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Sample records for mri implants causing

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

    PubMed Central

    Busch, Martin HJ; Vollmann, Wolfgang; Grönemeyer, Dietrich HW

    2006-01-01

    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 investigations. The finite

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

    SciTech Connect

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

    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.

  3. Wrong detection of ventricular fibrillation in an implantable cardioverter defibrillator caused by the movement near the MRI scanner bore.

    PubMed

    Mattei, Eugenio; Censi, Federica; Triventi, Michele; Mancini, Matteo; Napolitano, Antonio; Genovese, Elisabetta; Cannata, Vittorio; Falsaperla, Rosaria; Calcagnini, Giovanni

    2015-01-01

    The static magnetic field generated by MRI systems is highly non-homogenous and rapidly decreases when moving away from the bore of the scanner. Consequently, the movement around the MRI scanner is equivalent to an exposure to a time-varying magnetic field at very low frequency (few Hz). For patients with an implanted cardiac stimulators, such as an implantable cardioverter/defibrillator (ICD), the movements inside the MRI environment may thus induce voltages on the loop formed by the leads of the device, with the potential to affect the behavior of the stimulator. In particular, the ICD's detection algorithms may be affected by the induced voltage and may cause inappropriate sensing, arrhythmia detections, and eventually inappropriate ICD therapy.We performed in-vitro measurements on a saline-filled humanshaped phantom (male, 170 cm height), equipped with an MRconditional ICD able to transmit in real-time the detected cardiac activity (electrograms). A biventricular implant was reproduced and the ICD was programmed in standard operating conditions, but with the shock delivery disabled. The electrograms recorded in the atrial, left and right ventricle channels were monitored during rotational movements along the vertical axis, in close proximity of the bore. The phantom was also equipped with an accelerometer and a magnetic field probe to measure the angular velocity and the magnetic field variation during the experiment. Pacing inhibition, inappropriate detection of tachyarrhythmias and of ventricular fibrillation were observed. Pacing inhibition began at an angular velocity of about 7 rad/s, (dB/dt of about 2 T/s). Inappropriate detection of ventricular fibrillation occurred at about 8 rad/s (dB/dt of about 3 T/s). These findings highlight the need for a specific risk assessment of workers with MR-conditional ICDs, which takes into account also effects that are generally not considered relevant for patients, such as the movement around the scanner bore.

  4. rf enhancement and shielding in MRI caused by conductive implants: dependence on electrical parameters for a tube model.

    PubMed

    Graf, Hansjörg; Steidle, Günter; Lauer, Ulrike A; Schick, Fritz

    2005-02-01

    Radio frequency (rf) eddy-currents induced in implants made of conductive material might cause significant image artifacts in magnetic resonance imaging (MRI) such as shielding of the lumen of vascular stents. rf alteration near metal parts was assessed theoretically in the approximation of alternating current electrodynamics: The implant was modeled as tube with diameter d(o), resistance R, and reactance Y, constituting the secondary winding of a transformer. The transmitter coil of the scanner acted as primary winding and generated the linearly polarized rf field B1,app. Tube axis was assumed parallel to B1,app. The results of the calculations were as follows: Ninety percent of the applied rf-field amplitude is reached in the lumen at a ratio chi=R/Y approximately 2. A rapid drop occurs with the reduction of chi, whereas a further increase of chi causes only a small effect. With chi approximately 1/d(o)(Y approximately d2o,R approximately d(o)), conditions for rf alteration clearly depend on the diameter of the tube. Inside tubes with smaller diameter, rf shielding is less pronounced. rf alteration increases in good approximation with the square root of the strength of the static field B0. The following experiments were carried out: Tubes of similar diameter (d(o) approximately 8 mm) made of material of different conductivity (Cu, Nitinol, carbon fiber reinforced plastic with three different fiber structures) were examined at B0=0.2 and 1.5 T in water phantoms. Tube axis was aligned perpendicular to B0 and spin-echo technique was applied. Local rf enhancement near the outer surface of the metal tubes was detected applying manual reduction of the transmitter amplitude. Shielding inside a carbon fiber tube with d(o) approximately 8 mm and inside a smaller tube with d(o)=3.3 mm was compared. Both tubes showed the same wall structure and thickness (d(w)=0.4 mm). All measurements confirmed the theoretical results. Consequences for the construction of vascular stents

  5. [How do metallic middle ear implants behave in the MRI?].

    PubMed

    Kwok, P; Waldeck, A; Strutz, J

    2003-01-01

    Magnetic resonance imaging (MRI) has gained in frequency and importance as a diagnostic procedure. In respect to the close anatomical relationship in the temporal bone it is necessary to know whether it is hazardous to patients with metallic middle ear implants regarding displacement and rise in temperature. For the MR image quality artefacts caused by metallic prostheses should be low. Four different stapes prostheses made from titanium, gold, teflon/platinum and teflon/steel, a titanium total ossicular reconstruction prosthesis (TORP) and two ventilation tubes (made from titanium and gold) were tested in a 1.5 Tesla MRI machine regarding their displacement. All objects were first placed in a petri dish, then suspended from a thread and finally immersed in a dish filled with Gadolinium. Temperature changes of the implants were recorded by a pyrometer. None of the implants moved when they were placed in the petri dish or suspended from the thread. On the water surface the teflon/platinum and the teflon/steel pistons adjusted their direction with their axis longitudinally to the MRI scanner opening and the teflon/steel piston floated towards the MRI-machine when put close enough to the scanner opening. No rise in temperature was recorded. All implants showed as little artefacts that would still make an evaluation of the surrounding tissue possible. Patients with any of the metallic middle ear implants that were examined in this study may undergo MRI-investigations without significant adverse effects.

  6. Automated extraction of subdural electrode grid from post-implant MRI scans for epilepsy surgery

    NASA Astrophysics Data System (ADS)

    Pozdin, Maksym A.; Skrinjar, Oskar

    2005-04-01

    This paper presents an automated algorithm for extraction of Subdural Electrode Grid (SEG) from post-implant MRI scans for epilepsy surgery. Post-implant MRI scans are corrupted by the image artifacts caused by implanted electrodes. The artifacts appear as dark spherical voids and given that the cerebrospinal fluid is also dark in T1-weigthed MRI scans, it is a difficult and time-consuming task to manually locate SEG position relative to brain structures of interest. The proposed algorithm reliably and accurately extracts SEG from post-implant MRI scan, i.e. finds its shape and position relative to brain structures of interest. The algorithm was validated against manually determined electrode locations, and the average error was 1.6mm for the three tested subjects.

  7. Central nervous system MRI and cardiac implantable electronic devices.

    PubMed

    Cadieu, Romain; Peron, Marilyne; Le Ven, Florent; Kerdraon, Sébastien; Boutet, Claire; Mansourati, Jacques; Ben Salem, Douraied

    2017-02-01

    As the population ages and indications for MRI increase, it is estimated that 50 to 75% of patients with a cardiac implantable electronic device (CIED) - pacemaker (PM) or implanted cardiac defibrillator (ICD) - will need an MRI during their CIED's lifetime. Three categories of materials are defined: MRI compatible, MRI non-compatible, and MRI conditional. MRI compatible CIEDs without electrodes have been developed, but do not allow battery changes, so that they are exclusively indicated for patients whose life expectancy is less than that of the battery (6-7years). For MRI conditional CIEDs, all manufacturers publish restrictions. These restrictions can relate to the patient (size, position in the MRI, body temperature), the MRI parameters (magnetic field), or the examination in itself (gradients, specific absorption rate, duration, isocenter). The neuroradiologist can expect to be confronted with the issue of MRI in patients with a CIED. The purpose of this review is to provide them with updated information on MRI and CIEDs.

  8. MRI interactions of a fully implantable pressure monitoring device.

    PubMed

    Stehlin, Ellyce F; McCormick, Daniel; Malpas, Simon C; Pontré, Beau P; Heppner, Peter A; Budgett, David M

    2015-11-01

    To investigate the potential patient risk and interactions between a prototype implantable pressure monitoring device and a 3T clinical magnetic resonance imaging (MRI) machine to guide device design towards MR Conditional safety approval. The pressure monitor device contained a catheter-mounted piezo-resistive pressure sensor, rechargeable battery, wireless communication system, and inductive pickup coil. Standard testing methods were used to guide experiments to investigate static field induced force and torque, radiofrequency (RF)-induced heating, image artifacts, and the MR's effect on device function. The specific clinical application of intracranial pressure monitoring was considered. RF-induced heating experiments were supported by numerical modeling of the RF body coil, the device, and experimental phantom. Sensing catheter lead length and configuration was an important component of the device design. A short 150 mm length catheter produced a heating effect of less than 2°C and a long 420 mm length catheter caused heating of 7.2°C. Static magnetic field interactions were below standard safety risk levels and the MR did not interfere with device function; however, artifacts have the potential to interfere with image quality. Investigation of MR interactions at the prototype stage provides useful implantable device design guidance and confidence that an implantable pressure monitor may be able to achieve MR Conditional safety approval. © 2015 Wiley Periodicals, Inc.

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

    PubMed

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

    2014-07-01

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

  10. Safety of active implantable devices during MRI examinations: a finite element analysis of an implantable pump.

    PubMed

    Büchler, Philippe; Simon, Anne; Burger, Jürgen; Ginggen, Alec; Crivelli, Rocco; Tardy, Yanik; Luechinger, Roger; Olsen, Sigbjørn

    2007-04-01

    The goal of this study was to propose a general numerical analysis methodology to evaluate the magnetic resonance imaging (MRI)-safety of active implants. Numerical models based on the finite element (FE) technique were used to estimate if the normal operation of an active device was altered during MRI imaging. An active implanted pump was chosen to illustrate the method. A set of controlled experiments were proposed and performed to validate the numerical model. The calculated induced voltages in the important electronic components of the device showed dependence with the MRI field strength. For the MRI radiofrequency fields, significant induced voltages of up to 20 V were calculated for a 0.3T field-strength MRI. For the 1.5 and 3.0OT MRIs, the calculated voltages were insignificant. On the other hand, induced voltages up to 11 V were calculated in the critical electronic components for the 3.0T MRI due to the gradient fields. Values obtained in this work reflect to the worst case situation which is virtually impossible to achieve in normal scanning situations. Since the calculated voltages may be removed by appropriate protection circuits, no critical problems affecting the normal operation of the pump were identified. This study showed that the proposed methodology helps the identification of the possible incompatibilities between active implants and MR imaging, and can be used to aid the design of critical electronic systems to ensure MRI-safety.

  11. Safety of MRI with metallic middle ear implants.

    PubMed

    Tohme, Souheil M; Karkas, Alexandre A; Romanos, Bassam H

    2003-01-01

    Investigation of the effects of magnetic resonance fields on commonly used metallic middle ear implants. Nine middle ear prostheses (seven containing stainless steel and two made of pure gold used as control) were tested in vitro and one stainless steel stapedectomy prosthesis was tested on a cadaveric temporal bone. Each metallic prosthesis was placed in an empty Petri dish and introduced into a 1.5-tesla (T) magnetic resonance imaging (MRI) unit. Most of the prostheses were then placed in a water-filled Petri dish and reintroduced into the MRI unit. Eventual in vitro displacement was assessed visually by two means. In situ testing was done by implanting a piston in a cadaveric temporal bone and performing MR sequences ; any possible displacement was then assessed by CT scan and under microscopic vision. None of the prostheses was displaced in the empty Petri dish. However, while in the water-filled Petri dish, three of these moved with the flux. The implanted piston in the temporal bone did not move. The displacement of three of the prostheses in water is not relevant in real clinical situations. MRI can thus be considered safe in usual clinical settings, as far as our studied implants are concerned.

  12. Cranio-orbital reconstruction: safety and image quality of metallic implants on CT and MRI scanning.

    PubMed

    Sullivan, P K; Smith, J F; Rozzelle, A A

    1994-10-01

    A study was undertaken to evaluate the safety of magnetic resonance imaging (MRI) of metallic implants used in cranio-orbital reconstruction (stainless steel wire and titanium and Vitallium plates) and also to compare the degree of artifact created on computed tomographic (CT) scanning and MRI by each material. Samples of each material were tested for deflection (movement) in a 1.5-T MRI field and for temperature change under conditions simulating a clinical MRI scan. None of the materials exhibited any deflection, and none exhibited any significant temperature change compared with water. Standardized bars of each material and commonly used, commercially available titanium and Vitallium implants (plates, mesh) were evaluated for artifact. On blinded evaluation by three radiologists and on quantitative computer analysis of the CT images, the stainless steel produced the most artifact on both CT scan and MRI, followed by the Vitallium, with the least artifact caused by titanium. All the titanium images were felt to be acceptable to detect orbital pathology, while only the images with the thinnest Vitallium (micromesh) implant were acceptable.

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

    PubMed Central

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

    2014-01-01

    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 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. PMID:25114595

  14. Use of brain MRI after deep brain stimulation hardware implantation.

    PubMed

    Nazzaro, Jules M; Lyons, Kelly E; Wetzel, Louis H; Pahwa, Rajesh

    2010-03-01

    The objective of this study was to examine the experience with and safety of brain 1.5 Tesla (T) magnetic resonance imaging (MRI) in deep brain stimulation (DBS) patients. This was a retrospective review of brain MRI scanning performed on DBS patients at the University of Kansas Medical Center between January 1995 and December 2007. A total of 249 DBS patients underwent 445 brain 1.5 T MRI scan sessions encompassing 1,092 individual scans using a transmit-receive head coil, representing the cumulative scanning of 1,649 DBS leads. Patients with complete implanted DBS systems as well as those with externalized leads underwent brain imaging. For the majority of scans, specific absorption rates localized to the head (SAR(H)) were estimated and in all cases SAR(H) were higher than that specified in the present product labeling. There were no clinical or hardware related adverse events secondary to brain MRI scanning. Our data should not be extrapolated to encourage MRI scanning beyond the present labeling. Rather, our data may contribute to further defining safe MRI scanning parameters that might ultimately be adopted in future product labeling as more centers report in detail their experiences.

  15. [MRI investigations in patients with problems due to metal-on-metal implants].

    PubMed

    Parsons, T M; Satchithananda, K; Berbe, R; Siddiqui, I A; Robinson, E; Hart, A J; Hart, A

    2013-08-01

    Until recently, metal-on-metal (MoM) hip implants were commonly used for joint replacement and resurfacings. Their use has rapidly declined following reports of Frühversagen and soft tissue disease caused by the release of metal debris from the prosthesis. Detection of these soft tissue lesions has proven difficult using conventional imaging techniques and blood metal ion tests. Current guidelines recommend the use of imaging modalities including metal artefact reduction sequence (MARS) magnetic resonance imaging (MRI), computed tomography and ultrasound but provide little indication which is best. MARS significantly reduces the susceptibility artefact induced by the presence of metal objects, thereby producing diagnostic quality images that can be shared with other physicians and compared over time. The clinical interpretation of MRI findings of solid pseudotumours and severe muscle atrophy is straightforward: revision is usually recommended. However, the most common MRI findings are of a cystic pseudotumour and minor muscle wasting. In these cases decision-making is difficult and we currently use multi-disciplinary and multi-colleague based meetings to make decisions regarding patient management. This article presents a comparison of imaging modalities and an update on the interpretation of MARS MRI for the investigation of patients with MoM hip implants.The English full-text version of this article is available at Springer Link (under "Supplemental").

  16. [Enucleation: causes of extrusion of orbital implants (author's transl)].

    PubMed

    Hanselmayer, H; Ritzinger, I

    1978-02-01

    The frequency and the causes of extrusion of orbital implants have been investigated. Of the 294 patients in which enucleation was done, in 17 cases (5.8%) extrusion of the first implant developed; in 9 cases with second or third implantations another 5 implants have been extruded. The extrusion of implants is caused mainly by the operative technique and only rarely by intolerance reactions. For a reliable healing exact sutures of the muscles and also exact closure of the implant with plenty of covering tissue is important.

  17. Implantable cardioverter defibrillator pocket infection caused by Klebsiella pneumonia.

    PubMed

    Ertas, F; Acet, H; Kaya, H; Kayan, F; Soydinc, S

    2012-09-01

    Like any other foreign bodies, implanted cardiac devices can become infected. Staphylococcus aureus and coagulase-negative Staphilococci are the most common causes of infections of pacemaker and defibrillator systems. In this case an implantable cardioverter defibrillator pocket infection caused by an extremely rare microorganism, Klebsiella pneumonia, is presented.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Altered sensation caused by peri-implantitis: a case report.

    PubMed

    Kim, Jong-Eun; Shim, Ji-Suk; Huh, Jung-Bo; Rim, Jae-Suk; Lee, Jeong-Yol; Shin, Sang-Wan

    2013-07-01

    Frequently reported is a case wherein a lesion caused by periodontitis or periapical lesion in a natural tooth enlarged, invaded the inferior alveolar nerve canal, and induced paresthesia. Cases wherein paresthesia occurred because of peri-implantitis have been rarely reported. The patient in this case report had experienced transient paresthesia after implant placement and recovered normal sensation 3 months later. Thirteen years later, this patient visited the authors' hospital with paresthesia in the same region because the peri-implantitis progressed to the apex of the implant. One week after removal of the implant, sense recovery and pain relief started, and 15 days after removal, the paresthesia and pain completely disappeared. For patients who experience transient paresthesia and recovery owing to nerve damage caused by the placement of an implant in the mandibular molar or premolar area, or in patients in whom the implant is close to the inferior alveolar nerve canal or the mental nerve, the spread of inflammation caused by peri-implantitis can induce paresthesia.

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

    PubMed

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2015-09-21

    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 B(1)(+) 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.

  1. Transapical Perceval S Sutureless Aortic Valve Implantation under MRI guidance: Acute and Short-term Results

    PubMed Central

    Horvath, Keith A.; Mazilu, Dumitru; Cai, Junfeng; Kindzelski, Bogdan; Li, Ming

    2014-01-01

    Objectives Despite the increasing success and applicability of TAVR, two critical issues remain unanswered; the durability of the valves and the ideal imaging to aid implantation. This study was designed to investigate the transapical implantation of a device of known durability using rtMRI guidance. Methods The Sorin Perceval S valve employs a self-expanding nitinol stent and is amenable to transapical delivery. A 1.5T MRI was used to identify the anatomic landmarks in 60kg Yucatan swine. Prostheses were loaded into an MRI compatible delivery device with an active guidewire to enhance visualization. A series of acute feasibility experiments were conducted (n=10). Additional animals (n=6) were allowed to survive and had follow-up MRI scans and echocardiography at 90-days postoperatively. Postmortem gross examination was then performed. Results The Perceval S valve is MRI compatible and creates no significant MRI artifacts. The three commissural struts were visible on short axis view, therefore coronary ostia obstruction was easily avoided. The average implantation time was 65 seconds. Final results demonstrated stability of the implants with preservation of myocardial perfusion and function over 90 days: EF was 48±15%; peak gradient was 17.3±11.3 mm Hg; mean gradient was 9.8±7.2 mm Hg. Mild aortic regurgitation was seen in 4 cases, trace in 1 case, and severe central jet in 1 case. Prosthesis positioning was evaluated during gross examination. Conclusions We demonstrated that the Perceval S valve can be safely and expeditiously implanted through a transapical approach under rtMRI guidance. Post-implantation results showed a well-functioning prosthesis with minimal regurgitation and stability over time. PMID:25466854

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

    PubMed Central

    Bladowska, Joanna; Bednarek-Tupikowska, Grażyna; Sokolska, Violetta; Badowski, Roman; Moroń, Krzysztof; Bonicki, Wiesław; Sąsiadek, Marek

    2010-01-01

    Summary 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 1.5T 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. PMID

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

    NASA Astrophysics Data System (ADS)

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2015-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Woo, Taeseong; Kim, Dongmin; Someya, Takao; Sekino, Masaki

    2017-05-01

    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.

  5. MRI during cochlear implant assessment: Should we image the whole brain?

    PubMed

    Proctor, Robin D; Gawne-Cain, Mary L; Eyles, Julie; Mitchell, Timothy E; Batty, Vincent B

    2013-01-01

    Magnetic resonance imaging (MRI) is a standard part of a cochlear implant assessment in most centres. While there is ample literature on the temporal bone-specific imaging that is required, the role of whole brain imaging has not been as fully studied. We present the first report of the incidence of associated brain abnormalities in the whole cochlear implant population, including adults and consider their significance. We retrospectively reviewed 51 (12 adults and 39 children) sequential cases since we added whole brain MRI sequences to our cochlear implant assessment protocol. We reviewed the scans for abnormalities of the cochlea and cochlear nerve and a neuroradiologist reviewed the images of the whole brain sequences for further abnormalities. We identified abnormalities on the whole brain sequences in 21 (41%) of these patients, 5 of 12 adults (42%) and 16 of 39 children (41%). Thirty-six (71%) patients subsequently had at least one implant inserted, 13 with abnormalities on whole brain MRI (36%) and 23 without. Of the 15 patients who did not undergo subsequent implantation, 8 had positive findings on their whole brain MRI sequence (53%). There was no statistical difference in the probability of finding an abnormality on the whole brain MRI between those who did and those who did not go on to have an implant (P = 0.35). There were abnormalities within the inner ear in five patients. The abnormalities detected on the whole brain images are heterogenous and of wide ranging clinical significance ranging from truly incidental findings to abnormalities that are so severe that they may predict a very poor prognosis such that an implant may contribute little.

  6. Magnet removal and reinsertion in a cochlear implant recipient undergoing brain MRI.

    PubMed

    Migirov, Lela; Wolf, Michael

    2013-01-01

    Recent advances in cochlear implants (CIs) and in magnetic resonance imaging (MRI) techniques have led to increasing numbers of implanted patients who have undergone brain MRIs for various reasons. This paper first describes the surgical procedure for removing the magnet before an MRI and its subsequent reinsertion immediately afterwards in a CI recipient. After the administration of local anesthesia, the magnet was removed by a surgical incision made along the posterior margin of the receiver-stimulator. The flap was elevated and the capsule over the implant was incised. The magnet was removed, maintained under sterile conditions and reinserted immediately after the completion of the 1.5-Tesla MRI. The patient was able to wear her device immediately after surgery. Large CI-associated artifacts were observed on the MRIs irrespective of sequences. The function of the device was not altered by either the MRI or the surgical procedure. The proposed surgical incision that follows the posterior margins of the receiver-stimulator allows the wearing of the device immediately after the surgical procedure. An MRI has limited diagnostic value for lesions located on the implanted side due to unavoidable artifacts, even after the magnet has been removed. Copyright © 2013 S. Karger AG, Basel.

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

    PubMed Central

    Iacono, Maria Ida; Makris, Nikos; Mainardi, Luca; Angelone, Leonardo M.; Bonmassar, Giorgio

    2013-01-01

    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. PMID:23956789

  8. MRI brain abnormalities in cochlear implant candidates: how common and how important are they?

    PubMed

    Jonas, N E; Ahmed, J; Grainger, J; Jephson, C G; Wyatt, M E; Hartley, B E; Saunders, Dawn; Cochrane, L A

    2012-07-01

    To investigate the incidence of abnormal findings on brain MRI in paediatric cochlear implantation candidates. Retrospective review of brain MRI scans of cochlear implant patients between 2000 and 2009 who underwent MRI brain as part of their pre-operative work-up. MRI scans of 162 patients were reviewed (76 female patients and 86 male patients). The mean age at time of MRI scan was 3 years 8 months. Abnormalities were detected/ reported in 49 patients (30%). The total number of abnormalities detected was 51 (two patients had two separate abnormalities each). Of the abnormalities 82% could be related to known pre-existing conditions. 18% of the abnormalities were incidental/unexpected. Incidental/unexpected abnormalities were found in 9 patients (6%). Four of the patients with incidental abnormalities required referral and further investigations (2.5%). The most common abnormality detected was white matter changes (70%). All the white matter changes were related to pre-existing known medical conditions. At our institution abnormalities detected by pre-operative brain MRI scans on cochlear implant candidates are common (30%). The majority of abnormalities are related to known pre-existing medical conditions. Incidental findings are rare (4%) and approximately half of them required further investigation or referral. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  9. MRI induced torque and demagnetization in retention magnets for a bone conduction implant.

    PubMed

    Jansson, Karl-Johan Fredén; Håkansson, Bo; Reinfeldt, Sabine; Taghavi, Hamidreza; Eeg-Olofsson, Måns

    2014-06-01

    Performing magnetic resonance imaging (MRI) examinations in patients who use implantable medical devices involve safety risks both for the patient and the implant. Hearing implants often use two permanent magnets, one implanted and one external, for the retention of the external transmitter coil to the implanted receiver coil to achieve an optimal signal transmission. The implanted magnet is subjected to both demagnetization and torque, magnetically induced by the MRI scanner. In this paper, demagnetization and a comparison between measured and simulated induced torque is studied for the retention magnet used in a bone conduction implant (BCI) system. The torque was measured and simulated in a uniform static magnetic field of 1.5 T. The magnetic field was generated by a dipole electromagnet and permanent magnets with two different types of coercive fields were tested. Demagnetization and maximum torque for the high coercive field magnets was 7.7% ± 2.5% and 0.20 ± 0.01 Nm, respectively and 71.4% ± 19.1% and 0.18 ± 0.01 Nm for the low coercive field magnets, respectively. The simulated maximum torque was 0.34 Nm, deviating from the measured torque in terms of amplitude, mainly related to an insufficient magnet model. The BCI implant with high coercive field magnets is believed to be magnetic resonance (MR) conditional up to 1.5 T if a compression band is used around the skull to fix the implant. This is not approved and requires further investigations, and if removal of the implant is needed, the surgical operation is expected to be simple.

  10. An implanted 8-channel array coil for high-resolution macaque MRI at 3T.

    PubMed

    Janssens, T; Keil, B; Farivar, R; McNab, J A; Polimeni, J R; Gerits, A; Arsenault, J T; Wald, L L; Vanduffel, W

    2012-09-01

    An 8-channel receive coil array was constructed and implanted adjacent to the skull in a male rhesus monkey in order to improve the sensitivity of (functional) brain imaging. The permanent implant was part of an acrylic headpost assembly and only the coil element loop wires were implanted. The tuning, matching, and preamplifier circuitry was connected via a removable external assembly. Signal-to-noise ratio (SNR) and noise amplification for parallel imaging were compared to single-, 4-, and 8-channel external receive-only coils routinely used for macaque fMRI. In vivo measurements showed significantly improved SNR within the brain for the implanted versus the external coils. Within a region-of-interest covering the cerebral cortex, we observed a 5.4-, 3.6-fold, and 3.4-fold increase in SNR compared to the external single-, 4-, and 8-channel coils, respectively. In the center of the brain, the implanted array maintained a 2.4×, 2.5×, and 2.1× higher SNR, respectively compared to the external coils. The array performance was evaluated for anatomical, diffusion tensor and functional brain imaging. This study suggests that a stable implanted phased-array coil can be used in macaque MRI to substantially increase the spatial resolution for anatomical, diffusion tensor, and functional imaging. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. An implanted 8-channel array coil for high-resolution macaque MRI at 3T

    PubMed Central

    Janssens, T.; Keil, B.; Farivar, R.; McNab, J.A.; Polimeni, J. R.; Gerits, A.; Arsenault, J.T.; Wald, L. L.; Vanduffel, W.

    2012-01-01

    An 8-channel receive coil array was constructed and implanted adjacent to the skull in a male rhesus monkey in order to improve the sensitivity of (functional) brain imaging. The permanent implant was part of an acrylic headpost assembly and only the coil element loop wires were implanted. The tuning, matching, and preamplifier circuitry was connected via a removable external assembly. Signal-to-noise ratio (SNR) and noise amplification for parallel imaging were compared to a single-, 4-, and 8-channel external receive-only coil routinely used for macaque fMRI. In vivo measurements showed significantly improved SNR within the brain for the implanted versus the external coils. Within a region-of-interest covering the cerebral cortex, we observed a 5.4-, 3.6-fold, and 3.4-fold increase in SNR compared to the external single-, 4-, and 8-channel coil, respectively. In the center of the brain, the implanted array maintained a 2.4×, 2.5×, and 2.1× higher SNR, respectively compared to the external coils. The array performance was evaluated for anatomical, diffusion tensor and functional brain imaging. This study suggests that a stable implanted phased-array coil can be used in macaque MRI to substantially increase the spatial resolution for anatomical, diffusion tensor, and functional imaging. PMID:22609793

  12. [Botulinum toxin to treat sweat caused sequelae in patients with hearing aids, active middle ear implants and cochlear implants].

    PubMed

    Laskawi, R; Winterhoff, J; Blum, J; Matthias, C

    2012-11-01

    The production of sweat in the temporal skin region may be a serious problem for patients with hearing aids, active middle ear implants or cochlear implants. We report on two patients suffering from a loss of function of their hearing aid and a reduction of the "wear comfort" of an active middle ear implant. The patients underwent intracutaneous botulinum toxin (BTX) treatment of the temporal skin region. In both patients a distinct improvement of their complaints occurred, enabling them to use their hearing aids and active middle ear implants continuously. BTX injections are suited to improve sweat-caused complaints in patients with hearing aids, active middle ear implants and cochlear implants.

  13. Allergic contact dermatitis caused by titanium screws and dental implants.

    PubMed

    Hosoki, Maki; Nishigawa, Keisuke; Miyamoto, Youji; Ohe, Go; Matsuka, Yoshizo

    2016-07-01

    Titanium has been considered to be a non-allergenic material. However, several studies have reported cases of metal allergy caused by titanium-containing materials. We describe a 69-year-old male for whom significant pathologic findings around dental implants had never been observed. He exhibited allergic symptoms (eczema) after orthopedic surgery. The titanium screws used in the orthopedic surgery that he underwent were removed 1 year later, but the eczema remained. After removal of dental implants, the eczema disappeared completely. Titanium is used not only for medical applications such as plastic surgery and/or dental implants, but also for paints, white pigments, photocatalysts, and various types of everyday goods. Most of the usage of titanium is in the form of titanium dioxide. This rapid expansion of titanium-containing products has increased percutaneous and permucosal exposure of titanium to the population. In general, allergic risk of titanium material is smaller than that of other metal materials. However, we suggest that pre-implant patients should be asked about a history of hypersensitivity reactions to metals, and patch testing should be recommended to patients who have experienced such reactions. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. Cochlear implantation for severe sensorineural hearing loss caused by lightning.

    PubMed

    Myung, Nam-Suk; Lee, Il-Woo; Goh, Eui-Kyung; Kong, Soo-Keun

    2012-01-01

    Lightning strike can produce an array of clinical symptoms and injuries. It may damage multiple organs and cause auditory injuries ranging from transient hearing loss and vertigo to complete disruption of the auditory system. Tympanic-membrane rupture is relatively common in patients with lightning injury. The exact pathogenetic mechanisms of auditory lesions in lightning survivors have not been fully elucidated. We report the case of a 45-year-old woman with bilateral profound sensorineural hearing loss caused by a lightning strike, who was successfully rehabilitated after a cochlear implantation.

  15. Using bimodal MRI/fluorescence imaging to identify host angiogenic response to implants

    PubMed Central

    Berdichevski, Alexandra; Simaan Yameen, Haneen; Dafni, Hagit; Neeman, Michal; Seliktar, Dror

    2015-01-01

    Therapies that promote angiogenesis have been successfully applied using various combinations of proangiogenic factors together with a biodegradable delivery vehicle. In this study we used bimodal noninvasive monitoring to show that the host response to a proangiogenic biomaterial can be drastically affected by the mode of implantation and the surface area-to-volume ratio of the implant material. Fluorescence/MRI probes were covalently conjugated to VEGF-bearing biodegradable PEG-fibrinogen hydrogel implants and used to document the in vivo degradation and liberation of bioactive constituents in an s.c. rat implantation model. The hydrogel biodegradation and angiogenic host response with three types of VEGF-bearing implant configurations were compared: preformed cylindrical plugs, preformed injectable microbeads, and hydrogel precursor, injected and polymerized in situ. Although all three were made with identical amounts of precursor constituents, the MRI data revealed that in situ polymerized hydrogels were fully degraded within 2 wk; microbead degradation was more moderate, and plugs degraded significantly more slowly than the other configurations. The presence of hydrogel degradation products containing the fluorescent label in the surrounding tissues revealed a distinct biphasic release profile for each type of implant configuration. The purported in vivo VEGF release profile from the microbeads resulted in highly vascularized s.c. tissue containing up to 16-fold more capillaries in comparison with controls. These findings demonstrate that the configuration of an implant can play an important role not only in the degradation and resorption properties of the materials, but also in consequent host angiogenic response. PMID:25825771

  16. MRI of mediastinal parathyroid cystic adenoma causing hyperparathyroidism

    SciTech Connect

    Soler, R.; Bargiela, A.; Cordido, F.; Aguilera, C.; Argueeso, R.; Cao, I.

    1996-01-01

    Primary hyperparathyroidism is a common disorder that results from an increased secretion of parathyroid hormone, most often due to a solitary and solid parathyroid adenoma usually found in the inferior group of parathyroid glands. Parathyroid gland is ectopic in approximately 10 to 20% of the cases, and the retrosternal and prevascular mediastinum is the most common location. Most mediastinal parathyroid adenomas are solid and <3 cm, but mediastinal parathyroid cysts are very uncommon and rarely cause hyperparathyroidism. We know of 18 cases of mediastinal parathyroid cysts that have been previously reported and only four of them presented with hyperparathyroidism. We report an unusual case of hyperparathyroidism due to a large cystic parathyroid adenoma located in the anterior mediastinum diagnosed by MRI. 2 refs., 1 fig.

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

    PubMed

    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.

  18. Ensuring Safety of Implanted Devices under MRI using Reversed RF Polarization

    PubMed Central

    Overall, William R.; Pauly, John M.; Stang, Pascal P.; Scott, Greig C.

    2011-01-01

    Patients with long-wire medical implants are currently prevented from undergoing MRI scans due to the risk of RF heating. We have developed a simple technique for determining the heating potential for these implants using reversed RF polarization. This technique could be used on a patient-to-patient basis as a part of the standard pre-scan procedure to ensure that the subject’s device does not pose a heating risk. By using reversed quadrature polarization, the MR scan can be sensitized exclusively to the potentially dangerous currents in the device. Here, we derive the physical principles governing the technique and explore the primary sources of inaccuracy. These principles are verified through finite-difference simulations and through phantom scans of implant leads. These studies demonstrate the potential of the technique for sensitively detecting potentially dangerous coupling conditions before they can do harm. PMID:20593374

  19. Feasibility of Structural and Functional MRI Acquisition with Unpowered Implants in Argus II Retinal Prosthesis Patients: A Case Study

    PubMed Central

    Cunningham, Samantha I.; Shi, Yonggang; Weiland, James D.; Falabella, Paulo; Olmos de Koo, Lisa C.; Zacks, David N.; Tjan, Bosco S.

    2015-01-01

    Purpose Magnetic resonance imaging (MRI) can measure the effects of vision loss and recovery on brain function and structure. In this case study, we sought to determine the feasibility of acquiring anatomical and functional MRI data in recipients of the Argus II epiretinal prosthesis system. Methods Following successful implantation with the Argus II device, two retinitis pigmentosa (RP) patients completed MRI scans with their implant unpowered to measure primary visual cortex (V1) functional responses to a tactile task, whole-brain morphometry, V1 cortical thickness, and diffusion properties of the optic tract and optic radiation. Measurements in the subjects with the Argus II implant were compared to measurements obtained previously from RP patients and sighted individuals. Results The presence of the Argus II implant resulted in artifacts that were localized around the patient's implanted eye and did not extend into cortical regions or white matter tracts associated with the visual system. Structural data on V1 cortical thickness and the retinofugal tract obtained from the two Argus II subjects fell within the ranges of sighted and RP groups. When compared to the RP and sighted subjects, Argus II patients' tactile-evoked cross-modal functional MRI (fMRI) blood oxygen level-dependent (BOLD) responses in V1 also fell within the range of either sighted or RP groups, apparently depending on time since implantation. Conclusions This study demonstrates that successful acquisition and quantification of structural and functional MR images are feasible in the presence of the inactive implant and provides preliminary information on functional changes in the brain that may follow sight restoration treatments. Transitional Relevance Successful MRI and fMRI acquisition in Argus II recipients demonstrates feasibility of using MRI to study the effect of retinal prosthesis use on brain structure and function. PMID:26693097

  20. Feasibility of Structural and Functional MRI Acquisition with Unpowered Implants in Argus II Retinal Prosthesis Patients: A Case Study.

    PubMed

    Cunningham, Samantha I; Shi, Yonggang; Weiland, James D; Falabella, Paulo; Olmos de Koo, Lisa C; Zacks, David N; Tjan, Bosco S

    2015-12-01

    Magnetic resonance imaging (MRI) can measure the effects of vision loss and recovery on brain function and structure. In this case study, we sought to determine the feasibility of acquiring anatomical and functional MRI data in recipients of the Argus II epiretinal prosthesis system. Following successful implantation with the Argus II device, two retinitis pigmentosa (RP) patients completed MRI scans with their implant unpowered to measure primary visual cortex (V1) functional responses to a tactile task, whole-brain morphometry, V1 cortical thickness, and diffusion properties of the optic tract and optic radiation. Measurements in the subjects with the Argus II implant were compared to measurements obtained previously from RP patients and sighted individuals. The presence of the Argus II implant resulted in artifacts that were localized around the patient's implanted eye and did not extend into cortical regions or white matter tracts associated with the visual system. Structural data on V1 cortical thickness and the retinofugal tract obtained from the two Argus II subjects fell within the ranges of sighted and RP groups. When compared to the RP and sighted subjects, Argus II patients' tactile-evoked cross-modal functional MRI (fMRI) blood oxygen level-dependent (BOLD) responses in V1 also fell within the range of either sighted or RP groups, apparently depending on time since implantation. This study demonstrates that successful acquisition and quantification of structural and functional MR images are feasible in the presence of the inactive implant and provides preliminary information on functional changes in the brain that may follow sight restoration treatments. Successful MRI and fMRI acquisition in Argus II recipients demonstrates feasibility of using MRI to study the effect of retinal prosthesis use on brain structure and function.

  1. Tracking the Fate of Stem Cell Implants with Fluorine-19 MRI

    PubMed Central

    Gaudet, Jeffrey M.; Ribot, Emeline J.; Chen, Yuhua; Gilbert, Kyle M.; Foster, Paula J.

    2015-01-01

    Background In this study we used cellular magnetic resonance imaging (MRI) to detect mesenchymal stem cells (MSC) labeled with a Fluorine-19 (19F) agent. 19F-MRI offers unambiguous detection and in vivo quantification of labeled cells. Methods We investigated two common stem cell transplant mouse models: an immune competent, syngeneic transplant model and an immune compromised, xenograft transplant model. 19F labelled stem cells were implanted intramuscularly into the hindlimb of healthy mice. The transplant was then monitored for up to 17 days using 19F-MRI, after which the tissue was excised for fluorescence microscopy and immunohistochemisty. Results Immediately following transplantation, 19F-MRI quantification correlated very well with the expected cell number in both models. The 19F signal decreased over time in both models, with a more rapid decrease in the syngeneic model. By endpoint, only 2/7 syngeneic mice had any detectable 19F signal. In the xenograft model, all mice had detectable signal at endpoint. Fluorescence microscopy and immunohistochemistry were used to show that the 19F signal was related to the presence of bystander labeled macrophages, and not original MSC. Conclusions Our results show that 19F-MRI is an excellent tool for verifying the delivery of therapeutic cells early after transplantation. However, in certain circumstances the transfer of cellular label to other bystander cells may confuse interpretation of the long-term fate of the transplanted cells. PMID:25767871

  2. MRI Compatibility of Microfabricated Magnetic Actuators for Implantable Catheters: Mechanical Evaluations

    PubMed Central

    Lee, Hyowon; Xu, Qing; Ephrati, Jeremy; Bergsneider, Marvin; Judy, Jack W.

    2017-01-01

    Here we demonstrate the mechanical robustness of microfabricated torsional magnetic actuators in withstanding the magnetic fields produced by a 7 T MRI magnet. The static and dynamic mechanical characteristics of 30 devices were quantitatively measured before and after exposure to both uniform and non-uniform magnetic fields. The results show no statistically significant change in both the static and dynamic mechanical performance, which mitigates concerns about the mechanical compatibility of our devices with MRI scanners. Additional experiments are required to quantify the potential image-artifact size and radio-frequency-induced heating caused by the magnetic microactuators inside an MRI scanner. PMID:21096979

  3. Clinical routine implantation of a dual chamber pacemaker system designed for safe use with MRI: a single center, retrospective study on lead performance of Medtronic lead 5086MRI in comparison to Medtronic leads 4592-53 and 4092-58.

    PubMed

    Wollmann, C G; Thudt, K; Vock, P; Globits, S; Mayr, H

    2011-12-01

    We report our experience concerning lead performance and re-surgery rate of the Medtronic EnRhythm MRI SureScan pacemaker system (MRI-PM) in comparison to standard pacemaker (PM) systems and leads used at our institution. All patients (except patients with transvenous left ventricular leads) with successful PM implantation performed at our institution from 1 March 2009 to 31 October 2009 were included in this analysis and followed until mid January 2010. Lead measurements (assessed at implantation, prehospital discharge interrogation (1st follow-up) and at the first scheduled out-patient follow-up (2nd follow-up) were compared between atrial leads 4592-53 cm and 5086MRI-52 cm (lead group 1), and between ventricular leads 4092-58 cm and 5086MRI-52 cm/-58 cm (lead group 2), respectively. Causes for re-operations were assessed and compared between patients with standard dual chamber PM (DC-PM) and the MRI-PM. A total of 140 patients (VVI-PM: 36 patients; DDD-PM: 102 patients; biventricular PM: 1 patient) were successfully implanted with a PM within the implantation period. Two patients with transvenous left ventricular leads were excluded from further analysis. In an atrial position, lead 4592 was implanted in 51 patients and lead 5086MRI-52 cm was implanted in 40 patients, respectively. Ventricular leads were lead 4092-58 cm (64 patients) and lead 5086MRI (41 patients), respectively. Patients were followed for 26 ± 11 weeks. Comparison of lead measurements of lead group 1 showed significant differences for pacing impedance and pacing threshold at implantation, and for sensing at the 2nd follow-up. Comparison of lead measurements within lead group 2 showed significant differences for pacing impedance at implantation, for pacing threshold at the 1st follow-up, and for sensing, pacing threshold, and impedance at the 2nd follow-up. All assessed mean values were favorable for all leads at any follow-up. The number of re-operations was high in

  4. [Influence of implants on human body during MRI examinations: fundamental experiment using metal balls].

    PubMed

    Muranaka, Hiroyuki; Nakamura, Osamu; Usui, Shuji; Ueda, Yoshitake; Morikawa, Kaoru

    2005-07-20

    It is increasingly the case that patients who have implants feel pain during high-field MRI examinations. A probable reason for the pain is the generation by irradiation of RF pulses and changing of the magnetic field gradient. As a fundamental study on the effect of implants on the human body under MRI procedures, temperature measurements were obtained from metal balls incorporated into gel-filled phantoms by using two kinds of measuring instruments, a copper-constantan thermocouple and a fluorescence fiber thermometer. At first we pursued a correlation between a copper-constantan thermocouple (absolute measurement) and fluoroptic thermometer and confirmed the precision and stability of the fluoroptic thermometer under MRI procedures. When a stainless steel ball with or without a loop antenna was used, only in the former case did the temperature rise during RF pulse irradiation. There was no significant difference between the magnetic field gradient ON and OFF. Furthermore, differences in metal (steel, aluminum, brass, stainless steel, copper) and size (5, 10, 20 mmPhi) were affected according to the increase of temperature. In conclusion, both RF pulse irradiation and a loop antenna are necessary for heat generation on the surface of metals.

  5. Functional MRI in conscious rats using a chronically implanted surface coil.

    PubMed

    Martin, Chris J; Kennerley, Aneurin J; Berwick, Jason; Port, Michael; Mayhew, John E W

    2013-09-01

    To establish procedures for functional MRI (fMRI) in rats without the need for anesthetic agents. Rats were trained to habituate to restraint in a harness and scanner noise. Under anesthesia, rats were then prepared with a cranial implant that permitted stabilization of the head during subsequent imaging experiments. The cranial implant included an radiofrequency (RF) coil that was used to transmit and receive radiofrequency signals during imaging. Further training was then conducted to habituate the animals to head fixation whilst in the MR scanner. Using this method, we were able to successfully and repeatedly record BOLD fMRI responses to hypercapnia and whisker stimulation in awake rats. Electrical stimulation of the whisker pad produced a ∼7% increase in BOLD signal in the corresponding barrel cortex as well as adjacent negative BOLD responses, whilst hypercapnia produced larger increases in BOLD signal amplitude. This methodology leaves the face and limbs free from obstruction, making possible a range of behavioral or sensory stimulation protocols. Further development of this animal model could enable traditional behavioral neuroscience techniques to be combined with modern functional neuroimaging. Copyright © 2012 Wiley Periodicals, Inc., a Wiley company.

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

    PubMed Central

    Ciritsis, Alexander; Truhn, Daniel; Hansen, Nienke L.; Otto, Jens; Kuhl, Christiane K.; Kraemer, Nils A.

    2016-01-01

    Object 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. Material and Methods 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. Results 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”. Conclusion Both “positive contrast” techniques depicted implanted meshes with hyperintense signal. SGM comes without additional acquisition time and can therefore be utilized in every patient. PMID:27192201

  7. Paraplegia caused by posture during MRI in a patient with cervical disk herniation.

    PubMed

    Kato, Yoshihiko; Nishida, Norihiro; Taguchi, Toshihiko

    2010-06-09

    A 48-year-old man presented with numbness in the lower left extremity of 4 months' duration. One month earlier, he presented to an orthopedic clinic and magnetic resonance imaging (MRI) revealed cervical disk herniation. Because the pain did not subside, he visited the clinic again and MRI was performed. His neck was slightly extended and fixed to the headrest of the MRI instrument. Because of the posture of his cervical spine, he suffered severe pain in the scapular region during the MRI. After 15 minutes the pain was unbearable and the MRI examination was aborted. As the patient tried to descend from the MRI table, he was unable to move his bilateral lower extremities. No muscle contraction was observed in his lower limbs. Following MRI with flexion posture of the cervical spine, he was diagnosed with paraplegia caused by cervical disk herniation. Emergency surgery consisting of anterior decompression and fusion was performed. The patient showed good neurological recovery. Three weeks postoperatively, the patient could walk without assistance and he was discharged. The extension posture of the cervical spine during MRI was considered to be the cause of acute paraplegia in this patient. Care should be taken with the posture of the cervical spine, when performing MRI in patients with cervical disk herniation. Extended posture of the cervical spine during MRI may lead to acute neurological deterioration. Copyright 2010, SLACK Incorporated.

  8. Successful treatment of a large implant periapical lesion that caused paraesthesia and perimandibular abscess

    PubMed Central

    Jafarian, Mohammad; Rayati, Farshid; Najafi, Elnaz

    2016-01-01

    Successful treatment of a large implant periapical lesion (IPL) that caused paraesthesia and perimandibular abscess. IPL is a pathologic phenomenon that rarely involves implants. This event first described in 1992 with an incidence rate of 0.26-9.9% and the origin is not well known. The most likely suggested causes are presence of preexisting bone pathology, contamination of implant surface, bone overheating during implant surgery, vascular ischemia, excessive tightening of the implant, fenestration of the buccal plate and different implant surface designs. In the present case report, we describe relatively large periapical lesions involving several implants caused severe abscess accompanied by transient inferior alveolar nerve paraesthesia and its successful management. A brief review of the literature and a discussion of possible causes and different treatment plans are also included. PMID:27076835

  9. Successful treatment of a large implant periapical lesion that caused paraesthesia and perimandibular abscess.

    PubMed

    Jafarian, Mohammad; Rayati, Farshid; Najafi, Elnaz

    2016-01-01

    Successful treatment of a large implant periapical lesion (IPL) that caused paraesthesia and perimandibular abscess. IPL is a pathologic phenomenon that rarely involves implants. This event first described in 1992 with an incidence rate of 0.26-9.9% and the origin is not well known. The most likely suggested causes are presence of preexisting bone pathology, contamination of implant surface, bone overheating during implant surgery, vascular ischemia, excessive tightening of the implant, fenestration of the buccal plate and different implant surface designs. In the present case report, we describe relatively large periapical lesions involving several implants caused severe abscess accompanied by transient inferior alveolar nerve paraesthesia and its successful management. A brief review of the literature and a discussion of possible causes and different treatment plans are also included.

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

    PubMed

    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.

  11. Correlation of histological findings with gadolinium enhanced MRI scans during healing of a PHEMA orbital implant in rabbits

    PubMed Central

    Hicks, C.; Morris, I.; Vijayasekaran, S.; Fallon, M.; McAllister, J.; Clayton, A.; Chirila, T.; Crawford, G.; Constable, I.

    1999-01-01

    BACKGROUND/AIMS—To investigate a poly(2-hydroxyethyl methacrylate) (PHEMA) orbital implant with a spongy anterior hemisphere and a smooth gel posterior hemisphere, by histology correlated with magnetic resonance images.
METHODS—Following enucleation, eight rabbits received PHEMA implants to which the muscles were directly sutured, and underwent gadolinium enhanced magnetic resonance imaging (MRI) from 3 to 52 weeks. After the rabbits were killed, the implants were removed, cut in a plane corresponding to the scan, and processed for light and electron microscopy.
RESULTS—All eight rabbits retained their implant to the end of the study period without complications. The scans demonstrated muscle attachment to the anterior half of the implant, and enhancement was seen on injection of gadolinium chelate. Histology confirmed muscle attachment, and cellular and vascular ingrowth. Over time, a transformation from reactive inflammatory to relatively non-vascular scar tissue was seen within the implant. Calcium deposits in one implant were detected by imaging and histology.
CONCLUSION—The implants are readily visualised on MRI. Muscle attachment and fibrovascular ingrowth into the anterior hemisphere are seen, while encapsulation of the posterior hemisphere is minimal. Histological findings confirm the progress of the healing response, with initial inflammation and marked vascularisation, developing later into quiescent scar tissue predominantly of fibroblasts.

 PMID:10216066

  12. Penile Implants among Prisoners—A Cause for Concern?

    PubMed Central

    Yap, Lorraine; Butler, Tony; Richters, Juliet; Malacova, Eva; Wand, Handan; Smith, Anthony M. A.; Grant, Luke; Richards, Alun; Donovan, Basil

    2013-01-01

    Background We report the prevalence of penile implants among prisoners and determine the independent predictors for having penile implants. Questions on penile implants were included in the Sexual Health and Attitudes of Australian Prisoners (SHAAP) survey following concerns raised by prison health staff that increasing numbers of prisoners reported having penile implants while in prison. Methods Computer-Assisted Telephone Interviewing (CATI) of a random sample of prisoners was carried out in 41 prisons in New South Wales and Queensland (Australia). Men were asked, “Have you ever inserted or implanted an object under the skin of your penis?” If they responded Yes: “Have you ever done so while you were in prison?” Univariate logistic regression and logistic regression were used to determine the factors associated with penile implants. Results A total of 2,018 male prisoners were surveyed, aged between 18 and 65 years, and 118 (5.8%) reported that they had inserted or implanted an object under the skin of their penis. Of these men, 87 (73%) had this done while they were in prison. In the multivariate analysis, a younger age, birth in an Asian country, and prior incarceration were all significantly associated with penile implants (p<0.001). Men with penile implants were also more likely to report being paid for sex (p<0.001), to have had body piercings (p<0.001) or tattoos in prison (p<0.001), and to have taken non-prescription drugs while in prison (p<0.05). Conclusions Penile implants appear to be fairly common among prisoners and are associated with risky sexual and drug use practices. As most of these penile implants are inserted in prison, these men are at risk of blood borne viruses and wound infection. Harm reduction and infection control strategies need to be developed to address this potential risk. PMID:23326383

  13. Pelvic hydatid disease: CT and MRI findings causing sciatica.

    PubMed

    Sanal, Hatice Tuba; Kocaoglu, Murat; Bulakbasi, Nail; Yildirim, Duzgun

    2007-01-01

    Pelvic masses, especially hydatid disease, rarely present with sciatica (1, 2). We present the computed tomography (CT) and the magnetic resonance imaging (MRI) findings of a 49-year-old female patient with presacral hydatid disease, who was evaluated for her sciatica. We also want to emphasize the importance of assessing the pelvis of patients with symptoms and clinical findings that are inconsistent and that cannot be satisfactorily explained by the spinal imaging findings.

  14. Pelvic Hydatid Disease: CT and MRI Findings Causing Sciatica

    PubMed Central

    Kocaoglu, Murat; Bulakbasi, Nail; Yildirim, Duzgun

    2007-01-01

    Pelvic masses, especially hydatid disease, rarely present with sciatica (1, 2). We present the computed tomography (CT) and the magnetic resonance imaging (MRI) findings of a 49-year-old female patient with presacral hydatid disease, who was evaluated for her sciatica. We also want to emphasize the importance of assessing the pelvis of patients with symptoms and clinical findings that are inconsistent and that cannot be satisfactorily explained by the spinal imaging findings. PMID:18071287

  15. Rupture of silicone-gel breast implants: causes, sequelae, and diagnosis.

    PubMed

    Brown, S L; Silverman, B G; Berg, W A

    1997-11-22

    Silicone-gel-filled breast implants have been widely used for breast augmentation and reconstruction after mastectomy. The rate of implant rupture and its sequelae are not known. We review the frequency, causes, sequelae, and detection of implant rupture. Materials testing of removed implants provides evidence that as implants age in vivo, they weaken and may rupture. Sequelae of rupture include migration of gel accompanied by inflammation and silicone granuloma formation. The role of free silicone gel in relation to idiopathic or atypical connective tissue disease is not clear. Magnetic resonance imaging is substantially more sensitive in the detection of rupture than is mammography or ultrasonography.

  16. Lethal Hemorrhage Caused by Aortoenteric Fistula Following Endovascular Stent Implantation

    SciTech Connect

    Kahlke, Volker; Brossmann, Joachim; Klomp, Hans-Juergen

    2002-06-15

    A 55-year-old women developed an aortointestinal fistula between the bifurcation of the aorta and the distal ileum following implantation of multiple endovascular stents into both common iliac arteries for treatment of aortoiliac occlusive disease. Ten months before the acute onset of the gastrointestinal hemorrhage two balloon-expandable steel stents had been implanted into both common iliac arteries. Due to restenosis and recurrent intermittent claudication, three balloon-expandable covered stents were implanted 4 months later on reintervention. The patient presented with abdominal pain and melena, and fell into hemorrhagic shock with signs of upper gastrointestinal bleeding. After transfer to our hospital, she again developed hemorrhagic shock with massive upper and lower gastrointestinal bleeding and died during emergency laparotomy. The development of aortoenteric fistulas following endovascular surgery/stent implantation is very rare and has to be considered in cases of acute gastrointestinal hemorrhage.

  17. Localization of neurosurgically implanted electrodes via photograph-MRI-radiograph coregistration.

    PubMed

    Dalal, Sarang S; Edwards, Erik; Kirsch, Heidi E; Barbaro, Nicholas M; Knight, Robert T; Nagarajan, Srikantan S

    2008-09-15

    Intracranial electroencephalography (iEEG) is clinically indicated for medically refractory epilepsy and is a promising approach for developing neural prosthetics. These recordings also provide valuable data for cognitive neuroscience research. Accurate localization of iEEG electrodes is essential for evaluating specific brain regions underlying the electrodes that indicate normal or pathological activity, as well as for relating research findings to neuroimaging and lesion studies. However, electrodes are frequently tucked underneath the edge of a craniotomy, inserted via a burr hole, or placed deep within the brain, where their locations cannot be verified visually or with neuronavigational systems. We show that one existing method, registration of postimplant computed tomography (CT) with preoperative magnetic resonance imaging (MRI), can result in errors exceeding 1cm. We present a novel method for localizing iEEG electrodes using routinely acquired surgical photographs, X-ray radiographs, and magnetic resonance imaging scans. Known control points are used to compute projective transforms that link the different image sets, ultimately allowing hidden electrodes to be localized, in addition to refining the location of manually registered visible electrodes. As the technique does not require any calibration between the different image modalities, it can be applied to existing image databases. The final result is a set of electrode positions on the patient's rendered MRI yielding locations relative to sulcal and gyral landmarks on individual anatomy, as well as MNI coordinates. We demonstrate the results of our method in eight epilepsy patients implanted with electrode grids spanning the left hemisphere.

  18. SU-C-17A-02: Sirius MRI Markers for Prostate Post-Implant Assessment: MR Protocol Development

    SciTech Connect

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

    2014-06-15

    Purpose: Currently, CT is used to visualize prostate brachytherapy sources, at the expense of accurate structure contouring. MRI is superior to CT for anatomical delineation, but the sources appear as voids on MRI images. Previously we have developed Sirius MRI markers (C4 Imaging) to replace spacers to assist source localization on MRI images. Here we develop an MRI pulse sequence protocol that enhances the signal of these markers to enable MRI-only post-implant prostate dosimetric analysis. Methods: To simulate a clinical scenario, a CIRS multi-modality prostate phantom was implanted with 66 markers and 86 sources. The implanted phantom was imaged on both 1.5T and 3.0T GE scanners under various conditions, different pulse sequences (2D fast spin echo [FSE], 3D balanced steadystate free precession [bSSFP] and 3D fast spoiled gradient echo [FSPGR]), as well as varying amount of padding to simulate various patient sizes and associated signal fall-off from the surface coil elements. Standard FSE sequences from the current clinical protocols were also evaluated. Marker visibility, marker size, intra-marker distance, total scan time and artifacts were evaluated for various combinations of echo time, repetition time, flip angle, number of excitations, bandwidth, slice thickness and spacing, fieldof- view, frequency/phase encoding steps and frequency direction. Results: We have developed a 3D FSPGR pulse sequence that enhances marker signal and ensures the integrity of the marker shape while maintaining reasonable scan time. For patients contraindicated for 3.0T, we have also developed a similar sequence for 1.5T scanners. Signal fall-off with distance from prostate to coil can be compensated mainly by decreasing bandwidth. The markers are not visible using standard FSE sequences. FSPGR sequences are more robust for consistent marker visualization as compared to bSSFP sequences. Conclusion: The developed MRI pulse sequence protocol for Sirius MRI markers assists source

  19. Mycobacterium fortuitum causing infection of a biventricular pacemaker/implantable cardioverter defibrillator.

    PubMed

    Hu, Yuhning L; Bridge, Bronwyn; Wang, Jeffrey; Jovin, Ion S

    2012-12-01

    Increased utilization of cardiovascular implantable electronic devices (CIED) has seen a corresponding rise in related infections. Non-tuberculosis mycobacteria (NTM) are rarely the cause. Treatment involves susceptibilities, antimicrobials, and device removal. This study presents a patient who underwent a biventricular implantable cardioverter defibrillator upgrade with a multi-drug resistant Mycobacterium fortuitum located at the pocket site and a lead infection.

  20. X-ray radiation causes electromagnetic interference in implantable cardiac pacemakers.

    PubMed

    Hirose, Minoru; Tachikawa, Keiichi; Ozaki, Masanori; Umezawa, Naoki; Shinbo, Toshihiro; Kokubo, Kenichi; Kobayashi, Hirosuke

    2010-10-01

    X-rays are not thought to cause electromagnetic interference (EMI) in implantable cardiac pacemakers. However, x-ray radiation during computed tomography (CT) scanning has been reported to cause EMI in some implantable cardiac pacemakers. The objectives of this study were to identify the location within the pacemakers where x-ray radiation causes EMI and to investigate the association of EMI with the x-ray radiation conditions. We verified the location where x-ray radiation caused EMI using a CT scanner and conventional radiographic x-ray equipment. An inhibition test and an asynchronous test were performed using five types of implantable cardiac pacemakers. X-ray radiation inhibited the pacing pulses of four types of implantable cardiac pacemakers when the body of each implantable cardiac pacemaker, containing a complementary metal-oxide semiconductor (CMOS), was scanned using a CT scanner. We confirmed that x-ray-induced EMI depends on the x-ray radiation conditions, that is, the tube voltage, tube current, x-ray dose, and direction of x-ray radiation, as well as the sensing thresholds of the implantable cardiac pacemakers. X-ray radiation caused EMI in some implantable cardiac pacemakers, probably because the CMOS component was irradiated. The occurrence of EMI depended on the pacemaker model, sensing threshold of the pacemaker, and x-ray radiation conditions. ©2010, The Authors. Journal compilation ©2010 Wiley Periodicals, Inc.

  1. Biophysics of cochlear implant/MRI interactions emphasizing bone biomechanical properties.

    PubMed

    Sonnenburg, Robert E; Wackym, Phillip A; Yoganandan, Narayan; Firszt, Jill B; Prost, Robert W; Pintar, Frank A

    2002-10-01

    The forces exerted during a 1.5-Tesla MRI evaluation on the internal magnet of a cochlear implant (CI) raise concern about the safety for CI recipients. This study determines the magnitude of force required to fracture the floor of a CI receiver bed. Recessed CI beds were drilled to maximum uniform thinness into formalin-fixed and fresh-frozen human calvaria specimens. A Med-El stainless steel CI template mounted to the piston of an electrohydraulic testing device was used to fracture the floor of the implant beds. Force and displacement were measured as a function of time using a digital data acquisition system. Mean force to first failure, displacement to first failure, and minimum thickness, respectively, were: group 1 (formalin-fixed, 0.3-0.4-mm thick [n = 22]), 34.08 N (8.21-59.64 N, standard deviation [SD] 15.41 N), 1.09 mm (0.40-2.16 mm, SD 0.51 mm), 0.36 mm (0.3-0.4 mm, SD 0.05 mm); group 2 (formalin-fixed, 0.5-0.9 mm thick [n = 21]), 52.82 N (20.28-135.53 N, SD 25.29 N), 1.08 mm (0.50-2.28 mm, SD 0.47 mm), 0.58 mm (0.5-0.9 mm, SD 0.12 mm); group 3 (fresh-frozen [n = 9]), 134.13 N (86.44-190.70 N, SD 34.92 N), 1.96 mm (1.47-2.46 mm, SD 0.35 mm), 0.42 mm (0.3-0.6 mm, SD 0.11 mm). The mean magnitude of force required to fracture the floor of a CI bed is significantly greater than those that are generated when a Med-El Combi 40+, CII Bionic Ear CI, or Nucleus Contour CI is placed into a 1.5-Tesla MRI unit.

  2. Implantable cardioverter-defibrillator infection caused by Tsukamurella.

    PubMed

    Almehmi, Ammar; Pfister, Alfred K; McCowan, Ronald; Matulis, Susie

    2004-01-01

    Human infections with Tsukamurella are very rare with only 13 reported cases in the literature. Certain conditions, such as immunosuppression, an indwelling foreign body, and postoperative wounds predispose humans to Tsukamurella infections. The rarity of Tsukamurella infection in humans makes its diagnosis and treatment very difficult. This article describes the first case of implantable cardioverter-defibrillator (ICD) infection related to Tsukamurella in the literature.

  3. A semi-supervised Support Vector Machine model for predicting the language outcomes following cochlear implantation based on pre-implant brain fMRI imaging.

