The purpose of this study was to demonstrate a simple and fast method for solving the time-dependent Bloch-McConnell equations describing the behavior of magnetization in magnetic resonance imaging (MRI) in the presen...The purpose of this study was to demonstrate a simple and fast method for solving the time-dependent Bloch-McConnell equations describing the behavior of magnetization in magnetic resonance imaging (MRI) in the presence of multiple chemical exchange pools. First, the time-dependent Bloch- McConnell equations were reduced to a homogeneous linear differential equation, and then a simple equation was derived to solve it using a matrix operation and Kronecker tensor product. From these solutions, the longitudinal relaxation rate (R1ρ) and transverse relaxation rate in the rotating frame (R2ρ) and Z-spectra were obtained. As illustrative examples, the numerical solutions for linear and star-type three-pool chemical exchange models and linear, star- type, and kite-type four-pool chemical exchange models were presented. The effects of saturation time (ST) and radiofrequency irradiation power (ω1) on the chemical exchange saturation transfer (CEST) effect in these models were also investigated. Although R1ρ and R2ρ were not affected by the ST, the CEST effect observed in the Z-spectra increased and saturated with increasing ST. When ω1 was varied, the CEST effect increased with increasing ω1 in R1ρ, R2ρ, and Z-spectra. When ω1 was large, however, the spillover effect due to the direct saturation of bulk water protons also increased, suggesting that these parameters must be determined in consideration of both the CEST and spillover effects. Our method will be useful for analyzing the complex CEST contrast mechanism and for investigating the optimal conditions for CEST MRI in the presence of multiple chemical exchange pools.展开更多
目的:利用化学位移编码磁共振成像(chemical-shift-encoded magnetic resonance imaging,CSE-MRI)技术定量检测脂肪组织脂肪酸组分,分析直肠癌患者不同部位脂肪酸组分变化情况,探讨该技术应用于评价脂肪酸影响直肠癌发生、发展的价值。...目的:利用化学位移编码磁共振成像(chemical-shift-encoded magnetic resonance imaging,CSE-MRI)技术定量检测脂肪组织脂肪酸组分,分析直肠癌患者不同部位脂肪酸组分变化情况,探讨该技术应用于评价脂肪酸影响直肠癌发生、发展的价值。方法:对2021年10月—2022年12月于复旦大学附属华东医院经术后病理学检查证实的直肠腺癌患者术前行直肠常规MRI扫描和多回波梯度回波CSE-MRI检查以测定直肠系膜、肠系膜和臀部皮下3个部位的脂肪组织脂肪酸组分[包括饱和脂肪酸分数(fraction of saturated fatty acid,fSFA)、单不饱和脂肪酸分数(fraction of monounsaturated fatty acid,fMUFA)和多不饱和脂肪酸分数(fraction of polyunsaturated fatty acid,fPUFA)]。同期入组与年龄性别相匹配的对照组非直肠癌患者20例。分析直肠癌组与对照组间以及直肠癌患者中各部位脂肪组织脂肪酸组分变化,评价脂肪酸在肿瘤发生发展过程中的作用;分别分析直肠癌淋巴血管侵犯(lymphovascular invasion,LVI)、周围神经侵犯(peripheral nerve invasion,PNI)阳性组和阴性组各部位脂肪组织脂肪酸组分变化,评价脂肪酸对肿瘤侵袭性的影响。脂肪酸分数参数测量的观察者间一致性通过组内相关系数(intraclass correlation coefficient,ICC)评估。两组间差异分析用独立样本t检验或Mann-Whitney U检验;多组间差异分析用单因素方差分析(One-Way ANOVA)或Kruskal-Wallis H(K)检验。结果:共纳入56例直肠腺癌患者,包括男性36例,女性20例,平均(65.1±10.1)岁;LVI阳性11例(19.6%),PNI阳性10例(17.9%)。对照组20例,其中男性12例,女性8例,平均(66.3±8.8)岁。观察者间各部位各脂肪酸分数的测量相关性良好,ICC均>0.60。直肠癌组中直肠系膜脂肪组织fSFA高于对照组(37.2±4.2 vs 35.0±2.7,P=0.035);直肠癌患者中直肠系膜、肠系膜与臀部皮下脂肪组织中的fMUFA(分别为37.5±2.4、37.3±8.1和40.6±8.7,P=0.003)和fPUFA(分别为24.9±4.1、26.3±4.9和21.5±4.7,P<0.001)的差异均有统计学意义;LVI(+)直肠癌直肠系膜脂肪中fMUFA高于LVI(-)组(38.8±1.5 vs 37.1±2.5,P=0.035);PNI(+)/(-)直肠癌组间各部位脂肪组织各脂肪酸分数差异均无统计学意义(P>0.05)。结论:①直肠癌患者直肠系膜脂肪SFA分数与正常对照组存在差异;②直肠癌患者直肠系膜和肠系膜脂肪的fMUFA和fPUFA与皮下脂肪组织之间存在差异;③直肠癌患者直肠系膜脂肪fMUFA与LVI存在关联。展开更多
文摘The purpose of this study was to demonstrate a simple and fast method for solving the time-dependent Bloch-McConnell equations describing the behavior of magnetization in magnetic resonance imaging (MRI) in the presence of multiple chemical exchange pools. First, the time-dependent Bloch- McConnell equations were reduced to a homogeneous linear differential equation, and then a simple equation was derived to solve it using a matrix operation and Kronecker tensor product. From these solutions, the longitudinal relaxation rate (R1ρ) and transverse relaxation rate in the rotating frame (R2ρ) and Z-spectra were obtained. As illustrative examples, the numerical solutions for linear and star-type three-pool chemical exchange models and linear, star- type, and kite-type four-pool chemical exchange models were presented. The effects of saturation time (ST) and radiofrequency irradiation power (ω1) on the chemical exchange saturation transfer (CEST) effect in these models were also investigated. Although R1ρ and R2ρ were not affected by the ST, the CEST effect observed in the Z-spectra increased and saturated with increasing ST. When ω1 was varied, the CEST effect increased with increasing ω1 in R1ρ, R2ρ, and Z-spectra. When ω1 was large, however, the spillover effect due to the direct saturation of bulk water protons also increased, suggesting that these parameters must be determined in consideration of both the CEST and spillover effects. Our method will be useful for analyzing the complex CEST contrast mechanism and for investigating the optimal conditions for CEST MRI in the presence of multiple chemical exchange pools.
