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  1. Article ; Online: Enhancing the brain MRI at ultra-high field systems using a meta-array structure.

    Alipour, Akbar / Seifert, Alan C / Delman, Bradley N / Hof, Patrick R / Fayad, Zahi A / Balchandani, Priti

    Medical physics

    2023  Volume 50, Issue 12, Page(s) 7606–7618

    Abstract: Background: The main advantage of ultra-high field (UHF) magnetic resonance neuroimaging is theincreased signal-to-noise ratio (SNR) compared with lower field strength imaging. However, the wavelength effect associated with UHF MRI results in ... ...

    Abstract Background: The main advantage of ultra-high field (UHF) magnetic resonance neuroimaging is theincreased signal-to-noise ratio (SNR) compared with lower field strength imaging. However, the wavelength effect associated with UHF MRI results in radiofrequency (RF) inhomogeneity, compromising whole brain coverage for many commercial coils. Approaches to resolving this issue of transmit field inhomogeneity include the design of parallel transmit systems (PTx), RF pulse design, and applying passive RF shimming such as high dielectric materials. However, these methods have some drawbacks such as unstable material parameters of dielectric pads, high-cost, and complexity of PTx systems. Metasurfaces are artificial structures with a unique platform that can control the propagation of the electromagnetic (EM) waves, and they are very promising for engineering EM device. Implementation of meta-arrays enhancing MRI has been explored previously in several studies.
    Purpose: The aim of this study was to assess the effect of new meta-array technology on enhancing the brain MRI at 7T. A meta-array based on a hybrid structure consisting of an array of broadside-coupled split-ring resonators and high-permittivity materials was designed to work at the Larmor frequency of a 7 Tesla (7T) MRI scanner. When placed behind the head and neck, this construct improves the SNR in the region of the cerebellum,brainstem and the inferior aspect of the temporal lobes.
    Methods: Numerical electromagnetic simulations were performed to optimize the meta-array design parameters and determine the RF circuit configuration. The resultant transmit-efficiency and signal sensitivity improvements were experimentally analyzed in phantoms followed by healthy volunteers using a 7T whole-body MRI scanner equipped with a standard one-channel transmit, 32-channel receive head coil. Efficacy was evaluated through acquisition with and without the meta-array using two basic sequences: gradient-recalled-echo (GRE) and turbo-spin-echo (TSE).
    Results: Experimental phantom analysis confirmed two-fold improvement in the transmit efficiency and 1.4-fold improvement in the signal sensitivity in the target region. In vivo GRE and TSE images with the meta-array in place showed enhanced visualization in inferior regions of the brain, especially of the cerebellum, brainstem, and cervical spinal cord.
    Conclusion: Addition of the meta-array to commonly used MRI coils can enhance SNR to extend the anatomical coverage of the coil and improve overall MRI coil performance. This enhancement in SNR can be leveraged to obtain a higher resolution image over the same time slot or faster acquisition can be achieved with same resolution. Using this technique could improve the performance of existing commercial coils at 7T for whole brain and other applications.
    MeSH term(s) Humans ; Magnetic Resonance Imaging ; Neuroimaging ; Brain/diagnostic imaging ; Brain Stem ; Head ; Phantoms, Imaging ; Radio Waves ; Signal-To-Noise Ratio ; Equipment Design
    Language English
    Publishing date 2023-10-24
    Publishing country United States
    Document type Journal Article
    ZDB-ID 188780-4
    ISSN 2473-4209 ; 0094-2405
    ISSN (online) 2473-4209
    ISSN 0094-2405
    DOI 10.1002/mp.16801
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    Zs.A 1210: Show issues Location:
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  2. Article ; Online: Evidence of traumatic brain injury in headbutting bovids.

    Ackermans, Nicole L / Varghese, Merina / Williams, Terrie M / Grimaldi, Nicholas / Selmanovic, Enna / Alipour, Akbar / Balchandani, Priti / Reidenberg, Joy S / Hof, Patrick R

    Acta neuropathologica

    2022  Volume 144, Issue 1, Page(s) 5–26

    Abstract: Traumatic brain injury (TBI) is a leading cause of neurologic impairment and death that remains poorly understood. Rodent models have yet to produce clinical therapies, and the exploration of larger and more diverse models remains relatively scarce. We ... ...

