正常脑老化过程中脑组织水分子扩散系数的变化规律

目的 探讨正常脑老化过程中脑内各部位的表观扩散系数(ADC)的年龄变化规律.资料与方法 120名健康自愿者(男、女各60名),按年龄分为6组,每组20名.所有自愿者均于3.0 T MR上行颅脑常规扩散加权成像(DWI)及液体衰减反转恢复(FLAIR)DWI.在两侧大脑半球各选择19个能够清楚辨别的神经解剖结构进行ADC值的测量和分析.结果 脑组织的平均ADC值为(7.41±0.56)×10-4mm2/s,皮层灰质显著高于白质.顶叶灰白质、额叶灰白质、枕叶灰质、颞叶白质、小脑白质、豆状核、丘脑、内囊、半卵圆区、扣带回及胼胝体膝部的ADC值在不同年龄段间差异有统计学意义(P<0.05),而且这种年龄组间ADC值的差异现象在60岁后明显,60岁前只有枕叶灰质和丘脑的ADC值在不同年龄段之间存在差异.顶叶白质、额叶白质及胼胝体膝部、半卵圆区、额叶灰质、丘脑的ADC值与年龄增长呈明显的正性相关(P<0.05).结论 不同部位ADC值存在年龄差异,这种差异在60岁后明显;脑组织ADC值随年龄增长而增加(以白质为主),皮层灰质见于额叶.     

液体衰减反转恢复脉冲对DWI图像信噪比及ADC值的影响

目的:探讨液体衰减反转恢复(FLAIR)脉冲序列对扩散加权图像(DWI)信噪比及ADC值的影响.方法:17名健康志愿者在3.0T MRI上行常规轴位DWI和FIAIR-DWI扫描,分别测量两侧半卵圆区、扣带回、丘脑及胼胝体膝部和压部的ADC值及DWI信号强度,同时测量基底节层面的DWI信号强度作为噪声,计算以上5个部位DWI图像的信噪比.结果:扣带回和胼胝体压部的ADC值在施加FLAIR脉冲后显著下降,而半卵圆区、丘脑及胼胝体膝部在施加FLAIR脉冲前后无明显变化;5个部位的DWI图像信噪比在施加FLAIR脉冲后均显著下降(P＜0.01).结论:FLAIR显著提高了脑组织和脑脊液ADC值测量的准确性,但是也明显降低了DWI图像的信嗓比.     

3D-ASL磁共振成像检查各脑区血流量及年龄与性别因素对其影响

目的探讨年龄、性别因素对3D-ASL测量各脑区血流量有无影响。方法抽取在本院常规体检项目、神经系统检查及MRI检查均正常,MRA无颅内动脉异常的健康体检者共64例(男性34例,女性30例)为研究对象,按年龄分为青年(≤44岁)19例、中年(45~59岁)19例及老年组(≥60岁)26例三组,行3D-ASL检查(GE Discovery MR750w3.0T)。采用Functool-ASL后处理软件(Adw 4.6版本)进行图像后处理,ROI选取双侧对称区域的小脑皮层、丘脑核团、额叶、颞叶、顶叶、枕叶皮层,测量并记录各脑区的CBF(Cerebral Blood Flow)值。统计学分析使用SPSS Statistics 17.0,双侧脑区对称区域CBF值差异采用配对t检验、各年龄及性别分组间差异采用方差分析(P0.05为具有统计学意义);采用分别控制变量(年龄、性别)的偏相关分析各组、各脑区CBF值有无相关性。结果 64例研究对象中,除青年组1例、老年组2例运动伪影不能明确测量CBF外,其余61例(男性32例,女性29例)均获得了各脑区的CBF值。双侧各脑区对称区域CBF值差异的配对t检验P值均大于0.05。年龄分组时中年组除双侧小脑、右丘脑外,各脑区CBF均值略高于青年和老年组各脑区,老年组的双侧小脑、右丘脑的CBF均值略高于青年和中年组,方差分析P值均大于0.05,CBF值的差异无统计学显著意义。性别分组时除左丘脑外,女性各脑区CBF均值高于男性,其中左、右小脑及右额叶的差异具有统计学意义(P值分别为0.007,0.000及0.032)。控制变量的偏相关分析显示双侧各脑区CBF值与年龄无相关性,左、右小脑及右额叶的CBF值与性别相关(分别为r=0.627,P=0.009,r=0.812,P=0.000,r=0.511,P=0.043),其余脑区与性别无相关性。结论 3D-ASL测量各脑区CBF时,年龄因素无显著影响;女性除左侧丘脑外,各脑区的CBF值均高于男性,其中双侧小脑及右额叶的性别差异具有统计学意义。     