    PubMed

    Tan, Lirong; Holland, Scott K; Deshpande, Aniruddha K; Chen, Ye; Choo, Daniel I; Lu, Long J

    2015-12-01

    We developed a machine learning model to predict whether or not a cochlear implant (CI) candidate will develop effective language skills within 2 years after the CI surgery by using the pre-implant brain fMRI data from the candidate. The language performance was measured 2 years after the CI surgery by the Clinical Evaluation of Language Fundamentals-Preschool, Second Edition (CELF-P2). Based on the CELF-P2 scores, the CI recipients were designated as either effective or ineffective CI users. For feature extraction from the fMRI data, we constructed contrast maps using the general linear model, and then utilized the Bag-of-Words (BoW) approach that we previously published to convert the contrast maps into feature vectors. We trained both supervised models and semi-supervised models to classify CI users as effective or ineffective. Compared with the conventional feature extraction approach, which used each single voxel as a feature, our BoW approach gave rise to much better performance for the classification of effective versus ineffective CI users. The semi-supervised model with the feature set extracted by the BoW approach from the contrast of speech versus silence achieved a leave-one-out cross-validation AUC as high as 0.97. Recursive feature elimination unexpectedly revealed that two features were sufficient to provide highly accurate classification of effective versus ineffective CI users based on our current dataset. We have validated the hypothesis that pre-implant cortical activation patterns revealed by fMRI during infancy correlate with language performance 2 years after cochlear implantation. The two brain regions highlighted by our classifier are potential biomarkers for the prediction of CI outcomes. Our study also demonstrated the superiority of the semi-supervised model over the supervised model. It is always worthwhile to try a semi-supervised model when unlabeled data are available.

  4. Technical complications of implant-causes and management: A comprehensive review

    PubMed Central

    Gupta, Swati; Gupta, Hemant; Tandan, Amrit

    2015-01-01

    Given the increasing popularity of dental implants, the number of failures due to late implant fracture is also expected to increase. Hence, the scope for prevention and management needs to be emphasized. The objective of this review article is to analyze the various causes of failure of dental implants due to implant fixture/abutment screw fractures and also to enumerate the management and the preventive options for these failures, thereby aiming to help the clinicians to properly plan the implant-supported prosthesis treatment by considering the important biomechanical aspects of this type of rehabilitation. The present review emphasizes the causes and management of technical complications and not the incidence of such complications. PMID:26668445

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

    PubMed Central

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

    2005-01-01

    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 factor above ten. Using MR

  6. Brain Activation in Response to Visceral Stimulation in Rats with Amygdala Implants of Corticosterone: An fMRI Study

    PubMed Central

    Johnson, Anthony C.; Myers, Brent; Lazovic, Jelena; Towner, Rheal; Greenwood-Van Meerveld, Beverley

    2010-01-01

    Background 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. Methodology/Principal Findings Anesthetized male rats received micropellets (30 µg 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. Conclusions and Significance 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

  7. Magnetic Resonance Imaging in a Neurofibromatosis Type 2 Patient with a Novel MRI-Compatible Auditory Brainstem Implant

    PubMed Central

    Shew, Matthew; Bertsch, Judson; Camarata, Paul; Staecker, Hinrich

    2017-01-01

    Auditory brainstem implantation has become a key technique for the rehabilitation of hearing in patients with neurofibromatosis type 2. The nature of this devastating genetic disease requires ongoing MRI for the patient's lifespan. Today, most auditory brainstem implants require removal of the magnet that connects the internal device to the external speech processor to undergo imaging as their disease progresses. Patients have the option of having a short procedure to have the magnet taken out and replaced each time, or alternately using a headband to secure the processor over the receiver coil of the internal device. Novel magnet technology has led to the development of a freely rotating magnet that can be used inside the magnetic field of an MRI scanner without losing magnet strength and without being displaced from the body of the device. We report one of the first patients implanted with a Med-El Synchrony ABI in the United States who subsequently underwent successful imaging with MRI 1.5 tesla to follow for other existing schwannomas. PMID:28210535

  8. Magnetic Resonance Imaging in a Neurofibromatosis Type 2 Patient with a Novel MRI-Compatible Auditory Brainstem Implant.

    PubMed

    Shew, Matthew; Bertsch, Judson; Camarata, Paul; Staecker, Hinrich

    2017-01-01

    Auditory brainstem implantation has become a key technique for the rehabilitation of hearing in patients with neurofibromatosis type 2. The nature of this devastating genetic disease requires ongoing MRI for the patient's lifespan. Today, most auditory brainstem implants require removal of the magnet that connects the internal device to the external speech processor to undergo imaging as their disease progresses. Patients have the option of having a short procedure to have the magnet taken out and replaced each time, or alternately using a headband to secure the processor over the receiver coil of the internal device. Novel magnet technology has led to the development of a freely rotating magnet that can be used inside the magnetic field of an MRI scanner without losing magnet strength and without being displaced from the body of the device. We report one of the first patients implanted with a Med-El Synchrony ABI in the United States who subsequently underwent successful imaging with MRI 1.5 tesla to follow for other existing schwannomas.

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

    PubMed Central

    2012-01-01

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

  10. Halofuginone inhibits angiogenesis and growth in implanted metastatic rat brain tumor model--an MRI study.

    PubMed

    Abramovitch, Rinat; Itzik, Anna; Harel, Hila; Nagler, Arnon; Vlodavsky, Israel; Siegal, Tali

    2004-01-01

    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 alpha1(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.

  11. MRI scanning in patients implanted with a round window or stapes coupled floating mass transducer of the Vibrant Soundbridge.

    PubMed

    Renninger, Daniel; Ernst, Arne; Todt, Ingo

    2016-01-01

    Conclusion MRI examinations in patients with an alternatively coupled VSB can lead to unpleasant side-effects. However, the residual hearing was not impaired, whereas the hearing performance with the VSB was decreased in one patient which could be fixed by a surgical revision. Different experiences for the VSB 503 can be expected. Objective To investigate the in vivo effects of MRI scanning on the Vibrant Soundbridge system (VSB) with an alternatively coupled Floating Mass Transducer (FMT). Method Sixty-five VSB (502) implantees were included in this study. Of them, 42 questionnaires could be evaluated with the patients' statements about their medical, otological, and general condition before, during, and after an MRI scan which was indicated for different medical reasons, despite the previous implantation of an alternatively coupled Vibrant Soundbridge System. Results In four patients (9.5%), five MRI examinations were performed. These were done for different indications (e.g. knee and shoulder joint diagnostics). During the scanning, noise and subjectively perceived distortion of the implant were described. A deterioration of the hearing gain with the VSB in place was found in one patient. A decrease of the hearing threshold was not observed.

  12. Predictors of false negative diffusion-weighted MRI in clinically suspected central cause of vertigo.

    PubMed

    Akoglu, Ebru Unal; Akoglu, Haldun; Cimilli Ozturk, Tuba; Onur, Bahaeddin; Eroglu, Serkan Emre; Onur, Ozge; Denizbasi, Arzu

    2017-09-23

    Vertigo is classified as peripheral and central. Differentiation of stroke mimics is the most important diagnostic challenge. There is no clinical guidance for the indications of neuroimaging in isolated vertigo patients. The primary aim of this study is to test the diagnostic value of a DWI-MRI protocol to rule-out a central cause in patients with acute isolated vertigo in the ED. We prospectively enrolled 144 patients who were presented with isolated vertigo to the ED. A detailed neurological examination and maneuvers were performed for differential diagnosis. All patients underwent CT and/or DW-MRI either during ED visit or at the follow-up, if necessary. Out-patient follow-up exams and evaluations were repeated until all patients had a definitive diagnosis. In the study, 137 of the 144 patients completed the follow-up period, and 34 of 137 patients were diagnosed with central vertigo. Six of 34 central vertigo patients had normal DW-MRI findings. One was diagnosed with migraine headache and five with vertebra-basilar insufficiency during the out-patient follow-up. One of the 28 patients with a pathological MRI was diagnosed with mass and the rest was stroke. The utility of DW-MRI in vertigo patients was moderately high (sensitivity: 82%, specificity: 100%). We found that age, history of HT, history of CAD and vertigo unresponsive to ED treatment were significantly associated with a central cause of vertigo. We suggest that unresponsiveness to ED treatment, especially in patients with a history of HT and CAD, should alert physicians for central causes and warrant DW-MRI imaging. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    PubMed

    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 <24 months at fMRI scanning and <36 months at first implantation. A silent background fMRI acquisition method was performed to acquire fMRI during auditory 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

  14. [Aberrant internal carotid artery as a cause of pulsatile tinnitus: a difficult diagnosis in MRI?].

    PubMed

    Soyka, M B; Schuknecht, B; Huber, A M

    2010-02-01

    We present the case of a 43-year-old patient with sensorineural hearing loss and the finding of an aberrant internal carotid artery in the left tympanic cavity that was causing pulsatile tinnitus. The aberrant vessel was initially invisible on magnetic resonance imaging (MRI) and was confirmed by high-resolution computed tomography and MR angiography (MRA). Recognition of an aberrant course of an internal carotid artery often requires a combination of MRI and MRA to establish the diagnosis and rule out other differential diagnoses.

  15. Electromagnetic interference in an implantable loop recorder caused by a portable digital media player.

    PubMed

    Thaker, Jay P; Patel, Mehul B; Jongnarangsin, Krit; Liepa, Valdis V; Castellani, Mark; Thakur, Ranjan K

    2008-10-01

    The implantable loop recorder has been shown to be a cost-effective tool for diagnosis of intermittent cardiovascular symptoms such as syncope and palpitations. Electromagnetic interference in these recorders may be caused by commonly encountered electronic devices such as antitheft electronic surveillance systems and magnetic resonance imaging cameras. In this report, we describe interference in two patients with implantable loop recorders from a portable digital media player.

  16. High dielectric material in MRI: Numerical assessment of the reduction of the induced local power on implanted cardiac leads.

    PubMed

    Mattei, Eugenio; Lucano, Elena; Censi, Federica; Angelone, Leonardo M; Calcagnini, Giovanni

    2016-08-01

    High dielectric materials (HDM) have been proposed in magnetic resonance imaging (MRI) to increase the signal-to-noise ratio (SNR) of the images acquired while reducing the radiofrequency (RF) absorption in tissue. The aim of this study is to assess the potential merit of using HDM to reduce power induced at the tip of an endocardial lead in patients undergoing MRI. Numerical simulations were performed using a commercial finite-differences time-domain (FDTD) software to model the RF field generated by a birdcage body coil at 64 MHz on a human body model. Two HDM pads were placed between the coil and the body model, and their effect was evaluated in terms of local induced power at the tip of a pacemaker lead. Two different patient imaging positions inside the coil (i.e., head & thorax) were studied. In both cases, the use of HDM allowed reducing the induced power (i.e., 57% reduction with head landmark, 68% with thorax landmark), while maintaining the same magnitude of B1 RMS at the isocenter of the coil. Additionally, when the HDM pads were placed at the head landmark, there was a significant decrease in the local-induced power at the tip of the implant path (58%). Conversely, there was only a 9% decrease when pads were placed at the thorax landmark. In conclusion, the study shows that when the implant is not included in the volume surrounded by the HDM, pads placed between the RF coil and the patient allow obtaining the same magnitude of B1-field with a lower input power of the RF coil, reducing significantly the local induced power around the implant. Conversely, if the implant is included in the volume surrounded by the HDM, the use of HDM can still reduce the input power necessary to obtain the same magnitude of B1-field, but the effect on the local induce power at the implant is lower in magnitude.

  17. Image-guided tissue engineering of anatomically shaped implants via MRI and micro-CT using injection molding.

    PubMed

    Ballyns, Jeffery J; Gleghorn, Jason P; Niebrzydowski, Vicki; Rawlinson, Jeremy J; Potter, Hollis G; Maher, Suzanne A; Wright, Timothy M; Bonassar, Lawrence J

    2008-07-01

    This study demonstrates for the first time the development of engineered tissues based on anatomic geometries derived from widely used medical imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). Computer-aided design and tissue injection molding techniques have demonstrated the ability to generate living implants of complex geometry. Due to its complex geometry, the meniscus of the knee was used as an example of this technique's capabilities. MRI and microcomputed tomography (microCT) were used to design custom-printed molds that enabled the generation of anatomically shaped constructs that retained shape throughout 8 weeks of culture. Engineered constructs showed progressive tissue formation indicated by increases in extracellular matrix content and mechanical properties. The paradigm of interfacing tissue injection molding technology can be applied to other medical imaging techniques that render 3D models of anatomy, demonstrating the potential to apply the current technique to engineering of many tissues and organs.

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

    PubMed

    Córcoles, Juan; Zastrow, Earl; Kuster, Niels

    2017-03-02

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

  19. Torque measurements of the ossicular chain: implication on the MRI safety of the hearing implant Vibrant Soundbridge.

    PubMed

    Jesacher, Marco Otto; Kiefer, Jan; Zierhofer, Clemens; Fauser, Claudius

    2010-06-01

    Is the human ossicular chain stabile enough to withstand the torque of a Vibrant Soundbridge middle ear hearing implant in the magnetic field of a 1.5 T magnetic resonance imaging (MRI) system? The Vibrant Soundbridge is a semi-implantable hearing device in which a tiny electromechanical transducer, called floating mass transducer (FMT), is clipped to the ossicular chain within the middle ear. The FMT contains a permanent magnet, which can generate a torque when exposed to a static magnetic field of MRI systems. Since the transducer is routinely attached to the long process of the incus, this torque could affect or even disrupt the ossicular chain. This study investigates the likelihood of a middle ear injury by an FMT in an MRI system. Torque measurements were performed on 10 unpreserved human temporal bones. A brass fork was attached to the long process of the incus via a posterior tympanotomy, and a defined torque was applied by a calibrated torque meter. The torque was increased stepwise until an injury of the middle ear was observed. The mean torque at which the middle ear was injured was 4.3 mN.m +/- 1.7 mN.m. The lowest value measured was 1.5 mN.m, and the highest was 6.5 mN.m. Even the lowest torque measured is more than 1.5 times higher than the "worst-case" torque affecting the FMT during a 1.5 T MRI examination. The torque on an FMT crimped to the long process of the incus should therefore not harm the human middle ear.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Causes of Phakic Implantable Collamer Lens Explantation/Exchange at King Khaled Eye Specialist Hospital

    PubMed Central

    AlSabaani, Nasser A.; Behrens, Ashley; Jastanieah, Sabah; Al Malki, Salem; Al Jindan, Mohanna; Al Motowa, Saeed

    2016-01-01

    PURPOSE: The purpose of this study is to evaluate the causes of phakic implantable collamer lens (ICL) explantation/exchange at an eye hospital in Saudi Arabia. MATERIALS AND METHODS: A retrospective chart review was performed for patients who underwent ICL implantation from 2007 to March 2014 and data were collected on cases that underwent ICL explantation. RESULTS: Of the 787 ICL implants, 30 implants (3.8% [95% confidence interval 2.6%; 5.3%]) were explanted. The causes of explantation included incorrect lens size (22), cataract (4), high residual astigmatism (2), rhegmatogenous retinal detachment (1), and intolerable glare (1). Corrective measures mainly included an exchange with an appropriately sized lens (9), ICL explantation (11), with phacoemulsification and posterior chamber intraocular lens implantation (6), or replacement with an ICL of correct power (2). CONCLUSION: Incorrect ICL size was the most common cause of ICL explantation. More accurate sizing methods for ICL are required to reduce the explantation/exchange rate. PMID:27994391

  2. Does residual cement around implant-supported restorations cause peri-implant disease? A retrospective case analysis.

    PubMed

    Linkevicius, Tomas; Puisys, Algirdas; Vindasiute, Egle; Linkeviciene, Laura; Apse, Peteris

    2013-11-01

    The purpose of this study was to determine the relationship between patients with a history of periodontitis and development of cement-related peri-implant disease. Seventy-seven patients with 129 implants for this retrospective analysis were selected from completed implant cases that were scheduled for regular maintenance or had experienced mechanical or biological complications between years 2006 and 2011 in private practice. Implants with extracoronal residual cement and implants without cement remnants were analyzed. The selected cases were further divided into two groups--implants in patients with history of periodontitis (1) and implants in periodontitis-free individuals (2). The selection of these groups was made on the basis of treatment history and orthopantomograph. As a control group, a set of 238 screw-retained implant restorations, delivered to 66 patients during the same period of time was examined. The incidence of peri-implant disease among implants in all groups was calculated. Peri-implant disease was evident in 62 of 73 implants with cement remnants (85%). All implants in group 1 developed peri-implantitis--4 early and 35 delayed disease cases. In the periodontally healthy group, 20 of 31 implants were diagnosed with peri-implant mucositis, 3 implants had early peri-implantitis, and 11 implants with cement remnants did not develop biological complications. In the group of implants without cement remnants, peri-implant disease was diagnosed in 17 of 56 cases (30%). In contrast, only two occurrences of peri-implant disease were registered in the control group of screw-retained restorations (1.08%). Implants with cement remnants in patients with history of periodontitis may be more likely to develop peri-implantitis, compared with patients without history of periodontal infection. © 2012 John Wiley & Sons A/S.

  3. Compressed Sensing SEMAC: 8-fold Accelerated High Resolution Metal Artifact Reduction MRI of Cobalt-Chromium Knee Arthroplasty Implants.

    PubMed

    Fritz, Jan; Ahlawat, Shivani; Demehri, Shadpour; Thawait, Gaurav K; Raithel, Esther; Gilson, Wesley D; Nittka, Mathias

    2016-10-01

    The aim of this study was to prospectively test the hypothesis that a compressed sensing-based slice encoding for metal artifact correction (SEMAC) turbo spin echo (TSE) pulse sequence prototype facilitates high-resolution metal artifact reduction magnetic resonance imaging (MRI) of cobalt-chromium knee arthroplasty implants within acquisition times of less than 5 minutes, thereby yielding better image quality than high-bandwidth (BW) TSE of similar length and similar image quality than lengthier SEMAC standard of reference pulse sequences. This prospective study was approved by our institutional review board. Twenty asymptomatic subjects (12 men, 8 women; mean age, 56 years; age range, 44-82 years) with total knee arthroplasty implants underwent MRI of the knee using a commercially available, clinical 1.5 T MRI system. Two compressed sensing-accelerated SEMAC prototype pulse sequences with 8-fold undersampling and acquisition times of approximately 5 minutes each were compared with commercially available high-BW and SEMAC pulse sequences with acquisition times of approximately 5 minutes and 11 minutes, respectively. For each pulse sequence type, sagittal intermediate-weighted (TR, 3750-4120 milliseconds; TE, 26-28 milliseconds; voxel size, 0.5 × 0.5 × 3 mm) and short tau inversion recovery (TR, 4010 milliseconds; TE, 5.2-7.5 milliseconds; voxel size, 0.8 × 0.8 × 4 mm) were acquired. Outcome variables included image quality, display of the bone-implant interfaces and pertinent knee structures, artifact size, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Statistical analysis included Friedman, repeated measures analysis of variances, and Cohen weighted k tests. Bonferroni-corrected P values of 0.005 and less were considered statistically significant. Image quality, bone-implant interfaces, anatomic structures, artifact size, SNR, and CNR parameters were statistically similar between the compressed sensing-accelerated SEMAC prototype and SEMAC

  4. Pinpointing synaptic loss caused by Alzheimer's disease with fMRI

    PubMed Central

    Brickman, Adam M.; Small, Scott A.; Fleisher, Adam

    2010-01-01

    During its earliest stage, before cell loss and independent of amyloid plaques and neurofibrillary tangles, Alzheimer's disease (AD) causes synaptic loss affecting the basal functional properties of neurons. In principle, synaptic loss can be detected by measuring AD-induced changes in basal function, or by measuring stimulus-evoked responses on top of basal changes. Functional magnetic resonance imaging (fMRI) is sensitive to both basal changes and evoked-responses, and there are therefore two experimental approaches in which fMRI can be used to pinpoint synaptic loss in AD. In this review, we will compare and contrast both approaches for pinpointing when and where synaptic loss in AD begins and for monitoring therapeutic efficacy. PMID:19847048

  5. Categorization of Pathology Causing Low Back Pain using Magnetic Resonance Imaging (MRI)

    PubMed Central

    Nadhamuni, Kulasekaran; Karthikeyan, T.

    2015-01-01

    Background: Low backache is the most common ailment flooding the orthopaedic clinic. Most of the population at least once seek medical attention for low back ache. Magnetic Resonance Imaging (MRI) is a non invasive, commonly used diagnosing modality and accurate in diagnosing pathology causing low back ache. Aim: To classify and quantify the causes of low back pain referred to radiology department by MRI. Materials and Methods: Patients with back pain referred to radiology department were subjected to single MRI scan after ruling out any contraindications using the following sequences: T1W Turbo Spin Echo, T2W Turbo Spin Echo, Gradient-echo, Myelogram and short TI inversion recovery (STIR), in all imaging planes. Gadolinium enhanced T1W turbo spin echo sequence was used wherever necessary. Results: Data were analysed using Excel 2007, SPSS 14, Students t-test. Degenerative disc diseases were the commonest pathology followed by congenital and traumatic lesions. Neoplastic lesions were the least common. Commonest herniation type being the disc bulge (79%) followed by disc protrusion (15%), disc extrusion (6%) and disc sequestration (<1%). The posterolateral disc herniation as the commonest and foraminal the least. Sacralisation was the most common congenital spinal anomaly, followed by lumbar scoliosis and perineural cyst. There is no sex difference in disc protrusion but male preponderance in disc extrusion with subligmentous extrusion. Conclusion: MRI is useful in classifying the spinal lesions which again influences the treatment modality and clinical outcome. Degenerative disc disease is the single most common category which accounts for most the Low Back Ache for which a preventing strategy should be drafted. PMID:25738056

  6. Categorization of Pathology Causing Low Back Pain using Magnetic Resonance Imaging (MRI).

    PubMed

    Gopalakrishnan, Nirmalkumar; Nadhamuni, Kulasekaran; Karthikeyan, T

    2015-01-01

    Low backache is the most common ailment flooding the orthopaedic clinic. Most of the population at least once seek medical attention for low back ache. Magnetic Resonance Imaging (MRI) is a non invasive, commonly used diagnosing modality and accurate in diagnosing pathology causing low back ache. To classify and quantify the causes of low back pain referred to radiology department by MRI. Patients with back pain referred to radiology department were subjected to single MRI scan after ruling out any contraindications using the following sequences: T1W Turbo Spin Echo, T2W Turbo Spin Echo, Gradient-echo, Myelogram and short TI inversion recovery (STIR), in all imaging planes. Gadolinium enhanced T1W turbo spin echo sequence was used wherever necessary. Data were analysed using Excel 2007, SPSS 14, Students t-test. Degenerative disc diseases were the commonest pathology followed by congenital and traumatic lesions. Neoplastic lesions were the least common. Commonest herniation type being the disc bulge (79%) followed by disc protrusion (15%), disc extrusion (6%) and disc sequestration (<1%). The posterolateral disc herniation as the commonest and foraminal the least. Sacralisation was the most common congenital spinal anomaly, followed by lumbar scoliosis and perineural cyst. There is no sex difference in disc protrusion but male preponderance in disc extrusion with subligmentous extrusion. MRI is useful in classifying the spinal lesions which again influences the treatment modality and clinical outcome. Degenerative disc disease is the single most common category which accounts for most the Low Back Ache for which a preventing strategy should be drafted.

  7. A media player causes clinically significant telemetry interference with implantable loop recorders.

    PubMed

    Thaker, Jay P; Patel, Mehul B; Shah, Ashok J; Liepa, Valdis V; Jongnarangsin, Krit; Thakur, Ranjan K

    2009-03-01

    The implantable loop recorder is a useful diagnostic tool for intermittent cardiovascular symptoms because it can automatically record arrhythmias as well as a patient-triggered ECG. Media players have been shown to cause telemetry interference with pacemakers. Telemetry interference may be important in patients with implantable loop recorders because capturing a patient-triggered ECG requires a telemetry link between a hand-held activator and the implanted device. The purpose of this study was to determine if a media player causes interference with implantable loop recorders. Fourteen patients with implantable loop recorders underwent evaluation for interference with a 15 GB third generation iPod (Apple, Inc.) media player. All patients had the Reveal Plus (Medtronic, Inc.) implantable loop recorder. We tested for telemetry interference on the programmer by first establishing a telemetry link with the loop recorder and then, the media player was placed next to it, first turned off and then, on. We evaluated for telemetry interference between the activator and the implanted device by placing the activator over the device (normal use) and the media player next to it, first turned off and then, on. We made 5 attempts to capture a patient-triggered ECG by depressing the activator switch 5 times while the media player was off or on. Telemetry interference on the programmer screen, consisting of either high frequency spikes or blanking of the ECG channel was seen in all patients. Telemetry interference with the activator resulted in failure to capture an event in 7 patients. In one of these patients, a green indicator light on the activator suggested that a patient-triggered event was captured, but loop recorder interrogation did not show a captured event. In the remaining 7 patients, an event was captured and appropriately recognized by the device at least 1 out of 5 times. A media player playing in close proximity to an implanted loop recorder may interfere with

  8. Silicone granuloma from ruptured breast implants as a cause of cervical lymphadenopathy.

    PubMed

    Borghol, K; Gallagher, G; Skelly, B L

    2016-09-01

    A 56-year-old woman with a 10-year history of bilateral silicone breast implants presented to the ear, nose and throat outpatient clinic with a 2-month history of a right-sided neck lump. She was found to have a 1.3cm supraclavicular lymph node that gave the clinical impression of being reactive. Ultrasonography guided fine needle aspiration was inconclusive and initial review of subsequent computed tomography failed to identify a cause. This was followed by excisional biopsy of the lymph node, which revealed a silicone granuloma that was linked to a ruptured right-sided breast implant placed ten years previously. This case highlights the importance for otolaryngologists to consider silicone granuloma among the differential diagnoses of cervical lymphadenopathy in patients with a history of silicone breast implants. Recognising this differential diagnosis could avoid undue anxiety for patient and clinician regarding more serious pathology.

  9. External beam radiotherapy boosts to reduce the impact caused by edema in prostate permanent seed implants

    NASA Astrophysics Data System (ADS)

    Yue, Ning; Mori, Jonathan; Nath, Ravinder; Heron, Dwight E.; Saiful Huq, M.

    2006-05-01

    In prostate permanent seed implants, it has been shown that edema caused by the surgical procedure decreases dose coverage and hence may reduce treatment efficacy. This reduction in treatment efficacy has been characterized by an increase in tumour cell survival, and biomathematical models have been developed to calculate the tumour cell survival increases in seed implanted prostates of different edema magnitudes and durations. External beam boosts can be utilized to neutralize the negative impact of edema so that originally desired treatment efficacy can be achieved. In this study, a linear quadratic model is used to determine fractionation sizes of the external beam boosts for both 125I and 103Pd seed implants. Calculations were performed for prostates of different edema magnitudes and durations, and for tumour cells of different repair rates and repopulation rates.

  10. Construction and modeling of a reconfigurable MRI coil for lowering SAR in patients with deep brain stimulation implants.

    PubMed

    Golestanirad, Laleh; Iacono, Maria Ida; Keil, Boris; Angelone, Leonardo M; Bonmassar, Giorgio; Fox, Michael D; Herrington, Todd; Adalsteinsson, Elfar; LaPierre, Cristen; Mareyam, Azma; Wald, Lawrence L

    2017-02-15

    Post-operative MRI of patients with deep brain simulation (DBS) implants is useful to assess complications and diagnose comorbidities, however more than one third of medical centers do not perform MRIs on this patient population due to stringent safety restrictions and liability risks. A new system of reconfigurable magnetic resonance imaging head coil composed of a rotatable linearly-polarized birdcage transmitter and a close-fitting 32-channel receive array is presented for low-SAR imaging of patients with DBS implants. The novel system works by generating a region with low electric field magnitude and steering it to coincide with the DBS lead trajectory. We demonstrate that the new coil system substantially reduces the SAR amplification around DBS electrodes compared to commercially available circularly polarized coils in a cohort of 9 patient-derived realistic DBS lead trajectories. We also show that the optimal coil configuration can be reliably identified from the image artifact on B1(+) field maps. Our preliminary results suggest that such a system may provide a viable solution for high-resolution imaging of DBS patients in the future. More data is needed to quantify safety limits and recommend imaging protocols before the novel coil system can be used on patients with DBS implants.

  11. Allergic reaction to vanadium causes a diffuse eczematous eruption and titanium alloy orthopedic implant failure.

    PubMed

    Engelhart, Sally; Segal, Robert J

    2017-04-01

    Allergy as a cause of adverse outcomes in patients with implanted orthopedic hardware is controversial. Allergy to titanium-based implants has not been well researched, as titanium is traditionally thought to be inert. We highlight the case of a patient who developed systemic dermatitis and implant failure after surgical placement of a titanium alloy (Ti6Al4V) plate in the left foot. The hardware was removed and the eruption cleared in the following weeks. The plate and screws were submitted for metal analysis. The elemental composition of both the plate and screws included 3 major elements-titanium, aluminum, and vanadium-as well as trace elements. Metal analysis revealed that the plate and screws had different microstructures, and electrochemical studies demonstrated that galvanic corrosion could have occurred between the plate and screws due to their different microstructures, contributing to the release of vanadium in vivo. The patient was patch tested with several metals including components of the implant and had a positive patch test reaction only to vanadium trichloride. These findings support a diagnosis of vanadium allergy and suggests that clinicians should consider including vanadium when patch testing patients with a suspected allergic reaction to vanadium-containing implants.

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

    PubMed

    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. CT-negative, MRI GRE-positive primary motor cortex contusion causing isolated foot drop

    PubMed Central

    Tucker, Alexander M.; Niu, Tianyi; Nagasawa, Daniel T.; Everson, Richard; Sedighim, Shaina; Buitrago Blanco, Manuel M.

    2016-01-01

    Background: Isolated acute foot drop due to traumatic brain injury is exceedingly rare and is often misdiagnosed during initial evaluation. Here, we present the case of a patient who presented with left foot drop after falling off a bicycle. Case Description: The patient is a 55-year-old male who was mountain biking when he fell, hit his head, and lost consciousness. Neurologic examination of the left leg revealed foot drop, no sensory deficits, and 3+ reflexes at the knee and ankle with clonus. Electroencephalography, computed tomography (CT) of the head, magnetic resonance imaging (MRI) of the lumbar spine, and CT of the lower extremities were all negative. Only MRI of the brain with a gradient echo sequence revealed microhemorrhages focused around the right precentral gyrus. The patient underwent physical therapy, and by 3 months had regained full strength in his left leg. Conclusion: Central causes of foot drop are exceptionally rare, however, they should be considered in all cases of post-traumatic dorsiflexion paresis. The key to the accurate diagnosis is a high index of suspicion as well as thorough and careful physical examination including reflex and sensory testing. Selective imaging modalities such as MRI or CT can then be used to verify the diagnosis. PMID:27904756

  14. The Safety of Using Body-Transmit MRI in Patients with Implanted Deep Brain Stimulation Devices

    PubMed Central

    Kahan, Joshua; Papadaki, Anastasia; White, Mark; Mancini, Laura; Yousry, Tarek; Zrinzo, Ludvic; Limousin, Patricia; Hariz, Marwan; Foltynie, Tom; Thornton, John

    2015-01-01

    Background Deep brain stimulation (DBS) is an established treatment for patients with movement disorders. Patients receiving chronic DBS provide a unique opportunity to explore the underlying mechanisms of DBS using functional MRI. It has been shown that the main safety concern with MRI in these patients is heating at the electrode tips – which can be minimised with strict adherence to a supervised acquisition protocol using a head-transmit/receive coil at 1.5T. MRI using the body-transmit coil with a multi-channel receive head coil has a number of potential advantages including an improved signal-to-noise ratio. Study outline We compared the safety of cranial MRI in an in vitro model of bilateral DBS using both head-transmit and body-transmit coils. We performed fibre-optic thermometry at a Medtronic ActivaPC device and Medtronic 3389 electrodes during turbo-spin echo (TSE) MRI using both coil arrangements at 1.5T and 3T, in addition to gradient-echo echo-planar fMRI exposure at 1.5T. Finally, we investigated the effect of transmit-coil choice on DBS stimulus delivery during MRI. Results Temperature increases were consistently largest at the electrode tips. Changing from head- to body-transmit coil significantly increased the electrode temperature elevation during TSE scans with scanner-reported head SAR 0.2W/kg from 0.45°C to 0.79°C (p<0.001) at 1.5T, and from 1.25°C to 1.44°C (p<0.001) at 3T. The position of the phantom relative to the body coil significantly impacted on electrode heating at 1.5T; however, the greatest heating observed in any position tested remained <1°C at this field strength. Conclusions We conclude that (1) with our specific hardware and SAR-limited protocol, body-transmit cranial MRI at 1.5T does not produce heating exceeding international guidelines, even in cases of poorly positioned patients, (2) cranial MRI at 3T can readily produce heating exceeding international guidelines, (3) patients with ActivaPC Medtronic systems are safe

  15. The Safety of Using Body-Transmit MRI in Patients with Implanted Deep Brain Stimulation Devices.

    PubMed

    Kahan, Joshua; Papadaki, Anastasia; White, Mark; Mancini, Laura; Yousry, Tarek; Zrinzo, Ludvic; Limousin, Patricia; Hariz, Marwan; Foltynie, Tom; Thornton, John

    2015-01-01

    Deep brain stimulation (DBS) is an established treatment for patients with movement disorders. Patients receiving chronic DBS provide a unique opportunity to explore the underlying mechanisms of DBS using functional MRI. It has been shown that the main safety concern with MRI in these patients is heating at the electrode tips - which can be minimised with strict adherence to a supervised acquisition protocol using a head-transmit/receive coil at 1.5T. MRI using the body-transmit coil with a multi-channel receive head coil has a number of potential advantages including an improved signal-to-noise ratio. We compared the safety of cranial MRI in an in vitro model of bilateral DBS using both head-transmit and body-transmit coils. We performed fibre-optic thermometry at a Medtronic ActivaPC device and Medtronic 3389 electrodes during turbo-spin echo (TSE) MRI using both coil arrangements at 1.5T and 3T, in addition to gradient-echo echo-planar fMRI exposure at 1.5T. Finally, we investigated the effect of transmit-coil choice on DBS stimulus delivery during MRI. Temperature increases were consistently largest at the electrode tips. Changing from head- to body-transmit coil significantly increased the electrode temperature elevation during TSE scans with scanner-reported head SAR 0.2W/kg from 0.45°C to 0.79°C (p<0.001) at 1.5T, and from 1.25°C to 1.44°C (p<0.001) at 3T. The position of the phantom relative to the body coil significantly impacted on electrode heating at 1.5T; however, the greatest heating observed in any position tested remained <1°C at this field strength. We conclude that (1) with our specific hardware and SAR-limited protocol, body-transmit cranial MRI at 1.5T does not produce heating exceeding international guidelines, even in cases of poorly positioned patients, (2) cranial MRI at 3T can readily produce heating exceeding international guidelines, (3) patients with ActivaPC Medtronic systems are safe to be recruited to future fMRI experiments

  16. Causes and correction of dissatisfaction after implantation of presbyopia-correcting intraocular lenses

    PubMed Central

    Gibbons, Allister; Ali, Tayyeba K; Waren, Daniel P; Donaldson, Kendall E

    2016-01-01

    Purpose The purpose of this study was to assess the causes and possible solutions for patient dissatisfaction after the implantation of presbyopia-correcting intraocular lenses (IOLs). Methods This study was a retrospective review of clinical records. All patients who were seen between January 2009 and December 2013 whose primary reason for consultation was dissatisfaction with visual performance after presbyopia-correcting IOL implantation were included in the study. A single treating physician, who determined the most probable cause of dissatisfaction, decided which interventions to pursue following the initial consultation. Results Data from 74 eyes of 49 patients were analyzed. The most common cause for complaint was blurry or foggy vision both for distance and near (68%). Complaints were most frequently attributed to residual refractive error (57%) and dry eye (35%). The most common interventions pursued were treatment of refractive error with glasses or contact lenses (46%) and treatment for dry eye (24%). Corneal laser vision correction was done in 8% of eyes; 7% required an IOL exchange. After the interventions, 45% of patients had completed resolution of symptoms, 23% of patients were partially satisfied with the results, and 32% remained completely dissatisfied with the final results. Conclusion The most identifiable causes of dissatisfaction after presbyopia-correcting IOL implantation are residual refractive error and dry eye. Most patients can be managed with conservative treatment, though a significant number of patients remained unsatisfied despite multiple measures. PMID:27784985

  17. Optimization of Scan Time in MRI for Total Hip Prostheses: SEMAC Tailoring for Prosthetic Implants Containing Different Types of Metals.

    PubMed

    Deligianni, X; Bieri, O; Elke, R; Wischer, T; Egelhof, T

    2015-12-01

    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. Müller 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. Five of the most common total hip prostheses have been investigated in vitro. Tailored SEMAC protocols - in terms of

  18. [Effect of vibration caused by time-varying magnetic fields on diffusion-weighted MRI].

    PubMed

    Ogura, Akio; Maeda, Fumie; Miyai, Akira; Hayashi, Kohji; Hongoh, Takaharu

    2006-04-20

    Diffusion-weighted images (DWIs) with high b-factor in the body are often used to detect and diagnose cancer at MRI. The echo planar imaging (EPI) sequence and high motion probing gradient pulse are used at diffusion weighted imaging, causing high table vibration. The purpose of this study was to assess whether the diffusion signal and apparent diffusion coefficient (ADC) values are influenced by this vibration because of time-varying magnetic fields. Two DWIs were compared. In one, phantoms were fixed on the MRI unit's table transmitting the vibration. In the other, phantoms were supported in air, in the absence of vibration. The phantoms called "solution phantoms" were made from agarose of a particular density. The phantoms called "jelly phantoms" were made from agarose that was heated. The diffusion signal and ADC value of each image were compared. The results showed that the signal of DWI units using the solution phantom was not affected by vibration. However, the signal of DWI and ADC were increased in the low-density jelly phantom as a result of vibration, causing the jelly phantom to vibrate. The DWIs of vibrating regions such as the breast maybe be subject to error. A countermeasure seems to be to support the region adequately.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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 micromolding 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.

  20. A rare cause of cyanosis and hypoxia that should not be forgotten after implantable cardioverter defibrillator implantation.

    PubMed

    Canpolat, Uğur; Bahadır, Nihan; Şahiner, Levent; Aytemir, Kudret

    2017-09-01

    Transvenous pacemaker or implantable cardioverter defibrillator (ICD) implantation procedures are usually performed under local anesthetic, and prilocaine is the most common agent to be used. The data regarding methemoglobinemia after cardiac device implantation are scarce. Thus, presently described is the case of a 47-year-old female patient with arrhythmogenic right ventricular cardiomyopathy/dysplasia who underwent ICD implantation for secondary prophylaxis and developed cyanosis as a result of prilocaine-associated methemoglobinemia. Prilocaine was administered during the procedure. To our knowledge, this is the second case in the literature presenting methemoglobinemia due to local anesthetic after transvenous cardiac device implantation.

  1. Fungal endophthalmitis caused by Paecilomyces variotii, in an immunocompetent patient, following intraocular lens implantation.

    PubMed

    Anita, K B; Fernandez, V; Rao, R

    2010-01-01

    We report the case of a 70-year-old man who was admitted for anterior endophthalmitis following an intraocular lens implantation. He had developed a fluffy growth resembling a fungal mass on the iris of the right eye. The mass was removed and sent for fungal studies to our department. Direct microscopy revealed hyphae. Further studies helped identify the fungus to belong to genus Paecilomyces. This is a rare case of fungal endophthalmitis caused by Paecilomyces variotii in an immunocompetent person.

  2. Revision of unicompartmental knee arthroplasty: implants used and causes of failure.

    PubMed

    Mozella, Alan de Paula; Borges Gonçalves, Felipe; Osterno Vasconcelos, Jansen; de Araújo Barros Cobra, Hugo Alexandre

    2014-01-01

    to determine the causes of unicondylar knee arthroplasty failures, as well as identify the implants used and the need of bone grafting in patients undergoing revision UKA in Center of Knee Surgery at the Instituto Nacional de Traumatologia e Ortopedia (INTO) in the period between January 1990 and January 2013. a retrospective analysis of the medical documentation and imaging, determining the cause of failure of UKA and the time of its occurrence, as well as prosthetic components implanted during the review and the need for bone grafting. in this study, 27 UKA failures in 26 patients were included. Collapse of one or more components was the main cause of failure, occurring in 33% of patients. Aseptic failure was identified in 30% of cases, progression of osteoarthrosis in 15%, infection and pain 7% each, and osteolysis and polyethylene failure in 4% each. Early failure occurred in 41% of all revisions of UKA and late failure in 59%. 23 patients have undergone revision of UK. in 35% of revisions the use of bone grafting was needed in tibial area; in 3 cases we needed allograft from Tissue Bank. We did not use metal increase in any of the revision. In one patient we used implant constraint for instability.

  3. Revision of unicompartmental knee arthroplasty: implants used and causes of failure☆

    PubMed Central

    Mozella, Alan de Paula; Borges Gonçalves, Felipe; Osterno Vasconcelos, Jansen; de Araújo Barros Cobra, Hugo Alexandre

    2014-01-01

    Objective to determine the causes of unicondylar knee arthroplasty failures, as well as identify the implants used and the need of bone grafting in patients undergoing revision UKA in Center of Knee Surgery at the Instituto Nacional de Traumatologia e Ortopedia (INTO) in the period between January 1990 and January 2013. Methods a retrospective analysis of the medical documentation and imaging, determining the cause of failure of UKA and the time of its occurrence, as well as prosthetic components implanted during the review and the need for bone grafting. Results in this study, 27 UKA failures in 26 patients were included. Collapse of one or more components was the main cause of failure, occurring in 33% of patients. Aseptic failure was identified in 30% of cases, progression of osteoarthrosis in 15%, infection and pain 7% each, and osteolysis and polyethylene failure in 4% each. Early failure occurred in 41% of all revisions of UKA and late failure in 59%. 23 patients have undergone revision of UK. Conclusion in 35% of revisions the use of bone grafting was needed in tibial area; in 3 cases we needed allograft from Tissue Bank. We did not use metal increase in any of the revision. In one patient we used implant constraint for instability. PMID:26229792

  4. Fracture and migration of implantable venous access port catheters: Cause analysis and management of 4 cases.

    PubMed

    Xiao, Shu-ping; Xiong, Bin; Chu, Jun; Li, Xiao-fang; Yao, Qi; Zheng, Chuan-sheng

    2015-10-01

    This study aimed to investigate the causes and managements of the fractures and migrations of the implantable venous access port catheter (IVAPC). The fracture or migration of IVAPC occurred in 4 patients who were treated between May 2012 and January 2014 in Union Hospital, Wuhan, China. The port catheter leakage was found in 2 cases during drug infusion. Catheters that dislodged to the superior vena cava and right atrium were confirmed by port angiogram. The two dislodged catheters were successfully retrieved by interventional procedures. Catheter fracture occurred in two cases during port removal. One catheter was eventually removed from the subclavian vein through right clavicle osteotomy and subclavian venotomy, and the other removed by external jugular venotomy. Flushing the port in high pressure and injury of the totally implantable venous access port (TIVP) during implantation are usually responsible for catheter displacement. Interventional retrieval procedure can be used if the catheter dislodges to the vena cava and right atrium. Catheter fracture may occur during removal if clipping syndrome occurs or the catheter is sutured very tight during implantation.

  5. Evaluation of the susceptibility artifacts and tissue injury caused by implanted microchips in dogs on 1.5 T magnetic resonance imaging.

    PubMed

    Saito, Miyoko; Ono, Shin; Kayanuma, Hideki; Honnami, Muneki; Muto, Makoto; Une, Yumi

    2010-05-01

    Performing magnetic resonance imaging (MRI) in patients with a metallic implant raises concern over the potential complications, including susceptibility artifacts, implant migration, and heat injury. The purpose of this study was to investigate these complications in dogs with implanted microchips by evaluating MR images and the histopathological changes after 1.5 Tesla (T) MRI. Five dogs underwent microchip implantation in the cervicothoracic area. One month later, the area was imaged using 1.5T MRI in three dogs. The microchips were removed surgically together with the surrounding tissue in all dogs. There was significant signal loss and image distortion over a wide range around the area where the microchip was implanted. This change was consistent with susceptibility artifacts, which rendered the affected area including the spinal cord undiagnostic. The artifact was more extensive in T2*-weighted images (gradient-echo) and less extensive in proton density-weighted images (fast spin-echo with short echo time). Histopathologically, all microchips were well-encapsulated with granulation tissue, and there were no evidence of migration of microchips. Cell debris and a moderate number of degenerated cells with fibrin were seen in the inner layer of the granulation tissue in each dog that underwent MRI. These changes were very subtle and did not seem to be clinically significant. The results of this study suggest that, in 1.5T MRI, susceptibility artifacts produced by implanted microchips can be marked, although the dogs with implants appeared to be scanned safely.

  6. Peri-implant bone loss caused by occlusal overload: repair of the peri-implant defect following correction of the traumatic occlusion. A case report.

    PubMed

    Tawil, Georges

    2008-01-01

    The purpose of this case report is to demonstrate the relation between occlusal overload and peri-implant bone loss and the reversal of the situation after removal of the offending forces. The placement of an unstable removable prosthesis on 3 well-integrated implants that had been stable for 9 years caused noticeable bone loss after 6 months. The elimination of the traumatic occlusion reversed the situation, and a remarkable healing of the peri-implant tissue occurred until the pretrauma condition was nearly restored. The condition has been stable for the past 4 years.

  7. Cerebral embolization during percutaneous valve implantation does not occur during balloon inflation valvuloplasty: prospective diffusion-weighted brain MRI study.

    PubMed

    Astarci, Parla; Price, Joel; Glineur, David; D'Hoore, William; Kefer, Joelle; Elkhoury, Gébrine; Grandin, Cécile; Vanoverschelde, Jean-Louis

    2013-01-01

    The study aim was to define the timing of cerebral embolization events during transcatheter aortic valve implantation (TAVI), and to determine if events were more closely associated with valve implantation or with balloon inflation. Between January 2008 and November 2011, a total of 114 patients underwent TAVI at the author's institution. Of these patients, 44 had previously undergone imaging before and after TAVI, and were included in the study (26 transfemoral (TF); 18 transapical (TA)). Eleven patients who had only balloon valvuloplasty (BV) during the same period were included, as were 22 patients who had open aortic valve replacement (AVR), as controls. All 77 patients underwent neurological examination, and all had cerebral MRIs before and after their procedures. Fifty of the 77 patients who underwent postprocedural MRI had new cerebral lesions, as follows: 24/26 (92%) in TF patients; 17/18 (94%) in TA patients; 3/11 (27%) in BV patients; and 6/22 (27%) in AVR patients (TF and TA versus BV and AVR, p < 0.0001). The mean number and volume of embolic lesions per patient were respectively 5.4/438 mm3 for TF, 11.6/3414 mm3 for TA, 0.7/46 mm3 for BV, and 0.4/48 mm3 for AVR (TF versus TA and BV versus AVR, p = NS; TF and TA versus BV and AVR, p < 0.0001). No association was found between either the EuroSCORE or patient age and the number of events. In the present study, an incidence of silent cerebral embolic lesions after TAVI was identified which was significantly higher than that for BV or AVR. This indicated an association of embolism with valve implantation rather than with balloon inflation.

  8. Visual fatigue caused by watching 3DTV: an fMRI study

    PubMed Central

    2015-01-01

    The objective of this study is to observe the visual fatigue caused by watching 3DTV using the method of functional magnetic resonance imaging (fMRI). The data of fMRI during three kinds of visual stimulation tasks were obtained from twenty subjects. At first, blood-oxygen-level dependent (BOLD) signal changes during stimuli of checkerboard task were compared before and after one-hour watching 3D/2DTV, and subjective evaluation was conducted based on the questionnaire simultaneously. Then 3D and 2D images were used to stimulate healthy individuals to measure brain activities that correlated with stereoscopic vision. Finally, the relationship between front or back depth of field images and visual fatigue was investigated. The results reveal that the 3D group shows more significant differences of brain activities in BA8, BA17, BA18 and BA19 than the 2D group during the checkerboard stimulation. BA5, BA6, BA7 and BA8 were testified to have close relationship with stereoscopic perception via the 2D/3D images stimulation. Furthermore, the front depth of field image was proven to impose a more serious impact on visual fatigue than the back one. These conclusions are useful for healthy and reasonable 3DTV watching as well as properly designing of 3D scenes. PMID:25603496

  9. MRI-induced heating of selected thin wire metallic implants-- laboratory and computational studies-- findings and new questions raised.

    PubMed

    Bassen, H; Kainz, W; Mendoza, G; Kellom, T

    2006-01-01

    We performed experiments and computer modeling of heating of a cardiovascular stent and a straight, thin wire by RF fields in a 1.5 T MRI birdcage coil at 64 MHz. We used ASTM F2182-02a standard and normalized results to 4 W/kg whole body average. We used a rectangular saline-gel filled phantom and a coiled, double stent (Intracoil by ev3 Inc) 11 cm long. The stent had thin electrical insulation except for bare ends (simulating drug eluting coating). The stent and phantom were placed close to the wall of the RF Coil and had approximately 0.5 degrees C initial temperature rise at the ends (local SAR = 320 W/kg). We exposed a wire (24.1 cm, 0.5 mm diameter) with 0.5 mm insulation and saw an 8.6 degrees C temperature rise (local SAR = 5,680 W/kg) at the bare ends. All heating was within 1 mm3 of the ends, so the position of our fiber optic temperature probe was critical for repeatability. Our computational study used finite difference time domain software with a thermodynamics solver. We modeled a coiled bare-wire stent as a spiral with a rectangular cross section and found a maximum increase of 0.05 degrees C induced at the tips for plane wave exposures. A maximum local SAR of up to 200 W/kg occurred in a volume of only 8 x 10(-3) mm. We developed improved computational exposure sources-- optimized birdcage coils and quasi-MRI fields that may eliminate the need to model an RF coil. We learned that local (point) SAR (initial linear temperature rise) is the most reliable indicator of the maximum heating of an implant. Local SAR depends greatly on implant length, insulation and shape, and position in the MRI coil. Accurate heating must be measured with sensors or software having millimeter resolution. Many commercially available fiber optic temperature probes do meet this requirement.

  10. Implanted depleted uranium fragments cause soft tissue sarcomas in the muscles of rats.

    PubMed Central

    Hahn, Fletcher F; Guilmette, Raymond A; Hoover, Mark D

    2002-01-01

    In this study, we determined the carcinogenicity of depleted uranium (DU) metal fragments containing 0.75% titanium in muscle tissues of rats. The results have important implications for the medical management of Gulf War veterans who were wounded with DU fragments and who retain fragments in their soft tissues. We compared the tissue reactions in rats to the carcinogenicity of a tantalum metal (Ta), as a negative foreign-body control, and to a colloidal suspension of radioactive thorium dioxide ((232)Th), Thorotrast, as a positive radioactive control. DU was surgically implanted in the thigh muscles of male Wistar rats as four squares (2.5 x 2.5 x 1.5 mm or 5.0 x 5.0 x 1.5 mm) or four pellets (2.0 x 1.0 mm diameter) per rat. Ta was similarly implanted as four squares (5.0 x 5.0 x 1.1 mm) per rat. Thorotrast was injected at two sites in the thigh muscles of each rat. Control rats had only a surgical implantation procedure. Each treatment group included 50 rats. A connective tissue capsule formed around the metal implants, but not around the Thorotrast. Radiographs demonstrated corrosion of the DU implants shortly after implantation. At later times, rarifactions in the radiographic profiles correlated with proliferative tissue responses. After lifetime observation, the incidence of soft tissue sarcomas increased significantly around the 5.0 x 5.0 mm squares of DU and the positive control, Thorotrast. A slightly increased incidence occurred in rats implanted with the 2.5 x 2.5 mm DU squares and with 5.0 x 5.0 mm squares of Ta. No tumors were seen in rats with 2.0 x 1.0 mm diameter DU pellets or in the surgical controls. These results indicate that DU fragments of sufficient size cause localized proliferative reactions and soft tissue sarcomas that can be detected with radiography in the muscles of rats. PMID:11781165

  11. Implanted depleted uranium fragments cause soft tissue sarcomas in the muscles of rats.

    PubMed

    Hahn, Fletcher F; Guilmette, Raymond A; Hoover, Mark D

    2002-01-01

    In this study, we determined the carcinogenicity of depleted uranium (DU) metal fragments containing 0.75% titanium in muscle tissues of rats. The results have important implications for the medical management of Gulf War veterans who were wounded with DU fragments and who retain fragments in their soft tissues. We compared the tissue reactions in rats to the carcinogenicity of a tantalum metal (Ta), as a negative foreign-body control, and to a colloidal suspension of radioactive thorium dioxide ((232)Th), Thorotrast, as a positive radioactive control. DU was surgically implanted in the thigh muscles of male Wistar rats as four squares (2.5 x 2.5 x 1.5 mm or 5.0 x 5.0 x 1.5 mm) or four pellets (2.0 x 1.0 mm diameter) per rat. Ta was similarly implanted as four squares (5.0 x 5.0 x 1.1 mm) per rat. Thorotrast was injected at two sites in the thigh muscles of each rat. Control rats had only a surgical implantation procedure. Each treatment group included 50 rats. A connective tissue capsule formed around the metal implants, but not around the Thorotrast. Radiographs demonstrated corrosion of the DU implants shortly after implantation. At later times, rarifactions in the radiographic profiles correlated with proliferative tissue responses. After lifetime observation, the incidence of soft tissue sarcomas increased significantly around the 5.0 x 5.0 mm squares of DU and the positive control, Thorotrast. A slightly increased incidence occurred in rats implanted with the 2.5 x 2.5 mm DU squares and with 5.0 x 5.0 mm squares of Ta. No tumors were seen in rats with 2.0 x 1.0 mm diameter DU pellets or in the surgical controls. These results indicate that DU fragments of sufficient size cause localized proliferative reactions and soft tissue sarcomas that can be detected with radiography in the muscles of rats.

  12. Small temporal pole encephalocele: A hidden cause of "normal" MRI temporal lobe epilepsy.

    PubMed

    Toledano, Rafael; Jiménez-Huete, Adolfo; Campo, Pablo; Poch, Claudia; García-Morales, Irene; Gómez Angulo, Juan Carlos; Coras, Roland; Blümcke, Ingmar; Álvarez-Linera, Juan; Gil-Nagel, Antonio

    2016-05-01

    Small temporal pole encephalocele (STPE) can be the pathologic substrate of epilepsy in a subgroup of patients with noninformative magnetic resonance imaging (MRI). Herein, we analyzed the clinical, neurophysiologic, and radiologic features of the epilepsy found in 22 patients with STPE, and the frequency of STPE in patients with refractory focal epilepsy (RFE). We performed an observational study of all patients with STPE identified at our epilepsy unit from January 2007 to December 2014. Cases were detected through a systematic search of our database of RFE patients evaluated for surgery, and a prospective collection of patients identified at the outpatient clinic. The RFE database was also employed to analyze the frequency of STPE among the different clinical subgroups. We identified 22 patients with STPE (11 women), including 12 (4.0%) of 303 patients from the RFE database, and 10 from the outpatient clinic. The median age was 51.5 years (range 29-75) and the median age at seizure onset was 38.5 years (range 15-73). Typically, 12 (80%) of 15 patients with left STPE reported seizures with impairment of language. Among the RFE cases, STPE were found in 9.6% of patients with temporal lobe epilepsy (TLE), and in 0.5% of those with extra-TLE (p = 0.0001). STPEs were more frequent in TLE patients with an initial MRI study reported as normal (23.3%) than in those with MRI-visible lesions (1.4%; p = 0.0002). Stereo-electroencephalography was performed in four patients, confirming the localization of the epileptogenic zone at the temporal pole with late participation of the hippocampus. Long-term seizure control was achieved in four of five operated patients. STPE can be a hidden cause of TLE in a subgroup of patients with an initial report of "normal" MRI. Early identification of this lesion may help to select patients for presurgical evaluation and tailored resection. Wiley Periodicals, Inc. © 2016 International League Against Epilepsy.

  13. Implanted neural electrodes cause chronic, local inflammation that is correlated with local neurodegeneration

    NASA Astrophysics Data System (ADS)

    McConnell, George C.; Rees, Howard D.; Levey, Allan I.; Gutekunst, Claire-Anne; Gross, Robert E.; Bellamkonda, Ravi V.

    2009-10-01

    Prosthetic devices that are controlled by intracortical electrodes recording one's 'thoughts' are a reality today, and no longer merely in the realm of science fiction. However, widespread clinical use of implanted electrodes is hampered by a lack of reliability in chronic recordings, independent of the type of electrodes used. One major hypothesis has been that astroglial scar electrically impedes the electrodes. However, there is a temporal discrepancy between stabilization of scar's electrical properties and recording failure with recording failure lagging by 1 month. In this study, we test a possible explanation for this discrepancy: the hypothesis that chronic inflammation, due to the persistent presence of the electrode, causes a local neurodegenerative state in the immediate vicinity of the electrode. Through modulation of chronic inflammation via stab wound, electrode geometry and age-matched control, we found that after 16 weeks, animals with an increased level of chronic inflammation were associated with increased neuronal and dendritic, but not axonal, loss. We observed increased neuronal and dendritic loss 16 weeks after implantation compared to 8 weeks after implantation, suggesting that the local neurodegenerative state is progressive. After 16 weeks, we observed axonal pathology in the form of hyperphosphorylation of the protein tau in the immediate vicinity of the microelectrodes (as observed in Alzheimer's disease and other tauopathies). The results of this study suggest that a local, late onset neurodegenerative disease-like state surrounds the chronic electrodes and is a potential cause for chronic recording failure. These results also inform strategies to enhance our capability to attain reliable long-term recordings from implantable electrodes in the CNS.

  14. Implanted neural electrodes cause chronic, local inflammation that is correlated with local neurodegeneration.

    PubMed

    McConnell, George C; Rees, Howard D; Levey, Allan I; Gutekunst, Claire-Anne; Gross, Robert E; Bellamkonda, Ravi V

    2009-10-01

    Prosthetic devices that are controlled by intracortical electrodes recording one's 'thoughts' are a reality today, and no longer merely in the realm of science fiction. However, widespread clinical use of implanted electrodes is hampered by a lack of reliability in chronic recordings, independent of the type of electrodes used. One major hypothesis has been that astroglial scar electrically impedes the electrodes. However, there is a temporal discrepancy between stabilization of scar's electrical properties and recording failure with recording failure lagging by 1 month. In this study, we test a possible explanation for this discrepancy: the hypothesis that chronic inflammation, due to the persistent presence of the electrode, causes a local neurodegenerative state in the immediate vicinity of the electrode. Through modulation of chronic inflammation via stab wound, electrode geometry and age-matched control, we found that after 16 weeks, animals with an increased level of chronic inflammation were associated with increased neuronal and dendritic, but not axonal, loss. We observed increased neuronal and dendritic loss 16 weeks after implantation compared to 8 weeks after implantation, suggesting that the local neurodegenerative state is progressive. After 16 weeks, we observed axonal pathology in the form of hyperphosphorylation of the protein tau in the immediate vicinity of the microelectrodes (as observed in Alzheimer's disease and other tauopathies). The results of this study suggest that a local, late onset neurodegenerative disease-like state surrounds the chronic electrodes and is a potential cause for chronic recording failure. These results also inform strategies to enhance our capability to attain reliable long-term recordings from implantable electrodes in the CNS.

  15. MRI

    MedlinePlus

    ... sweatpants and a t-shirt). Certain types of metal can cause blurry images. You will lie on ... placed artificial joints Vascular stents Worked with sheet metal in the past (you may need tests to ...

  16. Review of the principal extra spinal pathologies causing sciatica and new MRI approaches

    PubMed Central

    Ailianou, A; Fitsiori, A; Syrogiannopoulou, A; Toso, S; Viallon, M; Merlini, L; Beaulieu, J Y; Vargas, M I

    2012-01-01

    In this paper we illustrate the principal extraspinal pathologies causing sciatica and new approaches for the study of structures such as the lumbosacral plexus (LSP). Visualisation of the LSP in its entirety is difficult with conventional two-dimensional MRI sequences owing to its oblique orientation. In our institution, we have found that the utilisation of three-dimensional short tau inversion-recovery sampling perfection with application-optimised contrasts using different flip angle evolutions sequence is helpful, allowing multiplanar and maximum intensity projection reconstructions in the coronal oblique plane and curvilinear reformats through the plexus. Diffusion tensor imaging enables the observation of microstructural changes and can be useful in surgical planning. The normal anatomy of the LSP, its different extraspinal pathologies and differential diagnoses are thoroughly presented. PMID:22374280

  17. Stent Implantation for Superior Vena Cava Syndrome of Malignant Cause.

    PubMed

    Büstgens, Felix A; Loose, Reinhard; Ficker, Joachim H; Wucherer, Michael; Uder, Michael; Adamus, Ralf

    2017-02-02

    Purpose The purpose of this paper is the retrospective analysis of endovascular therapy for the treatment of superior vena cava syndrome (SVCS) of malignant cause. This study focuses on the effectiveness of the therapy regarding the duration of remission, symptom control and practicability. Materials and Methods From January 2003 to November 2012, therapeutic implantation of one or more stents was performed in 141 patients suffering from SVCS. The medical history was retrospectively researched using digitalized patient files. If those were incomplete, secondary research was conducted using the cancer registry of the General Hospital Nuremberg, the cancer registry of the tumor center at Friedrich-Alexander-University Erlangen-Nuremberg (FAU) or information given by physicians in private practice. This data was collected using Microsoft Office Excel(®) and statistically analyzed using IBM SPSS Statistics 22(®). Results 168 stents were implanted in 141 patients (median age: 64.6 years; range: 36 - 84), 86 being male and 55 being female. In 121 patients, SVCS was caused by lung cancer (85.8 %), in 9 patients by mediastinal metastasis of an extrathoracic carcinoma (6.4 %), in 3 patients by mesothelioma of the pleura (2.1 %) and in 1 patient by Hodgkin's disease (0.7 %). There was no histological diagnosis in 7 cases (4.9 %). The primary intervention was successful in 138 patients (97.9 %). Immediate thrombosis in the stent occurred in the remaining 3 cases. Recurrence of SVCS was observed in 22 patients (15.6 %), including 5 early and 17 late occlusions. Stent dislocation or breakage was not observed. As expected, the survival after implantation was poor. The median survival was 101 days, and the median occlusion-free survival was 80 days. Conclusion The symptomatic therapy of SVCS with endovascular stents is effective and safe. Despite effective symptom control and a low rate of recurrence, the patients' prognosis is poor. Key Points

  18. Ultrasound images of implanted tumors in nude mice using Sono-CT correlated with MRI appearance

    NASA Astrophysics Data System (ADS)

    Freedman, Matthew T.; Sarcone, Anita; Pirollo, Kathleen F.; Lin, Chin-Shoou; Chang, Esther

    2001-05-01

    Monitoring the effect of novel cancer chemotherapeutic agents in nude mice is now commonly done by external direct measurement and by autopsy. The development of small animal imaging has focused on micro-MRI, micro-CT and micro-PET -- each a highly expensive and highly valuable method. Far less work has been done with ultrasound imaging. We wish to demonstrate a new method of ultrasound imaging of living mice named Sono-CTR, Sono-CTR provides a compound image by combining the images obtained by electronically directing the transducer to scan from multiple angles.

  19. Feasibility of using linearly polarized rotating birdcage transmitters and close-fitting receive arrays in MRI to reduce SAR in the vicinity of deep brain simulation implants.