    Abstract Traumatic brain injury (TBI) is a leading cause of neurologic impairment and death that remains poorly understood. Rodent models have yet to produce clinical therapies, and the exploration of larger and more diverse models remains relatively scarce. We investigated the potential for brain injury after headbutting in two combative bovid species by assessing neuromorphology and neuropathology through immunohistochemistry and stereological quantification. Postmortem brains of muskoxen (Ovibos moschatus, n = 3) and bighorn sheep (Ovis canadensis, n = 4) were analyzed by high-resolution MRI and processed histologically for evidence of TBI. Exploratory histological protocols investigated potential abnormalities in neurons, microglia, and astrocytes in the prefrontal and parietal cortex. Phosphorylated tau protein, a TBI biomarker found in the cerebrospinal fluid and in neurodegenerative lesions, was used to detect possible cellular consequences of chronic or acute TBI. MRI revealed no abnormal neuropathological changes; however, high amounts of tau-immunoreactive neuritic thread clusters, neurites, and neurons were concentrated in the superficial layers of the neocortex, preferentially at the bottom of the sulci in the muskoxen and occasionally around blood vessels. Tau-immunoreactive lesions were rare in the bighorn sheep. Additionally, microglia and astrocytes showed no grouping around tau-immunoreactive cells in either species. Our preliminary findings indicate that muskoxen and possibly other headbutting bovids suffer from chronic or acute brain trauma and that the males' thicker skulls may protect them to a certain extent.
    MeSH term(s) Animals ; Brain/pathology ; Brain Injuries/pathology ; Brain Injuries, Traumatic/diagnostic imaging ; Brain Injuries, Traumatic/pathology ; Cattle ; Chronic Traumatic Encephalopathy/pathology ; Male ; Neuropathology ; tau Proteins/metabolism
    Chemical Substances tau Proteins
    Language English
    Publishing date 2022-05-17
    Publishing country Germany
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 1079-0
    ISSN 1432-0533 ; 0001-6322
    ISSN (online) 1432-0533
    ISSN 0001-6322
    DOI 10.1007/s00401-022-02427-2
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  3. Article ; Online: Design, Construction, and Implementation of a Magnetic Resonance Elastography Actuator for Research Purposes.

    Triolo, Emily Rose / Khegai, Oleksandr / Ozkaya, Efe / Rossi, Nicholas / Alipour, Akbar / Fleysher, Lazar / Balchandani, Priti / Kurt, Mehmet

    Current protocols

    2022  Volume 2, Issue 3, Page(s) e379

    Abstract: Magnetic resonance elastography (MRE) is a technique for determining the mechanical response of soft materials using applied harmonic deformation of the material and a motion-sensitive magnetic resonance imaging sequence. This technique can elucidate ... ...

    Abstract Magnetic resonance elastography (MRE) is a technique for determining the mechanical response of soft materials using applied harmonic deformation of the material and a motion-sensitive magnetic resonance imaging sequence. This technique can elucidate significant information about the health and development of human tissue such as liver and brain, and has been used on phantom models (e.g., agar, silicone) to determine their suitability for use as a mechanical surrogate for human tissues in experimental models. The applied harmonic deformation used in MRE is generated by an actuator, transmitted in bursts of a specified duration, and synchronized with the magnetic resonance signal excitation. These actuators are most often a pneumatic design (common for human tissues or phantoms) or a piezoelectric design (common for small animal tissues or phantoms). Here, we describe how to design and assemble both a pneumatic and a piezoelectric MRE actuator for research purposes. For each of these actuator types, we discuss displacement requirements, end-effector options and challenges, electronics and electronic-driving requirements and considerations, and full MRE implementation. We also discuss how to choose the actuator type, size, and power based on the intended material and use. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Design, construction, and implementation of a convertible pneumatic MRE actuator for use with tissues and phantom models Basic Protocol 2: Design, construction, and implementation of a piezoelectric MRE actuator for localized excitation in phantom models.
    MeSH term(s) Animals ; Brain/diagnostic imaging ; Elasticity Imaging Techniques/methods ; Magnetic Resonance Imaging/methods ; Motion ; Phantoms, Imaging
    Language English
    Publishing date 2022-08-17
    Publishing country United States
    Document type Journal Article
    ISSN 2691-1299
    ISSN (online) 2691-1299
    DOI 10.1002/cpz1.379
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  4. Article ; Online: An endovaginal MRI array with a forward-looking coil for advanced gynecological cancer brachytherapy procedures: Design and initial results.

