Large dynamic fluctuations of the static magnetic field (B(0)) are observed in the human body during MR scanning, compromising image quality and detection sensitivity in several MR imaging and spectroscopy sequences. Partially, these dynamic B(0) fluctuations are due to physiological motion such as breathing, but other sources of temporal B(0) field fluctuations are also present in the MR system (e.g., eddy currents). Especially at ultrahigh field (≥7 T), the increased susceptibility effects lead to large B(0) field variations over time. Direct measurement and correction of these temporal field variations of up to 70 Hz will lead to a significant reduction of artifacts and improved measurement stability/reproducibility. For direct measurement of the temporally changing B(0) field, a simple field probe was developed, that was placed in proximity to the tissue of interest. In this work, it is shown how such a field probe system can be used to monitor temporal B(0) field variations in the human body during MRI and magnetic resonance spectroscopy. Furthermore, it is shown how the acquired temporal B(0) field information can drive a dynamic shim module to directly correct the B(0) magnetic field in real time.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/mrm.23272 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Orientation selectivity properties for the affine Gaussian derivative and the affine Gabor models for visual receptive fields.
J Comput Neurosci
January 2025
Computational Brain Science Lab, Division of Computational Science and Technology, KTH Royal Institute of Technology, SE-100 44, Stockholm, Sweden.
This paper presents an in-depth theoretical analysis of the orientation selectivity properties of simple cells and complex cells, that can be well modelled by the generalized Gaussian derivative model for visual receptive fields, with the purely spatial component of the receptive fields determined by oriented affine Gaussian derivatives for different orders of spatial differentiation. A detailed mathematical analysis is presented for the three different cases of either: (i) purely spatial receptive fields, (ii) space-time separable spatio-temporal receptive fields and (iii) velocity-adapted spatio-temporal receptive fields. Closed-form theoretical expressions for the orientation selectivity curves for idealized models of simple and complex cells are derived for all these main cases, and it is shown that the orientation selectivity of the receptive fields becomes more narrow, as a scale parameter ratio , defined as the ratio between the scale parameters in the directions perpendicular to vs.
View Article and Find Full Text PDFRadiogenomic explainable AI with neural ordinary differential equation for identifying post-SRS brain metastasis radionecrosis.
Med Phys
January 2025
Deparment of Radiation Oncology, Duke University, Durham, North Carolina, USA.
Background: Stereotactic radiosurgery (SRS) is widely used for managing brain metastases (BMs), but an adverse effect, radionecrosis, complicates post-SRS management. Differentiating radionecrosis from tumor recurrence non-invasively remains a major clinical challenge, as conventional imaging techniques often necessitate surgical biopsy for accurate diagnosis. Machine learning and deep learning models have shown potential in distinguishing radionecrosis from tumor recurrence.
View Article and Find Full Text PDFUse of Resonant Acoustic Fields as Atmospheric-Pressure Ion Gates.
Anal Chem
January 2025
Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, New York 12180, United States.
Ion optics are crucial for spectrometric methods such as mass spectrometry (MS) and ion mobility spectrometry (IMS). Among the wide selection of ion optics, temporal ion gates are of particular importance for time-of-flight MS (TOF-MS) and drift-tube IMS. Commonly implemented as electrostatic ion gates, these optics offer a rapid, efficient means to block ion beams and form discrete ion packets for subsequent analysis.
View Article and Find Full Text PDFMueller matrix polarization measurement technique, as a non-invasive and label-free, provides comprehensive optical information on polarization-related and structural characteristics of the measured target. It has been widely applied in biomedical, agricultural, and industrial fields. However, the traditional time-division modulation Mueller matrix measurement method requires multiple measurements, which suffers from long measurement time and susceptibility to cumulative errors from moving parts.
View Article and Find Full Text PDFThe space-time wave packet (STWP) is a type of pulsed optical field, exhibiting distinctive characteristics, including the capacity to propagate without diffraction or dispersion and to have arbitrary group velocities. However, the intensity of the STWP is constrained by the low damage threshold of some indispensable optical elements like the spatial light modulator (SLM). While optical parametric amplification (OPA) has been proposed for amplifying STWPs, spatio-temporal (ST) characteristics of amplified STWPs remain significantly unexplored.
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!