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Sample records for active mri implants

  1. 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.

  2. 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.)

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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.)

  2. 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.)

  3. 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

  4. 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.)

  5. 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)

  6. 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)

  7. 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)

  8. 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.

  9. 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.

  10. 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.

  11. [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.

  12. 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

  13. 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.

  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. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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

  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. 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.

  4. 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.)

  5. 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.

  6. 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

  7. 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)

  8. 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

  9. 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.

  10. 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...

  11. 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.

  12. 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.

  13. 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)

  14. 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

  15. 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.

  16. 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 ...

  17. 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.

  18. 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

  19. 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.

  20. Evaluation of 39 medical implants at 7.0 T

    Science.gov (United States)

    Feng, David X; McCauley, Joseph P; Morgan–Curtis, Fea K; Salam, Redoan A; Pennell, David R; Loveless, Mary E

    2015-01-01

    Objective: With increased signal to noise ratios, 7.0-T MRI has the potential to contribute unique information regarding anatomy and pathophysiology of a disease. However, concerns for the safety of subjects with metallic medical implants have hindered advancement in this field. The purpose of the present research was to evaluate the MRI safety for 39 commonly used medical implants at 7.0 T. Methods: Selected metallic implants were tested for magnetic field interactions, radiofrequency-induced heating and artefacts using standardized testing techniques. Results: 5 of the 39 implants tested may be unsafe for subjects undergoing MRI at 7.0 T. Conclusion: Implants were deemed either “MR Conditional” or “MR Unsafe” for the 7.0-T MRI environment. Further research is needed to expand the existing database categorizing implants that are acceptable for patients referred for MRI examinations at 7.0 T. Advances in knowledge: Lack of MRI testing for common metallic medical implants limits the translational potential of 7.0-T MRI. For safety reasons, patients with metallic implants are not allowed to undergo a 7.0-T MRI scan, precluding part of the population that can benefit from the detailed resolution of ultra-high-field MRIs. This investigation provides necessary MRI testing of common medical implants at 7.0 T. PMID:26481696

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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...

  7. 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

  8. 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.)

  9. 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.

  10. 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 ...

  11. 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.

  12. 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.

  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

    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.)

  15. 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.)

  16. 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. ...

  17. 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(

  18. 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 ...

  19. PIP breast implants: rupture rate and correlation with breast cancer.

    Science.gov (United States)

    Moschetta, M; Telegrafo, M; Cornacchia, I; Vincenti, L; Ranieri, V; Cirili, A; Rella, L; Stabile Ianora, A A; Angelelli, G

    2014-01-01

    To evaluate the incidence of Poly Implant Prosthése (PIP) rupture as assessed by magnetic resonance imaging (MRI), the prevalence of the detected signs and the potential correlation with breast carcinoma. 67 patients with silicone breast implants and clinical indications for breast MRI were evaluated for a total of 125 implants: 40 (32%) PIP in 21 patients and 85 non-PIP in 46 patients (68%), the latest considered as control group. A 1.5-T MR imaging device was used in order to assess implant integrity with dedicated sequences and in 6 cases a dynamic study was performed for characterizing breast lesions. Two radiologists with more than 5 years' experience in the field of MRI evaluated in consensus all MR images searching for the presence of clear signs of intra or extra-capsular implant rupture. 20/40 (50%) PIP implants presented signs of intra-capsular rupture: linguine sign in 20 cases (100%), tear-drop sign in 6 (30%). In 12/20 cases (60%), MRI signs of extra-capsular rupture were detected. In the control group, an intra-capsular rupture was diagnosed in 12/85 cases (14%) associated with extra-capsular one in 5/12 cases (42%). Among the six cases with suspected breast lesions, in 2/21 patients with PIP implants (10%) a breast carcinoma was diagnosed (mucinous carcinoma, n=1; invasive ductal carcinoma, n=1). In 4/46 patients (9%) with non-PIP implants, an invasive ductal carcinoma was diagnosed. The rupture rate of PIP breast implants is significantly higher than non-PIP (50% vs 14%). MRI represents the most accurate imaging tool for evaluating breast prostheses and the linguine sign is the most common MRI sign to be searched. The incidence of breast carcinoma does not significantly differ between the PIP and non-PIP implants and a direct correlation with breast cancer can not been demonstrated.

  20. 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.

  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. People with the ...

  2. The diagnosis of breast implant rupture

    DEFF Research Database (Denmark)

    Hölmich, Lisbet R; Vejborg, Ilse; Conrad, Carsten

    2005-01-01

    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...... 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...

  3. 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.

  4. Analysis of 30 breast implant rupture cases.

    Science.gov (United States)

    Tark, Kwan Chul; Jeong, Hii Sun; Roh, Tae Suk; Choi, Jong Woo

    2005-01-01

    Breast implants used for augmentation mammoplasty or breast reconstruction could rupture from various causes such as trauma or spontaneous failure. The objectives of this study were to investigate the relationships between the causes of implant rupture and the degree of capsular contracture, and then to evaluate the relative efficacies of specific signs on magnetic resonance imaging (MRI) known to be beneficial for diagnosing the rupture. A retrospective review identified patients with prosthetic implant rupture or impending rupture treated by the senior author. The 30 cases of implant rupture available for review were classified into two groups: intracapsular and extracapsular ruptures. The 30 cases of breast implant ruptures were analyzed with respect to the clinical symptoms and signs, the causes of rupture, the degree of capsular contracture, and therapeutic plans. Among the 30 cases, 14 patients who had undergone MRI during the diagnostic period were analyzed with respect to the relationships between MRI readings and operative findings. Spontaneous rupture of membranes was most common (80%), followed by failure because of trauma (7%) and valve or implant base (4%). The symptoms during implant rupture were contour deformity, palpated mass-like lesions, pain, and focal inflammation. According to the analysis of specific MRI signs, the sensitivity and specificity of the linguine sign were 87% and 100%, respectively, for intracapsular rupture. For extracapsular rupture, the sensitivity and specificity of the linguine sign were, respectively, 67% and 75%. The sensitivity and specificity of the rat-tail sign and tear drop sign were 14% and 50%, respectively. Breast implant rupture was correlated with the degree of capsular contracture in our study. Among the various specific MRI signs used in diagnosing the rupture, the linguine sign was reliable and had a high sensitivity and specificity, especially in cases of intracapsular rupture. On the other hand, the rat

  5. 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

  6. 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.

  7. 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 ...

  8. 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

  9. 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.

  10. 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. ...

  11. 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 ...

  12. Assessment of functional recovery after autologous implantation of neural progenitor cells for the treatment of traumatic brain injury

    International Nuclear Information System (INIS)

    Wu Xing; Zhang Dong; Zuo Zhuantao; Ge Feng; Zhu Jianhong; Zhou Liangfu

    2005-01-01

    Objective: To assess the functional recovery in the patients with traumatic brain injury (TBI) after autologous implantation of neural progenitor cells, and 7 counterparts with matched age, injury location and extent were chosen as the control. Methods: Neural progenitor cells were isolated from exposed brain tissue and propagated for 25 to 30 d, then implanted the autologous neural progenitor cells at seven points around the traumatic regions with MRI-stereotactic guiding device for 7 patients. All recruited patients underwent 18 F-fluorodeox-yglucose (FDG) PET imaging, function MRI (fMRI) and assessment of Glasgow outcome scale extended (GOSE) after operation for open brain trauma. The examinations were repeated one month after neural progenitor cell implantation and then repeated every 3 months during follow-up in the first year, and every 6 months in the second year. The same examinations were performed on untreated counterparts at similar intervals for avoiding deviations of spontaneous recovery. The data were analyzed with region of interest (ROI) and statistical parametric mapping (SPM). Results: At the third month of follow-up, mean tracer uptake in the damaged territory in implantation group increased significantly (P 18 F-FDG in the top of precentral gyrus was significantly increased in implantation group, and the metabolism of 18 F-FDG in the frontal lobe was significantly elevated postoperation according to paired SPM analysis. The activation in fMRI maps was seen in the motor cortex since the third month after implantation, whereas no active signals were detected before implantation or in control group. At the 6th month of follow-up, mean score of GOSE in the group of implantation was 6.63±0.52, whereas the mean score was 4.50 ±0.76 in control group (P 18 F-FDG uptake in the injured area was 3 months prior to the elevation of GOSE. Conclusions: The results of the study show that 18 F-FDG PET and fMRI both showed significantly increased neurological

  13. 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 ...

  14. 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.

  15. 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....

  16. 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.

  17. 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

  18. Linguine sign in musculoskeletal imaging: calf silicone implant rupture.

    Science.gov (United States)

    Duryea, Dennis; Petscavage-Thomas, Jonelle; Frauenhoffer, Elizabeth E; Walker, Eric A

    2015-08-01

    Imaging findings of breast silicone implant rupture are well described in the literature. On MRI, the linguine sign indicates intracapsular rupture, while the presence of silicone particles outside the fibrous capsule indicates extracapsular rupture. The linguine sign is described as the thin, wavy hypodense wall of the implant within the hyperintense silicone on T2-weighted images indicative of rupture of the implant within the naturally formed fibrous capsule. Hyperintense T2 signal outside of the fibrous capsule is indicative of an extracapsular rupture with silicone granuloma formation. We present a rare case of a patient with a silicone calf implant rupture and discuss the MRI findings associated with this condition.

  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. Customizable cap implants for neurophysiological experimentation.

    Science.gov (United States)

    Blonde, Jackson D; Roussy, Megan; Luna, Rogelio; Mahmoudian, Borna; Gulli, Roberto A; Barker, Kevin C; Lau, Jonathan C; Martinez-Trujillo, Julio C

    2018-04-22

    Several primate neurophysiology laboratories have adopted acrylic-free, custom-fit cranial implants. These implants are often comprised of titanium or plastic polymers, such as polyether ether ketone (PEEK). Titanium is favored for its mechanical strength and osseointegrative properties whereas PEEK is notable for its lightweight, machinability, and MRI compatibility. Recent titanium/PEEK implants have proven to be effective in minimizing infection and implant failure, thereby prolonging experiments and optimizing the scientific contribution of a single primate. We created novel, customizable PEEK 'cap' implants that contour to the primate's skull. The implants were created using MRI and/or CT data, SolidWorks software and CNC-machining. Three rhesus macaques were implanted with a PEEK cap implant. Head fixation and chronic recordings were successfully performed. Improvements in design and surgical technique solved issues of granulation tissue formation and headpost screw breakage. Primate cranial implants have traditionally been fastened to the skull using acrylic and anchor screws. This technique is prone to skin recession, infection, and implant failure. More recent methods have used imaging data to create custom-fit titanium/PEEK implants with radially extending feet or vertical columns. Compared to our design, these implants are more surgically invasive over time, have less force distribution, and/or do not optimize the utilizable surface area of the skull. Our PEEK cap implants served as an effective and affordable means to perform electrophysiological experimentation while reducing surgical invasiveness, providing increased strength, and optimizing useful surface area. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

  1. 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

  2. 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

  3. 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

  4. 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.

  5. Linguine sign in musculoskeletal imaging: calf silicone implant rupture

    International Nuclear Information System (INIS)

    Duryea, Dennis; Petscavage-Thomas, Jonelle; Frauenhoffer, Elizabeth E.; Walker, Eric A.

    2015-01-01

    Imaging findings of breast silicone implant rupture are well described in the literature. On MRI, the linguine sign indicates intracapsular rupture, while the presence of silicone particles outside the fibrous capsule indicates extracapsular rupture. The linguine sign is described as the thin, wavy hypodense wall of the implant within the hyperintense silicone on T2-weighted images indicative of rupture of the implant within the naturally formed fibrous capsule. Hyperintense T2 signal outside of the fibrous capsule is indicative of an extracapsular rupture with silicone granuloma formation. We present a rare case of a patient with a silicone calf implant rupture and discuss the MRI findings associated with this condition. (orig.)

  6. Linguine sign in musculoskeletal imaging: calf silicone implant rupture

    Energy Technology Data Exchange (ETDEWEB)

    Duryea, Dennis; Petscavage-Thomas, Jonelle [Milton S. Hershey Medical Center, Department of Radiology, H066, 500 University Drive, P.O. Box 850, Hershey, PA (United States); Frauenhoffer, Elizabeth E. [Milton S. Hershey Medical Center, Department of Pathology, 500 University Drive, P.O. Box 850, Hershey, PA (United States); Walker, Eric A. [Milton S. Hershey Medical Center, Department of Radiology, H066, 500 University Drive, P.O. Box 850, Hershey, PA (United States); Uniformed Services University of the Health Sciences, Department of Radiology and Nuclear Medicine, Bethesda, MD, 20814 (United States)

    2015-08-15

    Imaging findings of breast silicone implant rupture are well described in the literature. On MRI, the linguine sign indicates intracapsular rupture, while the presence of silicone particles outside the fibrous capsule indicates extracapsular rupture. The linguine sign is described as the thin, wavy hypodense wall of the implant within the hyperintense silicone on T2-weighted images indicative of rupture of the implant within the naturally formed fibrous capsule. Hyperintense T2 signal outside of the fibrous capsule is indicative of an extracapsular rupture with silicone granuloma formation. We present a rare case of a patient with a silicone calf implant rupture and discuss the MRI findings associated with this condition. (orig.)

  7. 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.

  8. 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)

  9. 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.)

  10. 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.)

  11. 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.

  12. Artefacts in multimodal imaging of titanium, zirconium and binary titanium-zirconium alloy dental implants: an in vitro study.

    Science.gov (United States)

    Smeets, Ralf; Schöllchen, Maximilian; Gauer, Tobias; Aarabi, Ghazal; Assaf, Alexandre T; Rendenbach, Carsten; Beck-Broichsitter, Benedicta; Semmusch, Jan; Sedlacik, Jan; Heiland, Max; Fiehler, Jens; Siemonsen, Susanne

    2017-02-01

    To analyze and evaluate imaging artefacts induced by zirconium, titanium and titanium-zirconium alloy dental implants. Zirconium, titanium and titanium-zirconium alloy implants were embedded in gelatin and MRI, CT and CBCT were performed. Standard protocols were used for each modality. For MRI, line-distance profiles were plotted to quantify the accuracy of size determination. For CT and CBCT, six shells surrounding the implant were defined every 0.5 cm from the implant surface and histogram parameters were determined for each shell. While titanium and titanium-zirconium alloy induced extensive signal voids in MRI owing to strong susceptibility, zirconium implants were clearly definable with only minor distortion artefacts. For titanium and titanium-zirconium alloy, the MR signal was attenuated up to 14.1 mm from the implant. In CT, titanium and titanium-zirconium alloy resulted in less streak artefacts in comparison with zirconium. In CBCT, titanium-zirconium alloy induced more severe artefacts than zirconium and titanium. MRI allows for an excellent image contrast and limited artefacts in patients with zirconium implants. CT and CBCT examinations are less affected by artefacts from titanium and titanium-zirconium alloy implants compared with MRI. The knowledge about differences of artefacts through different implant materials and image modalities might help support clinical decisions for the choice of implant material or imaging device in the clinical setting.

  13. Artefacts in multimodal imaging of titanium, zirconium and binary titanium–zirconium alloy dental implants: an in vitro study

    Science.gov (United States)

    Schöllchen, Maximilian; Aarabi, Ghazal; Assaf, Alexandre T; Rendenbach, Carsten; Beck-Broichsitter, Benedicta; Semmusch, Jan; Sedlacik, Jan; Heiland, Max; Fiehler, Jens; Siemonsen, Susanne

    2017-01-01

    Objectives: To analyze and evaluate imaging artefacts induced by zirconium, titanium and titanium–zirconium alloy dental implants. Methods: Zirconium, titanium and titanium–zirconium alloy implants were embedded in gelatin and MRI, CT and CBCT were performed. Standard protocols were used for each modality. For MRI, line–distance profiles were plotted to quantify the accuracy of size determination. For CT and CBCT, six shells surrounding the implant were defined every 0.5 cm from the implant surface and histogram parameters were determined for each shell. Results: While titanium and titanium–zirconium alloy induced extensive signal voids in MRI owing to strong susceptibility, zirconium implants were clearly definable with only minor distortion artefacts. For titanium and titanium–zirconium alloy, the MR signal was attenuated up to 14.1 mm from the implant. In CT, titanium and titanium–zirconium alloy resulted in less streak artefacts in comparison with zirconium. In CBCT, titanium–zirconium alloy induced more severe artefacts than zirconium and titanium. Conclusions: MRI allows for an excellent image contrast and limited artefacts in patients with zirconium implants. CT and CBCT examinations are less affected by artefacts from titanium and titanium–zirconium alloy implants compared with MRI. The knowledge about differences of artefacts through different implant materials and image modalities might help support clinical decisions for the choice of implant material or imaging device in the clinical setting. PMID:27910719

  14. 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.

  15. 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.

  16. Magnetic resonance imaging-a diagnostic tool for postoperative evaluation of dental implants: a case report.

    Science.gov (United States)

    Wanner, Laura; Ludwig, Ute; Hövener, Jan-Bernd; Nelson, Katja; Flügge, Tabea

    2018-04-01

    Compared with cone beam computed tomography (CBCT), magnetic resonance imaging (MRI) might be superior for the diagnosis of nerve lesions associated with implant placement. A patient presented with unilateral pain associated with dysesthesia in the region of the right lower lip and chin after implant placement. Conventional orthopantomography could not identify an association between the position of the inferior alveolar nerve and the implant. For 3-dimensional display of the implant in relation to the surrounding anatomy, CBCT was compared with MRI. MRI enabled the precise depiction of the implant position and its spatial relation to the inferior alveolar nerve, whereas the nerve position and its exact course within the mandible could not be directly displayed in CBCT. MRI may be a valuable, radiation-free diagnostic tool for the visualization of intraoral hard and soft tissues, offering an objective assessment of nerve injuries by a direct visualization of the inferior alveolar neurovascular bundle. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. 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.

  18. Intracapsular implant rupture: MR findings of incomplete shell collapse.

    Science.gov (United States)

    Soo, M S; Kornguth, P J; Walsh, R; Elenberger, C; Georgiade, G S; DeLong, D; Spritzer, C E

    1997-01-01

    The objective of this study was to determine the frequency and significance of the MR findings of incomplete shell collapse for detecting implant rupture in a series of surgically removed breast prostheses. MR images of 86 breast implants in 44 patients were studied retrospectively and correlated with surgical findings at explantation. MR findings included (a) complete shell collapse (linguine sign), 21 implants; (b) incomplete shell collapse (subcapsular line sign, teardrop sign, and keyhole sign), 33 implants; (c) radial folds, 31 implants; and (d) normal, 1 implant. The subcapsular line sign was seen in 26 implants, the teardrop sign was seen in 27 implants, and the keyhole sign was seen in 23 implants. At surgery, 48 implants were found to be ruptured and 38 were intact. The MR findings of ruptured implants showed signs of incomplete collapse in 52% (n = 25), linguine sign in 44% (n = 21), and radial folds in 4% (n = 2). The linguine sign perfectly predicted implant rupture, but sensitivity was low. Findings of incomplete shell collapse improved sensitivity and negative predictive values, and the subcapsular line sign produced a significant incremental increase in predictive ability. MRI signs of incomplete shell collapse were more common than the linguine sign in ruptured implants and are significant contributors to the high sensitivity and negative predictive values of MRI for evaluating implant integrity.

  19. Revision surgery due to magnet dislocation in cochlear implant patients: an emerging complication.

    Science.gov (United States)

    Hassepass, Frederike; Stabenau, Vanessa; Maier, Wolfgang; Arndt, Susan; Laszig, Roland; Beck, Rainer; Aschendorff, Antje

    2014-01-01

    To analyze the cause and effect of magnet dislocation in cochlear implant (CI) recipients requiring magnet revision surgery for treatment. Retrospective study. Tertiary referral center. Case reports from 1,706 CI recipients consecutively implanted from January 2000 to December 2011 were reviewed. The number of cases requiring magnet revision surgery was assessed. Revision surgery involving magnet removal or replacement was indicated in 1.23% (21/1,706), of all CI recipients. Magnet dislocation occurring during magnetic resonance tomography (MRI), at 1.5 Tesla (T), with the magnet in place and with the application of compression bandaging around the head, was the main cause for revision surgery in 47.62% (10/21) of the affected cases. All 10 cases were implanted with Cochlear Nucleus cochlear implants. These events occurred, despite adherence to current recommendations of the manufacturer. The present study underlines that MRI examination is the main cause of magnet dislocation. The use of compressive bandaging when using 1.5-T MRI does not eliminate the risk of magnet dislocation. Additional cautionary measures are for required for conditional MRI. We recommend X-ray examination after MRI to determine magnet dislocation and avoid major complications in all cases reporting pain during or after MRI. Additional research regarding silicon magnet pocket design for added retention is needed. Effective communication of guidelines for precautionary measures during MRI examination in CI patients is mandatory for all clinicians involved. MRI in CI recipients should be indicated with caution.

  20. 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

  1. 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

  2. The preoperative imaging evaluation for cochlear implantation

    International Nuclear Information System (INIS)

    Liu Zhonglin; Wang Zhenchang; Fu Lin; Li Yong; Xian Junfang; Yang Bentao; Lan Baosen; Li Yongxin; Zheng Jun; Song Yan; Liu Bo; Chen Xueqing; He Haili

    2006-01-01

    Objective: To analyze CT and MRI findings of temporal bone and to evaluate preoperative diagnostic value for cochlear implantation. Methods: One hundred and sixty candidates for cochlear implantation were examined with axial CT scan, 64 of them also with coronal CT scan, and 119 patients with MRI. Results: All of 320 ears were well-aerated, and 206 ears had mastoid cavities extended posteriorly to the sigmoid sinus. The length from posterior-lateral tympanic wall to the outer cortex was (2.34±0.42) mm (left side) and (2.25±0.40) mm (right side) (U=1.887, P 1 and T 2 signal on MRI. The congenital malformations of inner ear occurred in 67 ears, including complete dysplasia in 1 ear, cochlear hypodysplasia in 6 ears, Mondini deformation in 5 ears, enlarged vestibular aqueduct in 40 ears, dysplastic semicircular canal and the vestibulae in 10 ears, and narrowing of internal auditory canal in 5 ears. Conclusion: Preoperative imaging examinations can provide critical information to ensure successful cochlear' implantation. (authors)

  3. 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 ...

  4. CT evaluation of preoperative cochlear implantation cochlear implantation

    International Nuclear Information System (INIS)

    Tan Xiuzhong; Zhong Lansheng; Lan Bowen; Huang Yaosheng; Du Baowen; Zhu Jian

    2004-01-01

    Objective: To evaluate CT scan as a preoperative evaluation for cochlear implantation candidates. Methods: Axial high-resolution temporal bone CT and three-dimensional reconstruction of inner ear were performed in 93 patients with sensorineural hearing loss. results: Among 81 patients with congenital sensorineural deafness, Mondini malformation was seen in 7 case (13 ears); large vestibular aqueduct syndrome (LVAS) was revealed in 5 cases (8 ears); and inner ear ossification was found in 1 case (2 ears). In 1 case (2 ears) of inner ear fibrosis, reduced cochlear signal was noted on MRI but no unremarkable findings was shown on CT scan, however, in the operation, the device could not inserted into the basal circle of the cochlea, due to fibrous obliteration. In 12 patients with post-speech deafness, chronic suppurative tympanitis was seen in 2 cases (4 ears), and inner ear ossification was revealed in 1 case (2 ears). Conclusion: CT plays an indispensable role in the pre-operative evaluation of cochlear implantation. T 2 -weighted FSE-MRI of the inner ear is a useful complementary to CT scan. (authors)

  5. 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. ...

  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 ... 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 ...

  8. 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 ...

  9. 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 ...

  10. 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 ...

