Dataset Information

General design approach and practical realization of decoupling matrices for parallel transmission coils.

ABSTRACT: In a coupled parallel transmit (pTx) array, the power delivered to a channel is partially distributed to other channels because of coupling. This power is dissipated in circulators resulting in a significant reduction in power efficiency. In this study, a technique for designing robust decoupling matrices interfaced between the RF amplifiers and the coils is proposed. The decoupling matrices ensure that most forward power is delivered to the load without loss of encoding capabilities of the pTx array.The decoupling condition requires that the impedance matrix seen by the power amplifiers is a diagonal matrix whose entries match the characteristic impedance of the power amplifiers. In this work, the impedance matrix of the coupled coils is diagonalized by a successive multiplication by its eigenvectors. A general design procedure and software are developed to generate automatically the hardware that implements diagonalization using passive components.The general design method is demonstrated by decoupling two example parallel transmit arrays. Our decoupling matrices achieve better than -20 db decoupling in both cases.A robust framework for designing decoupling matrices for pTx arrays is presented and validated. The proposed decoupling strategy theoretically scales to any arbitrary number of channels. Magn Reson Med 76:329-339, 2016. © 2015 Wiley Periodicals, Inc.

SUBMITTER: Mahmood Z

PROVIDER: S-EPMC4733602 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

General design approach and practical realization of decoupling matrices for parallel transmission coils.

Mahmood Zohaib Z McDaniel Patrick P Guérin Bastien B Keil Boris B Vester Markus M Adalsteinsson Elfar E Wald Lawrence L LL Daniel Luca L

Magnetic resonance in medicine 20150731 1

<h4>Purpose</h4>In a coupled parallel transmit (pTx) array, the power delivered to a channel is partially distributed to other channels because of coupling. This power is dissipated in circulators resulting in a significant reduction in power efficiency. In this study, a technique for designing robust decoupling matrices interfaced between the RF amplifiers and the coils is proposed. The decoupling matrices ensure that most forward power is delivered to the load without loss of encoding capabili ...[more]

PMID: 26228386

Similar Datasets

Project description:There is significant evidence that patients with acute eye symptoms are poorly assessed in primary care. There is a tendency to diagnose viral or bacterial conjunctivitis in any acutely red eye. This has led to delays in treatment and in some cases, permanent loss of sight. The aim of this project was to improve acute eye consultations within the Birchwood Medical Practice. The project focused on the "red flag" findings that would identify patients who require referral for same-day ophthalmology assessment. A retrospective baseline audit was carried out on all cases read-coded "conjunctivitis" over the period of one year. Initially, only 2.8% of consultations had documented all four findings. By considering the main factors that lead to poor eye assessments, two main areas for improvement were identified. These were education (reinforced with memory aids) and improving the availability of eye examination equipment within each consultation room. An "eye examination kit" was developed with the needs of the general practitioner in mind. The practice was re-audited six weeks following the intervention. Consultations where all four red flag findings were documented rose from 2.8% to 50%. This was found to be a statistically significant difference (p < 0.01). Pain was checked 63% of the time, compared to 26% prior to intervention. Visual acuity screening had increased to from 35% to 69%. Photophobia was the most significantly increased metric, from being documented only 6% of the time to now 63% of the time. Documentation of whether the symptoms were unilateral or bilateral had also increased from 88% to 94% of consultations. The initial audit indicated that general practitioners often diagnosed conjunctivitis without screening for symptoms of sight-threatening disease. However, it was clear from the results that the doctors had made a significant change to their approach to acute eye consultations. This shows that doctors are willing to make changes to their behaviour when given the right tools and information. It was felt that a first-hand understanding of the problem and an open discussion regarding the changes required was key to the success of this project. This project has shown that significant improvements can be achieved with practical and inexpensive interventions. Therefore, general practices throughout the UK are encouraged to adopt similar strategies to improve the identification of patients needing same-day Ophthalmology assessment.

Dataset Information

General design approach and practical realization of decoupling matrices for parallel transmission coils.

Publications

General design approach and practical realization of decoupling matrices for parallel transmission coils.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets