Emre Kopanoglu

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The ultimate intrinsic signal-to-noise ratio is the highest possible signal-to-noise ratio, and the ultimate intrinsic specific absorption rate provides the lowest limit of the specific absorption rate for a given flip angle distribution. Analytic expressions for ultimate intrinsic signal-to-noise ratio and ultimate intrinsic specific absorption rate are(More)
INTRODUCTION In magnetic resonance imaging (MRI), an increase in signal to noise ratio (SNR) provides higher quality images, making diagnosis easier, thus it should be maximized. The main noise sources in an MRI experiment are classified as preamplifier, coil and body noises. Preamplifier noise is small when ultra-low-noise amplifiers (ULNA) are utilized.(More)
The specific absorption rate is used as one of the main safety parameters in magnetic resonance imaging. The performance of imaging sequences is frequently hampered by the limitations imposed on the specific absorption rate that increase in severity at higher field strengths. The most well-known approach to reducing the specific absorption rate is(More)
Turbo Spin Echo (TSE) is a method of acquiring the echoes of a Cartesian readout in a T2-weighted echo train, resulting in a very fast imaging time. On the other hand, recent methods of spatial encoding with nonlinear magnetic fields have been studied by our group and others to reduce data acquisitions time, such as, PatLoc, O-Space, Null Space, 4D-RIO,(More)
PURPOSE An iterative k-space trajectory and radiofrequency (RF) pulse design method is proposed for excitation using nonlinear gradient magnetic fields. THEORY AND METHODS The spatial encoding functions (SEFs) generated by nonlinear gradient fields are linearly dependent in Cartesian coordinates. Left uncorrected, this may lead to flip angle variations in(More)
During magnetic resonance imaging, there is an interaction between the time-varying magnetic fields and the active implantable medical devices (AIMD). In this study, in order to express the nature of this interaction, simplified analytical expressions for the electric fields induced by time-varying magnetic fields are derived inside a homogeneous(More)
NOVEL TECHNIQUES REGARDING SPECIFIC ABSORPTION RATE AND FIELD OF VIEW REDUCTION IN MAGNETIC RESONANCE IMAGING Emre Kopanoglu Ph.D. in Electrical and Electronics Engineering Supervisors: Prof. Dr. Ergin Atalar Assoc. Prof. Dr. Vakur B. Ertürk September, 2012 In this dissertation, novel strategies regarding the reduction of the specific absorption rate (SAR)(More)
PURPOSE Turbo spin echo (TSE) imaging reduces imaging time by acquiring multiple echoes per repetition (TR), requiring fewer TRs. O-space can also require fewer TRs by using a combination of nonlinear magnetic gradient fields and surface coil arrays. Although to date, O-space has only been demonstrated for gradient echo imaging, it is valuable to combine(More)
PURPOSE While O-Space imaging is well known to accelerate image acquisition beyond traditional Cartesian sampling, its advantages compared to undersampled radial imaging, the linear trajectory most akin to O-Space imaging, have not been detailed. In addition, previous studies have focused on ultrafast imaging with very high acceleration factors and(More)
In this paper, a Multi-Channel/Multi-Contrast image reconstruction algorithm is proposed. The method, which is based on the Augmented Lagrangian Method uses joint convex objective functions to utilize the mutual information in the data from multiple channels to improve reconstruction quality. For this purpose, color total variation and group sparsity are(More)