  11. Complexity of MRI induced heating on metallic leads: Experimental measurements of 374 configurations

    Directory of Open Access Journals (Sweden)

    Mendoza Gonzalo

    2008-03-01

    Full Text Available Abstract Background MRI induced heating on PM leads is a very complex issue. The widely varying results described in literature suggest that there are many factors that influence the degree of heating and that not always are adequately addressed by existing testing methods. Methods We present a wide database of experimental measurements of the heating of metallic wires and PM leads in a 1.5 T RF coil. The aim of these measurements is to systematically quantify the contribution of some potential factors involved in the MRI induced heating: the length and the geometric structure of the lead; the implant location within the body and the lead path; the shape of the phantom used to simulate the human trunk and its relative position inside the RF coil. Results We found that the several factors are the primary influence on heating at the tip. Closer locations of the leads to the edge of the phantom and to the edge of the coil produce maximum heating. The lead length is the other crucial factor, whereas the implant area does not seem to have a major role in the induced temperature increase. Also the lead structure and the geometry of the phantom revealed to be elements that can significantly modify the amount of heating. Conclusion Our findings highlight the factors that have significant effects on MRI induced heating of implanted wires and leads. These factors must be taken into account by those who plan to study or model MRI heating of implants. Also our data should help those who wish to develop guidelines for defining safe medical implants for MRI patients. In addition, our database of the entire set of measurements can help those who wish to validate their numerical models of implants that may be exposed to MRI systems.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. MRI and morphological observation in C6 glioma model rats and significance

    International Nuclear Information System (INIS)

    Zhou Ying; Yuan Bo; Wang Hao; Lu Jin; Yuan Changji; Ma Yue; Tong Dan; Zhang Kun; Gao Feng; Wu Xiaogang

    2013-01-01

    Objective: To establish stable and reliable rat C6 glioma model, and to perform MRI dynamic observation and pathomorphological observation in model animal brain, and to provide experimental basis for pharmaceutical research on anti-glioma drugs. Methods: The C6 glioma cells were cultured and 20 μL cultural fluid containing 1×10 6 C6 cells was sterotactically implanted into the left caudate nuclei in 10 male Wistar rats, respectively. The changes in the behavior of the rats after implantation were observed and recorded. MRI dynamic scanning was performed in 10 rats 2, 3 and 4 weeks after implantation and the brain tissues were taken for general and pathological examination when the 10 rats were naturally dead. The survival period of tumor-bearing rats was calculated. Results: 2 weeks after implantation the rats showed decreased activities and food intake, fur lackluster, and conjunctival congestion and so on; 3 weeks later, some rats appeared nerve symptoms such as body twitch, body hemiplegy, body distortion, rotation and so on. All the 10 rats died in 8-30 d. The median survival period of the tumor-bearing rats was 18 d, the average survival period was (18.3±7.3) d. The pathological examination showed that the tumor cells were arranged irregularly closely and karyokinesis was easy to see; tumor vascular tissue proliferation and tumor invasive growth into surrounding normal tissues were found. The expression of glial fibrillary acidic protein (GFAP) was positive in the tumors. Conclusion: A stable animal model of intracranial glioma is successfully established by stereotactic implantation of C6 cells into the rat caudate nucleus. The results of MRI dynamic observation and pathohistological observation on the model animal brain tissue. Can provide experimental basis for selecting the appropriate time window to perform the pharmaceutical research on anti-glioma drugs. (authors)

  19. Reversing the polarity of a cochlear implant magnet after magnetic resonance imaging.

    Science.gov (United States)

    Jeon, Ju Hyun; Bae, Mi Ran; Chang, Jae Won; Choi, Jae Young

    2012-08-01

    The number of patients with cochlear implant (CI) has been rapidly increasing in recent years, and these patients show a growing need of examination by magnetic resonance imaging (MRI). However, the use of MRI on patients with CI is restricted by the internal magnet of the CI. Many studies have investigated the safety of performing 1.5T MRI on patients with CI, which is now being practiced in a clinical setting. We experienced a case in which the polarity of the cochlear implant magnet was reversed after the patient was examined using 1.5T MRI. The external device was attached to the internal device oppositely. We could not find displacement of the internal device, magnet, or electrode upon radiological evaluation. We came up with two possible mechanisms by which the polarity of the magnet reversed. The first possibility was that the magnetic field of MRI reversed the polarity of the magnet. The second was that the internal magnet was physically realigned while interacting with the MRI. We believe the second hypothesis to be more reliable. A removable magnet and a loose magnet boundary of a CI device may have allowed for physical reorientation of the internal magnet. Therefore, in order to avoid these complications, first, the internal magnet must not be aligned anti-parallel with the magnetic polarity of MRI. In the Siemens MRI, the vector of the magnetic field is downward, so implant site should be placed in facing upwards to minimize demagnetization. In the GE Medical Systems MRI, the vector of the magnetic field is upward, so the implant site should be placed facing downwards. Second, wearing of a commercial mold which is fixed to the internal device before performing MRI can be helpful. In addition, any removable internal magnets in a CI device should be removed before MRI, especially in the trunk. However, to ultimately solve this problem, the pocket of the internal magnet should be redesigned for safety. Copyright © 2011. Published by Elsevier Ireland Ltd.

  20. 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.

  1. 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.

  2. Scattering of the radiofrequency electromagnetic field by orthopedic bone support frame implants

    International Nuclear Information System (INIS)

    Mohsin, S.A.; Sheikh, N.M.

    2009-01-01

    The interaction of the fields in MRI (Magnetic Resonance Imaging) with orthopedic implants is investigated. The primary interaction is the scattering of the MRI RF (Radiofrequency) field by the implants. As a specific case study, the scattel-cd field due to a bone support frame implant is computed by the finite-element-method. The support frame has steel pins of significant length embedded in tissue. The induced surface current distributions on the steel pins and the spatial electric field distributions in the surrounding tissue have been obtained. (author)

  3. 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

  4. 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.

  5. 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

  6. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    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. ...

  7. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    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 ...

  8. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    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 ...

  9. Magnetic Resonance Imaging (MRI) -- Head

    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 ...

  10. 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 ...

  11. A Rare Complication of Cochlear Implantation After Magnetic Resonance Imaging: Reversion of the Magnet.

    Science.gov (United States)

    Öztürk, Erkan; Doruk, Can; Orhan, Kadir Serkan; Çelik, Mehmet; Polat, Beldan; Güldiken, Yahya

    2017-06-01

    Cochlear implants are mechanical devices used for patients with severe sensory-neural hearing loss, which has an inner magnet. It is proven that 1.5 Tesla magnetic resonance imaging (MRI) scanners are safe to use in patients with cochlear implant. In our patient, the authors aim to introduce a rare complication caused after a 1.5 Tesla MRI scanning and the management of this situation; the reversion of the magnet of the implant without displacement and significance of surgery in management.

  12. MRI in patients with pacemakers? First global consensus recommendations from radiologists and cardiologists

    International Nuclear Information System (INIS)

    Heindel, Walter; Kugel, Harald

    2017-01-01

    Under the title ''MR Imaging in Patients with Cardiac Pacemakers and Implantable Cardioverter Defibrillators'', this issue of Roefo - simultaneously with the journal of the German Cardiac Society ''Der Kardiologe'' - presents a consensus paper of the German Roentgen Society and the German Cardiac Society [1] [2] that was jointly written by the authors in radiology and cardiology but does not exclusively address cardiac MRI. This publication relates to MR imaging of all regions of the body. In Germany and internationally the number of MRI examinations is increasing: 1,008,944 examinations were performed on patients receiving inpatient treatment in 2005 while 1,767,005 examinations were performed in 2013 (DRG hospitals). This development can be attributed to our aging population as well as to new indications for MRI including: Analyses of tissue composition and function, for example in the liver [3] [4] and the heart [5] [6]; multiparametric analyses of MR perfusion, e.g. in treated brain tumors [7]; new organs such as the lung [8]; dedicated examinations for intervention planning and operation monitoring [9] [10] [11]; as well as MRI-guided interventions [12] [13] [14] [15] [16]. Implants must always be considered in all of these MRI examinations even if the reason for the examination request is not related to an implant. The involvement of cardiology in this case is not based on the medical issue but rather on the type of implant. Expertise in cardiology is required when dealing with cardiac pacemakers (PM) and implantable cardioverter defibrillators (ICD).

  13. Differentiation of prostate cancer from normal prostate tissue in an animal model: conventional MRI and dynamic contrast-enhanced MRI

    International Nuclear Information System (INIS)

    Gemeinhardt, O.; Prochnow, D.; Taupitz, M.; Hamm, B.; Beyersdorff, D.; Luedemann, L.; Abramjuk, C.

    2005-01-01

    Purpose: to differentiate orthotopically implanted prostate cancer from normal prostate tissue using magnetic resonance imaging (MRI) and Gd-DTPA-BMA-enhanced dynamic MRI in the rat model. Material and methods: tumors were induced in 15 rats by orthotopic implantation of G subline Dunning rat prostatic tumor cells. MRI was performed 56 to 60 days after tumor cell implantation using T1-weighted spin-echo, T2-weighted turbo SE sequences, and a 2D FLASH sequence for the contrast medium based dynamic study. The interstitial leakage volume, normalized permeability and the permeability surface area product of tumor and healthy prostate were determined quantitatively using a pharmacokinetic model. The results were confirmed by histologic examination. Results: axial T2-weighted TSE images depicted low-intensity areas suspicious for tumor in all 15 animals. The mean tumor volume was 46.5 mm3. In the dynamic study, the suspicious areas in all animals displayed faster and more pronounced signal enhancement than surrounding prostate tissue. The interstitial volume and the permeability surface area product of the tumors increased significantly by 420% (p<0.001) and 424% (p<0.001), respectively, compared to normal prostate tissue, while no significant difference was seen for normalized permeability alone. Conclusion: the results of the present study demonstrate that quantitative analysis of contrast-enhanced dynamic MRI data enables differentiation of small, slowly growing orthotopic prostate cancer from normal prostate tissue in the rat model. (orig.)

  14. 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.)

  15. 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.)

  16. 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.

  17. 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...

  18. 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

  19. 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

  20. 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)

  1. 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.

  2. 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.

  3. 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.

  4. Modeling of electrodes and implantable pulse generator cases for the analysis of implant tip heating under MR imaging

    International Nuclear Information System (INIS)

    Acikel, Volkan; Atalar, Ergin; Uslubas, Ali

    2015-01-01

    Purpose: The authors’ purpose is to model the case of an implantable pulse generator (IPG) and the electrode of an active implantable medical device using lumped circuit elements in order to analyze their effect on radio frequency induced tissue heating problem during a magnetic resonance imaging (MRI) examination. Methods: In this study, IPG case and electrode are modeled with a voltage source and impedance. Values of these parameters are found using the modified transmission line method (MoTLiM) and the method of moments (MoM) simulations. Once the parameter values of an electrode/IPG case model are determined, they can be connected to any lead, and tip heating can be analyzed. To validate these models, both MoM simulations and MR experiments were used. The induced currents on the leads with the IPG case or electrode connections were solved using the proposed models and the MoTLiM. These results were compared with the MoM simulations. In addition, an electrode was connected to a lead via an inductor. The dissipated power on the electrode was calculated using the MoTLiM by changing the inductance and the results were compared with the specific absorption rate results that were obtained using MoM. Then, MRI experiments were conducted to test the IPG case and the electrode models. To test the IPG case, a bare lead was connected to the case and placed inside a uniform phantom. During a MRI scan, the temperature rise at the lead was measured by changing the lead length. The power at the lead tip for the same scenario was also calculated using the IPG case model and MoTLiM. Then, an electrode was connected to a lead via an inductor and placed inside a uniform phantom. During a MRI scan, the temperature rise at the electrode was measured by changing the inductance and compared with the dissipated power on the electrode resistance. Results: The induced currents on leads with the IPG case or electrode connection were solved for using the combination of the MoTLiM and

  5. 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.

  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 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 ...

  8. 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...

  9. A novel brain stimulation technology provides compatibility with MRI.

    Science.gov (United States)

    Serano, Peter; Angelone, Leonardo M; Katnani, Husam; Eskandar, Emad; Bonmassar, Giorgio

    2015-04-29

    Clinical electrical stimulation systems--such as pacemakers and deep brain stimulators (DBS)--are an increasingly common therapeutic option to treat a large range of medical conditions. Despite their remarkable success, one of the significant limitations of these medical devices is the limited compatibility with magnetic resonance imaging (MRI), a standard diagnostic tool in medicine. During an MRI exam, the leads used with these devices, implanted in the body of the patient, act as an electric antenna potentially causing a large amount of energy to be absorbed in the tissue, which can lead to serious heat-related injury. This study presents a novel lead design that reduces the antenna effect and allows for decreased tissue heating during MRI. The optimal parameters of the wire design were determined by a combination of computational modeling and experimental measurements. The results of these simulations were used to build a prototype, which was tested in a gel phantom during an MRI scan. Measurement results showed a three-fold decrease in heating when compared to a commercially available DBS lead. Accordingly, the proposed design may allow a significantly increased number of patients with medical implants to have safe access to the diagnostic benefits of MRI.

  10. Fully automated MRI-guided robotics for prostate brachytherapy

    International Nuclear Information System (INIS)

    Stoianovici, D.; Vigaru, B.; Petrisor, D.; Muntener, M.; Patriciu, A.; Song, D.

    2008-01-01

    The uncertainties encountered in the deployment of brachytherapy seeds are related to the commonly used ultrasound imager and the basic instrumentation used for the implant. An alternative solution is under development in which a fully automated robot is used to place the seeds according to the dosimetry plan under direct MRI-guidance. Incorporation of MRI-guidance creates potential for physiological and molecular image-guided therapies. Moreover, MRI-guided brachytherapy is also enabling for re-estimating dosimetry during the procedure, because with the MRI the seeds already implanted can be localised. An MRI compatible robot (MrBot) was developed. The robot is designed for transperineal percutaneous prostate interventions, and customised for fully automated MRI-guided brachytherapy. With different end-effectors, the robot applies to other image-guided interventions of the prostate. The robot is constructed of non-magnetic and dielectric materials and is electricity free using pneumatic actuation and optic sensing. A new motor (PneuStep) was purposely developed to set this robot in motion. The robot fits alongside the patient in closed-bore MRI scanners. It is able to stay fully operational during MR imaging without deteriorating the quality of the scan. In vitro, cadaver, and animal tests showed millimetre needle targeting accuracy, and very precise seed placement. The robot tested without any interference up to 7T. The robot is the first fully automated robot to function in MRI scanners. Its first application is MRI-guided seed brachytherapy. It is capable of automated, highly accurate needle placement. Extensive testing is in progress prior to clinical trials. Preliminary results show that the robot may become a useful image-guided intervention instrument. (author)

  11. How safe is magnetic resonance imaging in patients with contraceptive implants

    International Nuclear Information System (INIS)

    Muehler, M.; Taupitz, M.

    2006-01-01

    When patients with an implanted contraceptive device undergo MRI, it must be ensured that the examination involves no risk to the patient (MR safety) and that the diagnosis is not affected by artifacts or the function of the device compromised (MR compatibility). Two basic types of intrauterine devices can be distinguished: the metal-containing/metal-free intrauterine device (IUD) and the hormone-containing implant, the fully metal-free intrauterine system (IUS), as well as the ESSURE insert made of stainless steel, which has been approved for use in Europe since February 2001. The metal-containing and metal-free IUDs and ESSURE are MRI compatible up to a magnetic field strength of 1.5 T. They do not interact in any relevant way with the external magnetic or high-frequency field and the temperature increase is within the physiologic range. The implants merely produce a local signal void with a shape that depends on their orientation relative to the magnetic field lines. At 3 T, only the metal-free IUD and the IUS are MRI safe in terms of the material used. In contrast, metal-containing IUDs and the ESSURE have not yet been fully evaluated in the 3 T field, which is why they represent a contraindication to MRI. No data are available on the MRI compatibility at 3 T for any of these devices. (orig.) [de

  12. 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

  13. 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.

  14. 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.

  15. [Magnetic resonance imaging in patients with implantable devices for treatment of disturbed heart rhythm: review of the current situation].

    Science.gov (United States)

    Sviridova, A A

    The question of the possibility of MRI scanning in patients with cardiac implantable electronic devices (CIED) appeared simultaneously with the introduction of MRI in clinical practice. A lot of in-vitro, in-vivo and clinical researches were performed to estimate wat going on with CIED in strong magnetic field and is it possible to perform some unified protocol of safe MRI-scanning for these patients. Recommendations were provided, but not for the wide practice. MRI remained strongly contraindicated for CIED patient. To meet the clinical need CIEM manufacturers changed the design of devices to made them MRI-compatible, including reducing of ferromagnetic components, additional filters, new software. Lead coil design was changed as well to minimize lead heating and electrical current induction. Now all leaders of CIED industry have in their portfolio all types of MRI-conditional implanted cardiac rhythm management devices (pacemakers, ICDs, CRTs). "Conditional" means MRI scanning can be done only under specific condition. For MRI device and lead in one system have to be from the same manufacturer. Now, if you need to implant the device, you must proceed from the fact that the patient is more likely to need an MRI in the future and choose the appropriate model, not forgetting that the electrodes should also be MRI-compatible.

  16. Evaluation of permanent I-125 prostate implants using radiography and magnetic resonance imaging

    International Nuclear Information System (INIS)

    Moerland, Marinus A.; Wijrdeman, Harm K.; Beersma, Robert; Bakker, Chris J.G.; Battermann, Jan J.

    1997-01-01

    Purpose: The aim of this study is the evaluation of permanent I-125 prostate implants using radiography and magnetic resonance imaging (MRI). Methods and Materials: Twenty-one patients underwent radiography on the simulator and MRI 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 seed-induced signal voids on MRI provided the seed positions in relation to the prostate. The prostate was contoured on the transversal magnetic resonance images, and dose-volume histograms were computed to evaluate the implants. The validity of the ellipsoidal prostate volume approximation, as applied in preimplant dose calculation, was assessed by comparison of ellipsoidal volumes given by prostate width, height, and length and prostate volumes obtained by a slice-by-slice contouring method, both on postimplant MRI. Prostate volume changes due to postimplant prostate swelling were assessed from radiographs taken at 3 days and 1 month after the implantation. Results: The seeds were readily identified on T 1 -weighted spin-echo images and matched with the seed distribution reconstructed from the isocentric radiographs. The matching error, averaged over 21 patients, amounted to 1.8 ± 0.4 mm (mean ± standard deviation). The fractions of the prostate volumes receiving the prescribed matched peripheral dose (MPD) ranged from 32 to 71% (mean ± standard deviation: 60 ± 10%). Prostate volumes, obtained by the contouring method on postimplant MRI, were a factor 1.5 ± 0.3 larger than the ellipsoidal volumes given by the prostate dimensions on postimplant MRI. Prostate volumes 3 days after the implantation were a factor 1.3 ± 0.2 larger than the prostate volumes 1 month after the implantation. Registration of the reconstructed seed distribution and the MR images showed inaccuracies in seed placement, for example, two or more seeds clustering together or seeds outside the prostate

  17. 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...

  18. [Factors for Degaussing of a Cochlear Implant Magnet in the MR Scanner].

    Science.gov (United States)

    Koganezawa, Takumi; Uchiyama, Naoko; Teshigawara, Mai; Ogura, Akio

    This study examined the conditions influencing degauss of the magnet using magnetic resonance imaging (MRI). Poly methyl methacrylate (PMMA) was used to fix the measurement magnets to the MRI bed at angles from 0° to 180° for the magnetic flux vector of static magnetic field. The PMMA was moved in the MRI magnetic field. Magnetic flux density was measured before and after bed movement, and the rate of degauss was calculated. The contents examined are as follows: (1) the angle of the magnetic flux vector of the measurement magnets for the magnetic flux vector of the static magnetic field, (2) the number of movements, (3) moving velocity, and (4) the movement on the spatial gradient of magnetic field. Mann-Whitney U test was used for statistical analysis of the data. In conclusion, the effect of the angle of the magnetic flux vector of the implant magnet was high under the conditions of degauss in this study. Therefore, during the MRI examination of a patient with a cochlear implant magnet, the operators identified the directions of the magnetic flux vector and static magnetic field of the implant magnet.

  19. 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

  20. 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

  1. A feasibility study of magnetic resonance imaging of silicone breast implants in Finland

    DEFF Research Database (Denmark)

    Kulmala, Ilona; Boice, John D; McLaughlin, Joseph K

    2005-01-01

    to determine the feasibility of conducting a magnetic resonance imaging (MRI)-based study of rupture incidence. The pilot investigation included a clinical examination by a plastic surgeon, MRI scan, and self-administered questionnaire. The participation rate was 100%. Implants in our study represented a cross...... the other diagnosed all implants as intact. The procedures of the feasibility study proved successful, and the results demonstrate the importance of a rigid image evaluation protocol with employment of well-defined rupture criteria, as well as the benefits of several image readers.......Cosmetic breast implants have become increasingly popular throughout the world. However, there is insufficient knowledge about the frequency and severity of local complications such as rupture and capsular contracture. A pilot study of 25 Finnish women with 50 cosmetic breast implants was organized...

  2. Magnetic resonance imaging in cadaver dogs with metallic vertebral implants at 3 Tesla: evaluation of the WARP-turbo spin echo sequence.

    Science.gov (United States)

    Griffin, John F; Archambault, Nicholas S; Mankin, Joseph M; Wall, Corey R; Thompson, James A; Padua, Abraham; Purdy, David; Kerwin, Sharon C

    2013-11-15

    Laboratory investigation, ex vivo. Postoperative complications are common after spinal implantation procedures, and magnetic resonance imaging (MRI) would be the ideal modality to image these patients. Unfortunately, the implants cause artifacts that can render MRI nondiagnostic. The WARP-turbo spin echo (TSE) sequence has been developed to mitigate artifacts caused by metal. The objective of this investigation was to evaluate the performance of the WARP-TSE sequence in canine cadaver specimens after implantation with metallic vertebral implants. Magnetic field strength, implant type, and MRI acquisition technique all play a role in the severity of susceptibility artifacts. The WARP-TSE sequence uses increased bandwidth, view angle tilting, and SEMAC (slice-encoding metal artifact correction) to correct for susceptibility artifact. The WARP-TSE technique has outperformed conventional techniques in patients, after total hip arthroplasty. However, published reports of its application in subjects with vertebral column implants are lacking. Ex vivo anterior stabilization of the atlantoaxial joint was performed on 6 adult small breed (implantation with stainless steel implants. N/A.

  3. Safety of a dedicated brain MRI protocol in patients with a vagus nerve stimulator.

    Science.gov (United States)

    de Jonge, Jeroen C; Melis, Gerrit I; Gebbink, Tineke A; de Kort, Gérard A P; Leijten, Frans S S

    2014-11-01

    Although implanted metallic devices constitute a relative contraindication to magnetic resonance imaging (MRI) scanning, the safety of brain imaging in a patient with a vagus nerve stimulator (VNS) is classified as "conditional," provided that specific manufacturer guidelines are followed when a transmit and receive head coil is used at 1.5 or 3.0 Tesla. The aim of this study was to evaluate the safety of performing brain MRI scans in patients with the VNS. From September 2009 until November 2011, 101 scans were requested in 73 patients with the VNS in The Netherlands. Patients were scanned according to the manufacturer's guidelines. No patient reported any side effect, discomfort, or pain during or after the MRI scan. In one patient, a lead break was detected based on device diagnostics after the MRI-scan. However, because no system diagnostics had been performed prior to MR scanning in this patient, it is unclear whether MR scanning was responsible for the lead break. The indication for most scans was epilepsy related. Twenty-six scans (26%) were part of a (new) presurgical evaluation and could probably better have been performed prior to VNS implantation. Performing brain MRI scans in patients with an implanted VNS is safe when a modified MRI protocol is followed. Wiley Periodicals, Inc. © 2014 International League Against Epilepsy.

  4. Magnetic Resonance Imaging (MRI) -- Head

    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 ... called MR angiography (MRA) provides detailed images of blood vessels in the ... the opening of certain types of MRI machines. The presence of an implant ...

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. Detection of Brain Reorganization in Pediatric Multiple Sclerosis Using Functional MRI

    Science.gov (United States)

    2014-10-01

    7.5 years). Pediatric temporal lobe epilepsy patients who undergo clinically-indicated Wada test and/or implantation of subdural electrodes with...cohort. 2.6. Validation of fMRI in temporal lobe epilepsy patients: The validation of passive language fMRI was carried out on patient cohort 1...made up of 15 pediatric-onset temporal lobe epilepsy surgical patients all of whom had some form of invasive mapping for comparisons against fMRI

  10. Prevalence of inner ear anomalies among cochlear implant candidates.

    Science.gov (United States)

    Aldhafeeri, Ahmad M; Alsanosi, Abdulrahman A

    2016-10-01

    To determine the prevalence of inner ear anomalies and the frequency of different anomaly types among cochlear implant recipients. This study included a retrospective chart review of all patients who received cochlear implants between January 2009 and January 2013 in King Abdulaziz University Hospital cochlear implant program in Riyadh, Saudi Arabia. All subjects underwent thin-cut CT of the temporal bone and MRI. The collected data included age, gender, and CT and MRI findings regarding temporal bone anomalies. Patients with any identified congenital inner ear anomalies were included in the study.  In total, 316 patients' cases were reviewed. Inner ear malformations were identified in 24 patients, which represented a prevalence of 7.5%. Among these 24 patients, 8 (33.3%) presented with a large vestibular aqueduct (LVA), 8 (33.3%) semicircular canal (SCC) dysplasia, 7 (29.1%) classical Mondini deformity, and one (4.1%) cochlear hypoplasia. The prevalence of inner ear anomalies among cochlear implant recipients was 7.5%. This result is consistent with findings worldwide. The most common anomalies were LVA and SCC hypoplasia; by contrast, in other regions, the most common anomaly is either the Mondini deformity, or LVA.

