高血压脑白质疏松患者降压治疗中血压与脑白质疏松的MRI相关性研究

目的 探讨高血压脑白质疏松患者降压治疗过程中,不同血压水平对脑白质疏松的影响.方法 选取2013年7月至2014年3月经临床确诊的高血压患者36例,经MRI确认脑白质疏松病灶,且除外缺血性脑白质病以外的其他脑白质病变,分别于降压治疗后3个月、6个月及1年复查MRI,利用Fazekas量表量化脑白质疏松病灶,研究降压治疗后血压水平与脑白质疏松病灶的对应关系.结果 36例高血压脑白质疏松患者在1年的降压治疗过程中按血压控制水平分为正常组(21例)与非正常组(15例),与治疗前比较,血压正常组患者中20例脑白质疏松病变评分无变化,1例评分增加1分,非正常组所有患者病变评分均无变化,正常组与非正常组Fazekas评分变化差异无统计学意义(P>0.05).结论 高血压脑白质疏松患者降压治疗后,在一定时期内(1年),不论血压控制与否,脑白质疏松病灶没有明确变化.     

基于 MRI 健康成人丘脑的形态测量

目的:探讨MRI丘脑与毗邻结构形态学变化规律和意义,为与丘脑形态改变相关的疾病提供线性测量指标方法:利用成人活体头部MRI扫描资料,观测丘脑及其毗邻结构,分析各线性指标与丘脑面积、丘脑体积的相关性。结果:在断层标本上采用单因素方差分析显示:丘脑矢径、丘脑宽、丘脑面积性差和侧差未见显著性差异;丘脑横径、丘脑长侧差未见显著性差异,但其性差差异性显著(P<0.05)。方差齐性检验后Pearson相关分析显示:丘脑长与壳横径、壳矢径、壳面积、尾状核头矢径成正相关,丘脑宽与尾状核头矢径负相关,丘脑矢径、丘脑长与侧脑室前角间距成负相关。在体积测量中标准化后各组样本采用单因素方差分析显示:丘脑体积、尾状核头横径、尾状核头矢径及壳矢径左、右侧差异显著(左侧>右侧,P<0.05),其余各数据无显著性差异。标准化后与丘脑体积相关程度最为密切的线性指标分别是丘脑横径、丘脑矢径、丘脑长、丘脑宽(正相关)。结论:丘脑毗邻结构参数与丘脑参数存在线性关系,其毗邻结构的形态变化可作为研究丘脑形态变化的参考指标,丘脑横径、丘脑矢径、丘脑长、丘脑宽可作为丘脑形态变化的初筛指标。     