    Alipour, Akbar / Viswanathan, Akila N / Watkins, Ronald D / Elahi, Hassan / Loew, Wolfgang / Meyer, Eric / Morcos, Marc / Halperin, Henry R / Schmidt, Ehud J

    Medical physics

    2021  Volume 48, Issue 11, Page(s) 7283–7298

    Abstract: Purpose: To develop an endovaginal MRI array that provides signal enhancement forward into the posterior parametrium and sideways into the vaginal wall, accelerating multiple-contrast detection of residual tumors that survive external beam radiation. ... ...

    Abstract Purpose: To develop an endovaginal MRI array that provides signal enhancement forward into the posterior parametrium and sideways into the vaginal wall, accelerating multiple-contrast detection of residual tumors that survive external beam radiation. The array's enclosure should form an obturator for cervical cancer brachytherapy, allowing integration with MRI-guided catheter placement, CT, and interstitial radiation dose delivery.
    Methods: The endovaginal array consisted of forward-looking and sideways-looking components. The forward-looking element imaged the cervix and posterior endometrium, and the sideways-looking elements imaged the vaginal wall. Electromagnetic simulation was performed to optimize the geometry of a forward-looking coil placed on a conductive-metallic substrate, extending the forward penetration above the coil's tip. Thereafter, an endovaginal array with one forward-looking coil and four sideways-looking elements was constructed and tested at 1.5 Tesla in saline and gel phantoms, and three sexually mature swine. Each coil's tuning, matching, and decoupling were optimized theoretically, implemented with electronic circuits, and validated with network-analyzer measurements. The array enclosure emulates a conventional brachytherapy obturator, allowing use of the internal imaging array together with tandem coils and interstitial catheters, as well as use of the enclosure alone during CT and radiation delivery. To evaluate the receive magnetic field (
    Results: Simulated
    Conclusions: Higher SNR gynecological imaging is supported by forward-looking and sideways-looking coils. A forward-looking endovaginal coil for cervix and parametrium imaging was built with optimized metal backing. Array placement within an obturator enhanced integration with the brachytherapy procedure and accelerated imaging for detecting postexternal-beam residual tumors.
    MeSH term(s) Animals ; Brachytherapy ; Equipment Design ; Female ; Humans ; Magnetic Resonance Imaging ; Phantoms, Imaging ; Signal-To-Noise Ratio ; Swine ; Uterine Cervical Neoplasms/diagnostic imaging ; Uterine Cervical Neoplasms/radiotherapy
    Language English
    Publishing date 2021-10-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 188780-4
    ISSN 2473-4209 ; 0094-2405
    ISSN (online) 2473-4209
    ISSN 0094-2405
    DOI 10.1002/mp.15228
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    Zs.A 1210: Show issues Location:
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  5. Article ; Online: Intracardiac MR imaging (ICMRI) guiding-sheath with amplified expandable-tip imaging and MR-tracking for navigation and arrythmia ablation monitoring: Swine testing at 1.5 and 3T.

    Schmidt, Ehud J / Olson, Gregory / Tokuda, Junichi / Alipour, Akbar / Watkins, Ronald D / Meyer, Eric M / Elahi, Hassan / Stevenson, William G / Schweitzer, Jeffrey / Dumoulin, Charles L / Johnson, Thomas / Kolandaivelu, Aravindan / Loew, Wolfgang / Halperin, Henry R

    Magnetic resonance in medicine

    2022  Volume 87, Issue 6, Page(s) 2885–2900

    Abstract: Purpose: Develop a deflectable intracardiac MR imaging (ICMRI) guiding-sheath to accelerate imaging during MR-guided electrophysiological (EP) interventions for radiofrequency (500 kHz) ablation (RFA) of arrythmia. Requirements include imaging at three ... ...