  11. Dependence of excitation frequency of resonant circuit on RF irradiation position of MRI equipment

    International Nuclear Information System (INIS)

    Shimizu, Masato; Yamada, Tsutomu; Takemura, Yasushi; Niwa, Touru; Inoue, Tomio

    2010-01-01

    Hyperthermia using implants is a cancer treatment in which cancer tissue is heated to over 42.5 deg C to selectively kill the cancer cells. In this study, a resonant circuit was used as an implant, and a weak magnetic field of radiofrequency (RF) pulses from a magnetic resonance imaging (MRI) device was used as an excitation source. We report here how the temperature of the resonant circuit was controlled by changing the excitation frequency of the MRI. As a result, the temperature rise of the resonant circuit was successfully found to depend on its position in the MRI device. This significant result indicates that the temperature of the resonant circuit can be controlled only by adjusting the excitation position. Accurate temperature control is therefore expected to be possible by combining this control technique with the temperature measurement function of MRI equipment. (author)

  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. Murine liver implantation of radiation-induced fibrosarcoma: characterization with MR imaging, microangiography and histopathology

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huaijun; Keyzer, Frederik de; Jin, Lixin; Yu, Jie; Marchal, Guy; Ni, Yicheng [Catholic University of Leuven, Department of Radiology, University Hospitals, Leuven (Belgium); Putte, Marie van de; Witte, Peter de [K.U. Leuven, Laboratory for Pharmaceutical Biology, Faculty of Pharmaceutical Sciences, Leuven (Belgium); Chen, Feng [Catholic University of Leuven, Department of Radiology, University Hospitals, Leuven (Belgium); Southeast University, Department of Radiology, Zhong Da Hospital, Nanjing, Jiangsu Province (China)

    2008-07-15

    We sought to establish and characterize a mouse liver tumor model as a platform for preclinical assessment of new diagnostics and therapeutics. Radiation-induced fibrosarcoma (RIF-1) was intrahepatically implanted in 27 C3H/Km mice. Serial in vivo magnetic resonance imaging (MRI) with a clinical 1.5-T-magnet was performed using T1- (T1WI), T2- (T2WI), and diffusion-weighted sequences (DWI), dynamic contrast-enhanced MRI (DCE-MRI), and contrast-enhanced T1WI, and validated with postmortem microangiography and histopathology. Implantation procedure succeeded in 25 mice with 2 deaths from overdosed anesthesia or hypothermia. RIF-1 grew in 21 mice with volume doubling time of 2.55{+-}0.88 days and final size of 216.2{+-}150.4 mm{sup 3} at day 14. Three mice were found without tumor growth and one only with abdominal seeding. The intrahepatic RIF-1 was hypervascularized with negligible necrosis as shown on MRI, microangiography and histology. On DCE-MRI, maximal initial slope of contrast-time curve and volume transfer constant per unit volume of tissue, K, differed between the tumor and liver with only the former significantly lower in the tumor than in the liver (P<0.05). Liver implantation of RIF-1 in mice proves a feasible and reproducible model and appears promising for use to screen new diagnostics and therapeutics under noninvasive monitoring even with a clinical MRI system. (orig.)

  14. Murine liver implantation of radiation-induced fibrosarcoma: characterization with MR imaging, microangiography and histopathology

    International Nuclear Information System (INIS)

    Wang, Huaijun; Keyzer, Frederik de; Jin, Lixin; Yu, Jie; Marchal, Guy; Ni, Yicheng; Putte, Marie van de; Witte, Peter de; Chen, Feng

    2008-01-01

    We sought to establish and characterize a mouse liver tumor model as a platform for preclinical assessment of new diagnostics and therapeutics. Radiation-induced fibrosarcoma (RIF-1) was intrahepatically implanted in 27 C3H/Km mice. Serial in vivo magnetic resonance imaging (MRI) with a clinical 1.5-T-magnet was performed using T1- (T1WI), T2- (T2WI), and diffusion-weighted sequences (DWI), dynamic contrast-enhanced MRI (DCE-MRI), and contrast-enhanced T1WI, and validated with postmortem microangiography and histopathology. Implantation procedure succeeded in 25 mice with 2 deaths from overdosed anesthesia or hypothermia. RIF-1 grew in 21 mice with volume doubling time of 2.55±0.88 days and final size of 216.2±150.4 mm 3 at day 14. Three mice were found without tumor growth and one only with abdominal seeding. The intrahepatic RIF-1 was hypervascularized with negligible necrosis as shown on MRI, microangiography and histology. On DCE-MRI, maximal initial slope of contrast-time curve and volume transfer constant per unit volume of tissue, K, differed between the tumor and liver with only the former significantly lower in the tumor than in the liver (P<0.05). Liver implantation of RIF-1 in mice proves a feasible and reproducible model and appears promising for use to screen new diagnostics and therapeutics under noninvasive monitoring even with a clinical MRI system. (orig.)

  15. 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

  16. Intra-prosthetic breast MR virtual navigation: a preliminary study for a new evaluation of silicone breast implants.

    Science.gov (United States)

    Moschetta, Marco; Telegrafo, Michele; Capuano, Giulia; Rella, Leonarda; Scardapane, Arnaldo; Angelelli, Giuseppe; Stabile Ianora, Amato Antonio

    2013-10-01

    To assess the contribute of intra-prosthetic MRI virtual navigation for evaluating breast implants and detecting implant ruptures. Forty-five breast implants were evaluated by MR examination. Only patients with a clinical indication were assessed. A 1.5-T device equipped with a 4-channel breast coil was used by performing axial TSE-T2, axial silicone-only, axial silicone suppression and sagittal STIR images. The obtained dicom files were also analyzed by using virtual navigation software. Two blinded radiologists evaluated all MR and virtual images. Eight patients for a total of 13 implants underwent surgical replacement. Sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated for both imaging strategies. Intra-capsular rupture was diagnosed in 13 out of 45 (29%) implants by using MRI. Basing on virtual navigation, 9 (20%) cases of intra-capsular rupture were diagnosed. Sensitivity, specificity, accuracy, PPV and NPV values of 100%, 86%, 89%, 62% and 100%, respectively, were found for MRI. Virtual navigation increased the previous values up to 100%, 97%, 98%, 89% and 100%. Intra-prosthetic breast MR virtual navigation can represent an additional promising tool for the evaluation of breast implants being able to reduce false positives and to provide a more accurate detection of intra-capsular implant rupture signs. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. SU-E-J-232: Feasibility of MRI-Based Preplan On Low Dose Rate Prostate Brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y; Tward, J; Rassiah-Szegedi, P; Zhao, H; Sarkar, V; Huang, L; Szegedi, M; Kokeny, K; Salter, B [University of Utah Huntsman Cancer Institute, Salt Lake City, UT (United States)

    2015-06-15

    Purpose: To investigate the feasibility of using MRI-based preplan for low dose rate prostate brachytherapy. Methods: 12 patients who received transrectal ultrasound (TRUS) guided prostate brachytherapy with Pd-103 were retrospectively studied. Our care-standard of the TRUS-based preplan served as the control. One or more prostate T2-weighted wide and/or narrow-field of view MRIs obtained within the 3 months prior to the implant were imported into the MIM Symphony software v6.3 (MIM Software Inc., Cleveland, OH) for each patient. In total, 37 MRI preplans (10 different image sequences with average thickness of 4.8mm) were generated. The contoured prostate volume and the seed counts required to achieve adequate dosimetric coverage from TRUS and MRI preplans were compared for each patient. The effects of different MRI sequences and image thicknesses were also investigated statistically using Student’s t-test. Lastly, the nomogram from the MRI preplan and TRUS preplan from our historical treatment data were compared. Results: The average prostate volume contoured on the TRUS and MRI were 26.6cc (range: 12.6∼41.3cc), and 27.4 cc (range: 14.3∼50.0cc), respectively. Axial MRI thicknesses (range: 3.5∼8.1mm) did not significantly affect the contoured volume or the number of seeds required on the preplan (R2 = 0.0002 and 0.0012, respectively). Four of the MRI sequences (AX-T2, AX-T2-Whole-Pelvis, AX-T2-FSE, and AXIALT2- Hi-Res) showed statistically significant better prostate volume agreement with TRUS than the other seven sequences (P <0.01). Nomogram overlay between the MRI and TRUS preplans showed good agreement; indicating volumes contoured on MRI preplan scan reliably predict how many seeds are needed for implant. Conclusion: Although MRI does not allow for determination of the actual implant geometry, it can give reliable volumes for seed ordering purposes. Our future work will investigate if MRI is sufficient to reliably replace TRUS preplanning in patients

  18. Selective laser melting of titanium alloy enables osseointegration of porous multi-rooted implants in a rabbit model.

    Science.gov (United States)

    Peng, Wei; Xu, Liangwei; You, Jia; Fang, Lihua; Zhang, Qing

    2016-07-21

    Osseointegration refers to the direct connection between living bone and the surface of a load-bearing artificial implant. Porous implants with well-controlled porosity and pore size can enhance osseointegration. However, until recently implants were produced by machining solid core titanium rods. The aim of this study was to develop a multi-rooted dental implant (MRI) with a connected porous surface structure to facilitate osseointegration. MRIs manufactured by selective laser melting (SLM) and commercial implants with resorbable blasting media (RBM)-treated surfaces were inserted into the hind limbs of New Zealand white rabbits. Osseointegration was evaluated periodically over 12 weeks by micro-computerized tomography (CT) scanning, histological analysis, mechanical push-out tests, and torque tests. Bone volume densities were consistently higher in the MRI group than in the RBM group throughout the study period, ultimately resulting in a peak value of 48.41 % for the MRI group. Histological analysis revealed denser surrounding bone growth in the MRIs; after 4 and 8 weeks, bone tissue had grown into the pore structures and root bifurcation areas, respectively. Biomechanics tests indicated binding of the porous MRIs to the neobone tissues, as push-out forces strengthened from 294.7 to 446.5 N and maximum mean torque forces improved from 81.15 to 289.57 N (MRI), versus 34.79 to 87.8 N in the RBM group. MRIs manufactured by SLM possess a connected porous surface structure that improves the osteogenic characteristics of the implant surface.

  19. Ex-PRESS glaucoma filter: an MRI compatible metallic orbital foreign body imaged at 1.5 and 3 T

    International Nuclear Information System (INIS)

    Mabray, M.C.; Uzelac, A.; Talbott, J.F.; Lin, S.C.; Gean, A.D.

    2015-01-01

    Aim: To report on the MRI compatibility of the Ex-PRESS glaucoma filtration device, a tiny metallic implant placed into the anterior chamber of the eye that is much smaller than traditional glaucoma shunts, and to educate the radiology community regarding its appearance. Materials and methods: Seven patients with Ex-PRESS glaucoma filtration devices were identified that had undergone MRI at San Francisco General Hospital/University of California San Francisco Medical Center by searching and cross-referencing the radiology reporting system and the electronic medical record. MRI images were reviewed for artefact interfering with interpretation. Ophthalmology examinations were reviewed for evidence of complications. Results: Eighteen individual MRI examinations were performed during 12 unique MRI events on these 7 patients. 13/18 individual MRI examinations and 7/12 MRI events were performed at 3 T with the others performed at 1.5 T. Mean time from Ex-PRESS implantation to MRI was 17.5 months. Mean time from MRI to first ophthalmology examination was 1.1 months and from MRI to latest ophthalmology examination was 6.6 months. Susceptibility artefact did not interfere with image interpretation and no complications related to MRI were encountered. Conclusion: The Ex-PRESS glaucoma filtration device appears to be safe for MRI at 1.5 and 3 T and does not produce significant susceptibility artefact to affect diagnostic interpretation adversely. - Highlights: • The Ex-PRESS glaucoma filtration device is a tiny metallic orbital implant. • It can simulate a metallic orbital foreign body on imaging. • There is little information in the literature about it's MRI safety. • We report 18 MRIs performed on 7 patients including the first at 3 T. • Imaging appears to be safe at 1.5 and 3 T in patients with this device

  20. 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

  1. 3 Tesla MRI of patients with a vagus nerve stimulator: initial experience using a T/R head coil under controlled conditions.

    Science.gov (United States)

    Gorny, Krzysztof R; Bernstein, Matt A; Watson, Robert E

    2010-02-01

    To assess safety of clinical MRI of the head in patients with implanted model 100, 102, and 103 vagus nerve stimulation (VNS) Therapy Systems (Cyberonics, Inc., Houston, TX) in 3.0 Tesla MRI (GE Healthcare, Milwaukee, WI). The distributions of the radiofrequency B(1) (+)-field produced by the clinically used transmit/receive (T/R) head coil (Advanced Imaging Research Incorporated, Cleveland, OH) and body coil were measured in a head and shoulders phantom. These measurements were supplemented by temperature measurements on the lead tips and the implantable pulse generator (IPG) of the VNS devices in a head and torso phantom with the same two coils. Clinical 3T MRI head scans were then acquired under highly controlled conditions in a series of 17 patients implanted with VNS. Phantom studies showed only weak B(1) (+) fields at the location of the VNS IPG and leads for MRI scans using the T/R head coil. The MRI-related heating on a VNS scanned in vitro at 3T was also found to be minimal (0.4-0.8 degrees C at the leads, negligible at the IPG). The patient MRI examinations were completed successfully without any adverse incidents. No patient reported any heating, discomfort, or any other unusual sensation. Safe clinical MRI head scanning of patients with implanted VNS is shown to be feasible on a GE Signa Excite 3T MRI system using one specific T/R head coil. These results apply to this particular MRI system configuration. Extrapolation or generalization of these results to more general or less controlled imaging situations without supporting data of safety is highly discouraged.

  2. 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.

  3. MRI-tracking of transplanted human ASC in a SCID mouse model

    Energy Technology Data Exchange (ETDEWEB)

    Siegmund, Birte J.; Kasten, Annika [Department of Oral and Maxillofacial Surgery, Facial Plastic Surgery, Rostock University Medical Center (Germany); Kühn, Jens-Peter [Institute of Diagnostic Radiology and Neuroradiology, Greifswald University Medical Center (Germany); Winter, Karsten [Institute of Anatomy, Faculty of Medicine, University of Leipzig (Germany); Grüttner, Cordula [Micromod Partikeltechnologie GmbH, Rostock (Germany); Frerich, Bernhard, E-mail: bernhard.frerich@med.uni-rostock.de [Department of Oral and Maxillofacial Surgery, Facial Plastic Surgery, Rostock University Medical Center (Germany)

    2017-04-01

    Background: Regarding strategies improving the efficacy of stem cell transplantation in adipose tissue engineering, cell tracking might be useful. Here we report the in vivo tracking of adipose tissue derived stem cells (ASC) by means of nanoparticle labeling and magnetic resonance imaging (MRI). Here we report the in vivo tracking of adipose tissue derived stromal cells (ASC) by means of nanoparticle labeling and magnetic resonance imaging (MRI). Materials and methods: Human ASC were amplified and labeled with two types of magnetic nanoparticles (MNP), BNF starch and nanomag®-D-spio. Adipose tissue constructs were fabricated by seeding collagen scaffolds with labeled and unlabeled ASCs. Constructs were implanted subcutaneously in the back of severe combined immunodeficient (SCID) mice (n =69, group 1: control with cells w/o label, group 2: BNF starch labeled cells, group 3: nanomag®-D-spio labeled cells). MRI scans were performed at 24 hours, four, twelve and 28 days and four months in a 7.1 T animal device. Explanted constructs were analyzed histomorphometrically. Results: MRI scans showed high contrast of the labeled cells in t2-tse-sequence compared to unlabeled controls. Loss of volume of the implants was observed over time due to partial loss for transplanted cells without significant difference (level of significance p<0.017). Compared to histomorphometry, there was found a positiv correlations in measurement of implant size with a significant at day four (correlation coefficient =0.643; p=0.024) and day twelve (correlation coefficient =0.687; p=0.010). Additional Prussian blue stain showed iron in all implants. Significant differences between the three groups (significance level p<0.017) were found after twelve days between control group and group 3 (p=0.008) and after 28 days between control group and group 2 and 3 (p=0.011). Conclusion: Both MNPs might be suitable for tracking of ASC in vivo and show long term stability over 4 months. - Highlights:

  4. Outcomes of Interventional-MRI Versus Microelectrode Recording-Guided Subthalamic Deep Brain Stimulation

    Directory of Open Access Journals (Sweden)

    Philip S. Lee

    2018-04-01

    Full Text Available In deep brain stimulation (DBS of the subthalamic nucleus (STN for Parkinson’s disease (PD, there is debate concerning the use of neuroimaging alone to confirm correct anatomic placement of the DBS lead into the STN, versus the use of microelectrode recording (MER to confirm functional placement. We performed a retrospective study of a contemporaneous cohort of 45 consecutive patients who underwent either interventional-MRI (iMRI or MER-guided DBS lead implantation. We compared radial lead error, motor and sensory side effect, and clinical benefit programming thresholds, and pre- and post-operative unified PD rating scale scores, and levodopa equivalent dosages. MER-guided surgery was associated with greater radial error compared to the intended target. In general, side effect thresholds during initial programming were slightly lower in the MER group, but clinical benefit thresholds were similar. No significant difference in the reduction of clinical symptoms or medication dosage was observed. In summary, iMRI lead implantation occurred with greater anatomic accuracy, in locations demonstrated to be the appropriate functional region of the STN, based on the observation of similar programming side effect and benefit thresholds obtained with MER. The production of equivalent clinical outcomes suggests that surgeon and patient preference can be used to guide the decision of whether to recommend iMRI or MER-guided DBS lead implantation to appropriate patients with PD.

  5. 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

  6. A prospective study on silicone breast implants and the silicone-related symptom complex.

    Science.gov (United States)

    Contant, C M E; Swaak, A J G; Obdeijn, A I M; van der Holt, B; Tjong Joe Wai, R; van Geel, A N; Eggermont, A M M

    2002-06-01

    This cohort study prospectively evaluated the prevalence of the silicone-related symptom complex (SRSC) in relation to antinuclear antibodies (ANA) and magnetic resonance imaging (MRI) of silicone breast implants (SBI) 1 year after implantation. A total of 57 women undergoing mastectomy followed by immediate breast reconstruction (IBR) and SBI between March 1995 and March 1997 at the University Hospital Rotterdam/Daniel den Hoed Cancer Centre, were prospectively evaluated. Just before and 1 year after IBR the sera of these women were tested for the presence of ANA and they were screened for the prevalence of SRSC-related symptoms by questionnaire. All prostheses were evaluated by MRI 1 month and 1 year after IBR. Just before operation 11% of the women had a Sjögren score of more than 2, whereas 30% had such a score 1 year after IBR ( P = 0.01). One year postoperatively women had significantly more RA/Raynaud-related complaints: 21% preoperatively versus 40% 1 year after IBR ( P = 0.03). Within the undefined complaints-related group 19% had a score of 2 or more preoperatively and 33% 1 year after IBR ( P = 0.09). There were no new cases of ANA positivity 1 year after IBR. The linguine sign was seen by MRI in three implants: one 1 month after IBR and two 1 year after IBR. There was no relation to changes in SRSC expression and these MRI findings. In conclusion, 1 year after SBI implantation women had more SRSC-related complaints, especially Sjögren's and RA/Raynaud's. Moreover there was no correlation between elevated SRSC expression and changes in the presence of ANA or changes in MRI of the SBI 1 year after IBR.

  7. Investigation of radio frequency heating of dental implants made of titanium in 1.5 tesla and 3.0 tesla magnetic resonance procedure. Measurement of the temperature by using tissue-equivalent phantom

    International Nuclear Information System (INIS)

    Ideta, Takahiro; Yamazaki, Masaru; Kudou, Sadahiro; Higashida, Mitsuji; Nakazawa, Masami; Mori, Shintarou; Kaneda, Takashi

    2013-01-01

    Titanium (Ti) implants are increasingly being used for dental parts. There is no problem with the attraction of a static magnetic field for Ti in magnetic resonance imaging (MRI), since Ti is paramagnetic. However, there is a risk of radio frequency (RF) heat generation within Ti. 3.0 T-MRI scanners are becoming increasingly common. The specific absorption rate (SAR) of 3.0 T-MRI is quadruple that of SAR compared with 1.5 T-MRI due to its being proportional to the square of the strength of a static magnetic field. The effect of heat generation in 3.0 T-MRI can thus be greater than in 1.5 T-MRI. So, using 1.5 T and 3.0 T-MRI scanners, we measured the temperature of several Ti implants using the same scanning parameters during MRI scanning. Our measurements showed the rise in temperature of the Ti implants to be a maximum of 0.4degC. In this study, however, Ti in a human mouth was not directly measured, so we need to attempt to perform MRI carefully on patients with Ti implants. (author)

  8. 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

  9. 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

  10. Magnetic Resonance Imaging With Cochlear Implant Magnet in Place: Safety and Imaging Quality.

    Science.gov (United States)

    Carlson, Matthew L; Neff, Brian A; Link, Michael J; Lane, John I; Watson, Robert E; McGee, Kiaran P; Bernstein, Matt A; Driscoll, Colin L W

    2015-07-01

    To evaluate the safety and image quality of 1.5-T MRI in patients with cochlear implants and retained internal magnets. Retrospective case series from 2012 to 2014. Single tertiary academic referral center. All cochlear implant recipients undergoing 1.5-T MRI without internal magnet removal. MRI after tight headwrap application. Patient tolerance, complications, and characteristics of imaging artifact. Nineteen ears underwent a total of 34 MRI scans. Two patients did not tolerate imaging with the headwrap in place and required magnet removal before rescanning. One subject experienced two separate episodes of polarity reversal in the same device from physical realignment (i.e., flipping) of the internal magnet requiring surgical repositioning. Three patients were discovered to have canting of the internal magnet after imaging. In all three cases, the magnet could be reseated by applying gentle firm pressure to the scalp until the magnet "popped" back into place. These patients continue to use their device without difficulty and have not required surgical replacement. In patients receiving head MRI, the ipsilateral internal auditory canal and cerebellopontine angle could be visualized without difficulty in 94% of cases. There were no episodes of cochlear implant device failure or soft tissue complications. Under controlled conditions, 1.5-T MRI can be successfully performed in most patients without the need for cochlear implant magnet removal. In nearly all cases, imaging artifact does not impede evaluation of the ipsilateral skull base. Patients should be counseled regarding the risk of internal magnet movement that may occur in up to 15% of cases, even with tight headwrap application. If internal magnet polarity reversal occurs, a trial of reversing the external magnet can be considered. If canting or mild displacement of the internal magnet occurs, an attempt at reseating can be made by applying gentle firm pressure to the scalp over the internal magnet. If

  11. 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.

  12. Magnetic resonance imaging of an equine fracture model containing stainless steel metal implants.

    Science.gov (United States)

    Pownder, S L; Koff, M F; Shah, P H; Fortier, L A; Potter, H G

    2016-05-01

    Post operative imaging in subjects with orthopaedic implants is challenging across all modalities. Magnetic resonance imaging (MRI) is preferred to assess human post operative musculoskeletal complications, as soft tissue and bones are evaluated without using ionising radiation. However, with conventional MRI pulse sequences, metal creates susceptibility artefact that distorts anatomy. Assessment of the post operative equine patient is arguably more challenging due to the volume of metal present, and MRI is often not performed in horses with implants. Novel pulse sequences such as multiacquisition variable resonance image combination (MAVRIC) now provide improved visibility in the vicinity of surgical-grade implants and offer an option for imaging horses with metal implants. To compare conspicuity of regional anatomy in an equine fracture-repair model using MAVRIC, narrow receiver bandwidth (NBW) fast spin echo (FSE), and wide receiver bandwidth (WBW) FSE sequences. Nonrandomised in vitro experiment. MAVRIC, NBW FSE and WBW FSE were performed on 9 cadaveric distal limbs with fractures and stainless steel implants in the third metacarpal bone and proximal phalanx. Objective measures of artefact reduction were performed by calculating the total artefact area in each transverse image as a percentage of the total anatomic area. The number of transverse images in which fracture lines were visible was tabulated for each sequence. Regional soft tissue conspicuity was assessed subjectively. Overall anatomic delineation was improved using MAVRIC compared with NBW FSE; delineation of structures closest to the metal implants was improved using MAVRIC compared with WBW FSE and NBW FSE. Total artefact area was the highest for NBW FSE and lowest for MAVRIC; the total number of transverse slices with a visible fracture line was highest in MAVRIC and lowest in NBW FSE. MAVRIC and WBW FSE are feasible additions to minimise artefact around implants. © 2015 EVJ Ltd.