采用磁敏感加权成像技术研究年龄相关的脑铁沉积现象

目的 采用磁敏感加权成像技术,探讨正常人大脑不同区域的铁含量随年龄变化的规律.方法 78名成年健康志愿者按照年龄分为青年组(≤35岁)27名、中年组(36～55岁)35名和老年组(≥56岁)16名,所有受试者均进行磁敏感加权成像,在校正相位图上分别测量苍白球、壳核、尾状核、黑质、红核、丘脑和额叶白质的相位值.30岁以上受试者各脑区的平均相位值和文献报道的脑铁实际含量进行Pearson相关分析,采用单因素方差分析比较各脑区不同年龄组之间的校正相位值差异.用线性回归分析法进一步研究由方差分析法所揭示的年龄相关的铁含量变化,并计算其变化率.结果 各脑区的平均相位值和文献报道的脑铁实际含量问存在负相关性(r=-0.796,P=0.032),铁含量多的脑区相位值的负值大.青年组、中年组和老年组壳核相位值的中位数分别是-0.0185、-0.0362和-0.0566,额叶白质相位值中位数分别是0.0034、-0.0031和-0.0021,各年龄组间的差异具有统计学意义(F值分别为20.115、3.536,P值分别＜0.01、＜0.05).线性回归分析表明,壳核、红核和额叶白质的铁含量随着年龄的增加而增加(回归系数分别为-0.001、-0.001、＜-0.001,P值均＜0.05),苍白球、尾状核、黑质和丘脑的铁含量不随年龄而变化.结论 研究结果证明并拓展了对年龄相关的脑铁沉积现象的认识,为全面、准确认识疾病相关的脑铁异常沉积现象提供了必要的基础.     

孤立性侧脑室扩张胎儿脑的MRI弥散加权成像评估

目的:探讨ADC值对胎儿侧脑室扩张的诊断价值。方法:对50例轻度孤立性侧脑室扩张胎儿(轻度扩张组)及50例重度孤立性侧脑室扩张的胎儿(重度扩张组)行DWI扫描,分别测量胎脑双侧额叶、顶叶、颞叶、枕叶白质、基底核、丘脑及小脑ADC值,比较两组各脑区ADC值差异及各个侧脑室扩张胎儿左侧及右侧各脑区ADC值的差异。结果:与轻度扩张组比较,重度扩张组双侧额叶、顶叶,枕叶白质及基底核ADC值下降(P均<0.05)。侧脑室扩张胎儿左侧与右侧各脑区ADC值差异均无统计学意义(P均>0.05)。结论:重度侧脑室扩张胎儿额叶、顶叶,枕叶,基底节ADC值下降,ADC值对检测潜在脑部损伤较敏感,有助于评估胎儿孤立性侧脑室扩张神经系统改变。     

青年人与老年人海马体积及形态的MR研究

目的 在区分海马标志点的基础上,测量青年人和老年人正常海马及其头、体、尾3个部位的体积、形态.方法 选择正常青年人(年龄20～29岁,青年组)和老年人(60岁以上,老年组)志愿者各30名进行头部MR扫描,所得图像经后处理软件分析,确定较恒定、易辨认的解剖标志点后对海马进行分割.测量青年组和老年组海马的体积、平均扫描层面积及扫描层数,两组间以及青年组和老年组不同性别、不同侧别海马体积的比较采用独立样本t检验,并作海马的三维重建.结果 60名受试者钩隐窝、脑室三角、钩顶等均能清晰显示.青年组和老年组不同性别间海马体积差异均无统计学意义.青年组左侧海马头部、体部、尾部及整体体积分别为(1250±174)、(653±115)、(372±116)、(2277±109)mm~3,右侧分别为(1255±147)、(657±129)、(386±105)、(2298±213)mm~3,左、右侧间差异均无统计学意义(t值分别为0.08、0.10、0.33、0.35,P值均＞0.05).老年组左侧海马头部、体部、尾部及整体体积分别为(660±109)、(472±92)、(181±73)、(1313±163)mm~3,右侧分别为(717±116)、(474±95)、(240±75)、(1432±171)mm~3,右侧海马尾部体积明显大于左侧,差异具有统计学意义(t=2.21,P＜0.05);其他部位左、右侧海马体积差异均无统计学意义(t值分别为1.39、0.06、1.95,P值均＞0.05).青年组和老年组左侧海马头部、体部、尾部及整体体积差异均有统计学意义(t值分别为15.78、6.71、7.70、20.83,P值均＜0.05),右侧各部位差异也均有统计学意义(t值分别为15.76、6.26、6.15、17.36,P值均＜0.05).老年组各部位体积明显小于青年组,其中以头部最为明显.青年组及老年组海马头部左侧层面积分别为(75±24)、(56±21)mm~2,右侧层面积分别为(73±22)、(58±19)mm2,两组间差异均有统计学意义(t值分别为3.33、2.81,P值均＜0.01).青年组及老年组左侧层数分别为(11.1±3.2)、(7.9±3.9)层,右侧层数分别为(11.5±3.7)、(8.2±3.1)层,两组间差异也均有统计学意义(t值分别为3.48、3.75,P值均＜0.05).老年组的海马头部层数和层面积均小于青年组,呈短而窄的外形.结论 根据海马标志点确认的原则,其所提出的标志点为海马形态体积的标准化测量提供了测量的基础,其所测的正常值有助于疾病的诊断或为某些疾病发病机制的研究提供基础.     

