弥散加权成像在新生儿低血糖性脑病中的快速诊断价值

目的探讨弥散加权成像(DWI)在新生儿低血糖性脑病(HE)中的快速诊断价值。方法回顾性分析24例临床诊断符合新生儿HE的患者,均于出生后4~15 d内进行了头颅常规T1WI、T2WI、FLAIR和DWI扫描。比较患儿脑内T1WI、T2WI、FLAIR和DWI序列的表现。结果 24例新生儿HE中,顶枕叶受累22例(其中6例仅累及顶枕叶),胼胝体压部受累18例。病灶在DWI较T2WI信号高,且范围更清楚。DWI对新生儿HE病灶的显示率明显高于T1WI(χ2=59.733,P=0.000)、T2WI(χ2=36.771,P=0.000)和FLAIR(χ2=24.380,P=0.000)的显示率。结论新生儿HE在MRI上常表现为较特征的双侧顶枕叶和胼胝体压部受累,DWI有助于快速诊断急性期新生儿HE。     

Postmortem MR imaging in the fetal and neonatal period

Postmortem imaging has become an increasingly important part in the examination of deceased fetuses and neonates. This article discusses how to perform magnetic resonance (MR) imaging autopsy, including such technical determinators as field strength, and factors influencing image quality. Also included is a discussion on the indications for MR autopsy, including stillborns and terminations of pregnancy, and natural and unexplained death.     

体素内不相干运动弥散加权成像与弥散加权成像鉴别诊断甲状腺良恶性结节：Meta分析

目的 采用Meta分析方法评价体素内不相干运动弥散加权成像（IVIM-DWI）及弥散加权成像（DWI）鉴别诊断甲状腺良恶性结节的效能。方法 检索Cochrane Library、Embase、PubMed、中国知网、万方医学网及中国生物医学文献数据库,根据标准筛选建库至2020年5月IVIM-DWI及DWI参数鉴别诊断甲状腺良恶性结节相关文献,提取相关资料,以Stata 12.0和Meta-disc 1.4软件进行Meta分析。结果 纳入文献17篇文献,包括12篇英文、5篇中文文献,787个良性、634个恶性共1 421个甲状腺结节;根据真实扩散系数（D）值诊断的合并敏感度及特异度、阳性似然比及阴性似然比分别为0.85（0.71,0.92）、0.90（0.85,0.94）、8.77（5.29,14.55）及0.17（0.09,0.34）;表观扩散系数（ADC）的相应合并值分别为0.88（0.85,0.91）、0.90（0.85,0.94）、8.86（5.66,13.88）及0.13（0.10,0.16）,其AUC与D值差异无统计学意义（Z=-0.299,P=0.385）。异质性检验结果显示文献中ADC的合并特异度及D值的合并敏感度存在异质性。ADC值及D值诊断甲状腺良恶性结节无明显阈值效应（r=-0.113、-0.145,P=0.676、0.784）。分析研究类型、设备场强、b值、感兴趣区等因素,均未发现异质性的明确来源。结论 以D值及ADC值诊断甲状腺良恶性结节的效能相当,但IVIM-DWI参数可提供更多相关信息,且结果稳定性、可重复性更佳。     

全身磁共振弥散加权成像的临床应用及前景

20世纪90年代以来,随着磁共振成像(MRI)技术的飞速进展,弥散加权成像(diffusion-weighted imaging,DWI)法已广泛应用于扫描腹部、盆腔等颅外部位[1]。高梯度场的应     

健康成人肾脏磁共振体素内不相干运动及扩散张量成像的参数分析

目的分析磁共振体素内不相干运动成像(IVIM-DWI)及扩散张量成像(DTI)中成人正常双肾的各参数指标的特点,并评估各参数的可靠性。方法选择35位健康成人志愿者行肾脏IVIM-DWI及DTI扫描并将图像进行后处理,由2名影像科医师测量双肾上、下极及中部的皮、髓质IVIM-DWI参数D、D*、f值及DTI参数FA值,比较双侧肾脏,同侧肾不同部位及同部位的皮髓质之间各参数平均值的差异。结果 IVIM-DWI及DTI各参数在双侧肾脏间无统计学差异(P0.05);同侧肾脏在不同部位各参数测量值间亦无统计学差异(P0.05)。同部位肾脏D值在皮质高于髓质(t=3.215,P0.05),FA值在髓质高于皮质(t=-6.088,P0.05)而皮髓质的D*、f值差异无统计学意义(P0.05)。两次所测得的FA及D值组内相关系数分(ICC)具有较高可信度,D*及D值可信度一般。结论 FA及D值在肾皮、髓质中具有显著差异,且具有较高的可重复性,可作为反映肾功能的稳定指标;而D*及f值可重复性一般,尚需扩大样本进一步研究期应用价值。     

