目的本研究旨在探寻一类性能优异的血管增强算法,并结合阈值水平集分割算法进行肝脏血管系统的三维自动分割。方法首先对原始三维增强CT数据进行S型非线性灰度映射;随后对不同的血管增强算法进行对比分析;最后使用阈值水平集分割算法分...目的本研究旨在探寻一类性能优异的血管增强算法,并结合阈值水平集分割算法进行肝脏血管系统的三维自动分割。方法首先对原始三维增强CT数据进行S型非线性灰度映射;随后对不同的血管增强算法进行对比分析;最后使用阈值水平集分割算法分割出肝血管系统。选用3Dircadb公开数据集中的20例腹部增强CT数据定量评估了两类经典的血管增强算法,包括血管特征提取算法及扩散滤波算法。结果血管特征提取算法运行效率平均优于扩散滤波算法。血管特征提取算法结果的对比度平均高于扩散滤波算法2 d B以上,导致扩散滤波算法后续的计算复杂度高,准确性降低。阈值水平集分割算法的结果与区域生长算法、形态检测水平集算法和测地线活动轮廓水平集算法相比,准确性达77%以上,高于其余分割算法。结论血管特征提取算法与扩散滤波算法相比,更适合依赖灰度值的血管分割。阈值水平集算法能缓解单纯依赖阈值或依赖血管边界的血管欠分割问题,结合血管增强算法后能更准确的分割出肝脏血管。展开更多
Solid malignancies have to develop their own blood supply for their aggressive growth and metastasis;a process known as tumor angiogenesis.Angiogenesis is largely involved in tumor survival,progression and spread,whic...Solid malignancies have to develop their own blood supply for their aggressive growth and metastasis;a process known as tumor angiogenesis.Angiogenesis is largely involved in tumor survival,progression and spread,which are known to be significantly attributed to treatment failures.Over the past decades,efforts have been made to understand the difference between nor-mal and tumor vessels.It has been demonstrated that tumor vasculature is structurally immature with chaotic and leaky phenotypes,which provides opportunities for developing novel anticancer strategies.Targeting tumor vasculature is not only a unique therapeutic interven-tion to starve neoplastic cells,but also enhances the efficacy of conventional cancer treatments.Vascular dis-rupting agents(VDAs) have been developed to disrupt the already existing neovasculature in actively growing tumors,cause catastrophic vascular shutdown within short time,and induce secondary tumor necrosis.VDAs are cytostatic;they can only inhibit tumor growth,but not eradicate the tumor.This novel drug mechanism has urged us to develop multiparametric imaging biomark-ers to monitor early hemodynamic alterations,cellular dysfunctions and metabolic impairments before tumor dimensional changes can be detected.In this article,we review the characteristics of tumor vessels,tubulin-destabilizing mechanisms of VDAs,and in vivo effects of the VDAs that have been mostly studied in preclinical studies and clinical trials.We also compare the differ-ent tumor models adopted in the preclinical studies on VDAs.Multiparametric imaging biomarkers,mainly diffu-sion-weighted imaging and dynamic contrast-enhanced imaging from magnetic resonance imaging,are evalu-ated for their potential as morphological and functional imaging biomarkers for monitoring therapeutic effects of VDAs.展开更多
文摘目的本研究旨在探寻一类性能优异的血管增强算法,并结合阈值水平集分割算法进行肝脏血管系统的三维自动分割。方法首先对原始三维增强CT数据进行S型非线性灰度映射;随后对不同的血管增强算法进行对比分析;最后使用阈值水平集分割算法分割出肝血管系统。选用3Dircadb公开数据集中的20例腹部增强CT数据定量评估了两类经典的血管增强算法,包括血管特征提取算法及扩散滤波算法。结果血管特征提取算法运行效率平均优于扩散滤波算法。血管特征提取算法结果的对比度平均高于扩散滤波算法2 d B以上,导致扩散滤波算法后续的计算复杂度高,准确性降低。阈值水平集分割算法的结果与区域生长算法、形态检测水平集算法和测地线活动轮廓水平集算法相比,准确性达77%以上,高于其余分割算法。结论血管特征提取算法与扩散滤波算法相比,更适合依赖灰度值的血管分割。阈值水平集算法能缓解单纯依赖阈值或依赖血管边界的血管欠分割问题,结合血管增强算法后能更准确的分割出肝脏血管。
基金Supported by(partially) The grants awarded by Fonds voor Wetenschappelijk Onderzoek-Vlaanderen(FWO Vlaanderen) Impulsfinanciering project(ZWAP/05/018)Geconcerteerde Onderzoeksactie of the Flemish Government,OT project(OT/06/70)+1 种基金the K.U.Leuven Molecular Small Animal Imaging Center MoSAIC (KUL EF/05/08)the center of excellence In vivo Molecular Imaging Research of K.U.Leuven and a EU project Asia-Link CfP 2006-EuropeAid/123738/C/ACT/Multi-Proposal No.128-498/111
文摘Solid malignancies have to develop their own blood supply for their aggressive growth and metastasis;a process known as tumor angiogenesis.Angiogenesis is largely involved in tumor survival,progression and spread,which are known to be significantly attributed to treatment failures.Over the past decades,efforts have been made to understand the difference between nor-mal and tumor vessels.It has been demonstrated that tumor vasculature is structurally immature with chaotic and leaky phenotypes,which provides opportunities for developing novel anticancer strategies.Targeting tumor vasculature is not only a unique therapeutic interven-tion to starve neoplastic cells,but also enhances the efficacy of conventional cancer treatments.Vascular dis-rupting agents(VDAs) have been developed to disrupt the already existing neovasculature in actively growing tumors,cause catastrophic vascular shutdown within short time,and induce secondary tumor necrosis.VDAs are cytostatic;they can only inhibit tumor growth,but not eradicate the tumor.This novel drug mechanism has urged us to develop multiparametric imaging biomark-ers to monitor early hemodynamic alterations,cellular dysfunctions and metabolic impairments before tumor dimensional changes can be detected.In this article,we review the characteristics of tumor vessels,tubulin-destabilizing mechanisms of VDAs,and in vivo effects of the VDAs that have been mostly studied in preclinical studies and clinical trials.We also compare the differ-ent tumor models adopted in the preclinical studies on VDAs.Multiparametric imaging biomarkers,mainly diffu-sion-weighted imaging and dynamic contrast-enhanced imaging from magnetic resonance imaging,are evalu-ated for their potential as morphological and functional imaging biomarkers for monitoring therapeutic effects of VDAs.