健康成人脑组织ADC值的测量及其影响因素分析

目的 测量健康成人脑组织的表观弥散系数(apparent diffusion coefficient, ADC)值,比较左右两侧脑结构的弥散特征,分析年龄和性别对ADC值的影响.方法 50例健康成人志愿者行弥散加权成像(diffusion-weighted imaging, DWI).在DWI图像上选取23个脑区,左右对称性放置ROI行ADC值测量.结果 不同解剖区域平均ADC值由高到低依次为: 大脑皮层灰质[(0.760±0.054)×10-3mm2/s]、侧脑室周围白质[(0.728±0.097)×10-3mm2/s]、海马[(0.722±0.096)×10-3mm2/s]、大脑白质[(0.709±0.076)×10-3mm2/s]、杏仁体[(0.705±0.098)×10-3mm2/s]、内囊[(0.678±0.094) ×10-3mm2/s]、丘脑[(0.664±0.116)×10-3mm2/s]、基底节灰质[(0.636±0.095)×10-3mm2/s]、桥脑[(0.534±0.096)×10-3mm2/s].除颞叶皮层,颞、顶、枕叶白质,半卵圆中心和侧脑室体后白质的ADC值有显著的左右侧差异外(P<0.01),其余部位左右侧均无显著性差异(P>0.05).壳核、左内囊前肢和膝部及脑室周围白质(额角、枕角、侧脑室体前和体后)的ADC值与年龄呈正相关(r≥0.40,P＜0.05), 其中左内囊膝部和左右侧额角周围白质ADC值与年龄呈直线相关(P＜0.05).各部位脑组织的ADC值均无性别差异(P>0.05).结论 健康成人脑组织的ADC值受年龄和左右侧别的影响,这将为今后DWI的定量研究及临床应用提供参考.     

正常成人肾脏磁共振扩散加权成像研究

目的 通过测量正常成人肾脏磁共振扩散加权成像(DWI)时的表观弥散系数(ADC)值,为肾脏病变患者在DWI成像时提供正常对照标准.资料与方法 20例健康志愿者均行MRI常规平扫及DWI成像,DWI成像时b值分别采用0s/mm2、200s/mm2、500s/mm2、800s/mm2、1000s/mm2.结果 不同b值下双侧肾脏皮髓质ADC值及双侧肾脏平均ADC值差异有统计学意义(F=57.863～240.324,P=0.000),双侧肾脏皮髓质ADC值及平均ADC值均高于肝、脾及胰腺ADC值.双侧肾脏皮质在不同b值下的ADC值均高于髓质,差异有统计学意义(t=8.436～20.281,P=0.000).左侧肾脏皮、髓质ADC值及平均ADC值在b=500s/mm2、b=800s/mm2及1000s/mm2时均高于右侧,差异有统计学意义(b=800s/mm2时t=2.023,P=0.048;其余P=0.000).b=200s/mm2时双侧肾脏皮、髓质ADC值及平均ADC值之间差异无统计学意义(t=1.739,P=0.098;t=0.704,P=0.490;t=-0.314,P=0.757).结论 正常成人肾脏ADC值在不同b值下有差异,双侧肾脏平均ADC值亦存在差异.     