    PubMed

    Golestanirad, Laleh; Keil, Boris; Angelone, Leonardo M; Bonmassar, Giorgio; Mareyam, Azma; Wald, Lawrence L

    2017-04-01

    MRI of patients with deep brain stimulation (DBS) implants is strictly limited due to safety concerns, including high levels of local specific absorption rate (SAR) of radiofrequency (RF) fields near the implant and related RF-induced heating. This study demonstrates the feasibility of using a rotating linearly polarized birdcage transmitter and a 32-channel close-fit receive array to significantly reduce local SAR in MRI of DBS patients. Electromagnetic simulations and phantom experiments were performed with generic DBS lead geometries and implantation paths. The technique was based on mechanically rotating a linear birdcage transmitter to align its zero electric-field region with the implant while using a close-fit receive array to significantly increase signal to noise ratio of the images. It was found that the zero electric-field region of the transmitter is thick enough at 1.5 Tesla to encompass DBS lead trajectories with wire segments that were up to 30 degrees out of plane, as well as leads with looped segments. Moreover, SAR reduction was not sensitive to tissue properties, and insertion of a close-fit 32-channel receive array did not degrade the SAR reduction performance. The ensemble of rotating linear birdcage and 32-channel close-fit receive array introduces a promising technology for future improvement of imaging in patients with DBS implants. Magn Reson Med 77:1701-1712, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  20. Revision cochlear implantation with different electrodes can cause incomplete electrode insertion and poor performance.

    PubMed

    Shin, Seung-Ho; Park, Sera; Lee, Won Sang; Kim, Hee Nam; Choi, Jae Young

    2013-04-01

    To review our experiences with revision cochlear implantation (CI), to assess revision CI efficacy, and to find factors that cause incomplete electrode insertion. Retrospective chart review of revision CI from 2004 to 2011. Academic tertiary referral center. Twenty-two patients who underwent revision CI. Revision cochlear implant surgery, explanted device analysis, electrode analysis for a newly implanted device, measurement of electrode insertion depth on postoperative radiographic evaluation, and postoperative speech perception test by open-set testing. Surgical outcomes, postoperative performance, and analysis of used electrodes. Approximately 2.7% (22/816) of CI recipients underwent revision surgery. The reasons for revision surgery were device failure (n = 14) and medical reason (n = 8). Cochlear implantation was performed at an average of 4.7 years after initial operation. Seventeen patients underwent revision CI with an electrode that was the same as or similar to the initial one, and all electrodes were fully inserted. Different electrode types were used in the remaining 5 patients. Interestingly, 4 of the 5 had incomplete electrode insertion. Among the 4 patients, 2 had poorer open set sentence scores after revision than after initial surgery. In this study, full electrode insertion was achieved in all cases where the same type of electrode was used during initial and revision CI. In contrast, we noticed incomplete insertion in 4 of 5 patients who had revision electrodes that differed from initial electrodes. While incomplete electrode insertion does not necessitate poor speech performance, some patients with incomplete electrode insertion certainly experience it. Therefore, electrode selection requires circumspection in revision CI. Choosing a thinner electrode for revision CI may reduce the possibility of incomplete electrode insertion.

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

    PubMed

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

    2015-01-01

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

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

    SciTech Connect

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

    2016-06-15

    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.

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

    PubMed

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

    2016-10-01

    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.

  4. Effect of stent implantation on upstream coronary artery compliance--a cause of late plaque rupture?

    PubMed

    Ward, Michael R; Hibi, Kiyoshi; Shaw, James A; Furukawa, Eri; Resnic, Frederic S; Kimura, Kazuo

    2005-09-01

    Stent implantation in the rabbit aorta has been shown to increase vessel wall compliance at the inflow to the stent, but it is uncertain whether similar effects might be seen in the coronary arteries of humans and whether this would have any significant clinical consequences. First, we measured vessel compliance (systolic lumen area--diastolic lumen area/pulse pressure) before, immediately after, and at the 6-month follow-up visit at a site 5 mm upstream of the proximal edge of an implanted coronary stent in patients undergoing coronary intervention using motorized pull-back intravascular ultrasound recordings. Compliance in the upstream segment increased significantly immediately after stenting (before 7.13 +/- 1.49 vs after 10.73 +/- 1.36 mm2/mm Hg, p = 0.03), an effect that was unchanged at 6 months of follow-up (11.84 +/- 2.11 mm2/mm Hg, p = 0.08 vs before stenting). Second, we examined the site of plaque rupture in all patients presenting with an acute coronary syndrome in whom the culprit lesion was in a vessel that had had a stent implanted >12 months previously (n = 31). Plaque rupture was statistically more likely at the inflow to the stent (n = 22) than at other sites within the culprit vessel (n = 9, p <0.01). We conclude that stenting causes an increase in vessel compliance immediately proximal to the stent, and that when a vessel has been previously stented, plaque rupture is most likely to occur at the stent inflow site.

  5. CARDIAC MRI SCAR PATTERNS DIFFER BY GENDER IN AN IMPLANTABLE CARDIOVERTER DEFIBRILLATOR AND CARDIAC RESYNCHRONIZATION COHORT

    PubMed Central

    Loring, Zak; Strauss, David G.; Gerstenblith, Gary; Tomaselli, Gordon F.; Weiss, Robert G.; Wu, Katherine C.

    2013-01-01

    Background Recent meta-analyses suggest that the effectiveness of cardiac devices may differ between genders. Compared to men, women may not benefit as much from implantable defibrillators (ICDs), yet benefit more from cardiac resynchronization therapy (CRT). Myocardial scar burden is associated with increased incidence of appropriate ICD shocks but decreased response to CRT and may explain gender differences in device benefit. Objective To test the hypothesis that the extent of myocardial scar is less in women than men. Methods In 235 patients referred for primary prevention ICDs who underwent cardiac magnetic resonance imaging, we compared scar size by gender. Analyses were performed for all patients (ICD cohort) and those receiving biventricular pacemakers (CRT subgroup). Results In the ICD cohort, women (vs. men) had a higher prevalence of non-ischemic cardiomyopathy (NICM, 64% vs. 39%, p<0.001) which accounted for a smaller overall scar burden (0.5% vs 13%, p<0.01). Likewise, in the CRT subgroup, the higher prevalence of NICM in women (83% vs. 46%, p=0.01) also contributed to a smaller scar size (0 vs 13%, p<0.01). Women also had significantly less scarring of the inferolateral LV wall. Conclusions In a cohort of patients undergoing clinically indicated ICD and CRT, women had less myocardial scar than men. This difference was primarily driven by a higher prevalence of NICM in women. These findings may have important implications for the future study of gender disparities in ICD and CRT outcomes. PMID:23313802

  6. Medial temporal lobe heterotopia as a cause of increased hippocampal and amygdaloid MRI volumes.

    PubMed

    Watson, C; Nielsen, S L; Cobb, C; Burgerman, R; Williamson, B

    1996-10-01

    Magnetic resonance imaging (MRI)-based volumetric measurements of the hippocampus and amygdala are useful in detecting hippocampal and amygdaloid sclerosis in patients with temporal lobe epilepsy. In these pathological entities, volumetric MRI analysis shows the epileptogenic structures to be atrophic when compared to the normal, nonepileptogenic side. Described are 2 patients with increased hippocampal and amygdaloid volumes on the side of seizure onset due to medial temporal lobe heteroto pias. Care must be taken in the interpretation of volumetric MRI data to make certain that asymmetries in hippocampal and amygdaloid measurements are due to atrophy and sclerosis of the abnormal side and not to increased tissue such as heterotopic gray matter.

  7. Inhibition of implantation caused by methylmercury and mercuric chloride in mouse embryos in vivo

    SciTech Connect

    Kajiwara, Yuji; Inouye, Minoru

    1992-10-01

    Methylmercury, an environmental pollutant, produces a wide spectrum of fetotoxic effects in men and laboratory animals. Experimental studies have shown that the exposure to methylmercury in the gestation period causes fetal death, gross malformation, growth retardation of the fetuses, and stillbirth. Although the effects of methylmercury on fetuses have been well documented, only a few experiments have been performed on the embryo toxicity at the early gestation periods. Because the embryos at preimplantation period are known to be highly sensitive to methylmercury in vitro and in vivo, in the present experiment, the embryonic development after implantation was investigated following treatment with methylmercury during the preimplantation period. Since the previous report showed that methylmercury and inorganic mercury were different in their manifestation of toxicity on preimplantation and mercuric chloride on embryos were investigated in vivo in the present study. 22 refs., 3 figs., 3 tabs.

  8. [Urethral injuries secondary to implantation of penile prosthesis. Analysis of the causes, prevention and treatment].

    PubMed

    Vitarelli, Antonio; Divenuto, Lucia; Palminteri, Enzo; Lorusso, Giovanni; Pagliarulo, Arcangelo

    2014-01-01

    Urethral injuries due to penile prosthesis implant represent a rare complication of the intervention to position penile prosthesis, but unfortunately scientific literature about this is poor. This rare complication may occur during surgery and in the postoperative period, both early and late. It recognizes a variety of causes that may include anatomical or functional conditions, for example cavernosal fibrosis or outcomes of inflammations or previous urethral lesions and pathological sensibility due to diabetic neuropathy or other forms of neuropathy including those from spinal cord injury or myelopathy. This review evaluates the possible predisposing conditions, the clinical presentations, and the devices in the surgical procedures to use to minimize the risk of onset of this lesions and the measures to take if they occur.

  9. Sleeping with the fishes: electromagnetic interference causing an inappropriate implantable cardioverter defibrillator shock.

    PubMed

    Knight, Hui Min; Cakebread, Holly Elizabeth; Gajendragadkar, Parag Ravindra; Duehmke, Rudolf Martin

    2014-05-30

    A 60-year-old man with a cardiac defibrillator implanted due to previous ventricular fibrillation arrest and ischaemic cardiomyopathy received a shock while cleaning his fish pond. At the time, his immersed arm was close to a submersed water pump, but the patient was asymptomatic. As a result of the shock he lost consciousness, but collapsed backwards, away from the pond. Interrogation of the device revealed a high-frequency artefact that was sensed by the device and triggered a shock. Device parameters were otherwise normal. Subsequently, the submersed water pump was found to be the source of an external alternating current leak and was identified as the likely cause of the inappropriate shock due to electromagnetic interference (EMI). Awareness of potential sources of EMI along with evaluation of data with a detailed clinical history is warranted in all cases. 2014 BMJ Publishing Group Ltd.

  10. Re-implantation of a degloving amputation of distal index finger caused by fireworks: a case report and literature review.

    PubMed

    Zhang, Q; Cao, X C

    2013-07-01

    Amputations associated with fireworks are customarily treated by stump revision resulting in permanent disability. In this case report, we present an eight-year old boy who suffered an amputation of his right distal index finger at the level of the epiphyseal disk with degloving injury of the amputated finger caused by fireworks. Successful re-implantation was achieved. Two-year follow-up revealed fair cosmesis and acceptable functional and aesthetic recovery though the free distal phalanx had been absorbed completely. Re-implantation of a degloving amputation finger caused by fireworks is possible and can provide good distal soft tissue coverage and recovery of sensory and motor functions.

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

    SciTech Connect

    Soliman, A; Elzibak, A; Fatemi, A; Safigholi, H; Ravi, A; Morton, G; Song, W; Han, D

    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

  12. [Correction of enophthalmos deformity caused by orbital blow-out fractures using medpor implantation].

    PubMed

    Li, Teng; Min, Ren; Lai, Gui

    2005-07-01

    To study the surgical reconstruction for correction of enophthalmos deformity caused by orbital blow-out fractures. From December 1996 to March 2004, 56 cases of enophthalmos deformity caused by orbital blow-out fracture were repaired. There were 37 cases diplopia, 35 cases with worsened visual acuity than pre-trauma. Typical sub-ciliary incision was employed to expose the fractured area. The dissection was done beneath the medial and inferior orbital periosteum. The fracture areas were exposed and the tissues protrusion to maxillary sinus were released through the space between fractured bones. After the medial and inferior orbital walls and orbital floors were exposed,the herniated orbital contents were released and reduced to the orbital cavity. The fractured orbital walls were repaired precisely with Medpor which were fixed to the area beneath the periosteum with 2 plates at least. All 56 cases of enophthalmos deformity caused by orbital blow-out fracture repaired with this technique recovered well and their facial appearance improved greatly. With a follow-up ranged from 2 months to 5 years, the degree of enophthalmos stabilized at within 2 mm, no relapse and other complications occurred. Of 34 patients with diplopia, 27 were improved. Of the 35 cases with worsened visual acuity, 9 were improved with different degree. No diplopia or visual acuity worsening occurred. It is safe and effective to correct the orbital blow-out fractures. The earlier it is repaired, the better the effect will be. Medpor with its advantages like better histocompatibility, easier sculpturing, moderate hardness, lower absorptivity, fewer complications and permanence effect is the preferable implantation material for correcting enophthalmos deformity.

  13. Blood oxygenation level-dependent functional MRI signal turbulence caused by ultrahigh spatial resolution: numerical simulation and theoretical explanation

    PubMed Central

    Chen, Zikuan; Chen, Zeyuan; Calhoun, Vince

    2015-01-01

    High-spatial-resolution functional MRI (fMRI) can enhance image contrast and improve spatial specificity for brain activity mapping. As the voxel size is reduced, an irregular magnetic fieldmap will emerge as a result of less local averaging, and will lead to abnormal fMRI signal evolution with respect to the image acquisition TE. In this article, we report this signal turbulence phenomenon observed in simulations of ultrahigh-spatial-resolution blood oxygenation level-dependent (BOLD) fMRI (voxel size of less than 50 × 50 × 50 μm3). We present a four-level coarse-to-fine multiresolution BOLD fMRI signal simulation. Based on the statistical histogram of an intravoxel fieldmap, we reformulate the intravoxel dephasing summation (a form of Riemann sum) into a new formula that is a discrete Fourier transformation of the intravoxel fieldmap histogram (a form of Lebesgue sum). We interpret the BOLD signal formation by relating its magnitude (phase) to the even (odd) symmetry of the fieldmap histogram. Based on multiresolution BOLD signal simulation, we find that the signal turbulence mainly emerges at the vessel boundary, and that there are only a few voxels (less than 10%) in an ultrahigh-resolution image that reveal turbulence in the form of sparse point noise. Our simulation also shows that, for typical human brain imaging of the cerebral cortex with millimeter resolution, TE < 30 ms and B0 = 3 T, we are unlikely to observe BOLD signal turbulence. Overall, the main causes of voxel signal turbulence include a high spatial resolution, high field, long TE and large vessel. PMID:22927163

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

    PubMed

    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 < 50%, or of an R-wave amplitude < 5.0 mV at 1-month follow-up. The assessment of safety and efficacy was supported by recording of all adverse events, changes in pacing threshold, R-wave sensing, pacing impedances and in 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

  15. Pseudophakic pupillary block caused by pupillary capture after phacoemulsification and in-the-bag AcrySof lens implantation.

    PubMed

    Khokhar, Sudarshan; Sethi, Harinder Singh; Sony, Parul; Sudan, Rajeev; Soni, Ambrish

    2002-07-01

    We describe a 50-year-old patient who developed pupillary block caused by pupillary capture 1 week after uneventful phacoemulsification and implantation of an AcrySof foldable intraocular lens (IOL). The patient had a large but intact capsulorhexis with the haptics lying in the bag; the optic lay in the pupillary area anterior to the capsulorhexis. This case was successfully managed by a neodymium: YAG laser iridotomy, IOL explantation, and subsequent implantation of a poly(methyl methacrylate) posterior chamber IOL. To prevent this complication, we suggest the optic be larger than the capsulorhexis and advocate correct, gentle insertion of the foldable IOL.

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

    SciTech Connect

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

    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

  17. A Novel Operative Procedure for Pelvic Organ Prolapse Utilizing a MRI-Visible Mesh Implant: Safety and Outcome of Modified Laparoscopic Bilateral Sacropexy

    PubMed Central

    Meyberg-Solomayer, Gabriele; Radosa, Julia; Bader, Werner; Schneider, Guenther; Solomayer, Erich

    2015-01-01

    Introduction. Sacropexy is a generally applied treatment of prolapse, yet there are known possible complications of it. An essential need exists for better alloplastic materials. Methods. Between April 2013 and June 2014, we performed a modified laparoscopic bilateral sacropexy (MLBS) in 10 patients using a MRI-visible PVDF mesh implant. Selected patients had prolapse POP-Q stages II-III and concomitant OAB. We studied surgery-related morbidity, anatomical and functional outcome, and mesh-visibility in MRI. Mean follow-up was 7.4 months. Results. Concomitant colporrhaphy was conducted in 1/10 patients. Anatomical success was defined as POP-Q stage 0-I. Apical success rate was 100% and remained stable. A recurrent cystocele was seen in 1/10 patients during follow-up without need for intervention. Out of 6 (6/10) patients with preoperative SUI, 5/6 were healed and 1/6 persisted. De-novo SUI was seen in 1/10 patients. Complications requiring a relaparoscopy were seen in 2/10 patients. 8/10 patients with OAB were relieved postoperatively. The first in-human magnetic resonance visualization of a prolapse mesh implant was performed and showed good quality of visualization. Conclusion. MLBS is a feasible and safe procedure with favorable anatomical and functional outcome and good concomitant healing rates of SUI and OAB. Prospective data and larger samples are required. PMID:25961042

  18. iPad2(R) use in patients with implantable cardioverter defibrillators causes electromagnetic interference: the EMIT Study.

    PubMed

    Kozik, Teri M; Chien, Gianna; Connolly, Therese F; Grewal, Gurinder S; Liang, David; Chien, Walter

    2014-04-10

    Over 140 million iPads(®) have been sold worldwide. The iPad2(®), with magnets embedded in its frame and Smart Cover and 3G cellular data capability, can potentially cause electromagnetic interference in implantable cardioverter defibrillators. This can lead to potentially life-threatening situations in patients. The goal of this study was to determine whether the iPad2(®) can cause electromagnetic interference in patients with implantable cardioverter defibrillators. Twenty-seven patients with implantable cardioverter defibrillators were studied. The iPad2(®) was held at reading distance and placed directly over the device with cellular data capability activated and deactivated. The manufacturers/models of devices and the patients' body mass index were noted. The presence of electromagnetic interference was detected by using a programmer supplied by each manufacturer. Magnet mode with suspension of anti-tachycardia therapy was triggered in 9 (33%) patients. All occurred when the iPad2(®) was placed directly over the device. The cellular data status did not cause interference and no noise or oversensing was noted. There was no significant difference between the mean body mass index of the groups with or without interference. The iPad2(®) can trigger magnet mode in implantable cardioverter defibrillators when laid directly over the device. This is potentially dangerous if patients should develop life-threatening arrhythmias at the same time. As new electronic products that use magnets are produced, the potential risk to patients with implantable defibrillators needs to be addressed.

  19. Electromagnetic interference caused by common surgical energy-based devices on an implanted cardiac defibrillator.

    PubMed

    Paniccia, Alessandro; Rozner, Marc; Jones, Edward L; Townsend, Nicole T; Varosy, Paul D; Dunning, James E; Girard, Guillaume; Weyer, Christopher; Stiegmann, Gregory V; Robinson, Thomas N

    2014-12-01

    Surgical energy-based devices emit energy, which can interfere with other electronic devices (eg, implanted cardiac pacemakers and/or defibrillators). The purpose of this study was to quantify the amount of unintentional energy (electromagnetic interference [EMI]) transferred to an implanted cardiac defibrillator by common surgical energy-based devices. A transvenous cardiac defibrillator was implanted in an anesthetized pig. The primary outcome measure was the average maximum EMI occurring on the implanted cardiac device during activations of multiple different surgical energy-based devices. The EMI transferred to the implanted cardiac device is as follows: traditional bipolar 30 W .01 ± .004 mV, advanced bipolar .004 ± .003 mV, ultrasonic shears .01 ± .004 mV, monopolar Bovie 30 W coagulation .50 ± .20 mV, monopolar Bovie 30 W blend .92 ± .63 mV, monopolar instrument without dispersive electrode .21 ± .07 mV, plasma energy 3.48 ± .78 mV, and argon beam coagulator 2.58 ± .34 mV. Surgeons can minimize EMI on implanted cardiac defibrillators by preferentially utilizing bipolar and ultrasonic devices. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Silicone implant incompatibility syndrome (SIIS): a frequent cause of ASIA (Shoenfeld's syndrome).

    PubMed

    Cohen Tervaert, J W; Kappel, R M

    2013-07-01

    Silicon has a molecular mass of 28 daltons. In nature, silicon is found as silicon dioxide (silica) or in a variety of silicates (e.g., in talc or asbestos). Furthermore, silicon is present in silicones, polymerized siloxanes, which are often used as medical silicones in breast implants. Silicon exposure is associated with different systemic autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, progressive systemic sclerosis, and vasculitis. Remarkably, silicon in silicone-filled breast implants is considered to be safe, not increasing the risk of developing autoimmune diseases. We analyzed the impact of silicone-filled breast implants on the immune system in 32 consecutive patients attending a specialized autoimmunity clinic. All 32 patients had silicone implant incompatibility syndrome and complaints fulfilling the diagnostic criteria of ASIA (autoimmune/inflammatory syndrome induced by adjuvants). Furthermore, in 17 of the 32 patients, a systemic autoimmune disease was diagnosed, and 15 of the 32 patients had an impaired humoral immune system. Patients developed symptoms and signs after long-term follow-up, suggesting that these symptoms and signs started after implant aging and/or rupture. We postulate that silicon in silicone-filled breast implants may increase the risk of developing (auto) immune diseases and immune deficiencies.

  1. How MRI Compatible is 'MRI Compatible'? A Systematic Comparison of Artifacts Caused by Biopsy Needles at 3.0 and 1.5 T

    SciTech Connect

    Penzkofer, Tobias; Peykan, Nilufar; Schmidt, Katja; Krombach, Gabriele; Kuhl, Christiane K.

    2013-12-15

    Purpose: This study was designed to systematically investigate artifacts caused by interventional needles recommended for use in MRI, with focus on field strength, needle/mandrin type, orientation and sequence. Methods: Eight different MRI compatible needles were placed in porcine tissue and examined at 1.5 and 3.0 T with balanced-steady-state-free-precession (B-SSFP) and T1-weighted-spoiled-gradient-echo (T1-SPGR) sequences in different orientations to B{sub 0}. Artifact diameters with regards to the primary, inner, and secondary, outer artifacts were assessed and statistically evaluated. Results: The types and degree of artifacts varied considerably, especially between different mandrin types even for the same needles. Orientation of the needle in the magnetic field was another main contributor to the artifact dimensions. Less important factors were the type of pulse sequence and field strength. Artifacts ranged from 0.7 mm (steel, 0 Degree-Sign , B-SSFP, 3.0 T, inner) to 71.4 mm (nitinol, 90 Degree-Sign , B-SSFP, 1.5 T, outer). Inner artifact diameters in B-SSFP were slightly larger (8.2 {+-} 5.7 mm) than those in T1-SPGR (7.6 {+-} 5.4 mm) and comparable between 1.5 and 3.0 T (e.g., 8.0 vs. 8.4 mm, B-SSFP). Conclusions: Although all were sold as 'MR compatible,' the artifacts differed greatly between needle types, and even more so for different mandrins. The results suggest an empirical approach to the needle choice based on lesion type and approach angle.

  2. Candida spondylitis: Comparison of MRI findings with bacterial and tuberculous causes.

    PubMed

    Lee, Sheen-Woo; Lee, Sang Hoon; Chung, Hye Won; Kim, Min Jee; Seo, Min Jeong; Shin, Myung Jin

    2013-10-01

    Candida spondylitis is relatively uncommon and is usually encountered as an opportunistic infection. We analyzed the MRI characteristics of biopsy-proven cases of Candida spondylitis, and compared the findings with bacterial or tuberculous spondylitis. The study included patients with infectious spondylitis who underwent MRI and biopsy from 1998 to 2011 (60 patients; mean age 56 ± 18 years). MR images were analyzed with respect to the number of involved vertebrae, contrast enhancement pattern, signal intensity of spinal inflammatory masses on T2-weighted imaging, paraspinal abscess size, intervertebral disk destruction, subligamentous spread, and skip lesions. The Fisher exact test and analysis of variance were used for statistical analysis. There were 10 cases of Candida spondylitis, and 29 and 21 cases of bacterial and tuberculous spondylitis, respectively. On MRI, disk destruction was seen in 50%, 93%, and 30% of Candida, bacterial, and tuberculous cases, respectively. Subligamentous spread of infection was noted in 22%, 10%, and 85%. Paraspinal inflammatory masses were seen in 100%, 100%, and 76%, and abscesses in 100%, 66%, and 90%, of Candida, bacterial, and tuberculous cases, respectively. Paraspinal inflammatory masses contained low T2 signal intensity portions in 80%, 21%, and 67%, and skip lesions were seen in 0%, 10%, and 14%, respectively. Small abscesses were noted in 100%, 76%, and 35% of Candida, bacteria, and tuberculosis infections, respectively. Candida involved 2.3 ± 0.4 vertebrae compared with 2.3 ± 0.9 and 3.0 ± 1.7 in bacterial and tuberculous, respectively. Differences in the three groups were statistically significant (p < 0.05) except for the number of involved vertebrae, and skip lesions. Candida spondylitis can be suspected when infectious lesions contain low-signal spinal inflammatory masses on T2-weighted imaging, small paraspinal abscesses, and in immunocompromised patients.

  3. Long-Term Implanted cOFM Probe Causes Minimal Tissue Reaction in the Brain

    PubMed Central

    Hochmeister, Sonja; Asslaber, Martin; Kroath, Thomas; Pieber, Thomas R.; Sinner, Frank

    2014-01-01

    This study investigated the histological tissue reaction to long-term implanted cerebral open flow microperfusion (cOFM) probes in the frontal lobe of the rat brain. Most probe-based cerebral fluid sampling techniques are limited in application time due to the formation of a glial scar that hinders substance exchange between brain tissue and the probe. A glial scar not only functions as a diffusion barrier but also alters metabolism and signaling in extracellular brain fluid. cOFM is a recently developed probe-based technique to continuously sample extracellular brain fluid with an intact blood-brain barrier. After probe implantation, a 2 week healing period is needed for blood-brain barrier reestablishment. Therefore, cOFM probes need to stay in place and functional for at least 15 days after implantation to ensure functionality. Probe design and probe materials are optimized to evoke minimal tissue reaction even after a long implantation period. Qualitative and quantitative histological tissue analysis revealed no continuous glial scar formation around the cOFM probe 30 days after implantation and only a minor tissue reaction regardless of perfusion of the probe. PMID:24621608

  4. Measurement of lattice damage caused by ion-implantation doping of semiconductors.

    NASA Technical Reports Server (NTRS)

    Hunsperger, R. G.; Wolf, E. D.; Shifrin, G. A.; Marsh, O. J.; Jamba, D. M.

    1971-01-01

    Discussion of two new techniques used to measure the lattice damage produced in GaAs by the implantation of 60 keV cadmium ions. In the first method, optical reflection spectra of the ion-implanted samples were measured in the wavelength range from 2000 to 4600 A. The decrease in reflectivity resulting from ion-implantation was used to determine the relative amount of lattice damage as a function of ion dose. The second technique employed the scanning electron microscope. Patterns very similar in appearance to Kikuchi electron diffraction patterns are obtained when the secondary and/or backscattered electron intensity is displayed as a function of the angle of incidence of the electron beam on a single crystal surface. The results of measurements made by both methods are compared with each other and with data obtained by the method of measuring lattice damage by Rutherford scattering of 1 MeV helium ions.

  5. Diffusional kurtosis MRI of the lower leg: changes caused by passive muscle elongation and shortening.

    PubMed

    Filli, Lukas; Kenkel, David; Wurnig, Moritz C; Boss, Andreas

    2016-06-01

    Diffusional kurtosis MRI (DKI) quantifies the deviation of water diffusion from a Gaussian distribution. We investigated the influence of passive elongation and shortening of the lower leg muscles on the DKI parameters D (diffusion coefficient) and K (kurtosis). After approval by the local ethics committee, eight healthy volunteers (age, 29.1 ± 2.9 years) underwent MRI of the lower leg at 3 T. Diffusion-weighted images were acquired with 10 different b values at three ankle positions (passive dorsiflexion 10°, neutral position 0°, passive plantar flexion 40°). Parametrical maps of D and K were obtained by voxel-wise fitting of the signal intensities using a non-linear Levenberg-Marquardt algorithm. D and K were measured in the tibialis anterior, medial and lateral gastrocnemius, and soleus muscles. In the neutral position, D and K values were in the range between 1.66-1.79 × 10(-3) mm(2) /s and 0.21-0.39, respectively. D and K increased with passive shortening, and decreased with passive elongation, which could also be illustrated on the parametrical maps. In dorsiflexion, D (p < 0.01) and K (p = 0.036) were higher in the tibialis anterior than in the medial gastrocnemius. In plantar flexion, the opposite was found for K (p = 0.035). DKI parameters in the lower leg muscles are significantly influenced by the ankle joint position, indicating that the diffusion of water molecules in skeletal muscle deviates from a Gaussian distribution depending on muscle tonus. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Bruxism: its multiple causes and its effects on dental implants - an updated review.

    PubMed

    Lobbezoo, F; Van Der Zaag, J; Naeije, M

    2006-04-01

    There is a growing interest in bruxism, as evidenced by the rapidly increasing number of papers about this subject during the past 5 years. The aim of the present review was to provide an update of two previous reviews from our department (one about the aetiology of bruxism and the other about the possible role of this movement disorder in the failure of dental implants) and to describe the details of the literature search strategies used, thus enabling the readers to judge the completeness of the review. Most studies that were published about the etiology during the past 5 years corroborate the previously drawn conclusions. Similarly, the update of the review about the possible causal relationship between bruxism and implant failure reveals no new points of view. Thus, there is no reason to assume otherwise than that bruxism is mainly regulated centrally, not peripherally, and that there is still insufficient evidence to support or refute a causal relationship between bruxism and implant failure. This illustrates that there is a vast need for well-designed studies to study both the aetiology of bruxism and its purported relationship with implant failure.

  7. Allergic contact stomatitis caused by a titanium nitride-coated implant abutment: a clinical report.

    PubMed

    Lim, Hyun-Pil; Lee, Kwang-Min; Koh, Young-Il; Park, Sang-Won

    2012-10-01

    A patient developed contact mucositis after being treated with a titanium nitride implant abutment. Patch testing disclosed a positive reaction to titanium nitride. After removal of the titanium nitride-coated abutment and placement of an uncoated abutment, all signs and symptoms disappeared. This clinical report suggests that titanium nitride-coated abutments may be a potential allergen in some patients.

  8. Evidence of healing of partial-thickness rotator cuff tears following arthroscopic augmentation with a collagen implant: a 2-year MRI follow-up

    PubMed Central

    Bokor, Desmond John; Sonnabend, David; Deady, Luke; Cass, Ben; Young, Allan; Van Kampen, Craig; Arnoczky, Steven

    2016-01-01

    Summary Background partial-thickness rotator cuff tears frequently enlarge due to increased local strain and often progress to full-thickness tears. Studies suggest the addition of new tendinous tissue to injured cuff tendons would significantly decrease peak strain, possibly protecting against tear progression. The aim of this study was to assess the ability of a highly-porous collagen implant to induce new tissue formation and limit tear progression when placed on the bursal surface of partial-thickness cuff tears. Methods following arthroscopic subacromial decompression, the implant was attached to the bursal surface of the supraspinatus tendon in a prospective series of 13 consecutive patients with intermediate – (3–6 mm) to high-grade (>6 mm) partial – thickness cuff tears (5 articular, 3 bursal, 5 intra-substance). Tendon thickness, defect size, and tendon quality were evaluated using magnetic resonance imaging (MRI) preoperatively and at 3, 6, 12, and 24 months postoperatively. Clinical outcomes were assessed using the Constant and American Shoulder and Elbow Society scores at the same preoperative and follow-up times. All 13 patients completed all follow-up exams (mean length of follow-up 27.0 months, range 23.3–32.0); no patients were lost to follow-up. Results the implant induced significant new tissue formation in all patients by 3 months (mean increase in tendon thickness 2.2 ± 0.26 mm). This tissue matured over time and became radiologically indistinguishable from the underlying tendon. The partial-thickness cuff tears showed consistent filling of the defects, with complete healing in 7 patients at 12 months, and a progressive improvement in tendon quality in the remaining patients. No tear progression was observed by MRI in any of the patients at 24 months. All clinical scores improved significantly over time. At 24 months, 12 of 13 patients (92%) had satisfactory or better results. Conclusions the results of this clinical study demonstrated

  9. An 8-week brain MRI follow-up analysis of rat eosinophilic meningitis caused by Angiostrongylus cantonensis infection.

    PubMed

    Shyu, L Y; Tsai, H H; Lin, D P; Chang, H H; Tyan, Y S; Weng, J C

    2014-09-01

    Early differential diagnosis and timely follow-up are advantageous in the management of Angiostrongylus cantonensis infection. This study aimed to characterize angiostrongyliasis in the rat brain for an 8-week period using magnetic resonance imaging (MRI) with contrast-enhanced T1-weighted images (T1WI), T2-weighted imaging (T2WI), fluid attenuation inversion recovery (FLAIR) and R2 mapping sequences. The data were analysed with Mathematica and Matlab software programs for weekly changes in each brain following the infection of 20, 50, 100 and 300 third-stage larvae (L3), respectively. The results showed that the average subarachnoid space detected by T2WI technique was peaked up to 10% increase of original size on day 35 after 100 or 300 larvae infection, while those infected with 20 or 50 larvae showed less than 4% increase during the entire course of observation. This increase was relevant to the mortality of the infected rats, because those with 100 or 300 larvae infections showed a sharp decrease in survival rate before day 40. After day 40, the average subarachnoid space was decreased, but the average ventricle size was persistently increased, with the highest increase observed in the group infected with 300 larvae on day 56. Furthermore, the R2 mapping mean and R2 mapping size were significantly different between the brains with severe infection (100 and 300 larvae groups together) and those with mild infection (20 and 50 larvae groups together) on day 49, but not on day 35. Our results showed that diagnosis for different quantity of larvae infection using MRI is possible and follow-up characterization is informative in revealing the effects of angiostrongyliasis on different brain areas. In conclusion, our results support the use of MRI as a non-invasive diagnostic technique for eosinophilic meningitis caused by A. cantonensis infection. © 2013 Blackwell Verlag GmbH.

  10. Physiotherapy as a Rare Cause of Twiddler’s Syndrome in a Patient With an Implanted Cardioverter Defibrillator

    PubMed Central

    Schernthaner, Christiana; Danmayr, Franz; Krausler, Richard; Strohmer, Bernhard

    2013-01-01

    A 65-year-old male patient with a history of ischemic cardiomyopathy developed ventricular tachycardia resulting in presyncope. An ICD was indicated for secondary prophylaxis of ventricular tachyarrhythmias. A dual chamber ICD was implanted from the right side because insertion of the device from the left side was unfeasible after surgery of a left subscapularis tendon lesion. ICD implantation and testing of defibrillation threshold were uneventful. During early follow-up a progressive increase of the stimulation threshold was detected. On chest X-ray coiling of both atrial and ventricular leads was noted and caused inadvertently by active shoulder-arm physiotherapy. Complete revision of the ICD system was necessary for restoration of the pacemaker function of the ICD. This unique case highlights important steps for early recognition and prevention of Twiddler’s syndrome that may occur due to physiotherapy treatment even without abnormal manipulations by the patient.

  11. Updating working memory in aircraft noise and speech noise causes different fMRI activations

    PubMed Central

    Sætrevik, Bjørn; Sörqvist, Patrik

    2015-01-01

    The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between “substitution processes,” which involve adding new items to the working memory representation and suppressing old items, and “exclusion processes,” which involve rejecting new items and maintaining an intact memory set. The current findings supported the findings of a previous study by showing that substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, whereas exclusion activated the anterior medial frontal cortex. Moreover, the prefrontal cortex was activated more by substitution processes when exposed to background speech than when exposed to aircraft noise. These results indicate that (a) the prefrontal cortex plays a special role when task-irrelevant materials should be denied access to working memory and (b) that, when compensating for different types of noise, either different cognitive mechanisms are involved or those cognitive mechanisms that are involved are involved to different degrees. PMID:25352319

  12. Updating working memory in aircraft noise and speech noise causes different fMRI activations.

    PubMed

    Saetrevik, Bjørn; Sörqvist, Patrik

    2015-02-01

    The present study used fMRI/BOLD neuroimaging to investigate how visual-verbal working memory is updated when exposed to three different background-noise conditions: speech noise, aircraft noise and silence. The number-updating task that was used can distinguish between "substitution processes," which involve adding new items to the working memory representation and suppressing old items, and "exclusion processes," which involve rejecting new items and maintaining an intact memory set. The current findings supported the findings of a previous study by showing that substitution activated the dorsolateral prefrontal cortex, the posterior medial frontal cortex and the parietal lobes, whereas exclusion activated the anterior medial frontal cortex. Moreover, the prefrontal cortex was activated more by substitution processes when exposed to background speech than when exposed to aircraft noise. These results indicate that (a) the prefrontal cortex plays a special role when task-irrelevant materials should be denied access to working memory and (b) that, when compensating for different types of noise, either different cognitive mechanisms are involved or those cognitive mechanisms that are involved are involved to different degrees.

  13. Intraoperative Electrophysiologic Variations Caused by the Scalar Position of Cochlear Implant Electrodes.

    PubMed

    Mittmann, Philipp; Ernst, Arneborg; Todt, Ingo

    2015-07-01

    The position of cochlear implant (CI) electrodes in the cochlea is fundamental for the interaction between the implant and the neurons of the spiral ganglion. The scalar position of the electrode in the cochlea is assumed to be an important parameter for the clinical outcome. In our study, the intraoperative electrophysiologic characteristics in dependence of the position of CI electrodes in the scala tympani or in the scala vestibuli after scalar change should be determined. The intraoperative impedances and neural response telemetry (NRT) data of 23 patients implanted with a Nucleus Advance Contour (Cochlear Pty, Sydney, Australia) electrode were recorded. One CI surgeon and two radiologists evaluated the electrode array's position independently radiologically by flat-panel tomography. Results from 17 patients with the electrode positioned in the scala tympani and six patients with the electrode changing intraoperatively from the tympanic into the vestibular scala were retrospectively analyzed. We found a statistically significant difference with an NRT threshold-based ratio for the groups. An estimation of the (radiologically confirmed) scalar position based on the NRT ratio was possible retrospectively. The evaluation of specific intraoperative electrophysiologic data allowed separating between a regular and an irregular (i.e., scalar changing) position of CI electrodes. This noninvasive methodology can support the postoperative radiologic evaluation of the CI electrode array position.

  14. Capsular contracture by silicone breast implants: possible causes, biocompatibility, and prophylactic strategies

    PubMed Central

    Steiert, Andreas E; Boyce, Maria; Sorg, Heiko

    2013-01-01

    The most common implanted material in the human body consists of silicone. Breast augmentation and breast reconstruction using silicone-based implants are procedures frequently performed by reconstructive and aesthetic surgeons. A main complication of this procedure continues to be the development of capsular contracture (CC), displaying the result of a fibrotic foreign body reaction after the implantation of silicone. For many years, experimental and clinical trials have attempted to analyze the problem of its etiology, treatment, and prophylaxis. Different theories of CC formation are known; however, the reason why different individuals develop CC in days or a month, or only after years, is unknown. Therefore, we hypothesize that CC formation, might primarily be induced by immunological mechanisms along with other reasons. This article attempts to review CC formation, with special attention paid to immunological and inflammatory reasons, as well as actual prophylactic strategies. In this context, the word “biocompatibility” has been frequently used to describe the overall biological innocuousness of silicone in the respective studies, although without clear-cut definitions of this important feature. We have therefore developed a new five-point scale with distinct key points of biocompatibility. Hence, this article might provide the basis for ongoing discussion in this field to reduce single-publication definitions as well as increase the understanding of biocompatibility. PMID:24324348

  15. Breast Implants: Saline vs. Silicone

    MedlinePlus

    ... be inserted at the same time. If an MRI scan detects an implant rupture but you don't ... require additional, specialized views. You might need routine MRI scans. The Food and Drug Administration recommends monitoring silicone ...

  16. Silicone breast implant rupture: a review

    PubMed Central

    Fowler, Jason D.; Barta, Ruth; Cunningham, Bruce

    2017-01-01

    Silicone breast implants have been in use for nearly 6 decades. In this time they have undergone significant changes in design and use. They have been subject to intense scrutiny with regard to safety and efficacy, including an almost 10 years moratorium on their use. The current generations of implants have been followed via the manufacturer’s Core studies in order to obtain long term data regarding safety and complications. The results of the more recent studies are compiled in this review. Rupture rates are initially very low and begin to increase after 6–8 years of implantation. Implant rupture may be detected by physical exam, ultrasound or magnetic resonance imaging (MRI). The majority of silicone implant ruptures are clinically undetectable. Symptomatic patients may present with capsular contracture, breast lumps or changes in breast shape. The most common cause of implant rupture is instrument damage during placement. Implant rupture may be confined to the peri-prosthetic capsule or may extravasate into the breast tissue. Patients with ruptured implants have been studied closely and the consensus of the literature states there are no health risks associated with implant rupture. Symptomatic patients with ruptured implants should be offered the choice of observation, or explantation and capsulectomy with or without replacement. PMID:28497020

  17. Cardiac MRI and pulmonary MR angiography of sinus venosus defect and partial anomalous pulmonary venous connection in cause of right undiagnosed ventricular enlargement.

    PubMed

    Kafka, Henryk; Mohiaddin, Raad H

    2009-01-01

    Patients may be referred for cardiology assessment because of an enlarged right ventricle (RV) with no cause apparent on echocardiography. Cardiac MRI can contribute to the management of these patients by detecting sinus venosus defect or partial anomalous pulmonary venous connection (PAPVC). We sought to show how often sinus venosus defect or PAPVC was detected on MRI in patients with an enlarged RV without a previously established definite diagnosis. First cardiac MRI scans obtained over a 4-year period in adults with an undiagnosed cause of RV enlargement were searched for the MRI diagnosis of sinus venosus defect or PAPVC. Thirty-seven patients (25 female, 12 male) met the study criteria. Nineteen patients had a cardiac MRI diagnosis of sinus venosus defect, with PAPVC being present in 95% of those patients. All PAPVCs associated with sinus venosus defect were from the right side. Eleven of the 19 patients with sinus venosus defect underwent surgery at our institution. Sinus venosus defect was confirmed in all 11 cases. Of the 37 patients, 36 had PAPVC, which was right-sided in 27 patients (75%), left-sided in seven patients (19.4%), and bilateral in two patients (5.6%). Three patients had scimitar veins. The common defects associated with PAPVC were sinus venosus defect in 18 patients (50%) and secundum atrial septal defect in six patients (17%). This article about cardiac MRI in adults with sinus venosus defect and PAPVC shows that cardiac MRI can reliably detect and quantify these lesions when other methods have not provided a complete diagnosis for the cause of right heart enlargement.

  18. A case of metastatic carcinoma of anal fistula caused by implantation from rectal cancer.

    PubMed

    Takahashi, Rina; Ichikawa, Ryosuke; Ito, Singo; Mizukoshi, Kosuke; Ishiyama, Shun; Sgimoto, Kiichi; Kojima, Yutaka; Goto, Michitoshi; Tomiki, Yuichi; Yao, Takashi; Sakamoto, Kazuhiro

    2015-12-01

    This case involved an 80-year-old man who was seen for melena. Further testing revealed a tubular adenocarcinoma 50 mm in size in the rectum. In addition, an anal fistula was noted behind the anus along with induration. A biopsy of tissue from the external (secondary) opening of the fistula also revealed adenocarcinoma. Nodules suspected of being metastases were noted in both lung fields. The patient was diagnosed with rectal cancer, a cancer arising from an anal fistula, and a metastatic pulmonary tumor, and neoadjuvant chemotherapy was begun. A laparoscopic abdominoperineal resection was performed 34 days after 6 cycles of mFOLFOX-6 therapy. Based on pathology, the rectal cancer was diagnosed as moderately differentiated adenocarcinoma, and this adenocarcinoma had lymph node metastasis (yp T3N2aM1b). There was no communication between the rectal lesion and the anal fistula, and a moderately differentiated tubular adenocarcinoma resembling the rectal lesion was noted in the anal fistula. Immunohistochemical staining indicated that both the rectal lesion and anal fistula were cytokeratin 7 (CK7) (-) and cytokeratin 20 (CK20) (+), and the patient's condition was diagnosed as implantation of rectal cancer in an anal fistula.In instances where an anal fistula develops in colon cancer, cancer implantation in that fistula must also be taken into account, and further testing should be performed prior to surgery.

  19. Mast cells rescue implantation defects caused by c-kit deficiency

    PubMed Central

    Woidacki, K; Popovic, M; Metz, M; Schumacher, A; Linzke, N; Teles, A; Poirier, F; Fest, S; Jensen, F; Rabinovich, G A; Maurer, M; Zenclussen, A C

    2013-01-01

    Various physiologically relevant processes are regulated by the interaction of the receptor tyrosine kinase (c-Kit) and its ligand stem cell factor (SCF), with SCF known to be the most important growth factor for mast cells (MCs). In spite of their traditional role in allergic disorders and innate immunity, MCs have lately emerged as versatile modulators of a variety of physiologic and pathologic processes. Here we show that MCs are critical for pregnancy success. Uterine MCs presented a unique phenotype, accumulated during receptivity and expanded upon pregnancy establishment. KitW-sh/W-sh mice, whose MC deficiency is based on restricted c-Kit gene expression, exhibited severely impaired implantation, which could be completely rescued by systemic or local transfer of wild-type bone marrow-derived MCs. Transferred wild-type MCs favored normal implantation, induced optimal spiral artery remodeling and promoted the expression of MC proteases, transforming growth factor-β and connective tissue growth factor. MCs contributed to trophoblast survival, placentation and fetal growth through secretion of the glycan-binding protein galectin-1. Our data unveil unrecognized roles for MCs at the fetomaternal interface with critical implications in reproductive medicine. PMID:23328669

  20. Proton dose perturbations caused by high-voltage leads from implanted cardioverter defibrillators

    PubMed Central

    Wootton, Landon S.; Polf, Jerimy C.; Peterson, Stephen; Wilkinson, Jeff; Rozner, Marc A.; Balter, Peter A.; Beddar, Sam

    2013-01-01

    An increasing number of patients undergoing proton radiotherapy have cardiac implantable electrical devices (CIEDs). We recently encountered a situation in which a high-voltage coil on a lead from an implanted cardiac defibrillator was located within the clinical treatment volume for a patient receiving proton radiotherapy for esophageal cancer. To study the effects of the lead on the dose delivery we placed a high-Z CIED lead at both the center and the distal edge of a clinical spread-out Bragg peak (SOBP) in a water phantom, in both a stationary position and with the lead moving in a periodic pattern to simulate cardiorespiratory movement. We then calculated planned doses using a commercial proton treatment planning system (TPS) and compared them with the doses delivered in the phantom, measured using radiographic film. Dose profiles from TPS-calculated and measured dose distributions showed large pertubrations in the delivered proton dose in the vicinity of the CIED lead when it was not moving. The TPS predicted perturbations up to 20% and measurements revealed perturbations up to 35%. However, the perturbations were less than 3% when the lead was moving. Greater dose perturbations were seen when the lead was placed at the distal edge of the SOBP than when it was placed in the center of the SOBP. We conclude that although cardiorespiratory motion of the lead mitigates some of the perturbations, the effects of the leads should be considered and steps taken to reduce these effects during the treatment planning process. PMID:22766952

  1. Impact of residual defects caused by extension ion implantation in FinFETs on parasitic resistance and its fluctuation

    NASA Astrophysics Data System (ADS)

    Matsukawa, Takashi; Liu, Yongxun; Mori, Takahiro; Morita, Yukinori; Otsuka, Shintaro; O'uchi, Shin-ichi; Fuketa, Hiroshi; Migita, Shinji; Masahara, Meishoku

    2017-06-01

    The influence of extension doping on parasitic resistance and its variability has been investigated for FinFETs. Electrical characterization of FinFETs and crystallinity evaluation of the doped fin structure are carried out for different fin thicknesses and different donor species for ion implantation, i.e., As and P. Reducing the fin thickness and the use of donor species with a larger mass cause serious degradation in the variability and median value of the parasitic resistance. Crystallinity evaluation by transmission electron microscope reveals that significant crystal defects remain after dopant activation annealing for the cases of smaller fin thickness and the implanted dopant with a larger mass. The unrecovered defects cause serious degradation in the parasitic resistance and its variability. In 1998, he joined the Electrotechnical Laboratory, which is former organization of National Institute of Advanced Industrial Science and Technology (AIST). He has been working on development of front-end process technology, variability issues of the FinFETs and technologies for suppressing the variability. He is now a group leader of the AIST and leads the research on the silicon-based CMOS devices. He is a member of the IEEE Electron Devices Society, and the Japan Society of Applied Physics.

  2. Are "Human Factors" the Primary Cause of Complications in the Field of Implant Dentistry?

    PubMed

    Renouard, Franck; Amalberti, René; Renouard, Erell

    Complications in medicine and dentistry are usually analyzed from a purely technical point of view. Rarely is the role of human behavior or judgment considered as a reason for adverse outcomes. When the role of human factors is considered, these are usually described in general terms rather than specifically identifying the factors responsible for an adverse event. The impact of cognitive and behavioral factors in the explanation of adverse events has been studied in other high-stakes areas such as aviation and nuclear power. Specific protocols have been developed to reduce rates of human error, and, where human error is unavoidable, to lessen its impact. This approach has dramatically reduced the incidence of accidents in these fields. This article aims to review how a similar approach may prove valuable in the reduction of complications in implant dentistry.

  3. Abnormal Magnetic Resonance Imaging Findings in Patients With Sudden Sensorineural Hearing Loss: Vestibular Schwannoma as the Most Common Cause of MRI Abnormality.

    PubMed

    Jeong, Kyung-Hwa; Choi, Jin Woo; Shin, Jung Eun; Kim, Chang-Hee

    2016-04-01

    The etiology of sudden sensorineural hearing loss (SSNHL) remains unclear in most cases. This study aimed to assess abnormal magnetic resonance imaging (MRI) findings in patients with SSNHL and evaluate the value of MRI in identifying the cause of SSNHL.A retrospective analysis of the charts and MRI findings of 291 patients with SSNHL was performed.In 291 patients, MRI abnormality, which was considered a cause of SSNHL, was detected in 13 patients. Vestibular schwannoma involving the internal auditory canal (IAC) and/or cerebellopontine angle was observed in 9 patients. All 9 patients had intrameatal tumors, and 6 of the 9 patients displayed extrameatal extension of their tumors. The tumor was small (<1 cm) or medium-sized (1.1-2.9 cm) in these 6 patients. Intralabyrinthine schwannoma, labyrinthine hemorrhage, IAC metastasis, and a ruptured dermoid cyst were each observed in 1 patient.The most commonly observed MRI abnormality in patients with SSNHL was vestibular schwannoma, and all of the lesions were small or medium-sized tumors involving the IAC.

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

    PubMed

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

    2017-03-21

    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.

  5. Clostridium novyi-NT can cause regression of orthotopically implanted glioblastomas in rats.

    PubMed

    Staedtke, Verena; Bai, Ren-Yuan; Sun, Weiyun; Huang, Judy; Kibler, Kathleen Kazuko; Tyler, Betty M; Gallia, Gary L; Kinzler, Kenneth; Vogelstein, Bert; Zhou, Shibin; Riggins, Gregory J

    2015-03-20

    Glioblastoma (GBM) is a highly aggressive primary brain tumor that is especially difficult to treat. The tumor's ability to withstand hypoxia leads to enhanced cancer cell survival and therapy resistance, but also yields a microenvironment that is in many aspects unique within the human body, thus offering potential therapeutic opportunities. The spore-forming anaerobic bacterium Clostridium novyi-NT(C. novyi-NT) has the ability to propagate in tumor-generated hypoxia, leading to oncolysis. Here, we show that intravenously injected spores of C. novyi-NT led to dramatic tumor destructions and significant survival increases in implanted, intracranial syngeneic F98 and human xenograft 060919 rat GBM models. C. novyi-NT germination was specific and confined to the neoplasm, with sparing of the normal brain parenchyma. All animals tolerated the bacteriolytic treatment, but edema and increased intracranial pressure could quickly be lethal if not monitored and medically managed with hydration and antibiotics. These results provide pre-clinical data supporting the development of this therapeutic approach for the treatment of patients with GBM.

  6. Clostridium novyi-NT can cause regression of orthotopically implanted glioblastomas in rats

    PubMed Central

    Sun, Weiyun; Huang, Judy; Kibler, Kathleen Kazuko; Tyler, Betty M.; Gallia, Gary L.; Kinzler, Kenneth; Vogelstein, Bert; Zhou, Shibin; Riggins, Gregory J.

    2015-01-01

    Glioblastoma (GBM) is a highly aggressive primary brain tumor that is especially difficult to treat. The tumor's ability to withstand hypoxia leads to enhanced cancer cell survival and therapy resistance, but also yields a microenvironment that is in many aspects unique within the human body, thus offering potential therapeutic opportunities. The spore-forming anaerobic bacterium Clostridium novyi-NT(C. novyi-NT) has the ability to propagate in tumor-generated hypoxia, leading to oncolysis. Here, we show that intravenously injected spores of C. novyi-NT led to dramatic tumor destructions and significant survival increases in implanted, intracranial syngeneic F98 and human xenograft 060919 rat GBM models. C. novyi-NT germination was specific and confined to the neoplasm, with sparing of the normal brain parenchyma. All animals tolerated the bacteriolytic treatment, but edema and increased intracranial pressure could quickly be lethal if not monitored and medically managed with hydration and antibiotics. These results provide pre-clinical data supporting the development of this therapeutic approach for the treatment of patients with GBM. PMID:25849940

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

    SciTech Connect

    Frank, Steven J.; Johansen, Mary J.; Martirosyan, Karen S.; Gagea, Mihai; Van Pelt, Carolyn S.; Borne, Agatha; Carmazzi, Yudith; Madden, Timothy

    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

  8. Incidence, Causes, and Impact of In-Hospital Infections After Transcatheter Aortic Valve Implantation.

    PubMed

    Tirado-Conte, Gabriela; Freitas-Ferraz, Afonso B; Nombela-Franco, Luis; Jimenez-Quevedo, Pilar; Biagioni, Corina; Cuadrado, Ana; Nuñez-Gil, Ivan; Salinas, Pablo; Gonzalo, Nieves; Ferrera, Carlos; Vivas, David; Higueras, Javier; Viana-Tejedor, Ana; Perez-Vizcayno, Maria Jose; Vilacosta, Isidre; Escaned, Javier; Fernandez-Ortiz, Antonio; Macaya, Carlos

    2016-08-01

    In-hospital infections (IHI) are one of the most common and serious problems after invasive procedures. Transcatheter aortic valve implantation (TAVI) is an increasingly used alternative to surgery in patients with severe symptomatic aortic stenosis. The aim of this study was to determine the incidence, origin, risk factors, and clinical outcomes of IHI after TAVI. A total of 303 consecutive patients with severe aortic stenosis who underwent transfemoral TAVI were included and followed during a median time of 21 months. We examined the occurrence, types, origin, and timing of infections during hospital stay as well as short- and long-term clinical outcomes according to the occurrence of IHI. A total of 51 patients (17%; 62 infectious episodes) experienced IHI after TAVI. Respiratory and urinary tract infections were the most frequent type of infections (44% and 34%, respectively), followed by surgical site infection (8%) and bloodstream infection (5%). Positive cultures were obtained in 74% of the samples, of which 65% were gram-negative bacilli. Modifiable factors such as bleeding (p = 0.005) and length of coronary care unit stay (p <0.001) were independently associated with an increased infection risk. Patients with IHI had a longer hospital stay (14 vs 6 days, p <0.001), an increased mortality (hazard ratio 2.48, 95% CI 1.45 to 4.23) and readmission rate (hazard ratio 2.0, 95% CI 1.27 to 3.14) during the follow-up. In conclusion, IHI is a frequent complication after TAVI with a significant impact on short- and long-term clinical outcomes. The most important risk factors associated with the development of this complication were modifiable periprocedural aspects. These results underline the importance to implement specific preventive strategies to reduce in-hospital-acquired infections after TAVI.

  9. Heart MRI

    MedlinePlus

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

  10. Digital music players cause interference with interrogation telemetry for pacemakers and implantable cardioverter-defibrillators without affecting device function.

    PubMed

    Webster, Gregory; Jordao, Ligia; Martuscello, Maria; Mahajan, Tarun; Alexander, Mark E; Cecchin, Frank; Triedman, John K; Walsh, Edward P; Berul, Charles I

    2008-04-01

    Concern exists regarding the potential electromagnetic interaction between pacemakers, implantable cardioverter-defibrillators (ICDs) and digital music players (DMPs). A preliminary study reported interference in 50% of patients whose devices were interrogated near Apple iPods. Given the high prevalence of DMP use among young patients, we sought to define the nature of interference from iPods and evaluate other DMPs. Four DMPs (Apple Nano, Apple Video, SanDisk Sansa and Microsoft Zune) were evaluated against pacemakers and ICDs (PM/ICD). Along with continuous monitoring, we recorded a baseline ECG strip, sensing parameters and lead impedance at baseline and for each device. Among 51 patients evaluated (age 6 to 60 years, median 22), there was no interference with intrinsic device function. Interference with the programmer occurred in 41% of the patients. All four DMPs caused programmer interference, including disabled communication between the PM/ICD and programmer, noise in the ECG channel, and lost marker channel indicators. Sensing parameters and lead impedances exhibited no more than baseline variability. When the DMPs were removed six inches, there were no further programmer telemetry interactions. Contrary to a prior report, we did not identify any evidence for electromagnetic interference between a selection of DMPs and intrinsic function of PM/ICDs. The DMPs did sometimes interfere with device-programmer communication, but not in a way that compromised device function. Therefore, we recommend that DMPs not be used during device interrogation, but suggest that there is reassuring counterevidence to mitigate the current high level of concern for interactions between DMPs and implantable cardiac rhythm devices.

  11. Digital Music Players Cause Interference with Interrogation Telemetry for Pacemakers and Implantable Cardioverter-Defibrillators without Affecting Device Function

    PubMed Central

    Webster, Gregory; Jordao, Ligia; Martuscello, Maria; Mahajan, Tarun; Alexander, Mark E.; Cecchin, Frank; Triedman, John K.; Walsh, Edward P.; Berul, Charles I.

    2014-01-01

    Background Concern exists regarding the potential electromagnetic interaction between pacemakers, implantable cardioverter-defibrillators (ICDs) and digital music players (DMPs). A preliminary study reported interference in 50% of patients whose devices were interrogated near Apple iPods. Objective Given the high prevalence of DMP use among young patients, we sought to define the nature of interference from iPods and evaluate other DMPs. Methods Four DMPs (Apple Nano, Apple Video, SanDisk Sansa and Microsoft Zune) were evaluated against pacemakers and ICDs (PM/ICD). Along with continuous monitoring, we recorded a baseline ECG strip, sensing parameters and lead impedance at baseline and for each device. Results Among 51 patients evaluated (age 6 to 60 years, median 22), there was no interference with intrinsic device function. Interference with the programmer occurred in 41% of the patients. All four DMPs caused programmer interference, including disabled communication between the PM/ICD and programmer, noise in the ECG channel, and lost marker channel indicators. Sensing parameters and lead impedance exhibited no more than baseline variability. When the DMPs were removed six inches, there were no further programmer telemetry interactions. Conclusions Contrary to a prior report, we did not identify any evidence for electromagnetic interference between a selection of DMPs and intrinsic function of PM/ICDs. The DMPs did sometimes interfere with device-programmer communication, but not in a way that compromised device function. Therefore, we recommend that DMPs not be used during device interrogation, but suggest that there is reassuring counterevidence to mitigate the current high level of concern for interactions between DMPs and implantable cardiac rhythm devices. PMID:18362020

  12. Magnetic resonance imaging in patients with a subcutaneous implantable cardioverter-defibrillator.

    PubMed

    Keller, Jirí; Neužil, Petr; Vymazal, Josef; Janotka, Marek; Brada, Jirí; Žáček, Radovan; Vopálka, Roman; Weichet, Jirí; Reddy, Vivek Y

    2015-05-01

    Our aim was to evaluate the potential for safely imaging patients with a new type of implantable cardioverter-defibrillator called the subcutaneous implantable cardioverter-defibrillator (S-ICD) in a 1.5 T magnetic resonance imaging (MRI) scanner. With the increasing number of patients with cardiac implantable devices who are indicated for MRI, there is a growing need for establishing MRI compatibility of cardiac implantable devices. Patients with implanted S-ICD systems underwent one or more types of anatomical MRI scans. The S-ICD was programmed off and patients were monitored throughout the imaging procedure. Device function was evaluated pre- and post-scan. Patients were asked to report immediately any pain, torqueing movement, or heating sensation in the area of the pocket or electrode. Fifteen patients underwent a total of 22 examinations at 1.5 T. Scans included brain, spine, knee, and heart. Two patients were re-scanned due to complaints of heating over the can during lumbar scans, which was caused by a thermistor probe placed on the skin to measure skin temperature. All the remaining scans occurred without incident. No evidence of device malfunction was observed. This study is the first to domonstrate the feasibility of exposing S-ICD patients to MRI using the scanning and monitoring protocol described. More data are required to support S-ICD as a MRI conditional device. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Cardiology.

  13. CUSTOM-FIT RADIOLUCENT CRANIAL IMPLANTS FOR NEUROPHYSIOLOGICAL RECORDING AND STIMULATION

    PubMed Central

    Mulliken, Grant H; Bichot, Narcisse P; Ghadooshahy, Azriel; Sharma, Jitendra; Kornblith, Simon; Philcock, Michael; Desimone, Robert

    2015-01-01

    Background Recording and manipulating neural activity in awake behaving animal models requires long-term implantation of cranial implants that must address a variety of design considerations, which include preventing infection, minimizing tissue damage, mechanical strength of the implant, and MRI compatibility. New Method Here we address these issues by designing legless, custom-fit cranial implants using structural MRI-based reconstruction of the skull and that are made from carbon-reinforced PEEK. Results We report several novel custom-fit radiolucent implant designs, which include a legless recording chamber, a legless stimulation chamber, a multi-channel microdrive and a head post. The fit to the skull was excellent in all cases, with no visible gaps between the base of the implants and the skull. The wound margin was minimal in size and showed no sign of infection or skin recession. Comparison with Existing Methods Cranial implants used for neurophysiological investigation in awake behaving animals often employ methyl methacrylate (MMA) to serve as a bonding agent to secure the implant to the skull. Other designs rely on radially extending legs to secure the implant. Both of these methods have significant drawbacks. MMA is toxic to bone and frequently leads to infection while radially extending legs cause the skin to recede away from the implant, ultimately exposing bone and proliferating granulation tissue. Conclusions These radiolucent implants constitute a set of technologies suitable for reliable long-term recording, which minimize infection and tissue damage. PMID:25542350

  14. Histrelin Implant

    MedlinePlus

    ... implant (Supprelin LA) is used to treat central precocious puberty (CPP; a condition causing children to enter puberty too soon, resulting in faster than normal bone growth and development of sexual characteristics) in girls ...

  15. Head MRI

    MedlinePlus

    ... the head; MRI - cranial; NMR - cranial; Cranial MRI; Brain MRI; MRI - brain; MRI - head ... the test, tell your provider if you have: Brain aneurysm clips An artificial heart valves Heart defibrillator ...

  16. Endovascular repair of a perforation of the vena caval wall caused by the retrieval of a Gunther Tulip filter after long-term implantation.

