scholarly journals Controlling motion artefact levels in MR images by suspending data acquisition during periods of head motion

2018 ◽  
Vol 80 (6) ◽  
pp. 2415-2426 ◽  
Author(s):  
Rémi Castella ◽  
Lionel Arn ◽  
Estelle Dupuis ◽  
Martina F. Callaghan ◽  
Bogdan Draganski ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Head Motion ◽  
Mr Images ◽  
Motion Artefact

scholarly journals Controlling motion artefact levels in MR images by suspending data acquisition during periods of head motion

2017 ◽  
Author(s):  
Rémi Castella ◽  
Lionel Arn ◽  
Estelle Dupuis ◽  
Martina F. Callaghan ◽  
Bogdan Draganski ◽  
...  
Keyword(s):  
Data Quality ◽  
Data Acquisition ◽  
Motion Correction ◽  
Head Movements ◽  
Head Motion ◽  
Motion Artefacts ◽  
Motion Artefact ◽  
Position Information ◽  
Trade Off ◽  
Scan Time

AbstractHead movements are a major source of MRI artefacts that hamper radiological assessment and computer-based morphological and functional measures of the human brain. Prospective motion correction techniques continuously update the MRI scanner based on head position information provided by an external tracking system. While prospective motion correction significantly improves data quality, strong motion artefacts may remain with large head motions or when motion takes place at sensitive times of the acquisition. Here we present a framework that allows the suspension of data acquisition when head motion is predicted to have a strong negative impact on data quality. The predictor, calculated in real-time during the acquisition, accounts for the amplitude of the signal acquired at the time of the motion, thereby offering a re-acquisition strategy more efficient than relying on head speed alone. The suspension of data acquisition is governed by the trade-off between image degradation due to motion and prolonging the scan time. This trade-off can be tuned by the user according to the desired level of image quality and the participant‘s tolerability. We test the framework using two motion experiments and two head coils. Significant improvements in data quality are obtained with stringent threshold values for the suspension of acquisition. Substantial reductions in motion artefact levels are also achieved with minimal prolongation of scan time. However, high levels of motion artefacts occasionally remain despite stringent thresholds with the 64-channel head coil, an effect that might be attributed to head movement in the sharp sensitivity profile of this coil.

K-space filter effect in three-dimensional contrast MR angiography

1997 ◽  
Vol 38 (1) ◽  
pp. 173-175 ◽  
Author(s):  
K. Ito ◽  
J. Kato ◽  
S. Okada ◽  
T. Kumazaki
Keyword(s):  
Contrast Agent ◽  
Data Acquisition ◽  
Mr Angiography ◽  
Three Dimensional ◽  
Mr Images ◽  
Acquisition Period ◽  
Filter Effect ◽  
Flowing Material ◽  
Space Filter

Purpose: In three-dimensional (3-D) contrast MR angiography, temporal misregistration between the data acquisition period and the arrival of the contrast agent in the target vessels is thought to degrade the quality of the reconstructed images. The purpose of this study was to demonstrate and investigate this effect in phantom experiments. Material and Methods: MR images of a phantom tube were evaluated with flowing materials of water or Gd-DTPA solution by changing from water to Gd-DTPA solution halfway through the data acquisition period. Results: While no signal could be acquired with a stream of water in the tube, a clear signal was obtained with a flow of Gd-DTPA solution. Blurring and ghost artifacts surrounding the tube along the phase-encoding direction were observed when the flowing material was changed from water to Gd-DTPA solution halfway through the data acquisition period. Conclusion: K-space filter effect occurs during 3-D contrast MR angiography owing to the transient passage of the contrast agent, and this effect causes spatial artifacts in the reconstructed images.

scholarly journals Head motion during fMRI tasks is reduced in children and adults if participants take breaks