脑组织ADC值定量研究的影响因素分析

目的:探讨不同的MR成像技术对脑组织近似弥散系数(ADC)定量的影响.材料和方法:使用5种不同的弥散敏感系数(b值)(b=500、1 000、1 500、2 000、3 000s/mm2)在3T MR上对17名志愿者进行颅脑弥散加权成像(DWI)以及b=1 000s/mm2下的液体翻转衰减恢复弥散加权成像(FLAIR-DWI);其中10名志愿者完成3TMR检查后,再用1.5T MR进行b=1 000s/mm2的颅脑弥散加权成像.获得ADC图后,分别测量两侧半卵圆中心、扣带回、丘脑、胼胝体膝部、胼胝体压部及侧脑室体部的ADC值,并进行统计学分析.结果:b值的增加使脑组织的ADC值显著下降,FLAIR可以明显降低脑脊液对ADC值测量的污染;不同MR扫描仪对ADC值的定量无显著影响.结论:DWI参数的选择对ADC值的测量有着显著的影响,尤其是b值,最佳的b值应该为1 000s/mm2,因而在研究中必须始终保持扫描参数的一致;DWI前施加FLAIR抑止脑脊液信号明显减轻了脑脊液部分容积效应对ADC值测量的影响,这对于脑萎缩患者的ADC值测量有着十分重要的价值;同一厂家生产的不同场强的MR成像系统对ADC值定量研究无显著影响.     

表观弥散系数定量测量评价足月新生儿缺氧缺血性脑病的初步研究

目的 探讨表观弥散系数(ADC)定量测量在评价足月新生儿缺氧缺血性脑损伤(HIE)中的价值.方法 对31例临床诊断为HIE的足月新生儿(按临床诊断标准轻度组10例,中度组13例,重度组8例),进行常规MRI和DWI检查(b=1000 s/mm2),同时选择6例正常足月新生儿做对照研究.测量各感兴趣区平均ADC值,并进行组间比较.结果 中度组内囊后肢(PLIC)和放射冠ADC值均较对照组下降(P=0.003和P=0.001),重度组PLIC、放射冠、丘脑、豆状核和顶叶白质ADC值均较对照组下降(P值均＜0.05),重度组PLIC的ADC值较中度组下降(P＜0.001).其中PLIC的ADC值下降与临床分度相符合程度高.结论 ADC值定量测量可为早期诊断HIE提供客观依据,PLIC的ADC值定量测量在预后转归评价方面可能具有重要的价值.     

Regional diffusion changes of cerebral grey matter during normal aging—A fluid-inversion prepared diffusion imaging study

Background and purpose

Although diffusion characteristics of white matter (WM) and its aging effects have been well described in the literature, diffusion characteristics of grey matter (GM), especially the cortical GM, have not been fully evaluated. In the present study, we used the fluid-inversion prepared diffusion imaging (FLIPD) technique to determine if there are age-related water diffusivity changes in GM.

Materials and methods

120 healthy volunteers were recruited for our study. They were divided into three age groups: group one (20-39 years old), group two (40-59 years old) and group three (60 years or older). All patients were evaluated with MRI using FLIPD at 3.0 T. Apparent diffusion coefficient (ADC) values of the frontal GM, cingulate cortex and thalami were determined bilaterally by region-of-interest analysis.

Results

Group three had significantly higher ADC values in both thalami and the left frontal GM compared to group two or group one. No ADC value difference was found among the three groups in the right frontal GM and bilateral cingulate cortex. There was a significant positive correlation between individual ADC values and age in both thalami and left frontal GM. For the cingulate cortex and the right frontal GM, ADC values did not correlate significantly with advancing age.

Conclusion

Statistically significant age-related diffusion changes were observed in both thalami and the left frontal cortex. The data reported here may serve as a reference for future studies.     

DWI在胎儿后颅窝池扩张中的研究

目的 测量后颅窝池扩张胎儿脑部表观扩散系数(ADC),探讨DWI及ADC值在后颅窝池扩张胎儿的应用.方法 16例后颅窝池扩张胎儿及16例对照进行DWI扫描及ADC值测量,比较2组各脑区ADC值差异及后颅窝池扩张胎儿左右脑区ADC值差异.将ADC值、后颅窝池扩张程度分别与孕周进行相关分析.结果 后颅窝池扩张胎儿脑部ADC值在双侧额叶及顶叶白质、双侧丘脑及小脑下降;后颅窝池扩张胎儿左右脑区ADC值差异无统计学意义(P>0.05);双侧基底节区和丘脑ADC值与孕周呈负相关(P<0.05),后颅窝池扩张程度与孕周未见相关(P>0.05).结论 后颅窝池扩张胎儿多个脑区出现ADC值下降,提示ADC值对于检测潜在脑部损伤更为敏感,常规序列结合DWI及ADC值能更准确地检测胎儿异常.     