  13. 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

  14. Pre-, intra- and post-operative imaging of cochlear implants

    Energy Technology Data Exchange (ETDEWEB)

    Vogl, T.J.; Naguib, N.N.N.; Burck, I. [University Hospital Frankfurt (Germany). Inst. of Diagnostic and Interventional Radiology; Tawfik, A. [Mansoura Univ. (Egypt). Dept. of Diagnostic and Interventional Radiology; Emam, A. [University Hospital Alexandria (Egypt). Dept. of Diagnostic and Interventional Radiology; Nour-Eldin, A. [University Hospital Cairo (Egypt). Dept. of Radiology; Stoever, T. [University Hospital of Frankfurt (Germany). Dept. of Otolaryngology

    2015-11-15

    The purpose of this review is to present essential imaging aspects in patients who are candidates for a possible cochlear implant as well as in postsurgical follow-up. Imaging plays a major role in providing information on preinterventional topography, variations and possible infections. Preoperative imaging using DVT, CT, MRI or CT and MRI together is essential for candidate selection, planning of surgical approach and exclusion of contraindications like the complete absence of the cochlea or cochlear nerve, or infection. Relative contraindications are variations of the cochlea and vestibulum. Intraoperative imaging can be performed by fluoroscopy, mobile radiography or DVT. Postoperative imaging is regularly performed by conventional X-ray, DVT, or CT. In summary, radiological imaging has its essential role in the pre- and post-interventional period for patients who are candidates for cochlear implants.

  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. 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

  17. 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.)

  18. Poly Implant Prothèse (PIP) incidence of rupture: a retrospective MR analysis in 64 patients.

    Science.gov (United States)

    Scotto di Santolo, Mariella; Cusati, Bianca; Ragozzino, Alfonso; Dell'Aprovitola, Nicoletta; Acquaviva, Alessandra; Altiero, Michele; Accurso, Antonello; Riccardi, Albina; Imbriaco, Massimo

    2014-12-01

    The purpose of this retrospective study was to describe the magnetic resonance imaging (MRI) features of Poly Implant Prothèse (PIP) hydrogel implants in a group of 64 patients and to assess the incidence of rupture, compared to other clinical trials. In this double-center study, we retrospectively reviewed the data sets of 64 consecutive patients (mean age, 43±9 years, age range, 27-65 years), who underwent breast MRI examinations, between January 2008 and October 2013, with suspected implant rupture on the basis of clinical assessment or after conventional imaging examination (either mammography or ultrasound). All patients had undergone breast operation with bilateral textured cohesive gel PIP implant insertion for aesthetic reasons. The mean time after operation was 8 years (range, 6-14 years). No patients reported history of direct trauma to their implants. At the time of clinical examination, 41 patients were asymptomatic, 16 complained of breast tenderness and 7 had clinical evidence of rupture. Normal findings were observed in 15 patients. In 26 patients there were signs of mild collapse, with associated not significant peri-capsular fluid collections and no evidence of implant rupture; in 23 patients there was suggestion of implant rupture, according to breast MRI leading to an indication for surgery. In particular, 14 patients showed intra-capsular rupture, with associated evidence of the linguine sign in all cases; the keyhole sign and the droplet signs were observed in 6 cases. In 9 patients there was evidence of extra-capsular rupture, with presence of axillary collections (siliconomas) in 7 cases and peri-prosthetic and mediastinal cavity siliconomas, in 5 cases. The results of this double center retrospective study, confirm the higher incidence (36%) of prosthesis rupture observed with the PIP implants, compared to other breast implants.

  19. Phase-contrast MRI versus numerical simulation to quantify hemodynamical changes in cerebral aneurysms after flow diverter treatment

    Science.gov (United States)

    Frolov, Sergey; Prothmann, Sascha; Liepsch, Dieter; Balasso, Andrea; Berg, Philipp; Kaczmarz, Stephan; Kirschke, Jan Stefan

    2018-01-01

    Cerebral aneurysms are a major risk factor for intracranial bleeding with devastating consequences for the patient. One recently established treatment is the implantation of flow-diverters (FD). Methods to predict their treatment success before or directly after implantation are not well investigated yet. The aim of this work was to quantitatively study hemodynamic parameters in patient-specific models of treated cerebral aneurysms and its correlation with the clinical outcome. Hemodynamics were evaluated using both computational fluid dynamics (CFD) and phase contrast (PC) MRI. CFD simulations and in vitro MRI measurements were done under similar flow conditions and results of both methods were comparatively analyzed. For preoperative and postoperative distribution of hemodynamic parameters, CFD simulations and PC-MRI velocity measurements showed similar results. In both cases where no occlusion of the aneurysm was observed after six months, a flow reduction of about 30-50% was found, while in the clinically successful case with complete occlusion of the aneurysm after 6 months, the flow reduction was about 80%. No vortex was observed in any of the three models after treatment. The results are in agreement with recent studies suggesting that CFD simulations can predict post-treatment aneurysm flow alteration already before implantation of a FD and PC-MRI could validate the predicted hemodynamic changes right after implantation of a FD. PMID:29304062

  20. 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.

  1. 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...

  2. Safety of Simultaneous Scalp or Intracranial EEG during MRI: A Review

    Directory of Open Access Journals (Sweden)

    Hassan B. Hawsawi

    2017-10-01

    Full Text Available Understanding the brain and its activity is one of the great challenges of modern science. Normal brain activity (cognitive processes, etc. has been extensively studied using electroencephalography (EEG since the 1930's, in the form of spontaneous fluctuations in rhythms, and patterns, and in a more experimentally-driven approach in the form of event-related potentials (ERPs allowing us to relate scalp voltage waveforms to brain states and behavior. The use of EEG recorded during functional magnetic resonance imaging (EEG-fMRI is a more recent development that has become an important tool in clinical neuroscience, for example for the study of epileptic activity. The purpose of this review is to explore the magnetic resonance imaging safety aspects specifically associated with the use of scalp EEG and other brain-implanted electrodes such as intracranial EEG electrodes when they are subjected to the MRI environment. We provide a theoretical overview of the mechanisms at play specifically associated with the presence of EEG equipment connected to the subject in the MR environment, and of the resulting health hazards. This is followed by a survey of the literature on the safety of scalp or invasive EEG-fMRI data acquisitions across field strengths, with emphasis on the practical implications for the safe application of the techniques; in particular, we attempt to summarize the findings in terms of acquisition protocols when possible.

  3. 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)

  4. 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

  5. Cochlear Implant Outcomes and Genetic Mutations in Children with Ear and Brain Anomalies

    Directory of Open Access Journals (Sweden)

    Micol Busi

    2015-01-01

    Full Text Available Background. Specific clinical conditions could compromise cochlear implantation outcomes and drastically reduce the chance of an acceptable development of perceptual and linguistic capabilities. These conditions should certainly include the presence of inner ear malformations or brain abnormalities. The aims of this work were to study the diagnostic value of high resolution computed tomography (HRCT and magnetic resonance imaging (MRI in children with sensorineural hearing loss who were candidates for cochlear implants and to analyse the anatomic abnormalities of the ear and brain in patients who underwent cochlear implantation. We also analysed the effects of ear malformations and brain anomalies on the CI outcomes, speculating on their potential role in the management of language developmental disorders. Methods. The present study is a retrospective observational review of cochlear implant outcomes among hearing-impaired children who presented ear and/or brain anomalies at neuroimaging investigations with MRI and HRCT. Furthermore, genetic results from molecular genetic investigations (GJB2/GJB6 and, additionally, in selected cases, SLC26A4 or mitochondrial-DNA mutations on this study group were herein described. Longitudinal and cross-sectional analysis was conducted using statistical tests. Results. Between January 1, 1996 and April 1, 2012, at the ENT-Audiology Department of the University Hospital of Ferrara, 620 cochlear implantations were performed. There were 426 implanted children at the time of the present study (who were <18 years. Among these, 143 patients (64 females and 79 males presented ear and/or brain anomalies/lesions/malformations at neuroimaging investigations with MRI and HRCT. The age of the main study group (143 implanted children ranged from 9 months and 16 years (average = 4.4; median = 3.0. Conclusions. Good outcomes with cochlear implants are possible in patients who present with inner ear or brain abnormalities

  6. 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.

  7. Magnetic resonance imaging metallic artifact of commonly encountered surgical implants and foreign material.

    Science.gov (United States)

    Sutherland-Smith, James; Tilley, Brenda

    2012-01-01

    Magnetic resonance imaging (MRI) artifacts secondary to metallic implants and foreign bodies are well described. Herein, we provide quantitative data from veterinary implants including total hip arthroplasty implants, cranial cruciate repair implants, surgical screws, a skin staple, ligation clips, an identification microchip, ameroid constrictor, and potential foreign bodies including air gun and BB projectiles and a sewing needle. The objects were scanned in a gelatin phantom with plastic grid using standardized T2-weighted turbo-spin echo (TSE), T1-weighted spin echo, and T2*-weighted gradient recalled echo (GRE) image acquisitions at 1.5 T. Maximum linear dimensions and areas of signal voiding and grid distortion were calculated using a DICOM workstation for each sequence and object. Artifact severity was similar between the T2-weighted TSE and T1-weighted images, while the T2*-weighted images were most susceptible to artifact. Metal type influenced artifact size with the largest artifacts arising from steel objects followed by surgical stainless steel, titanium, and lead. For animals with metallic surgical implants or foreign bodies, the quantification of the artifact size will help guide clinicians on the viability of MRI. © 2012 Veterinary Radiology & Ultrasound.

  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. Maintained functionality of an implantable radiotelemetric blood pressure and heart rate sensor after magnetic resonance imaging in rats

    International Nuclear Information System (INIS)

    Nölte, I; Boll, H; Figueiredo, G; Groden, C; Brockmann, M A; Gorbey, S; Lemmer, B

    2011-01-01

    Radiotelemetric sensors for in vivo assessment of blood pressure and heart rate are widely used in animal research. MRI with implanted sensors is regarded as contraindicated as transmitter malfunction and injury of the animal may be caused. Moreover, artefacts are expected to compromise image evaluation. In vitro, the function of a radiotelemetric sensor (TA11PA-C10, Data Sciences International) after exposure to MRI up to 9.4 T was assessed. The magnetic force of the electromagnetic field on the sensor as well as radiofrequency (RF)-induced sensor heating was analysed. Finally, MRI with an implanted sensor was performed in a rat. Imaging artefacts were analysed at 3.0 and 9.4 T ex vivo and in vivo. Transmitted 24 h blood pressure and heart rate were compared before and after MRI to verify the integrity of the telemetric sensor. The function of the sensor was not altered by MRI up to 9.4 T. The maximum force exerted on the sensor was 273 ± 50 mN. RF-induced heating was ruled out. Artefacts impeded the assessment of the abdomen and thorax in a dead rat, but not of the head and neck. MRI with implanted radiotelemetric sensors is feasible in principal. The tested sensor maintains functionality up to 9.4 T. Artefacts hampered abdominal and throacic imaging in rats, while assessment of the head and neck is possible

  11. 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.

  12. 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.

  13. MR imaging of autologous chondrocyte implantation of the knee

    Energy Technology Data Exchange (ETDEWEB)

    James, S.L.J.; Connell, D.A.; Saifuddin, A.; Skinner, J.A.; Briggs, T.W.R. [RNOH Stanmore, Department of Radiology, Stanmore, Middlesex (United Kingdom)

    2006-05-15

    Autologous chondrocyte implantation (ACI) is a surgical technique that is increasingly being used in the treatment of full-thickness defects of articular cartilage in the knee. It involves the arthroscopic harvesting and in vitro culture of chondrocytes that are subsequently implanted into a previously identified chondral defect. The aim is to produce a repair tissue that closely resembles hyaline articular cartilage that gradually becomes incorporated, restoring joint congruity. Over the long term, it is hoped that this will prevent the progression of full-thickness articular cartilage defects to osteoarthritis. This article reviews the indications and operative procedure performed in ACI. Magnetic resonance imaging (MRI) sequences that provide optimal visualization of articular cartilage in the post-operative period are discussed. Normal appearances of ACI on MRI are presented along with common complications that are encountered with this technique. (orig.)

  14. 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.

  15. Magnetic resonance imaging at 1.5-T in patients with implantable cardioverter-defibrillators.

    Science.gov (United States)

    Naehle, Claas P; Strach, Katharina; Thomas, Daniel; Meyer, Carsten; Linhart, Markus; Bitaraf, Sascha; Litt, Harold; Schwab, Jörg Otto; Schild, Hans; Sommer, Torsten

    2009-08-04

    Our aim was to establish and evaluate a strategy for safe performance of magnetic resonance imaging (MRI) at 1.5-T in patients with implantable cardioverter-defibrillators (ICDs). Expanding indications for ICD placement and MRI becoming the imaging modality of choice for many indications has created a growing demand for MRI in ICD patients, which is still considered an absolute contraindication. Non-pacemaker-dependent ICD patients with a clinical need for MRI were included in the study. To minimize radiofrequency-related lead heating, the specific absorption rate was limited to 2 W/kg. ICDs were reprogrammed pre-MRI to avoid competitive pacing and potential pro-arrhythmia: 1) the lower rate limit was programmed as low as reasonably achievable; and 2) arrhythmia detection was programmed on, but therapy delivery was programmed off. Patients were monitored using electrocardiography and pulse oximetry. All ICDs were interrogated before and after the MRI examination and after 3 months, including measurement of pacing capture threshold, lead impedance, battery voltage, and serum troponin I. Eighteen ICD patients underwent a total of 18 MRI examinations at 1.5-T; all examinations were completed safely. All ICDs could be interrogated and reprogrammed normally post-MRI. No significant changes of pacing capture threshold, lead impedance, and serum troponin I were observed. Battery voltage decreased significantly from pre- to post-MRI. In 2 MRI examinations, oversensing of radiofrequency noise as ventricular fibrillation occurred. However, no attempt at therapy delivery was made. MRI of non-pacemaker-dependent ICD patients can be performed with an acceptable risk/benefit ratio under controlled conditions by taking both MRI- and pacemaker-related precautions. (Implantable Cardioverter Defibrillators and Magnetic Resonance Imaging of the Heart at 1.5-Tesla; NCT00356239).

  16. 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

  17. 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

  18. Breast augmentation and reconstructive surgery: MR imaging of implant rupture and malignancy

    Energy Technology Data Exchange (ETDEWEB)

    Herborn, Christoph U. [Institute of Diagnostic Radiology, University Hospital, Zuerich (Switzerland); Department of Diagnostic and Interventional Radiology, University Hospital Essen, Hufelandstrasse 55, 45128 Essen (Germany); Marincek, Borut; Erfmann, Daniel; Kubik-Huch, Rahel A. [Institute of Diagnostic Radiology, University Hospital, Zuerich (Switzerland); Meuli-Simmen, Claudia; Wedler, Volker [Department of Surgery, Clinic for Reconstructive Surgery, University Hospital, Zurich (Switzerland); Bode-Lesniewska, Beate [Department of Pathology, University Hospital, Zurich (Switzerland)

    2002-09-01

    The purpose of this study was to assess the diagnostic accuracy of MRI in detecting prosthesis integrity and malignancy after breast augmentation and reconstruction. Forty-one implants in 25 patients were analyzed by MRI before surgical removal. Imaging results were compared with ex vivo findings. Magnetic resonance imaging of the breast was performed on a 1.5-T system using a dedicated surface breast coil. Axial and sagittal T2-weighted fast spin-echo as well as dynamic contrast-enhanced T1-weighted gradient-recalled-echo sequences were acquired. The linguine sign indicating collapse of the silicone shell or siliconomas indicating free silicone proved implant rupture, whereas early focal contrast enhancement of a lesion was suspicious for malignancy. The sensitivity for detection of implant rupture was 86.7% with a specificity of 88.5%. The positive and negative predictive values were 81.3 and 92.0%, respectively. The linguine sign as a predictor of intracapsular implant rupture had a sensitivity of 80% with a specificity of 96.2%. Magnetic resonance imaging revealed two lesions with suspicious contrast enhancement (one carcinoma, one extra-abdominal fibromatosis). Magnetic resonance imaging is a reliable and reproducible technique for diagnosing both implant rupture and malignant lesions in women after breast augmentation and reconstruction. (orig.)

  19. Breast augmentation and reconstructive surgery: MR imaging of implant rupture and malignancy

    International Nuclear Information System (INIS)

    Herborn, Christoph U.; Marincek, Borut; Erfmann, Daniel; Kubik-Huch, Rahel A.; Meuli-Simmen, Claudia; Wedler, Volker; Bode-Lesniewska, Beate

    2002-01-01

    The purpose of this study was to assess the diagnostic accuracy of MRI in detecting prosthesis integrity and malignancy after breast augmentation and reconstruction. Forty-one implants in 25 patients were analyzed by MRI before surgical removal. Imaging results were compared with ex vivo findings. Magnetic resonance imaging of the breast was performed on a 1.5-T system using a dedicated surface breast coil. Axial and sagittal T2-weighted fast spin-echo as well as dynamic contrast-enhanced T1-weighted gradient-recalled-echo sequences were acquired. The linguine sign indicating collapse of the silicone shell or siliconomas indicating free silicone proved implant rupture, whereas early focal contrast enhancement of a lesion was suspicious for malignancy. The sensitivity for detection of implant rupture was 86.7% with a specificity of 88.5%. The positive and negative predictive values were 81.3 and 92.0%, respectively. The linguine sign as a predictor of intracapsular implant rupture had a sensitivity of 80% with a specificity of 96.2%. Magnetic resonance imaging revealed two lesions with suspicious contrast enhancement (one carcinoma, one extra-abdominal fibromatosis). Magnetic resonance imaging is a reliable and reproducible technique for diagnosing both implant rupture and malignant lesions in women after breast augmentation and reconstruction. (orig.)

  20. Breast augmentation and reconstructive surgery: MR imaging of implant rupture and malignancy.

    Science.gov (United States)

    Herborn, Christoph U; Marincek, Borut; Erfmann, Daniel; Meuli-Simmen, Claudia; Wedler, Volker; Bode-Lesniewska, Beate; Kubik-Huch, Rahel A

    2002-09-01

    The purpose of this study was to assess the diagnostic accuracy of MRI in detecting prosthesis integrity and malignancy after breast augmentation and reconstruction. Forty-one implants in 25 patients were analyzed by MRI before surgical removal. Imaging results were compared with ex vivo findings. Magnetic resonance imaging of the breast was performed on a 1.5-T system using a dedicated surface breast coil. Axial and sagittal T2-weighted fast spin-echo as well as dynamic contrast-enhanced T1-weighted gradient-recalled-echo sequences were acquired. The linguine sign indicating collapse of the silicone shell or siliconomas indicating free silicone proved implant rupture, whereas early focal contrast enhancement of a lesion was suspicious for malignancy. The sensitivity for detection of implant rupture was 86.7% with a specificity of 88.5%. The positive and negative predictive values were 81.3 and 92.0%, respectively. The linguine sign as a predictor of intracapsular implant rupture had a sensitivity of 80% with a specificity of 96.2%. Magnetic resonance imaging revealed two lesions with suspicious contrast enhancement (one carcinoma, one extra-abdominal fibromatosis). Magnetic resonance imaging is a reliable and reproducible technique for diagnosing both implant rupture and malignant lesions in women after breast augmentation and reconstruction.

  1. 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

  2. Mapping effective connectivity in the human brain with concurrent intracranial electrical stimulation and BOLD-fMRI.

    Science.gov (United States)

    Oya, Hiroyuki; Howard, Matthew A; Magnotta, Vincent A; Kruger, Anton; Griffiths, Timothy D; Lemieux, Louis; Carmichael, David W; Petkov, Christopher I; Kawasaki, Hiroto; Kovach, Christopher K; Sutterer, Matthew J; Adolphs, Ralph

    2017-02-01

    Understanding brain function requires knowledge of how one brain region causally influences another. This information is difficult to obtain directly in the human brain, and is instead typically inferred from resting-state fMRI. Here, we demonstrate the safety and scientific promise of a novel and complementary approach: concurrent electrical stimulation and fMRI (es-fMRI) at 3T in awake neurosurgical patients with implanted depth electrodes. We document the results of safety testing, actual experimental setup, and stimulation parameters, that safely and reliably evoke activation in distal structures through stimulation of amygdala, cingulate, or prefrontal cortex. We compare connectivity inferred from the evoked patterns of activation with that estimated from standard resting-state fMRI in the same patients: while connectivity patterns obtained with each approach are correlated, each method produces unique results. Response patterns were stable over the course of 11min of es-fMRI runs. COMPARISON WITH EXISTING METHOD: es-fMRI in awake humans yields unique information about effective connectivity, complementing resting-state fMRI. Although our stimulations were below the level of inducing any apparent behavioral or perceptual effects, a next step would be to use es-fMRI to modulate task performances. This would reveal the acute network-level changes induced by the stimulation that mediate the behavioral and cognitive effects seen with brain stimulation. es-fMRI provides a novel and safe approach for mapping effective connectivity in the human brain in a clinical setting, and will inform treatments for psychiatric and neurodegenerative disorders that use deep brain stimulation. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. A novel aragonite-based scaffold for osteochondral regeneration: early experience on human implants and technical developments.

    Science.gov (United States)

    Kon, Elizaveta; Robinson, Dror; Verdonk, Peter; Drobnic, Matej; Patrascu, Jenel Mariano; Dulic, Oliver; Gavrilovic, Gordon; Filardo, Giuseppe

    2016-12-01

    Chondral and osteochondral lesions represent a debilitating disease. Untreated lesions remain a risk factor for more extensive joint damage. The objective of this clinical study is to evaluate safety and early results of an aragonite-based scaffold used for osteochondral unit repair, by analysing both clinical outcome and MRI results, as well as the benefits of the procedure optimization through novel tapered shaped implants. A crystalline aragonite bi-phasic scaffold was implanted in patients affected by focal chondral-osteochondral knee lesions of the condyle and trochlea. Twenty-one patients (17 men, 4 women with a mean age of 31.0 ± 8.6 years) without severe OA received tapered shaped implants for the treatment of 2.5 ±1.7 cm 2 sized defects. The control group consisted of 76 patients selected according to the same criteria from a database of patients who previously underwent implantation of cylindrical-shaped implants. The clinical outcome of all patients was evaluated with the IKDC subjective score, the Lysholm score, and all 5 KOOS subscales administered preoperatively and at 6 and 12 months after surgery, while MRI evaluation was performed at the 12 month follow-up. A statistically significant improvement in all clinical scores was documented both in the tapered implants and the cylindrical group. No difference could be detected in the comparison between the improvement obtained with the two implant types, neither in the clinical nor in imaging evaluations. A difference could be detected instead in terms of revision rate, which was lower in the tapered implant group with no implant removal - 0% vs 8/76-10.5% failures in the cylindrical implants. This study highlighted both safety and potential of a novel aragonite-based scaffold for the treatment of chondral and osteochondral lesions in humans. A tapered shape relative to the cylindrical shaped implant design, improved the scaffold's safety profile. Tapered scaffolds maintain the clinical improvement

  4. 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.

  5. 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)

  6. Sub-meninges implantation reduces immune response to neural implants.

    Science.gov (United States)

    Markwardt, Neil T; Stokol, Jodi; Rennaker, Robert L

    2013-04-15

    Glial scar formation around neural interfaces inhibits their ability to acquire usable signals from the surrounding neurons. To improve neural recording performance, the inflammatory response and glial scarring must be minimized. Previous work has indicated that meningeally derived cells participate in the immune response, and it is possible that the meninges may grow down around the shank of a neural implant, contributing to the formation of the glial scar. This study examines whether the glial scar can be reduced by placing a neural probe completely below the meninges. Rats were implanted with sets of loose microwire implants placed either completely below the meninges or implanted conventionally with the upper end penetrating the meninges, but not attached to the skull. Histological analysis was performed 4 weeks following surgical implantation to evaluate the glial scar. Our results found that sub-meninges implants showed an average reduction in reactive astrocyte activity of 63% compared to trans-meninges implants. Microglial activity was also reduced for sub-meninges implants. These results suggest that techniques that isolate implants from the meninges offer the potential to reduce the encapsulation response which should improve chronic recording quality and stability. Published by Elsevier B.V.