    PubMed

    Morishita, Hiroyuki; Yamagami, Takuji; Matsumoto, Tomohiro; Takeuchi, Yoshito; Sato, Osamu; Nishimura, Tsunehiko

    2011-02-01

    Symptomatic penetration of the inferior vena cava (IVC) wall reportedly occurs in 0.3% of patients in whom a filter has been implanted, and it causes injury to the adjacent structures (Bogue et al. in Pediatr Radiol 39(10):1110-1113, 1; Brzezinski et al. in Burns 32(5):640-643, 2). We succeeded in the endovascular repair of perforation of the IVC wall occurring during the retrieval of a penetrated Gunther tulip vena cava filter (Cook, Bjaeverskov, Denmark) after long-term implantation.

  17. Endovascular Repair of a Perforation of the Vena Caval Wall Caused by the Retrieval of a Gunther Tulip Filter After Long-Term Implantation

    SciTech Connect

    Morishita, Hiroyuki; Yamagami, Takuji; Matsumoto, Tomohiro; Takeuchi, Yoshito; Sato, Osamu; Nishimura, Tsunehiko

    2011-02-15

    Symptomatic penetration of the inferior vena cava (IVC) wall reportedly occurs in 0.3% of patients in whom a filter has been implanted, and it causes injury to the adjacent structures (Bogue et al. in Pediatr Radiol 39(10):1110-1113, 1; Brzezinski et al. in Burns 32(5):640-643, 2). We succeeded in the endovascular repair of perforation of the IVC wall occurring during the retrieval of a penetrated Gunther tulip vena cava filter (Cook, Bjaeverskov, Denmark) after long-term implantation.

  18. RF artifacts caused by metallic implants or instruments which get more prominent at 3 T: an in vitro study.

    PubMed

    Graf, Hansjörg; Lauer, Ulrike A; Berger, Alexander; Schick, Fritz

    2005-04-01

    Metallic devices with high electrical conductivity inside or adjacent to the body might lead to marked alterations of the RF amplitude B1 in the tissue under investigation, especially at increased RF frequency, and if specific conditions for electromagnetic resonance are fulfilled. RF-metal interaction effects were investigated systematically at B0=0.2, 1.5 and 3 T analyzing correlated image artifacts for copper wires (d=1 mm, L=53 and 27 cm), and for following instruments and implants made of titanium or nitinol: biopsy needles, hip prostheses, vascular stents and aneurysm clips. The samples were examined in Gd-DTPA-doped 140 mM NaCl solution using spin-echo (SE) sequences with high readout bandwidth. Automatic transmitter adjustment V(T,auto) and manually reduced transmitter voltage VT were applied in order to detect B1 enhancement. At 0.2 T, beyond the shielding of the luminal region of the stents, no RF effects were observed. At 1.5 T, the copper wires caused distinct RF artifacts. At 3 T, RF artifacts also appeared for the hip prostheses and the biopsy needles. Stents with pronounced luminal shielding at lower field strength revealed marked B1 enhancement close to their outer surface.

  19. Delayed low frequency hearing loss caused by cochlear implantation interventions via the round window but not cochleostomy.

    PubMed

    Rowe, David; Chambers, Scott; Hampson, Amy; Eastwood, Hayden; Campbell, Luke; O'Leary, Stephen

    2016-03-01

    Cochlear implant recipients show improved speech perception and music appreciation when residual acoustic hearing is combined with the cochlear implant. However, up to one third of patients lose their pre-operative residual hearing weeks to months after implantation, for reasons that are not well understood. This study tested whether this "delayed" hearing loss was influenced by the route of electrode array insertion and/or position of the electrode array within scala tympani in a guinea pig model of cochlear implantation. Five treatment groups were monitored over 12 weeks: (1) round window implant; (2) round window incised with no implant; (3) cochleostomy with medially-oriented implant; (4) cochleostomy with laterally-oriented implant; and (5) cochleostomy with no implant. Hearing was measured at selected time points by the auditory brainstem response. Cochlear condition was assessed histologically, with cochleae three-dimensionally reconstructed to plot electrode paths and estimate tissue response. Electrode array trajectories matched their intended paths. Arrays inserted via the round window were situated nearer to the basilar membrane and organ of Corti over the majority of their intrascalar path compared with arrays inserted via cochleostomy. Round window interventions exhibited delayed, low frequency hearing loss that was not seen after cochleostomy. This hearing loss appeared unrelated to the extent of tissue reaction or injury within scala tympani, although round window insertion was histologically the most traumatic mode of implantation. We speculate that delayed hearing loss was related not to the electrode position as postulated, but rather to the muscle graft used to seal the round window post-intervention, by altering cochlear mechanics via round window fibrosis. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Positron emission tomography (PET) attenuation correction artefacts in PET/CT and PET/MRI

    PubMed Central

    Hartung-Knemeyer, V; Forsting, M; Antoch, G; Heusner, T A

    2013-01-01

    Objective: To compare the effect of implanted medical materials on 18F-fludeoxyglucose (18F-FDG) positron emission tomography (PET)/MRI using a Dixon-based segmentation method for MRI-based attenuation correction (MRAC), PET/CT and CT-based attenuation-corrected PET (PETCTAC). Methods: 12 patients (8 males and 4 females; age 58±11 years) with implanted medical materials prospectively underwent whole-body 18F-FDG PET/CT and PET/MRI. CT, MRI and MRAC maps as well as PETCTAC and PETMRAC images were reviewed for the presence of artefacts. Their morphology and effect on the estimation of the 18F-FDG uptake (no effect, underestimation, overestimation compared with non-corrected images) were compared. In PETMRAC images, a volume of interest was drawn in the area of the artefact and in a reference site (contralateral body part); the mean and maximum standardised uptake values (SUVmean; SUVmax) were measured. Results: Of 27 implanted materials (20 dental fillings, 3 injection ports, 3 hip prostheses and 1 sternal cerclage), 27 (100%) caused artefacts in CT, 19 (70%) in T1 weighted MRI and 17 (63%) in MRAC maps. 20 (74%) caused a visual overestimation of the 18F-FDG uptake in PETCTAC, 2 (7%) caused an underestimation and 5 (19%) had no effect. In PETMRAC, 19 (70%) caused spherical extinctions and 8 (30%) had no effect. Mean values for SUVmean and SUVmax were significantly decreased in artefact-harbouring sites (p<0.001). Conclusion: Contrary to PET attenuation correction artefacts in PET/CT, which often show an overestimation of the 18F-FDG uptake, MRAC artefacts owing to implanted medical materials in most cases cause an underestimation. Advances in knowledge: Being aware of the morphology of artefacts owing to implanted medical materials avoids interpretation errors when reading PET/MRI. PMID:23580397

  1. Immediate changes of bone density caused by the implantation of a femoral stem--a DEXA study. Ulf.Leichtle@med.uni-tuebingen.de.

    PubMed

    Leichtle, Ulf G; Leasure, Jeremi; Martini, Franz; Leichtle, Carmen I

    2011-01-01

    Considerable immediate periprosthetic bone density changes after implantation of femoral stems have been observed comparing DEXA measurements taken pre- and post-operatively. This is important in relation to the interpretation of DEXA studies. We analysed these density changes under standardised experimental conditions. Five human femora were implanted with a custom made femoral stem and ten femora with a standard cementless prosthesis. Densitometry was performed at various stages of implantation. Following rasping only slight density changes were noted (-2.7% to +0.7%). Comparing post-implantation and pre-operative measurements, all custom made stems with a proximal press-fit demonstrated clear increases in proximal periprosthetic bone density of +11% and +14%. In contrast, the standard prosthesis with a distal press-fit showed a loss of -5% and -2% in the proximal zones. Measurements following removal of the implants demonstrated hardly any density changes (0% to -4%) compared to the pre-operative measurements. We concluded that compacting of trabecular bone or bone loss due to rasping are not the main causes of density changes. Substantial measuring errors exist. For examination of periprosthetic bone density changes, pre-operative initial measurements should not be used as a baseline for comparison. Studies should commence with an immediate postoperative measurement.

  2. Adhesive arachnoiditis causing cauda equina syndrome in ankylosing spondylitis: CT and MRI demonstration of dural calcification and a dorsal dural diverticulum.

    PubMed

    Bilgen, I G; Yunten, N; Ustun, E E; Oksel, F; Gumusdis, G

    1999-07-01

    We present the radiological features of a 42-year-old man with long-standing inactive ankylosing spondylitis (AS), demonstrating that arachnoiditis is a cause of a cauda equina syndrome (CES) in this disease. CT showed a dorsal arachnoid diverticulum causing scalloped erosion of the laminae, and punctate and curvilinear dural calcification. MRI revealed adhesion and convergence of the cauda equina dorsally into the arachnoid pouch, causing the dural sac to appear empty canal. To the best of our knowledge, dural calcification on CT is a new finding in AS, which may be related to the CES. Our findings support the hypothesis that chronic adhesive arachnoiditis with subsequent loss of meningeal elasticity may be the main cause of CES in AS.

  3. Radio frequency versus susceptibility effects of small conductive implants--a systematic MRI study on aneurysm clips at 1.5 and 3 T.

    PubMed

    Lauer, Ulrike A; Graf, Hansjorg; Berger, Alexander; Claussen, Claus D; Schick, Fritz

    2005-05-01

    Metallic implants cause enlarged artifacts in magnetic resonance (MR) images at higher magnetic fields, B0, due to their magnetic susceptibility. Interactions of conductive material with radio frequency (RF) pulses also change for higher field strengths, B0, due to the frequency dependence of resonance conditions. Systematic measurements on commercial aneurysm clips and simplified copper models were performed in order to investigate both phenomena at 1.5 and 3 T. Six different commercial aneurysm clips made of titanium, straight copper wires and bent copper models were examined in Gd-DTPA-doped water. RF-related effects were measured by adapted 2D and 3D spin-echo sequences. For reliable differentiation from susceptibility-related effects, variable transmitter voltages were applied. In addition, RF-induced heating was controlled by an infrared (IR) camera. At 3 T, a significant RF-induced electric response could be demonstrated for the copper samples and more moderate for one of the commercial clips, dependent on the geometrical structure determining possible resonant RF coupling. Related RF effects could be distinguished from susceptibility artifacts: a signal enhancement at reduced transmitter voltages indicated locally amplified B1-field amplitudes. No significant heating effect could be measured by IR measurements. MR imaging was used to analyze possible RF-induced effects. At 3 T, resonant RF coupling even of small metallic implants has to be considered carefully. Despite a local enhancement of the RF amplitude, no significant RF-induced heating inside the surrounding fluid was found. A direct thermal endangering of patients seems to be unlikely, but extremely high B1-field amplitudes might occur adjacent to the metallic surface with potential nonthermal affection of tissue.

  4. Optogenetic Functional MRI

    PubMed Central

    Lin, Peter; Fang, Zhongnan; Liu, Jia; Lee, Jin Hyung

    2016-01-01

    The investigation of the functional connectivity of precise neural circuits across the entire intact brain can be achieved through optogenetic functional magnetic resonance imaging (ofMRI), which is a novel technique that combines the relatively high spatial resolution of high-field fMRI with the precision of optogenetic stimulation. Fiber optics that enable delivery of specific wavelengths of light deep into the brain in vivo are implanted into regions of interest in order to specifically stimulate targeted cell types that have been genetically induced to express light-sensitive trans-membrane conductance channels, called opsins. fMRI is used to provide a non-invasive method of determining the brain's global dynamic response to optogenetic stimulation of specific neural circuits through measurement of the blood-oxygen-level-dependent (BOLD) signal, which provides an indirect measurement of neuronal activity. This protocol describes the construction of fiber optic implants, the implantation surgeries, the imaging with photostimulation and the data analysis required to successfully perform ofMRI. In summary, the precise stimulation and whole-brain monitoring ability of ofMRI are crucial factors in making ofMRI a powerful tool for the study of the connectomics of the brain in both healthy and diseased states. PMID:27167840

  5. SU-E-J-205: Dose Distribution Differences Caused by System Related Geometric Distortion in MRI-Guided Radiation Treatment System

    SciTech Connect

    Wang, J; Yang, J; Wen, Z; Marshall, S; Court, L; Ibbott, G

    2015-06-15

    Purpose: MRI has superb soft tissue contrast but is also known for geometric distortions. The concerns and uncertainty about MRI’s geometric distortion have contributed to the hesitation of using only MRI for simulation in radiation therapy. There are two major categories of geometric distortion in MRI; system related and patient related. In this presentation, we studied the impact of system-related geometric distortion on dose distribution in a digital body phantom under an MR-Linac environment. Methods: Residual geometric distortion (after built-in geometric correction) was modeled based on phantom measurements of the system-related geometric distortions of a MRI scanner of a combined MR guided Radiation Therapy (MRgRT) system. A digital oval shaped phantom (40×25 cm) as well as one ellipsoid shaped tumor volume was created to simulate a simplified human body. The simulated tumor volume was positioned at several locations between the isocenter and the body surface. CT numbers in HUs that approximate soft tissue and tumor were assigned to the respective regions in the digital phantom. To study the effect of geometric distortion caused by system imperfections, an IMRT plan was optimized with the distorted image set with the B field. Dose distributions were re-calculated on the undistorted image set with the B field (as in MR-Linac). Results: The maximum discrepancies in both body contour and tumor boundary was less than 2 mm, which leads to small dose distribution change. For the target in the center, coverage was reduced from 98.8% (with distortion) to 98.2%; for the other peripheral target coverage was reduced from 98.4% to 95.9%. Conclusion: System related geometric distortions over the 40×25 area were within 2mm and the resulted dosimetric effects were minor for the two tumor locations in the phantom. Patient study will be needed for further investigation. The authors received a corporate research grant from Elekta.

  6. A Case of Ovarian Pregnancy Diagnosed by MRI

    PubMed Central

    Io, Shingo; Hasegawa, Masaaki; Koyama, Takashi

    2015-01-01

    Ovarian pregnancy is a rare form of ectopic pregnancy, causing a great diagnostic challenge. We report a case of ovarian pregnancy in a 42-year-old woman, in whom MRI successfully demonstrated the implantation in the ovary. Transvaginal ultrasonography showed an echogenic mass in the right ovary but failed to demonstrate tubal pregnancy. T2-weighted MR images disclosed a gestational sac structure in the right ovary, which exhibited heterogeneous high intensity intermingled with punctate foci of distinct low intensity. MRI may be a useful tool for diagnosing ovarian pregnancy, by demonstrating a gestational sac in the ovary. PMID:26491583

  7. A Case of Ovarian Pregnancy Diagnosed by MRI.

    PubMed

    Io, Shingo; Hasegawa, Masaaki; Koyama, Takashi

    2015-01-01

    Ovarian pregnancy is a rare form of ectopic pregnancy, causing a great diagnostic challenge. We report a case of ovarian pregnancy in a 42-year-old woman, in whom MRI successfully demonstrated the implantation in the ovary. Transvaginal ultrasonography showed an echogenic mass in the right ovary but failed to demonstrate tubal pregnancy. T2-weighted MR images disclosed a gestational sac structure in the right ovary, which exhibited heterogeneous high intensity intermingled with punctate foci of distinct low intensity. MRI may be a useful tool for diagnosing ovarian pregnancy, by demonstrating a gestational sac in the ovary.

  8. The use of /sup 99/Tc-pyrophosphate for imaging and measuring of calcification caused by implanted polymers

    SciTech Connect

    Cifkova, I.; Sprincl, L.

    1980-11-01

    Pyrophosphate labeled with /sup 99/Tc was evaluated as an indicator of the calcification which occurs after implantation of polymeric materials in rats. Poly(2-hydroxyethyl methacrylate), both porous and homogeneous, had been implanted. /sup 99/Tc pyrophosphate was applied intravenously to rats in intervals from 14 days to 15 months. Scintigraphy, x-ray examination, and histology were carried out. The ratio of specific activity in the capsule around the implant to specific activity in the reference tissue was determined. The cumulation of activity was parallel with the development of calcification as revealed by histology. The method can be used not only in the screening test of new polymeric materials, but also in a quantitative determination of the degree of calcification in general.

  9. Significant Artifact Reduction at 1.5T and 3T MRI by the Use of a Cochlear Implant with Removable Magnet: An Experimental Human Cadaver Study.

    PubMed

    Wagner, Franca; Wimmer, Wilhelm; Leidolt, Lars; Vischer, Mattheus; Weder, Stefan; Wiest, Roland; Mantokoudis, Georgios; Caversaccio, Marco D

    2015-01-01

    Cochlear implants (CIs) are standard treatment for postlingually deafened individuals and prelingually deafened children. This human cadaver study evaluated diagnostic usefulness, image quality and artifacts in 1.5T and 3T magnetic resonance (MR) brain scans after CI with a removable magnet. Three criteria (diagnostic usefulness, image quality, artifacts) were assessed at 1.5T and 3T in five cadaver heads with CI. The brain magnetic resonance scans were performed with and without the magnet in situ. The criteria were analyzed by two blinded neuroradiologists, with focus on image distortion and limitation of the diagnostic value of the acquired MR images. MR images with the magnet in situ were all compromised by artifacts caused by the CI. After removal of the magnet, MR scans showed an unequivocal artifact reduction with significant improvement of the image quality and diagnostic usefulness, both at 1.5T and 3T. Visibility of the brain stem, cerebellopontine angle, and parieto-occipital lobe ipsilateral to the CI increased significantly after magnet removal. The results indicate the possible advantages for 1.5T and 3T MR scanning of the brain in CI carriers with removable magnets. Our findings support use of CIs with removable magnets, especially in patients with chronic intracranial pathologies.

  10. "Power-on resets" in cardiac implantable electronic devices during magnetic resonance imaging.

    PubMed

    Higgins, John V; Sheldon, Seth H; Watson, Robert E; Dalzell, Connie; Acker, Nancy; Cha, Yong-Mei; Asirvatham, Samuel J; Kapa, Suraj; Felmlee, Joel P; Friedman, Paul A

    2015-03-01

    Magnetic resonance imaging (MRI) has been safely performed in some patients with cardiac implantable electronic devices (CIEDs) under careful monitoring and prespecified conditions. Pacemaker-dependent patients are often excluded, partly because of the potential for "power-on reset" (PoR), which can lead to a change from asynchronous to inhibited pacing with consequent inhibition of pacing due to electromagnetic interference during MRI. The purpose of this study was to review risk factors for PoR during MRI. A prospective study was performed between January 2008 and May 2013 in patients with CIEDs undergoing clinically indicated MRI. Eligible patients were not pacemaker dependent. Devices were interrogated before and after MRI, programmed to an asynchronous mode or an inhibition mode with tachyarrhythmia therapies turned off, and reprogrammed to their original settings after MRI. MRI scans (n = 256) were performed in 198 patients with non-MRI-conditional CIEDs between 2008 and 2013 (median age 66 years; interquartile range 57-77 years; 59% men). PoR occurred during 9 MRI scans (3.5%) in 8 patients. PoR was more frequent with Medtronic devices than with other generator brands (n = 9/139 vs 0/117 [6% vs 0%]; P = .005). Devices with PoR were all released before 2002 and were implanted from 1999 to 2004. Effects of PoR included a decrease in heart rate during MRI (n = 4) and transient anomalous battery life indication (n = 1). All devices functioned normally after MRI. PoR occurs infrequently but can cause deleterious changes in pacing mode and heart rate. MRI should not be performed in pacemaker-dependent patients with older at-risk generators. Continuous monitoring during MRI is essential because unrecognized PoR may inhibit pacing or accelerate battery depletion due to high pacing output. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  11. Magnetic Resonance Imaging Compatibility of the Polymer-based Cochlear Implant

    PubMed Central

    Kim, Jin Ho; Min, Kyou Sik; An, Soon Kwan; Jeong, Joon Soo; Jun, Sang Beom; Cho, Min Hyoung; Son, Young-Don; Cho, Zang-Hee

    2012-01-01

    Objectives In this study, we compared the magnetic resonance (MR) image artifacts caused by a conventional metal-based cochlear implant and a newly developed liquid crystal polymer (LCP)-based device. Methods The metal-based cochlear implant system (Nurobiosys Co.) was attached to side of the head of a subject and the LCP-based device was attached to opposite side. In both devices, alignment magnets were removed for safety. Magnetic resonance imaging (MRI) was performed on a widely used 3.0 T and an ultra-high 7.0 T MRI machine. 3.0 and 7.0 T MR images were acquired using T1- and T2*-weighted gradient echo sequences, respectively. Results In the 3.0 T images, the metal-based device on the left side generated the significant amount of artifacts. The MR images in the proximity of the metal package were obscured by the artifacts in both axial and sagittal views. On the other hand, the MR images near the LCP-based device were relatively free from the artifacts and clearly showed the brain structures. 7.0 T MR images showed the more severe distortion in the both sides but the metal-based cochlear implant system caused a much larger obscure area than the LCP-based system. Conclusion The novel LCP-based cochlear implant provides a good MRI compatibility beyond present-day cochlear implants. Thus, MR images can be obtained from the subjects even with the implanted LCP-based neural prosthetic systems providing useful diagnostic information. Furthermore, it will be also useful for functional MRI studies of the auditory perception mechanism after cochlear implantations as well as for positron emission tomography-MRI hybrid imaging. PMID:22701769

  12. A Novel Brain Stimulation Technology Provides Compatibility with MRI

    PubMed Central

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

    2015-01-01

    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. PMID:25924189

  13. MRI and low back pain

    MedlinePlus

    ... cause of the pain cannot be found. An MRI scan is an imaging test that creates detailed pictures ... neck pain often gets better on its own. MRI scans create detailed pictures of your spine. It can ...

  14. Reduction of dark-band-like metal artifacts caused by dental implant bodies using hypothetical monoenergetic imaging after dual-energy computed tomography.

    PubMed

    Tanaka, Ray; Hayashi, Takafumi; Ike, Makiko; Noto, Yoshiyuki; Goto, Tazuko K

    2013-06-01

    The aim of this study was to evaluate the usefulness of hypothetical monoenergetic images after dual-energy computed tomography (DECT) for assessment of the bone encircling dental implant bodies. Seventy-two axial images of implantation sites clipped out from image data scanned using DECT in dual-energy mode were used. Subjective assessment on reduction of dark-band-like artifacts (R-DBAs) and diagnosability of adjacent bone condition (D-ABC) in 3 sets of DECT images-a fused image set (DE120) and 2 sets of hypothetical monoenergetic images (ME100, ME190)-was performed and the results were statistically analyzed. With regards to R-DBAs and D-ABC, significant differences among DE120, ME100, and ME190 were observed. The ME100 and ME190 images revealed more artifact reduction and diagnosability than those of DE120. DECT imaging followed by hypothetical monoenergetic image construction can cause R-DBAs and increase D-ABC and may be potentially used for the evaluation of postoperative changes in the bone encircling implant bodies. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Optimization of dental implantation

    NASA Astrophysics Data System (ADS)

    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.

  16. Reduction of artefacts caused by missing ray-sum data in optical-CT imaging of implants in gel dosimeters

    NASA Astrophysics Data System (ADS)

    Asena, A.; Smith, S. T.; Kairn, T.; Crowe, S. B.; Franich, R. D.; Trapp, J. V.

    2017-05-01

    This study demonstrates the degradation in image quality, and subsequent dose evaluation inaccuracies, that are encountered when an optical-CT system reconstructs an image slice of a gel dosimeter containing an opaque implant, and evaluates the feasibility of a simple correction method to improve the accuracy of radiotherapy dose distribution measurements under these circumstances. MATLAB was used to create a number of different virtual phantoms and treatment plans along with their synthetic projections and reconstructed data sets. The results have illustrated that accurately evaluating 3D gel dose distributions in the vicinity of high-Z interfaces is not possible using the filtered back projection method, without correction, as there are serious artefacts throughout the dose volume that are induced by the missing ray-sum data. Equivalent artefacts were present in physical measurements of irradiated PAGAT gel containers when read by an optical-CT system. An interpolation correction performed prior to reconstruction via the filtered back projection algorithm has been shown to significantly improve dose evaluation accuracy to within approximately 15 mm of the opacity. With careful placement of the implant within the gel sample, and use of the linear interpolation method described in this study, there is the potential for more accurate optical CT imaging of gels containing opaque objects.

  17. Quinolinic acid released from polymeric brain implants causes behavioral and neuroanatomical alterations in a rodent model of Huntington's disease.

    PubMed

    Haik, K L; Shear, D A; Schroeder, U; Sabel, B A; Dunbar, G L

    2000-06-01

    Quinolinic acid (QA) is an N-methyl-d-aspartate agonist that has been shown to produce neurotoxic effects that mimic certain neurodegenerative diseases when administered to laboratory animals. Intrastriatal injections of QA in rats have been used extensively to produce some of the neuropathological and behavioral deficits that are analogous to Huntington's disease (HD). However, acute intrastriatal injections of QA produce symptoms that are not analogous to the progressive nature of HD. Thus far, models using chronic administration of QA that produce HD-like behavioral and neuroanatomical changes have necessitated the use of a relatively bulky and fragile microdialytic pump apparatus. The present study tested an alternative way of chronically administering QA. Specifically, this study tested whether gradual release of QA from ethylene vinylacetate (EVA) polymers could produce symptoms analogous to HD. Rats received either no implants or bilateral intrastriatal implants of polymers with or without QA. Subsequent tests for spontaneous motor activity (SMA), grip strength, balance, and learning ability in a radial-arm-water-maze task revealed QA-induced impairments in balance and learning ability, but did not affect grip strength or SMA. Histological analysis revealed QA-induced enlargement of lateral ventricles, striatal atrophy, and striatal neuronal loss, with relative sparing of NADPH-diaphorase-positive neurons. These results suggest that QA released from polymers can produce behavioral and neuropathological profiles analogous to early stages of HD and that EVA polymers offer a useful means of chronically delivering QA in rodent models of neurodegeneration.

  18. Sodium MRI.

    PubMed

    Ouwerkerk, Ronald

    2011-01-01

    Sodium ((23)Na) imaging has a place somewhere between (1)H-MRI and MR spectroscopy (MRS). Like MRS it potentially provides information on metabolic processes, but only one single resonance of ionic (23)Na is observed. Therefore pulse sequences do not need to code for a chemical shift dimension, allowing (23)Na images to be obtained at high resolutions as compared to MRS. In this chapter the biological significance of sodium in the brain will be discussed, as well as methods for observing it with (23)Na-MRI. Many vital cellular processes and interactions in excitable tissues depend on the maintenance of a low intracellular and high extracellular sodium concentration. Healthy cells maintain this concentration gradient at the cost of energy. Leaky cell membranes or an impaired energy metabolism immediately leads to an increase in cytosolic total tissue sodium. This makes sodium a biomarker for ischemia, cancer, excessive tissue activation, or tissue damage as might be caused by ablation therapy. Special techniques allow quantification of tissue sodium for the monitoring of disease or therapy in longitudinal studies or preferential observation of the intracellular component of the tissue sodium. New methods and high-field magnet technology provide new opportunities for (23)Na-MRI in clinical and biomedical research.

  19. An in vitro study of cartilage-meniscus tribology to understand the changes caused by a meniscus implant.

    PubMed

    Majd, Sara Ehsani; Rizqy, Aditya Iman; Kaper, Hans J; Schmidt, Tannin A; Kuijer, Roel; Sharma, Prashant K

    2017-07-01

    Active lifestyles increase the risk of meniscal injury. A permanent meniscus implant of polycarbonate urethane (PCU) is a promising treatment to postpone/prevent total knee arthroplasty. Study of the changes in articular cartilage tribology in the presence of PCU is essential in developing the optimum meniscus implant. Therefore, a cartilage-meniscus reciprocating, sliding model was developed in vitro, mimicking the stance and swing phases of the gait cycle. The meniscus was further replaced with PCU and surface-modified PCUs (with C18 chains, mono-functional polydimethylsiloxane groups and mono-functional polytetrafluoroethylene groups) to study the changes. The coefficient of friction (COF) was calculated, and cartilage wear was determined and quantified histologically. The cartilage-meniscus sliding resulted in low COF during both stance and swing (0.01< COF <0.12) and low wear of cartilage (scores <1). The cartilage-PCU sliding, during stance, revealed similar low COFs. But during swing, the COFs were high (average ∼1, maximum 1.6), indicating a breakdown in interstitial fluid pressurization lubrication and non-effective activation of the boundary lubrication. This may lead to wear of cartilage in long term. However, under the tested conditions the wear of cartilage against PCUs was not higher than its wear against meniscus, and the cartilage was occasionally damaged. The COF decreased with increasing the contact pressure (as-per a power equation) up to 1MPa. The changes in the surface modification of PCU did not affect PCU's tribological performance. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  20. Adhesions to Mesh after Ventral Hernia Mesh Repair Are Detected by MRI but Are Not a Cause of Long Term Chronic Abdominal Pain

    PubMed Central

    Langbach, Odd; Holmedal, Stein Harald; Grandal, Ole Jacob

    2016-01-01

    Aim. The aim of the present study was to perform MRI in patients after ventral hernia mesh repair, in order to evaluate MRI's ability to detect intra-abdominal adhesions. Materials and Methods. Single-center long term follow-up study of 155 patients operated for ventral hernia with laparoscopic (LVHR) or open mesh repair (OVHR), including analyzing medical records, clinical investigation with patient-reported pain (VAS-scale), and MRI. MRI was performed in 124 patients: 114 patients (74%) after follow-up, and 10 patients referred for late complaints after ventral mesh repair. To verify the MRI-diagnosis of adhesions, laparoscopy was performed after MRI in a cohort of 20 patients. Results. MRI detected adhesions between bowel and abdominal wall/mesh in 60% of the patients and mesh shrinkage in 20–50%. Adhesions were demonstrated to all types of meshes after both LVHR and OVHR with a sensitivity of 70%, specificity of 75%, positive predictive value of 78%, and negative predictive value of 67%. Independent predictors for formation of adhesions were mesh area as determined by MRI and Charlson index. The presence of adhesions was not associated with more pain. Conclusion. MRI can detect adhesions between bowel and abdominal wall in a fair reliable way. Adhesions are formed both after open and laparoscopic hernia mesh repair and are not associated with chronic pain. PMID:26819601

  1. Effects of magnetic resonance imaging on implantable permanent magnets.

    PubMed

    Schneider, M L; Walker, G B; Dormer, K J

    1995-09-01

    Implantable permanent magnets are increasingly used in devices for otolaryngologic applications. It is likely that at least some of the patients with implanted magnets will be in need of magnetic resonance imaging (MRI). The effect of an MRI scan on the magnetic properties of implanted permanent magnets has not been previously demonstrated. Some of the basic concepts and descriptive terminology used in industry regarding permanent magnets are reviewed. Experiments presented show that the MRI scan is capable of demagnetizing permanent magnets. A case history is also presented that demonstrates demagnetizing of an implanted Audiant magnet by an MRI scan.

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

    PubMed

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

    2010-08-01

    To assess the agreement between intraoperative and post-operative dosimetry and to identify factors that influence dose calculations of prostate brachytherapy implants. Patients treated with prostate brachytherapy implants underwent post-operative CT and XMR (combined X-ray and MR) imaging. Dose-volume histograms were calculated from CT, XMR and CT-MR fusion data and compared with intraoperative values for two observers. Multiple linear regression models assessed the influences of intraoperative D90, gland oedema, gland volume, source loss and migration, and implanted activity/volume prostate on post-operative D90. Forty-nine patients were studied. The mean D90 differences (95% confidence limits) between intraoperative and post-operative CT, XMR and CT-MR fusion assessments were: 11 Gy (-22, 45), 18 Gy (-13, 49) and 20 Gy (-17, 58) for Observer 1; and 15 Gy (-34, 63), 13 Gy (-29, 55) and 14 Gy (-27, 54) for Observer 2. Multiple linear regression modelling showed that the observed oedema and intraoperative D90 were significant independent variables for the prediction of post-operative D90 values for both observers using all modalities. This is the first study to report Bland-Altman agreement analysis between intraoperative and post-operative dosimetry. Agreement is poor. Post-operative dosimetry is dependent on the intraoperative D90 and the subjectively outlined gland volume. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

  3. Outcome of penile prosthesis implantation: are malleable prostheses an appropriate treatment option in patients with erectile dysfunction caused by prior radical surgery?

    PubMed

    Sevinc, Cuneyd; Ozkaptan, Orkunt; Balaban, Muhsin; Yucetas, Ugur; Karadeniz, Tahir

    2016-04-26

    The aim of our study was to evaluate the outcome of penile prosthesis implantation in patients with various comorbidities as a cause of erectile dysfunction (ED). The data of 181 patients who underwent surgery between 1998 and 2012 in two centers were evaluated. The mean age of the patients was 52.2 years (range: 31-71 years). The study group contained 162 patients (89.5%) with malleable prostheses and 19 (10.5%) with inflatable implants. All patients were re-evaluated 1 month later to assess prosthesis function and complications, and further re-examinations were performed if needed. Satisfaction was defined as having satisfactory intercourse and happiness with the device in general. The follow-up period was at least 12 months for each patient. The postoperative complication rate was 32% (n = 58). The number of complications with inflatable and malleable prostheses was 7 (3.9%) and 51 (28.1%), respectively. Overall, 21 prostheses (11.6%) had to be removed because of various complications and patient dissatisfaction. Patients with prior radical surgery had higher extraction rates (ƛ = 14.606, P < 0.05, Chi-square test). The main reasons for removal were erosion (n = 11; 6.1%) and infection (n = 3; 2.1%). With respect to satisfaction during intercourse, we found that 104 (57.5%) patients described themselves as very satisfied with the prosthesis, while 21 (11.6%) were unsatisfied. The high explantation rate in patients with prior surgery was remarkable in our study. Our results revealed that a malleable prosthesis should not be the preferred type of implant for patients with prior surgery.

  4. Outcome of penile prosthesis implantation: are malleable prostheses an appropriate treatment option in patients with erectile dysfunction caused by prior radical surgery?

    PubMed Central

    Sevinc, Cuneyd; Ozkaptan, Orkunt; Balaban, Muhsin; Yucetas, Ugur; Karadeniz, Tahir

    2017-01-01

    The aim of our study was to evaluate the outcome of penile prosthesis implantation in patients with various comorbidities as a cause of erectile dysfunction (ED). The data of 181 patients who underwent surgery between 1998 and 2012 in two centers were evaluated. The mean age of the patients was 52.2 years (range: 31–71 years). The study group contained 162 patients (89.5%) with malleable prostheses and 19 (10.5%) with inflatable implants. All patients were re-evaluated 1 month later to assess prosthesis function and complications, and further re-examinations were performed if needed. Satisfaction was defined as having satisfactory intercourse and happiness with the device in general. The follow-up period was at least 12 months for each patient. The postoperative complication rate was 32% (n = 58). The number of complications with inflatable and malleable prostheses was 7 (3.9%) and 51 (28.1%), respectively. Overall, 21 prostheses (11.6%) had to be removed because of various complications and patient dissatisfaction. Patients with prior radical surgery had higher extraction rates (ƛ = 14.606, P < 0.05, Chi-square test). The main reasons for removal were erosion (n = 11; 6.1%) and infection (n = 3; 2.1%). With respect to satisfaction during intercourse, we found that 104 (57.5%) patients described themselves as very satisfied with the prosthesis, while 21 (11.6%) were unsatisfied. The high explantation rate in patients with prior surgery was remarkable in our study. Our results revealed that a malleable prosthesis should not be the preferred type of implant for patients with prior surgery. PMID:27121195

  5. Failure of impedance monitoring to prevent adverse clinical events caused by fracture of a recalled high-voltage implantable cardioverter-defibrillator lead.

    PubMed

    Kallinen, Linda M; Hauser, Robert G; Lee, Ken W; Almquist, Adrian K; Katsiyiannis, William T; Tang, Chuen Y; Melby, Daniel P; Gornick, Charles C

    2008-06-01

    The Medtronic Sprint Fidelis implantable cardioverter-defibrillator high-voltage lead is prone to fracture. The October 2007 safety advisory recommended lead impedance monitoring to aid in identifying lead fractures. The aim of this single-center study was to examine the effectiveness of impedance monitoring for detecting Sprint Fidelis lead failures before they caused adverse clinical events such as inappropriate shocks. Impedance and sensing information were acquired during routine clinic and CareLink follow-up and at the time of lead failure using the Patient Alert, sensing integrity counter, nonsustained episode, and electrogram features in Medtronic pulse generators. Between September 2004 and February 2008, 17 of 514 Sprint Fidelis leads (3.3%) followed up at our center failed between 11 and 35 months after implantation (mean 23.0 +/- 8.0 months). Fifteen of these failures (88%) were caused by pace-sense conductor fractures, and 2 (12%) were caused by high-voltage conductor defects. Twelve of 15 patients (80%) with pace-sense conductor fractures received inappropriate shocks; of these, 4 had no significant increase in lead impedance before they were shocked, 2 were shocked <3 hours after their lead impedances exceeded the 1,000 Omega audible alert threshold, and 2 patients did not hear the alarm. All pace-sense conductor failures whose sensing function could be evaluated (13 of 15) had oversensing based on stored data, and oversensing usually (11 of 13) preceded impedances changes. Impedance monitoring did not prevent inappropriate shocks in two-thirds of our patients. Thus, pace-sense conductor impedance monitoring as currently implemented does not reliably forewarn patients of a lead malfunction. Consequently, patients who have Sprint Fidelis leads remain at risk for adverse clinical events associated with pace-sense conductor fracture.

  6. Case report and brief review of literature on sonographic detection of accidentally implanted wooden foreign body causing persistent sinus

    PubMed Central

    2012-01-01

    Despite advances in imaging techniques, the detection of vegetative foreign bodies in soft tissues remains a difficult and sometimes even a challenging task. Clinical evaluation of such patient may present several months or even years after the initial injury and clinician may fail to elicit an antecedent skin puncture. X-ray examination will miss radiolucent foreign bodies. A 15-year-old boy presented with a draining non-healing sinus at the lateral aspect of his right thigh for 9 months. Musculoskeletal ultrasonography was ordered after ruling out chronic osteomyelitis to detect possible lesions around the thigh. High-frequency linear ultrasonic probe readily detected an elongated foreign body within the vastus lateralis muscle. A long piece of wood was confirmed at surgery. Non-healing sinus with normal finding in radiograph following old trauma should raise the suspicion of implanted radiolucent foreign body/bodies. The role of diagnostic ultrasound as a valuable screening tool for the detection of foreign body is briefly reviewed. PMID:22871025

  7. Evaluation and analysis of graft hypertrophy by means of arthroscopy, biochemical MRI and osteochondral biopsies in a patient following autologous chondrocyte implantation for treatment of a full-thickness-cartilage defect of the knee.

    PubMed

    Niemeyer, Philipp; Uhl, Markus; Salzmann, Gian M; Morscheid, Yannik P; Südkamp, Norbert P; Madry, Henning

    2015-06-01

    Graft hypertrophy represents a characteristic complication following autologous chondrocyte implantation (ACI) for treatment of cartilage defects. Although some epidemiological data suggest that incidence is associated with first-generation ACI using autologous chondrocyte implantation, it has also been reported in other technical modifications of ACI using different biomaterials. Nevertheless, it has not been described in autologous, non-periosteum, implant-free associated ACI. In addition, little is known about histological and T2-relaxation appearance of graft hypertrophy. The present case report provides a rare case of extensive graft hypertrophy following ACI using an autologous spheres technique with clinical progression over time. Detailed clinical, MR tomographic and histological evaluation has been performed, which demonstrates a high quality of repair tissue within the hypertrophic as well as non-hypertrophic transplanted areas of the repair tissue. No expression of collagen type X (a sign of chondrocyte hypertrophy), only slight changes of the subchondral bone and a nearly normal cell-matrix ratio suggest that tissue within the hypertrophic area does not significantly differ from intact and high-quality repair tissue and therefore seems not to cause graft hypertrophy. This is in contrast to the assumption that histological hypertrophy might cause or contribute to an overwhelming growth of the repair tissue within the transplantation site. Data presented in this manuscript might contribute to further explain the etiology of graft hypertrophy following ACI.

  8. Temporal bone histopathology in a case of sensorineural hearing loss caused by superficial siderosis of the central nervous system and treated by cochlear implantation

    PubMed Central

    Nadol, Joseph B.; Adams, Joe C.; O'Malley, Jennifer T.

    2011-01-01

    Objectives To evaluate the histopathology of the temporal bones of a patient with documented superficial siderosis of the central nervous system who underwent right cochlear implantation six years before death. Background Superficial siderosis of the central nervous system is due to chronic or repeated subarachnoid hemorrhage and results in sensorineural deafness in 95% of affected individuals in addition to other neurologic findings. The deposition of hemosiderin in the meninges and around cranial nerves is thought to be causative. There have been no previous reports of temporal bone pathology in this disorder. This 57 year old man developed progressive, bilateral hearing loss starting in his 30's with loss of pure tone thresholds and word recognition. He underwent a right cochlear implant at age 51 with full insertion of the device. Methods The temporal bones and brainstem were fixed in formalin and prepared for histologic study by standard techniques. Special stains, including Gomori stain for iron were performed on sections of the temporal bones and cochlear nucleus. Results There was severe bilateral degeneration of the organ of Corti, spiral ligament, stria vascularis, and spiral ganglion cells. Gomori stain revealed iron deposits within the spiral ligament, stria vascularis and in the subepithelial mesenchymal tissue of the maculae of the vestibular system. Evaluation of the cochlear nucleus revealed iron deposits within glial cells and larger cells, probably macrophages, near the CSF surface. On the right side, the track created by the cochlear implant entered the scala tympani and continued to mm17, as measured from the round window. Discussion and Conclusions This is the first known case of superficial siderosis with documented temporal bone histopathology. Hearing loss was likely caused by severe degeneration of spiral ganglion cells in both ears, despite the presence of remaining hair cells in the middle and apical turns. This was consistent with

  9. MRI after implantation of a novel femoral closure device following intra-arterial catheterisation: implications for subsequent contrast-enhanced MR angiography.

    PubMed

    Mohrs, Oliver K; Petersen, Steffen E; Nowak, Bernd; Kauczor, Hans-Ulrich; Voigtlaender, Thomas

    2010-05-01

    To assess MRI safety aspects and artefacts of a novel femoral artery closure device during contrast-enhanced MR angiography in patients following intra-arterial catheterisation. Ten consecutive patients underwent MRI within 24 h of coronary angiography and placement of a femoral artery closure device. We used a T2-weighted gradient-echo MRI sequence to measure the device-related artefact size in comparison with a phantom image, phase-contrast flow measurement proximal to, at the level of and distal to the device to quantify potential differences in flow velocity and contrast-enhanced 3D gradient-echo MR angiography to differentiate potential femoral artery stenosis from device-related artefacts. The mean size of the oval-shaped artefact was 8.4 x 6.6 mm (+/-1.0 x 0.8 mm) and was almost identical to the maximum artefact size of the phantom measurement (8.3 x 5.7 mm). Device placement did not result in an increased peak velocity (proximal 69 +/- 23 cm/s, at the level of 64 +/- 11 cm/s and distal to the device 63 +/- 12 cm/s, p = 0.67). The mean artefact penetration into the vessel lumen was 0.5 +/- 0.5 mm (percentage vessel narrowing 7.0 +/- 6%; range 0-16%). The MR conditional StarClose femoral artery closure device was used safely within 24 h of deployment at 1.5 T. Despite clip-related artefacts MR angiography will allow for easy differentiation of clip-related artefacts from high-grade atherosclerotic stenosis.

  10. Combined preoperative information using a bullseye plot from speckle tracking echocardiography, cardiac CT scan, and MRI scan: targeted left ventricular lead implantation in patients receiving cardiac resynchronization therapy.

    PubMed

    Bakos, Zoltan; Markstad, Hanna; Ostenfeld, Ellen; Carlsson, Marcus; Roijer, Anders; Borgquist, Rasmus

    2014-05-01

    To evaluate the feasibility and incremental value of using an integrated bullseye model for presenting data from cardiac computed tomography (CT) and magnetic resonance imaging (MRI) in combination with echocardiography evaluation of segmental mechanical delay for guiding optimal left ventricular lead placement in cardiac resynchronization therapy (CRT). Thirty-nine patients (69 ± 9.7 years, 77% male, 82% with LBBB, 54% with ischaemic cardiomyopathy, 82% New York Heart Association classification of heart failure III) eligible for CRT were included. The left ventricular segment with the latest mechanical activation was determined by echocardiography with speckle tracking radial strain. Cardiac CT scan was used for anatomical evaluation of the coronary sinus and its branches. Cardiac MRI was used for evaluation of viability. A composite bullseye plot was constructed, indicating the most appropriate site for left ventricle (LV) lead placement. The latest mechanical delay was in the basal-anterior (3%), basal-inferior (3%), basal-inferolateral (13%), basal-anterolateral (21%), mid-anterior (8%), mid-inferior (3%), mid-inferolateral (34%), and mid-anterolateral (16%) segment. There were on average 2.5 ± 0.8 veins of suitable sizes (≥1.5 mm in diameter). A preoperative combined bullseye plot indicated that in 53% of the patients, there was a matching vein in the segment with the latest mechanical delay. If immediately adjacent segments were included, an optimal placement was possible in 95% of the patients. At 6 months, there was a statistically significant reduction in the left ventricular end systolic volume and the left ventricular ejection fraction was improved (P < 0.01). Presenting data from echocardiography, cardiac CT, and MRI in a combined bullseye plot is both feasible and convenient for indicating the most appropriate site for LV lead placement. An optimal electrode position can be suggested in almost all patients.

  11. Cochlear Implants

    MedlinePlus

    ... Medical Procedures Implants and Prosthetics Cochlear Implants Cochlear Implants Share Tweet Linkedin Pin it More sharing options ... normal ear, ear with hearing loss, and cochlear implant procedure Welcome to the Food and Drug Administration ( ...

  12. Congenital and prolonged adult-onset deafness cause distinct degradations in neural ITD coding with bilateral cochlear implants.

    PubMed

    Hancock, Kenneth E; Chung, Yoojin; Delgutte, Bertrand

    2013-06-01

    Bilateral cochlear implant (CI) users perform poorly on tasks involving interaural time differences (ITD), which are critical for sound localization and speech reception in noise by normal-hearing listeners. ITD perception with bilateral CI is influenced by age at onset of deafness and duration of deafness. We previously showed that ITD coding in the auditory midbrain is degraded in congenitally deaf white cats (DWC) compared to acutely deafened cats (ADC) with normal auditory development (Hancock et al., J. Neurosci, 30:14068). To determine the relative importance of early onset of deafness and prolonged duration of deafness for abnormal ITD coding in DWC, we recorded from single units in the inferior colliculus of cats deafened as adults 6 months prior to experimentation (long-term deafened cats, LTDC) and compared neural ITD coding between the three deafness models. The incidence of ITD-sensitive neurons was similar in both groups with normal auditory development (LTDC and ADC), but significantly diminished in DWC. In contrast, both groups that experienced prolonged deafness (LTDC and DWC) had broad distributions of best ITDs around the midline, unlike the more focused distributions biased toward contralateral-leading ITDs present in both ADC and normal-hearing animals. The lack of contralateral bias in LTDC and DWC results in reduced sensitivity to changes in ITD within the natural range. The finding that early onset of deafness more severely degrades neural ITD coding than prolonged duration of deafness argues for the importance of fitting deaf children with sound processors that provide reliable ITD cues at an early age.

  13. Meta-Analysis of the Relation of Ventricular Arrhythmias to All-Cause Mortality After Implantation of a Left Ventricular Assist Device.

    PubMed

    Makki, Nader; Mesubi, Olurotimi; Steyers, Curtis; Olshansky, Brian; Abraham, William T

    2015-11-01

    Ventricular arrhythmias (VAs) are commonly reported after implantation of left ventricular assist devices (LVADs). Their relation to all-cause mortality and potential risk factors remains unclear. We conducted a meta-analysis of observational studies with the primary objective of evaluating the association of post-LVAD VAs with all-cause mortality at 60, 120, and 180 days. The secondary end point was the association of potential risk factors (cause of cardiomyopathy, indication for LVAD, and history of VA) with mortality in patients with post-LVAD VAs. We searched MEDLINE, Embase, and Cochrane Central from 2001 to 2015. Two reviewers independently searched, selected, and assessed quality of included studies with differences resolved by consensus. Data were collected and analyzed using random- and fixed-effect model, as appropriate, with inverse-variance weighting. Of 2,393 studies identified, 9 observational studies were eligible including 1,179 patients with a mean follow-up of 220 days. Post-LVAD VAs were associated with increased risk of all-cause mortality after adjusting for competing risk factors at 60 days (adjusted odds ratio [OR] 1.91, 95% confidence interval [CI] 1.18 to 3.11, p = 0.001), 120 days (adjusted OR 1.97, 95% CI 1.01 to 3.85, p = 0.05), and 180 days (adjusted OR 2.04, 95% CI 1.01 to 4.15, p = 0.05). Using meta-regression analysis, it was found that only history of VA was a risk factor for mortality after LVAD implantation. In conclusion, post-LVAD VA is associated with an increased risk of all-cause mortality with pre-LVAD VAs acting as a risk factor. This meta-analysis, despite being only hypothesis generating, sets the stage for prospective collection of VA information in a prospective device trial or in the Interagency Registry for Mechanically Assisted Circulatory Support.

  14. Assessing Timing and Causes of Neonatal Lamb Losses in a Bighorn Sheep Ovis canadensis canadensis Herd via Use of Vaginal Implant Transmitters.

    PubMed

    Grigg, Jamin L; Wolfe, Lisa L; Fox, Karen A; Killion, Halcyon J; Jennings-Gaines, Jessica; Miller, Michael W; P Dreher, Brian

    2017-02-13

    We evaluated the use of vaginal implant transmitters (VITs) as a means of detecting, capturing, and radio collaring Rocky Mountain bighorn sheep ( Ovis canadensis canadensis) lambs to estimate survival and to facilitate carcass recovery to assess causes of mortality. We focused on one of several bighorn herds in Colorado, USA, suffering from depressed recruitment that was not preceded by a classic all-age die-off. We captured, radio-collared, diagnosed pregnancy by ultrasound examination, and inserted VITs into 15 pregnant ewes from a herd residing near Granite, Colorado. We were subsequently able to collar a lamb from each of 13 VITs, and two additional lambs opportunistically from ewes without transmitters. As lambs died, we recovered and submitted carcasses for necropsy and laboratory assessment. All lambs captured and one additional lamb (carcass found opportunistically) were dead by about 130 d of age: 11 died of apparent pneumonia (all within 8-10 wk of age), one died from trauma after being kicked or trampled, one was killed by a mountain lion ( Puma concolor ), and three died of starvation likely caused by abandonment after capture. Pneumonic lambs had involvement of Mycoplasma ovipneumoniae and leukotoxigenic Bibersteinia trehalosi . The use of VITs and lamb collars enabled us to efficiently identify pneumonia as the predominant cause of depressed lamb recruitment in this herd; however, we urge care in neonatal lamb handling to minimize abandonment.

  15. Cochlear implantation in superficial siderosis.

    PubMed

    Kim, Chong-Sun; Song, Jae-Jun; Park, Min-Hyun; Kim, Young Ho; Koo, Ja-Won

    2006-08-01

    Superficial siderosis (SS) of the central nervous system has been thought to be a rare condition that generates progressive hearing loss, ataxia, pyramidal signs, and dementia. The main cause of hearing loss by SS is thought to be neuronal. Because there is no histopathologic report of the human temporal bone in SS, there is a debate about the possibility of cochlear involvement. We present a 25-year-old man who was investigated for bilateral progressive sensorineural hearing loss and vestibular failure after head trauma. On brain MRI, SS of the central nervous system was detected. Distortion product otoacoustic emission (DPOAE) and auditory brainstem response (ABR) showed no response on both sides. However, integrity of the eighth nerve was proved by the electrical ABR test on the right side and the patient benefited significantly from cochlear implantation. The sensorineural hearing loss in SS seems to be related to cochlear damage as well as neuronal damage. So, cochlear implantation would be a hearing rehabilitation modality for the sensorineural hearing loss caused by SS.

  16. RESOLUTE PET/MRI Attenuation Correction for O-(2-(18)F-fluoroethyl)-L-tyrosine (FET) in Brain Tumor Patients with Metal Implants.

    PubMed

    Ladefoged, Claes N; Andersen, Flemming L; Kjær, Andreas; Højgaard, Liselotte; Law, Ian

    2017-01-01

    Aim: Positron emission tomography (PET) imaging is a useful tool for assisting in correct differentiation of tumor progression from reactive changes, and the radiolabeled amino acid analog tracer O-(2-(18)F-fluoroethyl)-L-tyrosine (FET)-PET is amongst the most frequently used. The FET-PET images need to be quantitatively correct in order to be used clinically, which require accurate attenuation correction (AC) in PET/MRI. The aim of this study was to evaluate the use of the subject-specific MR-derived AC method RESOLUTE in post-operative brain tumor patients. Methods: We analyzed 51 post-operative brain tumor patients (68 examinations, 200 MBq [18F]-FET) investigated in a PET/MRI scanner. MR-AC maps were acquired using: (1) the Dixon water fat separation sequence, (2) the ultra short echo time (UTE) sequences, (3) calculated using our new RESOLUTE methodology, and (4) a same day low-dose CT used as reference "gold standard." For each subject and each AC method the tumor was delineated by isocontouring tracer uptake above a tumor(T)-to-brain background (B) activity ratio of 1.6. We measured B, tumor mean and maximal activity (TMEAN, TMAX), biological tumor volume (BTV), and calculated the clinical metrics TMEAN/B and TMAX/B. Results: When using RESOLUTE 5/68 studies did not meet our predefined acceptance criteria of TMAX/B difference to CT-AC < ±0.1 or 5%, TMEAN/B < ±0.05 or 5%, and BTV < ±2 mL or 10%. In total, 46/68 studies failed our acceptance criteria using Dixon, and 26/68 using UTE. The 95% limits of agreement for TMAX/B was for RESOLUTE (-3%; 4%), Dixon (-9%; 16%), and UTE (-7%; 10%). The absolute error when measuring BTV was 0.7 ± 1.9 mL (N.S) with RESOLUTE, 5.3 ± 10 mL using Dixon, and 1.7 ± 3.7 mL using UTE. RESOLUTE performed best in the identification of the location of peak activity and in brain tumor follow-up monitoring using clinical FET PET metrics. Conclusions: Overall, we found RESOLUTE to be the AC method that most robustly reproduced the

  17. Dental Implant Systems

    PubMed Central

    Oshida, Yoshiki; Tuna, Elif B.; Aktören, Oya; Gençay, Koray

    2010-01-01

    Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities. PMID:20480036

  18. Cochlear Implants.

    ERIC Educational Resources Information Center

    Clark, Catherine; Scott, Larry

    This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

  19. Cochlear Implants.

    ERIC Educational Resources Information Center

    Clark, Catherine; Scott, Larry

    This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

  20. [Imaging in silicone breast implantation].

    PubMed

    Gielens, Maaike P M; Koolen, Pieter G L; Hermens, Roland A E C; Rutten, Matthieu J C M

    2013-01-01

    Recently, there have been concerns regarding the use of breast implants from Poly Implant Prothèse (PIP, Seyne sur Mer, France) for breast augmentation due to their tendency to rupture and the possibility of having toxic contents. MRI using a specific silicone-sensitive sequence has proven to be the most sensitive and specific technique in the detection of intra- and extracapsular implant rupture. However, given its high costs, it is important that this technique is used sparingly. In this clinical lesson, we compare the sensitivity and specificity of mammography, ultrasound, CT and MRI for the detection of breast implant rupture. Based on two cases, a diagnostic approach is given in order to reduce health care costs.

  1. RESOLUTE PET/MRI Attenuation Correction for O-(2-18F-fluoroethyl)-L-tyrosine (FET) in Brain Tumor Patients with Metal Implants

    PubMed Central

    Ladefoged, Claes N.; Andersen, Flemming L.; Kjær, Andreas; Højgaard, Liselotte; Law, Ian

    2017-01-01

    Aim: Positron emission tomography (PET) imaging is a useful tool for assisting in correct differentiation of tumor progression from reactive changes, and the radiolabeled amino acid analog tracer O-(2-18F-fluoroethyl)-L-tyrosine (FET)-PET is amongst the most frequently used. The FET-PET images need to be quantitatively correct in order to be used clinically, which require accurate attenuation correction (AC) in PET/MRI. The aim of this study was to evaluate the use of the subject-specific MR-derived AC method RESOLUTE in post-operative brain tumor patients. Methods: We analyzed 51 post-operative brain tumor patients (68 examinations, 200 MBq [18F]-FET) investigated in a PET/MRI scanner. MR-AC maps were acquired using: (1) the Dixon water fat separation sequence, (2) the ultra short echo time (UTE) sequences, (3) calculated using our new RESOLUTE methodology, and (4) a same day low-dose CT used as reference “gold standard.” For each subject and each AC method the tumor was delineated by isocontouring tracer uptake above a tumor(T)-to-brain background (B) activity ratio of 1.6. We measured B, tumor mean and maximal activity (TMEAN, TMAX), biological tumor volume (BTV), and calculated the clinical metrics TMEAN/B and TMAX/B. Results: When using RESOLUTE 5/68 studies did not meet our predefined acceptance criteria of TMAX/B difference to CT-AC < ±0.1 or 5%, TMEAN/B < ±0.05 or 5%, and BTV < ±2 mL or 10%. In total, 46/68 studies failed our acceptance criteria using Dixon, and 26/68 using UTE. The 95% limits of agreement for TMAX/B was for RESOLUTE (−3%; 4%), Dixon (−9%; 16%), and UTE (−7%; 10%). The absolute error when measuring BTV was 0.7 ± 1.9 mL (N.S) with RESOLUTE, 5.3 ± 10 mL using Dixon, and 1.7 ± 3.7 mL using UTE. RESOLUTE performed best in the identification of the location of peak activity and in brain tumor follow-up monitoring using clinical FET PET metrics. Conclusions: Overall, we found RESOLUTE to be the AC method that most robustly

  2. Penile Implants

    MedlinePlus

    Penile Implants Overview By Mayo Clinic Staff Penile implants are devices placed inside the penis to allow men with erectile dysfunction (ED) to get an erection. Penile implants are typically recommended after other treatments for ED ...

  3. Dental Implants.

    PubMed

    Griggs, Jason A

    2017-10-01

    Systematic reviews of literature over the period between 2008 and 2017 are discussed regarding clinical evidence for the factors affecting survival and failure of dental implants. The factors addressed include publication bias, tooth location, insertion torque, collar design, implant-abutment connection design, implant length, implant width, bone augmentation, platform switching, surface roughness, implant coatings, and the use of ceramic materials in the implant body and abutment. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. The silicone breast implant controversy.

    PubMed

    Guerette, P H

    1995-02-01

    Feminists call it objectification. Consumer advocates call it victimization. Medical personnel call it augmentation. Women, implantation. Whatever the term, media hype and the increasing number of lawsuits against U.S. manufacturers of silicone breast implants has caused widespread concern among women and raised serious questions about the long term health risks and safety of breast implant devices.

  5. MRI in ocular drug delivery.

    PubMed

    Li, S Kevin; Lizak, Martin J; Jeong, Eun-Kee

    2008-11-01

    Conventional pharmacokinetic methods for studying ocular drug delivery are invasive and cannot be conveniently applied to humans. The advancement of MRI technology has provided new opportunities in ocular drug-delivery research. MRI provides a means to non-invasively and continuously monitor ocular drug-delivery systems with a contrast agent or compound labeled with a contrast agent. It is a useful technique in pharmacokinetic studies, evaluation of drug-delivery methods, and drug-delivery device testing. Although the current status of the technology presents some major challenges to pharmaceutical research using MRI, it has a lot of potential. In the past decade, MRI has been used to examine ocular drug delivery via the subconjunctival route, intravitreal injection, intrascleral injection to the suprachoroidal space, episcleral and intravitreal implants, periocular injections, and ocular iontophoresis. In this review, the advantages and limitations of MRI in the study of ocular drug delivery are discussed. Different MR contrast agents and MRI techniques for ocular drug-delivery research are compared. Ocular drug-delivery studies using MRI are reviewed.

  6. MRI in ocular drug delivery

    PubMed Central

    Li, S. Kevin; Lizak, Martin J.; Jeong, Eun-Kee

    2008-01-01

    Conventional pharmacokinetic methods for studying ocular drug delivery are invasive and cannot be conveniently applied to humans. The advancement of MRI technology has provided new opportunities in ocular drug-delivery research. MRI provides a means to non-invasively and continuously monitor ocular drug-delivery systems with a contrast agent or compound labeled with a contrast agent. It is a useful technique in pharmacokinetic studies, evaluation of drug-delivery methods, and drug-delivery device testing. Although the current status of the technology presents some major challenges to pharmaceutical research using MRI, it has a lot of potential. In the past decade, MRI has been used to examine ocular drug delivery via the subconjunctival route, intravitreal injection, intrascleral injection to the suprachoroidal space, episcleral and intravitreal implants, periocular injections, and ocular iontophoresis. In this review, the advantages and limitations of MRI in the study of ocular drug delivery are discussed. Different MR contrast agents and MRI techniques for ocular drug-delivery research are compared. Ocular drug-delivery studies using MRI are reviewed. PMID:18186077

  7. Clinical outcomes and causes of death in Japanese patients with long-term inferior vena cava filter implants and deep vein thrombosis.

    PubMed

    Iwamoto, Yumiko; Okamoto, Mitsunori; Hashimoto, Masaki; Fukuda, Yukihiro; Uchimura, Yuko; Iwamoto, Akimichi; Matsumoto, Takeshi; Iwasaki, Toshitaka; Kinoshita, Hiroki; Ueda, Hironori; Kihara, Yasuki

    2014-10-01

    We assessed the causes of death and efficacy of permanent inferior vena cava (IVC) filters for preventing new pulmonary embolisms (PE) in Japanese deep vein thrombosis (DVT) patients with or without PE. We studied the clinical outcomes during the follow-up period of 1 day to 9 years (median: 18 months; mean: 28 months) in 66 of 72 consecutive patients (44 with acute PE, 27 with intrapelvic DVT, and 1 with floating femoral vein thrombosis). Fifty of 66 patients received anticoagulant therapy after the filter placement. Five patients died within 1 month (median 9 days) after the filter placement: three from recurrence of PE, one from cancer, and one from sepsis. Two of the three patients with recurrence of PE had preexisting intracardiac thrombi in the right atrium or main pulmonary artery before filter implantation. Ten patients died from the underlying disease (cancer: 7; brain hemorrhage: 1; amyotrophic lateral sclerosis: 1; pneumonia: 1) over 1 month after the filter placement (median follow-up period: 21 months). No new symptomatic PE recurrence was observed over 1 month after the filter placement. The 61 patients with long-term follow-up had no deterioration of DVT, and all the 31 patients who underwent multi-slice computed tomography showed no PE recurrence or filter thrombus occlusion, fracture, or migration. Underlying diseases and preexisting intracardiac thrombi may be the determining factors for the prognosis of DVT patients. Permanent IVC filters with anticoagulant therapy may be effective for preventing death from new PE in Japanese DVT patients. Copyright © 2014. Published by Elsevier Ltd.

  8. Heterotopic ossification associated with myelopathy following cervical disc prosthesis implantation.

    PubMed

    Wenger, Markus; Markwalder, Thomas-Marc

    2016-04-01

    This case report presents a 37-year-old man with clinical signs of myelopathy almost 9 years after implantation of a Bryan disc prosthesis (Medtronic Sofamor Danek, Memphis, TN, USA) for C5/C6 soft disc herniation. As demonstrated on MRI and CT scan, spinal cord compression was caused by bony spurs due to heterotopic ossification posterior to the still moving prosthesis. The device, as well as the ectopic bone deposits, had to be removed because of myelopathy and its imminent aggravation. Conversion to anterior spondylodesis was performed.