多发性硬化患者脑灰质损害的MRI表现及扩散张量成像定量研究

目的 分析多发性硬化(MS)患者脑灰质病灶的MRI特征及表现正常的脑灰质(NAGM)是否存在隐匿性损伤.方法 对34例临床确诊的MS患者(MS组)和25名健康志愿者(对照组)行常规头颅MRI和扩散张量成像(DTI),观察MS的脑灰质病灶特征,测量深部灰质核团的平均扩散率(ADC)和各向异性分数(FA),采用非配对t检验比较两组间是否存在差异.结果 MR检查发现MS的脑灰质病灶共83个,占全部病灶(443个)的18.7%.分布以额叶最多,其次是颞叶与丘脑.大多数病灶呈圆形或类圆形,其中T2WI发现灰质病灶60个,液体衰减反转恢复(FLAIR)序列T2WI发现病灶78个,其中71个病灶呈高或稍高信号,3个病灶呈中心低、周围稍高的环形改变,4个呈低信号.扩散加权成像(DWI)发现高信号或低信号病灶36个,其中有9个小病灶在DWI呈明显高信号.其余病灶呈等信号而不能被发现.MS组尾状核头、壳核、丘脑的ADC值分别为(8.0±0.7)、(7.4 ±0.5)、(7.7±0.4)×10-4mm2/s,均高于对照组[分别为(7.4±0.6)、(7.0 ±0.5)、(7.2±0.7)×10-4mm2/s],差异具有统计学意义(t值分别为-3.079、-2.564、-2.722,P值均<0.05).结论 MS的脑灰质病灶在常规MRI和DWI上的表现有一定的特征,FLAIR联合DWI可提高病灶的检出,DTI可以反映出NAGM内的隐匿性损害.     

0.5T磁共振机弥散加权像诊断急性脑梗塞

目的：分析０．５Ｔ磁共振机的弥散加权像（ＤＷＩ）对急性脑梗塞诊断的临床价值。材料与方法：计算５０例健康志愿者正常脑组织各不同部位的表观弥散系数（ＡＤＣ）值,并对急性脑梗塞发作后３～１２小时的１０名患者进行ＤＷＩ及常规Ｔ_１ＷＩ、Ｔ_２ＷＩ、ＦＬＡＩＲ及ＭＲＡ检查。结果：测得正常人额、顶、枕叶脑白质、半卵圆中心、基底节、脑干、小脑半球、脑脊液部位的ＡＤＣ平均值。对于临床患者,ＤＷＩ可明确显示急性期脑梗塞病灶,常规Ｔ_１ＷＩ、Ｔ_２ＷＩ、ＦＬＡＩＲ均不能显示或显示不清。结论：以ＤＷＩ为主,结合Ｔ_１ＷＩ、Ｔ_２ＷＩ、ＦＬＡＩＲ及ＭＲＡ序列能非常准确、可靠的诊断急性脑梗塞。     

磁共振扩散加权成像评价胎儿肾脏功能的初步研究

目的：探讨表观扩散系数(ADC)值在正常胎儿肾脏上是否具有规律及特点,为应用磁共振扩散加权成像(DWI)评价胎儿肾脏功能提供正常数据参考。方法对71例经超声和常规 MR 检查均诊断肾脏正常的胎儿进行产前 DWI 扫描,b 值取100、200、500、700 s/mm2,分别统计分析左右肾感兴趣区(ROI)同 b 值、ADC 值差异,单侧肾不同 b 值、ADC 值差异以及双肾平均 ADC值与孕周的相关性。结果除 b=100 s/mm2,左右肾间 ADC 值存在统计学差异,其余各组间比较均无统计学差异。同侧肾不同 b值比较中,除右肾 b=100 s/mm2与 b=700 s/mm2组间比较无统计学意义,其余各组间比较均有统计学意义。同时随孕周增大,双肾 ADC 值均呈下降趋势。结论DWI 评价胎儿肾脏发育是可行的,不同 b 值得到的 ADC 值可作为定量参数评估正常胎儿肾脏发育情况。     