  7. Use of (N-1)-D expansions for N-D phase unwrapping in MRI

    Science.gov (United States)

    Bones, Philip J.; King, Laura J.; Millane, Rick P.

    2017-09-01

    In MRI the presence of metal implants causes severe artifacts in images and interferes with the usual techniques used to separate fat signals from other tissues. In the Dixon method, three images are acquired at different echo times to enable the variation in the magnetic field to be estimated. However, the estimate is represented as the phase of a complex quantity and therefore suffers from wrapping. High field gradients near the metal mean that the phase estimate is undersampled and therefore challenging to unwrap. We have developed POP, phase estimation by onion peeling, an algorithm which unwraps the phase along 1-D paths for a 2-D image obtained with the Dixon method. The unwrapping is initially performed along a closed path enclosing the implant and well separated from it. The recovered phase is expanded using a smooth periodic basis along the path. Then, path-by-path, the estimate is applied to the next path and then the expansion coefficients are estimated to best fit the wrapped measurements. We have successfully tested POP on MRI images of specially constructed phantoms and on a group of patients with hip implants. In principle, POP can be extended to 3-D imaging. In that case, POP would entail representing phase with a suitably smooth basis over a series of surfaces enclosing the implant (the "onion skins"), again beginning the phase estimation well away from the implant. An approach for this is proposed. Results are presented for fat and water separation for 2-D images of phantoms and actual patients. The practicality of the method and its employment in clinical MRI are discussed.

  8. 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

  9. 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.

  10. Assessment of the coronary venous system in heart failure patients by blood pool agent enhanced whole-heart MRI

    Energy Technology Data Exchange (ETDEWEB)

    Manzke, Robert [University Hospital of Ulm, Department of Internal Medicine II, Ulm (Germany); Philips Research Europe, Clinical Sites Research, Hamburg (Germany); Binner, Ludwig; Bornstedt, Axel; Merkle, Nico; Lutz, Anja; Gradinger, Robert [University Hospital of Ulm, Department of Internal Medicine II, Ulm (Germany); Rasche, Volker [University Hospital of Ulm, Department of Internal Medicine II, Ulm (Germany); Experimental Cardiovascular Imaging, Internal Medicine II, Ulm (Germany)

    2011-04-15

    To investigate the feasibility of MRI for non-invasive assessment of the coronary sinus (CS) and the number and course of its major tributaries in heart failure patients. Fourteen non-ischaemic heart failure patients scheduled for cardiac resynchronisation therapy (CRT) underwent additional whole-heart coronary venography. MRI was performed 1 day before device implantation. The visibility, location and dimensions of the CS and its major tributaries were assessed and the number of potential implantation sites identified. The MRI results were validated by X-ray venography conventionally acquired during the device implantation procedure. The right atrium (RA), CS and mid-cardiac vein (MCV) could be visualised in all patients. 36% of the identified candidate branches were located posterolaterally, 48% laterally and 16% anterolaterally. The average diameter of the CS was quantified as 9.8 mm, the posterior interventricular vein (PIV) 4.6 mm, posterolateral segments 3.3 mm, lateral 2.9 mm and anterolateral 2.9 mm. Concordance with X-ray in terms of number and location of candidate branches was given in most cases. Contrast-enhanced MRI venography appears feasible for non-invasive pre-interventional assessment of the course of the CS and its major tributaries. (orig.)

  11. Assessment of the coronary venous system in heart failure patients by blood pool agent enhanced whole-heart MRI

    International Nuclear Information System (INIS)

    Manzke, Robert; Binner, Ludwig; Bornstedt, Axel; Merkle, Nico; Lutz, Anja; Gradinger, Robert; Rasche, Volker

    2011-01-01

    To investigate the feasibility of MRI for non-invasive assessment of the coronary sinus (CS) and the number and course of its major tributaries in heart failure patients. Fourteen non-ischaemic heart failure patients scheduled for cardiac resynchronisation therapy (CRT) underwent additional whole-heart coronary venography. MRI was performed 1 day before device implantation. The visibility, location and dimensions of the CS and its major tributaries were assessed and the number of potential implantation sites identified. The MRI results were validated by X-ray venography conventionally acquired during the device implantation procedure. The right atrium (RA), CS and mid-cardiac vein (MCV) could be visualised in all patients. 36% of the identified candidate branches were located posterolaterally, 48% laterally and 16% anterolaterally. The average diameter of the CS was quantified as 9.8 mm, the posterior interventricular vein (PIV) 4.6 mm, posterolateral segments 3.3 mm, lateral 2.9 mm and anterolateral 2.9 mm. Concordance with X-ray in terms of number and location of candidate branches was given in most cases. Contrast-enhanced MRI venography appears feasible for non-invasive pre-interventional assessment of the course of the CS and its major tributaries. (orig.)

  12. The diagnosis of silicone breast-implant rupture: clinical findings compared with findings at magnetic resonance imaging

    DEFF Research Database (Denmark)

    Hölmich, Lisbet Rosenkrantz; Fryzek, Jon P; Kjøller, Kim

    2005-01-01

    The objective was to evaluate the usefulness of clinical examination in the evaluation of breast-implant integrity, using the diagnosis at magnetic resonance imaging (MRI) as the "gold standard." Fifty-five women with 109 implants underwent a breast examination either just before or shortly after...

  13. 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

  14. 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

  15. Ex-PRESS glaucoma filter: an MRI compatible metallic orbital foreign body imaged at 1.5 and 3T.

    Science.gov (United States)

    Mabray, M C; Uzelac, A; Talbott, J F; Lin, S C; Gean, A D

    2015-05-01

    To report on the MRI compatibility of the Ex-PRESS glaucoma filtration device, a tiny metallic implant placed into the anterior chamber of the eye that is much smaller than traditional glaucoma shunts, and to educate the radiology community regarding its appearance. Seven patients with Ex-PRESS glaucoma filtration devices were identified that had undergone MRI at San Francisco General Hospital/University of California San Francisco Medical Center by searching and cross-referencing the radiology reporting system and the electronic medical record. MRI images were reviewed for artefact interfering with interpretation. Ophthalmology examinations were reviewed for evidence of complications. Eighteen individual MRI examinations were performed during 12 unique MRI events on these 7 patients. 13/18 individual MRI examinations and 7/12 MRI events were performed at 3 T with the others performed at 1.5 T. Mean time from Ex-PRESS implantation to MRI was 17.5 months. Mean time from MRI to first ophthalmology examination was 1.1 months and from MRI to latest ophthalmology examination was 6.6 months. Susceptibility artefact did not interfere with image interpretation and no complications related to MRI were encountered. The Ex-PRESS glaucoma filtration device appears to be safe for MRI at 1.5 and 3 T and does not produce significant susceptibility artefact to affect diagnostic interpretation adversely. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  16. Assessing the Risks Associated with MRI in Patients with a Pacemaker or Defibrillator.

    Science.gov (United States)

    Russo, Robert J; Costa, Heather S; Silva, Patricia D; Anderson, Jeffrey L; Arshad, Aysha; Biederman, Robert W W; Boyle, Noel G; Frabizzio, Jennifer V; Birgersdotter-Green, Ulrika; Higgins, Steven L; Lampert, Rachel; Machado, Christian E; Martin, Edward T; Rivard, Andrew L; Rubenstein, Jason C; Schaerf, Raymond H M; Schwartz, Jennifer D; Shah, Dipan J; Tomassoni, Gery F; Tominaga, Gail T; Tonkin, Allison E; Uretsky, Seth; Wolff, Steven D

    2017-02-23

    The presence of a cardiovascular implantable electronic device has long been a contraindication for the performance of magnetic resonance imaging (MRI). We established a prospective registry to determine the risks associated with MRI at a magnetic field strength of 1.5 tesla for patients who had a pacemaker or implantable cardioverter-defibrillator (ICD) that was "non-MRI-conditional" (i.e., not approved by the Food and Drug Administration for MRI scanning). Patients in the registry were referred for clinically indicated nonthoracic MRI at a field strength of 1.5 tesla. Devices were interrogated before and after MRI with the use of a standardized protocol and were appropriately reprogrammed before the scanning. The primary end points were death, generator or lead failure, induced arrhythmia, loss of capture, or electrical reset during the scanning. The secondary end points were changes in device settings. MRI was performed in 1000 cases in which patients had a pacemaker and in 500 cases in which patients had an ICD. No deaths, lead failures, losses of capture, or ventricular arrhythmias occurred during MRI. One ICD generator could not be interrogated after MRI and required immediate replacement; the device had not been appropriately programmed per protocol before the MRI. We observed six cases of self-terminating atrial fibrillation or flutter and six cases of partial electrical reset. Changes in lead impedance, pacing threshold, battery voltage, and P-wave and R-wave amplitude exceeded prespecified thresholds in a small number of cases. Repeat MRI was not associated with an increase in adverse events. In this study, device or lead failure did not occur in any patient with a non-MRI-conditional pacemaker or ICD who underwent clinically indicated nonthoracic MRI at 1.5 tesla, was appropriately screened, and had the device reprogrammed in accordance with the prespecified protocol. (Funded by St. Jude Medical and others; MagnaSafe ClinicalTrials.gov number, NCT

  17. MRI-Based Nonrigid Motion Correction in Simultaneous PET/MRI

    Science.gov (United States)

    Chun, Se Young; Reese, Timothy G.; Ouyang, Jinsong; Guerin, Bastien; Catana, Ciprian; Zhu, Xuping; Alpert, Nathaniel M.; El Fakhri, Georges

    2014-01-01

    Respiratory and cardiac motion is the most serious limitation to whole-body PET, resulting in spatial resolution close to 1 cm. Furthermore, motion-induced inconsistencies in the attenuation measurements often lead to significant artifacts in the reconstructed images. Gating can remove motion artifacts at the cost of increased noise. This paper presents an approach to respiratory motion correction using simultaneous PET/MRI to demonstrate initial results in phantoms, rabbits, and nonhuman primates and discusses the prospects for clinical application. Methods Studies with a deformable phantom, a free-breathing primate, and rabbits implanted with radioactive beads were performed with simultaneous PET/MRI. Motion fields were estimated from concurrently acquired tagged MR images using 2 B-spline nonrigid image registration methods and incorporated into a PET list-mode ordered-subsets expectation maximization algorithm. Using the measured motion fields to transform both the emission data and the attenuation data, we could use all the coincidence data to reconstruct any phase of the respiratory cycle. We compared the resulting SNR and the channelized Hotelling observer (CHO) detection signal-to-noise ratio (SNR) in the motion-corrected reconstruction with the results obtained from standard gating and uncorrected studies. Results Motion correction virtually eliminated motion blur without reducing SNR, yielding images with SNR comparable to those obtained by gating with 5–8 times longer acquisitions in all studies. The CHO study in dynamic phantoms demonstrated a significant improvement (166%–276%) in lesion detection SNR with MRI-based motion correction as compared with gating (P < 0.001). This improvement was 43%–92% for large motion compared with lesion detection without motion correction (P < 0.001). CHO SNR in the rabbit studies confirmed these results. Conclusion Tagged MRI motion correction in simultaneous PET/MRI significantly improves lesion detection

  18. Assessment of cartilage repair after chondrocyte transplantation with a fibrin-hyaluronan matrix – Correlation of morphological MRI, biochemical T2 mapping and clinical outcome

    International Nuclear Information System (INIS)

    Eshed, Iris; Trattnig, Siegfried; Sharon, Michal; Arbel, Ron; Nierenberg, Gabriel; Konen, Eli; Yayon, Avner

    2012-01-01

    Objective: To evaluate change over time of clinical scores, morphological MRI of cartilage appearance and quantitative T2 values after implantation with BioCart™II, a second generation matrix-assisted implantation system. Methods: Thirty-one patients were recruited 6–49 months post surgery for cartilage defect in the femoral condyle. Subjects underwent MRI (morphological and T2-mapping sequences) and completed the International Knee Documentation Committee (IKDC) questionnaire. MRI scans were scored using the MR Observation of Cartilage Repair Tissue (MOCART) system and cartilage T2-mapping values were registered. Analysis included correlation of IKDC scores, MOCART and T2 evaluation with each other, with implant age and with previous surgical intervention history. Results: IKDC score significantly correlated with MOCART score (r = −0.39, p = 0.031), inversely correlated with previous interventions (r = −0.39, p = 0.034) and was significantly higher in patients with longer follow-up time (p = 0.0028). MOCART score was slight, but not significantly higher in patients with longer term implants (p = 0.199). T2 values were significantly lower in patients with longer duration implants (p < 0.001). This trend was repeated in patients with previous interventions, although to a lesser extent. Conclusions: Significant improvement with time from BioCart™II implantation can be expected by IKDC scoring and MRI T2-mapping values. Patients with previous knee operations can also benefit from this procedure.

  19. 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

  20. 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)

  1. 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)

  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. 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.

  4. 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.

  5. Implantable devices in the electromagnetic environment

    Directory of Open Access Journals (Sweden)

    Luca Santini

    2013-12-01

    Full Text Available In the last few years we are witnessing a dramatic increase in the number of CIEDs implanted. At the same time new emitters are constantly entering the marketplace and more and more medical procedures are based on electromagnetic fields as well. Therefore, the topic of the interaction of CIEDs with the EMI is a real, actual and challenging one. In the non-medical environment several types of devices may be intentional or non-intentional sources of EMI. Most of the studies reported in literature focused on mobile phones, metal detectors, as well as on headphones or digital players, but many other instruments and tools may generate electromagnetic fields. In the medical environment most of the attention is paid to MRI and recently new PM and MRI conditional ICDs have been developed and launched in the market, but the risk of interaction is present also with ionizing radiation, electrical nerve stimulation and electrosurgery. Pacemaker/ICD manufacturers are incorporating state of the art technology to make implantable devices less susceptible to EMI. However, patients and emitter manufacturers should be aware that limitations exist and that there is not complete immunity to EMI.

  6. In vitro assessment of MRI issues at 3-Tesla for a breast tissue expander with a remote port.

    Science.gov (United States)

    Linnemeyer, Hannah; Shellock, Frank G; Ahn, Christina Y

    2014-04-01

    A patient with a breast tissue expander may require a diagnostic assessment using magnetic resonance imaging (MRI). To ensure patient safety, this type of implant must undergo in vitro MRI testing using proper techniques. Therefore, this investigation evaluated MRI issues (i.e., magnetic field interactions, heating, and artifacts) at 3-Tesla for a breast tissue expander with a remote port. A breast tissue expander with a remote port (Integra Breast Tissue Expander, Model 3612-06 with Standard Remote Port, PMT Corporation, Chanhassen, MN) underwent evaluation for magnetic field interactions (translational attraction and torque), MRI-related heating, and artifacts using standardized techniques. Heating was evaluated by placing the implant in a gelled-saline-filled phantom and MRI was performed using a transmit/receive RF body coil at an MR system reported, whole body averaged specific absorption rate of 2.9-W/kg. Artifacts were characterized using T1-weighted and GRE pulse sequences. Magnetic field interactions were not substantial and, thus, will not pose a hazard to a patient in a 3-Tesla or less MRI environment. The highest temperature rise was 1.7°C, which is physiologically inconsequential. Artifacts were large in relation to the remote port and metal connector of the implant but will only present problems if the MR imaging area of interest is where these components are located. A patient with this breast tissue expander with a remote port may safely undergo MRI at 3-Tesla or less under the conditions used for this investigation. These findings are the first reported at 3-Tesla for a tissue expander. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. 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 ...

  8. 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

  9. 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.

  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. PMID:26106257

  11. WE-B-BRD-00: MRI for Radiation Oncology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2015-06-15

    The use of MRI in radiation therapy is rapidly increasing. Applications vary from the MRI simulator, to the MRI fused with CT, and to the integrated MRI+RT system. Compared with the standard MRI QA, a broader scope of QA features has to be defined in order to maximize the benefits of using MRI in radiation therapy. These QA features include geometric fidelity, image registration, motion management, cross-system alignment, and hardware interference. Advanced MRI techniques require a specific type of QA, as they are being widely used in radiation therapy planning, dose calculations, post-implant dosimetry, and prognoses. A vigorous and adaptive QA program is crucial to defining the responsibility of the entire radiation therapy group and detecting deviations from the performance of high-quality treatment. As a drastic departure from CT simulation, MRI simulation requires changes in the work flow of treatment planning and image guidance. MRI guided radiotherapy platforms are being developed and commercialized to take the advantage of the advance in knowledge, technology and clinical experience. This symposium will from an educational perspective discuss the scope and specific issues related to MRI guided radiotherapy. Learning Objectives: Understand the difference between a standard and a radiotherapy-specific MRI QA program. Understand the effects of MRI artifacts (geometric distortion and motion) on radiotherapy. Understand advanced MRI techniques (ultrashort echo, fast MRI including dynamic MRI and 4DMRI, diffusion, perfusion, and MRS) and related QA. Understand the methods to prepare MRI for treatment planning (electron density assignment, multimodality image registration, segmentation and motion management). Current status of MRI guided treatment platforms. Dr. Jihong Wang has a research grant with Elekta-MRL project. Dr. Ke Sheng receives research grants from Varian Medical systems.

  12. 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...

  13. 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.

  14. Electromagnetic Interference in Implantable Rhythm Devices - The Indian Scenario

    Directory of Open Access Journals (Sweden)

    Johnson Francis

    2002-07-01

    Full Text Available Implantable rhythm device (IRD is the generic name for the group of implantable devices used for diagnosis and treatment of cardiac arrhythmias. Devices in this category include cardiac pacemakers, implantable cardioverter defibrillators and implantable loop recorders. Since these devices have complex microelectronic circuitry and use electromagnetic waves for communication, they are susceptible to interference from extraneous sources of electromagnetic radiation and magnetic energy. Electromagnetic interference (EMI is generally not a major problem outside of the hospital environment. The most important interactions occur when a patient is subjected to medical procedures such as magnetic resonance imaging (MRI, electrocautery and radiation therapy. Two articles in this issue of the journal discusses various aspects of EMI on IRD1,2 . Together these articles provide a good review of the various sources of EMI and their interaction with IRD for the treating physician.

  15. 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.

  16. MRI in patients with pacemakers? First global consensus recommendations from radiologists and cardiologists; Mit Schrittmacher ins MRT? Weltweit erste konsentierte Handlungsempfehlung von Radiologen und Kardiologen

    Energy Technology Data Exchange (ETDEWEB)

    Heindel, Walter; Kugel, Harald [University Hospital Muenster (Germany). Dept. of Clinical Radiology

    2017-03-15

    Under the title ''MR Imaging in Patients with Cardiac Pacemakers and Implantable Cardioverter Defibrillators'', this issue of Roefo - simultaneously with the journal of the German Cardiac Society ''Der Kardiologe'' - presents a consensus paper of the German Roentgen Society and the German Cardiac Society [1] [2] that was jointly written by the authors in radiology and cardiology but does not exclusively address cardiac MRI. This publication relates to MR imaging of all regions of the body. In Germany and internationally the number of MRI examinations is increasing: 1,008,944 examinations were performed on patients receiving inpatient treatment in 2005 while 1,767,005 examinations were performed in 2013 (DRG hospitals). This development can be attributed to our aging population as well as to new indications for MRI including: Analyses of tissue composition and function, for example in the liver [3] [4] and the heart [5] [6]; multiparametric analyses of MR perfusion, e.g. in treated brain tumors [7]; new organs such as the lung [8]; dedicated examinations for intervention planning and operation monitoring [9] [10] [11]; as well as MRI-guided interventions [12] [13] [14] [15] [16]. Implants must always be considered in all of these MRI examinations even if the reason for the examination request is not related to an implant. The involvement of cardiology in this case is not based on the medical issue but rather on the type of implant. Expertise in cardiology is required when dealing with cardiac pacemakers (PM) and implantable cardioverter defibrillators (ICD).

  17. 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%.

  18. 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.

  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. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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

  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. Rehabilitation of deaf persons with cochlear implants

    International Nuclear Information System (INIS)

    Gstoettner, W.; Hamzavi, J.; Czerny, C.

    1997-01-01

    In the last decade, the rehabilitation of postlingually deaf adults and prelingually deaf children with cochlear implants has been established as a treatment of deafness. The technological development of the implant devices and improvement of the surgical technique have led to a considerable increase of hearing performance during the last years. The postlingually deaf adults are able to use the telephone and may be integrated in their original job. Prelingually deaf children can even visit normal schools after cochlear implantation and hearing rehabilitation training. In order to preoperatively establish the state of the cochlear, radiological diagnosis of the temporal bone is necessary. High resolution computerized tomography imaging of the temporal bone with coronar and axial 1 mm slices and MRI with thin slice technique (three dimensional, T2 weighted turbo-spinecho sequence with 0.7 mm slices) have proved to be valuable according to our experience. Furthermore a postoperative synoptical X-ray, in a modified Chausse III projection, offers good information about the position of the implant and insertion of the stimulating electrode into the cochlea. (orig.) [de

  7. The effect of authentic metallic implants on the SAR distribution of the head exposed to 900, 1800 and 2450 MHz dipole near field.

    Science.gov (United States)

    Virtanen, H; Keshvari, J; Lappalainen, R

    2007-03-07

    As the use of radiofrequency (RF) electromagnetic (EM) fields has increased along with increased use of wireless communication, the possible related health risks have also been widely discussed. One safety aspect is the interaction of medical implants and RF devices like mobile phones. In the literature, effects on active implants like pacemakers have been discussed but the studies of passive metallic (i.e. conductive) implants are rare. However, some studies have shown that the EM power absorption in tissues may be enhanced due to metallic implants. In this study, the effect of authentic passive metallic implants in the head region was examined. A half-wave dipole antenna was used as an exposure source and the specific absorption rate (SAR, W kg(-1)) in the near field was studied numerically. The idea was to model the presumably worst cases of most common implants in an accurate MRI-based phantom. As exposure frequencies GSM (900 and 1800 MHz) and UMTS (2450 MHz) regions were considered. The implants studied were skull plates, fixtures, bone plates and ear rings. The results indicate that some of the implants, under very rare exposure conditions, may cause a notable enhancement in peak mass averaged SAR.

  8. 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)

  9. 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

  10. Definitive diagnosis of breast implant rupture using magnetic resonance imaging.

    Science.gov (United States)

    Ahn, C Y; Shaw, W W; Narayanan, K; Gorczyca, D P; Sinha, S; Debruhl, N D; Bassett, L W

    1993-09-01

    Breast implant rupture is an important complication of augmented and reconstructed breasts. Although several techniques such as mammography, xeromammography, ultrasound, thermography, and computed tomographic (CT) scanning have been proven to be useful to detect implant rupture, they have several disadvantages and lack specificity. In the current study, we have established magnetic resonance imaging (MRI) as a definitive, reliable, and reproducible technique to diagnose both intracapsular and extracapsular ruptures. The study was conducted in 100 symptomatic patients. Our imaging parameters were able to identify ruptures in implants with silicone shells. All the ruptures showed the presence of wavy lines, free-floating silicone shell within the gel ("free-floating loose-thread sign" or "linguine sign"). We had a 3.75 percent incidence of false-positive and false-negative results. The sensitivity for detection of silicone implant rupture was 76 percent, with a specificity of 97 percent. In addition, we also were able to identify the artifacts that may interfere with the definitive diagnosis of implant rupture.

  11. Treatment of Neuropathic Pain and Functional Limitations Associated With Multiple Sclerosis Using an MRI-Compatible Spinal Cord Stimulator: A Case Report With Two Year Follow-Up and Literature Review.