    Abstract Purpose: Develop a deflectable intracardiac MR imaging (ICMRI) guiding-sheath to accelerate imaging during MR-guided electrophysiological (EP) interventions for radiofrequency (500 kHz) ablation (RFA) of arrythmia. Requirements include imaging at three to five times surface-coil SNR in cardiac chambers, vascular insertion, steerable-active-navigation into cardiac chambers, operation with ablation catheters, and safe levels of MR-induced heating.
    Methods: ICMRI's 6 mm outer-diameter (OD) metallic-braided shaft had a 2.6 mm OD internal lumen for ablation-catheter insertion. Miniature-Baluns (MBaluns) on ICMRI's 1 m shaft reduced body-coil-induced heating. Distal section was a folded "star"-shaped imaging-coil mounted on an expandable frame, with an integrated miniature low-noise-amplifier overcoming cable losses. A handle-activated movable-shaft expanded imaging-coil to 35 mm OD for imaging within cardiac-chambers. Four MR-tracking micro-coils enabled navigation and motion-compensation, assuming a tetrahedron-shape when expanded. A second handle-lever enabled distal-tip deflection. ICMRI with a protruding deflectable EP catheter were used for MR-tracked navigation and RFA using a dedicated 3D-slicer user-interface. ICMRI was tested at 3T and 1.5T in swine to evaluate (a) heating, (b) cardiac-chamber access, (c) imaging field-of-view and SNR, and (d) intraprocedural RFA lesion monitoring.
    Results: The 3T and 1.5T imaging SNR demonstrated >400% SNR boost over a 4 × 4 × 4 cm
    Conclusion: ICMRI assisted EP-catheter navigation to difficult targets and accelerated RFA monitoring.
    MeSH term(s) Animals ; Arrhythmias, Cardiac ; Catheter Ablation/methods ; Equipment Design ; Heart Atria ; Magnetic Resonance Imaging/methods ; Swine
    Language English
    Publishing date 2022-02-10
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 605774-3
    ISSN 1522-2594 ; 0740-3194
    ISSN (online) 1522-2594
    ISSN 0740-3194
    DOI 10.1002/mrm.29168
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    Zs.A 1959: Show issues Location:
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  6. Article ; Online: Multimodal Assessment of Bottlenose Dolphin Auditory Nuclei Using 7-Tesla MRI, Immunohistochemistry and Stereology.

    Orekhova, Ksenia / Selmanovic, Enna / De Gasperi, Rita / Gama Sosa, Miguel A / Wicinski, Bridget / Maloney, Brigid / Seifert, Alan / Alipour, Akbar / Balchandani, Priti / Gerussi, Tommaso / Graïc, Jean-Marie / Centelleghe, Cinzia / Di Guardo, Giovanni / Mazzariol, Sandro / Hof, Patrick R

    Veterinary sciences

    2022  Volume 9, Issue 12

    Abstract: The importance of assessing neurochemical processes in the cetacean brain as a tool for monitoring their cognitive health and to indirectly model human neurodegenerative conditions is increasingly evident, although available data are largely ... ...

    Abstract The importance of assessing neurochemical processes in the cetacean brain as a tool for monitoring their cognitive health and to indirectly model human neurodegenerative conditions is increasingly evident, although available data are largely semiquantitative. High-resolution MRI for post-mortem brains and stereology allow for quantitative assessments of the cetacean brain. In this study, we scanned two brains of bottlenose dolphins in a 7-Tesla (7T) MR scanner and assessed the connectivity of the inferior colliculi and ventral cochlear nuclei using diffusion tensor imaging (DTI). Serial thick sections were investigated stereologically in one of the dolphins to generate rigorous quantitative estimates of identifiable cell types according to their morphology and expression of molecular markers, yielding reliable cell counts with most coefficients of error <10%. Fibronectin immunoreactivity in the dolphin resembled the pattern in a human chronic traumatic encephalopathy brain, suggesting that neurochemical compensation for insults such as hypoxia may constitute a noxious response in humans, while being physiological in dolphins. These data contribute to a growing body of knowledge on the morphological and neurochemical properties of the dolphin brain and highlight a stereological and neuroimaging workflow that may enable quantitative and translational assessment of pathological processes in the dolphin brain in the future.
    Language English
    Publishing date 2022-12-13
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2768971-2
    ISSN 2306-7381 ; 2306-7381
    ISSN (online) 2306-7381
    ISSN 2306-7381
    DOI 10.3390/vetsci9120692
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  7. Article ; Online: Utilizing Multiple BioMEMS Sensors to Monitor Orthopaedic Strain and Predict Bone Fracture Healing.

    Wolynski, Jakob G / Sutherland, Conor J / Demir, Hilmi Volkan / Unal, Emre / Alipour, Akbar / Puttlitz, Christian M / McGilvray, Kirk C

    Journal of orthopaedic research : official publication of the Orthopaedic Research Society

    2019  Volume 37, Issue 9, Page(s) 1873–1880

    Abstract: Current diagnostic modalities, such as radiographs or computed tomography, exhibit limited ability to predict the outcome of bone fracture healing. Failed fracture healing after orthopaedic surgical treatments are typically treated by secondary surgery; ... ...

