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Linear-fitting-based similarity coefficient map for tissue dissimilarity analysis in T2^*-w magnetic resonance imaging
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作者 余绍德 伍世宾 +5 位作者 王浩宇 魏新华 陈鑫 潘万龙 Hu Jiani 谢耀钦 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第12期610-615,共6页
Similarity coefficient mapping(SCM) aims to improve the morphological evaluation of T*2weighted magnetic resonance imaging(T*2-w MRI). However, how to interpret the generated SCM map is still pending. Moreover, ... Similarity coefficient mapping(SCM) aims to improve the morphological evaluation of T*2weighted magnetic resonance imaging(T*2-w MRI). However, how to interpret the generated SCM map is still pending. Moreover, is it probable to extract tissue dissimilarity messages based on the theory behind SCM? The primary purpose of this paper is to address these two questions. First, the theory of SCM was interpreted from the perspective of linear fitting. Then, a term was embedded for tissue dissimilarity information. Finally, our method was validated with sixteen human brain image series from multiecho T*2-w MRI. Generated maps were investigated from signal-to-noise ratio(SNR) and perceived visual quality, and then interpreted from intra- and inter-tissue intensity. Experimental results show that both perceptibility of anatomical structures and tissue contrast are improved. More importantly, tissue similarity or dissimilarity can be quantified and cross-validated from pixel intensity analysis. This method benefits image enhancement, tissue classification, malformation detection and morphological evaluation. 展开更多
关键词 T*2-w magnetic resonance imaging similarity coefficient map linear fitting tissue dissimilarity
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Feasibility of similarity coefficient map for improving morphological evaluation of T_2* weighted MRI for renal cancer
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作者 王浩宇 Hu Jiani +7 位作者 谢耀钦 陈杰 Yu Amy 魏新华 戴勇鸣 Li Meng 包尚联 E.M.Haacke 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第3期539-549,共11页
The purpose of this paper is to investigate the feasibility of using a similarity coefficient map(SCM) in improving the morphological evaluation of T2* weighted(T2*W) magnatic resonance imaging(MRI) for renal ... The purpose of this paper is to investigate the feasibility of using a similarity coefficient map(SCM) in improving the morphological evaluation of T2* weighted(T2*W) magnatic resonance imaging(MRI) for renal cancer.Simulation studies and in vivo 12-echo T2*W experiments for renal cancers were performed for this purpose.The results of the first simulation study suggest that an SCM can reveal small structures which are hard to distinguish from the background tissue in T2*W images and the corresponding T2* map.The capability of improving the morphological evaluation is likely due to the improvement in the signal-to-noise ratio(SNR) and the carrier-to-noise ratio(CNR) by using the SCM technique.Compared with T2* W images,an SCM can improve the SNR by a factor ranging from 1.87 to 2.47.Compared with T2* maps,an SCM can improve the SNR by a factor ranging from 3.85 to 33.31.Compared with T2*W images,an SCM can improve the CNR by a factor ranging from 2.09 to 2.43.Compared with T2* maps,an SCM can improve the CNR by a factor ranging from 1.94 to 8.14.For a given noise level,the improvements of the SNR and the CNR depend mainly on the original SNRs and CNRs in T2*W images,respectively.In vivo experiments confirmed the results of the first simulation study.The results of the second simulation study suggest that more echoes are used to generate the SCM,and higher SNRs and CNRs can be achieved in SCMs.In conclusion,an SCM can provide improved morphological evaluation of T2*W MR images for renal cancer by unveiling fine structures which are ambiguous or invisible in the corresponding T2*W MR images and T2* maps.Furthermore,in practical applications,for a fixed total sampling time,one should increase the number of echoes as much as possible to achieve SCMs with better SNRs and CNRs. 展开更多
关键词 renal cancer T2* weighted MRI similarity coefficient map
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Building a Post-Layout Simulation Performance Model with Global Mapping Model Fusion Technique
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作者 Zhikai Wang Wenfei Hu +4 位作者 Sen Yin Ruitao Wang Jian Zhang Yan Wang Zuochang Ye 《Tsinghua Science and Technology》 SCIE EI CAS CSCD 2022年第3期512-525,共14页
Building a post-layout simulation performance model is essential in closing the loop of analog circuits, but it is a challenging task because of the high-dimensional space and expensive simulation cost. To facilitate ... Building a post-layout simulation performance model is essential in closing the loop of analog circuits, but it is a challenging task because of the high-dimensional space and expensive simulation cost. To facilitate efficient modeling, this paper proposes a Global Mapping Model Fusion(GMMF) technique. The key idea of GMMF is to reuse the schematic-level model trained by the Artificial Neural Network(ANN) algorithm, and combine it with few mapping coefficients to build the post-simulation model. Furthermore, as an efficient global optimization algorithm,differential evolution is applied to determine the optimal mapping coefficients with few samples. In GMMF, only a small number of mapping coefficients are unknown, so the number of post-layout samples needed is significantly reduced. To enhance practical utility of the proposed GMMF technique, two specific mapping relations, i.e., linear or weakly no-linear and nonlinear, are carefully considered in this paper. We conduct experiments on two topologies of two-stage operational amplifier and comparator in different commercial processes. All the simulation data for modeling are obtained from a parametric design framework. A more than 5 runtime speedup is achieved over ANN without surrendering any accuracy. 展开更多
关键词 post-layout simulation performance model Global mapping Model Fusion(GMMF) Artificial Neural Network(ANN) few mapping coefficients differential evolution
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The Mapping Synthesis of Ternary Functions under Fixed Polarities 被引量:1
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作者 陈偕雄 吴浩敏 《Journal of Computer Science & Technology》 SCIE EI CSCD 1993年第4期356-361,共6页
This paper proposes a mapping method simplifying the Reed-Muller expansion(“RM expansion”)of a ternary function under fixed polarities and the transformation of the RM expansion coefficients with different fixed pol... This paper proposes a mapping method simplifying the Reed-Muller expansion(“RM expansion”)of a ternary function under fixed polarities and the transformation of the RM expansion coefficients with different fixed polarities. 展开更多
关键词 RM expansion b_j coefficient map simplification of ternary functions multivalued logic modular algebra
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