2019 ◽  
Author(s):  
Tobias W. Meissner ◽  
Jon Walbrin ◽  
Marisa Nordt ◽  
Kami Koldewyn ◽  
Sarah Weigelt
Keyword(s):  
Data Acquisition ◽  
Time Lag ◽  
Task Engagement ◽  
Fmri Data ◽  
Head Motion ◽  
List Type ◽  
Positive Effects ◽  
Scan Time ◽  
Pediatric Neuroimaging ◽  
Child Friendly

AbstractHead motion remains a challenging confound in functional magnetic resonance imaging (fMRI) studies of both children and adults. Most pediatric neuroimaging labs have developed experience-based, child-friendly standards concerning e.g. the maximum length of a session or the time between mock scanner training and actual scanning. However, it is unclear which factors of child-friendly neuroimaging approaches are effective in reducing head motion. Here, we investigate three main factors including (i) time lag of mock scanner training to the actual scan, (ii) prior scan time, and (iii) task engagement in a dataset of 77 children (aged 6-13) and 64 adults (aged 18-35) using a multilevel modeling approach. In children, distributing fMRI data acquisition across multiple same-day sessions reduces head motion. In adults, motion is reduced after inside-scanner breaks. Despite these positive effects of splitting up data acquisition, motion increases over the course of a study as well as over the course of a run in both children and adults. Our results suggest that splitting up fMRI data acquisition is an effective tool to reduce head motion in general. At the same time, different ways of splitting up data acquisition benefit children and adults.HighlightsIn children, fMRI data acquisition split into multiple sessions reduces head motionIn adults, fMRI data acquisition split by inside-scanner breaks reduces head motionIn both children and adults, motion increases over the duration of a studyIn both children and adults, motion increases over the duration of a run

scholarly journals MR-PET head motion correction based on co-registration of multi-contrast MR images

2018 ◽  
Author(s):  
Zhaolin Chen ◽  
Francesco Sforazzini ◽  
Jakub Baran ◽  
Thomas Close ◽  
N. Jon Shah ◽  
...  
Keyword(s):  
Motion Correction ◽  
Estimation Method ◽  
Correction Method ◽  
Head Motion ◽  
Mr Images ◽  
Image Sharpness ◽  
Positron Emission ◽  
Quantitative Accuracy ◽  
Slow Infusion ◽  
Pet Image Reconstruction

AbstractHead motion is a major source of image artefacts in neuroimaging studies and can lead to degradation of the quantitative accuracy of reconstructed PET images. Simultaneous Magnetic Resonance-Positron Emission Tomography (MR-PET) makes it possible to estimate head motion information from high-resolution MR images and then correct motion artefacts in PET images. In this paper, we introduce a fully automated PET motion correction method, MR-guided MAF, based on the co-registration of multi-contrast MR images. The performance of the MR-guided MAF method was evaluated using MR-PET data acquired from a cohort of ten healthy participants who received a slow infusion of fluorodeoxyglucose ([18-F]FDG). Compared with conventional methods, MR guided PET image reconstruction can reduce head motion introduced artefacts and improve the image sharpness and quantitative accuracy of PET images acquired using simultaneous MR-PET scanners. The fully automated motion estimation method has been implemented as a publicly available web-service.

scholarly journals MR-PET head motion correction based on co-registration of multicontrast MR images

2019 ◽  
Author(s):  
Zhaolin Chen ◽  
Francesco Sforazzini ◽  
Jakub Baran ◽  
Thomas Close ◽  
Nadim Jon Shah ◽  
...  
Keyword(s):  
Motion Correction ◽  
Head Motion ◽  
Mr Images

scholarly journals Comparison of Brain MR Images at 1.5T Using BLADE and Rectilinear Techniques for Patients Who Move during Data Acquisition

2011 ◽  
Vol 33 (1) ◽  
pp. 77-82 ◽  
Author(s):  
E. Nyberg ◽  
G.S. Sandhu ◽  
J. Jesberger ◽  
K.A. Blackham ◽  
D.P. Hsu ◽  
...  
Keyword(s):  
Data Acquisition ◽  
Mr Images ◽  
Brain Mr Images
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