    Abstract Current diagnostic modalities, such as radiographs or computed tomography, exhibit limited ability to predict the outcome of bone fracture healing. Failed fracture healing after orthopaedic surgical treatments are typically treated by secondary surgery; however, the negative correlation of time between primary and secondary surgeries with resultant health outcome and medical cost accumulation drives the need for improved diagnostic tools. This study describes the simultaneous use of multiple (n = 5) implantable flexible substrate wireless microelectromechanical (fsBioMEMS) sensors adhered to an intramedullary nail (IMN) to quantify the biomechanical environment along the length of fracture fixation hardware during simulated healing in ex vivo ovine tibiae. This study further describes the development of an antenna array for interrogation of five fsBioMEMS sensors simultaneously, and quantifies the ability of these sensors to transmit signal through overlaying soft tissues. The ex vivo data indicated significant differences associated with sensor location on the IMN (p < 0.01) and fracture state (p < 0.01). These data indicate that the fsBioMEMS sensor can serve as a tool to diagnose the current state of fracture healing, and further supports the use of the fsBioMEMS as a means to predict fracture healing due to the known existence of latency between changes in fracture site material properties and radiographic changes. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1873-1880, 2019.
    MeSH term(s) Fracture Healing ; Humans ; Micro-Electrical-Mechanical Systems ; Orthopedic Procedures ; Stress, Mechanical
    Language English
    Publishing date 2019-05-17
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 605542-4
    ISSN 1554-527X ; 0736-0266
    ISSN (online) 1554-527X
    ISSN 0736-0266
    DOI 10.1002/jor.24325
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    Zs.A 1879: Show issues Location:
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  8. Article ; Online: Improvement of magnetic resonance imaging using a wireless radiofrequency resonator array.

    Alipour, Akbar / Seifert, Alan C / Delman, Bradley N / Robson, Philip M / Shrivastava, Raj / Hof, Patrick R / Adriany, Gregor / Fayad, Zahi A / Balchandani, Priti

    Scientific reports

    2021  Volume 11, Issue 1, Page(s) 23034

    Abstract: In recent years, new human magnetic resonance imaging systems operating at static magnetic fields strengths of 7 Tesla or higher have become available, providing better signal sensitivity compared with lower field strengths. However, imaging human-sized ... ...

    Abstract In recent years, new human magnetic resonance imaging systems operating at static magnetic fields strengths of 7 Tesla or higher have become available, providing better signal sensitivity compared with lower field strengths. However, imaging human-sized objects at such high field strength and associated precession frequencies is limited due to the technical challenges associated with the wavelength effect, which substantially disturb the transmit field uniformity over the human body when conventional coils are used. Here we report a novel passive inductively-coupled radiofrequency resonator array design with a simple structure that works in conjunction with conventional coils and requires only to be tuned to the scanner's operating frequency. We show that inductive-coupling between the resonator array and the coil improves the transmit efficiency and signal sensitivity in the targeted region. The simple structure, flexibility, and cost-efficiency make the proposed array design an attractive approach for altering the transmit field distribution specially at high field systems, where the wavelength is comparable with the tissue size.
    MeSH term(s) Adult ; Biomedical Engineering ; Brain/diagnostic imaging ; Computer Simulation ; Contrast Media ; Electricity ; Electromagnetic Radiation ; Equipment Design ; Female ; Hot Temperature ; Humans ; Magnetic Fields ; Magnetic Resonance Imaging/instrumentation ; Magnetic Resonance Imaging/methods ; Magnetics ; Male ; Middle Aged ; Nanotechnology ; Phantoms, Imaging ; Radio Waves ; Signal Processing, Computer-Assisted
    Chemical Substances Contrast Media
    Language English
    Publishing date 2021-11-29
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-021-02533-3
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  9. Article ; Online: The transitional pattern of pain and disability, from perceived pain to sick leave. Experience from a longitudinal study.

    Alipour, Akbar / Bodin, Lennart / Bergstrom, Gunnar / Jensen, Irene

    Journal of back and musculoskeletal rehabilitation

    2013  Volume 26, Issue 4, Page(s) 411–419

    Abstract: Objectives: To investigate the prospective value of the transitional and dynamic patterns of pain disability over time on sick leave in chronic recurrent back/neck pain cases.: Methods: The material used was based on a longitudinal study with three ... ...