  9. Evaluation of 39 medical implants at 7.0 T

    PubMed Central

    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

  10. Management of peri-implantitis

    PubMed Central

    Prathapachandran, Jayachandran; Suresh, Neethu

    2012-01-01

    Peri-implantitis is a site-specific infectious disease that causes an inflammatory process in soft tissues, and bone loss around an osseointegrated implant in function. The etiology of the implant infection is conditioned by the status of the tissue surrounding the implant, implant design, degree of roughness, external morphology, and excessive mechanical load. The microorganisms most commonly associated with implant failure are spirochetes and mobile forms of Gram-negative anaerobes, unless the origin is the result of simple mechanical overload. Diagnosis is based on changes of color in the gingiva, bleeding and probing depth of peri-implant pockets, suppuration, X-ray, and gradual loss of bone height around the tooth. Treatment will differ depending upon whether it is a case of peri-implant mucositis or peri-implantitis. The management of implant infection should be focused on the control of infection, the detoxification of the implant surface, and regeneration of the alveolar bone. This review article deals with the various treatment options in the management of peri-implantitis. The article also gives a brief description of the etiopathogenesis, clinical features, and diagnosis of peri-implantitis. PMID:23559913

  11. Cardiac Implantable Electronic Device Safety during Magnetic Resonance Imaging

    PubMed Central

    Hwang, You Mi; Lee, Ji Hyun; Kim, Minsu; Nam, Gi-Byoung; Choi, Kee-Joon; Kim, You-Ho

    2016-01-01

    Background and Objectives Although magnetic resonance imaging (MRI) conditional cardiac implantable electronic devices (CIEDs) have become recently available, non-MRI conditional devices and the presence of epicardial and abandoned leads remain a contraindication for MRIs. Subjects and Methods This was a single center retrospective study, evaluating the clinical outcomes and device parameter changes in patients with CIEDs who underwent an MRI from June 1992 to March 2015. Clinical and device related information was acquired by a thorough chart review. Results A total of 40 patients, 38 with a pacemaker (including epicardially located pacemaker leads) and 2 with implantable cardioverter defibrillators, underwent 50 MRI examinations. Among the patients, 11 had MRI conditional CIEDs, while the remaining had non-MRI conditional devices. Among these patients, 23 patients had traditional contraindications for an MRI: (1) nonfunctional leads (n=1, 2.5%), (2) epicardially located leads (n=9, 22.5%), (3) scanning area in proximity to a device (n=9, 22.5%), (4) devices implanted within 6 weeks (n=2, 5%), and (5) MRI field strength at 3.0 Tesla (n=6, 15%). All patients underwent a satisfactory MRI examination with no adverse events during or after the procedure. There were no significant changes in parameters or malfunctioning devices in any patients with CIEDs. Conclusion Under careful monitoring, MRI is safe to perform on patients with non-MRI conditional CIEDs, remnant leads, and epicardially located leads, as well as MRI-conditional devices. PMID:27826339

  12. Magnetic Resonance Imaging (MRI) Safety

    MedlinePlus

    ... radiation. Instead, MRI uses a powerful magnetic field, radio waves, rapidly changing magnetic fields, and a computer to ... in most of the body's tissues. The applied radio waves then cause these protons to produce signals that ...

  13. Knee MRI

    MedlinePlus

    ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ... tell the technologist if you have medical or electronic devices in your body. These objects may interfere ...

  14. Shoulder MRI

    MedlinePlus

    ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ... tell the technologist if you have medical or electronic devices in your body. These objects may interfere ...

  15. Shoulder MRI

    MedlinePlus

    ... of the shoulder uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of ... scans, MRI does not utilize ionizing radiation. Instead, radio waves redirect alignment of hydrogen atoms that naturally exist ...

  16. Knee MRI

    MedlinePlus

    ... of the knee uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of ... scans, MRI does not utilize ionizing radiation. Instead, radio waves redirect alignment of hydrogen atoms that naturally exist ...

  17. {l_brace}311{r_brace} Defects in ion-implanted silicon: The cause of transient diffusion, and a mechanism for dislocation formation

    SciTech Connect

    Eaglesham, D.J.; Stolk, P.A.; Cheng, J.Y.; Gossmann, H.J.; Poate, J.M.; Haynes, T.E.

    1995-04-01

    Ion implantation is used at several critical stages of Si integrated circuit manufacturing. The authors show how {l_brace}311{r_brace} defects arising after implantation are responsible for both enhanced dopant diffusion during annealing, and stable dislocations post-anneal. They observe {l_brace}311{r_brace} defects in the earliest stages of an anneal. They subsequently undergo rapid Ostwald ripening and evaporation. At low implant doses evaporation dominates, and they can quantitatively relate the interstitials emitted from these defects to the transient enhancement in diffusivity of dopants such as B and P. At higher doses Ostwald ripening is significant, and they observe the defects to undergo a series of unfaulting reactions to form both Frank loops and perfect dislocations. They demonstrate the ability to control both diffusion and dislocations by the addition of small amounts of carbon impurities.

  18. MRI renaissance.

    PubMed

    Hensley, S

    1997-12-01

    A few years ago, magnetic resonance imaging was healthcare's version of a foreign sports car-flashy, expensive and impractical. Now, after years in the doldrums, sales of MRI systems are roaring back. An aging fleet of MRI scanners due for replacement and a hearty increase in doctors' use of the versatile imaging tools are combining to fuel the surge in demand, vendors and customers say.

  19. A no bleed implant.

    PubMed

    Ersek, R A; Navarro, J A; Nemeth, D Z; Sas, G

    1993-01-01

    Breast implants have evolved from the original saline-filled, smooth-surfaced silicone rubber bag to silicone gel-filled smooth-walled sacs to a combination of a silicone gel-filled bag within a saline-filled sac, and, most recently, a reversed, double-lumen implant with a saline bag inside of a gel-filled bag. Texture-surfaced implants were first used in 1970 when the standard silicone gel-filled implant was covered with a polyurethane foam. Because of concerns about the degradation products of this foam, they were removed from the market in 1991. In 1975 double-lumen silicone textured implants were developed, followed by silicone gel-filled textured implants. In 1990 a new radiolucent, biocompatible gel was produced that reduced the problem of radioopacity of silicone implants. Because of the gel's sufficiently low coefficient of friction, leakage caused by fold flaw fracture may also be decreased. We present a case where this new biocompatible gel implant was repositioned after four months. The resulting scar capsule in this soft breast was thin [< 0.002 cm (0.008 in.)] and evenly textured as a mirror image of the textured silicone surface. Scanning electron microscopy and x-ray defraction spectrophotometry revealed no silicone bleed.

  20. Dental Implants.

    PubMed

    Zohrabian, Vahe M; Sonick, Michael; Hwang, Debby; Abrahams, James J

    2015-10-01

    Dental implants restore function to near normal in partially or completely edentulous patients. A root-form implant is the most frequently used type of dental implant today. The basis for dental implants is osseointegration, in which osteoblasts grow and directly integrate with the surface of titanium posts surgically embedded into the jaw. Radiologic assessment is critical in the preoperative evaluation of the dental implant patient, as the exact height, width, and contour of the alveolar ridge must be determined. Moreover, the precise locations of the maxillary sinuses and mandibular canals, as well as their relationships to the site of implant surgery must be ascertained. As such, radiologists must be familiar with implant design and surgical placement, as well as augmentation procedures utilized in those patients with insufficient bone in the maxilla and mandible to support dental implants.

  1. Penile Implants

    MedlinePlus

    ... Three-piece inflatable implants use a fluid-filled reservoir implanted under the abdominal wall, a pump and ... an erection, you pump the fluid from the reservoir into the cylinders. Afterward, you release the valve ...

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

    PubMed

    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.

  3. Septal repair implants: evaluation of magnetic resonance imaging safety at 3 T.

    PubMed

    Shellock, Frank G; Valencerina, Samuel

    2005-12-01

    Specialized implants are used for transcatheter closure of septal defects, including atrial and ventricular septal defects, and patent foramen ovale. These metallic devices may pose a risk to patients undergoing magnetic resonance imaging (MRI) procedures especially if performed at 3 T. Therefore, this investigation evaluated MRI safety at 3 T for septal repair implants (CardioSEAL Septal Repair Implant and STARFlex Septal Repair Implant, NMT Medical, Boston, MA, USA) by characterizing magnetic field interactions, heating and artifacts. These implants exhibited minor magnetic field interactions; heating was not excessive (+0.5 degrees C); and artifacts will only create a problem if the area of interest is in the same area as or near these devices. Thus, the findings indicated that it would be safe for a patient with these implants to undergo MRI at 3 T or lower. Importantly, because of the minor magnetic field interactions, MRI may be performed immediately after implantation.

  4. Low dose of continuous-wave microwave irradiation did not cause temperature increase in muscles tissue adjacent to titanium alloy implants--an animal study.

    PubMed

    Ye, Dongmei; Xu, Yiming; Fu, Tengfei; Zhang, Han; Feng, Xianxuan; Wang, Gang; Jiang, Lan; Bai, Yuehong

    2013-12-23

    Research studies on the influence of radiofrequency electromagnetic radiation on implants in vitro have failed to investigate temperature changes in the tissues adjacent to the implants under microwave therapy. We therefore, used a rabbit model in an effort to determine the impact of microwave therapy on temperature changes in tissues adjacent to the titanium alloy implants and the safety profile thereof. Titanium alloy internal fixation plates were implanted in New Zealand rabbits in the middle of femur. Microwave therapy was performed by a 2450 MHz microwave generator 3 days after the surgery. Temperature changes of muscles adjacent to the implants were recorded under exposure to dose-gradient microwave radiation from 20w to 60w. Significant difference between control and microwave treatment group at peak temperatures (T(peak)) and temperature gap (T(gap) = T(peak)-T(vally)) were observed in deep muscles (T(peak), 41.63 ± 0.21°C vs. 44.40 ± 0.17°C, P < 0.01; T(gap), 5.33 ± 0.21°C vs. 8.10 ± 0.36°C, P < 0.01) and superficial muscles (T(peak), 41.53 ± 0.15°C vs. 42.03 ± 0.23°C, P = 0.04; T(gap), 5.23 ± 0.21°C vs. 5.80 ± 0.17°C, P = 0.013) under 60 w, and deep muscles (T(peak), 40.93 ± 0.25°C vs. 41.87 ± 0.23°C, P = 0.01; T(gap), 4.73 ± 0.20°C vs. 5.63 ± 0.35°C, P = 0.037) under 50w, but not under 20, 30 and 40w. Our results suggest that low-dose (20w-40w) continuous-wave microwave irradiation delivered by a 2450 MHz microwave generator might be a promising treatment for patients with titanium alloy internal fixation, as it did not raise temperature in muscle tissues adjacent to the titanium alloy implant.

  5. Low dose of continuous – wave microwave irradiation did not cause temperature increase in muscles tissue adjacent to titanium alloy implants – an animal study

    PubMed Central

    2013-01-01

    Background Research studies on the influence of radiofrequency electromagnetic radiation on implants in vitro have failed to investigate temperature changes in the tissues adjacent to the implants under microwave therapy. We therefore, used a rabbit model in an effort to determine the impact of microwave therapy on temperature changes in tissues adjacent to the titanium alloy implants and the safety profile thereof. Methods Titanium alloy internal fixation plates were implanted in New Zealand rabbits in the middle of femur. Microwave therapy was performed by a 2450 MHz microwave generator 3 days after the surgery. Temperature changes of muscles adjacent to the implants were recorded under exposure to dose-gradient microwave radiation from 20w to 60w. Results Significant difference between control and microwave treatment group at peak temperatures (Tpeak) and temperature gap (Tgap= Tpeak-Tvally) were observed in deep muscles (Tpeak, 41.63 ± 0.21°C vs. 44.40 ± 0.17°C, P < 0.01; Tgap, 5.33 ± 0.21°C vs. 8.10 ± 0.36°C, P < 0.01) and superficial muscles (Tpeak, 41.53 ± 0.15°C vs. 42.03 ± 0.23°C, P = 0.04; Tgap, 5.23 ± 0.21°C vs. 5.80 ± 0.17°C, P = 0.013) under 60 w, and deep muscles (Tpeak, 40.93 ± 0.25°C vs. 41.87 ± 0.23°C, P = 0.01; Tgap, 4.73 ± 0.20°C vs. 5.63 ± 0.35°C, P = 0.037) under 50w, but not under 20, 30 and 40w. Conclusion Our results suggest that low-dose (20w-40w) continuous-wave microwave irradiation delivered by a 2450 MHz microwave generator might be a promising treatment for patients with titanium alloy internal fixation, as it did not raise temperature in muscle tissues adjacent to the titanium alloy implant. PMID:24365389

  6. Portable MRI

    SciTech Connect

    Espy, Michelle A.

    2012-06-29

    This project proposes to: (1) provide the power of MRI to situations where it presently isn't available; (2) perform the engineering required to move from lab to a functional prototype; and (3) leverage significant existing infrastructure and capability in ultra-low field MRI. The reasons for doing this: (1) MRI is the most powerful tool for imaging soft-tissue (e.g. brain); (2) Billions don't have access due to cost or safety issues; (3) metal will heat/move in high magnetic fields; (4) Millions of cases of traumatic brain injury in US alone; (5) even more of non-traumatic brain injury; (6) (e.g. stroke, infection, chemical exposure); (7) Need for early diagnostic; (8) 'Signature' wound of recent conflicts; (9) 22% of injuries; (10) Implications for post-traumatic stress disorder; and (11) chronic traumatic encephalopathy.

  7. Two-stage implant systems.

    PubMed

    Fritz, M E

    1999-06-01

    Since the advent of osseointegration approximately 20 years ago, there has been a great deal of scientific data developed on two-stage integrated implant systems. Although these implants were originally designed primarily for fixed prostheses in the mandibular arch, they have been used in partially dentate patients, in patients needing overdentures, and in single-tooth restorations. In addition, this implant system has been placed in extraction sites, in bone-grafted areas, and in maxillary sinus elevations. Often, the documentation of these procedures has lagged. In addition, most of the reports use survival criteria to describe results, often providing overly optimistic data. It can be said that the literature describes a true adhesion of the epithelium to the implant similar to adhesion to teeth, that two-stage implants appear to have direct contact somewhere between 50% and 70% of the implant surface, that the microbial flora of the two-stage implant system closely resembles that of the natural tooth, and that the microbiology of periodontitis appears to be closely related to peri-implantitis. In evaluations of the data from implant placement in all of the above-noted situations by means of meta-analysis, it appears that there is a strong case that two-stage dental implants are successful, usually showing a confidence interval of over 90%. It also appears that the mandibular implants are more successful than maxillary implants. Studies also show that overdenture therapy is valid, and that single-tooth implants and implants placed in partially dentate mouths have a success rate that is quite good, although not quite as high as in the fully edentulous dentition. It would also appear that the potential causes of failure in the two-stage dental implant systems are peri-implantitis, placement of implants in poor-quality bone, and improper loading of implants. There are now data addressing modifications of the implant surface to alter the percentage of

  8. Chest MRI

    MedlinePlus

    ... as the contrast dye is injected. The MRI machine is a large, tunnel-like machine that has a table. You will lie still ... table, and the table will slide into the machine. You will hear loud humming, tapping, and buzzing ...

  9. Cardiac MRI

    MedlinePlus

    ... as the contrast dye is injected. The MRI machine is a large, tunnel-like machine that has a table. You will lie still ... table and the table will slide into the machine. You will hear loud humming, tapping, and buzzing ...

  10. Deep brain stimulation with a pre-existing cochlear implant: Surgical technique and outcome

    PubMed Central

    Eddelman, Daniel; Wewel, Joshua; Wiet, R. Mark; Metman, Leo V.; Sani, Sepehr

    2017-01-01

    Background: Patients with previously implanted cranial devices pose a special challenge in deep brain stimulation (DBS) surgery. We report the implantation of bilateral DBS leads in a patient with a cochlear implant. Technical nuances and long-term interdevice functionality are presented. Case Description: A 70-year-old patient with advancing Parkinson's disease and a previously placed cochlear implant for sensorineural hearing loss was referred for placement of bilateral DBS in the subthalamic nucleus (STN). Prior to DBS, the patient underwent surgical removal of the subgaleal cochlear magnet, followed by stereotactic MRI, frame placement, stereotactic computed tomography (CT), and merging of imaging studies. This technique allowed for successful computational merging, MRI-guided targeting, and lead implantation with acceptable accuracy. Formal testing and programming of both the devices were successful without electrical interference. Conclusion: Successful DBS implantation with high resolution MRI-guided targeting is technically feasible in patients with previously implanted cochlear implants by following proper precautions. PMID:28480109

  11. Deep brain stimulation with a pre-existing cochlear implant: Surgical technique and outcome.

    PubMed

    Eddelman, Daniel; Wewel, Joshua; Wiet, R Mark; Metman, Leo V; Sani, Sepehr

    2017-01-01

    Patients with previously implanted cranial devices pose a special challenge in deep brain stimulation (DBS) surgery. We report the implantation of bilateral DBS leads in a patient with a cochlear implant. Technical nuances and long-term interdevice functionality are presented. A 70-year-old patient with advancing Parkinson's disease and a previously placed cochlear implant for sensorineural hearing loss was referred for placement of bilateral DBS in the subthalamic nucleus (STN). Prior to DBS, the patient underwent surgical removal of the subgaleal cochlear magnet, followed by stereotactic MRI, frame placement, stereotactic computed tomography (CT), and merging of imaging studies. This technique allowed for successful computational merging, MRI-guided targeting, and lead implantation with acceptable accuracy. Formal testing and programming of both the devices were successful without electrical interference. Successful DBS implantation with high resolution MRI-guided targeting is technically feasible in patients with previously implanted cochlear implants by following proper precautions.

  12. Long-term effectiveness of an ad hoc tailored titanium implant as a spacer for microvascular decompression in the treatment of trigeminal neuralgia caused by megadolichoectatic basilar artery anomaly: 9-year follow-up.

    PubMed

    Banczerowski, Péter; Czigléczki, Gábor; Nyáry, István

    2014-12-01

    An enlarged, elongated, ectatic, and sclerotic aberration of the vertebrobasilar system is known as a megadolichoectatic basilar artery (BA) anomaly. The anomaly is often involved in the pathological process of trigeminal neuralgia by compressing and distorting the trigeminal nerve. First-line medical treatment includes drug therapy, but a second-line surgical procedure could be effective in medication-resistant cases. The authors report the case of a 65-year-old man with a 12-year history of progressing trigeminal neuralgia who underwent microvascular decompression after the first-line drug treatment had failed. This case is unique because an in situ tailored titanium microplate was used as a spacer to alleviate compression by the BA on the trigeminal nerve. The titanium implant provided durable and sufficient retraction for the sclerotic arterial complex when the trigeminal nerve was placed in the tunnel of the implant. The 9-year follow-up examination proves the safety and long-term efficacy of titanium implants in the treatment of trigeminal neuralgia caused by a megadolichoectatic BA anomaly. The method applied in this case was not intended to be and certainly is not an alternative to routine microvascular decompression-this surgical solution may be reserved for some extreme cases.

  13. Peri-implant mucositis and peri-implantitis: clinical and histopathological characteristics and treatment.

    PubMed

    Khammissa, R A G; Feller, L; Meyerov, R; Lemmer, J

    2012-04-01

    Osseointegrated dental implants are used routinely in dentistry in the confidence of predictable success. However, if the implant surfaces become colonised by pathogenic bacteria, the plaque-induced inflammation around the implants may cause peri-implant tissue destruction. Peri-implant mucositis is a reversible, plaque-induced inflammatory lesion confined to the peri-implant soft tissue unit and clinically is characterised by redness, swelling and bleeding on gentle probing. Peri-implantitis is an extension of peri-implant mucositis to involve the bone supporting the implant: it is characterised by loss of osseointegration of the coronal part of the implant, by increased probing depth and by bleeding and/or suppuration on probing. Established peri-implantitis does not respond predictably to treatment. The best management of plaque-induced peri-implant inflammatory diseases is prevention. Regular personal and professional cleaning of the implant is mandatory to minimise bacterial load. Despite our best efforts, plaque-induced peri-implant inflammatory diseases will occur frequently, and as these diseases respond best to early treatment, early detection of peri-implant mucositis by regular assessment will permit timely treatment. Peri-implant mucositis is readily treated non-surgically. Peri-implantitis is more difficult to treat largely because of the problem of decontamination of the roughened, threaded surfaces of exposed implants. As a rule, surgical treatment will be necessary, and even then success is not assured.

  14. Implantable Microimagers

    PubMed Central

    Ng, David C.; Tokuda, Takashi; Shiosaka, Sadao; Tano, Yasuo; Ohta, Jun

    2008-01-01

    Implantable devices such as cardiac pacemakers, drug-delivery systems, and defibrillators have had a tremendous impact on the quality of live for many disabled people. To date, many devices have been developed for implantation into various parts of the human body. In this paper, we focus on devices implanted in the head. In particular, we describe the technologies necessary to create implantable microimagers. Design, fabrication, and implementation issues are discussed vis-à-vis two examples of implantable microimagers; the retinal prosthesis and in vivo neuro-microimager. Testing of these devices in animals verify the use of the microimagers in the implanted state. We believe that further advancement of these devices will lead to the development of a new method for medical and scientific applications. PMID:27879873

  15. Rupture of poly implant prothèse silicone breast implants: an implant retrieval study.

    PubMed

    Swarts, Eric; Kop, Alan M; Nilasaroya, Anastasia; Keogh, Catherine V; Cooper, Timothy

    2013-04-01

    Poly Implant Prothèse implants were recalled in Australia in April of 2010 following concerns of higher than expected rupture rates and the use of unauthorized industrial grade silicone as a filler material. Although subsequent investigations found that the gel filler material does not pose a threat to human health, the important question of what caused a relatively modern breast implant to have such a poor outcome compared with contemporary silicone breast implants is yet to be addressed. From a cohort of 27 patients, 19 ruptured Poly Implant Prothèse breast implants were subjected to a range of mechanical tests and microscopic/macroscopic investigations to evaluate possible changes in properties as a result of implantation. New Poly Implant Prothèse implants were used as controls. All samples, explanted and controls, complied with the requirements for shell integrity as specified in the International Organization for Standardization 14607. Compression testing revealed rupture rates similar to those reported in the literature. Shell thickness was highly variable, with most shells having regions below the minimum thickness of 0.57 mm that was specified by the manufacturer. Potential regions of stress concentration were observed on the smooth inner surfaces and outer textured surfaces. The high incidence of Poly Implant Prothèse shell rupture is most likely a result of inadequate quality control, with contributory factors being shell thickness variation and manufacturing defects on both inner and outer surfaces of the shell. No evidence of shell degradation with implantation time was determined.

  16. High Productivity Implantation ''PARTIAL IMPLANT''

    SciTech Connect

    Hino, Masayoshi; Miyamoto, Naoki; Sakai, Shigeki; Matsumoto, Takao

    2008-11-03

    The patterned ion implantation 'PARTIAL IMPLANT' has been developed as a productivity improvement tool. The Partial Implant can form several different ion dose areas on the wafer surface by controlling the speed of wafer moving and the stepwise rotation of twist axis. The Partial Implant system contains two implant methods. One method is 'DIVIDE PARTIAL IMPLANT', that is aimed at reducing the consumption of the wafer. The Divide Partial Implant evenly divides dose area on one wafer surface into two or three different dose part. Any dose can be selected in each area. So the consumption of the wafer for experimental implantation can be reduced. The second method is 'RING PARTIAL IMPLANT' that is aimed at improving yield by correcting electrical characteristic of devices. The Ring Partial Implant can form concentric ion dose areas. The dose of wafer external area can be selected to be within plus or minus 30% of dose of wafer central area. So the electrical characteristic of devices can be corrected by controlling dose at edge side on the wafer.

  17. Endodontic implants

    PubMed Central

    Yadav, Rakesh K.; Tikku, A. P.; Chandra, Anil; Wadhwani, K. K.; Ashutosh kr; Singh, Mayank

    2014-01-01

    Endodontic implants were introduced back in 1960. Endodontic implants enjoyed few successes and many failures. Various reasons for failures include improper case selection, improper use of materials and sealers and poor preparation for implants. Proper case selection had given remarkable long-term success. Two different cases are being presented here, which have been treated successfully with endodontic implants and mineral trioxide aggregate Fillapex (Andreaus, Brazil), an MTA based sealer. We suggest that carefully selected cases can give a higher success rate and this method should be considered as one of the treatment modalities. PMID:25298723

  18. A clinical feasibility study to evaluate the safety and efficacy of PEOT/PBT implants for human donor site filling during mosaicplasty.

    PubMed

    Bartha, Lajos; Hamann, Doreen; Pieper, Jeroen; Péters, Fabiènne; Riesle, Jens; Vajda, Andras; Novak, Pal Kaposi; Hangody, Laszlo Rudolf; Vasarhelyi, Gabor; Bodó, Laszlo; van Blitterswijk, Clemens; de Wijn, Joost; Kenyeres, Annamaria; Modis, Laszlo; Balo, Eszter; Hangody, Laszlo

    2013-01-01

    Mosaicplasty has become a well-accepted treatment modality for articular cartilage lesions in the knee. Postoperative bleeding remains potentially concerning. This study evaluates the porous poly(ethylene oxide)terephthalate/poly(butylene terephthalate) (PEOT/PBT) implants used for donor site filling. Empty donor sites were the controls. After 9 months, MRI, macroscopical and histological analysis were carried out. Treated defects did not cause postoperative bleeding. No adverse events or inflammatory response was observed. PEOT/PBT implants were well integrated. Empty controls occasionally showed protrusion of repair tissue at the defect margins. Surface stiffness was minimally improved compared to controls. Existing polymer fragments indicated considerable biodegradation. Histological evaluation of the filled donor sites revealed congruent fibrocartilaginous surface repair with proteoglycan-rich domains and subchondral cancellous bone formation with interspersed fibrous tissue in all implanted sites. The PEOT/PBT implants successfully reduce donor site morbidity and postoperative bleeding after mosaicplasty. II.

  19. Assessment of Electromagnetic Interference with Active Cardiovascular Implantable Electronic Devices (CIEDs) Caused by the Qi A13 Design Wireless Charging Board.

    PubMed

    Seckler, Tobias; Jagielski, Kai; Stunder, Dominik

    2015-05-27

    Electromagnetic interference is a concern for people wearing cardiovascular implantable electronic devices (CIEDs). The aim of this study was to assess the electromagnetic compatibility between CIEDs and the magnetic field of a common wireless charging technology. To do so the voltage induced in CIEDs by Qi A13 design magnetic fields were measured and compared with the performance limits set by ISO 14117. In order to carry this out a measuring circuit was developed which can be connected with unipolar or bipolar pacemaker leads. The measuring system was positioned at the four most common implantation sites in a torso phantom filled with physiological saline solution. The phantom was exposed by using Helmholtz coils from 5 µT to 27 µT with 111 kHz sine‑bursts or by using a Qi A13 design wireless charging board (Qi‑A13‑Board) in two operating modes "power transfer" and "pinging". With the Helmholtz coils the lowest magnetic flux density at which the performance limit was exceeded is 11 µT. With the Qi‑A13‑Board in power transfer mode 10.8% and in pinging mode 45.7% (2.2% at 10 cm distance) of the performance limit were reached at maximum. In neither of the scrutinized cases, did the voltage induced by the Qi‑A13‑Board exceed the performance limits.

  20. Assessment of Electromagnetic Interference with Active Cardiovascular Implantable Electronic Devices (CIEDs) Caused by the Qi A13 Design Wireless Charging Board

    PubMed Central

    Seckler, Tobias; Jagielski, Kai; Stunder, Dominik

    2015-01-01

    Electromagnetic interference is a concern for people wearing cardiovascular implantable electronic devices (CIEDs). The aim of this study was to assess the electromagnetic compatibility between CIEDs and the magnetic field of a common wireless charging technology. To do so the voltage induced in CIEDs by Qi A13 design magnetic fields were measured and compared with the performance limits set by ISO 14117. In order to carry this out a measuring circuit was developed which can be connected with unipolar or bipolar pacemaker leads. The measuring system was positioned at the four most common implantation sites in a torso phantom filled with physiological saline solution. The phantom was exposed by using Helmholtz coils from 5 µT to 27 µT with 111 kHz sine-bursts or by using a Qi A13 design wireless charging board (Qi-A13-Board) in two operating modes “power transfer” and “pinging”. With the Helmholtz coils the lowest magnetic flux density at which the performance limit was exceeded is 11 µT. With the Qi-A13-Board in power transfer mode 10.8% and in pinging mode 45.7% (2.2% at 10 cm distance) of the performance limit were reached at maximum. In neither of the scrutinized cases, did the voltage induced by the Qi-A13-Board exceed the performance limits. PMID:26024360

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    Virtanen, H.; Keshvari, J.; Lappalainen, R.

    2007-03-01

    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.

  3. Battlefield MRI

    SciTech Connect

    Espy, Michelle

    2015-06-01

    Magnetic Resonance Imaging is the best method for non-invasive imaging of soft tissue anatomy, saving countless lives each year. It is regarded as the gold standard for diagnosis of mild to moderate traumatic brain injuries. Furthermore, conventional MRI relies on very high, fixed strength magnetic fields (> 1.5 T) with parts-per-million homogeneity, which requires very large and expensive magnets.

  4. Metal artifact reduction in MRI-based cervical cancer intracavitary brachytherapy

    NASA Astrophysics Data System (ADS)

    Rao, Yuan James; Zoberi, Jacqueline E.; Kadbi, Mo; Grigsby, Perry W.; Cammin, Jochen; Mackey, Stacie L.; Garcia-Ramirez, Jose; Goddu, S. Murty; Schwarz, Julie K.; Gach, H. Michael

    2017-04-01

    Magnetic resonance imaging (MRI) plays an increasingly important role in brachytherapy planning for cervical cancer. Yet, metal tandem, ovoid intracavitary applicators, and fiducial markers used in brachytherapy cause magnetic susceptibility artifacts in standard MRI. These artifacts may impact the accuracy of brachytherapy treatment and the evaluation of tumor response by misrepresenting the size and location of the metal implant, and distorting the surrounding anatomy and tissue. Metal artifact reduction sequences (MARS) with high bandwidth RF selective excitations and turbo spin-echo readouts were developed for MRI of orthopedic implants. In this study, metal artifact reduction was applied to brachytherapy of cervical cancer using the orthopedic metal artifact reduction (O-MAR) sequence. O-MAR combined MARS features with view angle tilting and slice encoding for metal artifact correction (SEMAC) to minimize in-plane and through-plane susceptibility artifacts. O-MAR improved visualization of the tandem tip on T2 and proton density weighted (PDW) imaging in phantoms and accurately represented the diameter of the tandem. In a pilot group of cervical cancer patients (N  =  7), O-MAR significantly minimized the blooming artifact at the tip of the tandem in PDW MRI. There was no significant difference observed in artifact reduction between the weak (5 kHz, 7 z-phase encodes) and medium (10 kHz, 13 z-phase encodes) SEMAC settings. However, the weak setting allowed a significantly shorter acquisition time than the medium setting. O-MAR also reduced susceptibility artifacts associated with metal fiducial markers so that they appeared on MRI at their true dimensions.

  5. Metal artifact reduction in MRI-based cervical cancer intracavitary brachytherapy.

    PubMed

    Rao, Yuan James; Zoberi, Jacqueline E; Kadbi, Mo; Grigsby, Perry W; Cammin, Jochen; Mackey, Stacie L; Garcia-Ramirez, Jose; Goddu, S Murty; Schwarz, Julie K; Gach, H Michael

    2017-04-21

    Magnetic resonance imaging (MRI) plays an increasingly important role in brachytherapy planning for cervical cancer. Yet, metal tandem, ovoid intracavitary applicators, and fiducial markers used in brachytherapy cause magnetic susceptibility artifacts in standard MRI. These artifacts may impact the accuracy of brachytherapy treatment and the evaluation of tumor response by misrepresenting the size and location of the metal implant, and distorting the surrounding anatomy and tissue. Metal artifact reduction sequences (MARS) with high bandwidth RF selective excitations and turbo spin-echo readouts were developed for MRI of orthopedic implants. In this study, metal artifact reduction was applied to brachytherapy of cervical cancer using the orthopedic metal artifact reduction (O-MAR) sequence. O-MAR combined MARS features with view angle tilting and slice encoding for metal artifact correction (SEMAC) to minimize in-plane and through-plane susceptibility artifacts. O-MAR improved visualization of the tandem tip on T2 and proton density weighted (PDW) imaging in phantoms and accurately represented the diameter of the tandem. In a pilot group of cervical cancer patients (N  =  7), O-MAR significantly minimized the blooming artifact at the tip of the tandem in PDW MRI. There was no significant difference observed in artifact reduction between the weak (5 kHz, 7 z-phase encodes) and medium (10 kHz, 13 z-phase encodes) SEMAC settings. However, the weak setting allowed a significantly shorter acquisition time than the medium setting. O-MAR also reduced susceptibility artifacts associated with metal fiducial markers so that they appeared on MRI at their true dimensions.

  6. About Implantable Contraception

    MedlinePlus

    ... TV, Video Games, and the Internet About Implantable Contraception KidsHealth > For Parents > About Implantable Contraception Print A ... How Much Does It Cost? What Is Implantable Contraception? Implantable contraception (often called the birth control implant) ...

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

    SciTech Connect

    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.

  8. QUANTIFICATION OF LOCAL HEMODYNAMIC ALTERATIONS CAUSED BY VIRTUAL IMPLANTATION OF THREE COMMERCIALLY-AVAILABLE STENTS FOR THE TREATMENT OF AORTIC COARCTATION

    PubMed Central

    Kwon, Sung; Feinstein, Jeffrey A.; Dholakia, Ronak J.; LaDisa, John F.

    2014-01-01

    Patients with coarctation of the aorta (CoA) are prone to morbidity including atherosclerotic plaque that has been shown to correlate with altered wall shear stress (WSS) in the descending thoracic aorta (dAo). We created the first patient-specific computational fluid dynamics (CFD) model of a CoA patient treated by Palmaz stenting to date, and compared resulting WSS distributions to those from virtual implantation of GenesisXD and modified NumedCP stents also commonly used for CoA. CFD models were created from magnetic resonance imaging, fluoroscopy and blood pressure (BP) data. Simulations incorporated vessel deformation, downstream vascular resistance and compliance to match measured data and generate blood flow velocity and time-averaged WSS (TAWSS) results. TAWSS was quantified longitudinally and circumferentially in the stented region and dAo. While modest differences were seen in the distal portion of the stented region, marked differences were observed downstream along the posterior dAo and depended on stent type. The GenesisXD model had the least area of TAWSS values exceeding the threshold for platelet aggregation in vitro, followed by the Palmaz and NumedCP stents. Alterations in local blood flow patterns and WSS imparted on the dAo appear to depend on the type of stent implanted for CoA. Following confirmation in larger studies, these findings may aid pediatric interventional cardiologists in selecting the most appropriate stent for each patient, and ultimately reduce long-term morbidity following treatment for CoA by stenting. PMID:24259013

  9. Arteriovenous fistula complication following MRI

    PubMed Central

    Kirkman, Danielle; Junglee, Naushad; Mullins, Paul; Macdonald, Jamie Hugo

    2012-01-01

    Health professionals should be aware of medical procedures that cause vascular access complications. This case describes a haemodialysis patient who experienced pain, swelling and bruising over a radiocephalic fistula following MRI. Exactly the same signs and symptoms were evident following a second scan performed 3 months later. Plausible explanations include a radio frequency-induced electrical current being formed at the arteriovenous fistula, or varying gradients of the MRI sequence stimulating peripheral nerves, leading to a site of increased tissue stimulation. Of note, a juxta-anastomotic venous stenosis was confirmed by fistulogram 4 days after the second scan, although whether this access failure was due to the MRI scan per se could not be ascertained. Nevertheless, these previously undocumented observations suggest that careful patient and fistula monitoring is required when completing MRI scans in those with an arteriovenous fistula. PMID:22927271

  10. Arteriovenous fistula complication following MRI.

    PubMed

    Kirkman, Danielle; Junglee, Naushad; Mullins, Paul; Macdonald, Jamie Hugo

    2012-08-27

    Health professionals should be aware of medical procedures that cause vascular access complications. This case describes a haemodialysis patient who experienced pain, swelling and bruising over a radiocephalic fistula following MRI. Exactly the same signs and symptoms were evident following a second scan performed 3 months later. Plausible explanations include a radio frequency-induced electrical current being formed at the arteriovenous fistula, or varying gradients of the MRI sequence stimulating peripheral nerves, leading to a site of increased tissue stimulation. Of note, a juxta-anastomotic venous stenosis was confirmed by fistulogram 4 days after the second scan, although whether this access failure was due to the MRI scan per se could not be ascertained. Nevertheless, these previously undocumented observations suggest that careful patient and fistula monitoring is required when completing MRI scans in those with an arteriovenous fistula.

  11. PET/MRI and PET/MRI/SISCOM coregistration in the presurgical evaluation of refractory focal epilepsy.

    PubMed

    Fernández, S; Donaire, A; Serès, E; Setoain, X; Bargalló, N; Falcón, C; Sanmartí, F; Maestro, I; Rumià, J; Pintor, L; Boget, T; Aparicio, J; Carreño, M

    2015-03-01

    We aimed to investigate the usefulness of coregistration of positron emission tomography (PET) and magnetic resonance imaging (MRI) findings (PET/MRI) and of coregistration of PET/MRI with subtraction ictal single-photon emission computed tomography (SPECT) coregistered to MRI (SISCOM) (PET/MRI/SISCOM) in localizing the potential epileptogenic zone in patients with drug-resistant epilepsy. We prospectively included 35 consecutive patients with refractory focal epilepsy whose presurgical evaluation included a PET study. Separately acquired PET and structural MRI images were coregistered for each patient. When possible, ictal SPECT and SISCOM were obtained and coregistered with PET/MRI. The potential location of the epileptogenic zone determined by neuroimaging was compared with the seizure onset zone determined by long-term video-EEG monitoring and with invasive EEG studies in patients who were implanted. Structural MRI showed no lesions in 15 patients. In these patients, PET/MRI coregistration showed a hypometabolic area in 12 (80%) patients that was concordant with seizure onset zone on EEG in 9. In 7 patients without MRI lesions, PET/MRI detected a hypometabolism that was undetected on PET alone. SISCOM, obtained in 25 patients, showed an area of hyperperfusion concordant with the seizure onset zone on EEG in 7 (58%) of the 12 of these patients who had normal MRI findings. SISCOM hyperperfusion was less extensive than PET hypometabolism. A total of 19 patients underwent surgery; 11 of these underwent invasive-EEG monitoring and the seizure onset zone was concordant with PET/MRI in all cases. PET/MRI/SISCOM coregistration, performed in 4 of these patients, was concordant in 3 (75%). After epilepsy surgery, 13 (68%) patients are seizure-free after a mean follow-up of 4.5 years. PET/MRI and PET/MRI/SISCOM coregistration are useful for determining the potential epileptogenic zone and thus for planning invasive EEG studies and surgery more precisely, especially in

  12. Ectopic cervical thymus as a rare cause of pediatric neck mass: the role of ultrasound and MRI in the diagnosis. Case report.

    PubMed

    Ozel, Alper; Akdur, Pinar Ozdemır; Celebi, Irfan; Karasu, Rabia; Yilmaz, Banu; Basak, Muzaffer

    2015-06-01

    Ectopic cervical thymus (ECT) is an uncommon cause for cervical mass in the pediatric age group. Ultrasound and magnetic resonance imaging findings of the mass (located along the thymic descent pathway along the thymopharyngeal tract and has identical echostructure and signal intensities to the native thymus in the superior mediastinum) would lead to the diagnosis. The diagnosis is confirmed by fine needle aspiration biopsy or histopathology after resection. The management of ECT is a conservative follow up, except in symptomatic cases with tracheal compression and histologically confirmed neoplasia where surgery is indicated. We present the case of ECT presenting as a left upper neck mass in a 12 year old girl.

  13. Do high radiation doses in locally advanced prostate cancer patients treated with 103Pd implant plus external beam irradiation cause increased urinary, rectal, and sexual morbidity?

    PubMed

    Stone, Nelson N; Cesaretti, Jamie A; Rosenstein, Barry; Stock, Richard G

    2010-01-01

    To investigate the morbidity of higher radiation doses in prostate cancer patients. Five hundred eighty-five men treated with seed implantation and external beam irradiation were followed a median of 5 years (range, 2-11). Hormonal therapy (HT) of 9 months duration was used in 504 (86.2%) patients. The biologic effective dose (BED) was calculated using an alpha/beta of 2. Urinary incontinence (UI) and symptoms (IPSS) were prospectively collected. Rectal morbidity was scored according to the Radiation Therapy Oncology Group (RTOG) scale. Two BED dose groups of 220 Gy (n=136) were used. Comparisons of means were made by Student's t test, and the associations were tested by chi-square analysis (Pearson). Urinary retention developed in 36 (6.2%) and was not associated with BED or IPSS. Retention occurred more often with prostate volume >50 cc (17%, p=0.001). The median change in urinary symptoms (IPSS) was 1. Sixty-one percent with high BED were more likely to have increased postimplant symptoms compared with 39% with lower BED (p=0.025; odds ratio [OR], 1.107; 95% confidence interval [CI], 1.10-1.21). UI occurred in 25 patients (4.3%) and was only associated with a postimplant transurethral resection of the prostate (TURP) (n=25), 16% vs. 2.3% for no TURP (p=0.001; OR, 8; 95% CI, 2.4-27). Of the 373 patients initially potent, 204 (54.7%) maintained potency. Impotence was only associated with age at implant (p=0.001) and HT (p=0.004). Sixty-two (10.6%) patients had Grade 1-2 and 4 patients had Grade 3-4 (0.7%, 2 ulcers and 2 fistulas) rectal complications. Three of the Grade 3/4 complications occurred with a dose 220 Gy does not seem to increase morbidity. (c) 2010 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  14. Breast MRI scan

    MedlinePlus

    MRI - breast; Magnetic resonance imaging - breast; Breast cancer - MRI; Breast cancer screening - MRI ... the same breast or the other breast after breast cancer has been diagnosed Distinguish between scar tissue and ...

  15. MRI (Magnetic Resonance Imaging)

    MedlinePlus

    ... Procedures Medical Imaging MRI (Magnetic Resonance Imaging) MRI (Magnetic Resonance Imaging) Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Magnetic Resonance Imaging (MRI) is a medical imaging procedure for making ...

  16. Cochlear implant

    MedlinePlus

    ... bilateral cochlear implantation: a review. Curr Opin Otolaryngol Head Neck Surg . 2007;15(5):315-318. PMID: 17823546. ... BH, Lund V, et al, eds. Cummings Otolaryngology: Head & Neck Surgery . 6th ed. Philadelphia, PA: Elsevier Saunders; 2015: ...

  17. Breast Implants

    MedlinePlus

    ... in the United States: saline-filled and silicone gel-filled. Both types have a silicone outer shell. ... them. Provide information on saline-filled and silicone gel-filled breast implants, including data supporting a reasonable ...

  18. Magnetic Resonance Imaging at 1.5 Tesla With a Cochlear Implant Magnet in Place: Image Quality and Usability.

    PubMed

    Sharon, Jeffrey D; Northcutt, Benjamin G; Aygun, Nafi; Francis, Howard W

    2016-10-01

    To study the quality and usability of magnetic resonance imaging (MRI) obtained with a cochlear implant magnet in situ. Retrospective chart review. Tertiary care center. All patients who underwent brain MRI with a cochlear implant magnet in situ from 2007 to 2016. None. Grade of view of the ipsilateral internal auditory canal (IAC) and cerebellopontine angle (CPA). Inclusion criteria were met by 765 image sequences in 57 MRI brain scans. For the ipsilateral IAC, significant predictors of a grade 1 (normal) view included: absence of fat saturation algorithm (p = 0.001), nonaxial plane of imaging (p = 0.01), and contrast administration (p = 0.001). For the ipsilateral CPA, significant predictors of a grade 1 view included: absence of fat saturation algorithm (p = 0.001), high-resolution images (p = 0.001), and nonaxial plane of imaging (p = 0.001). Overall, coronal T1 high-resolution images produced the highest percentage of grade 1 views (89%). Fat saturation also caused a secondary ring-shaped distortion artifact, which impaired the view of the contralateral CPA 52.7% of the time, and the contralateral IAC 42.8% of the time. MRI scans without any usable (grade 1) sequences had fewer overall sequences (N = 4.3) than scans with at least one usable sequence (N = 7.1, p = 0.001). MRI image quality with a cochlear implant magnet in situ depends on several factors, which can be modified to maximize image quality in this unique patient population.

  19. Simulation of impact test for determining "health" of percutaneous bone anchored implants.

    PubMed

    Jones, S; Faulkner, G; Raboud, D; Fyfe, K; Wolfaardt, J

    2006-10-01

    There is an ongoing requirement for a clinically relevant, noninvasive technique to monitor the integrity of percutaneous implants used for dental restorations, bone-anchored hearing aids, and to retain extra-oral prostheses (ear, eye, nose, etc). Because of the limitations of conventional diagnostic techniques (CT, MRI), mechanical techniques that measure the dynamic response of the implant-abutment system are being developed. This paper documents a finite element analysis that simulates a transient response to mechanical impact testing using contact elements. The detailed model allows for a specific interface between the implant and bone and characterizes potential clinical situations including loss of bone margin height, loss of osseointegration, and development of a soft connective tissue layer at the bone-implant interface. The results also show that the expected difference in interface stiffness between soft connective tissue and osseointegrated bone will cause easily measurable changes in the response of the implant/abutment system. With respect to the loss of bone margin height, changes in the order of 0.2 mm should be detectable, suggesting that this technique is at least as sensitive as radiography. A partial loss of osseointegration, while not being as readily evident as a bone margin loss, would still be detectable for losses as small as 0.5 mm.

  20. Breast MRI: EUSOBI recommendations for women's information.

    PubMed

    Mann, Ritse M; Balleyguier, Corinne; Baltzer, Pascal A; Bick, Ulrich; Colin, Catherine; Cornford, Eleanor; Evans, Andrew; Fallenberg, Eva; Forrai, Gabor; Fuchsjäger, Michael H; Gilbert, Fiona J; Helbich, Thomas H; Heywang-Köbrunner, Sylvia H; Camps-Herrero, Julia; Kuhl, Christiane K; Martincich, Laura; Pediconi, Federica; Panizza, Pietro; Pina, Luis J; Pijnappel, Ruud M; Pinker-Domenig, Katja; Skaane, Per; Sardanelli, Francesco

    2015-12-01

    This paper summarizes information about breast MRI to be provided to women and referring physicians. After listing contraindications, procedure details are described, stressing the need for correct scheduling and not moving during the examination. The structured report including BI-RADS® categories and further actions after a breast MRI examination are discussed. Breast MRI is a very sensitive modality, significantly improving screening in high-risk women. It also has a role in clinical diagnosis, problem solving, and staging, impacting on patient management. However, it is not a perfect test, and occasionally breast cancers can be missed. Therefore, clinical and other imaging findings (from mammography/ultrasound) should also be considered. Conversely, MRI may detect lesions not visible on other imaging modalities turning out to be benign (false positives). These risks should be discussed with women before a breast MRI is requested/performed. Because breast MRI drawbacks depend upon the indication for the examination, basic information for the most important breast MRI indications is presented. Seventeen notes and five frequently asked questions formulated for use as direct communication to women are provided. The text was reviewed by Europa Donna-The European Breast Cancer Coalition to ensure that it can be easily understood by women undergoing MRI. • Information on breast MRI concerns advantages/disadvantages and preparation to the examination • Claustrophobia, implantable devices, allergic predisposition, and renal function should be checked • Before menopause, scheduling on day 7-14 of the cycle is preferred • During the examination, it is highly important that the patient keeps still • Availability of prior examinations improves accuracy of breast MRI interpretation.

  1. Cochlear implants.

    PubMed

    Connell, Sarah S; Balkany, Thomas J

    2006-08-01

    Cochlear implants are cost-effective auditory prostheses that safely provide a high-quality sensation of hearing to adults who are severely or profoundly deaf. In the past 5 years, progress has been made in hardware and software design, candidate selection, surgical techniques, device programming, education and rehabilitation,and, most importantly, outcomes. Cochlear implantation in the elderly is well tolerated and provides marked improvement in auditory performance and psychosocial functioning.

  2. Contraceptive implants.

    PubMed

    McDonald-Mosley, Raegan; Burke, Anne E

    2010-03-01

    Implantable contraception has been extensively used worldwide. Implants are one of the most effective and reversible methods of contraception available. These devices may be particularly appropriate for certain populations of women, including women who cannot use estrogen-containing contraception. Implants are safe for use by women with many chronic medical problems. The newest implant, Implanon (Organon International, Oss, The Netherlands), is the only device currently available in the United States and was approved in 2006. It is registered for 3 years of pregnancy prevention. Contraceptive implants have failure rates similar to tubal ligation, and yet they are readily reversible with a return to fertility within days of removal. Moreover, these contraceptive devices can be safely placed in the immediate postpartum period, ensuring good contraceptive coverage for women who may be at risk for an unintended pregnancy. Irregular bleeding is a common side effect for all progestin-only contraceptive implants. Preinsertion counseling should address possible side effects, and treatment may be offered to women who experience prolonged or frequent bleeding.

  3. MRI analyses show that kinesio taping affects much more than just the targeted superficial tissues and causes heterogeneous deformations within the whole limb.

    PubMed

    Pamuk, Uluç; Yucesoy, Can A

    2015-12-16

    Kinesio taping (KT) is widely used in the treatment of sports injuries and various neuro-musculoskeletal disorders. However, it is considered as selectively effective on targeted tissues and its mechanical effects have not been quantified objectively. Ascribed to continuity of muscular and connective tissues, mechanical loading imposed can have widespread heterogeneous effects. The aim was to characterize the mechanical effects of KT objectively and to test the hypotheses that KT causes acutely, local deformations not necessarily (I) in agreement with tape adhering direction and (II) limited to the directly targeted tissues. High-resolution 3D magnetic resonance image sets were acquired in healthy human subjects (n=5) prior to and acutely after KT application over the skin along m. tibialis anterior (TA). Hip, knee and ankle angles were kept constant. Demons image registration algorithm was used to calculate local tissue deformations within the lower leg, in vivo. Mean peak tissue strains were significantly higher than strain artifacts. Only KT-to-TA region in part shows local deformations in agreement with tape adhering direction whereas, superficial skin, the rest of KT-to-TA and TA regions show deformations (up to 51.5% length change) in other directions. Non-targeted tissues also show sizable heterogeneous deformations, but in smaller amplitudes. Inter-subject variability is notable. Magnetic resonance imaging analyses allow for a detailed assessment of local tissue deformation occurring acutely after KT application. The findings confirm our hypotheses and characterize how KT affects the underlying tissues, both immediately targeted and distant. This allows revealing mechanisms that can affect clinical outcomes of KT objectively.

  4. The epithelial interface with osseointegrated implants.

    PubMed

    Kellett, M; Smith, G A

    1991-01-01

    The development of osseointegration has generated interest in the field of intraoral and maxillofacial implantology. There is well documented evidence of a high level of success in achieving osseointegration, using titanium and alumina-ceramic implant materials. Long term retention of intraoral implants appears in part, to be dependent upon the integrity of the epithelium/implant interface. This paper presents the design features of two commercially available systems Intra-Mobile-Zylinder (IMZ) and Tubingen (Frialit), which represent titanium and alumina-ceramic implants respectively, and reviews current knowledge of the nature of the epithelial junction to implant materials and the bacterial flora associated with successful and failing implants. Implant failure may be caused by a site specific infection with a similar ecosystem and bacterial flora to that found in periodontal disease. Care in patient selection and maintenance of a healthy epithelial junction are essential for the long term function of osseointegrated implants.

  5. Visualization of Medpor implants using surface rendering.

    PubMed

    Wang, Meng; Gui, Lai; Liu, Xiao-Jing

    2011-09-01

    The Medpor surgical implant is one of the easiest implants in clinical practice, especially in craniomaxillofacial surgery. It is often used as a bone substitute material for the repair of skull defects and facial deformities. The Medpor implant has several advantages but its use is limited because it is radiolucent in both direct radiography and conventional computed tomography, causing serious problems with visualization. In this study, a new technique for visualizing Medpor implants was evaluated in 10 patients who had undergone facial reconstruction using the material. Continuous volume scans were made using a 16-channel tomographic scanner and 3D reconstruction software was used to create surface renderings. The threshold values for surface renderings of the implant ranged from -70 HU to -20 HU, with bone as the default. The shape of the implants and the spatial relationship between bone and implant could both be displayed. Surface rendering can allow successful visualization of Medpor implants in the body.

  6. Implant fractures: Rare but not exceptional

    PubMed Central

    Sanivarapu, Sahitya; Moogla, Srinivas; Kuntcham, Rupa Sruthi; Kolaparthy, Lakshmi Kanth

    2016-01-01

    Fabrication of dentures aided with implants has become a preferred treatment option for rehabilitation of completely and partially edentulous patients when durability is concerned. Simulation to natural teeth in terms of esthetics and to a greater extent in function can be considered as key elements in the raise of implant dentistry worldwide. Despite its high success rate, therapy with osseointegrated dental implants is not free of complications. Implant failure can occur for other reasons, with implant fracture being one of the major reasons for late failure. Although the incidence of implant fractures may be low, it invariably effects the patient and also clinician. Thus, sound evidence based knowledge of cause of fracture is mandatory for that careful treatment that can reduce the incidence of fracture helping in a better treatment plan. The aim of this review is to enlighten the various causes of implant fracture. PMID:27041830

  7. Safety of magnetic resonance imaging in patients with implanted cardiac prostheses and metallic cardiovascular electronic devices.

    PubMed

    Baikoussis, Nikolaos G; Apostolakis, Efstratios; Papakonstantinou, Nikolaos A; Sarantitis, Ioannis; Dougenis, Dimitrios

    2011-06-01

    Magnetic resonance imaging (MRI) in patients with implanted cardiac prostheses and metallic cardiovascular electronic devices is sometimes a risky procedure. Thus MRI in these patients should be performed when it is the only examination able to help with the diagnosis. Moreover the diagnostic benefit must outweigh the risks. Coronary artery stents, prosthetic cardiac valves, metal sternal sutures, mediastinal vascular clips, and epicardial pacing wires are not contraindications for MRI, in contrast to pacemakers and implantable cardioverter-defibrillators. Appropriate patient selection and precautions ensure MRI safety. However it is commonly accepted that although hundreds of patients with pacemakers or implantable cardioverter-defibrillators have undergone safe MRI scanning, it is not a safe procedure. Currently, heating of the pacemaker lead is the major problem undermining MRI safety. According to the US Food and Drug Administration (FDA), there are currently neither "MRI-safe" nor "MRI-compatible" pacemakers and implantable cardioverter-defibrillators. In this article we review the international literature in regard to safety during MRI of patients with implanted cardiac prostheses and metallic cardiovascular electronic devices. Copyright © 2011 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  8. Managing an extreme peri-implantitis.

    PubMed

    Materni, A

    2013-09-01

    Peri-implantitis leads to gradual peri-implant bone loss. Severe and extreme cases lead to complete implant failure and imply lost implants have to be removed. The aim of the present report is to present a case where an extreme peri-implantitis, causing complete peri-implant bone loss, was managed successfully. A patient already rehabilitated with a prosthesis supported by two implants at positions 3.4 and 3.6 presented with severe peri-implantitis affecting both implants. Initial probing depths were 11 and 9 mm respectively. Implant at position 3.4 showed a bone-implant gap ≥3 mm all around it, but was kept firmly in place by the prosthesis, still supported by the other implant. The patient refused to have her prosthesis removed. In an attempt to save it anyway, after debridement, sandblasting and decontamination of both implant surfaces an enzyme-deantigenic collagenic bone substitute was grafted. Controls followed at 1, 3, 5 and 12 months after surgery. Radiographic exams showed radio-opacity at the grafted sites to gradually increase over time. Postoperative probing depth gain, 7 and 6 mm respectively at position 3.4 and 3.6 remained unchanged at all follow-up controls. After 12 months the patient is asymptomatic and the failed implant can be considered restored. The way we managed this extreme peri-implantitis case has allowed to give clinical success even if, to comply to the patient's will, the best clinical, evidence-based treatment, was not performed. The implant that was otherwise lost was successfully recovered. As an hypothesis, a new osseointegration process could have occurred between the implant and the newly formed bone.

  9. An implant-supported removable partial denture for a patient with post-inflammatory scar contracture caused by burn complications: a clinical report

    PubMed Central

    Kim, Jee-Hwan

    2012-01-01

    The scars and contracture around the oral-facial region may cause difficulty in prosthodontic treatment to restore esthetics and function for the patients, who suffered severe burns. This article presents a technique that uses a fixed partial denture prepared with a conventional milling technique and an attachment to support anterior cantilever removable partial denture, thereby providing a more esthetically acceptable and functional result. PMID:22439102

  10. Further studies on the effects of magnetic resonance imaging fields on middle ear implants.

    PubMed

    Applebaum, E L; Valvassori, G E

    1990-10-01

    We investigated the effects of magnetic resonance imaging (MRI) fields on 21 stapedectomy prostheses and other middle ear implants and two different receiver-stimulator modules from 22-channel cochlear implants. None of the middle ear implants was displaced by the magnetic field, except for one platinum-stainless steel stapedectomy piston. Magnetism was not induced in any of the middle ear implants subjected to prolonged exposure in the MRI scanner. We conclude that MRI could pose a hazard to patients who have had stapedectomy using certain platinum-stainless steel piston prostheses and to patients with cochlear implants. Magnetic resonance imaging should pose no hazard to patients who have had the other middle ear implants reported on in this and our previous investigation.

  11. Magnetic Resonance Imaging (MRI): Brain (For Parents)

    MedlinePlus

    ... cause a problem near a strong magnetic field. Electronic devices aren't permitted in the MRI room. ... child may be given headphones to listen to music or earplugs to block the noise, and will ...

  12. Changes in the surface of bone and acid-etched and sandblasted implants following implantation and removal

    PubMed Central

    Eroglu, Cennet Neslihan; Ertugrul, Abdullah Seckin; Eskitascioglu, Murat; Eskitascioglu, Gurcan

    2016-01-01

    Objective: The aim of this study was to determine whether there are any changes in the surface of bone or implant structures following the removal of a screwed dental implant. Materials and Methods: For this, six individual samples of acid-etched and sandblasted implants from three different manufacturers’ implant systems were used. They were screwed in a D1 bovine bone, and they were removed after primary stabilization. The bone and implant surfaces are evaluated with scanning electron microscope. Results: Through examination of the surfaces of the bone prior to implantation and of the used and unused implant surfaces, it was found that inhomogeneity in the implant surface can cause microcracking in the bone. Conclusions: This is attributed to the stress induced during the implantation of self-tapping implants and suggests that a tap drill may be required in some instances to protect the implant surface. PMID:27011744

  13. Hip Implant Modified To Increase Probability Of Retention

    NASA Technical Reports Server (NTRS)

    Canabal, Francisco, III

    1995-01-01

    Modification in design of hip implant proposed to increase likelihood of retention of implant in femur after hip-repair surgery. Decreases likelihood of patient distress and expense associated with repetition of surgery after failed implant procedure. Intended to provide more favorable flow of cement used to bind implant in proximal extreme end of femur, reducing structural flaws causing early failure of implant/femur joint.

  14. Management of dental implant fractures. A case history.

    PubMed

    Al Quran, Firas A M; Rashan, Bashar A; Al-Dwairi, Ziad N

    2009-01-01

    The widespread use of endosseous osseointegrated implants to replace missing natural teeth increases the chances of implant complications and failures, despite the high initial success rate reported in the literature. Implant fracture is one possible complication that results in ultimate failure of the dental implant. Such a complication poses a management crisis even for the most experienced clinician. This article reports on a case of implant fracture, its possible causes, and how the case was managed.

  15. Behaviour of implantable coronary stents during magnetic resonance imaging.

    PubMed

    Friedrich, Matthias G; Strohm, Oliver; Kivelitz, Dietmar; Gross, Werner; Wagner, Anja; Schulz-Menger, Jeanette; Liu, Xiaomeng; Hamm, Bernd

    1999-01-01

    BACKGROUND: Magnetic resonance imaging (MRI) becomes more and more a routine diagnostic tool in clinical cardiology. In patients undergoing MRI, metallic implants may be harmful by motion or heating under certain circumstances. Many cardiac patients have implanted intracoronary stents. However, the safety of these metallic implants and especially their temperature behaviour during MRI has not been sufficiently tested. METHODS: This study investigated motion and temperature changes of 14 different stents for intracoronary application in two clinical scanners at field strengths of 1.0 and 1.5 T. At 1.5 T these studies were repeated after implantation of the stents into the coronary arteries of excised porcine hearts. Furthermore, the clinical status of 33 patients was assessed after a cardiac MR study and compared with a group of 33 patients matched for age, sex and risk factors for restenosis. RESULTS: No visible motion of the stents was observed. Furthermore, using a highly sensitive infrared camera any significant heating of the stents during MRI could be excluded. The rate of clinical events was not different in patients after MRI as compared with the control group. CONCLUSION: It is concluded that MRI is safe in patients with the currently available intracoronary stents.

  16. Determinants of all-cause mortality in different age groups in patients with severe systolic left ventricular dysfunction receiving an implantable cardioverter defibrillator (from the Italian ClinicalService Multicenter Observational Project).

    PubMed

    Fumagalli, Stefano; Gasparini, Maurizio; Landolina, Maurizio; Lunati, Maurizio; Boriani, Giuseppe; Proclemer, Alessandro; Santini, Massimo; Mangoni, Lorenza; Padeletti, Margherita; Marchionni, Niccolò; Padeletti, Luigi

    2014-05-15

    Heart failure (HF) is a common condition in elderly patients. Despite great improvements in medical therapy, HF mortality remains high. Implantable cardioverter defibrillator (ICD) significantly lengthens the survival rate of subjects with severe HF, but little evidence exists on its effect in elderly persons. Aim of this study was to compare the age-related determinants of prognosis in a large population of patients with ICD. We divided all patients who underwent an ICD implantation in 117 Italian centers of the "ClinicalService Project" into 3 age groups (<65, 65 to 74, ≥ 75 years), and collected clinical and instrumental variables at baseline and during follow-up (median length: 27 months). Between 2004 and 2011, 6,311 patients were enrolled (5,174 men; left ventricular ejection fraction 29% ± 9%); 1,510 subjects were ≥ 75 years (23.9%; mean age 78 ± 3 years). The prevalence of co-morbidities increased with age. HF was most frequently due to coronary artery disease in the elderly, who also showed the worst New York Heart Association class. At multivariate analysis, older age, coronary artery disease, chronic obstructive pulmonary disease, chronic renal failure, diabetes, complex ventricular arrhythmias, and left ventricular ejection fraction were significant predictors of all-cause mortality. After adjustment, the hazard ratio(age group) for mortality was 22.6% less than at univariate analysis. When groups were analyzed separately, age alone predicted mortality in the oldest. In conclusion, a large proportion of our population was aged ≥ 75 years. Mortality was related to age and several co-morbidities, except for the oldest patients in whom age alone resulted predictive.

