Objective: As the MRI main magnetic field rises for improved signal-to-noise ratio, susceptibility-induced B0-inhomogeneity increases proportionally, aggravating related artifacts. Considering only susceptibility disparities between air and biological tissue, we explore the topological conditions for which perfect shimming could be performed in a Region of Interest (ROI) such as the human brain or part thereof.
Materials And Methods: After theoretical considerations for perfect shimming, spherical harmonic (SH) shimming simulations of very high degree are performed, based on a 100-subject database of 1.7-mm-resolved brain fieldmaps acquired at 3T . In addition to the whole brain, shimmed ROIs include slabs targeting the prefrontal cortex, both or single temporal lobes, or spheres in the frontal brain above the nasal sinus.
Results And Discussion: We show "perfect" SH shimming is possible only if the ROI can be contained in a sphere that does not enclose sources of magnetic field inhomogeneity, which are gathered at the air-tissue interface. We establish a [Formula: see text]Hz inhomogeneity hard shim limit at 7T for whole brain SH shimming, that can only be attained at shimming degree higher than 90. On the other hand, under limited power and SH degree resources, 3D region-specific shimming is shown to greatly improve homogeneity in critical zones such as the prefrontal cortex and around ear canals.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1007/s10334-022-01025-3 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Regulation of Dopamine Release by Tonic Activity Patterns in the Striatal Brain Slice.
ACS Chem Neurosci
January 2025
Departments of Psychiatry and Neurology, Division of Molecular Therapeutics, New York State Psychiatric Institute, Columbia University Medical Center, New York, New York 10032, United States.
Voluntary movement, motivation, and reinforcement learning depend on the activity of ventral midbrain neurons, which extend axons to release dopamine (DA) in the striatum. These neurons exhibit two patterns of action potential activity: low-frequency tonic activity that is intrinsically generated and superimposed high-frequency phasic bursts that are driven by synaptic inputs. acute striatal brain preparations are widely employed to study the regulation of evoked DA release but exhibit very different DA release kinetics than recordings.
View Article and Find Full Text PDF"The Brain is…": A Survey of the Brain's Many Definitions.
Neuroinformatics
January 2025
Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, 760 Westwood Plaza, Los Angeles, CA, 90024, USA.
A reader of the peer-reviewed neuroscience literature will often encounter expressions like the following: 'the brain is a dynamic system', 'the brain is a complex network', or 'the brain is a highly metabolic organ'. These expressions attempt to define the essential functions and properties of the mammalian or human brain in a simple phrase or sentence, sometimes using metaphors or analogies. We sought to survey the most common phrases of the form 'the brain is…' in the biomedical literature to provide insights into current conceptualizations of the brain.
View Article and Find Full Text PDFThe roles of vision and proprioception in spatial tuning of sensory attenuation.
Exp Brain Res
January 2025
Institute for Experimental Psychology, Heinrich Heine University Düsseldorf, 40225, Düsseldorf, Germany.
When we touch ourselves, the pressure appears weaker compared to when someone else touches us, an effect known as sensory attenuation. Sensory attenuation is spatially tuned and does only occur if the positions of the touching and the touched body-party spatially coincide. Here, we ask about the contribution of visual or proprioceptive signals to determine self-touch.
View Article and Find Full Text PDFMicrosurgical preservation of lenticulostriate artery perforators in insular glioma: the two point antegrade skeletonization technique.
Acta Neurochir (Wien)
January 2025
Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014, Uttar Pradesh, India.
Background: Reaching parenchymal segments of the lateral lenticulostriate artery (LSA) perforators, which represent the medial resection limit in insular gliomas (IG), remains a challenge. The currently described methods are indirect and sometimes, imprecise.
Methods: We report an antegrade direct skeletonization technique to identify these tiny arteries at the medial end of IGs with an illustrative case of grade 2 astrocytoma.
Early childhood stress and amygdala structure in children and adolescents with neurodevelopmental disorders.
Brain Struct Funct
January 2025
Applied Psychology, Faculty of Education, University of Western Ontario, 1137 Western Rd, London, ON, N6G 1G7, Canada.
Children and adolescents with neurodevelopmental disorders such as autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) may be more susceptible to early life stress compared to their neurotypical peers. This increased susceptibility may be linked to regionally-specific changes in the striatum and amygdala, brain regions sensitive to stress and critical for shaping maladaptive behavioural responses. This study examined early life stress and its impact on striatal and amygdala development in 62 children and adolescents (35 males, mean age = 10.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!