A local multi‐transmit coil combined with a high‐density receive array for cerebellar fMRI at 7 T

Priovoulos, Nikos; Roos, Thomas; Ipek, Özlem; Meliadò, Ettore F.; Nkrumah, Richard O.; Klomp, Dennis W. J.; Zwaag, Wietske van der

doi:10.1002/nbm.4586

Cited by 10 publications

(5 citation statements)

References 70 publications

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“…Finally, our current implementation employs hard rectangular pulses, trading off increased sensitivity to B 1 / B 0 inhomogeneities (Figure S2 ) for saturation efficiency. This may be problematic in areas like the frontal lobe or cerebellum (Priovoulos, Roos, et al, 2021 ). Adiabatic, pTX‐enabled, or off‐resonance RF pulses may offer a better tradeoff for high‐field application across the brain.…”

Section: Discussionmentioning

confidence: 99%

Combining arterial blood contrast with BOLD increases fMRI intracortical contrast

Priovoulos

Oliveira

Poser

et al. 2023

Human Brain Mapping

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BOLD fMRI is widely applied in human neuroscience but is limited in its spatial specificity due to a cortical‐depth‐dependent venous bias. This reduces its localization specificity with respect to neuronal responses, a disadvantage for neuroscientific research. Here, we modified a submillimeter BOLD protocol to selectively reduce venous and tissue signal and increase cerebral blood volume weighting through a pulsed saturation scheme (dubbed Arterial Blood Contrast) at 7 T. Adding Arterial Blood Contrast on top of the existing BOLD contrast modulated the intracortical contrast. Isolating the Arterial Blood Contrast showed a response free of pial‐surface bias. The results suggest that Arterial Blood Contrast can modulate the typical fMRI spatial specificity, with important applications in in‐vivo neuroscience.

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Section: Discussionmentioning

confidence: 99%

Combining arterial blood contrast with BOLD increases fMRI intracortical contrast

Priovoulos

Oliveira

Poser

et al. 2023

Human Brain Mapping

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“…Other parameters were: TR/TE 1–5 = 105 ms/6 ms, 14 ms, 22 ms, 30 ms, 38 ms, readout bandwidth = 131.4 Hz/pixel, FA = 16° (Raimondo, Priovoulos, et al, 2023 ). Data were acquired using two custom‐built high‐density 16‐channel surface coils arrays (total 32 channels) for signal reception (Petridou et al, 2013 ; Priovoulos et al, 2021 ) and the NOVA coil for transmission (Nova Medical, Wilmington, MA). The gradient coil has a maximum amplitude of 40 mT/m and a 200 T/m/s maximum slew rate.…”

Section: Methodsmentioning

confidence: 99%

“…Other parameters were: TR/TE 1-5 = 105 ms/6 ms, 14 ms, 22 ms, 30 ms, 38 ms, readout bandwidth = 131.4 Hz/pixel, FA = 16 (Raimondo, Priovoulos, et al, 2023). Data were acquired using two custom-built high-density 16-channel surface coils arrays (total 32 channels) for signal reception (Petridou et al, 2013;Priovoulos et al, 2021)…”

Section: Session 2-line-scanningmentioning

confidence: 99%

A selection and targeting framework of cortical locations for line‐scanning fMRI

Heij,

Raimondo,

Siero

et al. 2023

Human Brain Mapping

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Depth‐resolved functional magnetic resonance imaging (fMRI) is an emerging field growing in popularity given the potential of separating signals from different computational processes in cerebral cortex. Conventional acquisition schemes suffer from low spatial and temporal resolutions. Line‐scanning methods allow depth‐resolved fMRI by sacrificing spatial coverage to sample blood oxygenated level‐dependent (BOLD) responses at ultra‐high temporal and spatial resolution. For neuroscience applications, it is critical to be able to place the line accurately to (1) sample the right neural population and (2) target that neural population with tailored stimuli or tasks. To this end, we devised a multi‐session framework where a target cortical location is selected based on anatomical and functional properties. The line is then positioned according to this information in a separate second session, and we tailor the experiment to focus on the target location. Anatomically, the precision of the line placement was confirmed by projecting a nominal representation of the acquired line back onto the surface. Functional estimates of neural selectivities in the line, as quantified by a visual population‐receptive field model, resembled the target selectivities well for most subjects. This functional precision was quantified in detail by estimating the distance between the visual field location of the targeted vertex and the location in visual cortex (V1) that most closely resembled the line‐scanning estimates; this distance was on average ~5.5 mm. Given the dimensions of the line, differences in acquisition, session, and stimulus design, this validates that line‐scanning can be used to probe local neural sensitivities across sessions. In summary, we present an accurate framework for line‐scanning MRI; we believe such a framework is required to harness the full potential of line‐scanning and maximize its utility. Furthermore, this approach bridges canonical fMRI experiments with electrophysiological experiments, which in turn allows novel avenues for studying human physiology non‐invasively.