  17. Cochlear Implants

    MedlinePlus

    ... outside of the body, behind the ear. A second part is surgically placed under the skin. An implant does not restore normal hearing. It can help a person understand speech. Children and adults can benefit from them. National Institute on Deafness and Other Communication Disorders

  18. An Assessment of Hazards Caused by Electromagnetic Interaction on Humans Present near Short-Wave Physiotherapeutic Devices of Various Types Including Hazards for Users of Electronic Active Implantable Medical Devices (AIMD)

    PubMed Central

    Gryz, Krzysztof

    2013-01-01

    Leakage of electromagnetic fields (EMF) from short-wave radiofrequency physiotherapeutic diathermies (SWDs) may cause health and safety hazards affecting unintentionally exposed workers (W) or general public (GP) members (assisting patient exposed during treatment or presenting there for other reasons). Increasing use of electronic active implantable medical devices (AIMDs), by patients, attendants, and workers, needs attention because dysfunctions of these devices may be caused by electromagnetic interactions. EMF emitted by 12 SWDs (with capacitive or inductive applicators) were assessed following international guidelines on protection against EMF exposure (International Commission on Nonionizing Radiation Protection for GP and W, new European directive 2013/35/EU for W, European Recommendation for GP, and European Standard EN 50527-1 for AIMD users). Direct EMF hazards for humans near inductive applicators were identified at a distance not exceeding 45 cm for W or 62 cm for GP, but for AIMD users up to 90 cm (twice longer than that for W and 50% longer than that for GP because EMF is pulsed modulated). Near capacitive applicators emitting continuous wave, the corresponding distances were: 120 cm for W or 150 cm for both—GP or AIMD users. This assessment does not cover patients who undergo SWD treatment (but it is usually recommended for AIMD users to be careful with EMF treatment). PMID:24089662

  19. An assessment of hazards caused by electromagnetic interaction on humans present near short-wave physiotherapeutic devices of various types including hazards for users of electronic active implantable medical devices (AIMD).

    PubMed

    Karpowicz, Jolanta; Gryz, Krzysztof

    2013-01-01

    Leakage of electromagnetic fields (EMF) from short-wave radiofrequency physiotherapeutic diathermies (SWDs) may cause health and safety hazards affecting unintentionally exposed workers (W) or general public (GP) members (assisting patient exposed during treatment or presenting there for other reasons). Increasing use of electronic active implantable medical devices (AIMDs), by patients, attendants, and workers, needs attention because dysfunctions of these devices may be caused by electromagnetic interactions. EMF emitted by 12 SWDs (with capacitive or inductive applicators) were assessed following international guidelines on protection against EMF exposure (International Commission on Nonionizing Radiation Protection for GP and W, new European directive 2013/35/EU for W, European Recommendation for GP, and European Standard EN 50527-1 for AIMD users). Direct EMF hazards for humans near inductive applicators were identified at a distance not exceeding 45 cm for W or 62 cm for GP, but for AIMD users up to 90 cm (twice longer than that for W and 50% longer than that for GP because EMF is pulsed modulated). Near capacitive applicators emitting continuous wave, the corresponding distances were: 120 cm for W or 150 cm for both-GP or AIMD users. This assessment does not cover patients who undergo SWD treatment (but it is usually recommended for AIMD users to be careful with EMF treatment).

  20. Safety of Magnetic Resonance Imaging After Implantation of Stainless Steel Embolization Coils.

    PubMed

    Slesnick, Timothy C; Schreier, Jenna; Soriano, Brian D; Kutty, Shelby; Nutting, Arni C; Kim, Dennis W; Powell, Andrew J; Valente, Anne Marie

    2016-01-01

    Stainless steel embolization coils (SSEC) have been used for over four decades for vascular occlusion. Recently, the safety of these coils in a magnetic resonance environment has been called into question, with important ramifications for thousands of patients with existing coils in place. We performed a retrospective chart review at five tertiary care pediatric centers evaluating all children and young adults with implanted SSEC who underwent magnetic resonance imaging (MRI). Data reviewed included demographics, coil implantation, MRI studies, and follow-up evaluations. Complications such as heating, discomfort, or device migration were specifically sought. Two hundred and ninety-seven patients with implanted SSEC underwent 539 MRI examinations. The median age at SSEC implantation was 2.3 years (1 week-23.2 years). The MRI studies were performed a median of 7.4 years (4 days-23.1 years) after implantation. No patients experienced any reported complications associated with their MRI examinations during the study or at median follow-up post-MRI of 4.8 years (1 day-23 years). In this large, retrospective review of patients with implanted SSEC undergoing MRI, there were no reported adverse events. These findings support the recent change by Cook Medical Inc. of their standard embolization coils from a designation of magnetic resonance unsafe to conditional.

  1. Complications of Poly Implant Prothèse breast implants: the current discussion.

    PubMed

    Kolios, Leila; Hirche, Christoph; Spiethoff, Alexander; Daigeler, Adrien; Lehnhardt, Marcus

    2013-03-01

    Against the background of the current discussion about Poly Implant Prothèse (PIP, Seyne-sur-mer, France) breast implants, we want to present a case demonstrating the complications such as implant rupture, silicone dissemination and level III silicone lymphadenopathy. A 29-year-old woman with cosmetic breast augmentation with PIP implants 5 years previously showed a sensitive swelling in her right axilla and neck region. All tests to detect an infectious or lymphomatous lymphadenopathy were negative. After ultrasound and MRI, rupture of the right implant was assumed and multiple pathologically enlarged lymph nodes up to supraclavicular region were shown. An excision biopsy of one axillary lymph node was performed; the histological examination detected a strong silicone lymphadenopathy. Surgical removal of both implants as well as capsulectomy was performed and 14 axillary lymph nodes up to level II were resected. Histologic evaluation confirmed the previous results. Our case underlines the actual discussion concerning increased rupture rate and massive silicone lymphadenopathy by PIP implants. The Agence Francaise de Sécurité Sanitaire des Produits de Santé (AFSSAPS) recommends clinical and ultrasound examination every 6 months for women with PIP implants. Any rupture, suspected rupture or leakage of prosthesis should lead to its explantation as well as that of the contralateral implant. In cases of unusual signs of inflammation, histological and immunohistochemical samples are to be taken.

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

    PubMed

    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.

  3. [Cerebral circulation and metabolism in the patients with higher brain dysfunction caused by chronic minor traumatic brain injury: a study by the positron emission tomography in twenty subjects with normal MRI findings].

    PubMed

    Kabasawa, Hidehiro; Ogawa, Tetsuo; Iida, Akihiko; Matsubara, Michitaka

    2002-06-01

    Many individuals are affected on their higher brain functions, such as intelligence, memory, and attention, even after minor traumatic brain injury (MTBI). Although higher brain dysfunction is based on impairment of the cerbral circulation and metabolism, the precise relationship between them remains unknown. This study was undertaken to investigate the relationship between the cerebral circulation or cerebral metabolism and higher brain dysfunction. Twenty subjects with higher brain dysfunction caused by chronic MTBI were studied. They had no abnormal MRI findings. The full-scale intelligence quotient (FIQ) were quantitatively evaluated by the Wechsler Adult Intelligence Scale-Revised (WAIS-R), and the subjects were classified into the normal group and the impaired group. Concurrent with the evaluation of FIQ, positron emission tomography (PET) was performed by the steady state method with 15O gases inhalation. Regional cerebral blood flow (rCBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) were calculated in the bilateral frontal, parietal, temporal, and occipital lobe. First, of all twenty subjects, we investigated rCBF, OEF and CMRO2 in all regions. Then we compared rCBF, OEF, and CMRO2 between the normal group and the impaired group based on FIQ score. We also studied the change of FIQ score of 13 subjects 9.3 months after the first evaluation. In addition, we investigated the change of rCBF, OEF and CMRO2 along with the improvement of FIQ score. Although rCBF and OEF of all subjects were within the normal range in all regions, CMRO2 of more than half of subjects was under the lower normal limit in all regions except in the right occipital lobe, showing the presence of "relative luxury perfusion". Comparison of rCBF, OEF and CMRO2 between normal group and impaired group revealed that CMRO2 of the impaired group was significantly lower than that of the normal group in the bilateral frontal, temporal, and occipital lobe. After

  4. Short Implants: New Horizon in Implant Dentistry

    PubMed Central

    Gulati, Manisha; Garg, Meenu; Pathak, Chetan

    2016-01-01

    The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration. PMID:27790598

  5. Short Implants: New Horizon in Implant Dentistry.

    PubMed

    Jain, Neha; Gulati, Manisha; Garg, Meenu; Pathak, Chetan

    2016-09-01

    The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration.

  6. Stability, Visibility, and Histologic Analysis of a New Implanted Fiducial for Use as a Kilovoltage Radiographic or Radioactive Marker for Patient Positioning and Monitoring in Radiotherapy

    SciTech Connect

    Neustadter, David; Tune, Michal; Zaretsky, Asaph; Shofti, Rona; Kushnir, Arnon; Harel, Tami; Carmi-Yinon, Dafna; Corn, Ben M.S.

    2010-07-15

    Purpose: To analyze the stability, visibility, and histology of a novel implantable soft-tissue marker (nonradioactive and radioactive) implanted in dog prostate and rabbit liver. Methods and Materials: A total of 34 nonradioactive and 35 radioactive markers were implanted in 1 dog and 16 rabbits. Stability was assessed by measuring intermarker distance (IMD) variation relative to IMDs at implantation. The IMDs were measured weekly for 4 months in the dog and biweekly for 2-4 weeks in the rabbits. Ultrasound and X-ray imaging were performed on all subjects. Computed tomography and MRI were performed on the dog. Histologic analysis was performed on the rabbits after 2 or 4 months. Results: A total of 139 measurements had a mean ({+-} SD) absolute IMD variation of 1.1 {+-} 1.1 mm. These IMD variations are consistent with those reported in the literature as due to random organ deformation. The markers were visible, identifiable, and induced minimal or no image artifacts in all tested imaging modalities. Histologic analysis revealed that all pathologic changes were highly localized and not expected to be clinically significant. Conclusions: The markers were stable from the time of implantation. The markers were found to be compatible with all common medical imaging modalities. The markers caused no significant histologic effects. With respect to marker stability, visibility, and histologic analysis these implanted fiducials are appropriate for soft-tissue target positioning in radiotherapy.

  7. Biomedical Imaging in Implantable Drug Delivery Systems

    PubMed Central

    Zhou, Haoyan; Hernandez, Christopher; Goss, Monika; Gawlik, Anna; Exner, Agata A.

    2015-01-01

    Implantable drug delivery systems (DDS) provide a platform for sustained release of therapeutic agents over a period of weeks to months and sometimes years. Such strategies are typically used clinically to increase patient compliance by replacing frequent administration of drugs such as contraceptives and hormones to maintain plasma concentration within the therapeutic window. Implantable or injectable systems have also been investigated as a means of local drug administration which favors high drug concentration at a site of interest, such as a tumor, while reducing systemic drug exposure to minimize unwanted side effects. Significant advances in the field of local DDS have led to increasingly sophisticated technology with new challenges including quantification of local and systemic pharmacokinetics and implant-body interactions. Because many of these sought-after parameters are highly dependent on the tissue properties at the implantation site, and rarely represented adequately with in vitro models, new nondestructive techniques that can be used to study implants in situ are highly desirable. Versatile imaging tools can meet this need and provide quantitative data on morphological and functional aspects of implantable systems. The focus of this review article is an overview of current biomedical imaging techniques, including magnetic resonance imaging (MRI), ultrasound imaging, optical imaging, X-ray and computed tomography (CT), and their application in evaluation of implantable DDS. PMID:25418857

  8. MRI Safety during Pregnancy

    MedlinePlus

    ... 20 to 40 minutes. top of page Contrast material For some MRI exams, a contrast material called gadolinium will need to be injected into a vein in the arm. While contrast material sometimes improves the MRI images, during pregnancy the ...

  9. Sinus MRI scan

    MedlinePlus

    ... sinuses. The test is noninvasive. MRI uses powerful magnets and radio waves instead of radiation. Signals from ... in the eyes. Because the MRI contains a magnet, metal-containing objects such as pens, pocketknives, and ...

  10. Arm MRI scan

    MedlinePlus

    ... arm MRI (magnetic resonance imaging) scan uses strong magnets to create pictures of the upper and lower ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed into the room ...

  11. Magnetic Resonance Imaging (MRI)

    MedlinePlus

    ... an image. Repeated exposure can be harmful.An MRI scan takes longer to perform (30 to 60 minutes, ... a treatment plan.Depending on your symptoms, an MRI will scan a specific portion of your body to diagnose: ...

  12. MRI Safety during Pregnancy

    MedlinePlus

    ... 20 to 40 minutes. top of page Contrast material For some MRI exams, a contrast material called gadolinium will need to be injected into a vein in the arm. While contrast material sometimes improves the MRI images, during pregnancy the ...

  13. Noninvasive management of cochlear implant's inner magnet displacement after magnetic resonance.

    PubMed

    Di Nardo, Walter; Giannantonio, Sara; Schinaia, Lorenzo; De Corso, Eugenio; Paludetti, Gaetano

    2013-03-01

    MRI is a widespread and greatly helpful diagnostic tool, yet its use on cochlear implant patients is restricted by the presence of an inner magnet. We report on a case of magnet dislodgment after 1.5T MRI in a 31-year-old female with a Hi-Res 90K cochlear implant. In this case, it was possible to implement an alternative, totally noninvasive approach based on an external manual repositioning rather than a surgical procedure of the displaced magnet.

  14. Detection and Quantification of Magnetically Labeled Cells by Cellular MRI

    PubMed Central

    Liu, Wei; Frank, Joseph A.

    2008-01-01

    Labeling cells with superparamagnetic iron oxide (SPIO) nanoparticles, paramagnetic contrast agent (gadolinium) or perfluorocarbons allows for the possibility of tracking single or clusters of labeled cells within target tissues following either direct implantation or intravenous injection. This review summarizes the practical issues regarding detection and quantification of magnetically labeled cells with various MRI contrast agents with a focus on SPIO nanoparticles. PMID:18995978

  15. A Virtual Patient Simulator Based on Human Connectome and 7 T MRI for Deep Brain Stimulation

    PubMed Central

    Bonmassar, Giorgio; Angelone, Leonardo M.; Makris, Nikos

    2015-01-01

    This paper presents a virtual model of patients with Deep Brain Stimulation implants. The model is based on Human Connectome and 7 Tesla Magnetic Resonance Imaging (MRI) data. We envision that the proposed virtual patient simulator will enable radio frequency power dosimetry on patients with deep brain stimulation implants undergoing MRI. Results from the proposed virtual patient study may facilitate the use of clinical MRI instead of computed tomography scans. The virtual patient will be flexible and morphable to relate to patient-specific neurological and psychiatric conditions such as Obsessive Compulsive Disorder, which benefit from deep brain stimulation. PMID:25705324

  16. MRI findings in pediatric patients with scurvy.

    PubMed

    Gulko, Edwin; Collins, Lee K; Murphy, Robyn C; Thornhill, Beverly A; Taragin, Benjamin H

    2015-02-01

    In modern times scurvy is a rarely encountered disease caused by ascorbic acid (vitamin C) deficiency. However, sporadic cases of scurvy persist, particularly within the pediatric population. Recent individual case reports highlight an increased incidence of scurvy among patients with autism or developmental delay, with isolated case reports detailing the magnetic resonance imaging (MRI) findings of scurvy in these pediatric populations. We present the MRI findings of scurvy in four patients with autism or developmental delay, and review the literature on MRI findings in pediatric patients with scurvy. Despite its rarity, the radiologist must consider scurvy in a pediatric patient with a restricted diet presenting with arthralgia or myalgia.

  17. Multimodal MRI of experimental stroke

    PubMed Central

    Duong, Timothy Q

    2014-01-01

    Stroke is the fourth leading cause of death and the leading cause of long-term disability in the United States. Brain imaging data from experimental stroke models and stroke patients have shown that there is often a gradual progression of potentially reversible ischemic injury toward infarction. Reestablishing tissue perfusion and/or treating with neuroprotective drugs in a timely fashion are expected to salvage some ischemic tissues. Diffusion-weighted imaging based on magnetic resonance imaging (MRI) in which contrast is based on water motion can detect ischemic injury within minutes after onsets, whereas computed tomography and other imaging modalities fail to detect stroke injury for at least a few hours. Along with quantitative perfusion imaging, the perfusion-diffusion mismatch which approximates the ischemic penumbra could be imaged non-invasively. This review describes recent progresses in the development and application of multimodal MRI and image analysis techniques to study ischemic tissue at risk in experimental stroke in rats. PMID:24323751

  18. [Bruxism and overload of periodontium and implants].

    PubMed

    Jacobs, R; De Laat, A

    2000-07-01

    Bruxism is responsible for occlusal tooth wear but can not induce nor aggravate gingivitis or periodontitis. Bruxism induces jiggling forces, which cause a clinical tooth hypermobility, radiologically seen as a widened periodontal space. Although there is no direct causal relation between bruxism and implant failure, implant overload may lead to fractures of the components and bone loss.

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

    PubMed Central

    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

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

    PubMed

    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.

  1. The Clinical Implications of Poly Implant Prothèse Breast Implants: An Overview

    PubMed Central

    Wazir, Umar; Kasem, Abdul

    2015-01-01

    Mammary implants marketed by Poly Implant Prothèse (PIP) were found to contain industrial grade silicone and this caused heightened anxiety and extensive publicity regarding their safety in humans. These implants were used in a large number of patients worldwide for augmentation or breast reconstruction. We reviewed articles identified by searches of Medline, PubMed, Embase, and Google Scholar databases up to May 2014 using the terms: "PIP", "Poly Implant Prothèse", "breast implants" and "augmentation mammoplasty" "siloxanes" or "silicone". In addition the websites of regulating bodies in Europe, USA, and Australia were searched for reports related to PIP mammary implants. PIP mammary implants are more likely to rupture than other implants and can cause adverse effects in the short to the medium term related to the symptoms of rupture such as pain, lumps in the breast and axilla and anxiety. Based on peer-reviewed published studies we have calculated an overall rupture rate of 14.5% (383/2,635) for PIP implants. However, there is no evidence that PIP implant rupture causes long-term adverse health effects in humans so far. Silicone lymphadenopathy represents a foreign body reaction and should be treated conservatively. The long-term adverse effects usually arise from inappropriate extensive surgery, such as axillary lymph node dissection or extensive resection of breast tissue due to silicone leakage. PMID:25606483

  2. Dental Implant Surgery

    MedlinePlus

    Dental implant surgery Overview By Mayo Clinic Staff Dental implant surgery is a procedure that replaces tooth roots ... that look and function much like real ones. Dental implant surgery can offer a welcome alternative to dentures ...

  3. Hip Implant Systems

    MedlinePlus

    ... Medical Devices Products and Medical Procedures Implants and Prosthetics Metal-on-Metal Hip Implants Hip Implants Share ... femoral head) is removed and replaced with a prosthetic ball made of metal or ceramic, and the ...

  4. Impact of magnetic resonance imaging on ventricular tachyarrhythmia sensing: Results of the Evera MRI Study.

    PubMed

    Gold, Michael R; Sommer, Torsten; Schwitter, Juerg; Kanal, Emanuel; Bernabei, Matthew A; Love, Charles J; Surber, Ralf; Ramza, Brian; Cerkvenik, Jeffrey; Merkely, Béla

    2016-08-01

    Studies have shown that magnetic resonance imaging (MRI) conditional pacemakers experience no significant effect from MRI on device function, sensing, or pacing. More recently, similar safety outcomes were demonstrated with MRI conditional defibrillators (implantable cardioverter-defibrillator [ICD]), but the impact on ventricular arrhythmias has not been assessed. The purpose of this study was to assess the effect of MRI on ICD sensing and treatment of ventricular tachyarrhythmias. The Evera MRI Study was a worldwide trial of 156 patients implanted with an ICD designed to be MRI conditional. Device-detected spontaneous and induced ventricular tachycardia/ventricular fibrillation (VT/VF) episodes occurring before and after whole body MRI were evaluated by a blinded episode review committee. Detection delay was computed as the sum of RR intervals of undersensed beats. A ≥5-second delay in detection due to undersensing was prospectively defined as clinically significant. Post-MRI, there were 22 polymorphic VT/VF episodes in 21 patients, with 16 of these patients having 17 VT/VF episodes pre-MRI. Therapy was successful for all episodes, with no failures to treat or terminate arrhythmias. The mean detection delay due to undersensing pre- and post-MRI was 0.60 ± 0.59 and 0.33 ± 0.63 seconds, respectively (P = .17). The maximum detection delay was 2.19 seconds pre-MRI and 2.87 seconds post-MRI. Of the 17 pre-MRI episodes, 14 (82%) had some detection delay as compared with 11 of 22 (50%) post-MRI episodes (P = .03); no detection delay was clinically significant. Detection and treatment of VT/VF was excellent, with no detection delays or significant impact of MRI observed. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  5. [Cochlear implants].

    PubMed

    Lehnhardt, E; Battmer, R D; Nakahodo, K; Laszig, R

    1986-07-01

    Since the middle of 1984, the HNO-Klinik der Medizinischen Hochschule Hannover has provided deaf adults with a 22-channel cochlear implant (CI) device of Clark-NUCLEUS. The digital working system consists of an implantable stimulator/receiver and an externally worn speech processor. Energy and signals are transmitted transcutaneously via a transmitter coil. During the prevailing 26 operations (April 1986) the electrode array could be inserted at least 17 mm into the cochlea. The threshold and comfort levels of all patients were adjusted very quickly; the dynamic range usually grows during the first postoperative weeks. The individual rehabilitation results vary greatly, but all patients show a significant increase of vowel and consonant comprehension while using the speech processor and an improvement of words understood per minute in speech tracking from lip-reading alone to lip-reading with speech processor. Four months after surgery seven of 17 patients (group I) are able to understand on average 42.7 words per minute by speech tracking without lip-reading. Six patients (group II) recognise 69.2% of vowels and 42.5% of consonants by speech processor alone. Four patients (group III) can correctly repeat only vowels (52.3%) without lip-reading, but using the speech processor together with lip reading they have an improvement in consonant understanding of 37.9% and under freefield conditions they are able to understand up to 17.8% numbers of the Freiburg speech test.

  6. Implant periapical lesion: Diagnosis and treatment

    PubMed Central

    Maestre-Ferrín, Laura; Cervera-Ballester, Juan; Peñarrocha-Oltra, David

    2012-01-01

    The implant periapical lesion is the infectious-inflammatory process of the tissues surrounding the implant apex. It may be caused by different factors: contamination of the implant surface, overheating of bone during drilling, preparation of a longer implant bed than the implant itself, and pre-existing bone disease. Diagnosis is achieved by studying the presence of symptoms and signs such us pain, swelling, suppuration or fistula; in the radiograph an implant periapical radiolucency may appear. A diagnostic classification is proposed to establish the stage of the lesion, and determine the best treatment option accordingly. The following stages are distinguished: acute apical periimplantitis (non-suppurated and suppurated) and subcacute (or suppurated-fistulized) apical periimplantitis. The most adequate treatment of this pathology in the acute stage and in the subacute stage if there is no loss of implant stability is apical surgery. In the subacute stage, if there is implant mobility, the extraction of the implant is necessary. Key words:Implant periapical lesion, apical periimplantitis, retrograde periimplantitis. PMID:22926472

  7. Therapy using implanted organic bioelectronics

    PubMed Central

    Jonsson, Amanda; Song, Zhiyang; Nilsson, David; Meyerson, Björn A.; Simon, Daniel T.; Linderoth, Bengt; Berggren, Magnus

    2015-01-01

    Many drugs provide their therapeutic action only at specific sites in the body, but are administered in ways that cause the drug’s spread throughout the organism. This can lead to serious side effects. Local delivery from an implanted device may avoid these issues, especially if the delivery rate can be tuned according to the need of the patient. We turned to electronically and ionically conducting polymers to design a device that could be implanted and used for local electrically controlled delivery of therapeutics. The conducting polymers in our device allow electronic pulses to be transduced into biological signals, in the form of ionic and molecular fluxes, which provide a way of interfacing biology with electronics. Devices based on conducting polymers and polyelectrolytes have been demonstrated in controlled substance delivery to neural tissue, biosensing, and neural recording and stimulation. While providing proof of principle of bioelectronic integration, such demonstrations have been performed in vitro or in anesthetized animals. Here, we demonstrate the efficacy of an implantable organic electronic delivery device for the treatment of neuropathic pain in an animal model. Devices were implanted onto the spinal cord of rats, and 2 days after implantation, local delivery of the inhibitory neurotransmitter γ-aminobutyric acid (GABA) was initiated. Highly localized delivery resulted in a significant decrease in pain response with low dosage and no observable side effects. This demonstration of organic bioelectronics-based therapy in awake animals illustrates a viable alternative to existing pain treatments, paving the way for future implantable bioelectronic therapeutics. PMID:26601181

  8. Occlusal considerations in implant therapy: clinical guidelines with biomechanical rationale.

    PubMed

    Kim, Yongsik; Oh, Tae-Ju; Misch, Carl E; Wang, Hom-Lay

    2005-02-01

    Due to lack of the periodontal ligament, osseointegrated implants, unlike natural teeth, react biomechanically in a different fashion to occlusal force. It is therefore believed that dental implants may be more prone to occlusal overloading, which is often regarded as one of the potential causes for peri-implant bone loss and failure of the implant/implant prosthesis. Overloading factors that may negatively influence on implant longevity include large cantilevers, parafunctions, improper occlusal designs, and premature contacts. Hence, it is important to control implant occlusion within physiologic limit and thus provide optimal implant load to ensure a long-term implant success. The purposes of this paper are to discuss the importance of implant occlusion for implant longevity and to provide clinical guidelines of optimal implant occlusion and possible solutions managing complications related to implant occlusion. It must be emphasized that currently there is no evidence-based, implant-specific concept of occlusion. Future studies in this area are needed to clarify the relationship between occlusion and implant success.

  9. The peri-implantitis: implant surfaces, microstructure, and physicochemical aspects.

    PubMed

    Mouhyi, Jaafar; Dohan Ehrenfest, David M; Albrektsson, Tomas

    2012-04-01

    There are two ways of looking at secondary failures of osseointegration; one is to reflect on possible causes for the failure, the other focuses on the pathology per se. In the first case, background factors such as mechanical trauma (adverse loading) or inflammations/infections are being discussed as the cause of failure. Then peri-implantitis is a term reserved for implant disturbance due to inflammation/infections only. However, irrespective of the original reason for the failure being adverse loading or inflammation/infection, the end result with bone resorption and inflammation may be very similar. Hence, in the present article, an alternative outlook has been chosen. Trigerring factors for peri-implantitis are generally gathered under four categories: lesions of peri-implant attachment, presence of aggressive bacteria, excessive mechanical stress, and corrosion. If only one of these factors would start a chain reaction leading to lesions, then the other factors may combine to worsen the condition. With other words, peri-implantitis is a general term dependent on a synergy of several factors, irrespective of the precise reason for first triggering off symptoms. © 2009 Wiley Periodicals, Inc.

  10. The breast implant controversy.

    PubMed

    Cook, R R; Harrison, M C; LeVier, R R

    1994-02-01

    The breast implant issue is a "bad news/good news" story. For many women with implants, the controversy has caused a fair degree of anxiety which may or may not be resolved as further information becomes available. It has also taken its toll on Dow Corning. Whole lines of medical products have been eliminated or are being phase out. The development of new medical applications has been terminated. As a consequence, employees have lost their jobs. What the effect will be on the biomedical industry as a whole remains to be seen (11). While silicones have been an important component in various medical devices, it is likely that other materials can be used as replacements. However, suppliers of non-silicone materials are also reevaluating their role in this market. For example, Du Pont, the nation's largest chemical company, has determined that the unpredictable and excessive costs of doing business with manufacturers of implantable medical devices no longer justifies the unrestricted sale of standard raw materials into this industry. Other companies are quietly following suit. On the up side, it is possible that the research being driven by this controversy will result in a greater understanding of the immunologic implications of xenobiotics, of the importance of nonbiased observations, of the need for ready access to valid data sets, and of the opportunity for valid scientific information to guide legal decisions. Only time will tell.

  11. Implant marketing: cost effective implant dentistry.

    PubMed

    Wohrle, P S; Levin, R P

    1996-01-01

    The application of the KAL-Technique to the field of implant dentistry allows both patients and dental practices to benefit. It is an exciting advance that decreases frustration and stress in providing implant procedures and lowers overall costs. Professionals using the KAL-Technique report significant predictability in achieving passive framework fit. They are also lowering overall cost of implant cases, which increases the number of patients who can accept implant treatment. It has been well established that the more individuals in a practice that receive implants, the more referrals a practice will gain. This is because implant patients find tremendous advances in the quality of life, and do not hesitate to tell others who can take advantage of this opportunity. Implant dentistry is one of the fastest growing fields in dentistry today. While some other areas of dentistry begin to decline in volume and need, implant dentistry provides the opportunity to keep practices strong and to insure long-term success.

  12. Deep brain stimulation in the setting of cochlear implants: Case report and literature review

    PubMed Central

    Buell, Thomas J.; Ksendzovsky, Alexander; Shah, Binit B.; Kesser, Bradley W.; Elias, W. Jeffrey

    2015-01-01

    Background/Aims As technology continues to advance for our aging population, an increasing number of DBS candidates will have preexisting implanted electrical devices. In this article, we discuss safe and successful DBS in a patient with Parkinson's disease (PD) and bilateral cochlear implants. Methods A 70 year-old male with PD and bilateral cochlear implants underwent successful microelectrode-guided DBS implantation into bilateral subthalamic nuclei (STN). The patient's cochlear implant magnets were removed and replaced in outpatient clinic for pre-operative MRI and stereotactic targeting. The cochlear implants were turned off intraoperatively for STN microelectrode recordings. Results Precise, MRI-guided stereotactic DBS implantation was possible. Intraoperative high-fidelity microelectrode recordings confirmed STN neurons with the cochlear implants turned off. These recordings were not possible with active cochlear implant devices. Our literature review describes the other approaches/techniques that have been used to manage DBS surgery in the setting of cochlear implants. Conclusions Despite the risk of electrical interference between implanted medical devices, DBS and cochlear implants may be safe and compatible in the same patient if necessary precautions are taken. PMID:25998722

  13. Implantable visual prostheses.

    PubMed

    Thanos, S; Heiduschka, P; Stupp, T

    2007-01-01

    Visual impairment and blindness is primarily caused by optic neuropathies like injuries and glaucomas, as well as retinopathies like agerelated macular degeneration (MD), systemic diseases like diabetes, hypertonia and hereditary retinitis pigmentosa (RP). These pathological conditions may affect retinal photoreceptors, or retinal pigment epithelium, or particular subsets of retinal neurons, and in particular retinal ganglion cells (RGCs). The RGCs which connect the retina with the brain are unique cells with extremely long axons bridging the distance from the retina to visual relays within the thalamus and midbrain, being therefore vulnerable to heterogeneous pathological conditions along this pathway. When becoming mature, RGCs loose the ability to divide and to regenerate their accidentally or experimentally injured axons. Consequently, any loss of RGCs is irreversible and results to loss of visual function. The advent of micro- and nanotechnology, and the construction of artificial implants prompted to create visual prostheses which aimed at compensating for the loss of visual function in particular cases. The purpose of the present contribution is to review the considerable engineering expertise that is essential to fabricate current visual prostheses in connection with their functional features and applicability to the animal and human eye. In this chapter, 1) Retinal and cortical implants are introduced, with particular emphasis given to the requirements they have to fulfil in order to replace very complex functions like vision. 2) Advanced work on material research is presented both from the technological and from the biocompatibility aspect as prerequisites of any perspectives for implantation. 3) Ultimately, experimental studies are presented showing the shaping of implants, the procedures of testing their biocompatibility and essential modifications to improve the interfaces between technical devices and the biological environment. The review ends by

  14. Cochlear implants: our experience and literature review

    PubMed Central

    Martins, Mariane Barreto Brandão; de Lima, Francis Vinicius Fontes; Santos, Ronaldo Carvalho; Santos, Arlete Cristina Granizo; Barreto, Valéria Maria Prado; de Jesus, Eduardo Passos Fiel

    2012-01-01

    Summary Introduction: Cochlear Implants are important for individuals with severe to profound bilateral sensorineural hearing loss. Objective: Evaluate the experience of cochlear implant center of Otorhinolaryngology through the analysis of records of 9 patients who underwent cochlear implant surgery. Methods: This is a retrospective study performed with the patients records. Number 0191.0.107.000-11 ethics committee approval. We evaluated gender, etiology, age at surgery, duration of deafness, classification of deafness, unilateral or bilateral surgery, intraoperative and postoperative neural response and impedance of the electrodes in intraoperative and preoperative tests and found those that counter-indicated surgery. Results: There were 6 pediatric and 3 adult patients. Four male and 5 female. Etiologies: maternal rubella, cytomegalovirus, ototoxicity, meningitis, and sudden deafness. The age at surgery and duration of deafness ranged from 2–46 years and 2–18 years, respectively. Seven patients were pre-lingual. All had profound bilateral PA. There were 7 bilateral implants. Intraoperative complications: hemorrhage. Complications after surgery: vertigo and internal device failure. In 7 patients the electrodes were implanted through. Telemetry showed satisfactory neural response and impedance. CT and MRI was performed in all patients. We found enlargement of the vestibular aqueduct in a patient and incudomalleolar malformation. Conclusion: The cochlear implant as a form of auditory rehabilitation is well established and spreading to different centers specialized in otoaudiology. Thus, the need for structured services and trained professionals in this type of procedure is clear. PMID:25991976

  15. MRI thermometry: Fast mapping of RF-induced heating along conductive wires.

    PubMed

    Ehses, Philipp; Fidler, Florian; Nordbeck, Peter; Pracht, Eberhard D; Warmuth, Marcus; Jakob, Peter M; Bauer, Wolfgang R

    2008-08-01

    Conductive implants are in most cases a strict contraindication for MRI examinations, as RF pulses applied during the MRI measurement can lead to severe heating of the surrounding tissue. Understanding and mapping of these heating effects is therefore crucial for determining the circumstances under which patient examinations are safe. The use of fluoroptic probes is the standard procedure for monitoring these heating effects. However, the observed temperature increase is highly dependent on the positioning of such a probe, as it can only determine the temperature locally. Temperature mapping with MRI after RF heating can be used, but cooling effects during imaging lead to a significant underestimation of the heating effect. In this work, an MRI thermometry method was combined with an MRI heating sequence, allowing for temperature mapping during RF heating. This technique may provide new opportunities for implant safety investigations. (c) 2008 Wiley-Liss, Inc.

  16. Dental implants in patients with bruxing habits.

    PubMed

    Lobbezoo, F; Brouwers, J E I G; Cune, M S; Naeije, M

    2006-02-01

    Bruxism (teeth grinding and clenching) is generally considered a contraindication for dental implants, although the evidence for this is usually based on clinical experience only. So far, studies to the possible cause-and-effect relationship between bruxism and implant failure do not yield consistent and specific outcomes. This is partly because of the large variation in the literature in terms of both the technical aspects and the biological aspects of the study material. Although there is still no proof for the suggestion that bruxism causes an overload of dental implants and of their suprastructures, a careful approach is recommended. There are a few practical guidelines as to minimize the chance of implant failure. Besides the recommendation to reduce or eliminate bruxism itself, these guidelines concern the number and dimensions of the implants, the design of the occlusion and articulation patterns, and the protection of the final result with a hard occlusal stabilization splint (night guard).

  17. Improved CMOS field isolation using Germaniun/Boron implantation

    SciTech Connect

    Pfiester, J.R.; Alvis, J.R. )

    1988-08-01

    A novel germanium/boron implantation technique for improving the electrical field isolation for high-density CMOS circuits is demonstrated. Germanium implantation causes a reduction in dopant diffusion and segregation during field oxidation and is shown to increase the p-well field threshold voltage by as much as 40 percent with no significant degradation to junction or device performance. Selective germanium implantation with a blanket boron field implant can also improve the electrical field isolation behavior for CMOS circuits.

  18. Clinical outcome following DIAM implantation for symptomatic lumbar internal disk disruption: a 3-year retrospective analysis

    PubMed Central

    Lu, Kang; Liliang, Po-Chou; Wang, Hao-Kuang; Chen, Jui-Sheng; Chen, Te-Yuan; Huang, Ruyi; Chen, Han-Jung

    2016-01-01

    Background/objective Internal disk disruption (IDD), an early event of lumbar disk degeneration, is the most common cause of low back pain. Since increased intradiskal pressure (IDP) is associated with symptoms and progression of disk degeneration, unloading a painful disk with an interspinous process device (IPD) is a rational treatment option. The goal of this study was to evaluate the effectiveness of dynamic stabilization with an IPD in the treatment of symptomatic IDD of the lumbar spine. Patients and methods Patients with symptomatic IDD were treated with implantation of an IPD, the device for intervertebral assisted motion (DIAM). Diagnosis of IDD was based on typical MRI finding of posterior annular high-intensity zone and positive provocative test on discography. IDP was analyzed intraoperatively. Axial back and leg pain was evaluated with visual analog scale, functional status with Oswestry Disability Index, and final clinical outcomes with Odom criteria. Data from 34 patients followed up for at least 3 years were collected. Results DIAM implantation significantly reduced IDP (n=11, P<0.0001). All 34 patients reported symptom relief. Thirty-one patients (91%) remained symptom free until the last followups. Three patients (9%) experienced recurrence of pain, of which the causes were unrelated to the IDD or surgery. Disk status at the DIAM-implanted segments remained stable. Segmental flexion/extension mobility was preserved in 27 of 30 patients with preoperative mobility. No proximal or distal adjacent segment degeneration was observed. The final clinical outcomes were excellent/good in 31 and fair/poor in three patients. Conclusion For patients with symptomatic IDD, dynamic stabilization with DIAM provides pain relief and functional improvement. The implantation maintains disk status and prevents progression of disk degeneration, without compromising segmental flexion/extension mobility or causing adjacent segment degeneration. PMID:27826214

  19. Bilayer Implants

    PubMed Central

    Schagemann, Jan C.; Rudert, Nicola; Taylor, Michelle E.; Sim, Sotcheadt; Quenneville, Eric; Garon, Martin; Klinger, Mathias; Buschmann, Michael D.; Mittelstaedt, Hagen

    2016-01-01

    Objective To compare the regenerative capacity of 2 distinct bilayer implants for the restoration of osteochondral defects in a preliminary sheep model. Methods Critical sized osteochondral defects were treated with a novel biomimetic poly-ε-caprolactone (PCL) implant (Treatment No. 2; n = 6) or a combination of Chondro-Gide and Orthoss (Treatment No. 1; n = 6). At 19 months postoperation, repair tissue (n = 5 each) was analyzed for histology and biochemistry. Electromechanical mappings (Arthro-BST) were performed ex vivo. Results Histological scores, electromechanical quantitative parameter values, dsDNA and sGAG contents measured at the repair sites were statistically lower than those obtained from the contralateral surfaces. Electromechanical mappings and higher dsDNA and sGAG/weight levels indicated better regeneration for Treatment No. 1. However, these differences were not significant. For both treatments, Arthro-BST revealed early signs of degeneration of the cartilage surrounding the repair site. The International Cartilage Repair Society II histological scores of the repair tissue were significantly higher for Treatment No. 1 (10.3 ± 0.38 SE) compared to Treatment No. 2 (8.7 ± 0.45 SE). The parameters cell morphology and vascularization scored highest whereas tidemark formation scored the lowest. Conclusion There was cell infiltration and regeneration of bone and cartilage. However, repair was incomplete and fibrocartilaginous. There were no significant differences in the quality of regeneration between the treatments except in some histological scoring categories. The results from Arthro-BST measurements were comparable to traditional invasive/destructive methods of measuring quality of cartilage repair. PMID:27688843

  20. Subdermal progestin implant contraception.

    PubMed

    Darney, P D

    1991-08-01

    Sustained-release progestin contraceptives are a new approach to meeting a worldwide need for more effective and acceptable birth control. These contraceptive systems provide low, stable levels of synthetic progestins for periods of months to several years. Unlike earlier injectable and oral contraceptives, they do not cause peaks in progestin levels beyond those required for effective contraception, nor do they employ estrogens. For these reasons, sustained-release progestin systems are without some of the health risks attributed to birth control pills, and they are more effective, as well as easy to use, and completely reversible. They share common side effects, the most frequent of which is irregular menstrual bleeding caused by the erratic shedding of hypotrophic endometrium. Despite this and other minor side effects, most users find the sustained-release systems acceptable alternatives to other methods of contraception. Permanent or biodegradable subdermal implants, injections, intrauterine and intracervical devices, and vaginal rings are all employed as delivery systems for contraceptive progestins. The Norplant (Wyeth Ayerst, Radnor, PA) system, consisting of six silastic tubes filled with levonorgestrel and implanted under the skin, was recently approved by the US Food and Drug Administration and is already used by more than a half million women worldwide. The other sustained-release systems are in various stages of development, at least several years away from general use. When these new methods complete clinical trials, women will be able to choose from among implants, injections, or pellets with various durations of action, all providing convenient, highly effective contraception with low risk to health.

  1. [Temporomandibular joint: MRI diagnostics].

    PubMed

    Kress, B; Schmitter, M

    2005-09-01

    MRI of the temporomandibular joint (TMJ) requires 1.5 T. The radiologist must be familiar with the anatomy and pathology of the TMJ. This review gives a description of MRI protocols for the TMJ, and MRI anatomy and pathology of the TMJ (open and closed mouth) by means of MR images and drawings. Diagnosing of the TMJ related diseases depends on standardized clinical and MR examinations. Therefore close interdisciplinary cooperation between dentist and radiologist is necessary.

  2. MRI brain imaging.

    PubMed

    Skinner, Sarah

    2013-11-01

    General practitioners (GPs) are expected to be allowed to request MRI scans for adults for selected clinically appropriate indications from November 2013 as part of the expansion of Medicare-funded MRI services announced by the Federal Government in 2011. This article aims to give a brief overview of MRI brain imaging relevant to GPs, which will facilitate explanation of scan findings and management planning with their patients. Basic imaging techniques, common findings and terminology are presented using some illustrative case examples.

  3. Radiographic evaluation of hip implants.

    PubMed

    Chang, Connie Y; Huang, Ambrose J; Palmer, William E

    2015-02-01

    Serial radiographs are the mainstay in the longitudinal assessment of hip implants. The prosthesis, periprosthetic bone, and juxta-articular soft tissues are inspected for fracture, periosteal reaction, stress shielding, calcar resorption, osteolysis, bony remodeling, metallic debris, and heterotopic ossification. Comparison radiographs best confirm implant migration, subsidence, and aseptic loosening. Infection, particle disease, reaction to metal, and mechanical impingement are important causes of postsurgical pain, but in their earliest stages they may be difficult to diagnose using radiographs. This article addresses the role of radiography following hip arthroplasty. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  4. Radiation induced currents in MRI RF coils: application to linac/MRI integration

    PubMed Central

    Burke, B; Fallone, B G; Rathee, S

    2010-01-01

    The integration of medical linear accelerators (linac) with magnetic resonance imaging (MRI) systems is advancing the current state of image-guided radiotherapy. The MRI in these integrated units will provide real-time, accurate tumor locations for radiotherapy treatment, thus decreasing geometric margins around tumors and reducing normal tissue damage. In the real-time operation of these integrated systems, the radiofrequency (RF) coils of MRI will be irradiated with radiation pulses from the linac. The effect of pulsed radiation on MRI radio frequency (RF) coils is not known and must be studied. The instantaneous radiation induced current (RIC) in two different MRI RF coils were measured and presented. The frequency spectra of the induced currents were calculated. Some basic characterization of the RIC was also done: isolation of the RF coil component responsible for RIC, dependence of RIC on dose rate, and effect of wax buildup placed on coil on RIC. Both the time and frequency characteristics of the RIC were seen to vary with the MRI RF coil used. The copper windings of the RF coils were isolated as the main source of RIC. A linear dependence on dose rate was seen. The RIC was decreased with wax buildup, suggesting an electronic disequilibrium as the cause of RIC. This study shows a measurable RIC present in MRI RF coils. This unwanted current could be possibly detrimental to the signal to noise ratio in MRI and produce image artifacts. PMID:20071754

  5. Influence of dental materials on dental MRI

    PubMed Central

    Tymofiyeva, O; Vaegler, S; Rottner, K; Boldt, J; Hopfgartner, AJ; Proff, PC; Richter, E-J; Jakob, PM

    2013-01-01

    Objectives: To investigate the potential influence of standard dental materials on dental MRI (dMRI) by estimating the magnetic susceptibility with the help of the MRI-based geometric distortion method and to classify the materials from the standpoint of dMRI. Methods: A series of standard dental materials was studied on a 1.5 T MRI system using spin echo and gradient echo pulse sequences and their magnetic susceptibility was estimated using the geometric method. Measurements on samples of dental materials were supported by in vivo examples obtained in dedicated dMRI procedures. Results: The tested materials showed a range of distortion degrees. The following materials were classified as fully compatible materials that can be present even in the tooth of interest: the resin-based sealer AH Plus® (Dentsply, Maillefer, Germany), glass ionomer cement, gutta-percha, zirconium dioxide and composites from one of the tested manufacturers. Interestingly, composites provided by the other manufacturer caused relatively strong distortions and were therefore classified as compatible I, along with amalgam, gold alloy, gold–ceramic crowns, titanium alloy and NiTi orthodontic wires. Materials, the magnetic susceptibility of which differed from that of water by more than 200 ppm, were classified as non-compatible materials that should not be present in the patient’s mouth for any dMRI applications. They included stainless steel orthodontic appliances and CoCr. Conclusions: A classification of the materials that complies with the standard grouping of materials according to their magnetic susceptibility was proposed and adopted for the purposes of dMRI. The proposed classification can serve as a guideline in future dMRI research. PMID:23610088

  6. [Bilateral cochlear implantation].

    PubMed

    Kronenberg, Jona; Migirov, Lela; Taitelbaum-Swead, Rikey; Hildesheimer, Minka

    2010-06-01

    Cochlear implant surgery became the standard of care in hearing rehabilitation of patients with severe to profound sensorineural hearing loss. This procedure may alter the lives of children and adults enabling them to integrate with the hearing population. In the past, implantation was performed only in one ear, despite the fact that binaural hearing is superior to unilateral, especially in noisy conditions. Cochlear implantation may be performed sequentially or simultaneously. The "sensitive period" of time between hearing loss and implantation and between the two implantations, when performed sequentially, significantly influences the results. Shorter time spans between implantations improve the hearing results after implantation. Hearing success after implantation is highly dependent on the rehabilitation process which includes mapping, implant adjustments and hearing training. Bilateral cochlear implantation in children is recommended as the proposed procedure in spite of the additional financial burden.

  7. Magnetic resonance imaging safety in pacemaker and implantable cardioverter defibrillator patients: how far have we come?

    PubMed Central

    Nordbeck, Peter; Ertl, Georg; Ritter, Oliver

    2015-01-01

    Magnetic resonance imaging (MRI) has long been regarded a general contraindication in patients with cardiovascular implanted electronic devices such as cardiac pacemakers or cardioverter defibrillators (ICDs) due to the risk of severe complications and even deaths caused by interactions of the magnetic resonance (MR) surrounding and the electric devices. Over the last decade, a better understanding of the underlying mechanisms responsible for such potentially life-threatening complications as well as technical advances have allowed an increasing number of pacemaker and ICD patients to safely undergo MRI. This review lists the key findings from basic research and clinical trials over the last 20 years, and discusses the impact on current day clinical practice. With ‘MR-conditional’ devices being the new standard of care, MRI in pacemaker and ICD patients has been adopted to clinical routine today. However, specific precautions and specifications of these devices should be carefully followed if possible, to avoid patient risks which might appear with new MR technology and further increasing indications and patient numbers. PMID:25796053

  8. [Cost Analysis of Cochlear Implantation in Adults].

    PubMed

    Raths, S; Lenarz, T; Lesinski-Schiedat, A; Flessa, S

    2016-04-01

    The number of implantation of cochlear implants has steadily risen in recent years. Reasons for this are an extension of indication criteria, demographic change, increased quality of life needs and greater acceptance. The consequences are rising expenditure for statutory health insurance (SHI) for cochlear implantation. A detailed calculation of lifetime costs from SHI's perspective for postlingually deafened adolescents and adults is essential in estimating future cost developments. Calculations are based on accounting data from the Hannover Medical School. With regard to further life expectancy, average costs of preoperative diagnosis, surgery, rehabilitation, follow-ups, processor upgrades and electrical maintenance were discounted to their present value at age of implantation. There is an inverse relation between cost of unilateral cochlear implantation and age of initial implantation. From SHI's perspective, the intervention costs between 36,001 and 68,970 € ($ 42,504-$ 81,429). The largest cost components are initial implantation and processor upgrades. Compared to the UK the cost of cochlear implantation in Germany seems to be significantly lower. In particular the costs of, rehabilitation and maintenance in Germany cause only a small percentage of total costs. Also, the costs during the first year of treatment seem comparatively low. With regard to future spending of SHI due to implant innovations and associated extension of indication, increasing cost may be suspected. © Georg Thieme Verlag KG Stuttgart · New York.

  9. [Comperative study of implant surface characteristics].

    PubMed

    Katona, Bernadett; Daróczi, Lajos; Jenei, Attila; Bakó, József; Hegedus, Csaba

    2013-12-01

    The osseointegration between the implant and its' bone environment is very important. The implants shall meet the following requirements: biocompatibility, rigidity, resistance against corrosion and technical producibility. In our present study surface morphology and material characteristics of different implants (Denti Bone Level, Denti Zirconium C, Bionika CorticaL, Straumann SLA, Straumann SLA Active, Dentsply Ankylos and Biotech Kontact implant) were investigated with scanning electron microscopy and energy-dispersive X-ray spectroscopy. The possible surface alterations caused by the manufacturing technology were also investigated. During grit-blasting the implants' surface is blasted with hard ceramic particles (titanium oxide, alumina, calcium phosphate). Properties of blasting material are critical because the osseointegration of dental implants should not be hampered. The physical and chemical features of blasting particles could importantly affect the produced surfaces of implants. Titanium surfaces with micro pits are created after immersion in mixtures of strong acids. On surfaces after dual acid-etching procedures the crosslinking between fibrin and osteogenetic cells could be enhanced therefore bone formation could be directly facilitated on the surface of the implant. Nowadays there are a number of surface modification techniques available. These can be used as a single method or in combination with each other. The effect of the two most commonly used surface modifications (acid-etching and grit-blasting) on different implants are demonstrated in our investigation.

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

    PubMed

    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.

  11. MRI of the Musculoskeletal System

    MedlinePlus

    ... does not completely surround you. Some newer MRI machines have a larger diameter bore which can be ... size patients or patients with claustrophobia. Other MRI machines are open on the sides (open MRI). Open ...

  12. Magnetic Resonance Imaging (MRI) - Spine

    MedlinePlus

    ... does not completely surround you. Some newer MRI machines have a larger diameter bore which can be ... size patients or patients with claustrophobia. Other MRI machines are open on the sides (open MRI). Open ...

  13. Multisite Infection with Mycobacterium abscessus after Replacement of Breast Implants and Gluteal Lipofilling

    PubMed Central

    Rüegg, Eva; Cheretakis, Alexandre; Modarressi, Ali; Harbarth, Stephan; Pittet-Cuénod, Brigitte

    2015-01-01

    Introduction. Medical tourism for aesthetic surgery is popular. Nontuberculous mycobacteria (NTM) occasionally cause surgical-site infections. As NTM grow in biofilms, implantations of foreign bodies are at risk. Due to late manifestation, infections occur when patients are back home, where they must be managed properly. Case Report. A 39-year-old healthy female was referred for acute infection of the right gluteal area. Five months before, she had breast implants replacement, abdominal liposuction, and gluteal lipofilling in Mexico. Three months postoperatively, implants were removed for NTM-infection in Switzerland. Adequate antibiotic treatment was stopped after seven days for drug-related hepatitis. At entrance, gluteal puncture for bacterial analysis was performed. MRI showed large subcutaneous collection. Debridement under general anaesthesia was followed by open wound management. Total antibiotic treatment was 20 weeks. Methods. Bacterial analysis of periprosthetic and gluteal liquids included Gram-stain plus acid-fast stain, and aerobic, anaerobic and mycobacterial cultures.  Results. In periprosthetic fluid, Mycobacterium abscessus, Propionibacterium, and Staphylococcus epidermidis were identified. The same M. abscessus strain was found gluteally. The gluteal wound healed within six weeks. At ten months' follow-up, gluteal asymmetry persists for deep scarring. Conclusion. This case presents major complications of multisite aesthetic surgery. Surgical-site infections in context of medical tourism need appropriate bacteriological investigations, considering potential NTM-infections. PMID:25893122

  14. Rat model of cholelithiasis with human gallstones implanted in cholestasis-induced virtual gallbladder

    PubMed Central

    Cona, Marlein Miranda; Liu, Yewei; Yin, Ting; Feng, Yuanbo; Chen, Feng; Mulier, Stefaan; Li, Yue; Zhang, Jian; Oyen, Raymond; Ni, Yicheng

    2016-01-01

    AIM: To facilitate translational research on cholelithiasis, we have developed a rat model of human gallstones by exploiting the unique biliopancreatic features of this species. METHODS: Under anesthesia, 16 adult rats of equal genders underwent two times of abdominal surgery. First, their common bile duct (CBD) was ligated to cause cholestasis by total biliary obstruction (TBO). On day 0, 1, 3, 7, 14, 21 and 28 after TBO, magnetic resonance imaging (MRI) was conducted to monitor the dilatation of the CBD, and blood was sampled to analyze total serum bilirubin (TSB). Secondly, on day 30, the abdomen was re-opened and gallstone(s) collected from human patients were implanted in the dilated CBD as a virtual gallbladder (VGB), which was closed by suture ligation. This rat cholelithiasis model was examined by MRI, clinical observation, microcholangiography and histology. RESULTS: All rats survived two laparotomies. After ligation, the CBD was dilated to a stable size of 4 to 30 mm in diameter on day 21-28, which became a VGB. The rats initially showed signs of jaundice that diminished over time, which paralleled with the evolving TSB levels from 0.6 ± 0.3 mg/dL before ligation, through a peak of 10.9 ± 1.9 mg/dL on day 14, until a nearly normalized value after day 28. The dilated CBD with thickened wall allowed an incision for implantation of human gallstones of 1-10 mm in diameter. The rat cholelithiasis was proven by in vivo MRI and postmortem microcholangiography and histomorphology. CONCLUSION: A rat model cholelithiasis with human gallstones has been established, which proves feasible, safe, reliable, nontoxic and cost-effective. Given the gallstones of human origin, applications of this model may be of help in translational research such as optical detection and lysis of gallstones by systemic drug administration. PMID:27376020

  15. Rat model of cholelithiasis with human gallstones implanted in cholestasis-induced virtual gallbladder.

    PubMed

    Cona, Marlein Miranda; Liu, Yewei; Yin, Ting; Feng, Yuanbo; Chen, Feng; Mulier, Stefaan; Li, Yue; Zhang, Jian; Oyen, Raymond; Ni, Yicheng

    2016-06-26

    To facilitate translational research on cholelithiasis, we have developed a rat model of human gallstones by exploiting the unique biliopancreatic features of this species. Under anesthesia, 16 adult rats of equal genders underwent two times of abdominal surgery. First, their common bile duct (CBD) was ligated to cause cholestasis by total biliary obstruction (TBO). On day 0, 1, 3, 7, 14, 21 and 28 after TBO, magnetic resonance imaging (MRI) was conducted to monitor the dilatation of the CBD, and blood was sampled to analyze total serum bilirubin (TSB). Secondly, on day 30, the abdomen was re-opened and gallstone(s) collected from human patients were implanted in the dilated CBD as a virtual gallbladder (VGB), which was closed by suture ligation. This rat cholelithiasis model was examined by MRI, clinical observation, microcholangiography and histology. All rats survived two laparotomies. After ligation, the CBD was dilated to a stable size of 4 to 30 mm in diameter on day 21-28, which became a VGB. The rats initially showed signs of jaundice that diminished over time, which paralleled with the evolving TSB levels from 0.6 ± 0.3 mg/dL before ligation, through a peak of 10.9 ± 1.9 mg/dL on day 14, until a nearly normalized value after day 28. The dilated CBD with thickened wall allowed an incision for implantation of human gallstones of 1-10 mm in diameter. The rat cholelithiasis was proven by in vivo MRI and postmortem microcholangiography and histomorphology. A rat model cholelithiasis with human gallstones has been established, which proves feasible, safe, reliable, nontoxic and cost-effective. Given the gallstones of human origin, applications of this model may be of help in translational research such as optical detection and lysis of gallstones by systemic drug administration.

  16. On the heating of inductively coupled resonators (stents) during MRI examinations.

    PubMed

    Busch, Martin; Vollmann, Wolfgang; Bertsch, Thomas; Wetzler, Rainer; Bornstedt, Axel; Schnackenburg, Bernhard; Schnorr, Jörg; Kivelitz, Dietmar; Taupitz, Matthias; Grönemeyer, Dietrich

    2005-10-01

    Stents that have been implanted to preserve the results of vascular dilatation are frequently affected by in-stent restenosis, which ideally should be followed up by a noninvasive diagnostic modality. Active MRI stents can enable this kind of follow-up, while normal metallic stents can not. The prototype stents investigated in this study were designed as electric resonating circuits without a direct connection to the MR imager, and function as inductively coupled transmit coils. The model of a long solenoid coil is used to describe the additional power loss caused by such resonators. The theoretically estimated temperature increase is verified by measurements for different resonators and discussed for worst-case conditions. The RF power absorption of an active resonator is negligible compared to the total power absorbed during MRI. The local temperature increase observed for prototypes embedded in phantoms is in a range that excludes direct tissue damage. However, ruptures in the conducting structure of a resonator can cause hot spots, which may establish a high local temperature. This hazard can be reduced by designing resonators with a low quality (Q) factor or by setting the circuit slightly off resonance; however, this would lower the nominal amplification for which the resonator was designed.

  17. Fetal tracheolaryngeal airway obstruction: prenatal evaluation by sonography and MRI

    PubMed Central

    Courtier, Jesse; Poder, Liina; Wang, Zhen J.; Westphalen, Antonio C.; Yeh, Benjamin M.

    2010-01-01

    We reviewed the sonographic and MRI findings of tracheolaryngeal obstruction in the fetus. Conditions that can cause tracheolaryngeal obstruction include extrinsic causes such as lymphatic malformation, cervical teratoma and vascular rings and intrinsic causes such as congenital high airway obstruction syndrome (CHAOS). Accurate distinction of these conditions by sonography or MRI can help facilitate parental counseling and management, including the decision to utilize the ex utero intrapartum treatment (EXIT) procedure. PMID:20737145

  18. MRI Scans - Multiple Languages

    MedlinePlus

    ... español) Ukrainian (українська ) Arabic (العربية) Expand Section MRI (Magnetic Resonance Imaging) - العربية (Arabic) Bilingual PDF Health Information Translations Chinese, Simplified (Mandarin dialect) (简体中文) Expand Section MRI ( ...

  19. Assessment of magnetic field interactions and radiofrequency-radiation-induced heating of metallic spinal implants in 7 T field.

    PubMed

    Tsukimura, Itsuko; Murakami, Hideki; Sasaki, Makoto; Endo, Hirooki; Yamabe, Daisuke; Oikawa, Ryosuke; Doita, Minoru

    2017-08-01

    The safety of metallic spinal implants in magnetic resonance imaging (MRI) performed using ultrahigh fields has not been established. Hence, we examined whether the displacement forces caused by a static magnetic field and the heating induced by radiofrequency radiation are substantial for spinal implants in a 7 T field. We investigated spinal rods of various lengths and materials, a screw, and a cross-linking bridge in accordance with the American Society for Testing and Materials guidelines. The displacement forces of the metallic implants in static 7 T and 3 T static magnetic fields were measured and compared. The temperature changes of the implants during 15-min-long fast spin-echo and balanced gradient-echo image acquisition sequences were measured in the 7 T field. The deflection angles of the metallic spinal materials in the 7 T field were 5.0-21.0° [median: 6.7°], significantly larger than those in the 3 T field (1.0-6.3° [2.2°]). Among the metallic rods, the cobalt-chrome rods had significantly larger deflection angles (17.8-21.0° [19.8°]) than the pure titanium and titanium alloy rods (5.0-7.7° [6.2°]). The temperature changes of the implants, including the cross-linked rods, were 0.7-1.0°C [0.8°C] and 0.6-1.0°C [0.7°C] during the fast spin-echo and balanced gradient-echo sequences, respectively; these changes were slightly larger than those of the controls (0.4-1.1°C [0.5°C] and 0.3-0.9°C [0.6°C], respectively). All of the metallic spinal implants exhibited small displacement forces and minimal heating, indicating that MRI examinations using 7 T fields may be performed safely on patients with these implants. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1831-1837, 2017. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society.

  20. Implant failure associated with actinomycosis in a medically compromised patient.

    PubMed

    Sun, Chun-Xiao; Henkin, Jeffrey M; Ririe, Craig; Javadi, Elham

    2013-04-01

    Oral actinomycosis is not a common disease, but it can cause massive destruction. This article reports a case of implant failure associated with actinomycosis. A 55-year-old Caucasian male patient had tooth #20 extracted years ago and an implant placed 3 years ago. The #20 implant area developed an abscess about 1½ years after implant placement. Radiographic findings revealed a large radiolucency on the mesial aspect of the #20 implant. The implant was surgically removed and the lesion thoroughly debrided. The patient experienced severe pain when the apical soft tissue was curreted following implant removal. A periapical radiograph revealed that the lesion approached the mental foramen. A short course of antibiotics was prescribed. Histological observation found sulfur granules, which were found to be actinomycotic colonies. Peri-implant actinomycosis was diagnosed. No recurrence had occurred at the 1-year follow-up.

