scholarly journals Inter-slice motion correction using spatiotemporal interpolation for functional magnetic resonance imaging of the moving fetus

2017 ◽  
Author(s):  
Wonsang You ◽  
Catherine Limperopoulos
Keyword(s):  
Magnetic Resonance Imaging ◽  
Experimental Data ◽  
Motion Correction ◽  
Motion Artifact ◽  
Motion Artifacts ◽  
Robust Method ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Spatiotemporal Interpolation ◽  
Fetal Motion

Fetal motion continues to be one of the major artifacts in in-utero functional MRI; interestingly few methods have been developed to address fetal motion correction. In this study, we propose a robust method for motion correction in fetal fMRI by which both inter-slice and inter-volume motion artifacts are jointly corrected. To accomplish this, an original volume is temporally split into odd and even slices, and then voxel intensities are spatially and temporally interpolated in the process of image registration. Our experimental data demonstrate that our method was more effective in correcting fetal motion artifact compared to traditional motion correction methods.

scholarly journals Gradual Restraint Habituation for Awake Functional Magnetic Resonance Imaging Combined With a Sparse Imaging Paradigm Reduces Motion Artifacts and Stress Levels in Rodents

2021 ◽  
Vol 15 ◽  
Author(s):  
Gabriele Russo ◽  
Xavier Helluy ◽  
Mehdi Behroozi ◽  
Denise Manahan-Vaughan
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Functional Magnetic Resonance Imaging ◽  
Acoustic Stimulation ◽  
Motion Artifacts ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Non Invasive ◽  
Stress Levels ◽  
Awake Rats

Functional magnetic resonance imaging, as a non-invasive technique, offers unique opportunities to assess brain function and connectivity under a broad range of applications, ranging from passive sensory stimulation to high-level cognitive abilities, in awake animals. This approach is confounded, however, by the fact that physical restraint and loud unpredictable acoustic noise must inevitably accompany fMRI recordings. These factors induce marked stress in rodents, and stress-related elevations of corticosterone levels are known to alter information processing and cognition in the rodent. Here, we propose a habituation strategy that spans specific stages of adaptation to restraint, MRI noise, and confinement stress in awake rats and circumvents the need for surgical head restraint. This habituation protocol results in stress levels during awake fMRI that do not differ from pre-handling levels and enables stable image acquisition with very low motion artifacts. For this, rats were gradually trained over a period of three weeks and eighteen training sessions. Stress levels were assessed by analysis of fecal corticosterone metabolite levels and breathing rates. We observed significant drops in stress levels to below pre-handling levels at the end of the habituation procedure. During fMRI in awake rats, after the conclusion of habituation and using a non-invasive head-fixation device, breathing was stable and head motion artifacts were minimal. A task-based fMRI experiment, using acoustic stimulation, conducted 2 days after the end of habituation, resulted in precise whole brain mapping of BOLD signals in the brain, with clear delineation of the expected auditory-related structures. The active discrimination by the animals of the acoustic stimuli from the backdrop of scanner noise was corroborated by significant increases in BOLD signals in the thalamus and reticular formation. Taken together, these data show that effective habituation to awake fMRI can be achieved by gradual and incremental acclimatization to the experimental conditions. Subsequent BOLD recordings, even during superimposed acoustic stimulation, reflect low stress-levels, low motion and a corresponding high-quality image acquisition. Furthermore, BOLD signals obtained during fMRI indicate that effective habituation facilitates selective attention to sensory stimuli that can in turn support the discrimination of cognitive processes in the absence of stress confounds.

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