Comparison of local and global arrays for MRI

Spence, D.K.; Wright, Steven M.

doi:10.1002/cmr.b.20088

Cited by 5 publications

(5 citation statements)

References 20 publications

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“…To increase the SNR gain of a target located deeply inside the body (e.g., the brain), increasing the size of the surface coils or the number of detector elements has proven to be of no particular benefit. For instance, a surface coil of 10 × 10 cm 2 provides lower SNR compared to a surface coil 1/4 of its size over a 3‐cm depth when the sample loss dominates (). Additionally, the results of another study exhibited similar sensitivity at a depth of 10 cm, although the configurations of the array were changed from 1 × 1 to 4 × 4 or 8 × 8 to cover the same area ().…”

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confidence: 99%

New design concept of monopole antenna array for UHF 7T MRI

et al. 2013

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confidence: 99%

New design concept of monopole antenna array for UHF 7T MRI

et al. 2013

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“…Keeping only the non-constant parameters for our situation we arrive at the commonly used simplified relation [14] …”

Section: Magnetic Resonance Imaging (Mri) and Signal-to-noise Ratio (mentioning

confidence: 99%

“…(3) and Eq. (4), students can derive these equations using the Biot-Savart law following the method in reference [14]. To understand the choice for optimal d l students can find the maximum of Eq.…”

Section: Extensions To the Laboratorymentioning

confidence: 99%

Birdcage volume coils and magnetic resonance imaging: a simple experiment for students

et al. 2017

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Background: This article explains some simple experiments that can be used in undergraduate or graduate physics or biomedical engineering laboratory classes to learn how birdcage volume radiofrequency (RF) coils and magnetic resonance imaging (MRI) work. For a clear picture, and to do any quantitative MRI analysis, acquiring images with a high signal-to-noise ratio (SNR) is required. With a given MRI system at a given field strength, the only means to change the SNR using hardware is to change the RF coil used to collect the image. RF coils can be designed in many different ways including birdcage volume RF coil designs. The choice of RF coil to give the best SNR for any MRI study is based on the sample being imaged. Results: The data collected in the simple experiments show that the SNR varies as inverse diameter for the birdcage volume RF coils used in these experiments. The experiments were easily performed by a high school student, an undergraduate student, and a graduate student, in less than 3 h, the time typically allotted for a university laboratory course. Conclusions: The article describes experiments that students in undergraduate or graduate laboratories can perform to observe how birdcage volume RF coils influence MRI measurements. It is designed for students interested in pursuing careers in the imaging field.

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“…In current clinical cardiac MR (CMR), integrated large volume body radiofrequency (RF) coils are commonly used for 1 H excitation together with close-fitting receive-only (RX) RF surface coil arrays [ 1 ]. The large-volume excitation with a body RF coil bodes well for a uniform transmission field (B 1 + -field) across the upper torso, which is nearly independent of the RF coil’s loading and the target region under investigation.…”

Section: Introductionmentioning

confidence: 99%

Local Multi-Channel RF Surface Coil versus Body RF Coil Transmission for Cardiac Magnetic Resonance at 3 Tesla: Which Configuration Is Winning the Game?

et al. 2016

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IntroductionThe purpose of this study was to demonstrate the feasibility and efficiency of cardiac MR at 3 Tesla using local four-channel RF coil transmission and benchmark it against large volume body RF coil excitation.MethodsElectromagnetic field simulations are conducted to detail RF power deposition, transmission field uniformity and efficiency for local and body RF coil transmission. For both excitation regimes transmission field maps are acquired in a human torso phantom. For each transmission regime flip angle distributions and blood-myocardium contrast are examined in a volunteer study of 12 subjects. The feasibility of the local transceiver RF coil array for cardiac chamber quantification at 3 Tesla is demonstrated.ResultsOur simulations and experiments demonstrate that cardiac MR at 3 Tesla using four-channel surface RF coil transmission is competitive versus current clinical CMR practice of large volume body RF coil transmission. The efficiency advantage of the 4TX/4RX setup facilitates shorter repetition times governed by local SAR limits versus body RF coil transmission at whole-body SAR limit. No statistically significant difference was found for cardiac chamber quantification derived with body RF coil versus four-channel surface RF coil transmission. Our simulation also show that the body RF coil exceeds local SAR limits by a factor of ~2 when driven at maximum applicable input power to reach the whole-body SAR limit.ConclusionPursuing local surface RF coil arrays for transmission in cardiac MR is a conceptually appealing alternative to body RF coil transmission, especially for patients with implants.

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Comparison of local and global arrays for MRI

Cited by 5 publications

References 20 publications

New design concept of monopole antenna array for UHF 7T MRI

New design concept of monopole antenna array for UHF 7T MRI

Birdcage volume coils and magnetic resonance imaging: a simple experiment for students

Local Multi-Channel RF Surface Coil versus Body RF Coil Transmission for Cardiac Magnetic Resonance at 3 Tesla: Which Configuration Is Winning the Game?

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