磁共振动态增强及扩散加权成像诊断乳腺纤维腺瘤

目的 探讨乳腺纤维腺瘤的动态增强MR及DWI特点。方法 回顾性分析59例经手术或穿刺病理证实的乳腺纤维腺瘤患者的MRI资料,观察病灶的形态特征、MR平扫、增强及DWI信号特点、时间-信号强度曲线类型,测量 ADC值。结果 59例共检出62个纤维腺瘤病灶,其中类圆形29个,分叶状33个;58个病灶边缘光滑;12个(12/62,19.35%)病灶于压脂T2WI 上可见低信号分隔。在动态增强图像上,2个病灶无或轻度强化,60个明显强化,其中34个(34/60,56.67%)可见低信号分隔,35个(35/60,58.33%)病灶呈离心模式强化。时间-信号强度曲线类型:I型43个(43/62,69.35%),Ⅱ型15个(15/62,24.19%),Ⅲ型2个(2/62,3.22%),Ⅳ型2个(2/62,3.22%)。DWI上高信号病灶45个(45/62,72.58%),等信号17个(17/62,27.42%)。共测量52个病灶的ADC值,为(0.79~2.78)×10^-3 mm²/s,平均ADC值为(1.67±0.38)×10^-3 mm²/s,95%可信区间为(1.56~1.78)×10^-3 mm²/s。结论 乳腺纤维腺瘤具有特征性MRI表现,结合ADC值有助于鉴别诊断。     

分段读出扩散加权成像在鼻咽癌检查中的价值

目的探讨分段读出扩散加权成像(RS-EPI DWI)相对于单次激发平面回波扩散加权成像(SS-EPI DWI)在鼻咽癌检查中的价值。方法收集30例经病理证实的未做任何治疗的鼻咽癌患者,采用Siemens 3.0 T Skyra磁共振扫描仪对患者常规平扫加增强扫描基础上加做鼻咽的轴位RS-EPI DWI及SS-EPI DWI序列,分别计算出鼻咽肿瘤区域的信噪比(SNR)、对比噪声比(CNR),以T_1增强轴位图像为参考,计算鼻咽层面图像的变形百分比,测量鼻咽肿瘤长、短径,比较SS-EPI DWI、RS-EPI DWI图像上肿瘤大小的准确性,比较颅底层面磁敏感伪影幅度。结果RS-EPI DWI较SS-EPI DWI图像的SNR(t=34.074,P0.01)、CNR(t=23.120,P0.01)值高,图像变形较轻,相同解剖层面,RS-EPI DWI图像测出的肿瘤大小更接近增强后T1轴位上病灶大小,颅底层面RS-EPI DWI图像磁敏感伪影明显较弱(b值为0 s/mm~2时t=10.634,P0.01,b值为1000 s/mm~2时t=8.219,P0.01),两名医师分别对SS-EPI DWI、RS-EPI DWI的ADC图病灶区进行测值,两组测值在判断病灶扩散受限上统计学差异(t=0.00,P=1.000.05)。结论分段读出扩散加权成像较传统的弥散加权成像图像质量更佳,其临床应用更有价值,对于诊断的准确性具有积极的作用。     