    Science.gov (United States)

    Provenzano, David A; Williams, Joseph R; Jarzabek, Gaye; DeRiggi, Leonard A; Scott, Thomas F

    2016-06-01

    To report a case with two years follow-up of neuropathic pain and functional limitations associated with multiple sclerosis (MS) effectively treated with an MRI conditional spinal cord stimulator (SCS) system that allowed for spinal imaging. To present a comprehensive literature review of spinal cord stimulator utilization in the treatment of multiple sclerosis. Case report and literature review. Treatment was a spinal cord stimulation implant after successful trial. Pain scores, medication utilization, and functional outcomes were reviewed. Pre- and post-SCS implant MRI spine images were obtained. At 24 months follow-up, the patient has had a 77% reduction in pain and a 99% reduction in opioid use. Furthermore, he had improvement in reported tactile sensation, spasticity levels, and ambulation. Post-SCS implant, MRI images at 18 months follow-up provided the ability to review the spinal cord with minimal artifact. No new MS documented plaques occurred during this time period. A literature review demonstrated 33 published reports including a total of 496 trialed and 744 implanted patients. Only 3 of the reports occurred after the year 2000. We report the successful treatment of MS-associated pain and functional limitations with an MRI conditional spinal cord stimulator system. The ability to obtain post-implant MRI imaging of not only the brain but also the spinal cord in MS patients allows for the continued need to document and follow disease progression, especially with the advancements in pharmacological therapy. © 2016 International Neuromodulation Society.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.)

  17. 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.)

  18. Recall management of patients with Rofil Medical breast implants.

    Science.gov (United States)

    Schott, Sarah; Bruckner, Thomas; Golatta, Michael; Wallwiener, Markus; Küffner, Livia; Mayer, Christine; Paringer, Carmen; Domschke, Christoph; Blumenstein, Maria; Schütz, Florian; Sohn, Christof; Heil, Joerg

    2014-07-01

    Some Rofil Medical breast implants are relabelled Poly Implant Prothèse (PIP) implants, and it is recommended that Rofil implants be managed in the same way as PIP implants. We report the results of a systematic recall of patients who had received Rofil implants. All patients who received Rofil implants at our centre were identified and invited for specialist consultation. In patients who opted for explantation, preoperative and intraoperative work-up was performed in accordance with national guidelines and analysed. In cases suspicious for rupture, an MRI scan was performed. Two-hundred and twenty-five patients (average age 56; range 28-80) received a total of 321 Rofil implants an average of 5.8 (range 1-11) years previously, 225/321 (70%) implants were used for reconstruction after breast cancer. A total of 43 implants were removed prior to 2011, mainly due to capsular contracture (CC). A total of 188 patients were still affected at the time of recall. Of the 188 patients, 115 (61%) attended for specialist consultation, of which 50 (44%) requested immediate implant removal. To date, 72 of 115 (63%) women attending consultation (38% of all affected) have chosen explantation, 66 of 72 (92%) opting for new implants. Of the 108 explanted implants, 25 (23%) had capsular rupture and 57 (53%) had implant bleeding. Preoperative clinical assessment was unreliable for predicting CC or rupture. The majority of patients attended for consultation and requested explantation. The quality of the explanted Rofil implants was comparable to PIP implants, with a higher rupture prevalence compared with other, non-affected implants. Nevertheless, the acceptance of breast implants for reimplantation remained high. Copyright © 2014 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  19. 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.

  20. 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.

  1. 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.)

  2. MO-B-BRC-04: MRI-Based Prostate HDR

    International Nuclear Information System (INIS)

    Mourtada, F.

    2016-01-01

    Brachytherapy has proven to be an effective treatment option for prostate cancer. Initially, prostate brachytherapy was delivered through permanently implanted low dose rate (LDR) radioactive sources; however, high dose rate (HDR) temporary brachytherapy for prostate cancer is gaining popularity. Needle insertion during prostate brachytherapy is most commonly performed under ultrasound (U/S) guidance; however, treatment planning may be performed utilizing several imaging modalities either in an intra- or post-operative setting. During intra-operative prostate HDR, the needles are imaged during implantation, and planning may be performed in real time. At present, the most common imaging modality utilized for intra-operative prostate HDR is U/S. Alternatively, in the post-operative setting, following needle implantation, patients may be simulated with computed tomography (CT) or magnetic resonance imaging (MRI). Each imaging modality and workflow provides its share of benefits and limitations. Prostate HDR has been adopted in a number of cancer centers across the nation. In this educational session, we will explore the role of U/S, CT, and MRI in HDR prostate brachytherapy. Example workflows and operational details will be shared, and we will discuss how to establish a prostate HDR program in a clinical setting. Learning Objectives: Review prostate HDR techniques based on the imaging modality Discuss the challenges and pitfalls introduced by the three imagebased options for prostate HDR brachytherapy Review the QA process and learn about the development of clinical workflows for these imaging options at different institutions

  3. MO-B-BRC-04: MRI-Based Prostate HDR

    Energy Technology Data Exchange (ETDEWEB)

    Mourtada, F. [Christiana Care Hospital (United States)

    2016-06-15

    Brachytherapy has proven to be an effective treatment option for prostate cancer. Initially, prostate brachytherapy was delivered through permanently implanted low dose rate (LDR) radioactive sources; however, high dose rate (HDR) temporary brachytherapy for prostate cancer is gaining popularity. Needle insertion during prostate brachytherapy is most commonly performed under ultrasound (U/S) guidance; however, treatment planning may be performed utilizing several imaging modalities either in an intra- or post-operative setting. During intra-operative prostate HDR, the needles are imaged during implantation, and planning may be performed in real time. At present, the most common imaging modality utilized for intra-operative prostate HDR is U/S. Alternatively, in the post-operative setting, following needle implantation, patients may be simulated with computed tomography (CT) or magnetic resonance imaging (MRI). Each imaging modality and workflow provides its share of benefits and limitations. Prostate HDR has been adopted in a number of cancer centers across the nation. In this educational session, we will explore the role of U/S, CT, and MRI in HDR prostate brachytherapy. Example workflows and operational details will be shared, and we will discuss how to establish a prostate HDR program in a clinical setting. Learning Objectives: Review prostate HDR techniques based on the imaging modality Discuss the challenges and pitfalls introduced by the three imagebased options for prostate HDR brachytherapy Review the QA process and learn about the development of clinical workflows for these imaging options at different institutions.

  4. A Randomized Seven-Year Study on Performance of the Stemmed Metal M2a-Magnum and Ceramic C2a-Taper, and the Resurfacing ReCap Hip Implants

    DEFF Research Database (Denmark)

    Borgwardt, Arne; Borgwardt, Lotte; Zerahn, Bo

    2018-01-01

    BACKGROUND: The large-diameter metal-on-metal hip prostheses were expected to have low wear and reduced dislocation rate compared to the traditional metal-on-polyethylene implants. We compare 2 such prostheses, the ReCap resurfacing implant and the M2a-Magnum stemmed implant, with the C2a ceramic......-on-ceramic stemmed implant as to clinical performance, serum concentrations of prosthesis metals, and the durability of the implants in a randomized, controlled clinical trial at 7 years of follow-up. METHODS: All included patients had osteoarthritis. Preoperatively, the size of the implants was estimated from...... of the soft tissue adjacent to the implant as well as MRI with metal artifact reduction sequence (MARS-MRI) when indicated. RESULTS: One hundred fifty-two hips in 146 patients were included. The serum cobalt and chromium concentrations were significantly higher for the 2 metal-on-metal prostheses than...

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

    Energy Technology Data Exchange (ETDEWEB)

    Haddock, Bryan; Holm, Soeren; Poulsen, Jakup M.; Enevoldsen, Lotte H.; Larsson, Henrik B.W.; Kjaer, Andreas; Suetta, Charlotte [Rigshospitalet Glostrup, Copenhagen University Hospital, Department of Clinical Physiology, Nuclear Medicine and PET, Glostrup (Denmark)

    2017-04-15

    The aim of this study was to determine the relationship between relative glucose uptake and MRI T{sub 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 {sup 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 {sup 18}F-FDG PET/MRI and muscle groups were evaluated for increases in {sup 18}F-FDG uptake and MRI T{sub 2} values. A significant linear correlation between {sup 18}F-FDG uptake and changes in muscle T{sub 2} (R {sup 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 {sup 18}F-FDG uptake and changes in muscle T{sub 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 {sup 18}F-FDG uptake and changes in muscle T{sub 2} with physical exercise. Accordingly, it seems that changes in muscle T{sub 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. 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.

  7. Effect of pulse sequence parameter selection on signal strength in positive-contrast MRI markers for MRI-based prostate postimplant assessment

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Tze Yee [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and The University of Texas at Houston Graduate School of Biomedical Sciences, 6767 Bertner Avenue, Houston, Texas 77030 (United States); Kudchadker, Rajat J., E-mail: rkudchad@mdanderson.org; Wang, Jihong; Ibbott, Geoffrey S. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Stafford, R. Jason [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); MacLellan, Christopher [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 and The University of Texas at Houston Graduate School of Biomedical Sciences, 6767 Bertner Avenue, Houston, Texas 77030 (United States); Rao, Arvind [Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); Frank, Steven J. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States)

    2016-07-15

    Purpose: For postimplant dosimetric assessment, computed tomography (CT) is commonly used to identify prostate brachytherapy seeds, at the expense of accurate anatomical contouring. Magnetic resonance imaging (MRI) is superior to CT for anatomical delineation, but identification of the negative-contrast seeds is challenging. Positive-contrast MRI markers were proposed to replace spacers to assist seed localization on MRI images. Visualization of these markers under varying scan parameters was investigated. Methods: To simulate a clinical scenario, a prostate phantom was implanted with 66 markers and 86 seeds, and imaged on a 3.0T MRI scanner using a 3D fast radiofrequency-spoiled gradient recalled echo acquisition with various combinations of scan parameters. Scan parameters, including flip angle, number of excitations, bandwidth, field-of-view, slice thickness, and encoding steps were systematically varied to study their effects on signal, noise, scan time, image resolution, and artifacts. Results: The effects of pulse sequence parameter selection on the marker signal strength and image noise were characterized. The authors also examined the tradeoff between signal-to-noise ratio, scan time, and image artifacts, such as the wraparound artifact, susceptibility artifact, chemical shift artifact, and partial volume averaging artifact. Given reasonable scan time and managable artifacts, the authors recommended scan parameter combinations that can provide robust visualization of the MRI markers. Conclusions: The recommended MRI pulse sequence protocol allows for consistent visualization of the markers to assist seed localization, potentially enabling MRI-only prostate postimplant dosimetry.

  8. MRI of pituitary adenomas following treatment

    Energy Technology Data Exchange (ETDEWEB)

    Gouliamos, A. [Dept. of Radiology, CT and MRI Section, Areteion Hospital, Univ. of Athens (Greece); Athanassopoulou, A. [Dept. of Radiology, CT and MRI Section, Areteion Hospital, Univ. of Athens (Greece); Rologis, D. [Neurosurgical Clinic, Athens General Hospital (Greece); Kalovidouris, A. [Dept. of Radiology, CT and MRI Section, Areteion Hospital, Univ. of Athens (Greece); Kotoulas, G. [Dept. of Radiology, CT and MRI Section, Areteion Hospital, Univ. of Athens (Greece); Vlahos, L. [Dept. of Radiology, CT and MRI Section, Areteion Hospital, Univ. of Athens (Greece); Papavassiliou, C. [Dept. of Radiology, CT and MRI Section, Areteion Hospital, Univ. of Athens (Greece)

    1993-10-01

    The purpose of this study was to assess pituitary adenomas following surgical and/or medical treatment in 28 patients. All patients were evaluated with both computed tomography (CT) and magnetic resonance imaging (MRI). The results were correlated with the clinical findings. Apart from the visualization of the adenoma itself (either residual or recurrent) other findings and in particular, morphological changes of the optic chiasm, the pituitary stalk and the sellar floor were evaluated with both imaging modalities. By comparing the two imaging modalities it was found that MRI was superior to CT in demonstrating residual/recurrent adenoma as well as evaluating the morphological changes of the optic chiasm and optic nerves. CT was superior or equal to MR in demonstrating the sellar floor changes. The intra-operatively implanted fat was equally seen by CT and MR. In conclusion, the anatomical variations of the optic chiasm and pituitary stalk are better visualized by MRI and allow a more precise evaluation of changes attributed to surgical or medical treatment of pituitary adenomas. (orig.)

  9. MRI of pituitary adenomas following treatment

    International Nuclear Information System (INIS)

    Gouliamos, A.; Athanassopoulou, A.; Rologis, D.; Kalovidouris, A.; Kotoulas, G.; Vlahos, L.; Papavassiliou, C.

    1993-01-01

    The purpose of this study was to assess pituitary adenomas following surgical and/or medical treatment in 28 patients. All patients were evaluated with both computed tomography (CT) and magnetic resonance imaging (MRI). The results were correlated with the clinical findings. Apart from the visualization of the adenoma itself (either residual or recurrent) other findings and in particular, morphological changes of the optic chiasm, the pituitary stalk and the sellar floor were evaluated with both imaging modalities. By comparing the two imaging modalities it was found that MRI was superior to CT in demonstrating residual/recurrent adenoma as well as evaluating the morphological changes of the optic chiasm and optic nerves. CT was superior or equal to MR in demonstrating the sellar floor changes. The intra-operatively implanted fat was equally seen by CT and MR. In conclusion, the anatomical variations of the optic chiasm and pituitary stalk are better visualized by MRI and allow a more precise evaluation of changes attributed to surgical or medical treatment of pituitary adenomas. (orig.)

  10. Diffusion, confusion and functional MRI

    International Nuclear Information System (INIS)

    Le Bihan, Denis

    2012-01-01

    Diffusion MRI has been introduced in 1985 and has had a very successful life on its own. While it has become a standard for imaging stroke and white matter disorders, the borders between diffusion MRI and the general field of fMRI have always remained fuzzy. First, diffusion MRI has been used to obtain images of brain function, based on the idea that diffusion MRI could also be made sensitive to blood flow, through the intra-voxel incoherent motion (IVIM) concept. Second, the IVIM concept helped better understand the contribution from different vasculature components to the BOLD fMRI signal. Third, it has been shown recently that a genuine fMRI signal can be obtained with diffusion MRI. This 'DfMRI' signal is notably different from the BOLD fMRI signal, especially for its much faster response to brain activation both at onset and offset, which points out to structural changes in the neural tissues, perhaps such as cell swelling, occurring in activated neural tissue. This short article reviews the major steps which have paved the way for this exciting development, underlying how technical progress with MRI equipment has each time been instrumental to expand the horizon of diffusion MRI toward the field of fMRI. (authors)

  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. 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)

  13. 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.

  14. 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.

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.)

  3. 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.

  4. 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.

  5. 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.

  6. Magnetic Resonance Imaging of Surgical Implants Made from Weak Magnetic Materials

    Science.gov (United States)

    Gogola, D.; Krafčík, A.; Štrbák, O.; Frollo, I.

    2013-08-01

    Materials with high magnetic susceptibility cause local inhomogeneities in the main field of the magnetic resonance (MR) tomograph. These inhomogeneities lead to loss of phase coherence, and thus to a rapid loss of signal in the image. In our research we investigated inhomogeneous field of magnetic implants such as magnetic fibers, designed for inner suture during surgery. The magnetic field inhomogeneities were studied at low magnetic planar phantom, which was made from four thin strips of magnetic tape, arranged grid-wise. We optimized the properties of imaging sequences with the aim to find the best setup for magnetic fiber visualization. These fibers can be potentially exploited in surgery for internal stitches. Stitches can be visualized by the magnetic resonance imaging (MRI) method after surgery. This study shows that the imaging of magnetic implants is possible by using the low field MRI systems, without the use of complicated post processing techniques (e.g., IDEAL).

  7. 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.

  8. Congenital malformations of the inner ear and the vestibulocochlear nerve in children with sensorineural hearing loss: evaluation with CT and MRI.

    Science.gov (United States)

    Westerhof, J P; Rademaker, J; Weber, B P; Becker, H

    2001-01-01

    The purpose of this work was to study the diagnostic value of CT and MRI in children with sensorineural hearing loss and to analyze anatomic abnormalities of the inner ear and the vestibulocochlear nerve in this patient group. We evaluated 42 inner ears in 21 children with congenital deafness who had congenital inner ear malformations and who were candidates for cochlear implants. All patients were studied with high resolution MR and helical CT examinations. The MR study included a T2-weighted 3D fast SE sequence. We describe and tabulate the anatomic abnormalities. Special attention was given to abnormalities of the vestibulocochlear nerve. The field of view in the plane according to the length axis of the internal auditory canal (IAC) was 4 cm. Additional continuous parasagittal reformations perpendicular to the length axis of the IAC were studied with a field of view of 3 cm. CT and MRI allowed accurate identification of malformations of the inner ear in children with congenital deafness. We identified 99 malformations, with a majority of patients demonstrating multiple abnormalities. Common imaging findings were Mondini abnormality and Mondini variants (12/42) and fusion of the lateral or superior semicircular canal with the vestibule (12/42). MRI demonstrated in 9 of 21 patients a rudimentary or absent vestibulocochlear nerve in the auditory canal. CT and MRI are important modalities to analyze the inner ear in children who are candidates for cochlear implants. MRI with an extremely small field of view should be used to study possible abnormalities of the vestibulocochlear nerves. This may alter clinical care and allow cochlear implant placement in patients whose electrodiagnostic studies suggest that the implant should not be performed. The detailed analysis of abnormalities of the inner ear might establish prognostic factors.

  9. The effect of varying implant position in immediately loaded implant-supported mandibular overdentures.

    Science.gov (United States)

    Shaarawy, Mohammed A; Aboelross, Ehab M

    2013-06-01

    This study was carried out to evaluate the effect of varying implant position in immediately loaded implant-supported mandibular overdentures on peri-implant bone density, muscle activity, and patient satisfaction. Fourteen completely edentulous patients were selected for the study. After complete denture construction, patients were divided into 2 equal groups. Four dental implants were installed bilaterally in the interforaminal region in the first group, while in the second group, 4 dental implants were inserted bilaterally: 2 in the interforaminal region and 2 in the first molar area. Immediately after suturing, telescopic abutments were screwed to the implants, and the retaining caps were picked up into the fitting surface of the lower denture, which was delivered to the patient. Patients were recalled for radiographic bone density evaluation just after denture delivery and then at 3, 6, and 12 months thereafter. Muscle activities of masseter and temporalis muscles as well as patient satisfaction were also evaluated. The results of the study showed a high success rate approximating 98.2% of the immediately loaded implants. The electromyographic (EMG) records of both muscles in group 1 were significantly higher during chewing hard food after 3 months compared with group 2 (P overdentures through posterior placement beyond the interforaminal area results in a favorable response in terms of increased peri-implant bone density as well as decreased EMG activity of masseter and temporalis muscles.

  10. 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

  11. 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

  12. Novel digital imaging techniques to assess the outcome in oral rehabilitation with dental implants: a narrative review.

    Science.gov (United States)

    Benic, Goran I; Elmasry, Moustafa; Hämmerle, Christoph H F

    2015-09-01

    To examine the literature on novel digital imaging techniques for the assessment of outcomes in oral rehabilitation with dental implants. An electronic search of Medline and Embase databases including studies published prior to 28th December 2014 was performed and supplemented by a manual search. A synthesis of the publications was presented describing the use of computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography, optical scanning, spectrophotometry or optical coherence tomography (OCT) related to the outcome measures in implant therapy. Most of the digital imaging techniques have not yet sufficiently been validated to be used for outcome measures in implant dentistry. In clinical research, cone beam CT (CBCT) is increasingly being used for 3D assessment of bone and soft tissue following augmentation procedures and implant placement. Currently, there are no effective methods for the reduction of artifacts around implants in CBCT. Optical scanning is being used for the 3D assessment of changes in the soft tissue contour. The combination of optical scan with pre-operative CBCT allows the determination of the implant position and its spatial relation to anatomical structures. Spectrophotometry is the method most commonly used to objectively assess the color match of reconstructions and peri-implant mucosa to natural dentition and gingiva. New optical imaging techniques may be considered possible approaches for monitoring peri-implant soft tissue health. MRI and ultrasonography appear promising non-ionizing radiation imaging modalities for the assessment of soft tissue and bone defect morphologies. Optical scanners and OCT may represent efficient clinical methods for accurate assessment of the misfit between the reconstructions and the implants. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. 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

  14. 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.)

  15. 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.)

  16. 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.)

  17. 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.

  18. Close relationship between fMRI signals and transient heart rate changes accompanying K-complex. Simultaneous EEG/fMRI study

    International Nuclear Information System (INIS)

    Kan, Shigeyuki; Koike, Takahiko; Miyauchi, Satoru; Misaki, Masaya

    2009-01-01

    Combining functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) allows the investigation of spontaneous activities in the human brain. Recently, by using this technique, increases in fMRI signal accompanying transient EEG activities such as sleep spindles and slow waves were reported. Although these fMRI signal increases appear to arise as a result of the neural activities being reflected in the EEG, when the influence of physiological activities upon fMRI signals are taken into consideration, it is highly controversial that fMRI signal increases accompanying transient EEG activities reflect actual neural activities. In the present study, we conducted simultaneous fMRI and polysomnograph recording of 18 normal adults, to study the effect of transient heart rate changes after a K-complex on fMRI signals. Significant fMRI signal increase was observed in the cerebellum, the ventral thalamus, the dorsal part of the brainstem, the periventricular white matter and the ventricle (quadrigeminal cistern). On the other hand, significant fMRI signal decrease was observed only in the right insula. Moreover, intensities of fMRI signal increase that was accompanied by a K-complex correlated positively with the magnitude of heart rate changes after a K-complex. Previous studies have reported that K-complex is closely related with sympathetic nervous activity and that the attributes of perfusion regulation in the brain differ during wakefulness and sleep. By taking these findings into consideration, our present results indicate that a close relationship exists between a K-complex and the changes in cardio- and neurovascular regulations that are mediated by the autonomic nervous system during sleep; further, these results indicate that transient heart rate changes after a K-complex can affect the fMRI signal generated in certain brain regions. (author)

  19. 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.)

  20. Language changes coincide with motor and fMRI changes following upper extremity motor therapy for hemiparesis: a brief report.

    Science.gov (United States)

    Harnish, Stacy; Meinzer, Marcus; Trinastic, Jonathan; Fitzgerald, David; Page, Stephen

    2014-09-01

    To formally assess changes in language, affected UE movement, and motor functional activation changes via functional magnetic resonance imaging (fMRI) following participation in motor therapy without any accompanying language intervention. Pre-post case series. Five subjects with stroke exhibiting chronic, stable UE hemiparesis. The upper extremity section of the Fugl-Meyer (FM), the Western Aphasia Battery (WAB), and functional magnetic resonance imaging (fMRI), administered during performance of an affected UE motor task. All subjects were administered six weeks of repetitive task specific training (RTP), performed for approximately 2.5 hours per day, split into two sessions. For the first four weeks of the intervention period, RTP was administered every weekday, whereas, for the subsequent two weeks, RTP was administered 3 days/week. Epidural cortical stimulation was co-administered with the RTP via an electrode array and implanted pulse generator. For all sessions, one subject worked with a single therapist. Four weeks before and four weeks after the intervention period, all subjects were administered the FM, WAB, and fMRI. Three of the subjects exhibited clinically significant language changes on the WAB. These individuals exhibited the largest motor changes as measured by the FM. Functional MRI revealed distinct motor activation patterns in these subjects, characterized by more strongly right lateralized focal BOLD activity or a shift in activation toward the right hemisphere. Language changes appear to co-occur with motor changes after UE RTP. Understanding the underlying mechanisms of these findings may lead to more efficient and synergistic rehabilitative therapy delivery.

  1. 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.

  2. Experience with magnetic resonance imaging of human subjects with passive implants and tattoos at 7 T: a retrospective study.

    Science.gov (United States)

    Noureddine, Yacine; Bitz, Andreas K; Ladd, Mark E; Thürling, Markus; Ladd, Susanne C; Schaefers, Gregor; Kraff, Oliver

    2015-12-01

    Over the last decade, the number of clinical MRI studies at 7 T has increased dramatically. Since only limited information about the safety of implants/tattoos is available at 7 T, many centers either conservatively exclude all subjects with implants/tattoos or have started to perform dedicated tests for selected implants. This work presents our experience in imaging volunteers with implants/tattoos at 7 T over the last seven and a half years. 1796 questionnaires were analyzed retrospectively to identify subjects with implants/tattoos imaged at 7 T. For a total of 230 subjects, the type of local transmit/receive RF coil used for examination, imaging sequences, acquisition time, and the type of implants/tattoos and their location with respect to the field of view were documented. These subjects had undergone examination after careful consideration by an internal safety panel consisting of three experts in MR safety and physics. None of the subjects reported sensations of heat or force before, during, or after the examination. None expressed any discomfort related to implants/tattoos. Artifacts were reported in 52% of subjects with dental implants; all artifacts were restricted to the mouth area and did not affect image quality in the brain parenchyma. Our initial experience at 7 T indicates that a strict rejection of subjects with tattoos and/or implants is not justified. Imaging can be conditionally performed in carefully selected subjects after collection of substantial safety information and evaluation of the detailed exposure scenario (RF coil/type and position of implant). Among the assessed subjects with tattoos, no side effects from the exposure to 7 T MRI were reported.