Assessing the sensitivity of diffusion MRI to detect neuronal activity directly

Functional MRI (fMRI) is widely used to study brain function in the neurosciences. Unfortunately, conventional fMRI only indirectly assesses neuronal activity via hemodynamic coupling. Diffusion fMRI was proposed as a more direct and accurate fMRI method to detect neuronal activity, yet confirmative findings have proven difficult to obtain. Given that the underlying relation between tissue water diffusion changes and neuronal activity remains unclear, the rationale for using diffusion MRI to monitor neuronal activity has yet to be clearly established. Here, we studied the correlation between water diffusion and neuronal activity in vitro by simultaneous calcium fluorescence imaging and diffusion MR acquisition. We used organotypic cortical cultures from rat brains as a biological model system, in which spontaneous neuronal activity robustly emerges free of hemodynamic and other artifacts. Simultaneous fluorescent calcium images of neuronal activity are then directly correlated with diffusion MR signals now free of confounds typically encountered in vivo. Although a simultaneous increase of diffusion-weighted MR signals was observed together with the prolonged depolarization of neurons induced by pharmacological manipulations (in which cell swelling was demonstrated to play an important role), no evidence was found that diffusion MR signals directly correlate with normal spontaneous neuronal activity. These results suggest that, whereas current diffusion MR methods could monitor pathological conditions such as hyperexcitability, e.g., those seen in epilepsy, they do not appear to be sensitive or specific enough to detect or follow normal neuronal activity.Developing a direct MRI method to detect neuronal activity in vivo and noninvasively is a major focus in neuroscience. Progress in this area is required to improve our understanding of normal brain function, and in a clinical setting, to develop new tools for studying normal and abnormal development to diagnose diseases and disorders of the brain. Functional MRI (fMRI) has been widely used in the cognitive neurosciences since its invention in the 1990s (1–3). The most widely used fMRI method, blood-oxygenation-level-dependent (BOLD) MRI, detects hemodynamic changes in the brain, which only indirectly reflects neuronal activity. Moreover, its hemodynamic origin limits both its spatial and temporal resolution and its interpretation as a direct proxy for neuronal activity (4, 5).More recently, several MRI methods were proposed to provide more direct measures of neuronal excitation (6). In particular, diffusion MRI, a method to measure the apparent diffusivity of water within tissues (7–9), has been suggested as a direct functional imaging method to detect neuronal activity (10–13). Early in vivo experiments in both humans and animals reported small but significant increases in highly diffusion-weighted MRI signals, which were ascribed to changes directly induced by the underlying neuronal activity rather than indirect hemodynamic changes (10–13). In vitro experiments on brain slices (14, 15) and spinal cord (16) reported similar reductions in water diffusivity under conditions of extreme hyperexcitability using strong pharmacologic stimulants.However, functional diffusion MRI (fDMRI) has not been widely used or adopted since its introduction almost two decades ago. Two major reasons for this may be a dearth of experiments that convincingly establish its neurophysiological basis and the poor reproducibility of the originally reported changes in diffusion MRI signals by different laboratories. The inability to detect the predicted changes using fDMRI and the possible confounds of hemodynamic contributions in fDMRI measurements in vivo do not argue for a robust connection between changes in diffusion MRI and underlying neuronal activity (17–20). Thus, “ground-truth” experiments, potentially establishing a connection between the changes in diffusion MRI and underlying neuronal activity, are needed, particularly to shed light on the possible biophysical basis of the fDMRI signal.Recently, we developed a novel test bed that could be used to assess non–hemodynamic-based functional MRI methods, in which MR signal acquisition and intracellular calcium fluorescence imaging to monitor neuronal activity can be performed simultaneously on organotypic cortical cultures from rat brains (21). The organotypic cortex culture is a well-characterized biological model of neuronal activity free of hemodynamic, respiratory, and other physiological confounds. Not only is the in vivo cortical cytoarchitecture preserved (including cortical layers and cortical cell types), but neuronal activity in the culture also displays bursts of spontaneous neuronal avalanches grouped into so-called up-states and separated by periods of low activity (22–25), resembling resting neuronal activity in vivo (26–28). Specifically, fluorometric calcium (Ca²⁺) imaging is used to detect intracellular Ca²⁺ concentration changes that closely follow action potentials in neurons under normal conditions and provide a direct method for detecting neuronal spiking activity in a neuronal network (29, 30). This test bed thus allows one to study precisely and accurately temporal correlations between the candidate functional MR signals, which are free of the usual in vivo confounds, and the underlying neuronal spiking activity by using an independent intracellular Ca²⁺ imaging experiment (21).In the current study, diffusion MR signals are obtained simultaneously with intracellular calcium fluorescence imaging of the organotypic cortex culture. The direct effects of neuronal activity on the diffusion MR signals are studied by time-series analysis of the simultaneous calcium and MR signals during normal neuronal activity and in different pathological states, which include induced hyperexcitability by kainic acid (kainate) and potassium, disinhibition by picrotoxin (PTX), suppression of excitability by tetrodotoxin (TTX), and cell volume modulation caused by osmotic pressure challenges. On the basis of these findings, it is possible to assess the prospect of detecting normal and abnormal neuronal activity using fDMRI and to better understand the relationship between fDMRI changes and biophysical mechanisms associated with neuronal excitation.     

体位改变对腰椎前斜入路通道影响的影像学分析

目的:探讨体位变化对L1~L5腰椎前斜入路椎间融合术(oblique lateral interbody fusion,OLIF)通道大小的影响。方法:随机选取40例健康志愿者,分别在仰卧位及右侧卧位进行L1~L5 MRI扫描。在位于椎间盘中点的图像内定义椎间盘中心点为O;A(平卧位)/A′(右侧卧位)点以及B(平卧位)/B′(右侧卧位)点为∠AOB(∠A′OB′)达到最小值时主动脉(或髂血管)左侧壁以及腰大肌前内侧壁上的点,记录各节段AB及A′B′的距离,并在各节段将AB与A′B′比较;将L1~L5各节段的A′B′进行节段间比较,并探讨其与性别、体重指数(body mass index,BMI)及腰大肌截面积(relative psoas cross-sectional area,PCSA)之间的关系。结果 :40例志愿者的BMI值为18.4~26.5,6例存在主动脉高分叉现象;各节段AB和A′B′(mm):L1/2为14.80±3.89和12.37±3.62,L2/3为12.85±4.16和9.96±3.37,L3/4为12.24±4.10和10.85±3.30,L4/5为9.78±4.69和9.72±4.37;主动脉高分叉者L4/5为7.72±3.56和6.71±2.86。在L1/2、L2/3、L3/4节段A′B′值显著小于AB(P=0.005,0.003,0.020);L4/5节段无论是否存在主动脉高分叉现象均无统计学差异(P=0.946,0.097);不同节段间A′B′值存在显著差异(P=0.046),通道大小趋势为L1/2L3/4L2/3L4/5主动脉高分叉者L4/5(其中L1/2显著主动脉高分叉者L4/5,P=0.003);男女性间A′B′在各节段无统计学差异(P均0.05);BMI与PCSA在L3/4与A′B′呈负线性相关(P=0.015,0.000),而PCSA在L1/2也与A′B′呈负线性相关(P=0.024)。结论 :右侧卧位时,OLIF通道解剖空间在L1/2、L2/3、L3/4水平显著减少,平卧位MRI对通道空间评估价值有限;而且OLIF通道大小与腰椎节段水平有关,并且受BMI值和腰大肌横截面积影响。     

