Abstract：
:Image quality and total scan time in MRI are determined in large part by the trajectory employed to sample the Fourier space. Each trajectory has different properties like coverage of k-space, scan time, sensitivity to off-resonance conditions, etc. These properties are often contradictory, therefore a universal optimal trajectory does not exist and ultimately, it will depend on the image characteristics sought. Most trajectories used today are designed based on intuition and k-space analysis more than with optimization methods. This work presents a 3D k-space trajectory design method based on Genetic Algorithm optimization. Genetic Algorithms have been chosen because they are particularly good for searching large solution spaces. They emulate the natural evolutionary process allowing better offsprings to survive. The objective function searches the maximum of the trajectory's k-space coverage subject to hardware constraints for a fixed scanning time using the trajectory's torsion as its optimization variable. The method proved to be effective for generating k-space trajectories. They are compared with well-established trajectories. The results of simulated experiments show that they can be appropriate for image acquisition under certain special conditions, like off-resonance and undersampling. This design method can be extended to include other objective functions for different behaviors.
journal_name
Magn Reson Imagingjournal_title
Magnetic resonance imagingauthors
Sabat S,Mir R,Guarini M,Guesalaga A,Irarrazaval Pdoi
10.1016/s0730-725x(03)00174-7subject
Has Abstractpub_date
2003-09-01 00:00:00pages
755-64issue
7eissn
0730-725Xissn
1873-5894pii
S0730725X03001747journal_volume
21pub_type
杂志文章abstract：OBJECTIVE:The pathological changes in Parkinson disease begin in the brainstem; reach the limbic system and ultimately spread to the cerebral cortex. In Parkinson disease (PD) patients, we evaluated the alteration of cingulate fibers, which comprise part of the limbic system, by using diffusional kurtosis imaging (DKI)...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2013.06.009
更新日期：2013-11-01 00:00:00
abstract：:Most modern techniques for functional magnetic resonance imaging (fMRI) rely on blood-oxygen-level-dependent (BOLD) contrast as the basic principle for detecting neuronal activation. However, the measured BOLD effect depends on a transfer function related to neurophysiological changes accompanying electrical neural ac...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2008.02.006
更新日期：2008-11-01 00:00:00
abstract：:Disseminated osseous tuberculosis is a rare disease. This is a report of two cases of disseminated osseous tuberculosis imaged with MRI at 1.5-T, CT, plain radiography and bone scintigraphy. CT and plain radiography demonstrated either highly destructive or cystic lesions with sclerotic margins. Bone scintigraphy and ...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(87)90384-5
更新日期：1987-01-01 00:00:00
abstract：:Conventional and spatially resolved proton NMR and relaxation measurements are used in order to study the molecular motions and the equilibrium and nonequilibrium diffusion of oils in Berea sandstone and Venezuelan reservoir rocks. In the water-saturated Berea a single line with T*2 congruent to 150 microseconds is ob...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(92)90420-5
更新日期：1992-01-01 00:00:00
abstract：:Hippocampal metabolite concentrations were determined by localized in vivo proton magnetic resonance spectroscopy (1H MRS) in eleven patients suffering from refractory mesial temporal lobe epilepsy (MTLE), as well as in eleven age-matched healthy volunteers, and compared with patient history, postoperative outcome and...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(98)00123-4
更新日期：1998-10-01 00:00:00
abstract：PURPOSE:The detection of small parenchymal hepatic lesions identified by preoperative imaging remains a challenge for traditional pathologic methods in large specimens. We developed a magnetic resonance imaging (MRI) compatible localization device for imaging of surgical specimens aimed to improve identification and lo...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2016.11.021
更新日期：2017-04-01 00:00:00
abstract：:A new approach to solid-state imaging (SSI) is presented. The method relies on narrowing the resonance line using the Lee-Goldburg sequence. The technique is easy to implement in practice and may find widespread applications in materials science. ...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(92)90409-s
更新日期：1992-01-01 00:00:00
