scholarly journals Single‐shot spiral imaging at 7  T

2018 ◽  
Vol 80 (5) ◽  
pp. 1836-1846 ◽  
Author(s):  
Maria Engel ◽  
Lars Kasper ◽  
Christoph Barmet ◽  
Thomas Schmid ◽  
Laetitia Vionnet ◽  
...  
Keyword(s):  
Single Shot ◽  
Spiral Imaging

Single‐shot spiral imaging enabled by an expanded encoding model: D emonstration in diffusion MRI

2016 ◽  
Vol 77 (1) ◽  
pp. 83-91 ◽  
Author(s):  
Bertram J. Wilm ◽  
Christoph Barmet ◽  
Simon Gross ◽  
Lars Kasper ◽  
S. Johanna Vannesjo ◽  
...  
Keyword(s):  
Diffusion Mri ◽  
Single Shot ◽  
Spiral Imaging

scholarly journals Integration of a radiofrequency coil and commercial field camera for ultra-high-field MRI

2021 ◽  
Author(s):  
Kyle M Gilbert ◽  
Paul Dubovan ◽  
Joseph S Gati ◽  
Ravi S Menon ◽  
Corey A Baron
Keyword(s):  
High Field ◽  
Field Monitoring ◽  
Gradient Coil ◽  
Single Shot ◽  
Rf Coil ◽  
Space Trajectories ◽  
Ultra High Field ◽  
Spiral Imaging ◽  
Before And After ◽  
Commercial Field

Purpose: To develop an RF coil with an integrated commercial field camera for ultra-high field (7 T) neuroimaging. The RF coil will operate within a head-only gradient coil and be subject to the corresponding design constraints. The RF coil can thereafter be used for subject-specific correction of k-space trajectories-notably in gradient-sensitive sequences such as single-shot spiral imaging. Methods: The transmit and receive performance was evaluated before and after the integration of field probes, while field probes were evaluated when in an optimal configuration external to the coil and after their integration. Diffusion-weighted EPI and single-shot spiral acquisitions were employed to evaluate the efficacy of correcting higher order field perturbations and the consequent effect on image quality. Results: Field probes had a negligible effect on RF-coil performance, including the transmit efficiency, transmit uniformity, and mean SNR over the brain. Modest reductions in field-probe signal lifetimes were observed, caused primarily by non-idealities in the gradient and shim fields of the head-only gradient coil at the probe positions. The field monitoring system could correct up to second-order field perturbations in single-shot spiral imaging. Conclusion: The integrated RF coil and field camera was capable of concurrent field monitoring within a 7T head-only scanner and facilitated the subsequent correction of k-space trajectories during spiral imaging.

scholarly journals Advances in Spiral fMRI: A High-resolution Study with Single-shot Acquisition

2019 ◽  
Author(s):  
Lars Kasper ◽  
Maria Engel ◽  
Jakob Heinzle ◽  
Matthias Mueller-Schrader ◽  
Nadine N. Graedel ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Static Field ◽  
7 Tesla ◽  
List Type ◽  
Single Shot ◽  
Planar Imaging ◽  
Spatiotemporal Resolution ◽  
Signal Model ◽  
Spiral Imaging ◽  
Spiral Readout

AbstractSpiral fMRI has been put forward as a viable alternative to rectilinear echo-planar imaging, in particular due to its enhanced average k-space speed and thus high acquisition efficiency. This renders spirals attractive for contemporary fMRI applications that require high spatiotemporal resolution, such as laminar or columnar fMRI. However, in practice, spiral fMRI is typically hampered by its reduced robustness and ensuing blurring artifacts, which arise from imperfections in both static and dynamic magnetic fields.Recently, these limitations have been overcome by the concerted application of an expanded signal model that accounts for such field imperfections, and its inversion by iterative image reconstruction. In the challenging ultra-high field environment of 7 Tesla, where field inhomogeneity effects are aggravated, both multi-shot and single-shot 2D spiral imaging at sub-millimeter resolution was demonstrated with high depiction quality and anatomical congruency.In this work, we further these advances towards a time series application of spiral readouts, namely, single-shot spiral BOLD fMRI at 0.8 mm in-plane resolution. We demonstrate that spiral fMRI at 7 T is not only feasible, but delivers both competitive image quality and BOLD sensitivity, with a spatial specificity of the activation maps that is not compromised by artifactual blurring. Furthermore, we show the versatility of the approach with a combined in/out spiral readout at a more typical resolution (1.5 mm), where the high acquisition efficiency allows to acquire two images per shot for improved sensitivity by echo combination.HighlightsThis work reports the first fMRI study at 7T with spiral readout gradient waveforms.We achieve spiral fMRI with sub-millimeter resolution (0.8 mm, in-plane FOV 230 mm), acquired in a single shot.Spiral images exhibit intrinsic geometric congruency to anatomical scans, and spatially highly specific activation patterns.Image reconstruction rests on a signal model expanded by measured trajectories and static field maps, inverted by cg-SENSE.We assess generalizability of the approach for spiral in/out readouts, providing two images per shot (1.5 mm resolution).

