Fast Optimization of a Biplanar Gradient Coil Set

Tomasi, Dardo; Caparelli, Elisabeth de Castro; Panepucci, Horácio Carlos; Foerster, Bernd

doi:10.1006/jmre.1999.1832

Cited by 28 publications

(30 citation statements)

References 20 publications

(32 reference statements)

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“…[7], respectively. As shown in these figures, the optimization of stream functions results in coils producing larger HGV than those designed by our previous method [2].…”

Section: Resultsmentioning

confidence: 71%

“…Solid, dashed, and dotted lines correspond to the designs achieved in this work, Ref. [2], and Ref. [7], respectively.…”

Section: Resultsmentioning

confidence: 98%

“…The method described below is proposed for the design of self-shielded gradient sets with biplanar geometry [1,2]. In these gradient system, currents flow in four parallel (x, y)-planes: The primary current density flows in the two inner planes, placed at z = ±a, and the shielding current density flows in the two outer planes, placed at z = ±b (a ≤ b).…”

Section: Theorymentioning

confidence: 99%

“…For the transverse gradient coils, the return path of each wire in the primary planes is a wire in the shielding planes; these coils are similar to rectangular sandwiches formed by two rectangular solenoids of b − a thickness [2]. For inter-connections between the primary and shielding planes, b − a length wires along the z-axis were used to null the z-component of the magnetic field resulting from these segments.…”

Section: Discrete Current Distributionsmentioning

confidence: 99%

“…In these systems, the gap between pole tips is minimized in order to increase the magnetic field strength, B 0 , and the gradient coils need to fit restricted volumes and are located very close to metallic parts of the scanner. This proximity results in eddy currents that cause severe image artifacts, especially for fast imaging modalities such as echo-planar imaging (EPI) that can only be minimized by using self-shielded gradient coils [2][3].…”

Section: Introductionmentioning

confidence: 99%

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Optimization of biplanar gradient coils for magnetic resonance imaging

Tomasi

2006

Braz. J. Phys.

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"Open" magnetic resonance imaging (MRI) scanners are frequently based on electromagnets or permanent magnets, and require self-shielded planar gradient coils to prevent image artifacts resulting from eddy currents in metallic parts of the scanner. This work presents an optimization method for the development of self-shielded gradient coils with biplanar geometry for "Open" MRI scanners. Compared to other optimization methods, this simple approach results in coils that produce larger uniform gradient volumes, and have simple and scalable manufacture.

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“…[7], respectively. As shown in these figures, the optimization of stream functions results in coils producing larger HGV than those designed by our previous method [2].…”

Section: Resultsmentioning

confidence: 71%

“…Solid, dashed, and dotted lines correspond to the designs achieved in this work, Ref. [2], and Ref. [7], respectively.…”

Section: Resultsmentioning

confidence: 98%

Section: Theorymentioning

confidence: 99%

Section: Discrete Current Distributionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optimization of biplanar gradient coils for magnetic resonance imaging

Tomasi

2006

Braz. J. Phys.

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Stream function optimization for gradient coil design

Tomasi

2001

Magn. Reson. Med.

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This work presents a method applied to the design of short self‐shielded gradient coils of cylindrical geometry. The method uses a hybrid technique that combines the simulated annealing and target field methods to optimize the standard stream functions. The optimized stream functions were parameterized using a few degrees of freedom to reduce the computing time. The optima stream function parameters are given for easy coil design purposes. The proposed approach is compared to the target field method. The main advantage of the present method over the target field method is its ability to enlarge the homogeneous gradient volume. In addition, the designs of short coils based on this approach have shown lower inductance than the coil design based on the target field method. The fast‐simulated annealing technique presented in this work enables the gradient coil optimization in less than 3 min of computing time. Magn Reson Med 45:505–512, 2001. © 2001 Wiley‐Liss, Inc.

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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...

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Fast Optimization of a Biplanar Gradient Coil Set

Cited by 28 publications

References 20 publications

Optimization of biplanar gradient coils for magnetic resonance imaging

Optimization of biplanar gradient coils for magnetic resonance imaging

Stream function optimization for gradient coil design

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

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