Now showing items 1-20 of 26

    • Analysis of B1 mapping by Bloch Siegert shift 

      Abacı-Türk, Esra; İder, Yusuf Ziya; Atalar, Ergin (ISMRM, 2012-05)
      The Bloch-Siegert shift is a new phase-based B1 mapping method [1]. This method utilizes the fact that for a large off-resonance frequency, square of the B1 field magnitude is proportional to the phase. In this study, ...
    • Analysis of B1 mapping by Bloch Siegert Shift 

      Türk, Esra Abacı; İder, Yusuf Ziya; Atalar, Ergin (ISMRM, 2012)
      In this study, B1 mapping by the Bloch-Siegert shift is analyzed with simulations and experiments. The importance of the pulse duration and the crusher gradients are investigated. It is shown that the off-resonance pulse ...
    • Approximate fourier domain expression for bloch-siegert shift 

      Turk, E. A.; Ider, Y. Z.; Ergun, A. S.; Atalar, E. (John Wiley and Sons Inc., 2015)
      Purpose: In this study, a newsimple Fourier domain-based analytical expression for the Bloch-Siegert (BS) shift-based B1 mapping method is proposed to obtain |B1+| more accurately while using short BS pulse durations and ...
    • Comparison of system-matrix-based and projection-based reconstructions for field free line magnetic particle imaging 

      Ilbey, S.; Top, C. B.; Güngör, A.; Çukur, T.; Saritas, E. U.; Güven, H. E. (Infinite Science Publishing, 2017)
      In magnetic particle imaging (MPI), system sensitivity can be enhanced by scanning the sample along a field free line (FFL) instead of a field free point (FFP). FFL MPI data can then be processed via system-matrix or ...
    • Decreasing SAR of a multi-dimensional central brightening inhomogeneity correction pulse using nonlinear gradient fields and VERSE 

      Kopanoğlu, Emre; Gökhalk, Yıldıray; Yılmaz, Uğur; Açıkel, Volkan; Atalar, Ergin (ISMRM, 2012-05)
      To correct for B1 inhomogeneity artifacts, multi-dimensional pulses are widely used. However, such pulses increase SAR significantly. In this study, we compare, and combine two SAR reduction methods, the variable rate ...
    • Decreasing SAR of a multi-dimensional central brightening inhomogeneity correction pulse using nonlinear gradient fields and VERSE 

      Kopanoğlu, Emre; Gökhalk, Yıldıray; Yılmaz, Uğur; Açıkel, Volkan; Atalar, Ergin (ISMRM, 2012)
      To correct for B1 inhomogeneity artifacts, multi-dimensional pulses are widely used. However, such pulses increase SAR significantly. In this study, we compare, and combine two SAR reduction methods, the variable rate ...
    • Detection of MR signal during RF excitation using a transmit array system 

      Özen, Ali Çağlar; Ertan, Koray; Atalar, Ergin (ISMRM, 2012-05)
      Most of conventional MRI applications are based on a time interleaved approach for RF excitation and signal detection. The idea of concurrent RF excitation and reception was implemented in a few recent studies using sideband ...
    • Detection of MR signal during RF excitation using a transmit array system 

      Özen, Ali Çağlar; Ertan, Koray; Atalar, Ergin (ISMRM, 2012)
      Concurrent RF transmission and signal reception is significant for applications including imaging species with ultra short T2 values, and measurement of spin properties during excitation. In this study, magnetic field ...
    • Effect of implantable pulse generator (IPG) cases on implant tip heating 

      Açıkel, Volkan; Uslubaş, A.; Atalar, Ergin (2012)
    • Effects of duty cycle on magnetostimulation thresholds in MPI 

      Demirel, O. B.; Saritas, E. U. (Infinite Science Publishing, 2017)
      Magnetic Particle Imaging (MPI) relies on time-varying magnetic fields to generate an image of the spatial distribution of superparamagnetic iron oxide nanoparticles. However, these oscillating magnetic fields form electric ...
    • Evaluation of internal MRI coils using ultimate intrinsic SNR 