Diffusion-weighted MR imaging in Japanese encephalitis

OBJECTIVE: This study was performed to evaluate the role of diffusion-weighted imaging (DWI) in the diagnosis of Japanese encephalitis (JE) and to look for any relationship of the apparent diffusion coefficient (ADC) values with duration of the illness. METHODS: We performed DWI in fourteen patients of JE. T2 weighted (T2W) and DWI were compared for number and location of lesions in all patients. Based on imaging patients were divided in three groups: group 1 (n=9) showing more lesions on DWI compared with T2W images, group 2 (n=3) with equal number of lesions on T2W and DWI and group 3 (n=2) with lesions more pronounced on T2W than DWI. ADC values were computed for all the lesions. The time interval between onset of neurologic signs/symptoms and MRI were charted and correlated with ADC values. RESULTS: DWI was helpful in making early diagnosis of JE by showing characteristic involvement of bilateral thalami in four patients. Nine out of fourteen patients showed additional lesions on DWI. ADC from lesions in groups I, II and III measured 0.648 +/- 0.099 x 10 mm/s, 0.739 +/- 0.166 x 10 mm/s and 1.123 +/- 0.185 x 10 mm/s respectively. The ADC from the lesions in group 1 was significantly lower compared with group 2 (P value <0.05) while it was higher in group 3 lesions compared with the other two groups. There was a significant direct correlation of ADC values with the disease duration in these cases (r=0.847, P <0.01). CONCLUSIONS: DWI is helpful in early diagnosis and characterization of the duration of the lesions in JE.     

Influence of fluid-attenuated inversion-recovery on stroke apparent diffusion coefficient measurements and its clinical application

Background and purpose

The application of a fluid-attenuated inversion-recovery pulse with a conventional diffusion-weighted MRI sequence (FLAIR DWI) decreases the partial volume effects from cerebrospinal fluid on apparent diffusion coefficient (ADC) measurements. For this reason, FLAIR DWI may be more useful in the evaluation of ischemic stroke, but few studies have looked at the effect of FLAIR on ADC measurements in this setting. This study quantitatively compares FLAIR DWI and conventional DWI in ischemic stroke of varying ages to assess the potential advantages of this technique.

Methods

We respectively analyzed 139 DWI studies in patients with ischemic stroke with and without FLAIR at varying time points ranging from hyperacute to chronic. ADC values were measured in each lesion, as well as in the contralateral normal side. Comparisons were made between the ADC values obtained from the DWI sequences with and without FLAIR for both the lesion and the normal contralateral side.

Results

The ADC measurements within the ischemic lesion were very similar on FLAIR DWI and conventional DWI for lesions less than 14 days old (p > 0.05), but were significantly decreased on FLAIR DWI for lesions between 15 and 30 days old and in lesions >31 days old (chronic stage) (p < 0.01). The contralateral ADC values were all significantly decreased on the FLAIR DWI sequence compared with conventional DWI (p < 0.01).

Conclusions

The application of an inversion pulse does not significantly affect the ADC values for early stage ischemic stroke (less than 14 days from symptom onset), but results in a more accurate relative ADC measurement by reducing the cerebrospinal fluid partial volume effects of the normal contralateral side. In addition, combined with the conventional DWI, FLAIR DWI may be helpful in determining the age of ischemic lesions.     

Age-related and zonal anatomical changes of apparent diffusion coefficient values in normal human prostatic tissues

PURPOSE: To identify age-related changes and differences in the diffusion of water molecules within the prostate, through diffusion-weighted imaging (DWI) of the prostate gland in healthy adult Japanese men. MATERIALS AND METHODS: A total of 114 healthy male volunteers (mean age, 55 years; range, 24-81 years) underwent DWI of the prostate with a single-shot echo-planar imaging (EPI) sequence using b-factors of 0 and 1000 seconds/mm(2). Apparent diffusion coefficient (ADC) values of six locations in the peripheral zone (PZ) and two locations in the central gland (CG) were measured and correlations between region and age were examined. RESULTS: ADC values measured within both PZ and CG regions of the prostate showed a uniform distribution, and no significant differences were found between evaluated regions. However, mean ADC values were 1.64 +/- 0.27 x 10(-3) mm(2)/second for PZ and 1.26 +/- 0.12 x 10(-3) mm(2)/second for CG, representing a significant difference. In addition, significant positive correlations were identified between ADC values for both PZ and CG regions and subject age (r = 0.526, P < 0.0001; r = 0.190, P = 0.0431, respectively). CONCLUSION: ADC values within both PZ and CG regions of the prostate increase with age, and this must be taken into consideration when using DWI in the diagnosis of prostate cancer.