  1. Learning distance function for regression-based 4D pulmonary trunk model reconstruction estimated from sparse MRI data

    NASA Astrophysics Data System (ADS)

    Vitanovski, Dime; Tsymbal, Alexey; Ionasec, Razvan; Georgescu, Bogdan; Zhou, Shaohua K.; Hornegger, Joachim; Comaniciu, Dorin

    2011-03-01

    Congenital heart defect (CHD) is the most common birth defect and a frequent cause of death for children. Tetralogy of Fallot (ToF) is the most often occurring CHD which affects in particular the pulmonary valve and trunk. Emerging interventional methods enable percutaneous pulmonary valve implantation, which constitute an alternative to open heart surgery. While minimal invasive methods become common practice, imaging and non-invasive assessment tools become crucial components in the clinical setting. Cardiac computed tomography (CT) and cardiac magnetic resonance imaging (cMRI) are techniques with complementary properties and ability to acquire multiple non-invasive and accurate scans required for advance evaluation and therapy planning. In contrary to CT which covers the full 4D information over the cardiac cycle, cMRI often acquires partial information, for example only one 3D scan of the whole heart in the end-diastolic phase and two 2D planes (long and short axes) over the whole cardiac cycle. The data acquired in this way is called sparse cMRI. In this paper, we propose a regression-based approach for the reconstruction of the full 4D pulmonary trunk model from sparse MRI. The reconstruction approach is based on learning a distance function between the sparse MRI which needs to be completed and the 4D CT data with the full information used as the training set. The distance is based on the intrinsic Random Forest similarity which is learnt for the corresponding regression problem of predicting coordinates of unseen mesh points. Extensive experiments performed on 80 cardiac CT and MR sequences demonstrated the average speed of 10 seconds and accuracy of 0.1053mm mean absolute error for the proposed approach. Using the case retrieval workflow and local nearest neighbour regression with the learnt distance function appears to be competitive with respect to "black box" regression with immediate prediction of coordinates, while providing transparency to the

  2. Can MRI accurately detect pilon articular malreduction? A quantitative comparison between CT and 3T MRI bone models

    PubMed Central

    Radzi, Shairah; Dlaska, Constantin Edmond; Cowin, Gary; Robinson, Mark; Pratap, Jit; Schuetz, Michael Andreas; Mishra, Sanjay

    2016-01-01

    Background Pilon fracture reduction is a challenging surgery. Radiographs are commonly used to assess the quality of reduction, but are limited in revealing the remaining bone incongruities. The study aimed to develop a method in quantifying articular malreductions using 3D computed tomography (CT) and magnetic resonance imaging (MRI) models. Methods CT and MRI data were acquired using three pairs of human cadaveric ankle specimens. Common tibial pilon fractures were simulated by performing osteotomies to the ankle specimens. Five of the created fractures [three AO type-B (43-B1), and two AO type-C (43-C1) fractures] were then reduced and stabilised using titanium implants, then rescanned. All datasets were reconstructed into CT and MRI models, and were analysed in regards to intra-articular steps and gaps, surface deviations, malrotations and maltranslations of the bone fragments. Results Initial results reveal that type B fracture CT and MRI models differed by ~0.2 (step), ~0.18 (surface deviations), ~0.56° (rotation) and ~0.4 mm (translation). Type C fracture MRI models showed metal artefacts extending to the articular surface, thus unsuitable for analysis. Type C fracture CT models differed from their CT and MRI contralateral models by ~0.15 (surface deviation), ~1.63° (rotation) and ~0.4 mm (translation). Conclusions Type B fracture MRI models were comparable to CT and may potentially be used for the postoperative assessment of articular reduction on a case-to-case basis. PMID:28090442

  3. Norplant implants.

    PubMed

    Henley, E

    1993-06-01

    This letter to the editor is in response to 3 articles on the use of the Norplant implant contraceptive in The Indian Health Service (IHS) Provider. Norplant and the FDA-approved Depo-Provera now expand contraceptive options for women. All IHS and 638 sites might be able to offer both options. Several of the authors expressed concern regarding decreased Norplant effectiveness in heavier patients. Norplant is still more effective than any other currently available reversible contraceptive in the US at all weights. Many experts feel the current silastic capsule provides adequate hormone levels even in heavier women. The Crow Service Unit has initiated their Norplant program, although the Wyeth consent form seems unnecessarily extensive. The Albuquerque Service Unit consent form simply describes the procedure and confirms that patients have read and understand the fact sheet. The theoretical risk of thromboembolism is vastly outweighed by the potential benefit of reliable contraception in high risk alcoholic women, except perhaps in women with severe liver disease. While Norplant is expensive, programs need to consider the actual cost of a pregnancy, potential complications, and the financial and social costs of unintended pregnancy. For those in difficult straits, the manufacturer has set up a foundation for obtaining Norplant free of charge. Depo-Provera comes in a 150 mg dose vial that is given every 3 months. The mean time to ovulation is 4.5 months from the last dose. The adverse reaction spectrum is similar to Norplant as they are both progesterone-related agents. Providers and clinics should reduce barriers to family planning by giving out more pill packs at a time; letting adolescents who wish to delay their first pelvic exam have 3 months of pills without an exam; making condoms available in exam rooms rather than through pharmacy prescriptions; and increasing patient accessibility to the morning-after pill.

  4. Factors associated with early and late failure of dental implants.

    PubMed

    Sakka, Salah; Baroudi, Kusai; Nassani, Mohammad Zakaria

    2012-11-01

    Osseointegration is a good indication of the clinical success of titanium implants referring to the direct anchorage of such implants to the surrounding host bone. Despite the high success rate of endosseous dental implants, they do fail. A lack of primary stability, surgical trauma, and infection seem to be the most important causes of early implant failure. Early signs of infection may be an indication of a much more critical result than if the same complications occur later, because of disturbance of the primary bone healing process. Occlusal overload and periimplantitis seem to be the most important factors associated with late failure. Suboptimal implant design and improper prosthetic constructions are among those risk factors responsible for implant complications and failure. This concise review highlights the main causes associated with early and late implant failure, as thorough knowledge of this unavoidable clinical fact is essential in the field of oral implantology. © 2012 Wiley Publishing Asia Pty Ltd.

  5. Cd ion implantation in AlN

    NASA Astrophysics Data System (ADS)

    Miranda, S. M. C.; Franco, N.; Alves, E.; Lorenz, K.

    2012-10-01

    AlN thin films were implanted with cadmium, to fluences of 1 × 1013 and 8 × 1014 at/cm2. The implanted samples were annealed at 950 °C under flowing nitrogen. Although implantation damage in AlN is known to be extremely stable the crystal could be fully recovered at low fluences. At high fluences the implantation damage was only partially removed. Implantation defects cause an expansion of the c-lattice parameter. For the high fluence sample the lattice site location of the ions was studied by Rutherford Backscattering/Channelling Spectrometry. Cd ions are found to be incorporated in substitutional Al sites in the crystal and no significant diffusion is seen upon thermal annealing. The observed high solubility limit and site stability are prerequisite for using Cd as p-type dopant in AlN.

  6. Emerging MRI methods in rheumatoid arthritis.

    PubMed

    Borrero, Camilo G; Mountz, James M; Mountz, John D

    2011-02-01

    New MRI techniques have been developed to assess not only the static anatomy of synovial hyperplasia, bone changes and cartilage degradation in patients with rheumatoid arthritis (RA), but also the activity of the physiological events that cause these changes. This enables an estimation of the rate of change in the synovium, bone and cartilage as a result of disease activity or in response to therapy. Typical MRI signs of RA in the pre-erosive phase include synovitis, bone marrow edema and subchondral cyst formation. Synovitis can be assessed by T2-weighted imaging, dynamic contrast-enhanced MRI or diffusion tensor imaging. Bone marrow edema can be detected on fluid-sensitive sequences such as short-tau inversion recovery or T2-weighted fast-spin echo sequences. Detection of small bone erosions in the early erosive phase using T1-weighted MRI has sensitivity comparable to CT. Numerous MRI techniques have been developed for quantitative assessment of potentially pathologic changes in cartilage composition that occur before frank morphologic changes. In this Review, we summarize the advances and new directions in the field of MRI, with an emphasis on their current state of development and application in RA.

  7. MRI-Safe Robot for Endorectal Prostate Biopsy

    PubMed Central

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

    2014-01-01

    This paper reports the development of an MRI-Safe robot for direct (interventional) MRI-guided endorectal prostate biopsy. The robot is constructed of nonmagnetic and electrically nonconductive materials, and is electricity free, using pneumatic actuation and optical sensors. Targeting biopsy lesions of MRI abnormality presents substantial clinical potential for the management of prostate cancer. The paper describes MRI-Safe requirements, presents the kinematic architecture, design and construction of the robot, and a comprehensive set of preclinical tests for MRI compatibility and needle targeting accuracy. The robot has a compact and simple 3 degree-of-freedom (DoF) structure, two for orienting a needle-guide and one to preset the depth of needle insertion. The actual insertion is performed manually through the guide and up to the preset depth. To reduce the complexity and size of the robot next to the patient, the depth setting DoF is remote. Experimental results show that the robot is safe to use in any MRI environment (MRI-Safe). Comprehensive MRI tests show that the presence and motion of the robot in the MRI scanner cause virtually no image deterioration or signal to noise ratio (SNR) change. Robot’s accuracy in bench test, CT-guided in-vitro, MRI-guided in-vitro and animal tests are 0.37mm, 1.10mm, 2.09mm, and 2.58mm respectively. These values are acceptable for clinical use. PMID:25378897

  8. The effect of bruxism on treatment planning for dental implants.

    PubMed

    Misch, Carl E

    2002-09-01

    Bruxism is a potential risk factor for implant failure. Excessive force is the primary cause of late implant complications. An appreciation of the etiology of crestal bone loss, failure of implants, failure to retain implant restorations, and fracture of components will lead the practitioner to develop a treatment plan that reduces force on implants and their restorations. The forces are considered in terms of magnitude, duration, direction, type, and magnification. Once the dentist has identified the source(s) of additional force on the implant system, the treatment plan is altered to contend with and reduce the negative sequelae on the bone, implant, and final restoration. One viable approach is to increase the implant-bone surface area. Additional implants can be placed to decrease stress on any one implant, and implants in molar regions should have an increased width. Use of more and wider implants decreases the strain on the prosthesis and also dissipates stress to the bone, especially at the crest. The additional implants should be positioned with intent to eliminate cantilevers when possible. Greater surface area implant designs made of titanium alloy and with an external hex design can also prove advantageous. Anterior guidance in mandibular excursions further decreases force and eliminates or reduces lateral posterior force. Metal occlusal surfaces decrease the risk of porcelain fracture and do not require as much abutment reduction, which in turn enhances prosthesis retention. The retention of the final prosthesis or super-structure is also improved with additional implant abutments. Night guards designed with specific features also are a benefit to initially diagnose the influence of occlusal factors for the patient, and as importantly, to reduce the influence of extraneous stress on implants and implant-retained restorations.

  9. Clinical safety of brain magnetic resonance imaging with implanted deep brain stimulation hardware: large case series and review of the literature.

    PubMed

    Zrinzo, Ludvic; Yoshida, Fumiaki; Hariz, Marwan I; Thornton, John; Foltynie, Thomas; Yousry, Tarek A; Limousin, Patricia

    2011-01-01

    Over 75,000 patients have undergone deep brain stimulation (DBS) procedures worldwide. Magnetic resonance imaging (MRI) is an important clinical and research tool in analyzing electrode location, documenting postoperative complications, and investigating novel symptoms in DBS patients. Functional MRI may shed light on the mechanism of action of DBS. MRI safety in DBS patients is therefore an important consideration. We report our experience with MRI in patients with implanted DBS hardware and examine the literature for clinical reports on MRI safety with implanted DBS hardware. A total of 262 MRI examinations were performed in 223 patients with intracranial DBS hardware, including 45 in patients with an implanted pulse generator. Only 1 temporary adverse event occurred related to patient agitation and movement during immediate postoperative MR imaging. Agitation resolved after a few hours, and an MRI obtained before implanted pulse generator implantation revealed edema around both electrodes. Over 4000 MRI examinations in patients with implanted DBS hardware have been reported in the literature. Only 4 led to adverse events, including 2 hardware failures, 1 temporary and 1 permanent neurological deficit. Adverse neurological events occurred in a unique set of circumstances where appropriate safety protocols were not followed. MRI guidelines provided by DBS hardware manufacturers are inconsistent and vary among devices. The importance of MRI in modern medicine places pressure on industry to develop fully MRI-compatible DBS devices. Until then, the literature suggests that, when observing certain precautions, cranial MR images can be obtained with an extremely low risk in patients with implanted DBS hardware. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Immediate bleeding complications in dental implants: A systematic review

    PubMed Central

    Balaguer-Martí, José-Carlos; Peñarrocha-Oltra, David; Balaguer-Martínez, José

    2015-01-01

    Objective: A review is made of the immediate or immediate postoperative bleeding complications in dental implants, with a view to identifying the areas of greatest bleeding risk, the causes of bleeding, the length of the implants associated with bleeding, the most frequently implicated blood vessels, and the treatments used to resolve these complications. Material and Methods: A Medline (PubMed) and Embase search was made of articles on immediate bleeding complications in dental implants published in English up until May 2014. Inclusion criteria: studies in humans subjects with severe bleeding immediately secondary to implant placement, which reported the time until the hemorrhage, the implant lenght, the possible cause of bleeding and the treatment. Exclusion criteria: patients receiving anticoagulation treatment. Results: Fifteen articles met the inclusion criteria. The area with the largest number of bleeding complications corresponded to the mandibular canine. The cause of bleeding was lingual cortical bone perforation during implant placement, with damage to the sublingual artery. The implants associated with bleeding were those measuring 15 mm in length or more. Management focused on securing the airway (with intubation or tracheostomy if necessary), with bleeding control. Conclusions: It’s important to pay special attention when the implants are placed in the mandibular anterior zone, especially if long implants are used. The most frequently cause of bleeding was the perforation of the lingual plate. Treatment involves securing the airway, with bleeding control. Key words:Hemorrhage, complications, immediate, bleeding, dental implants. PMID:25475779

  11. [Biomaterials in cochlear implants].

    PubMed

    Stöver, T; Lenarz, T

    2009-05-01

    Cochlear implants (CI) represent the "gold standard" for the treatment of congenitally deaf children and postlingually deafened adults. Thus, cochlear implantation is a success story of new bionic prosthesis development. Owing to routine application of cochlear implants in adults but also in very young children (below the age of one), high demands are placed on the implants. This is especially true for biocompatibility aspects of surface materials of implant parts which are in contact with the human body. In addition, there are various mechanical requirements which certain components of the implants must fulfil, such as flexibility of the electrode array and mechanical resistance of the implant housing. Due to the close contact of the implant to the middle ear mucosa and because the electrode array is positioned in the perilymphatic space via cochleostomy, there is a potential risk of bacterial transferral along the electrode array into the cochlea. Various requirements that have to be fulfilled by cochlear implants, such as biocompatibility, electrode micromechanics, and although a very high level of technical standards has been carried out there is still demand for the improvement of implants as well as of the materials used for manufacturing, ultimately leading to increased implant performance. General considerations of material aspects related to cochlear implants as well as potential future perspectives of implant development will be discussed.

  12. Light and scanning electron microscopic report of four fractured implants.

    PubMed

    Piattelli, A; Piattelli, M; Scarano, A; Montesani, L

    1998-01-01

    Although they are fortunately rare, implant fractures can cause significant problems for both clinicians and patients. The authors present a light and scanning electron microscopic study of four fractured implants in two patients. Both patients had parafunctional habits (bruxism), hypertrophic masticatory muscles, and wear of occlusal surfaces. The scanning electron microscopic study of the fractured surfaces of all four implants showed the presence of fatigue striations. Bending overload was probably created by a combination of parafunctional forces, bone resorption, posterior location of the implants, and implant diameter.

  13. The Hamster as a Model for Embryo Implantation

    PubMed Central

    Reese, Jeff; Wang, Hehai; Ding, Tianbing; Paria, B. C.

    2008-01-01

    Defects in preimplantation embryonic development, uterine receptivity, and implantation are the leading cause of infertility, pregnancy problems and birth defects. Significant progress has been made in our basic understanding of these processes using the mouse model, where implantation is ovarian estrogen-dependent in the presence of progesterone. However, an animal model where implantation is progesterone-dependent must also be studied to gain a full understanding of the embryo and uterine events that are required for implantation. In this regard, the hamster is a useful model and this review summarizes the information currently available regarding mechanisms involved in synchronous preimplantation embryo and uterine development for implantation in this species. PMID:18178492

  14. MRI manifestations of bowler's thumb.

    PubMed

    Showalter, Martha F; Flemming, Donald J; Bernard, Stephanie A

    2011-01-01

    Bowler's thumb is a rare perineural fibrosis involving the ulnar digital nerve of the thumb. Affected patients present with pain, neuropathy, and mass lesion. The condition is caused by chronic repetitive impaction of the ulnar soft tissues of the thumb against the thumbhole of a bowling ball. In our case, MRI showed decreased signal intensity on both T1- and T2-weighted images surrounding an enlarged ulnar digital nerve of the thumb. The findings can be confused with giant-cell tumor of the tendon sheath or peripheral-nerve-sheath tumor.

  15. Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art

    PubMed Central

    Stradiotti, P.; Curti, A.; Castellazzi, G.

    2009-01-01

    The projectional nature of radiogram limits its amount of information about the instrumented spine. MRI and CT imaging can be more helpful, using cross-sectional view. However, the presence of metal-related artifacts at both conventional CT and MRI imaging can obscure relevant anatomy and disease. We reviewed the literature about overcoming artifacts from metallic orthopaedic implants at high-field strength MRI imaging and multi-detector CT. The evolution of multichannel CT has made available new techniques that can help minimizing the severe beam-hardening artifacts. The presence of artifacts at CT from metal hardware is related to image reconstruction algorithm (filter), tube current (in mA), X-ray kilovolt peak, pitch, hardware composition, geometry (shape), and location. MRI imaging has been used safely in patients with orthopaedic metallic implants because most of these implants do not have ferromagnetic properties and have been fixed into position. However, on MRI imaging metallic implants may produce geometric distortion, the so-called susceptibility artifact. In conclusion, although 140 kV and high milliamperage second exposures are recommended for imaging patients with hardware, caution should always be exercised, particularly in children, young adults, and patients undergoing multiple examinations. MRI artifacts can be minimized by positioning optimally and correctly the examined anatomy part with metallic implants in the magnet and by choosing fast spin-echo sequences, and in some cases also STIR sequences, with an anterior to posterior frequency-encoding direction and the smallest voxel size. PMID:19437043

  16. Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art.

    PubMed

    Stradiotti, P; Curti, A; Castellazzi, G; Zerbi, A

    2009-06-01

    The projectional nature of radiogram limits its amount of information about the instrumented spine. MRI and CT imaging can be more helpful, using cross-sectional view. However, the presence of metal-related artifacts at both conventional CT and MRI imaging can obscure relevant anatomy and disease. We reviewed the literature about overcoming artifacts from metallic orthopaedic implants at high-field strength MRI imaging and multi-detector CT. The evolution of multichannel CT has made available new techniques that can help minimizing the severe beam-hardening artifacts. The presence of artifacts at CT from metal hardware is related to image reconstruction algorithm (filter), tube current (in mA), X-ray kilovolt peak, pitch, hardware composition, geometry (shape), and location. MRI imaging has been used safely in patients with orthopaedic metallic implants because most of these implants do not have ferromagnetic properties and have been fixed into position. However, on MRI imaging metallic implants may produce geometric distortion, the so-called susceptibility artifact. In conclusion, although 140 kV and high milliamperage second exposures are recommended for imaging patients with hardware, caution should always be exercised, particularly in children, young adults, and patients undergoing multiple examinations. MRI artifacts can be minimized by positioning optimally and correctly the examined anatomy part with metallic implants in the magnet and by choosing fast spin-echo sequences, and in some cases also STIR sequences, with an anterior to posterior frequency-encoding direction and the smallest voxel size.

  17. Skeletal muscle disease: patterns of MRI appearances.

    PubMed

    Theodorou, D J; Theodorou, S J; Kakitsubata, Y

    2012-12-01

    Although the presumptive diagnosis of skeletal muscle disease (myopathy) may be made on the basis of clinical-radiological correlation in many cases, muscle biopsy remains the cornerstone of diagnosis. Myopathy is suspected when patients complain that the involved muscle is painful and tender, when they experience difficulty performing tasks that require muscle strength or when they develop various systemic manifestations. Because the cause of musculoskeletal pain may be difficult to determine clinically in many cases, MRI is increasingly utilised to assess the anatomical location, extent and severity of several pathological conditions affecting muscle. Infectious, inflammatory, traumatic, neurological, neoplastic and iatrogenic conditions can cause abnormal signal intensity on MRI. Although diverse, some diseases have similar MRI appearances, whereas others present distinct patterns of signal intensity abnormality. In general, alterations in muscle signal intensity fall into one of three cardinal patterns: muscle oedema, fatty infiltration and mass lesion. Because some of the muscular disorders may require medical or surgical treatment, correct diagnosis is essential. In this regard, MRI features, when correlated with clinical and laboratory findings as well as findings from other methods such as electromyography, may facilitate correct diagnosis. This article will review and illustrate the spectrum of MRI appearances in several primary and systemic disorders affecting muscle, both common and uncommon. The aim of this article is to provide radiologists and clinicians with a collective, yet succinct and useful, guide to a wide array of myopathies.

  18. The effect of implant angulation and splinting on stress distribution in implant body and supporting bone: A finite element analysis

    PubMed Central

    Behnaz, Ebadian; Ramin, Mosharraf; Abbasi, Samaneh; Pouya, Memar Ardestani; Mahmood, Farzin

    2015-01-01

    Objective: The aim of this study was to investigate the influence of implant crown splinting and the use of angulated abutment on stress distribution in implant body and surrounding bone by three-dimensional finite element analysis. Materials and Methods: For this study, three models with two implants at the site of mandibular right second premolar and first molar were designed (1): Both implants, parallel to adjacent teeth, with straight abutments (2): Anterior implant with 15 mesial angulations and posterior implant were placed parallel to adjacent tooth, (3): Both implants with 15 mesial angulations and parallel to each other with 15° angulated abutments. Restorations were modeled in two shapes (splinted and nonsplinted). Loading in tripod manner as each point 50 N and totally 300 N was applied. Stress distribution in relation to splinting or nonsplinting restorations and angulations was done with ABAQUS6.13. Results: Splinting the restorations in all situations, led to lower stresses in all implant bodies, cortical bone and spongy bone except for the spongy bone around angulated first molar. Angulated implant in nonsplinted restoration cause lower stresses in implant body and bone but in splinted models more stresses were seen in implant body in comparison with straight abutment (model 2). Stresses in nonsplinted and splinted restorations in cortical bone of angulated molar region were more than what was observed in straight molar implant (model 3). Conclusion: Implant restorations splinting lead to a better distribution of stresses in implant bodies and bone in comparison with nonsplinted restorations, especially when the load is applied off center to implant body. Angulations of implant can reduce stresses when the application of the load is in the same direction as the implant angulation. PMID:26430356

  19. Peri-Implant Diseases

    MedlinePlus

    ... Alcohol Consumption and Gum Health Workshop on Regeneration Periodontal Disease More Prevalent among Ethnic Minorities Dental Implants Periodontal ... factors for developing peri-implant disease include previous periodontal disease diagnosis, poor plaque control, smoking , and diabetes . It ...

  20. Implants for lucky few

    NASA Astrophysics Data System (ADS)

    Brandon, David

    2011-08-01

    In his article "Vision of beauty" (May pp22-27), Richard Taylor points the way to fractal design for retinal implants and makes an enthusiastic case for incorporating such features into the next generation of such implants.

  1. Ion-implantation studies on perpendicular media.

    PubMed

    Gaur, Nikita; Maurer, Siegfried L; Nunes, Ronald W; Piramanayagam, S N; Bhatia, C S

    2011-03-01

    Magnetic and structural properties of ion implanted perpendicular recording media have been investigated. Effects of 12C+ ion implantation with the doses of 2 x 10(11), 10(13), 10(14) and 10(16) ions/cm2 in the magnetic recording layer of conventional granular and continuous perpendicular media are reported in this paper. Implantation with the highest fluence of 10(16) ions/cm2 resulted in change of the magnetization reversal mechanism, thereby reducing coercivity. In continuous media the implanted ions cause increase in pinning defects, leading to an increase in coercivity. In contrast, high dose was found to cause similar change in the crystallographic properties of both the granular and continuous media.

  2. In vitro magnetic resonance imaging evaluation of ossicular implants at 3 T.

    PubMed

    Shellock, Frank G; Meepos, Lauren N; Stapleton, Matthew R; Valencerina, Sam

    2012-07-01

    Ossicular implants made from metallic materials may be acceptable or pose hazards for patients referred for magnetic resonance imaging (MRI) examinations, depending on the outcome of proper MRI testing procedures. Using a 3-T MR system, 2 ossicular implants were tested for magnetic field interactions, heating, and artifacts. Two different ossicular implants (Stainless Steel/Fluoroplastic Sanna-Type Piston [6 mm in length] and the Offset ALTO Total Prosthesis [15 mm in length, titanium/silicone]; Grace Medical, Memphis, TN, USA) were selected for testing, which represented the largest metallic mass and materials with the highest magnetic susceptibilities, with the intent of applying the MRI findings to other ossicular implants. The implants were evaluated at 3-T for magnetic field interactions, heating, and artifacts using standard previously described techniques. Each ossicular implant showed relatively minor magnetic field interactions that will not be associated with movement in situ. Heating was not excessive (highest temperature change, ≤ 1.6°C; background temperature change, 1.5°C). Artifacts, although relatively small, may create issues for diagnostic imaging if the area of interest is in the same area or close to these ossicular implants. The results of this investigation demonstrated that it would be acceptable (i.e., "MR conditional" using current terminology) for patients with these ossicular implants to undergo MRI examinations at 3 T or less. In consideration of the materials and dimensions of the implants that underwent testing, these findings pertain to many other similar ossicular implants from the same manufacturer.

  3. Correction of MRI-induced geometric distortions in whole-body small animal PET-MRI

    SciTech Connect

    Frohwein, Lynn J. Schäfers, Klaus P.; Hoerr, Verena; Faber, Cornelius

    2015-07-15

    Purpose: The fusion of positron emission tomography (PET) and magnetic resonance imaging (MRI) data can be a challenging task in whole-body PET-MRI. The quality of the registration between these two modalities in large field-of-views (FOV) is often degraded by geometric distortions of the MRI data. The distortions at the edges of large FOVs mainly originate from MRI gradient nonlinearities. This work describes a method to measure and correct for these kind of geometric distortions in small animal MRI scanners to improve the registration accuracy of PET and MRI data. Methods: The authors have developed a geometric phantom which allows the measurement of geometric distortions in all spatial axes via control points. These control points are detected semiautomatically in both PET and MRI data with a subpixel accuracy. The spatial transformation between PET and MRI data is determined with these control points via 3D thin-plate splines (3D TPS). The transformation derived from the 3D TPS is finally applied to real MRI mouse data, which were acquired with the same scan parameters used in the phantom data acquisitions. Additionally, the influence of the phantom material on the homogeneity of the magnetic field is determined via field mapping. Results: The spatial shift according to the magnetic field homogeneity caused by the phantom material was determined to a mean of 0.1 mm. The results of the correction show that distortion with a maximum error of 4 mm could be reduced to less than 1 mm with the proposed correction method. Furthermore, the control point-based registration of PET and MRI data showed improved congruence after correction. Conclusions: The developed phantom has been shown to have no considerable negative effect on the homogeneity of the magnetic field. The proposed method yields an appropriate correction of the measured MRI distortion and is able to improve the PET and MRI registration. Furthermore, the method is applicable to whole-body small animal

  4. [Implantable artificial heart].

    PubMed

    Nojiri, Chisato

    2005-11-01

    Heart transplants have been decreasing globally due to the lack of available donor hearts. As a result, the increased use of artificial hearts is anticipated as an alternative therapy. Although biocompatibility issues, such as thrombus formation/thromboembolism and infection, are still the main cause of mortality associated with artificial hearts, more than 20 different types are now clinically available after a half-century of development and experimental trials. These devices range from extracorporeal pneumatic to implantable battery-powered artificial hearts. The early development of artificial hearts logically focused on volumetric pump designs incorporating functions similar to the natural heart. Today, development has shifted toward designs that are significantly different from the natural heart. These pumps utilize axial or centrifugal flow allowing for a much simpler design, which is smaller in size and has very few moving parts. With rapid advances in technology, this new generation of artificial heart pumps is beginning to emerge as an alternative to heart transplants.

  5. Cochlear Implants for Children.

    ERIC Educational Resources Information Center

    Hasenstab, M. Suzanne; Laughton, Joan

    1991-01-01

    The use of cochlear implants in children with profound bilateral hearing loss is discussed, focusing on how a cochlear implant works; steps in a cochlear implant program (evaluation, surgery, programing, and training); and rehabilitation procedures involved in auditory development and speech development. (JDD)

  6. Implantable Heart Aid

    NASA Technical Reports Server (NTRS)

    1984-01-01

    CPI's human-implantable automatic implantable defibrillator (AID) is a heart assist system, derived from NASA's space circuitry technology, that can prevent erratic heart action known as arrhythmias. Implanted AID, consisting of microcomputer power source and two electrodes for sensing heart activity, recognizes onset of ventricular fibrillation (VF) and delivers corrective electrical countershock to restore rhythmic heartbeat.

  7. Late extrusion of alloplastic orbital floor implants.

    PubMed

    Brown, A E; Banks, P

    1993-06-01

    Complications following the use of alloplastic orbital floor implants are well documented but it is not widely recognised that these can occur many years after initial treatment. Three patients who presented with late extrusion of an implant through the facial skin are reported. This complication occurred 10, 16 and 17 years respectively after treatment of the orbital floor fracture. The tissue reaction to silicone rubber and Teflon inplants is reviewed and the possible cause for this late complication is discussed.

  8. Extraocular Surgical Approach for Placement of Subretinal Implants in Blind Patients: Lessons from Cochlear-Implants

    PubMed Central

    Koitschev, Assen; Stingl, Katarina; Bartz-Schmidt, Karl Ulrich; Braun, Angelika; Gekeler, Florian; Greppmaier, Udo; Sachs, Helmut; Peters, Tobias; Wilhelm, Barbara; Zrenner, Eberhart; Besch, Dorothea

    2015-01-01

    In hereditary retinal diseases photoreceptors progressively degenerate, often causing blindness without therapy being available. Newly developed subretinal implants can substitute functions of photoreceptors. Retina implant extraocular surgical technique relies strongly on cochlear-implant know-how. However, a completely new surgical approach providing safe handling of the photosensor array had to be developed. The Retina Implant Alpha IMS consisting of a subretinal microphotodiode array and cable linked to a cochlear-implant-like ceramic housing was introduced via a retroauricular incision through a subperiosteal tunnel above the zygoma into the orbit using a specially designed trocar. Implant housing was fixed in a bony bed within a tight subperiosteal pocket in all patients. Primary outcomes were patient short term safety as well as effectiveness. Nine patients participated in the first part of the multicenter trial and received the subretinal visual implant in one eye. In all cases microphotodiode array pull-through procedure and stable positioning were possible without affecting the device function. No intraoperative complications were encountered. The minimally invasive suprazygomatic tunneling technique for the sensor unit as well as a subperiosteal pocket fixation of the implant housing provides a safe extraocular implantation approach of a subretinal device with a transcutaneous extracorporeal power supply. PMID:26783453

  9. Extraocular Surgical Approach for Placement of Subretinal Implants in Blind Patients: Lessons from Cochlear-Implants.

    PubMed

    Koitschev, Assen; Stingl, Katarina; Bartz-Schmidt, Karl Ulrich; Braun, Angelika; Gekeler, Florian; Greppmaier, Udo; Sachs, Helmut; Peters, Tobias; Wilhelm, Barbara; Zrenner, Eberhart; Besch, Dorothea

    2015-01-01

    In hereditary retinal diseases photoreceptors progressively degenerate, often causing blindness without therapy being available. Newly developed subretinal implants can substitute functions of photoreceptors. Retina implant extraocular surgical technique relies strongly on cochlear-implant know-how. However, a completely new surgical approach providing safe handling of the photosensor array had to be developed. The Retina Implant Alpha IMS consisting of a subretinal microphotodiode array and cable linked to a cochlear-implant-like ceramic housing was introduced via a retroauricular incision through a subperiosteal tunnel above the zygoma into the orbit using a specially designed trocar. Implant housing was fixed in a bony bed within a tight subperiosteal pocket in all patients. Primary outcomes were patient short term safety as well as effectiveness. Nine patients participated in the first part of the multicenter trial and received the subretinal visual implant in one eye. In all cases microphotodiode array pull-through procedure and stable positioning were possible without affecting the device function. No intraoperative complications were encountered. The minimally invasive suprazygomatic tunneling technique for the sensor unit as well as a subperiosteal pocket fixation of the implant housing provides a safe extraocular implantation approach of a subretinal device with a transcutaneous extracorporeal power supply.

  10. Magnetic Resonance Imaging (MRI): Lumbar Spine (For Parents)

    MedlinePlus

    ... cause a problem near a strong magnetic field. Electronic devices aren't permitted in the MRI room. ... child may be given headphones to listen to music or earplugs to block the noise, and will ...

  11. MRI of the Breast

    MedlinePlus

    ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ... tell the technologist if you have medical or electronic devices in your body. These objects may interfere ...

  12. MRI of the Prostate

    MedlinePlus

    ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ... tell the technologist if you have medical or electronic devices in your body. These objects may interfere ...

  13. Lumbar MRI scan

    MedlinePlus

    ... may need a lumbar MRI if you have: Low back pain that does not get better after treatment Leg ... spine Injury or trauma to the lower spine Low back pain and a history or signs of cancer Multiple ...

  14. Cervical MRI scan

    MedlinePlus

    ... magnetic resonance imaging) scan uses energy from strong magnets to create pictures of the part of the ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed into the room ...

  15. Leg MRI scan

    MedlinePlus

    ... resonance imaging) scan of the leg uses strong magnets to create pictures of the leg. This may ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed into the room ...

  16. Shoulder MRI scan

    MedlinePlus

    ... an imaging test that uses energy from powerful magnets and to create pictures of the shoulder area. ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed in the room ...

  17. MRI of the Breast

    MedlinePlus

    ... of the breast uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of ... scans, MRI does not utilize ionizing radiation. Instead, radio waves redirect alignment of hydrogen atoms that naturally exist ...

  18. Discomfort/pain due to periodontal and peri-implant probing: Implant type and age.

    PubMed

    Stanner, Julia; Klum, Matthias; Parvini, Puria; Zuhr, Otto; Nickles, Katrin; Eickholz, Peter

    2017-07-01

    There is evidence that patients experience more discomfort/pain after peri-implant probing than periodontal probing. However, there are several plausible factors to additionally influence this observation: e.g., implant type, age, smoking. Thus, this study was designed to compare discomfort/pain after periodontal and peri-implant probing in different implant types. Two dentists recruited and examined 80 patients, each of them exhibiting a dental implant with a contralateral natural tooth. Only two types of implants were included. Periodontal and peri-implant probing depths (PPD) and probing attachment level (PAL) were assessed. Whether implant or tooth were measured first was randomly assigned. Immediately after probing patients scored discomfort/pain using a visual analogue scale (VAS). Eighty patients (median; lower/upper quartile: age 57; 47.5/65.5 years; 40 females, 11 smokers) were examined. With the exception of PPD and PAL at the deepest site as well as mean PPD (p < .05) clinical parameters (PAL, bleeding on probing, suppuration) were well balanced between implants and teeth. Peri-implant probing (VAS: 9.0; 5.0/17.0) caused significantly (p = .038) more discomfort/pain than periodontal probing (5.5; 2.0/13.5). This was confirmed by repeated measures analysis of variance adjusting for several factors (p = .011). Peri-implant probing caused significantly more discomfort/pain than periodontal probing. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. MRI Mode Programming for Safe Magnetic Resonance Imaging in Patients With a Magnetic Resonance Conditional Cardiac Device.

    PubMed

    Nakai, Toshiko; Kurokawa, Sayaka; Ikeya, Yukitoshi; Iso, Kazuki; Takahashi, Keiko; Sasaki, Naoko; Ashino, Sonoko; Okubo, Kimie; Okumura, Yasuo; Kunimoto, Satoshi; Watanabe, Ichiro; Hirayama, Atsushi

    2016-01-01

    Although diagnostically indispensable, magnetic resonance imaging (MRI) has been, until recently, contraindicated in patients with an implantable cardiac device. MR conditional cardiac devices are now widely used, but the mode programming needed for safe MRI has yet to be established. We reviewed the details of 41 MRI examinations of patients with a MR conditional device. There were no associated adverse events. However, in 3 cases, paced beats competed with the patient's own beats during the MRI examination. We describe 2 of the 3 specific cases because they illustrate these potentially risky situations: a case in which the intrinsic heart rate increased and another in which atrial fibrillation occurred. Safe MRI in patients with an MR conditional device necessitates detailed MRI mode programming. The MRI pacing mode should be carefully and individually selected.

  20. Chimeric Peptides as Implant Functionalization Agents for Titanium Alloy Implants with Antimicrobial Properties

    NASA Astrophysics Data System (ADS)

    Yucesoy, Deniz T.; Hnilova, Marketa; Boone, Kyle; Arnold, Paul M.; Snead, Malcolm L.; Tamerler, Candan

    2015-04-01

    Implant-associated infections can have severe effects on the longevity of implant devices and they also represent a major cause of implant failures. Treating these infections associated with implants by antibiotics is not always an effective strategy due to poor penetration rates of antibiotics into biofilms. Additionally, emerging antibiotic resistance poses serious concerns. There is an urge to develop effective antibacterial surfaces that prevent bacterial adhesion and proliferation. A novel class of bacterial therapeutic agents, known as antimicrobial peptides (AMPs), are receiving increasing attention as an unconventional option to treat septic infection, partly due to their capacity to stimulate innate immune responses and for the difficulty of microorganisms to develop resistance towards them. While host and bacterial cells compete in determining the ultimate fate of the implant, functionalization of implant surfaces with AMPs can shift the balance and prevent implant infections. In the present study, we developed a novel chimeric peptide to functionalize the implant material surface. The chimeric peptide simultaneously presents two functionalities, with one domain binding to a titanium alloy implant surface through a titanium-binding domain while the other domain displays an antimicrobial property. This approach gains strength through control over the bio-material interfaces, a property built upon molecular recognition and self-assembly through a titanium alloy binding domain in the chimeric peptide. The efficiency of chimeric peptide both in-solution and absorbed onto titanium alloy surface was evaluated in vitro against three common human host infectious bacteria, Streptococcus mutans, Staphylococcus epidermidis, and Escherichia coli. In biological interactions such as occur on implants, it is the surface and the interface that dictate the ultimate outcome. Controlling the implant surface by creating an interface composed chimeric peptides may therefore

  1. Molecular fMRI

    PubMed Central

    Bartelle, Benjamin B.; Barandov, Ali

    2016-01-01

    Comprehensive analysis of brain function depends on understanding the dynamics of diverse neural signaling processes over large tissue volumes in intact animals and humans. Most existing approaches to measuring brain signaling suffer from limited tissue penetration, poor resolution, or lack of specificity for well-defined neural events. Here we discuss a new brain activity mapping method that overcomes some of these problems by combining MRI with contrast agents sensitive to neural signaling. The goal of this “molecular fMRI” approach is to permit noninvasive whole-brain neuroimaging with specificity and resolution approaching current optical neuroimaging methods. In this article, we describe the context and need for molecular fMRI as well as the state of the technology today. We explain how major types of MRI probes work and how they can be sensitized to neurobiological processes, such as neurotransmitter release, calcium signaling, and gene expression changes. We comment both on past work in the field and on challenges and promising avenues for future development. SIGNIFICANCE STATEMENT Brain researchers currently have a choice between measuring neural activity using cellular-level recording techniques, such as electrophysiology and optical imaging, or whole-brain imaging methods, such as fMRI. Cellular level methods are precise but only address a small portion of mammalian brains; on the other hand, whole-brain neuroimaging techniques provide very little specificity for neural pathways or signaling components of interest. The molecular fMRI techniques we discuss have particular potential to combine the specificity of cellular-level measurements with the noninvasive whole-brain coverage of fMRI. On the other hand, molecular fMRI is only just getting off the ground. This article aims to offer a snapshot of the status and future prospects for development of molecular fMRI techniques. PMID:27076413

  2. MRI-guided brachytherapy

    PubMed Central

    Tanderup, Kari; Viswanathan, Akila; Kirisits, Christian; Frank, Steven J.

    2014-01-01

    The application of MRI-guided brachytherapy has demonstrated significant growth during the last two decades. Clinical improvements in cervix cancer outcomes have been linked to the application of repeated MRI for identification of residual tumor volumes during radiotherapy. This has changed clinical practice in the direction of individualized dose administration, and mounting evidence of improved clinical outcome with regard to local control, overall survival as well as morbidity. MRI-guided prostate HDR and LDR brachytherapy has improved the accuracy of target and organs-at-risk (OAR) delineation, and the potential exists for improved dose prescription and reporting for the prostate gland and organs at risk. Furthermore, MRI-guided prostate brachytherapy has significant potential to identify prostate subvolumes and dominant lesions to allow for dose administration reflecting the differential risk of recurrence. MRI-guided brachytherapy involves advanced imaging, target concepts, and dose planning. The key issue for safe dissemination and implementation of high quality MRI-guided brachytherapy is establishment of qualified multidisciplinary teams and strategies for training and education. PMID:24931089

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

    PubMed

    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.

  4. MB-SWIFT functional MRI during deep brain stimulation in rats.

    PubMed

    Lehto, Lauri J; Idiyatullin, Djaudat; Zhang, Jinjin; Utecht, Lynn; Adriany, Gregor; Garwood, Michael; Gröhn, Olli; Michaeli, Shalom; Mangia, Silvia

    2017-08-07

    Recently introduced 3D radial MRI pulse sequence entitled Multi-Band SWeep Imaging with Fourier Transformation (MB-SWIFT) having virtually zero acquisition delay was used to obtain functional MRI (fMRI) contrast in rat's brain at 9.4 T during deep brain stimulation (DBS). The results demonstrate that MB-SWIFT allows functional images free of susceptibility artifacts, and provides an excellent fMRI activation contrast in the brain. Flip angle dependence of the MB-SWIFT fMRI signal and elimination of the fMRI contrast while using saturation bands, indicate a blood flow origin of the observed fMRI contrast. MB-SWIFT fMRI modality permits activation studies in the close proximity to an implanted lead, which is not possible to achieve with conventionally used gradient echo and spin echo - echo planar imaging fMRI techniques. We conclude that MB-SWIFT fMRI is a powerful imaging modality for investigations of functional responses during DBS. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  5. Liposuction fat-fillant implant for breast augmentation and reconstruction.

    PubMed

    Hang-Fu, L; Marmolya, G; Feiglin, D H

    1995-01-01

    The perfect breast implant fillant material would have higher viscosity than water and would be autologous and harmless. We describe the confinement of liposuction fat in implants using the Lipovacutainer during a routine liposuction procedure. This collected fat is prepared inside the Lipovacutainer and is reinjected through a Lipomedia filling cannula into a leaf valve implant as the fillant in place of saline. The implants are used for bilateral augmentation mammoplasty and breast reconstruction procedures. Our six clinical cases have been monitored closely using mammography and MRI. These cases showed slow liquefaction without interference with mammography studies. We obtained excellent overall body contours. All complications were correctable and non-life-threatening and there was no capsule formation.

  6. A Case of Orbital Abscess following Porous Orbital Implant Infection

    PubMed Central

    Hong, Seung Woo; Paik, Ji-Sun; Kim, So-Youl

    2006-01-01

    Purpose We present a case of orbital abscess following porous orbital implant infection in a 73-year-old woman with rheumatoid arthritis. Methods Just one month after a seemingly uncomplicated enucleation and porous polyethylene (Medpor®) orbital implant surgery, implant exposure developed with profuse pus discharge. The patient was unresponsive to implant removal and MRI confirmed the presence of an orbital pus pocket. Despite extirpation of the four rectus muscles, inflammatory granulation debridement and abscess drainage, another new pus pocket developed. Results After partial orbital exenteration, the wound finally healed well without any additional abscess formation. Conclusions A patient who has risk factors for delayed wound healing must be examined thoroughly and extreme care such as exenteration must be taken if there is persistent infection. PMID:17302210

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

    PubMed

    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.

  8. Delivering optical power to subcutaneous implanted devices.

    PubMed

    Ayazian, Sahar; Hassibi, Arjang

    2011-01-01

    In this paper, a new, easy-to-implement, and MRI-compatible approach for delivering power to implantable devices is presented. The idea is to harvest the energy of light within the therapeutic window wavelengths, where the optical absorption is small, by using subcutaneous photovoltaic (PV) cells. Depending on the application, this energy can then be used to directly drive the embedded electronics of an implanted device or recharge its battery. To show the feasibility of this system, a CMOS chip based on this concept has been implemented and tested. The experimental results demonstrate that μW's of power in ambient light conditions can be harvested using mm(2)-size PV cells. This amount of power is sufficient to address the needs of many low-power applications.

  9. [Hypersensitivity to metals in patients with orthopedic implants].

    PubMed

    Sánchez Olivas, Manuel Anastacio; Valencia Zavala, Martha Patricia; Sánchez Olivas, Jesús Alberto; Sepúlveda Velázquez, Guadalupe

    2010-01-01

    All metals in contact with biological systems suffer corrosion, which is an electrochemical process that causes metallic ions formation, known as haptens, which link with endogenous or exogenous proteins, therefore inducing an immune response. A hypersensitivity response to an implanted material should be suspected when cutaneous lesions or inflammatory reactions occur proximal to or surrounding the site of the metallic orthopedic implant. At present there is no a reliable diagnostic test for the determination of hypersensitivity to implanted metallic devices. It has been shown that the products of corrosive degradation are associated with dermatitis, urticaria and vasculitis. Cutaneous lesions in patients with unsuccessful metallic implants are more frequent than in non-rejected implants or the general population. Although the cellular and humoral hypersensitivity response in metallic orthopedic implants has been clearly identified, the risk is very low. Nowadays the importance of hypersensitivity to metals as a contributing factor in the failure of implants is unknown.

  10. Trends in Cochlear Implants

    PubMed Central

    Zeng, Fan-Gang

    2004-01-01

    More than 60,000 people worldwide use cochlear implants as a means to restore functional hearing. Although individual performance variability is still high, an average implant user can talk on the phone in a quiet environment. Cochlear-implant research has also matured as a field, as evidenced by the exponential growth in both the patient population and scientific publication. The present report examines current issues related to audiologic, clinical, engineering, anatomic, and physiologic aspects of cochlear implants, focusing on their psychophysical, speech, music, and cognitive performance. This report also forecasts clinical and research trends related to presurgical evaluation, fitting protocols, signal processing, and postsurgical rehabilitation in cochlear implants. Finally, a future landscape in amplification is presented that requires a unique, yet complementary, contribution from hearing aids, middle ear implants, and cochlear implants to achieve a total solution to the entire spectrum of hearing loss treatment and management. PMID:15247993

  11. Alternative diagnoses at paediatric appendicitis MRI.

    PubMed

    Moore, M M; Kulaylat, A N; Brian, J M; Khaku, A; Hulse, M A; Engbrecht, B W; Methratta, S T; Boal, D K B

    2015-08-01

    As the utilization of MRI in the assessment for paediatric appendicitis increases in clinical practice, it is important to recognize alternative diagnoses as the cause of abdominal pain. The purpose of this review is to share our institution's experience using MRI in the evaluation of 510 paediatric patients presenting with suspected appendicitis over a 30 month interval (July 2011 to December 2013). An alternative diagnosis was documented in 98/510 (19.2%) patients; adnexal pathology (6.3%, n = 32), enteritis-colitis (6.3%, n = 32), and mesenteric adenitis (2.2%, n = 11) comprised the majority of cases. These common entities and other less frequent illustrative cases obtained during our overall institutional experience with MRI for suspected appendicitis are reviewed.

  12. Clinical safety of the ProMRI pacemaker system in patients subjected to thoracic spine and cardiac 1.5-T magnetic resonance imaging scanning conditions.

    PubMed

    Bailey, William M; Mazur, Alexander; McCotter, Craig; Woodard, Pamela K; Rosenthal, Lawrence; Johnson, Whitney; Mela, Theofanie

    2016-02-01

    Permanent cardiac pacemakers have historically been considered a contraindication to magnetic resonance imaging (MRI). The purpose of the ProMRI Phase B Study, a multicenter, prospective, single-arm, nonrandomized study, was to evaluate the clinical safety of the Biotronik ProMRI pacemaker system in patients undergoing thoracic spine and cardiac MRI. The ProMRI Phase B study enrolled 245 patients with stable baseline pacing indices implanted with an Entovis pacemaker (DR-T or SR-T) and Setrox 53-cm and/or 60-cm lead(s). Device interrogation was performed at enrollment, pre- and post-MRI scan, and 1 and 3 months post-MRI. End-points were (1) freedom from MRI- and pacing system-related serious adverse device effects through 1 month post-MRI; (2) freedom from atrial and ventricular MRI-induced pacing threshold increase (>0.5 V); and (3) freedom from P- and R-wave amplitude attenuation (<50%), or P wave <1.5 mV, or R wave <5.0 mV at 1 month post-MRI. In total, 216 patients completed the MRI and 1-month post-MRI follow-up. One adverse event possibly related to the implanted system and the MRI procedure occurred, resulting in a serious adverse device effect-free rate of 99.6% (220/221; P < .0001. Freedom from atrial and ventricular pacing threshold increase was 100% (194/194, P < .001) and 100% (206/206, P < .001) respectively. Freedom from P- and R-wave amplitude attenuation was 98.2% (167/170, P < .001) and 100% (188/188, P < .001) respectively. The results of the ProMRI Phase B study demonstrate the clinical safety and efficacy of the ProMRI pacemaker system in patients subjected to thoracic spine and cardiac MRI conditions. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  13. Management of implant failure during transcatheter aortic valve implantation.

    PubMed

    Ussia, Gian Paolo; Barbanti, Marco; Immè, Sebastiano; Scarabelli, Marilena; Mulè, Massimiliano; Cammalleri, Valeria; Aruta, Patrizia; Pistritto, Anna Maria; Capodanno, Davide; Deste, Wanda; Di Pasqua, Maria Concetta; Tamburino, Corrado

    2010-09-01

    Transcatheter aortic valve implantation (TAVI) is an emerging alternative to palliative medical therapy for nonsurgical patients with severe aortic stenosis. There is a paucity of detailed data on the management and outcome of complications related to the sub-optimal deployment of the prosthesis. We appraised the incidence and management of early implant failure occurring during TAVI. Of 110 patients who underwent TAVI using the third generation 18-French CoreValve ReValving System (Medtronic, MN) in our Institution between June 2007 and January 2010, we identified those experiencing early implant failure and reported on their management and clinical outcome. The primary endpoint was the incidence of major adverse cardiovascular and cerebrovascular event (MACCE) at 30 days and mid-term follow up. Early implant failure occurred in 18 of 110 patients (16.3%). The most common cause was prosthesis under-expansion conditioning moderate to severe peri-valvular leak (44.4%). Prosthesis deployment too low or too high with respect to the aortic annulus leading to severe peri-valvular leak occurred in 22.2% and 5.5% of patients, respectively. Need of valve retrieve after the first attempt of deployment occurred in four cases (22.2%). Prosthesis embolization in the ascending aorta occurred in 5.5% of patients who experienced early implant failure. All implant failure cases were managed percutaneously with gain in aortic valve area from 0.44 ± 0.17 to 1.28 ± 0.27 cm(2) (P < 0.001), decrease of mean transaortic gradient from 55.00 ± 19.51 to 11.58 ± 5.91 mmHg (P < 0.001) and no MACCE at 30 days. After 11 ± 6 months, MACCE occurred cumulatively in two patients (11.1%). Early implant failure can complicate the TAVI procedure with the CoreValve system, but it can be managed safely and effectively with bailout transcatheter techniques, avoiding surgery, with good early and mid-term clinical and echocardiographic results.

  14. Histopathology of the inner ear relevant to cochlear implantation.

    PubMed

    Nadol, Joseph B; Eddington, Donald K

    2006-01-01

    The most common forms of severe hearing loss and deafness are related to morphological changes in the cochlea. Many individuals with such forms of hearing disorders have received cochlear implants. It has been assumed that preservation of spiral ganglion cells is important for success of cochlear implants. Preservation of ganglion cells is negatively correlated with the duration of the hearing loss. It has, however, not been possible to reveal a relationship between the degree of survival of spiral ganglion cells and performance of cochlear implants. It is important to understand the histopathological changes that follow cochlear implantation. Insertion of cochlear implants may cause trauma to the basilar membrane, the spiral lamina, and the spiral ligament. Rupture of the basilar membrane may occur. Over time, new bone forms at the cochleostomy and along the implant track. Further investigation is necessary to evaluate the causes of variability of behavioral measures of performance.

  15. Bioactive coatings for orthopaedic implants-recent trends in development of implant coatings.

    PubMed

    Zhang, Bill G X; Myers, Damian E; Wallace, Gordon G; Brandt, Milan; Choong, Peter F M

    2014-07-04

    Joint replacement is a major orthopaedic procedure used to treat joint osteoarthritis. Aseptic loosening and infection are the two most significant causes of prosthetic implant failure. The ideal implant should be able to promote osteointegration, deter bacterial adhesion and minimize prosthetic infection. Recent developments in material science and cell biology have seen the development of new orthopaedic implant coatings to address these issues. Coatings consisting of bioceramics, extracellular matrix proteins, biological peptides or growth factors impart bioactivity and biocompatibility to the metallic surface of conventional orthopaedic prosthesis that promote bone ingrowth and differentiation of stem cells into osteoblasts leading to enhanced osteointegration of the implant. Furthermore, coatings such as silver, nitric oxide, antibiotics, antiseptics and antimicrobial peptides with anti-microbial properties have also been developed, which show promise in reducing bacterial adhesion and prosthetic infections. This review summarizes some of the recent developments in coatings for orthopaedic implants.

  16. In Vivo Magnetic Resonance Imaging of Type I Collagen Scaffold in Rat: Improving Visualization of Bladder and Subcutaneous Implants

    PubMed Central

    Sun, Yi; Geutjes, Paul; Oosterwijk, Egbert

    2014-01-01

    Noninvasive monitoring of implanted scaffolds is important to understand their behavior and role in tissue engineering, in particular to follow their degradation and interaction with host tissue. Magnetic resonance imaging (MRI) is well suited for this goal, but its application is often hampered by the low contrast of scaffolds that are prepared from biomaterials such as type I collagen. The aim of this study was to test iron oxide particles incorporation in improving their MRI contrasts, and to follow their degradation and tissue interactions. Scaffolds with and without iron oxide particles were implanted either subcutaneously or on the bladder of rats. At predetermined time points, in vivo MRI were obtained and tissues were then harvested for histology analysis and transmission electron microscopy. The result showed that the incorporation of iron oxide particles improved MRI contrast of the implants, providing information on their location, shapes, and degradation. Second, the host tissue reaction to the type I collagen implants could be observed in both MRI and histology. Finally, MRI also revealed that the degradation and host tissue reaction of iron particles-loaded scaffolds differed between subcutaneous and bladder implantation, which was substantiated by histology. PMID:24625324

  17. Comparison of vascularization of Medpor and Medpor-Plus orbital implants: a prospective, randomized study.

    PubMed

    Naik, Milind N; Murthy, Ramesh K; Honavar, Santosh G

    2007-01-01

    To compare vascularization of porous polyethylene (Medpor) and porous polyethylene with synthetic bone graft particulate (Medpor-Plus) orbital implants following enucleation. Prospective, randomized study involving 10 patients. A standard enucleation procedure was performed, and each patient was randomized to receive either Medpor or Medpor-Plus orbital implant with anterior scleral cap technique. Gadolinium-enhanced, 3-Tesla MRI was performed at 1.5 months, 3 months, and 4.5 months following surgery. Implant vascularization was calculated in axial, coronal, and sagittal planes with manual planimetric method using postcontrast T1-weighted Digital Imaging and Communications in Medicine images. The mean area of implant vascularization at 1.5 months, 3 months, and 4.5 months for Medpor implants was 58%, 70%, and 75%, respectively, and for Medpor-Plus implants was 69%, 76%, and 85%, respectively. The mean vascularization of Medpor-Plus implants was more than Medpor implants at 1.5 months (p = 0.008), 3 months (p = 0.09), and 4.5 months (p = 0.003). The difference between the 2 groups assessed by repeated measures analysis of variance was statistically significant (p < 0.0001). During the mean follow-up of 36.7 months (range, 18-43 months), 1 patient in the Medpor group had implant exposure that responded to scleral patch graft. Implant vascularization is faster with Medpor-Plus implants compared with Medpor implants when assessed by a planimetric method using 3 Tesla MRI. The addition of synthetic bone graft particulate (Novabone) to porous polyethylene may enhance implant vascularization.

  18. Adverse events and discomfort during magnetic resonance imaging in cochlear implant recipients.

    PubMed

    Kim, Bo Gyung; Kim, Jin Won; Park, Jeong Jin; Kim, Sung Huhn; Kim, Hee Nam; Choi, Jae Young

    2015-01-01

    Patients with cochlear implants (CIs) should be fully informed before undergoing magnetic resonance imaging (MRI) about the possibility of discomfort or pain. Prior to an MRI scan, patients need to fully understand not only the potential complications but also the potential discomfort that they may experience during the scan. To assess the adverse events during MRI in patients with CIs and to investigate the safety and diagnostic efficiency of MRI in patients with CIs with internal magnets. Retrospective review of the medical records of 18 patients with CIs undergoing MRI between September 2003 and February 2014 at a single tertiary referral center. Sixteen patients underwent MRI in a 1.5-T scanner, and 2 patients underwent MRI in a 3.0-T scanner. Twelve brain MRI scans were performed, and 18 MRI scans were performed in areas outside the brain. Discomfort or pain, adverse events, and auditory performance after MRI were evaluated using medical records or interviews. Thirteen of 18 patients completed their MRI scans (25 of 30 scans). Five patients with head bandages were unable to complete their MRI scans owing to pain; one of these patients experienced magnet displacement, and another underwent surgery for magnet removal and reinsertion. Finally, 1 patient experienced polarity reversal of the magnet. Artifacts induced by the CI internal magnet compromised the diagnosis of ipsilateral brain lesions under 1.5-T MRI. Auditory performance in the CI recipients who had major events was unaffected. Even with protective head bandages, 1.5-T MRI in patients with CIs led to a variety of adverse events, including discomfort or pain and displacement of the internal magnet. Therefore, sedation and careful head positioning may be appropriate for some patients with CIs who undergo MRI, and these patients should be carefully monitored to decrease the likelihood of such adverse effects.

  19. Indications of implant removal: A study of 83 cases

    PubMed Central

    Haseeb, Muhammad; Butt, Muhammad Farooq; Altaf, Tariq; Muzaffar, Khalid; Gupta, Anil; Jallu, Aleena

    2017-01-01

    Introduction: Fracture fixation has become advanced with the advent of new and custom metal implants for each type of bone/fracture. After union though, the implant ceases to be important and may be removed. Routine removal is advocated by some and opposed by others. Nevertheless, some patients require removal of the hardware because of various implant-related problems. Our study was aimed at identifying the most common causes for implant removal. Objective: To investigate the common indications of orthopedic implant removal surgeries. Methods: Adult patients admitted for implant removal in our department were included in the study. They were operated in the next OT list. They were then followed for an average 4 months for resolutions of symptoms or appearance of new problems. Results: A total of 83 patients were studied. 71 of them were males. The mean age was 38 years. The reasons for removal of implants were found to lie in five categories: Pain/discomfort/prominent hardware, infected hardware, implant failure, elective (patient’s insistence), and other reasons. Overall, the most frequently removed implants in our series were distal tibial/ankle plates (14.45% of implants removed), femoral intramedullary (IM) nails (13.25%), olecranon wires and plates (12.04%), and tibial IM nails and patellar tension band wirings (9.53% each). Discussion and Conclusion: The clinical indications of implant removal are not well established, and few definitive data exist to guide whether routine implant removal is appropriate. Symptomatic hardware frequently needs removal. We found that pain and implant prominence (mechanical symptoms) are the most common indications. Infection is the next most common, followed by hardware failure. Other indications are implant failure, bone resorption due to excessive stress shielding and patient’s will. Removal is, however, not an easy surgery, and several factors such as bone ingrowth and wear of the implant may make its removal difficult

  20. Osteonecrosis associated with dental implants in patients undergoing bisphosphonate treatment.

    PubMed

    Kwon, Tae-Geon; Lee, Chung-O; Park, Jin-Woo; Choi, So-Young; Rijal, Girdhari; Shin, Hong-In

    2014-05-01

    Bisphosphonate-related jaw necrosis (BRONJ) associated with dental implants is a rare but continuously reported complication. To verify clinical and pathological characteristics of BRONJ around dental implants, the present study analyzed clinical, radiographic and histopathological findings of these lesions. Nineteen patients were diagnosed with osteonecrosis of the jaw associated with dental implants and treated at our institute from 2008 to 2011. The patients' medical history, demographic features, radiographic, and histopathological findings along with information on bisphosphonates (BP) administration were analyzed. The majority of BRONJ patients associated with dental implants used oral BP for osteoporosis. The patients were divided into two groups: BP initiation before (n = 16) and after (n = 3) implant surgery. Only three patients (15.8%) could be regarded as "implant surgery-triggered" BRONJ. Many patients (n = 9) showed successful osteointegration after fixture installation to an average of 35 months (11-82 months) until the development of osteonecrosis. The histological features of the lesion showed that the necrotic bone with empty lacunae was infiltrated by inflammatory cells and bacterial colonies. Viable osteocytes were also observed in some areas of the bony specimens. Three types of bone destruction pattern were observed: (i) complete necrosis of the bone around the implant (frozen type), (ii) extensive osteolysis around the implant with or without sequestra (osteolytic type), and (iii) sequestration of bone with an implant maintaining direct implant-bone contact (en block sequestration type). These findings could be existed at the same lesions depending on the degree of local bone destruction and the severity of the infection. These results and those of others suggested that already osseointegrated dental implants can also cause the osteonecrosis around the implant after BP administration. En block sequestration of bone with implant might be one of

  1. Safety of magnetic resonance imaging of patients with a new Medtronic EnRhythm MRI SureScan pacing system: clinical study design

    PubMed Central

    Sutton, Richard; Kanal, Emanuel; Wilkoff, Bruce L; Bello, David; Luechinger, Roger; Jenniskens, Inge; Hull, Michael; Sommer, Torsten

    2008-01-01

    Background Magnetic Resonance Imaging (MRI) of patients with implanted cardiac devices is currently considered hazardous due to potential for electromagnetic interference to the patient and pacemaker system. With approximately 60 million MRI scans performed worldwide per year, an estimated majority of pacemaker patients may develop an indication for an MRI during the lifetime of their pacemakers, suggesting that safe use of pacemakers in the MRI environment would be clinically valuable. A new pacing system (Medtronic EnRhythm MRI™ SureScan™ and CapSureFix MRI™ leads) has been designed and pre-clinically tested for safe use in the MRI environment. The EnRhythm MRI study is designed to confirm the safety and efficacy of this new pacing system. Methods The EnRhythm MRI study is a prospective, randomized controlled, unblinded clinical trial to confirm the safety and efficacy of MRI at 1.5 Tesla in patients implanted with a specifically designed pacemaker and lead system. The patients have standard indications for dual chamber pacemaker implantation. Successfully implanted patients are randomized in a 2:1 ratio to undergo MRI (MRI group) or to have no MRI scan (control group) at 9–12 weeks after pacemaker system implantation. Magnetic resonance (MR) scanning includes 14 head and lumbar scan sequences representing clinically relevant scans while maximizing the gradient slew rate up to 200 T/m/s, and/or the transmitted radiofrequency (RF) power up to SAR (specific absorption rate) levels of 2 W/kg body weight (upper limit of normal operating mode). Full interrogation of all device information and sensing and capture function are measured at device implantation, every follow-up and before and immediately after MRI in the MRI group and at the same time points in the control group. Complete pacemaker and lead evaluations are also done at one week and one month after the scan for the MRI and control group patients. The primary endpoint is safe and successful

  2. Multidimensional diffusion MRI

    NASA Astrophysics Data System (ADS)

    Topgaard, Daniel

    2017-02-01

    Principles from multidimensional NMR spectroscopy, and in particular solid-state NMR, have recently been transferred to the field of diffusion MRI, offering non-invasive characterization of heterogeneous anisotropic materials, such as the human brain, at an unprecedented level of detail. Here we revisit the basic physics of solid-state NMR and diffusion MRI to pinpoint the origin of the somewhat unexpected analogy between the two fields, and provide an overview of current diffusion MRI acquisition protocols and data analysis methods to quantify the composition of heterogeneous materials in terms of diffusion tensor distributions with size, shape, and orientation dimensions. While the most advanced methods allow estimation of the complete multidimensional distributions, simpler methods focus on various projections onto lower-dimensional spaces as well as determination of means and variances rather than actual distributions. Even the less advanced methods provide simple and intuitive scalar parameters that are directly related to microstructural features that can be observed in optical microscopy images, e.g. average cell eccentricity, variance of cell density, and orientational order - properties that are inextricably entangled in conventional diffusion MRI. Key to disentangling all these microstructural features is MRI signal acquisition combining isotropic and directional dimensions, just as in the field of multidimensional solid-state NMR from which most of the ideas for the new methods are derived.