磁共振非高斯弥散加权成像评价健康脑白质和脑胶质瘤水弥散微环境的可重复性研究

目的 探讨磁共振22b值(0～ 5000 s/mm2)非高斯弥散加权成像在健康成人脑白质和胶质瘤应用的可重复性.方法 12名健康志愿者和65名胶质瘤患者进行22 b值eDWI(enhanced diffusion weighted imaging)磁共振扫描.前者进行连续2次eDWI扫描,选取基底节层面和半卵圆中心层面深部白质为感兴趣区;后者进行单次eDWI扫描,由2名神经放射医师分别在肿瘤最大层面的肿瘤实质区放置感兴趣区,工作站进行双指数和拉伸指数模型后处理;前者对2次扫描双指数模型拟合的慢弥散系数Dslow(slow diffusion coefficient)、快弥散系数Dfast(fast diffusion coefficient)和快弥散容积分数PF(perfusion fraction of Dfast)以及拉伸指数模型拟合的分布弥散系数DDC(distributed diffusion coefficient)和不均质指数α进行配对t检验、计算变异系数(coefficient of variability,CV)和绘制Bland-Altman(B-A)散点图;后者对2次测量的Dslow、Dfast、PF、DDC和α进行观察者间一致性检验,并计算CV.结果 健康志愿者各参数2次测量配对比较差异均无统计学意义(P＞0.05),CV值均小于5％,B-A散点图绝大多数(≥11/12)测值均位于95％一致性范围内;胶质瘤各参数2次测量一致性系数均大于0.75(P＜0.001),Dfast和PF的CV值最大,范围在5.0％～11.5％之间,其次是DDC和Dslow,α最小,CV值小于2％,除α外,其余参数CV值均随胶质瘤级别增高而增大.结论 健康脑白质评价中非高斯弥散加权成像各参数均具有较好的可重复性;胶质瘤评价中拉伸指数模型α具有最好的可重复性.     

磁共振功能成像诊断中央区前列腺癌的临床应用价值探讨

目的探讨磁共振功能成像（fMRI）在中央区前列腺癌诊断中的应用价值。方法回顾性分析20例经临床、病理检查证实为中央区前列腺癌患者的术前MRI图像,包括T2WI、动态对比增强MRI（DCE-MRI）、扩散加权成像（DWI）及表观扩散系数（ADC）,从而得到中央区前列腺癌的影像特征,计算fMRI在中央区前列腺癌检测中的准确率。结果20例患者前列腺中央区显示完整,fMRI共提示恶性病灶26个,24个与临床病理诊断相符合,其中9个病灶与外周带界限不清,另外2个病灶与病理诊断不符合。1例患者病理检查提示侵犯外周带而MRI显示不明显。MRI功能成脉对中央区前列腺癌诊断准确率92.31%。结论fMRI能显示前列腺中央区,并能对中央区前列腺癌作出较为准确的诊断,为临床治疗方案的选择提供理论依据。     

膝骨性关节炎患者MRIUTE分级与VAS评分关系的研究

目的探讨膝骨性关节炎（knee-osterarthritis,KOA）患者的MRI检查超短波长序列（UTE）分级与膝关节疼痛程度的关系。方法收集66例KOA患者的临床资料,对股骨内侧髁软骨UTE进行分级,就诊时患者的疼痛程度进行视觉模拟评分（VAS评分）,比较不同UTE分级患者的VAS评分,并对两者的关系作相关性分析。结果VAS评分均为重度疼痛时,UTE分级0、Ⅰ、Ⅱ、Ⅲ级者所占比例分别为10.0%（1/10）、21.7%（5/23）、33.3%（7/21）、50.0%（6/12）,差异有统计学意义（字2=5.936,P＜0.05）。Spearman相关分析显示,股骨远端内侧髁软骨UTE分级与VAS评分存在相关性（r=0.62,P＜0.01）。结论KOA患者的MRIUTE分级与膝关节疼痛程度存在相关性。     

鼻腔鼻窦内翻性乳头状瘤比较CT与MRI在诊断中的作用

【摘要】目的：分析鼻腔鼻窦内翻性乳头状瘤应用CT和MRI的诊断价值。方法：以102例病理检查确诊为鼻腔鼻窦内翻性乳头状瘤患者为研究对象,分别使用CT和MRI检查,对比CT和MRI检查结果与病理检查结果。结果：CT扫描可清晰显示NIP边界、NIP与鼻腔和鼻窦关系;MRI扫描可观察鼻腔鼻窦内黏膜及潴留分泌物,可清晰显示肿瘤及周边软组织关系。97例（95.1%）患者的CT检查分期符合病理检查结果,100例（98%）患者的MRI检查分期结果符合的病理检查结果,CT和MRI扫描分期符合率差异无统计学意义（P＞0.05）。结论：CT和MRI诊断NIP的价值较高,联合CT和MRI检查可提高疾病诊断率。