病毒性脑炎的磁共振成像和扩散加权成像表现

目的探讨病毒性脑炎的核磁共振成像(MRI)和扩散加权成像(DWI)表现。方法71例病毒性脑炎患者,28例颅内有病灶者为A组,43例颅内无病灶者为B组;100例正常成人作为对照组。3组均进行常规MRI及DWI检查,比较病毒性脑炎与正常成人的额叶白质、颞叶白质、侧脑室旁及基底节-丘脑区的平均表观扩散系数(ADC)值的差异。结果 A组病毒性脑炎患者额叶白质、颞叶白质、侧脑室旁及基底节-丘脑区的平均ADC值分别为(1.070±0.21)×10-3mm2/s、(1.110±0.21)×10-3mm2/s、(1.080±0.19)×10-3mm2/s、(1.030±0.18)×10-3mm2/s;B组病毒性脑炎患者额叶白质、颞叶白质、侧脑室旁及基底节-丘脑区的平均ADC值分别为(0.789±0.05)×10-3mm2/s、(0.813±0.04)×10-3mm2/s、(0.789±0.04)×10-3mm2/s、(0.779±0.03)×10-3mm2/s;正常成人的额叶白质、颞叶白质、侧脑室旁及基底节-丘脑区的平均ADC值分别为(0.7961±0.04)×10-3mm2/s、(0.805±0.05)×10-3mm2/s、(0.785±0.03)×10-3mm2/s、(0.770±0.02)×10-3mm2/s。A组的平均ADC值较B组及对照组均升高,差异具有统计学意义(P均<0.05),而B组与对照组差异无统计学意义(P均>0.05)。结论DWI及ADC可反映病毒性脑炎病变组织的微观结构变化信息,是常规MRI非常有价值的补充,与临床诊断相结合,有助于病毒性脑炎的诊断。但在病毒性脑炎早期尚未形成可见的颅内病灶者,MRI包括DWI及ADC对病毒性脑炎的诊断受到限制,尚需进一步探讨。     

A comparison of fetal biometric ratios to neonatal morphometrics

Ratios of fetal abdominal circumference to femur length (AC/FL) and thigh circumference to femur length (TC/FL) have been suggested as indices of fetal nutrition. Birthweight, skin-fold thickness, and ponderal index are accepted neonatal indices of nutrition. The purpose of this study was to compare fetal to neonatal indices of nutrition. In 52 patients in term labor, fetal abdominal circumference, thigh circumference, and femur length were measured ultrasonographically. Neonatal skin-fold thickness was calculated as the average of tricipital, subscapular, abdominal, and anterior thigh measurements determined with Harpenden skin-fold calipers. Linear correlation analysis demonstrated a significant relationship between AC/FL and ponderal index (r = 0.340, P = 0.028) and between TC/FL and ponderal index (r = 0.368, P = 0.007). Neither AC/FL nor TC/FL were significantly related to birthweight or skin-fold thickness. These data suggest that the diagnostic reliability of antenatal studies of fetal biometric ratios may be enhanced by using the ponderal index as a neonatal endpoint rather than birthweight or skin-fold thickness.     

Relation of fetal femur length to neonatal crown-heel length

Sonographically measured femur lengths in 102 fetuses were compared with neonatal crown-heel lengths within 72 hours of delivery. The optimal model for describing crown-heel length as a function of femur length was a linear model, with a coefficient of determination (r2) of 66 per cent; the standard deviation in predicting crown-heel length from femur length was 2.4 cm. These data were compared with autopsy data from the literature, which showed an even stronger correlation between femur length and crown-heel length. Because of the strong correlation between these two dimensions, the femur length should prove useful in the detection of intrauterine growth retardation when crown-heel length is compromised. It should also be useful as a variable in the prediction of fetal weight in utero, since crown-heel lengths at the extremes of normal can significantly affect in utero weight estimates using ultrasound.     

扩散加权成像和表观扩散系数值在病毒性脑炎的应用

目的探讨扩散加权成像（DWI）和表观扩散系数（ADC）值在病毒性脑炎的应用价值。方法病毒性脑炎28例进行MRI平扫加DWI检查。病灶部位及对侧相应正常脑组织分别进行ADC值测量,比较两侧部位的ADC值大小。结果病毒性脑炎病灶ADC值较对侧相应正常区域明显升高,（1.11±0.21）×10-3mm2/s vs（0.84±0.05）×10-3mm2/s（P〈0.01）。结论 DWI及ADC值可以反映病毒性脑炎病变组织的微观结构变化信息,对病毒性脑炎的诊断与其临床诊断相符合,可为常规MRI检查提供补充信息,对其临床诊疗和评估也有一定的价值。     

