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Your search keyword '"Kim, Kyoung-Nam"' showing total 43 results
Start Over Author "Kim, Kyoung-Nam" Publisher wiley
43 results on '"Kim, Kyoung-Nam"'

42. Voxel-wise partial volume correction method for accurate estimation of tissue sodium concentration in 23 Na-MRI at 7 T.

Author

Kim SY, Song J, Yoon JH, Kim KN, Chung JY, and Noh Y

Subjects
Adult, Cerebrospinal Fluid chemistry, Computer Simulation, Datasets as Topic, Female, Gray Matter chemistry, Humans, Linear Models, Male, Monte Carlo Method, Nuclear Magnetic Resonance, Biomolecular instrumentation, Organ Size, Phantoms, Imaging, Proton Magnetic Resonance Spectroscopy, White Matter chemistry, Young Adult, Brain Chemistry, Neuroimaging methods, Nuclear Magnetic Resonance, Biomolecular methods, Sodium analysis
Abstract

Sodium is crucial for the maintenance of cell physiology, and its regulation of the sodium-potassium pump has implications for various neurological conditions. The distribution of sodium concentrations in tissue can be quantitatively evaluated by means of sodium MRI ( 23 Na-MRI). Despite its usefulness in diagnosing particular disease conditions, tissue sodium concentration (TSC) estimated from 23 Na-MRI can be strongly biased by partial volume effects (PVEs) that are induced by broad point spread functions (PSFs) as well as tissue fraction effects. In this work, we aimed to propose a robust voxel-wise partial volume correction (PVC) method for 23 Na-MRI. The method is based on a linear regression (LR) approach to correct for tissue fraction effects, but it utilizes a 3D kernel combined with a modified least trimmed square (3D-mLTS) method in order to minimize regression-induced inherent smoothing effects. We acquired 23 Na-MRI data with conventional Cartesian sampling at 7 T, and spill-over effects due to the PSF were considered prior to correcting for tissue fraction effects using 3D-mLTS. In the simulation, we found that the TSCs of gray matter (GM) and white matter (WM) were underestimated by 20% and 11% respectively without correcting tissue fraction effects, but the differences between ground truth and PVE-corrected data after the PVC using the 3D-mLTS method were only approximately 0.6% and 0.4% for GM and WM, respectively. The capability of the 3D-mLTS method was further demonstrated with in vivo 23 Na-MRI data, showing significantly lower regression errors (ie root mean squared error) as compared with conventional LR methods (p < 0.001). The results of simulation and in vivo experiments revealed that 3D-mLTS is superior for determining under- or overestimated TSCs while preserving anatomical details. This suggests that the 3D-mLTS method is well suited for the accurate determination of TSC, especially in small focal lesions associated with pathological conditions., (© 2020 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.)

Published
2021
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43. Imaging and analysis of lenticulostriate arteries using 7.0-Tesla magnetic resonance angiography.

Author

Kang CK, Park CW, Han JY, Kim SH, Park CA, Kim KN, Hong SM, Kim YB, Lee KH, and Cho ZH

Subjects
Adult, Female, Humans, Image Enhancement instrumentation, Image Interpretation, Computer-Assisted instrumentation, Magnetic Resonance Angiography instrumentation, Middle Aged, Phantoms, Imaging, Reproducibility of Results, Sensitivity and Specificity, Algorithms, Basal Ganglia Cerebrovascular Disease pathology, Cerebral Arteries pathology, Image Enhancement methods, Image Interpretation, Computer-Assisted methods, Intracranial Arteriovenous Malformations pathology, Magnetic Resonance Angiography methods
Abstract

The purpose of this study was to analyze human lenticulostriate arteries (LSAs) obtained non-invasively by 7.0-T MRI. A three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) technique was used with an investigational 7.0-T MRI scanner with a radio-frequency coil that was optimized and designed for angiographic purposes. We obtained images from 16 healthy volunteers (8 males and 8 females, mean age 21 +/- 2.7 years). For direct comparison of LSA images with digital subtraction angiography (DSA), we also obtained 7.0-T MRA and DSA images from one patient, a 27-year-old woman with a posterior fossa arteriovenous malformation (AVM). We then analyzed the characteristics of LSAs using a custom data analysis method with MatLab for quantitative analysis. Analysis of LSA images included shape and number of branches and origins, findings that are essential and useful for quantification of LSA abnormalities in both healthy controls and patients. Ultra-high-field MRA provided clear anatomic delineation of the LSAs, thereby suggesting that 7.0-T MRA may be a promising technique for microvascular imaging of the LSAs.

Published
2009
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