Publications by authors named "E Alonso-Ortiz"
On the impact of B0 shimming algorithms on single-voxel MR spectroscopy.
Magn Reson Med
January 2025
Purpose: To assess the impact of different B0 shimming algorithms on MRS.
Methods: B0 field maps and single-voxel MR spectroscopy were acquired in the prefrontal cortex of five volunteers at 3 T using five different B0 shimming approaches. B0 shimming was achieved using Siemens' proprietary shim algorithm, in addition to the Pseudo-Inverse (PI), Quadratic Programming (QuadProg), Least Squares (LSq), and Gradient optimization (Grad) algorithms.
Purpose: Advancing the development of 7 T MRI for spinal cord imaging is crucial for the enhanced diagnosis and monitoring of various neurodegenerative diseases and traumas. However, a significant challenge at this field strength is the transmit field inhomogeneity. Such inhomogeneity is particularly problematic for imaging the small, deep anatomical structures of the cervical spinal cord, as it can cause uneven signal intensity and elevate the local specific absorption ratio, compromising image quality.
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- Clinical research typically requires careful study designs that account for variables like sex and age, but often overlooks body size factors like height and weight in neuroimaging studies.
- This study analyzed data from 267 healthy adults to explore how body height and weight relate to various brain and spinal cord MRI metrics, finding significant correlations, especially with brain gray matter volume and cervical spinal cord area.
- The results suggest that body size is an important biological variable that should be included in clinical neuroimaging study designs to enhance accuracy in understanding brain and spinal cord structures.
Purpose: To address the limitations of spinal cord imaging at ultra-high field (UHF) due to time-consuming parallel transmit (pTx) adjustments. This study introduces calibration-free offline computed universal shim modes that can be applied seamlessly for different pTx RF coils and spinal cord target regions, substantially enhancing spinal cord imaging efficiency at UHF.
Methods: A library of channel-wise relative maps for the cervical spinal cord (six datasets) and thoracic and lumbar spinal cord (nine datasets) was constructed to optimize transmit homogeneity and efficiency for these regions.
Obtaining high quality images of the spinal cord with MRI is difficult, partly due to the fact that the spinal cord is surrounded by a number of structures that have differing magnetic susceptibility. This causes inhomogeneities in the magnetic field, which in turn lead to image artifacts. In order to address this issue, linear compensation gradients can be employed.
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