肝脏恶性肿瘤扩散加权成像与T2加权成像对比研究

目的比较肝脏扩散加权成像(DWI)和T2WI反映肝脏恶性肿瘤扩散特征、病理特征及肿瘤范围的价值.方法回顾性研究肝脏恶性肿瘤44例48灶(肝细胞癌30例30灶,肝转移瘤10例14灶,胆管细胞癌4例4灶),比较DWI与T2WI图像液体(脑脊液,胆囊胆汁)和肝脏恶性肿瘤的信号,肿瘤/肝脏信号强度比(SIR),对比噪声比(CNR)以及肿瘤范围,测量肿瘤表观扩散系数(ADC)值.结果在b=600 s/mm2的图像中,所有病例的脑脊液均显示为低信号.肝脏恶性肿瘤多表现为高信号,其信号分布特征与T2WI不同;肿瘤的信号强度和瘤/肝SIR,DWI与T2WI不相关;DWI信号强度与ADC值呈负相关.DWI的病灶对比噪声比高于T2WI,二者差异有显著性.DWI显示病灶范围与T2WI差异无显著性.结论b=600 s/mm2的肝脏DWI图像受T2穿透效应影响较小,能够较好地反映肝脏恶性肿瘤的扩散特征.DWI肿瘤对比噪声比更高,有助于病灶边界的确定.DWI反映的肝脏恶性肿瘤的扩散特征,可作为其影像学特征之一.     

以直肠内线圈进行前列腺扩散加权成像的可行性研究

目的以腹部相控阵线圈获得的前列腺常规DWI成像为标准,研究以1.5T磁共振系统进行直肠内线圈DWI成像所得前列腺ADC值的准确性。方法随机选择20例同时进行了常规DWI和直肠内DWI的前列腺病例,比较两种DWI图像的空间分辨率和信噪比。以第三方软件逐点测量前列腺的ADC值,并手动测量ADC值,与常规方法所得ADC值进行对比,分析直肠内线圈所得ADC值的可用性。结果直肠内DWI的空间分辨率明显高于常规DWI,两种DWI信噪比无显著性差异。观察获得的散点图,发现与直肠内线圈表面相距22.9 mm以内的ADC值与常规ADC值差异不大。在前列腺外周带手工测量两种ADC值,无统计学差异,相关系数为0.820。结论前列腺直肠内线圈DWI图像分辨率高,但仅距离线圈前表面约22.9 mm以内的ADC值与常规ADC值具有可比性。     

脑干急性梗死弥散加权成像的相关性分析研究

目的应用弥散加权成像(DWI)探讨脑干急性梗死的发生率及其与年龄、性别的相关性。方法对连续8 063例行头颅MRI和DWI检查的患者资料进行回顾性分析,年龄1~98岁,平均62岁。按性别及年龄进行分组,观察脑干急性梗死的发生率并进行统计分析。结果 8 063例中,脑干急性梗死175例,发生率为2.17%,<20岁、20~39岁、40~59岁、60~79岁和≥80岁年龄组脑干急性梗死的发生率依次为0(0/552)、0.70%(4/568)、1.99%(59/2 966)、2.61%(91/3 484)和4.26%(21/493)。脑干急性梗死男、女发生率分别为2.87%(120/4 177)和1.42%(55/3 886),性别间差异有统计学意义(χ2=20.142,P=0.000)。结论脑干急性梗死的总体发生率为2.17%,随年龄增长发病率呈上升趋势,男性多见。     

Large deformation diffeomorphic registration of diffusion-weighted imaging data

Registration plays an important role in group analysis of diffusion-weighted imaging (DWI) data. It can be used to build a reference anatomy for investigating structural variation or tracking changes in white matter. Unlike traditional scalar image registration where spatial alignment is the only focus, registration of DWI data requires both spatial alignment of structures and reorientation of local signal profiles. As such, DWI registration is much more complex and challenging than scalar image registration. Although a variety of algorithms has been proposed to tackle the problem, most of them are restricted by the diffusion model used for registration, making it difficult to fit to the registered data a different model. In this paper we describe a method that allows any diffusion model to be fitted after registration for subsequent multifaceted analysis. This is achieved by directly aligning DWI data using a large deformation diffeomorphic registration framework. Our algorithm seeks the optimal coordinate mapping by simultaneously considering structural alignment, local signal profile reorientation, and deformation regularization. Our algorithm also incorporates a multi-kernel strategy to concurrently register anatomical structures at different scales. We demonstrate the efficacy of our approach using in vivo data and report detailed qualitative and quantitative results in comparison with several different registration strategies.     