  3. Evaluation of electrode position in deep brain stimulation by image fusion (MRI and CT)

    Energy Technology Data Exchange (ETDEWEB)

    Barnaure, I.; Lovblad, K.O.; Vargas, M.I. [Geneva University Hospital, Department of Neuroradiology, Geneva 14 (Switzerland); Pollak, P.; Horvath, J.; Boex, C.; Burkhard, P. [Geneva University Hospital, Department of Neurology, Geneva (Switzerland); Momjian, S. [Geneva University Hospital, Department of Neurosurgery, Geneva (Switzerland); Remuinan, J. [Geneva University Hospital, Department of Radiology, Geneva (Switzerland)

    2015-09-15

    Imaging has an essential role in the evaluation of correct positioning of electrodes implanted for deep brain stimulation (DBS). Although MRI offers superior anatomic visualization of target sites, there are safety concerns in patients with implanted material; imaging guidelines are inconsistent and vary. The fusion of postoperative CT with preoperative MRI images can be an alternative for the assessment of electrode positioning. The purpose of this study was to assess the accuracy of measurements realized on fused images (acquired without a stereotactic frame) using a manufacturer-provided software. Data from 23 Parkinson's disease patients who underwent bilateral electrode placement for subthalamic nucleus (STN) DBS were acquired. Preoperative high-resolution T2-weighted sequences at 3 T, and postoperative CT series were fused using a commercially available software. Electrode tip position was measured on the obtained images in three directions (in relation to the midline, the AC-PC line and an AC-PC line orthogonal, respectively) and assessed in relation to measures realized on postoperative 3D T1 images acquired at 1.5 T. Mean differences between measures carried out on fused images and on postoperative MRI lay between 0.17 and 0.97 mm. Fusion of CT and MRI images provides a safe and fast technique for postoperative assessment of electrode position in DBS. (orig.)

  4. 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.

  5. 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

  6. Impact of dental implant insertion method on the peri-implant bone tissue: Experimental study

    Directory of Open Access Journals (Sweden)

    Stamatović Novak

    2013-01-01

    Full Text Available Background/Aim. The function of dental implants depends on their stability in bone tissue over extended period of time, i.e. on osseointegration. The process through which osseointegration is achieved depends on several factors, surgical insertion method being one of them. The aim of this study was to histopathologically compare the impact of the surgical method of implant insertion on the peri-implant bone tissue. Methods. The experiment was performed on 9 dogs. Eight weeks following the extraction of lower premolars implants were inserted using the one-stage method on the right mandibular side and two-stage method on the left side. Three months after implantation the animals were sacrificed. Three distinct regions of bone tissue were histopathologically analyzed, the results were scored and compared. Results. In the specimens of one-stage implants increased amount of collagen fibers was found in 5 specimens where tissue necrosis was also observed. Only moderate osteoblastic activity was found in 3 sections. The analysis of bone-to-implant contact region revealed statistically significantly better results regarding the amount of collagen tissue fibers for the implants inserted in the two-stage method (Wa = 59 105, α = 0.05. No necrosis and osteoblastic activity were observed. Conclusion. Better results were achieved by the two-stage method in bone-to-implant contact region regarding the amount of collagen tissue, while the results were identical regarding the osteoblastic activity and bone tissue necrosis. There was no difference between the methods in the bone-implant interface region. In the bone tissue adjacent to the implant the results were identical regarding the amount of collagen tissue, osteoblastic reaction and bone tissue necrosis, while better results were achieved by the two-stage method regarding the number of osteocytes.

  7. 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

  8. 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

  9. Clinical application of functional MRI

    International Nuclear Information System (INIS)

    Taniwaki, Takayuki

    2010-01-01

    Described is the present state of clinical application of fMRI in the preoperative assessment of brain tumors, and plasticity in and pathophysiology of central diseases. For the tumor resection, fMRI is useful for risk assessment of postoperative nerve dysfunction, for selection of the patient rather suitable for brain mapping at the invasive surgery than at the pre-operation and for guidance of the operation itself. Preoperative fMRI alone can neither distinguish the regions of the primary and secondary functions nor exhibit the relation between the tumor and white matter fibers but there are compensatory means for these drawbacks. Benefit of preoperative fMRI has not yet been based on the evidence on double blind trials. Combination of fMRI imaging and electroencephalography (EEG) finding has shown that, in generalized epilepsy, extensive and stimulated activation occurs in both frontal/occipital regions and in thalamus area, respectively, and that the concomitant lowered activities are conceivably the reflection of burst discharge in normal brain functions. Plasticity in the human brain has been demonstrated by fMRI in cerebral vascular diseases, multiple sclerosis and amyotrophic lateral sclerosis. Pathogenesis of Parkinson disease and depression has been better understood by fMRI investigations revealing regions with elevated and reduced activities. Studies of attention deficit hyperactivity disorder have shown similar change of activities with functional reductions of the right dorsolateral frontal anterior area and of dorsal frontal cingulate gyrus, together with stimulated wider regions to given tasks. As above, fMRI has greatly contributed to our understanding of diseases of central nervous system and is to be expected to expand wider in this field. (T.T.)

  10. 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.

  11. 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....

  12. 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

  13. High-resolution metal artifact reduction MR imaging of the lumbosacral plexus in patients with metallic implants

    Energy Technology Data Exchange (ETDEWEB)

    Ahlawat, Shivani; Fritz, Jan [The Johns Hopkins Medical Institutions, The Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, MD (United States); Stern, Steven E. [Bond University, Bond Business School, Gold Coast, QLD (Australia); Belzberg, Allan J. [Johns Hopkins University School of Medicine, Department of Neurosurgery, Baltimore, MD (United States)

    2017-07-15

    To assess the quality and accuracy of metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) for the diagnosis of lumbosacral neuropathies in patients with metallic implants in the pelvis. Twenty-two subjects with lumbosacral neuropathy following pelvic instrumentation underwent 1.5-T MARS MRI including optimized axial intermediate-weighted and STIR turbo spin echo sequences extending from L5 to the ischial tuberosity. Two readers graded the visibility of the lumbosacral trunk, sciatic, femoral, lateral femoral cutaneous, and obturator nerves and the nerve signal intensity of nerve, architecture, caliber, course, continuity, and skeletal muscle denervation. Clinical examination and electrodiagnostic studies were used as the standard of reference. Descriptive, agreement, and diagnostic performance statistics were applied. Lumbosacral plexus visibility on MARS MRI was good (4) or very good (3) in 92% of cases with 81% exact agreement and a Kendall's W coefficient of 0.811. The obturator nerve at the obturator foramen and the sciatic nerve posterior to the acetabulum had the lowest visibility, with good or very good ratings in only 61% and 77% of cases respectively. The reader agreement for nerve abnormalities on MARS MRI was excellent, ranging from 95.5 to 100%. MARS MRI achieved a sensitivity of 86%, specificity of 67%, positive predictive value of 95%, and negative predictive value of 40%, and accuracy of 83% for the detection of neuropathy. MARS MRI yields high image quality and diagnostic accuracy for the assessment of lumbosacral neuropathies in patients with metallic implants of the pelvis and hips. (orig.)

  14. High-resolution metal artifact reduction MR imaging of the lumbosacral plexus in patients with metallic implants.

    Science.gov (United States)

    Ahlawat, Shivani; Stern, Steven E; Belzberg, Allan J; Fritz, Jan

    2017-07-01

    To assess the quality and accuracy of metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) for the diagnosis of lumbosacral neuropathies in patients with metallic implants in the pelvis. Twenty-two subjects with lumbosacral neuropathy following pelvic instrumentation underwent 1.5-T MARS MRI including optimized axial intermediate-weighted and STIR turbo spin echo sequences extending from L5 to the ischial tuberosity. Two readers graded the visibility of the lumbosacral trunk, sciatic, femoral, lateral femoral cutaneous, and obturator nerves and the nerve signal intensity of nerve, architecture, caliber, course, continuity, and skeletal muscle denervation. Clinical examination and electrodiagnostic studies were used as the standard of reference. Descriptive, agreement, and diagnostic performance statistics were applied. Lumbosacral plexus visibility on MARS MRI was good (4) or very good (3) in 92% of cases with 81% exact agreement and a Kendall's W coefficient of 0.811. The obturator nerve at the obturator foramen and the sciatic nerve posterior to the acetabulum had the lowest visibility, with good or very good ratings in only 61% and 77% of cases respectively. The reader agreement for nerve abnormalities on MARS MRI was excellent, ranging from 95.5 to 100%. MARS MRI achieved a sensitivity of 86%, specificity of 67%, positive predictive value of 95%, and negative predictive value of 40%, and accuracy of 83% for the detection of neuropathy. MARS MRI yields high image quality and diagnostic accuracy for the assessment of lumbosacral neuropathies in patients with metallic implants of the pelvis and hips.

  15. High-resolution metal artifact reduction MR imaging of the lumbosacral plexus in patients with metallic implants

    International Nuclear Information System (INIS)

    Ahlawat, Shivani; Fritz, Jan; Stern, Steven E.; Belzberg, Allan J.

    2017-01-01

    To assess the quality and accuracy of metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) for the diagnosis of lumbosacral neuropathies in patients with metallic implants in the pelvis. Twenty-two subjects with lumbosacral neuropathy following pelvic instrumentation underwent 1.5-T MARS MRI including optimized axial intermediate-weighted and STIR turbo spin echo sequences extending from L5 to the ischial tuberosity. Two readers graded the visibility of the lumbosacral trunk, sciatic, femoral, lateral femoral cutaneous, and obturator nerves and the nerve signal intensity of nerve, architecture, caliber, course, continuity, and skeletal muscle denervation. Clinical examination and electrodiagnostic studies were used as the standard of reference. Descriptive, agreement, and diagnostic performance statistics were applied. Lumbosacral plexus visibility on MARS MRI was good (4) or very good (3) in 92% of cases with 81% exact agreement and a Kendall's W coefficient of 0.811. The obturator nerve at the obturator foramen and the sciatic nerve posterior to the acetabulum had the lowest visibility, with good or very good ratings in only 61% and 77% of cases respectively. The reader agreement for nerve abnormalities on MARS MRI was excellent, ranging from 95.5 to 100%. MARS MRI achieved a sensitivity of 86%, specificity of 67%, positive predictive value of 95%, and negative predictive value of 40%, and accuracy of 83% for the detection of neuropathy. MARS MRI yields high image quality and diagnostic accuracy for the assessment of lumbosacral neuropathies in patients with metallic implants of the pelvis and hips. (orig.)

  16. Real-time fMRI neurofeedback of the mediodorsal and anterior thalamus enhances correlation between thalamic BOLD activity and alpha EEG rhythm.

    Science.gov (United States)

    Zotev, Vadim; Misaki, Masaya; Phillips, Raquel; Wong, Chung Ki; Bodurka, Jerzy

    2018-02-01

    Real-time fMRI neurofeedback (rtfMRI-nf) with simultaneous EEG allows volitional modulation of BOLD activity of target brain regions and investigation of related electrophysiological activity. We applied this approach to study correlations between thalamic BOLD activity and alpha EEG rhythm. Healthy volunteers in the experimental group (EG, n = 15) learned to upregulate BOLD activity of the target region consisting of the mediodorsal (MD) and anterior (AN) thalamic nuclei using rtfMRI-nf during retrieval of happy autobiographical memories. Healthy subjects in the control group (CG, n = 14) were provided with a sham feedback. The EG participants were able to significantly increase BOLD activities of the MD and AN. Functional connectivity between the MD and the inferior precuneus was significantly enhanced during the rtfMRI-nf task. Average individual changes in the occipital alpha EEG power significantly correlated with the average MD BOLD activity levels for the EG. Temporal correlations between the occipital alpha EEG power and BOLD activities of the MD and AN were significantly enhanced, during the rtfMRI-nf task, for the EG compared to the CG. Temporal correlations with the alpha power were also significantly enhanced for the posterior nodes of the default mode network, including the precuneus/posterior cingulate, and for the dorsal striatum. Our findings suggest that the temporal correlation between the MD BOLD activity and posterior alpha EEG power is modulated by the interaction between the MD and the inferior precuneus, reflected in their functional connectivity. Our results demonstrate the potential of the rtfMRI-nf with simultaneous EEG for noninvasive neuromodulation studies of human brain function. © 2017 Wiley Periodicals, Inc.

  17. 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

  18. Zinc and phosphorus co-implantation in indium phosphide

    International Nuclear Information System (INIS)

    Yu, K.M.; Ridgway, M.C.

    1998-01-01

    Electrical activation and dopant diffusion in Zn-implanted InP after rapid thermal annealing have been investigated. For an as-implanted Zn concentration of ∼4x10 19 thinspcm -3 , only ∼7% of the implanted Zn atoms formed electrically active shallow acceptors following a 950thinsp degree C/5 s annealing cycle. The low activation was the result of rapid Zn out-diffusion emdash only ∼14% of the implanted dopant was retained after annealing. A significant enhancement in electrical activation and a reduction in Zn loss were achieved in Zn+P co-implanted samples which yielded a net hole concentration of ≤6x10 18 thinspcm -3 and >50% Zn retention. The saturation of the free hole concentration in Zn+P co-implanted samples was attributed to the formation of Zn interstitial donors and Group-V-related donor-type native defects. For comparison, Zn+Al and Zn+Al+P co-implanted samples were also examined to distinguish the relative influences of implantation-induced disorder and nonstoichiometry on electrical activation and dopant diffusion. For the given implant conditions, we found that nonstoichiometry was the dominant influence. copyright 1998 American Institute of Physics

  19. 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

  20. 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

  1. Development and clinical implementation of a new template for MRI-based intracavitary/interstitial gynecologic brachytherapy for locally advanced cervical cancer: from CT-based MUPIT to the MRI compatible Template Benidorm. Ten years of experience

    Directory of Open Access Journals (Sweden)

    Silvia Rodríguez Villalba

    2016-10-01

    Full Text Available Purpose : To study outcome and toxicity in 59 patients with locally advanced cervix carcinoma treated with computed tomography (CT-based Martinez universal perineal interstitial template (MUPIT and the new magnetic resonance imaging (MRI-compatible template Benidorm (TB. Material and methods: From December 2005 to October 2015, we retrospectively analyzed 34 patients treated with MUPIT and 25 treated with the TB. Six 4 Gy fractions were prescribed to the clinical target volume (CTV combined with external beam radiotherapy (EBRT. The organs at risk (OARs and the CTV were delineated by CT scan in the MUPIT implants and by MRI in the TB implants. Dosimetry was CT-based for MUPIT and exclusively MRI-based for TB. Dose values were biologically normalized to equivalent doses in 2 Gy fractions (EQD2. Results : Median CTV volumes were 163.5 cm3 for CT-based MUPIT (range 81.8-329.4 cm3 and 91.9 cm3 for MRI-based TB (range 26.2-161 cm3. Median D90 CTV (EBRT + BT was 75.8 Gy for CT-based MUPIT (range 69-82 Gy and 78.6 Gy for MRI-based TB (range 62.5-84.2. Median D2cm3 for the rectum was 75.3 Gy for CT-based MUPIT (range 69.8-132.1 Gy and 69.9 Gy for MRI-based TB (range 58.3-83.7 Gy. Median D2cm3 for the bladder was 79.8 Gy for CT-based MUPIT (range 71.2-121.1 Gy and 77.1 Gy for MRI-based TB (range 60.5-90.8 Gy. Local control (LC was 88%. Overall survival (OS, disease free survival (DFS, and LC were not statistically significant in either group. Patients treated with CT-based MUPIT had a significantly higher percentage of rectal bleeding G3 (p = 0.040 than those treated with MRI-based TB, 13% vs. 2%. Conclusions : Template Benidorm treatment using MRI-based dosimetry provides advantages of MRI volume definition, and allows definition of smaller volumes that result in statistically significant decreased rectal toxicity compared to that seen with CT-based MUPIT treatment.

  2. Individualised 3D printed vaginal template for MRI guided brachytherapy in locally advanced cervical cancer

    DEFF Research Database (Denmark)

    Lindegaard, Jacob Christian; Lænsø Madsen, Mads; Hansen, Anders Traberg

    2016-01-01

    Intracavitary–interstitial applicators for MRI guided brachytherapy are becoming increasingly important in locally advanced cervical cancer. The 3D printing technology enables a versatile method for obtaining a high degree of individualisation of the implant. Our clinical workflow is presented...

  3. Determining the risks of magnetic resonance imaging at 1.5 tesla for patients with pacemakers and implantable cardioverter defibrillators.

    Science.gov (United States)

    Cohen, Jennifer D; Costa, Heather S; Russo, Robert J

    2012-12-01

    Conventional pacemaker and implantable cardioverter-defibrillator product labeling currently cautions against exposure to magnetic resonance imaging (MRI). However, there is a growing clinical need for MRI, without an acceptable alternative imaging modality in many patients with cardiac devices. The purpose of this study was to determine the risk of MRI at 1.5 T for patients with cardiac devices by measuring the frequency of device failures and clinically relevant device parameter changes. Data from a single-center retrospective review of 109 patients with pacemakers and implantable cardioverter-defibrillators (the MRI group) who underwent 125 clinically indicated MRI studies were compared to data from a prospective cohort of 50 patients with cardiac devices who did not undergo MRI (the control group). In the MRI group, there were no deaths, device failures requiring generator or lead replacement, induced arrhythmias, losses of capture, or electrical reset episodes. Decreases in battery voltage of ≥0.04 V occurred in 4%, pacing threshold increases of ≥0.5 V in 3%, and pacing lead impedance changes of ≥50 Ω in 6%. Although there were statistically significant differences between the MRI and control groups for the mean change in pacing lead impedance (-6.2 ± 23.9 vs 3.0 ± 22.1 Ω) and left ventricular pacing threshold (-0.1 ± 0.3 vs 0.1 ± 0.2 V), these differences were not clinically important. In conclusion, MRI in patients with cardiac devices resulted in no device or lead failures. A small number of clinically relevant changes in device parameter measurements were noted. However, these changes were similar to those in a control group of patients who did not undergo MRI. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. 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.

  5. 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

  6. 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)

  7. 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.)

  8. Morphologic Features of Magnetic Resonance Imaging as a Surrogate of Capsular Contracture in Breast Cancer Patients With Implant-based Reconstructions.

    Science.gov (United States)

    Tyagi, Neelam; Sutton, Elizabeth; Hunt, Margie; Zhang, Jing; Oh, Jung Hun; Apte, Aditya; Mechalakos, James; Wilgucki, Molly; Gelb, Emily; Mehrara, Babak; Matros, Evan; Ho, Alice

    2017-02-01

    Capsular contracture (CC) is a serious complication in patients receiving implant-based reconstruction for breast cancer. Currently, no objective methods are available for assessing CC. The goal of the present study was to identify image-based surrogates of CC using magnetic resonance imaging (MRI). We analyzed a retrospective data set of 50 patients who had undergone both a diagnostic MRI scan and a plastic surgeon's evaluation of the CC score (Baker's score) within a 6-month period after mastectomy and reconstructive surgery. The MRI scans were assessed for morphologic shape features of the implant and histogram features of the pectoralis muscle. The shape features, such as roundness, eccentricity, solidity, extent, and ratio length for the implant, were compared with the Baker score. For the pectoralis muscle, the muscle width and median, skewness, and kurtosis of the intensity were compared with the Baker score. Univariate analysis (UVA) using a Wilcoxon rank-sum test and multivariate analysis with the least absolute shrinkage and selection operator logistic regression was performed to determine significant differences in these features between the patient groups categorized according to their Baker's scores. UVA showed statistically significant differences between grade 1 and grade ≥2 for morphologic shape features and histogram features, except for volume and skewness. Only eccentricity, ratio length, and volume were borderline significant in differentiating grade ≤2 and grade ≥3. Features with Pbreast cancer patients who undergo implant reconstruction. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. 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.

  10. 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...

  11. Initial experience with lung-MRI at 3.0 T: Comparison with CT and clinical data in the evaluation of interstitial lung disease activity

    International Nuclear Information System (INIS)

    Lutterbey, G.; Grohe, C.; Gieseke, J.; Falkenhausen, M. von; Morakkabati, N.; Wattjes, M.P.; Manka, R.; Trog, D.; Schild, H.H.

    2007-01-01

    Objectives: We evaluated the feasibility of highfield lung-MRI at 3.0 T. A comparison with Computed Tomography (CT) and clinical data regarding the assessment of inflammatory activity in patients with diffuse lung disease was performed. Material and methods: Prospective evaluation of 21 patients (15 males, 6 females, 43-80 y) with diffuse lung diseases who underwent clinical work-up inclusive laboratory tests, lung-function tests and transbronchial biopsy. After routine helical CT (additional 12 HRCT) a lung-MRI (3.0 Intera, Philips Medical Systems, Best, The Netherlands) using a T2-weighted, cardiac and respiratory triggered Fast-Spinecho-Sequence (TE/TR = 80/1500-2500 ms, 22 transverse slices, 7/2 mm slice-thickness/-gap) was performed. A pneumologist classified the cases into two groups: A = temporary acute interstitial disease or chronic interstitial lung disease with acute episode or superimposed infection/B = burned out interstitial lung disease without activity. Two blinded CT-radiologists graded the cases in active/inactive disease on the basis of nine morphological criteria each. A third radiologist rated the MRI-cases as active/inactive, depending on the signal-intensities of lung tissues. Results: The pneumologist classified 14 patients into group A and 7 patients into group B. Using CT, 6 cases were classified as active, 15 cases as inactive disease. With MRI 12 cases were classified as active and 9 cases as inactive. In the complete group of 21 patients MRI decisions and CT decisions respectively were false positive/false negative/correct in 2/4/15 respectively 0/8/13 cases. Correct diagnoses were obtained in 72% (MRI) respectively 62% (CT). In the subgroup of 12 cases including HRCT, MRI respectively CT were false positive/false negative/correct in 2/1/9 respectively 0/5/7 cases. Correct diagnoses were obtained in 75% (MRI) respectively 58% (CT). Conclusion: Highfield MRI of the lung is feasible and performed slightly better compared to CT in the

  12. Initial experience with lung-MRI at 3.0 T: Comparison with CT and clinical data in the evaluation of interstitial lung disease activity

    Energy Technology Data Exchange (ETDEWEB)

    Lutterbey, G. [Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn (Germany)]. E-mail: goetz.lutterbey@ukb.uni-bonn.de; Grohe, C. [Department of Internal Medicine, University of Bonn (Germany); Gieseke, J. [PHILIPS Medical Systems, Best (Netherlands); Falkenhausen, M. von [Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn (Germany); Morakkabati, N. [Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn (Germany); Wattjes, M.P. [Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn (Germany); Manka, R. [Department of Internal Medicine, University of Bonn (Germany); Trog, D. [Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn (Germany); Schild, H.H. [Department of Radiology, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn (Germany)

    2007-02-15

    Objectives: We evaluated the feasibility of highfield lung-MRI at 3.0 T. A comparison with Computed Tomography (CT) and clinical data regarding the assessment of inflammatory activity in patients with diffuse lung disease was performed. Material and methods: Prospective evaluation of 21 patients (15 males, 6 females, 43-80 y) with diffuse lung diseases who underwent clinical work-up inclusive laboratory tests, lung-function tests and transbronchial biopsy. After routine helical CT (additional 12 HRCT) a lung-MRI (3.0 Intera, Philips Medical Systems, Best, The Netherlands) using a T2-weighted, cardiac and respiratory triggered Fast-Spinecho-Sequence (TE/TR = 80/1500-2500 ms, 22 transverse slices, 7/2 mm slice-thickness/-gap) was performed. A pneumologist classified the cases into two groups: A = temporary acute interstitial disease or chronic interstitial lung disease with acute episode or superimposed infection/B = burned out interstitial lung disease without activity. Two blinded CT-radiologists graded the cases in active/inactive disease on the basis of nine morphological criteria each. A third radiologist rated the MRI-cases as active/inactive, depending on the signal-intensities of lung tissues. Results: The pneumologist classified 14 patients into group A and 7 patients into group B. Using CT, 6 cases were classified as active, 15 cases as inactive disease. With MRI 12 cases were classified as active and 9 cases as inactive. In the complete group of 21 patients MRI decisions and CT decisions respectively were false positive/false negative/correct in 2/4/15 respectively 0/8/13 cases. Correct diagnoses were obtained in 72% (MRI) respectively 62% (CT). In the subgroup of 12 cases including HRCT, MRI respectively CT were false positive/false negative/correct in 2/1/9 respectively 0/5/7 cases. Correct diagnoses were obtained in 75% (MRI) respectively 58% (CT). Conclusion: Highfield MRI of the lung is feasible and performed slightly better compared to CT in the

  13. 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.