Functional MRI of the human motor cortex using single-shot, multiple gradient-echo spiral imaging

1999 ◽  
Vol 17 (9) ◽  
pp. 1239-1243 ◽  
Author(s):  
Markus Barth ◽  
Alexander Metzler ◽  
Markus Klarhöfer ◽  
Stefan Röll ◽  
Ewald Moser ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Functional Mri ◽  
Single Shot ◽  
Gradient Echo ◽  
Spiral Imaging ◽  
Human Motor Cortex ◽  
Human Motor

scholarly journals Sensitivity-encoded single-shot spiral imaging for reduced susceptibility artifacts in BOLD fMRI

2002 ◽  
Vol 48 (5) ◽  
pp. 860-866 ◽  
Author(s):  
Markus Weiger ◽  
Klaas P. Pruessmann ◽  
Robert Österbauer ◽  
Peter Börnert ◽  
Peter Boesiger ◽  
...  
Keyword(s):  
Single Shot ◽  
Spiral Imaging ◽  
Susceptibility Artifacts ◽  
Bold Fmri

Nicht-kontrastverstärkte hochaufgelöste Quiescent Interval Single Shot 3-Tesla-MR-Angiografie bei Patienten mit fortgeschrittener peripherer arterieller Verschlusskrankheit

2014 ◽  
Vol 186 (S 01) ◽  
Author(s):  
K Thierfelder ◽  
G Meimarakis ◽  
K Nikolaou ◽  
WH Sommer ◽  
PM Kazmierczak ◽  
...  
Keyword(s):  
3 Tesla ◽  
Single Shot

Komplikationen und Wirkung der lumbalen SSPDA (single shot peridural analgesia) beim älteren Menschen

2003 ◽  
Vol 141 (S 1) ◽  
Author(s):  
C Ludwig ◽  
DP König ◽  
P Eysel
Keyword(s):  
Single Shot ◽  
Peridural Analgesia

Functional stereotactic radiosurgery involving a dedicated linear accelerator and gamma unit: a comparison study

2004 ◽  
pp. 373-380 ◽  
Author(s):  
Timothy D. Solberg ◽  
Steven J. Goetsch ◽  
Michael T. Selch ◽  
William Melega ◽  
Goran Lacan ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Linear Accelerator ◽  
Treatment Plan ◽  
Single Shot ◽  
Submillimeter Range ◽  
Primate Model ◽  
Content Type ◽  
Stereotactic Frame ◽  
Targeting Ability ◽  
Fine Print

Object. The purpose of this work was to investigate the targeting and dosimetric characteristics of a linear accelerator (LINAC) system dedicated for stereotactic radiosurgery compared with those of a commercial gamma knife (GK) unit. Methods. A phantom was rigidly affixed within a Leksell stereotactic frame and axial computerized tomography scans were obtained using an appropriate stereotactic localization device. Treatment plans were performed, film was inserted into a recessed area, and the phantom was positioned and treated according to each treatment plan. In the case of the LINAC system, four 140° arcs, spanning ± 60° of couch rotation, were used. In the case of the GK unit, all 201 sources were left unplugged. Radiation was delivered using 3- and 8-mm LINAC collimators and 4- and 8-mm collimators of the GK unit. Targeting ability was investigated independently on the dedicated LINAC by using a primate model. Measured 50% spot widths for multisource, single-shot radiation exceeded nominal values in all cases by 38 to 70% for the GK unit and 11 to 33% for the LINAC system. Measured offsets were indicative of submillimeter targeting precision on both devices. In primate studies, the appearance of an magnetic resonance imaging—enhancing lesion coincided with the intended target. Conclusions. Radiosurgery performed using the 3-mm collimator of the dedicated LINAC exhibited characteristics that compared favorably with those of a dedicated GK unit. Overall targeting accuracy in the submillimeter range can be achieved, and dose distributions with sharp falloff can be expected for both devices.

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