    Abstract Objectives: To investigate the prospective value of the transitional and dynamic patterns of pain disability over time on sick leave in chronic recurrent back/neck pain cases.
    Methods: The material used was based on a longitudinal study with three repeated measurements. The graded Chronic Pain Scale was used to assess levels of pain disability. The relationship between the transitional patterns of the pain disability score (ten defined states of decrease, increase or no change, between two time points) and sick leave was analyzed for 909 chronic/recurrent cases in three different models using logistic regression.
    Results: Those with high level of pain disability have a more transitional pattern and their pain level changed during the time period studied. When adjusting for age, gender, education and previous sick leave, the final model indicated that the current level of pain disability was a risk factor in taking sick leave. The likelihood of sick leave was highest in the transition of pain into the highest levels of disability, independent of past disability level of pain. Earlier sick leave remained as an important predictor of sick leave.
    Conclusions: From a clinical and prognostic perspective the probability of sick leave will be different and can be predicted based on previous sick leave but not from former history of pain disability level or its transitional pattern.
    MeSH term(s) Adolescent ; Adult ; Back Pain/diagnosis ; Back Pain/physiopathology ; Chronic Pain/diagnosis ; Chronic Pain/physiopathology ; Disability Evaluation ; Disabled Persons ; Female ; Humans ; Longitudinal Studies ; Male ; Middle Aged ; Neck Pain/diagnosis ; Neck Pain/physiopathology ; Occupational Diseases/diagnosis ; Occupational Diseases/physiopathology ; Recurrence ; Risk Factors ; Sick Leave
    Language English
    Publishing date 2013
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1184721-9
    ISSN 1878-6324 ; 1053-8127
    ISSN (online) 1878-6324
    ISSN 1053-8127
    DOI 10.3233/BMR-130400
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  10. Article ; Online: An inductively coupled ultra-thin, flexible, and passive RF resonator for MRI marking and guiding purposes: Clinical feasibility.

    Alipour, Akbar / Gokyar, Sayim / Algin, Oktay / Atalar, Ergin / Demir, Hilmi Volkan

    Magnetic resonance in medicine

    2017  Volume 80, Issue 1, Page(s) 361–370

    Abstract: Purpose: The purpose of this study is to develop a wireless, flexible, ultra-thin, and passive radiofrequency-based MRI resonant fiducial marker, and to validate its feasibility in a phantom model and several body regions.: Methods: Standard ... ...

    Abstract Purpose: The purpose of this study is to develop a wireless, flexible, ultra-thin, and passive radiofrequency-based MRI resonant fiducial marker, and to validate its feasibility in a phantom model and several body regions.
    Methods: Standard microfabrication processing was used to fabricate the resonant marker. The proposed marker consists of two metal traces in the shape of a square with an edge length of 8 mm, with upper and lower traces connected to each other by a metalized via. A 3T MRI fiducial marking procedure was tested in phantom and ex vivo, and then the marker's performance was evaluated in an MRI experiment using humans. The radiofrequency safety was also tested using temperature sensors in the proximity of the resonator.
    Results: A flexible resonator with a thickness of 115 μm and a dimension of 8 × 8 mm was obtained. The experimental results in the phantom show that at low background flip angles (6-18°), the resonant marker enables precise and rapid visibility, with high marker-to-background contrast and signal-to-noise ratio improvement of greater than 10 in the vicinity of the marker. Temperature analysis showed a specific absorption ratio gain of 1.3. Clinical studies further showed a successful biopsy procedure using the fiducial marking functionality of our device.
    Conclusions: The ultra-thin and flexible structure of this wireless flexible radiofrequency resonant marker offers effective and safe MR visualization with high feasibility for anatomic marking and guiding at various regions of the body. Magn Reson Med 80:361-370, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
    MeSH term(s) Animals ; Artifacts ; Biocompatible Materials/chemistry ; Biopsy, Needle ; Catheterization ; Equipment Design ; Feasibility Studies ; Fiducial Markers ; Forehead/diagnostic imaging ; Humans ; Knee/diagnostic imaging ; Magnetic Resonance Imaging/instrumentation ; Magnetic Resonance Imaging/methods ; Materials Testing ; Metals/chemistry ; Phantoms, Imaging ; Rabbits ; Radio Waves ; Reproducibility of Results ; Signal-To-Noise Ratio
    Chemical Substances Biocompatible Materials ; Metals
    Language English
    Publishing date 2017-11-16
    Publishing country United States
    Document type Journal Article
    ZDB-ID 605774-3
    ISSN 1522-2594 ; 0740-3194
    ISSN (online) 1522-2594
    ISSN 0740-3194
    DOI 10.1002/mrm.26996
    Database MEDical Literature Analysis and Retrieval System OnLINE

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