Motion correction for functional MRI with three-dimensional hybrid radial-Cartesian EPI

Purpose Subject motion is a major source of image degradation for functional MRI, especially when using multi-shot sequences like 3D EPI. We present a hybrid radial-Cartesian 3D EPI trajectory enabling motion correction in k-space for functional MRI. Methods The EPI “blades” of the 3D hybrid radial-Cartesian EPI sequence (TURBINE) are rotated about the phase-encoding axis to fill out a cylinder in 3D k-space. Angular blades are acquired over time using a golden angle rotation increment, allowing reconstruction at flexible temporal resolution. The self-navigating properties of the sequence are used to determine motion parameters from a high temporal resolution navigator time-series. The motion is corrected in k-space as part of the image reconstruction and evaluated for experiments with both cued and natural motion. Results We demonstrate that the motion correction works robustly and that we can achieve substantial artifact reduction as well as improvement in temporal SNR and fMRI activation in the presence of both severe and subtle motion. Conclusion We show the potential for hybrid radial-Cartesian 3D EPI to substantially reduce artifacts for application in fMRI, especially for subject groups with significant head motion. The motion correction approach does not prolong the scan and no extra hardware is required.</p

Motion correction for functional MRI with three-dimensional hybrid radial-Cartesian EPI

Purpose Subject motion is a major source of image degradation for functional MRI, especially when using multi-shot sequences like 3D EPI. We present a hybrid radial-Cartesian 3D EPI trajectory enabling motion correction in k-space for functional MRI. Methods The EPI “blades” of the 3D hybrid radial-Cartesian EPI sequence (TURBINE) are rotated about the phase-encoding axis to fill out a cylinder in 3D k-space. Angular blades are acquired over time using a golden angle rotation increment, allowing reconstruction at flexible temporal resolution. The self-navigating properties of the sequence are used to determine motion parameters from a high temporal resolution navigator time-series. The motion is corrected in k-space as part of the image reconstruction and evaluated for experiments with both cued and natural motion. Results We demonstrate that the motion correction works robustly and that we can achieve substantial artifact reduction as well as improvement in temporal SNR and fMRI activation in the presence of both severe and subtle motion. Conclusion We show the potential for hybrid radial-Cartesian 3D EPI to substantially reduce artifacts for application in fMRI, especially for subject groups with significant head motion. The motion correction approach does not prolong the scan and no extra hardware is required.</p

Strategies for proteomic analysis of non-enzymatically glycated proteins

Among post-translational modifications of proteins, non-enzymatic glycation is one of the less frequently studied by experts in proteomics. However, the relevance of protein glycation has been widely shown up in several pathological conditions. In fact, non-enzymatic glycation has been strongly related to hyperglycemic conditions and, thus, to chronic complications associated to diabetes mellitus and renal failure as well as degenerative changes occurring in the course of aging. Two different glycation levels are distinguished whether the structure of the protein is seriously damaged or not. The biochemical and clinical significance of both glycations have been already described. Several reasons have contributed to the lack of highly sensitive and selective methods for identification and quantitation of glycated proteins. These are mainly (1) the low concentration of glycated proteins in humans due to the low efficiency of the glycation process, (2) the modification of enzymatic digestion patterns, (3) the low ionization efficiency of glycated peptides, and (4) the lack of software including tools to identify this post-translational modification. The aim of this review is to provide the analytical guidelines required to succeed in the analysis of glycated proteins. For this purpose, different analytical approaches are considered to solve the main drawbacks derived from this gap in the proteomics field. Some challenges are finally proposed to be taken into account in future research