32‐channel 3 Tesla receive‐only phased‐array head coil with soccer‐ball element geometry

Wiggins, Graham C.; Triantafyllou, Christina; Potthast, Andreas; Reykowski, Arne; Nittka, M.; Wald, Lawrence L.

doi:10.1002/mrm.20925

Cited by 346 publications

(360 citation statements)

References 15 publications

(10 reference statements)

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“…In the averaged values, a maximum SNR gain of a factor of 17.7 in the region close to the loops and a minimum of 3.7 in the centered slice can be observed. Although these values are much higher than expected (19)(20)(21), they are reasonable when the coil properties are …”

Section: Snr Comparisonmentioning

confidence: 48%

Design and evaluation of a 32‐channel phased‐array coil for lung imaging with hyperpolarized 3‐helium

Meise

Rivoire

Terekhov

et al. 2010

Magnetic Resonance in Med

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Imaging with hyperpolarized 3-helium is becoming an increasingly important technique for MRI diagnostics of the lung but is hampered by long breath holds (>20 sec), which are not always applicable in patients with severe lung disease like chronic obstructive pulmonary disease (COPD) or a-1-anti-trypsin deficiency. Additionally, oxygen-induced depolarization decay during the long breath holds complicates interpretation of functional data such as apparent diffusion coefficients. To address these issues, we describe and validate a 1.5-T, 32-channel array coil for accelerated 3 He lung imaging and demonstrate its ability to speed up imaging 3 He. A signal-to-noise ratio increase of up to a factor of 17 was observed compared to a conventional double-resonant birdcage for unaccelerated imaging, potentially allowing increased image resolution or decreased gas production requirements. Accelerated imaging of the whole lung with one-dimensional and two-dimensional acceleration factors of 4 and 4 3 2, respectively, was achieved while still retaining excellent image quality. Key words: MRI; parallel imaging; helium; lung; phased array coil Lung imaging using hyperpolarized 3 He has received increased attention in the last several years for studying lung diseases (1-12). So far, functional imaging, e.g., the apparent diffusion coefficient (ADC) or methods to observe the microstructure of the lung (12,13), requires long breath holds (up to 30 sec), which are the main barrier to applying this technology to patients with severe lung disease. Improvements in array coil methodology are a promising approach for increasing signal-to-noise ratio (SNR) and allowing significant acceleration of the image-encoding process. Lee et al. (14,15) presented a 24-channel array and later a 128-channel array for 3 He imaging, which demonstrated the feasibility of this approach. The acceleration afforded by parallel imaging is particularly important for hyperpolarized gas imaging since the nonequilibrium state of the magnetization allows faster imaging, often without incurring the standard SNR penalty proportional to the square root of imaging time (16). To analyze the improvements of these techniques in more detail, a 32-channel phased array was designed and built. For comparison, imaging protocols such as used in the European Community Framework V project ''Polarized Helium Imaging of the Lung'' were applied, as well as newly developed protocols, which utilize the extra sensitivity of the array. The sensitivity improvements were compared to a single-channel volume coil and the benefits of parallel imaging for lung diagnostics were analyzed by theoretical geometry-factor (g-factor) maps for the array and demonstrated in accelerated imaging. MATERIALS AND METHODS CoilsThe phased-array coil (Fig. 1) consists of 32 loops mounted on a clamshell former, which was presented by Schmitt et al. (17) for cardiac imaging. The 32 receive elements were milled from 35-lm copper-plated 1.5mm-thick FR4 circuit board material and arranged in two groups of 16 ele...