  14. 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...

  15. 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.

  16. 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.

  17. 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.

  18. MRI after patellofemoral replacement: The preserved compartments

    International Nuclear Information System (INIS)

    Heyse, Thomas J.; Figiel, Jens; Hähnlein, Ulrike; Timmesfeld, Nina; Lakemeier, Stefan; Schofer, Markus D.; Fuchs-Winkelmann, Susanne; Efe, Turgay

    2012-01-01

    Introduction: The aim of this study was to assess the reproducibility of magnet resonance imaging (MRI) analysis of preserved anatomic structures of the knee after patellofemoral replacement (PFR). It was hypothesized that evaluation of cartilage, ligaments, meniscus and tendons would result in high inter-observer reliability after PFR. Material and methods: MRI, tailored to reduce metallic artefacts of the knee, after PFR was performed in seven patients. Two independent investigators evaluated cartilage, menisci, collateral and cruciate ligaments, the quadriceps and patellar tendons and the presence of joint effusion. The reviewers used a five-point scale to give a degree of confidence to their evaluation of each parameter. Inter-observer reliability was determined by calculation of Cohen's Kappas. Results: Artefact provoked by the implants was not observed. For all assessed structures, there was excellent inter-observer reliability, with high Cohen's Kappas. There were also high levels of inter-observer agreement and observer confidence in the evaluation of cartilage, meniscus, tendons, ligaments and joint effusion. Conclusion: Tailored MRI allows reproducible analysis of the preserved knee joint structures after PFR. It might prove helpful in assessment of painful knee joints after PFR

  19. MRI after patellofemoral replacement: The preserved compartments

    Energy Technology Data Exchange (ETDEWEB)

    Heyse, Thomas J., E-mail: heyse@med.uni-marburg.de [Department of Orthopedics and Rheumatology, University Hospital Marburg, Baldingerstrasse, 35043 Marburg (Germany); Figiel, Jens [Department of Radiology, University Hospital Marburg, Marburg (Germany); Hähnlein, Ulrike [Department of Orthopedics and Rheumatology, University Hospital Marburg, Baldingerstrasse, 35043 Marburg (Germany); Timmesfeld, Nina [Institute for Medical Biometry and Epidemiology, Marburg (Germany); Lakemeier, Stefan; Schofer, Markus D.; Fuchs-Winkelmann, Susanne; Efe, Turgay [Department of Orthopedics and Rheumatology, University Hospital Marburg, Baldingerstrasse, 35043 Marburg (Germany)

    2012-09-15

    Introduction: The aim of this study was to assess the reproducibility of magnet resonance imaging (MRI) analysis of preserved anatomic structures of the knee after patellofemoral replacement (PFR). It was hypothesized that evaluation of cartilage, ligaments, meniscus and tendons would result in high inter-observer reliability after PFR. Material and methods: MRI, tailored to reduce metallic artefacts of the knee, after PFR was performed in seven patients. Two independent investigators evaluated cartilage, menisci, collateral and cruciate ligaments, the quadriceps and patellar tendons and the presence of joint effusion. The reviewers used a five-point scale to give a degree of confidence to their evaluation of each parameter. Inter-observer reliability was determined by calculation of Cohen's Kappas. Results: Artefact provoked by the implants was not observed. For all assessed structures, there was excellent inter-observer reliability, with high Cohen's Kappas. There were also high levels of inter-observer agreement and observer confidence in the evaluation of cartilage, meniscus, tendons, ligaments and joint effusion. Conclusion: Tailored MRI allows reproducible analysis of the preserved knee joint structures after PFR. It might prove helpful in assessment of painful knee joints after PFR.

  20. 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.

  1. High energy ion implantation

    International Nuclear Information System (INIS)

    Ziegler, J.F.

    1985-01-01

    High energy ion implantation offers the oppertunity for unique structures in semiconductor processing. The unusual physical properties of such implantations are discussed as well as the special problems in masking and damage annealing. A review is made of proposed circuit structures which involve deep implantation. Examples are: deep buried bipolar collectors fabricated without epitaxy, barrier layers to reduce FET memory sensitivity to soft-fails, CMOS isolation well structures, MeV implantation for customization and correction of completed circuits, and graded reach-throughs to deep active device components. (orig.)

  2. 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.

  3. Ion implantation of boron in germanium

    International Nuclear Information System (INIS)

    Jones, K.S.

    1985-05-01

    Ion implantation of 11 B + into room temperature Ge samples leads to a p-type layer prior to any post implant annealing steps. Variable temperature Hall measurements and deep level transient spectroscopy experiments indicate that room temperature implantation of 11 B + into Ge results in 100% of the boron ions being electrically active as shallow acceptor, over the entire dose range (5 x 10 11 /cm 2 to 1 x 10 14 /cm 2 ) and energy range (25 keV to 100 keV) investigated, without any post implant annealing. The concentration of damage related acceptor centers is only 10% of the boron related, shallow acceptor center concentration for low energy implants (25 keV), but becomes dominant at high energies (100 keV) and low doses ( 12 /cm 2 ). Three damage related hole traps are produced by ion implantation of 11 B + . Two of these hole traps have also been observed in γ-irradiated Ge and may be oxygen-vacancy related defects, while the third trap may be divacancy related. All three traps anneal out at low temperatures ( 0 C). Boron, from room temperature implantation of BF 2 + into Ge, is not substitutionally active prior to a post implant annealing step of 250 0 C for 30 minutes. After annealing additional shallow acceptors are observed in BF 2 + implanted samples which may be due to fluorine or flourine related complexes which are electrically active

  4. 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.

  5. 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.

  6. Finite element analysis of the stress distributions in peri-implant bone in modified and standard-threaded dental implants

    Directory of Open Access Journals (Sweden)

    Serkan Dundar

    2016-01-01

    Full Text Available The aim of this study was to examine the stress distributions with three different loads in two different geometric and threaded types of dental implants by finite element analysis. For this purpose, two different implant models, Nobel Replace and Nobel Active (Nobel Biocare, Zurich, Switzerland, which are currently used in clinical cases, were constructed by using ANSYS Workbench 12.1. The stress distributions on components of the implant system under three different static loadings were analysed for the two models. The maximum stress values that occurred in all components were observed in FIII (300 N. The maximum stress values occurred in FIII (300 N when the Nobel Replace implant is used, whereas the lowest ones, in the case of FI (150 N loading in the Nobel Active implant. In all models, the maximum tensions were observed to be in the neck region of the implants. Increasing the connection between the implant and the bone surface may allow more uniform distribution of the forces of the dental implant and may protect the bone around the implant. Thus, the implant could remain in the mouth for longer periods. Variable-thread tapered implants can increase the implant and bone contact.

  7. Cochlear Implantation in Patients with Neurofibromatosis Type 2 and Patients with Vestibular Schwannoma in the Only Hearing Ear

    Directory of Open Access Journals (Sweden)

    Erika Celis-Aguilar

    2012-01-01

    Full Text Available Cochlear implants are a new surgical option in the hearing rehabilitation of patients with neurofibromatosis type 2 (NF2 and patients with vestibular schwannoma (VS in the only hearing ear. Auditory brainstem implant (ABI has been the standard surgical treatment for these patients. We performed a literature review of patients with NF2 and patients with VS in the only hearing ear. Cochlear implantation (CI provided some auditory benefit in all patients. Preservation of cochlear nerve integrity is crucial after VS resection. Results ranged from environmental sound awareness to excellent benefit with telephone use. Promontory stimulation is recommended although not crucial. MRI can be performed safely in cochlear implanted patients.

  8. 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

  9. Dual-ion implantation into GaAs

    International Nuclear Information System (INIS)

    Sealy, B.J.; Bell, E.C.; Surridge, R.K.; Stephens, K.G.; Ambridge, T.; Heckingbottom, R.

    1976-01-01

    A variety of dual implants have been carried out to test the theory of Ambridge and Heckingbottom (Ambridge, T. and Heckingbottom, R., 1973, Radiat. Effects, vol. 17, 31). After annealing at 700 0 C or 750 0 C a significant enhancement of electrical activity compared with single-ion implants has been obtained for (Ga + Se) and (Sn + Se) implants but the degree of enhancement is dose dependent. The results imply that the dual implantation process is more complex than predicted by the theory and the electrical activity measured seems to be dominated by residual, compensating damage. (author)

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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, Gareth J; Rubia, Katya; McGuire, Philip; Shergill, Sukhwinder S; Allen, Paul

    2018-02-12

    Neurocognitive models and previous neuroimaging work posit that auditory verbal hallucinations (AVH) arise due to increased activity in speech-sensitive regions of the left posterior superior temporal gyrus (STG). Here, we examined if patients with schizophrenia (SCZ) and AVH could be trained to down-regulate STG activity using real-time functional magnetic resonance imaging neurofeedback (rtfMRI-NF). We also examined the effects of rtfMRI-NF training on functional connectivity between the STG and other speech and language regions. Twelve patients with SCZ and treatment-refractory AVH were recruited to participate in the study and were trained to down-regulate STG activity using rtfMRI-NF, over four MRI scanner visits during a 2-week training period. STG activity and functional connectivity were compared pre- and post-training. Patients successfully learnt to down-regulate activity in their left STG over the rtfMRI-NF training. Post- training, patients showed increased functional connectivity between the left STG, the left inferior prefrontal gyrus (IFG) and the inferior parietal gyrus. The post-training increase in functional connectivity between the left STG and IFG was associated with a reduction in AVH symptoms over the training period. The speech-sensitive region of the left STG is a suitable target region for rtfMRI-NF in patients with SCZ and treatment-refractory AVH. Successful down-regulation of left STG activity can increase functional connectivity between speech motor and perception regions. These findings suggest that patients with AVH have the ability to alter activity and connectivity in speech and language regions, and raise the possibility that rtfMRI-NF training could present a novel therapeutic intervention in SCZ.

  19. 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

  20. 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…

  1. 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.

  2. 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.

  3. Correlation between resting state fMRI total neuronal activity and PET metabolism in healthy controls and patients with disorders of consciousness.

    Science.gov (United States)

    Soddu, Andrea; Gómez, Francisco; Heine, Lizette; Di Perri, Carol; Bahri, Mohamed Ali; Voss, Henning U; Bruno, Marie-Aurélie; Vanhaudenhuyse, Audrey; Phillips, Christophe; Demertzi, Athena; Chatelle, Camille; Schrouff, Jessica; Thibaut, Aurore; Charland-Verville, Vanessa; Noirhomme, Quentin; Salmon, Eric; Tshibanda, Jean-Flory Luaba; Schiff, Nicholas D; Laureys, Steven

    2016-01-01

    The mildly invasive 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a well-established imaging technique to measure 'resting state' cerebral metabolism. This technique made it possible to assess changes in metabolic activity in clinical applications, such as the study of severe brain injury and disorders of consciousness. We assessed the possibility of creating functional MRI activity maps, which could estimate the relative levels of activity in FDG-PET cerebral metabolic maps. If no metabolic absolute measures can be extracted, our approach may still be of clinical use in centers without access to FDG-PET. It also overcomes the problem of recognizing individual networks of independent component selection in functional magnetic resonance imaging (fMRI) resting state analysis. We extracted resting state fMRI functional connectivity maps using independent component analysis and combined only components of neuronal origin. To assess neuronality of components a classification based on support vector machine (SVM) was used. We compared the generated maps with the FDG-PET maps in 16 healthy controls, 11 vegetative state/unresponsive wakefulness syndrome patients and four locked-in patients. The results show a significant similarity with ρ = 0.75 ± 0.05 for healthy controls and ρ = 0.58 ± 0.09 for vegetative state/unresponsive wakefulness syndrome patients between the FDG-PET and the fMRI based maps. FDG-PET, fMRI neuronal maps, and the conjunction analysis show decreases in frontoparietal and medial regions in vegetative patients with respect to controls. Subsequent analysis in locked-in syndrome patients produced also consistent maps with healthy controls. The constructed resting state fMRI functional connectivity map points toward the possibility for fMRI resting state to estimate relative levels of activity in a metabolic map.

  4. 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 ...

  5. Functional MRI of the patellofemoral joint: comparison of ultrafast MRI, motion-triggered cine MRI and static MRI

    Energy Technology Data Exchange (ETDEWEB)

    Muhle, C. [Klinik fuer Radiologische Diagnostik, Univ. Kiel (Germany); Brossmann, J. [Klinik fuer Radiologische Diagnostik, Univ. Kiel (Germany); Melchert, U.H. [Klinik fuer Radiologische Diagnostik, Univ. Kiel (Germany); Schroeder, C. [Radiologische Abt., Universitaets-Kinderklinik, Christian-Albrechts-Universitaet, Kiel (Germany); Boer, R. de [Philips Medical Systems, Best (Netherlands); Spielmann, R.P. [Klinik fuer Radiologische Diagnostik, Univ. Kiel (Germany); Heller, M. [Klinik fuer Radiologische Diagnostik, Univ. Kiel (Germany)

    1995-12-31

    To evaluate the feasibility and usefulness of ultrafast MRI (u), patellar tracking from 30 of flexion to knee extension (0 ) was analysed and compared with motion-triggered cine MRI (m) and a static MRI technique (s). The different imaging methods were compared in respect of the patellofemoral relationship, the examination time and image quality. Eight healthy subjects and four patients (in total 18 joints) with patellar subluxation or luxation were examined. Significant differences between the static MRI series without quadriceps contraction and the functional MRI studies (motion-triggered cine MRI and ultrafast MRI) were found for the patellar tilt angle. In the dynamic joint studies there was no statistical difference of the regression coefficients between the motion-triggered cine MRI studies and the ultrafast MRI studies. The findings of the functional MRI studies compared with the static MRI images were significantly different for the lateralisation of the patella, expressed by the lateral patellar displacement and bisect offset. No significant differences in patellar lateralisation were found between motion-triggered cine MRI and ultrafast MRI. Ultrafast MRI was superior to motion-triggered cine MRI in terms of the reduction in imaging time and improvement of the image quality. (orig.)

  6. Functional MRI of the patellofemoral joint: comparison of ultrafast MRI, motion-triggered cine MRI and static MRI

    International Nuclear Information System (INIS)

    Muhle, C.; Brossmann, J.; Melchert, U.H.; Schroeder, C.; Boer, R. de; Spielmann, R.P.; Heller, M.

    1995-01-01

    To evaluate the feasibility and usefulness of ultrafast MRI (u), patellar tracking from 30 of flexion to knee extension (0 ) was analysed and compared with motion-triggered cine MRI (m) and a static MRI technique (s). The different imaging methods were compared in respect of the patellofemoral relationship, the examination time and image quality. Eight healthy subjects and four patients (in total 18 joints) with patellar subluxation or luxation were examined. Significant differences between the static MRI series without quadriceps contraction and the functional MRI studies (motion-triggered cine MRI and ultrafast MRI) were found for the patellar tilt angle. In the dynamic joint studies there was no statistical difference of the regression coefficients between the motion-triggered cine MRI studies and the ultrafast MRI studies. The findings of the functional MRI studies compared with the static MRI images were significantly different for the lateralisation of the patella, expressed by the lateral patellar displacement and bisect offset. No significant differences in patellar lateralisation were found between motion-triggered cine MRI and ultrafast MRI. Ultrafast MRI was superior to motion-triggered cine MRI in terms of the reduction in imaging time and improvement of the image quality. (orig.)

  7. A comparative study of two advanced spraying techniques for the deposition of biologically active enzyme coatings onto bone-substituting implants

    International Nuclear Information System (INIS)

    Jonge, Lise T. de; Ju, J.; Leeuwenburgh, S.C.G.; Yamagata, Y.; Higuchi, T.; Wolke, J.G.C.; Inoue, K.; Jansen, J.A.

    2010-01-01

    Surface modification of implant materials with biomolecule coatings is of high importance to improve implant fixation in bone tissue. In the current study, we present two techniques for the deposition of biologically active enzyme coatings onto implant materials. The well-established thin film ElectroSpray Deposition (ESD) technique was compared with the SAW-ED technique that combines high-frequency Surface Acoustic Wave atomization with Electrostatic Deposition. By immobilizing the enzyme alkaline phosphatase (ALP) onto implant surfaces, the influence of both SAW-ED and ESD deposition parameters on ALP deposition efficiency and ALP biological activity was investigated. ALP coatings with preserved enzyme activity were deposited by means of both the SAW-ED and ESD technique. The advantages of SAW-ED over ESD include the possibility to spray highly conductive protein solutions, and the 60-times faster deposition rate. Furthermore, significantly higher deposition efficiencies were observed for the SAW-ED technique compared to ESD. Generally, it was shown that protein inactivation is highly dependent on both droplet dehydration and the applied electrical field strength. The current study shows that SAW-ED is a versatile and flexible technique for the fabrication of functionally active biomolecule coatings.

  8. 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)

  9. Antibacterial iodine-supported titanium implants.

    Science.gov (United States)

    Shirai, T; Shimizu, T; Ohtani, K; Zen, Y; Takaya, M; Tsuchiya, H

    2011-04-01

    Deep infection remains a serious complication in orthopedic implant surgery. In order to reduce the incidence of implant-associated infections, several biomaterial surface treatments have been proposed. This study focused on evaluating the antibacterial activity of iodine-supported titanium (Ti-I(2)) and its impact on post-implant infection, as well as determining the potential suitability of Ti-I(2) as a biomaterial. External fixation pins were used in this experiment as trial implants because of the ease of making the septic models. The antibacterial activity of the metal was measured using a modification of the Japanese Industrial Standards method. Activity was evaluated by exposing the implants to Staphylococcus aureus or Escherichia coli and comparing reaction of pathogens to Ti-I(2) vs. stainless steel and titanium controls. Ti-I(2) clearly inhibited bacterial colonization more than the control metals. In addition, cytocompatibility was assessed by counting the number of colonies that formed on the metals. The three metals showed the same amount of fibroblast colony formation. Japanese white rabbits were used as an in vivo model. Three pins were inserted into both femora of six rabbits for histological analysis. Pin sites were inspected and graded for infection and inflammation. Fewer signs of infection and inflammatory changes were observed in conjunction with the Ti-I(2) pins. Furthermore, osteoconductivity of the implant was evaluated with osteoid formation surface of the pin. Consecutive bone formation was observed around the Ti-I(2) and titanium pins, while little osteoid formation was found around the stainless steel pins. These findings suggest that Ti-I(2) has antimicrobial activity and exhibits cytocompatibility. Therefore, Ti-I(2) substantially reduces the incidence of implant infection and shows particular promise as a biomaterial. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. MRI texture analysis (MRTA) of T2-weighted images in Crohn's disease may provide information on histological and MRI disease activity in patients undergoing ileal resection

    Energy Technology Data Exchange (ETDEWEB)

    Makanyanga, Jesica; Bhatnagar, Gauraang; Halligan, Steve; Taylor, Stuart A. [University College London and University College London Hospitals NIHR Biomedical Research Centre, Center for Medical Imaging, London (United Kingdom); Ganeshan, Balaji; Groves, Ashley; Miles, Ken [University College London, University College Hospital, Institute of Nuclear Medicine, London (United Kingdom); Rodriguez-Justo, Manuel [University College London, Department of Research Pathology, University College London Cancer Institute, London (United Kingdom)

    2017-02-15

    To associate MRI textural analysis (MRTA) with MRI and histological Crohn's disease (CD) activity. Sixteen patients (mean age 39.5 years, 9 male) undergoing MR enterography before ileal resection were retrospectively analysed. Thirty-six small (≤3 mm) ROIs were placed on T2-weighted images and location-matched histological acute inflammatory scores (AIS) measured. MRI activity (mural thickness, T2 signal, T1 enhancement) (CDA) was scored in large ROIs. MRTA features (mean, standard deviation, mean of positive pixels (MPP), entropy, kurtosis, skewness) were extracted using a filtration histogram technique. Spatial scale filtration (SSF) ranged from 2 to 5 mm. Regression (linear/logistic) tested associations between MRTA and AIS (small ROIs), and CDA/constituent parameters (large ROIs). Skewness (SSF = 2 mm) was associated with AIS [regression coefficient (rc) 4.27, p = 0.02]. Of 120 large ROI analyses (for each MRI, MRTA feature and SSF), 15 were significant. Entropy (SSF = 2, 3 mm) and kurtosis (SSF = 3 mm) were associated with CDA (rc 0.9, 1.0, -0.45, p = 0.006-0.01). Entropy and mean (SSF = 2-4 mm) were associated with T2 signal [odds ratio (OR) 2.32-3.16, p = 0.02-0.004], [OR 1.22-1.28, p = 0.03-0.04]. MPP (SSF = 2 mm) was associated with mural thickness (OR 0.91, p = 0.04). Kurtosis (SSF = 3 mm), standard deviation (SSF = 5 mm) were associated with decreased T1 enhancement (OR 0.59, 0.42, p = 0.004, 0.007). MRTA features may be associated with CD activity. (orig.)

  11. 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.

  12. 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

  13. Osteogenesis and Morphology of the Peri-Implant Bone Facing Dental Implants

    Directory of Open Access Journals (Sweden)

    Marco Franchi

    2004-01-01

    Full Text Available This study investigated the influence of different implant surfaces on peri-implant osteogenesis and implant face morphology of peri-implant tissues during the early (2 weeks and complete healing period (3 months. Thirty endosseous titanium implants (conic screws with differently treated surfaces (smooth titanium = SS, titanium plasma sprayed = TPS, sand-blasted zirconium oxide = Zr-SLA were implanted in femur and tibiae diaphyses of two mongrel sheep. Histological sections of the implants and surrounding tissues obtained by sawing and grinding techniques were observed under light microscopy (LM. The peri-implant tissues of other samples were mechanically detached from the corresponding implants to be processed for SEM observation. Two weeks after implantation, we observed osteogenesis (new bone trabeculae around all implant surfaces only where a gap was present at the host bone-metal interface. No evident bone deposition was detectable where threads of the screws were in direct contact with the compact host bone. Distance osteogenesis predominated in SS implants, while around rough surfaces (TPS and Zr-SLA, both distance and contact osteogenesis were present. At SEM analysis 2 weeks after implantation, the implant face of SS peri-implant tissue showed few, thin, newly formed, bone trabeculae immersed in large, loose, marrow tissue with blood vessels. Around the TPS screws, the implant face of the peri-implant tissue was rather irregular because of the rougher metal surface. Zr-SLA screws showed more numerous, newly formed bone trabeculae crossing marrow spaces and also needle-like crystals in bone nodules indicating an active mineralising process. After 3 months, all the screws appeared osseointegrated, being almost completely covered by a compact, mature, newly formed bone. However, some marrow spaces rich in blood vessels and undifferentiated cells were in contact with the metal surface. By SEM analysis, the implant face of the peri-implant

  14. Evaluation of MRI issues for an access port with a radiofrequency identification (RFID) tag.

    Science.gov (United States)

    Titterington, Blake; Shellock, Frank G

    2013-10-01

    A medical implant that contains metal, such as an RFID tag, must undergo proper MRI testing to ensure patient safety and to determine that the function of the RFID tag is not compromised by exposure to MRI conditions. Therefore, the objective of this investigation was to assess MRI issues for a new access port that incorporates an RFID tag. Samples of the access port with an RFID tag (Medcomp Power Injectable Port with CertainID; Medcomp, Harleysville, PA) were evaluated using standard protocols to assess magnetic field interactions (translational attraction and torque; 3-T), MRI-related heating (3-T), artifacts (3-T), and functional changes associated with different MRI conditions (nine samples, exposed to different MRI conditions at 1.5-T and 3-T). Magnetic field interactions were not substantial and will pose no hazards to patients. MRI-related heating was minimal (highest temperature change, 1.7°C; background temperature rise, 1.6°C). Artifacts were moderate in size in relation to the device. Exposures to MRI conditions at 1.5-T and 3-T did not alter or damage the functional aspects of the RFID tag. Based on the findings of the test, this new access port with an RFID tag is acceptable (or, MR conditional, using current MRI labeling terminology) for patients undergoing MRI examinations at 1.5-T/64-MHz and 3-T/128-MHz. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. 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.