Optimization of biplanar gradient coils for magnetic resonance imaging

Tomasi, Dardo

doi:10.1590/s0103-97332006000100007

Cited by 8 publications

(5 citation statements)

References 14 publications

(28 reference statements)

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“…Planar gradient coils provide an interest to researchers due to their ability to be separated and also because the DSV contained between the plates is more accessible (87)(88)(89)(90)(91)(92)(93)(94)(95)(96). The DSV is the region in which a quality image can be obtained and it should be as large as possible for a given plate size.…”

Section: Planar Gradient Coilsmentioning

confidence: 99%

Theory of gradient coil design methods for magnetic resonance imaging

Hidalgo-Tobón

2010

Concepts Magnetic Resonance

128

104

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The process to produce an MR image includes nuclear alignment, RF excitation, spatial encoding, and image formation. In simple terms, an magnetic resonance imaging (MRI) system consists of five major components: a magnet, gradient systems, an RF coil system, a receiver, and a computer system. To form an image, it is necessary to perform spatial localization of the MR signals, which is achieved using gradient coils. In modern MRI, gradient coils able to generate high gradient strengths and slew rates are required to produce high imaging speeds and improved image quality. MRI also requires the use of gradient coils that generate magnetic fields, which vary linearly with position over the imaging volume. Gradient coils for MRI must therefore have high current efficiency (defined as the ratio of gradient generated to current drawn), short switching time (i.e., low inductance), gradient linearity over a large volume, low power consumption, and minimal interaction with any other equipment, which would otherwise result in eddy currents. Over the last two decades new methods of gradient coil design have been developed, and a combination of these methods can be a mixture of them trying to avoid discomforts to patients that at the end is the center of all the technological efforts in the art of MRI.

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Section: Planar Gradient Coilsmentioning

confidence: 99%

Theory of gradient coil design methods for magnetic resonance imaging

Hidalgo-Tobón

2010

Concepts Magnetic Resonance

128

104

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“…To this end, it can be shown that for a 3D Gaussian function the variance must scale by the inverse cube-root of the amplitude (see [46]). Applying the Gaussian filter (22) to the density map (20) produces an updated density map and the next streamline is seeded at the location corresponding to the maximum of this new density map. The entire process is repeated continuously, whereby the density map is successively lowered with each additional streamline, until the maximum of the updated density map falls below some threshold.…”

Section: Obtaining 3d Coil Windings and Calculating Coil Performancementioning

confidence: 99%

“…Additionally, coils of finite extent may be obtained by considering, for example, Fourier series representation for the current density [16][17][18][19]. Alternatively, it is also possible to design both cylindrical and biplanar gradient coil sets using coil-space optimisation strategies such as simulated annealing (see for example, [20][21][22]). …”

Section: Introductionmentioning

confidence: 99%

3D gradient coil design for open MRI systems

While

Forbes

Crozier

2010

Journal of Magnetic Resonance

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“…In planar gradient coil geometry, the y ‐gradient has two fingerprint winding patterns along the z ‐axis with current flowing clockwise on one loop and counterclockwise on the other loop. Unlike cylindrical gradient coils where the x ‐gradient pattern can be obtained with a 90° rotation of the y ‐gradient, the x ‐gradient for planar gradient coils is achieved with windings that are laid out as a 2 × 2 fingerprint pattern on each plane with current flowing clockwise and counterclockwise alternatively (10–20).…”

Section: Theorymentioning

confidence: 99%

Pediatric and Adult Interventional Cardiac Symposium (PICS/AICS 2010)

2010

Cathet Cardio Intervent

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Introduction: Pulmonary artery (PA) rehabilitation is one of the most common procedures performed in the cardiac catheterization laboratory, but solid data on procedure-related adverse events (AE) is scarce with most studies reporting small retrospective, single center experiences. Methods: Data was prospectively collected using a multi-center registry (C3PO). Between 02/07 and 12/09, 8 institutions submitted details on 1315 procedures (proc) that included either balloon angioplasty or stent implantation within a proximal or lobar branch PA. Results: The majority of patients (pts) had either complex 2-ventricle circulation (71%), or single-ventricle physiology (22%). The median age was 3.5 years (1d -70yr). Out of 2894 PA intervention, balloon angioplasty was performed in 51% (>8Atm in 34%), cutting balloon angioplasty in 14%, stent-angioplasty in 14%, and stent implantation in 21%. Procedures included interventions on proximal PAs in 60%, lobar branches in 17%, or both in 23%. Four or more PA lesions were treated in 9% proc. 81% of cutting balloons were used in lobar branches, whereas 82% of all stents were used in proximal branch PAs. Additional interventions were performed in 38% proc. Out of 324 total AE 53% were observed in 815 proc without additional cath interventions: No more than minor AE were documented in 9% proc; moderate/major/ catastrophic (level 3-5) AE were documented in 9% proc. 0.1% patients died as a direct result of the procedure. Type of AE included arrhythmias (16%), hypoxia or hypotension (10%), bleed via ET tube/reperfusion injury (16%), vascular trauma/tear/ aneurysm (19%), balloon rupture/stent migration/ malposition and stentrelated problems (14%), AE at vascular entry site (9%), and other AE (16%). AE were classified as not preventable in 49%, as possibly preventable in 43%, and as preventable in 8%. Factors associated with an increased incidence of level 3-5 AE included age <1 month (31% vs. 10%), date since last surgery <30 days (22% vs. 9%), number of treated lesions >4 (20% vs. 9%). There was a trend for increased risk of AE in pts with complex 2-ventricle and suprasystemic RV (21% vs. 14%). The incidence of level 3-5 AE was not related to weight, use of inotropes at start, location (proximal/lobar) and single vs. complex 2v. Conclusion: PA rehab is associated with not insignificant morbidity. Neonates, early postop period, and multi-level rehab are risk factors for level 3-5 AE.Background: Transcatheter treatment of many congenital and structural heart defects became the method of treatment. Recently new device -Cardio-O-Fix (COF) was introduced into clinical practice. Methods: Five patients aged 0,5 -69 years were included to the study -2 with ASD, 1 with PFO and cryptogenic stroke, and 2 with PDA (one 6 months old infant with additional hypertrophied cardiomyopathy, and 53 y old women after previous ligation of PDA with its recanalization). All were treated percuatneously with Cardio-O-Fix Occluders. There were no preliminary patient selection -the only limitation was the size o...

show abstract

Optimization of biplanar gradient coils for magnetic resonance imaging

Cited by 8 publications

References 14 publications

Theory of gradient coil design methods for magnetic resonance imaging

Theory of gradient coil design methods for magnetic resonance imaging

3D gradient coil design for open MRI systems

Pediatric and Adult Interventional Cardiac Symposium (PICS/AICS 2010)

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