文摘目的:利用化学位移编码磁共振成像(chemical-shift-encoded magnetic resonance imaging,CSE-MRI)技术定量检测脂肪组织脂肪酸组分,分析直肠癌患者不同部位脂肪酸组分变化情况,探讨该技术应用于评价脂肪酸影响直肠癌发生、发展的价值。方法:对2021年10月—2022年12月于复旦大学附属华东医院经术后病理学检查证实的直肠腺癌患者术前行直肠常规MRI扫描和多回波梯度回波CSE-MRI检查以测定直肠系膜、肠系膜和臀部皮下3个部位的脂肪组织脂肪酸组分[包括饱和脂肪酸分数(fraction of saturated fatty acid,fSFA)、单不饱和脂肪酸分数(fraction of monounsaturated fatty acid,fMUFA)和多不饱和脂肪酸分数(fraction of polyunsaturated fatty acid,fPUFA)]。同期入组与年龄性别相匹配的对照组非直肠癌患者20例。分析直肠癌组与对照组间以及直肠癌患者中各部位脂肪组织脂肪酸组分变化,评价脂肪酸在肿瘤发生发展过程中的作用;分别分析直肠癌淋巴血管侵犯(lymphovascular invasion,LVI)、周围神经侵犯(peripheral nerve invasion,PNI)阳性组和阴性组各部位脂肪组织脂肪酸组分变化,评价脂肪酸对肿瘤侵袭性的影响。脂肪酸分数参数测量的观察者间一致性通过组内相关系数(intraclass correlation coefficient,ICC)评估。两组间差异分析用独立样本t检验或Mann-Whitney U检验;多组间差异分析用单因素方差分析(One-Way ANOVA)或Kruskal-Wallis H(K)检验。结果:共纳入56例直肠腺癌患者,包括男性36例,女性20例,平均(65.1±10.1)岁;LVI阳性11例(19.6%),PNI阳性10例(17.9%)。对照组20例,其中男性12例,女性8例,平均(66.3±8.8)岁。观察者间各部位各脂肪酸分数的测量相关性良好,ICC均>0.60。直肠癌组中直肠系膜脂肪组织fSFA高于对照组(37.2±4.2 vs 35.0±2.7,P=0.035);直肠癌患者中直肠系膜、肠系膜与臀部皮下脂肪组织中的fMUFA(分别为37.5±2.4、37.3±8.1和40.6±8.7,P=0.003)和fPUFA(分别为24.9±4.1、26.3±4.9和21.5±4.7,P<0.001)的差异均有统计学意义;LVI(+)直肠癌直肠系膜脂肪中fMUFA高于LVI(-)组(38.8±1.5 vs 37.1±2.5,P=0.035);PNI(+)/(-)直肠癌组间各部位脂肪组织各脂肪酸分数差异均无统计学意义(P>0.05)。结论:①直肠癌患者直肠系膜脂肪SFA分数与正常对照组存在差异;②直肠癌患者直肠系膜和肠系膜脂肪的fMUFA和fPUFA与皮下脂肪组织之间存在差异;③直肠癌患者直肠系膜脂肪fMUFA与LVI存在关联。
文摘目的建立一个简单友好,显示和分析化学交换饱和转移(chemical exchange saturation transfer,CEST)Z谱的软件工具包,方便临床医生和研究者进行应用研究。材料与方法使用传统CEST成像方法采集数据,通过MATLAB GUI制作系统,并通过两种方法实现定制选取以鼠标指定点为中心的任意大小的多个感兴趣区域(region of interest,ROI),展示其Z谱,并对其进行分析比较。结果图像不同位置ROI、不同像素大小ROI得到的Z谱不同,反映出不同的生物学信息。结论Z谱决定最终CEST信号分析与相关生物医学信息提取。系统主要功能包括CEST图像归一化去噪,不对称磁化传递速率(magnetization transfer ratio,MTRasym)映射的形成,ROI选取及Z谱拟合。