abstract：BACKGROUND:The molecular structure, charge, thermodynamic and kinetic stability are approximately the same for gadodiamide and gadoversetamide, the main substantive difference is that gadodiamide is manufactured with 5% free ligand to form Omniscan® and gadoversetamide with 10% free ligand to form OptiMARK®. PURPOSE:T...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2018.11.015
更新日期：2019-05-01 00:00:00
abstract：OBJECTIVES:The objectives of this study were to develop protocols that measure abdominal fat and calf muscle lipids with magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), respectively, at 3 T and to examine the correlation between these parameters and insulin sensitivity. MATERIALS AND METHOD...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2007.06.006
更新日期：2008-02-01 00:00:00
abstract：:It is a big challenge to segment magnetic resonance (MR) images with intensity inhomogeneity. The widely used segmentation algorithms are region based, which mostly rely on the intensity homogeneity, and could bring inaccurate results. In this paper, we propose a novel region-based active contour model in a variationa...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2012.10.010
更新日期：2013-05-01 00:00:00
abstract：PURPOSE:To characterize the intracranial vascular features extracted from time of flight (TOF) images and their changes from baseline to follow-up in patients undergoing carotid revascularization, using arterial spin labeling (ASL) cerebral blood flow (CBF) measurement as a reference. METHODS:In this retrospective stu...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2020.10.004
更新日期：2021-01-01 00:00:00
abstract：:The advantages of event-related functional Magnetic Resonance Imaging (fMRI) and the increasing use of fMRI in cognitive experiments are both driving the development of techniques that allow images sensitive to the blood oxygen level-dependent effect to be acquired at ever-higher temporal resolution. Here, we present ...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2005.12.030
更新日期：2006-05-01 00:00:00
abstract：PURPOSE:The purpose was to validate diffusion-weighted imaging (DWI) in the assessment of hepatic metastases compared with superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging. MATERIALS AND METHODS:For 21 consecutive patients with 160 metastases from extrahepatic malignancy and 25 benign focal lesi...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2011.12.007
更新日期：2012-05-01 00:00:00
abstract：:Traumatic brain injury (TBI) is one of the commonest causes of morbidity and mortality in the developed countries with posttraumatic epilepsy and functional disability being its major sequelae. The purpose of this study was to test the hypothesis whether the normal appearing adjacent gray and white matter regions on T...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(03)00189-9
更新日期：2003-10-01 00:00:00
abstract：:Dysfunction of the corticolimbic circuitry has been highlighted in social anxiety disorder (SAD) during social stimuli. However, few studies have investigated functional connectivity in SAD during the resting state, which may improve our understanding of SAD pathophysiology. The aim of this study was to investigate wh...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2011.02.013
更新日期：2011-06-01 00:00:00
abstract：BACKGROUND:Blood-oxygen-level-dependent (BOLD) magnetic resonance imaging (MRI) can provide regional measurements of oxygen content using deoxyhemoglobin paramagnetic characteristics. The apparent relaxation rate or R2*(=1/T2*) can be determined from the slope of log (intensity) versus echo time and is directly proport...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2011.10.003
更新日期：2012-04-01 00:00:00
abstract：:To assess whether magnetic resonance imaging could assist in diagnosing Ewing sarcoma, we retrospectively analyzed T1- and T2-weighted images of 24 consecutive solitary lytic bone lesions, including 18 cases of histologically proven Ewing sarcoma, and six aggressive-appearing benign lesions including eosinophilic gran...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(94)92450-3
更新日期：1994-01-01 00:00:00
abstract：:Collagen fibers in tendons and entheses are highly ordered. The protons within the bound water are subject to dipolar interactions whose strength depends on the orientation of the fibers to the static magnetic field B(0). Clinical pulse sequences have been employed to investigate this magic angle effect of the Achille...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2008.09.003
更新日期：2009-05-01 00:00:00
abstract：PURPOSE:Only a few studies have investigated the brain morphology abnormalities in structural MRI in patients with drug-naïve idiopathic generalized epilepsy (IGE) and mainly focused on brain volume changes. In the present study, we aimed to investigate the changes in three morphologic measurement differences including...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2019.05.035
