Single‐shot echo‐planar imaging with Nyquist ghost compensation: Interleaved dual echo with acceleration (IDEA) echo‐planar imaging (EPI)

Poser, Benedikt A.; Barth, Markus; Goa, Pål-Erik; Deng, Weiran; Stenger, V. Andrew

doi:10.1002/mrm.24222

Cited by 24 publications

(33 citation statements)

References 35 publications

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“…Additional rigorous fMRI analyses are needed to define more generalizable L -factor thresholds. Nevertheless, the observed leakage percentages, even at high MB factors remain comparable to typically observed in-plane EPI Nyquist ghosting levels, even at 7T (Poser et al, 2012; van der Zwaag et al, 2009). In addition, the L -factor could serve as a metric for evaluating different optimization strategies for the slice-GRAPPA kernel (Cauley et al, 2012; Setsompop and Wald, 2012).…”

Section: Discussionsupporting

confidence: 79%

Evaluation of slice accelerations using multiband echo planar imaging at 3T

et al. 2013

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We evaluate residual aliasing among simultaneously excited and acquired slices in slice accelerated multiband (MB) echo planar imaging (EPI). No in-plane accelerations were used in order to maximize and evaluate achievable slice acceleration factors at 3 Tesla. We propose a novel leakage (L-) factor to quantify the effects of signal leakage between simultaneously acquired slices. With a standard 32-channel receiver coil at 3 Tesla, we demonstrate that slice acceleration factors of up to eight (MB = 8) with blipped controlled aliasing in parallel imaging (CAIPI), in the absence of in-plane accelerations, can be used routinely with acceptable image quality and integrity for whole brain imaging. Spectral analyses of single-shot fMRI time series demonstrate that temporal fluctuations due to both neuronal and physiological sources were distinguishable and comparable up to slice-acceleration factors of nine (MB = 9). The increased temporal efficiency could be employed to achieve, within a given acquisition period, higher spatial resolution, increased fMRI statistical power, multiple TEs, faster sampling of temporal events in a resting state fMRI time series, increased sampling of q-space in diffusion imaging, or more quiet time during a scan.

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Section: Discussionsupporting

confidence: 79%

Evaluation of slice accelerations using multiband echo planar imaging at 3T

et al. 2013

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“…Finally, these findings are constrained to the measurement sequence and methods applied at both field strengths. Future developments in fast imaging may allow both the sensitivity and specificity of ultra-high field fMRI to be increased (Poser et al, 2013). …”

Section: Discussionmentioning

confidence: 99%

Comparing the Microvascular Specificity of the 3- and 7-T BOLD Response Using ICA and Susceptibility-Weighted Imaging

Geißler¹,

Fischmeister²,

Gräβner³

et al. 2013

Front. Hum. Neurosci.

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In functional MRI it is desirable for the blood-oxygenation level dependent (BOLD) signal to be localized to the tissue containing activated neurons rather than the veins draining that tissue. This study addresses the dependence of the specificity of the BOLD signal – the relative contribution of the BOLD signal arising from tissue compared to venous vessels – on magnetic field strength. To date, studies of specificity have been based on models or indirect measures of BOLD sensitivity such as signal to noise ratio and relaxation rates, and assessment has been made in isolated vein and tissue voxels. The consensus has been that ultra-high field systems not only significantly increase BOLD sensitivity but also specificity, that is, there is a proportionately reduced signal contribution from draining veins. Specificity was not quantified in prior studies, however, due to the difficulty of establishing a reliable network of veins in the activated volume. In this study we use a map of venous vessel networks extracted from 7 T high resolution Susceptibility-Weighted Images to quantify the relative contributions of micro- and macro-vasculature to functional MRI results obtained at 3 and 7 T. High resolution measurements made here minimize the contribution of physiological noise and Independent Component Analysis (ICA) is used to separate activation from technical, physiological, and motion artifacts. ICA also avoids the possibility of timing-dependent bias from different micro- and macro-vasculature responses. We find a significant increase in the number of activated voxels at 7 T in both the veins and the microvasculature – a BOLD sensitivity increase – with the increase in the microvasculature being higher. However, the small increase in sensitivity at 7 T was not significant. For the experimental conditions of this study, our findings do not support the hypothesis of an increased specificity of the BOLD response at ultra-high field.

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“…A final Nyquist ghost corrected image can be achieved by simply combining

I_{p}

and

I_{n}

as in the phased array ghost elimination (PAGE) method . However, the image SNR will decrease by the geometry factor (g‐factor) because SENSE is utilized to unalias the positive and negative echo images, separately.…”

Section: Methodsmentioning

confidence: 99%