  3. Hypersensitivity to biomedical implants: Prevention and diagnosis.

    PubMed

    Rosner, Gregory A; Fonacier, Luz S

    2017-05-01

    There has been growing interest in the potential for adverse immunologic reactions to metals in biomedical devices and increasing referrals for the evaluation and management of metal hypersensitivity reactions reported in orthopedic, cardiac, gynecologic, and dental implant devices. However, there are few studies that give evidence-based recommendations on how to evaluate this issue in our practices. We reviewed reasonable evidence and expert opinion on biomedical device hypersensitivity and published guidelines on pre- and postimplantation evaluation of delayed hypersensitivity reactions in patients suspected of possible metal hypersensitivity to biomedical devices. There is consensus that routine preimplantation evaluation in individuals with no history of adverse cutaneous reactions to metals or a history of implant-related adverse events is not necessary. However, patients with a history of metal hypersensitivity of a magnitude sufficient to cause concern for the patient or health care provider may benefit from evaluation by patch testing (PT) before device implantation. Patients after implantation and with chronic unexplained implant failure or with dermatitis may benefit from patch test evaluation after other causes, such as infection and biomechanical issues, are ruled out. However, a positive metal patch test result does not prove symptom causality, and the decision regarding implant revision can only be made after a thorough discussion among the patient, the allergist or dermatologist, and the orthopedic surgeon. Consensus guidelines for the evaluation of hypersensitivity to biomedical devices can be used by the practicing physician while awaiting for the results of further investigations.

  4. A Ballistics Examination of Firearm Injuries Involving Breast Implants.

    PubMed

    Pannucci, Christopher J; Cyr, Adam J; Moores, Neal G; Young, Jason B; Szegedi, Martin

    2017-07-06

    This ballistics study examines whether saline breast implants can decrease tissue penetration in firearm injuries. We hypothesize that the fluid column within a saline breast implant can alter bullet velocity and/or bullet pattern of mushrooming. The two experimental groups included saline implants with 7.4 cm projection and a no implant group. The experimental design allowed the bullet to pass-through an implant and into ballistics gel (n = 10) or into ballistics gel without passage through an implant (n = 11). Shots that passed through an implant had 20.6% decreased penetration distance when compared to shots that did not pass-through an implant; this difference was statistically significant (31.9 cm vs. 40.2 cm, p < 0.001). Implant group bullets mushroomed prior to gel entry, but the no implant group mushroomed within the gel. Bullet passage through a saline breast implant results in direct bullet velocity reduction and earlier bullet mushrooming; this causes significantly decreased ballistics gel penetration. © 2017 American Academy of Forensic Sciences.

  5. Allergic or Hypersensitivity Reactions to Orthopaedic Implants.

    PubMed

    Roberts, Timothy T; Haines, Colin M; Uhl, Richard L

    2017-10-01

    Allergic or hypersensitivity reactions to orthopaedic implants can pose diagnostic and therapeutic challenges. Although 10% to 15% of the population exhibits cutaneous sensitivity to metals, deep-tissue reactions to metal implants are comparatively rare. Nevertheless, the link between cutaneous sensitivity and clinically relevant deep-tissue reactions is unclear. Most reactions to orthopaedic devices are type IV, or delayed-type hypersensitivity reactions. The most commonly implicated allergens are nickel, cobalt, and chromium; however, reactions to nonmetal compounds, such as polymethyl methacrylate, antibiotic spacers, and suture materials, have also been reported. Symptoms of hypersensitivity to implants are nonspecific and include pain, swelling, stiffness, and localized skin reactions. Following arthroplasty, internal fixation, or implantation of similarly allergenic devices, the persistence or early reappearance of inflammatory symptoms should raise suspicions for hypersensitivity. However, hypersensitivity is a diagnosis of exclusion. Infection, as well as aseptic loosening, particulate synovitis, instability, and other causes of failure must first be eliminated.

  6. [Bone Conduction and Active Middle Ear Implants].

    PubMed

    Volkenstein, S; Thomas, J P; Dazert, S

    2016-05-01

    The majority of patients with moderate to severe hearing loss can be supplied with conventional hearing aids depending on severity and cause for hearing loss in a satisfying way. However, some patients either do not benefit enough from conventional hearing aids or cannot wear them due to inflammatory reactions and chronic infections of the external auditory canal or due to anatomical reasons. For these patients there are fully- and semi-implantable middle ear and bone conduction implants available. These devices either directly stimulate the skull (bone conduction devices), middle ear structures (active middle ear implants) or the cochlea itself (direct acoustic stimulation). Patients who failed surgical hearing rehabilitation or do not benefit from conventional hearing aids may achieve a significant better speech understanding and tremendous improvement in quality of life by implantable hearing devices with careful attention to the audiological and anatomical indication criteria. © Georg Thieme Verlag KG Stuttgart · New York.

  7. Very low and broad threshold voltage fluctuation caused by ion implantation to silicon-on-insulator triple-gate fin-type field effect transistor using three-dimensional process and device simulations

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Toshiyuki

    2017-06-01

    The threshold voltage (V th) fluctuation induced by the ion implantation to the source and drain extensions (SDE) of a silicon-on-insulator (SOI) triple-gate (tri-gate) fin-type field-effect transistor (FinFET) was analyzed for the first time with the use of realistic positional information of discretely doped ions by both three-dimensional (3D) process and device simulations. Interestingly, it was found that the V th fluctuation induced by SDE ion implantation has a very low and broad distribution on the low-V th side even in the case of a robust device structure such as SOI tri-gate FinFET. Furthermore, for the first time, it was quantitatively demonstrated using a proposed cluster percolation model that the origin of the very low and broad V th fluctuation is the conductive percolation among unintentionally doped ions in the channel region of the device. These results would contribute to the realization of robust transistors.

  8. Ultra-low field MRI: bringing MRI to new arenas

    DOE PAGES

    Magnelind, Per Erik; Matlashov, Andrei Nikolaevich; Newman, Shaun Garrett; ...

    2016-11-01

    Conventional magnetic resonance imaging (MRI) is moving toward the use of stronger and stronger magnetic fields with 3T, and even 7 T systems being increasingly used in routine clinical applications. However there is another branch of MRI, namely Ultra Low Field MRI (ULF-MRI) where the magnetic fields during readout are several orders of magnitude smaller, namely 1–100 μT. While conventional high-field MRI remains the gold standard there are several situations such as in military emergencies or in developing countries where for cost and logistical reasons, conventional MRI is not practical. In such scenarios, ULF-MRI could provide a solution. Lastly, thismore » article describes the basic principles and the potential of ULF-MRI.« less

  9. Ultra-low field MRI: bringing MRI to new arenas

    SciTech Connect

    Magnelind, Per Erik; Matlashov, Andrei Nikolaevich; Newman, Shaun Garrett; Sandin, Henrik; Urbaitis, Algis V.; Volegov, Petr Lvovich; Espy, Michelle A.

    2016-11-01

    Conventional magnetic resonance imaging (MRI) is moving toward the use of stronger and stronger magnetic fields with 3T, and even 7 T systems being increasingly used in routine clinical applications. However there is another branch of MRI, namely Ultra Low Field MRI (ULF-MRI) where the magnetic fields during readout are several orders of magnitude smaller, namely 1–100 μT. While conventional high-field MRI remains the gold standard there are several situations such as in military emergencies or in developing countries where for cost and logistical reasons, conventional MRI is not practical. In such scenarios, ULF-MRI could provide a solution. Lastly, this article describes the basic principles and the potential of ULF-MRI.

  10. Peri-implantitis and late implant failures in postmenopausal women: a cross-sectional study.

    PubMed

    Dvorak, Gabriella; Arnhart, Christoph; Heuberer, Simone; Huber, Christian D; Watzek, Georg; Gruber, Reinhard

    2011-10-01

    Systemic bone loss is a major cause of fractures in postmenopausal women and may also affect the jawbone; however, its consequences on the success of dental implants remain poorly understood. In this cross-sectional study, the relation between self-reported osteoporosis and the success rate of dental implants in an adult female population was evaluated. The primary outcome parameters were the occurrence of peri-implantitis and late implant failures. Women with unknown bone status were excluded from the study. The potential confounders age, recipient site, smoking, periodontal disease and time of loading were recorded. Data from 203 women with a mean age of 63 ± 9 years and 967 dental implants were investigated. The patients were classified according to their medical history into one of three groups: osteoporosis (47 women), osteopenia (16 women) and healthy controls (140 women). Patients with unknown bone status (n=26) were excluded. The multi-level statistical analysis showed no association between peri-implantitis [odds ratio (OR) 2.1; p=0.6] or implant failure [hazards ratio (HR) 2.5; p=0.2] and systemic bone loss. No relation was found between osteoporosis and peri-implantitis in an adult female population. © 2011 John Wiley & Sons A/S.

  11. Economic Analysis of Screening Strategies for Rupture of Silicone Gel Breast Implants

    PubMed Central

    Chung, Kevin C.; Malay, Sunitha; Shauver, Melissa J.; Kim, H. Myra

    2012-01-01

    Background In 2006, the U.S. Food and Drug Administration (FDA) recommended screening of all women with silicone gel breast implants with magnetic resonance imaging (MRI) three years after implantation and every two years thereafter to assess their integrity. The cost for these serial examinations over the lifetime of the breast implants is an added burden to insurance payers and to women. We perform an economic analysis to determine the most optimal screening strategies by considering the diagnostic accuracy of the screening tests, the costs of the tests and subsequent implant removal. Methods We determined aggregate/pooled values for sensitivity and specificity of the screening tests ultrasound (US) and MRI in detecting silicone breast implant ruptures from the data obtained from published literature. We compiled costs, based on Medicare reimbursements for 2011, for the following elements: imaging modalities, anesthesia and 3 surgical treatment options for detected ruptures. We used decision tree to compare three alternate screening strategies of US only, MRI only and US followed by MRI in asymptomatic and symptomatic women. Results The cost per rupture of screening and management of rupture with US in asymptomatic women was $1,090, whereas in symptomatic women it was $1,622. Similar cost for MRI in asymptomatic women was $2,067, whereas in symptomatic women it was $2,143. Similar cost for US followed by MRI in asymptomatic women was $637, whereas in symptomatic women it was $2,908. Conclusion Screening with US followed by MRI was optimal for asymptomatic women and screening with US was optimal for symptomatic women. PMID:22743887

  12. Transapical sutureless aortic valve implantation under magnetic resonance imaging guidance: Acute and short-term results.

    PubMed

    Horvath, Keith A; Mazilu, Dumitru; Cai, Junfeng; Kindzelski, Bogdan; Li, Ming

    2015-04-01

    Despite the increasing success and applicability of transcatheter aortic valve replacement, 2 critical issues remain: the durability of the valves, and the ideal imaging to aid implantation. This study was designed to investigate the transapical implantation of a device of known durability using real-time magnetic resonance imaging (MRI) guidance. A sutureless aortic valve was used that employs a self-expanding nitinol stent and is amenable to transapical delivery. MRI (1.5-T) was used to identify the anatomic landmarks in 60-kg Yucatan swine. Prostheses were loaded into an MRI-compatible delivery device with an active guidewire to enhance visualization. A series of acute feasibility experiments were conducted (n = 10). Additional animals (n = 6) were allowed to survive and had follow-up MRI scans and echocardiography at 90 days postoperatively. Postmortem gross examination was performed. The valve was MRI compatible and created no significant MRI artifacts. The 3 commissural struts were visible on short-axis view; therefore, coronary ostia obstruction was easily avoided. The average implantation time was 65 seconds. Final results demonstrated stability of the implants with preservation of myocardial perfusion and function over 90 days: the ejection fraction was 48% ± 15%; the peak gradient was 17.3 ± 11.3 mm Hg; the mean gradient was 9.8 ± 7.2 mm Hg. Mild aortic regurgitation was seen in 4 cases, trace in 1 case, and a severe central jet in 1 case. Prosthesis positioning was evaluated during gross examination. We demonstrated that a sutureless aortic valve can be safely and expeditiously implanted through a transapical approach under real-time MRI guidance. Postimplantation results showed a well-functioning prosthesis, with minimal regurgitation, and stability over time. Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

  13. Radiotherapy Planning using MRI

    PubMed Central

    Schmidt, Maria A; Payne, Geoffrey S

    2016-01-01

    The use of Magnetic Resonance Imaging (MRI) in Radiotherapy (RT) planning is rapidly expanding. We review the wide range of image contrast mechanisms available to MRI and the way they are exploited for RT planning. However a number of challenges are also considered: the requirements that MR images are acquired in the RT treatment position, that they are geometrically accurate, that effects of patient motion during the scan are minimised, that tissue markers are clearly demonstrated, that an estimate of electron density can be obtained. These issues are discussed in detail, prior to the consideration of a number of specific clinical applications. This is followed by a brief discussion on the development of real-time MRI-guided RT. PMID:26509844

  14. Performance of Cochlear Implant Recipients With GJB2-Related Deafness

    PubMed Central

    Green, Glenn E.; Scott, Daryl A.; McDonald, Joshua M.; Teagle, Holly F.B.; Tomblin, Bruce J.; Spencer, Linda J.; Woodworth, George G.; Knutson, John F.; Gantz, Bruce J.; Sheffield, Val C.; Smith, Richard J.H.

    2011-01-01

    Congenital profound hearing loss affects 0.05–0.1% of children and has many causes, some of which are associated with cognitive delay. For prelingually-deafened cochlear implant recipients, the etiology of deafness is usually unknown. Mutations in GJB2 have been established as the most common cause of heritable deafness in the United States. In this report, we identify cochlear implant recipients with GJB2-related deafness and examine the performance of these individuals. Cochlear implant recipients received a battery of perceptive, cognitive, and reading tests. Neither subjects nor examiners knew the etiology of deafness in these individuals. The implant recipients were then examined for mutations in GJB2 using an allele-specific polymerase chain reaction assay, single-strand conformation polymorphism analysis, and direct sequencing. GJB2 mutations were the leading cause of congenital deafness among the cochlear implant recipients screened. Cochlear implant recipients with GJB2-related deafness read within one standard deviation of hearing controls better than other congenitally deaf cochlear implant recipients and non-cochlear implant recipients. Individuals with congenital deafness should be offered GJB2 screening. Positive results establish an etiologic diagnosis and provide prognostic, genetic, and therapeutic information. Effective rehabilitation for profoundly deaf individuals with GJB2-related deafness is possible through cochlear implantation. PMID:11977173

  15. Influences of microgap and micromotion of implant-abutment interface on marginal bone loss around implant neck.

    PubMed

    Liu, Yang; Wang, Jiawei

    2017-11-01

    To review the influences and clinical implications of micro-gap and micro-motion of implant-abutment interface on marginal bone loss around the neck of implant. Literatures were searched based on the following Keywords: implant-abutment interface/implant-abutment connection/implant-abutment conjunction, microgap, micromotion/micromovement, microleakage, and current control methods available. The papers were then screened through titles, abstracts, and full texts. A total of 83 studies were included in the literature review. Two-piece implant systems are widely used in clinics. However, the production error and masticatory load result in the presence of microgap and micromotion between the implant and the abutment, which directly or indirectly causes microleakage and mechanical damage. Consequently, the degrees of microgap and micromotion further increase, and marginal bone absorption finally occurs. We summarize the influences of microgap and micromotion at the implant-abutment interface on marginal bone loss around the neck of the implant. We also recommend some feasible methods to reduce their effect. Clinicians and patients should pay more attention to the mechanisms as well as the control methods of microgap and micromotion. To reduce the corresponding detriment to the implant marginal bone, suitable Morse taper or hybrid connection implants and platform switching abutments should be selected, as well as other potential methods. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. [Cochlear implant in adults].

    PubMed

    Bouccara, D; Mosnier, I; Bernardeschi, D; Ferrary, E; Sterkers, O

    2012-03-01

    Cochlear implant in adults is a procedure, dedicated to rehabilitate severe to profound hearing loss. Because of technological progresses and their applications for signal strategies, new devices can improve hearing, even in noise conditions. Binaural stimulation, cochlear implant and hearing aid or bilateral cochlear implants are the best opportunities to access to better level of comprehension in all conditions and space localisation. By now minimally invasive surgery is possible to preserve residual hearing and use a double stimulation modality for the same ear: electrical for high frequencies and acoustic for low frequencies. In several conditions, cochlear implant is not possible due to cochlear nerve tumour or major malformations of the inner ear. In these cases, a brainstem implantation can be considered. Clinical data demonstrate that improvement in daily communication, for both cochlear and brainstem implants, is correlated with cerebral activation of auditory cortex.

  17. A unique association of arrhythmogenic right ventricular dysplasia and acute myocarditis, as assessed by cardiac MRI: a case report.

    PubMed

    Ponsiglione, Andrea; Puglia, Marta; Morisco, Carmine; Barbuto, Luigi; Rapacciuolo, Antonio; Santoro, Mario; Spinelli, Letizia; Trimarco, Bruno; Cuocolo, Alberto; Imbriaco, Massimo

    2016-11-21

    Arrhythmogenic right ventricular dysplasia (ARVD), is a genetic disorder of the heart, which mainly involves the right ventricle. It is characterized by hypokinetic areas at the free wall of the right ventricle (RV) or both ventricles, where myocardium is replaced by fibrous or fatty tissue. ARVD is an important cause of ventricular arrhythmias in children and young adults. Although the transmission of the disease is based on hereditary, in young adults it may not show any symptoms. The main differential diagnoses with other frequent etiological causes of sudden arrhythmia are: idiopathic outflow tract ventricular tachycardia of the RV, myocarditis, dilated cardiomyopathy and sarcoidosis. We describe an unusual case of a 44-year-old woman who was hospitalized for ventricular tachycardia, deep asthenia and dyspnoea with no previous history of cardiac disease. The patient had a ten-year history of palpitations, which started immediately after her last pregnancy. She was diagnosed with both acute/subacute viral myocarditis and arrhythmogenic right ventricular dysplasia, based on established clinical and cardiac MRI criteria. After the diagnosis the patient received an automatic implantable cardioverter defibrillator. Currently, she is on clinical follow-up with no apparent further complications. Analyzing this rare case, we have shown the link between myocarditis and arrhythmogenic right ventricular dysplasia, and how important is to perform a cardiac MRI, in the context of acute myocarditis and ventricular arrhythmia.

  18. Implant treatment planning considerations.

    PubMed

    Kao, Richard T

    2008-04-01

    As dental implants become a more accepted treatment modality, there is a need for all parties involved with implant dentistry to be familiar with various treatment planning issues. Though the success can be highly rewarding, failure to forecast treatment planning issues can result in an increase of surgical needs, surgical cost, and even case failure. In this issue, the focus is on implant treatment planning considerations.

  19. Incorporating MRI structural information into bioluminescence tomography: system, heterogeneous reconstruction and in vivo quantification

    PubMed Central

    Zhang, Jun; Chen, Duofang; Liang, Jimin; Xue, Huadan; Lei, Jing; Wang, Qin; Chen, Dongmei; Meng, Ming; Jin, Zhengyu; Tian, Jie

    2014-01-01

    Combining two or more imaging modalities to provide complementary information has become commonplace in clinical practice and in preclinical and basic biomedical research. By incorporating the structural information provided by computed tomography (CT) or magnetic resonance imaging (MRI), the ill poseness nature of bioluminescence tomography (BLT) can be reduced significantly, thus improve the accuracies of reconstruction and in vivo quantification. In this paper, we present a small animal imaging system combining multi-view and multi-spectral BLT with MRI. The independent MRI-compatible optical device is placed at the end of the clinical MRI scanner. The small animal is transferred between the light tight chamber of the optical device and the animal coil of MRI via a guide rail during the experiment. After the optical imaging and MRI scanning procedures are finished, the optical images are mapped onto the MRI surface by interactive registration between boundary of optical images and silhouette of MRI. Then, incorporating the MRI structural information, a heterogeneous reconstruction algorithm based on finite element method (FEM) with L 1 normalization is used to reconstruct the position, power and region of the light source. In order to validate the feasibility of the system, we conducted experiments of nude mice model implanted with artificial light source and quantitative analysis of tumor inoculation model with MDA-231-GFP-luc. Preliminary results suggest the feasibility and effectiveness of the prototype system. PMID:24940545

  20. Long-term clinical effects of magnetic resonance imaging in patients with coronary artery stent implantation.

    PubMed

    Kaya, Mehmet Gungor; Okyay, Kaan; Yazici, Huseyin; Sen, Nihat; Tavil, Yusuf; Turkoglu, Sedat; Timurkaynak, Timur; Ozdemir, Murat; Cemri, Mustafa; Yalcin, Ridvan; Cengel, Atiye

    2009-03-01

    We sought to investigate the early and late effects of magnetic resonance imaging (MRI) on stent thrombosis and major adverse coronary events after coronary artery stent (CAS) implantation at a long-term follow-up period. Forty-three patients (28 men, mean age 63+/-10 years) who underwent CAS implantation before MRI examination were included. MRI was performed on a 1.5-T MR-system with a phased array multicoil. An average of 1.3 stents per patient were implanted (1-4 stents). More than one MRI was performed for two patients. Patients who underwent MRI within 8 weeks after the procedure were included in the early-term group (17 patients), and those who underwent MRI after 8 weeks were included in the late-term group (26 patients). Mean follow-up period was 36+/-15 months. There was no acute or subacute stent thrombosis. Late stent thrombosis that resulted in acute myocardial infarction was observed in a patient from the early group after an operation for prostate hyperplasia 5 months after MRI, and the patient underwent percutaneous coronary artery angioplasty. De-nova lesion was observed in four patients in the early group and two patients in the late group (P=0.14). In-stent restenosis was recorded in two patients in the early group and three patients in the late group (P=0.98). Composite major adverse cardiac events (acute coronary syndrome, myocardial infarction, death, and cerebrovascular event) were observed in seven of the early-group patients (41%), and in six of the late-group patients (23%) (P=0.20). MRI can be safely performed in patients with CAS implantation both in the early and late course, and is not associated with an increased risk of major adverse clinical cardiac events at long-term follow-up.

  1. The reversed internal magnet of cochlear implant after magnetic resonance imaging.

    PubMed

    Kong, Soo-Keun; Oh, Se-Joon; Lee, Il-Woo; Goh, Eui-Kyung

    2014-01-01

    Cochlear implants (CI) have now become a standard method of treating severe to profound hearing loss. Recently, the number of patients with CI has been rapidly increasing as the big benefits of CI become more widely known. Magnetic resonance imaging (MRI) has also become a routine diagnostic imaging modality, used in the diagnosis of common conditions, including stroke, back pain, and headache. We report our recent experience with a case in which internal magnet of the cochlear implant was reversed after 1.5-T lumbar spine MRI. This complication is managed successfully by reversing the orientation of the external magnet in the head coil.

  2. Comparative analysis of changes in MR imaging of pre and post intrauterine progesterone implants in adenomyosis cases

    PubMed Central

    Dashottar, S.; Singh, A.K.; Debnath, J.; Muralidharan, C.G.; Singh, R.K.; Kumar, Suman

    2015-01-01

    Background Magnetic Resonance Imaging (MRI) plays an important role in the evaluation and management of adenomyosis. In this study, we first diagnosed the adenomyosis on MRI and then we analyzed the MRI changes in the uterus in pre and post intrauterine progesterone implants cases. Method All the patients with clinical diagnosis of menorrhagia or dysmenorrhea were screened by Ultrasonography (USG) of the pelvis. Patients with heterogeneous echo texture of the uterus were then evaluated by the MRI of the pelvis. All patients with MRI findings suggestive of adenomyosis formed the study group. Result On MRI study 60 patients were diagnosed as adenomyosis, 68.33% had diffuse adenomyosis and 31.66% had focal adenomyosis. 83% of diagnosed adenomyosis cases had high intensity signal foci which were seen in 75% cases of diffuse adenomyosis and 100% cases of focal adenomyosis. 50 diagnosed adenomyosis cases were then reviewed after 03 months, 06 months and 12 months to see for any change in the MRI findings in the post intrauterine implant cases. On follow up MRI after post progesterone intrauterine implant, 50% of the cases showed reduction in the high intensity signals, 10% of the cases showed mild reduction in the junctional zone thickness with no significant change in the uterine size. Conclusions It is inferred that MR imaging is not only helpful in diagnosing but also helpful in monitoring the effects of hormonal therapy in adenomyosis. PMID:25859077

  3. Osseointegrated implant prosthodontics.

    PubMed

    Rogoff, G S

    1992-06-01

    This review covers recent literature on prosthodontic aspects of osseointegrated implants. Long-term prognosis, diagnosis and treatment planning, and clinical impression techniques and fabrication technology are discussed.

  4. [Silastic implant and synovitis].

    PubMed

    Sennwald, G

    1989-07-22

    The silastic implant based on siloxane polymere induces granulomatous synovitis in certain predisposed individuals, a reaction which may continue even after removal of the implant. This is also true of a prosthesis of the trapezium in two of our patients, though to a lesser degree. This is probably the reason why the problem has not yet been widely recognized. The hypothesis is put forward that an enzymatic predisposition may allow chemical degradation of the fragmented silastic implant into a toxic component responsible for the pathologic condition. The slow progression of the lesions is a challenge for the future and puts in question the further use of silastic implants.

  5. Magnetic Resonance Imaging (MRI) Safety

    MedlinePlus

    ... Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) Safety What is MRI and how does ... the area being scanned include: Metallic spinal rod Plates, pins, screws, or metal mesh used to repair ...

  6. 21 CFR 882.5860 - Implanted neuromuscular stimulator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... neuromuscular stimulator. (a) Identification. An implanted neuromuscular stimulator is a device that provides electrical stimulation to a patient's peroneal or femoral nerve to cause muscles in the leg to contract, thus... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Implanted neuromuscular stimulator....

  7. Dynamic lumbar spinal stenosis : the usefulness of axial loaded MRI in preoperative evaluation.

    PubMed

    Choi, Kyung-Chul; Kim, Jin-Sung; Jung, Byungjoo; Lee, Sang-Ho

    2009-09-01

    Two cases of dynamic lumbar spinal stenosis were identified by the authors using axial loaded magnetic resonance image (MRI). In both cases, the patients presented with neurogenic claudication but MRI in decumbency showed no definite pathologic condition associated with their symptoms. In contrast, axial loaded MRI demonstrated constrictive spinal stenosis and a significantly decreased dural sac caused by epidural fat buckling and thickening of the ligamentum flavum in both cases. In the second case, a more prominent disc protrusion was also demonstrated compared with decumbent MRI. After decompressive surgery, both patients had satisfactory outcomes. Axial loaded MRI can therefore give decisive information in dynamic spinal disorders by allowing simulation of an upright position.

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

    PubMed

    Lindegaard, Jacob Christian; Madsen, Mikkel Lænsø; Traberg, Anders; Meisner, Bjarne; Nielsen, Søren Kynde; Tanderup, Kari; Spejlborg, Harald; Fokdal, Lars Ulrik; Nørrevang, Ole

    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 and exemplified by a stage IVA cervical cancer with superior dose distribution.

  9. Muscle atrophy and metal-on-metal hip implants

    PubMed Central

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

    2015-01-01

    Background and purpose 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. Patients and methods 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. Results 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). Interpretation 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. PMID:25588091

  10. MRI of intact plants.

    PubMed

    Van As, Henk; Scheenen, Tom; Vergeldt, Frank J

    2009-01-01

    Nuclear magnetic resonance imaging (MRI) is a non-destructive and non-invasive technique that can be used to acquire two- or even three-dimensional images of intact plants. The information within the images can be manipulated and used to study the dynamics of plant water relations and water transport in the stem, e.g., as a function of environmental (stress) conditions. Non-spatially resolved portable NMR is becoming available to study leaf water content and distribution of water in different (sub-cellular) compartments. These parameters directly relate to stomatal water conductance, CO(2) uptake, and photosynthesis. MRI applied on plants is not a straight forward extension of the methods discussed for (bio)medical MRI. This educational review explains the basic physical principles of plant MRI, with a focus on the spatial resolution, factors that determine the spatial resolution, and its unique information for applications in plant water relations that directly relate to plant photosynthetic activity. © Springer Science+Business Media B.V. 2009

  11. Contrast agents for MRI.

    PubMed

    Shokrollahi, H

    2013-12-01

    Contrast agents are divided into two categories. The first one is paramagnetic compounds, including lanthanides like gadolinium, which mainly reduce the longitudinal (T1) relaxation property and result in a brighter signal. The second class consists of super-paramagnetic magnetic nanoparticles (SPMNPs) such as iron oxides, which have a strong effect on the transversal (T2) relaxation properties. SPMNPs have the potential to be utilized as excellent probes for magnetic resonance imaging (MRI). For instance, clinically benign iron oxide and engineered ferrite nanoparticles provide a good MRI probing capability for clinical applications. Furthermore, the limited magnetic property and inability to escape from the reticuloendothelial system (RES) of the used nanoparticles impede their further advancement. Therefore, it is necessary to develop the engineered magnetic nanoparticle probes for the next-generation molecular MRI. Considering the importance of MRI in diagnosing diseases, this paper presents an overview of recent scientific achievements in the development of new synthetic SPMNP probes whereby the sensitive and target-specific observation of biological events at the molecular and cellular levels is feasible.

  12. Biocompatible implants and methods of making and attaching the same

    DOEpatents

    Rowley, Adrian P; Laude, Lucien D; Humayun, Mark S; Weiland, James D; Lotfi, Atoosa; Markland, Jr., Francis S

    2014-10-07

    The invention provides a biocompatible silicone implant that can be securely affixed to living tissue through interaction with integral membrane proteins (integrins). A silicone article containing a laser-activated surface is utilized to make the implant. One example is an implantable prosthesis to treat blindness caused by outer retinal degenerative diseases. The device bypasses damaged photoreceptors and electrically stimulates the undamaged neurons of the retina. Electrical stimulation is achieved using a silicone microelectrode array (MEA). A safe, protein adhesive is used in attaching the MEA to the retinal surface and assist in alleviating focal pressure effects. Methods of making and attaching such implants are also provided.

  13. Peri-implant diseases: Consensus Report of the Sixth European Workshop on Periodontology.

    PubMed

    Lindhe, Jan; Meyle, Joerg

    2008-09-01

    Issues related to peri-implant disease were discussed. It was observed that the most common lesions that occur, i.e. peri-implant mucositis and peri-implantitis are caused by bacteria. While the lesion of peri-implant mucositis resides in the soft tissues, peri-implantitis also affects the supporting bone. Peri-implant mucositis occurs in about 80% of subjects (50% of sites) restored with implants, and peri-implantitis in between 28% and 56% of subjects (12-40% of sites). A number of risk indicators were identified including (i) poor oral hygiene, (ii) a history of periodontitis, (iii) diabetes and (iv) smoking. It was concluded that the treatment of peri-implant disease must include anti-infective measures. With respect to peri-implant mucositis, it appeared that non-surgical mechanical therapy caused the reduction in inflammation (bleeding on probing) but also that the adjunctive use of antimicrobial mouthrinses had a positive effect. It was agreed that the outcome of non-surgical treatment of peri-implantitis was unpredictable. The primary objective of surgical treatment in peri-implantitis is to get access to the implant surface for debridement and decontamination in order to achieve resolution of the inflammatory lesion. There was limited evidence that such treatment with the adjunctive use of systemic antibiotics could resolve a number of peri-implantitis lesions. There was no evidence that so-called regenerative procedures had additional beneficial effects on treatment outcome.

  14. Tolerance and Long-Term MRI Imaging of Gadolinium-Modified Meshes Used in Soft Organ Repair

    PubMed Central

    Letouzey, Vincent; Huberlant, Stéphanie; Cornille, Arnaud; Blanquer, Sébastien; Guillaume, Olivier; Lemaire, Laurent; Garric, Xavier; de Tayrac, Renaud

    2015-01-01

    Background Synthetic meshes are frequently used to reinforce soft tissues. The aim of this translational study is to evaluate tolerance and long-term MRI visibility of two recently developed Gadolinium-modified meshes in a rat animal model. Materials and Methods Gadolinium-poly-ε-caprolactone (Gd-PCL) and Gadolinium-polymethylacrylate (Gd-PMA) modified meshes were implanted in Wistar rats and their tolerance was assessed daily. Inflammation and biocompatibility of the implants were assessed by histology and immunohistochemistry after 30 days post implantation. Implants were visualised by 7T and 3T MRI at day 30 and at day 90. Diffusion of Gadolinium in the tissues of the implanted animals was assessed by Inductively Coupled Plasma Mass Spectrometry. Results Overall Gd-PMA coated implants were better tolerated as compared to those coated with Gd-PCL. In fact, Gd-PMA implants were characterised by a high ratio collagen I/III and good vascularisation of the integration tissues. High resolution images of the coated mesh were obtained in vivo with experimental 7T as well as 3T clinical MRI. Mass spectrometry analyses showed that levels of Gadolinium in animals implanted with coated mesh were similar to those of the control group. Conclusions Meshes coated with Gd-PMA are better tolerated as compared to those coated with Gd-PCL as no signs of erosion or significant inflammation were detected at 30 days post implantation. Also, Gd-PMA coated meshes were clearly visualised with both 7T and 3T MRI devices. This new technique of mesh optimisation may represent a valuable tool in soft tissue repair and management. PMID:25811855

  15. Acupressure magnets: a possible MRI hazard.

    PubMed

    Otjen, Jeffrey P; Mallon, Kara; Brown, Julie C

    2015-03-01

    The use of magnets as a component of complementary and alternative medicine is increasingly common. Magnet therapy is used to treat a variety of conditions and often involves tiny magnets adhered to the skin. In auriculotherapy, magnets are placed in specific locations of the ear pinnae which represent particular parts of the body. While generally considered safe, these magnets have the potential to cause imaging problems and serious injury during MRI. We report a case of auriculotherapy magnets which escaped detection despite the use of screening forms and a walk-through metal detector. The magnets caused image artifact but no other patient harm. We recommend updating patient screening practices and educating providers placing therapeutic magnets and performing MRIs of this new potential MRI hazard.

  16. Validation of CT-MRI fusion for intraoperative assessment of stereotactic accuracy in DBS surgery.

    PubMed

    Mirzadeh, Zaman; Chapple, Kristina; Lambert, Meg; Dhall, Rohit; Ponce, Francisco A

    2014-12-01

    Deep brain stimulation is typically performed with intraoperative microelectrode recording and test stimulation for target confirmation. Recent studies have shown accurate, clinically efficacious results after lead placement without microelectrode recording or test stimulation, using interventional magnetic resonance imaging (MRI) or intraoperative computed tomography (CT; iCT) for verification of accuracy. The latter relies on CT-MRI fusion. To validate CT-MRI fusion in this setting, we compared stereotactic coordinates determined intraoperatively using CT-MRI fusion with those obtained on postoperative MRI. Deep brain stimulation electrodes were implanted with patients under general anesthesia. Direct targeting was performed on preoperative MRI, which was merged with preimplantation iCT images for stereotactic registration and postimplantation iCT images for accuracy confirmation. Magnetic resonance imaging was obtained 6 weeks postoperatively for comparison. Postoperative MRI was obtained for 48 patients, with 94 leads placed over a 1-year period. Vector error of the targeted contact relative to the initial plan was 1.1 ± 0.7 mm on iCT and 1.6 ± 0.7 mm on postoperative MRI. Variance comparisons (F-tests) showed that the discrepancy between iCT- and postoperative MRI-determined errors was attributable to measurement error on postoperative MRI, as detected in inter-rater reliability testing. In multivariate analysis, improved lead placement accuracy was associated with frame-based stereotaxy with the head of the bed at 0° compared with frameless stereotaxy with the head of the bed at 30° (P = 0.037). Intraoperative CT can be used to determine lead placement accuracy in deep brain stimulation surgery. The discrepancy between coordinates determined intraoperatively by CT-MRI fusion and postoperatively by MRI can be accounted for by inherent measurement error. © 2014 International Parkinson and Movement Disorder Society.

  17. Assessment of corrosion in retrieved spine implants.

    PubMed

    Panagiotopoulou, V C; Hothi, H S; Anwar, H A; Molloy, S; Noordeen, H; Rezajooi, K; Sutcliffe, J; Skinner, J A; Hart, A J

    2017-03-09

    Recently the use of dissimilar metals in spine instrumentation has increased, especially in the case of adult deformities, where rods made from Cobalt Chrome alloys (CoCr) are used with Titanium (Ti) screws. The use of dissimilar metals increases the risk of galvanic corrosion and patients have required revision spine surgery due to severe metallosis that may have been caused by corrosion. We aimed to assess the presence of corrosion in spine implant retrievals from constructs with two types of material combinations: similar (Ti/Ti) and dissimilar (CoCr/Ti). First, we devised a grading score for corrosion of the rod-fixture junctions. Then, we applied this score to a collection of retrieved spine implants. Our proposed corrosion grading score was proven reliable (kappa > 0.7). We found no significant difference in the scores between 4 CoCr and 11 Ti rods (p = 0.0642). There was no indication that time of implantation had an effect on the corrosion score (p = 0.9361). We recommend surgeons avoid using implants designs with dissimilar metals to reduce the risk of corrosion whilst a larger scale study of retrieved spine implants is conducted. Future studies can now use our scoring system for spine implant corrosion. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017.

  18. Peri-implant infections of oral biofilm etiology.

    PubMed

    Belibasakis, Georgios N; Charalampakis, Georgios; Bostanci, Nagihan; Stadlinger, Bernd

    2015-01-01

    Biofilms are complex microbial communities that grow on various surfaces in nature. The oral micobiota tend to form polymicrobial biofilms, particularly on the hard mineralized surfaces of teeth, which may impact on oral health and disease. They can cause inflammation of the adjacent tooth-supporting (periodontal) tissues, leading to destructive periodontal disease and tooth loss. The emergence of osseointegrated dental implants as a restorative treatment option for replacing missing teeth has also brought along new artificial surfaces within the oral cavity, on which oral bacteria can form biofilms. As in the case of natural teeth, biofilms on implant surfaces may also trigger infection and cause inflammatory destruction of the peri-implant tissue (i.e. peri-implantitis). While there are strong similarities in the composition of the mixed microbial flora between periodontal and peri-implant infections, there are also a few distinctive differences. The immunological events underlying the pathogenesis of peri-implant infections are qualitatively similar, yet more extensive, compared to periodontal infections, resulting in a faster progression of tissue destruction. This chapter summarizes the current knowledge on the microbiology and immunology of peri-implant infections, including findings from the peri-implant crevicular fluid, the inflammatory exudate of the peri-implant tissue. Moreover, it discusses the diagnosis and current approaches for the treatment of oral infections.

  19. Impact of Surgical Template on the Accuracy of Implant Placement.

    PubMed

    Xu, Liang-Wei; You, Jia; Zhang, Jian-Xing; Liu, Yun-Feng; Peng, Wei

    2016-12-01

    To achieve functional and esthetic results, implants must be placed accurately; however, little information is available regarding the effect of surgical templates on the accuracy of implant placement. Thus, the aim of this study was to measure the deviation between actual and planned implant positions, and determine the deviation caused by the surgical template. Jaws from 16 patients were scanned using cone beam computed tomography (CBCT). For our study, 53 implants were planned in a virtual 3D environment, of which 35 were inserted in the mandible and 18 in the maxilla. A stereolithographic (SLA) surgical template was created. A CBCT scan of the surgical template fitted on a plaster model was performed, and the images obtained were matched to virtual implant plan images that contained the planned implant position. The actual implant position was acquired from the registration position of the surgical template. Deviation between actual and planned implant positions was analyzed. Mean central deviation at the hex and apex was 0.456 mm and 0.515 mm, respectively. Mean value of horizontal deviation at the hex was 0.193 mm, horizontal deviation at the apex was 0.277 mm, vertical deviation at the hex was 0.388 mm, vertical deviation at the apex was 0.390 mm, and angular deviation was 0.621°. Our study results revealed a significant deviation between actual and planned implant positions caused by the surgical template. © 2015 by the American College of Prosthodontists.

  20. Implantable ultrasound devices

    NASA Astrophysics Data System (ADS)

    Vilkomerson, David; Chilipka, Thomas; Bogan, John; Blebea, John; Choudry, Rashad; Wang, John; Salvatore, Michael; Rotella, Vittorio; Soundararajan, Krishnan

    2008-03-01

    Using medical implants to wirelessly report physiological data is a technique that is rapidly growing. Ultrasound is well-suited for implants -- it requires little power and this form of radiated energy has no ill effects on the body. We report here on techniques we have developed in our experience gained in implanting over a dozen Doppler ultrasound flow-measuring implants in dogs. The goal of our implantable device is to measure flow in an arterial graft. To accomplish this, we place a Doppler transducer in the wall of a graft and an implant unit under the skin that energizes the 20 MHz Doppler transducer system, either when started by external command or by internal timetable. The implant records the digitized Doppler real and imaginary channels and transmits the data to a nearby portable computer for storage and evaluation. After outlining the overall operation of the system, we will concentrate on three areas of implant design where special techniques are required: ensuring safety, including biocompatibility to prevent the body from reacting to its invasion; powering the device, including minimizing energy used so that a small battery can provide long-life; and transmitting the data obtained.

  1. Batteryless implanted echosonometer

    NASA Technical Reports Server (NTRS)

    Kojima, G. K.

    1977-01-01

    Miniature ultrasonic echosonometer implanted within laboratory animals obtains energy from RF power oscillator that is electronically transduced via induction loop to power receiving loop located just under animal's skin. Method of powering device offers significant advantages over those in which battery is part of implanted package.

  2. Implantable, Ingestible Electronic Thermometer

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard

    1987-01-01

    Small quartz-crystal-controlled oscillator swallowed or surgically implanted provides continuous monitoring of patient's internal temperature. Receiver placed near patient measures oscillator frequency, and temperature inferred from previously determined variation of frequency with temperature. Frequency of crystal-controlled oscillator varies with temperature. Circuit made very small and implanted or ingested to measure internal body temperature.

  3. Smoking and dental implants

    PubMed Central

    Kasat, V.; Ladda, R.

    2012-01-01

    Smoking is a prevalent behaviour in the population. The aim of this review is to bring to light the effects of smoking on dental implants. These facts will assist dental professionals when implants are planned in tobacco users. A search of “PubMed” was made with the key words “dental implant,” “nicotine,” “smoking,” “tobacco,” and “osseointegration.” Also, publications on tobacco control by the Government of India were considered. For review, only those articles published from 1988 onward in English language were selected. Smoking has its influence on general as well as oral health of an individual. Tobacco negatively affects the outcome of almost all therapeutic procedures performed in the oral cavity. The failure rate of implant osseointegration is considerably higher among smokers, and maintenance of oral hygiene around the implants and the risk of peri-implantitis are adversely affected by smoking. To increase implant survival in smokers, various protocols have been recommended. Although osseointegrated dental implants have become the state of the art for tooth replacement, they are not without limitations or complications. In this litigious era, it is extremely important that the practitioner clearly understands and is able and willing to convey the spectrum of possible complications and their frequency to the patients. PMID:24478965

  4. Batteryless implanted echosonometer

    NASA Technical Reports Server (NTRS)

    Kojima, G. K.

    1977-01-01

    Miniature ultrasonic echosonometer implanted within laboratory animals obtains energy from RF power oscillator that is electronically transduced via induction loop to power receiving loop located just under animal's skin. Method of powering device offers significant advantages over those in which battery is part of implanted package.

  5. Implantable CMOS Biomedical Devices

    PubMed Central

    Ohta, Jun; Tokuda, Takashi; Sasagawa, Kiyotaka; Noda, Toshihiko

    2009-01-01

    The results of recent research on our implantable CMOS biomedical devices are reviewed. Topics include retinal prosthesis devices and deep-brain implantation devices for small animals. Fundamental device structures and characteristics as well as in vivo experiments are presented. PMID:22291554

  6. Teeth and implants.

    PubMed

    Palmer, R

    1999-08-28

    An osseointegrated implant restoration may closely resemble a natural tooth. However, the absence of a periodontal ligament and connective tissue attachment via cementum, results in fundamental differences in the adaptation of the implant to occlusal forces, and the structure of the gingival cuff.

  7. NH2 + implantations induced superior hemocompatibility of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Guo, Meixian; Li, Dejun; Zhao, Mengli; Zhang, Yiteng; Deng, Xiangyun; Geng, Dongsheng; Li, Ruying; Sun, Xueliang; Gu, Hanqing; Wan, Rongxin

    2013-05-01

    NH2 + implantation was performed on multiwalled carbon nanotubes (MWCNTs) prepared by chemical vapor deposition. The hemocompatibility of MWCNTs and NH2 +-implanted MWCNTs was evaluated based on in vitro hemolysis, platelet adhesion, and kinetic-clotting tests. Compared with MWCNTs, NH2 +-implanted MWCNTs displayed more perfect platelets and red blood cells in morphology, lower platelet adhesion rate, lower hemolytic rate, and longer kinetic blood-clotting time. NH2 +-implanted MWCNTs with higher fluency of 1 × 1016 ions/cm2 led to the best thromboresistance, hence desired hemocompatibility. Fourier transfer infrared and X-ray photoelectron spectroscopy analyses showed that NH2 + implantation caused the cleavage of some pendants and the formation of some new N-containing functional groups. These results were responsible for the enhanced hemocompatibility of NH2 +-implanted MWCNTs.

  8. Percutaneous and skeletal biocarbon implants

    NASA Technical Reports Server (NTRS)

    Mooney, V.

    1977-01-01

    Review of carbon implants developed by NASA discussed four different types of implants and subsequent improvements. Improvements could be of specific interest to rehabilitation centers and similar organizations.

  9. Percutaneous and skeletal biocarbon implants

    NASA Technical Reports Server (NTRS)

    Mooney, V.

    1977-01-01

    Review of carbon implants developed by NASA discussed four different types of implants and subsequent improvements. Improvements could be of specific interest to rehabilitation centers and similar organizations.

  10. In vitro MRI of brain development.

    PubMed

    Rados, Marko; Judas, Milos; Kostović, Ivica

    2006-02-01

    In this review, we demonstrate the developmental appearance, structural features, and reorganization of transient cerebral zones and structures in the human fetal brain using a correlative histological and MRI analysis. The analysis of postmortem aldehyde-fixed specimens (age range: 10 postovulatory weeks to term) revealed that, at 10 postovulatory weeks, the cerebral wall already has a trilaminar appearance and consists of: (1) a ventricular zone of high cell-packing density; (2) an intermediate zone; (3) the cortical plate (in a stage of primary consolidation) with high MRI signal intensity. The anlage of the hippocampus is present as a prominent bulging in the thin limbic telencephalon. The early fetal telencephalon impar also contains the first commissural fibers and fornix bundles in the septal area. The ganglionic eminence is clearly visible as an expanded continuation of the proliferative ventricular zone. The basal ganglia showed an initial aggregation of cells. The most massive fiber system is in the hemispheric stalk, which is in continuity with thalamocortical fibers. During the mid-fetal period (15-22 postovulatory weeks), the typical fetal lamination pattern develops and the cerebral wall consists of the following zones: (a) a marginal zone (visible on MRI exclusively in the hippocampus); (b) the cortical plate with high cell-packing density and high MRI signal intensity; (c) the subplate zone, which is the most prominent zone rich in extracellular matrix and with a very low MRI signal intensity; (d) the intermediate zone (fetal "white matter"); (e) the subventricular zone; (f) the periventricular fiber-rich zone; (g) the ventricular zone. The ganglionic eminence is still a very prominent structure with an intense proliferative activity. During the next period (22-26 postovulatory weeks), there is the developmental peak of transient MRI features, caused by the high content of hydrophyllic extracellular matrix in the subplate zone and the accumulation

  11. Reversible MRI changes in a patient with uremic encephalopathy.

    PubMed

    Schmidt, M; Sitter, T; Lederer, S R; Held, E; Schiffl, H

    2001-01-01

    A 19-year-old patient on chronic ambulatory peritoneal dialysis experienced severe neurologic disturbances caused by uremia. Increased signal intensity was seen bilaterally in the cortical and subcortical areas of the occipital and parietal lobe on cranial magnetic resonance imaging (MRI). Insufficient peritoneal dialysis efficacy was documented and the patient was switched from peritoneal to hemodialysis. Cranial MRI indicated a marked regression of the lesions to nearly normal, confirming the diagnosis of uremic encephalopathy.

  12. Self-Assembling Nanocomplexes by combining Ferumoxytol, Heparin And Protamine For Cell Tracking by MRI

    PubMed Central

    Thu, Mya S.; Bryant, L. Henry; Coppola, Tiziana; Jordan, E. Kay; Budde, Matthew D.; Lewis, Bobbi K.; Chaudhry, Aneeka; Ren, Jiaqiang; Varma, Nadimpalli Ravi S.; Arbab, Ali S.; Frank, Joseph A.

    2011-01-01

    We report on a novel and straightforward magnetic cell labeling approach that combines three FDA-approved drugs, ferumoxytol (F), heparin (H) and protamine (P) in serum free media to form self-assembling nanocomplexes that effectively label cells for in vivo MRI. We observed that the HPF nanocomplexes were stable in serum free cell culture media. HPF nanocomplexes exhibited a three-fold increase in T2 relaxivity compared to F. Electron Microscopy revealed internalized HPF within endosomes, confirmed by Prussian blue staining of labeled cells. There was no long-term effect or toxicity on cellular physiology or function of HPF-labeled hematopoietic stem cells, bone marrow stromal cells, neural stem cells, and T-cells when compared to controls. In vivo MRI detected 1000 HPF-labeled cells implanted in rat brains. HPF labeling method should facilitate the monitoring by MRI of infused or implanted cells in clinical trials. PMID:22366951

  13. Mascara and eyelining tattoos: MRI artifacts.

    PubMed

    Weiss, R A; Saint-Louis, L A; Haik, B G; McCord, C D; Taveras, J L

    1989-04-01

    Magnetic resonance imaging (MRI) is very useful in the evaluation of ocular and orbital disease. Heavy metal particles, used in the pigment base of mascara and eyelining tattoos, have a paramagnetic effect that causes alteration of the local magnetic field in adjacent tissues. These changes in normal signal result in distortion of the globes. In some cases, the distortion may mimic actual ocular disease such as a ciliary body melanoma or cyst.

  14. Graphene for Biomedical Implants

    NASA Astrophysics Data System (ADS)

    Moore, Thomas; Podila, Ramakrishna; Alexis, Frank; Rao, Apparao; Clemson Bioengineering Team; Clemson Physics Team

    2013-03-01

    In this study, we used graphene, a one-atom thick sheet of carbon atoms, to modify the surfaces of existing implant materials to enhance both bio- and hemo-compatibility. This novel effort meets all functional criteria for a biomedical implant coating as it is chemically inert, atomically smooth and highly durable, with the potential for greatly enhancing the effectiveness of such implants. Specifically, graphene coatings on nitinol, a widely used implant and stent material, showed that graphene coated nitinol (Gr-NiTi) supports excellent smooth muscle and endothelial cell growth leading to better cell proliferation. We further determined that the serum albumin adsorption on Gr-NiTi is greater than that of fibrinogen, an important and well understood criterion for promoting a lower thrombosis rate. These hemo-and biocompatible properties and associated charge transfer mechanisms, along with high strength, chemical inertness and durability give graphene an edge over most antithrombogenic coatings for biomedical implants and devices.

  15. In vitro assessment of tissue heating near metallic medical implants by exposure to pulsed radio frequency diathermy

    NASA Astrophysics Data System (ADS)

    Ruggera, P. S.; Witters, D. M.; von Maltzahn, G.; Bassen, H. I.

    2003-09-01

    A patient with bilateral implanted neurostimulators suffered significant brain tissue damage, and subsequently died, following diathermy treatment to hasten recovery from teeth extraction. Subsequent MRI examinations showed acute deterioration of the tissue near the deep brain stimulator (DBS) lead's electrodes which was attributed to excessive tissue heating induced by the diathermy treatment. Though not published in the open literature, a second incident was reported for a patient with implanted neurostimulators for the treatment of Parkinson's disease. During a diathermy treatment for severe kyphosis, the patient had a sudden change in mental status and neurological deficits. The diathermy was implicated in causing damage to the patient's brain tissue. To investigate if diathermy induced excessive heating was possible with other types of implantable lead systems, or metallic implants in general, we conducted a series of in vitro laboratory tests. We obtained a diathermy unit and also assembled a controllable laboratory exposure system. Specific absorption rate (SAR) measurements were performed using fibre optic thermometry in proximity to the implants to determine the rate of temperature rise using typical diathermy treatment power levels. Comparisons were made of the SAR measurements for a spinal cord stimulator (SCS) lead, a pacemaker lead and three types of bone prosthesis (screws, rods and a plate). Findings indicate that temperature changes of 2.54 and 4.88 °C s-1 with corresponding SAR values of 9129 and 17 563 W kg-1 near the SCS and pacemaker electrodes are significantly higher than those found in the proximity of the other metallic implants which ranged from 0.04 to 0.69 °C s-1 (129 to 2471 W kg-1). Since the DBS leads that were implanted in the reported human incidents have one-half the electrode surface area of the tested SCS lead, these results imply that tissue heating at rates at least equal to or up to twice as much as those reported here for

  16. A technique to eliminate subgingival cement adhesion to implant abutments by using polytetrafluoroethylene tape.

    PubMed

    Hess, Timothy A

    2014-08-01

    Residual excess cement adhered subgingivally to an implant abutment has the potential to cause periimplant mucositis or periimplant disease. This article describes a procedure in which polytetrafluoroethylene (PTFE) tape is used to protect dental cements from adhering to the implant abutment. This technique ensures complete removal of cement from the implant abutment after seating of the crown.

  17. Speech quality evaluation of subcutaneously implanted microphone using in vivo experiment.

    PubMed

    Woo, Seong Tak; Lee, Gihyoun; Jung, Eui Sung; Lim, Hyung-Gyu; Seong, Ki Woong; Lee, Jyung Hyun; Kim, Myoung Nam; Cho, Jin-Ho

    2014-01-01

    The microphone in a fully implantable hearing device (FIHD) is generally implanted under the skin covering the temporal bone. However, the implanted microphone can be affected by the skin, which causes both sound attenuation and distortion, particularly at high frequencies. As the degree of attenuation and distortion through the skin is severe, speech quality evaluation parameters are needed for the received signal when designing an implantable microphone. However, the performance of most implantable microphones is only assessed based on the sensitivity and frequency response. Thus, practical indicators based on human auditory characteristics are needed for an objective evaluation of the performance of implantable microphones. In this study, a subcutaneously implantable microphone was designed, and its frequency response investigated using an in vivo experiment. Plus, to evaluate the objective indicators, the speech quality of the signals measured by the implanted microphone was calculated using a MATLAB program, and the indicators compared before and after implantation.

  18. The Relationship between Biofilm and Physical-Chemical Properties of Implant Abutment Materials for Successful Dental Implants

    PubMed Central

    de Avila, Erica Dorigatti; de Molon, Rafael Scaf; Vergani, Carlos Eduardo; de Assis Mollo, Francisco; Salih, Vehid

    2014-01-01

    The aim of this review was to investigate the relationship between biofilm and peri-implant disease, with an emphasis on the types of implant abutment surfaces. Individuals with periodontal disease typically have a large amount of pathogenic microorganisms in the periodontal pocket. If the individuals lose their teeth, these microorganisms remain viable inside the mouth and can directly influence peri-implant microbiota. Metal implants offer a suitable solution, but similarly, these remaining bacteria can adhere on abutment implant surfaces, induce peri-implantitis causing potential destruction of the alveolar bone near to the implant threads and cause the subsequent loss of the implant. Studies have demonstrated differences in biofilm formation on dental materials and these variations can be associated with both physical and chemical characteristics of the surfaces. In the case of partially edentulous patients affected by periodontal disease, the ideal type of implant abutments utilized should be one that adheres the least or negligible amounts of periodontopathogenic bacteria. Therefore, it is of clinically relevance to know how the bacteria behave on different types of surfaces in order to develop new materials and/or new types of treatment surfaces, which will reduce or inhibit adhesion of pathogenic microorganisms, and, thus, restrict the use of the abutments with indication propensity for bacterial adhesion. PMID:28788641

  19. The Relationship between Biofilm and Physical-Chemical Properties of Implant Abutment Materials for Successful Dental Implants.

    PubMed

    de Avila, Erica Dorigatti; de Molon, Rafael Scaf; Vergani, Carlos Eduardo; de Assis Mollo, Francisco; Salih, Vehid

    2014-05-07

    The aim of this review was to investigate the relationship between biofilm and peri-implant disease, with an emphasis on the types of implant abutment surfaces. Individuals with periodontal disease typically have a large amount of pathogenic microorganisms in the periodontal pocket. If the individuals lose their teeth, these microorganisms remain viable inside the mouth and can directly influence peri-implant microbiota. Metal implants offer a suitable solution, but similarly, these remaining bacteria can adhere on abutment implant surfaces, induce peri-implantitis causing potential destruction of the alveolar bone near to the implant threads and cause the subsequent loss of the implant. Studies have demonstrated differences in biofilm formation on dental materials and these variations can be associated with both physical and chemical characteristics of the surfaces. In the case of partially edentulous patients affected by periodontal disease, the ideal type of implant abutments utilized should be one that adheres the least or negligible amounts of periodontopathogenic bacteria. Therefore, it is of clinically relevance to know how the bacteria behave on different types of surfaces in order to develop new materials and/or new types of treatment surfaces, which will reduce or inhibit adhesion of pathogenic microorganisms, and, thus, restrict the use of the abutments with indication propensity for bacterial adhesion.

  20. Evaluation of the Etiologies of Implant Fracture in Patients With Fractures of the Implants of Lower Limbs’ Long Bones

    PubMed Central

    Yeganeh, Ali; Otoukesh, Babak; Kaghazian, Peyman; Yeganeh, Nima; Boddohi, Bahram; Moghtadaei, Mehdi

    2015-01-01

    Background: Orthopedics implants are important tools for treatment of bone fractures. Despite available recommendations for designing and making the implants, there are multiple cases of fracture of these implants in the body. Hence, in this study the frequency of failure of implants in long bones of lower extremities was evaluated. Methods and Materials: In this cross-sectional study, two types of fractured implants in the body were analyzed and underwent metalogical, mechanical, and modeling and stress-bending analysis. Results: The results revealed that the main cause of fractures was decreased mechanical resistance due to inappropriate chemical composition (especially decreased percentages of Nickel and Molybdenum). Conclusions: It may be concluded that following the standard chemical composition and use of optimal making method are the most important works for prevention of failure of implants. PMID:26843735

  1. Evaluation of the Etiologies of Implant Fracture in Patients With Fractures of the Implants of Lower Limbs' Long Bones.

    PubMed

    Yeganeh, Ali; Otoukesh, Babak; Kaghazian, Peyman; Yeganeh, Nima; Boddohi, Bahram; Moghtadaei, Mehdi

    2015-12-01

    Orthopedics implants are important tools for treatment of bone fractures. Despite available recommendations for designing and making the implants, there are multiple cases of fracture of these implants in the body. Hence, in this study the frequency of failure of implants in long bones of lower extremities was evaluated. In this cross-sectional study, two types of fractured implants in the body were analyzed and underwent metalogical, mechanical, and modeling and stress-bending analysis. The results revealed that the main cause of fractures was decreased mechanical resistance due to inappropriate chemical composition (especially decreased percentages of Nickel and Molybdenum). It may be concluded that following the standard chemical composition and use of optimal making method are the most important works for prevention of failure of implants.

  2. Suppression of human spermatogenesis by testosterone implants.

    PubMed

    Handelsman, D J; Conway, A J; Boylan, L M

    1992-11-01

    Hormonally induced azoospermia is an effective, reversible form of male contraception; however, some men treated with weekly im testosterone enanthate (TE) injections fail to become azoospermic. As weekly injections cause widely fluctuating and supraphysiological testosterone levels, we tested the hypothesis that more stable, physiological testosterone levels would consistently produce azoospermia. Using a depot testosterone formulation which provides stable, physiological range testosterone levels for up to 6 months, we studied nine men before and after insertion of six 200 mg testosterone implants under the abdominal wall skin and compared the results with 38 men treated in a previous study with weekly im injections of 200 mg TE. Testosterone implants suppressed sperm output to near-azoospermia between the second to fourth postimplant months returning to normal by the sixth postimplant month. The fall in sperm output at the first month was greater after testosterone implants than TE injections (58% vs. 17%, P = 0.011) but similar proportions of men became azoospermic (5/9 vs. 25/38) or severely oligozoospermic (< 1 million/ml; 9/9 vs. 37/38). Plasma testosterone and estradiol levels remained mostly within the eugonadal range after implants but were markedly supraphysiological during TE injections. Both treatments suppressed immunoreactive LH and FSH to undetectable levels by ultrasensitive fluoroimmunoassay. Sex hormone-binding globulin levels were decreased and PRL levels increased by TE injections but neither was changed by testosterone implants. Prostate-specific antigen demonstrated a small rise of marginal significance (P = 0.065) after testosterone implants. Fewer men experienced acne after implants (0/9 vs. 25/38, p = 0.0004). Therefore a depot testosterone preparation with quasi-zero-order release demonstrates higher dose efficiency with similar (but not uniform) efficacy at inducing azoospermia but may cause fewer androgenic side-effects than weekly TE

  3. MRI assessment of bone structure and microarchitecture.

    PubMed

    Chang, Gregory; Boone, Sean; Martel, Dimitri; Rajapakse, Chamith S; Hallyburton, Robert S; Valko, Mitch; Honig, Stephen; Regatte, Ravinder R

    2017-02-06

    Osteoporosis is a disease of weak bone and increased fracture risk caused by low bone mass and microarchitectural deterioration of bone tissue. The standard-of-care test used to diagnose osteoporosis, dual-energy x-ray absorptiometry (DXA) estimation of areal bone mineral density (BMD), has limitations as a tool to identify patients at risk for fracture and as a tool to monitor therapy response. Magnetic resonance imaging (MRI) assessment of bone structure and microarchitecture has been proposed as another method to assess bone quality and fracture risk in vivo. MRI is advantageous because it is noninvasive, does not require ionizing radiation, and can evaluate both cortical and trabecular bone. In this review article, we summarize and discuss research progress on MRI of bone structure and microarchitecture over the last decade, focusing on in vivo translational studies. Single-center, in vivo studies have provided some evidence for the added value of MRI as a biomarker of fracture risk or treatment response. Larger, prospective, multicenter studies are needed in the future to validate the results of these initial translational studies.

  4. Toxic metronidazole-induced MRI changes.

    PubMed

    Horlen, C K; Seifert, C F; Malouf, C S

    2000-11-01

    To report a case of changes documented by magnetic resonance imaging (MRI) of the head probably due to accumulation of metronidazole in a patient with liver dysfunction. A 34-year-old Hispanic man with cirrhosis and hepatitis C being treated with metronidazole for Bacteroides fragilis meningitis and bacteremia developed ataxia, disorientation, and peripheral neuropathy. An