更新日期：2019-09-01 00:00:00
abstract：:A dextran-Gd-DTPA compound has been recently synthesized utilizing 70,800 Da molecular weight dextran. This polymeric contrast agent for magnetic resonance imaging has been found chemically to be very stable and to demonstrate in vitro improved relaxivities of 1.5 to 2.3 times that of monomeric Gd-DTPA at 100 MHz. Thi...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(92)90515-2
更新日期：1992-01-01 00:00:00
abstract：:Manganese-dipyridoxal diphosphate (Mn-DPDP) is a liver-selective contrast agent selectively taken up by the hepatocytes. Because of the analogy of structure with pyridoxine (vitamin B6), it was previously suggested that this compound can be selectively taken up by the facilitated transport of vitamers B6. To understan...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(96)00140-3
更新日期：1996-01-01 00:00:00
abstract：:New methods for acquiring and processing gradient NMR well log data enable signals from gas, light oil, and water to be unambiguously separated and, in many cases, quantified. These methods exploit the combined effects of T1-based and diffusion-based contrast on log response. T1 contrast, which separates the water and...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/s0730-725x(96)00162-2
更新日期：1996-01-01 00:00:00
abstract：:Fast magnetic resonance (MR) imaging provides a consistent and predictable appearance of vascular abnormalities as shown by four patients with thrombi, dissection and aneurysm. Fast MR images are obtained during breath-holding, resulting in an absence of respiratory motion artifacts. The time of MR study is much less ...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(88)90483-3
更新日期：1988-07-01 00:00:00
abstract：PURPOSE:Time-of-flight (ToF) and phase contrast (PC) magnetic resonance angiographies (MRAs) are noninvasive applications to depict the cerebral arteries. Both approaches can image the cerebral vasculature without the administration of intravenous contrast. Therefore, it is used in routine clinical evaluation of cerebr...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2012.10.023
更新日期：2013-05-01 00:00:00
abstract：:The objective of this study was to determine the value of magnetic resonance (MR) imaging in diagnosing local recurrence of Ewing sarcoma. We retrospectively reviewed radiographs, Tc99m-methylene diphosphonate (MDP) skeletal scintigraphy, computed tomography scans, and MR studies of 11 patients who had local recurrenc...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(94)90079-7
更新日期：1994-01-01 00:00:00
abstract：:The phase difference method of phase contrast MR angiography provides a means of measuring the average velocity in each voxel of an MR scan. When static tissue is present in a voxel containing flow, the measured velocity is not the average velocity of the flow alone, but is lower due to the partial volume effect of th...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(94)91245-r
更新日期：1994-01-01 00:00:00
abstract：:Fifteen patients with liver cirrhosis and two control groups were examined. The first control group consisted of 7 healthy volunteers, and the second group of 17 patients with nonfocal liver diseases. The T1 and T2 relaxation times were calculated from signal intensities read out from a region of interest centrally lo...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章,评审
doi：10.1016/0730-725x(90)90137-q
更新日期：1990-01-01 00:00:00
abstract：:The objective of this study was to analyze regional variations of magnetic resonance (MR) relaxation times (T1ρ and T2) in hip joint cartilage of healthy volunteers and subjects with femoral acetabular impingement (FAI). Morphological and quantitative images of the hip joints of 12 healthy volunteers and 9 FAI patient...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2013.01.009
更新日期：2013-09-01 00:00:00
abstract：:Ten patients with biopsy-proved synovial sarcoma were evaluated by magnetic resonance (MR) imaging on a 1.5-T unit. The lesions showed intermediate signal intensity on T1-weighted images and heterogeneous high signal intensity on T2-weighted images. Tumors were well-demarcated from normal tissues. Additional informati...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/0730-725x(89)90706-6
更新日期：1989-03-01 00:00:00
abstract：:Parallel excitation using multiple transmit channels has emerged as an effective method to shorten multidimensional spatially selective radiofrequency (RF) pulses, which have a number of important applications, including B1 field inhomogeneity correction in high-field MRI. The specific absorption rate (SAR) is a prima...
journal_title：Magnetic resonance imaging
pub_type： 杂志文章
doi：10.1016/j.mri.2008.02.003
更新日期：2008-10-01 00:00:00