全身磁共振扩散加权成像正常表现

目的探讨全身磁共振扩散加权成像(magnetic resonance diffusion-weighted imaging,MRIDWI)正常影像表现。方法正常志愿者16例,在知情同意下接受全身磁共振扩散加权成像检查,分析全身MR DWI的正常表现。结果所采集图像都能满足影像分析要求,背景抑制效果较好。正常人骨骼系统呈低或等信号。双肺、纵隔、肝脏,血管、肌肉、脂肪呈低信号。颅脑、脾脏、双肾、子宫肌层、子宫内膜和前列腺外周带、睾丸、阴茎呈高信号。神经根及正常小淋巴结也显示为高信号。结论全身MR DWI可以在30分钟内对全身组织成像。熟练掌握全身MR DWI的正常表现,有利于加深对病变的认识,为进一步临床诊断应用打下基础。     

肝囊肿的弥散加权成像研究

目的 分析不同b值肝囊肿弥散加权像(DWI)的信号特点,并测量ADC值,为DWI对其他肝脏疾病的研究提供方向.方法 50例肝囊肿112个病灶进行磁共振DWI,分析b值为300、500、1000 s/mm2肝囊肿的DWI信号表现,并测量ADC值,分析b值为300、500 s/mm2时ADC值的分布情况.结果 肝囊肿在3种b值(300、500、1000 s/mm2)的DWI表现为低信号分别占79.5%、83.0%、92.0%,等信号分别占13.4%、11.6%、7.1%,高信号分别占7.1%、5.4%、0.9%;平均ADC值分别为(4.10±0.11)×10-3、(4.09±0.14)×10-3、(3.85±0.12)×10-3 mm2/s;b值＝300、500 s/mm2时;ADC值＝4.10×10-3 mm2/s分别为91例(占81.3%)、61例(占54.5%).结论 肝囊肿在DWI主要表现为低信号,且ADC值较稳定,选b=300、500 s/mm2时,ADC值接近一固定值4.10×10-3 mm2/s,结合DWI及ADC值可确诊肝囊肿.     

全身弥散加权成像观察骨转移瘤

目的 评价MR全身弥散加权成像(WB-DWI)在检测骨转移瘤中的作用及可行性. 方法 对20例恶性肿瘤并发骨转移患者(病变组)及20名健康人(对照组)行WB-DWI检查,6个月后对病变组患者行WB-DWI或核素骨显像复查. 结果 WB-DWI在20例患者中共检出57处骨转移灶,B-DWI在肱骨和股骨近端检出7处核素骨显像阴性病灶.病变组患者6个月后复查,9例骨转移灶进展,3例化疗后骨转移灶信号下降. 结论 WB-DWI可用于早期筛选骨转移瘤,也可发现骨外转移病灶.     

Large deformation diffeomorphic registration of diffusion-weighted imaging data

Registration plays an important role in group analysis of diffusion-weighted imaging (DWI) data. It can be used to build a reference anatomy for investigating structural variation or tracking changes in white matter. Unlike traditional scalar image registration where spatial alignment is the only focus, registration of DWI data requires both spatial alignment of structures and reorientation of local signal profiles. As such, DWI registration is much more complex and challenging than scalar image registration. Although a variety of algorithms has been proposed to tackle the problem, most of them are restricted by the diffusion model used for registration, making it difficult to fit to the registered data a different model. In this paper we describe a method that allows any diffusion model to be fitted after registration for subsequent multifaceted analysis. This is achieved by directly aligning DWI data using a large deformation diffeomorphic registration framework. Our algorithm seeks the optimal coordinate mapping by simultaneously considering structural alignment, local signal profile reorientation, and deformation regularization. Our algorithm also incorporates a multi-kernel strategy to concurrently register anatomical structures at different scales. We demonstrate the efficacy of our approach using in vivo data and report detailed qualitative and quantitative results in comparison with several different registration strategies.