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“…Finally, cerebellum 7.0-T MRI frequently suffers from B 1 inhomogeneities, which were particularly evident in two participants in our study. Image quality can be further enhanced in future implementations using plug-and-play parallel transmit approaches (12).…”

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confidence: 99%

High-Resolution Motion-corrected 7.0-T MRI to Derive Morphologic Measures from the Human Cerebellum in Vivo

Priovoulos¹,

Andersen²,

Dumoulin³

et al. 2023

Radiology

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NEURORADIOLOGYT he human cerebellum has approximately one-eighth the volume of the neocortex but a cortical sheet with a similar surface area (1). The cerebellar cortex is a prevalent lesion site for various disease processes, including multiple sclerosis (2,3), spinocerebellar ataxias (4), and alcoholism (5).The cerebellar cortex has a regular circuit characterized by the granular cells (granular layer: 250-350 μm wide) that output to the Purkinje cells (Purkinje layer: 12 μm) through the parallel fibers (molecular layer: 250-350 μm). Beams of parallel fibers underlie the characteristic cerebellar mediolateral folds (500-1000 μm) (6). Despite its importance, this mesoscopic scale of the cerebellar architecture is underexamined in humans: Current in vivo techniques are limited to gross anatomic features, such as the main cortical branches, due to inadequate resolution (1). As a result, clinical measures successfully used in the cerebral cortex, such as cortical thickness, volume, and myeloarchitecture/function correlates, have not been applied with high fidelity in the cerebellum (1). This hinders examination of the cerebellum in disease.Herein, we combined methodologic advances in image acquisition and analysis to image the cerebellar cortex, including its foliations and lamination, with use of in vivo 7.0-T MRI to improve the signal-to-noise ratio and signal-to-noise efficiency. We modified two MRI pulse sequences targeted at imaging the cortical surface and intracortical lamination, respectively, to translate this higher signal-to-noise ratio to spatial resolution Background: The human cerebellum has a large, highly folded cortical sheet. Its visualization is important for various disorders, including multiple sclerosis and spinocerebellar ataxias. The derivation of the cerebellar cortical surface in vivo is impeded by its high foliation.Purpose: To image the cerebellar cortex, including its foliations and lamination, in less than 20 minutes, reconstruct the cerebellocortical surface, and extract cortical measures with use of motion-corrected, high-spatial-resolution 7.0-T MRI. Materials and Methods:In this prospective study, conducted between February 2021 and July 2022, healthy participants underwent an examination with either a 0.19 × 0.19 × 0.5-mm 3 , motion-corrected fast low-angle shot (FLASH) sequence (14.5 minutes) or a whole-cerebellum 0.4 × 0.4 × 0.4-mm 3 , motion-corrected magnetization-prepared 2 rapid gradient-echo (MP2RAGE) sequence (18.5 minutes) at 7.0 T. Four participants underwent an additional FLASH sequence without motion correction. FLASH and MP2RAGE sequences were used to visualize the cerebellar cortical layers, derive cerebellar gray and white matter segmentations, and examine their fidelity. Quantitative measures were compared using repeated-measures analyses of variance or paired t tests.Results: Nine participants (median age, 36 years [IQR, 25-42 years; range, 21-62 years]; five women) underwent examination with the FLASH sequence. Nine participants (median age, 37 years [IQR,[34][35...

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A local multi‐transmit coil combined with a high‐density receive array for cerebellar fMRI at 7 T

Cited by 10 publications

References 70 publications

Combining arterial blood contrast with BOLD increases fMRI intracortical contrast

Combining arterial blood contrast with BOLD increases fMRI intracortical contrast

A selection and targeting framework of cortical locations for line‐scanning fMRI

High-Resolution Motion-corrected 7.0-T MRI to Derive Morphologic Measures from the Human Cerebellum in Vivo

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