping under 10 lux light.

    Science.gov (United States)

    Kang, Seung-Gul; Yoon, Ho-Kyoung; Cho, Chul-Hyun; Kwon, Soonwook; Kang, June; Park, Young-Min; Lee, Eunil; Kim, Leen; Lee, Heon-Jeong

    2016-11-09

    The aim of this study was to investigate the effect of exposure to dim light at night (dLAN) when sleeping on functional brain activation during a working-memory tasks. We conducted the brain functional magnetic resonance imaging (fMRI) analysis on 20 healthy male subjects. All participants slept in a polysomnography laboratory without light exposure on the first and second nights and under a dim-light condition of either 5 or 10 lux on the third night. The fMRI scanning was conducted during n-back tasks after second and third nights. Statistical parametric maps revealed less activation in the right inferior frontal gyrus (IFG) after exposure to 10-lux light. The brain activity in the right and left IFG areas decreased more during the 2-back task than during the 1- or 0-back task in the 10-lux group. The exposure to 5-lux light had no significant effect on brain activities. The exposure to dLAN might influence the brain function which is related to the cognition.

  9. The activL® Artificial Disc: a next-generation motion-preserving implant for chronic lumbar discogenic pain

    Directory of Open Access Journals (Sweden)

    Yue JJ

    2016-05-01

    Full Text Available James J Yue,1 Rolando Garcia Jr,2 Larry E Miller3 1Department of Orthopaedic Surgery, Yale School of Medicine, New Haven, CT, 2Orthopedic Care Center, Miami, FL, 3Miller Scientific Consulting, Inc., Asheville, NC, USA Abstract: Degeneration of the lumbar intervertebral discs is a leading cause of chronic low back pain in adults. Treatment options for patients with chronic lumbar discogenic pain unresponsive to conservative management include total disc replacement (TDR or lumbar fusion. Until recently, only two lumbar TDRs had been approved by the US Food and Drug Administration - the Charité Artificial Disc in 2004 and the ProDisc-L Total Disc Replacement in 2006. In June 2015, a next-generation lumbar TDR received Food and Drug Administration approval - the activL® Artificial Disc (Aesculap Implant Systems. Compared to previous-generation lumbar TDRs, the activL® Artificial Disc incorporates specific design enhancements that result in a more precise anatomical match and allow a range of motion that better mimics the healthy spine. The results of mechanical and clinical studies demonstrate that the activL® Artificial Disc results in improved mechanical and clinical outcomes versus earlier-generation artificial discs and compares favorably to lumbar fusion. The purpose of this report is to describe the activL® Artificial Disc including implant characteristics, intended use, surgical technique, postoperative care, mechanical testing, and clinical experience to date. Keywords: activL® Artificial Disc, artificial disc, degenerative disc disease, discogenic, implant, lumbar, motion preservation, pain

  10. Oxytocic and anti-implantation activities of the leaf extracts of ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... oxytocin while GPAE was found to reduce the normal contraction of the uterine strip. The anti- implantation investigation was done using three groups of eight week old virgin female Sprague-Dawley albino rats (eight ... Virgin female and proven male Sprague-Dawley rats (weight, 120-. 130 g) obtained ...

  11. Incorporation of Novel MRI and Biomarkers into Prostate Cancer Active Surveillance Risk Assessment

    Science.gov (United States)

    2017-09-01

    attending the MRI Ultrasound Fusion Guided Prostate biopsy II session at the American Urological Association 2017 annual meeting along with several...MV, Raman JD, Spears V, Stroup SP. An Update of the American Urological Association White Paper on the Prevention and Treatment of the More Common...support (no). Galván GC1, Johnson CB1, Price RS2, Liss MA3, Jolly CA1, deGraffenried LA1. Effects of Obesity on the Regulation of Macrophage

  12. Updating working memory in aircraft noise and speech causes different fMRI activations

    OpenAIRE

    Sætrevik, Bjørn; Sörqvist, Patrik

    2014-01-01

    The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between ?substitution processes,? which involve adding new items to the working memory representation and suppressing old items, and ?exclusion processes,? which involve rejecting new items and maintaining an intact memory set. The cu...

  13. MU-SYNTHESIS BASED ACTIVE ROBUST VIBRATION CONTROL OF AN MRI INLET

    Directory of Open Access Journals (Sweden)

    Atta Oveisi

    2016-04-01

    Full Text Available In this paper, a robust control technique based on μ-synthesis is employed in order to investigate the vibration control of a funnel-shaped structure that is used as the inlet of a magnetic resonance imaging (MRI device. MRI devices are widely subjected to the vibration of the magnetic gradient coil which then propagates to acoustic noise and leads to a series of clinical and mechanical problems. In order to address this issue and as a part of noise cancellation study in MRI devices, distributed piezo-transducers are bounded on the top surface of the funnel as functional sensor/actuator modules. Then, a reduced order linear time-invariant (LTI model of the piezolaminated structure in the state-space representation is estimated by means of a predictive error minimization (PEM algorithm as a subspace identification method based on the trust-region-reflective technique. The reduced order model is expanded by the introduction of appropriate frequency-dependent weighting functions that address the unmodeled dynamics and the augmented multiplicative modeling uncertainties of the system. Then, the standard D-K iteration algorithm as an output-feedback control method is used based on the nominal model with the subordinate uncertainty elements from the previous step. Finally, the proposed control system implemented experimentally on the real structure is to evaluate the robust vibration attenuation performance of the closed-loop system.

  14. Body Mass Index, Metabolic Factors, and Striatal Activation During Stressful and Neutral-Relaxing States: An fMRI Study

    OpenAIRE

    Jastreboff, Ania M; Potenza, Marc N; Lacadie, Cheryl; Hong, Kwangik A; Sherwin, Robert S; Sinha, Rajita

    2010-01-01

    Stress is associated with alterations in neural motivational-reward pathways in the ventral striatum (VS), hormonal/metabolic changes, and weight increases. The relationship between these different factors is not well understood. We hypothesized that body mass index (BMI) status and hormonal/metabolic factors would be associated with VS activation. We used functional magnetic resonance imaging (fMRI) to compare brain responses of overweight and obese (OW/OB: BMI ⩾25 kg/m2: N=27) individuals w...

  15. Real-time fMRI neurofeedback to down-regulate superior temporal gyrus activity in patients with schizophrenia and auditory hallucinations: a proof-of-concept study.

    Science.gov (United States)

    Orlov, Natasza D; Giampietro, Vincent; O'Daly, Owen; Lam, Sheut-Ling; Barker, Gare