Research Progress of Quantitative Susceptibility Mapping in MRI / 生物医学工程学杂志

Magnetic susceptibility is an intrinsic physical quantity which describes the relationship between material magnetization and applied external magnetic field. Quantitative susceptibility mapping (QSM) is an MRI technology which can quantify the buck magnetic susceptibility of tissue in vivo. It is particularly effective at elucidating anatomy with paramagnetic or diamagnetic components. QSM technology is a method for solving the ill-pose problem of unconventional de-convolution of the measured tissue magnetic field with the unit magnetic dipole field to obtain the susceptibility source map. Many multi orientation scan based QSM and clinically acceptable single orientation QSM methods have been proposed to solve this ill-posed problem. In this paper, the QSM concept is introduced and the various QSM methods are systematically categorized and discussed. The aim of this paper is to summarize the current research progress of QSM, popularize the knowledge of QSM and promote the improvements and the rational application of QSM in clinical field.

Magnetic resonance image fusion based on three dimensional band limited shearlet transform / 生物医学工程学杂志

More and more medical devices can capture different features of human body and form three dimensional (3D) images. In clinical applications, usually it is required to fuse multiple source images containing different and crucial information into one for the purpose of assisting medical treatment. However, traditional image fusion methods are normally designed for two dimensional (2D) images and will lead to loss of the third dimensional information if directly applied to 3D data. Therefore, a novel 3D magnetic image fusion method was proposed based on the combination of newly invented beyond wavelet transform, called 3D band limited shearlet transformand (BLST), and four groups of traditional fusion rules. The proposed method was then compared with the 2D and 3D wavelet and dual-tree complex wavelet transform fusion methods through 4 groups of human brain T2* and quantitative susceptibility mapping (QSM) images. The experiments indicated that the performance of the method based on 3D transform was generally superior to the existing methods based on 2D transform. Taking advantage of direction representation, shearlet transform could effectively improve the performance of conventional fusion method based on 3D transform. It is well concluded, therefore, that the proposed method is the best among the methods based on 2D and 3D transforms.

[UPLC fingerprint for quality assessment of ginsenosides of ginseng radix et rhizoma].

This paper is aimed to establish the method of fingerprint analysis of chemical constituents by reversed-phase ultra-performance liquid chromatography (UPLC) for the quality control of the roots and rhizomes of Panax ginseng (Ginseng Radix et Rhizoma). The method was performed on a ACQUITY UPLC BEH C18 (50 mm x 2.1 mm ID, 1.7 microm) with a mixed mobile phase of water and acetonitrile in a gradient mode. The flow rate was 0.3 mL x min(-1) and the wavelength of measurement was 203 nm. Eleven batches of the Ginseng Radix et Rhizoma were determined. The UPLC chromatographic fingerprints of chemical constituents were established from the eleven batches of the Ginseng Radix et Rhizoma and showed fifteen characteristic common peaks, among which fifteen peaks were recognized and nine compounds (ginsenosides Rg1, Re, Rf, Rg2, Rb1, Rc, Rb2, Rb3 and Rd) were determined by comparison with chromatographic behaviors and UV spectra of the authentic compounds. The eleven batches of samples were classified as two clusters by hierarchical clustering analysis (HCA) and principle component analysis (PCA), and six samples were confirmed to establish the mutual model. The quality was assessed by similarity evaluation system for chromatographic fingerprint of TCM (2004B Version). The convenient and high specific method can be used to identify and evaluate the quality of the Ginseng Radix et Rhizoma.