磁共振弥散成像血管密度:概念及潜在多种临床应用  

Magnetic resonance diffusion derived vessel density:concepts and potential diverse applications

作　　者：王毅翔[1] 姚殿琦 李才应 肖本亨 Akmal Sabarudin Giuseppe Guglielmi Wang Yixiang;Yao Dianqi;Li Caiying;Xiao Benheng;Akmal Sabarudin;Giuseppe Guglielmi(Department of Imaging and Interventional Radiology,Faculty of Medicine,The Chinese University of Hong Kong,Shatin,New Territories,Hong Kong SAR,China;Diagnostic Imaging and Radiotherapy Program,Faculty of Health Sciences,The National University of Malaysia,Kuala Lumpur,Malaysia;Radiology Unit,Department of Clinical and Experimental Medicine,Foggia University School of Medicine,Foggia,Italy)

机构地区：[1]香港中文大学医学院影像与介入放射学系,中国香港沙田 [2]Diagnostic Imaging and Radiotherapy Program,Faculty of Health Sciences,The National University of Malaysia,Kuala Lumpur,Malaysia [3]Radiology Unit,Department of Clinical and Experimental Medicine,Foggia University School of Medicine,Foggia,Italy

出　　处：《新发传染病电子杂志》2024年第6期36-41,共6页Electronic Journal of Emerging Infectious Diseases

基　　金：香港基础研究基金项目(14112521)。

摘　　要：在磁共振弥散加权成像中,当没有弥散梯度磁场(b=0s/mm^(2))时,血管包括微血管显示高信号;而即使在应用非常低的弥散梯度磁场(如b=1或2s/mm^(2))时,血管包括微血管显示低信号。因此,弥散梯度磁场“关闭”时图像和弥散梯度磁场“开启”时图像之间的信号差反映了组织血管密度,从而可通过磁共振弥散成像血管密度(diffusion derived vessel density,DDVD)来量化这个现象。从磁共振物理的角度,对于自旋回波平面回波成像(echo planar imaging,EPI)序列,流动血液中的氢质子在被180°射频脉冲之前的第1个弥散梯度磁场失相位后,180°射频脉冲之后的第2个弥散梯度磁场无法完全重新聚焦,这是产生DDVD现象的原因。DDVD序列的分析只需要2个b值(其中1个是b=0s/mm^(2)),允许在较短时间内完成扫描。与造影剂动态增强成像相比,DDVD不涉及注射造影剂,数据采集速度更快,数据后处理也相对简单。与造影剂增强CT相比,DDVD无辐射。与造影剂增强MRI相比,初步经验表明DDVD定量测量更稳定。DDVD在评估多种疾病,包括乙型肝炎肝纤维化、肝癌、肝血管瘤、直肠癌、先兆子痫、胎盘子宫植入、脑梗死缺血性半暗带等,均显示了较大的应用前景。On diffusion-weighted(DW)imaging,blood vessels show high signal when there is no diffusion gradient(b=0s/mm^(2)),while they show low signal even when very low b-values(such as b=1 or 2s/mm^(2))are applied.Thus,the signal difference between images when the diffusion gradient is‘off’and images when the diffusion gradient is‘on’reflects the extent of tissue vessel density.We measure this via MRI diffusion derived vessel density(DDVD).For spin-echo type echoplanar imaging sequence,the second motion probing gradient after the 180-degree radiofrequency pulse could not fully re-focus the flowing spins in vessel and micro-vessels after being de-phased by the first motion probing gradient before the 180-degree radiofrequency pulse.The analysis of DDVD requires only two b-values(with one being b=0s/mm^(2) and the other being a non-zero low b-value),with a significantly shorter scanning time than contrast enhanced CT/MRI while without the need of a contrast agent injection and without radiation associated with CT.DDVD measure appears to be useful as a straightforward imaging biomarker in diverse clinical scenarios,including hepatitis B liver fibrosis,hepatocellular carcinoma,rectal carcinoma,liver hemangioma,early preeclampsia placenta,placenta accreta spectrum disorder,ischemic penumbra of brain stroke.

关 键 词：磁共振 弥散加权成像 血管密度 乙型肝炎肝纤维化 

分 类 号：R445.2[医药卫生—影像医学与核医学]