      Çelik, H.; Eryaman, Y.; Altıntaş, A.; Abdel-Hafez, I. A.; Atalar, E. (John Wiley & Sons, 2004)
      The upper bounds of the signal-to-noise ratio (also known as the "ultimate intrinsic signal-to-noise ratio" (UISNR)) for internal and external coils were calculated. In the calculation, the body was modeled as a dielectric ...
    • Identification of a novel missense mutation in RAD51 in a large family with congenital mirror movements 

      Onat, Onur Emre; Gülsüner, Süleyman; Bilgen, R.; Dal, G. M.; Bilguvar, K.; Boyacı, Hüseyin; Doerschner, Katja; Uysal, H.; Günel, M.; Özçelik, Tayfun (American Society of Human Genetics, 2012-11)
      Congenital mirror movements (CMM) are a rare and heterogeneous group of disorders characterized by involuntary contralateral movements of mainly the upper extremities during intentional movements on the opposite side. ...
    • Interactive real time inductively coupled catheter coil tracking using a transmit array system 

      Yılmaz, Uğur; Pan, L.; Atalar, Ergin (ISMRM, 2012)
      Inductively coupled catheter coils are advantageous for interventional procedures, since they require no connection to MR scanners, which reduces the difficulties such as device-handling and RF safety problems faced with ...
    • Localizing the excitation to reduce scan time using nonlinear gradient fields 

      Kopanoğlu, Emre; Yılmaz, Uğur; Akın, Burak; Açıkel, Volkan; Atalar, Ergin (ISMRM, 2012)
      elatively low SAR, but they cannot excite local regions and therefore causes long scan times. Although small volumes can be excited using multi-dimensional excitation pulses, such pulses are long and/or have relatively ...
    • Magnetic resonance imaging–guided coronary interventions 

      Tsekos, N. V.; Ergin, A.; Li, D.; Omary, R. A.; Serfaty, J.-M.; Woodard, P. K. (John Wiley & Sons, 2004)
      Magnetic resonance imaging (MRI) guidance for coronary interventions offers potential advantages over conventional x‐ray angiography. Advantages include the use of nonionizing radiation, combined assessment of anatomy and ...
    • Mode matrix tranceiver surface coil 

      Demir, Taner; Türk, Esra Abacı; Atalar, Ergin (ISMRM, 2012)
      The concept of a mode matrix tranceiver surface coil for transmit array system is introduced. The coil performance is experimentally tested and the concept of mode matrix transmission is verified.
    • A motion feature-based algorithm for the detection of specular objects in natural scenes 

      Doerschner, Katja; Yılmaz, Özgür (Sage Publications, 2012-09)
      Successful identification of specularities in an image can be crucial for an artificial vision system when extracting the semantic content of an image or while interacting with the environment. We developed an algorithm ...
    • MR-trackable intramyocardial injection catheter 

      Karmarkar, P. V.; Kraitchman, D. L.; Izbudak, I.; Hofmann, L. V.; Amado, L. C.; Fritzges, D.; Young, R.; Pittenger, M.; Bulte, J. W. M.; Atalar, E. (John Wiley & Sons, 2004)
      There is growing interest in delivering cellular agents to infarcted myocardium to prevent postinfarction left ventricular remodeling. MRI can be effectively used to differentiate infarcted from healthy myocardium. MR-guided ...
    • Nanomaterials for bone tissue regeneration and orthopedic implants 

      Gülseren, Gülcihan; Ceylan, Hakan; Tekinay, Ayşe B.; Güler, Mustafa O. (John Wiley & Sons, 2016-03-11)
      Hierarchical organization and specialized composition of bone extracellular matrix (ECM) control the cellular processes including proliferation, migration, and differentiation for continuous modulation and maintenance of ...
    • Rapid classification of specular and diffuse reflection from image velocities 

      Doerschner, K.; Kersten, D.; Schrater, P. R. (Elsevier BV, 2011-09)
      We propose a method for rapidly classifying surface reflectance directly from the output of spatiotemporal filters applied to an image sequence of rotating objects. Using image data from only a single frame, we compute ...