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Section: Snr Comparisonmentioning

confidence: 48%

Design and evaluation of a 32‐channel phased‐array coil for lung imaging with hyperpolarized 3‐helium

Meise

Rivoire

Terekhov

et al. 2010

Magnetic Resonance in Med

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“…Although the individual elements are smaller, they are much closer to the tissue, resulting in higher signal per channel. Consequently, the recent introduction of 32 channel receive coils on 3T and 7T systems will further improve SNR (21).…”

Section: Snrmentioning

confidence: 99%

Signal to noise ratio and uncertainty in diffusion tensor imaging at 1.5, 3.0, and 7.0 Tesla

Polders

Leemans

Hendrikse

et al. 2011

Magnetic Resonance Imaging

121

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Purpose: To compare diffusion tensor imaging (DTI) measurements at ultra high field strength (7 Tesla [T]) in human volunteers with DTI measurements performed at 1.5 and 3 Tesla. Materials and Methods:The signal to noise ratio (SNR) and the uncertainty in fitted DTI parameters fractional anisotropy and primary eigenvector are assessed with tractography based regions of interest, measured in nine volunteers at 1.5T, 3T, and 7T with clinically available hardware configurations.Results: An increase in SNR is observed on the 7T system compared with the 1.5 or 3T system. The measured increase in SNR at 7T is larger than expected from field strength alone, indicating the large influence of improved receive coil hardware. Additionally, while the average fractional anisotropy remains relatively constant across field strengths, a decrease in uncertainty in the fitted values for fractional anisotropy and the principal eigenvector of the DTI tensor was found. Increased spatial heterogeneity of signal intensities is observed at 7T.Conclusion: Given the current hardware constraints, DTI at ultra-high field strengths is possible with improved performance in selected regions of interest.

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“…We used a custom-built 32-channel head array receive coil (Wiggins et al, 2006) and a body transmit coil. The array consisted of 32 circular surface coils tessellated evenly to cover the whole brain.…”

Section: Image Data Acquisitionmentioning

confidence: 99%

“…Increasing the number of channels can thus increase MRI sampling rates. To this end, dense head coil arrays consisting of 16 de Zwart et al, 2002;de Zwart et al, 2004), 23, 32 and 90 elements (Wiggins et al, 2005a;Wiggins et al, 2005b) have been constructed in support of a range of parallel acquisition applications. In addition, a dedicated 64-channel linear planar array has been developed to achieve 64-fold acceleration (McDougall and Wright, 2005).…”

Section: Introductionmentioning

confidence: 99%

Event-related single-shot volumetric functional magnetic resonance inverse imaging of visual processing

et al. 2008

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Developments in multi-channel radio-frequency (RF) coil array technology have enabled functional magnetic resonance imaging (fMRI) with higher degrees of spatial and temporal resolution. While modest improvement in temporal acceleration has been achieved by increasing the number of RF coils, in parallel data acquisition techniques, the maximum attainable acceleration is intrinsically limited only by the amount of independent spatial information in the combined array channels. Since the geometric configuration of a large-n MRI head coil array is similar to that used in EEG electrode or MEG SQUID sensor arrays, the source localization algorithms used in MEG or EEG source imaging can be extended to also process MRI coil array data, resulting in greatly improved temporal resolution by minimizing k-space traversal during signal acquisition. Using a novel approach, we acquire multi-channel MRI head coil array data and then apply inverse reconstruction methods to obtain volumetric fMRI estimates of blood oxygenation level dependent (BOLD) contrast at unprecedented whole-brain acquisition rates of 100 ms per sample. We call this combination of techniques magnetic resonance Inverse Imaging (InI), a method that provides estimates of dynamic spatially-resolved signal change that can be used to construct statistical maps of task-related brain activity. We demonstrate the sensitivity and inter-subject reliability of volumetric InI using an eventrelated design to probe the hemodynamic signal modulations in primary visual cortex. Robust results from both single subject and group analyses demonstrate the sensitivity and feasibility of using volumetric InI in high temporal resolution investigations of human brain function.

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32‐channel 3 Tesla receive‐only phased‐array head coil with soccer‐ball element geometry

Cited by 346 publications

References 15 publications

Design and evaluation of a 32‐channel phased‐array coil for lung imaging with hyperpolarized 3‐helium

Design and evaluation of a 32‐channel phased‐array coil for lung imaging with hyperpolarized 3‐helium

Signal to noise ratio and uncertainty in diffusion tensor imaging at 1.5, 3.0, and 7.0 Tesla

Event-related single-shot volumetric functional magnetic resonance inverse imaging of visual processing

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